Leaching Rate Of Copper Research Articles

An integrated and sustainable hydrometallurgical process for enrichment of precious metals and selective separation of copper, zinc, and lead from a roasted sand

The developed hydrometallurgical process for recovering copper, zinc, and lead from the roasted sand of WPCB-SA. • A hydrometallurgical process for recovering valuable elements was proposed. • Copper and zinc were selectively recovered by water leaching. • Lead was efficiently recovered by high-chloride leaching. • The leaching kinetics and conversion mechanism of lead were analyzed. • Gold and silver have been successfully enriched in the leached residue. This study developed an efficient and sustainable hydrometallurgical process for the enrichment of gold and silver and the stepwise separation of copper, zinc, and lead from sulfated roasted sand of waste printed circuit board smelting ash. Selective separation of copper and zinc was achieved by water leaching, and silver dispersion was reduced by controlling the amount of NaCl added during the leaching process. The results of the water leaching showed that the copper and zinc leaching rates were 99.85% and 99.47%, respectively, whereas the loss rate of silver was 2.1% with optimal leaching parameters. The high-chloride-complex method was used to study the efficient conversion and separation of lead from the leached residue, and the leaching kinetics and conversion mechanism of lead were discussed. The results showed that under the optimal conditions, the leaching rate of lead was 99.79%. Leaching kinetics analysis showed that lead leaching in the high - chlorine system was controlled by a chemical reaction; the apparent activation energy was 53.63 kJ/mol. After the leaching of copper, zinc, and lead, 1.66% Ag and 213 g/t Au were enriched in the leached residue; and the precious metal enrichment goal was reached. The chlorinated leachate showed good recycling performance, and a lead leaching rate of 97.93% was obtained after three circulations. After cooling, crystallization, and purification, lead chloride with a purity of 99.89% and high economic and industrial value was obtained from the lead-rich leachate. This process has favorable and sustainable industrial application prospects.

How copper dump leaching works

In copper dump leaching, run-of-mine ore is irrigated with acidic leaching solution to generate aqueous cupric ions for further processing. The very large size of the ore particles being leached, as much as two meters in diameter, should preclude any significant metal recovery. Dump leaching should not work; and yet it does. This study investigated the leaching of coarse-sized copper sulphide ore, with top sizes ranging from 150 to 250 mm. The simulated run-of-mine ore sizes were leached for more than six months. The data collected from these experiments included particle size distributions before and after leaching, copper distributions by size before and after leaching, and leaching kinetics at various irrigation rates. The results showed that leaching causes particle breakage. That breakage results in a continuous generation of fines and a continuous supply of fresh mineral surfaces for leaching. Dump leaching can be explained by a mechanism of breakage and fines generation. The rate of copper leaching in dumps is a product of the rate of fines generation and the rate of leaching of the fines.

Bioleaching and Electrochemical Behavior of Chalcopyrite by a Mixed Culture at Low Temperature.

Low-temperature biohydrometallurgy is implicated in metal recovery in alpine mining areas, but bioleaching using microbial consortia at temperatures <10°C was scarcely discussed. To this end, a mixed culture was used for chalcopyrite bioleaching at 6°C. The mixed culture resulted in a higher copper leaching rate than the pure culture of Acidithiobacillus ferrivorans strain YL15. High-throughput sequencing technology showed that Acidithiobacillus spp. and Sulfobacillus spp. were the mixed culture’s major lineages. Cyclic voltammograms, potentiodynamic polarization and electrochemical impedance spectroscopy unveiled that the mixed culture enhanced the dissolution reactions, decreased the corrosion potential and increased the corrosion current, and lowered the charge transfer resistance and passivation layer impedance of the chalcopyrite electrode compared with the pure culture. This study revealed the mechanisms via which the mixed culture promoted the chalcopyrite bioleaching.

