How Beet Sugar is Made - Pressing
The spent slices are de-sweetened in large screw presses where a variable pitch screw pushes the pulp at ever increasing pressure through a perforated, usually conical tube. The juice flows away and the pressed pulp, at around 70% moisture content, discharges from the end of the tube. Molasses is often added to the pressed pulp before drying in order to provide a higher sugar content animal feed. Typically 2 tons of pressed pulp and 0.4 tons of molasses are dried to make 1 ton of dried pulp at 10% moisture content. The dried pulp is then extruded into pellets to increase the density of the product and make it easier to store and handle.
The drying process is energy intensive, using about 1/3 of the total factory fuel consumption. Generally driers are large rotating drums with air at 600 to 900 °C used to drive the water out of the pulp. Some new driers use steam so that the water driven off can be used as heat in the sugar manufacturing process.