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Lilian Velásquez-Yévenes
Escuela de Ingeniería Civil de Minas, Facultad de Ingeniería, Universidad de Talca, Curicó 3340000, Chile

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Journal article
Published: 12 August 2021 in Materials
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The dissolution of both copper and arsenic from a copper concentrate was investigated in oxidative ammonia/ammonium solutions at moderate temperatures and atmospheric pressure. The main parameters studied were temperature, pH, concentrations of different ammonia salts, the presence of sodium hypochlorite, pretreatment with sodium chloride, and curing period. In all ammoniacal solutions studied, increasing the temperature enhanced the dissolution of copper, but the dissolution of arsenic remained marginal. Mixing the copper concentrate with sodium chloride and leaving it to rest for 72 h before leaching in ammoniacal solutions significantly increased the dissolution of copper and slightly increased the dissolution of arsenic from the concentrate. A maximum of 35% of Cu and 3.3% of As were extracted when ammonium carbonate was used as the lixiviant. The results show relatively rapid dissolution of the concentrate with the addition of sodium hypochlorite in ammonium carbonate solution, achieving a dissolution of up to 50% and 25% of copper and arsenic, respectively. A copper dissolution with a non-linear regression model was proposed, considering the effect of NaClO and NH4Cl at 25 °C. These findings highlight the importance of using the correct anionic ligands for the ammonium ions and temperature to obtain a high dissolution of copper or arsenic. The results also showed that the curing time of the packed bed before the commencement of leaching appeared to be an important parameter to enhance the dissolution of copper and leave the arsenic in the residues.

ACS Style

Lilian Velásquez-Yévenes; Hans Álvarez; Víctor Quezada; Antonio García. The Enhancement of Enargite Dissolution by Sodium Hypochlorite in Ammoniacal Solutions. Materials 2021, 14, 4529 .

AMA Style

Lilian Velásquez-Yévenes, Hans Álvarez, Víctor Quezada, Antonio García. The Enhancement of Enargite Dissolution by Sodium Hypochlorite in Ammoniacal Solutions. Materials. 2021; 14 (16):4529.

Chicago/Turabian Style

Lilian Velásquez-Yévenes; Hans Álvarez; Víctor Quezada; Antonio García. 2021. "The Enhancement of Enargite Dissolution by Sodium Hypochlorite in Ammoniacal Solutions." Materials 14, no. 16: 4529.

Review
Published: 02 July 2021 in Metals
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Although the main cause of hydrometallurgical plant closures is the depletion of oxidized copper minerals reserves, the lack of new hydrometallurgy projects also contributes to these closures. One solution is to be able to process copper sulphide ores hydrometallurgically. However, it is widely known that sulphide copper ores—and chalcopyrite in particular—have very slow dissolution kinetics in traditional leaching systems. An alternative to improve the extraction of copper from sulphide ores is the use of a pretreatment process. Several investigations were developed evaluating the effects of pretreatment, mainly in the extraction of copper from chalcopyrite in chloride media. This study presents a review of various pretreatment methods prior to heap leaching to aid in the dissolution of copper from sulphide ores. Different variables of pretreatment that affect the extraction of copper were identified, including the type of salts used in agglomeration, curing time, and curing temperatures. Successful cases such as the implementation of the CuproChlor® process (use of calcium chloride), and various pilot studies using sodium chloride and temperature, show that pretreatment is an alternative that aids in the dissolution of copper from sulphide ores.

ACS Style

Andrés Neira; Diana Pizarro; Víctor Quezada; Lilian Velásquez-Yévenes. Pretreatment of Copper Sulphide Ores Prior to Heap Leaching: A Review. Metals 2021, 11, 1067 .

AMA Style

Andrés Neira, Diana Pizarro, Víctor Quezada, Lilian Velásquez-Yévenes. Pretreatment of Copper Sulphide Ores Prior to Heap Leaching: A Review. Metals. 2021; 11 (7):1067.

