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Studies have been carried out of the solubilisation of lateritic nickel ores by the action of heterotrophic bacteria Bacillus subtilis. A sample of Brazilian lateritic nickel ore was used in which goethite was the primary Ni mineral, and the ore contained 1% NiO (0.85 % Ni). Bioleaching batch experiments demonstrated that about 8% Ni (0.7 mg Ni/ g ore) were solubilised by the B. subtilis after 7 days. Pre-treating the ore by microwave heating was found to increase the bioextraction to 26% Ni (2.3 mg Ni/ g ore)., Studies have been carried out of the solubilisation of lateritic nickel ores by the action of heterotrophic bacteria Bacillus subtilis. A sample of Brazilian lateritic nickel ore was used in which goethite was the primary Ni mineral, and the ore contained 1% NiO (0.85 % Ni). Bioleaching batch experiments demonstrated that about 8% Ni (0.7 mg Ni/ g ore) were solubilised by the B. subtilis after 7 days. Pre-treating the ore by microwave heating was found to increase the bioextraction to 26% Ni (2.3 mg Ni/ g ore).

The use of greensand slate as a source of an agricultural fertiliser, potassium thermophosphate, was investigated. Seven samples of the slate, which came from Cedro do Abaete, Minas Gerais state, Brazil, were found to contain an average of 37% glauconite, 24% quartz and 7% micas using X-ray diffraction, thin section microscopy and X-ray fluorescence. While the slate could be used for fertiliser production, it would need the addition of another phosphate rock due to its low phosphate content., The use of greensand slate as a source of an agricultural fertiliser, potassium thermophosphate, was investigated. Seven samples of the slate, which came from Cedro do Abaete, Minas Gerais state, Brazil, were found to contain an average of 37% glauconite, 24% quartz and 7% micas using X-ray diffraction, thin section microscopy and X-ray fluorescence. While the slate could be used for fertiliser production, it would need the addition of another phosphate rock due to its low phosphate content.

Detailed mineralogical characterisation was carried out using scanning electron microscope, energy dispersive spectrometer and X-ray diffraction techniques. Superficial treatments with HCl, HNO3 and HF were also carried out to evaluate the modifications on surface compositions and the morphology of the particles for flotation purposes. The studies showed that both xenotime and zircon present very small inclusions of thorite, zircon is strongly metamicitised giving rise to malacon. The HF pretreatment deeply affected the morphology of the particles as well as the surface properties in relation to flotation., Detailed mineralogical characterisation was carried out using scanning electron microscope, energy dispersive spectrometer and X-ray diffraction techniques. Superficial treatments with HCl, HNO3 and HF were also carried out to evaluate the modifications on surface compositions and the morphology of the particles for flotation purposes. The studies showed that both xenotime and zircon present very small inclusions of thorite, zircon is strongly metamicitised giving rise to malacon. The HF pretreatment deeply affected the morphology of the particles as well as the surface properties in relation to flotation.

Brazilian kaolin production is increasing, mainly due to the development of new enterprises along the Capim and Jari rivers. These deposits account for 80% of Brazilian resources. Total Brazilian production in 1995 was 1 957 750 t with a production value of US, Brazilian kaolin production is increasing, mainly due to the development of new enterprises along the Capim and Jari rivers. These deposits account for 80% of Brazilian resources. Total Brazilian production in 1995 was 1 957 750 t with a production value of US