| 摘要 |
<p>PURPOSE:To improve the rate of calcination and causticity by using MgCO3 and iron oxide in place of MgCO3 in a method in which an MgCO3 slurry formed by causticizing in a soda dissolving tank is dried with waste heat from a soda recovery boiler. CONSTITUTION:Highly concd. waste liquor is sprayed and burned in the bottom combustion section of a recovery boiler 10 to produce smelted matter. Powder contg. essentially MgCO3 and Fe2O3 is further blown into the section from feeding inlets 15. Most of MgO.Fe2O3 formed by calcination in the boiler 10 in accordance with equation I is allowed to flow down into a soda dissolving tank 16 together with the smelted matter flowing down along the wall of the boiler 10. In the tank 16, the smelted matter (Na2CO3 and MgO.Fe2O3) dissolves in water fed beforehand to the tank 16, and NaOH as chemicals for digestion is prepd. by a reaction represented by equation II. The NaOH is fed to a circulating system through a white liquor tank 19. A slurry contg. MgCO3 and Fe2O3 formed in the tank 16 is taken out of the outlet 21 and dried by contact with exhaust gas in a flue behind the boiler 10, and the resulting powder is fed to the boiler 10 from the inlets 15.</p> |
