CYCLIC PROCESS FOR PRODUCING ALKALI SOLUTION OF CELLULOSE CARBAMATE, PRECIPITATING THE CARBAMATE AND RECOVERING THE CHEMICALS

摘要

A cyclic process for producing an alkali solution of cellulose carbamate, for precipitating the celulose carbamate from the alkali solution, and for recovering and recycling the chemicals, comprises the following steps: (a) an alkali solution of cellulose carbamate is prepared by dissolving cellulose carbamate in an aqueous solution of sodium hydroxide, (b) the solution obtained in step (a) is brought into contact with a precipitating solution containing sodium carbonate, whereby the cellulose carbamate is precipitated and can be removed, (c) from the solution in step (b) sodium carbonate is crystallized and is returned to the precipitant solution in step (b), and (d) mother liquor containing sodium hydroxide, obtained in step (c), is used as the sodium hydroxide solution in step (a). The crystallization in step (c) can be carried out in two or more steps by cooling.