Bioleaching of a Copper-Zinc Concentrate with High Arsenic Content

The goal of the present work was to study the dependence of the rate of copper and zinc bioleaching from an arsenic-containing copper-zinc concentrate containing 16% Cu, 5.3% Zn, and 1.36% As, on the temperature and the presence of an organic carbon source (yeast extract) in the medium. The main minerals of the concentrate were chalcopyrite (CuFeS2), tennantite (Cu12As4S13), sphalerite (ZnS), and pyrite (FeS2). A mixed culture of moderately thermophilic acidophilic microorganisms oxidizing sulfur and ferrous iron, which was used in the work, consisted of the strains Acidithiobacillus caldus MBC-1, Sulfobacillus thermosulfidooxidans SH-1, and Acidiplasma sp. MBA-1. The experiments were carried out in flasks with 100 mL of mineral medium and 2 g of the concentrate on a rotary shaker for 30 days at temperatures from 40 to 60°C. It was shown that the leaching rate of copper depended both on temperature and on the presence of yeast extract. Copper leaching rate increased with increasing temperature, while zinc leaching was less dependent on the temperature. In the presence of an organic carbon source in the medium, both copper and zinc were actively leached at high temperatures (55 and 60°C), while in experiments with a medium without yeast extract, the activity of non-ferrous metals leaching from the concentrate at these temperatures was much lower. At the same time, at temperatures of 40–50°C, leaching activity was less dependent on the presence of the organic carbon source in the medium.

Mechanical Activation on Bioleaching of Chalcopyrite: A New Insight

Mechanical activation as a means of accelerating the mineral dissolution may play an important role in chalcopyrite bioleaching. In the present work, the mechanical activation by ball-milling with 10 min, 30 min, 60 min, 90 min, 120 min and 180 min time periods of bioleaching of chalcopyrite was studied, and then evaluated by a Density Functional Theory (DFT) calculation. The results showed that the specific surface area increased sharply in the very beginning of mechanical activation and then increased slowly until the agglomeration of the particles occurred, while the chalcopyrite lattices increased with the mechanical activation. The reaction activity analyzed by cyclic voltammetry (CV) increased slowly in 30 min, increased quickly in the following 90 min, and then decreased, while the hydrophobicity analyzed by contact angles of the chalcopyrite after activation showed less of a change. The results showed that after 15 days of bioleaching, the Cu leaching by Sulfobacillus thermosulfidooxidans (S. thermosulfidooxidans) increased from 9.39% in the 0 min of mechanical activation to 87.41% in the 120 min of mechanical activation, and the copper leaching rate increased by about 78%. The DFT results provide solid proof that the activated chalcopyrite can be adsorbed more easily by cells with higher adsorption energies and stronger bonds.

Bioleaching of Sulfide Concentrates with Different Copper and Zinc Contents and Evaluation of Bioleach Residue Grade

Bioleaching of sulfide concentrates with different copper and zinc contents using two cultures of acidophilic chemolithotrophic microorganisms, which were grown at 30 and 35°C, was studied. The average leaching rate of copper was shown to be directly dependent on the copper content in the concentrate. The leaching rate of zinc was found to depend not only on the zinc content but also on the copper content. At the same time, the specific leaching rate of copper varied insignificantly (28–45 mg/(g day)), while the change in the specific leaching rate of zinc was much more pronounced (107–319 mg/(g day)) and depended on the metal contents in the concentrates. Under all conditions of bioleaching, the specific rate of zinc extraction into the aqueous phase increased significantly with an increase in the copper content in the concentrates, which indicated galvanic interactions between sulfide minerals. The possibility of the obtainment of the copper concentrates containing negligible amounts of zinc after bioleaching of the concentrates, in which the content of copper exceeded that of zinc and was not less than 10%, was shown. Bioleaching of the concentrates containing more zinc than copper is impractical.

