Research On Mineral Particle Size Distribution And Its Effect On The Flotation Of Middle-low Grade Phosphate Ore

Phosphorus is indispensable to human life, and also an important resource to moderneconomic development. While phosphorite is the main type of phosphate ore in China,since high grade phosphate ore has been depleted as the demand increases year by year andthe non-renewability of mineral resources. How to rationally explore and utilizemiddle-low grade phosphate ore has become the center of attentions. Flotation is one of themost effective way to obtain high grade phosphate concentrates. While due to their lowgrade, fine grain size and complex in mineral composition, the middle-low gradephosphate ore have always experienced a low flotation performance problem. Therefore,improving the flotation technology of middle-low grade phosphate ore, and finding moresimple and effective ways to obtain high grade phosphate concentrate has becomingparticularly important.Researches on the processing mineralogy of middle-low grade phosphate ore haverevealed that both collophane and the gangue minerals in grounded phosphate ore varyaccording to the particle size, with gangue minerals such as quartz and dolomite tend to beconcentrated in fine fractions, while the phosphate mineral in coarse fractions. This mightbe one of the reasons why the fine particles are difficult to float. Although traditional bulkflotation method can obtain qualified phosphate concentration through complex direct andreverse flotation processes, always come with a large consumption of regents, lead to lowefficiency. To improve this situation, we have done some research through flotation processof middle-low grade phosphate in this thesis. By conditioning the factors as reagent systemand flotation time, we have studied the flotation behavior and grain-size variationcharacteristics in the flotation process. Through all those we learn how the content ofphosphate rock powder changes with different size levels and its reasons. The traditionalbulk flotation, sized flotation, and separated conditioning (fine and coarse fractions) plusmixed flotation processes have been tested and the superiority of sized flotation wasproved.The experiment results demonstrate that flotation performance are vastly differentbetween different particle sizes, the coarse and fine fractions are hard to float while theintermediate grain size particles is relatively easy. The flotation parameters are alsosensitive to the change of flotation conditions, such as flotation reagent system andtemperature. It turns out that particle size distribution of collophane and gangue mineralshas a great impact on flotation output.According to size analysis of various flotation conditions, it is found that mineralparticle size and its composition before flotation determines the separation efficency to acertain extent. Fine grinding has led to a high percentage of fine grain particles formiddle-low grade phosphate ore, thus affects the reagent efficiency and flotation result, then causing difficulty in beneficiation. Through the results in comparison of differentflotation methods shows the sized flotation process might be an effective way tobeneficiate the middle-low grade phosphate ore. Which is valuable to understand theflotation mechanism of phosphate ore, meanwhile improving the flotation process andincreasing the separation efficiency.