Investigating the performance of different chemicals for cyanide substitution in Bama lead & zinc flotation circuit

Cyanide is the most commonly depressant for pyrite and sphalerite in lead flotation. Although cyanide is a common and strong depressant, but its usage causes environmental pollution and serious hazards. In this study the performance of three chemical substances include sodium sulphide, sodium metabisulphite and sodium sulphite were investigated in lead flotation of Irankooh ore.Since in Bama plant, sequential flotation is being done and the tailing of lead circuit goes to zinc circuit, the effect of cyanide alternatives on zinc flotation was also investigated. After finding the optimal amount of each chemical substance and comparing its performance with cyanide, it became clear that sodium sulphite can be a suitable alternative for cyanide. In natural pH (8.5) with using 600 g/ton sodium sulphite instead of cyanide in lead flotation of Irankooh ore, lead recovery has increased 2.5% and zinc recovery in lead concentrate decreased 0.7%, against iron recovery increased 1.2% and lead grade decreased 1.5%. In this condition, sodium sulphite had positive effect on zinc flotation and in comparing with the optimal amount of cyanide, Zn recovery and Zn grade increased 1.5% and 1.2% respectively. If lead flotation is done with this amount of sodium sulphite and in pH=9.5, the performance will be quite better and in comparing with current plant performance, in addition of increasing 2.8% in lead recovery, lead grade will be increased 2%.