Study On The Desulfurization And Denitrification Performance Of Phosphate Tailings And Its Enhancement Mechanis

Effective treatment of SO₂and NO_xis an important subject of air pollution control.Phosphorus tailings,as a typical bulk solid waste,can be used to remove SO₂and NO_xfrom industrial flue gas to achieve"pollution control by waste"and"waste control by waste",which can provide a new idea for the treatment of industrial flue gas and the resource utilization of phosphorus tailings as well as sustainable economic development.Based on this,this paper proposed a phosphorus tail pulp as absorbent,and with appropriate additives to remove SO₂and NO_xin industrial flue gas.In this study,the simultaneous desulfurization and denitrification performance of phosphorus-tail pulp was analyzed first,and then several additives were selected for screening and the optimal ratio of additives was explored.Based on the optimal ratio,the performance of the combined additives in coordination with the simultaneous desulfurization and denitrification of phosphorus-tail pulp was studied.Finally,the response surface optimization design,desulfurization and denitrification products,mechanism analysis and kinetic calculation were carried out.In the experiment of simultaneous desulfurization and denitration of phosphorus tailings,it is found that phosphorus tailings pulp has good desulfurization performance and can be effectively removed during the experiment,but the denitration performance is poor,only about 56%.The results show that the denitration efficiency increases first and then decreases with the increase of solid-liquid ratio and liquid rotational speed.It decreases with the increase of reaction temperature and gas velocity.It increases with the increase of oxygen content in flue gas.The concentration of SO₂has a great influence on the removal of NO_x.Without the addition of SO₂,the denitrification efficiency is only 48.07%.When the concentration of SO2 is 3000 mg/m³,the removal rate of NO_xreaches 56.44%.The change of NO concentration had no significant effect on the removal rate of SO₂and NO_x.Through the screening experiment of denitration additives,it was found that the co-solvent of C₂H₅NO combined phosphorus tail pulp had better denitration performance,and the denitration efficiency reached 65.62%.Among the oxidants,KMn O₄and phosphorus tail pulp have better denitration performance,and denitration efficiency is 90%.When potassium permanganate and acetamide are combined and the composite ratio is 0.6%-3%,the denitrification effect of the synergistic phosphorus tail pulp is the best,and the highest is about 95%.In the experiment of intensive removal of SO₂and NO_xfrom phosphorus tail pulp with complex additives,the influence of single factors such as solid-liquid ratio on the performance of SO₂and NO_xremoval from phosphorus tailings with additives was explored respectively,and the optimal experimental conditions were obtained:potassium permanganate:acetamide is 0.6%:3%,slurry solid liquid ratio is 4%,liquid rotation speed is 400r/min,reaction temperature is 25℃,flue gas oxygen content is 15%,gas flow rate is controlled at 100m L/min,imported SO₂concentration is 3000mg/m³,imported NO concentration is 621mg/m³.Under the best conditions,the relationship between desulfurization and denitrification efficiency and time was studied.It was found that the desulphurization efficiency was always 100%in 12h of the experiment,increased slowly from 89.86%to 94.20%in 1-3h,maintained at about95%in 4-8h,and decreased after 8h.It decreased to 88.24%at 12h.Then the response surface optimization design was carried out for the gas flow rate,reaction temperature and solid-liquid ratio in the enhanced desulfurization and denitration of phosphorus tail pulp combined with complex additives.The result is:gas flow rate>solid-liquid ratio>reaction temperature.In the design of the model,the relationship between the regression equations of each factor is significant,and the correlation of the simulation equation is also good.Through the analysis of the mechanism,it can be seen that the reaction mechanism in the system is mainly divided into three aspects:（1）Part of SO₂and NO_xin the flue gas are dissolved in the phosphorus tail pulp,generating H⁺;（2）Catalytic oxidation of transition metal ions and acid-base neutralization of alkali metal ions in phosphorus tailings;（3）Strong oxidation of potassium permanganate.The kinetic calculation of SO₂and NO_xwas carried out,and the kinetic equation of SO₂was determined to be r_so2=2.886×10³C_SO2,and the activation energy was 62.83k J/mol.The kinetic equation of NO_xis r_NO=2.857×10³C_NOand the activation energy is 37.73k J/mol.