Method for the manufacture of pristine graphene from Kish graphite

A method for the manufacture of pristine graphene from kish graphite comprising:

• A. providing kish graphite,
• B. pre-treating the kish graphite, said pre-treatment of kish-graphite including the following successive sub-steps:
• i. a sieving step wherein the kish graphite is classified by size as follows:
• a) kish graphite having a size below 50 μm,
• b) kish graphite having a size above or equal to 50 μm,
• the fraction a) of the kish graphite having the size below 50 μm being removed,
• ii. a flotation step with the fraction b) of the kish graphite having the size above or equal to 50 μm,
• iii. an acid leaching step wherein an acid is added so that a ratio in weight (acid amount)/(the kish graphite amount) is between 0.25 and 1.0,
• iv. optionally washing and drying the kish graphite
• C. synthesizing pristine graphene from the kish-graphite including the following successive sub-steps:
• i. intercalating the kish graphite with a nitrate salt and an acid to obtain intercalated kish graphite,
• ii. thermal expanding the intercalated kish graphite to obtain expanded kish graphite at a temperature above 600° C.,
• iii. exfoliating the expanded kish graphite by ultra-sonication to obtain exfoliated kish graphite,
• iv. separating unexfoliated kish graphite from the exfoliated kish graphite to obtain pristine graphene.