Research On PM_2.5 Production And Emission Characteristics Of Iron And Steel Sintering Machine

Fine Particulate Matter(PM2.5) was harmful to human body and environment, and was the main pollutant that formed haze. Atmospheric particulate matter in the source analysis suggests that iron and steel industry was one of the main sources of PM2.5 in the atmosphere, At present, there were few field experiment researches on PM2.5 production and emission characteristic of iron and steel industry. The thesis selected three production lines of 180 m2, 360 m2 and 400 m2 belt-type sinterer in iron and steel industry as the study objects, using Finnish Dekati company produced Electrical Low Pressure Impactor(ELPI) field measured each spot of PM2.5 mass concentration and partical number concentration; using PM2.5 Impactor collected PM2.5 samples, Then analyzed particulate matter physicochemical property.Sinterer production and emission characteristic research results showed that : before dust removal device, PM2.5 concentration of particle number from the hundreds of thousands to tens of millions grain/cubic centimeter. PM2.5 particle number concentration distribution curve of trend was consistent, and was unimodal and the peak appeares in 0.07~0.12 μm; PM0.38~2.5 concentration showed a downward trend. Like particle number, there was a peak in the 0.1~0.3 μm and its peak value moved to the right compared to the concentration of particle number. The concentration of particle number emission reduced to thousands to hundreds of thousands grain/cubic centimeter, and distribution curve of trend was unimodal, while distribution curve peak of concentration was in 0.07~0.1 μm; the peak position of PM0.38 moved to the direction of the small particle size, PM0.38~2.5 declined gradually, the peak position of the overall emission of PM2.5 moved to the direction of small particle size., its concentration distribution curve was shown as unimodal distribution, the peak position of PM0.38 moved to the direction of the small particle siz, PM0.38~2.5 rised gradually. As a whole, compared to the concentration of particle matter generated all levels of the particle size, it had decreased to different extent after the dust removal, for large particle matter, the effect of removal was obvious, and small particle matter’s trapping effect was no better than than the large particle matter. The trapping effect of removal was weak for small particle matter, especially for the particle matter with the diameter of 0.1~1 μm. Dust remover reduced the concentration of PM2.5 without changing its distribution characteristics of particle number and mass concentration. After desulfurization, particle number concentration of PM2.5 was between thousands to millions grain/cubic centimeter, concentration distribution curve was shown as unimodal distribution, the peak position was at 0.04~0.07 μm, among concentration of all levels, some level of particle matter did not drop but fall.Sinterer physicochemical property characteristic research results showed that: before the dust removal, PM2.5 morphology was mainly solid spherical particles and irregular particles(lamellar structures, chain, flocculent soot aggregates), the particle size of spherical particles were between hundreds of nm and 2.5 μm. after dust remover, PM2.5 morphology was still mainly solid spherical particles and irregular particles, and some particles’ morphology changed, and a large number of ultrafine submicron particle collided and gathered to form flocculent soot aggregate. After the process of desulfurization, PM2.5 morphology was mainly irregular particles, more submicron particles gathered to form a larger layer, chain of soot aggregates. Among the PM2.5 produces, the concentrations of K+、Mg2+、Ca2+、F-、Cl-、SO42- were relatively stable, for example, the concentration of Ca2+ changed between 1.6~3.1%, the concentration of Cl- changed between 1~2.4%, and the concentration of NH4+ and NO3- volatiled, the concentration of NH4+ fluctuated between 0.4%~0.4%, the concentration of NO3- was in 0.24~15.2%, after the desulphurization Ca2+, SO42- appeared the phenomenon of enrichment. Among PM2.5 trace elements, Pb, Cd, V, Cr of production and emission concentration was basically fluctuating between a few to several hundred ppm, production and emission concentration of Hg, Se, As elements were less than 1 ppb; the concentration of trace elements Hg and As different sinter produces was lower than 0.23 ppb, through desulfurization equipment, Se, V and Pb were volatile, and the concentration of other elements of emission was relatively stable.