Abstract
Sodium cyanide (NaCN) and sodium sulphide (Na2S) are frequently employed in selective flotation to depress Lead (Pb) in galena during the froth flotation of sphalerite/galena (ZnS/PbS). Due to their extreme toxicity, there is now more emphasis on developing environmentally and economically sustainable alternative reagents. Following crushing and grinding of the Zurak-Wase ZnS/PbS, was sieve analysis, which yielded a range of -0.71+0.50 particle size and a 50 % cumulative weight passing for optimum liberation. The ZnS/PbS was separately floated in a Denver flotation cell in the presence of 2, 4 and 6 g of corn starch (CS). This produced concentrates of 189 g, 219 g, and 235 g with the corresponding tailings of 110 g, 81 g, and 65 g. The XRF analysis shows 499,997 ppm Pb was best activated and depressed 294,933 ppm Zn with 6 g of CS. It is noticed that CS is a promising Pb activator and Zn depressant with an increased volume which improves the material hydrophobicity and hydrophilicity in that order. CS at higher volume can be used to selectively float Pb from Zn when Pb is a material of the target. CS has proved to be a replacement for NaCN and Na2S to mitigate the ecological challenges related to them. Also, it is an effective reagent to selectively activate Pb and depress Zn Alternative organic materials like dextrin, citric acid, and tannins should be investigated to selectively depress Zn or activate
