The leaching kinetics of copper from low-grade copper ore was investigated in ammonia-ammonium sulfate solution with sodium persulfate. The effect parameters of stirring speed, temperature, particle size, concentratio...The leaching kinetics of copper from low-grade copper ore was investigated in ammonia-ammonium sulfate solution with sodium persulfate. The effect parameters of stirring speed, temperature, particle size, concentrations of ammonia, ammonium sulfate and sodium persulfate were determined. The results show that the leaching rate is nearly independent of agitation above 300 r/min and increases with the increase of temperature, concentrations of ammonia, ammonium sulfate and sodium persulfate. The EDS analysis and phase quantitative analysis of the residues indicate that bornite can be dissolved by persulfate oxidization. The leaching kinetics with activation energy of 22.91 kJ/mol was analyzed by using a new shrinking core model （SCM） in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. A semi-empirical rate equation was obtained to describe the leaching process and the empirical reaction orders with respect to the concentrations of ammonia, ammonium sulfate and sodium persulfate are 0.5, 1.2 and 0.5, respectively.展开更多
We have performed the first-principles calculations onto the structural,electronic and magnetic properties of seven 3d transition-metal(TM=V,Cr,Mn,Fe,Co,Ni and Cu) atom substituting cation Zn in both zigzag(10,0) and ...We have performed the first-principles calculations onto the structural,electronic and magnetic properties of seven 3d transition-metal(TM=V,Cr,Mn,Fe,Co,Ni and Cu) atom substituting cation Zn in both zigzag(10,0) and armchair(6,6) zinc oxide nanotubes(ZnONTs).The results show that there exists a structural distortion around 3d TM impurities with respect to the pristine ZnONTs.The magnetic moment increases for V-,Cr-doped ZnONTs and reaches maximum for Mn-doped ZnONTs,and then decreases for Fe-,Co-,Ni-and Cu-doped ZnONTs successively,which is consistent with the predicted trend of Hund's rule for maximizing the magnetic moments of the doped TM ions.However,the values of the magnetic moments are smaller than the predicted values of Hund's rule due to strong hybridization between p orbitals of the nearest neighbor O atoms of ZnONTs and d orbitals of the TM atoms.Furthermore,the Mn-,Fe-,Co-,Cu-doped(10,0) and(6,6) ZnONTs with half-metal and thus 100% spin polarization characters seem to be good candidates for spintronic applications.展开更多
基金Project(2007CB613601)supported by the National Basic Research Program of ChinaProject(10C1095)supported by the Foundation of Hunan Educational Committee,China
文摘The leaching kinetics of copper from low-grade copper ore was investigated in ammonia-ammonium sulfate solution with sodium persulfate. The effect parameters of stirring speed, temperature, particle size, concentrations of ammonia, ammonium sulfate and sodium persulfate were determined. The results show that the leaching rate is nearly independent of agitation above 300 r/min and increases with the increase of temperature, concentrations of ammonia, ammonium sulfate and sodium persulfate. The EDS analysis and phase quantitative analysis of the residues indicate that bornite can be dissolved by persulfate oxidization. The leaching kinetics with activation energy of 22.91 kJ/mol was analyzed by using a new shrinking core model （SCM） in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. A semi-empirical rate equation was obtained to describe the leaching process and the empirical reaction orders with respect to the concentrations of ammonia, ammonium sulfate and sodium persulfate are 0.5, 1.2 and 0.5, respectively.
基金supported by the National Natural Science Foundation of China (Grant No. 51071098)the State Key Development for Basic Research of China (Grant No. 2010CB631002)
文摘We have performed the first-principles calculations onto the structural,electronic and magnetic properties of seven 3d transition-metal(TM=V,Cr,Mn,Fe,Co,Ni and Cu) atom substituting cation Zn in both zigzag(10,0) and armchair(6,6) zinc oxide nanotubes(ZnONTs).The results show that there exists a structural distortion around 3d TM impurities with respect to the pristine ZnONTs.The magnetic moment increases for V-,Cr-doped ZnONTs and reaches maximum for Mn-doped ZnONTs,and then decreases for Fe-,Co-,Ni-and Cu-doped ZnONTs successively,which is consistent with the predicted trend of Hund's rule for maximizing the magnetic moments of the doped TM ions.However,the values of the magnetic moments are smaller than the predicted values of Hund's rule due to strong hybridization between p orbitals of the nearest neighbor O atoms of ZnONTs and d orbitals of the TM atoms.Furthermore,the Mn-,Fe-,Co-,Cu-doped(10,0) and(6,6) ZnONTs with half-metal and thus 100% spin polarization characters seem to be good candidates for spintronic applications.
