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.     

Leaching kinetics of malachite in ammonium carbonate solutions

Leaching of malachite was conducted with ammonium carbonate as lixiviant and with temperature, lixiviant concentration, and particle size as variables. Two stages of reaction were found. In Stage I, the initial dissolution of malachite proceeds rapidly, but after about 10 pct reaction the rate is reduced by surface blockage due to the presence of a needle-structured intermediate, presumably Cu(OH)₂. Subsequently, malachite and the intermediate dissolve concurrently. In Stage II, after 90 pct reaction, essentially all of the malachite has dissolved and only the intermediate remains. It dissolves in Stage II. The activation energy is 64 kJ/mole (15.3 kcal/mole) for Stage I and 75 kJ/mole (18 kcal/mole) for Stage II. The rate of reaction in Stage I is proportional to the reciprocal of particle size and is 0.8 order with respect to the concentration of ammonium carbonate. The structures of leaching residues were studied using a scanning electron microscope. The kinetic data (activation energy and entropy), particle size and concentration dependence, residue morphology, and general leaching behavior evident from microscopic monitoring during leaching were used to develop the geometric equation for leaching in Stage I. The equation, based on a heterogeneous reaction with geometric rate control, is: 1 − (1 − α^1/3 = K₀₁/r₀/[(NH₄)₂C0₃]^0.8 exp(-64,000/RT)t. It was deduced that initial steps in reaction were: (1) release of Cu²⁺ from malachite; (2) initial complexing with ammonia to form Cu(NH₃)²⁺; and (3) subsequent complexing to produce Cu(NH₃) ₄ ²⁺ which is stable in solution at pH 8.8, the buffered pH of reaction. Stage II appears to be a similar reaction except that the reaction obeys cylindrical geometry instead of spherical geometry as in Stage I.     

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.     

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.      

Leaching of chrysocolla with Ammonia-Ammonium carbonate solutions

Chrysocolla was leached in solutions of ammonium hydroxide and ammonium carbonate as a function of the variables: temperature (25 to 55 ‡C), ammonia-ammonium ratio (0.0:1.0 to 1.0:0.0), total ammonia concentration (0.25 to 6.0 M), and particle size (100 to 400 mesh). A model of the leaching behavior was deduced based on: (1) the activation energy of 60.75 kJ/mole (14.51 kcal/mole) for 3 M total NH₃ which was dependent on both total ammonia concentration and temperature; (2) first-order dependence of rate on [(NH₄)₂CO₃]; (3) dependence of initial reaction rate on reciprocal of particle diameter; and (4) morphological evidence from SEM and ED AX measurements of diffusion and leaching occurring primarily in surface microcracks and not in the submicroscopic pores. In addition to the importance of diffusion through microcracks in rate control chemical reaction at active surface sites to produce the species, CuNH ₃ ^{2 +}, is also important. Only a fraction of the Cu atoms react that are exposed to lixiviant. Higher ammonia-ammonium ion concentrations, higher temperatures, or much longer times are required for more refractory Cu atoms to dissolve. Formerly Graduate Student, Department of Metallurgy and Metallurgical Engineering, University of Utah     

Dissolution behaviour of a beryl ore for optimal industrial beryllium compound production

This study involves the leaching of the beryl ore with sulphuric acid (H₂SO₄) solution for predicting optimal beryllium extraction conditions with the aim of assessing the importance of leachant concentration, reaction temperature and particle size on the extent of dissolution. A kinetic model to represent the effects of these variables on the leaching rate was developed. It was observed that the dissolution of beryl ore increases with increasing H₂SO₄ concentration, temperature, decreasing particle size and solid to liquid ratio. At optimal leaching conditions, 89.3% of the ore was reacted by 1.25?mol/L at 75°C temperature and 120 minutes with moderate stirring, where 1612.0?mg/L Be²⁺, 786.7?mg/L Al³⁺, 98.1?mg/L Fe³⁺ and 63.4?mg/L Ag⁺ were found as major species in the leach liquor. The unleached products constituting about 10.7% were examined by X-ray diffraction (XRD) and found to contain primarily, siliceous compounds such as Xonotlite, Antigorite, Chrysolite and Kaolinite.     

