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 … Read more
Another concentrator device based on the spiral design is the helix gold trommel. 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 … Read more
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 … Read more
The Reichert cone concentrator is based on the pinched sluice concept. If a number of pinched sluices are arranged side by side, with the discharge ends pointed inward, they will form a circular tank with each sluice forming an individual compartment. Removing the sides of each sluice forms a circular tank with an inverted cone … Read more
Air tables use a shaking motion similar to that of shaking tables, but instead of water, air is used to separate heavy minerals. The table deck is covered with a porous material and air is blown up through the deck from a chamber underneath. The chamber equalizes the pressure from the compressor and thus ensures … Read more
The Long Tom is a sluice variant and as you would expect the LONG TOM and the dip box are included here because of their simplicity and potential usefulness. The long tom is a small sluice that uses less water than a regular sluice. It consists of a sloping trough 12 feet long, 15 to … Read more
Rockers are widely used for washing placer samples and under most conditions they are well suited to the needs of the field engineer. It should be noted that since its inception, the American gold dredging industry has, for the most part, used rockers in preference to other types of sample washing equipment. The fact that … Read more
Here is practical, timely information on Placer Mining Methods and equipment used in placer gold recovery. Included is detailed information on equipment, practices, recovery factors, efficiency, design, and, where available, costs. Selected gold recovery operations are described in detail. In addition, the reported efficiency and reliability of various types of equipment used today is presented. One … Read more
The source, amount, and delivered cost of water are important elements in a placer operation. In many cases they determine the type of equipment or mining method used. Water estimates for new or proposed operations are generally based on experience or working data obtained from comparable operations. The water required for various working methods varies … Read more
Another widely used sample washing device is the ordinary sluice box which in its smaller form is sometimes loosely but erroneously called a “long tom”. A sluice in its simplest form is no more than an elongated, rectangular trough fitted with transverse cleats or some other form of riffled bottom. It is operated by essentially … Read more