Heap leaching of poor nickel laterites by sulphuric acid at ambient temperature

Abstract

Column leach tests were conducted to evaluate the amenability of poor Greek nickel laterites to heap leaching with dilute sulphuric acid at ambient temperature. The ore tested was limonitic laterite with less than 1 % nickel and it was subjected to a suitable pretreatment with water prior to it being loaded into columns, following findings of preliminary research work. The acid solution was recycled after suitable pH adjustment. Factorial designs were used to determine the effects and interactions of the following factors: sulphuric acid concentration, ore column height, ore grain size and ratio of the solution volume to the ore quantity. The responses which were investigated included nickel and cobalt recoveries, co-dissolution of iron, calcium, magnesium, aluminium, chromium and silica and also sulphuric acid consumption. Experimental error was also determined. The tests showed that nickel recovery of 86% could be achieved in 80 days.