| 摘要 |
<p>PURPOSE:To reduce the discharge amount of a discharged aqueous MgSO4 solution, by holding the pH value of the recirculation solution containing an Mg(OH)2 absorbent of an absorbing tower to a low value and depositing, separating and recovering MgSO4 from a waste absorbing solution. CONSTITUTION:Exhaust gas is guided to an absorbing tower 1 and brought into contact with a recirculation solution of which the pH is adjusted to 4.0-6.5 by an Mg(OH)2 slurry to absorb and remove SO2. A part of the recirculation solution is guided to a neutralization/crystallization tank 2 and Mg(OH)2 is added to said tank 2 from a pipe 14 to convert Mg(HSO3)2 in the solution to MgSO3. The deposited MgSO3 is guided to a solid-luquid separator 3, and separated and recovered. The filtrate is guided to an oxidizing tower 4 through a filtrate tank 16 and MgSO3 in the solution is oxidized to MgSO4 by air to be discharge out of the system as an aqueous MgSO4 solution from a pipe 19.</p> |
