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Preparation and applications of wet-process strong phosphoric acid desulfurizing agent

A desulfurizer, concentrated phosphoric acid technology, applied in the field of phosphorus chemical industry, can solve the problems of high phosphorus content in filter residues, incomplete decomposition of phosphate rock, excessive phosphate rock, etc., and achieves rapid desulfurization, significant economic and environmental benefits, and desulfurization. good effect

Inactive Publication Date: 2014-01-29
WENGFU (GRP) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the wet-process phosphoric acid purification process generally uses phosphate rock powder to remove sulfate radicals in concentrated phosphoric acid in the pretreatment stage, and uses phosphor rock powder to remove sulfate radicals. Disadvantages such as high phosphorus content in medium and slow decomposition of phosphate rock lead to long reaction time

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0030] The preparation method of desulfurizer is:

[0031] (1) When the phosphorus content is 0.4% to 2.4%, the fluorine content is 0.4% to 2.0%, SO 4 2- Add lime milk with a CaO concentration of 10% to 25% to the waste water with a content of 0.3% to 0.8%. The amount of lime milk added is 1.5 to 2.4 times the mass of fluorine in the waste water as CaO in the lime milk. Stir and react at room temperature for 0.5 to 1h, then filter to obtain purified liquid and solid phase precipitation residue;

[0032] (2) Add milk of lime with a concentration of CaO of 10% to 25% in the obtained purification solution. The amount of milk of lime added is 1.4 to 1.8 times the mass of phosphorus in the purification solution as CaO in the milk of lime. Stir and react at room temperature for 0.5 to 1.5 h, then filter, the filter cake is dried to obtain desulfurizer, and the filtrate is purified and returned to the phosphoric acid production system for use as process water.

[0033]...

Embodiment 1

[0037] When the phosphorus content is 1.8%, the fluorine content is 1.2%, SO 4 2- Add 101kg of lime milk with a CaO concentration of 20% to 1 ton of waste water with a content of 0.5%, stir and react at room temperature for 40 minutes, and then filter to obtain a purified solution (1002kg, with a phosphorus content of 1.65%) and solid phase precipitation residue.

[0038] Add 124 kg of milk of lime with a CaO concentration of 20% to the obtained purified solution, stir and react at room temperature for 1 hour, and then filter to obtain a filter cake containing about 40% of free water. After purification, the filtrate is returned to the phosphoric acid production system as process water for use. The filter cake is dried to obtain 105kg of desulfurizer, its components and mass percentages are: CaHPO 4 ·2H 2 O: 74%, Ca(H 2 PO 4 ) 2 ·H 2 O: 4%, CaF 2 : 3%, CaSO 4 ·2H 2 O: 7%, CaCO 3 : 3%, others are impurities.

[0039] Combine the gai...

Embodiment 2

[0041] When the phosphorus content is 2.4%, the fluorine content is 2.0%, SO 4 2- Add 192kg of lime milk with a CaO concentration of 25% to 1 ton of wastewater with a content of 0.8%, stir and react at room temperature for 1 hour, and then filter to obtain a purified solution (979kg, with a phosphorus content of 2.0%) and solid-phase precipitation residue.

[0042] Add 141 kg of milk of lime with a CaO concentration of 25% to the obtained purified solution, stir and react at room temperature for 1.5 hours, and then filter to obtain a filter cake containing about 50% of free water. After purification, the filtrate is returned to the phosphoric acid production system as process water for use. The filter cake is dried to obtain 123kg of desulfurizer, its components and mass percentages are: CaHPO 4 ·2H 2 O: 80%, Ca(H 2 PO 4 ) 2 ·H 2 O: 3%, CaF 2 : 1%, CaSO 4 ·2H 2 O: 2%, CaCO 3 : 5%, others are impurities.

[0043] Combine the gained ...

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Abstract

The invention discloses a preparation and applications of a wet-process strong phosphoric acid desulfurizing agent. The desulfurizing agent comprises the following components in percentage by mass: 65%-80% of CaHPO4.2H2O.CaSO4, 3%-10% of Ca(H2PO4)2.H2O, 1%-10% of CaF2, 2%-10% of CaSO4.2H2O, 0.5%-5% of CaCO3, and the balance of impurities. The desulfurizing agent is prepared by the steps of: adding a certain amount of calcium hydroxide at normal temperature according to the quantity of fluorine in waste water, stirring for reacting, filtering, adding calcium hydroxide into a filtrate, drying the secondary filter cake to obtain the desulfurizing agent; mixing the desulfurizing agent and phosphoric acid with mass percentage concentration of P2O5 being15%-30% according to the mass of sulfate radical, forming slurry to be added into phosphoric acid with 40-54% ofP2O5 and 2.5%-6.5% of SO4<2->, carrying out desulfurization reaction at 50-80DEG C, and desulfurizing. The preparation has the characteristics of designing the treatment technology, changing waste water treatment process into a process of preparing a desulfurizing agent mainly containing phosphorus containing calcium salt precipitate, the desulfurizing agent can be used for removing sulfate radicals out of the wet-process strong phosphoric acid, is good in desulfurization effect, the phosphorous resource in the waste water can also be recovered, and the economic benefits and environment-friendly benefits are remarkable.

Description

technical field [0001] The invention relates to the field of phosphorus chemical industry, in particular to the preparation and application of a wet-process concentrated phosphoric acid desulfurizer. Background technique [0002] In the dihydrate wet-process phosphoric acid production process commonly used in my country, sulfuric acid must be in excess to obtain dihydrate gypsum crystals that are easy to filter. Therefore, there is a certain amount of sulfate radicals in the obtained wet-process phosphoric acid. At present, the wet-process phosphoric acid purification process generally uses phosphate rock powder to remove sulfate radicals in concentrated phosphoric acid in the pretreatment stage, and uses phosphor rock powder to remove sulfate radicals. The disadvantages of high phosphorus content in medium and slow decomposition of phosphate rock lead to long reaction time. [0003] Based on the current status of pretreatment desulfurization of wet-process concentrated pho...

Claims

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Application Information

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IPC IPC(8): C01B25/237
Inventor 刘旭何浩明解田胡宏龙庆兰杨俊
Owner WENGFU (GRP) CO LTD
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