FILTERABILITY OF RAW SUGARS - LABORATORY TESTS VERSUS REFINERY PERFORMANCE

The filterability of a raw sugar is one of its key quality parameters, and it has an important effect on refining. As yet we do not have a recognised method of measuring this property in a way that represents filtration performance in a refinery. A study has been carried out on the filtration characteristics of a number of raw sugars received at Tate & Lyle's Thames Refinery. The filterability of the affined raw sugars has been measured using a method that is a modification to the Nicholsen Horseley filtration test. These modifications are described. The filtration test has been carried out on both affined raw sugar, and on the melter liquor produced from that raw. A similar filtration test was also carried out on the carbonatation liquor, and all three were compared. Thus filtration characteristics of the raw sugars, and the ways that they behave in the refinery have been studied. The applicability of the test for a carbonatation refinery is discussed. The test will measure filtration problems caused by suspended solids, but will not indicate whether there will be problems due to starch. Starch will not cause a filtration problem in the test method, but will upset carbonatation, hence causing a filtration problem.