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The dissolution of copper sulphide ores continues to be a challenge for the copper industry. Several media and leaching alternatives have been proposed to improve the dissolution of these minerals, especially for the leaching of chalcopyrite. Among the alternatives, pretreatment prior to leaching was proposed as an option that increases the dissolution of copper from sulphide ores. In this study, a mineral sample from a copper mining company was used. The copper grade of the sample was 0.79%, and its main contributor was chalcopyrite (84%). The effect of curing time (as pretreatment) in a chloride media on copper sulphide ore was evaluated at various temperatures: 25, 50, 70 and 90 °C. The pretreated sample and leaching residues were characterized by X-ray diffraction, scanning electron microscopy, and reflected light microscopy. Pretreatment products such as CuSO4, NaFe3(SO4)2(OH)6, and S0 were identified although with difficulty, due to the low presence of chalcopyrite in the initial sample (1.99%). Under the conditions of 15 kg/t of H2SO4, 25 kg/t of NaCl, and 15 days of curing time, a copper extraction of 93.1% was obtained at 90 °C with 50 g/L of Cl− and 0.2 M of H2SO4.
Víctor Quezada; Antoni Roca; Oscar Benavente; Montserrat Cruells; Evelyn Melo; María Hernández. Pretreatment to Leaching for a Primary Copper Sulphide Ore in Chloride Media. Metals 2021, 11, 1260 .
AMA StyleVíctor Quezada, Antoni Roca, Oscar Benavente, Montserrat Cruells, Evelyn Melo, María Hernández. Pretreatment to Leaching for a Primary Copper Sulphide Ore in Chloride Media. Metals. 2021; 11 (8):1260.
Chicago/Turabian StyleVíctor Quezada; Antoni Roca; Oscar Benavente; Montserrat Cruells; Evelyn Melo; María Hernández. 2021. "Pretreatment to Leaching for a Primary Copper Sulphide Ore in Chloride Media." Metals 11, no. 8: 1260.
An option to improve the leaching efficiency of chalcopyrite is pretreatment prior to leaching. Pretreatment variables, such as the curing time and the addition of chloride, can increase the kinetics of copper extraction, particularly for sulphide ores. However, there has been little research on the topic. The reactions that govern this phenomenon have not been clearly identified. In this study, the effects of sulphuric acid and sodium chloride agglomeration and curing on chalcopyrite leaching were evaluated at various temperatures: 25, 50, 70, and 90 °C. The pretreated ore and leach residues were characterised by X-ray diffraction, scanning electron microscopy, and reflected light microscopy. Under the conditions of 15 kg/t of H2SO4, 25 kg/t of NaCl, and 15 days of curing time (as pretreatment), the following products were identified: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH), and S0. Increasing the curing time and leaching temperature increased copper leaching. The copper extraction was 94% when leaching at 90 °C after pretreatment with 50 g/L of Cl− and 0.2 M of H2SO4. Elemental sulphur, jarosite, and copper polysulphide (CuS2) were detected in the leaching residues.
Víctor Quezada; Antoni Roca; Oscar Benavente; Montserrat Cruells; Evelyn Melo. The Effects of Sulphuric Acid and Sodium Chloride Agglomeration and Curing on Chalcopyrite Leaching. Metals 2021, 11, 873 .
AMA StyleVíctor Quezada, Antoni Roca, Oscar Benavente, Montserrat Cruells, Evelyn Melo. The Effects of Sulphuric Acid and Sodium Chloride Agglomeration and Curing on Chalcopyrite Leaching. Metals. 2021; 11 (6):873.
Chicago/Turabian StyleVíctor Quezada; Antoni Roca; Oscar Benavente; Montserrat Cruells; Evelyn Melo. 2021. "The Effects of Sulphuric Acid and Sodium Chloride Agglomeration and Curing on Chalcopyrite Leaching." Metals 11, no. 6: 873.
