132 NEW YORK STATE MUSEUM 



CONCENTRATION PROBLEMS 



Mechanical ore separation is an ancient art and a modern science. 

 In the western section of the United States ore dressing is on a 

 far firmer basis than in the case of a comparatively small industry 

 like that of graphite. The separation of graphite from the gangue is 

 exceedingly difficult, calling for long experience and mechanical 

 ingenuity, which is rarely available in the graphite areas of the 

 Adirondacks. Numerous failures can be attributed to this cause. 

 During the past 15 years the technology has experienced some 

 remarkable improvements which have revolutionized the practice 

 of ore dressing in general. Graphite separation has suffered from 

 neglect and lays far behind. Still the old process of buddling con- 

 tinues to be the chief method, while flotation and electrostatic sepa- 

 ration have been developed without making any impression in the 

 graphite industry of this region. 



Table of specific gravities 



MINERAL SPECIFIC GRAVITY 



19 to 3.23 



Apatite 3 



Biotite ■ 2 



Chlorite 2 



Feldspar • 2 



Garnet . 3 



Graphite 2 



Muscovite 2 



Phlogopite 2 



Pyrite 4 



Pyroxene 3 



Quartz 2 



Serpentine 2 



Titanite 3 



70 to 3 . 10 

 65 to 2 . 96 

 47 to 2 . 67 

 15 to 4.30 

 09 to 2.23 

 76 to 3 . 00 

 78 to 2.85 

 95 to 5.10 

 20 to 3 . 60 

 65 to 2 . 66 

 50 to 2 . 65 

 40 to 3 . 56 



These newer processes render it possible to separate a wide range 

 of minerals of close specific gravity, that can not be separated by 

 jigging or slime washing. Even minerals having the slight difference 

 in specific gravity of 0.35 can be treated. The electrostatic method 

 has many admirers and promises to be used more and more. Several 

 large deposits of graphite seen by the writer were regarded of little 

 commercial value because of the large amounts of micaceous 

 minerals present. The separation of biotite and graphite is exceed-, 

 ingly difficult, if not impossible, by the usual processes. If, how- 

 ever, the electrostatic or flotation processes can be adapted to 

 graphite milling, then there are great sources of graphite still 

 untouched that would become available. 



Two ores of even identical composition can not always be treated 

 by the same method. On account of the different physical character 



