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A process for refining waste salt in chemical industry

A technology of industrial waste salt and process, applied in alkali metal chlorides, chemical instruments and methods, multi-stage treatment of water/sewage, etc., can solve the problems of incomplete incineration, non-reuse, secondary pollution, etc.

Active Publication Date: 2017-03-08
JIANGSU ZHONGDAN GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] High-concentration salt-containing wastewater can be treated by direct incineration with waste liquid incinerator, which has high energy consumption, incomplete incineration, and salt slag contains many impurities and cannot be reused.
It can only be stacked, which will inevitably cause secondary pollution

Method used

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  • A process for refining waste salt in chemical industry

Examples

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Comparison scheme
Effect test

Embodiment 1

[0018] Add ethanol, p-nitrochlorobenzene, and phase transfer catalyst into the reaction kettle, add 50-75% NaOH solution dropwise, and react at 60-65°C. After the reaction is finished, dilute with heated water, so that the salt in the lower layer is dissolved in water and reach the saturated concentration of sodium chloride, then stand still and separate layers. Remove the reaction product in the upper layer and the waste brine in the lower layer, add hydrochloric acid to adjust the pH value, so that the pH value is 1-3, remove tar and azo through activated carbon adsorption, and then remove p-nitrophenol by adsorption on macroporous resin, and remove the p-nitrophenol after adsorption The brine was adjusted to neutral with NaOH. Evaporate and crystallize through MVR, centrifuge to obtain solid salt, and then calcine the solid salt in a rotary kiln at a temperature of 400-750°C for 2-3 hours. The calcined salt is cooled and packaged for sale. The sodium chloride content in th...

Embodiment 2

[0020] Melt the solid o-nitrochlorobenzene into a liquid, put it into the reaction kettle, add ethanol and a phase transfer catalyst, add 75% liquid NaOH dropwise at 55-60 °C, after the reaction is completed, wash it with hot water, and let it stand Layering, adjust the salt-containing mother liquor to PH = 7, remove tar and azo through activated carbon adsorption, evaporate and crystallize the mother liquor through MVR, and centrifuge to obtain solid salt, and then calcinate the solid salt at a temperature of 400-750°C in a rotary kiln for 3 -4 hours, the calcined salt is made into a saturated solution, filtered through a precision filter, evaporated and crystallized by MVR, and centrifuged to obtain solid salt, which is packaged for sale after drying. The sodium chloride content in the salt was 95.5%, and the recovery rate reached 97%.

Embodiment 3

[0022]Add ethanol, p-nitrochlorobenzene, and phase transfer catalyst into the reaction kettle, add 50-75% NaOH solution dropwise, and react at 60-65°C. After the reaction is finished, dilute with heated water, so that the salt in the lower layer is dissolved in water and reach the saturated concentration of sodium chloride, then stand still and separate layers. Remove the reaction product in the upper layer and the waste brine in the lower layer, add hydrochloric acid to adjust the pH value, so that the pH value is 1-3, remove tar and azo through activated carbon adsorption, and then remove p-nitrophenol by adsorption on macroporous resin, and remove the p-nitrophenol after adsorption The brine was adjusted to neutral with NaOH. Evaporated and crystallized by MVR, centrifuged to obtain solid salt, and then calcined the solid salt in a rotary kiln at a temperature of 400-750°C for 2-3 hours, the calcined salt was made into a saturated solution, filtered through a precision filt...

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Abstract

The invention relates to a chemical industrial waste salt refining process which comprises the following steps: pretreating high salt wastewater generated in the production process of aminobenzene ether and p-nitrophenol so as to adjust the pH value, adsorbing by using activated carbon, kieselguhr or macroporous resin, removing organisms and organic salts in the wastewater, reducing the COD of the wastewater, neutralizing the high salt wastewater, performing multi-effect evaporation or mechanical recompression so as to evaporate and crystallize, and centrifuging a solid salt; performing high-temperature calcination on the centrifuged solid salt in a rotary kiln or a tunnel kiln, thereby decomposing and oxidizing the organisms at a high temperature, further thoroughly combusting the tail gas generated through calcination in a heat accumulation type tail gas combustion furnace, preheating and recycling the tail gas, performing spraying absorption, dissolving the calcinated salt with water so as to prepare a saturated solution, filtering by using a precise filter, directly supplying the filtrate to ionic membrane caustic soda for use, or performing multi-effect evaporation or mechanical recompression on the filtered saturated salt water so as to evaporate, crystallize and purify, and performing centrifugation, thereby obtaining high-quality solid sodium chloride.

Description

technical field [0001] The invention belongs to a waste salt refining process, in particular to a chemical industry waste salt refining process. Background technique [0002] In the production of aminophenyl ether by using p-nitrochlorinated benzene and o-nitrochlorinated benzene; in the process of producing p-nitrophenol with p-nitrochlorinated benzene, a large amount of sodium chloride will be generated, resulting in a large amount of high salt, High COD, highly toxic wastewater. High-salt wastewater must be treated with effective treatment measures. Otherwise, serious environmental pollution will be caused. When the salt content in wastewater reaches 2%, it is difficult for bacteria to survive during biochemical treatment. Generally, the salt content in wastewater is controlled below 1.5%, and the control method is to dilute with water. With the higher and higher requirements for environmental protection, at present, water dilution is not allowed, and the method of eva...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/10C01D3/06
Inventor 顾杰李留德吴德生毛永生
Owner JIANGSU ZHONGDAN GROUP
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