Patent GB-714671-A (GB)
Title: An improved method for the degreasing of bones
Inventor: CHAYEN ISRAEL HARRIS
IPC: C11B1/02
Filed: 1949-07-12
Abstract: <PICT:0714671/III/1> Pieces of bone are subjected to repeated intense impacts delivered through the medium of a liquid which is present in an amount at least three times the weight of the bone, whereby the membranes of the fat-containing cells are ruptured, none or substantially none of the pieces of bone being reduced to cell size or less, and the liberated fat is removed from the resulting mixture. Preferably the rough crushed bone in pieces 1in.-2in. in size is fed into a rapidly rotating hammer mill together with a weight of water, preferably cold, from 4.5 to 30 times that of the bone. The gratings of the mill are so adjusted to ensure that the bone is discharged (generally after not more than 10 seconds) before being crushed to cell size.  The mixture discharged from the mill may be allowed to fall into cold water in a separating vessel, and the bone may be removed from the bottom of the vessel by means of a worm.  The fat-water mixture which floats on top of the cold water in the separating vessel may be allowed to flow over a weir for collection, a paddle being provided to prevent the fat from entering the worm removing the bone.  The process may be operated continuously.  If desired, the disintegrated bone removed from the separating vessel may be allowed to fall through hot water (e.g. at 70-95 DEG C.) in a second separating vessel to remove residual fat. The bone is generally in contact with the hot water for about 2 minutes.  A worm conveyer for removing the bone and a weir and paddle for removing the separated fat may be provided in the second separating vessel. Desirably the bone emerging from the hot water is subjected to a hot water spray.  The bone discharged from the first separating vessel may, if desired, be passed with cold water into a centrifugal pump (instead of into hot water) and thence into a cold water separating vessel, from which separated fat may be taken off.  The bone may be removed from the bottom of this vessel by a worm conveyer and may be treated in hot water to separate residual traces of fat.  If desired the original bone may be subjected to the repeated intense impacts delivered through the liquid in more than one hammer mill, the grids being so adjusted in size that the degreased bone does not become too fine.  In general, after every mill treatment the bone is treated in cold water and given a final treatment in hot water.  As shown, rough crushed bone is fed into a hammer mill 2 and disintegrated in the presence of a rapidly moving stream of water from pipe 3.  The mixture discharged through pipe 4 falls into the separating vessel 5 having an inclined bottom and containing cold water.  A worm conveyer 7 continuously removes the crushed bone.  The separated fat-water mixture flows over a weir 8 and is prevented from entering the worm 7 by a paddle 9.  Surplus cold water may be removed by a pipe 10.  The separation of the material flowing over the weir may be effected by heating to 94-95 DEG C.  A second separating vessel 11 containing hot water may be provided for further treatment of the bone.  The temperature of the water is maintained between 70 DEG  and 95 DEG C. by steam injected through pipe 14.  The crushed bone removed by worm 7 from vessel 5 falls to the bottom of vessel 11 and is removed therefrom by worm 13. Desirably the bone emerging from vessel 11 is sprayed with hot water.  A weir 17 and paddle 16 are provided to remove the separated fat.  In an example fresh butcher bones (15-16 per cent. by weight of fat) are crushed to pieces 1-2 in. in size and fed at a rate of 10 cwt. per hour to a beater mill fitted with 0.25 in. grids and rotating at 2.400 r.p.m.  The mill is continuously flushed with cold water at a rate of 1,000 gallons per hour.  The reduced bone and water is treated in a separating vessel containing cold water and then in a second vessel containing water at 85 DEG C. The degreased bones had a fat content of 1.74 per cent. (on dry weight).