Leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system

The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69μm, holding at 80℃ for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2：1, and the ratio （g/mL） of solid to liquid being 1：10.     

低品位氧化锌矿在NH_3-NH_4HCO_3-H_2O体系中的浸出动力学研究（英文）

对高钙低品位氧化锌矿在NH3-NH4HCO3-H2O体系中的浸出动力学进行了系统研究.研究结果表明,氧化锌矿浸出过程遵循＂未反应核缩减＂模型,即遵循动力学方程：1-（1-α）1/3=k.t.反应的表观活化能Ea=6.489 kJ/mol,浸出过程由外扩散过程控制.增强搅拌强度、提高总氨浓度及反应温度均可加快该矿石中锌的浸出速率,并在一定范围内提高锌的浸出速率.     

Leaching kinetics of low-grade copper ore with high-alkality gangues in ammonia-ammonium sulphate solution

The leaching kinetics of low-grade copper ore with high-alkality gangues was studied in ammonia-ammonium sulphate solution. The main parameters, such as ammonia and ammonium sulphate concentrations, particle size, solid-to-liquid ratio and reaction temperature, were chosen in the experiments. The results show that the increase of temperature, concentrations of ammonia and ammonium sulphate is propitious to the leaching rate of copper ore. The leaching rate increases with the decrease of particle size and solid-to-liquid ratio. The leaching rate is controlled by the diffusion through the ash layer and the activation energy is determined to be 25.54 kJ/mol. A semi-empirical equation was proposed to describe the leaching kinetics.     

Dissolution kinetics of malachite in ammonia/ammonium sulphate solution

The dissolution kinetics of malachite was investigated in ammonia/ammonium sulphate solution. The effects of ammonia and ammonium sulphate concentration, pH, leaching time, reaction temperature, and particle size were determined. The results show that the optimum leaching conditions for malachite ore with a copper extraction more than 96.8% are ammonia/ammonium concentration 3.0 mol/L NH₄OH + 1.5 mol/L (NH₄)₂SO₄, liquid-to-solid ratio 25:1 mL/g, leaching time 120 min, stirring speed 500 r/min, reaction temperature 25 °C and particle size finer than 0.045 mm. The dissolution process of malachite with an activation energy of 26.75 kJ/mol is controlled by the interface transfer and diffusion across the product layer. A semi-empirical rate equation is obtained to describe the leaching process and the reaction orders with respect to concentration of ammonia and ammonium sulphate are 2.983 0 and 0.941 1, respectively.     

Zinc leaching from electric arc furnace dust in alkaline medium

Physical and chemical properties of electric arc furnace (EAF) dust from Tianjin seamless Pipe Company were measured and analyzed. The zinc leaching tests in alkaline medium were carried out under variation of leaching agent concentration, leaching temperature, leaching cumulative time and solid-to-liquid ratio. The thermodynamics and kinetics of the zinc leaching process were also analyzed. The results show that the EAF dust contains 10% (mass fraction) zinc and the median particle size is 0.69 μm. The zinc recovery of 73.4% is obtained under the condition of 90 °C, 6 mol/L NaOH, and 60 min leaching time. With the increase of concentration of NaOH and the cumulative time, zinc leaching will be significantly increased. The kinetics study demonstrates that the leaching reaction is chemically controlled and the reaction activation energy is 15.73 kJ/mol.     

Technological conditions and kinetics of leaching copper from complex copper oxide ore

The kinetic behavior of leaching copper from low grade copper oxide ore was investigated. The effects of leaching temperature, H₂SO₄ concentration, particle size of crude ore and agitation rate on the leaching efficiency of copper were also evaluated. And the kinetic equations of the leaching process were obtained. The results show that the leaching process can be described with a reaction model of shrinking core. The reaction can be divided into three stages. The first stage is the dissolution of free copper oxide and copper oxide wrapped by hematite-limonite ore. At this stage, the leaching efficiency is very fast (leaching efficiency is larger than 60%). The second stage is the leaching of diffluent copper oxides, whose apparent activation energy is 43.26 kJ/mol. During this process, the chemical reaction is the control step, and the reaction order of H₂SO₄ is 0.433 84. The third stage is the leaching of copper oxide wrapped by hematite-limonite and silicate ore with apparent activation energy of 16.08 kJ/mol, which belongs to the mixed control.     

Leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate as oxidant

The leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate was studied.The effects including leaching temperature, reaction time, particle size, stirring speed, and concentrations of sulfuric acid and sodium peroxodisulfate were investigated. The leaching process of molybdenum from Ni-Mo ore is controlled by the chemical reaction through the solid layer across the unreacted shrinking core. The apparent activation energy of the leaching of molybdenum is calculated to be 41.0 k J/mol and the leaching kinetics equation of molybdenum from Ni-Mo ore is expressed as1-(1-a)1/3=3405.7exp[-41030.0/(RT)]t.     

