Patent ID: 6228335
Filing Date: 2001-05-08
Classification: C01D,C22B,Y02P

Abstract:
A process for the production of sodium carbonate-containing crystalline solids which comprises:(i) withdrawing an aqueous mining solution containing dissolved sodium carbonate and at least about 1 wt % sodium bicarbonate from an underground alkali ore source;(ii) stripping CO.sub.2 gas from the withdrawn aqueous mining solution, to convert a portion of said sodium bicarbonate dissolved therein to sodium carbonate to provide a sodium carbonate concentration such that a resulting crystallization step provides crystals of both sodium carbonate monohydrate and sodium sesquicarbonate crystals wherein greater than one-fourth the total alkalinity of said crystals is from said monohydrate crystals;(iii) co-crystallizing sodium carbonate monohydrate and sodium sesquicarbonate crystalline solids from the CO.sub.2 -stripped aqueous mining solution at a temperature below the invariant point of said stripped solution to avoid co-crystallization of anhydrous sodium carbonate, by evaporation of water at a temperature of at least about 50.degree. C. and below said invariant point of said stripped solution to form a slurry of crystalline solids in an aqueous liquor wherein said sodium carbonate monohydrate crystals are present in an amount greater than one-fourth of the total alkalinity of said crystals;(iv) recovering said sodium carbonate monohydrate and sesquicarbonate crystalline solids from said slurry.