Effect of Acid Leaching on Recovery of Graphite from Calcareous Deposits

In this paper an attempt has been made for optimisation of acid leaching of calcite from graphite ore of Tamilnadu. The ore containing 39% acid soluble and 61 % insolubles. The best leaching parameters obtained at particle size below 150 microns are reaction time 20 minutes,temperature 40°C, solid liquid ratio 1:4 and stoichiometric ratio of acid 0.69. Flotation test results on partial leached
and on unleached sample indicate that the graphite grade and recoveries are improved from a calcite leached sample. The flotation product obtained from a leached sample contains 73% fixed carbon with 83% recovery.