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Method for producing phosphoric acid by hemihydrate technique

A phosphoric acid and process technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problem of unfavorable phosphate rock fully reacting to the growth of calcium sulfate hemihydrate crystals, inconvenient for phosphogypsum transport, transportation and recycling, filtration and separation, and Problems such as poor washing effect, to achieve the effect of convenient semi-aqueous reaction temperature, simplified and stable operation control, and stable semi-aqueous reaction temperature

Active Publication Date: 2012-09-19
GUIZHOU CHANHEN CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0010] ⑴ The four stages required for the wet phosphoric acid reaction of the hemihydrate method are not obvious, which is not conducive to the full reaction of phosphate rock and the growth of calcium sulfate hemihydrate crystals, which makes the decomposition and washing effect worse. The P in phosphogypsum 2 o 5 The content reaches more than 1.5-2%, and the overall phosphorus yield is low, generally only reaching 89-92%.
[0011] (2) Sulfuric acid is directly added to the reaction tank, and it is easy to form partial supersaturation of sulfuric acid at the place where sulfuric acid is added to acid, and it is easy to form more fine calcium sulfate hemihydrate crystals.
[0012] (3) In order to increase the yield of phosphorus as much as possible, wet slag discharge is generally adopted, which is not convenient for the transportation and later recycling of phosphogypsum
[0014] (5) The sulfate concentration in the slurry phase of the reaction material is controlled at 2.0-3.5wt%, which leads to high consumption of sulfuric acid and high production costs

Method used

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  • Method for producing phosphoric acid by hemihydrate technique
  • Method for producing phosphoric acid by hemihydrate technique
  • Method for producing phosphoric acid by hemihydrate technique

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] The method is carried out in the following steps: premixing of phosphate rock and slurry return, decomposition of phosphate rock, crystallization and slurry return, crystal growth, filtration and washing, and acid return.

[0062] The indicators of phosphate rock for production are as follows:

[0063] P 2 o 5 %

CaO%

MgO%

h 2 O%

Fe 2 o 3

al 2 o 3

Acid insoluble %

33.05

48.21

0.76

12.97

0.46

0.47

5.6

[0064] 1. Phosphate rock is premixed with the return slurry from the crystallization tank 3

[0065] The phosphate rock powder feeds continuously at 80t / h into the premixing tank 1, and the slurry from the crystallization tank 3 cooled by the flash evaporator 7 feeds at 1000m 3 Enter in / h, premix and react in premix tank 1, the reaction temperature is 90°C, and the indicators in the premix tank are as follows:

[0066]

[0067] The return index is as follows:

[0068] ...

Embodiment 2

[0078] The method is carried out in the following steps: premixing of phosphate rock and slurry return, decomposition of phosphate rock, crystallization and slurry return, crystal growth, filtration and washing, and acid return.

[0079] The indicators of phosphate rock for production are as follows:

[0080] P 2 o 5 %

CaO%

MgO%

h 2 O%

Fe 2 o 3

Al 2 o 3

Acid insoluble %

32.5

47.6

1.40

13.4

0.8

0.5

5.4

[0081] 1. Premixing of phosphate rock and return slurry

[0082] Phosphate rock powder feed rate is 85t / h, 1150m 3 The amount of pulp return per hour is pre-reacted in the premixing tank 1, the reaction temperature is 95°C, and the indicators in the premixing tank 1 are as follows:

[0083] P 2 o 5 %

CaO%

slurry ratio

filtrate acid

Solid content

[0084]

Heavy

specific gravity

％

43.35

1.01

1.76...

example 3

[0096] The method is carried out in the following steps: premixing of phosphate rock and slurry return, decomposition of phosphate rock, crystallization and slurry return, crystal growth, filtration and washing, and acid return.

[0097] The indicators of phosphate rock for production are as follows:

[0098] P 2 o 5 %

CaO%

MgO%

h 2 O%

Fe 2 o 3

Al 2 o 3

Acid insoluble %

34.36

48.23

1.17

12.95

0.46

0.81

6.4

[0099] 1. The amount of phosphate rock powder is 78t / h, 1000m 3 The amount of slurry returned per hour is pre-reacted in the premixing tank 1, the reaction temperature is 97°C, and the indicators in the premixing tank 1 are as follows:

[0100]

[0101] The return index is as follows:

[0102]

[0103] 2. Decomposition of phosphate rock

[0104] The semi-aqueous slurry overflows to the decomposition tank 2 for further decomposition reaction, and the reaction temperatur...

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Abstract

The invention discloses a method for producing phosphoric acid by a hemihydrate technique, belonging to the field of phosphoric acid production by a wet process. The invention aims to provide a method for producing phosphoric acid by a hemihydrate technique, which can enhance the phosphorus yield. The method comprises the following steps: a. pre-reaction: controlling sulfuric acid in a return slurry of a crystallization tank and CaO added into ground phosphorite in a mol ratio of (0.4-0.6):1; b. entering a decomposing tank for further reaction; c. entering the crystallization tank to react with a solution formed by thoroughly mixing a phosphoric acid solution and sulfuric acid to form crystals, and controlling the mass ratio of the sulfate group in the slurry acid liquor to the acid liquor at 1.5-2.0%; d. entering a grain growing tank to promote crystal growth; and e. filtering to obtain the finished phosphoric acid product. The method disclosed by the invention has the advantage of more optimized and reasonable process, is simpler and more stable to operate and control, and can obtain high phosphorus yield.

Description

technical field [0001] The invention belongs to the field of wet-process phosphoric acid production, and in particular relates to a method for producing phosphoric acid by a semi-water process. Background technique [0002] The wet-process phosphoric acid process is the process of decomposing phosphate rock with inorganic acid (mainly sulfuric acid) to produce phosphoric acid, that is, reacting sulfuric acid with phosphate rock to form calcium sulfate crystals and phosphoric acid solution, and then separating liquid and solid to obtain phosphoric acid. [0003] According to the current known literature and data, except for the anhydrous process, there are no industrialized devices in other processes, and all other processes have been built and put into operation. Among the various processes, the devices using the dihydric method account for 85%; In terms of current research, in the production of wet-process phosphoric acid, the directly obtained phosphoric acid concentration...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/226
Inventor 李进王佳才李顺方赵鹏唐晓林吴生平赵东
Owner GUIZHOU CHANHEN CHEM CO LTD
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