Kinetics of indium dissolution from marmatite with high indium content in pressure acid leaching

The kinetics of oxygen pressure acid leaching marmatite with high indium content was studied. The effects of particle size, agitation rate, temperature, H_2SO_4 concentration, and oxygen partial pressure on leaching rate of indium were investigated. The results show that when the agitation rate is above 600 r-min~(-1), its influence on indium leaching rate is insignificant. It is determined that the leaching rates increase with the increase in sulfuric acid concentration, temperature, partial oxygen pressure, and the decrease in particle size. Moreover, the results demonstrate that the process of indium leaching is controlled by interface chemical reaction, with apparent activation energy of 65.7 k J-mol~(-1). The apparent reaction orders of sulfuric acid and oxygen partial pressure are determined to be 0.749 and 1.260, respectively. The leaching reaction process follows shrinking unreacted core model. And finally, the kinetics model equation is established for indium.     

Effect of temperature,oxygen partial pressure and calcium lignosulphonate on chalcopyrite dissolution in sulfuric acid solution

The pressure leaching mechanism of chalcopyrite was studied by both leaching tests and in-situ electrochemical measurements. The effects of leaching temperature, oxygen partial pressure, and calcium lignosulphonate, on copper extraction and iron extraction of chalcopyrite pressure leaching were investigated. The leaching rate is accelerated by increasing the leaching temperature from 120 to 150 °C and increasing oxygen partial pressure to 0.7 MPa. The release of iron is faster than that of copper due to the formation of iron-depleted sulfides. Under the optimal leaching conditions without calcium lignosulphonate, the copper and iron extraction rates are 79% and 81%, respectively. The leaching process is mixedly controlled by surface reaction and product layer diffusion with an activation energy of 36.61 kJ/mol. Calcium lignosulphonate can effectively remove the sulfur passive layer, and the activation energy is 45.59 kJ/mol, suggesting that the leaching process with calcium lignosulphonate is controlled by surface chemical reactions. Elemental sulfur is the main leaching product, which is mixed with iron-depleted sulfides and leads to the passivation of chalcopyrite. Electrochemical studies suggest that increasing the oxygen partial pressure leads to increasing the cathodic reaction rate and weakening the passivation of chalcopyrite.     

反应合成制备Ag-Sn-O系电接触材料热力学分析

运用Gibbs Helmholtz方程进行了反应合成法制备AgSnO2复合材料的热力学计算和数据分析。结果表明：当反应温度小于505K时，反应合成属于固-固间的置换反应；当反应温度大于505K时，反应合成属于固-气间的氧化反应。通过计算500K～1200K范围内生成物SnO，SnO2单位体积生成自由能和分解氧分压，确定以Ag20，Ag，Sn等为原料，反应合成的最终产物为Ag和SnO2，不存在SnO相。通过数据分析为制定反应合成法制备AgSnO2复合材料的工艺参数提供了理论依据。     

Behavior of oxygen diffusion in buffer layers for coated conductors

We have evaluated the effect of annealing in oxygen atmosphere on the structure, texture and phase transformation of LZO films deposited on YSZ (yttria-stabilized zirconia) (0 0 l) single crystal substrates and textured NiW substrates by metal-organic deposition (MOD) method. The results show that the structure stability of the LZO films is heavily dependent on the oxygen partial pressure in annealing process. Then we have in details studied the behavior of oxygen diffusion in three kinds of buffer layer architectures on NiW substrates by varying the temperature, oxygen partial pressure and dwelling time in the annealing process. The oxygen diffusion within buffer layers leads to the oxidation of substrate, and even the texture and structure of buffer layers are destroyed with the increase of the thickness of the oxides layer related to NiW substrate. It reveals that the relative volume of oxides related to NiW substrate increases exponentially with the annealing temperature, and increases linearly with the annealing time at logarithmic scale. The relative intensity of texture peaks of buffer layers decreases and even disappears with the increase of the oxygen partial pressure in annealing process because of the acceleration of the oxidation reaction of substrate. The influence of annealing temperature, oxygen partial pressure and dwelling time on the oxygen diffusion is related to the intrinsic oxygen diffusion coefficient of buffer layers materials. Compared with the increase of oxygen partial pressure, the elongation of dwelling time shows a less effect on the oxidation rate of NiW substrate and a weak destruction of the texture of buffer layers. Except choosing the oxide materials with small oxygen diffusion coefficient as buffer layers in coated conductors, the degree of oxidation about NiW substrate could be greatly controlled and it would result in the less destruction of texture and structure of buffer layers by adjusting the annealing temperature, oxygen partial pressure and dwelling time in the process of YBCO deposition.     

