| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce an amount of use raw material magnesium hydroxide of by a method wherein in the case wherein an exhaust gas containing a sulfur oxide and a hydrogen chloride is treated with magnesium hydroxide as a desulfurization agent, a separation process wherein gypsum dihydrate, magnesium chloride, and magnesium hydroxide are avoided from being mixed in blow wastewater is provided. SOLUTION: While an absorbing liquid containing magnesium hydroxide is allowed to flow down in a shower shape in a desulfurization column 1, the absorption liquid is brought in gas-liquid contact with an exhaust gas G1 containing a sulfur oxide, and the sulfur oxide is absorbed to the solidified as magnesium sulfite or the like. A treating liquid is thereafter sent to an oxidizing tank 3 with a pump, a sulfuric acid generated by oxidation by air is allowed to react with magnesium hydroxide to be supplied for adjusting pH, and converted to magnesium sulfide. Then, the treating liquid is sent to a double decomposition tank 4, allowed to react with calcium hydroxide from a supply tank 5 to convert the magnesium sulfate to calcium hydroxide and gypsum dihydrate, and the magnesium hydroxide is sent back to the desulfurization column 1 via a separator 6.</p> |
