Process of isolating carbon nanotubes from a mixture containing carbon nanotubes and graphite particles

A process for the isolation of carbon nanotubes from a mixture containing carbon nanotubes and graphite particles, said process comprising the steps of:

• pulverizing said mixture to obtain a pulverized product;
• dispersing said pulverized product in a liquid medium to obtain a dispersion;
• centrifuging said dispersion to obtain a precipitate of graphite particles having a particle size of 0.3 .mu.m or more and a supernatant containing fine particles having an average particle size of 0.2 .mu.m or less and including carbon nanotubes and graphite particles;
• separating said supernatant by microfiltration into a solid phase including said fine particles and a liquid phase;
• and
• calcining said solid phase in an oxygen-containing atmosphere at a temperature sufficient to burn selectively the graphite particles and to leave the nanotubes.