CHAPTER XIII. 



THE CLARIFICATION Oil DEFECATION OF THE JUICE. 



The object of clarification is to remove from the juice, as far as possible, 

 all bodies other than sugar, to obtain a juice permitting of easy filtration and 

 working in the pans and centrifugals, and when making sugars intended for 

 direct consumption, to obtain a bright, light-coloured, transparent juice. 



In rough outline, the processes in use are as below : 



1. The juice is raised to a temperature of about 190 F. to 200 F. by 

 being passed through a juice heater (see below} ; it is then received into tanks 

 of 500 gallons' capacity and upwards, where it is allowed to settle for varying 

 times dependent upon the capacity of the clarifiers in relation to volume of 

 juice ; after half-an-hour's settling a fairly clear juice can be drawn off above 

 a deposit of dirt and precipitated matter ; this juice is sufficiently clarified to 

 be passed direct to the evaporators when dark crystals are being made. 



2. The fairly clear juice obtained as in 1 is passed on to vessels known 

 as eliminators ; these are rectangular tanks of depth from 3 to 3 feet, and 

 about 8 feet by 6 feet in length and breadth ; at the bottom is placed a 

 trunnion pipe into which are fitted brass or copper tubes through which steam 

 is passed for the purpose of heating the juice. An allowance of 1 square foot 

 heating surface for every 3 to 4 gallons capacity is usually found. Round 

 the top edge of the tank is arranged a gutter ; the juice is boiled in these 

 tanks with the object of bringing the suspended impurities to the surface, 

 whence they are brushed into the gutter and passed on to the filter presses ; 

 very clear juices can be obtained by this method, which is however most 

 wasteful of steam. 



3. The juice, either after passing through the juice heater, or when cold, 

 is received into tanks provided with a heating surface similar to the one 

 described in 2 ; the heating surface sometimes takes the form of a coil, or 

 the tank may have a steam jacket. The juice is kept in these tanks at a 

 temperature of about 205 F. ; at this temperature the heavier particles of dirt 

 subside, and a lighter aerated scum rises to the surface ; between these layers 

 is the bulk of the juice, clear and transparent. Many factories in Mauritius 

 make high-class, white, consumption sugars with these clarifiers alone. 



4. Any of the above processes may be used, followed by a bulk filtration 

 of the juice. 



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