生活垃圾气化后无机底渣制备免烧砖及生态风险评价研究

发布时间：2018-03-12 22:24

  本文选题：气化底渣　切入点：免烧砖　出处：《中原工学院》2015年硕士论文　论文类型：学位论文

【摘要】：随着城市化进程的脚步加快,生活垃圾处理问题已经刻不容缓,处理方式也日渐增多,传统方式与新兴方式双管齐下。其中以气化处理技术作为未来主要处置方式之一,其优势在于减量化效果显著,体积可减少90%左右。但仍有15%-25%质量的无机底渣需要填埋,且气化后无机底渣属于一般固体废弃物范畴,可直接进行资源化利用。本试验的研究目的是将生活垃圾气化后无机底渣应用于制备墙体材料免烧砖中,一方面减少水泥基建材中矿物原料的消耗,另一方面解决了垃圾全部资源化利用的瓶颈问题,实现真正意义上的垃圾“零填埋”。对北京市生活垃圾RDF(垃圾衍生燃料)气化底渣进行物化研究与分析,得出气化底渣由无机底渣,残渣碳,渣土,玻璃、陶瓷和砖块、石块等非均质物质组成,粒径范围主要集中在0.16-2.5mm。密度约为2g/cm3,含水率约为17%。矿物组成主要为α-石英,方解石和拉长石。化学组成主要为SiO2,CaO,Al2O3和Fe2O3,含有少量的MgO,K2O和Na2O等,为非放射性物质,属于含有活性氧化硅及氧化铝的潜在活性废渣,需要进行激发。利用层析分析法优选出气化底渣最理想的利用方式为制备水泥基建材中的免烧砖。通过生活垃圾气化底渣制备免烧砖试验研究,分析了原料掺量,成型压力、水分,养护工艺、时间对免烧砖性能的影响,并采用XRD、SEM及EDS等检测手段进行微观分析。试验表明,最优试验配比为m(电石渣):m(粉煤灰):m(水泥):m(气化底渣)=10%:10%:10%:70%;通过灰色关联度分析,得出最优配比方案与试验结果完全一致。最优试验工艺条件为成型压力20MPa,成型水分12%,环境温度19-21℃,相对湿度90%左右,养护箱养护28天。各项性能均满足JC/T422-2007《非烧结垃圾尾矿砖》标准中MU20的要求。在制备过程中,生活垃圾气化后无机底渣的掺量可达到70%。各种胶凝物质相互交织、填充,形成致密的三维空间网络结构。采用改进的BCR法对气化底渣免烧砖进行重金属形态和含量测定,得出其重金属形态基本以可氧化态和残渣态存在,Cd的可氧化态和残渣态占总形态的67.00%,其余重金属均占92.51%以上,稳定不易溶出;免烧砖体的制备对个别重金属固化效果明显,其中As、Cd、Cr、Ni和Zn的固化率分别达到89.82%、79.57%、73.64%、66.73%和88.05%。在此基础上,结合Hakanson潜在生态风险评价和RSP重金属污染评价两种方法,评价了免烧砖中重金属的风险。结果表明:生活垃圾气化底渣免烧砖对环境污染危害程度基本没有,但长期使用中要注意重金属Cd的可能迁移,造成生态环境的间接影响。
[Abstract]:With the rapid development of urbanization, the problem of domestic waste disposal has become urgent, and the treatment methods are increasing day by day. The traditional way and the new way are both in the same direction. Among them, gasification treatment technology is one of the main disposal methods in the future. The advantages are that the reduction effect is remarkable and the volume can be reduced by about 90%. However, there are still 15% to 25% of the inorganic base slag to be landfill, and the inorganic bottom slag after gasification belongs to the category of general solid waste. The purpose of this experiment is to apply the inorganic bottom slag after the gasification of solid waste in the preparation of wall materials without burning bricks, on the one hand, to reduce the consumption of mineral raw materials in cement based building materials. On the other hand, it solves the bottleneck problem of garbage utilization and realizes the "zero landfill" of municipal solid waste in real sense. The physical and chemical research and analysis of municipal solid waste (RDF) gasification bottom residue are carried out. The results show that the gasification slag is composed of inorganic slag, residual carbon, residue, glass, ceramic, brick, stone and other heterogeneous materials. The particle size ranges from 0.16-2.5mm. the density is about 2g / cm ~ 3, the moisture content is about 17.The mineral composition is mainly 伪 -quartz. Calcite and elongated stone. The chemical composition is mainly Sio _ 2, Cao, Al _ 2O _ 3 and Fe _ 2O _ 3, and contains a small amount of MgO _ 2O and Na2O, which is a non-radioactive substance, and belongs to the potentially active residue containing active silicon oxide and alumina. The best way to use gasification bottom slag is to prepare non-fired brick in cement based building materials. The experimental study on preparing no-fired brick from gasification bottom slag of domestic refuse is carried out. The amount of raw material and the forming pressure are analyzed. The effects of moisture, curing technology and time on the properties of fired free bricks are analyzed by means of XRDSEM and EDS. The results show that the optimum ratio of test is m (carbide slag: 1: M). The optimum proportioning scheme is in good agreement with the test results. The optimum technological conditions are as follows: molding pressure 20MPa, molding moisture 12, ambient temperature 19-21 鈩，

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