A kinetic study on nonoxidative dissolution of sphalerite in aqueous hydrochloric acid solutions

The nonoxidative leaching of sphalerite in aqueous acidic solutions was studied from a kinetic point of view. Also the selective nonoxidation leaching in a hydrochloric acid solution containing a large amount of sodium chloride was examined for a Pb-Zn sulfide bulk concentrate. The dissolution rates of sphalerites from five different mines appeared to be controlled by a chemical reaction on the surface of sphalerite. The dissolution rate of sphalerite is of the first order with respect to the hydrogen ion activity of the solutions. It is also considerably affected by the iron content of the sphalerite sample; a linear relationship was observed between iron content of the sphalerite and its dissolution rate. The addition of sodium chloride to the hydrochloric acid solutions greatly enhanced dissolution rates. Compared to the dissolution rates of galena, which were reported in a previous paper, the dissolution rates of sphalerite were found to be far slower. The difference in the dissolution rates between these two minerals becomes greater with the addition of sodium chloride to the hydrchloric acid solutions. Based on these findings, the selective leaching of Pb-Zn bulk concentrate in a hydrochloric acid solution containing a large amount of sodium chloride was examined. The experimental results clearly showed that the galena was selectively leached, leaving a residue of sphalerite. NORIO MISAKI formerly Graduate student, Kyoto University     

The Leaching of Hematite in Acid Solutions

The reactions of hematite in aqueous hydrochloric acid, perchloric acid, and sulfuric acid solutions with or without the addition of common or uncommon salts were studied using monosized particulates in a well-stirred reactor and dilute solid concentration to obtain fundamental details of the reaction kinetics. The experimental rate data suggest that the entire leaching reaction is controlled by a chemical process. The leaching rate of hematite was seen to be first order with respect to hydrogen ion activity, a(H⁺), in hydrochloric acid or perchloric acid solutions, with or without the addition of common salts, while the rate was of a half order in sulfuric acid solutions with or without the addition of sodium sulfate. A theoretical analysis showed that the anions next to the surface in the double layer were chloride ion and perchlorate ion in hydrochloric acid and perchloric acid solutions, respectively, and sulfate ion in sulfuric acid solutions, with or without the addition of sodium sulfate. The fact that the leaching rates of hematite were quite different in various acids having identical α(H⁺ values indicates the importance of anion adsorption. The dependency of the leaching rate upon α(H⁺) appeared to be controlled by adsorbed anions next to the surface in the double layer. TAKUMI MISHIMA, formerly Graduate Student, Kyoto University     

Kinetics of galena leaching in hydrochloric acid-chloride solutions

This article presents a series of studies on the nonoxidative leaching of galena with hydrochloric acid in the presence of a metallic chloride. A systematic study was carried out using a succession of metallic chlorides with cations of different valencies in an attempt to generalize the leaching behavior of these solutions. The reaction order for leaching galena, in terms of the mean ionic activity of HCl, is 3/2 over a wide range of concentration. The addition of soluble chlorides to a HCl solution increases the leaching rate of the galena by augmenting the mean ionic activity of the acid. A reaction order of 3/2 for the mean HCl activity in the solution is maintained for solutions in which the acid concentration is constant and the metallic chloride varies, as well as for the opposite situation. Therefore, the only activity that must figure in the kinetic equation is that of the HCl. The activation energy (58.5 kJ/mole) is independent of the chloride used to increase the activity of the hydrochloric acid. The same is true for the Arrhenius prefactor.     

Acid dissolution of cupric oxide

The rates of dissolution of synthetic cupric oxide in solutions containing perchloric, sulfuric, nitric or hydrochloric acid were studied using sintered disks. In each case, the dissolution rate increased with elapsed retention time until an essentially constant value was reached. This phenomenon can be attributed to an increase in the disk’s effective surface area. The dissolution rate is of the first order with respect to a_H ⁺ for perchloric, nitric, and hydrochloric acids, while it is of a half order for sulfuric acid. High activation energies, ranging from 12.4 to 20.5 kcal/mol, and the independence of agitation speed on cupric oxide dissolution reaction rate suggest that chemical reactions are the major determinants of dissolution rates. The addition of electrolytes having anions common with the acids resulted in an acceleration of the dissolution rate due to increases in a_H ⁺ values. However, the addition of electrolytes of noncommon anions revealed a quite different effect on dissolution rate. This suggests that the adsorption and/ or complexing of anions on the cupric oxide surface may have had a significant role in the determination of the dissolution rates. The type of acid used determined the identity of the adsorbed anion.     

