Continuous Extraction of Black Liquor Salts under Hydrothermal Conditions

In hydrothermal valorization of black liquor (BL) from the Kraft process, separation inorganic salts is pivotal to prevent them fouling downstream equipment such as reactors and for cost-efficient recycling into pulp cooking chemicals. this work, phase behavior present in BL was studied supercritical water conditions were optimized. A high-pressure differential scanning calorimetry study indicated concomitant precipitation formation a second salt-rich liquid-like phase. The potassium-to-sodium ratio found strongly impact salt mixture. Potassium lead alone. At K/(K + Na) ≥ 0.4, steady could be achieved, enabling continuous extraction up 96% concentrated brine effluent.