Tests with new flocculant for red mud decanting in alunorte

Abstract

To produce alumina with high quality, competitive costs and high efficiency on caustic recover with low flocculant consumption has been a challenge for the filtration area in Alunorte. This area has 3 chains each with 5 washers for 7 production lines where together, handles about 4,4 Mtpy of red mud. Specifically at production lines 6 & 7, the washer chain has only high rate settlers and apart from that, they receive bauxite from Mineração Bauxita de Paragominas. The combination of these two aspects results on lower density in the settler underflows. One of the actions to increase underflow solids content was to replace the conventional polyacrylate flocculant by another one which could be capable to increase the density in the washer underflows. Among other trials were gotten good results from the use of FLOMIN OL 99 polymer in lab tests as well as in the plant. The discussion of these results is the main propose of this paper.