The kinetics of leaching galena with ferric nitrate

The kinetics of leaching galena with ferric nitrate as oxidant has been studied. Experimental results indicate that the rate of galena dissolution is controlled by surface chemical reaction. Rate is proportional to the square root of the concentration of ferric ion. The addition of more than one mole/liter sodium nitrate decreases reaction rate. With nitrate additions below this concentration, rate either remains constant or is slightly enhanced. An activation energy of 47 kJ/mol was measured, and rate is proportional to the inverse of the initial size of galena particles. These results are explained in terms of mixed electrochemical control. The anodic reaction involves the oxidation of galena to lead ion and elemental sulfur, and the cathodic reaction involves the reduction of ferric ion to ferrous ion.     

Kinetic study of the dissolution of cuprite in oxyacid solutions

The rates of disproportionation dissolution of three artificial cuprite samples were measured in sulfuric acid and perchloric acid solutions, from which oxygen had been stripped, at different concentrations and temperatures. Samples were prepared by electrolysis, sintering of electro-lytically produced cuprite, and oxidation of hot-rolled copper sheets. The effects of sodium sulfate and sodium perchlorate on the dissolution of cuprite were also examined. Metal copper formed by the disproportionation reaction plays a role as a barrier for further dissolution of cuprite. Apparent activation energies were determined in the temperature range of 293 to 323 K for the initial stage of the disproportionation reaction of cuprites. The values ranged from 14.7 to 24.9 kJ mol^-1 in 0.003 mol dm^-3 sulfuric acid and perchloric acid and from 29.7 to 52.0 kJ mol^-1 in 0.1 mol dm^-3 sulfuric acid and perchloric acid. Judging from the effects of temper-ature, agitation speed, acid concentration, and common salt additions, it is concluded that the adsorption of H⁺ onto the surface site is important in determining the dissolution rate of cuprite in oxyacid solutions. The dissolution behaviors of different cuprite samples were also morpho-logically examined.     

Kinetics of nonoxidative leaching of galena in perchloric,hydrobromic, and hydrochloric acid solutions

Several kinetic studies are presented on the nonoxidative leaching of galena with solutions of hydrocloric, hydrobromic, and perchloric acid. The kinetic parameters were set up in terms of the mean ionic activities of the electrolytes. The apparent order of reaction for the mean ionic activity of perchloric acid is one. For hydrochloric acid the order of reaction over a wide range of concentrations is 3/2 with respect to its mean activity. For hydrobromic acid, whose anion has greater complex-forming power for lead than HC1, the order of reaction is 2. Activation energies are 64.4 kJ/mole for HC1, 71.5 kJ/mole for HC10₄, and 66.5 kJ mole for HBr. The complete kinetic equations are given for the three reactions.     

Kinetics of nonoxidative leaching of galena in perchloric, hydrobromic, and hydrochloric acid solutions

Several kinetic studies are presented on the nonoxidative leaching of galena with solutions of hydrocloric, hydrobromic, and perchloric acid. The kinetic parameters were set up in terms of the mean ionic activities of the electrolytes. The apparent order of reaction for the mean ionic activity of perchloric acid is one. For hydrochloric acid the order of reaction over a wide range of concentrations is 3/2 with respect to its mean activity. For hydrobromic acid, whose anion has greater complex-forming power for lead than HC1, the order of reaction is 2. Activation energies are 64.4 kJ/mole for HC1, 71.5 kJ/mole for HC10₄, and 66.5 kJ mole for HBr. The complete kinetic equations are given for the three reactions.     

Kinetics of galena dissolution in nitric acid solutions with hydrogen peroxide

The extraction of lead from a galena concentrate in nitric acid solutions with additional hydrogen peroxide was studied taking stirring speed, temperature, hydrogen peroxide and nitric acid concentrations, and particle size as dissolution parameters. The dissolution curves followed the surface chemical reaction controlled shrinking core model over the whole range of parameters, except at high nitric acid concentrations where the reaction was diffusion-controlled. The activation energy of 42 kJ mol^− 1 and a linear relationship between rate and inverse particle size support the reaction controlled dissolution mechanism. Hydrogen peroxide addition accelerated the reaction compared with nitric acid alone. It was concluded that the dissolution process is favourable, since the acid consumed for oxidation of galena can easily be regenerated in the same reactor by means of hydrogen peroxide.     

