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Solvent extraction of antimony and tin from speiss leachateSundell, Oscar January 2017 (has links)
This work is a cooperation with Boliden Minerals AB, who recently has been interested in recovering more valuable elements from their byproducts. For this case, solvent extraction was chosen as a potential method of recovering these valuables, as it is a method considered to be ideal for separation of trace elements from large amounts of other substances. The goal for this work was to execute manual extraction experiments as a preparation for a bigger project at LTU. The objectives of this thesis included the investigation of the selectivity for extraction of tin and antimony, using different concentrations of hydrochloric acid in the feed solution, analysis of the equilibrium isotherms for Sn and Sb at 8M of HCl as well as the evaluation of the number of steps needed for future extraction experiments, using the McCabe- Thiele method. By executing manual experiments with a speiss precipitate dissolved in hydrochloric acid, the results obtained indicated that the selectivity increased with a higher content of HCl in the feed solution. Using different ratios between the aqueous and organic phase, the equilibrium curves denoted a pushback effect, causing antimony to migrate back into the aqueous phase at the saturation level of tin. By constructing a McCable-Thiele diagram according to the equilibrium curves, the number of steps could be evaluated to three.
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Slag Cleaning of a Reduced Iron Silicate Slag by Settling : Influence of Process Parameters and Slag Modification on Copper ContentIsaksson, Jenny January 2021 (has links)
During the pyrometallurgical extraction of copper, a significant part of the copper is lost with discard slag, which decreases profits, overall copper recovery, and efficiency of raw material usage. Smelting furnace slag usually has a copper content that is close to or higher than that of copper ores. The investigation of copper losses to slag is thus a task of practical significance, as the ore grades are depleting. Slag cleaning, e.g., a settling furnace, can reduce copper losses to slag as the mechanically suspended copper-containing droplets separate from slag under the action of gravity and can hence be recovered. An industrial trial was conducted in an electric settling furnace with slag originating from an electric smelting furnace and processed in a zinc fuming furnace. The trial was conducted to increase the understanding of copper losses to slag and how the process parameters temperature and settling time influence the slag copper content. The obtained slag samples were also evaluated to gain better insights as to the settling mechanism and, if any, factors that hinder the copper phases from settling. Slag modification with CaO was also evaluated to investigate how the modification influences the settling of copper phases and, thus, the final slag copper content. Samples collected during the industrial trial were the basis for the evaluation in the current work. The samples came from batches with varying temperatures, settling times, and CaO content collected at four different sample positions. Instrumental techniques, including XRF, FAAS, ICP-SFMS, and SEM-EDS, were used to analyze the chemical compositions of the samples and the appearance of copper and associated phases. The results indicated that the copper content of outgoing slag increased with increasing temperature in the evaluated interval. The copper content was also concluded to be more strongly affected by the temperature compared to the settling time. Regulating the temperature to the lower temperature interval in the settling furnace could thus decrease the final slag copper content. During the slag characterization, it was found that suspended copper-containing phases were hindered from settling, due to the attachment to solid phases and gas bubbles in the slag. By controlling and minimizing the presence of the bottom buildup and thus solid phases in the slag, the copper content can be decreased. The results indicated that the CaO slag modification decreased the final slag copper content, and can thus be used as a modifier for increased settling.
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