pH-programmed precipitation with post-upgrading for integrated recovery of Be, Al, and ammonium sulfate from Be-bearing smelting residue

Beryllium (Be) metallurgy generates residues that are simultaneously hazardous wastes and potentially valuable secondary resources, yet practical Be recovery remains challenging because of the strongly coupled Be and aluminum (Al) hydrolysis chemistry and the complex Al–NH 4 + sulfate matrix. The study demonstrates a pH-programmed, two-stage precipitation strategy for the integrated recovery of Be, Al, and NH 4 + from Be-bearing smelting residue. Equilibrium analysis and experimental results consistently showed that Al precipitated preferentially in the weakly acidic range (pH 4.2∼5.0), Be reached a stable precipitation domain only near neutrality (pH about 7.0), thereby creating an operable selectivity window of approximately 1∼2 pH units. Equilibrium modeling reveals a sequential Al-first and Be-second hydrolysis–precipitation pathway through staged pH control. To further mitigate matrix carryover, the process was coupled with targeted post-treatment: heavy-liquid upgrading removed entrained impurities from the Be-enriched precipitate, and selective acid leaching recovered residual Be from the Al-rich fraction. The integrated flowsheet produced high-purity Be(OH) 2 , Al(OH) 3 and (NH 4 ) 2 SO 4 products with mean purities of 98.67%, 99.37%, and 99.47%, and recoveries of 78.52%, 97.74%, and 99.89%, respectively. A preliminary techno-economic assessment indicated a net benefit of approximately 2.13 × 10 4 CNY t −1 . These results demonstrate a simple, selective, and potentially scalable route for the comprehensive utilization of major recoverable components of Be-bearing smelting residue with simultaneous risk mitigation and resource recovery.