Search Results (4)

The reprocessing of metallurgical wastes to recover much-needed metals such as copper not only ensures an adequate supply of metals but also contributes to the cleaning of the environment. A copper smelter in Namibia accumulated significant amounts of spent refractory bricks that are enriched with metal values including copper. This supposedly waste material can potentially serve as a supplement to the ore concentrate, as a smelter feedstock for this toll smelter. Representative samples of crushed bricks, designated as Sample 1 and Sample 2, were used for mineralogical characterisation and flotation test work. The assays for Sample 1 and Sample 2 were 14% Cu and 18% Cu, respectively. Microscopy results identified various copper phases including metallic Cu, bornite, malachite and chalcopyrite. Batch flotation tests were conducted to investigate the effect of grind size (P₈₀ of 53, 75 and 106 μm), pulp pH (natural pulp pH, 10, 10.5 and 11) and collector (potassium amyl xanthate, PAX) dosage (70, 100 and 130 g/t) on the recovery of copper, concentrate grade and weight recovery. In some tests, a co-collector (dithiophosphate, DTP) and sulphidiser (Na₂S) were also added in the quest to maximise the recovery of copper. Based on the test conditions investigated in this study, the grind size is the key variable affecting the recovery of copper. The best copper recovery of 86% (with a weight recovery in the range of 42 to 45% (w/w) and concentrate grade of 37% Cu) was achieved for the finest grind size of 53 μm. The reagent suite that yielded the best recovery was 70 g/t PAX with no addition of the sulphidiser while the pH was 10. There is scope for developing the process routes to recover other valuable metals such as iron, lead and zinc that are also in the spent bricks, as well as potential reuse of the spent bricks (after recovering valuable metals) to make new refractory bricks. Full article

In this study, novel Fe₂O₃/TiO₂ photocatalytic composites were synthesised by combining traditional oxidation roasting with the sol-gel method, using low-cost metallurgical waste (iron scales) as the raw material. The characterisation results revealed that the oxidised iron scales could be transformed into high-purity and porous Fe₂O₃ particles through oxidation roasting, thereby providing additional sites for the adsorption process and thus serving as an effective carrier for TiO₂-based photocatalytic materials. During the sol-gel process, TiO₂ was loaded onto the synthesised Fe₂O₃ particles, generating core-shell heterostructure Fe₂O₃/TiO₂ photocatalytic composites. Under visible light irradiation for 90 min, the Fe₂O₃/TiO₂ photocatalytic composites achieved a remarkable methylene blue removal rate (97.71%). This reaction process followed the quasi-first-order kinetic model with a rate constant of 0.038 min⁻¹. The results have demonstrated that this combination of various components in the Fe₂O₃/TiO₂ photocatalytic composites improved the adsorption, light utilisation, and charge separation effect of the photocatalysts. Moreover, the material exhibited favourable stability and recyclability, making it a decent candidate for the treatment of wastewater from the biochemical industry. Therefore, this study provides a new strategy for improving the photocatalytic activity of TiO₂ and expanding the high value-added utilisation of iron scales. Full article

This study investigates the environmental and occupational health risks associated with arsenic (As) and mercury (Hg) contamination in a specific industrial site: a mercury mine site that contains a metallurgical plant within its premises. Utilising a comprehensive sampling and analysis approach, As and Hg concentrations in the soil and air across various zones within the site were assessed. The results revealed elevated levels of both contaminants, particularly in areas proximal to industrial processes such as metal smelting and waste disposal. Risk assessment using the Cancer Risk (CR) and Hazard Index (HI) indices demonstrated significant health hazards that exceed regulatory thresholds, indicating potential carcinogenic effects from As exposure and risks of non-cancerous occupational diseases. Three distinct risk areas were identified based on the CR and HI indices, guiding the formulation of tailored risk management strategies. While some zones may permit limited industrial activities under specific conditions, others require stringent safety measures and specialised personal protective equipment (PPE) due to exceptionally high contaminant concentrations. Overall, the findings underscore the critical need for robust safety protocols and regulatory compliance to mitigate the health risks associated with As and Hg exposure in industrial settings, ensuring the protection of worker health, environmental stewardship, and the promotion of sustainable mining practices. Full article

This review focusses on the use of recycled and virgin polymers in mineral and metallurgical processing, both high and ambient temperature processes, including novel applications. End of life applications of polymers as well as the utilisation of polymers during its life time in various applications are explored. The discussion includes applications in cleaner coal production, iron and steel production, iron ore palletisation, iron alloy manufacturing, manganese processing, E-wastes processing and carbon sequestration. The underlying principles of these applications are also explained. Advantages and disadvantages of using these polymers in terms of energy and emission reductions, reduction in non-renewables and dematerialisation are discussed. Influence of the polymers on controlling the evolution of micro and nanostructures in alloys and advanced materials is also considered. Full article