CPC B03B 5/626 (2013.01) | 19 Claims |
13. A spiral separator for providing at least partial separation of a first species and a second species, the spiral separator comprising at least two stages comprising at least a more upstream stage and a more downstream stage, each of said more upstream and more downstream stages comprising:
a feed arrangement;
a spiral trough comprising a more upstream region and a more downstream region; and
a splitting arrangement for off-take of a concentrate band of more desired material;
wherein the feed arrangement of each of the more upstream and more downstream stages is, in use, arranged to feed a feed slurry comprising a mix of said first species and said second species into the more upstream region of the respective spiral trough at a feed entry region of the respective spiral trough;
wherein the more upstream region of the respective spiral trough of each of the more upstream and more downstream stages has a trough floor region, and provides an effective cross-trough floor slope relative to the horizontal, which reduces from a cross-trough floor angle of between 15 and 20 degrees to a cross-trough floor angle of between 10 degrees and 14 degrees;
wherein the more downstream region of the respective spiral trough has a trough floor region having an effective cross-trough floor angle which reduces to between 4 degrees and 8 degrees, relative to the horizontal;
wherein the splitting arrangement of each of the more upstream and more downstream stages is provided at or immediately adjacent the said trough floor region having an effective cross-trough floor angle which reduces to between 4 degrees and 8 degrees, to split a concentrated band of the first species from the rest of the flow in the respective spiral trough; and
wherein the feed arrangement of the more downstream stage comprises a slurry preparation apparatus, comprising a mixing region for mixing material from a more fluid stream of a slurry flow exiting a stage upstream of the more downstream stage with material from a less fluid stream of the slurry flow exiting said stage upstream of the more downstream stage, prior to feeding mixed prepared slurry into said more downstream stage.
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