Although three rather extensive researches on the system gold-mercury have been published within the last ten years, the disagreement in the various results is most remarkable, particularly at lower temperatures. Quite recently rather precise results on the system silver-mercury, using a new type of solubility tube, have been published by Sunier
Many types of efficient placer gold recovery equipment are available today. The choices facing those designing a recovery system for a particular site are not easily made. A major consideration, of course, is cost versus recovery, but other factors must also be considered when designing an effective system. The size distribution of the gold
Bowl concentrators have been used only to a limited extent in small placer operations. The two most popular designs were the Ainlay and Knudsen bowls. There is little difference in design and operation between the two, except for riffle design and minor variations in bowl size and shape. They were used
An interesting variation of the spiral concentrator is the rotary table. This device is available from a variety of manufacturers under many trade names. Basically, the rotary table consists of a flat, circular plate in which a spiral pattern has been molded or cut. It is usually mounted on a frame with a wash water bar running laterally from
Another concentrator device based on the spiral design is the helix. A helix is a cylinder lined with spirals along the inside. Helixes are suitable for use as roughers or cleaners, depending on their size. Sizes range from small 1 foot diameter by 5 feet long cleaners to large roughers 8 feet in diameter and 40 feet long (Photo 8).
Pinched sluices have been used for heavy-mineral separations for centuries. In its elementary form, the pinched sluice is an inclined trough 2 to 3 feet long, narrowing from about 9 inches in width at the feed end to 1 inch at discharge. Feed consisting of 50-65% solids enters gently and stratifies as the particles flow through