Raymond Roller Mill
n A type of mill used for the dry-grinding of pigments or similar materials. The pre-crushed crudes or solids are fed into a circular grinding chamber in the base of the mill and by mechanical means are forced between rolls and a ring. Grinding of the pigment crude is obtained by the centrifugal force and pressure of the revolving roll exerted against the ring. A stream of compressed air passes through the mill and carries out the pigment particles which are fine enough to “float” on it; the larger particles drop back into the mill grinding chamber for further grinding.