GB657621A - Process for grinding and classifying organic materials - Google Patents

Abstract

657,621. Grinding organic material. CLARK, G. M. (Agicide Laboratories, Inc.). Jan. 22, 1948, No. 2011. [Class 59) In a process of finely dividing material of an organic nature sensitive to oxygen and to elevated temperatures, the material, while in a grinding mill, is maintained in a volume ,of steam at super-atmospheric pressure by vaporizing water in the mill, whereby oxygen is excluded and the temperature kept below the critical value. Material, e.g. nutshell, from a hopper 14, Fig. 1, is carried by a screw conveyer 15 through a rotary seal valve 16 to a mill 10 where it is ground in steam at superatmospheric pressure between two contrarotating discs 11, 12, the ground material passing from the mill through an outlet 17 to an interrupted screw conveyer 18. Water is supplied to the mill at such a rate that it is immediately vaporized by the heat developed by the grinding action by a pipe 27 having a valve 26 controlled by a thermostat 24 in the mill outlet 17. A damper controlled vent pipe 22 maintains the required pressure in the mill. Heat may be supplied externally to the mill Water may be introduced into the mill along with the material to be ground. The regulation of the valve 26 may be made responsive to increase in amperage in the grinding motor circuit. The ground product may be carried from the conveyer 18 to a primary air classifier 26<SP>1</SP>, Fig. 2, whence the fines pass to a classifier 36 and receivers 38, 41, and coarse particles are carried by conveyer 27<SP>1</SP> to; (a) an air classifier 32 whence the fines pass to a receiver 34 and coarse particles to a spout 33, and; (b) a spout 29 leading into the spout 33 whence it returns to the mill, the general arrangement being such that the recirculating load in the classifying system is at least three times the weight of the finished product collected. The classifying system is kept at a temperature of for example 180-212‹F. when the mill is at 275‹F., and at a humidity of 85 per cent or more. Specification 657,665 is referred to.