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EFFECTS OF FLOCCULATION CONDITIONS ON THE DEWATERABILITY OF HEMATITE AND RED MUD SUSPENSIONS

Hulston, J., de Kretser, R.G. and Scales, P.J.

Flocculation is commonly used in the minerals industry, such as the Bayer process, as a means of hastening solid-liquid separation. A comprehensive characterisation technique has been developed within the PFPC, which allows flocculation and dewaterability behaviour of suspensions to be investigated. The technique involves flocculating suspensions in a baffle reactor and determining the initial settling rate, equilibrium bed height and supernatant turbidity. The flocculated suspensions are then analysed in terms of the gel point, compressive yield stress, Py(φ), and hindered settling function, R(φ). The information gathered from these experiments can then be used in conjunction with a one-dimensional thickener model to predict the effectiveness of flocculants on thickening.

A variety of flocculation experiments were performed on hematite and red mud suspensions with the aim of making comparisons between the two systems and determining the suitability of hematite as a model system for red mud. The two systems were compared on the basis of their flocculation and dewaterability behaviour. In addition the thickener performance of both suspensions was modelled for the various flocculation conditions investigated.