Abstract: A cyclic solution mining method that uses aqueous sodium hydroxide for recovering valuable alkali values, preferably as soda ash, from subterranean deposits of trona or nahcolite, even when such deposits are NaCl-contaminated. The aqueous sodium hydroxide mining solvent is generated via electrodialysis of a recirculating sodium chloride brine stream. Hydrogen chloride that is also generated in the cell's operation is neutralized with aqueous sodium carbonate, to regenerate sodium chloride brine that is recirculated to the electrodialysis cell as brine feed.

Abstract: Hot flue gas containing sulfur oxides is treated in a dry injection desulfurization process by injecting a dry particulate soda ash sorbent into the SO.sub.2 -contaminated gas stream, which must contain 0.5-10 wt % water and be at a temperature of 100.degree.-175.degree. C., and collecting the sorbent in a solids collection device like a baghouse filter. The dry soda ash sorbent is a porous sodium carbonate, derived from calcination of a NaHCO.sub.3 -containing compound, and must have a minimum surface area of at least 2 m.sup.2 /g and less than 10 wt % residual bicarbonate. In this process, at least 40% of the sorbent's sodium content is utilized in the desulfurization reaction, at a normalized stoichiometric ratio=1.

Abstract: A method for enhancing the recovery of dense soda ash from Na.sub.2 SO.sub.4 - and NaCl-containing aqueous sodium carbonate solutions by first co-crystallizing anhydrous sodium carbonate and burkeite and next introducing the co-crystallized solids to an aqueous medium at elevated temperature to dissolve the burkeite and cause reversion of the anhydrous sodium carbonate solids to crystalline sodium carbonate monohydrate, which is then separated from the dissolved sulfate and recovered as product.

Abstract: A method for enhancing recovery of sodium carbonate from sodium carbonate solutions which contain sodium chloride. Anhydrous sodium carbonate is recovered in good yields from aqueous sodium carbonate solutions containing sodium chloride by evaporative crystallization at superatmospheric pressure and at a temperature of at least about 120.degree. C.

Abstract: A method for recovering alkali value from sodium bicarbonate-containing ore by utilizing an aqueous solvent containing ammonia. The aqueous ammonia solvent is contacted with the ore to solubilize the sodium bicarbonate-containing ore. The alkali values in the resulting solution are crystallized, preferably as sodium carbonate monohydrate or as sodium sesquicarbonate, which may be processed to recover soda ash. Aqueous ammonia solvent is preferably regenerated from the mother liquor remaining after recovery of the solids, the ammonia solvent then being employed in a cyclic method to recover additional alkali values from the ore.