Optimization of flotation process for reduction of alumina and silica from screw classifier overflow of an iron ore washing plant

Abstract

Reverse flotation process was optimized by an experimental programme based on statistical analysis for reduction of silica and alumina levels from screw classifier overflow so as to enrich iron values. Flotation of alumina and silica bearing minerals with Sokem 521C and starch as collector and depressant respectively was studied to estimate their optimum levels at different particle sizes. A two-level three factor design of experiments showed that particle size is insignificant in the ranges of study. Tests on an orthogonal design of the hexagonal type were then carried out to determine the effects of the other two variables, on the response, Selectivity Index (SI), a measure of separation efficiency of iron values from alumina and silica. Regression equations were developed as models and response contours were plotted. Maximum response (SI of 2.25) has been optimized at 0.306 kg/t of amine collector, 1.0043 kg/t of starch at a particle size of 40 µm.