Rare element pegmatites and their utilization

This literature work summarizes the present knowledge concerning the Finnish pegmatite deposits, and the meth-ods generally used for the concentration of pegmatite minerals and for the recovery of rare elements from their mineral concentrates. Finnish pegmatite deposits are located in Kemiö, Tammela-Somero, Eräjärvi, Seinäjoki-Alavus, Kaustinen--Ullava, Kitee, Kajaani, and Kangasala. Feldspars and quartz have been qualified for two centuries, presendy from the Kemiö deposit. Rare minerals have not been processed, even though there are reserves of spodumene, petalite, beryl, tantalite-columbite and other minerals in the Finnish pegmatites. For that reason, the recovery and markets of the following rare metals were taken to closer inspection: lithium (Li), rubidium (Rb), cesium (Cs), beryllium (Be), niobium (Nb), and tantalum (Ta). Flotation is the concentration method generally utilized for the pegmatite minerals. Gravity separation can be used only, when differences between the specific gravities of the minerals are large enough. From the mineral concentrate, the metal is usually recovered by converting it into a soluble compound by employing hot, strong acids. The impurities are then eliminated from the solution by successive precipitation. The metal is subsequently precipitated as one of its compounds. In 1983, the estimated world makets of niobium, tantalum, lithium, and beryllium totaled around 200 million USD each, whereas rubidium and cesium valued only around 2 million USD. The annual world demand was 9 500 tons of niobium, 6 300 tons of lithium, 860 tons of tantalum, 420 tons of beryllium, 22 tons of cesium, and l,5 tons of rubidium. The economic reserves of tantalum are barely sufficient to meet the cumulative primary demand until the year 2000. In case of the other rare metals, the reserve base is sub-stantially greater than the anticipated cumulative demand.