T28 NEW YORK STATE MUSEUM 



situated near the mines, while the refining is rarely practised by the 

 mine operators, the majority of them sending their concentrates to 

 other concerns for treatment. 



Ore separation in general is based on marked physical or chemical 

 characteristics of the ore and the gangue : (i) differences in 

 specific gravities, (2) differences in electrical conductivity, (3) 

 selective behavior of a mixture of water and oil upon the surface 

 tension, or (4) upon the magnetic properties of the ore and the 

 gangue minerals. Up to the present time graphite separation is 

 accomplished by specific gravity methods. 



" The whole problem of the concentration of graphite is in great 

 contrast to that of metallic ores, in that in the former case we seek 

 to save the light minerals and reject the heavy, while in the latter 

 case the reverse is true." 1 



The specific gravity method of concentrating graphite is sub- 

 divided into the wet and dry processes. Both methods require that 

 the ore, as it comes from the mine, first be reduced to a pulverized 

 condition. This is effected by various types of crushers, rolls and 

 stamps. A great variety of rock breakers are in use. There are 

 jaw crushers, which are intermittent in action; and the rotary and 

 gyratory types that are continuous in operation. Further crushing 

 is done by rolls which are constructed of manganese steel. The 

 space between the rolls varies from practically nothing to three- 

 fourths of an inch. They are fed with lumps about 1% to 1^ 

 inches in size. Frequently, however, California stamps are used 

 instead of, or in combination with, rolls. 



From this point on, the wet and dry methods differ. In the wet 

 process, which is the one most commonly employed in the Adiron- 

 dacks, the crushed rock is mixed with water and fed to a series of 

 buddies. These consist of circular tanks 3^ to 4 feet in depth and 

 16 to 18 feet in diameter, with a slightly convex bottom, so that the 

 floor of the tanks slopes in all directions from the center to the 

 circumference. A vertical shaft, situated in the center of the 

 buddle, carries a tub, perhaps 3 feet in diameter, with a perforated 

 bottom. The mixture of crushed ore and water is fed into this 

 tub by a stationary sluiceway or launder. Thus the ore is made to 

 enter the buddle at the center and is carried toward the sides by 

 the water which is allowed to escape through specially arranged 

 openings, either controlled by manually operated valves or wooden 

 stoppers fitting round holes. The movement and even distribution 



1 Kemp, J. F., U. S. G. S. Bui. 226, p. 513. 



