Coal Slurry Flue Gas Desulfurization Additives

Coal slurry flue gas desulphurization(FGD) based on aqueous catalyzed oxidation, is a method which removes SO₂ from flue gas with coal slurry as scrubbing medium.SO₂ transforms into H₂SO₃ after dissolving,and then H₂SO₃ is oxidized into H₂SO₄ through the reaction with coal pyrite and O₂.And therefore SO₂ is removed from flue gas.Coal pyrite sulfur can also be transformed into H₂SO₄ and coal pyrite sulfur content is reduced. Fe²⁺/Fe³⁺ ions,produced in the reaction,then served as catalyst in the aqueous catalyzed oxidation of SO₂.In desulphurization process,using chemical additive can enhance the desulphurization performance,the SO₂ removal efficiency and reduce the investment and the expenditure of the desulphurization system.The additives for coal slurry FGD process were experimentally selected with a bubbling reactor,by using N₂,O₂ and SO₂ to simulate flue gas to inspect the influence of chemical additive to the SO₂ removal efficiency,changing of pH value as well as the leaching rate of coal pyrite.Three materials,A,B and C,as the chemical additives were tested to study the effects in the high sulfur raw coal and the coal-slime slurry separately.The experiments indicated that chemical additive A could enhance the SO₂ removal efficiency,but it was not obviously effective to pH value and the leaching rate of coal pyrite.The effect of additive B was extremely obvious on the SO₂ removal efficiency.Under lower concentration,the SO₂ removal efficiency still maintained about 90%.But additive B could only slightly raise the iron leaching rate.Additive C could not only enhance the SO₂ removal efficiency,but effectively raised the iron leaching rate.The enhancing mechanism of the three additives was analyzed.