Thermal and structural study of low grade graphite ore from Shivaganga, India - Its implications in beneficiation process

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.