Advances in wet particle size-grading technologies and precise grading of aluminum hydroxide
With the booming development of the electrolytic aluminum industry,both modem large-scale prebaked aluminum reduction cells and dry purification technology require sandy alumina as the production raw material.However,domestic alumina enterprises mainly produce intermediate or"quasi-sand"alumina,and the particle size changes periodically.The product quality differs significantly from the world's advanced level,mainly due to differences in raw materials and substandard aluminum hydroxide particle screening technologies in the prior art.Therefore,it is urgent to develop a high-precision and high-efficiency wet particle classification device for aluminum hydroxide to produce high-quality sandy alumina with large and narrow particle size distribution(+80 μm≥90％,-45 pm＜8％).The commonly employed and large-scale application of wet particle size-grading technologies in domestic and foreign countries are first reviewed.The performance of hydraulic classification,wet screening,and some new coupling classification technologies are analyzed.Then,a new particle grading method of fluidization followed by screening for precise grading of aluminum hydroxide particles is proposed by combining hydraulic classification and sieve screening.Finally,a small-scale grading device(3.3 m3/h)capable of achieving large-scale continuous production is developed and passed the verification of on-site production siding in the production enterprise.This new type of precise particle classification technology is not only expected to realize energy conservation and emission reduction,transformation and upgrading,reduction of production costs,and significant economic benefits in the alumina industry but also promote the rapid development of mineral processing and fine powder industries,having some important and practical application and promotion values.
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