A system for preparing feed-grade phosphoric acid by wet-process phosphoric acid and its preparation method

A wet-process phosphoric acid, feed-grade technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of low defluorination efficiency, high cost of liquid-solid separation, large loss of phosphorus, etc., to improve the yield of phosphorus , to avoid the effect of excessive phosphoric acid concentration

Active Publication Date: 2021-09-03
YUNNAN PHOSPHATE CHEM GROUP CORP
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AI Technical Summary

Problems solved by technology

[0002] Feed-grade phosphoric acid is prepared by wet-process phosphoric acid. The key technology of the purification process is defluorination. At present, the domestic feed-grade phosphoric acid purification process has the following problems: (1) Large loss of phosphorus: At present, domestic feed-grade wet-process phosphoric acid purification uses chemical precipitation to defluorinate more, Chemical defluorination is the use of alkaline Na 2 CO 3 The formation of sodium fluorosilicate with fluorosilicate is achieved by utilizing the low solubility of sodium fluorosilicate in phosphoric acid. In phosphoric acid P 2 o 5 Under the condition of concentration of 40-47%, harmful impurities such as sulfate radicals, heavy metal ions and fluoride ions in phosphoric acid will form solid phase precipitates, and liquid-solid separation methods such as vacuum filtration or mechanical pressure filtration are used to realize phosphoric acid purification, but the solid phase contains walk a lot of P 2 o 5 , high phosphorus loss, high cost of liquid-solid separation; (2) low defluorination efficiency: gas stripping defluorination process, concentrated phosphoric acid is defluorinated by gas after removing sulfate and heavy metal ions, and the final product phosphoric acid P 2 o 5 / F reaches 300 to meet the quality requirements of feed-grade phosphoric acid. The gas stripping defluorination process is mostly single-stage defluorination, intermittent production, and the defluorination efficiency is low, especially when the Fe, Al, and Mg impurities in phosphoric acid are high ((Fe 2 o 3 +Al 2 o 3 +MgO) / P 2 o 5 >0.08) The defluorination efficiency is greatly reduced; (3) In the air stripping defluorination phosphoric acid purification process, in order to improve the air stripping defluorination efficiency, the general process is to concentrate dilute phosphoric acid to obtain P 2 o 5 Concentrated phosphoric acid with a concentration of 48-50%. During the aging process of concentrated phosphoric acid, impurities such as Fe and Al in phosphoric acid will form iron and aluminum phosphate precipitates. At the same time, F in phosphoric acid will also form some fluoride salts with fine crystal particles. For aging and sedimentation separation, it is necessary to recover phosphoric acid with higher solid content in the lower part of the sedimentation tank, that is, slag acid (the proportion of slag acid is generally 30%), and a filter press is generally used, but the cost of phosphoric acid filter press operation is high and the loss of phosphorus is large; Before the acid cleaning in the upper part of the cleaning tank is sent to the air stripping defluorination, a phosphoric acid filtration process is generally set up to further reduce the solid phase in the concentrated phosphoric acid (this solid phase is mostly fluorine salt with fine crystal particles). At present, phosphoric acid filtration is also a difficult problem , some slag acid will also be produced during the operation, and the cost is relatively high

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  • A system for preparing feed-grade phosphoric acid by wet-process phosphoric acid and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] figure 1 It shows: a system for preparing feed-grade phosphoric acid from wet-process phosphoric acid, which is composed of a graded concentration defluorination section 1, a gas stripping defluorination section 2, and a steam defluorination section 3.

[0035] The fractional concentration and defluorination section 1 is composed of a dilute acid aging tank 101, a dilute acid settling tank 102, a primary concentration unit 103, a weight removal reaction tank 104, an intermediate acid settling tank 105, and a secondary concentration unit 106, which are connected in sequence. Composition, the outlet at the bottom of the intermediate acid settling tank 105 is connected to the inlet of the dilute acid settling tank 102, the outlet at the bottom of the dilute acid settling tank 102 is connected to the phosphoric acid production device, and the inlet of the dilute acid aging tank 101 is connected to the phosphoric acid production device.

[0036] The primary concentration uni...

