Abstract: With the booming development of the electrolytic aluminum industry, both modern 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 μm<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.

Key words: aluminum hydroxide, particle classification, sandy alumina, dispersive fluidization, screening

摘要： 随着电解铝行业的蓬勃发展，现代大型预焙电解槽和干法净化技术均需砂状氧化铝作为生产原料。但国内氧化铝企业生产多为中间状氧化铝或“准砂状”氧化铝，且颗粒粒度呈周期性变化，产品质量与世界先进水平差别较大，主要原因是原料差异及现有氢氧化铝颗粒分级技术不达标所致。因此，亟需研制高精准、高效率的氢氧化铝湿颗粒分级装置，实现大颗粒、较窄粒径的高质量砂状氧化铝(+80 μm≥90%，-45 μm<8%)生产。本工作首先对国内外常用的、规模化应用的湿法颗粒分级技术进行综述，对水力分级技术、湿法筛分技术及新型耦合分级技术进行分析，随后提出将水力分级与筛网分级相结合、可应用于氢氧化铝颗粒苛刻分级要求的新型“流化-筛分”精准分级方法，最后研制出可实现规模化连续生产的小试分级装置(3.3 m3/h)，且该方法通过了生产企业的现场侧线验证。该新型颗粒精准分级技术不仅有望在氧化铝行业实现节能减排、转型升级、降低生产成本并能取得显著经济效益，还可促进选矿、精细粉体行业的迅速发展，具有重要的实用和推广应用价值。

关键词: 氢氧化铝, 颗粒分级, 砂状氧化铝, 散式流态化, 筛分