Extraction of Mn from Black Copper Using Iron Oxides from Tailings and Fe2+ as Reducing Agents in Acid Medium

Abstract

Exotic type deposits include several species of minerals, such as atacamite, chrysocolla, copper pitch, and copper wad. Among these, copper pitch and copper wad have considerable concentrations of manganese. However, their non-crystalline and amorphous structure makes it challenging to recover the elements of interest (like Cu or Mn) by conventional hydrometallurgical methods. For this reason, black copper ores are generally not incorporated into the extraction circuits or left unprocessed, whether in stock, leach pads, or waste. Therefore, to dilute MnO2, the use of reducing agents is essential. In the present research, agitated leaching was performed to dissolve Mn of black copper in an acidic medium, comparing the use of ferrous ions and tailings as reducing agents. Two samples of black copper were studied, of high and low grade of Mn, respectively, the latter with a high content of clays. The effect on the reducing agent/black copper ratio and the concentration of sulfuric acid in the system were evaluated. Better results in removing Mn were achieved using the highest-grade black copper sample when working with ferrous ions at a ratio of Fe2+/black copper of 2/1 and 1 mol/L of sulfuric acid. Besides, the low-grade sample induced a significant consumption of H2SO4 due to the high presence of gangue and clays.

Reducing-Effect of Chloride for the Dissolution of Black Copper

“…Black copper ores are a resource that is generally not incorporated into the extraction circuits or left untreated, whether in stock, leach pads, or waste [6,7]. This is due to the difficulty of recovering elements of interest like Cu or Mn by conventional hydrometallurgical processes since the complex structure is non-crystalline or amorphous [8].…”

“…In recent years, in Chile the treatment of other commodities has been incorporated into the extraction processes, for example, the recovery of Mo together with the Cu in flotation processes has been encouraged [24]. This helps to diversify the business and boost the export of additional products [6]. It is necessary to incorporate the minerals of black copper in the leaching processes, because of their considerable amounts of Mn (29%) which, when dissolved, favor the extraction of Cu, and would allow giving a high commercial value of these "residues".…”

A Stochastic Model Approach for Copper Heap Leaching through Bayesian Networks

“…Copper mining is a constantly growing industry [1], and in countries like Chile, this industry represents 10% of the gross national product (GNP) [2], while approximately 19.7 million tons are produced annually worldwide [3]. Among the copper ores on the planet, the vast majority correspond to sulfured minerals, and a smaller amount to oxidized minerals [4], which is why flotation techniques and smelting processes are used to process these minerals, and to a lesser extent hydrometallurgical techniques [5].…”

Copper Extraction from Black Copper Ores through Modification of the Solution Potential in the Irrigation Solution

“…The Lomas Bayas deposit in northern Chile includes a large area with the presence of exotic copper known as black oxides or black coppers. According to geological and mineralogical studies, 30% of the non-soluble copper in the Lomas Bayas deposit is due to the presence of black copper [6,7]. Previous research by the authors [6] determined the possibility of treating this type of deposit under reducing conditions.…”

“…Hydrometallurgical techniques applied to manganese minerals and marine polymetallic nodules are relevant to the treatment of black copper ore, given the similarities in composition and the resistance to conventional acid leaching [7]. Manganese nodules are mainly composed of two mixed metallic oxides: manganese dioxide and hydrous ferric oxide, and relative quantities of copper, nickel, cobalt, zinc, and molybdenum are also found.…”