Patent GB-995114-A (GB)
Title: Improvements in or relating to the treatment of run-of-mine friable material
IPC: B02C17/00
Filed: 1963-09-25
Abstract: 995,114. Grinding. HARDINGE CO. Inc. Sept. 25, 1963 [Oct. 5, 1962], No. 37700/63. Heading B2A. Apparatus for treating run-of-mine friable material comprises an autogenous mill 10, Fig. 3, for reducing all size ranges of the material, means 46 to remove a fine size range from the mill together with a selected larger size range, means to divide the larger size range into separate portions of like form, and feeding means leading at least one of these portions to treatment means located outside the mill and capable of changing the form of the portion, the treated portion or portions or the untreated portion being then returned, wholly or partially, to the mill for further size reduction by way of a return line. In the system, as described, the output of the mill 10 is applied to a double trommel separator 46 of the kind which rotates with the mill and divides the input into fine, medium and coarse or "pebble" portions 108, 112 and 50. Each of the medium and coarse portions is divided into separate portions by adjustable splitters 116<SP>1</SP>, 116 feeding to separate conduits (122, 124, Fig. 4, for the coarse portions). The coarse portion discharged from the conduit 124 is capable of being further divided by non-adjustable splitter 134 into two portions leading respectively to a return line 138 to the inlet of the mill 10 and a conveyer 140 leading to an auxiliary crusher 136. Discharge from the crusher 136 may be either through a line 140<SP>1</SP> or to the return line 138 to the mill 10. The coarse portion in the conduit 122 is supplied to a distributor 125 for distribution to one or more separation and treatment devices. As shown in Fig. 4 it may be applied to a picker-belt 64 and magnetic separator 66, the outputs of which are further divided by splitters 130, 132, 150, 146, for feed to the return line 138 or conveyor 140 or for bleeding-off at 142 or 148. Altenatively, material from the conduit 122 may be directed to a heavy-medium, screw-type separator 82, coarse and fine samples being bled off at 152, 156 or fed to the return line 138 or conveyer 140. A further possible application of the material from the conduit 122 is to an auxiliary treatment device 96 which may comprise any of a wide variety of concentrating tables, jigs, spirals, flotation apparatus, alternate magnetic separators, and sizing and reduction means, e.g. crushers, the output being discharged via line 160, or applied to the return line 138 or conveyer 140. The medium size portion 112 may be similarly sub-divided by an adustable splitter 116<SP>1</SP> into two issuing conduits 122<SP>1</SP>, 124<SP>1</SP>, Fig. 5, the discharge from which may be directed similarly to that described for the conduits 122, 124, Fig. 3. The fine size portion 108 from the trommel 46 discharges to a conduit 110, Fig. 3, and may either leave the circuit entirely or be treated therein. The autogenous mill 10 includes discharge openings 48, Fig. 1, which are small in proportion to grate sections 30 so that only a proportion of heavier material, e.g. the pebbles 50, is discharged from the grinding zone. The spaces 48 comprise portions of the radial spaces between segmental edges of the grate sections 30, and their extent and position are determined by suitably placing the sections of sectional lifter bars 28. In a modification, the grate 162, Fig. 6, is perpendicular to the mill axis and has radial lifter bars 164 which hold the grate connected to the exit end of the mill, if desired. The inner periphery of the grate terminates in a deflector ring 166, spaced in an axial direction from the end wall 16<SP>1</SP> to provide an annular discharge space 168. The grate and ring are maintained in position by spacer bars 170. The grate includes a number of discharge openings 176 larger than the normal slots in the grate. In a further modification, the end wall 16<SP>11</SP>, Fig. 7, which is parallel to the wall 14<SP>11</SP>, carries a grate 178 perpendicular to the mill axis and parallel to the exit end of the mill. The grate is spaced to provide an exit space 180 into which material is discharged, and an annular expansion zone 182 permits material to move laterally. Specification 949,791 is referred to.