Leaching solution can contain significant amounts of impurities such as iron ions, aluminum and copper ions. Purification of the leaching solution by the precipitation of impurities using an alkaline reaction often results in the loss of nickel in addition to the removal of impurities. this research a study of chemical precipitation processes with carbonate precipitating agents by which iron, aluminum, and copper precipitate from kinetic nickel leaching liquors with minimal nickel losses as a valuable soluble metal. Many attempts have been made to study empirically the relationship between the removal of impurities and the losses of nickel from nickel leaching solution, most of which limestone has been used. A four-component kinetic leaching solution containing + Fe (III) + Ni (II) Al (III) + Cu (II) was prepared. Carbonate precipitating agents of calcium carbonate, magnesium carbonate and dolomite along with sodium alkaline agent were used to remove impurities with minimal nickel loss. Also, in one part of this study, in addition to calcium carbonate and magnesium carbonate, the two factors of alkaline hydroxide, sodium hydroxide and magnesium hydroxide were used simultaneously and the removal of impure elements was investigated. In each of the selective precipitation tests, different concentrations of carbonate composition, pH, temperature and aging time were eva‎luated. The effect of governing factors on the selected precipitation process as well as the interaction of these factors with statistical analysis and modeling were investigated. pH, type of carbonate and concentration of carbonate agent were identified as important and influential factors on the removal efficiency of impure elements and the amount of nickel loss. Quadratic models using experimental data made it possible to create three-dimensional response levels. These diagrams clearly show the relationship between responses and factor interactions. Increasing the pH of the solution and the concentration of carbonate removes iron, aluminum and copper, but is associated with higher nickel losses. The mechanisms of element removal and nickel loss are mainly either co-precipitation or adsorption on unstable precipitates of other elements. Some elements, such as magnesium, can play an inhibitory role in reducing nickel losses. Temperature and time can be effective in removing most impure elements at low pHs because temperature reduces the solubility of impure precipitates and time leads to the stability of unstable precipitates of impure elements but at higher pHs increases nickel loss. By precisely controlling the pH and concentration of each carbonate agent using the precipitation process, iron, aluminum, and copper can be effectively removed with minimal nickel loss. For better removal of elements with the least nickel loss, MgCO3>Ca(OH)2>MgCa(CO3)2>CaCO3 were effective. Using the carbonate precipitation method, more than 99% of all three elements, iron, aluminum and copper, can be finally removed. The level of nickel to solid loss under optimal conditions was very high for calcium carbonate but for magnesium carbonate, calcium hydrate and dolomite were 3.57%, 3.5% and 5.64%, respectively.

مهدي علي زاده

سعيده غزالي

مريم كرباسي، علي سعيدي