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1.
Kinetics of copper dissolution during pressure oxidative leaching of lead-containing copper matte 总被引:1,自引:0,他引:1
The kinetics of pressure oxidative leaching of lead-containing copper matte with sulfuric acid was investigated. The effects of particle size, leaching temperature, oxygen partial pressure and sulfuric acid concentration on the kinetics and mechanism of copper extraction were studied. It was found that the reaction kinetic model follows the shrinking core model of chemical reaction control and the apparent activation energy was determined as 39.1 kJ/mol. The order of the reaction with respect to total pressure was found to be 0.64. The kinetic equations for the effect of particle size, leaching temperature, total pressure and sulfuric acid concentration were obtained and a mathematical model of copper extraction from lead-containing copper matte was developed as:This equation estimates the extraction of copper with very good agreement (r = 0.99) between the experimental and calculated values. 相似文献
2.
比较了常压浸出与加压浸出两种工艺的机理、流程、技术经济指标、投资以及存在的问题。试验和生产数据表明,加压浸出在技术上和工艺上都更具有吸引力。 相似文献
3.
比较了常压浸出与加压浸出两种工艺的机理、流程、技术经济指标、投资以及存在的问题。试验和生产数据表明,加压浸出在技术上和工艺上都更具有吸引力。 相似文献
4.
A kinetic study on the pressure leaching of sphalerite 总被引:4,自引:0,他引:4
The dissolution of sphalerite (ZnS) in sulfuric acid solution under oxygen pressure was investigated. Effects of temperature,
percent solids, agitation, sample size, oxygen partial pressure and foreign ions were evaluated. The effect of hydrogen pretreatment
on sphalerite leaching rate was also examined. Leaching of sphalerite at 90°C and 150 psi oxygen pressure was found to occur
at a constant rate. This rate was determined from the experimental data observed under the different leaching conditions mentioned
above. The constant leaching rate was attributed to the chemical reaction occurring on the surface of the flat-plate type
sphalerite sample. The rate-controlling step of the reaction was determined to be the oxidation of hydrogen sulfide to elemental
sulfur. Oxidation of hydrogen sulfide was studied through the addition of iron and through the observation of the change in
iron concentration during leaching. The oxidation was concluded to be by reaction with ferric ion rather than by direct oxygen
oxidation. Leaching tests run with samples pretreated with hydrogen do not show any increase in the rate of zinc extraction.
M. T. HEPWORTH, formerly with University of Denver. 相似文献
5.
《Hydrometallurgy》1987,17(3):369-384
The kinetics of the non-oxidative dissolution of four samples of sphalerite (ZnS) of different origin were studied. It was concluded that the dissolution is independent of the stirrer speed and is first order in [H+], and that the activation energies for the removal and deposition reactions are not sensitive to the impurity content of the solid. The rate of reaction is described by an ionic charge transfer mechanism. A large addition of Zn2+ retards the initial rate because equilibrium conditions are established, whereas the addition of H2S to the reaction system lowers the final extent of reaction. The addition of Fe (III) retards the initial rate of reaction due to an anodic shift in the potential difference at the surface-solution interface, but increases the final extent of reaction as a result of the consumption of H2S by Fe (III) to form elemental sulphur and Fe (II). The observed inhibition of the initial rate for the impure samples is explained in terms of an electron-transfer theory similar to that proposed for non-stoichiometric metal sulphides. 相似文献
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Minting Li Chang Wei Shuang Qiu Xuejiao Zhou Cunxiong Li Zhigan Deng 《Hydrometallurgy》2010,104(2):193-200
The leaching kinetics of vanadium from black shale in the sulphuric acid-oxygen system is presented. The effects of agitation speed, leaching temperature in the range of 110-150 °C, sulphuric acid concentration, oxygen partial pressure and particle size on the rate of vanadium leaching were determined. The results indicate that the rate is nearly independent of agitation above 200 rpm and increases with increasing temperature, sulphuric acid concentration and oxygen partial pressure. As leaching occurs, there is a progressive dissolution of a vanadium-bearing alumino-silicate phase, while the inert quartz phase assembles onto the mineral surface and remains as an “ash” layer. The leaching kinetics was analyzed by using a new variant of the shrinking core model (SCM) in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. The determined activation energy was found to be 40.14 kJ/mol and the reaction orders with respect to sulphuric acid concentration and oxygen partial pressure were 0.61 and 1.67, respectively. A semi-empirical rate equation was derived to describe the process. 相似文献
11.
