Enhanced green remediation and refinement disposal of electrolytic manganese residue using air-jet milling and horizontal-shaking leaching

Abstract

The reclamation and reuse of electrolytic manganese residue (EMR) as a bulk hazard solid waste are limited by its residual ammonia nitrogen (NH4+-N) and manganese (Mn2+). This work adopts a co-processing strategy comprising air-jet milling (AJM) and horizontal-shaking leaching (HSL) for refining and leaching disposal of NH4+-N and Mn2+ in EMR. Results indicate that the co-use of AJM and HSL could significantly enhance the leaching of NH4+-N and Mn2+ in EMR. Under optimal milling conditions (50 Hz frequency, 10 min milling time, 12 h oscillation time, 400 rpm rate, 30 ℃ temperature, and solid-to-liquid ratio of 1:30), NH4+-N and Mn2+ leaching efficiencies were optimized to 96.73% and 97.35%, respectively, while the fineness of EMR was refined to 1.78 µm. The leaching efficiencies of NH4+-N and Mn2+ were 58.83% and 46.96% higher than those attained without AJM processing. The AJM used strong airflow to give necessary kinetic energy to EMR particles, which then collided and sifted to become refined particles. The AJM disposal converted kinetic energy into heat energy upon particle collisions, causing EMR phase transformation, and particularly hydrated sulfate dehydration. The work provides a fire-new and high-efficiency method for significantly and simply leaching NH4+-N and Mn2+ from EMR.