Comparison of Copper Dissolution in Chalcopyrite Concentrate Bioleaching with Acidianus Brierleyi in Different Initial pH Values

Although bioleaching of chalcopyrite by thermophilic microorganisms enhances the rate of copper recovery, a high temperature accelerates iron precipitation as jarosite, which can bring many operational problems in the industrial processes. In this research work, the bioleaching of chalcopyrite concentrate by the thermophilic Acidianus brierleyi was studied, and the microbial growth, copper dissolution, iron oxidation, and jarosite precipitation were monitored in different initial pH (pHi) values. Bacterial growth was greatly affected by pHi. While the bacterial growth was delayed for 11 days with a pHi value of 0.8, this delay was reduced to nearly one day for a pHi value of 1.2. Two stages of copper recovery were observed during all the tests. A high pHi value caused a fast bacterial growth in the first stage and severe jarosite precipitation in the later days causing a sharp decline in the bacterial population and copper leaching rate. The copper recoveries after 11 days were 25%, 78%, 84%, 70%, 56%, and 39% for the pHi values of 0.8, 1.0, 1.2, 1.3, 1.5, and 1.7, respectively. Sulfur and jarosite were the main residues of the bioleaching tests. It was revealed that the drastic effect of jarosite precipitation on the microbial growth and copper recovery was mainly caused by the ferric iron depletion from solution rather than passivation of the chalcopyrite surface. A slow precipitation of crystalline jarosite did not cause a passive chalcopyrite surface. The mechanisms of chalcopyrite bioleaching were discussed.

The Alteration Mechanism of Copper-bearing Biotite and Leachable Property of Copper-bearing Minerals in Mulyashy Copper Mine, Zambia

The XRF, XRD, polarizing microscopy and SEM-EDS were used to study the alteration mechanism of copper-bearing biotite and the leachable property of copper-bearing minerals in Mulyashy Copper Mine, Zambia. It was found that biotite can be divided into copper-bearing biotite and copper-free biotite. Some copper-bearing biotite existed in the form of monomer, and others aggregated with copper-bearing chlorite, malachite or copper-bearing limonite. The main reason for the occurrence of biotite aggregations was that copper-bearing biotite underwent two kinds of alteration mechanisms as follows: altering into copper-bearing chlorite and malachite, and altering into copper-bearing chlorite and copper-bearing limonite. The order of factors effecting the copper leaching rate of the ores in acid leaching experiments was temperature > sample size > H2SO4 concentration > leaching time > stirring speed. In addition, the copper leaching rate of copper-bearing minerals at different temperatures was in the following order: malachite, chrysocolla and pseudomalachite > copper-bearing chlorite > copper-bearing muscovite > copper-bearing biotite > copper-bearing limonite. The leachable property of biotite is closely related to its special structure.

Sustainable copper extraction from mixed chalcopyrite–chalcocite using biomass

Abstract This paper elaborated on the sustainability of the copper extraction process. In fact, an alternative copper extraction route from mixed sulphide ores, chalcopyrite and chalcocite using mesophilic biomass consortium at 33.3 °C and ferric leaching process were attempted. Bioleaching experiments were settled with a fraction size of −75+53 µm. Bacteria were used as the catalyst. A copper yield of 65.50% was obtained. On the other hand, in ferric leaching process, with a fraction size of −53+38 µm, when the temperature was increased to 70 °C, the copper leaching rate increased to 78.52%. Thus, comparatively, the mesophilic bioleaching process showed a more obvious advantage in copper extraction than leaching process with a high temperature. However, it has been resolved from the characterization performed using SEM−EDS, FTIR and XRD observations coupled with different thermodynamic approaches that, the indirect mechanism is the main leaching mechanism, with three transitory mechanisms (polysulphide, thiosulphate and elemental sulphur mechanisms) for the mixed chalcopyrite−chalcocite ore. Meanwhile, the speciation turns into Cu2S−CuS−Cu5FeS4−Cu2S before turning into CuSO4. While ferrous oxidation and the formation of ferric sulphate occur, and there is a formation of strong acid as bacteria digest sulphide minerals into copper sulphate at low temperature, which is why this copper production scenario requires a redox potential more than 550 mV at room temperature for high copper leaching rate.

