The distribution characteristics and existing state of cadmium in the Jinding Pb-Zn deposit were studied. It was discovered that Cd was mainly distributed in sphalerite as an isomorphic impurity. There was a good corr...The distribution characteristics and existing state of cadmium in the Jinding Pb-Zn deposit were studied. It was discovered that Cd was mainly distributed in sphalerite as an isomorphic impurity. There was a good correlation between Cd and Zn in the primary ore. With the oxidation and resolution of pyrite, sphalerite, sulfide, and etc., many secondary minerals, such as colloform sphalerite and smithsonite, were formed. The distribution of Cd is not symmetrical, and enrichment and dilution were observed in partial area of the oxidation zone in the deposit. Cd, except in external pore space or cracks of secondary minerals as independent minerals, such as greenockite, was mainly distributed in sphalerite as an isomorphic impurity in the secondary sphalerate and smithsonite in the oxidation zone. The research showed that Cd showed a very strong active transfer ability in the oxidation process, not only indicating that supergene leaching might be the main reason for Cd enrichment in some Pb-Zn deposits, but also reflecting that Cd was easily mobilizeed and transferred to pollute ore areas in the oxidation process. Furthermore, Cd in oxidation ore was more easily mobilized and transferred to induce bad hazards for ore areas with the effect from AMD which was produced from oxidation of sulfides.展开更多
The sphalerite oxidative kinetics under hypergene condition was simulated and studied by means of a mixed flow reactor over a pH range of 1.0 7.8,and at dissolution temperatures from 20 to 55℃,ferric ion concentratio...The sphalerite oxidative kinetics under hypergene condition was simulated and studied by means of a mixed flow reactor over a pH range of 1.0 7.8,and at dissolution temperatures from 20 to 55℃,ferric ion concentrations from 1.0×10-5 to 1.0×10-2 mol/L,O 2 flux of 0.5 L/min,and oxidants of ferric ion and O 2.It is indicated that with ferric ion as oxidant,the oxidation rate of sphalerite increases with increasing ferric ion concentration,temperature and decreasing pH value,and under the studied conditions,the dissolution rates of Zn and Cd are approximately identical,with the values of activation energy being 41.75 and 42.51 kJ·mol-1,respectively,suggesting that the oxidation rate of sphalerite is controlled by chemical reactions on mineral surface.However,with O 2 as oxidant,the oxidation mechanism of sphalerite varies with pH value.Oxidation rate decreases with increasing pH value when pH is lower than 5.95,whereas the increase of pH value results in an increase in oxidation rate when pH value is higher than 7.The oxidation rate of sphalerite can be expressed as:R Zn =10 1.1663 [Fe3+] 0 0.154 ·[H+] 0.2659 ·e-41.75/RT or R Cd =10 1.7292 [Fe3+] 0 0.170 ·[H+] 0.2637 ·e-42.展开更多
基金supported by the National ‘973 Project’ (No. 2009CB421003)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No: KZCX2-YW-111-03, KZCX2-YW-136-2)the Foundation of State Key Lab. of Ore Deposit Geochemistry
文摘The distribution characteristics and existing state of cadmium in the Jinding Pb-Zn deposit were studied. It was discovered that Cd was mainly distributed in sphalerite as an isomorphic impurity. There was a good correlation between Cd and Zn in the primary ore. With the oxidation and resolution of pyrite, sphalerite, sulfide, and etc., many secondary minerals, such as colloform sphalerite and smithsonite, were formed. The distribution of Cd is not symmetrical, and enrichment and dilution were observed in partial area of the oxidation zone in the deposit. Cd, except in external pore space or cracks of secondary minerals as independent minerals, such as greenockite, was mainly distributed in sphalerite as an isomorphic impurity in the secondary sphalerate and smithsonite in the oxidation zone. The research showed that Cd showed a very strong active transfer ability in the oxidation process, not only indicating that supergene leaching might be the main reason for Cd enrichment in some Pb-Zn deposits, but also reflecting that Cd was easily mobilizeed and transferred to pollute ore areas in the oxidation process. Furthermore, Cd in oxidation ore was more easily mobilized and transferred to induce bad hazards for ore areas with the effect from AMD which was produced from oxidation of sulfides.
基金supported jointly by the National Natural Science Foundation of China (Grant No. 40930425)the Science and Technology Foundation of Guizhou Province [Grant No. (2010)2229]the Geological Science Foundation of the Bureau of Geology and Mineral Exploration and Development of Guizhou Province [Grant No. (2009)18]
文摘The sphalerite oxidative kinetics under hypergene condition was simulated and studied by means of a mixed flow reactor over a pH range of 1.0 7.8,and at dissolution temperatures from 20 to 55℃,ferric ion concentrations from 1.0×10-5 to 1.0×10-2 mol/L,O 2 flux of 0.5 L/min,and oxidants of ferric ion and O 2.It is indicated that with ferric ion as oxidant,the oxidation rate of sphalerite increases with increasing ferric ion concentration,temperature and decreasing pH value,and under the studied conditions,the dissolution rates of Zn and Cd are approximately identical,with the values of activation energy being 41.75 and 42.51 kJ·mol-1,respectively,suggesting that the oxidation rate of sphalerite is controlled by chemical reactions on mineral surface.However,with O 2 as oxidant,the oxidation mechanism of sphalerite varies with pH value.Oxidation rate decreases with increasing pH value when pH is lower than 5.95,whereas the increase of pH value results in an increase in oxidation rate when pH value is higher than 7.The oxidation rate of sphalerite can be expressed as:R Zn =10 1.1663 [Fe3+] 0 0.154 ·[H+] 0.2659 ·e-41.75/RT or R Cd =10 1.7292 [Fe3+] 0 0.170 ·[H+] 0.2637 ·e-42.
