Method for immobilizing contaminants in previously leached ores

Abstract

This invention relates to a process for reducing to environmentally acceptable levels the amount of soluble or mobile contaminants in formations that have been subjected to in situ leaching to recover mineral values therefrom. The present process is also applicable to surface milling operations. In accordance with the present invention, an aqueous solution containing orthophosphates is introduced into the formation to immobilize contaminants by forming a relatively stable precipitate. For example, radionuclides such as uranium, thorium or radium form stable precipitates with orthophosphates. When the formation fluids contain a high concentration of carbonates, the formation fluids are treated to reduce the carbonates concentration to levels which do not substantially interfere with the phosphate precipitation of contaminants.

Dependencies are inferred from the claim text.