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

Abstract

In this paper an attempt has been made to characterize the low grade calcareous graphite ore from Shivaganga region, India. By judicious combination of structural, thermal and chemical analytical techniques, the liberation size of graphite as well as estimation of minerals are determined to establish a feasible beneficiation process. This data show a good correlation. The ore consists of graphite, calcite and quartz as major minerals. The d-values 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 quantitative minerals estimation confirms that calcite significantly liberates below 90 micron size fraction and accounts for 60% calcite and 10% graphite minerals distribution. The DTA data show that calcite decomposes between 700-850 degrees C and graphite starts combustion at 850 degrees C. In view of this, 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.