Date of Award

12-2003

Degree Name

Master of Science

Department

Paper Engineering, Chemical Engineering and Imaging

First Advisor

Dr. John Cameron

Second Advisor

Dr. David Peterson

Third Advisor

Dr. Said AbuBakr

Access Setting

Masters Thesis-Open Access

Abstract

This thesis investigates a new development of autocausticizing the green liquor with trisodium borate. Sodium metaborate (NaBO2) reacts with the sodium carbonate (Na2CO3) in the char bed at 850°C in the recovery furnace to form trisodium borate (Na3BO3) which in tum, when dissolved in water produces sodium hydroxide (NaOH) regenerating sodium metaborate (NaBO2). The main objective of this research is to study the formation of trisodium borate from the reaction of sodium metaborate with sodium carbonate at different molar ratios of carbonate to borate and to determine the effect of the process parameters such as products concentration and temperature on the reaction of trisodium borate with green liquor producing sodium hydroxide. The results show evidence of trisodium borate formation due to decarbonization of sodium carbonate by sodium metaborate and with increase in sodium carbonate to sodium metaborate molar ratios, the decarbonization of sodium carbonate lowers, where more carbon dioxide (CO2) is released, which needs to be effectively purged out to improve decarbonization. The reaction of trisodium borate with green liquor (Na2S, H2O and Na2CO3) was fast and about 85% of trisodium borate formed reacts with water to form sodium hydroxide.

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