Effect of temperature on leaching behavior of copper minerals with different occurrence states in complex copper oxide ores

Abstract The effect of temperature on leaching behavior of copper minerals with different occurrence states in complex copper oxide ores was carried out by phase analysis means of XRD, optical microscopy and SEM−EDS. The results indicated that at ambient temperature, the easily leached copper oxide minerals were completely dissolved, while the bonded copper minerals were insoluble. At lukewarm temperature of 40 °C, it was mainly the dissolution of copper in isomorphism state. With increasing temperature to 60 °C, the copper leaching rate in the adsorbed state was significantly accelerated. In addition, when the temperature increased to 80 °C, the isomorphic copper was completely leached, leaving 11.2% adsorbed copper un-leached. However, the copper in feldspar−quartz−copper−iron colloid state was not dissolved throughout the leaching process. Overall, the leaching rates of copper in different copper minerals decreased in the order: malachite, pseudo-malachite > chrysocolla > copper-bearing chlorite > copper-bearing muscovite > copper-bearing biotite > copper-bearing limonite > feldspar−quartz−copper−iron colloid.

Removal of chemical oxygen demand (COD) and heavy metals by catalytic ozonation-microbial fuel cell and Acidithiobacillus ferrooxidans leaching in flotation wastewater (FW).

A catalytic ozonation-microbial fuel cell and Acidithiobacillus ferrooxidans leaching process was used in treating flotation wastewater to remove chemical oxygen demand (COD) and heavy metals in this study. The results indicated that when adding 1 g/L of manganese/modified activated carbon catalyst and 1.5 g/min ozone flow, the COD could be degraded from 2,043.67 mg/L to 711.4 mg/L. After that, the COD could continue decreasing down to 72.56 mg/L through an air-cathode single chamber microbial fuel cell (SCMFCs), coated with 0.4 mg/cm2 platinum catalyst, after 15 days. Meanwhile, the maximum voltages and the ultimate power density of the SCMFCs reached 378.96 mV and 7,608.35 mW/m2, respectively. For filter residue, when 1.2 g/L Fe3+, 10% (m/v) filter residue, and 10% Acidithiobacillus ferrooxidans were added, the copper leaching rate could reach 92.69% after 7 days if the pH values were adjusted to 1.9. Furthermore, the other heavy metals were also decreased to a level lower than the pollution control standard (Chinese standard GB3838-2002). The leaching parameters in terms of pH, redox potential, and cyclic voltammetry showed that the addition of an appropriate concentration of Fe3+ to the leaching systems was beneficial to copper dissolution.

Effect of mineral composition of sulfidic polymetallic concentrates on non-ferrous metals bioleaching

Bioleaching of sulfidic copper-zinc concentrates with different copper and zinc contents using two consortia of acidophilic microorganisms that grew at 30 and 35 °C was investigated. The average leaching rate of copper is directly proportional to its content in the concentrates and is significantly lower than zinc. Hereby with the ratio of copper and zinc, equal to 7.3, the leaching rates of copper and zinc were 53.8 and 80.3 mg L−1 day−1 in experiment at 30 °C, and 57.1 and 84.2 mg L−1 day−1 respectively in experiment at 35 °C. With the ratio of 1.4, the leaching rates of copper and zinc were 23.1 and 159 mg L−1 day−1 for consortium grew at 30 °C and 25.8 and 168 mg L−1 day−1 for consortium grew at 35 °C, respectively. The specific rates of copper leaching was in the range 22.9–28.1 mg g−1 day−1 at 30 °C and 25.5–31.5 at 35 °C. The specific extraction rate of zinc increased from 216 to 304 mg g−1 day−1 and from 229 to 319 mg g−1 day−1 in the experiments at 30 and 35 °C, respectively, with an increase in the copper-to-zinc ratio for the concentrate from 1.4 to 7.3. Thus, the more copper in the concentrate, the higher the specific rates of zinc leaching, which indicates the galvanic interactions between sulfide minerals. The content of copper in the residues was increased by 3–5% while zinc content decreased from 7.36 and 2.64 to 0.993 and 0.0034%, respectively. The obtained data indicate a high selectivity of zinc bioleaching from copper-zinc concentrates in comparison with copper. The development of research in this direction will improve the efficiency of copper-zinc concentrates processing using bioleaching.

