Leaching behaviour of low-grade copper ore in the presence of organic acid

This study investigated the kinetics of copper leaching from malachite ore using formic acid as an organic leaching reagent. The analysis was carried out to determine the effect of the following parameters: particle size, acid concentration, leaching time, formic acid/malachite ratio, reaction temperature and stirring speed. Based on the experimental results, the optimum leaching parameters are as follows: particle size, +75?30?µm; formic acid concentration, 0.4?mol?L^?1; leaching time, 90?min; formic acid (volume)/malachite (weight) ratio, 10?mL?g^?1; temperature, 25°C; and stirring speed, 200?rev min^?1. Copper extraction was 70.25% under optimum experimental conditions. Furthermore, a kinetic model was used to indicate the effects of these parameters on the leaching of copper from malachite ore in formic acid solution. It was observed that the leaching process was controlled by film diffusion through a product layer. In conclusion, formic acid can be utilised as an organic leaching reagent in the leaching process of other ores that are similar in structure and composition to malachite.     

In-place leaching of primary sulfide ores: Laboratory leaching data and kinetics model

Experimental results obtained in laboratory leaching studies of primary copper sulfide ore in sulfuric acid systems pressurized with oxygen are interpreted by a computerized geometric model involving the movement of a reaction zone through the ore fragments. Physical properties of the ore, including size, shape, and mineral content, are considered. The leaching mechanism involves mixed kinetics and includes a surface reaction within a moving reaction zone plus pore diffusion of dissolved oxygen through the reacted portion of the ore fragment to the reaction zone. The results are applicable to conditions that would exist innuclear solution mining or similar processes in which the ore is converted into rubble and then inundated by a leach solution adequately supplied with oxidants. Experimental results at 90°C are correlated with the model, which includes temperature-dependent parameters.     

A mathematical model for the solution mining of primary copper ore: Part I. leaching by oxygen-saturated solution containing no gas bubbles

An unsteady-state, one-dimensional model which simulates the solution mining of a rubblized copper ore body deeply buried below the water table has been developed. Leaching is accomplished by pumping water saturated with oxygen into the bottom of the flooded rubble chimney. The physical processes incorporated in the present model include the axial convective transport of mass and heat, axial dispersion of mass, mass transfer between the bulk fluid and solid surface, and pore diffusion within the ore fragments. The solution withdrawn from the top of the chimney is recycled through the bottom of the chimney, and the temperature of the chimney is allowed to build up by means of the heat generated during leaching. The coupled model equations are solved numerically by an implicit finite-difference method. Model calculations for the leaching process are made for two different modes of operation: (1) constant flow-rate and (2) variable flow-rate of the leach solution during leaching. The calculated results from both modes of operation indicate that thefractional recovery of copper increases with decreasing ore particle size, ore grade, pyrite/chalcopyrite molar ratio, and shape factor. Copper recovery is rather insensitive to the chimney porosity under typical operating conditions.     

Investigation of Leaching Kinetics of Copper from Malachite Ore in Ammonium Nitrate Solutions

The production of metallic copper from low-grade copper ores is generally carried out by hydrometallurgical methods. Leaching is the first prerequisite of any hydrometallurgical process. Solutions containing ammonia may allow for selective leaching of the copper from the ore. In this study, the leaching kinetics of malachite, which is an oxidized copper ore, in ammonium nitrate solutions was examined. The effects of some experimental parameters on the leaching process were investigated, and a kinetic model to represent the effects of these parameters on the leaching rate was developed. It was determined that the leaching rate increased with increasing solution concentration, temperature, and agitation speed, as well as decreasing particle size. It was found that the leaching reaction followed the mixed kinetic controlled model, which includes two different leaching processes including the surface chemical reaction (303?K to 323?K [30?°C to 50?°C]) and diffusion through a porous product layer (323?K to 343?K [50?°C to 70?°C]). The activation energies of these sequential steps were determined to be 95.10 and 29.50?kJ/mol, respectively.     

