THE PREPARATION OF EXPANDED GRAPHITE USING FINE FLAKY GRAPHITE

The preparation of expanded graphite from a fine flake graphite using a chemical method was studied to determine the optimum conditions. The results show that high quality expanded graphite with an expansion ratio of 180～200, a bulk density 0.012?5?g/mL, ash content 2.063?[WTBX]W/%～2.470?W/%, sulphur content 0.213?W/%～ 0.233?W/% and volatilization 4.5?W/%～8.5?W/% can be attained by the following procedure. First, acidify 100～160 mesh fine flaky graphite in a mixture of sulphuric acid and nitric acid (5.0～7.5∶1.0); then add 6?W/%～ 7?W/% strong oxidant (KMnO 4) and 6?W/% FeCl 3, stirring it for over 2?h. Finally after washing in water to a pH 5～7 and drying, expand it in the temperature range 900?℃～1?000?℃. The method is simple and has advantages over present methods in that nitric acid used in the processing was reduced by 30 to 60?% and only one acidifying treatment was required.