Types of Coal (Based on Quality & Usage)
The quality of coal is primarily determined by its carbon content, moisture level, and calorific value (the amount of heat it produces when burned). As plant matter is compressed over millions of years, it passes through different stages of carbonisation, resulting in four main types of coal.
Type | Carbon Percentage | Description | Quality | Use |
Peat | Less than 40% | Formed from decaying plants in swamps. | Low carbon, high moisture, low heating capacity. | Least useful; rarely used as industrial fuel. |
Lignite | 40% to 55% | Low-grade brown coal, soft, high moisture. | Better than peat. | Electricity generation (e.g., Neyveli in Tamil Nadu). |
Bituminous | 60% to 80% | Deep-buried, subjected to heat and pressure. | Most widely used in India; high heating value. | Power generation and general industrial use. |
Metallurgical Coal | 70% to 80% | High-grade bituminous coal. | High value for smelting iron due to its clean burn. | Used specifically in blast furnaces for steel making. |
Anthracite | 80% to 95% | Highest quality, hard coal. | Highest carbon content, burns without smoke. | Premium heating use and specialized industries. |
