The development of a flotation simulation methodology towards an optimisation study of UG2 platinum flotation circuits
Doctoral Thesis
2001
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University of Cape Town
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Abstract
The design of new flotation plants is still based substantially on experience obtained from prior plant designs. Design criteria are typically based on rule of thumb procedures that often prove to be highly ineffective. The development of appropriate models of the flotation process is a means of addressing these problems so that flotation plant simulations can be performed to identify the true potential of existing plants as well as in the design of new flotation plants. This thesis addresses the complex issue of developing a robust methodology for use in flotation circuit modelling and simulation, based on the operation of pilot-scale flotation equipment. The investigation is focussed on the processing of platinum bearing ores from the UG2 reef in South Africa. The UG2 reef is of considerable economic importance, containing a substantial proportion of the world wide reserves of platinum group metals. However, UG2 ore has very complex mineralogy, and a high degree of association with chromite, which renders processing of this ore relatively difficult. Consequently, optimising the design of flotation circuits to treat this ore has proved challenging, and has been the focus of much attention by major platinum producers over the last 10 to 20 years.The primary aim of this thesis is to identify, evaluate and refine appropriate flotation models and modelling procedures reported in the literature, and use these models to develop a flotation circuit simulation procedure that can be used to provide a sound basis for the evaluation of current UG2 circuit design trends, and as an optimisation tool for the design of UG2 circuits in the future. The processing of UG2 ore from three different locations is evaluated, using two continuous pilot plants of different size, each operated in a variety of different configurations. The investigation required extensive modification of the pilot plant facility that was used, to facilitate the acquisition of the data required by the selected models.The basis and implications of these modifications with respect to the design and operation of pilot plants as a tool for design and optimisation is extensively covered. The modelling approach adopted in this study is based on the separation of the factors affecting flotation into those arising from the characteristics of the ore (floatability) and those arising owing to the hydrodynamics in the equipment, in both the pulp and froth zones of the cell. It is proposed that the pulp zone performance can best be related to the bubble surface area flux based on the work of Gorain et al (1997), while ore floatability is modelled using a distributed floatability model, based on the approach developed by Runge et al (1997) and Harris (1997). The performance of the froth phase with respect to minerals recovered by true flotation is modelled based on the approach proposed by Harris (1997) and Gorain et al (1998), while entrainment in the froth is modelled using the approach proposed by Savassi et al (1998).
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Bibliography: p. [251]-266.
Reference:
Harris, T. 2001. The development of a flotation simulation methodology towards an optimisation study of UG2 platinum flotation circuits. University of Cape Town.