Kinetics of Dissolution of Tenorite in Ammonium Media

In this work, the dissolution kinetics of tenorite (CuO) in a NH₄OH-H₂O system was studied. The studied temperature range was 5–55°C, ammonium hydroxide concentration between 0.1 and 0.75 M, and a particle size range of 5–24 µm. The stirring speed, pH of the ammonia solution, and various agents were also studied. The results indicated that the leaching of tenorite occurred quickly with a particle size of 5 µm in a 0.45 M solution of NH₄OH for a pH value equal to 10.5. Dissolution of CuO also increases as temperature and the concentration of NH₄OH increase. For concentrations less than 0.10 M, there is almost no leaching tenorite. By decreasing the particle size, the dissolution of CuO increase. Results show the stirring speed had no significant effect on the leaching rate of tenorite for values above 250 rpm. Leaching kinetics was analyzed using the model of the surface chemical reaction. The reaction rate was of the order of 2.2 with respect to the concentration of ammonium hydroxide and inversely proportional to the initial particle size. Activation energy of 59 kJ/mol was estimated for the temperature range of 5–55°C.     

Direct selective leaching of chalcopyrite concentrate

The ammonium persulphate (APS) leaching of chalcopyrite concentrate in the presence of ammonium carbonate was studied. The effects of ammonium carbonate concentration, APS concentration, leaching time, leaching temperature, solid/liquid ratio and stirring speed were investigated. Optimum leaching conditions were found as follows: APS concentration is 200 g L^?1; ammonium carbonate concentration is 200 g L^?1; leaching time is 180 min; leaching temperature is 60°C; solid/liquid ratio is 0·04 g mL^?1; and stirring speed is 400 rev min^?1. Under these conditions, copper extraction yield was obtained at about 72%. Furthermore, iron extraction yield decreased with increasing ammonium carbonate concentration and iron did not pass into solution under this condition. X-ray and SEM analysis also supported these results. It was determined that the copper extraction results were satisfactory by way of all experiments were performed under atmospheric conditions (i.e. low temperature and atmospheric pressure) and achieved selective copper leaching from chalcopyrite concentrate.

On a étudié la lixiviation au persulfate d’ammonium (APS) du concentré de chalcopyrite en présence de carbonate d’ammonium. On a examiné l’effet de la concentration du carbonate d’ammonium, de la concentration d’APS, de la durée et de la température de lixiviation, du rapport solide-liquide et de la vitesse d’agitation. Les conditions optimales de lixiviation suivent: concentration d’APS?=?200 g L^?1; concentration de carbonate d’ammonium?=?200 g L^?1; durée de lixiviation?=?180 min; température de lixiviation?=?60°C; rapport solide-liquide?=?0·04 g mL^?1; et vitesse d’agitation?=?400 rpm. Avec ces conditions, le rendement d’extraction du cuivre était d’environ 72%. De plus, le rendement d’extraction du fer diminuait avec l’augmentation de la concentration de carbonate d’ammonium, qui empêchait également le fer de passer en solution. L’analyse aux rayons x et au SEM supportait également ces résultats. Grâce à toutes les expériences effectuées en conditions atmosphériques (c’est-à-dire à basse température et à pression atmosphérique), on a déterminé que les résultats d’extraction du cuivre étaient satisfaisants et qu’on obtenait une lixiviation sélective du cuivre à partir du concentré de chalcopyrite.     

Solubility prediction of malachite in aqueous ammoniacal ammonium chloride solutions at 25 °C

The solubility of malachite in the presence of ammonia, ammonium chloride and their mixed solution is calculated by a geochemical modeling code and is measured in a series of dissolution experiments using synthetic malachite at 25 °C. The simulated results show a good agreement with the experimental data gained at 25 °C. The predicted and experimental results indicate that the precipitate CuO limits the copper solubility in aqueous ammonia and Cu(OH)_1.5Cl_0.5 in aqueous ammonium chloride. For a mixed solution containing ammonia and ammonium chloride, highest copper solubility can be achieved by adjusting the [NH₃]/[NH₄Cl] ratio to about 2:1. The thermodynamic model presented rationalises the interactions between the different components and predicts the influence of changes in the concentration of ammonia and ammonium chloride on the copper solubility of malachite.     

Dissolution of MoS2 concentrate using NaClO from 283 to 373 K

This study analyses the leaching process of molybdenite (MoS₂) concentrate using sodium hypochlorite (NaClO) at temperatures ranging from 283 to 373?K. The following variables were studied: leaching time, stirring velocity, temperature, NaClO concentration, NaOH concentration, particle size and liquid:solid ratio. The optimum parameters for molybdenite dissolution were: Time?=?0.81?h, stirring speed?=?800?rev?min^??1, temperature?=?303?K, NaClO concentration?=?1.49M, NaOH concentration?=?8.01M, particle size?=?45?μm and liquid:solid ratio?=?300?:?1.?Under these conditions, molybdenite dissolution reached around 99%, while Cu and Fe recovery were insignificant. Analysis using XRD, QUESCAM and SEM showed release indices and subsequent reaction of the MoS₂ and the constituent parts of Cu and Fe.     

