Study On Strengthening The Technology Of Flue Gas Desulfurization With Pyrolusite Pulp And Resource Utilization Of Its Absorption Solution

Pyrolusite is in abundance and at a low price in China. Manganese products made from the absorption solution of flue gas desulfurization with pyrolusite pulp find a good market. As a result, the technology of flue gas desulfurization with pyrolusite pulp has attracted more and more attention, and studies on this subject have made much progress. This paper is the first one to advance the recycling technology: strengthening the technology of flue gas desulfurization with pyrolusite pulp by adding pH buffer, the absorption solution of which is utilized to produce electrolytic manganese, high-pure manganese carbonate and ammonium sulfate. With close research on the reaction mechanism, influencing factors, and technological conditions in this system, it is verified that the strengthening measure is effective and this technological route is feasible and benefits environmental protection and economic performance.There is no similar research reported at home that are carried out by adding pH buffer into pyrolusite flue gas desulfurization system to improve the effect of desulfurization and leaching of manganese. By comparing pyrolusite flue gas desulfurization system strengthened by adding pH buffer with traditional pyrolusite flue gas desulfurization system, this paper proves that in pyrolusite flue gas desulfurization system, there exist at the same time two reactions: redox reaction between MnO2 and SO2 and catalysis oxidation reaction between O2 and SO2, whichproduce MnSO4 and H2SO4. In the reaction system, pH value has a great influence on the process of desulfurization: over-low pH value is unfavorable to the dissolution of SO2 in liquid, which in turn decreases the rate of redox reaction between MnO2 and SO2, and as a result, a low rate of leaching Mn2+; to maintain a high pH value will just produce the opposite. The addition of pH buffer into the pyrolusite desulfurization system can effectively improve the pH value, and speed the redox reaction and increase the rate of leaching Mn2+. Experiments on the influence of the amount of pH buffer and oxygen of flue gas on pyrolusite wet flue gas desulfurization system have shown that if the proportion of oxygen in flue gas is 21%, that of pH buffer will have to be 30% to achieve the best result; if oxygen in flue gas is 7%, the demand for pH buffer will be 10%. The final experiments indicate that under the conditions of simulated flue gas from real flaming coal, if 10% of pH buffer is added, flue gas desulfurization can be realized in single JBR reactor and the desulfurization rate and the rate of leaching Mn2+ can reach over 80%. These results support that this method is workable in practice, profitable in economy, and promising in industry application.By experimenting on the technological process of producing electrolytic manganese from absorption solution of desulfurization, the conditions for getting rid of iron in solution are confirmed to be pH=5.5±0.5 .We choose ammonium sulfuration to getting rid of heavy metal and purified conditions is pH=5.5±0.5 and concentration of ammonium sulfuration 50ml/L. The influence of electrolysis technics parameter on electric current efficiency or cell voltage is also inspected in the experiments and the favorable technological conditions for electrolysis are found to be electric current density 390A/m2, temperature about 35, concentration of ammonium sulfate 110g/L, concentration of SeO2 0.04g/L, Mn2+concentration of solution in the cell 18g/L, Mn2+concentration of the inffluent 26g/L, pH value of the inffluent is 8 Under the conditions stated above, absorption solution of desulfurization can be purified and electrolysed to produce electrolytic manganese which meet the standards of GB3418-82. Research also shows that the anode solution can be used to make high-pure manganese carbonate products which meetthe standards of GB10305 and ammonium sulfate can be recovered from the solution and be utilized further.By adding a certain amount of pH buffer to the pyrolusite flue gas desulfurization system, this research has found a solution to the current problem, i.e. it is difficult to make defulfurization rate and the rate of leaching Mn2+ reach over 80% in the pyrolusite flue gas desulftirizationt technology carried out in single JBR reactor. At the same time, a new recycling technological way of pyrolusite flue gas desulfurization and resource utilization has been opened up to increase the extra value of recovered resources and reduce the damage to the environment. Therefore, it will be highly significant to extend the industry application of flue gas desulfurization system with pyrolusite pulp.