Rectification Purification of Inorganic Acids

Abstract

Among inorganic acids of the extra purity, an important role belongs to fluoric and hydrochloric acids used in atomic power engineering, microelectronics, fiber optics etc. The quality of an extra pure acid is determined by the content of limited microimpurities in it. When choosing purification methods those are preferred which limit possible additional contamination. For fine cleaning such processes as rectification (distillation), absorption, crystallization, ion exchange etc. are mainly used. In these processes, the extra pure acids are cleaned up to 10-6-10-8 % of separate impurities of the weight (Blyum et al., 2008). To get the specified acids we have developed the fine purification process with periodic rectification and absorption based on the international information standard ISO 10303. At the developing stage special attention paid to the possibility to use the same unit for cleaning both hydrochloric and fluoric acid. The main criterion for the implementation of this possibility is similarity of the processing conditions (Bessarabov, 2014). The developed technology is based on the standard apparatus modules where the distillation (rectification) and absorption modules are the main ones. The distillation (rectification) module is designed to be used at the final stage of producing the specified acids with qualification “extra purity”. In this module the base products are cleaned from impurities which are effectively separated with this method (mainly cations of metals).