DEMIN - Departamento de Engenharia de Minas
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Item Flotation routes for a phosphate ore bearing silicate-carbonate gangue.(2012) Albuquerque, Rodrigo Oscar de; Peres, Antônio Eduardo Clark; Aquino, José Aury de; Pereira, Carlos AlbertoThis laboratory scale investigation addressed two different process routes for the concentration of a phosphate ore bearing a silicate-carbonate gangue: (i) bulk apatite and calcite flotation followed by calcite flotation in the presence of phosphoric and citric acids; (ii) calcite flotation in the presence of carbon dioxide followed by apatite flotation. The target of selectively separating apatite from the contaminating silicates and carbonates was achieved. Following the flotation experiments, calcite zeta potential determinations were performed aiming at clarifying the mechanisms that rule the adsorption of the soybean bran oil soap onto the mineral surface in the presence of the modifying agents phosphoric acid, citric acid, and carbon dioxide.Item Carbonate content reduction in zinc ore concentrate.(2012) Martins, Lemyr; Peres, Antônio Eduardo Clark; Galery, Roberto; Pereira, Carlos AlbertoThe hydrometallurgical zinc extraction from the willemite concentrate is impaired by the presence of high carbonate content. A stiff froth is produced causing zinc losses and acid consumption. A standard procedure was developed to de ne the acceptable froth layer height in a laboratory test. Froth layers shorter than 2 cm resulted from carbonate content in the concentrate below 10.8%. The feasibility of adding a carbonate otation stage to the circuit was tested in laboratory and pilot scales. Among the collectors investigated, only those presenting a saponi cation degree above 189 mg KOH/mg were effective in the laboratory experiments. Oleine and rice bran oil soaps were selected for the pilot scale experiments. The nal stage was a one month long industrial trial performed in a circuit consisting of three pneumatic cells G18. A comparison between the average results of the industrial trial including the carbonate otation stage and data of the raw industrial concentrate indicated that the MgO content in the concentrate dropped from 3.7%–3%. Concurrently, the carbonate content in the concentrate dropped from 11%–10.6%, the zinc grade in the concentrate increased from 41.4%–42% and the zinc recovery increased from 86.6%–89.8%. The concentrate was processed in the hydrometallurgical plant with no frothing problems.Item The infrared spectra of amine collectors used in the flotation of iron ores.(2005) Lima, Rosa Malena Fernandes; Brandão, Paulo Roberto Gomes; Peres, Antônio Eduardo ClarkInverse froth flotation is the most used concentration method for itabiritic iron ores, where the quartz gangue is floated, and the iron oxides are kept depressed by starches; medium-chain etheramine acetates are the cationic collectors used. Since there is a lack of thorough studies on the infrared spectroscopy of these reagents (and by other similar techniques), an investigation on the band assignment in the infrared spectra of a typical etheramine acetate was carried out by Fourier-transform infrared spectrometry. To distinguish the bands due to the cationic amine ion from the acetate anion ones, a molecular decyletheramine was also studied, as well as its salts, after some degrees of neutralisation, by acetic or hydrochloric acids; also, potassium acetate was included, to assess the anion bands alone. From this approach, all the significant bands were successfully assigned to the important functional groups in the collector_s molecule: NHx, C H2, C H3, –O–, and the acetate bands. A confirmation of this method was the identification of the amine cation bands alone, without the presence of the previously associated acetate bands, after adsorption onto the surface of quartz particles, from an aqueous solution of a decyletheramine acetate, at pH = 10.5.Item Pilot scale direct flotation of a phosphate ore with silicate-carbonate gangue.(2012) Albuquerque, Rodrigo Oscar de; Peres, Antônio Eduardo Clark; Aquino, José Aury de; Praes, Plínio Eduardo; Pereira, Carlos AlbertoThe present pilot scale study addresses the direct flotation route for the concentration of a phosphate ore bearing a silicate-carbonate gangue. The target was to selectively separate apatite from a phosphate ore bearing silicate/carbonate gangue using flotation columns. Based on the results of a previous laboratory scale investigation, a reagents scheme was selected and tested, using, under alkaline conditions, corn starch and a natural collector extracted from the distillation of coconut oil. An open rougher-cleaner circuit yielded a final concentrate reaching 30.5% P2O5 grade, at 80.8% recovery level.Item Flotation concentration of a xenotime pre-concentrate.(1997) Pereira, Carlos Alberto; Peres, Antônio Eduardo ClarkThe worm market for rare-earths elements is increasing due to the development of new products and applications, resulting in the need for technology to treat deposits having highly complex mineralogy, such as that of Pitinga, AM, Brazil, with estimated reserves of 146,960 t of rare-earths oxides (REO), including Y203. Mineralogically the mine of Pitinga is very rich. The initial and major target of the company Paranapanema was the production of tin concentrates from placer deposits and later from primary ore. However, geological studies identified several other minerals of potential economical importance, such as: columbite-tantalite, zircon, cryolite and xenotime, the objective of the present investigation. The response of a pre-concentrate sample of the non-conducting fraction from Pitinga " s electrostatic separator to laboratory scale physical concentration methods was very poor. Another possibility for the selective separation of xenotime and zircon (the major associated mineral) is flotation. Microflotation experiments were performed in a modified HaUimond tube with pure samples of xenotime and zircon, in the presence of hydroxamate as collector and five different reagents as depressants.Item Reagents in calamine zinc ores flotation.(2004) Pereira, Carlos Alberto; Peres, Antônio Eduardo ClarkOxidised zinc ores are traditionallyfloated with fattyamines as collector. The effectiveness of this reagent requires a pre-sulph-idisation stage with sodium sulphide in conjunction with soda ash. Especiallyin the case of calamine ores, a dispersing agent becomes necessary. The collector must be emulsified with a fuel oil and the frother. This flotation system is characterised by the use of verylarge amounts of reagents. The proportion of each reagent in the reagents system must be carefullyoptimisedItem Dispersion effect on a lead–zinc sulphide ore flotation.(2009) Silvestre, Marcelo Oliveira; Pereira, Carlos Alberto; Galery, Roberto; Peres, Antônio Eduardo ClarkThis investigation was performed with samples from a lead–zinc sulphide deposit aiming at studying the influence of the dispersion degree of the particles in the pulp on lead and zinc flotation. Samples of ore and also of the minerals sphalerite, galena, pyrite, and dolomite were selected for the experiments. Nine types of dispersing agents and six blends among them were employed. A set of three dispersing agents was selected for the lead flotation and another set of three was chosen for zinc flotation. The criteria for the reagents selection were: high dispersion degree for galena and low for the other species, high dispersion degree for sphalerite and low for the other species, low dispersion degree for pyrite and high for the other species, and high dispersion degree for all species. Lead flotation experiments were performed under three conditions aiming at verifying the influence of the dispersing agent, of the pH, and of sodium carbonate. The zinc flotation tests were carried out at pH 10.5, modulated with lime. The use of dispersing agents in lead flotation did not improve the overall efficiency of the circuit for, despite improving the lead metallurgical recovery, they increase significantly the zinc losses in the lead concentrate. Sodium carbonate presented a low dispersion degree and did not affect the lead flotation results when compared with those achieved at natural pH and at pH 9.8 modulated with lime. Two dispersing agents were particularly effective in zinc flotation: dispersant 3223, a sodium polyac-rylate, and sodium hexametaphosphate. Both reagents significantly enhanced zinc recovery without impairing the concentrate quality.