Japan - used generator brushes recycled into mechanical pencil leads

Tokyo Electric Power Co. (TEPCO) and Tombow Pencil Co. have jointly developed mechanical pencil leads recycled from generator brushes used in TEPCO‘‘s thermal power plants. Japan for Sustainability reports that generator brushes are made from highly pure graphite (over 97 per cent), and are crushed to form graphite particles.

Generator brushes transmit electricity to rotating shafts and must be replaced on a regular basis because they get worn out from friction with the rotating shafts. Discarded brushes used to be disposed of as industrial waste in landfill. Having examined the cost and effectiveness of recycling generator brushes, TEPCO decided to recycle the brushes into mechanical pencil leads in collaboration with Tombow.

By specifying an optimal crushing method and suitable particle size distribution, and by improving strength and color density by mixing in other graphite materials, pencil leads equal in quality to conventional leads can be produced.

TEPCO estimates that about 300kg of used brushes are replaced in its thermal plants annually. Recycling all these brushes could produce 24 million refill leads (1.5 million packages of 16 leads each.