含碳酸盐脉石氧化铜矿的酸浸动力学

针对碳酸盐脉石对氧化铜矿酸浸动力学的影响进行探讨,研究了温度、酸度、矿石粒径、液固质量比、振荡速度等因素对含碳酸盐脉石氧化铜矿浸出的影响.结果表明,高温、高酸度、高液固质量比、小粒径和高振荡速度利于矿石的浸出,但碳酸盐脉石使得酸耗增加.考虑浸出成本确定合理的浸出条件为温度303 K、酸度35 g·L^-1、矿石粒径0.074~0.125 mm、液固质量比3∶1以及振荡速度180 r·min^-1,浸出180 min后铜浸出率达53.6%.对浸出前后矿石表面形貌进行分析.结果显示碳酸盐脉石与酸反应后在矿石表面形成CaSO₄·2H₂O沉淀,覆盖在颗粒表面,限制了矿石颗粒孔裂隙的发育.基于收缩未反应核模型对浸出动力学进行分析,发现碳酸盐脉石反应生成的沉淀阻碍了浸出反应,固体产物层扩散为浸出反应的控制步骤,反应的表观活化能为8.65 kJ·mol^-1.     

Recovery of Elemental Sulfur During the Ammoniacal Leaching of Copper Sulfide

Results of a preliminary study of the ammoniacal leaching of synthetic covellite (CuS) in an aqueous oxidizing system in the presence of a nonmiscible organic sulfur solvent are described. Up to 60 pct of the sulfur can be recovered from the solvent as elemental sulfur while achieving high degrees of solubilization of the mineral. The effects of temperature, particle size, oxygen pressure, ammonia concentration and ammonium ion concentration on the degree of sulfur recovery were investigated. Maximum recoveries were achieved at moderate temperatures and in well-buffered systems, with a large excess of ammonia. Oxygen pressure and particle size were found to have little effect on fractional recovery of sulfur. A simple empirical model based on electrochemical theory correlating the effects of some of the parameters controlling the degree of sulfur recovery is presented. The results of this work also confirm that in any proposed reaction mechanism for the oxidative ammoniacal leaching of copper sulfides, a primary oxidation product of the sulfide ion is elemental sulfur.     

含砷低品位硫化铜矿生物柱浸实验

介绍了含砷低品位硫化铜矿柱浸实验研究方法、装置和结果.实验在八根有机玻璃柱浸系统中进行,考察了细菌种类、矿石粒度、供氧条件及浸出周期等参数对浸出率的影响.结果表明,在-12mm粒度下,采用Z08090-O菌株浸出,浸出167d,铜浸出率为80.75%.对含大量黄铁矿且耗酸脉石少的矿石,酸的累积降低了采用普通驯化浸矿菌的铜浸出率,但采用激光诱变获得的耐低pH值浸矿菌,能够保持高效的铜浸出率.     

某铜钴矿的硫酸还原浸出研究

研究了刚果(金)某铜钴矿的硫酸还原浸出。结果表明,在矿样粒度为-0.074mm占90%、终点pH为1.5、SO2用量为理论量的1.5倍(4kg/t)、浸出温度80℃、浸出时间120min、液固比4∶1的条件下,铜、钴浸出率分别达到了93.35%和90.13%。在此基础上进行了模拟堆浸的柱浸试验,柱浸采用先浸铜再还原浸钴的分步浸出方式,铜浸出率达72%,钴浸出率为66%。     

A mathematical model for the solution mining of primary copper ore: Part II. leaching by solution containing oxygen bubbles

The one-dimensional model developed previously to simulate thein situ leaching of copper from deeply-buried low-grade copper ore deposits is used to simulate thein situ operation in which the oxygen-saturated solution containing oxygen bubbles is introduced at the bottom of the chimney. The physical and chemical processes incorporated in the present model include the axial convective transport of mass and heat, axial dispersion of mass, mass transfer between the liquid and gas phases, fluid-solid mass transfer, diffusion of oxygen in the pores of ore fragments, and the dissolution of sulfide minerals. The coupled model equations are solved numerically by an implicit finite-difference method. Calculations have been made for various values of the volume fraction of oxygen bubbles (up to 0.1) in the fluid just downstream of the oxygen sparging nozzle. Calculated results indicate that, for a specific chimney considered, the total amount of copper extracted increases with increasing volume fraction of undissolved oxygen bubbles in the inlet fluid and increasing superficial velocity of the solution (up to 20 m per day). However, a further increase in the superficial velocity of liquid or undissolved oxygen bubbles does not enhance copper extraction. Calculated results also indicate that the total fractional recovery of copper increases with decreasing pyrite to chalcopyrite molar ratio, ore grade, particle size, and shape factor.     

