Reduction roasting-magnetic separation mechanisms of nickelferous laterite ore in presence of sodium salts

The sodium salts are able to enhance the reduction roasting-magnetic separation of the laterite ores significantly and improve the content and recovery of nickel and iron of magnetic product.The reduced behaviors of saprolitic laterite in the presence of sodium sulfate or sodium carbonate were investigated by using thermodynamical calculation,X-ray diffractometry,optical microscopy and environmental scanning electron microscopy.The results show that sodium salts are able to enhance the reduction and beneficiation of nickel.The sodium carbonate is more effective than the sodium sulfate to reduce nickel locked in forsterite.However,the sodium sulfate is capable of facilitating the growth and coalescence of ferronickel particles because sulfur formed during the reduction of sodium sulfate,diminishing their surface tension,as well as improving the separation of nickel from iron by forming FeS and inhibiting the complete reduction of iron.Thus,a ferronickel material with high nickel content and high recovery of nickel can be obtained in the presence of both sodium sulfate and sodium carbonate.