The Role of Solar Energy (UV-VIS-NIR) as an Assistant for Sulfide Minerals Leaching and Its Potential Application for Metal Extraction

Abstract

The mining industry is facing emerging challenges as a result of the increase in energy consumption and environmental demands. These facts have promoted the use of renewable energy sources, such as wind, geothermal and, mainly, solar energy. This paper discusses the role of solar energy (UV-VIS-NIR) in leaching processes, evaluating its potential application in metal extraction from sulfide minerals, based on photochemical mechanisms that promote the regeneration of ferric iron or the so called ferrous iron cycling. The present paper discusses the possibility that ultraviolet, visible light and near infrared irradiation (e.g., sunlight provided) can assist the leaching processes in two main ways: by the oxidation of sulfide minerals through in-situ generated Fenton-like reactions, and by the photochemical activation of semiconductor minerals that contain transition metals (Fe, Cu, and Cr, among others). Thus, this paper provides theoretical support to move towards the future application of photoleaching, which consist of a leaching process assisted by UV, VIS, and NIR irradiation. This technology can be considered a promising mineral processing route, using direct photochemical solar energy that can reduce the energy consumption (electricity, fuels) and the environmental impact, opening an opportunity for an alternative method of metal extraction from sulfide ores.

Perspectives for Photochemical Leaching Processes of Chalcopyrite: A Solar Radical-Leaching Process

“…EMSURE ® ISO) was provided by Merck, New Jersey, USA. S2O8 2− It is also important to mention that coincidentally, in specific regions of the copper industry (Chile, Perú, and Australia), the average irradiance level exceeds the established threshold of 2000 kWh m −2 per year [7]. This condition indicates that these regions may be optimal for solar energy production, enabling us to reduce our reliance on non-renewable energy sources.…”

“…From an economic perspective, the reported capital cost of a hydrometallurgy plant with a capacity ranging from 40,000 to 200,000 metric tons per year is between USD 400 and USD 5000 per ton of copper cathode [5]. It is also important to mention that coincidentally, in specific regions of the copper industry (Chile, Perú, and Australia), the average irradiance level exceeds the established threshold of 2000 kWh m −2 per year [7]. This condition indicates that these regions may be optimal for solar energy production, enabling us to reduce our reliance on non-renewable energy sources.…”