Studies On Preparing Ammonium Molybdate From Ni-Mo Minerals

The Ni-Mo mineral has a abundant storage capacity in the provinceof Hunan and Guizhou in our country and it has a huge economic value.Because it is a kind of refractory mineral, adopting the traditionalphysical technique for ore-dressing is difficult to enrich the valueelements from the ores.The traditional pyro-metallurgy could not yetachieve the purpose of separation molybdenum, nickel from othermetals.There was no proper productive process to treat with it both inChina and other countries.On this condition, through the comparison towarding various project,a new productive process of ammonium molybdate from Ni-Mo ore hadbeen studied in this thesis.The process mainly consisted of roasting, leaching, and solventextraction three parts. At first, oxygenize the Ni-Mo ore by using themethod of oxidizing roast to make the Ni,Mo and other metals sulphideconversing oxidate. At the same time, using the saturated Na₂CO₃ toimbibite the air of SO₂ which released during the process of response tomake sodium pyrosulfite, it can erase the pollution of SO₂ toenvironments. Nextly, using NaOH to leach molybdenum selectively atthe condition of inleting O₃, so that it can achieve the purpose ofseparating the molybdenum and nickel. Thirdly, MgCl₂ solution isapplied to remove the impurities and solvent extraction technology hasbeen accepted to refine molybdenum to prepare Ammonium molybdate.During process of roast, the nickel sulphide of the mineral of Ni-Mohas inverted into the nickel oxide, it has advantageous to furthersour-leach to extract nickel. Moreover, the reaction can carry on in theway of normal atmosphere, hasing a low request to the equipments, lowcost, intensive adaptability, less pollution.This thesis researchs the influence of roast temperature and roasttime to the desulphur roasting of Ni-Mo ores through a single factorexperiment. Results show that the best craft parameters are: the Ni-Mominerals (powder was-120 mush), roast temperature 600℃, roast time is 2h.The effect for the extraction ratio of Ni-Mo minerals of roastingstate, leaching temperature, leaching times, odium hydroxide quantity isinvestigated.The experimental results show that the optimal technologicalparameters of leach are: NaOH (1.2 times), leaching temperature was90℃, adding active-oxygen time 2 hours, the ratio of liquor to solid was3:1.Through the research of dynamics by process of the active-oxygenalkali leaching, discover the process of Mo-leaching being controlled bythe chemical reaction model, the leach speed is added with the thereaction speed constant, so it is a major enhance means to raise the leachrate of molybdate by raising leach temperature.The effect for the extraction technique of the volume ratio of organicphase to aqueou, extraction time, pH value, reaction temperature, etc areinvestigated. The experimental result show that the optimal technologicalparameters of extraction process: the volume ratio of organic phase toaqueous (O/A) is 1:1, extraction time is 3 minutes, pregnant solution pHvalue is 2.0～3.5, reaction temperature is normal temperature.The effect for the extraction technique of the volume ratio of organicphase to aqueous, Ammonia concentration, anti-extraction time, etc, onthe anti-extraction process for Mo-contain organic phase solution isinvestigated.The experimental results show that the optimal technologicalparameters of anti-extraction process is: the volume ratio of organic phaseto aqueous is 1:1, ammonia concentration is 12.5%, anti-extraction timeis 10 minutes, place time is 30 minutes.Under the optimal technological parameters, desulphurizing roastingratio is about 90.1%, the loss ratio of Mo is 1.86%, leaching ratio couldreach 99.50%; disposal ratio of impurities P and As are both over 99%,while V is 98.7%, extraction ratio could reach 98.4%, and anti-extractionratio could reach 97.2%.Plasma spectrum (ICP-AES) is instituted to determine the chemicalcomponent of leaching solution and solution which has removedimpurities. X-diffraction(XRD) and the ICP-AES are instituted to analyzethe phase and chemical component of the ammonium molybdate, the results of ranalyze show that the ammonium molybdate specimen whichprepared by this process with a little amount ammonium sulfate,ammonium chloride and ammonium metavanadate are coarse ammoniummolybdate, the purityof ammonium molybdate is 95.32%, the contentammonium metavanadate is 0.65%, also contenting some impurities likeammonium sulfate, ammonium chloride. It is a good way to buy thepatent of Xiao Liansheng coming from CSU to removal the problem of V(patent number: 200510136644.4, public nubmer. CN1792819). It canremoval the ammonium sulfate, ammonium chloride during the refineprocess of ammonium molybdate.