At a time when transportation infrastructure construction is developing rapidly, asphalt mixing plants are the key "material factories" for road construction. The exhaust particulate matter, exhaust gas from the asphalt tank breathing port, asphalt fume from recycled material drying, exhaust gas from finished materials, and exhaust gas from secondary combustion of burners generated during the production process have become the focus and difficulty of air pollution prevention and control. How to efficiently treat these exhaust gases and achieve green production is an urgent problem to be solved in the industry.
The exhaust particulate matter in asphalt mixing plants mainly comes from sand and gravel drying, material transportation and mixing. These particles vary in size, which will not only affect the surrounding air quality, but also may endanger human health. Long-term inhalation can easily cause respiratory diseases. The exhaust gas from the asphalt tank breathing port, due to the volatilization of asphalt during storage, produces organic waste gas containing toxic and harmful substances such as benzopyrene. Benzopyrene is a strong carcinogen, and its emission poses a huge threat to the environment and human health.

The composition of asphalt fume generated during the drying process of recycled materials is complex. In addition to asphalt volatiles, it also contains a variety of pollutants produced by thermal decomposition of residual impurities in the recycled materials. The waste gas of finished materials is mostly generated in the unloading and loading links, and also contains particulate matter and volatile organic matter. If the secondary combustion waste gas of the burner is not properly handled, it will produce pollutants such as nitrogen oxides, aggravating air pollution.
For tail gas particulate matter, bag dust collectors or filter cartridge dust collectors can be used. These devices intercept particulate matter on the surface of the filter material through high-efficiency filtering materials, and the purification efficiency can be as high as 99% or more. For the exhaust gas from the breathing port of the asphalt tank and the asphalt fume from the drying of recycled materials, the combination of low-temperature plasma technology and activated carbon adsorption has a significant effect. Low-temperature plasma can ionize and crack organic waste gas molecules, and activated carbon can further adsorb residual pollutants to achieve standard emissions.
To treat the waste gas of finished materials, gas collection hoods can be set at key points such as the unloading port and the loading port to collect the waste gas and introduce it into the purification device. For the secondary combustion exhaust gas of the burner, the selective catalytic reduction (SCR) technology is used to remove nitrogen oxides. The use of low-nitrogen burners can greatly reduce the amount of nitrogen oxides produced.
Taking a large asphalt mixing station as an example, after the introduction of the above-mentioned comprehensive treatment equipment and technology, the concentration of tail gas particulate matter dropped from 80mg/m3 before treatment to below 10mg/m3, the removal rate of various organic waste gases exceeded 90%, and the nitrogen oxide emissions also met the national standards. By establishing a complete waste gas treatment system, the mixing station not only reduced pollution to the environment, but also improved the social image of the enterprise, achieving a win-win situation of economic and environmental benefits.
The multi-source waste gas treatment of asphalt mixing stations is a systematic project. It is necessary to select appropriate treatment equipment and technology according to the characteristics of different waste gases, and strengthen daily operation and maintenance management. In the future, with the continuous improvement of environmental protection requirements and the continuous innovation of technology, the waste gas treatment of asphalt mixing stations will develop in a more efficient, intelligent and low-carbon direction, contributing to the construction of green transportation and beautiful China.