Abstract: In order to determine the process conditions and properties for preparing expandable graphite from a natural flake graphite from Mozambique， the preparation conditions were studied， and its properties and mechanism were studied. The results show that the volume to mass ratio of HAc and HClO4 to graphite of +0.5 mm and 0.5~0.3 mm is 1.3 mL/g and 5 mL/g， the mass ratio of KMnO4 to graphite is 0.13， the reaction temperature is 50 ℃， the reaction time is 60 min， the expansion volume of expandable graphite at 850 ℃ is 450 mL/g and 400 mL/g， respectively； the volume to mass ratio of HAc and HClO4 to graphite of 0.3~0.18 mm is 1.3 mL/g and 5 mL/g， the mass ratio of KMnO4 to graphite is 0.17， the reaction temperature is 50 ℃， the reaction time is 60 min， the expansion volume of expandable graphite at 850 ℃ is 320 mL/g； the expansion volume of flake graphite of different grain sizes is roughly affected by the change of conditions， relatively speaking， the coarser the particle size， the better the effect of the oxidation intercalation reaction， and the larger the expansion volume of the produced expandable graphite； after the oxidation intercalation reaction， the gaps between the flake graphite layers are embedded with ClO[-4] and Ac^-， the obtained expandable graphite is expanded by high temperature， rapid gasification decomposition of ClO[-4] and Ac- in inter-layer voids， and the large amount of gas generated destroys the molecular force between the graphite layers， spread the graphite sheet， formed expanded graphite with large volume， good worm effect and rich pores.

Key words: Flake graphite, Graphite interlayer, Oxide intercalation, Expandable graphite, Expandable volume