Study on treatment of difficult settling wastewater from tungsten mineral processing

Abstract

Large amount of water glass and oleic acid added to the tungsten ore mineral processing resulted in high concentration of water glass residual in the flotation wastewater.Thus, the flotation wastewater was gelatinous and it was difficult for the suspended substance to settle.Researches at home and abroad about flotation wastewater treatment are focused on the removal of organic mineral process reagent and heavy metal.In the practical mineral flotation wastewater treatment project, polyaluminium chloride(PAC) was generally used as coagulant to remove the suspended substance which was difficult to settle.This paper screened and combined the different coagulant and coagulant aid, meanwhile optimized the experimental parameters to improve the effluent quality and meet the reusable water quality standard requirements.The experimental results showed the prepared simulated flotation wastewater based on the investigation of actual flotation wasterwater quality had the characteristics as follows:pH was 12.26, turbidity was 1 390 NTU, suspended substance was 2 780 mg/L, Zeta potential was -59.9 mV. Calcium chloride(CaCl2) and 15 million molecular weight cationic polyacrylamide(PAM) were selected as the optimum coagulant and coagulant aid, the dosage was 500 mg/L and 30 mg/L respectively.Under the experimental conditions of 450 r/min rapid stirring for 5 min, 160 r/min slow stirring for 2 min, followed by settlement for 20 min, the turbidity of the supernatant was 7.11 NTU and the removal rate could reach 99.48%.

Keywords

• flotation wastewater
• water glass
• difficult settling
• calcium chloride
• cationic polyacrylamide