METHOD AND APPARATUS FOR AUTOGENOUS COMMINUTION PRIMARILY OF OVERCOMPETENT, HETEROGENEOUS MINERAL MATERIAL

摘要

ABSTRACTIn autogenous grinding of mineral material in a grinding mill with ascreening wall a method is provided for enabling the removal of at leastthree different fractions without the need of the screening wall beingdivided into sectors, thus increasing grinding material turnover andgrinding capacity, namely by passing through openings (8) distributedover the screening wall (7) a mixed material fraction containing allmaterial fractions having a particle size greater than or equal to thegreatest openings (8) in the screening wall and dividing up the mixedmaterial fraction into at least three fractions in a classifying appara-tus (13), by always taking out from the classifying apparatus (13) atleast a fine fraction, a coarse fraction and a medium coarse fraction,the latter two fractions being kept separate for permitting, as required,diversion (38) of the coarse material fraction as grinding charge tofollowing grinding steps, the two fractions being put together when saidneed of charge material is not present, when they may be taken to ameans for reduction to sub-critical sizes for subsequent return to themill (1) for renewed grinding.