Research On The Emission Reduction Of Fine Particulate Matter From Iron Sintering Flue Gas Based On Chemical Agglomeration

Fine particulate matter(PM_10/2.5/1.0)is attracting increasing the attentions due to its unique characteristics that cause great harm to human body and the natural environment.China is a large iron and steel country,and the annual dust emission of iron and steel enterprises is second only to the coal-fired industry.The sintering process is one of the main links of long-process steelmaking,and its fine particulate emissions account for about 40%of the entire steel process.With the improvement of environmental protection standards,how to reduce the emission of fine particles more effectively and efficiently in the sintering process has gradually become the focus of research area for the experts and scholars.In this paper,the chemical agglomeration technology was applied to sintering dust removal system,the ELPI+(electrical low pressure impactor)system was used to monitor the emission behavior of particulates during sintering.The agglomeration solution parameters and spray parameters were carried out to reduce the sintering fine particulates.The results show that the sintering process of particulate emissions range is located in the preheating period,the disappearance of the over-wet layer leads to the weakening of its trapping effect on particulate matter.In terms of mass concentration,it is mainly particles with a particle diameter in the range of 2.5 to 10?m.In terms of number concentration,it is more than 99%of particles with a particle diameter of 1.0?m or less.According to adjusting parameters such as the type,concentration,and p H of the agglomeration solution,the optimal agglomeration solution parameters are0.05%CMC and 0.025%phosphoric acid addition amount,and the emission reduction rates of PM₁₀,PM_2.5,PM_1.0 were 50.99%,36.61%,and 29.11%,respectively.The further reduction of fine particles can also be achieved by properly increasing the injection flow rate of the agglomeration solution and extending the agglomeration time.By analyzing the morphological characteristics of particles before and after the agglomeration,and combining the results of the chemical relationship test of the agglomeration solution to explore the mechanism of agglomeration emission reduction,the results show that the surface of the particles before the agglomeration is smooth,and the morphology and composition of particles of different sizes are significantly different.Most of the small particles are alkali metal chloride,such as KCl,Na Cl,etc.Most of the large particles are metal oxides,sulfides,etc.,such as oxides or composite oxides containing Si,Ca,Al,Mg,Fe,etc.,which can be clearly seen after reunion.There is a phenomenon of connection between particles.Small particles adhere to the surface of large particles,and the surface is rough.The interface chemical relationship(contact angle,surface tension,zeta potential)research results show that by optimizing the parameters such as the type,concentration,and p H of the agglomerating agent,and it is beneficial to improve the surface wettability,activity,and stability of the particulate matter,thereby promoting the connection between particles.The flocculation bridge theory and polymer adsorption theory can better explain the reduction effect of chemical agglomeration technology on sintered fine particles,and provide theoretical support for the industrial application of chemical agglomeration technology.At the same time,combined with some parameters of the sintering process,the sintering machine particle emission trend and the particle emission behavior after electrostatic precipitating were studied,and an industrial application scheme was designed,which provided a new technology for the application of chemical agglomeration technology to the sintering process to achieve fine particle emission reduction.