bulletin_2_2013_industrial-data

RHI Bulletin >2>2013The Journal of Refractory Innovations
Industrial Edition
Novel Gas Purging System
for Copper Anode Furnaces
New Thrust Lock System for
Rotary Cement Kilns
Chrome Corundum
Applications in Glass
Melting Furnaces
Sulphur Recovery Unit

2 <
RHI Bulletin >2>2013The Journal of Refractory Innovations
RHI Bulletin 2/2013
Industrial Edition
Published by: RHI AG, Vienna, Austria
Chief Editor: Bernd Buchberger
Executive Editor: Markus Dietrich, Alfred Spanring
Technical Writer: Clare McFarlane
Proofreaders: Bernd Buchberger, Clare McFarlane
Project Manager: Ulla Kuttner
Photography, Graphics
and Production: Markus Kohlbacher, Christoph Brandner
Design and Typesetting: Universal Druckerei GmbH, Leoben, Austria
Printers: Universal Druckerei GmbH, Leoben, Austria
Contact: Ulla Kuttner
RHI AG, Technology Center
Magnesitstrasse 2
8700 Leoben, Austria
E-mail: ulla.kuttner@rhi-ag.com
Tel: +43 (0) 502 13-5323
Fax: +43 (0) 502 13-5237
www.rhi-ag.com
The products, processes, technologies, or tradenames in the
RHI Bulletin may be the subject of intellectual property rights
held by RHI AG or other companies.

> 3> 3
INTERSTOP Awarded Delivery of Stopper
Control System for the New Baosteel Steel
Plant in Zhanjiang
China >> Baosteel Group Corporation is one of the largest steel
producers in the world, with an installed capacity totalling 45 mil-
lion tonnes per annum. Currently, Baosteel is building a completely
new basic oxygen furnace plant in Zhanjiang (China), as part of a
strategy to concentrate production units and operate process tech-
nology that meets market requirements.
The steel plant will operate three BOFs with a nominal capacity
of 350 tonnes. As highly sophisticated steel grades (e.g., silicon
steels) are scheduled to be produced, converter slide gates for slag
retainment are foreseen. Furthermore, one ladle furnace and two
RH degassers are planned.
In the initial phase, with startup scheduled for the fourth quarter
of 2015, 2 x 2 strand slab casters from Siemens VAI Metals Tech-
nologies will be installed with an annual steel output of 6 million
tonnes. In the next stage, the existing 2 x 1 strand Danieli continu-
ous casting machines (CCMs) from Baosteel Luojing will be relo-
cated and revamped to a 1 x 2 strand CCM at Zhanjiang. After all
three CCMs are operational, the total output will reach 8.75 million
tonnes per annum in 2016.
Baosteel invited international bids for the entire stopper
control system to be installed initial on the 2 x 2 strand slab cast-
ers. The scope of equipment offered by RHI included stopper rods,
electrically actuated stopper drives, the newest generation of VUHZ
mould level sensors, an advanced argon management system
including data storage, and the process control system. A team
from INTERSTOP in Switzerland and Shanghai worked jointly on
the bid, convincing Baosteel of the technology leadership in this
field of flow control. As a result, on October 18, 2013, Stopinc AG
(Switzerland) was informed it had been awarded the contract.
Delivery of the equipment is scheduled for the third quarter of
2014.
TUNFLOW—The RHI Tundish
Flow Modifier
Since its market launch in 2010, RHI’s
impact pot and flow modifier for the
tundish has successfully entered 19 coun-
tries all over the world. Experienced
researchers and the use of CFD and water
modelling simulations are the basis for
RHI’s customer-orientated approach with
this product, enabling steel plants to make
the best of their existing conditions, such
as tundish geometry, by using the opti-
mum tailored flow modifier concept.
Under the brand name TUNFLOW, RHI
sold over 4000 pieces in 2012 and expects
total sales of more than 6000 pieces in
2013, with an ongoing trend for further
growth in the next years.
New Transport and Storage
Brochures Available
Austria >> Following frequent customer
requests, RHI created new bilingual
(German/English and English/Russian)
brochures concerning transport and stor-
age issues, with additional languages
planned. Containing state of the art three-
dimensional illustrations, they highlight
the main packaging types, labels, and
storage advice. Furthermore, an insight
into the undesirable hydration process is
provided, along with possible on-site
tests.
Due to different customer requirements,
the new brochures are available in Steel
and Industrial versions, both of which are
available on request from RHI Sales and
Technical Marketing personnel.
RHI Attends UNITECR 2013
Canada >> The 13th
Biennial Worldwide Congress on Refractories,
UNITECR’13, was held from September 10–13, 2013, in Victoria,
British Columbia.
More than 600 international participants were present, including
refractory producers, raw material suppliers, customers from vari-
ous industry segments, and academia. Considered the most impor-
tant refractory conference worldwide, it provides the opportunity
to discuss the latest trends in the sector of high-temperature mate-
rials.
RHI participated in various sessions, presenting topics including
zirconia characterization methods, the challenges for Western mag-
nesia-carbon brick manufacturers, and investigation of thermal
shock in lower slide gate plates. Additional papers focused on dif-
ferent destructive and nondistructive methods to characterize mag-
nesia and magnesia-chromite bricks, improved physical properties
of alumina-silica bricks using sol impregnation, and the perfor-
mance advantages provided by hybrid spinel technology in basic
bricks for cement rotary kiln applications. The latter topic is also
included in the first paper of this Bulletin (page 10).
Refractories Simply
Explained in the New RHI
Animation Video
Austria >> A new RHI video, titled
“What are Refractory Products?” pro-
vides a short animated explanation of
the importance, application, and produc-
tion of refractories. Available in both
English and German on the RHI website
(www.rhi-ag.com), it is designed to be
informative for nonexperts and high-
lights the indispensibility of refractories
for everyday life.
RHI worldwide

4 <4 <
RHI Clasil Receives IRMA
Award for Excellence
India >> At the Indian Refractory Mak-
ers Association’s (IRMA) 52nd
annual
general meeting, held on August 17,
2013, the IRMA Awards for Excellence in
2012–2013 were announced. RHI Clasil
Ltd., (India) received the accolade “Over-
all Excellence in Export Performance for
2012–2013” in the large scale sector. This
is the second consecutive year RHI Clasil
has been honoured with this award.
The IRMA was established in 1958 and
is the national organization representing
companies designing, engineering, and
installing refractories in India. Currently,
more that 70 refractory manufacturing
companies are members of the IRMA.
New Casting Sequence Record for RHI at
Outokumpu Stainless Alabama
USA >> Outokumpu Stainless USA (Calvert, Alabama) is a green-
field steel plant that produced its first heat on November 16, 2012.
Currently, RHI has a supply contract for 100% of the isostatically
pressed continuous casting refractory requirements.
On September 12, 2013, the first 8 heat sequence was success
fully cast with a RHI submerged entry nozzle (SEN), surpassing the
previous 6 heats. This achievement was recognized and celebrated
by the Outokumpu casting personnel, along with RHI.
The stainless steel grade was 304, in a mould width of 1260 mm,
with a total casting time of 499 minutes. The SEN (DELTEK
HX10Z98WX08), along with the ladle shroud (DELTEK A100) and
stopper rod (DELTEK A100D99N) were produced at the RHI Say-
brook plant (Ohio, USA).
An enormous amount of effort from the RHI and Outokumpu
team members contributed to this achievement, and additional
improvements are still possible.
TMS Annual Meeting in February 2014
USA >> The 143rd
TMS Annual Meeting and Exhibition will take
place at the San Diego Convention Center, California. More than
4000 of the world’s business leaders, engineers, scientists, and
other professionals in the materials field are expected at this event,
which is scheduled from February 16–20, 2014, and provides the
opportunity for an outstanding exchange of technical knowledge.
RHI will be presenting technical papers during the prestigious
EPD Symposium in honour of David G.C. Robertson—Celebrating
the Megascale—including a paper titled “Modelling and Compari-
son of Refractory Corrosion at RHI’s Technology Center“. RHI will
also participate in the 5th
International Symposium on High-Tem-
perature Metallurgical Processing. RHI personnel from numerous
departments look forward to seeing you at booth No. 229 to dis-
cuss any point of interest relating to the presented topics and other
refractory-related areas.
56th
International Colloquium on Refractories
2013
Germany >> The 56th
International Colloquium on Refractories,
held in Aachen from September 25–26, 2013, provided an impor-
tant opportunity to present current research topics as well as
develop and recruit the next generation of refractory engineers and
scientists. Diverse new ideas, with the focus on industrial applica-
tions, were introduced by European and international industries
and research institutes. RHI presented papers regarding basic
refractory wear in the nonferrous metals industry; an investigation
and verification of ultrasonic and resonant frequency measurement
methods for fired refractory products; and the importance, organi-
zation, and evaluation of interlaboratory tests.
Once again RHI had a booth in the exhibition area, providing a
meeting place for creative brainstorming and knowledge exchange.
Since a considerable number of delegates came from outside
Europe, this networking platform had an international character.
RHI Commissions Three
BOF Taphole Changing Units
at Tata Steel Jamshedpur
India >> Tata Steel is one of the largest
steel producers in India with an installed
capacity of 10 million tonnes per annum.
The plant has three BOF steel melting
shops designated LD#1 (2 x 165 tonnes),
LD#2 (3 x 165 tonnes), and LD#3 (2 x 165
tonnes). Whereas LD#1 and LD#2 have
been operating for a long time, LD#3
was only commissioned in 2011–2012.
In LD#1 and LD#3, the two vessel BOF
operation requires a high-efficiency tap-
hole exchange mechanism to ensure
maximum productivity is achieved. RHI
was approached by Tata Steel to assist
in this regard and after a detailed techni-
cal discussion it was finalized that RHI’s
Taphole Breakout Device (TBD) along
with ISOJET C type tapholes would be
the best possible solution to achieve the
desired taphole exchange time. As a
result, RHI received an order for three
TBD machines and the ISOJET C taphole
requirement for both shops.
RHI worked closely with Tata Steel and
within a period of 12 months all four
BOFs in LD#1 and LD#3 were converted
to the ISOJET C taphole system and the
three TBD machines were successfully
commissioned. The taphole exchange
time frame as well as the taphole life
achieved so far is in line with the cus-
tomer’s expectations.
RHI worldwide