Chicago/Turabian Style

Andrés Neira; Diana Pizarro; Víctor Quezada; Lilian Velásquez-Yévenes. 2021. "Pretreatment of Copper Sulphide Ores Prior to Heap Leaching: A Review." Metals 11, no. 7: 1067.

Short communication
Published: 20 November 2020 in Hydrometallurgy
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Chile is host to one of the most considerable Cu resources in the world. The primary source of Cu is from porphyry deposits. However, associated “exotic-Cu” deposits are also significant in the Atacama Desert of northern Chile. The critical processing issue for these ores is that they are refractory to dissolution under acidic and oxidative conditions, and consequently their dissolution kinetics are relatively slow. This paper reports a study on the extraction of copper and manganese from exotic-Cu ores using cane molasses as a reducing agent in the presence of chloride ions and diluted sulfuric acid media. The effects of concentrations of cane molasses, chloride ion, and sulfuric acid are discussed. Leaching tests on ground ore in shake flasks were studied, as well as the agglomeration and curing stages of a coarse ore sample. The dissolution of the exotic copper ore is enhanced when 50 g/L of NaCl and 60 g/L of cane molasses are added to the leaching solution. The dissolution of copper associated with copper wad appears independent of the Mn dissolution. Tests with the ore agglomerated with acid, chloride ions, and cane molasses showed enhanced dissolution of manganese contained in the copper wad, but not copper. It is thus confirmed that cane molasses is a suitable reductant in the leaching of Mn, especially in the presence of chloride ions. The behavior and fate of the wad-associated copper requires further investigation.

ACS Style

L. Velásquez-Yévenes; Ricardo Lasnibat. Simultaneous recovery of copper and manganese from exotic copper ore in acid chloride media using cane molasses as the reducing agent. Hydrometallurgy 2020, 199, 105531 .

AMA Style

L. Velásquez-Yévenes, Ricardo Lasnibat. Simultaneous recovery of copper and manganese from exotic copper ore in acid chloride media using cane molasses as the reducing agent. Hydrometallurgy. 2020; 199 ():105531.

Chicago/Turabian Style

L. Velásquez-Yévenes; Ricardo Lasnibat. 2020. "Simultaneous recovery of copper and manganese from exotic copper ore in acid chloride media using cane molasses as the reducing agent." Hydrometallurgy 199, no. : 105531.

Journal article
Published: 17 April 2020 in Metals
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An alternative copper concentrate leaching process using sodium nitrate and sulfuric acid diluted in seawater followed by gas scrubbing to recover the sodium nitrate has been evaluated. The work involved leaching test carried out under various condition by varying temperature, leaching time, particle size, and concentrations of NaNO3 and H2SO4. The amount of copper extracted from the chalcopyrite concentrate leached with seawater, 0.5 M of H2SO4 and 0.5 M of NaNO3 increased from 78% at room temperature to 91% at 45 °C in 96 h and 46 h of leaching, respectively. Gas scrubbing with the alkaline solution of NaOH was explored to recover part of the sodium nitrate. The dissolved salts were recovered by evaporation as sodium nitrate and sodium nitrite crystals.

ACS Style

César I. Castellón; Pía C. Hernández; Lilian Velásquez-Yévenes; María E. Taboada. An Alternative Process for Leaching Chalcopyrite Concentrate in Nitrate-Acid-Seawater Media with Oxidant Recovery. Metals 2020, 10, 518 .

AMA Style

César I. Castellón, Pía C. Hernández, Lilian Velásquez-Yévenes, María E. Taboada. An Alternative Process for Leaching Chalcopyrite Concentrate in Nitrate-Acid-Seawater Media with Oxidant Recovery. Metals. 2020; 10 (4):518.

Chicago/Turabian Style

César I. Castellón; Pía C. Hernández; Lilian Velásquez-Yévenes; María E. Taboada. 2020. "An Alternative Process for Leaching Chalcopyrite Concentrate in Nitrate-Acid-Seawater Media with Oxidant Recovery." Metals 10, no. 4: 518.