Development of equipment for thickening bauxite pulp under pressure

Abstract

A new technology has been developed for the multi-stage leaching of bauxite. The method reduces unit heat consumption in the Bayer cycle by 10-12% compared to the traditional one-stage scheme. The key piece of equipment needed to realize the method is a unit that can separate the solid and liquid phases under pressure and operate at high temperatures. Thus, it was decided to design such a unit to thicken bauxite pulp under pressure. Having this type of equipment available would solve a whole range of problems, including eliminating the hydrolysis of aluminate solutions and allowing operations to proceed at high temperatures, i.e., making it possible to send partially leached pulp on to the next leaching stage without a loss of heat. The nonstandard design problem that has to be solved to be able to build such equipment was solved using a step-by-step approach: the first step was to build a large laboratory pressure-thickening unit and determine the parameters of the process under laboratory conditions; the second step entailed constructing a three-dimensional hydrodynamic model that could be used to build a specimen suitable for factory tests. Data obtained from these tests would then be used to validate the hydrodynamic model, which would in turn make it possible to choose the best of several variants for modernizing the existing leaching equipment without having to make a large capital investment.