Method for separating and recovering phosphonic acid from acetic acid-nitric acid-phosphonic acid waiste liquid

Abstract

To provide a method capable of highly efficiently, selectively separating and recovering phosphoric acid from a mixed acid waste liquid containing acetic, nitric and phosphoric acids even in a practical large scale production by suppressing the emulsification of an oil phase with a water phase in a settling state in a separation process to enable the circulating use of an extractant solution sufficiently. The separating / recovering method comprises an extraction process for selectively dissolving acetic and nitric acids in the extractant solution to extract by mixing the waste liquid containing those acids with the extractant solution containing trialkyl phosphate, a recovery process for recovering phosphoric acid from a residual liquid left by the above process, and a separation process for bringing the obtained acetic / nitric acids-containing extractant solution into contact with a salt-containing water for separation to dissolve and transfer their acids into the above water for separation. The extractant solution can circularly be used by feeding back the oil-phase solution obtained from the separation process to the extraction process.

Description

[0001] This application claims the priority of Japanese Patent Application Japanese Patent Application No. 2004-350135 filed on December 2, 2004, and the disclosure thereof constitutes a part of the present application. technical field [0002] The present invention relates to a method for efficiently and selectively separating and recovering phosphoric acid from the acetic acid-nitric acid-phosphoric acid mixed acid waste liquid discharged from the liquid crystal manufacturing process or the semiconductor manufacturing process, etc. A method of recycling the extract by supplying it to the extraction process. Background technique [0003] In the liquid crystal manufacturing and semiconductor manufacturing industries that have developed rapidly in recent years, a variety of waste water flows out during the manufacturing process, but it is discharged after appropriate treatment according to the type and nature of each waste water. For example, mixed acid waste liquid formed by...

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Problems solved by technology

[0004] As mentioned above, when the mixed acid waste liquid formed by mixing acetic acid, nitric acid, and phosphoric acid is neutralized and then discharged, since the neutralization process produces salts such as acetate and nitrate in the wastewater, it will inevitably cause serious environmental pollution. From the viewpoint of environmental protection, it cannot be said that this kind of neutralization treatment is an ideal means

In addition, the importance of recycling has been called for in recent years in view of the requirements of global environmental protection. However, the conventional neutralization treatment discharge method is a method of discarding waste acid without completely recycling it, so it cannot fully meet the requirements of modern society.

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