Caro's acid—an oxidant for acid leaching of uranium ores

CIM Bulletin, Vol. 77, No. 862, 1984

R.J. RING Australian Atomic Energy Commission, Research Establishment, Lucas Heights Research Laboratories, N.S.W., Australia, M. YAMINE and D.J. WATERS Interox Chemicals Pty Ltd Botany, N.S.W., Australia

An experimental program has been carried out by the Australian Atomic Energy Commission to compare the effectiveness of Caro's acid as an alternative oxidant to pyrolusite in the leaching of uranium ores from the Alligator Rivers region of northern Australia. Batch leaching tests on Ranger, Nabarlek, Koon-garra and Jabiluka ores showed that uranium extraction was unaffected by choice of oxidant, but that Caro's acid reduced acid requirements by 15 - 25%. Lime requirements for neutralization of tailings liquors were reduced by 20 -30%. The batch studies were extended to a four-stage continuous leaching circuit with a capacity of 400 g ore h-1. Comparative leaching tests confirmed the reagent savings obtained in the batch tests. Following these encouraging laboratory results, Interox Chemicals Pty Ltd carried out plant trials using Caro's acid. Reagent savings in the mill were similar to, or better than, those obtained in laboratory testwork. The trials also established that Caro 's acid has a number of operational advantages over pyrolusite.

Keywords: Uranium extraction, Caro's acid, Leaching, Oxidants, Pyrolusite, Hydrogen peroxide, Alligator Rivers ores