Ammonium chloride method - Enan soda method

This is an improved ammonia soda process that improves the efficiency of sodium or chlorine utilization. 1 L of the mother liquor from which crude sodium bicarbonate is separated contains 190 g of NH ₄ Cl, 83 g of NH ₄ HCO ₃ , 77 g of NaCl, and 7 g of NaHCO ₃ , so ammonium chloride (ammonium chloride) and salt are recovered to improve the utilization rate of sodium and chlorine. There are various methods for producing ammonium chloride from NaHCO ₃ liquid, but ultimately the NaCl concentration is increased and finally cooled to precipitate ammonium chloride. Depending on the operation before the cooling process, there are the cooling method, the evaporation method, and the intermediate salt method. Currently, the cooling method is mainly used in Japan. In the cooling method, NH ₃ is first absorbed into the NaHCO ₃ liquid to increase the solubility of the HCO ₃ ^- ion, and the raw salt is separately made into a powdered refined salt and then added to the above liquid, where it is cooled to below 15°C while dissolving NaCl, and ammonium chloride is precipitated.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

ナトリウムあるいは塩素の利用効率向上をはかったアンモニアソーダ法の改良法．粗炭酸水素ナトリウムを分離した母液1 L 中には，NH₄Cl190 g，NH₄HCO₃83 g，NaCl 77 g，NaHCO₃7 g 程度が含まれるため，塩化アンモニウム(塩安)と食塩とを回収してナトリウムと塩素の利用率を向上させる．NaHCO₃液から塩安を製造する方法は種々あるが，結局はNaCl濃度を高め，最後に冷却して塩安を析出させている．冷却工程の前の操作により，冷却法，蒸発法，および中間塩法などがある．現在，わが国では，主として冷却法が行われている．冷却法では，まずNaHCO₃液にNH₃を吸収させ，HCO₃^－イオンの溶解性を増大し，別に原塩を粉末精製塩としてから上の液に投入し，NaClの溶解と同時に15 ℃ 以下に冷却し，塩安を析出させる．

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