Study On Flue Gas Desulfurization With Pyrolusite Pulp

Flue gas desulfurization with pyrolusite pulp, it not only can remove low concentration SO2 in flue gas, but also gain valuable by product MnSO4. In experiment applying Jet Bubbling Reactor (JBR) made by us as SO2-absorbing apparatus, using air(or N2)-SO2 mixtures as simulated flue gas, and mixing ore powder (<0.1mm) and water as ore pulp. Simulate flue gas was absorbed continually through JBR loading pyrolusite pulp, and desulfurization ratio and ratio of leaching Mn2+ were examined under various experimental conditions. On the basis of discussion and analysis for reaction mechanism and process of SO2 and MnO2, first studying on macro-kinetics of process of pyrolusite pulp absorbing SO2 at home and abroad. At the same time for the first time drawing JBR into desulfurization process with pyrolusite pulp. Furthermore, studying deeply on various technological parameters, combination of technological unite, as well as SO2 oxidized H2SO4 under catalytic function of Mn2+ at high agitation rate. Experimental results and study show that (1) The reaction rate of process is limited by diffusion of SO2 gas into aqueous phase. The conclusion is supported by reaction rate goes up with increase of stirring speed of gas phase(Fig. 3-6) , and is in linear relationship to gas-liquid phase area(Fig. 3-8). Finally the model of macro-kinetic is established to describe the reaction rate of the process:in which:(2) Optimum construction parameters of JBR are determined by experiment. Jet system of flue gas: the depth (h) of 100~240mm for jet hole plunging in solution; Jet velocity (V) of 6~9m/s; Diameter (do) of 3mm for jet hole. Agitation system of pyrolusite pulp: a ratio of the agitation diameter (d) to reactor diameter (D) : d/D =0.35; a ratio of distance (y) of agitation from the bottom of reactor to agitationdiameter (d): y/d = 0.5; agitation rate of 500~600r/min. Also, JBR has the feature that absorbing SO2 and leaching Mn2+ were carried out in the same apparatus , so there is no out-circling equipment system to avoid ore pulp pump. (3) The model between n and XB relationship are determined by fitting the experimental data to a linear regression equation. For single JBR running continually : * = 0.945 - 0.472XB ; For two connection of JBRs running continually : = 0.982-0.23XB? (4) Both desulfurization rate and rate of leachingMnz+ may reach 80%~85% using two-connection JBRs,. Furthermore, leaching solution were filtered, removed impurities, such as Fe, Al, Ca, Mg, Co, Ni and Pb, and crystallized lastly. MnSO4 H2O could be gained which can meet National Standard (GB1622-86). (5) Stirring speed can influence reaction of desulfurization with pyrolusite pulp. When stirring speed < 500r/min, SO2 mainly react MnO2 to produce MnSO4, and when stirring speed >1000r/min, because of increase of solving oxgen in solution, SO2 was oxidized to H2SO4 under the Mn2+ catalysis. Thus, it is a another new finding that SO2 in flue gas could be oxidized to rare H2SO4(10%~20%) with pyrolusite pulp under high agitation rate.