Bauxite residue is a highly alkaline waste containing soluble alkaline anions, which can cause environmental concerns. The optimal leaching conditions, distribution of alkaline anions, types of pivotal alkaline anions...Bauxite residue is a highly alkaline waste containing soluble alkaline anions, which can cause environmental concerns. The optimal leaching conditions, distribution of alkaline anions, types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment. Using a two-stage leaching, 86% of the soluble alkaline anions（CO3^2-, HCO4^-,Al（OH）4^-, OH^-） were leached with a L/S ratio of 2 mL/g, at 30 ℃, over 23 h. During the first stage of leaching, approximately 88% of alkaline anions were leached from the dissolution of free alkali（Na OH, carbonate, bicarbonate, NaAl（OH）4） with the rest originating from the dissolution of alkaline minerals（calcite, cancrinite and hydrogarnet）. Supernatant alkalinity was 69.78 mmol/L with CO3^2- accounting for 75%. Furthermore, carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol.展开更多
为了探究炭砖在铁水中的溶解行为,基于实际炉缸铁水成分配置不同元素质量分数的铁水,将炭砖制成圆柱试样并浸入铁水中,用旋转指棒法进行试验。研究结果表明,碳的溶解反应是炭砖侵蚀的主要反应,扫面电镜发现,反应后界面处炭砖孔径增大。...为了探究炭砖在铁水中的溶解行为,基于实际炉缸铁水成分配置不同元素质量分数的铁水,将炭砖制成圆柱试样并浸入铁水中,用旋转指棒法进行试验。研究结果表明,碳的溶解反应是炭砖侵蚀的主要反应,扫面电镜发现,反应后界面处炭砖孔径增大。基于旋转指棒法的试验数据,得到了炭砖侵蚀速率与铁水温度及元素质量分数间的定量关系,选取特征参数比较了元素质量分数对侵蚀速率的影响程度。建立了炭砖溶解反应动力学模型,利用模型分析了铁水元素质量分数对反应速率常数的影响,并计算了溶解反应的活化能为46.83 k J/mol。展开更多
Anodic polarization behavior of gold, silver, copper, nickel and iron in potentiostatic condition has been examined in an alkaline aqueous thiourea solution, where gold is hardly dissoluble normally. The addition of N...Anodic polarization behavior of gold, silver, copper, nickel and iron in potentiostatic condition has been examined in an alkaline aqueous thiourea solution, where gold is hardly dissoluble normally. The addition of Na2SO3 into the solution can accelerate anodic dissolution of gold. The factors affecting selective dissolution of gold in the alkaline thiourea solution by electrolysis have been studied, and the optimum condition was obtained. In 0.1 mol/L thiourea solution of pH 12. 5 containing 0. 5 mol/L Na2SO3 and 2. 5% acetone, at the potential of 0. 34 V vs NHE, at the temperature of 323 K, the dissolved mass of gold anode with the exposed area of 1. 0 cm2 reached more than 300 mg·dm-3 within 30 min, and other metals such as silver, copper, nickel and iron could hardly dissolve.展开更多
Carbon dissolution from solid fuels used in a COREX gasifier was investigated in a high-temperature furnace to investigate the influences of temperature, carbon structure and ash properties of solid fuels into molten ...Carbon dissolution from solid fuels used in a COREX gasifier was investigated in a high-temperature furnace to investigate the influences of temperature, carbon structure and ash properties of solid fuels into molten iron on carbon dissolution behavior. The results showed that the final carbon content of molten iron and dissolution reaction rate of carbon increased as the temperature increased. However, the dissolution behavior of different solid fuels varied with their properties. At the same temperature, the dissolution reaction rate of solid fuel from high to low was coke, semi-coke and lump coal. The apparent reaction rate constants of solid fuel were calculated using the piecewise fitting method based on the experimental data. The analyzed results showed that the dissolution rates of solid fuels had a good correlation with their microcrystalline structures. Moreover, the carbon crystallite structures of solid fuels used in COREX had greater influence on dissolution behavior than their ash properties.展开更多
基金Project(41371475)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
文摘Bauxite residue is a highly alkaline waste containing soluble alkaline anions, which can cause environmental concerns. The optimal leaching conditions, distribution of alkaline anions, types of pivotal alkaline anions and their dissolution behaviors were investigated based on the combination of single factors-orthogonal experiments and leaching stage experiment. Using a two-stage leaching, 86% of the soluble alkaline anions（CO3^2-, HCO4^-,Al（OH）4^-, OH^-） were leached with a L/S ratio of 2 mL/g, at 30 ℃, over 23 h. During the first stage of leaching, approximately 88% of alkaline anions were leached from the dissolution of free alkali（Na OH, carbonate, bicarbonate, NaAl（OH）4） with the rest originating from the dissolution of alkaline minerals（calcite, cancrinite and hydrogarnet）. Supernatant alkalinity was 69.78 mmol/L with CO3^2- accounting for 75%. Furthermore, carbonate leaching was controlled by solid film diffusion using the Stumm Model with an apparent activation energy of 10.24 kJ/mol.
文摘为了探究炭砖在铁水中的溶解行为,基于实际炉缸铁水成分配置不同元素质量分数的铁水,将炭砖制成圆柱试样并浸入铁水中,用旋转指棒法进行试验。研究结果表明,碳的溶解反应是炭砖侵蚀的主要反应,扫面电镜发现,反应后界面处炭砖孔径增大。基于旋转指棒法的试验数据,得到了炭砖侵蚀速率与铁水温度及元素质量分数间的定量关系,选取特征参数比较了元素质量分数对侵蚀速率的影响程度。建立了炭砖溶解反应动力学模型,利用模型分析了铁水元素质量分数对反应速率常数的影响,并计算了溶解反应的活化能为46.83 k J/mol。
文摘Anodic polarization behavior of gold, silver, copper, nickel and iron in potentiostatic condition has been examined in an alkaline aqueous thiourea solution, where gold is hardly dissoluble normally. The addition of Na2SO3 into the solution can accelerate anodic dissolution of gold. The factors affecting selective dissolution of gold in the alkaline thiourea solution by electrolysis have been studied, and the optimum condition was obtained. In 0.1 mol/L thiourea solution of pH 12. 5 containing 0. 5 mol/L Na2SO3 and 2. 5% acetone, at the potential of 0. 34 V vs NHE, at the temperature of 323 K, the dissolved mass of gold anode with the exposed area of 1. 0 cm2 reached more than 300 mg·dm-3 within 30 min, and other metals such as silver, copper, nickel and iron could hardly dissolve.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China （Nos. 51704216, 51474164 and U201760101） and China Postdoctoral Science Foundation （No. 2016M602378）.
文摘Carbon dissolution from solid fuels used in a COREX gasifier was investigated in a high-temperature furnace to investigate the influences of temperature, carbon structure and ash properties of solid fuels into molten iron on carbon dissolution behavior. The results showed that the final carbon content of molten iron and dissolution reaction rate of carbon increased as the temperature increased. However, the dissolution behavior of different solid fuels varied with their properties. At the same temperature, the dissolution reaction rate of solid fuel from high to low was coke, semi-coke and lump coal. The apparent reaction rate constants of solid fuel were calculated using the piecewise fitting method based on the experimental data. The analyzed results showed that the dissolution rates of solid fuels had a good correlation with their microcrystalline structures. Moreover, the carbon crystallite structures of solid fuels used in COREX had greater influence on dissolution behavior than their ash properties.
