In the past 30 years, with the constant increase of people’s sense of environment protection, the cost and the maximal recycling rate are not the only things which are considered by the plant designer. Nowadays, it should be considered that the optimal economic benefit can not certainly be obtained by the maximal recycling rate. Thus, we should focus on the efficient and environmental techniques. In the gravity separation process, there is no limitation of the particle size of the finished product. If the minerals are separated completely, the tailing can be discharged when it is as coarse as possible, which means that it is unnecessary to grind the minerals. Besides, it does not need agents in the gravity separation process. Because of the simplification of the processes of the discharge of the tailing and the dispose of the wastes, both of the major cost and the environmental cost can be reduced.
一、The Gravity Separation Process
The ore gravity separation process consists of a series of operations in succession. In essential, the operations can be divided into the preparation operation, the separation operation, and the product dispose operation.
⑴ Preparation Operation
a. Ores are crushed and ground for the separation of the useful mineral particles.
b. The colloidal ores or the ones of lot of clay should be washed.
c. The selective ores are classified according to their particle sizes by the screening method and the hydraulic classification method. After the classification, ores are separated respectively, which is beneficial to select the operation condition, in order to improve the separation efficiency.
⑵The separation operation is the main segment of the ore separation process. Some separation lines are simple while the others are complex. The simple one consists of unit operations, such as the heavy-medium separation.
⑶Product Dispose Operation: Concentrate dehydration, tailing transport and stock pilling.
二、The Gravity Separation Equipment
In order to dispose the ores recently, the necessary equipment should be of the following features: ⑴Large handling capacity. Objectively, the modern ore dispose is required to create benefits by the scale effect. ⑵The effect of the micro-size fraction should be obvious. ⑶The concentration degree is high and the separation indicator is good.⑷It is of low power consumption. Besides, the structure of the gravity separation process is simple, which is convenient for maintenance. The gravity separation machine is the spiral classifier. And the heavy medium separation machines are the jigger, the spiral chute, shaking table, and so on.