Study On Mechanism And Purification Of Fine Flake Graphite By Flotation And Alkali-acid Method From Danfeng Shanxi

The high-purity graphite was widely used in chemical,aerospace,metallurgy,electronic,mechanical,nuclear energy and other fields because of its good performance in electrical conductivity and thermal expansion,stronger reresistant of high temperature,corrosion and oxidation,self-lubricating and easy-precision machining.The demand for high-purity graphite materials increasing every day,while our country industrial production technology of graphite is still in low level presently in the world,most of the factory only can produce raw materials and raw products,so study the preparation methods of high purity graphite is necessary.This article aiming at graphite mine in Shanxi province,combining the graphite purification methods of floatation and alkali-acid method to prepared high-purity graphite,explore a way to deal with these types of graphite mine.The research of ore sample indicates that the ore is the fine flake graphite;the content of fixed carbon is 13.70%.The main gangue minerals of sample contains calcite,quartz,muscovite,feldspar,diopside and tremolite,etc.The khenpo size of this samples is much thin,75.75%of the graphite particle mainly distributed in-0.074mm size fractions.The flotation test showed that the appropriate roughing conditions were as follows:grinding fineness was 75.18%of-0.074mm size fraction content,pulp density was 30%,the dosage of kerosene and pine oil were 100g/t and 100g/t,the flotation time was 6 minutes.A coarse concentrate was obtained,who's the fixed carbon content was 47.38%and the recovery was 90.95%.The appropriate conditions of open circuit were as follows:one-time rough,one-time scavenging,four-time-regrinding and five-time concentration.Through the semi-industrial open test according to above-mentioned process obtained graphite concentrate sample with96.43%fixed carbon content,which reached the standard of high carbon graphite.The carbon graphite concentrate sample main minerals were graphite,mica,chlorite and feldspar.The alkali-acid method to preparation of high-purity graphite test showed that the appropriate conditions were as follows:the quality ratio of graphite and sodium hydroxide was 1:1,the mixing liquid to solid ratio of water and mixed sample was0.4:1,the calcinations temperature was 700?,roasting time was 0.5h;water volume was 4m~3/t of graphite,flooding temperature was 50?,flooding time was 30min,flooding stirring intensity was 200r/min,washed five times until pH between 7 and 8;used hydrochloric acid to leaching,volume of acid was 6m~3/t of graphite,concentration of acid was 1.0mol/L,leaching temperature was 35?,leaching time was 20min,washed four times until pH between 6 and 7.Under the above conditions obtained the high purity graphite concentrate with fixed carbon content was 99.96%,recovery was 96.58%.The mechanism analysis of this purification with alkali-acid method showed that oxides of metal elements could be separated from silicate mineral containing metal element in carbon graphite concentrate sample by roasting of adding alkaline and flooding,and then can be removed by acid leaching;impurities containing nonmetallic element could be dissolved and removed mostly by roasting of adding alkaline and flooding,minority elements such as silicon and sulfur will form the precipitate,needing acid-leaching to removed it.The graphite purification of fine flake and crystalline graphite mine in Shanxi province is determined through above research;the products reached the target of high-purity graphite,which will provide theoretical basic and technical reference to rational exploitation of this graphite.