Kinetics of oxidation-precipitation of cobalt(Ⅱ) from solution by ozone

In order to precipitate cobalt(II) in cobalt chloride solution, a novel method using ozone as the precipitant for its strong oxidability was proposed. The results show that the precipitation reaction is diffusion-controlled. The main factors affecting the oxidation rate such as the stirring speed, solution temperature, ozone partial pressure, initial concentration and flow rate were investigated. The kinetics equation of each condition was established. The results indicate that the oxidation rate is independent of the initial concentration or solution temperature. The oxidation rate increases obviously with increasing the stirring speed. The linear relationship between ozone partial pressure or flow rate and oxidation rate is found.     

热处理参数对LZO膜外延生长的影响

研究了热处理参数对LZO膜外延生长的影响。结果显示实验条件范围内,升高热处理温度、延长热处理时间和加快升温速度有利于提高(400)_(LZO)衍射峰的强度。相对于热处理温度、热处理时间和升温速度,LZO膜的织构类型对热处理时的氧分压十分敏感,氧分压直接影响到能否制备出具有单一织构成分的LZO膜。进一步分析显示,传统的形核生长理论可以很好地解释热处理温度、热处理时间和升温速度对LZO膜外延生长的影响。增加氧分压对LZO膜的外延生长存在双重作用,一方面提高氧分压可以降低膜中的积碳量,有利于LZO晶粒的长大,但另一方面,提高氧分压降低膜中的积碳后将导致对自发形核长大过程的抑制作用减弱,最终使得LZO膜不具有单一的立方织构。因此,更合理地控制/改变不同热处理阶段的氧分压才能在改善LZO膜生长动力学的同时又不影响其外延生长。     

微细浸染型金矿酸性热压氧化预处理动力学研究

以氧气消耗速率表征氧化速率,研究了微细浸染型硫化物金矿热压氧化预处理过程动力学的影响因素,考察了矿浆pH值、温度、矿样粒度、氧分压、气液界面面积和矿浆浓度对氧化速率的影响,以及氧化率和氧化速率的关系。结果表明,矿浆pH2.5时,保持较高的氧化速率;氧化速率随温度升高、氧分压增加和矿浆浓度降低而增大;增加气液接触面积可提高氧化速率,当矿浆浓度为33%、氧分压1.6 MPa,在优化条件下,气液接触比表面积达到25 m2/m3,40 min可完成氧化预处理。     

Kinetic study on pressure leaching of high iron sphalerite concentrate

The kinetics of pressure leaching high iron sphalerite concentrate was studied.The effects of agitation rate,temperature, oxygen partial pressure,initial acid concentration,particle size,iron content in the concentrate and concentration of Fe2 added into the solution on the leaching rate of zinc were examined.The experiment results indicate that if the agitation rate is greater than 600 r/min,its influence on Zn leaching rate is not substantial.A suitable rise in temperature can facilitate the leaching reaction,and the temperature should be controlled at 140-150℃.The increase trend of Zn leaching rate becomes slow when pressure is greater than 1.2 MPa,so the pressure is controlled at 1.2-1.4 MPa.Under the conditions of this study,Zn leaching rate decreases with a rise in the initial sulfuric acid concentration;and Zn leaching rate increases with a rise of iron content in the concentrate and Fe 2 concentration in the solution.Moreover,the experiment demonstrates that the leaching process follows the surface chemical reaction control kinetic law of“shrinking of unreacted core”.The activation energy for pressure leaching high iron sphalerite concentrate is calculated,and a mathematical model for this pressure leaching is obtained.The model is promising to guide the practical operation of pressure leaching high iron sphalerite concentrate.     

Phasengrenzreaktionen bei der Oxydation von Metallen. Hochtemperaturoxydation Dünner Nickelfolien

During the oxidation of nickel foils 5 μm thick in oxygen (1000–1200°C, oxygen partial pressure about 0·2–0·8 torr) a logarithmic rate law was observed. The apparent activation energy of the oxidation and the oxidation rate at the beginning of the reaction agree with the apparent activation energy and the double, extrapolated rate of the homomolecular oxygen exchange on NiO. Therefore the reaction of O₂ molecules with electrons at the interface may be discussed as the rate determining step of the high temperature oxidation of thin nickel foils.     

