The introduction of Spiral concentators

Spiral concentrators are modern, high capacity, low cost units developed for the concentration of low grade ore. Spiral consist a single or double helical sluice warpped around a central support with a wash water channel and a series of concentrate take-off ports placed at regular intervals along the spiral.

To increase the amount of material that can be processed by one unit, two or more starts are constructed aound one central support. New spirals have been developed that do not use wash water. these new units have modified cross sections and only one concentrate take-off port, which is located at the bottom of the spiral. Spiral concentrator are used for the processing of heavy mineral-bearing beach deposits in Floria and Australia.

The first commercially appled spirals were the cst iron Humphreys spirals introduced in the early 1940s. These units spiral concentrators are capable of sustained recoveries of heavy minerals in the size range of 3mm dowm to 75 microns (6-200 mesh). they are suitable for use as rougher, cleaners or scavengers. Feed rates may vary from 0. 5-4 tons per hour per start, depending on the size, shape, and density of the valuable material. Some factors that affect recovery are the diameter and pitch of the spiral, the density of the feed, and the location of splatters and take-off poits and the volume and pressure of the wash water. Individual spirals are easily monitored and controlled, but a large bank of spirals requires nearly constant attention.