Nalco Chemical Company

Jay S Gomer

Anthony E Gross

A bacterial-assisted heap leach process is employed for the solubilization of a metal from a refractory ore containing fines and/or clay wherein at least a portion of the metal is solubilized by the bacterial oxidation of sulfides and the concomitant or sequential dissolution of the metal into a leaching solution. For some metals, the leaching solution has a pH of greater than about 9. The improvement in the process includes the application of an aqueous solution of acrylamide polymer to the ore in an amount effective to agglomerate the fines and/or clay prior to heap formation. The acrylamide polymer has a molecular weight of at least 500,000 and is comprised of from about 0 to about 100 mole percent of (meth)acrylamide mer units and from about 0 to 100 mole percent of N-sulfoalkyl(meth)acrylamide mer units. The acrylamide polymer is preferably applied to the ore as an aqueous solution formed at least in part by recycled bio solution.

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Geneva, IL, United States of America

Jay S Gomer