Caustic soda is the most widely used chemical for cleaning sugar mill evaporators inudAustralia. It is partially effective in removing silica, silicates, proteins, polysaccharidesudand organic matter, but is ineffective when the major components of scale consist ofudcalcium phosphate, calcium oxalate, calcium magnesium aconitate, calcium sulphate,udcalcium carbonate and potassium calcium sulphate. In such situations, sulphamic acid isudtypically used. Some mills have found these normal procedures unsatisfactory and haveudused alternative but expensive cleaning methods, which have proved effective. However,udthese mills still use caustic soda and sulphamic acid in combination with the alternativeudmethods to clean evaporators resulting in a time consuming and laborious process. Thisudpaper describes the effect of caustic soda solution in the presence of additives toudsolubilise different scale types. The paper also describes attempts to identify foamudcomponents in scale and provides results on the efficacy of defoamers.
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