Phenomena in late period of seeded precipitation of sodium aluminate solution

https://doi.org/10.1016/S1003-6326(06)60357-9Get rights and content

Abstract

Aiming at seeded precipitation of aluminate solution with high caustic ratio(αk>2.4), corresponding to the late period of seeded precipitation, the influence of different types of seed on precipitation ratio was explained with respect to solution structure in the interface of seed and the evolution of Al(OH)3 growth units in this layer. The effects of solid content and seed size on agglomeration were determined by calculating the particle number of product. The results imply that the solution structure in the interface of seed imposes a notable significance on the process in the late period of seeded precipitation. Agglomeration still exists in this period. However, the agglomeration bodies break in the case of prolonging precipitation due to the mechanical effect, which results in the increase of particle number.

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Cited by (14)

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    Simultaneously, the silica components in the mineral, including kaolinite, quartz, chamosite, and illite react with the alkaline medium, resulting in a 90% dissolution of silica into the liquor. The molar ratio of Na2O to Al2O3 (αk value in the alumina industry) in the leachate of the sub-molten salt process is typically above 10; thus, the crystallization of hydrous sodium aluminate instead of aluminum hydroxide is adopted according to the phase diagram of Al2O3-Na2O-H2O (Cao et al., 2009), and the precipitated hydrous sodium aluminate is re-dissolved to obtain a sodium aluminate solution with an αk value of ~1.5 to precipitate aluminum hydroxide (Abramov, 1988; Li et al., 2006; Liu et al., 2014, 2018). Owing to the higher viscosity due to the silicate and aluminosilicate content (Abramov, 1988; Li and Wu, 2012; Lü et al., 2010; Wu et al., 2010), it is imperative to perform desilication before the crystallization of hydrous sodium aluminate from the solution.

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Foundation item: Project(2005CB623702) supported by the National Basic Research Program of China

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