| Summary: | Reagent concentration is an important factor in froth flotation. It is also known that the froth structure plays an important role in the flotation separation achieved. The effect of surfactant concentration, conditioning time, pH and adsorption of a single reagent on froth structure and flotation performance was studied in a HaIIimond tube (micro scale) and Denver cell (macro scale). The surfactant concentration was found to be important factors in determining froth structure and stability. The appearance of the upper bubble surface of flotation froths is used qualitatively as a basis for control in industrial flotation cells. A quantitative image-processing algorithm was developed for froth surface bubble size distribution measurement that is largely insensitive to factors such as froth type, lighting conditions and bubble size. This was used to estimate the flux of bubble surface area overflowing the weir. A quantitative kinetic model based on the flux of loaded bubble surface overflowing the concentrate weir in a free-flowing froth is described. The froth is divided into two distinct phases; the bubble shells, which contain hydrophobic solids selectively, attached, and the inter-bubble lamellae, which contain non-selectively entrained solids. Quantitative relationships between the froth structure and flotation performance were determined. It was found that the froth flux relationships did not scale-up directly from micro to macro scale. A sampling technique was developed for measuring the bubble shell solids loading, which allowed the lamella thickness and solids concentration to be estimated. Based on adsorption studies and froth structure, using various reagent addition strategies was investigated to enhance the flotation performance by altering the froth structure. It was found that the flotation performance could be improved by continuous reagent addition during flotation.
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