The use of metallurgical coke is vital in the production of iron as it provides both heat for the blast furnace and acts as a reducing agent in the production of iron from iron ore. The Canadian steel industry uses on average 3.7 megatonnes (Mt) of metallurgical coke in its blast furnaces each year. That’s equivalent to 13.7 Mt of carbon dioxide (CO2) making this industry one of the larger generators of CO2 gas in the metals sector.

Recognizing the impact of this on the Canadian environment, CanmetENERGY is working to reduce the amount of greenhouse gas emissions (GHG’s) released in steel making by lowering the amount of metallurgical coke used in the process. Coke is replaced with a renewable source of carbon, thus allowing a reduction in the CO2 that is produced. In the best possible scenario, 20% of metallurgical coke could be replaced by a renewable carbon, reducing CO2 output by 2.8 Mt.

Our initial strategy has been to investigate the replacement of metallurgical coal in the blend with commercially available charcoal. As the specifications for metallurgical coke are quite stringent, this is not a simple task. The coke consists of partially graphitized carbon materials derived from coal and any additions that interfere with the graphitization process could result in a lower coke quality. With this in mind, our scientists have been studying the effect of quantity, particle size and ash content of the charcoal being used as a substitute.

Our laboratory-scale work using the sole-heated oven (15 kg sample) and pilot-scale work (300 kg sample) indicates that our approach is scientifically and technically feasible. Based on the addition of 5% charcoal material to coking coal blends we have successfully produced industrial grade coke. Our work is continuing as we increase this amount and attempt to modify the charcoal by removing undesirable ash material.

This research is carried out in partnership with the Canadian Carbonization Research Association and is funded by the Government of Canada’s ecoEnergy Technology Initiative.