ECONOMIC-EVALUATION OF BLACK LIQUOR TREATMENT PROCESSES FOR INCREMENTAL KRAFT PULP PRODUCTION - A COMPARISON OF 2 PROCESSES AT PAPRICAN

Research at Paprican has resulted in the development of two processes for tile separation of lignin from kraft black liquor: acidification o f the liquor with waste acid or CO2, and electrolysis of weak black li quor where by sodium hydroxide can be recovered for use in bleaching. For the generic case of a 700 air-dry metric toll per day mill with an R8 generator, the capital cost estimates varied from $9.7M to $12.5M for the CO2 acidification and electrolytic options, assuming a 6 to 8% production increase. The corresponding payback would be between two a nd five years. A few Canadian mills with Mathieson generators would be nefit from the excess waste acid reducing the capital cost to $3M with a payback of less than one year.