Study On Catalytic Degradation Of Dye Wastewater By Blast Furnace Dust

Every year there are tens of millions of tons of metallurgical dust,metallurgical solid waste pollution disposal has become a major problem in the iron and steel industry.Blast furnace dust is rich in iron and carbon elements,so it can be used as raw material for sinter production.However,the elements such as zinc,lead,potassium and sodium in the dust not only affect the quality of the sintered products,but also accumulate in the inner wall of the blast furnace,thus affecting the operation and life of the blast furnace.Therefore,it is urgent to find a green and high value-added way to use metallurgical dust,reduce the environmental harm of metallurgical solid waste storage,waste into treasure.Dye wastewater is a kind of industrial wastewater with high toxicity,high chroma,many organic pollutants and high degradation difficulty coefficient,which seriously damages the water,soil and other environment.Conventional water treatment methods are difficult to destroy the complex structure of dyes,but the rapid development of advanced oxidation technology in recent years makes it possible for all kinds of dye wastewater to be completely degraded into CO₂and H₂O.Photo-Fenton technology is widely used in dye wastewater treatment for its advantages of high efficiency,low cost and simple operation.However,the most widely used ferric oxide catalyst is mainly prepared by pure chemical reagent,so the preparation cost is high and the preparation procedure is complicated,which seriously limits the further large-scale application of ferric oxide catalyst.Therefore,it is urgent to find a new type of catalyst which is low cost,high efficiency and easy to reuse.In view of the above pollution problems of blast furnace dust and dye wastewater,this topic first pretreated iron-containing dust of Shagang,and then studied the catalytic degradation performance of dye wastewater by forming heterogeneous photofenton system with H₂O₂ and UV light.The research contents and results are summarized as follows:（1）The basic physicochemical properties of Shagang blast furnace dust were studied by X-ray fluorescence spectrometer,X-ray diffractometer and scanning electron microscope.The results show that the content of K and Cl in sintering machine head ash is up to 34.1%;the content of K and Cl in blast furnace bag dust is 0.498 and 4.88%;and the content of K and Cl in blast furnace gravity ash is very small.（2）The influence of washing process on ash potassium leaching rate of sintering machine head ash was studied by single factor experiment.The results showed that the ratio of liquid to solid,leaching time and leaching temperature all had certain effects on the leaching rate of potassium,especially the ratio of liquid to solid had the most obvious effect on the leaching rate of potassium.When the ratio of liquid to solid was 5:1,the leaching time was 10 min and the leaching temperature was 25℃,the leaching rate could reach 90.78%.The effect of liquid-solid ratio on potassium leaching rate of blast furnace bag dust is also studied.The results show that the potassium content can be reduced to 0.169%when the ratio of liquid to solid is2:1,the leaching time is 30 min and the leaching temperature is 25℃.（3）The effects of the amount of H₂O₂,the amount of catalyst and the initial concentration of dye on the decolorization rate and degradation kinetics of methylene blue were studied with the leaching slag of sintering machine head ash,the leaching slag of blast furnace bag dust and the blast furnace gravity ash as raw materials.The results showed that the three catalysts had excellent catalytic degradation performance and stability,and the decolorization rates were up to 99.49%,96.83%,96.76%,respectively,and all accorded with the pseudo-first-order kinetic reaction.The rate constants were 0.0504 min^-1,0.0344 min^-1 and 0.0331min^-1,respectively.In addition,the catalytic degradation performance of methyl orange was studied using the ash leaching residue of sintering machine head ash as raw material.The results showed that the decolorization rate of methyl orange was up to 93.75%,which confirmed that the blast furnace dust also had excellent catalytic degradation performance for other dyes.