THE EFFECT OF THE DISPERSION DEGREE ON THE FLOATABILITY OF AN OXIDIZED ZINC ORE

Most of the Brazilian zinc deposits consist of the so-called ''calaminic'' ores (silicates and carbonates). Considering that the Italian reserves at Sardinia are now exhausted, the ores from Vazante - MG may be considered unique. Earlier studies of microflotation in a modified Hallimond tube indicated that the dispersion degree of the pulp should control the flotation behaviour of these ores. Dispersion tests were then performed in a sedimentation tube with samples of calaminic zinc ores from Mineracao Areiense. Bench scale flotation testwork was carried out under the best dispersion conditions, following traditional cationic flotation. The major objective of the present investigation was the establishment of correlations between slurry dispersion, desliming and flotation. It was verified that an adequate slurry dispersion is not enough for a high selectivity, a combination of desliming and dispersion being required. The performance of the dispersing agents and the magnesium grade in the concentrate depend on the pulp percent solids. The most efficient dispersing agents were determined for the three samples under investigation.