Anthracite South Africa exports lower-quality, higher-ash anthracite to Brazil to be used in steel-making. Anthracite is processed into different sizes by what is commonly referred to as a breaker. The large coal is raised from the mine and passed through breakers with toothed rolls to reduce the lumps to smaller pieces. The smaller pieces are separated into different sizes by a system of graduated sieves, placed in descending order. Sizing is necessary for different types of stoves and furnaces. Anthracite is classified into three grades, depending on its carbon content. Standard grade is used as a domestic fuel and in industrial
Anthracite difficulty of igniting it. This was a particular concern in smelting iron using a blast furnace. With the invention of hot blast in 1828, which used waste heat to preheat combustion air, anthracite became a preferred fuel, accounting for 45% of US pig iron production within 15 years. Anthracite for iron smelting was later displaced by coke. From the late 19th century until the 1950s, anthracite was the most popular fuel for heating homes and other buildings in the northern US, until it was supplanted by oil-burning systems and more recently natural gas systems. Many large public buildings, such as