Separation of cobalt and nickel using solvent extraction technique from aqueous solutions

The compounds and alloys of cobalt and nickel have widely and important range of applications in a number of industrial and technological fields. Because cobalt and nickel is often found together, these metals have similar physical and chemical properties and making them very hard to be purified, separation of cobalt and nickel have been formed the drawback of many research.Moreover, The supply-demand gap for nickel and other valuable ores have been increasing with limited supply and increasing demand. On this situation, one of the practical solutions to the problem would be recycling of solid and liquid waste containing trace amounts of precious metals, which lately has drawn very much attention. In generallly, the solvent extraction techniques are separation and enrichment process to selectively separation of desired metals from aqueous solution containing various metals or to enrich the metals which has trace level in the samples. So many studies have been performed in the scientific literature related in separation, recovery and enrichment of cobalt and nickel. Many of these studies have been used in industrial scale applications.The seletive separation of cobalt and nickel was examined in these studies. Trioctylamine (TOA) and 8-hydroxyquinoline (8-HQ) were used as an extractant and optimum conditions was determined with testing main parameters effected to the extraction efficiency such as the solvent type, the pH of the feed phase, the concentration of extractant, the mixing speed, the phase ratio (V0/Va), the concentration of complexing agent and the extraction time etc. Under the optimum conditions, the cobalt and nickel extraction from the Co/Ni solutions in various initial concentrations was examined. The optimum extraction conditions were applied to the acidic leach solutions obtained from solid wastes of ÇİNKUR plant. Thus, industrial application of the extraction systems were tested. Cobalt and nickel ions were transferred to the organic phase and were stripped and enriched using suitable aqueous solutions. The stochiometry of interfacial reactions was explained using Job and log-log plot analysis methods. During the extraction process, molecular structure of the compounds formed in interface between the aqueous and the ogranic phases were lightened with NMR and ATR-FTIR spectroscopie techiques.