AN INSTRUMENT TO ANALYZE AND IMPROVE RED MUD FLOCCULATION
Doucet, J., Ferland, P.A. and Tremblay, L.
Alcan International Limited has developed a settling apparatus to study the flocculation and the sedimentation of red mud in a dynamic and continuous flow. The instrument permits the qualitative evaluation of the flocculation as well as a quantitative determination of the required dosage of flocculant at various volumetric and solids throughputs. Originally designed for research purposes, the instrument has found broader application in a few Alcan alumina refineries and in particular for the troubleshooting and the improvement of the performance of the mud washing circuit. Training of plant personnel, process control and equipment optimization are major tasks accomplished with this new apparatus.
This paper describes the instrument and focuses on the method used to study the critical parameters that rule the flocculation and the sedimentation of red mud. Because of its unique configuration, the effect of multiple addition of flocculant, variable feed flow rate and slurry concentration, all inaccessible with standard jar tests, can be evaluated within hydrodynamic conditions that match the real process. The results of few case studies based on real processes are reported in detail in the paper.