THE RECOVERY OF POTASH FROM ALUNITE. 5 



good grade, and should increase considerably the supply of com- 

 mercial alunite in sight. 



Another important deposit occurs between 4 and 7 miles north 

 of Marysvale and about 3 miles from the river and the station of 

 Belknap, on the Denver and Rio Grande Raikoad. The alunite 

 hes between two rhyohte dikes running almost due south from Twin 

 Peaks (better known locally as Peak St. Louis or Iron Mountain) 

 to a peak (Santa Cruz claims) just north of the dividing line between 

 Sevier and Piute Counties. There is a fairly good wagon road from 

 Iron Mountain to Belknap. The alunite mass between these two 

 dikes is from 1,200 to 1,500 feet wide and about 4,000 yards long. 

 While no measurements have actually been made, the depth of the 

 deposit is probably considerable. 



These alunite deposits occur at a much lower level and are more 

 readily accessible than the purer crystalline deposits southwest of 

 Marysvale and should be mined and shipped very cheaply. 



THE PRODUCTION OF ALUM FROM ALUNITE. 



The main commercial use of alunite heretofore has been in the 

 manufacture of potash alum. This industry was introduced into 

 Europe as early as the thirteenth century and assumed considerable 

 prominence at Tolfa, Italy, where extensive deposits of alunite 

 occur. Alum is stUl produced in this region by the following process : 



The mineral is calcined at low red heat in heaps or in kilns for about 

 6 hours. When the oxides of sulphur begin to escape the material 

 is removed and transferred to brick bins, where it is exposed to 

 the air for several weeks or months, being moistened with water 

 from time to time during that period. The product is then mixed 

 with water and after the insoluble material has settled the clear 

 solution is decanted, evaporated, and crystallized. The reactions 

 taking place on heating to 500° C. may be represented thus: 



Alunite. 



K20.3Al203.4S03.6H20= 



Potass, aluminum 

 sulphate. 



. 2KA1 (SOJa + 



I Potass. al nmimiTn 

 sulphate. 

 2KA1 (SOJ3 



Alumina. 



2AL0, 



+ 



Water. 

 6H,0 



Water. 



+ 24H20= 



Potash alum. 

 2KA1(S04)2 24H2O 



Another method of producing potash alum from alunite, as recom- 

 mended by Guyot ^ consists in heating the mineral to 800 C.° for 



' Sur la richesse Jndu.strielle de I'aliinitf) cone en poudre. Compt. Rend. Acad. Sci. Paris, 95 pp. 

 MS-OM; Experiences sur la calcinations de ralunite en poudre. Idem. p. 1001-1003. 



