Preparation of high-purity tellurium powder by hydrometallurgical method

This hydrometallurgical method consists of oxidation leaching, sulfide impurities removing, and sulfur dioxide reduction. The crude tellurium powder was treated by H2O2 oxidation for 2.0 h at pH 2.5 when adding 50 ml H2O2(30 %) per 100 g raw material, a tellurium recover rate around 91 % is achieved. The tellurium leaching ratio can reach 98.9 % under 3.75 mol L-1NaOH concentration in liquid–solid ratio of 5:1 at 80 °C for 1.5 h. The overall separation of tellurium and other heavy metals is optimum at sulfide dosages of about 1.1 times of the theoretical values. The removal rates of Ag, Ni, Pb, and Cu from the solution are greater than 99.8 %, and As and Se removal rates are 98.6 % and 97.2 %, respectively. Over 99.5 %tellurium can be recovered by SO2 reaction when the operation is conducted at 85 °C in 6 mol L-1HCl solution.The tellurium powder with size of \5 lm and purity of[99.999 % is obtained.     

Recovering metals from hydrometallurgical residues

Experimental results and a method for recovering Cu, Zn, Cd, and Co from a solid hydrometallurgical residue are presented. A series of leaching, oxidation, and solvent extraction stages are the keys to the process.     

Removing and stabilizing as from copper refining circuits by hydrothermal processing

Experimental testwork has shown that arsenic can be removed from arsenic-bearing solutions by hydrothermal precipitation at temperatures in the 170–200°C range. The presence of Fe(III) is required for combination with As(V) to form the crystalline hydrated ferric arsenate known as scorodite (FeAsO₄·2H₂O). The contained arsenic is effectively immobilized by incorporation into a crystalline, low-solubility compound. Process options are suggested for disposing of arsenic in copper electrorefinery bleed liquors. For more information, contact A. J. Monhemius, Imperial College of Science, Technology and Medicine, Royal School of Mines, Prince Consort Road, London SW7 2BP, United Kingdom; telephone 44-171-594-7329; fax 44-171-594-7444; e-mail j.monhemius@ic.ac.uk.     

Recycling of WC-Co hardmetal sludge by a new hydrometallurgical route

A hydrometallurgical process based on aqua regia treatment of WC-Co hardmetal sludge was developed to simultaneously extract cobalt in solution and forming tungstic acid as residue in a single step. The parameters such as aqua regia concentration, temperature and time of reaction, and pulp density were optimized to process the sludge containing 60.9 wt.% W, 5.99 wt.% Co, 3.38 wt.% Fe and 12.64 wt.% C as the major components. Almost complete leaching of cobalt was achieved with 100 vol.% of aqua regia at 100 °C temperature, 60 min reaction time and 400 g/L pulp density. Complete conversion of tungsten carbide of the sludge to tungstic acid was observed at and below the pulp density of 150 g/L under this condition. The progress of reaction and conversion of tungsten carbide to tunstic acid (H₂WO₄) were investigated by XRD phase identification of the residues under different conditions. The tungstic acid produced from the acid treatment was purified by dissolving tungsten in 11.20 mol/L of ammonia solution at 60 °C while rejecting insoluble metallic impurities as a residue. Tungsten from the ammoniacal solution was recovered by evaporation-crystallization process as high purity (99.97%) ammonium paratunstate (APT, (NH₄)₁₀·H₂W₁₂O₄₂·4H₂O) with low levels of impurities.     

用剪切絮凝法脱除高岭石中的赤铁矿

采用剪切絮凝工艺,可有效脱除高岭石中的赤铁矿。Ａｕｇｅｒ电子能谱研究表明,油酸钠能够化学吸附于赤铁矿表面使其疏水,通过对赤铁矿颗粒间总作用势能的计算,推测赤铁矿在剪切搅拌力场的作用下发生疏水作用是其絮凝的主要原因,而在同样的条件下高岭石与油酸钠未发生相互作用,其颗粒仍保持高度的分散。     