Kinetics of the dissolution of copper in aqueous alkaline 2,2-dipyridyl solutions

Kinetics of the dissolution of copper in aqueous alkaline 2,2^′-dipyridyl solutions was investigated at varying oxygen partial pressure, complexing agent concentration, temperature and pH of the solution. It has been found that the oxygen partial pressure was the basic parameter which limited the process rate.The pH in the solution is the second factor that influences the dissolution rate at elevated oxygen partial pressure (0.05 MPa). It may be assigned to formation of various forms of Cu-2,2^′-dipyridyl complex, depending on OH⁻ ion concentration. Such complexes vary distinctly in their stability constant values.     

Cu在BMIMBF_4离子液体中的溶解性

在不同氧分压和温度下,研究Cu片在BMIMBF_4离子液体中的溶解速率,并测定Cu~(2+)在BMIMBF_4离子液体中的饱和浓度。结果表明,Cu必须有氧存在才能溶解在BMIMBF_4离子液体中,且溶解速率随氧分压和温度的增加而加快。根据实验数据得到在25℃～70℃和2.10×10~4Pa的氧分压下,Cu溶解速率的表观活化能为21.76 kJ/mol,并建立Cu在BMIMBF_4离子液体中溶解的速率方程。     

A fundamental study of the kinetics of zinc oxidation in the temperature range 320–415°C in atmospheres of pure oxygen and oxygen doped with gaseous impurities

The oxidation of pure zinc in the temperature range 320–415°C was investigated gravimetrically. Oxidation in pure oxygen was found to obey parabolic rate equations in the temperature range 375–415°C and logarithmic time-dependence in the range 320–370°C. The oxidation rate at temperatures above 370°C was generally proportional to the logarithm of oxygen pressure, although this was not obeyed at all temperatures and pressures in this range. A reaction mechanism involving control of oxidation at the oxide/oxygen interface has been proposed with two rate-determining surface reactions of oxygen. One of these leads to a logarithmic rate equation and the other to parabolic kinetics.The results obtained from zinc oxidation in atmospheres of oxygen mixed with small concentrations of water, hydrogen, carbon dioxide, iodine and ammonia have also been explained with reference to this mechanism.     

氧压酸浸低品位富银硫化矿富集提取银和锌

由于含有大量的黄铁矿和白铁矿(它们约占原矿的70%,质量分数),以及闪铅矿一定程度上的氧化,云南澜沧铅矿股份有限公司所产的富银硫化矿难以富集.本文通过对该矿在90-170℃下氧压酸浸,以期连同后面的氰化能提取精矿中的银.通过进行2L高压釜的小型试验,考察了温度、酸度、碘化钠用量、氧分压、氧气流速对银和锌回收率的影响.结果表明,银的回收率取决于银是否进入黄钾铁矾渣,或者与碘化钠反应生成碘化银沉淀.在优化的条件下,银和锌的回收率分别达到71.5%和41.29%.     

Hochtemperaturkorrosion von Nickel in Chlor und Chlor-Sauerstoffgemischen

High temperature corrosion of nickel in chlorine and chloride oxygen mixtures Investigation of the chlorination and oxychlorination of nickel in a quartz ap-paratus at 600 to 850°C. In chlorine a surface layer of Ni chloride is formed which adheres well to the metal surface up to 75O°C, while it is damaged by spalling at higher temperatures. The reaction rate depends from temperature, chlorine partial pressure and flow velocity. The kinetic law is parabolic but undergoes a pronounced change at higher temperatures because of the sublimation of nickel chloride. In chlorine-oxygen mixtures there may be processes similar to combustion at chlorine contents as low as about 1.2 Vol.-%. This fact can be attributed to the hinderance by oxy-gen of the normally occurring dissociation of NiCl; this reaction is substituted by another one yielding on the one hand NiO, on the other hand chlorine.     

