Metallurgical coal

• 1. Introduction

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  Metallurgical coal, also called coking coal, softens when heated in a low-oxygen environment. Its volatile components evaporate and escape, and the mass swells and grows in volume. What emerges is coke: an essential fuel and reactant in the primary steelmaking process.

  The demand for metallurgical coal moves in tight step with global demand for steel. Where steelmaking expands, so does the market for coking coal. That coupling gives metallurgical coal a distinct economic character. It is tied not to household energy needs but to the industries that build infrastructure and manufactured goods.

  Three questions run through the rest of this documentary. What physical properties separate coking coal from ordinary coal? How do steelmakers guarantee their supply? And which three countries control most of the global trade?

• 2. Rank, Purity, Testing

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  Metallurgical coal's rank is usually bituminous. But rank alone does not determine whether a seam will produce high-quality coke. The coal must also be low in ash, moisture, sulfur, and phosphorus. These purity requirements are what distinguish coking coal from the more common grades mined for power generation.

  The tendency of a coal to form coke is called its coking ability, or alternatively its caking ability. A coal's rank and physical properties offer a preliminary indication of suitability. To fully evaluate any given sample, laboratory testing is required. What that testing aims to measure becomes clearer when the coke is put to use inside a blast furnace.

• 3. The Blast Furnace

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  Inside a blast furnace, coke physically supports part of the ore and flux burden stacked within the vessel. A coke that fails structurally can disrupt the smelting process entirely. That mechanical demand is why strength and density are the two properties steelmakers evaluate most carefully.

  Metallurgical coal produces coke that is both strong and low in density. That coke can bear the combined weight of iron ore and flux as the furnace operates at full temperature.

  Thermal coal does not produce coke when heated. That difference in behavior explains why prices for the two types of coal are usually quite different. Because their end-uses are entirely separate, they trade in distinct markets.

  The difficulty of sourcing coal that reliably meets the blast furnace's demands has shaped how steelmakers organize their supply chains.

• 4. Supply and Trade

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  Primary steelmaking companies often operate their own coal-producing divisions. Maintaining that supply in-house helps secure a stable and low-cost feed of coking coal. This avoids dependence on open-market prices that can shift with broader market conditions.

  Metallurgical coal comes mainly from Canada, the United States, and Australia. Australia leads the seaborne trade by a wide margin, handling 58% of internationally shipped coking coal. Most of those exports travel to China.

  In the United States, the electric power sector consumed 93% of total coal used between 2007 and 2018. Metallurgical coal and coal for other uses such as heating together accounted for the remaining 7%. That breakdown shows how specialized coking coal is relative to total coal production. Yet it remains indispensable to industries that cannot substitute another fuel.

  Four distinct grades divide the coking coal market, each defined by how well it performs when converted to coke.

• 5. Grades and Types

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  Hard coking coals, abbreviated as HCC, rank highest among the metallurgical coal grades. Below them sit medium coking coal, semi-soft coking coal, and pulverized coal for injection, commonly called PCI coal. These grades differ in how well they perform when converted to coke.

  Some grades of anthracite coal also serve in steelmaking applications, separate from the coking process. Anthracite is used in sintering, in pulverized coal injection, as a direct blast furnace charge, and in pelletizing. It also contributes to the production of ferro-alloys, silicon-manganese, calcium-carbide, and silicon-carbide.

  The existence of four distinct grades, from HCC to PCI coal, means buyers and sellers are not trading a single uniform commodity. Each grade is suited to different roles within the steel and metals industries.