182 I. C. WHITE HISTORY OF PETROLEUM AND NATURAL GAS 



Jersey, on a small scale and at South Cliuchfield, Virginia, on a large 

 scale, by the International Coal Products Corporation, not only is a 

 substitute for anthracite produced from bituminous coal, as briquets, but 

 from each ton thereof 30 gallons of tarry and oily residues are derived, 

 from which 15 to 20 gallons of marketable oils can be obtained, all of 

 which are available for liquid fuel, and also two to three gallons of light 

 oil that can be stripped from the resulting gases before the latter are 

 used as a source of heat in the manufacture of the carbocoal briquets. 

 Hence, while the increasing use of liquid fuels may outstrip the produc- 

 tion of petroleum in the near future, yet with th« vast reserve that must 

 exist in the unexplored and undeveloped regions of the earth and the 



tively low temperatvu-e, 850° to 900° Fahrenheit, tlie volatile content of the coal being 

 reduced to approximately 8 per cent. The result of this primary distillation is a large 

 yield of tar, gas of a high thermal value, and a product rich in carbon, called "semi- 

 carbocoal." 



The characteristic feature of the primary distillation is that it is continuous, and that 

 the coal is constantly agitated and mixed during the entire operation. This is accom- 

 plished by a twin set of paddles, each revolving slowly, in opposite directions, and so 

 pitched as to advance the charge through the retort. By this means all portions of the 

 charge are uniformly distilled, and by controlling the speed at which the charge moves 

 through the retort the distillation may be carried to any desired stage. Due to the low 

 temperature of distillation and to the partial carbonization in the primary ovens, the 

 hard metallic cells characteristic of coke are avoided. The period of this distillation is 

 from two to three hours, and each retort has a carbonizing capacity of 24 tons or more 

 of raw coal per day. 



Briquetting. — The semi-cai-bocoal, after being discharged through the primary retort, 

 is ground and mixed with a certain proportion of pitch, obtained from the tar recovered 

 in the process, and this mixture is briquetted. 



Secondary distillation. — The briquets coming from the briquetting plant, which are 

 termed "raw briquets," are delivered to the secondary retorts, where they are subjected 

 to an additional distilla.tion at a higher temperature, approximately 1,800° Fahrenheit, 

 resulting in the production of '"carbocoal," the recovery of additional tar and gas, and a 

 substantial yield of ammonium sulphate. 



In the secondary distillation, pitch as a separate ingredient of the raw briquet disap- 

 pears. There is a marked shrinkage in the volume of the briquet, with a corresponding 

 increase in density, but no distortion of its shape. This distillation requires about six 

 hours and is performed in an incline retort, using gravity charge and discharge. The 

 capacity of these retorts is approximately 60 tons of raw briquets per day. 



The "carbocoal," which is the final product, represents approximately 70 per cent of 

 the weight of the raw coal, the exact percentage depending on the volatile content of 

 the coal. 



The process is self-contained — that is, it produces sufficient gas and in most cases an 

 excess over and above that required for carbonizing purposes. 



PRODUCTS FROM PROCESS 



From careful measurements made with Pittsburgh and Clinchfleld coals containing ap- 

 proximately 35 per cent volatile matter, and confirmed by numerous tests of other coals 

 containing a similar percentage of volatile matter, the following average yields from one 

 net ton of coal have been obtained : 



65 to 70 per cent of carbocoal briquets. 



15 to 20 gallons of tar oil products. 



20 pounds of sulphate of ammonia. 



2,000 cubic feet of surplus gas (550 B. T. U.). 



