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Method for reclaiming sodium rhodanate from sodium rhodanate-containing diatomite

A technology containing sodium thiocyanate and sodium thiocyanate, applied in the direction of thiocyanate, etc., can solve the problems of small processing capacity, high energy consumption, secondary pollution, etc., and achieve high recovery rate, low energy consumption and low water consumption little effect

Inactive Publication Date: 2009-01-21
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The main obstacles to the application of this method in industry are: high energy consumption, small processing capacity, residual methanol in diatomaceous earth causing secondary pollution, and recovery of methanol requires rectification dehydration

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] In this example, 90 L of water was added to 50 kg of diatomaceous earth containing 8% sodium thiocyanate, stirred continuously for 10 minutes in a 250 L stirring vessel, and filtered to obtain a solution with a small amount of suspended matter. Continue to add 90L of water to the filtered solid, stir and filter the combined filtrate to obtain 180L, the content of each component of the filtrate is: sodium thiocyanate 2.16%, impurity iron ion content 27.84ppm, deduct the non-volatile content of sodium thiocyanate 5.10%.

[0017] This sodium thiocyanate solution flows through the activated carbon adsorption column (column volume 8L, built-in activated carbon 3kg) with the speed of 1BV / hr, then rinses the activated carbon adsorption column with 20L water, obtains purified sodium thiocyanate solution 202L after merging, The concentration of sodium thiocyanate is 1.90%. After being converted to 10% sodium thiocyanate content, the impurity iron ion content is 0.53ppm, and the ...

Embodiment 2

[0019] In this example, 50L of water was added to 50kg of diatomaceous earth containing 4% sodium thiocyanate, stirred continuously for 5 minutes in a 200L stirring vessel, and a small amount of suspended matter was obtained after filtering on the first stage of a belt filter. The solution. Spray 50L of water continuously at the second stage of the belt filter, and the obtained filtrate is merged with the first section, and after merging, 95L of filtrate is obtained, and the concentration of sodium thiocyanate is 2.08%. After converting to 10% sodium thiocyanate content, impurities The content of iron ions is 11.99ppm, and the content of non-volatile matter (deducting sodium thiocyanate, the same below) is 3.84%.

[0020] This sodium thiocyanate solution flows through the activated carbon adsorption column (column volume 10L, built-in activated carbon 4kg) with the speed of 3BV / hr, and rinses the activated carbon adsorption column with 10L water, obtains purified sodium thiocy...

Embodiment 3

[0022] In this embodiment, 200L of water is flowed through the column that 50kg of diatomite containing 4% sodium thiocyanate is housed at a speed of 1BV / h, and 180L of leachate is collected, and the contents of each component of the leachate are: thiocyanate Sodium thiocyanate 1.08%, converted to 10% sodium thiocyanate content, impurity iron ion content 37.11ppm, non-volatile matter content 5.57%.

[0023] This sodium thiocyanate solution was mixed and stirred with 2kg gac for 1h, and the gac was removed by filtration to obtain 179L of purified sodium thiocyanate solution, wherein the concentration of sodium thiocyanate was 1.06%, after being converted into 10% sodium thiocyanate content, The impurity iron ion content is 0.57ppm, and the non-volatile matter content is 1.23%. Thus, the total recovery of sodium thiocyanate was 95%.

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Abstract

The invention discloses a method for recovering sodium thiocyanate from diatomaceous earth containing sodium thiocyanate. In the method, the diatomaceous earth containing sodium thiocyanate is mixed with water to form a pulp, and then adopts one or an arbitrary combination of the steps of stirring filtering by a continuous or intermittent stirring vessel, column infiltration, tank leaching and filtering by a belt type filter to separate the obtained pulp, and an aqueous solution of sodium thiocyanate is obtained; the obtained aqueous solution of sodium thiocyanate is subjected to purification by an active carbon fixed bed adsorption method or an active carbon stirring adsorption method, the purified aqueous solution of sodium thiocyanate is a solution with the sodium thiocyanate content of 10 percent, in which the iron ion impurity content is lower than 0.8ppm, and the content of non volatile matters except the sodium thiocyanate is lower than 2.0 percent. and aqueous solution of sodium thiocyanat can be reused in the system, so that the overall recovery of sodium thiocyanate is higher than 95 percent; moreover, the method of the invention is also simple in process and easy in operation.

Description

technical field [0001] The invention relates to a method for recovering sodium thiocyanate from diatomite containing sodium thiocyanate. Background technique [0002] Sodium thiocyanate solution is used as a solvent for the synthesis of polyacrylonitrile and its processing into products, and diatomaceous earth is used as a filter aid, mainly used in the recovery section to remove impurities in the sodium thiocyanate solution. Sodium thiocyanate is contained in the diatomite filter aid residue after use, and if it is disposed of in landfill, it will be a great waste of resources. At present, diatomite containing sodium thiocyanate is almost universally used for deep landfill disposal [Zhang Wei, Research on the treatment and reuse of diatomite filter aid in the production of acrylic fiber, Economic and Technical Cooperation Information, 2005, 2 : 43], however, this disposal method will bring increasing safety and environmental hazards; and the loss of a large amount of sodiu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01C3/20
Inventor 任其龙方兆华苏宝根杨亦文邢华斌苏云
Owner ZHEJIANG UNIV
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