Austrian experiences with sugar manufacture from nonpurified beet juices

Because of the articles dealing with sugar manufacture from nonpurified raw juice, published until recently, we will present the experiences made on this subject in Austria which were for the time being published only in part. Part one gives the results obtained from a project of a combined production of white sugar and ethanol. The idea was to concentrate raw juice followed by crystallisation (Evaporation crystallisation). The runoff of this crystallisation step was intended for alcohol production, whereas the sugar was processed to white sugar (melted liquor purification, multistep crystallisation). Concentrating of raw juice was initially impeded by scale formation on the evaporator tubes (deterioration of k-value). The situation could be improved by the addition of small amounts of soluble Ca-salts. The “raw juice sugar” obtained from the concentrate showed purities of 97-98%, but was turbid. Liming and carbonatation of the dissolved sugar gave melted liquors from which in three steps white sugar could be crystallised. The filtrability after liming and carbonatation depended largely on the quality of the “raw juice sugar”. Additional experiences with the workup of nonpurified beet juices were gathered in the production of “Vollzucker”. The problem of encrustation on concentrating was overcome by employing a special evaporator type – a metallic particle fluidized bed evaporator with flash evaporation. The syrup thus obtained has a shelf life of years, provided a certain dry substance range is kept and the headspace is filled with protective gas. A free flowing product can be obtained by means of spray drying, but in this case the content of glucose and fructose must not exceed certain limits. Even though an optimum separation of pulp particles and turbid material by separator was intended due to quality requirements, no totally blank concentrates were obtained. This held also true for a trial lot of sugar, obtained by evaporation crystallisation of the aforementioned concentrates.