ChocalaPedia: vacuum filters

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Sources of Sugar : 
 
The chief sources of sugar ( sucrose ) are the sugar cane and sugar beet. A brief outline of the processes of extraction and refinement of sugar from the cane is consonant with the objective of this treatise, but cannot possibly do justice to the incessant vigilance exercised by the producers and refiners to maintain the highest attainable standard of quality of the product. 
 
 
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Cane or Beet sugar 
To the chemist the term "sugar" can describe a wide range of substances. However the sugar confectioner tends to be more restrictive in his usage and uses "sugar" to describe the product extracted from sugar cane or sugar beet. 
 
This material is a carbohydrate known chemically as "sucrose". The product used in confectionery manufacture is in a very high state of purity. 
 
 
 
Descriptions contained in this blog use either "sucrose" or "cane or beet sugar" as appropriate to the text. Cane sugar contains a small amount of harmless natural impurities but still under one part in 500. 
 
sucrose refers to pure sugar which contains no impurity in its quoted value. Brown sugar in its various forms-contains a high proportion of sucrose - small quantities of other carbohydrates together with other natural impurities and possibly added colour. 
 
 
 
Extraction of Sugar from Cane : 
Sugar cane contains approximately 11-15 per cent. sucrose. 
The cane is torn and shredded by crushers preparatory to the removal of the juice. The juice is extracted by passing the crushed cane through a series of mills, each of which consists of triple, grooved rolls that exert a heavy pressure on the mass, to which water and weak juices are added to assist maceration and expression. 
 
This process extracts 95 per cent of the sugar bearing juice from the cane, the resultant bagasse and spent cane is either burned as fuel or used to manufacture insulating material. 
 
 
Clarification : 
 
The expressed juice is screened to remove floating impurities, and treated with lime to coagulate part of the colloidal matter, precipitate some of the impurities and change the pH value. 
 
Phosphoric acid may be added, since juices which do not contain a small amount of phosphates do not clarify well. If acid is added, an excess of line is added to maintain a standard pH. 
 
The mixture is heated by high pressure steam and settled in large tanks called clarifiers. To recover the sugar from the precipitated muds, continuous rotary drum vacuum filters or frame filter presses used. 
 
 
Evaporation : 
 
The filtrate, a clarified juice of high lime content, contains about 85 per cent water. It is evaporated to approximately 40 per cent water in triple or quadruple effect evaporators. 
The resultant dark brown, viscous liquid is concentrated and crystallised in a single-effect vacuum pan. 
 
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Sources of Sugar, Extraction of Sugar from Cane, Clarification

Sources of Sugar : The chief sources of sugar ( sucrose ) are the sugar cane and sugar beet. A brief outline of the processes of extracti...