Abstract

Mining residues, in general, and metal ores, in particular, contain heavy metals within the rock. These heavy metals are very harmful to humans and, as such, are a serious problem for the environment. They can be considered as contaminated rocks. One of the heavy metals with increasing demand around the world is copper (Cu) that is the subject of this study. To extract copper from the residue with 8,950 mg copper per kg rock, a biosurfactant, rhamnolipid was used. To optimize the conditions for maximum extraction, several batch tests were performed on washed ore samples in 25C̕. The best size of particle sizes was determined to be between 0.15 and 0.3 mm while the pH was set at 6. A minimum volume of 10mL rhamnolipid of 2% concentration for 1 g of ore was required to extract about 28% of copper from the ore. Although better results are also possible with higher concentrations of rhamnolipid, the solution becomes very viscous as well. Adding 1% NaOH to the solution dramatically improved the extraction up to 42% in 6 days. Unwashed samples of mixed size particles were tested under the optimized conditions and 24% of copper was extracted. A sequential extraction procedure was performed to determine the fractions of different forms of copper in the ore. The oxide and hydroxide, residual part, and carbonates are the main fractions and the extracted ore was extracted mainly from the oxide and hydroxide part.