ENZYMATIC PROCESS FOR DEXTRAN PRODUCTION AND UTILIZATION IN THE BAYER PROCESS

The utilization of biopolymers in industrial processes is gaining significant attention due to their eco-friendly nature and potential for sustainable development. Traditionally, dextran, a biopolymer is applied to the Bayer process as a flocculant for the recovery of the fines of alumina hydrate after crystallization, minimizing this way, the alumina hydrate content of the Bayer liquor stream returning to digest the bauxite.
This paper highlights the successful scale-up of an innovative enzymatic approach to produce dextran for the Bayer process, ensuring a sustainable and eco-friendly alumina production on an industrial scale. The objective was to improve the properties of the existing Dextran solution, based on fermentation technology, by introducing a second-generation process. The new process was developed at the laboratory scale in a collaboration between SNF and academic partners and has now been successfully implemented for the manufacturing of dextran at industrial scale.
The enzymatic method involves the use of specific enzymes to selectively produce the right quality of dextran for better applicative performance. It also eliminates the need for solvent-based fractionation, thus minimizing VOC emissions and reducing the environmental impact associated with traditional approaches. We will describe the process development at laboratory scale, the scale-up to pilot scale and to industrial scale and the applicative performance of the new product Flomin ALX NGP.
The successful implementation of this innovative process at industrial and commercial scale opens the path for the investigation of potential other utilizations of dextran in the Bayer process by specifically targeting the right quality of dextran for each specific application.