Abstract: Crystal solids made via the continuous crystallization of a crude, concentrated aqueous feed solution are recovered as a crystalline solid product that is relatively free of impurities present in the crystallizer liquor. A portion of the withdrawn crystallizer slurry is concentrated in a first hydroclone, diluted with crystallizer feed solution, concentrated in a second hydroclone, and centrifuged and dried to recover the crystalline solid product.

Abstract: Sodium bicarbonate is produced by introducing solid sodium carbonate, sodium sesquicarbonate, and/or Wegscheider's salt into a reversion slurry, saturated with respect to bicarbonate and containing at least 10 wt. % solids, to effect rapid and complete conversion of the feed solids to crystalline sodium bicarbonate which is recovered from the slurry. Carbon dioxide is introduced into the reversion liquor to maintain its composition at a relatively constant value, preferably in a region of the Na.sub.2 CO.sub.3 --NaHCO.sub.3 --H.sub.2 O phase diagram that minimizes the equilibrium partial pressure of CO.sub.2 vapor above such liquor.

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: Soda ash is prepared from dry-mined nahcolite ore by partially calcining the ore, dissolving the ore in aqueous solution, separating the resultant solution from the ore insolubles, crystallizing anhydrous sodium carbonate or sodium carbonate monohydrate, and recovering the crystallized sodium carbonate.

Abstract: YUtilization of a soda-type dry sorbent in a dry injection flue gas desulfurization process is increased, without sacrifice in the SO.sub.2 removal efficiency, by reinjecting a portion of the sorbent collected in the baghouse filter back into the hot flue gas stream along with fresh sorbent; the recycled sorbent is optionally cooled below the bag filter temperature prior to its reinjection.