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煤基灰/渣的大宗固废资源化利用现状及发展趋势

Resource utilization status and development trend of bulk solid waste of coal-based ash/slag

  • 摘要: 近年来,煤炭工业快速发展,为国民经济运行提供了重要能源保障和原料支撑,与此同时,燃煤电厂、工业和民用锅炉等设备在煤燃烧和气化工艺过程中,产生大量的煤基灰/渣(粉煤灰、燃煤炉渣、气化渣)等工业固体废弃物,对生态环境造成了较大影响。以粉煤灰和气化渣为代表的煤基灰/渣为例,我国每年排放约8亿t粉煤灰和3500万t气化渣,但是受限于国家能源结构、产业政策等因素的影响,以及煤基灰/渣的资源分布、产地性质的制约,目前,煤基灰/渣的高效资源化利用率还有待提升,其中,粉煤灰的综合利用率为70%、气化渣的综合利用率仅为30%,未来我国大宗固废仍存在产量大、资源利用不充分、综合利用产品附加值低等困境。因此,进一步提升大宗固废综合利用水平,全面提高资源利用效率,积极落实国家“碳达峰”和“碳中和”相关政策,完成煤炭工业“十四五”发展规划中相关工作,是当前煤炭开发利用需面对的重要问题。基于此,针对煤基灰/渣的性质,开展了大量的探索,如分级、分选、提质等技术研究,开发了具有针对性的工艺技术及装备,部分实现了煤基灰/渣的大宗固废资源化利用和高附加值利用。鉴于煤基灰/渣具有比表面积大、孔隙结构发达、含碳量偏高、铝硅含量丰富等特性,目前已经作为原料广泛应用于建工建材、环保、生态、化工等领域。文章分别从大宗固废资源化利用和深加工高附加值利用两个方面对煤基灰/渣进行了阐述。①建工建材等应用领域仍是提升煤基灰/渣大宗固废资源化利用的重要方向,但由于煤基灰/渣资源化利用存在脱碳与炭−灰分离技术装备有待完善、脱水与干燥困难、重金属可能存在沉淀等问题,后续有待深入研究;②提取有用组分并用于功能性碳材料制备、环境污染治理等领域可实现煤基灰/渣深加工高附加值利用,但需对生产工艺环节中产生的酸碱性或重金属废液进行有效处理,从而减少对环境的污染。针对煤基灰/渣在大宗固废资源化利用中所存在的问题,探讨了其未来发展趋势,以期为煤基灰/渣的大宗固废资源化利用以及煤化工行业高端化、低碳化、绿色化发展提供借鉴与参考。

     

    Abstract: In recent years, the rapid development of the coal industry has provided important energy security and raw material support for the national economy. At the same time, coal-fired power plants, industrial, civil boilers and other equipment produce large quantities of coal-based ash/slag (fly ash, coal-fired slag, gasification slag) and other industrial solid waste during the coal combustion and gasification processes, which have a significant impact on the ecological environment.Taking coal-based ash/slag represented by fly ash and gasification slag as an example, China emits about 800 million tons of fly ash and 35 million tons of gasification slag every year. However, limited by the national energy structure, industrial policy and other factors, as well as the resource distribution of coal-based ash/slag and the nature of the origin of the constraints. At present, the efficient resource utilisation of coal-based ash/slag is still to be improved. Among them, the comprehensive utilization rate of fly ash is 70%, and that of gasification slag is only 30%. In the future, China's bulk solid waste still faces the dilemma of large output, inadequate utilization of resources and low added value of comprehensive utilization products. Therefore, to further improve the comprehensive utilization level of bulk solid waste, comprehensively improve the efficiency of resource utilization, actively implement the national ‘carbon peak’ and ‘carbon neutrality’ related policies.Completing the relevant work in the ‘14th Five-Year Plan’ of the coal industry is an important issue for coal development and utilisation at present. Based on this, a lot of exploration has been carried out for the properties of coal-based ash/slag, such as classification, separation, quality and other technical research. Targeted process technologies and equipment have been developed, partially realising bulk solid waste resource utilisation and high value-added utilisation of coal-based ash/slag. In view of the characteristics of coal-based ash/slag with large specific surface area, developed pore structure, high carbon content, rich in aluminium and silicon content, it has been widely used as a raw material in construction and building materials, environmental protection, ecology, chemical industry and other fields.In this paper, the utilization of bulk solid waste resource and the utilization of high value-added in deep processing of coal-based ash/slag are discussed. ① Construction, building materials and other application fields are still important directions to improve the resource utilization of bulk solid waste of coal-based ash/slag. However, due to the problems of coal-based ash/slag resource utilization, such as decarbonization, carbon-ash separation technology, equipment need to be improved, difficulties in dewatering and drying, and possible precipitation of heavy metals, etc., which need to be followed up with in-depth research. ② Extraction of useful components and used in the preparation of functional carbon materials, environmental pollution control and other fields can realize the deep processing of coal-based ash/slag with high value-added utilization. However, it is necessary to effectively treat the acid, alkali or heavy metal waste liquid generated in the production process to reduce the pollution to the environment. In view of the existing problems in the resource utilization of bulk solid waste of coal-based ash/slag, its future development trend was discussed.It is expected to provide reference for the resource utilization of bulk solid waste of coal-based ash/slag as well as the high-end, low-carbon and green development of the coal chemical industry.

     

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