The invention relates to the field of preparation of expandable
graphite, in particular to a method for preparing low-
sulfur expandable
graphite in the
room temperature atmospheric environment by using low-concentration
sulfuric acid as an intercalation
reagent by a mild and easily-controlled chemical intercalation method in accordance with medium-low carbon fine
flake graphite. The method is simple in equipment, safe, controllable, free from
gas protection and special protection, and suitable for
mass preparation of low-
sulfur fine
flake graphite expandable
graphite with low cost. The method comprises the following steps of (1) adopting natural fine
flake graphite as a
raw material, wherein the percentage by
mass of carbon is 50-90%, and the size of graphite is 45-180 <mu>m; (2) under the condition of
room temperature, using
potassium permanganate as an oxidant, adopting the
sulfuric acid of which the percentage by
mass is 30-85% as an intercalation agent, and performing effective intercalation on the graphite
raw material under the condition of
room temperature, wherein heating is not needed in the process, and after uniform stirring is performed, the process can be completed under the standing condition; and (3) adopting a
microwave tube furnace for rapidly expanding the expandable graphite, and finally, obtaining a low-
sulfur fine flake expandable graphite
powder material with a high-expandable volume.