Scielo RSS <![CDATA[Journal of the Southern African Institute of Mining and Metallurgy]]> vol. 120 num. 5 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Assessment of the ergonomie design of self-contained self-rescuer (SCSR) devices for use by women in mining</b>]]> Increasing numbers of women are entering the South African mining industry, but self-contained self-rescuer (SCSR) devices might not be suited to female anthropometric dimensions. The aim of this project was to assess the ergonomic design of SCSRs for use by women in the SAMI. Body measurements and questionnaires were collected from 100 female mineworkers from one coal, one platinum, and one gold mine in South Africa. Practical performance assessments of SCSRs when worn on the belt and when donned and in use were conducted with 11 female mineworkers in a simulated underground mining environment. The majority of the participants experienced pain or discomfort when wearing an SCSR and numerous anthropometric dimensions differed from reference values. Dimensional limitations or shortcomings of current SCSRs for use by women in mining were identified, including that the devices were considered to be too heavy and bulky for daily wearing on the belt. The study findings can be used to inform interventions to improve the design and fit of SCSRs. <![CDATA[<b>Removal of arsenic from water using copper slag</b>]]> The potential use of copper slag (CS) as an adsorbent for removing arsenic contaminant from water was examined. The influence of solution pH, initial arsenate (As(V)) and arsenite (As(III)) concentrations, and adsorbent dosage was investigated by batch experiments to elucidate the adsorption mechanism of arsenate onto CS. The adsorption kinetics indicated that the second-order kinetic model best described the adsorption process. The adsorption data was analysed by the isotherm models, and was well fitted by the Langmuir model. The maximum removal of As(V) and As(III) achieved was 98.76% and 88.09%, respectively at an adsorbent dose of 10 g/L with an initial As(V) and As(III) concentration of 300μug/L This study showed that copper slag is a suitable adsorbent for removal of arsenic from water, with a capacity to reduce arsenic levels to < 10 μg/L, below the limit set for water by World Health Organization. <![CDATA[<b>Preliminary investigation into the extraction of light rare earth elements from different resources using the sulphation roasting process</b>]]> Rare earth elements (REEs) are commonly extracted from various resources using hydrometallurgical processes. However, these processes tend to be unselective, with high co-extraction of gangue components. Co-extraction of gangue elements is undesirable as it complicates downstream separation and purification processes. Preliminary tests were conducted on synthetic cerium oxide (chemical grade CeO2) to investigate the technical feasibility of the sulphation roasting process for the extraction of REEs from different resources. Sulphation roasting was also applied to a REE-bearing ore under selected conditions. The highest REE extraction efficiency of 89% from synthetic CeO2 was achieved under sulphation roasting conditions of 700°C over 24 hours in a gas atmosphere made up of 32% SO2 and 16% O2 (2:1, SO2:O2 ratio). The extraction efficiencies from the REE-bearing ore were 47% Ce, 46% La, and 67% Nd, 4% Fe, and 10% Mn after sulphation roasting at 750°C for 24 hours. These preliminary results indicate that it may be feasible to produce REEs from different resources using the established selective sulphation roasting process. <![CDATA[<b>In-truck ore grade estimation using apparent density measurements</b>]]> The Rio Tinto Iron and Titanium (RTIT) Havre St-Pierre (HSP) mine located in Quebec, Canada has implemented a grade estimation system based on the determination of the apparent density of the material loaded into mine trucks. The system is used to segregate economic ore from waste as part of the re-handling of a historical waste stockpile. The system takes advantage of the strong relationship established between ore density and grade for the HSP mineralization. The apparent density is derived from the measurements of (i) the volume of the truck load using a laser-based scanner and (ii) the mass of the truck load provided by an onboard truck scale. The ore grade is then calculated by applying a void factor to the apparent density measurement. In the future, this in-truck grade estimation technology could be expanded to the entire mine operations and be instrumental in ore vs waste discrimination and production reconciliation. <![CDATA[<b>An investigation into the wear mechanisms of carbon- and silicon carbide-based refractory materials by silicomanganese alloy</b>]]> Two carbon-based refractories were studied to elucidate the main wear mechanisms when in contact with SiMn alloy. The aim was to determine which refractory would be most suitable for application in the hearth area of a SiMn producing furnace. Thermodynamic calculations were conducted in FactSage™ 7.2 at temperatures of 1550°C, 1600°C, and 1650°C, with alloys containing 15, 17, and 18 mass % Si, in contact with type K or type SiC refractories. The calculations revealed that the SiMn alloy was not saturated in either C or SiC. In line with FactSage™ calculations, type SiC refractory (15 mass % Si) experienced the most wear when the temperature was varied. SEM analysis revealed that SiMn infiltrated both refractories, with type SiC experiencing more infiltration due to its porous nature. Type K refractory underwent the most wear when the temperature was 1600°C and the Si content varied from 15 to 18 mass %. Carbon solubility in the alloy decreased with increasing Si content, and the alloy was saturated with SiC at 17 mass % Si. SEM analysis revealed SiC precipitation products on the type K refractory surfaces. Similar to observations on temperature tests, higher infiltration was observed in type SiC refractory than in type K refractory. Type K refractory was assessed as the most suitable refractory to use in the hearth area of a SiMn producing furnace. In industry, carbon-based refractories generally last 1.2 times longer than SiC-based refractories in the tap-hole. <![CDATA[<b>Thiol collector blends for improved PGM recovery: a case study of a UG2 ore</b>]]> Different thiol collectors are widely used to improve the flotation performance of PGM-containing ore. They are used either as a single collector or as a collector blend. The performance of sodium n-propyl xanthate (SNPX), dithiocarbamate (DTC), and O-isopropyl-N-ethyl thionocarbamate (IPETC) collectors was evaluated in order to improve the recovery of PGMs from UG2 ore. SNPX was used as single collector, followed by SNPX blends with DTC and IPETC. The best blend improved the 3PGM + Au recovery from 81% to 86% without compromising the grade. As thiols remain the most widely used collectors in the recovery of PGMs from sulphide ores, particularly with leaner and more complex occurrences, there is room for continued research on the most effective blends. <![CDATA[<b>Purification of crude titanium powder produced by metallothermic reduction by acid leaching</b>]]> The CSIR is developing a process to produce commercially pure (CP) Grade 4 titanium metal powder via direct metallothermic reduction of TiCl4. Crude titanium produced by this method is inevitably contaminated with unreacted reducing metal and titanium subchlorides occluded in halide salt. For the product to meet stringent titanium industry quality requirements, the concentration of impurities must be held to acceptably low levels. Acid leaching was identified as a suitable method for purifying the crude reduction mass, due to the solubility of the by-products and the potential for cost-saving provided by this method compared to vacuum distillation. However, purification by leaching poses drawbacks such as high oxygen impurity concentrations in the product, due to the dissolution of subchlorides in water to form insoluble hydroxides and oxychlorides that concentrate on the surface of the titanium powder. The crude titanium was leached under different conditions using water and 1 M and 0.035 M hydrochloric acid at a temperature below 50°C. The 1 M acid leach yielded a product with the lowest oxygen content, demonstrating that when the pH of the media and temperature are controlled, the drawbacks associated with acid leaching can be overcome and the process used successfully for downstream purification of the crude product.