Carbones

Carbones are combustible sedimentary rocks formed from ancient plant material that has been buried, transformed by heat and pressure, and consolidated over geological time. They are mainly carbon, with varying amounts of moisture, volatile compounds, and mineral ash. Coal is classified by rank into lignite, sub-bituminous, bituminous, and anthracite, which generally correspond to increasing carbon content and energy density and decreasing moisture and volatiles.

Formation and composition: Coal originates from peat that was buried and subjected to diagenesis and metamorphism. Through coalification, plant matter loses moisture and gases while increasing carbon content. The different ranks reflect the degree of transformation, depth, and temperature experienced.

Mining and processing: Coal is extracted by underground mining or surface mining, using methods such as room-and-pillar or longwall in underground operations and open-pit mining on the surface. After extraction, coal is typically cleaned to remove soil and mineral matter. Some coal is used as a fuel without significant processing; other grades are processed for specialized uses, such as metallurgical coke produced from coking coal.

Uses and industry: The primary uses are electricity generation and heating (thermal coal) and metallurgical applications, especially steelmaking (coking coal). Coal also supplies chemical feedstocks and charcoal production in some regions, and remains a major energy source in parts of the world.

Environmental and social aspects: Coal combustion releases substantial carbon dioxide and other pollutants, contributing to climate change and air quality concerns. Mining can impact landscapes and ecosystems, prompting safety, environmental, and transition considerations as energy systems diversify.