Kinetics of nickel leaching from roasting-dissolving residue of spent catalyst with sulfuric acid

Sulfuric acid leaching process was applied to extract nickel from roasting-dissolving residue of a spent catalyst, the effect of different parameters on nickel extraction was investigated by leaching experiments, and the leaching kinetics of nickel was analyzed. The experimental results indicate that the effects of particle size and sulfuric acid concentration on the nickel extraction are remarkable; the effect of reaction temperature is mild; while the effect of stirring speed in the range of 400–1 200 r/min is negligible. Decreasing particle size or increasing sulfuric acid concentration and reaction temperature, the nickel extraction efficiency is improved. 93.5% of nickel in residue is extracted under suitable leaching conditions, including particle size (0.074–0.100) mm, sulfuric acid concentration 30% (mass fraction), temperature 80 °C, reaction time 180 min, mass ratio of liquid to solid 10 and stirring speed 800 r/min. The leaching kinetics analyses shows that the reaction rate of leaching process is controlled by diffusion through the product layer, and the calculated activation energy of 15.8 kJ/mol is characteristic for a diffusion controlled process. Foundation item: Project (50574101) supported by the National Natural Science Foundation of China; Project (2003UDBEA00C020) supported by the Collaborative Project of School and Province of Yunnan Province, China     

冶金污泥中铜锌镉铅的氨水和碳酸铵选择性浸出分离

为了将冶金污泥中的有价金属资源化并合理回收与利用,用采用氨水和铵盐复配对冶金污泥中的铜、锌、镉和铅进行选择性浸出,并且通过单因素条件试验分别考察铵盐种类、氨水和铵盐复配体系作为浸出剂中氨水和铵盐各自的浓度、浸出反应的温度和浸出反应时间等因素对铜、锌、镉和铅浸出率的影响,从而通过对比得出最佳的金属浸出工艺条件:复配体系中铵盐选择为碳酸铵,浓度为0.5mol/L,缓冲剂氨水浓度为3mol/L,反应温度为50℃,浸出反应时间时间为120min.在此条件下,铜、锌和镉的浸出率分别为91.51%、85.13%和89.51%,而铅的浸出率则低于6.00%,本工艺可以实现铜、锌和镉的回收同时可以实现对铅元素的基本分离.     

氨络合物体系中镍阴极电沉积的电化学行为

通过极化曲线测量，对氨络合物体系中镍阴极电沉积电化学行为进行研究，系统探讨了溶液中总镍离子浓度、氨水浓度、氯化铵浓度、阴离子及温度等工艺条件对镍阴极还原的影响。研究结果表明：镍放电电流随着总镍离子浓度的上升而上升，随氨水浓度的升高而降低；在1—4mol／L氯化铵浓度范围内，镍放电电流随其浓度的降低而升高，而当氯化铵浓度低于1mol／L时，镍放电电流出现下降的现象；氯盐氨络合物体系中镍阴极放电电流明显高于硫酸盐氨络合物体系镍放电电流，镍放电电流随温度的升高而升高。根据实验现象，进一步分析了镍阴极电沉积电化学行为变化的原因。     

高硅氧化锌矿浸出工艺的研究

针对高硅氧化锌矿的处理进行了研究,提出了二段循环酸浸的湿法冶金工艺.通过条件优化实验确定一、二段浸出条件分别为:始酸浓度75g/L、温度70℃、液固比6∶1、浸出时间1.5 h;始酸浓度18g/L、温度60℃、液固比3∶1、浸出时间0.5 h.本试验采用一段六轮循环浸出及二段三轮循环浸出,运行稳定,锌的总浸出率达到93.4%.     

Leaching kinetics of acid-soluble Cr（VI） from chromite ore processing residue with hydrofluoric acid

Leaching kinetics of acid-soluble Cr(VI) in chromite ore processing residue (COPR) using hydrofluoric (HF) acid solution as a leaching agent was investigated for potential remediation of COPR with industrial waste water containing HF. The results show that HF can effectively destabilize the Cr(VI)-bearing minerals, resulting in the mobilization of Cr(VI) from COPR into the leachate. Particle size significantly influences the leaching of acid-soluble Cr(VI) from COPR, followed by leaching time, whereas the effects of HF concentration and leaching temperature are slight and the influence of stirring rate is negligible. The leaching process of acid-soluble Cr(VI) from COPR is controlled by the diffusion through the product layer. The apparent activation energy is 8.696 kJ/mol and the reaction orders with respect to HF concentration and particle size is 0.493 8 and −2.013 3, respectively.     

