| 摘要 |
<p>A method for recovering chemicals in a process of producing pulp by the kraft process, characterized in that an alkaline solution containing Na2S which flows in a process of producing pulp by the kraft process is electrolyzed by the electrolytic oxidation method; a liquid which is formed in a positive electrode side and contains a polysulfide type sulfur in an amount of 6 g/L or more is added, as it is or after being caustificated, to the process before a chip has the maximum temperature, and a NaOH solution formed in a negative electrode side is added to at least one step of the process from a step wherein a chip has the maximum temperature to a final bleaching step; and at least the chemicals discharged from one or more steps, wherein NaOH is added, of those discharged from all the steps from a digestion step to a final leaching stage are recovered and reused. The method can be employed for rendering the process to be a closed system, and at the same time for improving the yield of pulp and for reducing the occurrence of environmental problems.</p> |
