GB1232183A - - Google Patents

Abstract

1,232,183. Rotary screens. FALCONBRIDGE NICKEL MINES Ltd. 19 June, 1969 [1 July, 1968], No. 31085/69. Heading B2H. [Also in Division C1] A benificiated nickel ore is obtained from nickeliferous boulders having nickel concentrations that decrease progressively inwardly from the surface thereof by providing a comminuting zone, e.g. tumbling mill 10, (Fig. 5), forming a body of said boulders therein, and tumbling the boulders in rubbing contact with each other to abrade material of relatively high nickel concentration from the boulders to form a comminuted product 14 and uncomminuted reject cores 15 of relatively low grade, the tumbling being controlled to effect a continuous and gradual abrasion of the boulders, and minimise breakage if the cores, fresh boulders 12 being provided through inlet 11 to displace the reject cores 15 and the product 14, the degree of upgrading of the product being controlled by controlling the amount of abrasion of the boulders. Boulders are indicated in the specification as being ore of particle size greater than 1 inch. The ore may be in the form of completely or partially serpentinised boulders. The reject cores and the upgraded product may be discharged together, e.g. through outlet 13 from the comminution zone being separated, e.g. by trommel 16, on discharge. In alternative embodiments (Figs. 6 and 7) shown, at least a portion of the upgraded product may be removed peripherally from the comminution zone by means of peripheral discharge grates 17 and 28, spaced at 90‹ around the periphery of the drum. The rate of abrasion of the boulders may be regulated by the feedrate to the mill and the speed of rotation of the mill which may be about 60% of its critical speed.