THE CARBONATION PROCESS. 



Review Of Process. The essential question with regard to any new 

 process is whether a return is given on invested capital. An estimate of 

 necessary working expenses for a factory working 1000 tons of cane per day 

 over a crop of 100 days is given below. 



The necessary extra plant over and above that needful for the ordinary 

 defecation process will include a limekiln, gas washer, and carbonic acid gas 

 pump ; and the carbonating tanks simply replace the clarifiers and eliminators 

 used in the defecation process. 



The cost of these may be estimated as : limekiln, 3500 ; gas washer, 

 150 ; carbonic acid pump, 600 ; a total cost of 4250. 



The extra current expenses for a crop of 100,000 tons will include pur- 

 chase of limestone sufficient to give 1500 tons of lime, for which would be 

 required 2678 tons pure limestone, or, say, 2900 tons actual crude material. 

 In certain instances, such as in Mauritius, estates near the seaboard could 

 lay the coral reefs under contribution, and obtain limestone at the factory at 

 a cost of 2s. to 3s. per ton. Then the lowest cost of the limestone would be 

 435, but in other cases, such as in Dernerara, the cost of transporting lime- 

 stone would be prohibitive. 



In general, in beet sugar factories eight pounds of coke are required per 

 hundred pounds of limestone ; wood in tropical countries is as a rule cheaper 

 than coke, and, taking the relative calorific value of wood to coke as 1 : 3, 

 twenty-four pounds of wood will be required per hundred pounds of limestone, 

 thus for the 2900 tons of limestone 696 tons of wood ; in very favourably 

 situated estates wood can be obtained at the factory at a cost of 6s. per ton, 

 giving the cost of fuel as 208 16s. 



The extra labour in working the kiln may be put at five men per shift, 

 and for the hundred days' campaign will cost 60. 



The large quantity of water used with the milk of lime requires addi- 

 tional expense in evaporation ; if the 1500 tons lime be employed at a density of 

 20 Brix approximately 6000 tons of water are also added. Allowing at the 

 triple effect one pound of coal to evaporate twenty pounds water, 300 tons of 

 coal will be required, which, at 25s. per ton (a price frequently reached in the 

 tropics), will cost 375. 



The total extra cost, then, allowing 10 per cent, interest and depreciation 

 on invested capital, will be for the 100,000 tons of cane 1508 16s., or 3-621 

 pence per ton of cane, and allowing a 10 per cent, recovery on the canes, 

 3s. per ton of sugar ; and this is an estimate made for circumstances more 

 favourable than would generally be the case. 



To counterbalance this extra cost the value of the crop must be increased, 

 and an increase can only be looked for on the score of quality, as the figures 

 published by the West Java Experiment Station show conclusively that no- 

 greater extraction is obtained by this process. 



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