In one aspect the present invention provides a method of recovering gold
from each of at least two different refractory gold-bearing sulfidic
mineral materials. A first mineral material is subjected to biooxidation
pretreatment to release gold locked within sulfide minerals. The
biooxidation produces an acidic biooxidation liquor effluent that
contains significant dissolved iron in the ferric form. All or a portion
of the biooxidation liquor effluent is used as an acidic treatment liquid
to treat the second mineral material, which contains acid-consuming
minerals. During the treatment, acid-consuming minerals react with the
acidic solution, raising solution pH and resulting in reduced solubility
and precipitation of dissolved iron and other metals. Also during the
treating, sulfides in the second mineral material or oxidized, thereby
releasing gold for subsequent recovery.