Leaching Of Copper Ore Research Articles

Copper sulfide precipitation from alkaline monosodium glutamate solutions

Recent studies of metal leaching using monosodium glutamate have shown promising results of this being an alternative to conventional leaching reagents. However, limited information is available covering the treatment of leaching solutions and the final recovery of metals. In this regard, this article presents an experimental study on the precipitation of copper from glutamate solutions using sodium hydrosulfide (NaHS), as a simple and efficient route for the processing of leaching solutions from this new system. Synthetic pregnant leach solutions (PLS) with varying copper total concentrations [CuT] and glutamate concentrations were used. The effects of [CuT], [CuT]:[NaHS] molar ratio and glutamate concentration on the particle size distribution and copper recovery were investigated. The results revealed that higher [CuT] led to smaller particle sizes, with the P90 decreasing from 106 µm to 60.7 µm and 73.2 µm for Cu concentrations of 1 g/L, 2.5 g/L, and 5 g/L, respectively. The [CuT]:[NaHS] molar ratio reduced the P90 particle size, from 60.7 µm to 56.4 µm and 7.44 µm as the molar ratio increased from 1:0.8 to 1:1 and 1:1.2, respectively. Copper recovery from glutamate solutions increased with higher molar ratios, achieving values of 70.95 %, 88.24 %, and 99.55 % for molar ratios of 1:0.8, 1:1, and 1:1.2, respectively, agreeing with copper recovery values of other chemical systems. The glutamate concentration had minimal impact on particle size but affected copper recovery, with a decrease from 88.24 % to 85.83 % when increasing the glutamate concentration from 0.5 M to 1 M. X-ray diffraction (XRD) analysis confirmed the presence of pure covellite with hexagonal phase in the precipitates. These findings contribute to understanding copper precipitation dynamics from glutamate solutions using NaHS and have implications for optimizing copper recovery processes in the perspectives of the advent of alkaline leaching of copper ores.

Extraction of Cu(II), Fe(III), Zn(II), and Mn(II) from Aqueous Solutions with Ionic Liquid R4NCy

The leaching of copper ores produces a rich solution with metal interferences. In this context, Fe(III), Zn(II), and Mn(II) are three metals contained in industrial copper-rich solutions in high quantities and eventually can be co-extracted with the copper. The purpose of the current study was to determine the feasibly of solvent extraction with the use of ionic liquid methyltrioctyl/decylammonium bis (2,4,4-trimethylpentyl)phosphinate (R4NCy) as an extractant of Cu(II) in the presence of Fe(III), Zn(II), and Mn(II). In general terms, the results showed a high single extraction efficiency of all the metals under study. In the case of Fe(III) and Zn(II), the extraction was close to 100%. On the contrary, the stripping efficiency was poor to Fe(III) and discrete to Zn(II), but very high to Cu(II) and Mn(II). Finally, the findings of this study suggest that the ionic liquid R4NCy is feasible for the pre-treatment of the copper solvent extraction process to remove metal impurities such as Fe(III) and Zn(II).

The effect of radio-waves irradiation on copper-ore leaching

In this study, focused radio wave (RW) assisted leaching was investigated for the first time to considerably enhance the efficiency of copper leaching from its low-grade ores. For this purpose, the effect of exposure to radio wave electromagnetic irradiation was experimentally investigated. Two series of leaching tests were conducted, in the form of agitated slurry and fixed-bed column modes. The experimental results indicated a significant improvement of recovery in both modes. The most probable mechanisms for enhanced recoveries could be the dielectric heating through concentrated irradiation. For less than 24 h of leaching in the fixed-bed column under irradiation, the recovery improved by about 40% (~60% for leaching vs. ~100% for RF leaching), as compared to the same tests with no irradiation, while the agitated leaching tests showed an increase of up to 10% under irradiation. It is concluded that electromagnetic technology, even in the range of radiofrequency (<109 Hz), has the potential to be used to improve the rate and the final copper recovery from copper ores.

Accelerating leaching of copper ore with surfactant and the analysis of reaction kinetics

To solve the problem of low permeability and lower extraction rates of high-mud ores, a surfactant was added as a penetrant to the pregnant leaching solution during column leaching tests. On the basis of the theories of physical chemistry and seepage flow mechanics, the mechanism by which seepage is enhanced under the effects of the surfactant was analyzed. The results show that the action modes of the surfactant were divided into four aspects: changing the wettability of the ore, reducing the viscosity of the leaching solution, adsorbing onto the surface of ore, and enhancing the permeability effect. The findings of column leaching tests demonstrated that permeability was substantially improved by the surfactant. In the later period of leaching, the permeability coefficient was two times higher than that of the control group. Meanwhile, the ore extraction rate increased by approximately 10%. During the leaching process, the surface tension of the solution did not substantially change, and that of the solution with surfactant increased slightly. The kinetics analysis of ore column leaching illustrated that the leaching processes were controlled by both internal diffusion (principal factor) and chemical reaction.

