Study On New Beneficiation Process Of High-carbon Graphite From Flake Graphite In Luobei

Graphite is a kind of important strategic resource, and its value is decided by flakesize and purity. In order to produce high-carbon graphite and protect graphite crystals,the beneficiation process commonly used in current is5to9times regrinding operationand7to13times flotation, which is too complicated and costs too much. How tosimplified the process and protect graphite crystals during the mineral processingprocess is one of the problem in the field of high-carbon graphite production nowadays.By controlling some process factors such as the re-grinding fineness and times, thebeneficiation process of high-carbon graphite is optimized and the graphite crystals isprotected at the same time, which are the purposes of this study.Luobei, which is one of the areas of Heilongjiang province, is abundant in graphiteresources, and the study object of this paper was graphite ores from Luobei, and asystematic technological mineralogy study was conducted, so were the grindingcondition tests, the rough beneficiation condition tests, and the comparative trial ofconcentrate about re-grinding fineness, regrinding times and floating density. Finally, aclosed circuit test was conducted, which was the basis for determining the concise andefficient beneficiation process to treat such kind of graphite ore.The study of technological mineralogy about this ore showed that it was a sort offlake graphite ore, whose fixed carbon content was9.29%, and its mineral componentswas complex and disseminated extent was fine. The main paragenetic gangue mineralsconsist of20%diopside,20%quartz,16%mica,13%feldspar,10%tremolite and3%pyrite.The results of roughing tests showed the appropriate conditions were as follows:grinding fineness was72.60%of-0.074mm size fraction content, pulp density was27%,pH of the pulp was9.0, the dosage of CaO was1000g/t, the dosage of kerosene was470g/t, the dosage of pine oil was50g/t and flotation time was6minutes. A coarseconcentrate was obtained, whose the fixed carbon content was48.88%and the recoverywas98.63%. The fixed carbon grade of the tailing was so low that the tailing wasabandoned.The open circuit comparative tests about regrinding fineness, times,grinding-flotation structure and floating density suggested that increasing totalregrinding time was beneficial for improving the content of fixed carbon, but harmful toprotect the flake of graphite. Regrinding time ranged from15min to45min, which ledthe concentrate fixed carbon content increased from96.37%to97.56%, and+0.045mmsize fraction content decreased from62.21%to47.35%. Under the condition of total regrinding time21min, reducing the grinding time of each segment and increasing thenumber of grinding segments from three to six resulted in the improving fixed carboncontent of concentrates from96.37%to97.56%, and improving content of+0.045mmsize fraction from50.21%to58.58%. Three-time concentrations were added after the“four-time-regrinding and five–time-concentration” process, which led the improvingfixed carbon content of the concentrate only from96.95%to96.72%. And adding aconcentration behind each segment of concentration made the fixed carbon content ofthe concentrate decrease with0.17percentage points. The lower the concentrationdensity was, the higher the fixed carbon content could be. When the floating density ofthe fifth concentration were3.33%,1.78%and0.89%, the fixed carbon content ofconcentrate were respectively97.40%,97.70%, and97.73%. Accordingly, the opencircuit process of “four-time-regrinding and five-time-concentration” was ascertained.The closed circuit tests determined the new process to produce high-carbongraphite with the short flow of “four-time-regrinding and five-time concentration withlow density”. The fixed carbon content of the concentrate and+0.045mm size fractioncontent were higher than the long process of “six-time-regrinding and seven-timeconcentration with low-density” with respectively0.46and15.18percentage points, andhigher than the process of “four-time-regrinding and five-time-concentration with highdensity” with respectively0.72and2.01percentage points. Finally, the graphiteconcentrate achieved the fixed carbon grade of97.53%and recovery of95.89%.The analysis of the concentrate showed that the gangue minerals mainly existed infine fraction, and the fixed carbon content of+0.150mm size fraction was98.30%,which was higher than that of-0.045mm size fraction with4.65percentage points.The exploratory researches of large flake graphite protection showed that under thecondition of the use of steel bars in the coarse grinding, reducing regrinding time couldupgrade large flake graphite content to9.36%and11.08%, but the fixed carbon contentdecreased to95.07%and92.56%. The paper explored the relationship between yieldand fixed carbon content of large flake graphite, providing an experimental basis for theproduction and protection of large flake graphite.