GB1374020A - Method of and apparatus for processing mineral ore containing fibrous material to remove the fibrous material therefrom - Google Patents

Abstract

1374020 Separating fibrous material from ore ALLIS-CHALMERS CORP 21 Nov 1972 [23 Nov 1971] 53698/72 Heading B2H A method of processing a mineral ore containing a desired mineral, e.g. nickel sulphide, and an undesirable fibrous material, e.g. asbestos, both associated with a gangue material, e.g. serpentine, comprises: (a) initially treating the ore to reduce it to a size suitable to form the input feed of a first grinding stage; (ib) subjecting the treated mineral ore at the first grinding stage to a relatively coarse grind sufficient to obtain liberation of substantially all of the undesirable fibrous material from the ore; (c) subjecting the discharge from the first grinding stage to a screening action to separate the liberated fibrous material from the defibred ore; and (d) subjecting the defibrated and separated ore at a second grinding stage to a grind sufficient to liberate a required amount of the desired mineral from the remainder of the defibred ore. As shown, the mineral ore is first crushed in a crusher 10 and fed to a first stage grinding, e.g. rod, mill 12, to which water is preferably added, so as to liberate the fibrous material from the ore. The fibre-laden, slurry discharged from the mill 12 passes through a screening device 14, which may be a stationary sieve bend or a vibrating screen, whereby the liberated coarse fibres are retained on the screen and the defibred slurry passes through. A dewatering device 17 may be provided to feed a fairly thick slurry to a second stage grinding, e.g. ball mill 16 to which water from a separate source may be added in controlled amounts to provide a proper solids-liquid ratio and in which the desired mineral is liberated from the ore. The ground material discharged from the mill 16 may then pass along an open circuit path 22 to further processing. Alternatively, the ground material may pass along a closed circuit path 23 to a classifier 18 which separates it into oversized product which is recycled along path 24 back into the feed end of the grinding mill 16 and undersized product which passes along path 20 to further processing. In a modification, Fig. 2 (not shown), the defibred slurry discharged from the screening device (14') passes through a classifier (18') which separates it into undersized product, which passes to further processing, and oversized product which passes through the second stage grinding mill (16') the output product of which is recycled back through the classifier. More than one grinding stage may be used downstream of the screening device.