铅、铬、镉在低温烧结陶瓷中的长期稳定化机理

The accumulation of metal-laden industrial hazardous waste has become a major environmental concern due to the release of hazardous Pb, Cr, and Cd to the environment without proper treatment. Nowadays, ceramic technology has been accepted as one of the most effective methods for heavy metal stabilization, and the metal-laden sludge can be beneficially blended into a variety of ceramic products, such as bricks, tiles and refractory aggregates. Current policy for metal-bearing waste focuses on developing its potential to be recycled into usable products as a waste-to-resource strategy. However, the efficiencies of these strategies and many metal stabilization mechanisms need to be fully understood to ensure product safety in long-term applications. Moreover, the generalization of ceramic technology for heavy metal stabilization is always limited due to a relatively high temperature of ceramic sintering. Therefore, this study intends to develop low-temperature reacting ceramic matrices to incorporate Pb, Cr, and Cd, and find out the stabilization mechanisms for three metals. An intensive study will be conducted on the explication of crystalline structures for Pb, Cr, and Cd incorporation, and the quantitative X-ray diffraction techniques will be adopted to quantify the stabilization efficiencies and partition ratios of Pb, Cr, and Cd in the ceramic products. Furthermore, a prolonged leaching procedure will be carried out to examine the stabilization effect of Pb, Cr, and Cd in the ceramic matrices. Through the goal of pursuing lower temperature ceramic systems to react with the target metals, a novel and cost-effective stabilization methodology will be provided for heavy metals, and a “waste-to-resource” strategy will be developed to realize a safe utilization for metal-laden industrial wastes.

工业危废中铅、铬、镉的迁移转化对生态环境造成严重危害，成为亟待解决的环境问题。高温陶瓷烧结技术在稳定重金属的同时将工业废物资源化利用，成为当前工业危废处理的最有效手段之一。目前研究主要集中于陶瓷产品性能测试，并没有明确重金属在陶瓷基体中稳定化的关键机理，同时高温烧结因能耗过高也限制了该技术的推广。因此，不仅需要建立低能耗烧结陶瓷体系，并且需要对该体系中重金属的稳定化机理进行系统的理论研究。本项目选择含铅、铬、镉的工业危废，加入不同种类及配比的陶瓷原材料形成低温烧结陶瓷体系，结合X射线衍射精修定量技术，解析铅、铬、镉赋存相的晶体结构，定量铅、铬、镉的稳定化效率，明确铅、铬、镉在赋存相中的分配行为，揭示烧结过程中铅、铬、镉的稳定化机理。本项目的实施，将为陶瓷烧结技术在电镀污泥、电池工业污泥、铬渣等重金属工业废物的推广提供理论基础，为固体废物协同处置及可持续资源化利用提供科学依据。

工业危废中铅、铬、镉的迁移转化对生态环境造成严重危害，成为亟待解决的环境问题。本研究旨在基于固废组分特征建立低温烧结陶瓷体系，系统研究和深入探讨该反应体系中铅、铬、镉等重金属的稳定化机理，解析铅、铬、镉赋存相的晶体结构信息，定量研究重金属稳定化效率及分配行为，揭示固废主要组分对重金属迁移转化及稳定化的影响机制，进一步探究多种重金属共存体系中的协同稳定化及竞争作用机制，评估烧结后产品的重金属浸出行为及稳定化效果。在上述研究基础上，设计及研发微晶玻璃、陶瓷膜等产品，进一步拓展固废的高值化利用空间。研究重要成果归纳如下：温度逐渐升高可以促进镉与体系中的二氧化硅反应，生成CdSiO3，而温度继续升高可促进CdAl2(SiO4)2的生成。铬与镍或铜共存时，可与体系中的铁铝等三价金属一起同镍或铜相结合，生成尖晶石固溶体结构（NiCr2-yFeyO4/CuFexAlyCr2-x-yO4）。且结果发现，烧结温度1150°C时铬向尖晶石结构的迁移转化率接近100%。研究进一步引入城市污泥焚烧灰渣建立低温烧结陶瓷体系，并研究了铅与其他重金属的共稳定化行为。铅的主要赋存物相为PbAl2Si2O8且在650-900°C范围内随温度升高而增加，但在900-1000°C的产品中随着样品呈现玻璃化而峰值逐渐消失。浸出结果表明，上述重金属在烧结后的产品中均可以实现有效稳定化，相较于以往的研究，达到最优稳定化的烧结温度保持在900-1100C范围内，实现了低温烧结陶瓷体系的构建。研究进一步以镍泥为例拓展了实际工业污泥稳定化的定量研究，同时探讨了硅钙等主要成分对重金属稳定化行为的影响。最后，研究构建复杂低温烧结体系，研究铅镉镍等重金属的共稳定化，结果同样表明，上述重金属在1000°C烧结的陶瓷产品中实现了有效稳定化。该项目的实施及所取得的理论成果，将为陶瓷烧结技术在电镀污泥、电池工业污泥、铬渣等重金属工业废物的推广提供理论基础，为降低能耗实现固体废物协同处置及可持续资源化利用提供有力的科学依据。