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Method for extraction of ammonium thiocyanate and ammonium sulfate from coke-oven gas ammonia process desulfurization waste liquid

A desulfurization waste liquid, ammonium thiocyanate technology, applied in thiocyanate, chemical instruments and methods, ammonia compounds and other directions, can solve the problems of environmental protection problems, low product prices, and site corrosion that plague coal coking enterprises, and achieve suitable Industrial promotion and application, good economic benefits, and the effect of thorough treatment

Active Publication Date: 2018-08-24
扬州康龙环保工程有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This negative treatment method has very serious consequences, mainly in the following aspects: 1. The treatment capacity is very limited, and it is impossible to add it in the rainy season; 2. It is very corrosive to the equipment and the operating environment deteriorates; 3. The coal The maintenance work of the tower equipment cannot be carried out normally; 4. Increase the energy consumption in the coking process; 5. Serious corrosion to the site; 6. The valuable chemical raw materials are not well utilized; cause new pollution
[0004] From this point of view, it is not advisable to use the method of spraying desulfurization liquid on the coal pile
Moreover, the thiocyanate ions contained in the desulfurization waste liquid have a strong bactericidal effect and cannot be biochemically treated. How to treat and comprehensively utilize the desulfurization and decyanation waste liquid has always been an environmental protection problem that plagues coal coking enterprises
[0005] At present, the desulfurization waste liquid salt extraction technology adopts the fractional crystallization method to extract the mixed salt of ammonium thiosulfate and ammonium thiocyanate and ammonium thiocyanate from the desulfurization waste liquid, which has the following disadvantages: 1, ammonium thiosulfate, ammonium sulfate Mixed salt cannot be sold and becomes a new problem caused by solid waste; 2. The difference in solubility between ammonium thiosulfate and ammonium thiocyanate is small. Due to process problems, ammonium thiosulfate in ammonium thiocyanate products will , Ammonium sulfate content is high, its purity can only reach about 92% to 95%, and the product price is low

Method used

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  • Method for extraction of ammonium thiocyanate and ammonium sulfate from coke-oven gas ammonia process desulfurization waste liquid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Such as figure 1 As shown in the schematic process flow diagram, the method for extracting ammonium thiocyanate and ammonium sulfate from the coke oven gas ammonia desulfurization waste liquid of this embodiment includes the following steps:

[0035] 1. One evaporation

[0036] The desulfurization waste liquid is transported to the primary evaporation kettle for vacuum evaporation and concentration, the temperature is controlled at 50°C, and after concentration to 30%, it is sent to the reaction kettle. The evaporated ammonia gas and water vapor are passed into the condenser through the vacuum to be condensed, and then collected into the condensate tank.

[0037] 2. Reaction

[0038] After evaporation and concentration, the desulfurization liquid is sent to the reactor to test the content of ammonium thiosulfate in the desulfurization liquid. After calculation, the amount of concentrated sulfuric acid (the ratio of the amount of ammonium thiosulfate and sulfuric acid is 1:3), ...

Embodiment 2

[0053] The operation steps of this embodiment and embodiment 1 are basically the same, the difference lies in:

[0054] Step 1: Concentrate at 70°C and concentrate to 10%;

[0055] Step 4: Concentrate at 70°C and concentrate to 75%;

[0056] Step 5: First control the temperature at 65°C, perform crystallization and centrifugal filtration, and then control the temperature at 45°C, perform crystallization and filtration again;

[0057] Step 6: The crystallization temperature is 35°C.

[0058] In this embodiment, the purity of the ammonium sulfate product reaches 98%, of which the ammonium thiosulfate content is 0.42%, the ammonium thiocyanate content is 0.79%, and the ammonium thiocyanate product purity reaches 96%.

Embodiment 3

[0060] The operation steps of this embodiment and embodiment 1 are basically the same, the difference lies in:

[0061] Step 1: Concentrate at 60°C and concentrate to 20%;

[0062] Step 4: Concentrate at 75°C and concentrate to 70%;

[0063] Step 5: First control the temperature at 60°C, perform crystallization and centrifugal filtration, and then control the temperature at 50°C, perform crystallization and filtration again;

[0064] Step 6: The crystallization temperature is 20°C.

[0065] In this embodiment, the purity of the ammonium sulfate product reaches 98%, in which the ammonium thiosulfate content is 0.26%, the ammonium thiocyanate content is 0.84%, and the ammonium thiocyanate product purity reaches 97%.

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Abstract

Belonging to the technical field of environmental protection, the invention discloses a method for extraction of ammonium thiocyanate and ammonium sulfate from coke-oven gas ammonia process desulfurization waste liquid. According to the invention, the salt extraction process consists of the following steps: primary evaporation, reaction, decolorization, secondary evaporation, ammonium sulfate crystallization, secondary filtration, ammonium thiocyanate crystallization and ammonium sulfate recrystallization. The method provided by the invention transforms a three-salt system into a two-salt system efficiently, the obtained ammonium sulfate and ammonium thiocyanate have high purity, good economic benefits can be achieved, the problem of conversion of wastewater into solid waste is thoroughlysolved, the desulfurization waste liquid is thoroughly treated, therefore the method is more suitable for industrial popularization and application.

Description

Technical field [0001] The invention belongs to the technical field of environmental protection, and more specifically, relates to a method for extracting ammonium thiocyanate and ammonium sulfate from a coke oven gas ammonia desulfurization waste liquid. Background technique [0002] The hydrogen sulfide in the coke oven gas is treated by the HPF wet oxidation method, which is a wet liquid phase catalytic oxidation desulfurization and decyanation process using ammonia as an alkali source. During the desulfurization process, the desulfurization liquid continuously generates ammonium thiosulfate, ammonium thiocyanate, ammonium sulfate and other salts. After the salt content in the desulfurization liquid reaches a certain value, the desulfurization efficiency will be significantly reduced. To maintain the desulfurization efficiency, a certain amount of desulfurization liquid must be replaced every day to maintain the balance of the total salt content in the desulfurization liquid. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01C1/245C01C3/20
CPCC01C1/245C01C3/20C01P2006/80
Inventor 李学龙马小军王少华
Owner 扬州康龙环保工程有限公司