Research On Extraction Of Valuable Components From Cu-Ni-O-S Mixed Ore By Ammonium Sulfate Roasting

As a precious non-ferrous metal resource,nikel plays a very important role in national economy and military manufacturing industry.Since being exploited by Germany in 1823 for the first time,nikel ore’s mining intensity has strenthened year by year.In order to extract each valuable component from raw ore,the research is under a closed circuit process,based on ammonium sulfate,operated in a shaft furnace with constant pressure.The main conclusions are as follow:1.After being analyzed,the raw ore consisted of high content of nikel,copper and iron,but low magnesium.And it was mainly sulfide minerals,without independent nikel phase,and nikel replaced part of iron’s lattice.2.Single factor test of ammonium sulfate roasting-water leaching process showed that under the conditions of tmeperature 450℃ time 2h,molar ratio of ammonium to ore 2.2:1,the extraction rate of Ni,Cu,Fe separately are 82.02%,80.77,79.41%.Orthogonal experiment opyimized the results and under the condition of tmeperature 500℃,time 3h,molar ratio of ammonium to ore 2.4:1,the extraction rate of Ni,Cu,Fe separately reached 88.99%,98.76%,83.15%.3.The TG-DTA of mixture of ammonium and ore as well as XRD pattern of clinkers under different temperature and mixture ratio together came up with the chemical reactions of each phase among the ore.Thermodynamic calculation of the reactions made it clear that the priorities of each component were iron>copper>nickel.The main iron loss was at the form of ihleite.4.Single factor test of ammonium sulfate roasting-water leaching process with sodium sulfate doping showed that under the conditions of sodium sulfate addition 4g,tmeperature 450℃,time 2h,molar ratio of ammonium to ore 2.2:1,particle size of raw ore 80μm,the extraction rate of Ni,Cu,Fe separately were 96.45%,99.95%,80.83%.Orthogonal experiment opyimized the results and under the condition of sodium sulfate addition 6g,tmeperature 475℃,time 3h,molar ratio of ammonium to ore 2.2:1,the extraction rate of Ni,Cu,Fe separately reached 98.78%,99.15%,90.12%.5.DG-DTA of doping mixtrue showed that:the addition of sodium sulfate broadened temperature range of sulphation process,delayed the decomposition of ferric sulfate and ammonium ferric sulfate,thus making it favarable for the extraction of each valuable compoent.The XRD pattern showed after being doped,the diffraction peak becomed sharper and crystalline structure of Na2SO4 was destroyed into amorphous,which was caused by sintering process of Na2SO4.Through XRD and SEM,the action mechanism of sodium sulfate could be summerized as the follows:1.sulfur product helped the growth of product grain;2.Na2SO4 offered alkali metal ion for the system,and it helped destroy mineral structure,promoting sulfation process and generating sodium aluminium silicate.3.It helped destroy sulfate film of the product surface,promoting mass transfer.The main iron loss was at the form of ihleite and ammonium jarosite.