Decarbonization of Sodium Carbonate with Sodium Metaborate, 2001 Pulping Conference Proceedings

J. Cameron, Z. Yusuf--Recently, there has been considerable interest in the use of borate as an autocausticizing agent for the conversion of sodium carbonate into sodium hydroxide. The objectives of this work were to determine the nature and rate controlling processes for the reaction of sodium metaborate with sodium carbonate. This reaction was studied by heating sodium metaborate/sodium carbonate in an electric furnace and monitoring the carbon dioxide generation rate. One finding of this work was that the reaction begins in the solid phase at temperatures between 600 and 850 degrees C. In the solid phase, approximately two moles of sodium metaborate are required to generate one mole of carbon dioxide. Once the salts melt, the reaction is extremely rapid with one mole of sodium metaborate reacting with one mole of sodium carbonate to generate one mole of carbon dioxide. It was found that the reaction was highly reversible and if the carbon dioxide generated was not removed, the reaction slowed significantly.