The Vickers Xatal Spirals are a similar approach to the Humphreys spiral. Operation of prototype alluvial processing plant was done Australia by Vickers FME and led to the development of new spiral concepts to overcome the problems inherent in old designs. The features of these new designs were to include increased unit capacity and easier operation and maintenance. The use of polyurethane lined fiber glass and multiple spiral starts per supporting column also resulted in major reductions in spiral plant size and the amount of structural support necessary.
It is important to mention that Vickers FG series were designed as high capacity spiral units which do not require water addition, have product take-off only at the bottom of the spiral and can treat considerable higher feed flow rates such as 4 t/h. for this reason, many of the objections to using spiral in high tonnage operations were removed by the introduction of this easy to operate, capacity unit. The only adjustable parts in this model are the two products cutters in the splitter box. These spiral are particularly useful in application where there is a low proportion of heavy minerals, such roughing and scavenging sections. In cleaning applications or where there are a high proportion of heavy minerals, a spiral design with more selectivity and the option to use wash water to clean the concentrate is likely to be preferred to the more robust FG design. As a consequence, the manufacturer developed the CC series of spirals. These feature easily operated concentrate and wash water splitters, and unblockable open was water and concentrate transport channels. These series of spirals are of easier control than other models. They also had the advantage of higher unit, capacity, adjustable wash water flow, and the ability to be used without was water in some applications.
The first of the series to be commercially used had a diameter of 1 m, compared to the more traditional; 0.6 m. also, it allows three spiral starts per column compared to the usual two. Other model called Wyong Coal Spiral was designed to treat up to 2.5 t/h per start, and a characteristic of this unit is the inner refuse channel that provides an effective internal middlings retreatment and allows misplaced material to be reclaimed to the product.
It is important to indicate that development of spiral concentrators stated in the forties with the introduction of the Humphreys spiral. This was initially used in the processing of chrome-bearing sands, but rapidly found applications in treating beach sands containing different heavy minerals. The original design was augmented by several similar designs, individual mine operators tailoring the original concept to suit local conditions. While Humphreys spiral was constructed of cast iron, other materials such as tire rubber and fiberglass have also been used.