Using combined acidified water glass and sodium citrate to selective inhibit fine-grained chlorite and achieve MgO reduction in zinc concentrate

The entrainment of Mg-containing chlorite usually occurs during marmatite flotation, which further deteriorates the smelting of zinc concentrate. In this study, the flotation behavior of marmatite and chlorite were investigated, which disclosed that fine-grained chlorite was more floatable and easily entered into zinc concentrate than coarse-grained chlorite. The combined water glass (AWG) and sodium citrate (SC) has been confirmed excellent chlorite depressant, which could decrease the grade of MgO from 3.45 % to 0.31 % in zinc concentrate. XPS and reagent adsorption analysis uncovered that Cu 2+ would not adhere and induce collector ML-8 attach to chlorite surface, meaning the entrainment of chlorite was not caused by activation flotation. The moisture of foam for fine-grained chlorite flotation is much higher than of marmatite, confirming that foam for chlorite flotation is not mineralized, and the collection of chlorites was caused by foam entrainment. Moreover, AWG and SC could selectively adsorb on the chlorite surface and reduce its contact angle to 16.85°. Eventually, SEM-EDS detection further revealed that the entrainment of fine-grained chlorite in zinc concentrate was almost disappeared after using the combined AWG and SC to increase the surface wettability of chlorite. The actual ore flotation further confirmed its excellent inhibitory effect on selectivity.