METHOD OF PURIFYING A CARBON MATERIAL Russian patent published in 1997 - IPC

FIELD: purification of carbon materials. SUBSTANCE: invention is concerned with producing objects for semiconductor engineering and nuclear industry. Burned carbon stock is charged into graphitizing furnace, heated to graphitization temperature with simultaneously feeding chlorine and fluorine-containing gas in a cycling mode: 7- 11 cycles lasting for 30-65 min with 5-35-min breaks. On achieving graphitization temperature, heating and gas feeding are ceased and nitrogen is entered until stock is cooled to 1800 C. Content of admixtures (Al, Fe, Mg, Mn, Si, Cu, B) in the purified stock does not exceed 1•10^-5 wt %. EFFECT: enhanced efficiency of purification. 2 cl, 2 tbl