Dolomite is a mineral composed of calcium and magnesium carbonate. It is of sedimentary origin and is expected to have been formed due to chemical action of sea-water containing high percentage of magnesia, on limestone. Depending upon the variation in the lime and magnesia content, various forms of dolomite include (a) ‘calcitic’ dolomite – having higher content of calcium carbonate, (b) ‘dolomitic limestone’ – with lower content of magnesium carbonate.
Dolomite is used predominantly in the production of refractory bricks (which finds application primarily in the steel industry) and as a flux material in blast furnace operation in secondary steel and ferro- manganese production. In addition, dolomite also finds application in glass making (sheet glass manufacturing) and for agriculture use as a soil conditioner for reducing soil acidity and addressing magnesium deficiencies. Further, dolomite is used for a range of filler applications in plastics, paints, rubbers, adhesives and sealants.
It is understood that there are significant dolomite reserves at Chunaikhola in Samtse dzongkhag in Western Bhutan as well as at dzongkhags viz. Pemagatshel and Samdrup Jongkhar in Eastern Bhutan although the quantity of reserves has not been ascertained as yet. Currently, the entire dolomite is mined by Jigme Mining of the Lhaki Group which has a 15 year lease for mining dolomite from Chunaikhola mines. The total production of dolomite in Bhutan was around 1.22 Mn MT in 2010 of which around 97% (1.16 Mn MT) was exported to India (dolomite powder: 0.09 Mn MT, dolomite chips/ lumps/ slabs: 1.07 Mn MT) while the remaining 3% (0.06 Mn MT) was exported to Bangladesh (Dolomite powder: 0.05 Mn MT, dolomite chips/ lumps/ slabs: 0.01 Mn MT).