No abstract

Distributing the red-sludge flow between paralleled thickeners is a relevant problem for controlling the process of thickening and washing the alumina sludge. Sludge sticks to thickener walls and rakes in operation, which reduces the effective volume of the machine and puts a greater strain on the rakes; raising the rakes is necessary to avoid breaking the stirrer, but this reduces the compacting rate of the thickened product. Redistributing the feed pulp between thickeners over the course of their gradual uneven contamination might solve the problem of the thickened product being under-compacted in the thickening-washing line. There are patents that address this issue; however, they only describe semiautomatic approaches. The problem has been covered to a great extent by Russian scientists and engineers such as M V Levin, T B Potapova, V V Aleksandrov, T G Milberger, P F Minin, I M Fain, R M Khamidov, as well as by the following institutions: All-Union Research and Development Institute of Aluminum, Magnesium, and Electrode Industries, Pikalevo Alumina Plant, Pavlodar Aluminum Plant. The paper describes the algorithm of an artificial immune system for redistributing the red-sludge flow in alumina production between paralleled thickeners.

The paper evaluates the behavior of a red-mud solid fraction in a thickener feeder cup, aiming to identify the main characteristics of particle distribution in the flocculation zone and to determine the dependencies affecting the further process taking place in the particle-free sedimentation zone in the thickener-thickening unit. This work used mathematical and numerical modeling to study the influence of such parameters as the flow rate of the feed pulp in the thickener, the flow rate of the flocculant, the density of pulp at the inlet to the unit, and the viscosity and temperature of the pulp on the particle-size distribution from under the feeder cup. The results and dependencies obtained are intended to be used as nominal values in the red-mud thickening process performed on a lab-scale unit.