> 5> 5
South America Hosts the Copper 2013
International Conference
Chile >> The 8th
Copper/Cobre 2013 conference took place from
December 1–4, 2013, at the CasaPiedra Convention Center in San-
tiago de Chile. More than 1000 delegates from 160 companies and
organizations participated at this very important meeting, which
has taken place every three years since 1987. RHI had a booth at
the exhibition and also presented five technical papers at the con-
ference—the world’s largest nonferrous metal meeting, with the
main focus on copper.
The presented papers focused on material characterization of
basic refractories, corrosion testing methods, and a scientific
journey through the area of wear mechanisms in the nonferrous
metal industry. The two additional topics: Novel gas purging tech-
nology for stationary and tilting copper anode furnaces (page 50)
and thermal shock resistant alumina-chromia brands (page 54) are
included in this edition of the Bulletin. For further information
regarding any of the presentations, please contact
nfm-marketing@rhi-ag.com
SIEMENS VAI Honours RHI
as a Highly Innovative
Supplier
Austria >> During an award ceremony in
Linz on November 6, 2013, plant manufac-
turer Siemens VAI honoured the perfor-
mances of its outstanding suppliers. RHI
was among seven finalists selected from
numerous international companies. The
Supplier Star was awarded for innovation
regarding the delivery and selection of
refractory materials for FAST, an opti-
mized and patented tapping system that
is integral in SIMETAL EAF Quantum.
The awards are presented on a biennial
basis to recognize its most outstanding
suppliers, since SIEMENS VAI considers
it essential to have strong and reliable
partners in order to be successful on the
global market.
This is the second occasion RHI has
won a Supplier Star award and underlines
the good cooperation between Siemens
VAI and RHI as well as confirms RHI’s
position as a competent and innovative
supplier of refractory materials.
Nucor Steel Texas Awards
Contract for INTERSTOP
Automatic Mould Level
System
USA >> Nucor Steel Texas, part of the
Bar Mill Group, recently awarded RHI a
contract for the INTERSTOP 13QC Auto-
matic Mould Level System. Five tundishes
will be converted along with twenty gates
for production of 350000 short tons of
round billets annually, and a possible
expansion to 1.1 million tons. Commis-
sioning is scheduled for the second quar-
ter of 2014.
50th
Anniversary of
ANKERHARTH Mixes
Austria >> In the last 50 years, ANKER-
HARTH has become the No. 1 hearth ram-
ming mix for electric arc furnaces on the
global market. To celebrate this success
story, all ANKERHARTH big bags from the
Breitenau and Hochfilzen plants will have
anniversary stickers in the coming
months. Further information regarding the
ANKERHARTH product range can be
found in the RHI Bulletin > 1 > 2013—Steel
Edition.
Application Instructions for Basic Mixes
Austria >> Following close collaboration between various
departments at RHI, the application instructions have been revised
and standardized for all grades in the current basic mix product
portfolio.
In contrast to shaped products that are delivered ready for instal-
lation, the correct processing of unshaped products at the custom-
er is an essential and often crucial step in order to achieve the
requested performance level. Therefore, for each grade all the
quality-relevant processing steps, from the right storage conditions
through to installation, are now described in tailor-made operating
instructions. These descriptions are as comprehensive as neces-
sary, while being as simple as possible. Additionally, pictograms
are included in all instructions, which highlight the most important
characteristics and provide hints for proper mix application. In the
future these pictograms should also enable users with reading dif-
ficulties to understand the main content of the instructions and
ensure correct utilization. As part of the project, the operating
instructions for nonbasic and basic mixes have also been
standardized.
RHI Achieves a Record Casting Sequence
at SDI Butler
USA >> Steel Dynamics, Inc., in Butler (Indiana) have operated
two thin slab casters since 1998, each with an annual capacity of
1.5 million tonnes. From this time, a major competitor had been
the sole supplier of submerged entry nozzles (SENs) to the plant.
As part of RHI’s ISO growth strategy, the Saybrook plant (Ohio,
USA) targeted SENs and stoppers at this customer. After extensive
trials, RHI won a share of the SEN supply in 2012. It had been rec-
ognized by SDI for some time that the SEN slag band wear rate
was better than the long-term supplier. Therefore, on August 18,
2013, SDI personnel had the confidence to run an RHI SEN on
boron grades for 18.5 hours, achieving 3.5 hours beyond the nor-
mal casting time. These grades are the sternest test of thin slab
SENs.

Total dedication throughout the year
RHI personnel provide a range
of refractory solutions

Season‘s greetings
from staff at the
Technology Center Leoben
www.rhi-ag.com

ANKRAL Q-Series
Pure innovation
setting the pace
RHI AG—Refractory competence for the cement industry
Sophisticated refractory products
Excellence
in Refractories
www.rhi-ag.com
hybrid spinel technology by RHI

> 9
Subscription Service
and Contributions
We encourage you, our customers and inter-
ested readers, to relay your comments, feed-
back, and suggestions to improve the publica-
tion quality using the contact details below.
Furthermore, to receive the RHI Bulletin free of
charge please e-mail or fax your details to the
Subscription Service using the form on the
back page.
E-mail: ulla.kuttner@rhi-ag.com
Phone: +43 (0) 502 13-5323
Fax: +43 (0) 502 13-5237
Contents
10 Hybrid Spinel Technology Provides
Performance Advances for Basic Cement
Rotary Kiln Bricks
13 New Sol-Bonded Product Members—
Gunning Experiences and Shotcasting
Applications
17 RHI Thrust Lock System for Cement
Rotary Kilns
20 Safety in the Mining Industry—A Value
25 Low Carbon Economy Roadmap for the
Ceramic Industry
27 Chrome Corundum: An Alternative to
Isostatically Pressed Products
31 Postmortem Studies of Standard Silica,
No-Lime Silica, and Fused Cast AZS from
Oxy-Fuel Fired Soda-Lime Glass Melting
Furnaces
36 Microstructural Analysis of Magnesia
Bricks Operating Under Altered Conditions
in the Regenerator Condensation Zone of
Glass Melting Furnaces
40 RHI US Ltd Provides Value-Added Services
to Environmental, Energy, and Chemical
Sectors in the USA
42 American Petroleum Institute Refractory
Installation Certification Programme
44 Determining Resistance to Abrasion at
Ambient Temperature—Improving
Comparability Between Laboratories
50 New Innovative Gas Purging System for
Stationary and Tilting Copper Anode
Furnaces
54 Thermal Shock Resistant Alumina-Chromia
Products for the Copper Industry
59 Thermomechanical Finite Element
Simulation of Heat-Up Processes in a
Lead Rotary Furnace
Editorial
A decade ago we launched the RHI Bulletin and over 200 articles
have been published describing innovative products and services
from RHI as well as broader refractory-related topics. Available in
both printed and digital format, it regularly communicates how
We lead the Industry. Everywhere. Anytime.
This edition contains a wide range of papers, principally focusing
on the cement, glass, and nonferrous metal industries. The first
paper describes how hybrid spinel technology in the ANKRAL
Q-series incorporates brick flexibility into magnesia bricks, which is
not only essential for lining mechanically critical areas but is highly
advantageous in the case of alkali salt infiltration. This is followed by
a description of the new sol-bonded monolithics that have been
developed for shotcasting and shotcreting applications, enabling
rapid and efficient installation of large amounts of material. Addition-
ally, the extended production programme to facilitate global access
to the sol-bonded products is highlighted. A newly designed retain-
ing system for the outlet zone in rotary kilns is the subject of the next
paper, illustrating how the RHI Thrust Lock System will significantly
improve refractory service life in this highly stressed kiln section.
Advances described for the glass industry include an economic
alternative to isostatically pressed chrome-containing material for
areas in glass furnaces that require high corrosion resistance. The
bonded alumina-chrome developed by RHI provides an additional
benefit of superior thermal shock resistance. Two further papers
describe postmortem studies that demonstrate the STELLA GNL
no-lime silica brand is advantageous for crown applications in oxy-
fuel fired glass furnaces and microstructural analysis of magnesia
bricks operating under altered conditions in the regenerator conden-
sation zone.
An innovative gas purging system for stationary and tilting copper
anode furnaces is introduced in the nonferrous section, as well as
thermal shock resistant alumina-chromia products for the copper
industry, and FEA modelling of a lead rotary furnace that resulted in
a modified lining design and improved furnace lifetime.
Additional papers in this edition describe the full service capability
now offered by RHI US Ltd., the American Petroleum Institute refrac-
tory installation programme that has been developed to improve
refractory reliability and service life, and an approach to increase the
reproducibility of material abrasion testing results. Furthermore, an
article regarding safety in the mining industry provides an insight
into this critical issue and the low carbon economy roadmap for the
ceramic industry is summarized in a paper that also includes the first
PRE results providing an average European carbon footprint for a
range of refractory products.
In closing I extend my gratitude to all the authors who kindly contrib-
uted to this edition and the editorial team for their dedication to this
publication, many of whom have been involved from its inception.
Yours sincerely
Bernd Buchberger
Corporate Research and Development
RHI AG
> 9

10 <
RHI Bulletin >2> 2013, pp. 10–12
Gerald Gelbmann, Roland Krischanitz and Susanne Jörg
Hybrid Spinel Technology Provides Performance
Advances for Basic Cement Rotary Kiln Bricks
Basic refractories used in cement rotary kiln applications are exposed to a complex mix of
simultaneously acting thermal, mechanical, and chemical stresses. This paper demonstrates
that incorporating brick flexibility into magnesia-based bricks is not only crucial for lining
mechanically critical areas, but it is also highly beneficial in the case of chemical attack
caused by alkali salt infiltration. The second issue is relevant in view of the steadily increasing
amount of alternative fuels fired in rotary kilns. Through the development of a new flexibiliz-
ing technology, this property has been significantly improved compared to magnesia spinel
bricks containing conventional magnesia-alumina spinel (MA spinel, MgAl2O4) for flexibiliza-
tion. The new approach based on a hybrid spinel technology has been implemented in the
Q-series brick brands: ANKRAL QF, ANKRAL Q1, ANKRAL Q2, and ANKRAL QE. With the
ANKRAL Q-series, RHI is able to offer solutions with outstanding thermomechanical behav-
iour even if significant alkali salt densification occurs.
Introduction
Cement rotary kiln refractories are exposed to severe
stresses originating from thermal, mechanical, and chemi-
cal loads. In particular, kiln rotation places basic refractory
materials under critical stresses because magnesia-based
bricks are comparatively brittle. Therefore, special additives
are used, so-called flexibilizing additives, to reduce the brit-
tleness in order to fulfil the high thermomechanical require-
ments in cement rotary kilns.
In addition to the thermomechanical stresses present in
rotary kilns, chemical load must also be considered, espe-
cially in view of the steadily increasing use of alternative
fuels. The infiltration of volatile components like K2O, SO3,
and Cl leads to two effects: Corrosion of the ceramic brick
bonding and thereby degeneration of the brick structure,
and a second no less critical effect, densification of the brick
structure by alkali salts that results in loss of thermome-
chanical flexibility.
While in the past chrome ore was used as a standard flexi-
bilizing concept, nowadays spinel group (AB2X4) minerals
are state of the art. These minerals have a lower thermal
expansion than magnesia, and the greater the thermal mis-
match compared to magnesia, the more effective the reduc-
tion in brittleness. The most commonly used minerals are
magnesia-alumina spinel, MgAl2O4 (MA spinel); iron-alu-
mina spinel, FeAl2O4 (hercynite); and manganese-alumina
spinel, MnAl2O4 (galaxite). The main focus of the research
performed was to develop, through the systematic use of
different spinels, high-performance bricks for cement rotary
kilns able to withstand high mechanical loads in combina-
tion with chemical stresses. An additional aim was to
reduce the loss of flexibility once the brick structure is den-
sified by alkali salts.
Spinel-Containing Magnesia Bricks
Two different brick types based on sintered synthetic high-
purity magnesia (MgO > 98 wt.%) and one type based on
sintered natural magnesia (MgO > 97 wt.%) were produced
on a pilot scale for the analyses. Type A was a magnesia
spinel brick, while types B and C were based on hybrid spi-
nels and different sintered magnesia grades (Table I). All the
brick types were fired at the same temperature.
Dynamic Young’s Modulus
Initially the dynamic Young’s modulus of all three materials
was determined to characterize the thermomechanical
behaviour. This investigation was performed by measuring
the ultrasonic velocity as a sample was heated from room
temperature to 1400 °C and as it cooled back to room tem-
perature [1].
The Young’s modulus or modulus of elasticity describes the
amount of stress required to create a defined, reversible
deformation in a material. It is also a characteristic of the
amount of stored elastic energy at this defined deformation
(i.e., a high Young’s modulus indicates a high amount of
stored elastic energy). The higher this value, the higher the
brittleness and the lower the thermal shock resistance of
the material. When the dynamic Young’s modulus of a pure
magnesia brick sample without flexiblizer was determined,
it showed a very brittle behaviour that slightly reduced with
increasing temperature and then increased back to the orig-
inal value as the sample cooled to room temperature (Fig-
ure 1). In comparison, the Young’s modulus was signifi-
cantly lower when MA spinel flexibilizer was present. Fur-
thermore, the temperature-dependent change of the
Young’s modulus was significantly different for the magne-
sia MA spinel sample compared to the pure magnesia
A B C
MgO 88.0 87.2 86.1
CaO 0.7 0.7 1.6
SiO2 0.3 0.3 0.8
Al2O3 10.5 9.1 9.0
Fe2O3 0.5 2.7 2.5
Table I. Chemical composition (wt.%) of the magnesia-based
brick types containing different spinel concepts.

