Abstract: The improvement in the method of recovering copper from low grade ore containing oxidized copper ore which comprises establishing a dump of such ore in fragmented form, substantially completely wetting the ore in the dump with strong aqueous sulfuric acid containing at least about 100 g/l H.sub.2 SO.sub.4, allowing the acid wetted ore to age for a period of at least about three days, thereafter washing the aged ore with dilute aqueous sulfuric acid containing about 5 to 40 g/l H.sub.2 SO.sub.4, collecting such washings, and recovering copper therefrom.

Abstract: Copper is recovered from ores containing sulfidic copper minerals by forming the ore into a dump leach heap, and substantially saturating (i.e. thoroughly wetting) the ore in the heap with an aqueous strong acid solution containing 100 to 400 g/l H.sub.2 SO.sub.4 and 5 to 50 g/l ferric ion. The ore thus saturated is cured in contact with the strong acid solution for a curing period of at least 2 days, and generally from 5 days to 6 months or even longer, depending on the character of the ore and its permeability by the acid solution. The ore in the heap may be run of mine size, or may be coarsely crushed, again depending on permeability to the strong acid solution. After the curing period, the ore in the heap is washed by percolating through it a weak acid solution containing up to 50 g/l H.sub.2 SO.sub.4 and 5 to 50 g/l ferric ion. The wash solutions are collected and treated for copper recovery. Washing is continued until the copper content of the heap has been largely extracted.

Abstract: A process for the leaching and recovery of copper values from copper-containing material which comprises vat leaching a sulfidic copper-containing material with an aqueous acidic ferric sulfate leach solution initially containing at least 10 gpl ferric ion to form a copper pregnant leach solution containing substantially less than 10 gpl ferric ion and a corresponding increase in ferrous ion concentration, extracting said leach solution with an extractant selective to copper and non-selective to iron to strip the copper values from said leach solution, adjusting the acid content of the stripped leach solution to between about 10 to 20 gpl to form an acidic leach solution, passing said acidic stripped leach solution through at least one mineral dump containing oxidized copper for a time sufficient to cause reoxidation of ferrous ion to restore the concentration of ferric ion to at least about 10 gpl, adding sufficient sulfuric acid to the dump off-solution to cause said solution to have an acid concentration o