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
The constructed potential-pH diagrams of Li-Ni(Co,Mn)-H_(2)O system indicate that the LiNiO_(2),LiCoO_(2)and LiMnO_(2)are thermodynamically stable in aqueous solution within the temperature range of 25-200℃and the ac...The constructed potential-pH diagrams of Li-Ni(Co,Mn)-H_(2)O system indicate that the LiNiO_(2),LiCoO_(2)and LiMnO_(2)are thermodynamically stable in aqueous solution within the temperature range of 25-200℃and the activity range of 0.01-1.00.A predominant co-region of LiNiO_(2),LiCoO_(2)and LiMnO_(2)oxides(Li-Ni-Co-Mncomposite oxide)is found in the Li-Ni-Co-Mn-H_(2)O potential-pH diagrams,in which the co-precipitation region expands towards lower pH with rising temperature,indicating the enhanced possibility of synthesizing Li-Ni-Co-Mn composite oxide in aqueous solution.The experimental results prove that it is feasible to prepare the LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)cathode materials(NCM523)by an aqueous routine.The as-prepared lithiated precursor and NCM523 both inherit the spherical morphology of the hydroxide precursor and the obtained NCM523 has a hexagonalα-NaFeO_(2)structure with good crystallinity.It is reasonable to conclude that the aqueous routine for preparing NCM cathode materials is a promising method with the guidance of the reliable potential-pH diagrams to some extent.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Project(FA2019015)supported by the Government of Chongzuo,Guangxi Zhuang Autonomous Region,ChinaProject(AD18281073)supported by Science and Technology Department of Guangxi Zhuang Autonomous Region,China
文摘The constructed potential-pH diagrams of Li-Ni(Co,Mn)-H_(2)O system indicate that the LiNiO_(2),LiCoO_(2)and LiMnO_(2)are thermodynamically stable in aqueous solution within the temperature range of 25-200℃and the activity range of 0.01-1.00.A predominant co-region of LiNiO_(2),LiCoO_(2)and LiMnO_(2)oxides(Li-Ni-Co-Mncomposite oxide)is found in the Li-Ni-Co-Mn-H_(2)O potential-pH diagrams,in which the co-precipitation region expands towards lower pH with rising temperature,indicating the enhanced possibility of synthesizing Li-Ni-Co-Mn composite oxide in aqueous solution.The experimental results prove that it is feasible to prepare the LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)cathode materials(NCM523)by an aqueous routine.The as-prepared lithiated precursor and NCM523 both inherit the spherical morphology of the hydroxide precursor and the obtained NCM523 has a hexagonalα-NaFeO_(2)structure with good crystallinity.It is reasonable to conclude that the aqueous routine for preparing NCM cathode materials is a promising method with the guidance of the reliable potential-pH diagrams to some extent.
