Apparatus suitable for making a coal-oil-water fuel mixture includes a grinder for grinding coal to a relatively fine particle size, a mixer for controllably mixing the coal particles with water and oil and a sonic agitator to stabilize the mixture. The sonic agitator comprises a processing chamber associated...http://www.google.com.au/patents/US4401437?utm_source=gb-gplus-sharePatent US4401437 - Apparatus for manufacturing and stabilizing coal-oil-water fuel mixture