Embodiment 2

[0040] A preparation method for wet process phosphoric acid to prepare feed grade phosphoric acid, specifically comprising the steps of:

[0041] (1) Fractional concentration and defluorination purification:

[0042] 1-1. Pump the dilute phosphoric acid obtained in the production of wet-process phosphoric acid into the dilute acid aging tank 101, and add a desulfurizing agent to remove sulfate radicals; the desulfurizing agent is phosphate rock slurry with a grade of 30% and containing The solid content is 60%, and the addition amount of phosphate rock is controlled by 1.0 times of the theoretically calculated amount.

[0043] 1-2. Pump the desulfurized dilute phosphoric acid into the dilute acid settling tank 102 for clarification to obtain P 2 o 5 Concentration of 25%, F content of 2.2% of the upper cleaning acid, dilute acid sedimentation tank 102 bottom slag acid is returned to the phosphoric acid production device, the upper cleaning acid is pumped into the primary conc...

Embodiment 3

[0052] A preparation method for wet process phosphoric acid to prepare feed grade phosphoric acid, specifically comprising the steps of:

[0053] (1) Fractional concentration and purification:

[0054] 1-1. Pump the dilute phosphoric acid obtained in the production of wet-process phosphoric acid into the dilute acid aging tank 101, and add a desulfurizer to remove sulfate radicals; the desulfurizer is phosphate rock pulp, the grade of which is 32%, and the The amount is 63%, and the addition amount of phosphate rock is controlled by 1.1 times of the theoretically calculated amount.

[0055] 1-2. Pump the desulfurized dilute phosphoric acid into the dilute acid settling tank 102 for clarification to obtain P 2 o 5 Concentration of 26%, F content of 2.5% of the upper cleaning acid, dilute acid settling tank 102 bottom slag acid is returned to the phosphoric acid production device, the upper cleaning acid is pumped into the primary concentration unit 103 for concentration;

[...

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Abstract

The invention discloses a system and a preparation method for preparing feed-grade phosphoric acid from wet-process phosphoric acid, and relates to the technical field of phosphoric acid production. The preparation method is composed of processes such as wet-process phosphoric acid desulfate radical removal, heavy metal removal, graded concentration defluorination, air stripping defluorination, steam defluorination and the like. Using wet-process phosphoric acid as raw material to remove sulfate and heavy metal ions in phosphoric acid under different phosphoric acid concentration conditions, the feed grade is completed by using steps such as fractional concentration defluorination section, multi-stage series gas defluorination section and steam defluorination section. Purify phosphoric acid to obtain high-quality feed-grade phosphoric acid. The method for preparing feed-grade phosphoric acid by wet-process phosphoric acid does not require phosphoric acid filtration or pressure filtration, and no slag phosphoric acid and solid waste are generated during the process, with high phosphorus yield, high defluorination efficiency, good recovery of fluorine resources, and P in the product phosphoric acid. 2 o 5 The / F can reach more than 300, the process continuity is good, the device capacity is large, and it also has the characteristics of low comprehensive energy consumption and excellent investment. The maximum can reach 300,000 tons P 2 o 5 / year.

Description

technical field [0001] The invention relates to the technical field of phosphoric acid production, in particular to a system for preparing feed-grade phosphoric acid from wet-process phosphoric acid and a preparation method thereof. Background technique [0002] Feed-grade phosphoric acid is prepared by wet-process phosphoric acid. The key technology of the purification process is defluorination. At present, the domestic feed-grade phosphoric acid purification process has the following problems: (1) Large loss of phosphorus: At present, domestic feed-grade wet-process phosphoric acid purification uses chemical precipitation to defluorinate more, Chemical defluorination is the use of alkaline Na 2 CO 3 The formation of sodium fluorosilicate with fluorosilicate is achieved by utilizing the low solubility of sodium fluorosilicate in phosphoric acid. In phosphoric acid P 2 o 5 Under the condition of concentration of 40-47%, harmful impurities such as sulfate radicals, heavy m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/237C01B25/235
CPCC01B25/2343C01B25/235
Inventor 朱剑锋张卫红
Owner YUNNAN PHOSPHATE CHEM GROUP CORP
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