Thanks to the weathering, raw gold ore exposed in the air can be crushed gradually into gold particles and cuttings. With the help of external force, minerals with heavier particles are enriched in hillside, bed, and lake shore. Once those settlings have mining valve, they become placer gold. Placer gold beneficiation working is classified into preparing work and separating work. Now, common placergold beneficiation equipment is briefly introduced.
Placer gold has coarser spare particles and good dissociation. Usually, high coarse concentrate is achieved by crushing, desliming, and then gravity separating. Minerals whose particles are more than 100mm exist in mined placer gold. Before separating, those coarse minerals should be crushed, and in case gold included in them are lost to tailings. Meanwhile, a part of gold is adsorpted in rock with coarse particle sizes. During the crushing process, this part of gold should be separated down to improve gold recovery rate. There are rare fine minerals containing gold. It is difficult in recovery. However, slurry of those fine minerals has heavy influence on later gravity separating, and fine slurry should be removed in preparing work. Placer gold beneficiation equipment used in preparing work is cylindrical screen and flat screen. Crushing and desliming are achieved by vibration of water and screen shaft. In separating work, commonly used equipment is shaking table, jig, spiral chute, and spiral concentrator. Minerals are separated and enriched according to differences of particle sizes, shapes, and weight. There are three methods of processing coarser minerals achieved by gravity separating. First one is gold is washed out by pans, and then, heavy sand is abandoned. Second one is HG is mixed by amalgamation barrel to achieve amalgam, and then, heavy sand is abandoned. And last one is when gold is achieved by washing or mixing GH, heavy sand is sent to refining plant. Methods of magnetic separating and electrical separating are used to recovery kinds of heavy sand minerals.