A SIMPLE AND EFFICIENT PROCESS FOR THE PREPARATION OF PENCIL LEAD FROM SPENT POT-LINERS

摘要

The present invention relates to a simple and efficient process for thepreparation of pencil lead from the spent or waste pot liners of aluminiumindustries, said process comprising steps of crushing the liners into smallsizes, adding chromic acid to the crushed liners, washing the reacted productwith distilled water, thermally shock-treating the dried mass to obtain a fineflowing graphite powder, mixing the powder with binder(s), moistening themixture with requisite amount of water to form a stiff dough, extruding thedough under pressure to obtain product in the form of a discs, heating thedried discs in an inert/reducing atmosphere in a furnace at temperatureranging between 400-1200~C for time duration ranging between 1 to 6 hours, andobtaining the pencil lead.