Investigation of Usability of Fatty Acids as Copper Extractant from Leached Copper Ore

This paper presents an experimental study on leaching and solvent extraction of copper from low-grade copper ore mined from Nasarawa (Nigeria) by fatty acids in petroleum-based diluents - methyl isobutyl ketone (MIBK), styrene, and kerosene. The leaching investigation showed that the optimum temperature, contact time, and H2SO4 concentration are 91.5oC, 39 minutes, and 2.9 M, respectively. Response Surface Methodology (RSM) was adopted for the optimization of the leaching conditions. The aqueous solution obtained from leaching of copper ore in sulfuric acid was used for the solvent extraction. The extraction studies showed that fatty acids in a petroleum-based organic solvent is an effective extractant for solvent extraction of copper. The fatty acids used in the studies were obtained by acidifying the soap that was produced when vegetable oil was treated with sodium hydroxide. It was also observed that diluents affect the percentage extraction of copper. Styrene achieved the highest percentage extraction, followed by kerosene and MIBK at 80 % and 90 % v/v diluents in fatty acids.

Studies on hydrometallurgical processes using nuclear techniques to be applied in copper industry. I. Application of 64Cu radiotracer for investigation of copper ore leaching

Abstract Scientifi c objective of this work was elaboration of radiometric method for the development of hydrometallurgical process for recovery of Cu from the copper ore. A neutron activation analysis (NAA) was identifi ed as a very convenient tool for the process investigation. The samples of copper ore were activated in a nuclear reactor. The parameters of the neutron activation were calculated. Radioisotope 64Cu was selected as an optimal tracer, and it was used for the investigation of the leaching process. During the experiments, various processes applying leaching media such as sulphuric acid, nitric acid, and organic acids were investigated. The recovery of the metals using sulphuric acid was insuffi cient, around 10%. Investigated organic media also did not meet expectations. The best results were obtained in experiments with nitric acid. Up to 90% of Cu and other metals were extracted from the copper ore. Copper concentration calculations obtained by NAA were confi rmed by inductively coupled plasma mass spectrometry (ICP-MS) technique. Both techniques gave comparable results, but the advantage of the NAA is a possibility for easy online measurements without shutting down or disturbing the system.

Percolation bacterial leaching of low-grade copper ore

The article describes results of research on copper recovery from low-grade copper ore by heap bioleaching method. The objects of investigation are ores of the Benkala deposit. Results of chemical analysis by atomic-emission spectrometric method and chemical phase analysis present ores element composition and identify copper and iron forms existing in the ores. Ores were subjected to bioleaching by chemolithotrophic bacteria, which oxidizes sulfur and iron compounds. Acidithiobacillus ferrooxidans FT-24 and BF, Acidithiobacillus thiooxidans BS, Acidithiobacillus ferrivorans SU-8 and Sulfobacillus thermosulfidooxidans ST-12 strains were used in the research. It was modeling the process of bacterial heap leaching of low-grade ore in percolation columns. Comparison of efficiency of sulfuric acid and bacterial leaching in percolation columns shows advantage of bioleaching. The copper yield was 47 % at using conventional sulfuric acid leaching, while utilizing bacterial leaching increased the copper recovery up to 86 % during 90 days of the experiment. The values of oxidation-reduction potential (ORP) at sulfuric acid and bacterial leaching of copper ore presented are in accordance with yield of copper. The values of ORP at standard sulfuric acid leaching are between 330-360 mV, at bacterial leaching more high and are 480-550 mV due to high content of ferric iron. During the extraction of copper, the effect of the organic reagent LIX 984N in concentrations 50 and 250 mg/L on the activity of microorganisms was studied. As a result, the extraction reagent has a little effect on the growth of microorganisms and the extraction of copper. Without adding the extraction reagent, the total copper recovery was about 83 %, while the addition of the extraction reagent with concentration 250 mg/L decreased it to 81 %. So using bioleaching technology allows deep processing of copper ore due to oxidation of copper sulfide minerals.