RHI Bulletin >2> 2013
> 11
refractory (see Figure 1). At room temperature the Young’s
modulus was low, slightly increasing as the sample was
heated up. Upon cooling the Young’s modulus significantly
increased until it reached a maximum at approximately
1000–1100 °C. With further cooling the Young’s modulus
returned to the original value at ambient temperature. The
increase during cooling down was caused by the thermal
misfit between magnesia and flexibilizer.
The type B material containing hybrid spinel showed a
lower overall dynamic Young’s modulus compared to the
conventional magnesia MA spinel brick sample (type A)
(Figure 2), as did type C. In addition, not only was the
Young’s modulus at a lower level during the entire heat-up
procedure, which would lead to a lower risk of spalling at
the hot face during heat-up in a cement rotary kiln, the
increase during cooling was also much less. Since the brick
type B did not show such a significant increase in brittle-
ness during cooling down, the danger of spalling at the hot
face during kiln cooling would be considerably reduced.
Wedge Splitting Test
The wedge splitting test enables the mechanical fracture
behaviour of refractory materials to be examined and can
be performed at temperatures up to 1500 °C [2]. The spe-
cific fracture energy, Gf, is determined by evaluating the
Table II. Mass increase (Δmass) and relative Young’s modulus of
the three brick types before and after chemical loading. E0 is the
relative Young’s modulus prior to chemical loading compared to
a noninfiltrated magnesia MA spinel sample and E1 denotes the
relative Young’s modulus after chemical loading compared to a
noninfiltrated magnesia MA spinel sample.
Type Δmass (%) E0 (%) E1 (%)
A 5.7 100 118
B 5 65 97
C 5.9 64 95
load/displacement curve during stable crack propagation
and indicates a material’s ability to absorb thermomechani-
cal stress. To provide a more detailed understanding of the
different brick types’ thermomechanical properties, wedge
splitting tests were performed at 1100 °C, the temperature at
which the most brittle behaviour was determined from the
dynamic Young’s modulus. Brick type B showed a signifi-
cantly higher Gf (area under the graph) than brick type A
(Figure 3). The maximum vertical force occurred at a higher
displacement compared to the brick type A and after passing
the maximum, the vertical force remained at a higher level,
which indicates a higher resistance against crack propaga-
tion. Brick type C showed similar results to brick type B.
In summary, both brick types containing hybrid spinels
showed a significantly lower dynamic Young’s modulus and
a very high resistance against crack propagation compared
to the magnesia MA spinel brick. These thermomechanical
properties are advantageous in high mechanically loaded
rotary kilns.
Thermomechanical Properties of
Infiltrated Bricks
In order to examine the thermomechanical behaviour under
chemical load, further laboratory investigations were per-
formed. Crucibles were prepared from the three different
brick types. The crucibles were filled with KHSO4, heated to
950 °C, and held for 24 hours. The dynamic Young’s modulus
of the crucible material was measured ultrasonically before
and after the materials had been subject to chemical loading.
As expected the noninfiltrated crucibles with hybrid spinel
technology showed a lower Young’s modulus compared to
noninfiltrated magnesia MA material (Table II). However, the
Figure 1. Dynamic Young’s modulus of brittle (pure magnesia)
and flexible (magnesia MA spinel) brick samples.
Temperature [°C]
800
700
600
500
400
300
200
100
0
DynamicYoung’smodulus[GPa]
5000 1000 1500
Pure magnesia brick—brittle
Magnesia brick with flexibilizer—low brittleness
Figure 2. Dynamic Young’s modulus of magnesia MA spinel (A)
and magnesia hybrid spinel (B) brick samples.
Temperature [°C]
800
700
600
500
400
300
200
100
0
Young’smodulus[GPa]
5000 1000 1500
n A
n B
Figure 3. Wedge splitting test performed on magnesia MA spinel
and magnesia hybrid spinel brick samples at 1100 °C.
900
600
300
0
Verticalforce[N]
0 1 2 3 4 5 6 7 8 9 10
Displacement [mm]
n A
n B

12 <
heavily infiltrated crucibles with hybrid spinel technology
also had a lower Young’s modulus than the nonchemically
loaded magnesia MA spinel material (Figure 4). This result
justifies the expectation that magnesia hybrid spinel bricks
with outstanding thermomechanical properties provide
excellent service lifetimes in high chemically loaded cement
rotary kilns. Since magnesia hybrid spinel bricks strongly
infiltrated with alkali salts are not as brittle as noninfiltrated
standard magnesia MA spinel bricks, the sensitivity of den-
sified bricks containing the hybrid spinel technology to ther-
mal shock and thereby spalling at the hot face is signifi-
cantly reduced.
The Q-Series—A Complete Product Range
Based on research results and experience gained from suc-
cessful installations and brick performances, the product
range containing the hybrid spinel technology has been
extended and a comprehensive new product line is avail
able—the Q-series.
References
[1] Triessnig, A., Studnicka, H. and Prietl, T. Determination of Thermo-Mechanical Properties at the RHI Refractories Technology Center Leoben.
RHI Bulletin. 2006, No.1, 33–37.
[2] Tschegg, E., Fendt, K., Manhart, C. and Harmuth, H. Fracture Properties of Refractory Materials Under Uniaxial and Biaxial Loading. RHI Bulletin.
2010, No. 1, 40–47.
[3] Jörg, S., Gelbmann, G., Krischanitz, R. and Fritsch, P. ANKRAL QF—A New Brick to Combat Tyre Stresses. RHI Bulletin. 2010, No. 1, 8–12.
[4] Jörg, S., Gelbmann, G. and Krischanitz, R. ANKRAL Q2—An Innovative Solution for Transition Zones. RHI Bulletin. 2012, No. 2, 8–11.
Authors
Gerald Gelbmann, RHI AG, Technology Center, Leoben, Austria.
Roland Krischanitz, RHI AG, Industrial Division, Vienna, Austria.
Susanne Jörg, RHI AG, Technology Center, Leoben, Austria.
Corresponding author: Roland Krischanitz, roland.krischanitz@rhi-ag.com
Established several years ago, the first member of the
Q-series, ANKRAL QF, is the top grade in the series. It has
demonstrated outstanding performance in critical kiln areas,
for example tyre sections subjected to alkali salt attack [3].
In many cases the lifetime of previous installations has
been increased significantly, in some cases even more than
doubled. The experience gained from in service results with
ANKRAL QF was the starting point for further product
developments. For example, the hybrid spinel technology
was adapted for use with RHI’s own sintered magnesia
resources. The result was ANKRAL Q2, a product with an
unparalleled price/performance ratio. This RHI brand also
has a long list of successful references [4]. As installation
results have shown, ANKRAL Q2 is able to successfully
compete with high cost competitor products and also offers
solutions for highly loaded transition zones in alternative
fuel fired kilns.
ANKRAL Q1 has been operational in various kilns since the
beginning of 2013 and supplements the high-grade Q-series
product range, also focusing on highly loaded transition
zones in alternative fuel fired kilns.
Additionally, the Q-series offers a solution for the sintering
zone. With ANKRAL QE RHI has developed a hybrid spinel
brick based on iron-rich sintered magnesia. This brand pro-
motes the superior coating adherence desired for applica-
tions in the central burning zone with the outstanding flexi-
bility of the Q-series. ANKRAL QE comprises an additional
novel technology enabling excellent refractoriness under
load (i.e., T0.5 = 1660 °C). Accordingly, ANKRAL QE can be
recommended not only for severely stressed central burn-
ing zones but also for transition zones.
With the various different brands currently available in the
Q-series, the most appropriate brick for a particular applica-
tion and operating conditions can be selected. This provides
cement customers with outstanding refractory performance
for the range of conditions in the basic lining zone at a low
investment cost.
Figure 4. Comparison of the relative Young’s modulus of
noninfiltrated and chemically loaded magnesia MA spinel
samples and magnesia hybrid spinel samples.
Relative mass increase during corroision test [%]
125
115
105
95
85
75
65
55
RelativeYoung’smodulus[%]
0.0 2.0 4.0 6.0 8.0
n A
n B
n C

