Beneficiation of graphite from Srikakulam and Visakhapatnam Districts, Andhra Pradesh

Graphite samples from Gajapathinagaram, Tonam, Andra, Kurapam, Chipurupalli, Ramabhadrapuram, Dotemba, Kondamosuru, Makavaripalem (near Narasipatnam), Venkannapalem (Chodavaram taluk) were subjected to beneficiation studies. Samples were mostly flaky and amorphous. The chief impurities were mica, quartz, feldspar, iron oxides and silicate gangue and calcite. The graphite content varied from 10 to 35 percent. The samples were subjected to flotation tests in various size grades using turpentine kerosene, pine oil, and crude oil as frothers; xanthate, brown coaltar oil and cresol as collectors; sodium silicate as depressor and sodium hydroxide or sodium carbonate and sulphuric acid as pH controllers. The size fractions ranged from -20 mesh to 200 mesh with a pulp density of 20 to 25 percent solids. The selection of reagents, size grades and pH depends on the nature of mineral constituents. The flaky and needle type graphite gave a very good flotation concentrate (after recleaning) upto 96% graphite carbon, and the fine size grade results into 98%. Hydrofluoric acid treatment gave 99.9% carbon content. (K. Kameswara Rao, Department of Geology, Ore-dressing laboratories, Andhra University, Waltair)