GB327909A - An improved method of producing potassium nitrate - Google Patents

Abstract

327,909. Kaselitz, O., and Kali-Forschungs-Anstalt, Ges. June 13, 1929. Potassium nitrate; aluminium chloride.-Potassium nitrate is produced by introducing into a solution of potassium chloride, aluminium and nitrogen in the form of an oxygen compound, for example, aluminium nitrate, or alumina and nitrous gases or nitric acid. According to one method the aluminium and nitrogen in the form of an oxygen compound, as above, may be added to a solution of potassium chloride to form a solution saturated at 0‹ C. with potassium nitrate, aluminium nitrate and aluminium chloride (or preferably potassium nitrate, aluminium chloride and potassium chloride). This solution is concentrated, for instance at 50 mm. pressure at 50‹ C., and cooled to 20‹ C. when AlCl3.6H2O separates. To the mother liquor separated therefrom, potassium chloride and aluminium nitrate, equivalent to the aluminium chloride separated, are added, and water to replace that lost by evaporation and as water of crystallization. The solution is cooled to 0‹ C., potassium nitrate separated, the solution evaporated and the first operation repeated. Alternatively, aluminium and nitrogen in the form of an oxygen compound as above may be introduced into a solution of potassium chloride to form a solution saturated at 0‹ C. with potassium nitrate, aluminium chloride and aluminium nitrate, potassium chloride added to precipitate the potassium nitrate which is removed, and aluminium nitrate then added to precipitate aluminium chloride, which is removed by filtration. Potassium chloride is added to the filtrate and the first operation repeated. The potassium nitrate and aluminium chloride are slightly washed, and the wash liquors may be added to the mother liquors instead of water. The hydrated aluminium chloride may be calcined to give hydrochloric acid and alumina, which latter may be converted into aluminium nitrate, or added with nitrous gases or nitric acid to the reaction.