PURPOSE: To obtain a graphite lamellar compound capable of giving a molded article having a high strength at a low cost with good operability in the titled preparation of dipping graphite in a liquid oxidation medium, by using a mixed solution of a used and recovered oxidation medium and a new oxidation medium.
CONSTITUTION: Flake graphite is dipped in a liquid oxidation medium, e.g. a mixed acid of sulfuric acid and nitric acid, and the treated graphite and the residual heating solution are separated in a suitable draining apparatus to give a recovered acid. New flake graphite is then treated with a mixed acid of the above-mentioned mixed acid and the recovered acid to separate the further treated graphite and the residual treating solution by the above-mentioned method. A mixed acid prepared by adding a new acid to the recovered acid is then repeatedly used to continue the treatment for new graphite. Thus, the viscosity of the acid on acid treatment is reduced, and the amount of a neutralizing agent required for discarding of the used acid is reduced. The interlayer residual ratio of the reactant is high, and the expanded graphite obtained by the subsequent expansion treatment has a great expansion. The resultant molded article thereof has a high mechanical strength.
FUJII YOSHIKATSU
FUJITA ATSUSHI
MURAKOSHI TAKESHI
YAMADA KAZUO
