水泥窑处置城市生活污泥全程中硫与磷的逸出及转化机理

The sulfur and phosphorus are the main semi-volatile elements in municipal sewage sludge (MSS). They will emit and be provided with the toxic substances, such as SOx、H2S、PxOy and others, in the whole disposal course of MSS with cement kiln. These substances have serious detrimental effects to environment and people's health. It will put troubles to the sustainable development of MSS disposal technology with cement kiln. However, the current researches on toxic substances focus on the NOx and heavy metals, and the study on the elements of sulfur and phosphorus mainly pay close attention to cement performance, and the performance-related in the cement field. In view of these problems, the emission ratio, substance composition, toxicity and evolution of combining form on the elements of sulfur and phosphorus in the whole disposal course of MSS with cement kiln will be investigated, and the physical characteristics and main chemical reactions on compound of sulfur and phosphorus will be discussed in this project based on the previous analysis of combining form on sulfur and phosphorus in MSS. The emissions, transformations, and the mechanism on emissions and transformation of sulfur and phosphorus in disposal of MSS with cement kiln will be uncovered, the release of toxic compound of sulfur and phosphorus, the solidification on a part of toxic compound of sulfur and phosphorus, the distribution of other compound of sulfur and phosphorus and these mechanism will be presented. In this project, all kind technologies of analysis and characterization will be used, and the knowledge of physics and chemistry will be employed. The implementation of this project is helpful to take precautions against, to prevent, eliminate and reduce the emission of toxic compound of sulfur and phosphorus, to improve and perfect the basic theory on the MSS disposal with cement kiln, to promote the sustainable development of MSS disposal technology with cement kiln and protect the environment. The completion of this project will provide the theoretical basis and technical support for the disposal of other solid waste with high sulfur and phosphorus content.

鉴于目前毒害物质研究注重NOx和重金属，硫与磷研究主要关注性能相关方面的特点，针对水泥窑处置城市生活污泥（简称：MSS）全程中逸出诸如SOx、H2S和PxOy等毒害物质，对环境、人类健康的危害和水泥窑处置MSS可持续发展的困扰，本课题在前期分析干化MSS中硫与磷存在结合形态等的基础上，拟采用各种分析与表征技术，结合物理与化学知识，通过研究水泥窑处置MSS全程中硫与磷逸出率、逸出物质组成、组成物质毒性、结合形态组成与分布的演变，硫与磷化合物在处置条件下的物理性质、主要化学反应及反应机理，阐明水泥窑处置MSS全程中硫、磷逸出与转化的规律及机理，理清毒害硫与磷物质释放与固化、残留硫与磷驻留于处置全程的规律与机理，为预防、防止、消除和降低毒害硫与磷化合物二次污染，完善水泥窑无害化处置MSS基础理论，促进水泥窑处置MSS的可持续发展和环境的保护，其它含硫与磷固体废弃物的水泥窑无害化处置提供科学依据。

我国城市生活污泥（简称：MSS）年排放量达3000 多万吨（以含水率80%计）。MSS成分复杂，除大量水分外，亦含有难降解有机物、重金属、病原微生物和寄生虫卵等。如处置不善，将带来严重环境问题。借助水泥熟料生产工艺的分解炉、水泥窑，与水泥生料共烧、煅烧处置MSS 的水泥窑处置技术，相较传统MSS 处置技术如填埋、农用和焚烧，水泥窑处置技术有诸多优势。但这些在处置过程中，这些以各种结合形态的硫与磷化合物伴随着处置温度的升高，会释放出诸如二氧化硫等有害物质。本项目的目的在于阐明水泥窑处置MSS全程中硫与磷逸出转化的机理。主要研究内容与结论如下：.1. 水泥窑高温烟气余热干化过程中MSS 中硫与磷逸出、转化及其机理.1) 余热干化中脂肪族硫、芳香族、硫磺酸硫的含量降低，出现亚砜和硫酸盐形态硫, 磷的形态仍为磷酸盐态；.2) 干化温度升高，硫与磷总量有下降趋势，这与污泥中磷的挥发分解有关；.3) 硫含量随干化时间延长而减少，有机硫逸出量增加，硫酸盐则有所增多，磷含量随干化时间增加变化不大；.4) 添加高锰酸钾，污泥中整体硫含量有所增加，但硫含量增加并不明显；添加氧化钙后，污泥中硫含量大大增多，这与三氧化硫和氧化钙作用生成硫酸盐相关。.2. 分解炉共烧过程中干化MSS 中硫与磷逸出、转化及其机理.1) 硫主要以硫酸盐态硫存在，磷以磷酸盐态磷存在，它们含量随MSS掺量增大而增多；.2) 硫与磷在不同预分解温度下含量差别并不大; .3) 不同率值对预分解料中硫与磷的含量无显著影响;.4) 高锰酸钾对硫有显著固化作用，掺加1%时，固硫率提高44.9%，掺加2%时，固硫率提高87.8%。.3. 水泥窑煅烧过程中经共烧MSS 中硫与磷逸出、转化及其机理.1) 污泥掺量与最终硫在水泥熟料中含量无关; 煅烧温度并未显著影响熟料中硫的含量; .2) 熟料中硫含量随硅率增大而降低；熟料中磷含量随石灰饱和系数增大而降低；.3) 高锰酸钾对熟料固硫存在一定作用，但添加量超过2%后，却有相反效果; .4) 掺加污泥后熟料矿物仍以C3S、C2S、C3A和C4AF为主，磷元素以硅酸盐二钙磷酸钙合物存在，且硅酸二钙峰随掺量增大而有所增强。.这些研究结果，为水泥窑协同处置MSS过程中，防止硫与磷释放，促进水泥窑协同处置MSS技术的发展，提供理论依据。