Method for preparing industrial-grade and food-grade phosphoric acid by emulsification extraction and purification of wet-process phosphoric acid

Abstract

The invention provides a method for preparing industrial-grade phosphoric acid by an emulsification, extraction and purification wet method. The method comprises the sequential process steps of primary de-coloring, emulsification and extraction, emulsification and washing, emulsification and reverse extraction, concentration, dearsenification and heavy metal removing, secondary deep de-coloring and concentration adjustment. A method for food-grade phosphoric acid by the emulsification, extraction and purification wet method comprises the sequential process steps of primary de-coloring, emulsification and extraction, emulsification and washing, emulsification and reverse extraction, concentration, dearsenification and heavy metal removing, secondary deep de-coloring, defluorination and concentration adjustment. The emulsification and extraction step comprises the following steps of: agitating at normal pressure and at a temperature of 50-60 DEG C for 10-60 seconds at the speed of 500-3000 r / min; and agitating at the normal pressure and at the temperature of 50-60 DEG C for 60-240 seconds at the speed of 120-220 r / min; the emulsification and washing step comprises the following steps of: agitating at the normal pressure and at the temperature of 50-60 DEG C for 10-60 seconds at the speed of 500-3000 r / min; and agitating at the normal pressure and at the temperature of 50-60 DEG C for 60-240 seconds at the speed of 120-220 r / min; and the emulsification and reverse extraction step comprises the following steps of: agitating at the normal pressure and at the temperature of 50-60 DEG C for 10-60 seconds at the speed of 500-3000 r / min; and agitating at the normal pressure and at the temperature of 50-60 DEG C for 60-240 seconds at the speed of 120-220 r / min.

Description

technical field [0001] The invention belongs to the preparation method of industrial-grade phosphoric acid and food-grade phosphoric acid, in particular to a method for preparing industrial-grade and food-grade phosphoric acid by purifying wet-process phosphoric acid with an emulsification extraction method. Background technique [0002] The preparation of industrial-grade phosphoric acid and food-grade phosphoric acid can use hot-process phosphoric acid or wet-process phosphoric acid as raw material. Due to the high pollution and high energy consumption of thermal phosphoric acid production, the use of wet process phosphoric acid to produce industrial-grade phosphoric acid and food-grade phosphoric acid has attracted more and more attention. At home and abroad, the research on the purification of wet-process phosphoric acid by solvent extraction has not stopped, and great progress has been made. Chinese patent ZL03117850.2 discloses a method for preparing industrial-grade ...

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Problems solved by technology

However, the above two patents have the following disadvantages: ① Desulfurization and defluorination pretreatment and secondary desulfurization and defluorination treatment are required before extraction, which consumes a long time, and the sulfate content is reduced before extraction, thereby directly reducing the extraction process. The extraction rate of phosphorus pentoxide; ② deep desulfurization of the extracted organic phase after the extraction process, the price of barium carbonate / barium hydroxide consumed in this step is relatively high, and the particles of barium sulfate are extremely small, and solid-liquid separation is very difficult; ③ the above If the method described in the patent adopts conventional extraction methods, such as extraction, washing and stripping with a mixing and settling tank or a vibrating sieve plate column, a longer residence time, a larger device, and a large part of the extraction agent are required. Only by circulating in the system can the normal operation of the device be maintained, resulting in an increase in product cost

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