9^ ]!^EW YOflK STATE MUSfiUM 



is blasted by dynamite. It splits readily along the cleavage planes. 

 The large blocks or slabs from blasting are reduced by sledges to a 

 size convenient for handling. From the stopes the talc is loaded into 

 cars and run out to the incline where it is dumped into skips and 

 hoisted to the surface. 



Preparation for the market. The processes in use for grinding 

 and preparing the talc have been gradually evolved out of long 

 continued experimentation. It is said that the first prepared talc 

 shipped from the district was ground in a grist mill. With the dis- 

 covery of the value of the fibrous variety as a paper filler, attention 

 was directed to the methods of treatment which have been per- 

 fected until capable of producing the desired quality and uniformity 

 of grade. 



The mills, all of which are run in connection with the mines, 

 number 7 or 8 in all. They have a combined capacity of between 

 75,000 and 100,000 tons of prepared talc a year. They are situated 

 along the Oswegatchie river in the stretch between Gouverneur and 

 Edwards, the sites being selected with reference to water power 

 facilities. The mines of the International Pulp Co. at Talcville ship 

 their product by railroad to the mills at Hailesboro. 



The reduction of the talc is accomplished in several stages. The 

 lump talc as mined is first broken in a jaw crusher of the Blake 

 type. The product then goes through a cone grinder or through 

 rolls where it is reduced to .5 inch or less. In the third stage the 

 crushed talc may be ground between buhrstones of special manu-j 

 facture or in a centrifugal grinder of which the Griffin mill is aj 

 common type. The1:alc is then passed through a bolt of about 60 ' 

 mesh and goes to the finishing cylinders, or the finest material may 

 be separated by air currents which blow it into settling chambers and 

 then forms one of the grades for the market. The common practice 

 is to m.ake the final reduction in revolving cylinders charged with 

 pebbles. The Alsing cylinder is the one generally used and is from 

 8 to 10 feet long and 6 feet in diameter. It is lined with porcelain 

 brick. It is turned from 20 to 25 times a minute. The charge con- 

 sists of I ton of talc and 3 tons of flint pebbles. The grinding of a 

 single charge takes from 2 to 5 hours, depending upon the grade of 

 product that is desired. The fibrous character of the talc is main- 

 tained throughout the grinding to the end product, so that it is diffi- 

 cult to size the ground talc by screening ; consequently the degree of 

 fineness is regulated entirely by the duration of the final grinding 

 process. 



