THE DEVELOPMENT OF A NEW BAYER PROCESS THAT REDUCES THE DESILICATION LOSS OF SODA BY 50% COMPARED TO THE CONVENTIONAL PROCESS
Harato, T., Ishida, T., Kato, H., Inami, M., Ishibashi, K., Kumagae, and Murakami, M.
At Sumitomo we have developed a new Bayer process (SNBP) that in comparison to the conventional Bayer process reduces the desilication loss of soda by more than 50%. This new process is applicable to gibbsitic bauxite. It consists of four key unit operations:
- Two stream heating and a tubular digestion system: alumina is fully extracted from bauxite, but less than half of reactive silica is extracted by the digestion system
- A high rate settler: digested slurry is separated in a few minutes under pressure
- Seeded post-desilication: desilication of pregnant liquor is performed
- High rate washers: bauxite residue is washed by counter current decantation
We have operated the SNBP at our Ehime (Kikumoto) Works since the end of 1993 at a plant capacity of 600 tons per day using Bintan (Indonesia) and Gove (Australia) bauxites.