Implementation of biological and chemical techniques to recover metals from copper-rich leach solutions

Pregnant leach solutions (PLS) resulting from (bio)leaching of copper ores are characterized by low pH, high concentrations of Fe (III), Cu, Zn and often significant amounts of Ni and Co. In order to make the metals available for further processing they require selective recovery form the acidic, multi-metal solution. Commonly, copper and other base metals are recovered by solvent-extraction/electro-winning (SX/EW) technologies from acidic, metal-rich solutions. This study describes the application of chemical and microbiological process steps for the selective recovery of base metals from the PLS. A multi-stage metal recovery system, involving initial Cu-SX/EW to recover copper, followed by iron hydroxy sulfate precipitation to recover the high amounts of these two metals before introducing the more sensitive biological step, is proposed. The biological route is based on a sulfidogenic bioreactor housing acidophilic bacteria producing hydrogen sulfide directly from the acidic, sulfate-rich PLS. The bioreactor promotes and controls the selective precipitation of CuS and ZnS in two connected vessels and the recovery of Ni and Co as metal sulfides within the bioreactor. The sulfidogenic system has additionally the advantage of lowering the sulfate concentration of the PLS and contribution to an increase in pH. A parallel alternative chemical metal recovery pathway allows the selective recovery of remaining Cu and other metals (e.g. Zn, Co, Ni) via ion exchange (IX). Both the biological and chemical routes lead to a modified PLS which can be reintroduced into the bioleaching operation. Silver and lead are recovered from solid (bio)leach residues by hot brine leaching. The system has been designed to selectively recover all relevant metals from the PLS following a zero waste concept, and its modular arrangement allows an independent operation of the units and the integration of further modules, depending on the nature of the leach solutions.

Simultaneous acid exposure and erosive particle wear of thermoset coatings

Handling acidic chemicals is a challenge in the chemical industry, requiring a careful choice of contact material. Certain thermoset organic coatings are applicable in low pH environments, but when particulate erosion is also present the performance demand is increased. This is the case in, e.g., stirred tanks for agitated leaching of copper ore, where sulfuric acid is mixed with an erosive slurry. A pilot-scale agitated leaching tank was designed and constructed to explore the performance of selected thermoset coatings in such an environment. For reference, simple immersion experiments were conducted. Coating durability was estimated by observing the film thickness change during exposure. It was found to be a function of film swelling and film contraction, due to chemical exposure, as well as the “polishing” caused by erosive wear. Film reduction rates varied with radial position in the tank bottom-placed coating samples. Maximum rates were found about halfway between the reactor center and wall. Polishing rates also varied significantly with acid concentration, most likely due to chemical reactions taking place between the acid and the coatings, damaging surface mechanical properties, similar to the erosion/corrosion-type phenomena found in metals. A vinyl ester-based coating was the most resistant to the simultaneous erosive/acidic exposure, with a maximum polishing rate of $$3.24\,\pm \,0.61$$ $$\upmu$$ m/week, while novolac epoxy and polyurethane coatings showed high polishing rates of $$11.7 \pm 1.50$$ and $$13.4 \pm 0.57\,\upmu \hbox {m}$$ /week, respectively.

Effect of Carbon Black on Copper Ore Leaching in Sulfuric Acid Media at 50°C

Effect of Carbon Black on Copper Ore Leaching in Sulfuric Acid Media at 50°C

Primary Copper Ore Leaching by Leaching Solution Adjusted Oxidation-Reduction Potential in Column

Copper ore is classified into three groups; primary copper sulfide, copper oxide and secondary copper sulfide. Leaching copper from primary copper sulfide, such as chalcopyrite, with sulfuric acid takes longer time than from copper oxide and secondary copper sulfide. As such, an oxidant is required to extract copper from chalcopyrite. In this study, column leaching tests were carried out using primary copper sulfide ores produced in an iron oxide copper gold (IOCG) deposit and rich in iron in coparison to porphyry copper ores. The columns of 10 cm diameter and 100 cm long had a double tube structure so that the column temperature can be kept at desired temperature by circulating warm water in the outer tube. The oxidation-reduction potential (ORP) of the leaching solutions were adjustedto 400, 450 and 500 mV vs Ag/AgCl. The column leaching test using just pH 2.0 sulfuric acid without adjustment of ORP at 45 °C got a copper recovery rate of 37 % in 400 days. On the other hand, with ORP adjusted leaching solutions of pH 2.0 sulfuric acid containing 500 mg/L Fe, the copper recovery rate reached up to 87 % in 400 days.In addition, it was necessary to keep the temperature above 45 oC to enhance copper leaching by ORP adjusted leaching solution. The result of the column leaching test at room temperature (around 30 °C) using ORP adjusted leaching solution shows that the recovery rate of copper is lower than the result at 45 °C. The ORP adjustment of leaching solution is effective for leaching copper from primary copper sulfide ore, however, the leaching temperature needs to be kept above 45 °C. As a result, it makes clear that copper leaching is enhanced by utilization of ORP adjusted leaching solutions and suggests that the solution ORP control is important to the application of bioleaching.