硫脲浸取某含金矿石的试验研究

对经过焙烧，且钴、铜、镍、钼、铋等有用元素基本已浸出的某含金多金属矿石浸渣，进行了硫脲浸金试验。试验结果表明。当硫脲用量为8kg／t，浓硫酸用量20L／t，浸出时间为4h，金的浸出率达90％以上。     

Catalytic-Oxidative Leaching of Low-Grade Complex Zinc Ore by Cu (II) Ions Produced from Copper Ore in Ammonia-Ammonium Sulfate Solution

The catalytic-oxidative leaching of a mixed ore, which consists of low-grade oxide copper ore and oxide zinc ore containing ZnS, was investigated in ammonia-ammonium sulfate solution. The effect of the main parameters, such as mass ratio of copper ore to zinc ore, liquid-to-solid ratio, concentration of lixivant, leaching time, and temperature, was studied. The optimal leaching conditions with a maximum extraction of Cu 92.6?pct and Zn 85.5?pct were determined as follows: the mass ratio of copper ore to zinc ore 4/10?g/g, temperature 323.15?K (50?°C), leaching time 6?hours, stirring speed 500?r/min, liquid-to-solid ratio 3.6/1?cm³/g, concentration of lixivant including ammonia 2.0?mol/dm³, ammonium sulfate 1.0?mol/dm³, and ammonium persulfate 0.3?mol/dm³. It was found that ZnS in the oxide zinc ore could be extracted with Cu(II) ion, which was produced from copper ore and was used as the catalyst in the presence of ammonium persulfate.     

紫金山低品位铜矿生物堆浸模拟研究

对紫金山低品位铜矿进行生物堆浸模拟试验。结果表明,起始喷淋液全铁浓度4.0g/L、矿石粒度-10mm,浸出周期为181天时,铜浸出率达到80%以上。片碱调节喷淋液pH沉矾除铁,采用不同喷淋制度抑制酸铁浸出是低品位铜矿生物堆浸未来重要研究方向。     

低品位含铜金矿柱浸试验研究

采用柱浸法对紫金山矿区含铜金矿进行浸出试验,分别考察矿样粒度、铜品位、喷淋强度、氰化钠喷淋浓度和浸出时间对浸出率的影响。结果表明,采用堆浸法处理该含铜金矿矿样是可行的,对-80mm粒级在15天内金浸出率大于86%,浸出前期金、铜同时浸出,在浸出后期出现沉铜现象。     

某铜矿尾矿渣微生物柱浸及其动力学

采用两段微生物柱浸对某铜矿尾矿渣中的有价金属进行二次回收研究。考察预处理酸度、接种量、尾矿和废石装矿方式及废石粒度等因素对铜、锌浸出的影响。结果表明,两段微生物柱浸无论改变接种量还是预处理酸度,尾矿最终铜离子浸出率均大于30%,在预处理酸度为5%、接种量10%、-2 mm废石粒级的条件下,铜浸出率可达到38.8%,锌浸出率可达到87.45%。不同的装矿方式浸出差异性不大,分层装尾矿和采场废石并不能有效改善柱子的渗透性。柱浸体系中铜锌浸出动力学模型表明,铜、锌的浸出符合内扩散控制模型。     

低品位次生硫化铜矿生物堆浸工艺优化研究

针对低品位次生硫化铜矿生物堆浸生产中浸出周期长的问题,进行了不同矿石粒度、不同堆高对铜、铁浸出影响的实验室试验和现场柱浸工业试验,优化了生物堆浸工艺,缩短浸出周期,提高了铜浸出率。结果表明,矿石粒度的降低可显著提高铜的浸出率,且不提高铁的溶出。相同粒度条件下,堆高提高有利于堆内温度保持,铜浸出率随之升高。-40mm工业柱浸出194d,铜的浸出率为62.67%,比-80mm高出10个百分点。     

Contribution à l'étude de la lixiviation de la chalcopyrite

A study of the kinetics of chalcopyrite dissolution in sulfuric acid medium under oxygen pressure of 70 psia (0.48 MPa) was made on a chalcopyrite concentrate as function of acid concentration, temperature, and grain size. An evaluation of the real surface, an examination of the surface of the grains by scanning electronic microscope, and an analysis of the residue by energy dispersion of X-rays were carried out for different leaching periods. The dissolution kinetics vary sensibly with grain size, leaching temperature and normality of the original solution. 80% of copper can be leached out of the concentrate after 10 hours of dissolution at 90'C with a solution of 1.8 N sulfuric acid and for a grain dimension of 5 pm. An exponential function is found suitable to explain the kinetics of leaching till the slowing of the copper dissolution is achieved. The nature of the attack is electrochemical with different forms. Crevice corrosion under deposits is an important contributing factor in dissolution and in slowing of the dissolution at the end of the process.     

