12 



BULLETIN 572, TJ. S. DEPARTMENT OF AGRICULTURE. 



Thus, R. J. Wysor x has shown in an investigation on the escape of 

 potash from blast furnaces that the specially designed tower spray 

 washers used for purifying the gas from the blast furnace are only 

 moderately efficient in freeing the gas from the finest dust particles, 

 and that much of the water-soluble alkalies remains in the gas 

 current after leaving the washers. This result is explained on the 

 ground that the particles of fume are in such an exceedingly fine 

 state of division that they escape contact with the relatively large 

 drops of water. 



Experiments to show the effect of variations in burning on the 

 volatilization of potash have been made recently at the plant of 

 the Security Cement and Lime Co. It was found that as the burn- 

 ing conditions were varied from normal to such a temperature as 

 to give overburned clinker, the percentage volatilization of the 

 potash increased from 31.6 per cent to 42.6 per cent. 2 



A similar result was obtained also in this laboratory in the analysis 

 of seven cement samples furnished us by the Tidewater Portland 

 Cement Co. The samples were collected successively as the burning 

 was raised from a temperature giving a very soft clinker to that 

 sufficient to make a very hard clinker. Corresponding samples of 

 raw mix were collected at the same time, giving a composite sample 

 which analyzed 0.71 per cent potash. The results obtained in the 

 analysis of the cement samples are shown in Table III. 



Table III. — Effect of variable burning on the liberation of potash in cement kilns. 



Sample. 



Potash in 

 clinker. 



Proportion 



of total 



potash 

 volatilized. ! 



Sample. 



Potash in 

 clinker. 



Proportion 

 of total 

 potash 



volatiiiied. 



No 1 a 



Per cent. 

 0.G9 



■ :S 



Per cent. 

 40.0 

 39.1 

 49.5 

 50.7 



No. 5 



Per cent. 

 0.51 



.44 

 .48 



Per cent. 

 55.6 



No 2 



No. 6 



61.7 



No 3 



No.7*> 



5S.4 



No. 4 









a Very so 



t. 



b Verv 1 



lard. 





These results show that the potash volatilized increases with the 

 temperature of burning, but the increase apparently is not sufficient 

 to attribute the great variation in the potash volatilized in different 

 plants entirely to differences in the temperature of burning. 



That it is possible also to bring about by chemical means an in- 

 crease in the amount of potash volatilized has been demonstrated 

 recently at the plant of the Security Cement and Lime Co. This 

 is effected by adding ordinary salt both to the raw mix and to the 

 coal used for fuel, and in such quantity that the total added amounts 



i Bui. Am. Inst. Mining Engineers, 121, 1 (1917). 



Anderson and Nestell. Loe. cit. 