Complex Processing of Wastes Generated in Chrysotile Asbestos Production

A new recycling technology has been studied in this work to produce magnesium chloride from wastes generated in chrysotile asbestos production. The steps include enrichment of raw material by sizing, leaching of magnesium with hydrochloric acid, purification of solution from impurities of iron and nonferrous metals, and the production of magnesium chloride solutions. Thermodynamic analysis shows the possibility of dissolution of magnesium compounds in the waste by hydrochloric acid. Magnesium chloride solution is subjected to hydrolytic purification from iron and nickel. Enrichment has been carried out with material particle size of 0.25 mm and liquid to solid ratio of 4:1 and leaching with 25% concentrated hydrochloric acid has been accomplished with a stoichiometric flow rate. Hydrolytic treatment was carried out at a pH 7.5–8.0. pH adjustment was carried out by magnesium oxide. Extraction of 92% of magnesium from serpentinite was achieved.     

Kinetic study of nonoxidative leaching of cinnabar ore in aqueous hydrochloric acid-potassium iodide solutions

Results obtained in a kinetic study of nonoxidative leaching of cinnabar ore in aqueous hydrochloric acid-potassium iodide solutions and the basic reactions in a new process of cinnabar treatment for obtaining mercury are presented. Experiments were performed at stirring speeds fast enough to eliminate the effect of this variable in the overall reaction rate. Under these experimental conditions the dissolution rate appears to be controlled by chemical reaction on the cinnabar surface. An activation energy of 42.3 kJ/mole was found. The dissolution rate is of the first order with respect to hydrochloric acid activity and of second order with respect to potassium iodide activity. The reaction rate in the different leaching conditions was established through weight loss of very pure cinnabar spheres submerged in the attack solution for known periods of time.     

The solubility of aqueous lead chloride solutions

Data are presented for the solubility of lead in acidic solutions of between 5 and 10 M chloride concentration, present as the salts of copper (II) and either sodium or calcium. Cooling these solutions from boiling point to 20°C precipitates approximately two thirds of the lead as PbCl₂ crystals of >99% purity. The solubility of PbCl₂ is shown to depend upon the activity of the lead and chloride ions in solution, and can be predicted from known thermodynamic constants. This has been tested for solutions containing only one cation, other than lead, at 25°C. This approach accurately predicts the lead solubility in solutions of calcium chloride but needs improving before it can be applied to sodium chloride solutions and hydrochloric acid.     

EDTA滴定法测定锑铋精矿中铋

对采用盐酸、硝酸和高氯酸溶样方式能溶解铋精矿而不能溶解成分较为相似的锑铋精矿的原因进行了探讨。采用X射线衍射仪(XRD)分别对铋精矿和锑铋精矿进行物相分析,结果表明造成锑铋精矿溶解不完全的原因可能是锑铋共生矿物的不完全溶解。针对这一问题,实验对该溶样方法进行了改进,采取盐酸、硝酸和高氯酸预溶解样品,高氯酸冒烟后补加3次盐酸和氢溴酸继续溶解样品的方法进行溶样。实验表明,采用改进后的方法溶解锑铋精矿样品,所得样品溶液中均有少许灰色不溶渣,但无黑色不溶物。采用焦硫酸钾熔融-酸溶法处理灰色不溶渣后用原子吸收光谱法(AAS)对其中铋进行测定,经计算,灰色不溶渣中铋含量与样品中铋含量的比值不大于0.2%,即灰色不溶渣中的铋可忽略不计。据此,采用上述改进方法进行溶样,建立了EDTA滴定法测定锑铋精矿中铋的方法。对样品量进行了优化,最终选择样品量为0.3g。探讨了锑铋精矿样品中高含量锑对测定的干扰,结果表明,样品中大部分的锑已在溶样过程中挥发出去,而留在样品溶液中的锑也不干扰测定。将实验方法应用于锑铋精矿样品中铋的测定,测定结果的相对标准偏差(RSD,n=8)为0.22%~0.47%,加标回收率在99%~101%之间,所得结果与电感耦合等离子体原子发射光谱法(ICP-AES)的测定值相吻合。     

电感耦合等离子体原子发射光谱法测定锂离子电池三元正极材料LiNi1-x-yCoxMnyO2中钠

在锂离子三元正极材料LiNi_1-x-yCo_xMn_yO₂中,钠离子会占据锂离子的位置,钠离子的存在会降低材料的克容量,因此需要严格控制材料中钠含量。在研究采用电感耦合等离子体原子发射光谱法(ICP-AES)测定锂离子三元正极材料LiNi_1-x-yCo_xMn_yO₂中的杂质元素钠含量的条件包括样品的溶解方法、测定介质盐酸的浓度、称样量、仪器参数基础上、建立了锂离子三元正极材料LiNi_1-x-yCo_xMn_yO₂中钠的测定方法。方法无需进行基体匹配、添加消电离剂等烦琐操作步骤就能得到准确、稳定的测量结果。方法的回收率在97.8%~103.6%之间,样品分析结果相对标准偏差小于2.5%,完全能够满足三元正极材料分析的要求。     

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 activation energy (Ea) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3/8.06 M HCl,and it suggests the surface diffusion model for the leaching reaction,while the Ea value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H202/8.06 M HC1,which suggests the surface chemical reaction model for the leaching reaction.Furthermore,the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two eases.Finally,the rate of reaction based on the reaction-controUed process has been described by a semiempirical mathematical model.The Arrhenius and reaction constants of 11.023 s-1,1.25×104 and 3.65×102 s-1,8.02×106 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H202/8.06 M HCl binary solutions,respectively.     

