腐殖酸固化/稳定化处理锰渣的研究

Research on the solidification/stabilization treatment of manganese slag with humic acid

  • 摘要: 锰渣是电解锰行业产生的废渣,大量堆存浪费资源,并因其含重金属危害生态环境。以腐殖酸为固化剂,解决了以往处理\mathrmNH_4^+-N时过度依赖碱性固化剂的局限性,并有效避免了由此产生的氨气二次污染问题。通过固化/稳定化技术研究腐殖酸投加量、固化时间以及腐殖酸与生石灰的协同作用对锰渣中Mn2+和\mathrmNH_4^+-N固化效果的影响,采用扫描电镜、傅里叶红外光谱进行机理研究。结果表明:当腐殖酸投加质量分数为3.0%,含水率为40.0%,固化时间为10 d时,浸出液中Mn2+和\mathrmNH_4^+-N的浓度分别为4.00和0.42 mg/L,符合GB 5085.3—2007《危险废物鉴别标准 浸出毒性鉴别》中的限值5和10 mg/L,固定化率分别为65.46%和97.05%;采用5.0%生石灰与3.0%腐殖酸协同试验结果发现,其他试验条件不变,对Mn2+的固定化率提高到99.90%,对\mathrmNH_4^+-N的固定化率不变,说明腐殖酸具有协同固化能力。机理研究发现,腐殖酸根与Mn2+和\mathrmNH_4^+-N发生络合吸附和氨化反应,生成Mn2+-腐殖酸较稳定的络合物以及腐殖酸铵。

     

    Abstract: Manganese slag is a solid waste produced by the electrolytic manganese metal (EMM) industry. Its large-scale stockpiling not only wastes resources but also poses a threat to the ecological environment due to its heavy metal content. Humic acid (HA) was used as a curing agent to address the limitations associated with the previous over-reliance on alkaline fixatives for \mathrmNH_4^+-N treatment, effectively avoiding secondary pollution issues caused by ammonia emissions. The impacts of HA dosage, curing time, and the synergistic effect of HA and quicklime on the solidification of Mn2+ and \mathrmNH_4^+-N in manganese slag were investigated by solidification/stabilization technique. Scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FTIR) were used for mechanistic studies. The results showed that when HA was added at a mass fraction of 3.0%, with a water content of 40.0%, and after the solidification for 10 days, the concentrations of Mn2+ and \mathrmNH_4^+-N in the leaching solution were 4.00 and 0.42 mg/L, respectively. These concentrations were within the limits of 5 mg/L and 10 mg/L specified in Identification Standards for Hazardous Wastes- Identification for Extraction Toxicity (GB 5085.3-2007). The solidification rates were 65.46% and 97.05%, respectively. The results of synergistic tests using 5.0% quicklime and 3.0% HA showed that when other test conditions remained unchanged, and the solidification rate of Mn2+ was increased to 99.90%, the solidification rate of \mathrmNH_4^+-N remained unchanged. This indicated that HA had a collaborative solidification ability. The mechanistic studies showed that the HA radical underwent complexation, adsorption, and ammoniation reactions with Mn2+ and \mathrmNH_4^+-N, generating a relatively stable complex of Mn2+-HA and ammonium humate.

     

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