110 MANUFACTURE OF FERTILIZING MATERIALS 



where it deposits potassium chloride more pure 

 than that got from the crude salt. The mother 

 liquor of this salt is added to the first. As the 

 carnallite from whence it comes contains less 

 common salt than the crude salt, this mother 

 liquor yields little residual salt. The salt yielded 

 by artificial carnallite is clarified with very 

 little water, and yields very high strength potas- 

 sium chloride of about 95 to 98 per cent. 



In most factories potassium chloride is dried 

 in reverberatory furnaces. In recently erected 

 factories the drying is conducted in cylindrical 

 coil-heated tanks, in which an agitator with blades 

 revolves, followed by a roller compressor. When 

 the shaft revolves the blades turn up the salt, 

 and the roller which follows makes them into 

 a cake again, so that the surfaces are continually 

 renewed. When the drying is finished the salt 

 is run out through a chute and bagged up. In 

 a general way factories which work according 

 to the processes described above are content 

 with producing 80 per cent potassium chloride; 

 they rarely push the clarification so far as to 

 make 97 to 98 per cent product, although the 

 potassium chloride dissolved by the clarification 

 can be recovered immediately in the crystal- 

 lizers, while the mother liquor is used to dissolve 

 the crude salt. To obtain 98 per cent salt with- 

 out effort, the method of dissolving the raw 

 salts is altered. The mother liquor, the small 

 amount of clarifying liquor, and finally the 



