The leaching results of bismuth sulfide concentrate containing molybdenum and tungsten in air-H2O2-NaOH system, pressure-O2-Na2CO3 system and pressure-O2-NaOH system were investigated. The results show that the extrac...The leaching results of bismuth sulfide concentrate containing molybdenum and tungsten in air-H2O2-NaOH system, pressure-O2-Na2CO3 system and pressure-O2-NaOH system were investigated. The results show that the extraction of molybdenum, tungsten and sulfur goes up with the increase of NaOH concentration, oxygen partial pressure and reaction time. The extraction of molybdenum and tungsten also rises up with temperature, but the leaching ratio of sulfur increases initially to a peak of 98% at 150℃ and then decreases with the increase of temperature. Under the optimal conditions, the extraction of molybdenum, tungsten and sulfur is more than 95.6%, 93.8% and 96.0%, respectively, and the main phases of residue are Bi2O3 and Fe2O3. Therefore, the method of pressure leaching in alkaline solution is provided as an effective separation of molybdenum, tungsten and sulfur from bismuth and a beneficial pretreatment for consequent process.展开更多
Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-...Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-80 specifications:35mL/L 85% H3PO4+20g/L CrO3 at 38℃.Influence of oxalic acid concentration,bath temperature and anodic current density on dissolution rate and coating ratio was examined,when the sulphuric acid concentration was maintained at 160g/L.It was found that chemically resistant and compact oxide layers were produced under low operational temperature (5℃) and high current densities (3A/dm^2).A beneficial effect was observed concerning the addition of oxalic acid (18g/L).The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy (SEM),atomic force microscopy (AFM) and glow-discharge optical emission spectroscopy (GDOES).展开更多
A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as ...A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as the rotation speed of electrode,voltage,and inlet air and liquid flow rates,on the regeneration rate was investigated.Compared with the traditional tank-type reactor,the regeneration rate with the new electrochemical reactor was increased significantly.Under the optimum conditions,the regeneration rate was increased from 45.3%to 84.8%.Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency,smaller equipment size and good stability in operation.展开更多
The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolutio...The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolution rate in hydrophilic surfactants such as tween 80 and sodium lauryl sulfate (SLS). Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) indicated the existence of both form Ⅰ and Ⅱ ofprednisolone in SLS treated crystals. The FT-IR results also showed that, only form Ⅱ could be detected in prednisolone crystals without surfactant and prednisolone form Ⅲ was produced in tween 80 treated crystals. These results were also confirmed by X-ray (XRD) diffraction and scanning electron microscopy (SEM). In general, the results indicated that the presence of hydrophilic surfactants could generate forms Ⅱ and Ⅲ of the crystals. These forms would give rlse to the increase of prednisolone's dissolution rate owing to their physicochemical instability and more hydrophilic property in comparison with stable polymorph of form Ⅰ.展开更多
文摘对不同硫含量的贵州高硫铝土矿硫的溶出率进行了研究。在铝土矿硫含量一定的条件下,考查石灰添加量、溶出温度、苛性碱浓度和溶出时间等对硫的溶出率的影响,得出对硫溶出率影响较大的影响因素。实验结果表明,中等硫含量的高硫铝土矿能得到较低硫溶出率,较适宜的溶出条件为溶出温度260℃,碱浓度195 g/l,石灰添加量CaO12%,时间50 min.
文摘The leaching results of bismuth sulfide concentrate containing molybdenum and tungsten in air-H2O2-NaOH system, pressure-O2-Na2CO3 system and pressure-O2-NaOH system were investigated. The results show that the extraction of molybdenum, tungsten and sulfur goes up with the increase of NaOH concentration, oxygen partial pressure and reaction time. The extraction of molybdenum and tungsten also rises up with temperature, but the leaching ratio of sulfur increases initially to a peak of 98% at 150℃ and then decreases with the increase of temperature. Under the optimal conditions, the extraction of molybdenum, tungsten and sulfur is more than 95.6%, 93.8% and 96.0%, respectively, and the main phases of residue are Bi2O3 and Fe2O3. Therefore, the method of pressure leaching in alkaline solution is provided as an effective separation of molybdenum, tungsten and sulfur from bismuth and a beneficial pretreatment for consequent process.
文摘Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-80 specifications:35mL/L 85% H3PO4+20g/L CrO3 at 38℃.Influence of oxalic acid concentration,bath temperature and anodic current density on dissolution rate and coating ratio was examined,when the sulphuric acid concentration was maintained at 160g/L.It was found that chemically resistant and compact oxide layers were produced under low operational temperature (5℃) and high current densities (3A/dm^2).A beneficial effect was observed concerning the addition of oxalic acid (18g/L).The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy (SEM),atomic force microscopy (AFM) and glow-discharge optical emission spectroscopy (GDOES).
基金Supported by the National Natural Science Foundation of China(21376229)the Excellent Innovation Projects of Postgraduates of Shanxi Province(20103084)the Science and Technology Innovation Projects of Shanxi Province Colleges and Universities(2013128)
文摘A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as the rotation speed of electrode,voltage,and inlet air and liquid flow rates,on the regeneration rate was investigated.Compared with the traditional tank-type reactor,the regeneration rate with the new electrochemical reactor was increased significantly.Under the optimum conditions,the regeneration rate was increased from 45.3%to 84.8%.Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency,smaller equipment size and good stability in operation.
文摘The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolution rate in hydrophilic surfactants such as tween 80 and sodium lauryl sulfate (SLS). Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) indicated the existence of both form Ⅰ and Ⅱ ofprednisolone in SLS treated crystals. The FT-IR results also showed that, only form Ⅱ could be detected in prednisolone crystals without surfactant and prednisolone form Ⅲ was produced in tween 80 treated crystals. These results were also confirmed by X-ray (XRD) diffraction and scanning electron microscopy (SEM). In general, the results indicated that the presence of hydrophilic surfactants could generate forms Ⅱ and Ⅲ of the crystals. These forms would give rlse to the increase of prednisolone's dissolution rate owing to their physicochemical instability and more hydrophilic property in comparison with stable polymorph of form Ⅰ.