> 13
René von der Heyde, Roland Krischanitz and Miloš Blajs
New Sol-Bonded Product Members—Gunning
Experiences and Shotcasting Applications
Very different types of sol-bonded monolithic refractories have been introduced and described
in past Industrial [1–3] and Steel [4,5] RHI Bulletins. These articles highlighted the diverse
application methods, industries, and customer-orientated research and development activities
at RHI regarding the sol-bonded product range. Particularly in the cement industry, these prod-
ucts have earned a very good reputation in the last years [6]. This paper presents, along with
impressive service performances of existing products, new application techniques available
using shotcasting (pumping) and shotcreting (wet gunning), which were developed in close
cooperation with an installation company and customers. Shotcasting is highly sophisticated
and enables very large amounts of material to be installed in a very short time frame with low
manpower. The first recent application using this technique to install more than 100 tonnes of
material at a Swiss cement plant is described as well as a smaller installation in Germany.
Introduction
The sol-bonded castables have been previously described
in detail in the RHI Bulletin [1–5]. The key features are easy
installation, no predrying, rapid and simple heat-up, high
application temperatures, and superior physical and chemi-
cal properties throughout the complete product group. After
very good results with old stored material, the recom-
mended shelf life of COMPAC SOL and CARSIT SOL prod-
ucts was recently increased to 18 months (previously 12
months), which provides customers, particularly in the case
of long-term planning, more possibilities regarding project
stock management. Currently, the sol-bonded materials
have a shelf life of more than 200% compared to common
low-cement castables and a very impressive 400% longer
storage life in comparison to other quick drying monolithics
available on the market.
Driven by continued increasing sales in the cement and
lime, steel, and environmental, energy, and chemical indus-
tries, the volume of sol-bonded alumina monolithic prod-
ucts sold, for the core brands COMPAC SOL, CARSIT SOL,
and COMPAC ROX, has risen by almost 170% compared to
2012 [3]. This continuous trend places these materials
among the fastest developing product group for RHI.
With sales and applications growing in all industries, not
only the actual tonnage sold is evolving fast, the product
portfolio is also rapidly developing. With more and more
customers experiencing the wide range of advantages pro-
vided by these products, including installation ease, drying
out and performance advantages, the pressure on competi-
tors in the market is rising. RHI is committed to retaining
this leading role and further extending market share
through new research and development activities, for
example the gunning advances described in this paper.
Sol-Gunning Experiences
Particularly the dry gunning products have had a very posi-
tive market impact. Comparing the period from Q3/2011–
Q2/2012 with Q3/2012–Q2/2013, sales of COMPAC SOL and
CARSIT SOL gunning mixes grew by more than 300%. The
gunning mixes are indicated in the brand nomenclature by G,
for example COMPAC SOL F53G-6. The chemical composi-
tion and material properties of the current sol-bonded gun-
ning and shotcreting product range are detailed in Table I.
To date, no competitor can offer fast drying materials for
gunning applications. In the past 12 months, sol-bonded
dry gunning materials were installed for example in Ger-
many, France, Ireland, Italy, the United Kingdom, Switzer-
land, India, and Luxembourg, mainly in the cement and
lime industries.
The first sol-bonded dry gunning material installations were
carried out at the beginning of 2011 and were described in
detail in the last Industrial RHI Bulletin [3]. An installation in
the roof and sidewall of a cooler in Germany provides a
very good example of the extraordinary performance dem-
onstrated by sol-bonded gunning materials. During the
installation one roof field was installed with a competitor
cement-bonded gunning material. The two different cast
ables can be easily distinguished by their colour in Figures
1–4, since the competitor cement-bonded gunning castable
appears more orange in colour. After one year (March 2012)
there was no major difference in the appearance of the two
materials (see Figures 1 and 2). However, after the second
year in service (February 2013), significant wear was
observed with the cement-bonded gunning castable (see
Figures 3 and 4), whereas CARSIT SOL F10G-6 was still in
very good condition. This result is even more convincing if
it is taken into account that the sol-bonded material was
based on fireclay whereas the conventional gunning mate-
rial had a mullitic raw material base. Both monolithics con-
tained approximately 10 wt.% silicon carbide.
Sol-Bonded Shotcreting
Dry gunning (i.e., torcreting or guniting) is a well-known
and commonly used installation method for fast turnaround
repairs. It is very rapid, flexible, and cheap in terms of
machinery demand. However, there are further gunning
methods that exist for installing large amounts of monolith-
ics that can now also be used for sol-bonded products,
namely shotcasting and shotcreting. Whilst torcreting
enables 1–2 tonnes of monolithic to be installed per hour,
using shotcasting 10 tonnes per hour can be achieved

14 <
Brand Al2O3 SiO2 Fe2O3 SiC CCS (N/mm2
) LTE ATL SL Raw materials Additional information
(wt.%) (wt.%) (wt.%) (wt.%) 110 °C 1000 °C 1000 °C (°C) (months)
(%)
COMPAC SOL F53G-6 50.0 47.0 0.7 - 45 45 0.55 1570 18 Dense fire clay, low iron
COMPAC SOL M64G-6 61.0 34.0 0.7 - 55 65 0.55 1670 18 Mullite
COMPAC SOL S64G-6 63.0 36.0 0.5 - 55 60 0.55 1670 18 Andalusite
COMPAC SOL FS99-3 1.5 98.0 0.2 - 20 30 0.00 1600 18 Fused silica
COMPAC SHOT FS99-3 0.2 99.5 0.1 - 12 25 0.00 1650 18 Fused silica Shotcreting, hot repair
CARSIT SHOT F30SB-6 39.0 30.0 0.6 30 63 75 0.55 1550 18 Dense fire clay, low iron/SiC Shotcreting
CARSIT SHOT M10SB-6 58.0 28.0 0.9 10 55 65 0.55 1650 18 Mullite/SiC Shotcreting
CARSIT SOL F10G-6 45.0 42.0 0.7 10 45 50 0.55 1550 18 Dense fire clay, low iron/SiC
CARSIT SOL F30G-6 38.0 31.0 0.7 30 45 45 0.55 1550 18 Dense fire clay, low iron/SiC
CARSIT SOL M10G-6 57.0 30.0 0.7 10 55 65 0.55 1650 18 Mullite/SiC
CARSIT SOL M30G-6 44.0 20.0 0.7 30 65 75 0.55 1580 18 Mullite/SiC
CARSIT SOL S10G-6 60.0 23.0 0.7 10 55 55 0.55 1650 18 Andalusite/SiC
CARSIT SOL S30G-6 44.0 22.0 0.7 30 55 55 0.55 1580 18 Andalusite/SiC
Table I. Product range of sol-bonded gunning and shotcreting mixes for the cement industry. Abbreviations include cold crushing
strength (CCS), linear thermal expansion (LTE), application temperature limit (ATL), and shelf life (SL).
Figure 4. Cooler roof section in Figure 2 after 2 years. The
anchoring was completely exposed in the orange coloured
cement-bonded material in the foreground and material loss had
occurred due to significant crack formation.
Figure 3. Cooler roof section in Figure 1 after 2 years in opera-
tion. The orange coloured cement-bonded material in the back-
ground showed heavy wear.
Figure 2. Reverse view of the cooler roof section in Figure 1.
Both gunned materials looked very similar in terms of wear after
1 year and the performance was considered equal by the cus-
tomer at this time.
Figure 1. Cooler roof in a German cement plant 1 year after
installation. The darker orange field in the background was lined
with a competitor’s conventional cement-bonded gunning mate-
rial. The other areas were lined with CARSIT SOL F10G-6.

> 15
easily. Shotcasting is a wet gunning method using adapted
vibration castables. It involves mixing the monolithic with
the required amount of liquid in a paddle or compulsory
mixer, pumping the wet material via double piston pumps to
the application area, and finally gunning with the use of a
small amount of compressed air and an accelerating liquid.
For shotcasting applications, the well-known RHI sol-bonded
vibration castables were slightly adapted to improve their
pumping properties—mainly to reduce friction in the pipes
and hoses. In addition, it was necessary to develop a com-
pletely new accelerating liquid, since the sodium silicate
solution (DIKASIL K) commonly used for cement-bonded
materials does not work with the cement-free bonding sys-
tem. As it is very effective, only a few litres of the newly
developed DIMASIL SB-LIQUID accelerator are needed per
tonne of shotcasting mix.
To fulfil the very tight development schedule, ensure optimal
workability, and to profit from the experience of an installa-
tion company, RHI worked closely together with Moeller
Feuerfesttechnik GmbH & Co. KG (Germany). Moeller was
very interested in this project because it sees great potential
in the sol-bonding features, particularly the short heat-up
period. The trials included tests with different pumps, a real-
istic gunning environment, including overhead gunning and
anchoring, as well as sample preparation to examine the
physical properties after installation (Figures 5 and 6).
Development during the 4 trial days at Lemgo (Moeller main
yard) and the RHI Urmitz plant is a very good example of the
successful collaboration between a refractory producer and
an experienced installation company to create a new
Figure 8. Shotcreting application of CARSIT SHOT M10SB-6 in a
cooler area at a German cement plant in spring 2013.
Figure 7. Kiln hood (roof) gunned with CARSIT SHOT M10SB-6
at a Swiss cement plant in spring 2013.
Figure 6. Shotcreting trial at Lemgo showing overhead gunned
panels. The lower left section generated a gunned sample for
further testing.
Figure 5. Machinery and setup for a shotcreting trial with the
German installation company Moeller Feuerfesttechnik in 2013
at their main yard in Lemgo.
product. In fact two products were created containing silicon
carbide, CARSIT SHOT M10SB-6 and CARSIT SHOT F30SB-6.
The acronym SB in the brand name indicates sol-bonded and
distinguishes these products from the conventional cement-
bonded brands.
Initially the cooperation with Moeller resulted in the installa-
tion of more than 100 tonnes of CARSIT SHOT M10SB-6 and
CARSIT SHOT F30SB-6 for a Swiss cement plant repair (i.e.,
cooler, kiln hood, nose zone, and inlet chamber area) in spring
2013 (Figure 7). A few weeks later a further cooler repair was
carried out in a German cement plant (Figure 8) by Moeller.
Sol News—Recent Developments
In the last years, the focus for sol-bonded castables was
mostly on Europe, with a more recent extension of the
demand worldwide. Therefore, whilst virtually all sol-bonded
castables were originally produced in Urmitz (Germany),
RHI’s largest alumina monolithic production plant, now a
selection of sol-bonded products are also available from RHI
production sites in India, Canada as well as Mexico, facilitat-
ing access to these sophisticated products for customers
globally.
North and South America
After the first excellent results with sol-bonded materials in
North and South America delivered from Europe, production
of selected castables from the sol-bonded product range was
extended to the RHI plants in Tlalnepantla (Mexico) and Burl-
ington (Canada). In addition, products for torcreting applica-
tions are in preparation (Figures 9 and 10) and will be avail
able by the end of 2013.

