Reduction of loss of tungsten trioxide in sulfide tailings

The beneficiation of scheelite-sulfide ores, by flotation, generally involves the preliminary separation of the sulfide minerals as molybdenum, copper-bismuth, pyrrhotite, or other concentrates. In one beneficiation plant, the loss of scheelite with the pyrrhotite product, the output of which was 15-20%, amounted to 4-5% of the ore. This loss was caused by mechanical carryover, without agglomeration, of the scheelite fraction which contained up to 70% of fine material (-0.044 + 0 mm). Various modifications have been made to the process in an endeavor to reduce the scheelite loss with the sulfide tailings. The results with industrial sulfide products are given. Laboratory studies on industrial products have shown that the loss of scheelite with the sulfide products can be reduced by 60-70%, by heating the product after treatment with sodium oleate (100 g/ton) with sodium silicate (temperature 85°C, time 15 min, consumption of silicate 20-25 kg/ton).