The mine employs a workforce of 430. Mining operations were halted in April 1998 after the tailings dam at Aznalcollar failed, releasing approximately 6 Mm3 of tailings water and tailings into the surrounding countryside. Apirsa received permission to recommence full operations at Los Frailes in March 1999, began mining again in April of that year, and resumed milling operations in June 1999. The deposits are in rhyolite-hosted pyroclastics as either mineralised pyroclastics or pyritised zones.
Blasted ore is loaded using mining shovels into haul trucks for transport to the primary crusher.
Significant modifications to the mill have included the introduction of autogenous grinding, conversion of the ball mills to secondary pebble mills and the installation of new and larger Dorr-Oliver flotation cells. After crushing and grinding, the concentrator uses conventional flotation techniques to recover zinc, lead and copper concentrates. After dewatering, these are transported 90 km by road to the port at Huelva. The copper concentrate is shipped to Japan. On 25 April 1998, a failure of the tailings dam wall released an estimated 5.5 Mm3 of tailings water and about 1.3 Mm3 of tailings.