2. After trona is crushed, dissolved (or brine) and clarified, lime milk is added at 95 ~ 100℃ for causticization, and the causticized solution is clarified, evaporated and concentrated to NaOH concentration of about 46%. The clear liquid is cooled to separate out salt, and then further concentrated. And a solid caustic soda product is prepared. The causticized slurry is washed with water, and the washing water is used to dissolve trona.
3. Add the refined preparation of soda ash, caustic soda and barium chloride to remove impurities such as calcium, magnesium and sulfate ions, then add sodium polyacrylate or causticized bran in the clarifier to accelerate precipitation, add hydrochloric acid for neutralization after sand filtration, preheat the brine and send it to electrolysis, preheat the electrolyte, evaporate, separate out salt and cool it to make liquid caustic soda, and further concentrate it to get the finished product of solid caustic soda.