Electronic-grade potassium hydroxide purification process

Abstract

The present invention discloses an electronic-grade potassium hydroxide purification process. The purification process comprises the following steps: adding pure water into food-grade potassium chloride, dissolving the compound at a high temperature, filtering the solution, and introducing hydrogen chloride gas or a hydrogen chloride aqueous solution into the solution, and salting-out and crystallizing the solution to obtain an acid salt mixed solution; carrying out centrifugal treatment on the acid salt mixture, and separating to obtain wet-based high-purity potassium chloride crystals; adding pure water for dissolving to obtain saline water with a certain concentration; and carrying out bipolar membrane electrolysis treatment on the brine, and then performing concentration and evaporation to obtain the electronic-grade potassium hydroxide. The concentration of the electronic-grade potassium hydroxide solution prepared by the method can reach 48%, the content of sodium in the solutionis less than 10ppm, and the content of other heavy metals is less than 100ppb. Compared with traditional electrolysis, hydrochloric acid and potassium hydroxide solutions are directly generated, hazardous chemical substances such as hydrogen and chlorine cannot be generated, potential safety hazards are reduced, and the environmental protection problem is solved. Besides, the purification processis simple, safe and environment-friendly, the operation cost is relatively low, and the yield can reach 90% or above.

Description

Technical field [0001] The invention belongs to the field of chemical manufacturing, and relates to a purification process of electronic grade potassium hydroxide and electronic grade sodium hydroxide prepared by adopting the purification process. Background technique [0002] At present, the domestic production of electronic grade potassium hydroxide mainly starts from the terminal. The obtained potassium hydroxide flakes are prepared into potassium hydroxide solutions of different concentrations, and heavy metals and sodium ions are removed by freezing crystallization or ion exchange. Potassium heavy metal ions are still high, sodium ions are not significantly reduced, and the yield is low, potassium hydroxide loss is large, and energy consumption is also high. [0003] CN107140658A proposes adding a complexing agent to an industrial-grade potassium hydroxide solution, and then ultra-low temperature freezing and crystallization to obtain high-purity potassium hydroxide crystals, ...

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Problems solved by technology

[0002] At present, the domestic production of electronic-grade potassium hydroxide mainly starts from the terminal, and the obtained potassium hydroxide tablet alkali is prepared into potassium hydroxide solutions of different concentrations, and heavy metals and sodium ions are removed by freezing crystallization or ion exchange, but the obtained hydroxide Potassium heavy metal ions are still high, the reduction of sodium ions is not obvious, and the yield is low, the loss of potassium hydroxide is large, and the energy consumption is also high

[0003] CN107140658A proposes to adopt complexing agent to add in the industrial-grade potassium hydroxide solution, then ultra-low temperature freezing and crystallization obtains high-purity potassium hydroxide crystals, and after heating and melting, it becomes high-purity potassium hydroxide solution; The rate is also low, the complexing agent is expensive, etc., and is not suitable for industrial production

CN104016376B proposes that potassium hydroxide solution is processed by chelating resin, cation exchange resin, anion exchange resin, electrodialysis, and multi-stage circulation filtration system to obtain electronic grade potassium hydroxide, and its single heavy metal can reach below 200ppb, and the sodium ion concentration is at 100ppm Below, but the concentration of potassium hydroxide solution used in this method is low, after purification, it is necessary to increase the concentration step, and the energy consumption is high. At the same time, the patent does not involve the concentration of potassium hydroxide. If the concentration is low, the heavy metal ion is naturally low. This still needs further discussion

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