Celestite

Celestite (strontium sulphate SrSO4) and strontianite (strontium carbonate SrCO 3) are the two principal strontium minerals; the former is the more common and by far the chief commercial source of strontium. More than 35 deposits or occurrences of celestite have been identified in Canada, chiefly in Newfoundland, Nova Scotia, New Brunswick, Ontario and British Columbia. Of particular economic interest are the Lake Enon and MacRae deposits in the Loch Lomond district of Cape Breton Island, N.S. The Lake Enon deposit was operated from 1969 to 1976 by Kaiser Celestite Mining Limited which supplied an upgraded celestite concentrate to an associated strontium carbonate plant at Point Edward, near Sydney. The MacRae deposit is of current interest to Chromasco, a division of Timminco Limited, Haley, Ont., which is considering its possible development for strontium carbonate manufacture. Celestite is used in the manufacture of strontium chemicals, principally strontium carbonate, nitrate, and hydroxide. Strontium chemicals, in turn, are used in the manufacture of glass and ceramics, in pyrotechnic devices, in the production of strontium metal and in other metallurgical applications. Beneficiation of Nova Scotia celestite ores, which grade 50 to 60% SrSO4, is necessary to upgrade the product to 90% SrSO4 , the feed grade required for strontium chemicals manufacture. Beneficiation consists chiefly of washing and flotation to remove undesirable clay, calcite and silica. The beneficiated strontium sulphate may be converted to the carbonate by a number of processes, the most economic being the "black ash," which involves chemical leaching, rotary kiln calcining with petroleum coke, washing, and treatment with carbon dioxide. Celestite ores from the Lake Enon and MacRae deposits, as well from Birch Island, B.C., have been extensively studied by CANMET. Only the Nova Scotia deposits are summarized in this report since they are primary celestite ores; the Birch Island deposit is principally a fluorite ore containing secondary celestite. Studies on the Nova Scotia ores demonstrate the technical feasibility of developing the Loch Lomond deposits, in particular, as viable sources of strontium sulphate for strontium chemicals manufacture.