Nickel and cobalt were extracted from low-grade nickeliferous laterite ore using a reduction roasting-ammonia leaching method.The reduction roasting-ammonia leaching experimental tests were chiefly introduced,by which...Nickel and cobalt were extracted from low-grade nickeliferous laterite ore using a reduction roasting-ammonia leaching method.The reduction roasting-ammonia leaching experimental tests were chiefly introduced,by which fine coal was used as a reductant.The results show that the optimum process conditions are confirmed as follows:in reduction roasting process,the mass fraction of reductant in the ore is 10%,roasting time is 120 min,roasting temperature is 1 023-1 073 K;in ammonia leaching process,the liquid-to-solid ratio is 4:1(mL/g),leaching temperature is 313 K,leaching time is 120 min,and concentration ratio of NH3 to CO2 is 90 g/L:60 g/L.Under the optimum conditions,leaching efficiencies of nickel and cobalt are 86.25% and 60.84%,respectively.Therefore,nickel and cobalt can be effectively reclaimed,and the leaching agent can be also recycled at room temperature and normal pressure.展开更多
Approximately 2.0-3.0 t of copper slag(CS) containing 35%-45% iron is generated for every ton of copper produced during the pyrometallurgical process from copper concentrate. Therefore, the recovery of iron from CS ut...Approximately 2.0-3.0 t of copper slag(CS) containing 35%-45% iron is generated for every ton of copper produced during the pyrometallurgical process from copper concentrate. Therefore, the recovery of iron from CS utilizes a valuable metal and alleviates the environmental stress caused by stockpile. In this paper, a new method has been developed to realize the enrichment of iron in CS through the selective removal of silica. The thermodynamic analyses and experimental results show that the iron in CS can be fully reduced into metallic iron by carbothermic reduction at 1473 K for 60 min. The silica was converted into free quartz solid solution(QSS) and cristobalite solid solution(CSS). QSS and CSS are readily soluble, whereas metallic iron is insoluble, in NaOH solution. Under optimal leaching conditions, a residue containing 87.32% iron is obtained by decreasing the silica content to 6.02% in the reduction roasted product. The zinc content in the residue is less than 0.05%. This study lays the foundation for the development of a new method to comprehensively extract silicon and iron in CS while avoiding the generation of secondary tailing.展开更多
Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracit...Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracite, higher manganese extraction efficiency is achieved at lower roasting temperature and shorter residence time. The effects of roasting parameters on the leaching efficiency of Mn and Fe were studied, and the optimal parameters are determined as follows: roasting temperature is 650 °C, residence time is 40 min, and black charcoal dosage is 10%(mass fraction). Under these conditions, the leaching efficiency of Mn reaches 82.37% while that of Fe is controlled below 7%. XRD results show that a majority of MnO2 and Fe2O3 in the raw ore are reduced to MnO and Fe3O4, respectively.展开更多
The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 2...The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.展开更多
LEACH(Low Energy Adaptive Clustering Hierarchy)是一种经典的WSN分层路由协议,它采取自适应分簇算法,一定程度上延长了网络生存期。然而LEACH路由协议的簇头随机产生,没有考虑节点的剩余能量,未达到簇头最优。LEACH簇头与基站直接通...LEACH(Low Energy Adaptive Clustering Hierarchy)是一种经典的WSN分层路由协议,它采取自适应分簇算法,一定程度上延长了网络生存期。然而LEACH路由协议的簇头随机产生,没有考虑节点的剩余能量,未达到簇头最优。LEACH簇头与基站直接通信,如果两者距离较远,则会带来较大的能量损耗。结合LEACH及LEACH现有的一些改进算法,提出了一种新的路由协议(Advance-Leach)。它综合考虑了节点的剩余能量和簇首节点数目,簇头和基站之间采用单跳和多跳结合策略,有效地降低了能耗,保证了网络负载的平衡。仿真结果表明:该协议的能耗、数据成功接收率等性能得到了有效提高,延长了节点和网络的生命周期。展开更多
基金Project(50674014) supported by the National Natural Science Foundation of China
文摘Nickel and cobalt were extracted from low-grade nickeliferous laterite ore using a reduction roasting-ammonia leaching method.The reduction roasting-ammonia leaching experimental tests were chiefly introduced,by which fine coal was used as a reductant.The results show that the optimum process conditions are confirmed as follows:in reduction roasting process,the mass fraction of reductant in the ore is 10%,roasting time is 120 min,roasting temperature is 1 023-1 073 K;in ammonia leaching process,the liquid-to-solid ratio is 4:1(mL/g),leaching temperature is 313 K,leaching time is 120 min,and concentration ratio of NH3 to CO2 is 90 g/L:60 g/L.Under the optimum conditions,leaching efficiencies of nickel and cobalt are 86.25% and 60.84%,respectively.Therefore,nickel and cobalt can be effectively reclaimed,and the leaching agent can be also recycled at room temperature and normal pressure.