16 <
Asia-Pacific
For the last two years, sol-bonded materials for casting
applications have been available from the RHI joint venture
Clasil plant in Visakhapatnam (India), mainly serving the
Asia-Pacific market. As a result of the reported excellent
performances of CARSIT SOL M10-5 V from cement cus-
tomers in Taiwan (i.e., nose zone) and New Zealand (i.e.,
burner pipe), in which the service life of various units was
increased significantly, demand for such innovative solu-
tions has risen. Therefore, the development of gunning
materials to be produced at Clasil is currently underway
and the first products will be available by the end of 2013.
Conclusions and Outlook
The first dry gunning sol-bonded installations and initial
results were presented a year ago [3]. Now longer term
results are available that further demonstrate the advan-
tages of these gunning mixes that no other refractory sup-
plier can currently offer. Not only regarding installation, but
also in terms of performance, they show significant advan-
tages and more and more customers are benefiting from
these types of materials.
The very successful sol-bonded monolithics were recently
adapted for application using shotcreting technology and
the initial installations have been very successful. If past
experiences are taken as a guide, these applications will
also show excellent performance and doubtless meet cus-
tomer expectations.
Trials with sol-bonded monolithics started only a number
of years ago with a few tonnes of cast material installed in
German cement plants. Since this time sol-bonded cast
ables have virtually developed into the standard lining
materials at numerous cement plants, not only in areas that
are difficult to dry and heat-up, but also for applications
with severe operating conditions in terms of alkali attack,
mechanical and thermal load, as well as thermal shock.
Since it is only a relatively short period of time since the
market introduction of the sol-bonded products it is difficult
to determine their eventual success; however, indications
are they will way exceed initial expectations in the future.
The sol-bonding technology is still under development,
with further improvements ongoing and the next promis-
ing technology already in sight. The so-called mullite-
bonded castables [5], which are also cement-free cast
ables, represent a further advance in the sol-bonded
mixes. The unique matrix design enables outstanding
material properties to be realized. The first products have
already proven very successful for electric arc furnace
roofs in the steel industry. In view of the high application
temperatures, this is also a promising product for the most
severe operating conditions in the cement industry, for
example the burner tip.
References
[1] Blajs, M., von der Heyde, R., Fritsch, P. and Krischanitz, R. COMPAC SOL—The New Generation of Easy, Safe, and Fast Heat-Up No Cement
Castables. RHI Bulletin. 2010, No. 1, 13–17.
[2] Fritsch, P., von der Heyde, R. and Krischanitz, R. COMPAC SOL—Operational Experiences With the Easy, Fast Heat-Up No Cement Castable.
RHI Bulletin. 2011, No. 2, 42–45.
[3] von der Heyde, R., Krischanitz, R., Hall, D. and Zingraf, E. COMPAC SOL—The Success Story Continues With Gunning Mixes and New Product
Developments. RHI Bulletin. 2012, No. 2, 12–16.
[4] Schütz, J., Maranitsch, A. and Blajs, M. New Oxycarbide Refractory Products Demonstrate Outstanding Properties—First Practical Results.
RHI Bulletin. 2012, No 1, 16–19.
[5] Hochegger, M., Blajs, M., Nonnen, B. and Zottler, P. First Practical Results With COMPAC SOL A100S-15—A High-End Sol-Bonded Castable
Designed for EAF Deltas. RHI Bulletin. 2013, No. 1, 14–19.
[6] von der Heyde, R., Taha, H. and Sadek, W. The Keys to Improvement. World Cement. 2013, 44, No. 8, 73–76.
Authors
René von der Heyde, RHI AG, Industrial Division, Mülheim-Kärlich, Germany.
Roland Krischanitz, RHI AG, Industrial Division, Vienna, Austria.
Miloš Blajs, RHI AG, Technology Center, Leoben, Austria.
Corresponding author: Roland Krischanitz, roland.krischanitz@rhi-ag.com
Figure 9. First sol-bonded gunning trial at the RHI Tlalnepantla
plant (Mexico) in April 2013.
Figure 10. Gunning equipment at the RHI Tlalnepantla plant
(Mexico), including an Allentown pressure vessel gunning
machine.

> 17
Andreas Wiry and Hans Ulrich Marshall
RHI Thrust Lock System for Cement Rotary Kilns
The permanent refractory lining problems in the outlet zone of many rotary kilns need to be
tackled with the highest priority. Therefore, a specific project was initiated by RHI to evaluate
prevailing wear mechanisms as well as the strengths and limitations of existing designs. The
outcome of this project is a newly designed retaining concept, called the RHI Thrust Lock
System, which will significantly improve the refractory lining service life in this highly
stressed kiln section. The design differences and targeted advantages compared to existing
concepts are highlighted in this paper.
Introduction
The specific topic of excessive thermomechanical stresses
at the rotary kiln outlet was the focus of a previous RHI Bul-
letin article [1]. Despite numerous different lining designs
and refractory materials installed and tested in the past
(e.g., magnesia and SiC bricks, castables, and preshaped
blocks), until now no comprehensive solution has been
available to solve all the severe lining problems that occur
in the kiln outlet zone (Figure 1).
Due to the excessive axial lining thrust of modern high-per-
formance kilns and the resulting thermomechanically over-
stressed lining, conventional designs, namely brick and/or
castable lining combined with rectangular retaining rings
(Figure 2), often do not achieve an acceptable service life or
stop the axial lining thrust entirely.
Figure 3. Veitscher-Magotteaux system (four steps).
Figure 2. Rectangular retaining ring design.
Figure 1. Destroyed brick lining at the retaining ring of a rotary kiln.
The Veitscher-Magotteaux system [2] (Figure 3) was the
first, but also the latest design, offering considerable
improvements. However, under excessive stress and unfa-
vourable conditions even this conical multistep retaining
ring system sometimes does not perform satisfactorily.
The central limitation of this design is the relatively small
inclination angle of the metallic retaining segments, which
is only 20°. Due to the prevailing high temperatures, lim-
ited heat resistance, and low mechanical strength of the
metallic honeycomb segments at higher temperatures,
the height of these metallic segments is restricted to about
70 mm. As a result of various operating conditions, for
example frequent shutdowns, ovality, and kiln shell defor-
mation, the special bricks installed at the segments can
override (Figure 4) causing force transmission to the outlet
segments.
Figure 4. Veitscher-Magotteaux system showing a 40 mm brick
override (arrows) in the direction of the kiln outlet.

18 <
RHI Thrust Lock System
The challenging target was to design a new system that
would provide additional benefits compared to already
existing concepts as well as the possibility to upgrade cur-
rent retaining designs. Instead of the common brick and
rectangular retaining ring design, a special skew brick set is
used in the RHI Thrust Lock System (Figure 5). Due to the
skew brick inclination (>> 20°), the contact face between
retaining elements and brick lining is much higher and
therefore the resulting contact pressure is considerably
reduced. In addition, the axial lining thrust is diverted into
radial and circumferential forces and consequently mechan-
ical stress in the bricks is further reduced.
Using the Abaqus, Version 6.12, finite element method
(FEM) program, three-dimensional models were created to
compare the load profiles and stress centres generated with
the Veitsch-Magottaeux system (20°), a common rectangu-
lar retaining ring design, and the new RHI Thrust Lock Sys-
tem (Figure 6).
The simulated brick movement and load distribution with
the Veitsch-Magotteaux system, under excessive load con-
ditions, are shown in Figure 6a. The other models demon-
strate that while the mechanical stress generated with the
common brick and rectangular retaining ring design (Figure
6b) can easily exceed the brick crushing strength and cause
the well-known brick damage (e.g., crack formation and
crushed bricks) associated with this system, the maximum
axial stress level with the Thrust Lock System is reduced by
at least 30%. An inclination of 40° was selected for the RHI
Thrust Lock System. In the model a homogeneous load dis-
tribution over the entire contact face of bricks was visible
(Figure 6c). The slight brick override can be compensated
with an expansion joint.
In spite of the favourable load reduction with this new sys-
tem, the thrust bearing bricks are highly stressed and there-
fore particular material characteristics are required to with-
stand the complex thermomechanical load conditions.
Based on the knowledge gained during development of the
unique ANKRAL Q-series technology, focused on outstand-
ing structural flexibility combined with high mechanical
strength at high temperatures (see page 10), a new top
Figure 6. Three-dimensional FEM models of the (a) Veitsch-
Magotteaux system (one step 20°), (b) common brick and rectan-
gular retaining ring design, and (c) RHI Thrust Lock System
(skew brick 40°). Dark green indicates tensile stresses and light
green to dark red depicts the increasing compressive stresses.
Figure 5. New RHI Thrust Lock System installed at a retaining
ring, comprising special skew brick sets (cream and brown) and
an expansion joint (white).
brand termed ANKRAL TLS was created for this special
application. Moreover, due to the raw material basis com-
prising the purest sintered synthetic magnesia and a special
spinel concept, ANKRAL TLS offers excellent resistance
against corrosion and clinker melt infiltration. Depending
on the installation position and working conditions, high-
alumina bricks or SiC bricks can also be used.
Continuing the basic RHI Thrust Lock System idea, a slightly
modified skew brick set (Figure 7) can be installed mid-kiln,
directly in front of an outlet segment, or additionally as part
of an existing Veitsch-Magotteaux system.
(c)
(b)
(a)

> 19
Figure 7. New RHI Thrust Lock System installed mid-kiln.
References
[1] Marschall, H.U. and Wiry, A. Computer-Aided Thermo-Mechanical Stress Modelling of Different Rotary Kiln Outlet Designs. RHI Bulletin. 2004,
No. 2, 12–16.
[2] Landthaler, A. Drehrohrofen. German Patent DE 2643412 C3, 1987.
Authors
Andreas Wiry, RHI AG, Industrial Division, Vienna, Austria.
Hans Ulrich Marschall, RHI AG, Technology Center, Leoben, Austria.
Corresponding author: Andreas Wiry, andreas.wiry@rhi-ag.com
Conclusion
After decades of struggling to cope with lining problems in
the outlet zone, RHI is able to provide a promising concept
applicable for all rotary kilns.
The new RHI Thrust Lock System offers the following
advantages:
>> Lower mechanical stress in load bearing bricks, retain-
ing rings, and outlet segments.
>> Modifiable inclination angle (20–80°) of the skew brick
set.
>> High heat resistance (>> 1000 °C).
>> Universally applicable at the outlet and mid-kiln region.
>> Installation as a single or multistep concept.
>> Easily combined with all existing retaining designs.
>> Considerable cost savings for the refractory lining.
>> Higher kiln availability.
>> Easy installation procedure.
>> Shorter downtime in the case of relining.
The first trials are planned for the second half of 2013. Tech-
nical support, investigation of current wear mechanisms,
process analysis, and installation supervision will be pro-
vided by RHI’s experts.
A patent application for the new RHI Thrust Lock System
has been filed.

20 <
Thomas Drnek
Safety in the Mining Industry—A Value
Introduction
Safety is a value and must be handled as such in the mining
industry. It is also the most important issue in the mining
business. However, this sector has an image problem
because mining is considered to be very dangerous by the
general public. To examine the actual situation and recent
developments, data published regarding mining safety was
analysed and the current status assessed. In addition, this
enabled the question of what future provisions can be made
to improve the situation to be considered. The safety data
available for large mining companies was collected and ana-
lysed as well as reporting practices and the situation in dif-
ferent mining countries and regions. Since experience and
technological advances are paramount to improve safety, the
current training and education opportunities available for
mining personnel in Austria were also examined.
Injuries and Fatalities in Large Mining
Companies
The safety situation was analysed for the large mining com-
panies Rio Tinto, Anglo American, and BHP Billiton. The
information was obtained from both annual reports and sus-
tainability reports published by these corporations [1]. The
figures presented are the lost time injury frequency rate
(LTIFR) (i.e., lost time injuries per 2 x 105
hours) (Figure 1)
and absolute number of fatalities (Figure 2). In general, the
data and reports were easily accessible (via the internet)
and show that these companies are working very hard to
improve safety issues. For example, analysis of the trends
revealed not only very low LTIFR values (i.e., 0.4–1.1 LTIFR/
2 x 105
working hours) for these three mining corporations,
but also a continuous improvement in this area.
The data regarding fatalities does not indicate such a strin-
gent development for all three companies. While the
improvement at Anglo American shows a very significant
two-thirds reduction over 5 years, decreasing from close to 45
to around 15 fatalities, the values for Rio Tinto peaked in 2008
due to a helicopter crash in which 10 exploration crew died.
Excluding this accident, the figures for Rio Tinto and BHP Bil-
liton are in the region of 5 fatalities per year.
The large mining companies examined in the analysis have a
very good reporting standard, as proposed by the Interna-
tional Council on Mining and Metals (ICMM), London. In the
last years, these companies achieved significant improve-
ments regarding the injury frequency rates, and in the case
of Anglo American the number of fatalities also decreased.
The question that arises from these figures is what has
caused this trend? The simple answer is that safety has
become the most important job for board members; they
have taken personal responsibility for the issue. In addition,
policies have been established and executed, for example
the Occupational Health and Safety Advisory Services
(OHSAS) standard 18001, which provides a very useful way
to monitor, measure, and improve safety and health in the
workplace.
Safety in a Major Mining Country: Republic
of South Africa
The situation in the Republic of South Africa’s mining sector
is very well highlighted in the 2011 and 2012 annual reports
published by the Chamber of Mines of South Africa [2,3],
where an entire chapter is dedicated to this topic. Particularly
remarkable is the significant reduction in fatalities over the
last 10 years (Figure 3). One reason for this trend is that the
Chamber together with mining companies—for example
Anglo American is a major player in the South African min-
ing industry—has set target values for the reduction of fatali-
ties, as well as other milestones regarding health and safety
in the South African mining sector.
In summary, the significant improvements realized in South
Africa are due to the Chamber of Mines of South Africa being
very active in the area of safety, with the mining industry acting
as the most important supporting factor. In recent years multi-
ple aims have been defined, very positive progress has been
achieved, and results are reported on a regular basis [2,3].
Figure 1. Annual injury frequency rates for three large mining
companies [1].
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Losttimeinjuries/2x105
workinghours
2006 2007 2008 2009 2010 2011
Year
n BHP Billiton
n Rio Tinto
n Anglo American
50
45
40
35
30
25
20
15
10
5
0
Absolutenumbers
2005 2006 2007 2008 2009 2010 2011
Year
n BHP Billiton
n Rio Tinto
n Anglo American
Figure 2. Annual fatalities in three large mining companies [1].

