Nowadays, enterprises have been able to produce single rare earth oxide, single rare earth metal, rare earth salts, rare earth alloys, rare earth functional materials and other rare earth products, and continue to extend to high added value, refined, deep processed products and downstream application products. With the rapid development of China’s new materials, military industry, aerospace, new energy vehicles and other industries, rare earth metal smelting industry has a bright future. The traditional smelting method has the problems of large energy consumption, pollution and so on. The industry seeks a new method for metal smelting, and the central vacuum system is the best choice. This paper introduces the application of central vacuum system in precious metal refining.
Precious metal refining is a kind of refining technology, which refers to the extraction of metals from ores by roasting, smelting, electrolysis and the use of chemical agents. It can reduce the impurities contained in metals or increase some components in metals to make the metals needed.
Traditional metal smelting methods include pyrometallurgy, hydrometallurgy and electrometallurgy.
The overall structure of Roots vacuum pump in central vacuum system is determined by the arrangement of pump body. At present, there are three types of Roots vacuum pump at home and abroad
1. The air inlet and outlet of the vertical structure are arranged horizontally, and the assembly and connection pipeline are relatively convenient. But the center of gravity of the pump is high, and its stability is poor at high speed, so this type of pump is mostly used for small pump.
2. The air inlet of horizontal pump is on the top and the air outlet is on the bottom. Sometimes, in order to facilitate the installation and connection of vacuum system pipes, the exhaust port can be connected from the horizontal direction, that is, the inlet and exhaust directions are mutually perpendicular. At this time, the exhaust port can be opened from the left or right direction. In addition to connecting one end of the exhaust pipe, the other end is blocked or connected with the bypass valve. The pump has low center of gravity and good stability at high speed. Generally, large and medium-sized pumps use this structure.
3. The two rotor shafts of the pump are installed vertically with the horizontal plane. The assembly clearance of the structure is easy to control, the rotor is easy to assemble and the pump occupies a small area. However, the center of gravity of the pump is high and the gear is inconvenient to be disassembled, and the lubricating mechanism is relatively complex.
Roots vacuum pump has the advantages of quick start, low power consumption, low operation and protection cost, large pumping speed and high efficiency. It is not sensitive to a large number of water vapor and dust contained in the extracted gas. It has a large pumping speed within the pressure range of 100-1 PA, and can eliminate the suddenly released gas quickly.
This pressure scale is just between oil sealed mechanical vacuum pump and dispersion pump. Therefore, it is often connected in series between the dispersion pump and the oil sealed mechanical vacuum pump to improve the pumping capacity of the two pressure scales. At this time it is also known as a mechanical booster pump.
At the same time, the central vacuum system is widely used in the smelting, degassing and rolling of vacuum metallurgy, as well as in the vacuum distillation, vacuum concentration and vacuum drying of food and pharmaceutical industries.
In recent years, with the national policy gradually improving the requirements of energy conservation and environmental protection for the non-ferrous metal industry, the pollution-free and green vacuum metallurgy technology has attracted more and more market attention. The application of central vacuum system in precious metal refining is a new smelting technology. It is believed that more fields can be applied in the future development.