Patent ID: 9187512
Filing Date: 2015-11-17
Classification: C02F,C07G,D21C

Abstract:
1. A process for recovering lignin from paper making black liquor comprising: (a) carbonizing said black liquor at a temperature between 80° C. and 200° C. and a pressure between about 50 psig and about 200 psig with and about of carbon dioxide to reduce the pH to between 9.0 and 10.5; (b) subjecting said carbonated black liquor to a phase separation wherein a dense liquid-lignin phase is formed and a lignin-depleted liquid phase is formed, and NaOH and other basic components are neutralized; (c) recovering said lignin-depleted liquid phase; (d) removing said dense liquid-lignin phase and neutralized NaOH and other basic components and acidifying said dense liquid-lignin phase with a acetic acid to neutralize residual NaOH and other basic components, thereby generating an acidified granular lignin; and (e) recovering lignin from said acidified granular lignin to remove residual acid and ash content, thereby generating purified lignin.