离子色谱法测定电子工业用高纯盐酸中痕量硫酸根离子

电子纯试剂(高纯盐酸)是电子化学品技术领域的关键性材料,建立一种电子工业用高纯盐酸中痕量硫酸根离子含量的离子色谱检测方法,对微电子技术发展具有重要意义.在高温条件下充分蒸发浓缩样品以除去其中的氯化氢和水,采用固相萃取柱银柱和钠柱分别除去除氯离子和金属离子,用超低压浓缩柱在线预富集,高容量阴离子分析柱分离测定,实现了离子...     

酸碱中和滴定法测定萤石中碳酸盐量

本方法在气体发生装置中用盐酸处理试料,Ba（OH）2溶液吸收产生的CO2,过量的碱用盐酸中和,加一定体积过量的盐酸标准滴定溶液以溶解BdCO3沉淀,再以甲基橙为指示剂,用NaOH标准滴定溶液返滴定测量碳酸盐量。通过进行氮气流量、氟离子干扰、硫离子干扰、盐酸对测量的干扰、BaCl2用量、标准物质回收等试验,确定最佳分析条件。该方法可直接反映萤石样品中碳酸盐的量,测量精度较好,可用于日常分析。     

Measurement of the activity of electrolytes and the application of activity to hydrometallurgical studies

The activity of HC1 in solutions of HCl-NaCl, and the approximate values of the activities of H⁺ and Cl⁻ in solutions of HC1, HC1O₄, HCl-NaCl, HClO₄-NaClO₄ and HC1O₄-NaCl were determined at 25 ° by measuring the electromotive force of a cell consisting of a Pt-Pt black electrode and an Ag-AgCl electrode. The liquid junction potential, estimated by using Henderson’s equation as a first approximation, was subtracted from the measured electromotive force of the cell. Some hydrometallurgical problems which were difficult to understand with the concept of concentration were re-examined, using the activity values thus determined. These problems were the rate of non-oxidative leaching of galena and sphalerite, the acid dissolution rate of cupric oxide, and the rate of oxidation of Fe(II) with molecular dissolved oxygen. Although the dependence of the dissolution rates of galena, sphalerite and cupric oxide upon acid concentration appeared to be rather complicated, the dissolution rates of these minerals were found to be of first order with respect to a_H+. It was also possible to elucidate the role of Cl⁻ ions by using thea _Cl-values. A rate equation obtained experimentally for the autoxidation of Fe(II) in HC1 solutions was found to generally explain the experimental results of previous researchers, which seemed to be inconsistent with each other. On leave-of-absence to the Department of Metallurgy and Material Science, University of Toronto, Ontario, Canada.     

Kinetics of the extraction of metals from deep-sea manganese nodules: Part I. the pore diffusion controlling case

The rate of dissolution of metal ions from two different deep-sea manganese nodule samples in dilute sulfuric acid solutions was studied. The addition of high concentrations of sodium and calcium salts was observed to increase the apparent kinetics of extraction and this has been interpreted in terms of the physical and chemical nature of nodules and their component minerals. The dissolution of copper and soluble cobalt was found to be very sensitive to the acid concentration and to be controlled by pore diffusion, while nickel dissolution was found to be controlled by chemical reaction. A pore model has been developed for the leaching of copper and cobalt. Formerly with the University of California, Berkeley.     

Tantalum sorption from chloride-fluoride solutions by anionites

The calculated and experimental data on sorption of tantalum ions from chloride-fluoride solutions by anionites of various classes and structures are considered and discussed. Based on the calculations carried out, it is shown that, in chloride-fluoride solutions, tantalum forms a whole series of complex ions, namely, chloride, fluoride, hydroxy, and mixed chloride-fluoride and hydroxychloride complex ions. The equilibrium of tantalum ions during their sorption from chloride solutions is investigated. The behavior of the tantalum ions during the sorption from hydrochloric acid solutions over a wide range of its concentration is interpreted from the viewpoint of the ionic state of the metal in the solution as well as the structure and functional features of ion exchangers. The conclusions made on the sorption chemistry are confirmed by the data of the IR spectroscopy investigations.