Optimization of brine leaching of metals from hydrometallurgical residue

An orthogonal array,L16(45),was used to examine the effects of four parameters,including NaCl concentration,H2SO4 concentration,temperature and pulp density,on the recovery of Cu,In,Pb and Zn from a hydrometallurgical residue via brine leaching.The results show that temperature of leaching solution has a significant effect on the recovery of Cu,In and Zn,while H2SO4 concentration has an obvious influence on these metals extraction.Both pulp density and NaCl concentration significantly affect Pb extraction.Based on the orthogonal array experiments,the optimum conditions for the extraction of Cu,In,Pb and Zn from hydrometallurgical residue are NaCl concentration of 250 g/L,H2SO4 concentration of 1.00 mol/L,temperature of 85℃,and pulp density of 100 g/L.After 1 h of treatment at these optimum conditions,over 91% of the metals are extracted from the residue.Brine leaching is therefore suitable for the recovery of metals from hydrometallurgical residues.     

Kinetics of simultaneous leaching of Ag and Pb from hydrometallurgical zinc residues by chloride

The leaching kinetics of silver and lead simultaneously from zinc residue by chloride was investigated.The effects of stirring speed,temperature,sodium chloride concentration,particle size and liquid/solid ratio on Ag and Pb dissolution in sodium chloride were studied.It was determined that the dissolution rates increased with increasing sodium chloride concentration,temperature and decreasing particle size.The dissolution kinetics followed a shrinking core model,with inter-diffusion through gangue layer as the rate determining step.This finding is in accordance with the apparent activation energy(Ea)of 26.8 kJ.mol-1(Ag)and 26.5 kJ.mo1-1(Pb),and a linear relationship between the rate constant and the reciprocal of squared particle size.The orders of reaction with respect to sodium chloride concentration,temperature and particle size were also achieved.The rate of reaction based on diffusion-controlled process can be expressed by semi-empirical equations.     

The hydrometallurgical extraction of lithium from egyptian montmorillonite-type clay

The processing of El-Fayoum montmorillonite-type clay deposits is attained through leaching with commercial sulfuric acid using a ball-mill-type autoclave. This process yields lithium sulfate, which can be used either for the production of lithium carbonate or to produce lithium metal. The effects of temperature, grain size, and sulfuric acid concentration and leaching on lithium recovery as well as the kinetics of the leaching process have been studied.     

The hydrometallurgical extraction of rhenium from copper industrial wastes

An attempt has been made in this investigation to develop a wet chemical method for treating a rhenium-containing lead slime produced during copper manufacture. The effects of temperature, grain size, oxygen partial pressure, and leaching time as well as the kinetics of the leaching process were studied.     

生物吸附-沉降法去除电镀废水中镉

以水沈废啤酒酵母为吸附剂,采用吸附-沉降法,研究水洗废啤酒酵母对电镀废水中镉的吸附规律及沉降效果.结果表明,在废水中镉含量为26mg/L、pH7、水洗废啤酒酵母用量40g/L(含水约72%)、室温(约18℃)、搅拌速度800r/min、吸附时间30min、沉降3.5h的条件下,废水中镉的吸附率及吸附-沉降后镉的去除率均达96%以上.并采用透射电子显微镜、电动电位及红外光潜分析手段,分析水洗废啤酒酵母对镉的吸附机理.水洗废啤酒酵母对镉的吸附不仅发生菌体表面,也发生在菌体内部.吸附过程存在化学络合、静电吸引、氢键等作用.     

铂钯精矿湿法分离Bi、Fe富集贵金属工艺

以铜阳极泥分铜液还原所得铂钯精矿为原料,根据其矿物特性选择HCl作为浸出剂湿法脱除Bi、Fe等主要贱金属元素,富集Au、Ag、Pt、Pd等贵金属;通过热力学计算绘制Bi(Ⅲ)、Fe(Ⅲ)在盐酸体系的组分分布图,实验考察了HCl浓度、Cl-浓度、反应温度和时间等因素对Bi、Fe浸出率的影响.结果表明:在HCl浓度为2 m...     

