The potential—pH diagrams of the Cr-H2O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K a...The potential—pH diagrams of the Cr-H2O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K agrees well with the previously reported results. Based on the potential—pH diagrams of the Cr-H2O and Fe-H2O systems, IR spectra and XRD pattern, the existence forms of iron in the potassium chromate were analyzed, and the methods of iron removal were investigated. The results show that the existence forms of iron in the potassium chromate are potassium ferrate. These results are instructive and helpful to the hydrometallurgical processing of chromite ore.展开更多
The physicochemical properties are very important in theoretical investigation of aqueous electrolyte solution and industrial design of hydrometallurgical processes. In the green hydrometallurgical process of chromite...The physicochemical properties are very important in theoretical investigation of aqueous electrolyte solution and industrial design of hydrometallurgical processes. In the green hydrometallurgical process of chromite ore with sub-molten salt medium of KOH, the ternary system of KOH+K2CrO4+H2O is essential to process control and industrial operation. In order to satisfy the needs of both fundamental research and industrial application, the dynamic viscosity (η) and density (ρ) of mixed aqueous electrolyte solution of KOH and K2CrO4 were measured over a temperature range from 15 to 60 ℃ by using Ubbelohde-type capillary viscometers and a series of densimeters, respectively. The temperature is controlled to an accuracy of ±0.01 ℃ throughout the experiment with thermostat. The dynamic viscosity and density of the ternary systems are performed as functions of chromate and hydroxide concentration and temperature. The regression equations for viscosity and density are obtained with a least-square method and the calculated values are consistent well with the experimental data. The semi-empirical equation obtained will be helpful and instructive to industrial application.展开更多
基金Project(2007CB613501) supported by the National Basic Research Program of ChinaProject(2006BAC02A05) supported by the National Science and Technology Pillar Program of ChinaProject(50904058) supported by the National Natural Science Foundation of China
文摘The potential—pH diagrams of the Cr-H2O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K agrees well with the previously reported results. Based on the potential—pH diagrams of the Cr-H2O and Fe-H2O systems, IR spectra and XRD pattern, the existence forms of iron in the potassium chromate were analyzed, and the methods of iron removal were investigated. The results show that the existence forms of iron in the potassium chromate are potassium ferrate. These results are instructive and helpful to the hydrometallurgical processing of chromite ore.
文摘研究了水热法蔗糖还原铬酸钾/重铬酸钾为水合氧化铬的工艺过程. 考察了蔗糖用量比Rm、等温温度Tiso与等温时间tiso对Cr(VI)还原过程的影响规律,并通过L9(34)正交试验得出了三个因素的相对影响程度为tiso<Rm<Tiso,确定了还原过程的最佳工艺条件:以铬酸钾为原料,铬酸钾水溶液浓度40%,蔗糖用量比1.3即相对过量30%,等温温度240oC,等温时间40 min;以重铬酸钾为原料,重铬酸钾水溶液浓度40%,蔗糖用量比1.2,等温温度220oC;等温时间40 min. 并对铬酸钾和重铬酸钾的还原过程进行了对比分析.
基金Project(2007CB613501) supported by the National Basic Research Program of Chinaproject(50904058) supported by the National Natural Science Foundation of Chinaproject(2006BAC02A05) supported by National Science and Technology Pillar Program of China
文摘The physicochemical properties are very important in theoretical investigation of aqueous electrolyte solution and industrial design of hydrometallurgical processes. In the green hydrometallurgical process of chromite ore with sub-molten salt medium of KOH, the ternary system of KOH+K2CrO4+H2O is essential to process control and industrial operation. In order to satisfy the needs of both fundamental research and industrial application, the dynamic viscosity (η) and density (ρ) of mixed aqueous electrolyte solution of KOH and K2CrO4 were measured over a temperature range from 15 to 60 ℃ by using Ubbelohde-type capillary viscometers and a series of densimeters, respectively. The temperature is controlled to an accuracy of ±0.01 ℃ throughout the experiment with thermostat. The dynamic viscosity and density of the ternary systems are performed as functions of chromate and hydroxide concentration and temperature. The regression equations for viscosity and density are obtained with a least-square method and the calculated values are consistent well with the experimental data. The semi-empirical equation obtained will be helpful and instructive to industrial application.