J. E. Dutrizac 《Metallurgical and Materials Transactions B》2006,37(2):161-171
The dissolution of sphalerite, (Zn,Fe)S, in ferric sulfate media was investigated using closely sized fractions of crushed
sphalerite crystals. Linear kinetics were observed, and the rate increased in proportion to the surface area, as the average
particle size of the sphalerite decreased. The predominant reaction products are ZnSO4, FeSO4, and elemental sulfur. The leaching rate increases with increasing temperature, and the apparent activation energy is 44
kJ/mol. The relatively high apparent activation energy suggests that the rate is chemically controlled, a conclusion supported
by the insensitivity of the rate of the rotation speed that was observed in complementary rotating disk experiments. The rate
increases as the 0.3 to 0.4 power of the Fe(SO4)1.5 concentration, and is nearly independent of the pulp density, in the presence of a stoichiometric excess of ferric sulfate.
In 0.3 M Fe(SO4)1.5 media, the rate increases with increasing acid concentrations >0.1 M H2SO4, but is insensitive to more dilute acid concentrations. In the absence of ferric ions, the rate increases rapidly with increasing
H2SO4 concentrations, and relatively rapid rates are observed in solutions containing >0.5 M H2SO4. The rate decreases with increasing initial concentrations of ZnSO4, MgSO4, or FeSO4 in the ferric sulfate leaching solution, and this emphasizes the importance of maintaining the dissolved iron in a fully
oxidized state in a commercial leaching operation. 相似文献
12.
Reaction mechanisms for the ferric chloride leaching of sphalerite are proposed based on data obtained in leaching and dual
cell experiments presented in this work and in a previous study. The results from the leaching experiments show that at low
concentrations the rate is proportional to [Fe3+]T
0.5 and [Cl-]T
0.43 but at higher concentrations the reaction order with respect to both [Fe3+]T and [Cl-]T decreases. Using dual cell experiments which allow the half cell reactions to be separated, increased rates are observed
when NaCl is added to the anolyte and to the catholyte. The increase in rate is attributed to a direct, anodic electrochemical
reaction of Cl- with the mineral. When NaCl is added only to the catholyte, a decrease in the rate is observed due to a decrease in theE
0 of the cathode which is attributed to the formation of ferric-chloro complexes. Several possible electrochemical mechanisms
and mathematical models based on the Butler-Volmer relation are delineated, and of these, one model is selected which accounts
for the experimentally observed changes in reaction order for both Fe3+ and Cl-. This analysis incorporates a charge transfer process for each ion and an adsorption step for ferric and chloride ions. The
inhibiting effect of Fe2+ noted by previous investigators is also accounted for through a similar model which includes back reaction kinetics for Fe2+. The proposed models successfully provide a theoretical basis for describing the role of Cl-, Fe3+, and Fe2+ as well as their interrelationship in zinc sulfide leaching reactions. Possible applications of these results to chloride
leaching systems involving other sulfides or complex sulfides are considered. 相似文献
13.
在锌冶炼过程的氧压浸出溶液中由于铜、铁、锰等杂质元素的存在,在使用EDTA络合滴定锌时终点变色不明显,结果误差大,不符合生产要求。采用硝酸消解试样,加入氨水、氯化铵、氟化钾沉淀分离铁、铅等元素,加入过硫酸铵使锰以二氧化锰析出;在pH 5.5~6.0的乙酸-乙酸钠缓冲溶液中以二甲酚橙为指示剂,铜(II)用硫脲掩蔽、铝用氟化钠掩蔽,滴定前加入抗坏血酸解除铁(III)对指示剂的封闭,用EDTA标准溶液滴定锌,终点明显,从而建立了使用EDTA滴定法测定氧压浸出溶液中锌的方法。按照实验方法测定氧压浸出溶液中锌,结果的相对标准偏差(RSD,n=9)为0.43%~1.3%;加标回收率为99%~102%;实验方法用于测定6个氧压浸出溶液中锌,测定值与参考值相吻合。 相似文献
14.
《Hydrometallurgy》1986,16(3):345-359
The leaching of a sphaleritic flotation concentrate in an acidic ferric sulphate solution is described by an electrochemical charge-transfer model in which the mineral surface potential is approximated by the solution redox potential for the ferrous-ferric redox couple. The oxidation of ferrous ions by dissolved oxygen is described by a model consistent with previously reported models, and the leaching of the sphalerite in the presence of dissolved iron and oxygen is described by the simultaneous integration of the two individual rate expressions. 相似文献
15.
