Method for regenerating sodium hydroxide by partial autocausticizing sodium carbonate containing smelt by reaction with a borate

A method for regenerating sodium hydroxide in a wood pulping process comprising the steps of:

• (a) partially autocausticizing a sodium carbonate-containing smelt by reaction with borate, thereby producing a borate-containing partially autotcausticized smelt which includes a reacted portion and an unreacted portion;
• (b) dissolving in aqueous solution said borate-containing partially autocausticized smelt, including said reacted and unreacted portions thereof, to form a borate-containing liquor, thereby regenerating sodium hydroxide and forming dissolved sodium carbonate from said reacted and unreacted portion, respectively, in said borate-containing liquor;
• and
• (c) introducing lime into said borate-containing liquor so as to react said dissolved sodium carbonate with said lime, thereby regenerating additional sodium hydroxide from said borate-containing liquor in the substantial absence of calcium borate formation.