> 21
Safety in an Another Major Mining Country:
USA
When the situation in the USA was examined, the first sig-
nificant observation was the excellent availability of statis-
tics on the Mine Safety and Health Administration (MSHA)
homepage [4]. The data is updated on a daily basis, and
each accident is documented and analysed. Table I provides
an example of the detailed information available on this
website: The daily fatality report for the coal mining indus-
try [5]. Additional statistics that can be accessed include the
actual number of mining-related fatalities in the USA
between 2001–2011 (Figure 4).
Mining Education in the USA
When the trends and injury reasons in the USA were ana-
lysed, no clear patterns appeared immediately evident. One
article summarized the situation with the statement: “Since
2006, a series of disastrous mining accidents with multiple
casualties has shocked the US American mining industry”
[6]. However, closer inspection revealed that the large min-
ing accidents in the USA were mainly caused by two rea-
sons: Methane gas explosions and massive roof failures.
This then raised the question: Why did these accidents hap-
pen when methane is widely known to be extremely danger-
ous in underground operations and checking the roof (rock)
Table I. MSHA coal mining industry daily fatality report on July 5, 2012, for the USA. Abbreviations include underground (UG) and
surface (S) mining [5].
Fatalities chargeable to the
coal mining industry
2007 2008 2009 2010 2011
UG S UG S UG S UG S UG S
Electrical 0 0 1 1 0 0 0 0 0 1
Exploding vessels under pressure 0 0 0 0 0 0 0 0 0 0
Explosive and breaking agents 0 1 0 0 0 0 0 0 0 0
Fall/slide material 1 0 0 0 0 0 0 0 1 0
Fall of face/rib/high wall 9 2 0 1 1 0 3 0 2 3
Fall off roof or back 3 0 4 0 2 0 3 0 1 0
Fire 0 0 0 0 0 0 0 0 0 0
Handling material 1 0 0 0 0 1 0 0 0 0
Hand tools 0 0 0 0 0 0 0 0 0 0
Nonpowered haulage 0 0 0 0 0 0 0 0 0 0
Powered haulage 1 3 7 3 1 7 4 5 3 1
Hoisting 0 0 0 0 1 1 0 0 0 0
Ignition/explosion of gas/dust 0 0 0 0 0 0 29 1 0 0
Inundation 0 0 0 0 0 0 0 0 0 0
Machinery 2 2 3 7 0 1 2 1 2 6
Slip/fall of person 0 8 0 1 1 1 0 0 0 1
Step/kneel on object 1 0 0 0 0 0 0 0 0 0
Striking or bumping 0 0 0 0 0 0 0 0 0 0
Others 0 0 0 2 1 0 0 0 0 0
Year to date totals 18 16 15 15 7 11 41 7 9 12
Combined year to date totals 34 30 18 48 21
End of year total 34 30 18 48 21
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Fatalities/1x106
workedhours
Year
Figure 3. Annual mining-related fatality rates in South Africa [2].
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Figure 4. MSHA annual mining-related fatalities in the USA [4].
80
70
60
50
40
30
20
10
0
Absolutenumber
Year
2001 2003 2005 2007 2009 2011

22 <
conditions in mines is a primary task for all miners? Having
identified these two factors, it appears the underlying causes
are both related to the following education issues:
>> Miners not having enough experience.
>> Mining engineers being insufficiently educated.
The reason for an overall decrease in experience amongst
US miners is that the average age has increased from 35
years old in 1980 to 47 in 2008 [6]. As a result of retirement,
the experience gained by senior miners is gradually being
lost, and safe behavioural practices are no longer being
transferred from experienced miners to inexperienced
young miners. In addition, after only six months new miners
can now take an exam and upon successful completion are
considered sufficiently experienced to work on their own
anywhere in a mine.
Regarding the second issue, due to high salaries offered by
the industry to graduates with a bachelor’s degree as well
as high tuition costs at US universities, fewer young engi-
neers are willing to study for master’s and doctoral degrees.
This has resulted in excessive aging of university staff, in
addition to mining authorities and research institutions fac-
ing a shortage of postgraduate employees.
CONSOL Energy—Absolute ZERO Value System
A positive example in the USA of a mining company that
has been very effective in creating a safe working environ-
ment is CONSOL Energy [7], where 97% of the more than
7500 employees worked in 2007 without a single accident
occurring. The company lists three principal factors that are
required to achieve such figures [6]:
>> Strict compliance with all safety regulations. Although,
these provisions alone are generally not sufficient and
effective.
>> Application of all available technologies even beyond the
mandatory legal requirements, including mine gas moni-
toring and wireless communication systems.
>> A corporate culture where the top priority is safe,
accident-free behaviour in the workplace. Employees
assume a central role in this culture and are responsible
for their own safety and health. The employees are not
only authorized, but explicitly required to immediately
correct any and all unsafe working conditions and if
necessary stop the production process in order to rectify
any defects. Regular training sessions and formal evalua-
tions of the safety behaviour also contribute towards
creating an active zero accident culture among all
employees [7].
CORESafety
In 2012, the US National Mining Association started the
CORESafety initiative: 20 steps until 2015 [8,9]: The following
modules, from a total of 20, are included in this programme:
>> Leadership development.
>> Responsibility and accountability.
>> Management system coordination.
>> Fatality prevention and risk management.
>> Training and competence.
>> Emergency management.
>> Culture enhancement.
>> Collaboration and communication.
The aim of CORESafety is to reduce fatalities to zero and
decrease the injury rate by 50% within 5 years.
In addition to these initiatives, the US Assistant Secretary
of Labor for Mine Safety and Health, Mr. Joe Main, called
for the creation of incentives so operators improve safety
practices as well as stronger civil and criminal penalties
to act as a powerful deterrent against mine operators
knowingly or persistently putting the lives of miners at
risk [10].
Safety in Europe
When the situation in Europe was examined, it showed
that the number of accidents and fatalities in the mining
sector is very low compared to other industries (Figure 5).
Unfortunately, these are the only overall European mining
statistics available; however, they do reveal the severity of
the accidents that have occurred in the mining sector,
since the percentage of fatalities is fivefold higher than
that of injuries [11].
Sweden and Austria
To provide a more in-depth assessment of the situation,
Sweden and Austria were examined individually, since
they both have a vital mining industry and very good sta-
tistics are available [12,13]. In both countries the lost day
injury frequency rate (LTIFR) (i.e., number of occupational
injuries per 1 x 106
working hours) shows a general decline
for both countries (Figures 6), namely in the last decade
the rate of 25 injuries per 1 million worked hours
decreased to 7.7 and 12 in Sweden and Austria, respec-
tively. Furthermore, the LTIFR in Austria reduced signifi-
cantly from 70 injuries per 1 million worked hours in 1970
to approximately 25 in 2000. The reason for this trend was
better equipment, stricter legislation, good education, and
a general improvement in public health. The number of
fatalities is in the range of 0 to 1 per year, with Austria
having 1 in 2010 and 2011, and Sweden having 1 in 2002,
2007, and 2009. In both countries there were zero fatalities
in the other years.
Mining Education in Austria
In part, the relatively low number of injuries and fatalities
in Austria can be attributed to the training and education
opportunities available for mining personnel in this coun-
try, which are divided into:
>> Miner.
>> Foreman.
>> Mine manager.
The training for a miner consists of a minimum of two
years working in a mine as a junior miner, during which
time the apprentice is not allowed to work alone and must
be accompanied by a well-experienced miner. After this
practical training (including several safety training ses-
sions) a mining course must be taken that consists of 120
lectures (each 50 minutes in duration). It covers all relevant
mining issues and ends with an exam [14].
Several years experience in the mining industry is required
before embarking on the foreman education programme.
The initial training consists of a 10 week basic course (39
hours per week), culminating in a written and oral exam.

> 23
After the basic course has been completed, one or more spe-
cial courses can be taken that focus on different topics (e.g.,
open pit, underground, and mineral processing). The special
courses comprise the same number of lessons as the basic
course [15]. In Autumn 2013, the Berg- und Hüttenschule HTL
in Leoben also started to offer a 5 year course focused on raw
materials for pupils typically aged 15–19 years old [16].
University level education is subdivided into bachelor’s and
master’s degree programmes. In addition, doctoral studies
can be performed. Most students in Austria graduate with
a master’s degree. A bachelor programme (7 semesters) is
offered at the University of Leoben under the title: Mineral
Resources Engineering. After completing this B.Sc., a mas-
ter’s programme (3 semesters) can be undertaken.
Figure 5. Percentage of serious and fatal accidents at work in Europe, according to economic activity (total cases: 3942999, fatalities:
4898) [11].
Manufacturing
Transportation and storage
Wholesale and retail trade
Agriculture, forestry, and fishing
Administrative and support service activities
Human health and social work activities
Accommodation and food service activities
Public administration and defence
Water supply; sewerage, waste management
Professional, scientific, and technical activities
Education
Arts, entertainment, and recreation
Other service activities
Information and communication
Financial and insurance activities
Electricity, gas, steam, and air conditioning supply
Real estate activities
Activities of extraterritorial organisations and bodies
Activities of households as employers
Construction
Mining and quarrying
n Serious accidents
n Fatal accidents
0 5 10 15 20 25 30
Figure 6. Annual lost day injury frequency rates in the (a) Swedish [12] and (b) Austrian mining industry [13].
80
70
60
50
40
30
20
10
0
No.ofinjuries/1x106
workinghours
1970 1973 1987 1996 2000 2002 2004 2006 2008 2010 2011
Year
30
25
20
15
10
5
0
No.ofinjuries/1x106
workinghours
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Year(a) (b)

