Physical-chemical characterization of lateritic mineral mixtures and pulps for the Moa pressure acid leaching process

Abstract

The research analyzed the chemical and mineralogical composition of mixtures of lateritic minerals with different magnesium contents, from which the pulps were formed for the Moa pressure acid leaching process. Chemical and mineralogical characterizations were carried out by atomic absorption and X-ray diffraction, respectively. The sedimentation behavior was evaluated with and without the use of additives and the rheological characteristics and viscosity of the lateritic mineral pulps (raw pulps) were analyzed. The sedimentation tests were carried out by observing the height of the liquid/solid interface for two hours and the rheological behavior was evaluated using the shear stress curves, from which the viscosity was calculated. The average contents of SiO2, Al, and Cr in the mineral samples were 17,5; 4,3; and 1,2 %. The mineralogical phases goethite, chlorite, gibssite and lizardite were identified in the mineral samples with different magnesium contents. The sedimentation rates of the raw pulps that were prepared with 2,84 and 3,42% magnesium minerals were equal to 0,06 m/h. The pulp that was prepared with 3, 42% magnesium mineral, regardless of the presence of additives, showed a non-Newtonian rheological behavior of the real plastic type (Herschel Bulkley model) and its viscosity with the joint presence of the additives sodium and iron sulfate was equal to 0,033 Pa.s.