The agitation intensity has a directly influence on flotation performance, lifting the particles and promoting the contact of bubbles and particles. In this paper, the energy input by the agitation on apatite flotation was investigated. The influence of pulp agitation in the flotation rate of particles with different sizes and two dosage levels was evaluated by batch testing. The flotation tests were conducted in an oscillating grid flotation cell (OGC), developed to promote a near isotropic turbulence environment. The cell is able to control the intensity of agitation and measure the energy transferred to the pulp phase. A sample of pure apatite was crushed (P 80 =310µm), characterized and floated with sodium oleate as collector. Four levels of energy dissipation, from 0.1 to 2 kWm -3 , and two levels of collector dosage are used during the tests. The flotation kinetics by particle size were determined in function of the energy transferred. The results show a strong influence of the agitation intensity on the apatite flotation rate with both low and high dosage. For fine particles, when increasing the energy input, the flotation rate increase too, and this fact can be attributed to elevation of bubble-particle collisions. The kinetic result for the coarse particles demonstrated a reduction of the flotation rate whenever the energy input for this particle size was increased, whereby the turbulence caused by the agitation promotes the detachment of bubble-particle.
Tailings disposal in the form of diluted slurries has a tendency for particle size segregation, where coarse particles settle near the discharge point, and finer particles are carried by the water flux to more distant regions. This causes a loss of reservoir capacity due to voids between the coarser particles and increased water content in the deposit. This work aimed to evaluate the feasibility of reaching non-segregable high-density slurries with fine tailings from the niobium oreflotation process and measure its disposal parameters. The innovation is to achieve increased solids percentage in the settled deposit and to avoid particle size segregation along the slurry path with niobium tailings. The study involved physical, chemical, and mineralogical characterization and semi-pilot thickening tests to produce enough volume of underflow with different bed heights and solids flux rates. Slump, rheology, and flume tests were performed to evaluate underflow disposal characteristics. The results indicated that the thickener bed height did not significantly influence the underflow solids content, yield stress, or slump. The solids flux rate, on the other side, had a greater influence—the higher it was, the lower the solids content, yield stress, and disposal angle, along with a higher slump. In flume tests, a high density of non-segregable tailings slurry was achieved with 1.96 t/m3, corresponding to an underflow with 66.8% solids, 43.9 Pa of yield stress with 0.5 (t/h)/m2, and 0.5 m of bed height.
ResumoUm estudo de caracterização foi conduzido para amostras mineralizadas em terras raras dos cinco principais litotipos do depósito de Catalão: Foscorito, Flogopitito, Bebedourito, Silexito e Cobertura. Os maiores teores de terras raras foram observados nas frações finas, predominando as terras raras leves, sendo acima de 95% em massa das terras raras totais. Frações granulométricas de cada litotipo foram submetidas a caracterização mineralógica, onde foram avaliadas as composições modais e suas associações mineralógicas, assim como a liberação da monazita por faixa granulométrica. A mineralogia presente nos litotipos é similar, embora com diferentes proporções. Confirmou-se que o principal mineral portador de terras raras em todos os litotipos é a monazita, porém suas associações e relações texturais podem variar. A mineralogia complexa torna tecnicamente inviável o uso de rotas de processos convencionais de concentração física, tais, como separação magnética e densitárias, além de flotação. Palavras-chave: Caracterização; Terras raras; Fosfato; Monazita; Catalão. MINERALOGICAL CARACTERIZATION AND ALTERNATIVE TO CONCENTRATE THE RARE EARTH LITHOTYPES FROM ALCALINE COMPLEX OF CATALÃO -GO AbstractA characterization study was conducted with five rare earth ore samples from the main lithotypes of Catalão deposit: Phoscorite, Phlogopitite, Bebedourite, Silexite and Cover. The fines particles have the higher rare earth grades, with predominance of light rare earth, corresponding to more than 95% of the rare earth total. The modal composition, mineral association and monazite liberation were determinate in the particle sizes fractions of each. The minerals determined in each sample were similar but in different concentrations. It was confirmed that monazite is the main rare earth bearing mineral for all the lithotypes, but its associations and textures are variable. The complex mineralogy becomes the use the conventional technics to concentrate rare earth mineral unavailable, like magnetic and density separation, besides flotation.
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