24 <
This is more focused and there are two areas available:
Mining and Tunnelling, and Raw Materials Engineering [17].
Safety in China
Currently, no statistical data is available regarding mining
safety in China. The only information is from media reports
(e.g., Xinhua) and the Government website [18]. The official
number of fatalities reported in coal mines for 2010 was
1920 (2436 in 2009); however, it is assumed that the number
of unreported cases is considerably higher, since a Chinese
miner is 100 times more likely to die in an accident than a
US miner [19].
The Chinese government is committed to improving the sit-
uation and a safety tax was imposed in 2012. This equates
to ~ US$4.8/tonne of coal and funds are planned to be used
to improve the safety of facilities, increase safety education,
set up health damage prevention programmes, build under-
ground shelters, and monitor equipment that is a major
danger source. The results of these measures have not
been published to date, but the impact could be enormous
because of the huge revenue available from such a taxation
scheme.
Summary and Recommendations
The analysis of mining safety data revealed there are no
comprehensive global statistics available. While the Interna-
tional Labour Organization (ILO), a United Nations agency,
provides some information, the data regarding injuries and
fatalities is incomplete. Large mining companies have very
good data and show very positive progress with their aims
to achieve zero injuries in the workplace. In contrast, analy-
sis of the available government data revealed a mixed situ-
ation, with some governments providing access to very
good data and others that do not have or want to publish
such statistics. However, in general from the large mining
company and specific country statistics there appears to be
a positive trend in the area of safety. One key factor influ-
encing safety is good training and education for all person-
nel working in the mining industry—starting with miners
and ending at executive management level.
In conclusion, the mining community must pay even more
attention to safety issues, and also promote more detailed
training and education opportunities for all mining person-
nel. Additionally, the International Organizing Committee of
the World Mining Congresses needs to place far more
attention on safety issues. Therefore, it was very positive to
see several sessions at the 23rd
World Mining Congress
(Montreal, Canada), in August 2013, were focused entirely
on safety.
References
[1] Annual reports and Sustainability reports for Rio Tinto, BHP, and Anglo American (2007–2011).
[2] http://www.bullion.org.za/documents/ar_2011-small.pdf
[3] http://www.bullion.org.za/documents/AR_2012_web_Final.pdf
[4] www.msha.gov
[5] http://www.msha.gov/stats/charts/coaldaily.asp
[6] Brune, J. Occupational Safety and Health in US American Mines – Problems and Potential Solutions. World of Mining - Surface and Underground.
2012, 64, No. 6, 382–389.
[7] http://www.consolenergy.com/about-us/corporate-responsibility/safety.aspx
[8] www.nma.org
[9] http://www.coresafety.org/index.html
[10] http://www.dol.gov/ocia/congressionaltestimony/20100520_JMain.htm
[11]http://epp.eurostat.ec.europa.eu/statistics_explained/index.php/Health_and_safety_at_work_statistics
[12] http://www.svemin.se/MediaBinaryLoader.axd?MediaArchive_FileID=f4416fc2-1c6a-4276-bf1f-1cfc1245459f&FileName=%C3%85rsrapport+201
1engelsk.pdf
[13]http://www.bmwfj.gv.at/EnergieUndBergbau/SicherheitImBergbau/Documents/Sp%C3%B6rker,%20Unfallstatistik.pdf
[14] http://www.htl-leoben.at/files/spezialkursprogramm2013_1_1.pdf
[15] http://www.htl-leoben.at/index.php?article_id=69
[16] http://www.htl-leoben.at/index.php?article_id=162
[17]http://starter.unileoben.ac.at/fileadmin/shares/starter/docs/Studienbrosch%C3%BCre_13_Web.pdf
[18] www.gov.cn
[19] http://www.bbc.co.uk/news/business-11497070
Author
Thomas Drnek, RHI AG, Raw Materials Division, Breitenau, Austria.
Corresponding author: Thomas Drnek, thomas.drnek@rhi-ag.com

> 25
Franz Maier and Clare McFarlane
Low Carbon Economy Roadmap for the Ceramic
Industry
Introduction
The European Commission is looking at cost-efficient ways
to make the European economy more climate friendly and
less energy consuming because if global warming is to be
held below 2 °C compared to the temperature in preindus-
trial times it considers all major economies will need to
make deep emission reductions [1]. Therefore, in July 2009,
leaders of the European Union (EU) and the G8 announced
an objective to reduce greenhouse gas emissions by at least
80% below 1990 levels by 2050, and in October 2009 the
European Council set the appropriate abatement objective
for Europe and other developed economies at 80–95% below
1990 levels by 2050 [2]. Additionally, the Commission esti-
mated the European industry has a technological and eco-
nomical potential to reduce the greenhouse gas (GHG) emis-
sions in the order of 83–87% by 2050 [3]. As far as industrial
sectors are concerned, the European Commission is calling
on them to develop individual roadmaps to address these
targets, as solutions will be highly sector specific.
To show the potentials of the ceramic industry, Cerame-
Unie, the trade industry association representing the eight
sectors of the European ceramic industry (i.e., refractories,
technical ceramics, brick and roof tiles, wall and floor tiles,
table and ornamentalware, sanitaryware, clay pipes, and
abrasives), across 25 EU member states, launched a
Ceramic Roadmap to 2050 for a low carbon economy [4,5].
As a member of the European Refractories Producers Feder-
ation (PRE), a representative organization of the European
refractory industry closely affiliated with Cerame-Unie, RHI
contributed to the refractory section of this roadmap.
Political Background
Europe 2020 is the EU’s growth strategy for the coming
decade [6]. It lays downs targets in the fields of:
>> Employment.
>> Innovation.
>> Climate and energy.
>> Education.
>> Social inclusion.
To support a successful realization of these targets, the EU
developed seven flagship initiatives contributing to smart,
sustainable, and inclusive growth [7]. Three of these initia-
tives are of particular relevance to the ceramic industry,
namely the Innovation Union, resource efficient Europe, and
an industrial policy for a globalization era.
As a consequence of the Europe 2020 strategy develop-
ment, the Commission also designed several roadmaps
(i.e., low carbon economy, resource efficiency, energy,
transport, and agriculture). All these roadmaps are interre-
lated and aim at the same objective of a competitive but
extremely green economy (e.g., resource utilization, CO2
emissions, and energy efficient) by 2050.
The Ceramic Roadmap to 2050
Following the Commission’s request to develop applicable
roadmaps for a low carbon economy [3], in 2012 Cerame-
Unie published the ceramic industry roadmap: Paving the
Way to 2050 [4,5]. This representative assessment was
made for the refractory, brick and roof tile, and wall and
floor tile sectors, since they account for 90% of the entire
ceramic industry’s emissions (Figure 1).
The emissions reduction model was developed with the
following assumptions:
>> Constant production from 2010 to 2050.
>> High degree of kiln capacity utilization.
>> 95% decarbonization of the electricity supply by 2050
(compared to 1990 levels).
Furthermore, future key technologies were considered even
if they require significant development, such as heat recov-
ery from the kiln stack or new kiln design, or they are break-
through technologies like carbon capture and storage (CCS),
on-site syngas or biogas production, and low temperature
heat recovery.
The potential for a 65% emission reduction by 2050 was
predicted with the model where syngas/biogas technology
is developed to replace fossil fuels and a sustainable and
affordable feedstock is secured. However, it also requires
the sector attains sufficient financial support for break-
through research and development and that a stable regula-
tory framework is implemented so the industry can com-
pete with manufacturers outside Europe.
Theoretically, a reduction potential of 75–78% could be real-
ized with a model that includes 50% electrification of the
ceramic kilns to replace fuel firing, assuming a 95% decar-
bonization of electricity production. However, such an elec-
trification programme would be completely uneconomical
because it would require an investment of €90 billion.
Figure 1. Sources of 90% of the entire ceramic industry’s CO2
emissions in 2010 [5].
Fuel
66%
Process
emissions
16%
Electricity
18%

26 <
Furthermore, the write-off and lost production costs would
account for an additional €40 billion and it would result in
absolutely unprofitable running costs.
Therefore, while the refractory industry will significantly
contribute to resource and energy efficiency, it is not feasi-
ble to the extent outlined in the EU 2050 roadmap. Since
refractories will continue to be indispensible for down-
stream users in the future and enable resource and energy
efficient production in other sectors, a regulatory framework
that enhances European competitiveness, supports sustain-
able growth, and avoids the risk of carbon and job leakage
must be considered the primary target.
European Carbon Footprint for Refractory
Products
To provide its members and their downstream customers
with information about the refractory industry’s carbon foot-
print, in September 2013 PRE published the first results of
the refractory product carbon footprint exercise [8,9]. The
data was collected from 40 sites and represents over 40% of
the total annual turnover represented by PRE membership
(i.e., approximately 1.7 million tonnes). It provides the aver-
age European carbon footprint for a range of different
refractory products and includes values obtained for eight
process steps typically involved in refractory manufacture
(Figure 2). The carbon footprint associated with raw materi-
als and product transport was excluded. Not only does this
data enable the European refractory industry to analyse its
environmental position, it also provides refractory user
industries with specific figures to calculate a more accurate
carbon footprint for their products.
The study showed the product carbon footprint directly cor-
related with the energy intensity, which mainly depended
on the kiln load. It also revealed that environmental require-
ments, such as mandatory post process waste gas combus-
tion, can increase the energy intensity by up to 30%.
The European refractory industry is committed to continu-
ing this exercise since it provides the possibility to reveal
emission-related trends. In addition to increasing the num-
ber of product groups covered by the analysis, future aims
include the use of national rather than European conversion
factors.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
TonneCO2equvalent/tonneofproduct
Total
nonbasic
fired shaped
Total
basic
fired shaped
Precast Basic
unfired
shaped
Unshaped
Figure 2. Carbon footprint of different refractory product groups [9].
References
[1] http://ec.europa.eu/clima/policies/roadmap/
[2] http://www.roadmap2050.eu/attachments/files/Volume1_fullreport_PressPack.pdf
[3] “A Roadmap for Moving to a Competitive Low Carbon Economy by 2050”. Communication From the Commission to the European Parliament,
the Council, the European Economic and Social Committee and the Committee of the Regions. COM(2011) 112 final, Ed.; EU-Commission,
Brussels, 2011.
[4] http://www.cerameunie.eu/en/news/european-ceramic-industry-launches-2050-roadmap-paving-the-way-to-a-better-future
[5] “Paving the Way to 2050. The Ceramic Industry Roadmap”. Cerame-Unie, Brussels, November 2012.
[6] http://ec.europa.eu/europe2020
[7] http://ec.europa.eu/europe2020/europe-2020-in-a-nutshell/flagship-initiatives/index_en.htm
[8] http://www.pre.eu/
[9] “PRE Product Carbon Footprint Report”. European Refractories Producers Federation, Brussels, September 2013.
Authors
Franz Maier, RHI AG, Technology Center, Leoben, Austria.
Clare McFarlane, RHI AG, Technology Center, Leoben, Austria.
Corresponding author: Franz Maier, franz.maier@rhi-ag.com

