Harmless disposal method of waste diatomite containing sodium thiocyanate

A technology containing sodium thiocyanate and waste diatomite, applied in chemical instruments and methods, inorganic chemistry, silicon compounds, etc., can solve the problems of long process, large pressure drop, difficult to achieve harmlessness, etc. The effect of saving operation cost, simple process and less water consumption

Inactive Publication Date: 2009-03-11
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

According to our research results, this water washing method is not reasonable enough, because the diatomite particle distribution is very wide and the particles are relatively fine, channeling and dead ends will occur during the scale-up production, the diatomite disposal is not complete, and the local sodium thiocyanate residue is serious, and Large pressure drop, difficult for practical application
[0009] Other washing methods th

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Take 5kg of waste diatomaceous earth containing 8% sodium thiocyanate, add 2.5L of water according to the solid-liquid ratio of 1:0.5, stir in a 10L kettle for 5min, the total amount is 7.5kg, and transfer to a belt with a mesh diameter of 2μm On the filter cloth, the conveying speed of the filter cloth is 1m / min, and the vacuum degree of 0.04MPa is kept underneath. The filter is divided into 3 stages, the latter two stages are sprayed with water, and the spray water is 5L, the filtrate is collected in 3 stages, and the last stage is 2L. Separately collect and return to the kettle to stir the raw materials, and the waste diatomaceous earth is discharged at the end of the filter cloth conveying. The sodium thiocyanate content in the treated waste diatomaceous earth is 0.07%, which achieves harmless treatment and can be returned to the system as a filter aid Repeated use or used as building materials, roadbeds and other materials.

Embodiment 2

[0024] Take 100 kg of waste diatomaceous earth containing 4% sodium thiocyanate, add 200L of water according to the solid-liquid ratio of 1:2, mix in a 500L kettle for 10 minutes, transfer to a belt filter cloth with a mesh pore size of 8μm, and transmit the filter cloth The speed is 0.2m / min. The filtrate is continuously separated by maintaining a vacuum of 0.03MPa below, and the top of the filter cloth is continuously sprayed and washed with water. The spray water is 100L. The filtrate is collected in 4 stages. The last stage of filtrate 40L is returned to the mixing kettle and mixed with the next batch of raw materials. , The waste diatomaceous earth is discharged at the end of the filter cloth conveying. The sodium thiocyanate content in the waste diatomaceous earth after the above treatment is 0.01%, which can be reused in the system.

Embodiment 3

[0026] Take 100kg of waste diatomaceous earth containing 4% sodium thiocyanate, add 100L of water according to the solid-liquid ratio of 1:1, mix in a 500L kettle for 10min, transfer to a belt filter cloth with a mesh pore size of 12μm, and transmit the filter cloth The speed is 0.4m / min. The filtrate is continuously separated by maintaining a vacuum of 0.06MPa below, and the top of the filter cloth is continuously sprayed and washed with water. The spray water is 100L. The filtrate is collected in 3 stages. The last stage of filtrate 40L is returned to the mixing kettle and mixed with the next batch of raw materials. , The waste diatomite is discharged at the end of the filter cloth conveying. The sodium thiocyanate content in the waste diatomite after the above treatment is 0.04%, which can be recycled to the system for reuse.

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PUM

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Abstract

The invention discloses a method for harmless treatment of waste diatomite containing sodium thiocyanate. The method comprises the following steps: mixing a raw material of waste diatomite with water to produce slurry with stirring; spreading the slurry on a filter belt fabric for continuous conveying and at the same time spraying water on the slurry to wash the slurry; keeping the space below the filter belt fabric vacuum and collecting the filtrate sectionally. The amount of water used for treatment is no more than four times of that of the diatomite. The content of sodium thiocyanate in the treated waste diatomite is less than 0.1 percent, and the treated waste diatomite can be reused in the system as a filter aid or used as a building material, a road bed material and so on. Compared with the prior process such as a methanol method, the method of the invention has the advantages of avoiding secondary pollution, and saving investment, transportation cost and water, along with simple and easy-to-implement process, a content of residual sodium thiocyanate less than 0.1 percent, low energy consumption, and suitability to mass production.

Description

Technical field [0001] The invention relates to a harmless disposal method of waste diatomite containing sodium thiocyanate. Background technique [0002] Sodium thiocyanate is a colorless deliquescent crystal or white powder, which is toxic. When diatomaceous earth is used as an adsorbent and filter aid to treat a solution containing sodium thiocyanate, the waste diatomaceous earth after use contains different concentrations of sodium thiocyanate [Ning Qiushi, Wan Zhiming, Li Zhongmo, sodium thiocyanate Research on the comprehensive management of environmental protection in the production process. Gansu Chemical Industry, 2004, 2:41-43]. In the past, because the waste diatomite could not be treated economically and simply, it was only possible to purchase land, build a cement yard, and store it in the open air. The storage yard is exposed to wind and rain, and the dissolved sodium thiocyanate infiltrates into the water body, posing a threat to nearby water sources and ecosystems...

Claims

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Application Information

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IPC IPC(8): C01B33/20C04B14/08
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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