Effect of sulfide mineral content in copper-zinc concentrates on the rate of leaching of non-ferrous metals by biogenic ferric iron

The leaching of copper-zinc concentrates with different sulfide mineral content by biogenic ferric iron has been studied. It was determined that chalcopyrite, sphalerite, pyrrhotite, and pyrite were in the range of 29–55, 11–3.9, 34–14, and 12–13%, respectively. The rate of copper leaching was shown to decrease from 5.1 to 2.6 g/L/h, while its content in the concentrate decreased from 19.2 to 10.1%. The rate of zinc leaching increased from 2.9 to 5.3 g/L/h, while its content in these concentrates increased from 2.64 to 7.36%. The results indicate that the specific rates of copper leaching remained unchanged in all the concentrates studied and were within 0.20 and 0.27 g/g/h. We suggest that this was primarily associated with the dependence of this parameter on the rest potential of chalcopyrite. The specific rate of zinc leaching varied from 0.73 to 1.14 g/g/h and depended significantly on the ratio of contents of sulfide minerals in the concentrates. This rate was also found to increase with an increase in the chalcopyrite content in the concentrate, which indicated the presence of galvanic interactions between the minerals. At the same time, sphalerite and pyrrhotite, which are the minerals with a low rest potential, acted as dissolving anodes, while chalcopyrite and pyrite, having high rest potentials, were cathodes. The possibility of predicting the efficiency of zinc and iron removal during ferric leaching of the copper-zinc concentrates was shown in the context of sulfide mineral content.

The leaching behaviour of Cu, Zn and Pb from waste printed circuit boards by [BSO&lt;SUB align="right"&gt;4HPy]HSO&lt;SUB align="right"&gt;4

Currently, researches are mainly focused on how to recycle valuable metals from waste printed circuit boards (WPCBs), but rarely on the toxic substances, such as zinc and lead, during the recycling process. In this research, the effect of zinc and lead during the process of leaching copper from WPCBs by an acidic ionic liquid (IL), N-sulfobutylpyridinium hydrosulphate ([BSO4HPy]HSO4), was investigated in detail. Results showed that copper and zinc could be successfully leached out by [BSO4HPy]HSO4. When 1 g of 0.1 to 0.25 mm WPCBs powder was leached by 25 mL of 80% (v/v) ionic liquid and 10 mL of 30% hydrogen peroxide at 40°C for 2 h, copper and zinc leaching rate could be up to 99.75% and 93.02%, respectively. H2O2 added amount, solid-liquid ratio and temperature could significantly impact the leaching rate of copper and zinc. On the contrary, lead leaching rate is hardly influenced by these factors, maintaining at around 2%. Thus, during the leaching process, zinc could significantly influence the leaching of copper, which was totally different for lead. Leaching kinetics analysis indicated that the leaching of copper and zinc is controlled by solid film diffusion, and the leaching of lead is controlled by chemical reaction.

Copper leaching from waste printed circuit boards using typical acidic ionic liquids recovery of e-wastes’ surplus value

In this study, using several types of acidic ionic liquids as the leaching reagents, the leaching behaviors of the copper present in waste printed circuit boards (WPCBs) were investigated. The effects of various parameters on the copper leaching rate were studied, such as the particle size of the shredded WPCB, type of ionic liquid used, hydrogen peroxide dosage, solid-to-liquid ratio, leaching temperature, and leaching time. The experimental results showed that the copper leaching rate increases continuously when the powder particle size is increased from 0.071 to 0.500 mm. Moreover, the copper leaching rate also increases with an increase in the leaching temperature. In contrast, the leaching rate first increases and then decreases with increases in the leaching time, hydrogen peroxide dosage, and solid-to-liquid ratio. The optimal conditions that provided a 98.31% copper leaching rate were: particle size >0.500 mm, 8.5 mL 90% (v/v) ionic liquid, 1.5 mL 30% hydrogen peroxide, solid-to-liquid ratio of 1/20, leaching temperature of 80 °C, and leaching time of 2 h.

