Study On Sinter Flue Gas Desulphurization With Pyrolusite Slurry

Sintering flue gas represent one of the significant sources of steel pollution. Lots ofsintering waste gas with complex composition of SO₂, NO_x, etc, and pollution to thesurrounding environment. The desulphurization of sintering flue gas has been payattention widely and has became a very serious problem of environmental protection inthe iron-making and steel-making industry. The thermodynamics of sintering flue gasdesulphurization with pyrolusite slurry, and chemical reaction mechanism of sinteringflue gas desulphurization with pyrolusite slurry by means of HSC Chemistry5.0. Asshown in the E-pH figure of SO₂-H₂O binary system at25℃, SO₃2-, HSO₃-, S2O₃2-andHS-are all produced when sulphur dioxide was dissolved into water. All these ions affectin different degree the sintering flue gas desulphurization process with pyrolusite slurrywith the variation of pH value of water solution. The chemical reaction production inwater solutions of sulfur dioxide from sintering flue gas and manganese dioxide ofpyrolusite slurry can be deduced with the E and pH value of water solution according tothe E-pH figure of SO₂-Mn-H₂O ternary system. Two possible chemical reactions wereincluded in the sintering flue gas desulphurization process by pyrolusite slurry. It is easilyfound from above results that the oxidation-reduction reaction of SO₂and MnO₂is thedominating desulphurization reaction with a high desulphurization speed and efficient inthe first stage of sintering flue gas desulphurization with pyrolusite slurry. In the mediumand later period, SO₂from sintering flue gas is oxidized directly into H₂SO4whichbecome gradually the primary desulphurization reaction and the desulphurization speedand efficient and also decrease gradually with the decreasing of pH value of pyrolusiteslurry. Manganese dioxide is stable in alkaline or acidic solution in general conditions.However, manganese dioxide will be reduced to Mn2+under the condition of highoxidation potential and reducing agent. Sintering flue gas desulphurization withpyrolusite slurry can be divided into five events: gas-film resistance, liquid-filmresistance, solid-film resistance, internal resistance, chemical reaction resistance.Experimental results and study show that the reaction rate of process is limited by gas-film resistance.To find out sintering flue gas desulphurization with pyrolusite slurry test: the desulphurization degree decreased with increasing the concentration of sulfur dioxide.According to the need of practical production, the concentration of sulfur dioxide iscontrolled about0.3%. Average particle size of pyrolusite was smaller, and thedesulphurization degree was higher. Liquid-to-solid ratio of pyrolusite was lower, and thedesulphurization degree was higher. Agitator rotational velocity was faster, and thedesulphurization degree was higher. Dioxide with content appropriately raise, thedesulphurization degree was capable of improving. Combined the desulphurizationdegree and the cost sintering flue gas desulphurization, average particle size of pyrolusitewas controlled about200mesh. Liquid-to-solid ratio of pyrolusite was controlled about100:1. Agitator rotational velocity was controlled about400r/min. Dioxide with contentappropriately was about40%.