Magnetic modification of pyrite via galvanically enhanced Ni-Co cementation for separation from mine tailings

This study presents a novel method for separating pyrite (FeS₂) from mine tailings using magnetic separation. Our approach employs a galvanically enhanced nickel (Ni)/cobalt (Co) cementation process with aluminum (Al) to form Ni and Co depositions on the FeS₂ surface. This process is driven by inherent electrochemical reactions between Al and FeS₂ in Ni and Co solutions, resulting in enhanced magnetic response. Experimental results confirmed the successful deposition of Co and Ni, significantly enhancing the magnetic susceptibility of FeS₂. The extent of deposition was influenced by solution parameters, such as pH, temperature, and metal ions concentration. Under optimal conditions - reaction time of 4 h, 0.2 mol/L of either Ni or Co, 5:5 wt ratio of Al to FeS₂, pH 2, and temperature of 40 °C - FeS₂ recovery efficiency reached 78.60 wt% with Ni cementation and 100 wt% recovery with Co cementation. To improve Ni cementation efficiency, adjustments to conditions, such as increasing particle size, introducing N₂ gas, elevating temperature, and increasing Ni concentration, were implemented. Ultimately, by raising the Ni concentration to 0.5 mol/L and the temperature to 50 °C, a full recovery efficiency of 100 wt% was achieved.