Calcium Chloride Enhanced Magnesium-based Nickel-rich Laterite Ore Coal-based Reduction-magnetic Separation Enrichment Of Nickel

Laterite ores are formed by the prolonged weathering of peridotite-containing nickeliferous silicate minerals,which widely distributed in tropical and subtropical regions,accounting for 70%of the world's nickel resources.With the excessive consumption of high grade nickel sulfide ore,the reserves have been reduced rapidly,therefore,more and more research and development is focued on the more abundant laterite nickel ore.This project set a low-nickel magnesium-rich laterite ore in Yunnan as raw materials,using coal-based reduction roasting and magnetic separation process,based on analysis of physical and chemical properties for minerals,and combined with the thermodynamic calculation,developing an investigation of accelerator for enhancing coal-based reduction-magnetic separation to enrich nickel.The research results provide a theoretical guidance for the development and utilization of low-nickel magnesium-rich laterite ore.In this paper,the chemical composition,X-ray diffraction,thermogravimetry and differential thermal analysis of raw ore were carried out,and the results demonstrate that the main minerals in the raw ore are lizardite and quartz,and with a certain iron ore,meawhle,nickel content reaches 0.82%,and 81.49%of which is distributed in silicate.On the basis of thermodynamic analysis,the effects of reduction time,reduction temperature,content of reductant and promoter on the enrichment of nickel were studied by reduction roasting-magnetic separation in presence of accelerator.The results show that a ferronickel concentrate content of 11.83%Ni,recoveries of 97.38%can be abtained by reducing the laterite ore at 1150? for 40 minutes in presence of 12 wt.%CaCl2·2H20 and 8 wt.%anthracite followed by wet grinding for 12 minutes and magnetic separation under 150 mT magnetic field.Compared with those reduced without calcium chloride,the nickel enrichment ratio of concentrate was increased from 3 to 14,which significantly improved the enrichment effect of nickel.Further study on the accelerate effect of clcium chloride to enrich nickel was carried out,and which is shown in following aspects:(1)The hydrogen chloride gas produced by the hydrolysis of calcium chloride with silicon dioxide under water vapor atmosphere,and then the metal oxides in the ore were chlorinated and reduced by hydrogen chloride and reducing gases.The addition of calcium hloride changed the direct reduction of metal oxides to the chlorination and reduction path,improving the reduction efficiency of nickel.(2)On the other hand,the dehydration of serpentine to be transformed into forsterite phase has been advanced in the presence of calcium chloride,which released nickel oxide from serpentine.The releaed nickel oxide reactes with iron oxide to form spinel,which promoted the aggregation of nickel and iron and then be reduced to ferronickel alloy.