Understanding the effect of sulphate in mining-process water on sulphide flotation

Abstract Water quality affects the flotation recovery of minerals and their separation. Mining-process waters become saturated with soluble salts after contact with minerals (oxidation and dissolution) during crushing, classification and flotation. Inorganic species, such as metal ions but also carbonate and sulphate ions, may have a positive or negative effect on mineral flotation. As sulphate ions are always found in high concentrations in process waters, their effects on the flotation of copper, molybdenum and zinc sulphides were investigated in single minerals and ores experiments with complementary mineral surface analysis and particle-bubble detachment studies. It was found that molybdenite flotation was more depressed than chalcopyrite flotation by the presence of sulphate ions in water as a result of increased surface oxidation which decreased particle-bubble attachment. Similar results were obtained in the flotation of two copper ores; however, the grade of chalcopyrite and molybdenite was much lower as a result of increased recovery of unwanted or gangue minerals (e.g., sphalerite, pyrite and quartz)

Sulphate removal from mining-process water by capacitive deionization

Abstract The removal of dissolved sulphate ions in water is one of the main challenges in the industry. Dissolved sulphate ions are ubiquitous in mining influenced waters because of its physical and chemical stability in aqueous solutions, including in process-water used by mineral beneficiation processes. It is a major problem for the mining industry because it can have negative impacts on the mineral beneficiation process and bring other issues for equipment and piping infrastructure. Not to mention the quality requirements for environmental water release. For instance, when water is recycled to the concentrator plant, dissolved sulphates can build up to increased concentration levels that can have negative effects in the processing of minerals. This work proposes a new approach for the removal of sulphate ions from mining influenced waters, including process water, which is the capacitive deionization technique (CADI). The technique can provide good quality water with low sulphate content suitable for recycling to the beneficiation process and meet adequate quality for recycling and safe release to the environment. Synthetic process-water with sulphate concentrations similar to those in mining and mineral process water was prepared and treated by CADI at fixed conditions of electric current and residence time. The original sulphate concentration in water was 1000, 2000, 3000 mg/L; and reduction rates achieved of sulphate concentrations of 275 mg/L, 712 mg/L and 1015 mg/L. respectively. The results show effective removal of sulphate ions

Effect of waste rock dilution on spodumene flotation

Abstract The effect of waste rock minerals introduced by dilution on the flotation of spodumene was investigated. The objectives of this work were to investigate how flotation yield and grades deteriorate mainly by Mg-bearing biotite and amphiboles that are introduced to the system by waste rock dilution and find the possible ways to improve the flotation performance regarding these Mg-bearing minerals. Laboratory flotation tests were conducted with modifications to the standard procedure and new conditions. Analytical methods used in this work include mineralogical tests like electron probe micro-analyzer (EPMA) to find out accurate elemental assays for the minerals in the deposit, especially biotite. X-ray fluorescence (XRF) and atomic absorption spectroscopy (AAS) to analyse flotation products contents. Mineral liberation analysis (MLA) for liberation, associations, Mg-distribution and modal mineralogy. Information about mineral recoveries in different flotation stages was obtained from element to mineral conversion calculations with HSC Chemistry software. The target grade and recovery of Li₂O for the Rapasaari ore were established on 4.5% and 84.18% (as a previous standard test). The use of Na₂CO₃ and starch modifiers gave promising results slightly improving the recoveries to 85.29% and 85.11% respectively while reaching almost 4.5% grade in final concentrate. Mineral liberation analysis (MLA) showed that biotite contains most of the Mg (80–90%), other minerals are amphiboles (mainly edenite and hornblende) and in less extent chlorite and clays. Biotite and amphiboles end up in the final concentrate mostly fully liberated while apatite is mostly coarse mixed grains. Mg-bearing minerals float into the concentrate because of similar surface properties with spodumene. Those similar properties may be due to chemically active Al-O sites that form on the mineral surfaces when the mineral breaks through its cleavage planes during comminution. Al-O sites act as collector attachment spots in fatty acid flotation and compete for collector adsorption

EMJM PROMISE:the new international Erasmus Mundus Joint Master in sustainable mineral and metal processing engineering

Abstract The challenge of attracting young people to the field of mineral processing as well as the ever-growing worldwide demand for minerals and metals together with lower-grade deposits and shortages of energy and water triggered the establishment of the new Erasmus Mundus Joint Master Program PROMISE. The consortium of four mining universities in Europe and Chile aims at master level education on engineering and sustainability issues in mineral processing. The first academic year of PROMISE will start in September 2022