PROCESS FOR THE TREATMENT OF BLACK LIQUOR

摘要

The present invention relates generally to a process for the recovery of lignin from black liquor. The process involves electrochemically treating the black liquor to reduce the pH thereof below about 11, precipitating the lignin from the electrochemically treated black liquor and recovering the solid lignin. The present invention also relates to a process for increasing pulp production of pulp in a Kraft process limited by the capacity of a recovery boiler. The process involves electrochemically treating at least one portion of a black liquor produced by the process before entry into said recovery boiler to reduce the pH thereof below 11 and optionally extracting at least a portion of inorganic materials therefrom. Lignin is precipitated and recovered from the electrochemically treated black liquor, and the resulting liquor is feed to the pulp production process before the evaporation train of the Kraft process.