Research On Direct Reduction Roasting And Magnetic Separation Of Laterite Nickel Ore

With the high grade and the easy mining nickel sulfide ores being used up, and therapid development of China’s stainless steel industry, more and more attention has beenput on the use of the low grade nickel laterite. This paper, taking one kind of importedlimonite type laterite ore as raw material, researched on the direct reduction roastingand magnetic separation. The experimental study mainly include the mineralcomposition, chemical component, reduction roasting, magnetic separation, as well asthe analysis of mineral composition and chemical component of nickel-iron concentrate.The conclusions are given as follows:(1)The primary and secondary order of the effection to nickel recovery can beprovided as: calcinations temperature> reductant dosage> reaction time> raw materialparticle size by the orthogonal test of reductive roasting nickel laterite. The test resultsshow that parameter of calcinations temperatures have great influence on the grade andrecovery of nickel. The higher calcinations temperature is, the more grade and recoveryof nickel are. However, the actual production show that the laterite nickel ore has aserious phenomenon of ring formation in rotary kiln when the temperature is1200℃,which hinder the normal production seriously. Therefore, the test take1150℃as thebest reduction temperature.(2)Additives in reduction roasting nickel laterite process show that: the effect ofreduction roasting-magnetic is not good without additives. However the effect can bestrengthened within suitable additives. The additives containing sulphur can reduce themelting point and surface tension of the nickel-iron crystals in the roasting reductionprocess, and promote the aggregation, growth of the nickel-iron crystals, which has obvious effcet. The compound additives has more effect than single additives. Thenickel grade increase from3.0%without additives to4.1%within the5%of compoundadditive T-5.(3)The optimal test conditions of reduction roasting-magnetic are that: the particlesize of ore being-200mesh, roasting temperature1150℃, lignite as reductant, theparticle size of reduction being-60mesh, the4%of reductor dosage, the roastingadditives being compound additives T-5, the4%of T-5dosage, reduction time being90min, roasting product particle size of-300mm, roughing in3000GS and thenchoiceness in1000GS of magnetic-field intensity. Under the optimal conditions, nickelgrade was4.1%, and iron grade was80%. The recovery of nickel and iron were92%and77%. XRD analysis of nickel-iron concentrate show that nickel dose not exist as anickel single substance, but rather exists as the form of a nickel-iron alloy. Thenickel-iron concentrate with high grade nickel can reduce the amount of slag and savethe energy consumption, which is the ideal raw material for making stainless steel.The result of this paper shows that: the reduction roasting-magnetic separationprocess can enrich nickel and iron selectively, and reduce the amount of slag forsubsequent smelting of ferronickel. The energy consumption also shrunk at the sametime. it is great significance for the development and utilization of the nickel laterite.