The need to sustainably produce raw materials encourages mining companies to develop and incorporate new economically and environmentally efficient processes. Therefore, there is a need to investigate the behavior and stabilization of hazardous elements present in effluents from metal recovery processes such as arsenic. This study evaluates the incorporation of an effluent solution from a copper smelter that is to be treated in a copper hydrometallurgical plant (heap leaching). The treatment is applied to recover compounds of interest such as copper, acid and water, in addition to confining impurities as stable residues in the leach residues. Here, we assess the capacity of the mineral to retain arsenic. To do this, a mixed solution of effluent and process solution was prepared, with a concentration of 1 g/L of arsenic. The solution was irrigated in leach columns loaded with a heap mineral with varying pH levels (0.8; 1.5 and 2) and solution potentials (510 and 540 mV). The concentrations of arsenic and iron in the solution and in the solid residues were measured to determine the capacity of the mineral to retain arsenic and how it was retained. The pH level plays an important role since, at a higher pH, the presence of arsenic and iron in the solution decreases, therefore increasing in the solid residue. Finally, a retention of 57% of arsenic is reached at pH 2. The characterization of the residues by scanning electron microscopy (SEM) confirms that arsenic is associated with Fe, S and O, forming ferric arsenates, while an X-Ray analysis identifies the arsenic compounds as crystalline scorodite.
Oscar Benavente; María Cecilia Hernández; Evelyn Melo; Víctor Quezada; Yan Sepúlveda; Yuri Zepeda. Stabilizing Arsenic in Copper Heap Leaching Residues. Metals 2020, 10, 1242 .
AMA StyleOscar Benavente, María Cecilia Hernández, Evelyn Melo, Víctor Quezada, Yan Sepúlveda, Yuri Zepeda. Stabilizing Arsenic in Copper Heap Leaching Residues. Metals. 2020; 10 (9):1242.
Chicago/Turabian StyleOscar Benavente; María Cecilia Hernández; Evelyn Melo; Víctor Quezada; Yan Sepúlveda; Yuri Zepeda. 2020. "Stabilizing Arsenic in Copper Heap Leaching Residues." Metals 10, no. 9: 1242.
This article presents the behavior of black copper minerals in reducing acid leaching using FeSO4 as reducing agent. The original sample, which was a blend of green and black copper minerals, was treated first by an oxidizing acid leach using O3 to dissolve the soluble phase (green copper oxides). The residue (mainly black copper) was evaluated by agitated leaching under three different solution potentials, with respect to the standard hydrogen electrode (SHE) (450, 500, and 600 mV (SHE)) at 25 °C. The original sample and the leach residue were characterized by scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The O3 leach residue was 1.43% copper, with 50% of the insoluble phase associated with copper pitch, copper limonites, and unreacted chrysocolla. The results of leaching using FeSO4 demonstrate that it is possible to obtain 90% copper extraction using a solution with a potential of 450 mV, while leaching at 600 mV resulted in 65% copper extraction. Acid consumption was 40 kg/t in the test at 450 mV, followed by 30 kg/t in the 500 mV test, and finally 25 kg/t in the 600 mV test, showing that reactivity decreases with increased solution potential. The results show that retreatment of a leaching residue is possible, considering the presence of copper pitch, copper limonites, and chrysocolla as the main copper contributing minerals. Modeling of copper extraction with nonlinear regression is proposed. The retreatment of residues resulting from conventional acid leaching can be an alternative to make use of the treatment capacity of hydrometallurgical plants.
Víctor Quezada; Oscar Benavente; Cristopher Beltrán; Danny Díaz; Evelyn Melo; Antonio García. Dissolution of Black Copper Oxides from a Leaching Residue. Metals 2020, 10, 1012 .
AMA StyleVíctor Quezada, Oscar Benavente, Cristopher Beltrán, Danny Díaz, Evelyn Melo, Antonio García. Dissolution of Black Copper Oxides from a Leaching Residue. Metals. 2020; 10 (8):1012.
Chicago/Turabian StyleVíctor Quezada; Oscar Benavente; Cristopher Beltrán; Danny Díaz; Evelyn Melo; Antonio García. 2020. "Dissolution of Black Copper Oxides from a Leaching Residue." Metals 10, no. 8: 1012.
