[stansfield-gilmore] carbonization OF LIGNITES 99 



see the advantage of the recently devised process of adding the neces- 

 sary binder, which will fill the pores of the carbonized material, and 

 then briquetting the whole before it is exposed to the air. 



Carbonization in a current of steam was tried as a possible 

 economical substitute for vacuum carbonization, in case the latter 

 was found to be advantageous; the primary physical effect, which 

 is the reduction of the partial pressures of the volatile products 

 (except steam), being the same in each case. The use of steam 

 would also have the advantage of driving the air from the retort at 

 the beginning, and of helping to equalize the temperature throughout 

 the charge. The results obtained, however, show that steam could 

 not satisfactorily be passed through the retort where the temperature 

 was over 450°C. Furthermore, the results discussed above, in 

 connection with the steam and pressure series, indicate the advisability 

 of either subjecting the lignite to a preliminary drying before it is 

 carbonized, or of withdrawing the steam and other gaseous products 

 from the retort as fast as they are formed. 



The supply of a suitable binder is probably the most serious 

 economic difficulty in any process for the utilization of lignite, and it 

 was in consideration of this problem that the pressure series was run. 

 One process is to carbonize the lignite in such a way as to obtain the 

 most valuable yield of by-products, the residue then being briquetted 

 with the addition of the necessary binder. Another possible process 

 is to carbonize the lignite in such a way as to necessitate the least 

 possible addition of a binder for briquetting; the by-products, in 

 contradistinction to the above, being given only secondary consider- 

 ation. It was thought that vacuum carbonization would give the 

 most valuable by-products, but that carbonization under pressure 

 might cause a breaking down of the volatile matter in the lignite in 

 such a way as to leave pitchy material in the residue, which would 

 therefore require the addition of less binder than usual for briquetting. 

 It should be noted that in every case some pitch suitable for a binder 

 could doubtless be obtained by distillation of the tar, but it is not 

 anticipated that this will be sufficient in any case for briquetting all 

 the residue obtained. The experiments so far carried out did not 

 cover determination of any binding material present in the residue; 

 but the results obtained showed that a residue of unusually high 

 calorific value was produced, if the lignite was given a preliminary 

 drying. Very few Canadian coals, as mined, have as high calorific 

 value as the residue from pressure carbonization at about 550°C. 



In conclusion, it may be stated that although all the above 

 experiments were carried out on one coal, a few preliminary experiments 

 in the regular series were carried out with a sample of coal from 



