Fly ash is a solid waste produced by burning coal in thermal power plants. In the past, it was a useless pollutant. Now, driven by new technologies, it is mixed into concrete as an excellent substitute for cement. The recycling technology of fly ash is relatively mature at present, but there is still a long way to go in terms of market promotion.

Since fly ash can be used in large quantities in cement and concrete, its application has always been the focus of research in my country’s cement industry. At present, 1/3 of coal-fired power plants in my country use the separation method to produce commercial fly ash, which has received good social and economic benefits. With the extensive use of sorting fly ash in water conservancy projects such as the Xiaolangdi Water Conservancy Project on the Yellow River and the Three Gorges Water Conservancy Project on the Yangtze River, my country’s fly ash separation technology has been gradually developed.
According to reports, as far as the fly ash grinding process currently used in the building materials industry is concerned, whether it is an open-circuit fine grinding process or a closed-circuit fine grinding process, since all ordinary mills are used, this mill will Grinding to 400m2/kg is easy, but it is difficult to grind to 600m2/kg, and there are problems such as a sharp increase in power consumption and an increase in the frequency of accidents. “Specifically, after grinding to a certain fineness, sticky materials and agglomeration tend to occur in ordinary mills, which hinder the progress of high-fine grinding, so that the water requirement ratio of the milled products cannot meet the standard of Class I ash, and the output is at the same time. lower, and the cost of the product goes up.”

The fly ash ultra-fine grinding technology has a reasonable grinding body gradation and a proprietary internal device, which can realize the production of materials with a specific surface area of ​​600m2/kg better than the first-grade ash as long as it meets the requirements of GB/T1596-2005. For ultrafine fly ash, the power consumption for grinding is about 30kwh/t. This special fly ash ultra-fine mill is more suitable for the physical properties of fly ash by technically transforming the lining plate, partition plate and grinding body gradation of the ball mill. and chemical activity, reducing the water demand ratio.

Ground fly ash plus activator under the combined action of mechanical activation and chemical activation, the mixing amount of ground fly ash is 45%, and other conditions are the same, the concrete structure is denser and the strength is higher.

At present, there are nearly 200 comprehensive utilization technologies of fly ash in my country, of which nearly 70 have been implemented and applied, mainly used in building materials, construction projects, road engineering, extraction of minerals from fly ash and high-value utilization. These technologies are relatively mature and use a large amount of ash, which is not only easy to popularize and use, but also brings obvious economic and environmental benefits.
The coal quality and the combustion conditions of power plant boilers in different parts of my country are different, and the quality of fly ash varies greatly from place to place. In general, the comprehensive utilization level of fly ash is far behind that of developed countries. Therefore, there are still some problems in the comprehensive utilization of fly ash in my country, such as: the rapid development of the coal-based power industry and the relatively backward comprehensive utilization of fly ash, the problem of insufficient distribution of interests and policy regulation between supply and demand, and weak technical research and development. Decentralization requires further improvement in technology. For example, for the optimal application technology of fly ash in concrete, my country should cite the method of “high-grade cement + high-efficiency fly ash superplasticizer” that is being developed internationally. At the same time, actively carry out research on the control of f-Cao in high-calcium fly ash, and develop the application technology of high-calcium fly ash as a concrete admixture. Focus on the development of special equipment for fly ash utilization with a high degree of automation, and improve the level of technical equipment for fly ash utilization. Carry out technical economical and systematic theoretical research on the comprehensive utilization of fly ash, and formulate reasonable product standards, technical regulations, quality management system and evaluation system for comprehensive utilization of fly ash.

Fly ash science and technology is a comprehensive, edge-sourced science and technology, and the sustainable development of its technology depends on the latest progress of other disciplines. If it can be used reasonably, it can not only be used to resolve the environmental problems caused by fly ash, but also can be used as an emerging resource to develop a variety of practical products, and its prospects are very bright.