Brown coal

Thermal coal is typically called brown coal or lignite. Coal is a kind of organic rock that is flammable and produces high levels of heat when burned. Coal is a sedimentary rock that is formed from organic materials that are buried in the earth, and are pressured and heated over millions of years. This process is called coalification, and it is a gradual process, so depending on how old a coal seam is, it will hold different kinds of coal that we rank according to age, moisture and carbon content.

Thermal Coal is younger than black coal, averaging at around 15 to 50 million years old. It is one of the early stages of coal that has been converted from peat, which is the very first stage of what becomes coal.

Thermal Coal has a higher water content than black coal, and less carbon, so when burnt it only produces around 25% of the heat produced by black coal. Even so, Thermal Coal is used mostly in energy production, and is a huge source of energy in Australia, and Victoria in particular, which relies on Thermal Coal for most of its energy production. Australia has around 19% of the world’s recoverable coal resources, ranking it second globally, just after the USA’s 20% of resources.

Though Thermal Coal is found all across Australia, Victoria is home to the majority of Australia’s Thermal Coal seams, and 90% of this is found in the Latrobe Valley in southern Victoria. Victoria is also the only state in Australia that mines brown coal.

How is it mined? In Victoria, the major mines of Yallourn, Anglesea, Loy Yang and Hazelwood produce Thermal Coal using open-cut mining methods. Firstly, the rock and soil covering the coal seams is blasted or dragged away. Once exposed, the coal is taken from the ground using massive excavators or dozers, then moved to conveyor belts and delivered to the surrounding power stations. Victoria produces almost 70 million tonnes of coal each year, which makes up 7% of global production, making Australia the 5th largest producer of coal (even though we have the second greatest amount of resources).

Thermal Coal can also be mined from underground, using a variety of methods that include the bord and pillar technique (also known as room and pillar), and the longwall method. In the first method, parallel tunnels called bords are drilled at right angles with other cuts called cut-throughs. This exposes the pillars, which are chunks of coal that can now be removed. Longwall mining is a single step method that removes the coal in large blocks, letting the mine roof collapse afterwards. The longwall method typically produces more coal than the bord and pillar method, as it is quicker and allows for removing larger blocks of coal.

One method that makes use of previous mines is known as the highwall technique, which works through the chasm of a completed open-cut mine. This technique uses underground mining methods to go further than the open-cut mining did. For example, the longwall mining method could be used after an open-cut mine is finished, and this would be called highwall mining. This is a very effective way of mining an area with many layers of coal seam.

Uses -Thermal Coal is typically used to create heat that runs the boilers in power stations. Many power stations are found near coal mines to make the transportation process easier, since most of the coal production goes directly to the power stations. For example, Alcoa of Australia mine at Anglesea in southern Victoria operates solely to produce coal to run the power station next door, which is responsible for providing the electricity for the Alcoa aluminium smelter at Point Henry. Once burned to generate electricity, the coal’s power is easily sent the 45km from Anglesea to Point Henry.

Brown coal is also formed into briquettes that appear in Australian homes, used to light fires and barbeques for cooking and heating. Briquettes are also used industrially and are commercially exported. Brown coal is a source of the industrial carbon that is used in chemical products. It is also used as a char in products such as glass, cement and iron. When used to create water gas, brown coal can be used to produce solvents and liquid fuels. Brown coal can also be used as fertiliser and soil conditioner. It is mined specifically at Maddingley for these agricultural purposes. So, while brown coal isn’t valued as much as its older brother black coal, it is still a hugely valuable resource that underpins the operation of many industries.