基金Project(WUT:2019IVA096)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2019M662733)supported by China Postdoctoral Science FoundationProject(2018YFC1901502)supported by National Key Research and Development Program of China。
文摘Approximately 2.0-3.0 t of copper slag(CS) containing 35%-45% iron is generated for every ton of copper produced during the pyrometallurgical process from copper concentrate. Therefore, the recovery of iron from CS utilizes a valuable metal and alleviates the environmental stress caused by stockpile. In this paper, a new method has been developed to realize the enrichment of iron in CS through the selective removal of silica. The thermodynamic analyses and experimental results show that the iron in CS can be fully reduced into metallic iron by carbothermic reduction at 1473 K for 60 min. The silica was converted into free quartz solid solution(QSS) and cristobalite solid solution(CSS). QSS and CSS are readily soluble, whereas metallic iron is insoluble, in NaOH solution. Under optimal leaching conditions, a residue containing 87.32% iron is obtained by decreasing the silica content to 6.02% in the reduction roasted product. The zinc content in the residue is less than 0.05%. This study lays the foundation for the development of a new method to comprehensively extract silicon and iron in CS while avoiding the generation of secondary tailing.
基金Project(2013JSJJ028)supported by the Teachers’Research Fund of Central South University,ChinaProject supported by Co-Innovation Center for Clean and Efficient Utilization of Strategic Mineral Resources,China
文摘Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracite, higher manganese extraction efficiency is achieved at lower roasting temperature and shorter residence time. The effects of roasting parameters on the leaching efficiency of Mn and Fe were studied, and the optimal parameters are determined as follows: roasting temperature is 650 °C, residence time is 40 min, and black charcoal dosage is 10%(mass fraction). Under these conditions, the leaching efficiency of Mn reaches 82.37% while that of Fe is controlled below 7%. XRD results show that a majority of MnO2 and Fe2O3 in the raw ore are reduced to MnO and Fe3O4, respectively.
基金Project(2010FJ1011)supported by the Major Project of Science and Technology of Hunan Province,China
文摘The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.
文摘LEACH(Low Energy Adaptive Clustering Hierarchy)是一种经典的WSN分层路由协议,它采取自适应分簇算法,一定程度上延长了网络生存期。然而LEACH路由协议的簇头随机产生,没有考虑节点的剩余能量,未达到簇头最优。LEACH簇头与基站直接通信,如果两者距离较远,则会带来较大的能量损耗。结合LEACH及LEACH现有的一些改进算法,提出了一种新的路由协议(Advance-Leach)。它综合考虑了节点的剩余能量和簇首节点数目,簇头和基站之间采用单跳和多跳结合策略,有效地降低了能耗,保证了网络负载的平衡。仿真结果表明:该协议的能耗、数据成功接收率等性能得到了有效提高,延长了节点和网络的生命周期。
