MANUFACTURING THE CONCENTRATED SALTS 4QI ' 



dustries. 3 A most important feature of the refining is the re- 

 duction in weight by rejecting useless constituents of the salts, 

 thus securing the valuable potash in a small bulk an essential 

 consideration for the man who pays the freight or handles the 

 products. Yet to refine closely is an expensive process, and 

 much study and great care are necessary to balance properly the 

 amount of concentration against the diverse uses and the cost of 

 shipping and handling the various materials. In estimating the 

 quantity of potash in the different products, chemists are accus- 

 tomed to make use of the term "actual potash," that is, potas- 

 sium oxid (K 2 O). The object of this is to establish a basis of 

 comparison of all potash salts ; therefore, when "potash" is named 

 in potash products, it is understood that the word refers to the 

 amount of actual potash present, and not the quantity of sulfate 

 or chlorid of potash, as the case may be. As a matter of fact, 

 potash is not sold commonly in the form of "actual potash" 

 (K 2 O), but as sulfate of potash, muriate (chlorid) of potash, 

 sulfate of potash-magnesia, etc. Sulfate of potash is simply actual 

 potash combined with sulfuric acid ; and muriate of potash, actual 

 potash combined with muriatic (hydrochloric) acid. 



In manufacturing muriate of potash from the crude minerals 

 found in the Stassfurt mines, all lime, soda, magnesia and other 

 salts are removed. Crude carnallit, as it comes from the mines, 

 contains on an average 1 5 per cent, muriate of potash ; the manu- 

 facturing process consists in separating this 15 per cent, from 

 the 85 per cent, of other crude ores, and makes use of the chemical 

 knowledge that these other salts are either more soluble or less 

 soluble in water and other solutions than pure muriate of potash. 

 The coarsely ground carnallit is "charged" into a large dissolv- 

 ing vat containing a boiling, saturated solution of magnesium 

 chlorid ( a by-product of the process, as shown below). The 

 mixture is agitated thoroughly by means of a "blow-up," or live 

 steam jet, and is boiled until it shows a degree of concentration 

 equal to 32 Beaume. The contents are drawn off into 

 settling tanks, from which the clear solution is run into crystal- 

 lizing vats and left three or four days to cool and crystallize, 



3 German Kali Works, The Stassfurt Industry, 1902 : 29. 



