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Metallurgical coal, also known as coking coal, supplies the heat and carbon used in the steel mill process to make steel products. The high temperatures created from the use of coke gives steel it's strength and flexibility, so it can be used in bridges, buildings, and automobiles.

While metallurgical coal is primarily used by steel companies, it is also used by a variety of other industrial users to heat and power foundries, cement plants, paper mills, chemical plants and other manufacturing and processing facilities. Metallurgical coal is less abundant than steam coal and can be used either for making coke or as a replacement for steam coal

Coal & Its Uses - Steel Making
Some 70% of total steel production is based on the smelting of iron ore in blast furnaces and the subsequent refining of the iron into steel, mainly in Basic Oxygen Furnaces (BOF). A blast furnace typically uses iron ore, coke (made from coal), small quantities of limestone, and, where Pulverised Coal Injection (PCI) is employed, pulverised or granulated thermal coal.Iron ore, mined in many countries, is a mineral containing iron oxides. Commercial ore grades usually have an iron or ferrous content of at least 58%. Most of the ore fed to the furnace is finely ground and then mixed and heated with coke fines to form 'sinter'. Smaller quantities of natural lump or pelletised ores are then added.

Coke is made from coking coals, which have certain physical properties that cause them to soften, liquefy and then resolidify into hard but porous lumps when heated in the absence of air. Coking coals must also have low sulphur and phosphorous contents.

Coal is carbonised in batteries of coke ovens. The coal blend, crushed to a maximum size of 3 mm, is poured into the top of the ovens and heated to above 1200°C over a period of 18-20 hours. The volatile contents of the coal are driven off as coke oven gas, which is first cleaned to remove impurities and yield by-products such as tar and benzole; then used to heat the ovens themselves and as fuel elsewhere in the steelworks. The red-hot coke is pushed out of the ovens, cooled and screened to remove the smaller sizes. The larger sized material - typically above 30 mm - goes to the blast furnace, where it:

supplies carbon as a reducing agent, removing the oxygen from the ore;
provides heat to melt the iron;
acts as a load-bearing but permeable layer, supporting the burden whilst allowing the reducing gases to pass through.
Ore, coke and limestone are fed into the top of the furnace. The hot air blast and, if PCI is installed, the pulverised coal, are injected through nozzles into the base of the furnace. The pulverised coal injected in this way is used as a less expensive source of carbon and fuel. The molten iron or hot metal are periodically tapped from the bottom of the furnace and taken directly to the Basic Oxygen Furnace. Steel scrap and more limestone are added, and oxygen is blown onto the liquid metal, which is 93-95% pure iron at this stage. The reaction with the oxygen raises the temperature to 1600-1650°C and oxidises the impurities to leave almost pure liquid steel.

Blast furnaces with PCI require 350-400 kg of coke, made from 525-600 kg of coking coal, plus 100-200 kg of cheaper PCI coal - around 700 kg of coal for each tonne of hot metal produced. Furnaces without PCI use more coke, also equivalent to some 700 kg of coal, but all of it the more expensive coking coal. As each tonne of steel uses approximately 90% hot metal and 10% scrap, about 630 kg of coal is used to produce 1,000 kg of steel.

Coking Coal

冶金焦煤是用来炼焦炭用的煤种，焦炭在炼铁炉中起着还原、熔化矿石，提供热能和支撑炉料，保持炉料透气性能良好的作用。因此，炼焦用煤的质量要求，是以能得到机械强度高、块度均匀、灰分和硫分低的优质冶金焦为目的。
    国家对冶金焦用煤有专门的质量标准，如下：
    1  肥煤、气煤
       灰份：1-13级（不大于5.5%为一级，每增加0.5%提高一级，到13）；
       硫份：1组 不大于0.5%   2组 0.51-1%   3组 1.01-1.5；
       水分：1号 不大于0.9%   2号 9.0-10%   3号 10.0-12.0。
    2  焦煤、瘦煤
       灰份：级别为11.5% ；
       硫份：1组 不大于0.5%   2组 0.51-1%   3组 1.01-1.5；
       水分：1号 不大于0.9%   2号 9.0-10%   3号 10.0-12.0。
    1/3焦煤是介于焦煤、肥煤和气煤之间的过渡煤，具有很强的粘结性和中高等挥发分，单独用来炼焦时，可以形成熔融性良好、强度较大的焦炭。因此，它是良好的配煤炼焦的基础煤。