Determination of the extractive behavior of ionic species from lateritic ore leachates is complex, since the leachates are pregnant with tens of different ions in, as a rule, multiple oxide states. To examine the possible pathways of intrinsic electrochemical extraction of the crucial elements Ni and Co, it was necessary to make model solutions of these elements and to subject them to electrochemical examination techniques in order to obtain a benchmark. Beside Ni and Co, the model system for Fe had to be evaluated. Iron, as a dominant ore component by far, is the main interfering factor in the extraction processes of Ni and Co in rather low amounts from leaching solution. The leachate examination results were compared to separate model solutions, as well as to their combinations in concentrations and to pH values comparable to those of the leachate. The separation of the leachate components was initially performed by continuous increase in pH upon leaching with NaOH solution, and afterwards the pH-adjusted solutions were subjected to electrochemical investigation. With the purpose of connecting and quantifying the visual changes in leachate upon increase in pH, conductometric measurements were performed. Reactions of oxidation/precipitations were indicated, which led to the essential Fe removal by precipitation. Resulting solutions were found suitable for Ni and Co electrochemical extraction.

Leaching solutions of complex ore concentrates are reach in different elements, some hindering the extraction of others. Chemically similar elements are difficult to extract using conventional separation methods. Electrochemical techniques are employed for Co and Ni selective extraction out of so-called pregnant leaching solution (PLS). Selective electrodeposition using chronoamperometry (CA) as a tool was used to extract cobalt and /or nickel from the solution. Besides different ions depositing at applied cathodic potential, hydrogen evolution reaction also occurs, which can impede deposition of the desired metals. Previous Linear sweep voltammetry (LSV) analysis of prepared model solutions at different pH values, and upon H2O2 addition, was conducted. The removal of metal ions from the solution, can be performed with adjusting the pH and applied potential (E), so their combination in electrochemical hydro-extraction for Ni and Co is investigated. It has been demonstrated that Fe can be separated from Ni and Co through Fe precipitation in the pH range of 3-6, followed by the electrochemical extraction of Ni/Co.