CRYSTALLIZATION SYSTEM AND METHOD FOR PRODUCING SODIUM ALUMINUM FLUORIDE CRYOLITE FROM HYDROFLUORIC ACID WASTE

摘要

A crystallization system for producing sodium aluminum fluoride cryolite from hydrofluoric acid waste includes a crystallization reaction tank, a sodium aluminate tank, a high concentration hydrofluoric acid waste tank, a pH value/fluoride detecting section, a dehydrator, a low concentration hydrofluoric acid waste tank, and a control device. The crystallization reaction tank includes a dispersing plate and the control plate to control the flow rate and liquid form of the sodium aluminate and the hydrofluoric acid waste. The loop-like pH value/fluoride detecting section is in communication with the reaction tank to detect the pH value/fluoride concentration of the water sample which is the aqueous mixture of sodium aluminate and hydrofluoric acid waste. Therefore, the crystallization system is capable of controlling factors affecting the cryolite purity during the operation process, and consequently, the crystallization system can produce cryolite whose purity is good enough for recycling.

主权项

1. A crystallization system for producing sodium aluminum fluoride cryolite from hydrofluoric acid waste, comprising:
a control device; a crystallization reaction tank 10 including a top input port 11 and a bottom output port 12, inside the crystallization reaction tank 10 being disposed a dispersing plate 13 which is formed with a plurality of dispersing apertures 131, and a control plate 14 being located above the dispersing plate 13 and formed with a plurality of control apertures 141, an interior of the crystallization reaction tank 10 being divided by the dispersing plate 13 and the control plate 14 into an upper dosing space 101 and a lower reaction space 102, in the upper dosing space 101 being provided a sodium aluminate level meter 15, the lower reaction space 102 being in communication with a discharge control section 16 via the bottom output port 12 to discharge cryolite and low concentration hydrofluoric acid waste produced by reaction, the sodium aluminate level meter 15 and the discharge control section 16 being electrically controlled by the control device 80; a sodium aluminate tank 20 being electrically controlled by the control device 80 and including a batch dosing control section 201 through which sodium aluminate flows from the sodium aluminate tank 20 to the upper dosing space 101 of the crystallization reaction tank 10; a high concentration hydrofluoric acid waste tank 30 being electrically controlled by the control device 80 and including a batch dosing control section 301 through which high concentration hydrofluoric acid waste is transported from the high concentration hydrofluoric acid waste tank 30 to the lower reaction space 102 of the crystallization reaction tank 10; and a pH value/fluoride detecting section 40 including a pH meter 41 and a fluoride meter 42 which are electrically connected by wires and controlled by the control device 80, the pH meter 41 including a first passage 43 which is in communication with a bottom of the lower reaction space 102 of the crystallization reaction tank 10, the fluoride meter 42 including a second passage 44 which is in communication with a top of the lower reaction space 102.