Research the slurry thickening efficiency of aluminum companies in Vietnam using experimental settling column system

Abstract

The thickening is the process of increasing the solid fraction in the slurry. The purpose of the process is to obtain a thicker sludge product and to obtain an overflow product with a minimum solid amount. The equipment used are traction thickener, cable thickener, caisson thickener, tray thickener, E-Cat thickener, lamella thickener, etc. This stage plays an essential role and greatly affects operations in mineral beneficiation factories. However, this is a problem for Aluminum companies in Vietnam because the amount of particles passing 1 mm is significantly higher than the design, leading to the overloading of thickeners. The overall productivity of the factories was affected and seriously reduced due to not being able to ensure the amount of feeding coarse particles and having to stop the operation to fix the problem. The requirement is to find and apply advanced technologies to improve the sedimentation process. This article presents the characteristics of bauxite slurry in Daknong and Lamdong companies. The amount of fine particles passing 0.02 mm reaches more than 62% (in the case of Daknong) and 72% (in the case of Lamdong) with the main minerals (gibbsite, goethite, kaolinite, ilmenite, etc.). On that basis, the survey was implemented to define the optimal type of flocculant aids (NALCO 85035 and HA - LB 080), flocculant dosage (40 grams/tons), and pH of the sludge (6.5 – 7). The obtained underflow product has a solid phase concentration of over 35% and the overflow has an amount of solid/water of less than 100 mg/l. Research was conducted on an experimental settling column system and it was recommended to pre-test a Lamella high-performance thickener for further research.