134 NEW YORK STATE MUSEUM 



made. The middlings are sometimes reground to rub off the 

 quartz and feldspar grains still attached to the flakes, and then 

 passed through the machine again. 



Mr Charles T. Rowland, president of the Rowland Graphite 

 Company, had a representative of the Huff Electrostatic Separator 

 Company make a thorough investigation covering the milling of the 

 Rowland ore in 1916. He says : " The sample used in making this 

 test was blasted out of the bed, as it was desired to get ... an 

 average sample of the output of the mine. This report shows that 

 the ore can be milled economically with a good recovery, and that 

 the flake produced is of very high grade and compares very favor- 

 ably with the best flake now being produced in this country." 1 



Cirkel says that " Experiments have . . . shown that . . . 

 (flake) graphite may possibly be separated from the gangue elec- 

 trostatically, and it is not unlikely that such a process may be 

 worked before long. The writer [Cirkel] submitted a parcel of 

 100 pounds for preliminary test to the Huff Electrostatic Separator 

 Company of Boston, Mass., and the tailings from this test were 

 without question quite clean. The middlings consisted of graphite 

 with attached gangue particles, and need regrinding before they 

 can be again submitted to the electrostatic treatment. The con- 

 centrates appear to be free from rock, but there was some attached 

 gangue. The writer [Cirkel] believes that if this product was sub- 

 mitted to the polishing treatment it is likely that a clean article may 

 be the result." 2 



The size of the graphite flake is another factor that must be taken 

 into consideration. A rock carrying a coarse flake is more desir- 

 able, other things being equal, since the value of the concentrates 

 and the economy and perfection of the separation is in direct pro- 

 portion to the size. One of the many factors involved is the easy 

 crushing of the rock-. Among other things that affect the ease of 

 crushing is the mineralogical make-up of the ore. The presence of 

 pyroxene (diopside), such as Avas seen in the Rowland ore, offers 

 serious objections to its utilization. The crushing machines must be 

 designed and adjusted so as to cause the least amount of attrition to 

 the flake. Moreover, there is the actual condition in which the 

 flake is found. It was repeatedly observed that where folding, 

 squeezing and igneous activity have taken place, the flake has been 

 frayed out into fantastic forms, resulting in the splitting of the 



1 Rowland, Charles T., letter of Oct. 16, 1917. 

 •-Cirkel, Fritz, Trans. Can. Min. Ind. 191 2, 15:267 



