Reducing-Effect of Chloride for the Dissolution of Black Copper

Abstract

Oxidized black copper ores are known for their difficulty in dissolving their components of interest through conventional methods. This is due to its non-crystalline and amorphous structure. Among these minerals, copper pitch and copper wad are of great interest because of their considerable concentrations of copper and manganese. Currently, these minerals are not incorporated into the extraction circuits or left untreated, whether in stock, leach pads, or waste. For the recovery of its main elements of interest (Cu and Mn), it is necessary to use reducing agents that dissolve the present MnO2, while allowing the recovery of Cu. In this research, the results for the dissolution of Mn and Cu from a black copper mineral are exposed, evaluating the reducing effect of NaCl for MnO2 through pre-treatment of agglomerate and curing, and subsequently leaching in standard condition with the use of a reducing agent (Fe2+). High concentrations of chloride in the agglomerate process and prolonged curing times would favor the reduction of MnO2, increasing the dissolution of Mn, while the addition of NaCl did not benefit Cu extractions. Under standard conditions, low Mn extractions were obtained, while in an acid-reducing medium, a significant dissolution of MnO2 was achieved, which supports the removal of Cu.

Treatment of black copper with the use of iron scrap - part I

“…In the investigations carried out by Benavente et al, [18] and Pérez et al, [16] it was discovered that working in an acid-reducing leaching favors dissolution of MnO2, thus favoring the extraction of copper. Subsequently, Torres et al, [17] demonstrated that it is possible to considerably increase concentrations of Cu and Mn in solutions obtained from black copper in short periods of time (20 min) when working in stirred reactors and carrying out pre-treatment processes (agglomeration and curing) by adding a reducing agent (NaCl in that study). Furthermore, it should be noted that various studies have been carried out with the aim of MnO2 dissolution from manganese nodules [20][21][22][23][24][25][26][27][28], which provided multiple alternatives for extraction of Mn and Cu from black copper, as they have are similarly processed in leaching systems.…”

“…Black copper minerals are abundant in Chile, being present in large deposits such as: Mina sur Chuquicamata, Damiana in El Salvador, Lomas Bayas Spence, and El Tesoro and Huanquintipa in Collahuasi [16]. Even though these minerals contain considerable amounts of Cu and Mn [17], they are not commonly incorporated in the leach pads, being considered waste [18]. This is due to its amorphous, which prevents treating these mineral resources by means of conventional hydrometallurgical processes [16].…”

“…There are few studies that investigated leaching of black copper minerals [16][17][18][19]. In the investigations carried out by Benavente et al, [18] and Pérez et al, [16] it was discovered that working in an acid-reducing leaching favors dissolution of MnO2, thus favoring the extraction of copper.…”

“…For dissolution of Mn from black copper with the use of sulfuric acid, chloride and Fe 2+ , the following reactions are proposed [17]:…”

Global sensitivity analyses of a neural networks model for a flotation circuit

“…Within copper extractive processes, flotation is the most widely used worldwide, producing 80 % of the production of this commodity [3][4][5][6][7]. Flotation processes are a recurring alternative in the treatment of copper sulfide minerals, since the selective separation of minerals is achieved, based on their hydrophobic and hydrophilic properties [8][9][10].…”