This article presented the behavior of ores containing black copper under acid leaching. The solution potential was modified by adding agents, and five leaching conditions were evaluated, one as a control based on sulfuric acid leaching (conventional), and the others by changing the solution potential with: ferrous sulfate (FeSO4), white metal (Cu2S), sulfur dioxide (SO2), and ozone (O3). Leaching behavior was evaluated with laboratory bottle (ISO-pH) and column leaching tests. Two ores samples from the Lomas Bayas mine were used. The samples, identified as low (LG) and high grade (HG), were characterized as 0.13–0.25% Cu and 0.15–0.38% Mn, respectively. The mineralogical analysis indicated that black copper represented around 20% of total Cu (0.05% Cu). The results of the bottle tests indicated that the solution potential decreased with the addition of reducing agents, while the copper extraction rate with the HG sample increased to 83.7%, which exceeded the extraction rate obtained by conventional acid leaching by 25%. Ozone did not favor the extraction of Mn and Cu extraction when the solution potential increased. Cu and Mn extraction were directly related. The results of the column leaching tests showed that it was possible to maintain the solution potential at values below 600 mV (SHE) with the addition of white metal and sulfur dioxide while obtaining the highest copper extraction rate of approximately 60%, which was 18% higher than the rate obtained with conventional leaching. Sulfuric acid consumption was 11 kg/t over 45 days of leaching.
Oscar Benavente; Ma.Cecilia Hernández; Evelyn Melo; Luis Ardiles; Víctor Quezada; Yuri Zepeda. Copper Extraction from Black Copper Ores through Modification of the Solution Potential in the Irrigation Solution. Metals 2019, 9, 1339 .
AMA StyleOscar Benavente, Ma.Cecilia Hernández, Evelyn Melo, Luis Ardiles, Víctor Quezada, Yuri Zepeda. Copper Extraction from Black Copper Ores through Modification of the Solution Potential in the Irrigation Solution. Metals. 2019; 9 (12):1339.
Chicago/Turabian StyleOscar Benavente; Ma.Cecilia Hernández; Evelyn Melo; Luis Ardiles; Víctor Quezada; Yuri Zepeda. 2019. "Copper Extraction from Black Copper Ores through Modification of the Solution Potential in the Irrigation Solution." Metals 9, no. 12: 1339.
Black copper oxides are amorphous materials of copper-bearing phases of manganese. They are complex mineral compounds with difficult to recognize mineralogy and have slow dissolution kinetics in conventional hydrometallurgical processes. This study evaluates the effects of various leaching media on copper dissolution from black copper minerals. Leach of a pure black copper sample from Lomas Bayas Mine and another from a regional mine were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), scanning electron microscopy (SEM), Qemscan and mechanically prepared for acid leaching under standard, oxidizing and reducing conditions through the addition of oxygen, iron sulfate or sulfur dioxide, respectively. Standard and high potential leaching (770 mV (SHE)) results in a copper dissolution rate of 70% and manganese dissolution rate of 2%. The addition of potential reducing agents (FeSO4 or SO2) decreases the redox potential to 696 and 431 mV, respectively, and favors the dissolution of manganese, thus increasing the overall copper extraction rate. The addition of SO2 results in the lowest redox potential and the highest copper extraction rates of 86.2% and 75.5% for the Lomas Bayas and regional samples, respectively, which represent an increase of 15% over the copper extract rates under standard and oxidizing conditions.
Oscar Benavente; María Cecilia Hernández; Evelyn Melo; Damián Núñez; Víctor Quezada; Yuri Zepeda. Copper Dissolution from Black Copper Ore under Oxidizing and Reducing Conditions. Metals 2019, 9, 799 .
AMA StyleOscar Benavente, María Cecilia Hernández, Evelyn Melo, Damián Núñez, Víctor Quezada, Yuri Zepeda. Copper Dissolution from Black Copper Ore under Oxidizing and Reducing Conditions. Metals. 2019; 9 (7):799.
