Agglomeration and column leaching behavi

Nickel (Ni) laterites account for about 60–70% of the world’s nickel mineralization. The processing of low grade (e.g., 1% Ni) laterite ores is favoured by the use of the more cost-effective hydrometallurgical techniques (e.g., atmospheric agitated tank or heap leaching) instead of smelting. Application of heap leaching, which boasts of low capital and operating expenditures, however, is very limited due to intractable challenges such as poor heap porosity/permeability associated with most laterite feed ores. Feed particles’ agglomeration into robust and porous agglomerates of right size range enables permeable and geotechnically stable bed required for successful heap leaching to be constructed. In this paper, several basic and applied studies of the agglomeration and column leaching behaviour of real Ni laterites ores are reported. The work involved isothermally, batch agglomeration tests carried out to produce 5–40 mm agglomerates which were characterized and subjected to >100 days of laboratory column leaching. The effect of ore characteristics (e.g., mineralogy/chemistry and particle size distribution) on agglomeration behaviour and agglomerates’ column leaching behaviour was investigated through laboratory column testing. Links between mineralogy/chemistry and size, binder dosage, agglomeration behaviour, agglomerate properties and leaching behaviour are established. The significance of the findings to Ni laterite plant agglomeration for enhanced heap leaching is discussed.