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 A portion of the withdrawn crystallizer slurry is concentrated in a first hydroclone, diluted with crystallizer feed solution, concentrated in a second hydroclone, and centrifuged and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.

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: Separate deposits of trona or nahcolite ore are solution mined with two solvents, aqueous sodium hydroxide and aqueous hydrogen chloride. Aqueous sodium carbonate solution is withdrawn from the region of the NaOH-treated ore deposit, for recovery of soda ash. Aqueous sodium chloride brine is withdrawn from the region of the HCl-treated ore deposit and introduced to an electrodialysis cell to regenerate the two solvents and thereby continue the solution mining cycle.

Abstract: Method of operating a rotary calciner retrofitted from oil- or natural gas-firing to coal-firing, in which coal is burned in a coal furnace and the coal combustion gases are then heated further in a booster burner utilizing oil or natural gas, to raise the combustion gas temperature to permit processing of calcine at up to a design capacity rate.

Abstract: Improved process for preparing sodium carbonate from crude trona without carbon column scaling by evaporating a portion of water from a clarified sodium carbonate solution to crystallize sodium carbonate crystals therefrom, separating the sodium carbonate crystals from the crystallizer liquor, passing only the crystallizer liquor which contains organic impurities through a carbon column to reduce the organic impurity concentration therein, and evaporating a portion of water from the carbon treated crystallizer liquor to crystallize additional sodium carbonate crystals.

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.