Abstract: Process for the manufacture of sodium carbonate crystals comprising: the addition of solid sodium carbonate (1) to an aqueous solution comprising sodium bicarbonate and sodium carbonate; the crystallization and the separation of sodium sesquicarbonate crystals; (B, C) the crystallization of sodium carbonate crystals, (E) the amount of sodium carbonate added being adjusted so that the crystallization of sesquicarbonate crystals can be carried out without preliminary evaporation of the aqueous suspension.

Abstract: Process for the manufacture of sodium carbonate crystals comprising: the addition of solid sodium carbonate (1) to an aqueous solution comprising sodium bicarbonate and sodium carbonate; the crystallization and the separation of sodium sesquicarbonate crystals; (B, C) the crystallization of sodium carbonate crystals, (E) the amount of sodium carbonate added being adjusted so that the crystallization of sesquicarbonate crystals can be carried out without preliminary evaporation of the aqueous suspension.

Abstract: A method for the recovery of ammonia from liquor from the filters of ammonia-soda plants, which contains free ammonia and ammonium chloride. In this method the liquor is heated to release the free ammonia, and the remaining liquor is then treated successively in a prelimer with lime in an amount insufficient to decompose the whole part of the ammonium chloride and in a still with steam and an alkali metal hydroxide in an amount sufficient to decompose the remaining part of ammonium chloride.

Abstract: Process for the fabrication of boric acid by carboammoniac attack of a borate mineral, involving subjecting a borosodium ore, in its natural state or previously refined, and in a finely ground condition, to a treatment in an aqueous medium with carbonic anhydride and ammonia in a manner to precipitate sodium bicarbonate which is separated. The remaining mother liquor is cooled to obtain crystals of ammonium borate which are separated, redissolved, the obtained solution being decomposed by thermal means in order to form ammonia which is recycled to the ore treatment and a boric acid solution from which the acid is separated by crystallization. This process permits obtaining two valuable products: NaHCO.sub.3 and H.sub.3 BO.sub.3. When the ore is preliminarily refined, more effective utilization can be made of the ammonia.