Studies of leaching of copper ores and flotation wastes

In Poland, there are significant deposits of copper ores. During the copper extraction, large amounts of flotation wastes are produced. In the ores and flotation wastes many other important elements are present. The main goal of this work was analysis of uranium content and to elaborate procedures for recovery of U from these materials. Two types of ores and four types of waste were examined. It has been found that uranium content varies from 4.5 to 25 ppm. The other elements have also been determined in these materials: Cu (4–5 % in ores and 0.3–1.7 % in waste), Ag, Re, Mo, La, Ni, V, etc. For leaching, sulfuric acid and sodium carbonates of various concentrations (temperature, time) were used. The optimum conditions for leaching have been found. The concentration of uranium in the final solution was generally less than 25 μg/mL. The other elements are also present in the leaching solutions. Simultaneous liquid–liquid extraction of uranium with these elements from leaching solution is under study. In our opinion, only such combined procedure for the recovery of uranium together with the accompanying elements could be cost-effective.

Leaching of copper ore of the Udokanskoe deposit at low temperatures by an association of acidophilic chemolithotrophic microorganisms

Pure cultures of indigenous microorganisms Acidithiobacillus ferrooxidans strain TFUd, Leptospirillum ferrooxidans strain LUd, and Sulfobacillus thermotolerans strain SUd have been isolated from the oxidation zone of sulfide copper ore of the Udokanskoe deposit. Regimes of bacterial-chemical leaching of ore have been studied over a temperature range from -10 to +20 degrees C. Effects of pH, temperature, and the presence of microorganisms on the extraction of copper have been shown. Bacterial leaching has been detected only at positive values of temperature, and has been much more active at +20 than at +4 degrees C. The process of leaching was more active when the ore contained more hydrophilic and oxidized minerals. The possibility of copper ore leaching of the Udokanskoe deposit using sulfuric acid with pH 0.4 at negative values of temperature and applying acidophilic chemolithotrophic microorganisms at positive values of temperature and low pH values was shown.

Evaluation of stucco binder for agglomeration in the heap leaching of copper ore

It is known that the presence of excess fines in heap leaching operations may cause low recovery due to reduced heap permeability and/or channeling of lixiviant flow. These problems are mitigated to some extent by agglomeration pretreatment prior to heap leaching. Sulfuric acid leach solution is the conventional liquid bridge used for copper ore agglomeration, but these agglomerates exhibit poor stability when compared to the agglomerates formed using stucco binder, calcium sulfate hemihydrates, CaSO 4·½H 2O. Results obtained from agglomeration experiments on the Zaldivar ore reveal that the stucco hydration reaction provides the agglomerates with more stability, increased size with less release of fines, and better permeability of the packed agglomerate bed. A phase diagram has been constructed to identify preferred agglomeration conditions. Finally a proposed description for the action of stucco binder during the agglomeration process is presented and discussed.

Investigation into the heap leaching of copper ore from the Disele deposit

Heap leaching of malachite–atacamite ores with high silica gangue using sulphuric acid is reported. The base metals were present in the ores in copper rich nodules with a network of fine strings rich in cobalt and manganese along the quartz grain boundaries. It was observed that leaching of copper was quicker and the corresponding recovery of copper was consistently higher when the ore particle was finer. The recovery of copper measured at different leaching times revealed that the efficiency of the process was better enhanced by refinement of the ore particle size than by increasing the concentration of sulphuric acid in the lixiviant from 60 to 120 g/L. Iron contamination in the pregnant leach solution (PLS) subsequently increased as the initial acid concentration in the lixiviant increased. The water loss during the heap leaching process was higher when the ore particle size was finer and when the concentration of sulphuric acid in the lixiviant was higher. Leaching residues typically contained 92% SiO 2 and 4% muscovite.

Ferrous iron oxidation and leaching of copper ore with halotolerant bacteria in ore columns

Growth on ferrous iron of a new isolate of the acidophile Thiobacillus prosperus occurred with a substrate oxidation rate similar to that of Acidithiobacillus ferrooxidans. As well as similar capacities for iron oxidation, these species were shown to possess similar, but not identical, clusters of genes (the rus operon) that encode proteins likely to be involved in transfer of electrons from ferrous iron. Abundant rusticyanin was present in acidified, cell-free extracts of T. prosperus. In contrast to these similarities between the species, T. prosperus grew at a salt (NaCl) concentration several times that which prevented growth of A. ferrooxidans. A mixed culture of halotolerant bacteria maintained continuous ferrous iron oxidation in the presence of 5% w/v NaCl in solution percolating through ore in laboratory columns, and so enhanced ferric iron-dependent solubilization of copper.

