N. Patnaik et al., Thermal and structural study of low grade graphite ore from Shivaganga, India - Its implications in beneficiation process, J THERM ANA, 57(2), 1999, pp. 541-549
In this paper an attempt has been made to characterize the low grade calcar
eous graphite ore from Shivaganga region, India. By judicious combination o
f structural, thermal and chemical analytical techniques, the liberation si
ze of graphite as well as estimation of minerals are determined to establis
h a feasible beneficiation process. This data show a good correlation. The
ore consists of graphite, calcite and quartz as major minerals. The d-value
s and decomposition of calcite are found maximum at two size fractions i.e.
, +500 and below 90 microns. The TG and chemical analysis data on quantitat
ive minerals estimation confirms that calcite significantly liberates below
90 micron size fraction and accounts for 60% calcite and 10% graphite mine
rals distribution. The DTA data show that calcite decomposes between 700-85
0 degrees C and graphite starts combustion at 850 degrees C. In view of thi
s, to achieve calcite free graphite the ore needs to be calcined below 850
degrees C and ground to 80% passing 75 micron size prior to flotation.