Methods of silica removal from pyrometallurgical processing wastes of ilmenite concentrate

This article presents a study on the processing of waste dust from electrical smelting of ilmenite concentrates with the removal of silica from them by alkaline and fluoride methods. The study of the smelting dust leaching by caustic soda solutions included investigation of the effect of sodium hydroxide concentration, process time, temperature, S:L ratio. The optimum conditions of concentrate electric smelting dust leaching - temperature 80-90 °С, duration 90-120 minutes, S:L ratio = 1:5, sodium hydroxide solution concentration 110-115 g/dm3 were determined. The optimum conditions for fluorination of electric melting dust were determined, at which the sublimation degree of silicon fluoride was 84.2 %. Studies have been performed to decomposite obtained silicon-containing sublime in the presence of ammonia agent. The optimum pyrolysis modes that provide the separation of fluoride and silicon oxide - temperature 530-560 °C and duration of 60-80 min have been determined based on the results of thermal analysis and studies on the process duration effect. The silicon oxide content in the obtained product was 96.3%.