Separation of Re and Mo from roasting-dust leach-liquor using solvent extraction technique by TBP

Re/Mo separation is studied by a new solvent extraction technique which is based on extraction mechanisms of the constituent metals. Based on McCabe–Thiele plots, a flow diagram has been proposed for separation and purification of Re over Mo. Re-recovery section of the diagram shows that Re is extracted when major amount of Mo is removed. For removal of the remained Mo, a two-stage extraction is required at pH = 2 and Va/Vo = 1. In order to obtain Re, the resulted aqueous phase is stripped by adding sulfuric acid. According to the results, while more Re is extracted at less pH, optimum extraction of Mo happens at pH = 1.2. Re selectivity over Mo maximizes by approaching of the pH to zero.

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► The extraction of Re occurs at lower pH with higher extraction percentage.
► The extraction of Mo increases by pH attaining a 96% peak at pH 1.2.
► The best pH range for selectivity Mo over Re is 1.8–2.
► Semi-countercurrent experimental results indicate seven steps for extraction and stripping.