| 摘要 |
PURPOSE:To recover efficiently an Na component from a black liquor generated at a paper plant by forming a fluidization medium of an abrasion-resistant and chemically stable substance, and releasing and removing Na components and metallic compds. formed on the surface of the medium, and hydrolyzing the removed substance. CONSTITUTION:A black liquor and Fe2O3 are mixed by a mixer 16, and the mixture is sent to a fluidized-bed furnace 1. A fluidized bed is formed in the fluidized-bed furnace 1 of a medium (silica sand, MgO, etc.) which is highly abrasion resistant and does not react with the black liquor. An NaFeO2 layer is formed on the circumference of the fluidization medium. The medium particles 6 are sent to a cooler 2 and cooled, and then supplied into a separator 3 wherein the NaFeO2 layer adhering to the surface of the medium particles 6 are mechanically released and removed. The removed NaFeO2 layer is sent to a hydrolysis stage 17 wherein the NaFeO2 is hydrolyzed into Fe2O3 and NaOH. The Fe2O3 is resupplied into the mixer 16, and the NaOH is reused in a pulp-making stage. The consumption of the metal oxide and heat can be remarkably reduced in this way. |
