Refratechnik Casting develops, produces, and supplies highgrade process materials for steel production. The Casting experts have 25 years of experience in the production and application of biogenic silicas. This know-how has helped put Refratechnik Casting into a commanding position.

1. Process materials
for steel production

2. 22©Refratechnik Casting GmbH
Process materials
for steel production
Refratechnik Casting develops,
produces, and supplies high-
grade process materials for
steel ­production.
The Casting experts have 25 years
of experience in the production
and application of biogenic silicas.
This know-how has helped put
Refratechnik Casting into a com-
manding position.
An expansion in the field of basic
products and in metallurgical slags
completes the product range and
means that it is now possible to
offer complete package solutions.
NERMAT® AF
Product examples
REPROMAT® 80
NERMAT® BF-LC
NERMAT® BF-V
NERMAT® P
NERMAT® BF
NERMAT® AF-V
SILIMAT® G
REFRAFLUX® 3452
SILIMAT® GS
REFRAFLUX® 4842
NERMAT® SP-AL

3. 33©Refratechnik Casting GmbH
Biogenous Silica
For more than 40 years
Refratechnik has been develop-
ing products with this natural raw
material. With the foundation of
Refratechnik Casting in 1997 a
re-orientation of Refratechnik’s
activities, in this field, took place.
Production
The term biogenous silica, being
called rice husk ash, too, points
at the origin of the product.
Biogenous silica is a natural
renewable raw material. In modern
biomass energy plants quality
controlled rice husks are used as
energy source. That means, this
raw material shows a neutral C02
behaviour during combustion.
More precisely, the amount of CO2
being released during combustion
equals the amount absorbed by
the rice plant from the atmosphere
before. This is a major environ-
mental benefit and becomes
more and more important for
raw ­materials of the future.
Properties
Biogenous silica is chemically
very pure and consists of 94-96%
Si02. This purity results in a very
high melting point of approx.
1650 °C. During production
the volatile components are
combusted, the unique, micro-
porous SiO2 structure however
is preserved.
NERMAT® – SILIMAT®
Both, an extremely low thermal
conductivity as well as a low bulk
density of the biogenous silica is
obtained thanks to its microporous
structure. The bulk densities of our
products are determined by the
production process.
NERMAT® AF-V ~ 160 kg/m³
NERMAT® AF ~ 200 kg/m³
NERMAT® BF ~ 190-350 kg/m³
Application
For all the aforementioned
properties, biogenous silica is
an ideal covering agent and has
become the most often used
material for this application in
the steel industry.
For more than 30 years
NERMAT® AF has been and still
is the classical covering agent for
thermal insulations of the continu-
ous casting tundish and casting
ladle and has set high standards in
quality and economy world-wide.
SILIMAT® G is our alternative
low carbon material. This white
biogenous silica shows particularly
good results in the production of
ULC grades < 25 ppm carbon.
NERMAT® AF and SILIMAT® G
are used in the ingot casting route
to insulate the ingot head and as
raw materials for the production of
hot tops, too.
Thermal conductivity of NERMAT®
thermalconductivity[W/m·K]
temperature [°C]
0.5
0.4
0.3
0.2
0.1
0
250 500 750 1000 1400

4. 44©Refratechnik Casting GmbH
Calcium Aluminates
The production of high quality
steel grades requires the applica-
tion of selected materials. Modern
process management of steel
plants minimises vessel slag carry
over. A secondary metallurgical
treatment of steel demands a syn-
thetic slag to be applied. Amongst
others, calcium aluminates is
used for this application, such as
REFRAFLUX® S.
Production
Amongst others, the raw
materials for the production
of REFRAFLUX® S are coarse
bauxite, limestone or dolomite
respectively.
REFRAFLUX® S is granulated
and sintered in a revolving
cylindrical furnace. Therefore,
REFRAFLUX® S is both, ­dust-
free and almost free from ­carbon,
crystal water and adherent
­moisture.
By combining granulation and
subsequent sintering it is possible
to produce calcium aluminates of
most different composition and
to produce them according to the
individual customer specifications.
10% < CaO < 53%
25% < Al2O3 < 60%
1% < MgO < 20%
Secondary phases:
SiO2, Fe2O3, TiO2 et al.
O2
SiO2
Al2O3
N2
NERMAT®
REFRAFLUX®
steel melt

5. 55©Refratechnik Casting GmbH
Another field of application of
pre-reacted calcium aluminates
is the production of hydrogen-
sensitive steel qualities, such as
heavy plate grades.
In continuous casting plants
REFRAFLUX® S is applied as a
flux in the tundish as so-called
„sandwich layer“. Having a liquid
top slag, the contact of steel with
the ambient air is avoided, and
possible reactions between the
steel and acid covering materials,
such as NERMAT® AF, are
reduced, and rising non-metallic
inclusions are bound.
Properties
Depending on the intended field
of application, REFRAFLUX® S
is produced in different fraction
sizes. As a flux for the continuous
casting tundish we offer a granu-
lation of 0.5-5.0 mm. In the field of
secondary metallurgy a granula-
tion of 5-15 mm is applied.
REFRAFLUX® S is a microporous
granulate. If the melt or slag is
moved, for instance by purging,
liquid slag or melt respectively
penetrates into the pores and
REFRAFLUX® S is quickly
dissolved.
Application
Their main field of application is in
the secondary metallurgy. Calcium
aluminates are particularly used
for desulphurisation in the ladle
furnace. A highly reactive slag
is built up very quickly. This slag
can easily be saturated by CaO on
adding lime for optimal desulphuri-
sation.
140120200 100806040
degreeofdesulphurisation[%]
input value sulphur ladle [ppm]
0
20
40
60
80
100
Desulphurisation with REFRAFLUX® 4842 S
Results of 1081 heats

6. 66©Refratechnik Casting GmbH
Magnesite
Since magnesite containing light
granulates show a high melting
point > 1700 °C, they cannot react
with the melt. From the metallurgi-
cal point of view they are inert and
do serve as an thermal insulation
only.
Dolomite
Basic covering agents are pro-
duced using dolomite as raw
material basis. The melting point
is controlled by adding SiO2 and
Na2O. These products show a high
absorbing capacity of non metallic
inclusions like Al2O3 without any
overcrusting.
REFRAMAT®
The REFRAMAT® product group
comprises all covering agents with
basic raw materials. This mainly
covers magnesite and dolomite as
well as their carbonates.
Basic products are exclusively used
for special applications, particu-
larly for the production of stainless
steels and special steels. Such
steel grades may react with some
components, such as SiO2, TiO2 and
Al2O3 in the “standard“ covering
materials like biogenous silica and
calcium aluminates.
Basic products

7. 77©Refratechnik Casting GmbH
Refratechnik Casting GmbH
belongs to the Refratechnik Group,
one of the world's most impor-
tant manufacturers of refractory
­products.
The Refratechnik Group is certified according to:
ISO 9001 – Quality management systems, and
ISO 14001 – Environmental management systems.
Let´s talk about your goals.
We will find the right way.
The administration as well as
research & development depart-
ment are located in Düsseldorf and
at the Refratechnik parent plant in
Göttingen.

8. Ca1-002-08/2017
Refratechnik Casting GmbH
Schiessstrasse 58
40549 Düsseldorf
Germany
Phone +49 211 5858 0
Fax +49 211 5858 149
casting@refra.com
www.refra.com
Ca1-002-08/2017