Beneficiation of a Greek serpentinic nickeliferous ore - Part II. Sulphuric acid heap and agitation leaching

Serpentinic laterite ore, after suitable mineral processing operations as described in Part I, was subjected to heap as well as atmospheric agitation leaching. The heap leach results showed that serpentinic laterites can be leached by this technique. The nickel and cobalt recoveries achieved were 60% and 45%, respectively, in 10 days. The sulphuric acid consumption amounted to 40 kg H2SO4/kg Ni. However, the effectiveness of leaching depended on the calcite content of the ore as this adversely affected the permeability of the heap. The agitation leach tests showed that the ore could be leached at atmospheric pressure without problems. Recoveries achieved were up to 74% for nickel and 51% for cobalt, after 2 h of leaching. The sulphuric acid consumption, depending on conditions, averaged 55 kg/kg Ni. Pulp mixing and filtration were excellent. (C) 2004 Elsevier B.V. All rights reserved.