Abstract to SPRI Conference, 2006

The options and prospects for the direct production of white sugar in a cane sugar mill are reviewed. Plantation white sugar has been made for many years in some countries but cannot meet the requirements for refined sugars. These low colour sugars are now a popular quality raw sugar for the increasing number of destination refineries. Attainment of refined sugar standards needs the application of some or all of the new separation technologies such as membrane separation, the use of adsorbents, and chromatographic separation. Only one of the new processes being proposed is close to commercialization, namely the WSM process developed by Tongaat Hulett Sugar. A new process for the production of white sugar in a cane sugar mill developed at the Audubon Sugar Institute is described in some detail. It does not require membrane separation and involves adsorption of colour and other impurities using granular activated carbon and ion exchange resins. Chemical regeneration of the carbon is utilized, which enhances the attractiveness of the process. Preliminary information is given on a possible full-scale installation in a raw sugar mill. Introduction Some significant trends are evident in the world sugar market. In the 1980s the proportion of white sugar traded on the world markets, both beet and cane showed a clear increase relative to the raw sugar (Clarke 1986). More recently, the trend has changed, since a number of new large refineries have been built and white sugar exports from producing countries, particularly from the EU, have reduced. Another trend evident is the swing to VHP or better raw sugar supply to refineries, and in particular an increase in deliveries of very low colour raws exemplified by Brazilian “cristal”. Todd (1997) has shown that the average cost of production of refining in attached refineries is about 55 % of the cost in stand-alone refineries. In order to compete, autonomous refineries have to be larger to achieve economies of scale and lower unit production costs. A further trend evident in the US has been the increase in vertical integration from field to white sugar output. All beet sugar factories in the US are now owned by the growers, and many large raw cane sugar producers have invested in refining, both white-end refineries and in existing or new refinery capacity. The first new stand-alone refinery to be build for 25 years was constructed in 1990 in Dubai. Since that time, over a dozen new refineries have been built and existing refineries have been expanded. Currently a number of new refineries are being built or are planned in areas such as Bangladesh, Egypt, Syria, India, Louisiana and Israel among others.