《Hydrometallurgy》1987,19(2):227-242
The kinetics of the oxidative dissolution of a zinc sulphide (sphalerite) concentrate was studied. It was observed that the dissolution of the concentrate continued beyond 90% conversion in two hours at 80°C. The kinetics of dissolution are successfully described by an electrochemical mechanism in which the charge transfer from the solid to the oxidant is rate-limiting. The rate of reaction is proportional to the sum of the concentrations of the Fe3+ (aq) and FeHSO42+ complexes with a reaction order of one-half. The addition of Fe (II) to the solution had an indirect effect on the reaction rate, by decreasing the concentrations of the electro-active ions. Addition of ZnSO4 did not affect the reaction rate. 相似文献
16.
The formation of zinc ferrite (ZnFe2O4) during the roasting of iron-bearing zinc concentrates requires substantial additional processing to recover the zinc from
this compound by leaching and to eliminate the iron from the leachate. The phase changes that occur in the particles of a
typical industrial zinc sulfide concentrate during roasting in a fluidized bed at 1223 K were investigated by the use of light
microscopy, electron microprobe analysis, and SEM with EDS. The processes which the iron undergoes during its eventual transformation
into ferrite have been clarified by examination of the phases and the morphology of partially roasted marmatitic sphalerite
particles (Zn, Fe)S, and by reference to the known phase equilibria involved in the Zn-Fe-S-0 system. The oxidation of ironbearing
sphalerite occurs in three stages. The first involves the selective diffusion of most of the iron to the particle surface
resulting in the formation of an iron oxide shell enclosing a largely unreacted zinc sulfide kernel. In the second stage,
this kernel is oxidized to form a solid solution of zinc oxide and iron oxide. The iron is initially present in the ferrous
state but, with the disappearance of the sulfide kernel, is oxidized to ferric iron. In the final stage, this dissolved iron
oxide and the iron oxide shell react with the surrounding zinc oxide to form the refractory spinel zinc ferrite. 相似文献
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18.
The kinetics of dissolution of sphalerite in ferric chloride solution 总被引:10,自引:0,他引:10
The dissolution of sphalerite in acidic ferric chloride solution was investigated in the temperature range 320 to 360 K. Both
sized particles from three sources and polished flat surfaces were used as samples. The effect of stirring rate, temperature,
ferric and ferrous ion concentration, purity, and particle size on the dissolution rate were determined. During the initial
stages of the process chemical reaction at the mineral surface is rate controlling while during the later stages diffusion
through the product sulfur layer is rate controlling. Overall the process follows the mixed-control model embodying both chemical
reaction and diffusion. The activation energy for the dissolution of sphalerite particles was found to be 46.9 kJ/mol. 相似文献
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20.
Effect of aging conditions on the leaching of mechanically activated pyrite and sphalerite 总被引:1,自引:0,他引:1
Huiping Hu Qiyuan Chen Zhoulan Yin Pingmin Zhang Lusheng Ye 《Metallurgical and Materials Transactions B》2003,34(5):639-645
The leaching of mechanically activated pyrite and sphalerite exposed to nitrogen (99.999 vol pct) or air at ambient temperature
or 573 K was investigated. The results indicate that at the same leaching time, the iron-leaching ratio of mechanically activated
pyrite or sphalerite aged in nitrogen at both ambient temperature and 573 K decreases slightly with increasing aging time
and remains constant after a certain aging period. The iron-leaching ratio of mechanically activated pyrite exposed to ambient
air varies with the exposure period. But, at the same leaching time, the zinc-leaching ratio of mechanically activated sphalerite
aged at ambient temperature does not change with the aging atmosphere. The structures of mechanically activated pyrite and
sphalerite after being aged were determined. The specific granulometric surface area of mechanically activated pyrite and
sphalerite decreases with increasing aging time, but keeps constant after a certain aging period. The X-ray diffraction patterns
of mechanically activated pyrites aged in nitrogen do not change with aging time; neither do the X-ray diffraction patterns
of mechanically activated sphalerites aged either in air or in nitrogen. For mechanically activated pyrite exposed to ambient
air for 3 and 6 months, new phases were found. The lattice distortion and the elemental sulfur content of pyrite and sphalerite
mechanically activated in nitrogen were also investigated. The results indicate that the elemental sulfur content of mechanically
activated pyrite rises noticeably, and its lattice distortion (ε) rises slightly, with increasing grinding time. The elemental sulfur content of mechanically activated sphalerite remains
constant at 0.5 mg elemental sulfur per gram of sphalerite, and its lattice-distortion ratio increases apparently with increasing
grinding time. These observations provide further evidence for our opinion that the formation of dangling bonds on the surface
of mechanically activated pyrites and the lattice distortion on the surface of mechanically activated sphalerites may mainly
result in the enhancement of hydrometallurgical process for corresponding sulfide minerals. 相似文献