Spiral separators and parts therefore

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.

A spiral trough for use in a spiral separator for providing at least partial separation of a first species and a second species by wet gravity separation, the spiral trough comprising:

• a more upstream region, the more upstream region comprising a slurry feed region adapted, in use, to receive a feed slurry comprising a mix of said first species and said second species from a feed arrangement of said spiral separator;
• and
• a more downstream region, adapted to be provided in said spiral separator with a splitting arrangement provided at or immediately adjacent the more downstream region, to split a concentrated band of the first species from the rest of the flow in the spiral trough;
• wherein the more upstream region of the spiral trough has a trough floor region, and provides an effective cross-trough floor slope relative to the horizontal, which reduces from 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 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, immediately adjacent a downstream end of the spiral trough;
• and
• wherein the trough provides an effective cross-trough floor slope which reduces between the more upstream region and the more downstream region, and wherein the reduction in effective cross-trough floor slope in a turn at the downstream region of the spiral trough is provided by the pitch of a more radially outer region of the spiral trough and the pitch of a more radially inner region of the trough being different over said turn of the spiral trough, and wherein the difference in pitch over said turn is between 0.08 and 0.18 times the radial distance between said more radially outer region and said more radially inner region.

A spiral separator for separating more-desired material from less-desired material, the spiral separator comprising:

• a feed arrangement for feeding a slurry of mixed more-desired material and less-desired material;
• a spiral trough;
• and
• a splitting arrangement for off-take of a concentrate band of more desired material;
• wherein the spiral trough is configured to provide a trough floor region with an effective cross-trough floor slope which reduces by between 5 and 8 degrees in a turn immediately upstream of the splitting arrangement;
• and
• wherein the trough provides an effective cross-trough floor slope which reduces between a more upstream region of the trough and a more downstream region of the trough, and wherein the reduction in effective cross-trough floor slope in a turn at the downstream region of the spiral trough is provided by the pitch of a more radially outer region of the spiral trough and the pitch of a more radially inner region of the trough being different over said turn of the spiral trough, and wherein the difference in pitch over said turn is between 0.08 and 0.18 times the radial distance between said more radially outer region and said more radially inner region.