Removing cadmium from electroplating wastewater by waste saccharomyces cerevisiae

The appropriate condition and scheme of removing cadmium from electroplating wastewater were investigated by adsorption-precipitation method using waste saccharomyces cerevisiae（WSC） as sorbent. Effect factors on biosorption of cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae and precipitation process of waste saccharomyces cerevisiae after adsorbing cadmium were studied. The results show that removal rate of cadmium is over 88% after 30 min adsorbing under the condition of cadmium concentration 26 mg/L, the dosage of waste saccharomyces cerevisiae 16.25 g/L, temperature 18℃, pH 6.0 and precipitation time 4 h. Biosorption-precipitation method is effective to remove cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae. The SEM, infrared spectroscopy and Zeta-potential of the cells show that chemical chelating is the main adsorption form; electrostatic attraction, hydrogen bonding and van der Waals force all function in adsorption process; and -NH2-,-C=O-,-C=O-NH-,-CH3, -OH are the main adsorption groups.     

Na2S选择性浸出铜转炉烟灰中的砷及Fe2(SO4)3稳定化砷(英文)

研究砷(As₂O₃)的Na₂S碱性浸出,以及用Fe₂(SO₄)₃沉淀砷。采用基于中心组合设计的响应面法对相关因素的影响进行定量和定性分析,提出用于参数优化的统计模型。结果表明,在Na₂S浓度100 g/L,固液比0.163 g/mL和温度80℃的最优预测条件下,89%的砷可从烟灰中去除。研究发现,固液比和Na₂S浓度是影响浸出过程的显著因素。在沉淀过程中,当pH为4.8、Fe³⁺与砷的摩尔比和H₂O₂与砷的摩尔比分别为5:1和4:1时,浸出液中99.93%以上的砷以无定形砷酸铁的形式被除去。Fe³⁺与砷的摩尔比和pH值为最显著因素,而且他们之间的相互作用也是显著的。     

利用旋转磁场去除铝熔体中的夹杂物颗粒

研究了旋转磁场去除液态铝合金熔体中夹杂物颗粒的效果.将铝硅过共晶合金凝固过程中析出的初生硅颗粒视为夹杂物颗粒.采用旋转磁场,研究了密度比周围铝熔体密度大的初生硅夹杂物颗粒在旋转磁场下的分布规律.利用光学显微镜和数码相机对凝固试样的宏观及微观组织进行观察.实验结果表明:旋转磁场可以有效去除液态铝合金熔体中的夹杂物颗粒,并且旋转磁场的除杂效果随着磁场频率的增大而显著增加.因此旋转磁场提供了一种高效的金属熔体净化的方法.     

Removing impurities from secondary alumina

Wet magnetic separation of a partly deagglomerated fines fraction of secondary alumina is an efficient way of separating the impurities P, S, Ti, V, Fe, and Ni from the process stream without sacrificing fluorine reclamation, and without significant loss of Al₂O₃. Although it is not carried out on an industrial scale today, increased purity requirements or deposition problems may make this process profitable.     

含硫砷金矿一段焙烧脱除硫和砷的热力学研究

采用热力学软件FactSage7.0研究了某含硫砷金矿焙烧的热力学行为,探索一段焙烧脱除硫和砷的可行性。模拟结果表明,在较窄的氧含量范围内,可在较宽温度范围内实现硫、砷的一段焙烧脱除;氧含量过高时,改变焙烧温度不能实现硫和砷的同时脱除;通过添加适量的碳、或通入一氧化碳,可还原硫酸盐和砷酸盐,提高硫和砷的一段焙烧脱除率。     

Removal of iron and aluminum impurities from metallurgical grade-silicon with hydrometallurgical route

A new method for production of solar grade silicon（SoG-Si） at low cost from metallurgical grade silicon （MG-Si） via vacuum metallurgical technique was proposed, which is a promising process to feedstock solar energy silicon material independence of traditional Siemens method. In this procedure, pre-treatment of MG-Si using hydrometallurgical routes to remove the metallic impurities such as iron and aluminum to reduce the production cost is an important process. The influences of acid agents, acid concentration, reaction time and temperature and particle size of raw material ground on the removal efficiency of iron and aluminum impurities were investigated, respectively. The results show that the optimum operation conditions for leaching in acid C are： acid concentration 6 mol/L, temperature 60 ℃, time 4 d, diameter for raw material 50 μm. The removal efficiencies of impurities iron and aluminum are up to 85% and 75%, respectively.