Method of recycling phosphorus in concentrated acid residue from wet process phosphoric acid and co-producing dihydrate gypsum and sodium fluosilicate

A technology of sodium fluorosilicate and dihydrate gypsum, which is applied in the fields of fluorosilicic acid, chemical instruments and methods, and silicon halide compounds, and can solve problems such as difficult disposal of waste residue, low efficiency of solid phase settlement, and large loss of phosphoric acid

Active Publication Date: 2018-03-23
SINOCHEM YUNLONG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] During the concentration process of dilute phosphoric acid, not only dihydrate gypsum will be transformed into hemihydrate gypsum with fine crystals and a certain amount of intercrystalline phosphorus (citrate-soluble phosphorus), but also fine crystalline fluorine salts and phosphates will also be precipitated, resulting in concentrated phosphoric acid. Low solid phase settling efficiency, high output of slag acid, large loss of phosphoric acid, and difficult disposal of waste slag

Method used

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  • Method of recycling phosphorus in concentrated acid residue from wet process phosphoric acid and co-producing dihydrate gypsum and sodium fluosilicate
  • Method of recycling phosphorus in concentrated acid residue from wet process phosphoric acid and co-producing dihydrate gypsum and sodium fluosilicate
  • Method of recycling phosphorus in concentrated acid residue from wet process phosphoric acid and co-producing dihydrate gypsum and sodium fluosilicate

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Experimental program
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Effect test

Embodiment 1

[0037] The composition of the concentrated slag acid of raw material wet-process phosphoric acid used in the present embodiment is as follows:

[0038]

[0039]The wet-process phosphoric acid concentrated slag acid and water with the above indicators are prepared at a mass ratio of 1:0.5, and added to the crystal conversion tank. Then add concentrated sulfuric acid with 1.5% slag acid content, 1% calcium sulfate dihydrate, 8% fluosilicic acid, 0.005% diammonium phosphate, crystal transformation temperature 55°C, stirring line speed 0.7m / s, crystal transformation time 120 minutes. After the crystal conversion is completed, the material enters the suspension separator, the stirring line speed is 0.5m / s, and the material residence time is 120 minutes. The slurry discharged from the bottom of the suspension separator is filtered and separated, and the filter residue is mixed with water at a ratio of 1:1. The pH of the gypsum slurry is adjusted to 3 with sulfuric acid. The puri...

Embodiment 2

[0041] The composition of the concentrated slag acid of raw material wet-process phosphoric acid used in the present embodiment is as follows:

[0042]

[0043] The wet-process phosphoric acid concentrated slag acid and water with the above indicators are prepared at a mass ratio of 1:1, and added to the crystal conversion tank. Then add 3% concentrated sulfuric acid, 2% calcium sulfate dihydrate, 12% fluosilicic acid, 0.005% ethoxylated alkyl sulfate sodium salt, 0.01% fatty alcohol polyoxyethylene ether sodium sulfate For salt, the crystallization temperature is 60°C, the linear stirring speed is 0.8m / s, and the crystallization time is 110 minutes. After the crystal conversion is completed, the material enters the suspension separator, the stirring line speed is 0.6m / s, and the material residence time is 140 minutes. The slurry discharged from the bottom of the suspension separator is filtered and separated, and the filter residue is mixed with water at a ratio of 1:1.2....

Embodiment 3

[0045] The composition of the concentrated slag acid of raw material wet-process phosphoric acid used in the present embodiment is as follows:

[0046]

[0047] The wet-process phosphoric acid concentrated slag acid and water with the above indicators are prepared at a mass ratio of 1:1.2, and added to the crystal conversion tank. Then add concentrated sulfuric acid with 4% slag acid content, 1.5% calcium sulfate dihydrate, 0.01% diammonium phosphate, 0.01% triethanolamine dodecylbenzenesulfonate, crystal transition temperature 55°C, stirring line speed 0.8m / s, the crystallization time is 100 minutes. After the crystal conversion is completed, the material enters the suspension separator, the stirring line speed is 0.6m / s, and the material residence time is 130 minutes. The slurry discharged from the bottom of the suspension separator is filtered and separated, and the filter residue is mixed with water at a ratio of 1:1.6. The pH of the gypsum slurry is adjusted to 5 wit...

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Abstract

The invention relates to the field of development and application of phosphorus chemical techniques and particularly discloses a method of recycling phosphorus in concentrated acid residue from wet process phosphoric acid and co-producing dihydrate gypsum and sodium fluosilicate. The method comprises: proportionally mixing concentrated acid residue from wet process phosphoric acid and process water, and adding the mixture into a crystal transformer trough; adding a crystal transformation control agent and a crystal transformation aid proportionally into the crystal transformer trough to perform semi-hydrated gypsum crystal transformation; after crystal transformation, feeding slurry into a suspension separator to perform precipitating separation; discharging the slurry from the bottom of the suspension separator, filtering the slurry, purifying with gypsum, filtering, and washing to obtain finished dihydrate gypsum; discharging slurry from the top of the suspension separator, filteringthe slurry, purifying for sodium fluosilicate, filtering, and washing to obtain finished sodium fluosilicate. Filtrates obtained may be returned directly to a phosphorite extraction trough or a dilute phosphoric storage trough. The method of the invention has the advantages that recycling of phosphorus in concentrated acid residue from wet process phosphoric acid and comprehensive use of waste residue are achieved, utilization value of the concentrated acid residue is improved, the process is simple, phosphorus recycling rate is high, no waste residue is produced, and the economic benefit issignificant.

Description

[0001] A method for recovering phosphorus in concentrated slag acid of wet-process phosphoric acid and co-producing dihydrate gypsum and sodium fluorosilicate. technical field [0002] The invention relates to the field of development and application of phosphorus chemical technology, in particular to a method for recovering phosphorus in wet-process phosphoric acid concentrated slag acid and co-producing dihydrate gypsum and sodium fluorosilicate. Background technique [0003] The wet-process phosphoric acid process is mainly based on the dihydrate method. The phosphate rock is extracted and reacted with sulfuric acid to obtain 22-25% dilute phosphoric acid, which is then concentrated to obtain 40-45% concentrated phosphoric acid. During the concentration process, as the water in the dilute phosphoric acid is evaporated, the concentration of phosphoric acid increases, resulting in the supersaturation of impurities dissolved in phosphoric acid and a large amount of precipitat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/10C01F11/46
CPCC01B33/103C01F11/466C01P2006/80
Inventor 颜跃勇盛勇周佩付全军陈明凤田萍
Owner SINOCHEM YUNLONG
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