Flotation of Vostok-2 skarn scheelite sulphide ore with modifiers

This paper describes the results of a study that looked at different reagent regimes of flotation of scheelite skarn ores with soda, sodium bicarbonate and sodium sulphide. According to published research data, these regimes of selective recovery scheelite from Skarn ores of Portuguese and Chinese deposits as an alternative to Petrov method. The results of studying the changes of the optical density of water glass in mixing with soda, sodium bicarbonate and sodium hydroxide at different temperatures are presented. Gelation of water glass is observed in a mixture of soda or sodium bicarbonate. The authors were studied the floatability of calcium minerals of scheelite sulphide ore by combined depressants (water glass and sodium sulphide), their dose (0–11.4 kg/t) and proportions (0.7 to 8), as well as the duration of conditioning at the Laboratory of Primorsky Concentrating Plant (PCP). In the course of research, it was established that a high dose of soda and sodium bicarbonate in the scheelite rougher flotation cycle determines a 2- to 6-times higher yield of rough scheelite concentrate with a 1.8-times lower WO3 enrichment ratio. A rise in the water dose to 1.4 kg/t in the rougher flotation cycle led to the recovery of scheelite falling to 30.4–41%, with the WO3 concentrate quality being 22.78–50.5%, corres pondingly. No commercial quality was reached when scheelite concentrate was subjected to heat treatment in a sodium sulphide (43–62 kg/t) and alkaline environment (рН 13) without water glass. Addition of 3.3 kg/t of water glass to sodium sulphide helped raise the quality of scheelite concentrate after three cleaner flotation to 54% WO3 and the recovery of scheelite was 68.4% only. A recovery of more than 82% of commercial grade scheelite concentrate (WO3 > 50%) was reached when running in standard mode using Petrov method of heat treatment. Application of the above processes, which demonstrated high performance in relation to scheelite ores taken from Skarn deposits of Portuguese and Chinese, to samples of Skarn scheelite sulphide ores from Far Eastern deposits, did not prove successful. The authors would like to thank the Research Laboratory of PCP for support with lab studies.