| Because of the prominent contradiction between supply and demand of traditional nickel-molybdenum resources,Ni-Mo ore,as a non-conventional nickel-molybdenum mineral resources in China,the development and utilization of it are paid attention.As for the combined method of pyrometallurgy and hydrometallurgy-roasting and leaching drawed lessons from the processing of nickel and molybdenum sulfide ore,it was carried out to in-depth study.This process having some disadvantages of low concentration SO2 flue gas,organic combustion gas,smoke dust containing molybdenum or arsenic,is serious pollution to environment,and difficult to concentrate and recycle other valuable element of vanadium,rhenium,rare earth,precious metals in minerals.Therefore,the research was carried out in the full wet process route of Ni-Mo ore in the domestic researchers.Among these full wet process routes,the oxygen pressure acid leaching process of Ni-Mo ore is a kind of high efficiency,clean and feasible technology.However,it is not clear that the behavior of the system is how to occur and vary during the leaching process.So in this paper,the oxidation and transformation behavior of Ni-Mo ore under the oxygen pressure acid leaching system was studied.(1)Mineralogical features of Ni-Mo ore were analysis by means of multi-element composition,chemical phase composition,XRD and SEM-EDS.There are some valuable metal elements in Ni-Mo ore,including Ni and Mo.The impurity elements are mainly composed of Fe,CaO,SiO2,Al2O3,C.The main form of nickel is NiS mineral,molybdenum is in the presence of amorphous molybdenum sulfide,and iron is mainly in the presence of pyrite minerals.As for the occurrence state of the sulfide of nickel,molybdenum and iron,the gangue matrix of Ni-Mo ore is carbon and aluminum silicate,and the sulfide of nickel,molybdenum,iron jointly or separately embedded in the gangue matrix.(2)The effects of temperature and oxygen partial pressure on the oxidation and conversion of nickel,molybdenum and iron were investigated.The results show that the nickel has been completely transformed and dissolved into the solution;molybdenum sulfide was completely transformed,partially dissolved into the solution,partially come into the slag in the form of the molybdenum oxide;iron oxide largely completed the transformation,partially dissolved into the solution,partially come into the slag in the form of the iron oxide in the slag.The increase of the reaction temperature and oxygen partial pressure is favorable to the leaching of nickel,molybdenum and iron sulfide in Ni-Mo ore.(3)In the study of leaching behavior,the effects of stirring speed,sulfuric acid concentration,reaction temperature,oxygen partial pressure,particle size and other experimental factors on the leaching rate of polymetallic sulfide mineral of nickel,molybdenum,and iron were observed.The results show that the leaching rate of nickel is rapidly increased,in the early stage of the reaction,simultaneously accompanied by leaching of molybdenum and iron.And nickel leaching process is controlled by chemical reaction,with an activation energy of 42.68 kJ/mol,and the reaction order with respect to oxygen partial pressure was 0.79;in the late stage,most of nickel were dissolved into the solution,the leaching rate of nickel decrease rapidly at the same time,with the precipitation transformation of molybdenum,iron,and the product layers of molybdenum and iron oxide were formed on the surface of the Ni Mo ore particles.because of it preventing the further dissolution of nickel,nickel leaching process was control by solid product layer diffusion,with an activation energy of 11.01kJ/mol. |
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