Efficacy of Mesh Size Variation on the Efficiency of Anka-Nassarawa (Zamfara State, Nigeria) Copper Ore Flotation

This research investigated the influence of mesh size variation on the efficiency of froth flotation on Anka-Nassarawa copper ore, sourced from Zamfara State, Nigeria. Physical and chemical characterization was carried out, followed by sieve size analysis of the ore, leading to its crushing and grinding to liberation size and processing using froth flotation at sieves 250, 180, 125, 90 and 63 μm. Reagents used were pine oil as a frother, potassium ethyl xanthate as a collector, zinc sulphate – depressant, copper sulphate – activator and pH regulator was sodium hydroxide. Physical characterization showed that the ore has a metallic luster, dark bronze color with greenish stripes, and irregular breakages. Compositional analysis of the crude ore using X-ray fluorescence (XRF) revealed that the ore contains 12.271% CuO, 30.042% Fe₂O₃, 11.475% SiO₂, 32.128% Nb₂O₅, and 3.426% SO₂, along with trace amounts of other minerals, including NiO, WO₃, CaO, and ZrO₂. The liberation size of the ore was determined to be 125 μm, and the Bond work index was found to be 18.81 kWh/tonne and the energy used in comminution was 557.536 kWh. After froth flotation, the resulting froth and depressed samples were dewatered and analyzed using XRF. The highest copper grade of 43.82% CuO was obtained at a mesh size of 63 μm, confirming that this size is optimal for maximizing copper recovery from Anka-Nassarawa ore using froth flotation. The study demonstrates that the most efficient flotation results are achieved by grinding the ore to a 63 size lower than the determined liberation size.