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Rheology of concentrated bauxite residue suspensions
thesisposted on 2017-11-21, 00:49 authored by Quoc Dzuy Nguyen
In the Bayer process where aluminium oxide is extracted from bauxite, a solid residue is generated and accumulated in enormous quantities. A typical alumina refinery may produce 10,000 tonnes per day of dry solid waste, one-third to one-half of which is fine mud, known as red mud, and the remainder is sand-sized materials. The existing disposal method of pumping the residue to settling ponds in the form of a caustic slurry of 20 to 30 percent solids by weight, causes many inherent problems such as high pumping energy consumption, rapid wear in pipelines, inefficient use of available land, and environmental pollution. These problems can be substantially reduced if coarse sands are removed from the residue and the fine red mud is disposed of as a dense slurry at 50 to 60 weight percent solids. Since concentrated mineral suspensions usually exhibit non-Newtonian characteristics, detailed knowledge of the rheology of red mud is essential for design of the pipeline transport system and assessment of energy requirements.