Patent GB-689752-A (GB)
Title: A method for refining diffusion juice or other colloidal liquids occurring in the production of sugar
Inventor: MULLER ARNE VIGAND BRIEGHEL
IPC: C13B20/06
Filed: 1950-09-08
Abstract: 689,752. Purifying saccharine liquids. AKTIESELSKABET DE DANSKE SUKKERFABRIKKER. Sept. 8, 1950, No. 22234/50. Class 127. A process for refining diffusion juice or other colloidal liquids obtained in the production of sugar, e.g. waste water from leached beet cuts comprises subjecting the said liquid to stabilisation by adding thereto a lime composition of which the alkalinity does not exceed 0.15 per cent CaO to bring the alkalinity of the liquid to within the range 0.01 to 0.05 per cent CaO, preferably 0.02 per cent CaO, and thereafter subjecting the liquid to continuous defeco-carbonation or to pre-liming in the presence of calcium carbonate, followed by liming and first and second carbonations. As shown in Fig. 1 the incoming diffusion juice is mixed in a container 1, provided with a stirrer 2, with a corresponding amount of carbonated juice which has been limed with lime milk to an alkalinity of about 0.15 per cent CaO, in a container 8 fitted with a stirrer 10. The mixture of diffusion juice and carbonated juice with addition of lime is pumped by a pump 4 from the container through a float valve 3 and a pre-heater 5 to the carbonation chamber 6 in which it is carbonated with addition of carbonated juice which has been limed with lime milk in the container 8. A pump 7 sends part of the carbonated juice back to the container 8 through a float valve 9 while the remaining amount of carbonated juice passes through an overflow 11 for further treatment by filtration and second carbonation. As shown in Fig. 2 the stabilisation, the liming, and the carbonation take place in one and the same container, which is provided with partition walls 12 in which there are adjustable shutters 13. The juice level in the system is controlled by an adjustable overflow 14, and the incoming diffusion juice passes the system in the main direction indicated in the drawing by the arrow 15. By means of a stirring device 16 a turbulent current is brought about, an inner circulation being thereby obtained among the chambers limited by the partition walls, the extent of which may be adjusted as desired by means of the shutters, or by a change in the speed of the stirring device. The system is kept heated at a desired temperature by circulating the liquid from the last liming chamber through the pre-heating system 17 by means of the pump 19. From the liming chambers the stabilised and pre-limed juice passes into the carbonation chamber, where it is carbonated by carbon dioxide, e.g. lime-kiln gas, provided through the distributer 20, the carbonation juice thereafter leaving the carbonation chamber through the adjustable overflow 14. From the overflow the juice passes through the thickening device 18, the clarified part of it leaving the upper outlet to be subjected to further treatment by filtration and second carbonation. Finally the residual compound leaving the bottom outlet of the thickening device 18 may be conducted either to the rotary filter 23 passing through the pump 21 and valve 22 or, if desired part of it may, by means of the pump 24 and valve 25, be supplied to the first chamber of the liming apparatus to supplement the calcium carbonate sludge available in the carbonated juice led back in the container, i.e. the addition of sludge from the bottom of the thickening device 18 should supplement the sludge which owing to the position of the shutter and the rotation of the stirring device, is led back inside the container against the direction of the main flow indicated by the arrow 15.