Flocculation process based purification and recovery of Lyocell spinning solvent NMMO

This paper introduced a new idea for the purification and recovery of NMMO in the coagulation bath—the flocculation process.The results show that proper control of additive,flocculating agent,temperature,stir speed,quantity of each agent and other process parameters could effectively remove the impurities in the coagulation bath such as the solid,big molecules in the forms of undissolved colloid and semi-colloid.The sizes of flocculates are big and loose,ready to precipitate,therefore the impurity removing effect is very ideal,greatly improving the exchange ability of the ion exchange resin in the subsequent process.The resulting solution after flocculation and ion-exchanging treatment shows very good redisolving and spinning properties,facilitating the industrial recovery of NMMO.