Production method for purifying low-concentration wet-process phosphoric acid, and purification apparatus thereof

Abstract

The invention relates to a production method for purifying low-concentration wet-process phosphoric acid, and a purification apparatus thereof, wherein food-grade phosphoric acid is prepared from low-concentration wet-process phosphoric acid by using a solvent extraction method. According to the method, the process comprises: pretreatment, extraction, washing, back extraction, defluorination, andposttreatment; the organic solvent for extraction is one or a plurality of materials selected from dibutyl butanephosphonate, dimethyl heptyl methyl phosphonate, diisooctyl isopropyl phosphonate and butyl dibutyl phosphonate; a ratio of extractants is adjusted; the extraction section, the washing section and the back extraction section are completed by at least three stages of ultrasonic mixer clarification devices; and during the washing, quaternary ammonium salt cations [N(C2H5)4]<+> (or [N(C3H7)4]<+>) are added to the washing liquid to improve the SO4<2-> removing efficiency. According to the present invention, the method and the apparatus are used in the industrial production of food grade phosphoric acid from wet-process phosphoric acid so as to significantly shorten the purificationprocess, reduce the consumption, and ultimately reduce the production cost of the entire process.

Description

technical field

[0001] The invention relates to a process method for purifying low-concentration wet-process phosphoric acid, in particular to a process method and a purifying device for purifying low-concentration wet-process phosphoric acid into food-grade phosphoric acid by solvent extraction. Background technique

[0002] Wet-process phosphoric acid has the characteristics of low production cost but high impurity content. In order to replace the high-cost thermal phosphoric acid, scientific and technological workers have been trying to develop wet-process phosphoric acid purification technology, mainly including chemical precipitation, organic solvent extraction, ion exchange, physical adsorption and crystallization. Among them, the solvent extraction method has the characteristics of high product purity, simple process equipment, low energy consumption, and large production capacity, and has gradually been widely used in industrial applications. Solvent extraction puri...

Examples

Embodiment 1

[0029] Embodiment 1: The technological process of 6000 tons / year purification wet-process phosphoric acid is as follows:

[0030] Concentration is 34wt%P 2 o 5 The raw material of wet-process phosphoric acid is settled and filtered, and Na is added to it 2 CO 3 , at 60-80°C, the reaction generates Na 2 SiF 6 Precipitate and filter to obtain pretreated defluorinated raw phosphoric acid, which enters the raw acid tank of the purification section.

[0031] The pretreated raw material wet-process phosphoric acid and organic solvent (a mixed solution of butyl phosphonate and dimethylheptyl phosphate, volume ratio 1:2, specific gravity 0.946) are metered by the pump to control the two-phase phase Ratio, and sent to the mixing chamber. At room temperature, the raw phosphoric acid and organic solvent are fully mixed, and the phosphoric acid enters the organic phase to obtain an extracted organic phase with a specific gravity of 1.206, and most impurities enter the raffinate. In...

Embodiment 2

[0034] Embodiment 2: Embodiment 1: the technological process of 15000 tons / year purification wet-process phosphoric acid is as follows:

[0035] Concentration of 42wt% P 2 o 5 The raw material of wet-process phosphoric acid is settled and filtered, and Na is added to it 2 CO 3 , at 68~88℃, the reaction generates Na 2 SiF 6 Precipitate and filter to obtain pretreated defluorinated raw phosphoric acid, which enters the raw acid tank of the purification section.

[0036] Pretreated raw material wet-process phosphoric acid and organic solvent (mixed solution of dibutyl butyl phosphonate, diisooctyl isopropyl phosphonate and butyl dibutyl phosphonate, the volume ratio is 3:4:3, Specific gravity 0.939) is measured by the pump to control the two-phase phase ratio, and transported to the mixing chamber. At room temperature, the raw phosphoric acid and the organic solvent are fully mixed, and the phosphoric acid enters the organic phase to obtain an extracted organic phase with a...

technical field

[0001] The invention relates to a process method for purifying low-concentration wet-process phosphoric acid, in particular to a process method and a purifying device for purifying low-concentration wet-process phosphoric acid into food-grade phosphoric acid by solvent extraction. Background technique

[0002] Wet-process phosphoric acid has the characteristics of low production cost but high impurity content. In order to replace the high-cost thermal phosphoric acid, scientific and technological workers have been trying to develop wet-process phosphoric acid purification technology, mainly including chemical precipitation, organic solvent extraction, ion exchange, physical adsorption and crystallization. Among them, the solvent extraction method has the characteristics of high product purity, simple process equipment, low energy consumption, and large production capacity, and has gradually been widely used in industrial applications. Solvent extraction puri...

Examples

Embodiment 1

[0029] Embodiment 1: The technological process of 6000 tons / year purification wet-process phosphoric acid is as follows:

[0030] Concentration is 34wt%P 2 o 5 The raw material of wet-process phosphoric acid is settled and filtered, and Na is added to it 2 CO 3 , at 60-80°C, the reaction generates Na 2 SiF 6 Precipitate and filter to obtain pretreated defluorinated raw phosphoric acid, which enters the raw acid tank of the purification section.

[0031] The pretreated raw material wet-process phosphoric acid and organic solvent (a mixed solution of butyl phosphonate and dimethylheptyl phosphate, volume ratio 1:2, specific gravity 0.946) are metered by the pump to control the two-phase phase Ratio, and sent to the mixing chamber. At room temperature, the raw phosphoric acid and organic solvent are fully mixed, and the phosphoric acid enters the organic phase to obtain an extracted organic phase with a specific gravity of 1.206, and most impurities enter the raffinate. In...

Embodiment 2

[0034] Embodiment 2: Embodiment 1: the technological process of 15000 tons / year purification wet-process phosphoric acid is as follows:

[0035] Concentration of 42wt% P 2 o 5 The raw material of wet-process phosphoric acid is settled and filtered, and Na is added to it 2 CO 3 , at 68~88℃, the reaction generates Na 2 SiF 6 Precipitate and filter to obtain pretreated defluorinated raw phosphoric acid, which enters the raw acid tank of the purification section.

[0036] Pretreated raw material wet-process phosphoric acid and organic solvent (mixed solution of dibutyl butyl phosphonate, diisooctyl isopropyl phosphonate and butyl dibutyl phosphonate, the volume ratio is 3:4:3, Specific gravity 0.939) is measured by the pump to control the two-phase phase ratio, and transported to the mixing chamber. At room temperature, the raw phosphoric acid and the organic solvent are fully mixed, and the phosphoric acid enters the organic phase to obtain an extracted organic phase with a...

Images