A comprehensive study of the leaching behavior and dissolution kinetics of copper oxide ore in sulfuric acid lixiviant

The leaching behavior of an Iranian copper oxide ore in sulphuric acid was investigated in detail to evaluate the influence of various factors, to optimize the dissolution conditions and to determine the kinetics of the leaching. The results indicated that the increase in the leaching time and temperature enhanced the leaching rate of copper. The leaching rate increased up to a certain value with increasing the agitation rate, acid concentration and liquid/solid ratio and with further increment reduced. Agitaion rate had the most influence on the dissolution of copper. The 3D response surface graphs confirmed the interactive effects of sulphuric acid concentration, agitation speed, and liquid/solid ratio with temperature. About 91% copper content was leached at~13% sulphuric acid concentration, stirring rate of 600 rpm, liquid/solid ratio of 10 mL/g and 50 °C after 80 min leaching. The dissolution kinetics was examined according to heterogeneous models. The shrinking core model assuming rate control by diffusion through the product layer was found appropriate to describe the dissolution of copper in sulphuric acid solution. The activation energy was obtained to be 26.699 kJ/mol and equation representing the leaching kinetics of copper based on diffusion-controlled model was found to be 1-3(1-x)2/3+2(1-x) = 161.97×exp(-26.699×103/8.314×T)×t.

A novel approach for recovery of metals from waste printed circuit boards and simultaneous removal of iron from steel pickling waste liquor by two-step hydrometallurgical method

Waste printed circuit boards (WPCBs) and steel pickling waste liquor (SPWL) have received extensive attention in recent years because of its harmfulness and resource. In this work, two-step leaching process was carried out by using SPWL as the leaching agent. A series of continuously domesticated bacteria were used for bioleaching and the bacterial strain was identified as Acidithiobacillus ferrooxidans (A. ferrooxidans) by 16S rDNA gene sequence analysis. The vast majority of the metals in WPCBs were recovered by two-step leaching, such as Cu, Pb, Zn, Sn, Al, Ni. Meanwhile, a large amount of iron was removed from SPWL, which greatly reduces the burden of the subsequent treatment. Pulp density and pH were optimized to achieve maximum recovery of copper and simultaneous removal of iron in bioleaching. It was found that the optimum conditions were pulp density 60 g/L and pH 0.5–1.0. Nearly 100% of copper was recovered and 51.94% of iron was removed under optimum conditions. The kinetic experiments showed that the rate of copper leaching was controlled by external diffusion rather than internal diffusion, because the acidic environment of the leachate prevented the formation of the precipitate and maintained it in a smaller size.

The effects of grooming on a copper ablative coating: a six year study

More than 90% of US Navy Ships are coated with copper ablative paint. These ships may spend long periods of time pier-side, which makes them vulnerable to fouling. Hull grooming has been proposed as a means of maintaining the coatings in an operational condition. This study investigated the effect of grooming on a copper ablative coating exposed statically for six years. Grooming was performed weekly or monthly with controls left ungroomed. The fouling community was visually assessed, dry film thickness measurements were taken to monitor coating loss, and the copper leaching rates were measured. It was found that weekly and monthly groomed surfaces reduced fouling, and the ungroomed surfaces became fully fouled. Coating loss was similar for weekly, monthly and ungroomed surfaces. The results suggest that grooming is a viable method for maintaining copper ablative coatings in a fouling-free condition without adverse increases in the total copper output.

Recovering copper from volcanic ASH by NH3 · H2O–NH2COONH4

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.

Effects of processing pH stimulation on cooperative bioleaching of chalcopyrite concentrate by free and attached cells

In order to investigate the effects of processing pH stimulation on bioleaching of chalcopyrite by moderate thermophiles, copper leaching rates and the dynamics of microbial community structures of free and attached cells were monitored. The results indicated that when the processing pH values were respectively adjusted to 1.0 and 3.0 on day 14, both free and attached cells experienced an adaptive phase. Meanwhile, the copper leaching rates were 86.9% and 64.0%, respectively, as opposed to a copper leaching rate of 87.5% in the control group without pH stimulation. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis suggested that pH stimulation imposed less impact on the attached organisms than on the free cells, indicating that the attached cells were more resistant to processing pH stimulation than the free cells. Furthermore, adjusting processing pH to 3.0 significantly disrupted both free and attached microbial communities, and the bioleaching system could not recover to the normal status as the control group.