煤基固废制泡沫陶瓷的发泡工艺研究及应用进展

Research and application progress of foaming technology of foam ceramics made from coal-based solid waste

煤基固体废弃物主要包括采煤和选煤过程中排放的煤矸石、燃煤电厂排出的粉煤灰等,由于无法进行大规模利用并不断堆积造成了严重的环境污染。环保要求的提高使得煤基固废的处理成为煤炭行业的重中之重。泡沫陶瓷是一种具有耐高温特性的新型多孔材料,性能优异,应用范围广。利用煤基固废制泡沫陶瓷,不仅可实现煤矸石和粉煤灰的规模化利用,减少环境污染,还可降低泡沫陶瓷的生产成本。综述了煤矸石和粉煤灰制泡沫陶瓷的主要方法,包括发泡法、添加造孔剂法和有机泡沫浸渍法。不同类型的发泡剂均可在高温下反应或分解产生气体,从而在坯体中产生孔隙,重点阐述了造孔剂的造孔机理,造孔剂添加量对泡沫陶瓷孔分布、孔径大小、孔形貌以及对泡沫陶瓷性能的影响,如气孔率、抗压强度等。对比了不同制备方法的优缺点、应用范围和主要发展方向,其中发泡法可以控制产品的各向异性,但对原材料的要求相对较高,制备工艺条件不受控制;有机泡沫浸渍法可调控泡沫陶瓷的形貌和组成,但需要较长时间排塑;添加造孔剂法可获得形状复杂、气孔结构不同的产品,但造孔剂易发生团聚现象。概述了泡沫陶瓷在不同领域的应用进展,针对不同的应用领域,泡沫陶瓷的性能侧重点也不尽相同,对孔结构要求也不同。由于煤基固废组成成分复杂程度不同,在一定程度上阻碍了泡沫陶瓷的发展,指出了今后煤基固废制备泡沫陶瓷所需解决的问题,即深入研究煤基固废的物料特性和烧结活性,加强对形成过程中孔结构的理论研究,建立煤基固废制不同类型泡沫陶瓷的性能指标体系和性能标准,从而为后续泡沫陶瓷性能的研究和大规模应用提供参考。

Coal-based solid waste mainly includes coal gangue discharged in the process of coal mining and coal washing,and fly ash discharged from coal-fired power plants.Because it cannot be utilised on a large scale,the continuous accumulation of coal-based solid waste caused serious environmental pollution.The improvement of environmental protection requirements makes the utilization of coal-based solid waste become the top priority of the coal industry.Foam ceramics is a new type of porous material with high temperature resistance,excellent performance and a wide range of applications.The use of coal-based solid waste to produce foam ceramics can not only realize the large-scale utilization of coal gangue and fly ash,reduce environmental pollution,but also reduce the cost of foam ceramics production.The main methods of producing foam ceramics from coal gangue and fly ash were reviewed,including foaming method,adding pore former method and the organic foam impregnation method.Different types of foaming agents can react or decompose to generate gas at high temperature,thereby creating pores in the blanks.The pore-forming mechanism of the pore-forming agent was mainly emphasized,including the effect of the amount of pore-forming agent on the pore distribution,pore size and morphology of the foam ceramics,as well as the performance of ceramic foam,such as porosity and compressive strength.The advantages and disadvantages of different preparation methods,the scope of application and main development directions were compared.The foaming method can control the anisotropy of the product,but the requirements for raw materials are relatively high,and the preparation process conditions are not well controlled.The organic foam impregnation method can regulate the morphology and composition of the foam ceramic,but it takes a long time to remove the organics.The pore former method can obtain products with complex shapes and different pore structures,but the pore former is prone to agglomeration.The application progress of foam ceramics in different fields was outlined.For different application fields,the focus of the foam ceramics performance and the requirements for the pore structure are also different.Due to the different complexity of the composition of coal-based solid waste,the development of foam ceramics is hindered to a certain extent.The problems that need to be solved in the production of foam ceramics from coal-based solid waste in the future were pointed out,i.e.,to deeply study the material characteristics and sintering activity of coal-based solid waste,strengthen the theoretical study of the pore structure during the formation process,and establish the performance index system and performance standards of different types of foam ceramics produced from coal-based solid waste,so as to provide a reference for the subsequent research and large-scale application of foam ceramic properties.