| 摘要 |
<p>A process for producing high-purity chemicals, such as high-purity sulfuric acid or high-purity ammonia water, suitable for use in semiconductor manufacture. High-purity sulfuric acid is produced via the absorption step wherein water is brought into contact with gaseous sulfuric anhydride, the stripping step where sulfurous acid gas is separated and removed, and the transporting step conducted through a liquid pumping system wherein the liquid-containing section is made from non-metallic material. High-purity ammonia water is produced via the absorption step wherein ammonia gas is absorbed in water and the step of cooling ammonia water and recirculating the same to the absorption step by utilizing the liquid pumping system wherein the liquid-contacting section is made from non-metallic material. The liquid pumping system is composed of a tank for reserving high-purity chemicals, a transfer tank, supply and discharge pipings, a piping for supplying gases to the transfer tank, and a piping for discharging gases from the transfer tank. This process provides high-purity sulfuric acid and ammonia water freed extremely from impurities such as metals and sulfurous acid gas.</p> |
