pH Control In Sugar Refineries

All traces of lime must be eliminated before the concentration step to prevent scale buildup in process pipes and vessels. Carbon dioxide is added to the juice to precipitate the lime as less soluble calcium carbonate, which also captures other impurities during precipitation. CO2 is usually added in several stages to avoid an unmanageable type of precipitate that can develop in single stage carbonation. At each stage of carbonation the pH is measured and an appropriate volume of CO2 is injected. By the final stage the pH should be reduced to approximately 9. After carbonation the juice is filtered to eradicate all traces of solid particles before flowing to the sulfitation tower.