Abstract: An improved method and apparatus for forming briquettes particularly adapted to low rank coal fines, various biomass waste and other particulate or fibrous materials uses asymmetric mating rollers, having alternating grooves and outer lips, where the outer lips of a first roller contact the groove of a second roller and the outer lips of the second roller contact the groove of the first roller, briquette forming cavities being formed in the outer lips and the rollers travel at rotational velocities that may be either synchronized or slightly mismatched.

Abstract: A briquetting die set comprises first and second mating cylindrical dies. The first die has a plurality of adjacent recesses surrounded by a wall having an upper rim. At least a portion of the upper rim of each recess is common to an adjacent recess and has a relatively small radius of curvature. The second mating die has mirror image recesses thereon. When the first and second dies are brought into mating relationship, the upper rims of the first and second plurality of recesses mate with each other in substantially line contact to form a briquetting cavity.