ACID LEACHING OF NICKEL LATERITE ORES FOR THE EXTRACTION OF THEIR NICKEL AND COBALT VALUES

摘要

The present invention provides an improved process of hydrometallurgical treatment of laterite ores of the limonitic type for the recovery of nickel and cobalt using sulphuric acid. In order to obtain high extractions of these metals while treating these ores in their humid state, in reaction times of up to 60 minutes, temperatures of up to 270 DEG C and corresponding pressures of up to 800 psia are used. In the present invention, a significant portion of the "mother liquor" emanating from the pressure leaching reaction is recycled to the feed preparation stage thereby substituting for all or at least a major proportion of the fresh water or de-ionized water that must be added. Concomitantly with the major savings in fresh water or de-ionized requirements, a significant reduction in new sulphuric acid requirements is effected along with a corresponding saving in limestone and lime required for subsequent neutralizations.