Experimental study of phase entrainment in copper solvent extraction

The entrainment of the organic phase in the aqueous applied to typical solutions in a solvent extraction of copper process was studied. The organic phase used is composed of the commercial extractant LIX 984-N diluted in Shellsol 2046 AR. The aqueous phase contains 6 g/L of Cu2+, at pH 2 and 20 ºC. The variables studied were: mixing speed of 400 to 1000 rpm; mixing time of 3 to 30 minutes; initial pH of the electrolyte 2, 3, and 4; percentage of extractant in the organic phase 10 to 30% v/v; and copper concentration in the aqueous phase 1 to 6 g/L. It was determined that the entrainment of the organic phase in the aqueous is determined by the physical properties of the phases in equilibrium and by the system’s hydrodynamics, and it is a phenomenon that involves the advancing speed of the interphase (or dispersion band) and the displacement speed of the organic drops.

Attachment of Acidithiobacillus ferrooxidans and Bioleaching of Chalcopyrite under Influence of Organic Substances Associated with Copper Solvent Extraction

Small quantities of organic substances are inevitably entrained and dissolve in the aqueous raffinate during a copper solvent extraction (SX) operation. These organic substances contaminate the bioleaching environment through the loopback of the raffinate. The attachment of cells of Acidithiobacillus ferrooxidans (At. ferrooxidans) to the low grade chalcopyrite ores and the bioleaching of the ores under the influence of solvent extraction organic substances were investigated. The results showed that the cells of At. ferrooxidans were apt to attach on the SX organics-contaminated chalcopyrite ores with an adsorption ratio of about 83%, larger than that of 44% on the uncontaminated ores as a control. However, the bioleaching efficiency decreased from 25% to 15% under the influence of the SX organic substances. Obviously, an improvement of the cells attachment did not improve the bioleaching efficiency of the low grade chalcopyrite ores by At. ferrooxidans in the present of the SX organic substances. The SX organic substances impacted the metabolism of At.ferrooxidans and their bioleaching ability.