Kinetic process of oxidative leaching of chalcopyrite under low oxygen pressure and low temperature

Kinetic process of oxidative leaching of chalcopyrite in chloride acid hydroxide medium under oxygen pressure and low temperature was investigated. The effect on leaching rate of chalcopyrite caused by these factors such as ore granularity, vitriol concentration, sodium chloride concentration, oxygen pressure and temperature was discussed. The results show that the leaching rate of chalcopyrite increases with decreasing the ore granularity. At the early stage of oxidative reaction, the copper leaching rate increases with increasing the oxygen pressure and dosage of vitriol concentration, while oxygen pressure affects leaching less at the later stage. At low temperature, the earlier oxidative leaching process of chalcopyrite is controlled by chemical reactions while the later one by diffusion. The chalcopyrite oxidative leaching rate has close relation with ion concentration in the leaching solution. The higher ion concentration is propitious for chalcopyrite leaching.     

Cu-Al合金内氧化的热力学分析——Ⅰ热力学函数

对Cu-Al合金内氧化的热力学条件进行了分析，绘制了内氧化的热力学条件区位图。结果表明：区位图中择优氧化区位很大，范围由上、下限氧分压确定，其中：lgPO2(max)=(-1761l／T) 12．91,lgPO2(min)=(-55830／T)-(4／3)Ig[％Al] 19．95，但实际的内氧化区位是靠近上限PO2，的1个很小区域；溶度积Ksp和残余Al浓度都是极小量，内氧化可进行得很彻底；内氧化控制中温度和氧分压的调节必须同步；理想的内氧化工艺条件应是：采用1223K左右的高温，介质中的氧分压力求接近或等于上限PO2；为了避免氧化，降温过程宜采用通H2急冷的方法。     

Oxidation of cobalt at high temperature

Precise values of parabolic rate constants of cobalt oxidation have been determined over a wide range of temperature (950–1300°C) and oxygen pressure (6.58× 10^?4?0.658 atm). The dependence of the calculated values of parabolic rate constants k″_p on oxygen pressure and temperature can be described by the following empirical equation: $$k''_p = const. \cdot {\text{p}}_{O_2 }^{{\text{1/n}}} \cdot exp ( - {\text{E}}_{\text{k}} /RT)$$ The exponent 1/n decreases with an increase in temperature from 1/3.40 at 950°C to 1/3.96 at 1300°C, whereas the activation energy E_k decreases with an increase in the oxygen pressure from 41.7 to 38.1 kcal/mole.     

Cu-Al合金内氧化的热力学分析——Ⅱ热力学函数的应用

这是(Cu-Al合金内氧化的热力学分析》一文的第Ⅱ部分。对Cu-Al合金内氧化的热力学条件进行了分析，绘制了内氧化的热力学条件区位图。结果表明：区位图中择优氧化区位很大，范围由上、下限氧分压确定，其中：lgPo2max=(-17611／T) 12．91，lgPo2min=(-55830／T)-(4／3)lg[％Al] 19．95，但实际的内氧化区位是靠近上限Po2的一个很小区域；溶度积Ksp和残余Al浓度都是极小量，内氧化可进行得很彻底；内氧化控制中温度和氧分压的调节必须同步：理想的内氧化工艺条件应是：采用1223K左右的高温，介质中的氧分压力求接近或等于上限Po2;为了避免氧化，降温过程宜采用通H2急冷的方法。     

Thermodynamic evaluation of oxygen behavior in Ti powder deoxidized by Ca reductant

To produce low oxygen Ti powder of less than 1000 mass ppm, commercial Ti powder was deoxidized by two types of Ca reductants: a solid Ca and a Ca vapor. Compared with the iso-oxygen partial pressure in the Ti-O binary phase diagram, the P_O2 in the raw Ti powder increased with temperature compared to the reduction reaction of Ca. Therefore, the O₂ content in the Ti powder decreased as the deoxidation temperature increased from 873 K, showing a local minima at 1273 K. The oxygen concentration at 1373 K was greater than that at 1273 K because the oxygen solubility of the Ti powder was increased by the equilibrium relation between Ca and CaO. On the basis of the thermodynamic assessment, the deoxidation of Ti powder can be improved by increasing the temperature and lowering the oxygen solubility with the saturation of CaO.     

High-temperature oxidation of titanium-hydride powders

The oxidation kinetics of titanium-hydride powders were studied in the temperature range of 298–1378 K in air at atmospheric pressure. DTA, DSC, X-ray analysis, and scanning electron microscopy were used. Oxidation was found to take place by TiH_xO_y oxyhydride phases formation. The oxidation reaction rate at temperatures above 870 K was limited by diffusion of oxygen atoms through a rutile scale formed on the surface. The activation energy and preexponential values of the Arrhenius equation for different interaction stages as well as transformation enthalpies were calculated.