Method for preparing industrial-grade and food-grade phosphoric acid by emulsification, extraction and purification wet method

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 a 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 by an emulsification extraction method. Background technique [0002] The preparation of industrial-grade phosphoric acid and food-grade phosphoric acid can use thermal phosphoric acid as raw material, or wet-process phosphoric acid as raw material. Due to the large 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. The research on the purification of wet phosphoric acid by solvent extraction has never stopped at home and abroad, and great progress has been made. Chinese patent ZL03117850.2 discloses a method for preparing industrial-gra...

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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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