18 



BULLETIN 1010, TJ. S. DEPARTMENT OF AGRICULTURE. 



ESTIMATED TOTAL COST OF REFINING CORN OIL. 



The cost of refining vegetable oils includes such items as cost of 

 chemicals, value of the oil lost in the several processes, fuel, labor, and 

 overhead. In a relatively small refining operation, such as is here 

 described, it is quite impossible to allocate the fuel, labor, and over- 

 head expenses to the several operations. Accordingly, these items 

 are charged in an estimated over-all cost of producing the finished 

 edible oil. The cost of the chemicals used and the value of the oil 

 lost are, however, highly specific to the several operations and can be 

 charged thereto with a fair degree of accuracy. 



Table 10. — Cost of chemicals used and value of oil lost in treating 25,000 pounds of 

 corn oil, containing 1.76 per cent of free fatty acids, by methods 1 and 2. 



Items of comparison. 



Method 1 



Method 2. 



Weight of oil pounds . 



Weight of free fatty acids (1.76 per cent) do... 



Sodium hydroxid necessary to neutralize the free fatty acids ; .do. . . 



Total sodium hydroxid necessary do. . . 



Soda ash required do. . . 



Cost of caustic t> 



Cost of soda ash c 



Value of oil lost in treatment, at 10 cents a pound: 



Method 1 (6.05 per cent) 



Method 2 (5.44 per cent) 



25,000 



440 



62.8 



a 163. 7 



25,000 



440 



62.8 



94.2 



500 



$8.19 



$4.71 

 10.00 



151. 25 



136. 00 



Total cost (chemicals and value of oil lost) 



Net cost (total cost, less the value of the soapstock, d $15.20 by method 1 and $17.32 by 

 method 2) 



159. 44 

 144.24 



150. 71 

 133. 39 



Net cost of chemicals used and value of oil lost per pound of crude oil cent . 



Net cost of chemicals used and value of oil lost per pound of refined oil do. . 



0.577 

 0.628 



0.533 

 0.564 



a Method 1 requires 10 per cent of 25,000 pounds, or 2,500 pounds, of 10" B6. caustic (6.55 per cent NaOH), 

 equivalent to 163.7 pounds of sodium hydroxid. 



b Caustic soda containing 76 per cent of sodium hydroxid is quoted at $3.75 per hundredweight, which 

 is equivalent to 5 cents a pound of 100 per cent sodium hydroxid, delivered. 



« Soda ash is quoted at $2 per hundredweight. 



d Soapstock is valued according to its fatty acid content. The value of soapstock for methods 1 and 2 is 

 derived asfollows: Weight of soapstock — (1) Caustic (sodium hydroxid solution), method 1, 2,500 pounds; 

 method 2, 1,000 pounds. (2) Soda ash, method 2, 500 pounds. (3) Oil lost, method 1, 1,512.5 pounds; 

 method 2, 1,360 pounds. Total, method 1, 4,012.5 pounds; method 2, 2,860 pounds. The weight of fatty 

 acids in the soapstock is calculated as follows: (1) Total weight of oil lost (oil and free acid), method 1, 

 1,512.5 pounds; method 2, 1,360 pounds. (2) Weight of free acids, method 1, 440 pounds; method 2, 440 

 pounds. (3) Weight of oil lost, method 1, 1,072.5 pounds; method 2, 920 pounds. (4) Weight of fatty 

 acids in oillost, method 1, 986.3 pounds; method 2, 846 pounds. (5) Total weight of fatty acids, (2)+(4), 

 metuod 1, 1,426.3 pounds; method 2, 1,286 pounds. (6) Total weight of soapstock, method i, 4,012.5 

 pounds; method 2, 2,860 pounds. (7) Fatty acids in soapstock, method 1, 35.5 per cent; method 2, 44.9 

 percent. Themoney value of the soapstock is calculated by the following formula: RxPXM-f-50= value 

 (dollars). In this formula R is the weight of the fatty acids(in pounds), P is the percentage of fatty acids 

 in the soapstock, and M is the market price per pound (in dollars). If soapstock containing 50 per cent 

 of fatty acids is quotedat $0,015 per pound, the value of the soapstock, ancordingto this formula bymethod 1 

 is 1,426.3X35.5X .015-7-50= $15.20. By method 2 the value is 1,286X44.9X. 015-^50= $17.32. 



CHEMICALS AND LOSS OF OIL. 



It is evident that a very good quality of oil can be produced by 

 both methods 1 and 2; hence, from this standpoint either method is 

 practicable. The choice of the methods would appear, therefore, to 

 depend upon which would be the more economical when such factors 

 as loss of oil, cost of the chemicals used, and the time involved are 

 considered. The cost of these items has been estimated on the basis 

 of the results of refining the 10-pound batches for treating 25,000 



