| With the increase of global nickel consumption,reliance on nickel sulphide ore to produce nickel metal can no longer meet the rapid development of the global economy today,and the reserves of nickel sulphide have declined dramatically in recent years,in the future,we are bound to look to the greater reserves of laterite nickel ore.The purpose of this paper is to realize the comprehensive recovery and utilization of valuable metals in laterite nickel ores,to study the sulphuric acid leaching under atmospheric pressure and leaching kinetics of Si-Mg-type laterite nickel ores containing 0.82%nickel and9.67%iron and nickel precipitation after impurity removal of leaching solution,to provide the theoretical basis for industrial application of Si-Mg-type laterite nickel ore.Firstly,The leaching rates of metal nickel and iron,and the nickel leaching kinetics during the atmospheric leaching of lowly-graded silicon–magnesium type’s nickel ore containing 0.82%of Ni and 9.67%of Fe were researched by using the sulfuric acid-atmospheric pressure leaching process.The effects of leaching time,leaching temperature,stirring speed,sulfuric acid concentration and liquid-to-solid ratio on the nickel and iron leaching rate were investigated.The best parameters for this experiment are:leaching time was 9h,leaching temperature was 85℃,stirring speed was 260r/min,concentration of sulfuric acid was 190g/L,and the liquid-to-solid ratio was 6:1.The leaching results under the optimal conditions show that:the leaching rates of nickel and iron were 94.7%and 80.6%.Moreover,In study on iron removal from leachate with natrojarosite method,investigations included factors influenced to iron removal rate and nickel loss rate such as the selection of iron removal precipitating agent;p H interval control in the process of iron removal reaction;dosage of H2O2,etc.The result of iron removal rate and nickel loss rate:when the leachate was oxidation pretreated with water of H2O2 dosage 4m L/L,the Na2SO4 was selected as the iron removal precipitating agent,p H.interval of solution was between 1.6-2.2 and the reaction time was 1.5h,the iron removal rate reached to92.1%and the nickel loss rate reached to 6.7%,then the filtrate was light green,the filtered residue was yellowish,the main phase of the filtered residue was natrojarosite[Na2Fe6（SO4）4（OH）12];the result of Mg2+removal rate from filtrate:after iron removal to remove the Mg2+from the filtrate with sodium fluoride method,under the optimal conditions of stirring intensity 300r/min,p H.between 5.5-6.0,sodium fluoride dosage30g/L,the Mg2+removal rate reached to 90.9%.Finally,Experimental study on the calcination of natrojarosite residue in order to realize the comprehensive recovery and utilization of valuable metal Fe in laterite nickel ore.Results shew:the resulted calcined product Fe2O3 from natrojarosite residue calcination at 720℃can be used as raw material for iron and steel;the calcined producded exhaust gas SO3 can be used to prepare sulfuric acid（SO3+H2O）,from which the comprehensive recovery and utilization of valuable metal Ni and Fe in the laterite nickel ore has been realized. |
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