> 27
Markus Dietrich and Stefan Postrach
Chrome Corundum: An Alternative to Isostatically
Pressed Products
Introduction
For several years, chrome-containing refractory products
have been installed in critical areas of soda-lime glass fur-
naces. Their high corrosion resistance against glass melts
ensures an extended furnace lifetime and the stability of
important furnace segments like weir walls and throats. In
particular, isostatically pressed products (iso-chrome) with
high chromium content (typically 95 wt.%) have become
more frequently installed for these applications over the last
years. However, besides their advantageous properties,
these products also exhibit the drawback of low thermal
shock resistance as well as a very elevated price. Therefore,
RHI has been focused on alternative materials based on
bonded alumina-chrome and for several years has been
able to offer much more economic solutions for areas with
high wear in all glass melting tanks. These products exhibit
corrosion resistance close to that of isostatically pressed
material in combination with superior thermal shock resis
tance.
Chrome Corundum
Chrome corundum is based on α-Al2O3 (corundum) and
Cr2O3 (eskolaite). These two oxides exhibit a very similar
crystal lattice and therefore chrome corundum can exist as
a mixed crystal at any Al2O3/Cr2O3 ratio. The phase diagram
of the chrome-alumina system in Figure 1 shows this com-
plete miscibility.
Standard chrome corundum products are produced by
mixing and firing pure eskolaite (Cr2O3) and corundum
(Al2O3) raw materials. The mixed crystal phase is generated
during the firing process and later during operation at high
temperatures. A higher product homogeneity can be
achieved by using fused chrome corundum raw materials.
This so-called smelt is produced in electric arc furnaces.
During fusion, the process parameters need to be accu-
rately controlled due to the high sensitivity to oxidation-
reduction reactions. The resulting fused chrome corundum
raw material consists of a very homogeneous mixed crystal
with a well-defined Al2O3/Cr2O3 ratio and therefore uniform
properties. Another advantage of this process is that not
only primary raw materials can be fused but also recyclable
material and production scrap, which further supports RHI’s
sustainability targets. Two different fused materials with a
Cr2O3 content of 30 wt.% and 60 wt.% are available. The for-
mulation of RHI’s new generation of chrome corundum
products is based on these two well-defined raw materials.
Properties of Chrome Corundum
The most important property of chrome-bearing refractories
is their high corrosion resistance against glass melts. This
property is determined in the laboratory using the static
plate corrosion test. It consists of dipping refractory sam-
ples in glass melt for a defined time at a fixed temperature.
The samples are corroded by the glass melt mainly at the
triple point where the refractory is in contact with both the
glass melt and atmosphere, producing a notch in the sam-
ple. The corrosion resistance is determined by measuring
the notch depth. The test is comparative and a sample of
the most common glass contact material, fused cast AZS, is
used as the standard. Figure 2 shows the results of this cor-
rosion test examining the relative corrosion resistance of
chrome corundum (i.e., SUPRAL brands), iso-chrome, and
fused cast AZS. It was clearly evident that all the chrome-
bearing products were much less corroded than the fused
Figure 2. Static plate corrosion test results. RHI’s SUPRAL RK50S
and SUPRAL RK70 chrome corundum grades (containing 53 wt.%
and 72.5 wt.% Cr2O3, respectively) were compared to isostatically
pressed chrome and fused cast AZS material for 144 hours at
1500 °C in soda-lime glass.
SUPRAL RK70
0.9
Notch depth [cm]
SUPRAL RK50S
0.9
AZS 40
3.6
ISO-chrome
0.8
Figure 1. Phase diagram showing the continuous miscibility of
Al2O3-Cr2O3 [1].
Composition [mol.%]
2300
2250
2200
2150
2100
2050
2000
1950
Temperature[°C]
0
Al2O3
2045 ± 5 °C
2275 ± 25 °C
Cr2O3
20 40 60 80 100

28 <
cast AZS with 40% ZrO2, whereas the difference between
the different chrome-containing materials was minor: The
uniaxially pressed chrome corundum grades were nearly as
resistant to corrosion as the isostatically pressed product.
At several positions in glass furnaces, good thermal shock
resistance is essential. This is a weak point of isostatically
pressed high chrome material. Thermal shock resistance is
tested by heating up cylindrical samples to 950 °C and then
quenching them in water. Isostatically pressed products
only survive a few such cycles, 2 or 3 in general.
Due to good structural flexibility, chrome corundum mate-
rial exhibits a much better thermal shock resistance. The
addition of small amounts of zirconia-based phases further
improves this characteristic. These grains have a different
thermal expansion behaviour compared to chrome corun-
dum and this creates a zone of microcracks in their vicinity.
The microcracks can stop the growth of larger cracks, which
would otherwise destroy the material. This effect is called
microcrack reinforcement. Results of a thermal shock test
comparing various chrome-containing refractory grades are
listed in Table I. The excellent thermal shock resistance of
chrome corundum enables it to be installed even as hot
repair overcoating tiles behind corroded soldier blocks on
container and float glass tanks.
Practical Experiences
Today, chrome-bearing refractory grades are used when
excellent corrosion resistance is required. For example, fur-
naces for the production of C-glass are entirely lined with
chrome corundum materials, permitting a furnace lifetime
of 4 or more years. Since 1980, RHI has also supplied
chrome corundum grades to insulation fibre producers and
over the last 12 years about 70 furnaces worldwide have
been equipped entirely or in major sections with these
materials.
More recently, chrome-bearing material with > 30 wt.%
chromium oxide has been installed in soda-lime glass fur-
naces. The material is only used in zones with high wear
rates, for example the weir wall in container glass furnaces
(Figure 3), doghouse corners, and the throat. Since 2004,
RHI has also supplied uniaxially pressed chrome corundum
grades with a chrome content of 30–70 wt.% for about 40
soda-lime glass furnaces worldwide. A closer look at the
weir walls has shown that chrome corundum greatly
extends their lifetime, when compared to the use of fused
cast AZS.
Weir walls significantly influence the glass melt flow profile,
supporting homogenization. At the same time the wall
retains impurity particles, which could otherwise lead to
glass defects. Thus, chrome corundum weir walls contribute
to longer production periods with high quality glass.
Batch material is fed into the furnace through the dog-
house. Due to the abrasive action of unmelted batch as well
as thermal shock, the doghouse corner blocks are especially
subjected to significant corrosion. When completely worn,
the doghouse corners must be extensively repaired.
Chrome corundum doghouse corners (Figure 4) fulfil the
Grade Cr2O3 content
(%)
TSR
cycles
DURITAL RK30NP 30 > 30
SUPRAL RK30S 30 25
SUPRAL RK50S 53 20
SUPRAL RK70 72 15
Iso-chrome 95 2
Table I. Thermal shock resistance (TSR) of selected chrome-
bearing refractory grades.
Figure 3. Chrome corundum weir wall in a container glass furnace.
Figure 4. Doghouse corner in a container glass furnace compris-
ing two chrome-bearing refractory grades, SUPRAL RK30S and
SUPRAL RK50S.
SUPRAL RK50S
SUPRAL RK30S
SUPRAL RK30S

> 29
demanding requirements in this difficult application area as
a result of the high corrosion resistance and excellent ther-
mal shock resistance of this material.
Frequently, chrome-bearing refractories are installed at the
throat entrance. In this area corrosion is mainly influenced
by forced convection of the glass melt and block failure is
critical because in many cases hot repairs are difficult to
realize. Therefore, corrosion resistant chrome-bearing mate-
rials have proven advantageous, compared to fused cast
AZS, in achieving long lasting campaigns.
Chrome corundum products can also be used as electrode
blocks for electric boosting. These blocks mainly suffer from
strong glass melt convection around the electrodes. High
chromium oxide containing products (> 70 wt.%) must not
be used in this position due to their low electrical resistivity.
If the resistivity is close to or inferior to that of the glass
melt, a short circuit may occur that can cause significant
damage. Chrome corundum grades (< 50 wt.%) are a good
alternative to standard fused cast AZS for this application
because they exhibit a similar electrical resistivity to AZS
combined with enhanced corrosion resistance (Figure 5).
Figure 6. (a) significantly corroded AZS soldier blocks and (b) installation of chrome corundum overcoating tiles providing hot repair.
Overcoating Tiles
An additional success story is the repair of tank sidewalls
with chrome corundum overcoating tiles, which are
installed behind corroded soldier blocks in container and
float glass furnaces (Figure 6). As the tiles heat-up very
rapidly during installation, a special thermal shock resistant
chrome corundum grade is used for this application. Since
2004, this approach has been effective for nearly 200 cases
of colour and flint glass furnaces. The direct comparison of
a chrome corundum overcoating tile and an AZS overcoat-
ing tile was performed on a container glass furnace wall,
where both types of material were installed side by side.
Two years after installation, the superior corrosion resist-
ance of the chrome corundum was clearly evident
(Figure 7).
To date, no negative influence of SUPRAL RK blocks and
DURITAL RK30NP overcoating tiles on the colour of flint
glass has been observed. This was confirmed by a cus-
tomer who detected no measurable increase of the chro-
mium concentration in glass products after installation of
overcoating tiles on a flint glass furnace (Figure 8).
Figure 7. Wear of AZS overcoating tiles (white) in the foreground
and chrome corundum overcoating tiles (black) in the back-
ground, both after 2 years application.
(a) (b)
Figure 5. Electrical resistivity of DURITAL chrome corundum
grades compared to iso-chrome, fused cast AZS, and soda-lime
glass melt.
Temperature [°C]
10000
1000
100
10
1
Electricalresistivity[ohm/cm]
400 600 800 1000 1200 1400 1600
n REFEL 1240
n DURITAL RK50S
n DURITAL RK30S
n Chrome 95
n Soda-lime glass

30 <
Reference
[1] Bunting, E.N. Phase Equilibrium in the System Cr2O3-Al2O3. Bur. Standard. J. Research. 1931, 6, 947–949.
Authors
Markus Dietrich, RHI AG, Industrial Division, Wiesbaden, Germany.
Stefan Postrach, RHI AG, Industrial Division, Wiesbaden, Germany.
Corresponding author: Markus Dietrich, markus.dietrich@rhi-ag.com
Summary
Chrome corundum materials from RHI exhibit excellent
characteristics for different applications in the glass
production process. By using fused raw materials in various
DURITAL and SUPRAL brands (i.e., RK30S and RK50S), the
properties are improved further because the fusion process
ensures homogeneous mixed crystals with a well-defined
Al2O3/Cr2O3 ratio.
Many years of successful experiences with chrome corun-
dum in C-glass furnaces have demonstrated this material is
appropriate for such a demanding environment. A relatively
new application of chrome corundum products is in soda-
lime glass furnaces. For example SUPRAL RK50S and
SUPRAL RK70 are particularly suitable replacements for iso-
statically pressed products in critical furnace segments such
as the throat, weir wall, and doghouse corner. This is
because a comparable corrosion resistance—despite a
much lower Cr2O3 content—is combined with a significantly
higher thermal shock resistance and a higher electrical
resistivity compared to iso-chrome.
Figure 8. Chromium concentration in soda-lime glass before and
after installation of chrome corundum overcoating tiles.
Cr2O3[ppm]
6 months
Installation of the overcoating tiles
9 months
25
20
15
10
5
0

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