由锌焙砂制备活性氧化锌的研究

以锌焙砂为原料，经氨浸，除杂，沉锌，干燥，煅烧等工序制取了活性氧化锌．采用正交设计确定制备过程的最佳技术条件，使锌的浸出率达95％以上，总回收率达90％．产品中活性氧化锌的含量为99．4％，比表面积为75m^2／g，产品质量达到HG／72572-94一等品标准．该工艺具有操作简单、稳定、可靠、适应性强以及锌的转化回收率高、“三废”少、环境污染小、成本低、产品质量好等特点．     

Techniques of copper recovery from Mexican copper oxide ore

Mexican copper ore is a mixed ore containing mainly copper oxide and some copper sulfide that responds well to flotation. The joint techniques of flotation and leaching were studied. The results indicate that an ore containing 19.01% copper could be obtained at a recovery ratio of 35.02% by using sodium sulfide and butyl xanthate flotation. Over 83.33% of the copper oxide can be recovered from the tailings by leaching in suitable conditions, such as 1 h stirring at a temperature around 25 ℃ with a mixing speed of 500 r/min, an H2SO4 concentration of 1.0 mol/L and a mass ratio of the ore-slurry-liquid to solid (mL/mS) of 3. The overall yield of refined ore after flotation and leaching is over 89.18% of the copper, which is much better than sole flotation or leaching. A copper product containing more than 99.9% copper was obtained by using the process: flotation-agitation leaching-solvent extraction-electro-winning.     

碳酸锌的沉淀及分解制备活性氧化锌

以硫酸铵-氨水浸出次级氧化锌,对浸出液进行除杂、蒸氨处理,以此溶液为原料,试验二氧化碳压力对碳酸锌沉淀的影响,以及碳酸锌的热分解条件对氧化锌粒度和比表面的影响。结果表明：高的二氧化碳压力可缩短沉锌的时间,增加碳酸锌堆积密度,有利于碳酸锌分解成氧化锌,并能减小氧化锌粒度;低温分解可得到较高的比表面,具有好的活性,高的二氧化碳压力所沉淀的碳酸锌最佳分解温度为300~320℃,分解时间4~5 h。     

用硫酸同时浸出会东闪锌矿与软锰矿的动力学研究

本文研究了常压下用硫酸同时浸出会东闪锌矿与软锰矿,考察了浸出时间、温度、初始酸度、闪锌矿的初始粒径等对同时浸出的影响。并对实验结果作了讨论,推导出了同时浸出的经验动力学方程式。     

氨浸置换法资源化废杂铜的研究

采用碳铵浸取-置换沉积新方法资源化、无害化回收废杂铜.考察浸取时间、氨水浓度、碳酸铵用量、催化剂用量对浸取效果的影响,并讨论还原剂用量、置换时间及搅拌速度对沉积过程的影响.结果表明:在(NH4)2CO3:6.5 g,NH3.H2O:6 mol/L、浸取催化剂:12 mL、浸取时间3 h的最优条件下,铜、锌的浸取率分别达到93.12%、95.03%,而伴生元素留在滤渣中.二段置换沉积过程中,在最佳工艺条件下,制备出产品纯度与附加值高的铜粉和七水硫酸锌.铜的回收率达到98.3%.该工艺具有操作简单、生产效率高、成本低、无污染等特点.     

砷灰的提纯工艺

采用湿法-火法对粗砷进行提纯,在氨水溶液浸出浓度为5～6 mol/L,液固比为1.7～2.2,浸出温度为50～65℃,浸出时间为3～4 h的工艺条件下,砷的浸出率可达95%以上,浸出液经蒸发结晶得到亚砷酸氢铵,亚砷酸氢铵经烘干后在500℃下分解得白砷产品,纯度可达99.5%以上,浸出剂氨经蒸发得到回收。该工艺无三废排放,原料消耗少,具有较好的经济和环境效益。     

超声波强化锌浮渣浸出的研究

研究了超声波强化草酸浸出锌浮渣的工艺，并分析和讨论了超声波辐射强度、辐射时间和液固比对锌浮渣浸出率的影响，揭示了超声波辐射浸出锌浮渣浸出率的影响规律。试验表明利用超声波强化浸出锌浮渣可大大提高了锌浮渣的浸出率，缩短了浸出时间。     

Comparative analysis of the dissolution kinetics of galena in binary solutions of HCl/FeCl3 and HCl/H2O2

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken.The dissolution kinetics of the galena was found to depend on leachant concentration,reaction temperature,stirring speed,solid-to-liquid ratio,and particle diameter.The dissolution rate of galena ore increases with the increase of leachant concentration,reaction temperature,and stirring speed,while it decreases with the increase of solid-to-liquid ratio and particle diameter.The ac...