Sulfur dioxide as a thiourea stabilizer in the Carbon-in-Leach (CIL) process using a hydrodynamic cavitation-reactor for gold recovery from dump tailings

Abstract

This research improves the gold recovery from dump tailings employing the Carbon in Leach (CIL) process and using thiourea as a gold lixiviant. The integration of sulfur dioxide in the CIL process, utilizing a Hydrodynamic Cavitation (HC) reactor, was explored to mitigate the pronounced consumption of thiourea. The HC reactor was found to catalyze the generation of OH^• radicals via hydrodynamic cavitation, acting as a robust oxidizing agent. A comprehensive examination revealed the impact of the inlet pressure of pulp in the HC reactor, temperature, and iron(III) sulfate concentration on the oxidoreduction potential (ORP) within the CIL process with supplied SO₂. We have found that under specific parameters -including the initial concentration of H₂SO₄, thiourea loading, coal loading, SO₂ supply, inlet pressure of pulp supply to the HC reactor, and the CIL processing time - a substantial degree of gold recovery is achievable. Particularly, with a thiourea consumption of 0.57 kg/t and sulfur dioxide at 8 kg/t, gold recovery peaked at 93.5%.