Synergistic extraction and separation of valuable elements from high-alumina fly ash with carbochlorination method

高铝粉煤灰中有价元素的碳热氯化协同提取分离

A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to conduct carbochlorination of the fly ash within the temperature range from 700 to 1000℃.The experimental results demonstrated that under the optimal conditions,the carbochlorination efficiency for Al,Si,Ca,Ti,and Mg exceeded 81.18%,67.62%,58.87%,82.15%,and 59.53%,respectively.The XRD patterns indicated that Al and Si in the mullite phase(Al_(6)Si_(2)O_(13))were chlorinated during the carbochlorination process,resulting in the formation of mullite mesophases(Al_(4.75)Si_(1.25)O_(9.63) and Al_(1.83)Si_(1.08)O_(4.85)).After the carbochlorination process,Al was accumulated as AlCl_(3) in the condenser,while SiCl_(4) and TiCl_(4) were enriched in the exhaust gas,and CaCl_(2),MgCl_(2),and unreacted oxides remained in the residue for further recycling.

提出一种高铝粉煤灰有价组元协同提取分离的新工艺。热力学分析结果表明,粉煤灰的碳热氯化反应在700~1000℃之间进行可以获得较好的氯化性能。实验结果表明,在优化条件下,粉煤灰中铝、硅、钙、钛和镁的碳热氯化效率分别达到81.18%、67.62%、58.87%、82.15%和59.53%。XRD分析结果表明,在碳热氯化反应过程中,莫来石相(Al_(6)Si_(2)O_(13))中的铝和硅被氯化,从而形成莫来石中间相(Al_(4.75)Si_(1.25)O_(9.63)和Al_(1.83)Si_(1.08)O_(4.85))。碳热氯化反应完成后,铝以氯化铝形式在冷凝器中冷凝沉积,氯化硅和氯化钛在尾气中富集,氯化钙、氯化镁和未反应的氧化物留在残留物中进一步循环利用。