Clay particle swelling, colloidal dispersion, and the associated loss of ore permeability in subterranean leaching are prevented by injection treatment with a fluid containing cationic polymers, diluents, and leaching agents. The polymers are preferably of the hydrocarbon chain type with molecular weights of 1,000-1,000,000, and include commercial clay stabilizers developed for use in drilling wells. The diluent solution preferably contains nacl 8, hcl 5-15, kcl 4, and methanol 5 pct. The suitable leach solution is aqueous nahco3 of ph approximately 8.5 and containing h2o2 oxidizer. The process is especially suitable for leaching uranium ore deposits containing calcium montmorillonite clay susceptible to swelling.
Chem. Abstr. 113:101,224H, May 15, 1990 U.S. Pat. 4,925,247