The feasibility of oxidation leaching process of nickel from nickel sulfide ore and the form of different components in the lixivium has been studied at first. The method of leaching nickel sulfide concentration direc...The feasibility of oxidation leaching process of nickel from nickel sulfide ore and the form of different components in the lixivium has been studied at first. The method of leaching nickel sulfide concentration directly by oxidants with existence of ultrasonic has been advanced. The process of leaching nickel from nickel sulfide concentration by using the system of persulfate and silver has been determined. The influence of different factors on the leaching rates of nickel,such as with and without ultrasonic,the concentration of Na2S2O8,liquid-solid ratio and the concentration of AgNO3 have been explored. The results show that:(1) in the oxidative leaching system,nickel can be leached completely as Ni2+ or NiSO4(aq.) from nickel sulfide concentration in theory;(2) the nicopyrite can not exist steadily in the persulfate acid leaching system,but Ni2+can. Meanwhile,sulfur may be existed steadily in the leaching process;(3) nicopyrite with much lower electrostatic potential may be leached earlier than chalcopyrite and sideropyrite;and(4) the overall reaction rate of the leaching process can be enhanced with ultrasonic radiation,but it does not change the mechanism of leaching. The more oxidant concentration or higher liquid-solid ratio is,the higher leaching percentage of nickel. The leaching percentage of nickel can be increased significantly by adding a small amount of AgNO3 during the leaching processes. Under the same conditions,the higher concentration of AgNO3 is,the higher leaching yields of nickel will be obtained.展开更多
Precursors of chromium oxide (p-Cr2O3) were prepared by reducing hexavalent chromium in the presence of sodium carbonate solution under hydrothermal conditions. Methanal was used as the reductant, and carbon dioxide w...Precursors of chromium oxide (p-Cr2O3) were prepared by reducing hexavalent chromium in the presence of sodium carbonate solution under hydrothermal conditions. Methanal was used as the reductant, and carbon dioxide was the acidulating agent. The influences of reaction temperature, initial pressure of carbon dioxide, isothermal time and methanal coefficient on Cr(Ⅵ) reduction were investigated. Experimental results showed that Cr(Ⅵ) was reduced to Cr(Ⅲ) with a yield of 99%. Chemical titration, thermogravimetry (TG), X-ray diffrac-tion (XRD) analysis, and scanning electron microscopy (SEM) were used to characterize the p-Cr2O3 and Cr2O3. The series of p-Cr2O3 were found to be multiphase even if they presented different colors, from gray green to lavender. After these p-Cr2O3 samples were calcined, the product of rhombohedral Cr2O3 with a purity of 99.5wt% was obtained.展开更多
基金Supported by the National Natural Science Foundation of China （50874087 50978212） the Key Projects in the National Science and Technology Pillar Program （2009BAA20B02）
文摘The feasibility of oxidation leaching process of nickel from nickel sulfide ore and the form of different components in the lixivium has been studied at first. The method of leaching nickel sulfide concentration directly by oxidants with existence of ultrasonic has been advanced. The process of leaching nickel from nickel sulfide concentration by using the system of persulfate and silver has been determined. The influence of different factors on the leaching rates of nickel,such as with and without ultrasonic,the concentration of Na2S2O8,liquid-solid ratio and the concentration of AgNO3 have been explored. The results show that:(1) in the oxidative leaching system,nickel can be leached completely as Ni2+ or NiSO4(aq.) from nickel sulfide concentration in theory;(2) the nicopyrite can not exist steadily in the persulfate acid leaching system,but Ni2+can. Meanwhile,sulfur may be existed steadily in the leaching process;(3) nicopyrite with much lower electrostatic potential may be leached earlier than chalcopyrite and sideropyrite;and(4) the overall reaction rate of the leaching process can be enhanced with ultrasonic radiation,but it does not change the mechanism of leaching. The more oxidant concentration or higher liquid-solid ratio is,the higher leaching percentage of nickel. The leaching percentage of nickel can be increased significantly by adding a small amount of AgNO3 during the leaching processes. Under the same conditions,the higher concentration of AgNO3 is,the higher leaching yields of nickel will be obtained.
基金the National Science Foundation for Distinguished Young Scholars of China(No.51125018)the National Key Technologies R&D Program(No.2011BAC06B07)+1 种基金the National High-Tech R&D Program of China(No.2011AA060704)Henan Yongtong Nickel Industry Co.,Ltd
文摘Precursors of chromium oxide (p-Cr2O3) were prepared by reducing hexavalent chromium in the presence of sodium carbonate solution under hydrothermal conditions. Methanal was used as the reductant, and carbon dioxide was the acidulating agent. The influences of reaction temperature, initial pressure of carbon dioxide, isothermal time and methanal coefficient on Cr(Ⅵ) reduction were investigated. Experimental results showed that Cr(Ⅵ) was reduced to Cr(Ⅲ) with a yield of 99%. Chemical titration, thermogravimetry (TG), X-ray diffrac-tion (XRD) analysis, and scanning electron microscopy (SEM) were used to characterize the p-Cr2O3 and Cr2O3. The series of p-Cr2O3 were found to be multiphase even if they presented different colors, from gray green to lavender. After these p-Cr2O3 samples were calcined, the product of rhombohedral Cr2O3 with a purity of 99.5wt% was obtained.