Convergence of a MFE–FV method for two phase flow with applications to heap leaching of copper ores

In this paper we describe error estimates for a finite element approximation to partial differential systems describing two-phase immiscible flows in porous media, with applications to heap leaching of copper ores. These approximations are based on mixed finite element (MFE) methods for the pressure and velocity and finite volume (FV) for the saturation. The fluids are considered incompressible. Numerical results for heap leaching simulation are presented.

Flow through porous media with applications to heap leaching of copper ores

The classical equations of two-phase flow in a porous media are solved together with two transport equations representing the leaching process. For the two-phase flow we use the pressure-saturation formulation, where the principal variables are the total pressure, the total flux and the saturation of the liquid phase. For the transport equations the variables of interest are the sulfuric acid and the copper concentration. The numerical method combines a mixed finite element method with a finite volume method. The first one is used to approximate the total pressure and flux, while the second is used to calculate the saturation and both concentrations. The advantage of this approach is its capacity to completely characterize the dynamics of the liquid and gaseous phase, and treat with the same model acid and bio-leaching processes. Several examples show the application of the method.

Elements Influencing Cost Allocation in the Pinal Creek Aquifer, Arizona, USA: An Introduction and Synopsis of Findings

This article provides context for the ensuing three-part study published in this volume that describes quantitative allocation of mass metal loading to the 20 km groundwater plume in the Pinal Creek alluvial aquifer. The plume resulted from >75 years of copper ore leaching by ferric sulfate and sulfuric acid in the Globe-Miami mining district, Arizona. Geochemical fingerprinting, followed by spatial and temporal analysis of Pinal Creek monitoring well data, identified three distinct source areas and plumes. Each exhibited a unique chlorine-copper-iron chemical signature that resulted from differences in process geochemistry, ore mineralogy, and solution handling. As the acid plume advanced, carbonate buffering capacity was consumed, with concomitant precipitation of metal oxyhydroxides that evolved into acid-bearing aluminum and iron cements. Column experiments, geochemical modeling, and empirical data indicate that dissolution of the residual acidic precipitates will result in asymptotic reductions in metal concentrations, which will affect response costs for up to 140 years after initiation of remedial pumping in the late 1980s. Finally, metal loading to the alluvial aquifer was quantified for each source area using Darcy's Law or flow data combined with the sum of aluminum, copper, iron, manganese, and zinc, which constitute >99% of the total metal mass. Based on this analysis, to date Webster Gulch contributed 94% of the loading, Upper Bloody Tanks Wash contributed 5%, and the Miami Unit contributed 1%. A sensitivity analysis that varied all parameters in the loading calculation by ±20% resulted in only small differences in allocation (±1%) because the large mass released from Webster Gulch (618 kt of metal) dominates the overall allocation.

Model for ferric sulfate leaching of copper ores containing a variety of sulfide minerals: Part II. Process modeling of in situ operations

The Lin-Sohn Leach simulation (DLS) computer model was used to simulate copper extraction from run-of-mine fragment size distributions expected for underground modifiedin situ solution mining. Ventilation was found to be a key variable in obtaining good copper recoveries, and the rate of ventilation was found to vary with ore type and through time. Improving recoveries and recovery rates with improved fragmentation was found to be more difficult than expected. Limitations on surface kinetics and bacterial ferric ion generation often erode benefits expected from reduction in diffusion limitation. Control of fines formation is difficult with the current state of the art in blasting. Fines may also improve the initial leaching rate at the expense of increased ventilation cost and more limited ultimate recovery. Ore grade was found to be less important to solution mining than to conventional copper recovery. Mineralogy was found to be crucial to solution mining economics. Mineralogy affects the grade of the ore and the importance of that grade. Pyrite was found to be helpful in increasing the ultimate copper recovery from ore but, at the same time, was found to reduce the rate of that recovery. Recovery rates were found to be very sensitive to mineral grain size, and calibration of DLS to a given ore may be especially important in this variable. Tortuosity and porosity of ore fragments appear relatively unimportant over the ranges typical of sulfide copper porphyry ore. Modifiedin situ solution mining appears to be a competitive option when a favorable ore type is available. The DLS computer code may be a valuable aid in screening options and selecting the most favorable orebodies.