CONTROLLED ROASTING OF ZINC SULPHIDES TO MINIMISE FERRITE FORMATION, THEN LEACH WITH SO2 OR AMM.AMM.CARB.

摘要

In a process for recovering zinc from zinc sulphide concentrates, the concentrate is roasted in an oxygen deficient atmosphere so as to retard ferrite formation in the temperature range of 600 DEG C to 1000 DEG C. In one embodiment the calcine produced is subjected to physical separation processes, the unreacted zinc sulphides are then dead roasted separately, and the separated iron containing fraction is treated for further zinc recovery. In another embodiment the unreacted sulphides in the calcine are separated by physical and or chemical means and returned to the partial roasting step; and the separated oxidic fraction either as solids or in a solution, are treated for zinc recovery, and iron disposal. Undesirable sulphides are bled off from the processing circuit as required.