Apparatus for reducing fraible materials into coarse and fine fractions

Claim 1

Apparatus for reducing material and distinguishing between coarse fractions and fine fractions, said apparatus comprising: (a) a material reducing mill having a rotary material fragmenter and adjacent wall means defining passage for the coarse fractions produced by said rotary fragmenter; (b) means for feeding material to be reduced; (c) passage forming means connecting said feeding means with said reducing mill, and including a Venturi section between said feeding means and said reducing mill; (d) conduit means connected across said reducing mill and passage forming means said conduit means including a first branch connected into said material reducing mill below said rotary material fragmenter, a second branch conduit connected into said material reducing mill above said rotary material fragmenter; (e) fluid flow propelling means connected into said conduit means and operable to create a flow of gaseous fluid through said reducing mill and passage forming means, said gaseous fluid flow acting to strip fine fractions from coarse fractions passing through said wall means and further stripping fine fractions from material introduced by said feeding means into said passage forming means; (f) means for discharging the coarse fractions from said reducing mill, and for discharging the fine fractions at a predetermined location in said conduit means; (g) a source of heated gaseous medium connected to said conduit means; (h) flow control valve means operably mounted in said second branch conduit; and (i) operating means connected to said valve means, said operating means being responsive to the fluid flow pressure in said passage forming means for positioning said valve means to allow heated gaseous medium to flow in said second branch conduit for maintaining a predetermined fluid flow pressure in said passage forming means.