Leaching Kinetics of Cu from Low-Grade Oxidized Copper Ore with High Alkalinity Gangue Using Edta·2na Solution

Low-grade oxidized copper ore with a high alkaline gangue content is considered refractory due to its high CaO and MgO content, which leads to significant sulfuric acid consumption during leaching and environmental pollution from the ammonia leaching process. In this study, an aqueous solution of ethylenediaminetetraacetic acid disodium salt (EDTA·2Na) was utilized as a leaching agent to explore the influence of key process variables, such as leaching temperature, EDTA·2Na concentration, leaching duration, stirring rate, and liquid-to-solid volume mass ratio, on the copper leaching rate over various durations. The kinetic analysis shows that the Cu leaching process of this ore with EDTA·2Na solution is mixed, controlled by both interfacial chemical reaction and solid product layer diffusion. The apparent activation energy EA = 11.32 kJ/mol, and the apparent reaction order, α, for EDTA·2Na concentration is 1.151, the apparent reaction order, β, for stirring rate is 0.245, and the apparent reaction order, θ, for the liquid–solid ratio is 0.021. The kinetic equation is \(\frac{1}{3}\ln \left( {1 - x} \right) + \left( {1 - x} \right)^{{ - \frac{1}{3}}} - 1 = k_{0} \cdot m^{1.151} \cdot r^{0.245} \cdot R^{0.021} \cdot e^{{ - \frac{11.32}{{RT}}}} \cdot t\) $\frac{1}{3}ln\left(1-x\right)+{\left(1-x\right)}^{-\frac{1}{3}}-1=k_0·m^{1.151}·r^{0.245}·R^{0.021}·e^{-\frac{11.32}{\mathit{RT}}}·t$ .