The Las Cruces mine is an open pit operation and process plant located in the Sevilla Province of Southern Spain.
The mine uses leaching and electrowinning technology to produce copper cathode. The plant is designed to produce approximately 72,000 tonnes of copper cathode per year which is shipped as final product.
Las Cruces uses conventional open pit mining methods, based upon hydraulic shovels and trucks, with drilling and blasting in the lower marls and ore zones. The project has a relatively high stripping ratio supported by the high grade ore. Las Cruces uses contract miners for all mine production.
Ore at Las Cruces is mined from an open pit. The metallurgical plant relies on an atmospheric leaching process to recover copper from the rich Las Cruces chalcocite ore. A unique feature of the plant is the use of eight OKTOP agitated reactors to dissolve the copper under conditions of high temperature and high acidity. Oxygen is also added into the reactors to complete the reaction. The feed to the leaching reactors is mine ore that has passed through three stages of crushing and a single stage of grinding.
Once leached, the liquid is separated from the ground solids to become PLS, the feed for the solvent extraction (“SX”) area. In the SX area the copper is passed to an organic solution and then to the electrolyte that feeds the electrowinning cells. The electrowinning cells produce LME grade copper cathodes weighing approximately 50 kilograms each. An automated crane and stripping machine then harvests and packages the cathodes for shipment.
Guidance on production of copper in 2014 is between 69,000 and 72,000 tonnes. Efforts have been underway, and will continue for some time, to test and debottleneck the plant for higher throughput rates as a result of lower grades, which are expected in late 2014.