PHOSPHATE ROCK: UTILIZATION AS FERTILIZER. 14 
PROCESSES DEALING WITH THE PRODUCTION OF TWO OR MORE 
FERTILIZER ELEMENTS. 
At first glance these methods appear particularly attractive from an 
economic standpoint, because two or more salable products are 
obtained by a single operation.. Two of the seemingly very promising 
processes, however, on being tested in the laboratory proved to be 
commercially impracticable. A complete list of the processes under 
this head is given in Table VIII, Appendix. 
The processes of Bickell' and Klett * deal with the production of 
soluble phosphoric acid and potash from phosphate rock and feldspar. 
Bickell’s process consists in heating in a reverberatory furnace to 
a light redness for two hours an intimate mixture of 1 part feldspar, 
0.5 part phosphate rock, and 3 or 4 parts of lime. It is claimed that 
both phosphoric acid and potash in available forms are obtained by 
this treatment. 
On testing this process in the laboratory it was found that Bickell’s 
claim was not substantiated, for over 44 per cent of the potash 
present in the mixture was volatilized upon ignition, and of that 
which remained in the residue only 9 per cent was water-soluble. 
While none of the phosphoric acid was volatilized, less than 39 per 
cent of it was soluble in a 2 per cent solution of citric acid. 
Klett’s process is similar to that of Bickell and consists in heating 
to redness for five hours an intimate mixture of 2 parts carbonate of 
lime, 1 part phosphate rock, and adding for each part of potash (K,O) 
in the feldspar 2 parts of calcium fluoride. It is claimed that a 
soluble silicate of lime and potassium phosphate are thus obtained. 
In view of the fact that the percentage of potash in the mixture is 
relatively small and that the time of heating is very long, it is hardly 
likely that the value of the product would cover the cost of manufac- 
ture. Moreover, the claim that phosphate of potash is formed in the 
operation is not justified. 
The process, however, was tried out on a laboratory scale and results 
obtained similar to those found in repeating Bickell’s method. 
Nearly all of the potash was volatilized, while less than one-half of 
the phosphoric acid present in the residue was citric-soluble. 
Both the patents of Bickell and Klett have long ago expired. 
The processes of McDougall,? Terne,t Washburn,® and Wilson and 
Haff ® all deal with the neutralization of the acid in superphosphate 
by means of ammonia, producing thereby a mixture of gypsum, 
ammonium sulphate, and calcium ammonium phosphate. These 
1 United States Patent No. 16111 (1856). 
2 United States Patent No. 49891 (1865). 
3 United States Patent No. 135995 (1873). 
4 United States Patent No. 709185 (1902). 
5 United States Patent No. 1100638 (1914). 
6 United States Patents Nos. 1062869 (1913); 1112183 (1914); 1122183 (1914). 
6819°—Bull. 312—15——3 