细粒层对浸矿表面形貌及钝化的影响

由于矿石粒径配比、表面粗糙度、密度等性质差异,筑堆过程中堆内极易出现矿石颗粒偏析现象.细粒层是导致矿石表面受侵蚀程度不均的关键因素,其严重制约了铜矿资源的高效浸取.为探究细粒层对矿石浸出效果、表面形貌及钝化现象的影响,选取粗颗粒矿石（4 mm < d < 6 mm）与细颗粒矿石（2 mm < d < 4 mm）,开展不同细粒层位置下次生硫化铜矿微生物浸出实验.结合CT扫描与冷场电镜扫描技术等分析手段,从宏、细、微观多层面,探究不同细粒层位置下矿石宏观浸出规律,细观矿石团聚结块,微观表面形貌特征与钝化.结果表明：细粒层导致铜浸出率普遍降低,均低于无细粒层、均匀粗颗粒介质的实验组;不同矿堆位置处细粒层对浸出效果影响不同,细粒层位于顶部的实验组铜浸出效果最优,浸矿60 d铜浸出率达71.3%;同一细粒层不同位置处矿石表面孔裂结构演化程度不一;浸矿60 d后,铜浸出率趋于峰值,矿石团聚结块与钝化现象显著,矿石表面形成以黄钾铁矾、多硫化物、胞外多聚物、硫膜为主的钝化物质层.     

Kinetics of copper dissolution during pressure oxidative leaching of lead-containing copper matte

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.     

Effect of Mechanical Activation on Pressure Leaching of Küre Massive Rich Copper Ore

The effect of mechanical activation on metal dissolutions by pressure leaching of massive rich copper ore taken from Küre copper ore deposit (Turkey) was investigated. The dissolution efficiencies of sulfide minerals are significantly improved by ultrafine grinding, also known as mechanical activation. This grinding results in decrease of particle size and an increase in crystal distortion of sulfide minerals. Leaching efficiencies of copper, cobalt, and Zinc increased from 45.2%, 25.9%, and 87.7% to 98%, 85%, and 97%, respectively, after 3-h mechanical activation. At the end of the activation, leaching was carried out at a temperature of 110°C, 10-bar oxygen partial pressure, and 150-g/L solid concentration without addition of acid. This study has also indicated that mechanical activation involving fine milling as a pretreatment is not only effective on copper minerals dissolution but also on the dissolution of other associated minerals, such as cobalt and zinc sulfides.     

Dissolution kinetics of malachite in ammonia/ammonium carbonate leaching

The leaching of oxide copper ore containing malachite, which is the unique copper mineral in the ore, by aqueous ammonia solution has been studied. The effect of leaching time, ammonium hydroxide, and ammonium carbonate concentration, pH, [NH₃]/[NH₄⁺] ratio, stirring speed, solid/liquid ratio, particle size, and temperature were investigated. The main important parameters in ammonia leaching of malachite ore are determined as leaching time, ammonia/ammonium concentration ratio, pH, solid/liquid ratio, leaching temperature, and particle size. Optimum leaching conditions from malachite ore by ammonia/ammonium carbonate solution are found as ammonia/ammonium carbonate concentrations: 5 M NH₄OH+0.3 M (NH₄)₂CO₃; solid/liquid ratio: 1:10 g/mL; leaching times: 120 min; stirring speed: 300 rpm; leaching temperature: 25 °C; particle size finer than 450 μm. More than 98% of copper was effectively recovered. During the leaching, copper dissolves as in the form of Cu(NH₃)₄⁺² complex ion, whereas gangue minerals do not react with ammonia. It was determined that interface transfer and diffusion across the product layer control the leaching process. The activation energy for dissolution was found to be 15 kJ mol⁻¹.