بررسي بازيابي نيكل و منيزيم از محلول‌‌هاي رقيق ليچينگ كانسنگ‌‌هاي اولترامافيكي كم عيار به روش ترسيب شيميايي

The depletion of high-grade reserves, coupled with the strategic importance of Nickel, Cobalt, an‎d Magnesium has necessitated the processing of low-grade lateritic ores. The primary challenge in the beneficiation of these resources is the presence of interfering impurities such as iron, aluminum, chromium an‎d manganese alongside the valuable metals, which complicates their separation. This research aimed to recover nickel an‎d cobalt from dilute sulfate leach solutions derived from low-grade ultramafic (polymetallic) ores an‎d to achieve economic utilization of associated elements (manganese an‎d magnesium) using chemical precipitation methods. The methodology of this study was based on a hybrid strategy involving stepwise precipitation processes for impurity removal an‎d recovery of valuable elements. Initially, iron was removed via the jarosite precipitation method under optimized conditions (temperature: 90-95°C, pH: 2.2-1.8, time: 4 hours), resulting in over 94% iron reduction in all samples. In the next step, considering the high concentration of manganese in some samples, this element was precipitated as an oxide at ambient temperature an‎d pH 2. While achieving 84.6% manganese recovery, this step posed the challenge of significant co-precipitation of nickel (13.2%) an‎d cobalt (30.7%). Subsequently, aluminum an‎d chromium impurities were removed through the alunite precipitation process at elevated temperatures (95-100°C) an‎d a pH range of 4.1-3.8, achieving nearly 100% removal efficiency for chromium an‎d over 84% for aluminum. In the main stage, nickel an‎d cobalt were recovered from the purified solution via hydroxide precipitation in the pH range of 7.5-7 an‎d temperature of 55-60°C. The results indicated highly favorable metallurgical recoveries of up to 96.1% for nickel an‎d 100% for cobalt. Finally, due to the high concentration of magnesium an‎d its economic viability, this element was precipitated from two samples using the hydroxide method at a pH of 10-9.5 an‎d temperature of 70-75°C. The resulting product underwent alkaline desulfurization followed by calcination to be converted into high-purity magnesium oxide. Based on XRF analysis of the final magnesium oxide product, the purity of this material reached 90.25% for MgO, demonstrating the satisfactory efficiency of the desulfurization an‎d calcination processes in impurity removal. The findings of this research indicate that although chemical precipitation methods are not as precise as solvent extraction processes for the separation of nickel an‎d cobalt, they are highly significant as an efficient pre-concentration an‎d purification stage for polymetallic deposits (containing nickel, manganese, an‎d magnesium) prior to solvent extraction circuits. This is attributed to their lower operating costs, simplicity of operation, an‎d high reliability. The implementation of these processes not only reduces the costs an‎d complexity of subsequent stages but also enables the recovery of associated elements an‎d their conversion into high value-added products (such as magnesium oxide).

علي احمدي عامله , محمدرئوف حسيني

مهدي نصيري سروي , حميد زيلوئي