Thermochemical equilibrium calculations indicate the possibility of considerable fuel savings and CO2 emission avoidance in the three steps of the Pidgeon process: (a) calcination of dolomite; (b) production of ferrosilicon from quartz sand, coal, and iron oxide; (c) silicothermic reduction of calcined dolomite by ferrosilicon to magnesium.
In this process, closed-end, nickel-chromium-steel alloy retorts are filled with a mixture of calcined dolomite ore and ferrosilicon, which are heated until magnesium crowns form. Each cycle takes about 11 hours, requires manually filling and emptying of the vacuum tubes, and uses about 11 tons of raw materials for every one ton of magnesium produced.
Commercially, the term limestone includes dolomite, dolomitic limestone, oolitic limestone, and travertine (Dolley 2007), a porous calcitic rock that is commonly formed near hot springs. The leading stone produced in the US, limestone accounts for 42% of total domestic production.
One example is that of the formation of dolomite in the urinary bladder of a Dalmatian dog, possibly as the result of an illness or infection. Uses. Dolomite is used as an ornamental stone, a concrete aggregate, and a source of magnesium oxide, as well as in the Pidgeon process for the production of magnesium.
In the last 10 years, the Pidgeon process has come to dominate world magnesium production. China is the dominant magnesium metal supplier, relying almost exclusively on this method. The silicothermic reduction of dolomite was first developed by Dr. Amati in 1938 at the University of Padua, where his thesis is archived.
Several different types of kilns are used for the calcination process. These kilns can be rotary kilns or shaft kilns. The type of the kiln to be selected strongly depend on the characteristics of the raw dolomite, anticipated production rate, cost of fuel, investment costs, available fuel, local conditions, infrastructure and other things.
Patent US2373913 - Production of magnesia and calcium . In a cyclic process of making magnesia and'` calcium carbonate from dolomite in which call cined dolomite is reacted in a magnesia branch of the process with a strong magnesium chloride brinefto precipitate hydrated magnesio.v and produce an end b'rine containing calcium chloride,