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The aim of this paper is to present and discuss the air dispersion parameters determined for industrial Brazilian flotation circuits. The rougher and scavenger circuits of RPM, Taquari-Vassouras, Copebras and Fosfertil-Catalão (today Vale Fertilizantes) were investigated. For RPM and Taquari-Vassouras, the superficial gas velocity (Jg), gas hold-up (&egr;g), bubble size diameter (d32) and superficial area bubble flux (Sb were measured, whereas only the Jg and &egr;g were measured in the other circuits. The results pointed out that, except for RPM, all the circuits presented very low values for the air dispersion parameters. Taquari-Vassouras presented the lowest values for average Jg and gas hold-up: 0.05 cm/s and 5%, respectively. The highest value was presented for the rougher circuit of Cope-bras, 1.17cm/s, while RPM presented the highest values for &egr;g and bubble size, respectively 31% and 2.61mm. In the circuits where the calculation of the Sb parameter was possible, the results obtained lay in a range lower than those re-ported in literature. [ABSTRACT FROM AUTHOR]

In the Ouro Preto - MG region, there are several soap stone workshops where artesans create souvenirs and pans. This activity produces a large amount of residues which are discarded without any control. The objective of this work was to recover the talc mineral present in the size fraction below 74µm of these residues by froth flotation and chemical leaching with HCl. Among the flotation variables studied, only the percentage of solids and frother dosage proved to be significant for mass recovery and whiteness. This process produced a concentrate whose whiteness (ISO) was 68.56% and whose chemical composition meets paint and paper standards. After chemical leaching of the flotation concentrate, a whiteness of 84% was obtained and its chemical composition met the specifications of the plastic and anti-adherant plastic industries. [ABSTRACT FROM AUTHOR]

The current processing study seeks to improve operations for the direct and reverse flotation of apatite originating from carbonatically-affiliated rocks to obtain an apatite concentrate in accordance with the phosphoric acid industry specifications. The direct flotation of apatite was carried out in two flotation phases, rougher and cleaner. The aim of direct flotation was to generate a product to feed the reverse flotation circuit of apatite. Reverse flotation was performed in three stages (rougher, cleaner and recleaner) and at pH 5.0, using phosphoric acid (H3PO4) as an apatite depressor. Summing up, the results of reverse flotation tests pointed out apatite recovery, which shows that the specific reagents used favored system selectivity. It was possible to obtain an apatite concentrate with 38.11% of P2O5, 50.98% of CaO, 1.07% of Fe2O3, 0.67% of MgO and ratio CaO/ P2O5 of 1.34 [ABSTRACT FROM AUTHOR]