Effect of Modified Polyvinyl Caprolactam on Gold Recovery from Fine Slime in Gold Ore Flotation

The authors investigate a new reagent—modified water-soluble polymer of polyvinyl caprolactam (PVCL)—as a collector in flotation of gold-bearing sulfide ore. Modified PVCL is obtained by solid-phase modification of poly(N-vinyl caprolactam) by thiourea. The electron scan and laser microscopy identified adsorption of PVCL at gold grains applied artificially to the surface of polished sections of pyrite. It is found that PVCL facilitates selective aggregation of gold-bearing minerals from fine slime, and more than 99% of gold goes from fine slime to sand at the content of 3.54 g/t. The use of PVCL together with butyl potassium xanthate (PVCL 30 g/t, BPX 200 g/t) in flotation of finely ground gold-bearing ore from the Olimpiada deposit improved the quality of the concentrate: gold content increased from 19.9 to 29.5 g/t and gold recovery increased from 81 to 95%. The joint application of modified PVCL and BPX results in the gold recovery higher by 14%, concentrate quality improved 1.5 times and in the gold content of tailings reduced to 0.15 g/t.