Method for producing electronic-grade nitric acid

Abstract

The invention discloses a method for producing electronic-grade nitric acid. The method sequentially comprises the following steps of: a) providing a chemically pure reagent-grade nitric acid raw material of which the concentration is about 70 percent; b) performing microfiltration on the nitric acid raw material, adding the nitric acid raw material into a pre-heater for preheating, and adding into a reboiler; c) heating the reboiler with saturated vapor, and making nitric acid vapor generated by heating pass through a vapor condenser to obtain a semi-finished product; d) blowing the semi-finished product with high-purity compressed air to remove residual vapor in the semi-finished product, cooling the obtained finished product again with a finished product cooler, and adding the finishedproduct into a finished product storage tank; and e) performing ultrafiltration on the finished product to remove particles so as to finally obtain the nitric acid applied in the electronic industry.In the method for producing the electronic-grade nitric acid, the normal chemically pure reagent-grade nitric acid raw material of which the concentration is about 70 percent is directly rectified and then the rectified product is blown with the high-purity compressed air. The used raw material is safe; the pressure for the subsequent tail gas treatment is greatly reduced; and the production costis reduced.

Description

technical field [0001] The invention relates to a method for producing nitric acid, in particular to a method for producing electronic-grade nitric acid required for large-scale integrated circuits. Background technique [0002] Nitric acid, with a relative molecular weight of 63.01, is a strong oxidizing and corrosive inorganic acid. It is easily soluble in water and completely ionized in water. At room temperature, its dilute solution is colorless and transparent, and its concentrated solution is brown. Nitric acid is unstable, easily decomposed by light, and can oxidize or nitrify organic matter. The density (at 25 degrees) is 1.42g / ml. Ultra-pure nitric acid is a strong acid cleaning agent and corrosive agent, which can be used in conjunction with glacial acetic acid and hydrogen peroxide. Nitric acid with a concentration of about 70% is mainly used in the production of large-scale integrated circuits. [0003] The preparation techniques of ultra-pure nitric acid mainl...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the concentrated nitric acid itself contains a small amount of free , and when the concentrated nitric acid is diluted with water, a large amount will be generated due to heat release The free must be removed. The traditional method uses Removing is not only uneconomical, but also brings trouble to the subsequent exhaust gas treatment. In addition, due to the strong corrosiveness of concentrated nitric acid and Instability, more than 95% concentrated nitric acid is used as raw material for production, safety factors also need to be considered

Images