| Sulfur-carbonate uranium deposit is an unconventional uranium resource,which occupies a large proportion of uranium reserves in China.Due to the high content of carbonate minerals and sulphide minerals in the ore,the problems of high acid consumption,serious mudification and low uranium leaching rate limit the development and utilization of this type of uranium ore.With the rapid development of China's nuclear industry and the proposal of the 14th Five-Year Plan,the demand for uranium continues to increase and the gap between supply and demand continues to expand.Therefore,it is of economic value and practical significance to study and utilize this type of uranium ore.The main contents and results of this study are as follows:(1)In order to improve the leaching rate of uranium in a sulfur-carbonate uranium ore and control the oxidation leaching rate of pyrite,the influence of particle size,temperature,sodium carbonate content and air partial pressure on the leaching rate of pyrite and uranium was investigated.The results showed that when the leaching temperature,alkali dosage,oxygen pressure and particle size were150?,16%,0.7 MPa and 74?m,the leaching rate of pyrite and uranium was 23.63%and 81.61%,respectively,which was higher than 7.27%in the process of alkali leaching at atmospheric pressure,and the leaching rate of pyrite was controlled at about 3.8%without obvious increase.Temperature,amount of sodium carbonate of sodium carbonate and particle size on pyrite leaching is the most significant,and the influence of oxygen pressure and particle size on uranium leaching is weak..(2)In order to study the influencing factors and kinetics of pyrite leaching under alkaline conditions,the properties of the ore were analyzed using XRD and XRF techniques.Single factor and orthogonal experiments were used to explore the influence of ore particle size,p H,leaching temperature and oxygen pressure on the oxidative leaching of pyrite,and the unreacted shrinkage nucleus model was used to analyze the kinetics of the pyrite leaching process.The results show that temperature and p H have a great influence on the leaching rate of pyrite;when the particle size is-140?m,the solid-liquid ratio is 1:20,the oxygen pressure is 0.8MPa,the p H is 13,the leaching temperature is 70?,and the leaching time is 6h.Under conditions,the oxidation leaching rate of pyrite can reach 14.72%;the leaching process is mainly controlled by the diffusion of the solid product layer,following the1-3(1-x)2/3+2(1-x)=kt kinetic model,The apparent activation energy of the leaching reaction is 14.316k J/mol..(3)The ore was pretreated by flotation,and the flotation product pyrite concentrate and carbonate tailings were leached by acid method and alkali method respectively.As a result,the recovery rate of Fe S2in pyrite concentrate is 67.31%and that of carbonate tailings is 96.26%.The leaching rate of pyrite is 50%lower than that of original ore and 94%higher than that of original ore.When pyrite concentrate is leached by acid method,the leaching rate of pyrite is 3%and that of uranium is 91.0%.The leaching effect of the sulfur-carbonate uranium ore is ideal after flotation,but the flotation process is relatively complex. |
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