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Method for recycling high-purity fluorine and phosphorus from wastewater of phosphogypsum residue field

A phosphogypsum, high-purity technology, applied in chemical instruments and methods, phosphorus compounds, water/sewage multi-stage treatment, etc., can solve problems such as large fluctuations in fluoride ions, large amounts of sludge, waste of resources, etc., and achieve phosphorus recovery rate High, high recovery rate, the effect of realizing resource recycling

Inactive Publication Date: 2013-01-23
HUBEI FORBON TECH
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  • Description
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Problems solved by technology

[0005] The purpose of the present invention is to solve the following problems in the prior art: the backwater of the conventional phosphogypsum slag field adopts the quicklime treatment precipitation process to remove fluoride ions and calcium ions in the wastewater, and the fluoride ions of the effluent quality fluctuate greatly, which is difficult to reach the standard. Moreover, fluorine and phosphorus are mostly removed in the form of impurity precipitation, which not only generates a large amount of sludge, but also wastes resources

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  • Method for recycling high-purity fluorine and phosphorus from wastewater of phosphogypsum residue field

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Embodiment 1

[0025] The wastewater discharge volume of a phosphogypsum slag yard in a chemical plant is 5000m3 / d, of which the phosphorus content in the wastewater is 5200mg / l, the fluorine content is 1500mg / l, the calcium ion content is 2300mg / l, and the pH of the wastewater is 2.3; the molar concentration of the first stage process is 1mol / l sodium hydroxide solution to adjust the pH of wastewater from the phosphogypsum slag field to 5.3, with calcium fluoride precipitation and a small amount of calcium phosphate precipitation formed. After analysis, the purity of calcium fluoride is 95%, and the recovery rate of fluorine is 99%. Among them, the residual fluorine in the wastewater Phosphorus is 15mg / l, phosphorus is 4698mg / l, calcium is 20mg / l; the second stage process uses sodium hydroxide solution with a molar concentration of 1mol / l to adjust the pH of phosphogypsum slag field wastewater to pH8.2, and the added concentration is 1mol / l chlorination 750ml of ammonium solution and 780ml ...

Embodiment 2

[0027] The wastewater discharge of a phosphogypsum slag yard in a chemical plant is 5000m3 / d, of which the phosphorus content in the wastewater is 10000mg / l, the fluorine content is 500mg / l, the calcium ion content is 1300mg / l, and the pH of the wastewater is 1.0; the molar concentration of the first stage process is 1mol / l sodium hydroxide solution to adjust the pH of phosphogypsum slag field wastewater to 3.0, calcium fluoride precipitation and a small amount of calcium phosphate precipitation are formed, the purity of calcium fluoride is 96% after analysis, the recovery rate of fluorine is 98%, and the residual fluorine in the wastewater 10mg / l, 9200mg / l phosphorus, and 15mg / l calcium; the second stage of the process uses a sodium hydroxide solution with a molar concentration of 1mol / l to adjust the pH of the phosphogypsum slag field wastewater to pH7.5, and the added concentration is 2mol / l bicarbonate 740ml of ammonium solution and 780ml of magnesium chloride solution wit...

Embodiment 3

[0029] The wastewater discharge volume of a phosphogypsum slag yard in a chemical plant is 5000m3 / d, of which the phosphorus content in the wastewater is 7000mg / l, the fluorine content is 3500mg / l, the calcium ion content is 6000mg / l, and the pH of the wastewater is 3.0; the molar concentration of the first stage process is 1mol / l sodium hydroxide solution to adjust the pH of wastewater from phosphogypsum slag field to 6.0, calcium fluoride precipitation and a small amount of calcium phosphate precipitation are formed, the purity of calcium fluoride is 99% after analysis, the recovery rate of fluorine is 99.7%, and the residual fluorine in the wastewater It is 15mg / l, phosphorus is 5800mg / l, and calcium is 25mg / l. After the treatment, an appropriate amount of ammonium bicarbonate is added to remove calcium ions, and the introduction of ammonium ions can participate in the second stage of the reaction of ammonium magnesium phosphate; The molar concentration is 1mol / l sodium hyd...

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Abstract

The invention relates to a method for recycling high-purity fluorine and phosphorus from a wastewater of phosphogypsum residue field. According to the different reaction conditions of calcium fluoride and magnesium ammonium phosphate, the implementation of the method is divided into two stages: in the first stage of recycling high-purity calcium fluoride: adjusting the pH (Potential Of Hydrogen) value of the wastewater of the phosphogypsum residue field by a sodium hydroxide solution to 3-6 to enable the fluoride ions and calcium ions in the wastewater to be reacted to generate calcium fluoride precipitate, filtering and recycling calcium fluoride; and the second stage of recycling high-purity magnesium ammonium phosphate: adjusting the pH value of the wastewater after the first section of recycling high-purity calcium fluoride by the sodium hydroxide solution to 7.5-9.5, adding a magnesium source and an ammonia source at the same time, generating magnesium ammonium phosphate, magnesium ammonium phosphate analogs or phosphate compounds in a crystalline state in a magnesium ammonium phosphate crystallization reactor, filtering and recycling magnesium ammonium phosphate. The water treated by the method disclosed by the invention has low impurity content and can be directly used as the industrial water and circulating cooling water in a phosphorus chemical production system.

Description

technical field [0001] The invention relates to the field of waste water treatment, in particular to recovering fluorine in the form of calcium fluoride and recovering phosphorus in the form of ammonium magnesium phosphate slow-release fertilizer in the waste water of phosphogypsum slag field. Background technique [0002] Phosphogypsum is a by-product of wet-process phosphoric acid production, and 4.5-5.5 tons (dry basis) of phosphogypsum is produced per ton of phosphoric acid, and its composition is related to the phosphate rock used and the process flow. Phosphogypsum contains water-soluble phosphorus pentoxide and fluoride ions. With the development of phosphoric acid and high-concentration phosphate fertilizer industry in China, the amount of phosphogypsum discharged every year is increasing, and the pollution to the environment is also becoming serious, especially when phosphogypsum passes through rainwater. After leaching, the dissolved pollutants will pollute surface...

Claims

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Application Information

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IPC IPC(8): C01F11/22C01B25/45C02F9/04
Inventor 王仁宗沙淮丽李厚涛王瑞潘春翔柴源
Owner HUBEI FORBON TECH
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