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Method for extracting high-purity sodium thiocyanate and sodium thiosulfate in gas desulfurization waste salt

A technology of sodium thiosulfate and sodium thiocyanate, applied in the directions of thiocyanic acid, thiosulfate/dithionite/polythionite, etc., can solve the problem of high production cost, achieve low production cost, Low energy consumption and controllable average particle size

Inactive Publication Date: 2013-05-01
WUHAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the market demand for high-purity NaSCN is great, but the chemical synthesis of NaSCN requires high-purity HCN, and the production cost is relatively high.

Method used

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  • Method for extracting high-purity sodium thiocyanate and sodium thiosulfate in gas desulfurization waste salt

Examples

Experimental program
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Effect test

Embodiment 1

[0022] A method for extracting high-purity sodium thiocyanate and sodium thiosulfate from gas desulfurization waste salt, the specific steps are:

[0023] Step 1, first prepare desulfurization waste salt, water and crystal mixed salt into a solution, wherein the concentration of sodium thiocyanate is 30-40wt%, and the concentration of sodium thiosulfate is 55-65wt%; Under the conditions of 50°C and 300-500r / min rotation speed, add activated carbon accounting for 3-4wt% of desulfurization waste salt while stirring, keep stirring and decolorize for 0.5-0.7h; then filter at 40-50°C and use 10-30 ℃ of water washing 1 to 2 times, the resulting filtrate I is the primary crystallization mother liquor;

[0024] Step 2: Add sodium thiosulfate seed crystals accounting for 0.5-1.0 wt% of desulfurization waste salt to the primary crystallization mother liquor prepared in step 1 under the conditions of normal pressure, 40-50°C and a rotating speed of 300-500r / min, Insulate and stir the cr...

Embodiment 2

[0029] A method for extracting high-purity sodium thiocyanate and sodium thiosulfate from gas desulfurization waste salt, the specific steps are:

[0030] Step 1, first prepare desulfurization waste salt, water and crystal mixed salt into a solution, wherein the concentration of sodium thiocyanate is 35-45wt%, and the concentration of sodium thiosulfate is 50-60wt%; Under the conditions of 55°C and 300-500r / min rotation speed, add activated carbon accounting for 3.5-4.5wt% of desulfurization waste salt while stirring, keep stirring and decolorize for 0.7-0.9h; then filter at 45-55°C, use 10- Washing with water at 30°C for 1 to 2 times, the resulting filtrate I is the primary crystallization mother liquor;

[0031]Step 2: Add sodium thiosulfate seed crystals accounting for 0.8-1.3 wt% of desulfurization waste salt to the primary crystallization mother liquor prepared in step 1 under normal pressure, 45-55°C and a rotating speed of 300-500r / min, Insulate and stir the crystal fo...

Embodiment 3

[0036] A method for extracting high-purity sodium thiocyanate and sodium thiosulfate from gas desulfurization waste salt, the specific steps are:

[0037] Step 1, first prepare desulfurization waste salt, water and crystal mixed salt into a solution, wherein the concentration of sodium thiocyanate is 40-50wt%, and the concentration of sodium thiosulfate is 45-55wt%; Under the conditions of 60°C and 300-500r / min rotation speed, add activated carbon accounting for 4-5wt% of desulfurization waste salt while stirring, keep stirring and decolorize for 0.8-1.0h; then filter at 50-60°C and use 10-30 ℃ of water washing 1 to 2 times, the resulting filtrate I is the primary crystallization mother liquor;

[0038] Step 2: Add sodium thiosulfate seed crystals accounting for 1.0-1.5 wt% of desulfurization waste salt to the primary crystallization mother liquor prepared in step 1 under the conditions of normal pressure, 50-60°C and a rotating speed of 300-500r / min, Insulate and stir the cr...

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Abstract

The invention relates to a method for extracting high-purity sodium thiocyanate and sodium thiosulfate in coal gas desulfurization waste salt. The technical scheme is that the method comprises the following steps: preparing the desulfurization waste salt as well as water and crystal mixed salt into solution, adding activated carbon to discolor, filtering, adding a sodium thiosulfate crystal seed into a filtrate, reducing the temperature to 25-30 DEG C at a speed of 1-3 DEG C / hour after crystallization and filtering to obtain secondary crystallization mother liquor and a sodium thiosulfate crystal with a purity of more than 95 weight percent; then adding a sodium thiocyanate crystal seed into the secondary crystallization mother liquor, adding a solventing-out agent at a velocity flow of 1-10 mL / min after crystallization and filtering to obtain tertiary crystallization mother liquor and a sodium thiocyanate crystal with a purity of more than 95 weight percent; and then evaporating and crystallizing the tertiary crystallization mother liquor to obtain the crystal mixed salt. The method has the characteristics of simple process, mild operation condition, low production cost, easiness in realizing large-scale production and high quality.

Description

technical field [0001] The invention belongs to the technical field of industrial solid waste treatment and recycling, in particular to a method for extracting high-purity sodium thiocyanate and sodium thiosulfate from gas desulfurization waste salt. Background technique [0002] H in coke oven gas 2 S and HCN are highly corrosive, and can easily cause catalyst poisoning in the synthesis gas reaction; when used as industrial and civil fuels, SO in the exhaust gas 2 and NO x It is a source of environmental pollution that must be strictly controlled. At present, the common desulfurization and decyanation of coke oven gas mostly adopts the wet oxidation desulfurization process: first, the lye is used to absorb the H in the gas 2 S and HCN, and under the catalysis of the oxygen carrier, the absorbed H 2 S is oxidized to elemental sulfur, and then the absorption liquid is recycled. However, in the process of wet oxidative desulfurization and decyanation process, some side re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B17/64C01C3/20
Inventor 张春桃刘帮禹王海蓉姜伟奇
Owner WUHAN UNIV OF SCI & TECH
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