Granular cryolite and preparation method capable of regulating and controlling molecular ratio thereof

Abstract

The invention discloses granular cryolite and a preparation method capable of regulating and controlling a molecular ratio thereof. The cryolite is mainly composed of, by mass, 52-55% of F, 12-15% of Al and 28-33% of Na according to a molecular ratio of 2.0-3.0, the cryolite is naturally granulated, and weight of the cryolite less than 1mm in grain diameter is less than or equal to 15%. The preparation method includes following steps: (1), adding sodium fluosilicate into cryolite mother liquid, adding ammonia water to enable pH value to be 8.0-9.5, and performing press filtering to obtain a sodium fluoride and ammonium fluoride mixed solution; (2), adding the sodium fluoride and ammonium fluoride mixed solution and a sodium aluminate solution into a synthesis tank to obtain cryolite slurry; (3), adding an aluminum-based compound into the cryolite slurry, and performing stirring reaction, solid-liquid separation and drying to obtain the granular cryolite. The granular cryolite is adjustable in the molecular ratio within a range of 2.0-3.0. The preparation method is simple, convenient and easy to operate, and the cryolite mother liquid is recyclable, low in energy consumption and low in pollution.

Description

Technical field [0001] The invention relates to a granular cryolite and a preparation method thereof, in particular to a granular cryolite and a preparation method capable of regulating its molecular ratio. Background technique [0002] The chemical name of cryolite is sodium fluoroaluminate, and the molecular formula is Na 3 AlF 6 . Cryolite is divided into natural and artificial. It is mainly used as a flux for electrolytic aluminum smelting, abrasion-resistant filler for rubber and grinding wheels, a brightener for enamel, and a flux for metals. The traditional process of sodium cryolite production is the fluoroaluminate soda method, and the emerging technologies include the clay brine method and the sodium fluorosilicate method. [0003] However, the sodium fluorosilicate method as an emerging process has certain drawbacks: in the process of producing cryolite with sodium fluorosilicate, the causticity ratio of sodium aluminate used cannot reach 1.0. If the cryolite mother liq...

AI Technical Summary

Problems solved by technology

[0004] The cryolite produced by the disclosed technical schemes such as CN1259242C, CN1043033C, CN1225897A, CN1300879A, CN1260130C are all powdery cryolite, to produce granular cryolite must carry out post-pressing, not only cost rises, and the granular ice that dry product is pressed out is easy Another technical defect in the production of cryolite by the above scheme is that the molecular ratio cannot be adjusted in the production process, some can only produce cryolite with high molecular ratio, and some can only produce cryolite with ordinary molecular ratio