Technological Aspects of Sintering Low-Quality Wolframite Concentrate with Potassium Carbonate

Abstract

The loss of quality of wolframite concentrates determines the need to improve their processing method that ensures maximum conversion of tungsten into water-soluble wolframate and a reduction in water-soluble impurities. The results of thermodynamic modeling of the sintering of wolframite concentrate with sodium and potassium carbonates indicate a greater efficiency of K2CO3: The reagent consumption required for complete conversion of tungsten into solution decreases from 170% from stoichiometric sintering with Na2CO3 to 110% for K2CO3, as well as the proportion of soluble silicates up to 0.1%. In addition, sintering with K2CO3 is accompanied by the formation of compounds with a higher melting point, preventing melting and coating formation during the process. Mathematical sintering models were obtained by the method of probabilistically deterministic planning of this experiment. Optimal parameters have been determined: The extraction of tungsten into a solution of more than 95% is achieved by sintering with K2CO3 in an amount of 105–110% according to the stoichiometric requirements for the formation of K2WO4, K2MoO4, and K2SO4 at temperatures of 1073–1123 K for 100–120 min. Pilot tests have confirmed the effectiveness of the process. The possibility of sintering a cinder of wolframite concentrate with K2CO3 without the introduction of recycled materials has been established. Sintering under optimal conditions ensures the transition of tungsten to water-soluble tungstate by 97.5%.