A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na2CO3 roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na2CO3-ore ma...A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na2CO3 roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na2CO3-ore mass ratio, and roasting temperature on Cr and Al extraction were studied. Experimental results indicate that the extraction rates of Cr and Al are up to 99%and 82%, respectively, under the optimal particle size of 44–74μm, Na2CO3-to-ore mass ratio of 0.6：1, and temperature of 1000 ℃. Dechromization within the range of 600–800 oC is controlled by the diffusion through the product layer with an apparent activation energy of 3.9 kJ/mol, and that it is controlled by the chemical reaction at the surface within the range of 900–1100 ℃ with an apparent activation energy of 54.3 kJ/mol. Besides, the Avrami diffusion controlled model with on apparent activation energy of 16.4 kJ/mol is most applicable for dealumination. Furthermore, 96.8%Ni and 95.6%Co could be extracted from the alkali-roasting residues in the subsequent pressure acid leaching process.展开更多
In order to realize the dechromization of a Cu-Cr alloy in HCl solution, the influence of surface roughness and deformation on dechromization of the Cu-Cr alloy was studied by means of metallographic observation, TEM,...In order to realize the dechromization of a Cu-Cr alloy in HCl solution, the influence of surface roughness and deformation on dechromization of the Cu-Cr alloy was studied by means of metallographic observation, TEM, SEM/EDX, and CH1660A electrochemical instrument. The results showed that the bigger the sample＇s deformation and surface roughness, the shorter the incubation time of dechromization of the Cu-Cr alloy, and the trend of dechromization increases. Simultaneously, the deformation can increase the dechromization rate, invite stress corrosion, and decrease the compactibifity of the microstructure of the dechromization layer. And yet the surface roughness does not obviously affect the dechromization rate and the compactibility of the dechromization layer.展开更多
基金Project(51125018)supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProject(51204153)supported by the National Natural Science Foundation of ChinaProject(2011BAC06B07)supported by the National High Technology Research and Development Program,China
文摘A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na2CO3 roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na2CO3-ore mass ratio, and roasting temperature on Cr and Al extraction were studied. Experimental results indicate that the extraction rates of Cr and Al are up to 99%and 82%, respectively, under the optimal particle size of 44–74μm, Na2CO3-to-ore mass ratio of 0.6：1, and temperature of 1000 ℃. Dechromization within the range of 600–800 oC is controlled by the diffusion through the product layer with an apparent activation energy of 3.9 kJ/mol, and that it is controlled by the chemical reaction at the surface within the range of 900–1100 ℃ with an apparent activation energy of 54.3 kJ/mol. Besides, the Avrami diffusion controlled model with on apparent activation energy of 16.4 kJ/mol is most applicable for dealumination. Furthermore, 96.8%Ni and 95.6%Co could be extracted from the alkali-roasting residues in the subsequent pressure acid leaching process.
文摘In order to realize the dechromization of a Cu-Cr alloy in HCl solution, the influence of surface roughness and deformation on dechromization of the Cu-Cr alloy was studied by means of metallographic observation, TEM, SEM/EDX, and CH1660A electrochemical instrument. The results showed that the bigger the sample＇s deformation and surface roughness, the shorter the incubation time of dechromization of the Cu-Cr alloy, and the trend of dechromization increases. Simultaneously, the deformation can increase the dechromization rate, invite stress corrosion, and decrease the compactibifity of the microstructure of the dechromization layer. And yet the surface roughness does not obviously affect the dechromization rate and the compactibility of the dechromization layer.