Kinetics of leaching selenium from Ni-Mo ore smelter dust using sodium chlorate in a mixture of hydrochloric and sulfuric acids

The kinetics of leaching selenium from Ni-Mo ore smelter dust in H₂SO₄-HCl-H₂O system was investigated. The effects including leaching temperature and time, particle size of the smelting dust, stirring speed, acid concentration and the coefficient β (the molar ratio of sodium chlorate to selenium in the smelter dust) on leaching of selenium were studied. The results indicated that the leaching of selenium increased sharply with the increase of temperature. The leaching of selenium reached 98% at 95 °C and stirring speed of 350 rpm for 150 min with the particle size of − 0.15 mm, initial [H⁺] concentration of 8 mol/L, the solid/liquid ratio of 1:5 g/mL and the coefficient β of 3.33. The leaching process was controlled by the surface chemical reaction and the kinetics of leaching selenium from Ni-Mo ore smelter dust followed the model of “shrinking core”. The apparent activation energy of leaching selenium was determined to be 44.4 kJ/mol, which was consistent with the values of activation energy reported for the surface chemical reaction control. The kinetics equation of leaching selenium from Ni-Mo ore smelter dust was expressed as , which coincided with the experimental results.     

某毒砂金矿硫氰酸盐氨性体系加压氧化提金探索试验

对某毒砂金矿进行了硫氰酸盐氨性体系氧压提取金的探索试验,考察了反应温度、Cu2+浓度、浸出时间、液固比、氨水浓度、氧分压和硫氰酸铵浓度等对金浸出率的影响。结果表明,在下述优化条件下金浸出率为61.7%,即硫氰酸铵浓度3mol/L,液固比5∶1,反应温度150℃,浸出时间6h,搅拌速度750r/min,氨水浓度4.64mo/L,铜加入量1.5g/L。而经400℃焙烧预处理后金浸出率达到86.2%。     

Recovering copper from volcanic ASH by NH<Subscript>3</Subscript> · H<Subscript>2</Subscript>O–NH<Subscript>2</Subscript>COONH<Subscript>4</Subscript>

Volcanic ash from Xinjiang in the PRC contains malachite and cuprite. The volcanic ash has a copper content of 1.29%. However, because of severe argillization it is difficult to recover the copper through enrichment by flotation. Because the ash contains significant amounts of calcium and magnesium carbonates leaching the ash with acid requires a large amount of acid. We thus studied the use of ammonia-water and ammonium carbamate as effective leaching agents for copper. Leaching with ammonia-water and ammonium carbamate does not affect gangue minerals such as quartz and calcite and it can also promote the dissolution of minerals that contain copper. This leaching agent is highly specific. Using this system we recovered more than 90% of the copper from the volcanic ash. Higher reaction temperatures, smaller ore particle sizes, a higher stirring speed, a higher liquid to solid ratio and an increase in the agent’s concentration increased the copper leaching rate. SEM analysis, the activation energy (7.827 kJ/mol) and kinetics data comprehensively indicate that the reaction of copper minerals in the ammonia-water and ammonium carbamate system is controlled by internal diffusion.     

氨法加压浸出钴铜氧化矿工艺

氨法浸出是基于目标金属与氨形成配合离子进入溶液,实现目标金属与部分杂质的分离,因此浸出过程具有选择性。对钴、铜与氨的配合机制及亚硫酸钠还原性能的影响因素进行了分析。结果表明:提高cNH3/cMe有利于形成稳定性高的钴、铜氨配合离子;降低cSO42-/cSO32-,提高体系pH可降低还原剂还原电位。实验过程采用加压氨浸工艺,在NH3-NH4+-H2O体系中浸出钴铜氧化矿中的钴和铜,研究了总氨浓度、氨铵比、液固比、浸出温度、还原剂用量对氧化矿中钴和铜浸出率的影响。结果表明,在总氨浓度7 mol.L-1、氨铵比2∶1、液固比6∶1、浸出温度100℃、还原剂亚硫酸钠用量为三价钴含量(摩尔比)4倍的最优条件下,钴浸出率可达到95.2%,铜浸出率可达到95.8%。浸出液后续处理工艺简单,氨及铵盐可实现闭路循环,对环境友好。     

Reductive leaching of pyrolusite ore by using sawdust for production of manganese sulfate

