Abstract: The present invention provides a process for the preparation of silicon carbide from spent pot liners generated from aluminum smelter plants. The present invention involves the use of spent pot liner (in short hereafter termed as SPL) by means of comminution of SPL by a chemical reaction followed by mixing it with appropriate proportion of commercially available quartz powder (high purity silica powder having particle size of ?100 BS mesh) and further followed by heating it in an argon plasma furnace for about 3 minutes. The product of this process is a granular powder of silicon-carbide as determined by XRD analysis. The yield of the carbon powder obtained is in the range of 30-35% and the percentage conversion to silicon carbide obtained is in the range of 70 to 85%.

Abstract: The present invention relates to a simple and efficient process for the preparation of pencil lead from the spent or waste pot liners of aluminum industries, said process comprising steps of crushing the liners into small sizes, adding chromic acid to the crushed liners, washing the reacted product with distilled water, thermally shock-treating the dried mass to obtain a fine flowing graphite powder, mixing the powder with binder(s), moistening the mixture with requisite amount of water to form a stiff dough, extruding the dough under pressure to obtain product in the form of a discs, heating the dried discs in an inert/reducing atmosphere in a furnace at temperature ranging between 400–1200° C. for time duration ranging between 1 to 6 hours, and obtaining the pencil lead.

Abstract: The present invention relates to a simple and efficient process for the preparation of pencil lead from the spent or waste pot liners of aluminum industries, said process comprising steps of crushing the liners into small sizes, adding chromic acid to the crushed liners, washing the reacted product with distilled water, thermally shock-treating the dried mass to obtain a fine flowing graphite powder, mixing the powder with binder(s), moistening the mixture with requisite amount of water to form a stiff dough, extruding the dough under pressure to obtain product in the form of a discs, heating the dried discs in an inert/reducing atmosphere in a furnace at temperature ranging between 400-1200° C. for time duration ranging between 1 to 6 hours, and obtaining the pencil lead.