WASTE GAS DESULFURIZATION METHOD

摘要

PROBLEM TO BE SOLVED: To eliminate the complication of reciprocally separating two kinds of crystals by forming an upper outlet and a lower outlet in a double decomposition tank and taking out a slurry mainly containing magnesium hydroxide through the upper outlet and the remaining slurry through the lower outlet. SOLUTION: An upper outlet and a lower outlet are formed in a double decomposition tank 4. A slurry mainly containing magnesium hydroxide and taken out of the upper outlet in the necessary amount for pH adjustment is turned back to an oxidation A double decomposition treatment liquid mainly containing gypsum dihydrate and taken out of the lower outlet is sent to a calcium ion removing tank 6, a part of a liquid treated in the oxidation process is added to the tank 6 and sulfate ion is added to lower the solubility of gypsum dihydrate and remove calcium ion. After that, the resultant liquid is turned back as a slurry of a mixture of magnesium sulfate-containing magnesium hydroxide and gypsum dihydrate to a desulfurization tower 1. In this way, crystals of gypsum dihydrate and magnesium hydroxide are separated by a simple installation.