How foundry coke is produced in Argentine using petroleum coke and coal tar pitch, with no coal in the blend. Raw materials, blend preparation, coke oven design and operation, coke quality

1. Foundry coke without coal: more
than half a century of production
in Argentina
Jorge Madias
Mariano de Cordova
San Nicolas, Argentina

2. Content
• Introduction
• Raw materials
• Blend design
• Coke plant operations
• Coke quality
• Conclusions

3. Introduction
• Foundry coke is produced in Argentina using
domestic raw materials, with any coal at all
• This way to produce coke was developed as a
substitute for coke imports, in the sixties
• Reasons
– Availability of domestic low S petroleum coke
– Availability of domestic coal tar pitch
– Lack of domestic coking coals
• Produced in non-recovery coke ovens

4. Raw materials
• Petroleum coke
– Production in four oil refineries
• YPF Lujan de Cuyo (Mendoza) and La Plata (Buenos
Aires): 0.93 Mt/year
• Esso Campana (Buenos Aires): 0.35 Mt/y
• Shell Avellaneda (Buenos Aires): 0.2 Mt/year
• Annual production in the order of 1.5 Mt
• Due to the crude oil quality, pet coke sulfur content is
in between 0.5 and 1%

5. Raw materials
• Petroleum coke
• Foundry coke producers must compete with other
industries for the supply
– the conventional slot oven batteries at Ternium Siderar, San
Nicolas, Buenos Aires, using up to 40% petroleum coke in the coal
blend
– Copetro, a coke calciner for the production of anodes for the
aluminum industry
– Ferroalloys producers, for use as a reductant at submerged arc
furnaces
– Other smaller markets

6. Raw materials
• Coal tar pitch
– Produced in Carboquimica del Parana, Ramallo,
Buenos Aires, departing from coal tar supplied by
Ternium Siderar steel plant
– Tar is heated to temperatures up to 400 oC in
specially designed distillation stills
– This removes moisture, naphtalene, light creosote
oil and heavy creosote oil from the coal tar
– The resultant product is the coal tar pitch

7. Raw materials
– Pitch substitutes (when domestic pitch is scarce)
• Imported pitch (Colombia, 200 l drums)
• Oxidized asphalt 120/5
– produced in batch reactors where hot liquid asphalt is air
injected and then dumped to a pool
– cut in big pieces after solidification.
– cut into small pieces in a special cutting machine
– incorporated to the blend, before grinding
• Asphaltite
– Mined in Mendoza and Neuquen states

8. Raw materials
• Coke fines
– Recycled to the coking blend to improve coke size
by acting on the fissuring network structure
• Additions for higher ash (for low
recarburization in cupolas)
– Imported coking coals (in the past)
– Domestic high-ash Rio Turbio steam coal
– Sand
– Soil

9. Blend design
• Typical
– 80% petroleum coke
– 17% coal tar pitch
– 3% coke breeze
• The lower the pitch content, the lower the
coke cost
• Compared with coal-based coking blends, ash
is much lower, fixed carbon is higher and
volatile matter is more or less the same

10. Blend design
• Alternative design (to replace pitch)
– with oxidized asphalt: 27%
• Careful oven control to avoid fast fissuring bringing
about too small coke size)
– with asphaltite
• Limited to 5% due to high Sulfur content
• For SAFs producing CaC2, 30-35% asphaltite, 5-10% coal
tar pitch, balance pet coke have been used

11. Blend design
• Coking mechanism differs somewhat from
coal-based blends
• Pitch softens at much lower temperature than
coking coals
• Grinding and mixing are key to coke quality, as
inert and active components are not
intimately mixed as in coking coal

12. Coke plant operations
• Six sites belonging to
five companies
– Las Palmas S.R.L.
– MECAF Argentina
S.R.L.
– SIDYMETAL S.A.
– Minera Lujan S.R.L.
– PROCAMET S.A.

13. Coke plant operations
• Typical process flow

14. Coke plant operations
• Non-recovery coke
ovens
– Rectangular plant
view
– Arched roof
– Low alumina
refractories

15. Coke plant operations

16. Coke plant operations
• The total number of ovens could be estimated
in 120
• Just four of them are of the heat-recovery
type, with sole heating by off gas
• Supposing continuous four-day operation and
four metric tons of coke per oven, annual
capacity would be around 40,000 t
• Some production is exported to Chile,
Uruguay and Brazil

17. Coke quality
• Typical specifications
Product Volatile
matter (%)
Ash (%) Moisture
(%)
Sulfur (%) Fixed
carbon (%)
Size >70
mm (%)
High
recarb./
Low S
1.7 1.5 4 0.6 96 min 95
Medium
recarb./
Low S
2.5 5 4 0.6 93 min 95
Low
recarb.
2.5 9 4 0.7 89 min 95
Medium
recarb./
Medium S
2.5 5 4 1.0 93 min 95

18. Coke quality
• Control at coke plant
– size, moisture, proximate analysis, sulfur and in
some cases, ASTM tumbler test
– Occasionally, MICUM tests and reactivity
determinations have been carried out by third
parties

19. Coke quality
• Most foundries evaluate this coke based on
visual aspect at arrival and behavior during
cupola operation; some of them request
proximate analysis to commercial labs
• Just the larger ones, dedicated to the
automotive industry, carry out some testing
(moisture, proximate analysis, sulfur)
• In operation, the low ash content must be
taken into account

20. Conclusions
• Due to lack of coking coals and availability of
low S pet coke and coal tar pitch, the foundry
coke industry opted for a coal-less coke
production in Argentina more than 50 years
ago
• Coke plant operations has to adapt to the
particular raw material base
• A low-ash high quality coke is obtained

21. Thank you for your attention!
Contact:
jorge.madias@metallon.com.ar