GB1050912A - - Google Patents

Abstract

1,050,912. Reducing grain. LAVASTO S.A. Sept. 20, 1963 [Sept. 27, 1962], No. 37175/63. Heading A2Q. In reducing cereal grains, such as wheat and rye, to flour, the grains are crushed as they are passed though the nip, e.g. 0.8 to 1.0 mm. wide, between at least one pair of smooth rollers 1 rotating, in opposite directions, with substantially the same peripheral speeds, and are thus broken into relatively large fragments of pericarp or shell and relatively fine fragments of-endosperm, i.e. flour particles without generating a substantial amount of frictional heat. The crushed grains are then passed into a centrifugal device 2, in which they are flung by a revolving rotor against the surrounding casing, so that flour particles are detached from shell fragments. The resulting mixture is passed into a sifter 3 comprising superimposed, reciprocating plane sieves. Coarse fragments of shells still retaining flour particles are retained on the two upper coarser sieves, and are discharged, through the nip, e.g. 0.1 to 0.12 mm. wide, between a second pair of rotating smooth rollers 9, and then through a second centrifugal device 10, into a second sifter 11. Coarser particles, retained on its two upper sieves, are dischaged, through ducts 12 and 13 respectively, into centrifugal bran finishers 14 and 15, in each of which a revolving, bladed rotor throws the particles against a vertical cylindrical sieve. Flour passes through each last-mentioned sieve and is discharged, through ducts 17 and 18, into a rotating, horizontal, cylindrical sieve 20, from which two sieved fractions of flour 21 and 22 are dischaged. Coarse particles of shell, e.g. bran, retained on this sieve are discharged from its end 23. Bran which does not pass through the vertical cylindrical sieves of the bran finishers is discharged at 16 and 19. Flour fractions which pass through the two lower and finer sieves of the sifters 3 and 11 are discharged, respectively, through outlet ducts 6, 7 and 39, 40. Coarser fractions, retained on the two lower sieves of the sifters 3 and 11, are fed, through ducts 8 and 24, into the nip, e.g. 0.1 to 0.12 mm. wide, between a pair of rotating smooth rollers 25, and then pass through a centrifugal separator 26 into a sifter 27, from which the coarsest fraction, retained on the upper sieve, is discharged, through a duct 28, into a bran finisher 32 discharging bran through an outlet 33, and flour through a duct 34 into a rotating, horizontal, cylindrical sieve 35. Fine fractions are discharged from the sifter 27 through outlets 29 and 30. Intermediate coarse fractions retained on its sieves are discharged, through a duct 31, into the sieve 35, from which two sieved flour fractions 36 and 37 are discharged. Coarse particles of shells and impurities are retained on the sieve 35 and discharged from its end 38. The second roller of each pair of smooth rollers may be non-positively driven, ie. a drag roller.