When choosing vacuum pump, alumina plant should pay attention to the following points when considering suction pressure:
① When the carbonation decomposition rate of the filter is too high (commonly known as "over head"), the slurry is suspended, which pastes the filter cloth like jelly, so it is difficult to filter, and the vacuum degree increases rapidly.
② The particle size of aluminum hydrogen in the slurry from the carbon separation tank of alumina production system by sintering process is uneven, especially containing some ultra-fine aluminum hydrogen particles, which is easy to block the filter cloth, and the aluminum hydrogen slurry by sintering process is easy to harden the filter cloth, which will rapidly improve the vacuum degree.
③ Due to the loss along the way and other reasons, the suction pressure at the filter is always lower than the suction pressure at the inlet of the vacuum pump. According to the experience data of each workshop of our company, the loss is about 0.005MPa.
In addition, other accidents may occur. The flat plate filter has experienced a rapid increase in vacuum when washing the filter cloth. Therefore, the suction pressure of the pump should be more margin than normal.