Research On The Present Situation Of Atmospheric Pollutants From Cement Industry

Cement is one of the most widely used building material and plays a significant role in the national economic development and construction.However the energy consumption and pollution in cement manufacturing industry is very serious.In the cement production process,the crushing,grinding and high temperature calcination result in a large amount of particulate matters,nitrogen oxides,sulfur dioxide and other air pollutants which seriously affected the ecological environment and human health and restricts the development of cement companies.This paper investigated the atmospheric pollutants emissions from cement production lines and analyzed the characteristics of different atmospheric pollutants,and then calculated the amount of fine particulate matter from a typical cement plant and evaluated its environmental impact through AERMOD model.The main conclusions are as follows.1,Through questionnaire and field survey of the 200 cement production lines,we obtained the concentration distribution and discharge coefficient of smoke dust,NO_x,SO2 emissions in cement plant,and estimated that the smoke dust,NOx,SO2emissions from the cement manufacturing industry were about 290,000 tons,1.58million tons and 215,000 tons respectively.2,From the macro data,cement smoke dust emission coefficient was approximately 156g/t clinker.kiln head and kiln rear smoke dust emissions are the main sources,namely 51%and 33%of the total.Comparing different scale cement production lines,the smoke dust discharge coefficient of backward cement is generally high,about 1.4 times of the mean.The result shows that the effect of bag dust collector is superior to electric dust collector.NOx discharge coefficient is approximately 1.14 kg/t clinker.Since all the new dry process production lines are equipped with SNCR denitration system,the emission concentration of most cement plants is maintained at 220³80 mg/m³.Before SNCR denitration,the concentration of small-scale cement plants is generally high,and the denitration cost is also high.The economical and feasible method is suppressing the generation of NO_x at the front end.The average SO₂ discharge coefficient is about 16 g/t clinker.There is a strong relation between SO₂ concentration and combustible sulfur in raw materials.Survey results indicate that about 86%cement plants’SO₂ discharge concentration is less than 100 mg/m³,but there are 6%cement plants exceeding the limit values of200mg/m³,which should be recommended to adopt desulfurization measures.3,Depending on the emission characteristics of particulate matter,the particulate matter sources intensities from a typical cement was calculated.The PM10 and PM2.5emissions inventory was listed.The result shows that organized particulate emission coefficient of cement is 147 g/t clinker which of fugitive particulate emission is 96 g/t of clinker.4,The AERMOD model was applied to simulate the concentration distribution of the PM10 and PM2.5 in the vicinity of a cement plant.Simulation shows that the particulate matter’influence scope is concentrated on the factory area.the PM2.5contribution is small outside the factory.The comparison of concerned points’actual value and the simulating one shows that the simulation value is of great reliability..