Dolomite is a common rock-forming mineral. It is a calcium magnesium carbonate with a chemical composition of CaMg(CO3)2. There are two types of materials often called dolomite, a true chemically uniform calcium magnesium carbonate with the chemical formula CaMg(CO3)2, and a dolomitic limestone, which is just an irregular mixture of calcium and magnesium carbonates. Dolomite crystals usually form transparent to translucent rhombs that are colorless to light-colored, although crystals may be red to brown if iron impurities are present. Some dolomite crystals also exhibit crystal faces that form slightly curved surfaces, rather than flat planes.
Dolomite is found mostly under the earth’s surface, therefore underground mining methods are required to extract them. One common method used is room and pillar mining. The mineral will be mined in a horizontal fashion underground and the mineral will be removed in a room and pillar horizontal array to support the roof. The rocks will then be crushed into smaller pieces before undergoing milling to break the pieces into fine powder.
Dolomite is used as a flux and for manufacture of refractories for basic open hearth furnaces and steel ladles. Dolomite for use as flux in steel metallurgy should be hard, compact and fine-grained so that it can stand the burden of the batch in the blast furnace as well as the basic steel converter. It should not be crystalline nor a saccharoidal texture which gives fritting effect in the furnace. It should be free from phosphorus and sulfur and contains low levels of impurities. Generally, two grades of dolomite are used. One is called blast furnace (BF) grade and the other steel melting shop (SMS) grade.
Dolomite is quarried for building and ornamental stone, road stone, and the production of refractory brick. Dolomite is used as filler for its higher strength and hardness in refractories which line rotary cement kilns.
It is the principal ore of magnesium metal and the source of the magnesium used by the chemical industry. Dolomite is used in the making of magnesium salts including magnesia, magnesium oxide (MgO).