Method for producing sodium tetraborate pentahydrate
AssigneeSocieta Chimica Larderello S.p.A.
InventorPaolo Mazzinghi
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Abstract
High-purity sodium tetraborate pentahydrate (Na.sub.2 B.sub.4 O.sub.7.5H.sub.2 O) is produced by: (a) reacting the mineral colemanite (2CaO.3B.sub.2 O.sub.3.5H.sub.2 O) with sodium carbonate (Na.sub.2 CO.sub.3) in an aqueous environment to produce an aqueous solution of sodium tetraborate and sodium hydroxide, with precipitation of solid calcium carbonate; (b) treating the aqueous solution obtained in stage (a), after separating the precipitated calcium carbonate, with boric acid (H.sub.3 BO.sub.3) to neutralize the sodium hydroxide and form a further quantity of sodium tetraborate; (c) separating sodium tetraborate pentahydrate by crystallization from the aqueous solution obtained in stage b.
Claims7
In the process of preparing sodium tetraborate pentahydrate (Na.sub.2 B.sub.4 O.sub.7. 5H.sub.2 O) from colemanite ore by treatment with sodium carbonate and boric acid, the improvement comprising
- (a) first reacting the mineral colemanite (2CaO. 3B.sub.2 O.sub.3.5H.sub.2 O) with sodium carbonate (Na.sub.2 CO.sub.3) in an aqueous environment in the absence of boric acid to produce an aqueous solution of sodium tetraborate and sodium hydroxide, with precipitation of solid calcium carbonate;
- (b) treating the aqueous solution obtained in stage (a), after separating the precipitated calcium carbonate, with boric acid (H.sub.3 BO.sub.3) with no further addition of sodium carbonate to neutralise the sodium hydroxide and form a further quantity of sodium tetraborate;
- (c) separating sodium tetraborate pentahydrate by crystallisation from the aqueous solution obtained in stage (b).
Dependencies are inferred from the claim text.