红土镍矿钠盐还原焙烧-磁选的机理

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

配加钠盐焙烧可改善红土镍矿的还原-磁选效果,显著提高磁性产品的镍、铁品位及回收率。通过热力学计算,并结合X射线衍射、光学显微镜以及环境扫描电镜分析,对硫酸钠和碳酸钠作用下红土镍矿的还原行为进行研究。结果表明:钠盐在红土镍矿还原焙烧过程中,可以破坏硅酸盐矿物的结构,有利于镍的还原富集。碳酸钠强化镍还原的能力强于硫酸钠的,硫酸钠则因还原过程中形成的硫具有降低镍铁金属颗粒表面张力的作用,因而其促进镍铁颗粒聚集长大的能力明显高于碳酸钠的,且硫酸钠作用下FeS的形成也有利于提高镍的品位。所以,硫酸钠和碳酸钠的共同作用下可获得高镍品位的磁性产品及较高的镍回收率。

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.