Nahcolite solution mining process

Abstract

Nahcolite solution mining process comprising drilling at least one well into a Nahcolite bed, circulating hot barren aqueous liquor in a cavity in said Nahcolite bed for a time sufficient to produce a pregnant liquor having an increase in the concentration of NaHCO.sub.3 in the range of from about 3 to about 20% while maintaining Na.sub.2 CO.sub.3 concentration in the range of about 0.25-4%, preferably less than 2.5%, withdrawing said pregnant liquor, cooling said pregnant liquor to preferentially precipitate NaHCO.sub.3 therefrom and to produce a barren liquor, recovering said NaHCO.sub.3, and reheating and re-injecting said barren liquor in said well. The cavity temperature is maintained below about 250.degree. F. and preferably below about 200.degree. F. The barren liquor is injected at a pressure of below about 150 psig. The pregnant liquor is extracted at a temperature in the range of from about 85.degree. F. to about 200.degree. F., and the cystallization occurs at a temperature of about 25.degree.-120.degree. F. The NaCl concentration is maintained at below about 6% and preferably below about 1.0%. Crystalline sodium bicarbonate of high purity (98+% NaHCO.sub. 3) is produced in the as-crystallized form, and simple washing increases the purity.

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