Chimenos J M, Fernández A I, Nadal R, Espiell F
Department of Chemical Engineering and Metallurgy, University of Barcelona, Martí i Franqués 1, 08028, Barcelona, Spain.
J Hazard Mater. 2000 Dec 15;79(3):287-99. doi: 10.1016/s0304-3894(00)00270-3.
The release of heavy metals from MSWI bottom ash has been the key concern in the management of this material. The leaching distribution values obtained from 100 freshly quenched bottom ash samples, according to the German DIN 38414-S4 procedure test, showed the release of lead, zinc and copper to be the main hazards associated with bottom ash utilisation as a secondary building material. Currently, natural weathering of MSWI bottom ash, for an estimated period of 1-3 months, is the most economic treatment available to ensure the eventual utilisation of this material. The leaching of natural weathered bottom ash in the short-term (up to 9 months) was studied. The most significant changes in the bottom ash were found to occur in the first 90 days. At pH values greater than 12, lead, zinc and copper were the main heavy metals to be released from the MSWI freshly quenched bottom ash samples studied. Natural weathering for a period of about 90 days reduced the leaching of heavy metals, stabilising the bottom ash pH to minimise the solubility of metal hydroxides, and enabled the residue to be used as secondary building material. The profile of the pH neutralisation curve is similar to that described by carbonates, which would suggest that the reaction is controlled by CO(2). The formation of insoluble oxides as well as carbonates control the immobilisation of certain heavy metals, e.g. lead and zinc. The leaching of aluminium increases during this short natural weathering stage due to elemental metal oxidation. Aluminium solubility is controlled by the precipitation of gibbsite or other aluminium-sulphate neoformations. The latter may contribute to the immobilisation of heavy metals.
城市固体废弃物焚烧底灰中重金属的释放一直是该材料管理中的关键问题。根据德国DIN 38414 - S4程序测试，从100个新鲜骤冷底灰样品中获得的浸出分布值表明，铅、锌和铜的释放是底灰作为二次建筑材料利用所带来的主要危害。目前，城市固体废弃物焚烧底灰估计1 - 3个月的自然风化是确保该材料最终得以利用的最经济的处理方式。研究了自然风化底灰在短期内（长达9个月）的浸出情况。发现底灰中最显著的变化发生在最初的90天内。在pH值大于12时，铅、锌和铜是所研究的城市固体废弃物新鲜骤冷底灰样品中释放的主要重金属。约90天的自然风化减少了重金属的浸出，稳定了底灰的pH值以最小化金属氢氧化物的溶解度，并使残渣能够用作二次建筑材料。pH中和曲线的轮廓与碳酸盐所描述的相似，这表明该反应受二氧化碳控制。不溶性氧化物以及碳酸盐的形成控制了某些重金属（如铅和锌）的固定化。在这个短暂的自然风化阶段，由于元素金属氧化，铝的浸出增加。铝的溶解度受三水铝石或其他硫酸铝新形成物沉淀的控制。后者可能有助于重金属的固定化。
