to control ph but rather on the acid consuming characteristic of the ore being processed and a limit to the amount of acid added at the ph at which the leach is controlled iron is predominantly present as the ferrous ion which has a lower affinity for the resin than copper application_number US 201515327828 A description in select embodiments the invention involves the treatment of acid consuming copper ores in alternative embodiments the ores may for example be copper oxide ores such as but not limited to delafossite chrysocolla azurite dioptase brochatite tennorite atacamite and malachite and mixtures thereof these ores are representative of higher acid consuming copper oxides ores other oxide ores may be present that are not acid consumers such as antlerite and chalcanthite processes of the invention involve adding a controlled amount of mineral acid to the comminuted copper ore in select embodiments sulphuric acid may be used hydrochloric acid may also be used or mixtures thereof in general the ore is comminuted to a grind size less than the average diameter of the ion exchange resin beads for example the ore may be ground to an average grind size less than about 500 u03bcm or alternatively less than about 200 u03bcm in select embodiments finer grind sizes for example of less than 100 u03bcm may facilitate separation of ion exchange resin from the ore solids as well as enhancement of leaching kinetics leaching may be carried out in the presence of various ion exchange media such as cross linked polystyrene or acrylic polymers functionalized with groups exhibiting preferential selectivity for copper from mildly acidic solutions for example polystyrene divinylbenzene crosslinked polymers.