Study On Removal Of SO₂ From Smelting Flue Gas By Copper Slag Tailings And Preparation Of Yellow Sodium Iron Strontium

In China,smelting flue gas is an important source of SO₂ emissions in the atmosphere.With the improvement of air pollutant emission standards in the smelting industry,the purification of SO₂ in smelting flue gas has become an urgent problem to be solved.In this paper,copper smelting flue gas is taken as the research object.Aiming at the characteristics of high concentration of SO₂ and large fluctuation of gas volume in copper smelting flue gas,a method for purifying SO₂ in copper smelting flue gas and preparing yellow sodium iron strontium in desulfurization liquid is proposed.In this study,the slurry in the copper slag tailings is used to absorb the SO₂ in the smelting flue gas to purify the SO₂ in the flue gas,and the iron and sulfate in the desulfurization solution after the reaction are recycled to obtain the yellow sodium iron strontium.After the product,the desulfurized slag after the reaction is transported to the original slag yard after being harmlessly treated.In the study of desulfurization of copper ore slurry,three kinds of characterizations of XRD,XRF and SEM were carried out on the copper slag tailings,and the mechanism of desulfurization reaction was presumed.The desulfurization mechanism is briefly described as:SO₂ in the flue gas is dissolved in the slurry.Oxidation to sulfuric acid under the action of O₂,the generated sulfuric acid reacts with the copper residue tailings,and the divalent iron therein is leached into the slurry,and then the divalent iron liquid phase catalytically oxidizes the SO₂ to remove it.The desulfurization reaction mechanism of the Mn-Fe detachment system formed after the addition of manganese sulfate is a free radical mechanism,and the chain reaction cycle is induced by the rapid formation of SO₃.^-.In order to enhance the desulfurization effect of the slurry,the four inorganic additives of MnSO₄,Fe₂（SO₄）₃,Fe and FeSO₄ were screened.The experimental results were MnSO₄>Fe>Fe₂（SO₄）₃>FeSO₄.After selecting manganese sulfate as the best desulfurization additive,six factors of inlet SO₂ concentration,reaction temperature,flue gas flow rate,solid-liquid ratio,flue gas oxidation amount and manganese sulfate addition amount were investigated for the formed Mn-Fe desulfurization system.According to the experimental results,the optimal parameters for desulfurization of copper slurry determined by the experimental results are inlet SO₂concentration of 1716 mg/m³,reaction temperature of 25°C,flue gas flow rate of 1.2 L/min,and flue gas oxygen content of 19.5%.The solid-liquid ratio was 1:4,and the amount of manganese sulfate added was 2.5%.For the desulfurization solution after the reaction,this paper also made relevant research content.The total iron content in the desulfurization solution was determined to be 33510 mg/L by titration.The types and contents of several ions in the desulfurization solution were measured by ICP-OES,and it was found to contain a large amount of sulfate ions.Under the experimental conditions of this study,the sodium sulfate solution was slowly added to the desulfurization solution after the reaction and heated to90°C.After 4 hours,the yellow sodium iron strontium product was obtained,and the obtained yellow sodium iron sputum product was characterized by XRD and XRF analysis.In the experiment,the desulfurization slag after the reaction was characterized by XRD,XRF and SEM.It can be seen from the characterization that the desulfurization slag still contains a large amount of Fe element after the reaction;the desulfurization slag is washed with water after 1:1 and the pH>2,and dried.After drying,the amount is reduced to 6%,and the pH is higher than hazardous waste.It can be directly returned to the slag yard and disposed of according to the original route.