MODIFICATION OF RHEOLOGICAL PROPERTIES OF NICKEL LATERITE FOR STIRRED MILLING

摘要

The rheological properties of siliceous goethitic (SG), goethitic (G), and saprolitic (SAP) nickel laterites were investigated to assess the effect of solid content, pH, dissolved salts (NaCl and Na_2SO_4), and dispersants (sodium silicate, sodium hexametaphosphate (SHMP), and ammonium polymethacrylate (Darvan C-N)) on the rheological properties of the pulps. In terms of solid content, SG slurries exhibited poor rheological behaviour, as compared to SAP and G slurries. The influence of pH on the rheology of different nickel laterite slurries differed significantly, and a specific slurry pH is suggested for each laterite type. SHMP, at a dosage of 2 kg/t, was the most effective dispersant in decreasing the yield stress of all samples. Sodium chloride (2 M) decreased the yield stress of SAP significantly among the three samples. Optimum conditions are suggested for selective size reduction of nickel laterites in stirred milling.