THE PREPARATION OF CORN" OIL. 



19 



pounds 9 of corn oil containing 1.76 per cent of free fatty acids, and a 

 comparison of these estimates for both methods is presented in 

 Table 10. 



TREATMENT WITH CAUSTIC. 



The difference in cost of chemicals and value of oil lost in the two 

 methods is 0.064 cent per pound of refined oil in favor of method 2. 

 This slightly lower cost of method 2 is due to the lower refining loss 

 of oil and the slightly greater value of the soapstock, although the 

 cost of the chemicals is higher than in method 1. 



Since both methods were found to give a good quality of oil and 

 since the difference in cost is not considerable, there would appear 

 to be little, if any, advantage of one method over the other. As has 

 been previously stated, however, method 2 does not require the 

 washing of the oil with brine to remove the traces of soap, and this 

 is a distinct advantage, especially from the standpoint of the time 

 involved. On the other hand, this method calls for special handling 

 of the soapstock in order to reduce the refining loss to the figure 

 given in Table 10. In this respect method 1 has the advantage. It 

 would appear, therefore, that the two methods are practically of 

 equal value as to the ease of operation and cost. 



BLEACHING. 



In commercial practice it is generally assumed that the bleaching 

 of vegetable oils with fuller's earth results in a loss of oil equivalent 

 to 20 per cent of the weight of earth used. On this basis, the cost 

 of the bleaching operation on the quantity of oil under discussion as 

 regards the cost of earth and the value of the oil lost would be as 

 shown in Table 11. 



Table 11. — Cost of material used and value of the oil lost in bleaching corn oil with 



fuller's earth. 



Items of comparison . 



Method 1. 



Method 2. 



Weight of oil to be bleached pounds. 



Quantity of fuller's earth required (5 per cent) « do. . . 



Loss of oil by treatment (20 per cent of weight of fuller's earth) do. . . 



Cost of fuller's earth (2J cents a pound) 



Cost of oil lost (10.5 cents a pound) b 



23, 487 



1, 174. 3 



234.8 



23, 640 

 1,182 

 236.4 



$26. 42 

 24.65 



24.82 



Total. 



51.07 



51.41 



Cost of above items per pound of crude oil cent. 



Cost of above items per pound of "bleached oil do.. . 



0.204 

 .22 



0.206 

 .22 



« This is a greater percentage of fuller's earth than is used for most vegetable oils, but commercial practice 

 and laboratory tests appear to agree that such a quantity is necessary in the case of corn oil. 

 b This figure represents the cost of crude oil plus the approximate cost of the treatment with caustic. 



9 The refining equipment described in this bulletin is designed to handle 50,000 pounds of oil a week. 

 This quantity of oil would be produced in a hominy plant milling from 15,000 to 18,000 bushels of corn daily. 

 In a starch plant, which produces at least twice as much oil from the same quantity of corn, the refinery 

 would need to be proportionately larger. 



