Extraction and Purification of Copper from a Nigerian Chalcopyrite Ore Leach Liquor by Dithizone in Kerosene

Abstract

The extraction and purification of copper by dithizone in kerosene from an aqueous chloride chalcopyrite leach liquor containing 934.44 mg/L Cu, 2326.73 mg/L Fe, 92.14 mg/L Mn, 0.65 mg/L Mg, 0.22 mg/L Ca, 0.076 mg/L Sn and 0.011 mg/L Pb was investigated. The effects of extractant concentration and pH of aqueous media on the total copper extraction were studied. The results of fundamental studies on solvent extraction of synthetic solutions of Cu(II) showed that metal ion extraction increased with increasing pH and extractant concentration. The leach liquor purification was firstly done by total precipitation of iron and manganese using Ca(OH)(2) and H2O2 as oxidizer at pH 3.58 and 4.25, respectively. An extraction efficiency of 97.3% total copper was obtained by 0.2 mol/L dithizone in kerosene at 25 +/- 2 degrees C within 30 minutes at pH 5.0. A 0.1 mol/L HCl solution was found to be adequate for the stripping of about 98.3% Cu from the loaded organic phase. The stripped copper solution was recovered as copper oxide (Tenorite, CuO : 05-0667) via precipitation with sodium hydroxide followed by calcination at 600 degrees C for 120 minutes. Finally, an operational scheme summarizing the extraction procedure to obtain a high grade copper compound was presented.