| Along with conventional nickel sulfide ore resources decresasing increasingly, extracting nickel and cobalt from complex unwieldiness nickel ore gradually become a hot research topic. At present our country many enterprises take control of the overseas about ten billion tons of laterite nickel ore resources, and mostly are laterite nickel ore. In this paper in view of the mechanism of extracting nickel and cobalt from laterite nickel ore is needed to study and the process for improvement is put forward, the process of sulfuric acid curing at low temperature and atmospheric water leaching nickel and cobalt was adopted to process laterite nickel ore. The mineralogy of laterite nickel ore, chemical reaction thermodynamics in the process of sulfuric acid curing, various factors influence on leaching rate of nickel, cobalt and iron, curing phase transition rule and kinetics of sulfuric acid curing process were studied.The mineralogy study of raw laterite ore sample showed that the nickel content in the ore is 1.1%, iron content is 47.3%, magnesium oxide content is 1.0%, so that the mineral is a typical laterite nickel ore. Nickel mainly occurs in the mineral of iron oxide, cobalt most occurrence in the mineral of iron oxide and a small number of occurrence in the gangue mineral, etc. The raw ore minerals mainly include goethite, hematite, chromite and quartz, and so on.The results of thermodynamics of sulfuric-acid curing process showed that the mineral with concentrated sulfuric acid is a spontaneous exothermic reaction. Sodium fluoride has a positive role in promoting the reaction of goethite with sulfuric acid and mineral aggregate curing. Under the influence of Sodium fluoride, temperature rising promotes the reation of nickel oxide with sulfuric acid and is advantageous to the nickel oxide into sulfate. In the temperature range (less than 500 ℃), nickel sulfate and cobalt sulfate stably exist so that it is liable to nickel, cobalt water leaching.The effects of temperature, time, sulfuric acid and water addition on extraction of nickel, cobalt were researched. The results show that the leaching of nickel and cobalt increase with an increase of temperature, acid addition and time, and the water addition is good for extraction of nickel, cobalt at some range. The optimal technological conditions are obtained:temperature 450℃, sulfuric acid addition 50%, water addition 20%, sulfation time 60 min. Under these conditions, nickel and cobalt extractions are up to 78.1% and 91.1%, respectively, and iron extraction is 12.5%.Thermogravimetric Analysis of the laterite ore curing process displayed one endothermic peak at about 328℃ with a weight loss of 4.8% attributed to the dehydroxylation of goethite to hematite. The curing material phase was mainly goethite so that the mine had not been completely destroyed at 200 ℃.However, curing material phase was given priority to hematite at 350 ℃, mineral stratification appeared and throughout nickel content distribution in each layer, nickel element migration occured from outside to inside. The XRD results of leaching residues proved that thimbleful of nickel and cobalt transforms into insoluble nickel iron oxide (NiFe2O4) and cobalt iron oxide (CoFe2O4) leading to the extraction loss of nickel and cobalt.In addition, the kinetics in the curing process was studied. The results manifest that the kinetic curves of both nickel and cobalt conform to multiphase solid-liquid regional reaction model from 250℃ to 450℃. The reaction order n< 1 and the rates fast in the beginning, then reduce with reaction proceed. The temperature of constant coefficient of both nickel and Cobalt between 1.0～1.6, the process is controlled by internal diffusion.
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