Flotation Flowsheet and Mode for Recovery of Gold from Refractory Ores
Problem Statement. When enriching refractory gold-bearing ores, a decrease in the yield of the concentrate sent to the gold extraction and subsequent cyanidation significantly reduces capital expenses and operating costs, providing a solution to the urgent problem of increasing the production efficiency of commercial products. Objectives. To increase the technical and economic indicators of ore processing by reducing the yield of the concentrate sent to the biooxidation of sulfides by aerating the pulp with a mixture of air and hot water steam, namely flotation with steam-air bubbles. Originality. Based on the data on the dependence of the forces of hydrophilic repulsion and hydrophobic attraction caused by the difference in the structure of water in the boundary layers of minerals from the structure of water in the bulk, it was concluded that it was possible to change the results of flotation by increasing the temperature of the wetting film, for example, by using steam condensation heat. For this purpose, the pulp is aerated with a mixture of air and hot steam. An increase in the temperature of the wetting film is the cause of an increase in the hydrophilic repulsion forces that stabilize the film, and the loss of stability of the wetting film is associated with an increase in the forces of hydrophobic attraction. Findings. Using the developed stand and the technique, the heat transfer coefficient was measured at different vapor concentrations in the air bubble and it was revealed that when the mass fraction of steam in the steam-air mixture was more than 0.30 kg∙kg-1 due to the heat of its condensation, water temperature in the boundary layer of the floating bubble increased by 11-14°C, leading to a decrease in thickness of the wetting film, corresponding to a change in the sign of the structural component of wedging pressure. Practical Relevance. An experimental testing of the developed technology was carried out on a sample of refractory gold-bearing ore and it was shown that when it was applied, the gold content in the flotation concentrate increased by 1.8 times with a decrease in the yield of the flotation concentrate by 39.5% rel. and gold recovery from the operation increased from 76.8% to 89.9%.