Chicago/Turabian StyleOscar Benavente; María Cecilia Hernández; Evelyn Melo; Damián Núñez; Víctor Quezada; Yuri Zepeda. 2019. "Copper Dissolution from Black Copper Ore under Oxidizing and Reducing Conditions." Metals 9, no. 7: 799.
Due to the depletion of oxidized copper ores, it necessitates the need to focus on metallurgical studies regarding sulphide copper ores, such as chalcopyrite. In this research, the electrochemical behaviour of chalcopyrite has been analysed under different conditions in order to identify the parameters necessary to increase the leaching rates. This was carried out through cyclic voltammetry tests at 1 mV/s using a pure chalcopyrite macro-electrode to evaluate the effect of scan rate, temperature, and the addition of chloride, cupric, and ferrous ions. Lastly, the feasibility of using seawater for chalcopyrite dissolution was investigated. An increase in the sweep rate and temperature proved to be beneficial in obtaining highest current densities at 10 mV/s and 50 °C. Further, an increase of chloride ions enhanced the current density values. The maximum current density obtained was 0.05 A/m2 at concentrations of 150 g/L of chloride. An increase in the concentration of cupric ions favoured the oxidation reaction of Fe (II) to Fe (III). Finally, the concentration of chloride ions present in seawater has been identified as favourable for chalcopyrite leaching.
Luis Beiza; Víctor Quezada; Evelyn Melo; Gonzalo Valenzuela. Electrochemical Behaviour of Chalcopyrite in Chloride Solutions. Metals 2019, 9, 67 .
AMA StyleLuis Beiza, Víctor Quezada, Evelyn Melo, Gonzalo Valenzuela. Electrochemical Behaviour of Chalcopyrite in Chloride Solutions. Metals. 2019; 9 (1):67.
Chicago/Turabian StyleLuis Beiza; Víctor Quezada; Evelyn Melo; Gonzalo Valenzuela. 2019. "Electrochemical Behaviour of Chalcopyrite in Chloride Solutions." Metals 9, no. 1: 67.
This work characterizes raw and decopperized slimes, with the objective of identifying the phases in these two sub-products. The main phases in copper anodes are metallic copper, including CuO, which are present in free form or associated with the presence of copper selenide or tellurides (Cu2(Se,Te)) and several Cu-Pb-Sb-As-Bi oxides. During electrorefining, the impurities in the anode release and are not deposited in the cathode, part of them dissolving and concentrated in the electrolyte, and others form a raw anode slime that contains Au, Ag, Cu, As, Se, Te and PGM, depending on the composition of the anode. There are several recovery processes, most of which involve acid leaching in the first step to dissolve copper, whose product is decopperized anode slime. SEM analysis revealed that the mineralogical species present in the raw anode slime under study were mainly eucarite (CuAgSe), naumannite (Ag2Se), antimony arsenate (SbAsO4), and lead sulfate (PbSO4). In the case of decopperized slime, the particles were mainly composed of SbAsO4 (crystalline appearance), non-stoichiometric silver selenide (Ag(2−x)Se), and chlorargyrite (AgCl).
Evelyn Melo Aguilera; María Cecilia Hernández Vera; Joan Viñals; Teófilo Graber Seguel. Characterization of Raw and Decopperized Anode Slimes from a Chilean Refinery. Metallurgical and Materials Transactions A 2015, 47, 1315 -1324.
AMA StyleEvelyn Melo Aguilera, María Cecilia Hernández Vera, Joan Viñals, Teófilo Graber Seguel. Characterization of Raw and Decopperized Anode Slimes from a Chilean Refinery. Metallurgical and Materials Transactions A. 2015; 47 (2):1315-1324.
Chicago/Turabian StyleEvelyn Melo Aguilera; María Cecilia Hernández Vera; Joan Viñals; Teófilo Graber Seguel. 2015. "Characterization of Raw and Decopperized Anode Slimes from a Chilean Refinery." Metallurgical and Materials Transactions A 47, no. 2: 1315-1324.