Roasting of sulphide concentrates and acid leaching of calcines emanating from conventional and microwave assisted roasting

M.Tech.The study presented, investigated the acid leaching behavior of calcines emanating from conventional roasting and microwave assisted roasting of sulphide ores. The aim was to investigate a possible change in the mineral composition of the calcine produced and to investigate the leaching behavior of the calcine produced by conventional and microwave assisted roasting. Two sulphide concentrates were received, pyrite concentrate from OTJIHASE concentrator and sphalerite concentrate from ZINCOR. The mineralogical study was done using the XRD (PANalytical X-PertPro X-Ray diffractometer) to determine the mineral composition of the concentrate and the head grade of each concentrate was determined with an Atomic Absorption Spectrometry (AAS) machine for copper, iron and zinc. The concentrates were wet screened at 500, 355, 212, 150, 106 and 75 μm screens for size distribution and for the purpose of the study it was required that 80% of concentrate should pass the 75 μm screen since after roasting, the calcine obtained were to be acid leached. Conventional roasting was carried out at temperatures of 500oC, 700oC, 850oC and 1000oC at durations of 5min, 10min, 20min, 30min, 1hour and 2hours, while microwave assisted roasting carried out at powers of 200W, 400W, 600W, 800W and time intervals of 3s, 10s, 30s, 30min and 1hou