煤气化渣综合利用研究进展

我国富煤、贫油、少气的能源结构特点,石油、天然气对外依存度高的实际情况以及对煤炭高效清洁利用的重视赋予了煤化工产业发展的机遇,作为煤化工产业龙头的煤气化技术在中国蓬勃发展。随着煤气化技术的大规模推广,煤气化渣的堆存量及产生量越来越大,造成了严重的环境污染和土地资源浪费,对煤化工企业的可持续发展造成不利影响,煤气化渣处理迫在眉睫。笔者介绍了煤气化渣的产生及其带来的环境问题,煤气化渣的基本特点,综述了国内外煤气化渣在建工建材(骨料、胶凝材料、墙体材料、免烧砖)、土壤水体修复(土壤改良、水体修复)、残碳利用(残碳性质、残碳提质、循环掺烧)、高值化利用(催化剂载体、橡塑填料、陶瓷材料、硅基材料)等方面的研究进展,提出了煤气化渣综合利用思路。煤气化渣主要由SiO2、Al2O3、CaO、Fe2O3、C组成,气化细渣残碳含量较气化粗渣高,煤气化渣的主要矿相为非晶态铝硅酸盐,夹杂着石英、方解石等晶相,富含硅、铝、碳资源的化学组成特点和特殊的矿相构成是煤气化渣回收利用的基础。目前煤气化渣规模化处置利用主要聚焦在建工建材、生态治理等方面,但因其碳含量高、杂质含量高等特点,导致建工建材掺量低、品质不稳定,生态治理二次污染严重等问题,经济和环境效益差。在资源化利用方面,结合煤气化渣资源特点,目前主要在碳材料开发利用、陶瓷材料制备、铝/硅基产品制备等方面引起广泛关注,虽然经济效益相对显著,但均处于实验室研究或扩试试验阶段,主要存在成本高、流程复杂、杂质难调控、下游市场小等问题,无法实现规模化利用。为了提高企业经济效益,同时解决企业环保难题,结合煤气化渣堆存量大、产生量大、处理迫切的现状以及富含铝、硅、碳资源的特殊属性,建议煤气化渣的综合利用思路为"规模化消纳解决企业环保问题为主+高值化利用增加企业经济效益为辅"。开发过程简单、适应性强、具有一定经济效益的煤气化渣综合利用技术路线,是目前煤气化渣利用的有效途径和迫切需求。

Research progress on comprehensive utilization of coal gasification slag

The energy structure characteristics of rich coal,poor oil and little gas,the actual situation of high external dependence of oil and natural gas,and the attention to the efficient and clean utilization of coal in China give the coal chemical industry development opportunities. As a leading technology in coal chemical industry,coal gasification technology is developing rapidly in China. With the large-scale promotion of coal gasification technology,the storage and production of coal gasification slag become larger and larger,which has caused serious environmental pollution and waste of land resources,and has adversely affected the sustainable development of coal chemical enterprises. The treatment of coal gasification slag is imminent. The background of coal gasification technology,the generation of gasification slag and its environmental problems,and the basic characteristics of coal gasification slag were introduced. The research progress on utilization of coal gasification slag at home and abroad was reviewed,including construction and building materials( aggregate,gelling material,wall material,non-burnt brick),soil and water restoration( soil improvement,water body repair),residual carbon utilization( residual carbon properties,residual carbon upgrading,cycle blending combustion),high value utilization( catalyst carrier,rubber-plastic filler,ceramic material,silicon-based material),etc. Suggestions for comprehensive utilization of coal gasification slag were proposed.The coal gasification slag is mainly composed of SiO2,Al2O3,CaO,Fe2O3 and C. The residual carbon content of gasified fine slag is higher than that of coarse slag. The main mineral phase of coal gasification slag is amorphous aluminosilicate,which is mixed with quartz,calcite and other crystalline phase. The chemical composition characteristics are rich in silicon,aluminum,carbon resources and the special mineral phase composition is the basis for the recovery and utilization of coal gasification slag. At present,the large-scale utilization of coal gasification slag is mainly focused on construction materials and ecological treatment. However,its characteristics of high carbon content and high impurity content lead to low incorporation of construction materials,unstable quality,and serious secondary pollution caused by ecological control. The economic and environmental benefits are poor. In terms of resource utilization,combined with the characteristics of coal gasification slag resources,it has attracted extensive attention in the development and utilization of carbon materials,the preparation of ceramic materials,and the preparation of aluminum/silicon based products. Although the economic benefits are relatively significant,they are all in the stage of laboratory research or expanding test. There are many problems,such as high cost,complicated process,difficult control of impurities,small downstream market and so on,which cannot realize large-scale utilization. In order to improve the economic benefits of enterprises and solve the environmental problems of enterprises,combined with the current situation of large coal gasification slag heap,large production volume,and urgent treatment,as well as the special properties rich in aluminum,silicon and carbon resources,it is suggested that the idea of comprehensive utilization of coal gasification slag is to solve the environmental problems of enterprises mainly by scale consumption and to increase the economic benefits of enterprises supplemented by high-value utilization. It is an effective way and urgent demand to develop a comprehensive utilization technology route of coal gasification slag with simple process,strong adaptability and certain economic benefit.