Manganese compounds, such as manganese sulfate, can be obtained from pyrolusite, a manganese ore. Low-grade manganese ores is usually treated by hydrometallurgical methods. In this study, the leaching and recovery of manganese from pyrolusite ore in sulfuric acid solutions containing sawdust as reducing agent was investigated. The effects of experimental parameters, such as sulfuric acid concentration, sawdust amount, solid-to-liquid ratio, stirring speed, particle size, reaction temperature, and leaching time, on the manganese extraction from ore were examined. The results showed that the leaching rate of pyrolusite ore increased with an increasing sulfuric acid concentration, sawdust amount, stirring speed, reaction temperature and leaching time, and decreasing in solid to liquid ratio and particle size. The kinetic analysis of leaching process was carried out, and it was determined that the reaction rate was controlled by diffusion through the product layer under the experimental conditions in this work. The activation energy was found to be 22.35 kJ mol^?1. Manganese can be recovered as manganese sulfate by the evaporative crystallization of the purified leach liquor.     

氨法浸出电镀废渣中镍铜的工艺

实验采用NH3-NH4+-H2O体系浸出电镀废渣中镍和铜,通过正交试验研究了总氨浓度、氨铵比、液固比、温度、浸出时间对浸出率的影响.结果表明,在总氨浓度为6 mol/L、氨铵比为1∶1、液固比为8∶1、浸出温度80℃、浸出时间3h的最优条件下,镍的浸出率可达到82％,铜的浸出率可达到95％.     

空气氧化—氨浸出废旧电路板中的铜

提出了在氨水—硫酸铵体系下鼓入空气浸出废旧电路板中铜的新工艺。考察了氨水浓度、硫酸铵浓度、固液比、反应温度、通入空气流量和浸出时间对铜浸出率的影响。结果表明,在下述最佳浸出条件下,渣计铜浸出率达到96.67%:氨水浓度2mol/L,硫酸铵浓度2mol/L,固液比1∶20,反应温度25℃、通入空气量8m3/h、浸出时间4h。     

Reaction Kinetics of magnesite ore in dilute ethanoic acid

The leaching of naturally occurring magnesite in dilute ethanoic acid is achieved to optimize the reaction conditions affecting the reaction kinetics. In the current study effect of various reaction parameters (The particle size of ore, concentration of leaching agent, the reaction temperature and rate of stirring) on the dissolution of magnesium carbonate ore with aqueous solutions of acetic acid is probed. It is inferred that the rate of leaching reaction of magnesium carbonate ore in the aqueous solutions of acetic acid rises with a rise in temperature of reaction medium, acetic acid solution strength and decreases with the increase in particle size of the magnesite ore samples. The analysis of kinetic data done by the application of graphical and statistical approaches reveals that the leaching kinetics of magnesite ore in dilute solutions of acetic acid follows a surface chemically controlled mechanism. The calculated value of energy of activation for the dissolution reaction of magnesium carbonate in acetic acid is 46.39 kJ mol^–1.     

紫金山高品位铜矿石的热压氧氨浸铜研究

对紫金山高品位铜矿进行了热压氧氨浸铜工艺研究 ,并从初始氨浓度、浸出温度、浸出时间等几方面对工艺参数进行了探讨。结果表明 ,初始氨浓度、浸出温度及铵盐量在一定范围内有最佳值 ;减小粒度、延长反应时间、增大搅拌速度、减小矿浆浓度可以提高Cu的浸出率。在氧气分压 0 5MPa,温度10 0℃ ,浸出时间 4h条件下 ,Cu的浸出率可达 96 1%。     

Leaching of sulfide copper ore in a NaCl–H2SO4–O2 media with acid pre-treatment

A study was made of the leaching of a sulfide copper ore in a NaCl–H₂SO₄–O₂ media after pre-treatment by agglomeration with H₂SO_4(conc) and NaCl. The leaching variables evaluated included the amount of NaCl to be employed, the percentage of solids in the leaching solution, particle size of the raw mineral to be leached, and the preferable method of agitation in the leaching system. Mineralogical characterization of the material to be leached included analysis of the raw ore and of the leached ore residue using reflected-light microscopy, X-ray diffraction, and scanning electron microscopy. The soluble species included djurleite and digenite. The most important parameters in the leaching process proved to be particle size and type of agitation. A total percentage of copper extraction of 70% was achieved using mechanical stirring, which increased to 78% when using compressed air agitation. The best extraction of the copper was achieved when leaching with 3 g/L of chloride, room temperature of 20 °C, and when all particles were < 1.65 mm in diameter.