Using coal in steelmaking

A major use of coal is to produce coke, a hard porous carbon material left after the gases of coal are removed by heating the coal to temperatures between 1000 C and 1100 C. Bituminous coals are typically used as coking (metallurgical) coals.

In steelmaking, crushed coke is combined with iron ore and limestone in blast furnaces. As it burns, the coke supplies carbon, removes oxygen from the ore and provides the high temperatures needed to melt the ore and produce crude iron. Steel is then produced in other furnaces from the iron and steel scraps.

In 2002, steelmakers in Ontario and Quebec consumed about four million tonnes of Canadian metallurgical coal, about seven per cent of Canadian consumption. They also imported coal from the U.S.

Canadian coal producers export most of their metallurgical coal — about 30 million tonnes on average each year — to markets in Asia, Europe and South America.

Although most coal in steelmaking is used to produce coke, some steelmakers in Canada and elsewhere have introduced new technologies that allow coal to be directly injected into blast furnaces.

Coke and the environment

As coke is burned, tar and hot oven gases are created. This gas mixture contains carbon dioxide, carbon monoxide, water vapor, benzene, light oils, tar vapor, particulate matter, polycyclic aromatic hydrocarbons and other emissions.

The coal tar and oven gas are collected and transported to a byproducts facility at the steelmaking plant. Some of the components — for example, benzene, sulphur, ammonia and coal tar — are removed and collected for sale.

Tar is used in clinical treatment of skin disorders. Ammonia is used to produce fertilizers. Chemicals recovered from the emissions provide raw material for plastics, solvents, dyes, drugs, paints, roads, roofing and insulation.

Coke oven gas is also distributed throughout the steelmaking plant and used as fuel to offset purchases of natural gas and oil.