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Electrochemistry-based alkaline waste residue dealkalization method

An electrochemical and alkaline technology, applied in the electrolysis process, electrolysis components, solid waste removal, etc., can solve the problems of difficult recovery of sodium and alkali, failure to meet the requirements of alkali content of red mud raw materials for building materials, high energy consumption, etc., and achieve technological Effects in simple steps

Active Publication Date: 2020-05-29
CENT SOUTH UNIV
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  • Application Information

AI Technical Summary

Problems solved by technology

Unable to meet the alkali content requirements of building materials for red mud raw materials
[0007] The patent (CN201910290643.7) discloses a method for direct cementation of high-iron red mud vortex melting reduction for dealkalization and iron extraction. The dehydrated raw material is mixed with a solid carbonaceous reducing agent and a slagging agent to make a mixture, which is directly injected into the The vortex center of the vortex stirring high-temperature furnace, the mixture is drawn into the molten pool, and the vortex stirring reduction is carried out at 1300-1600 ° C for 10-60 minutes. Although the dealkalization effect is good, it is difficult to recover the sodium-alkali produced in the flue gas. And the process consumes a lot of energy

Method used

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  • Electrochemistry-based alkaline waste residue dealkalization method

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Experimental program
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Effect test

Embodiment 1

[0039] The raw material is Bayer process red mud from an alumina plant in Shanxi, the main content of each component is Na 2 O 8.44%, SiO 2 16.97%, Al 2 O 3 24.15%, CaO 6.32%, Fe 2 O 3 16.97%.

[0040] Mix 1kg of red mud, 5kg of water and 0.6kg of CaO evenly, leaching at 70°C and 200r / min stirring speed for 2h, and then place it in the anode chamber of the electrolytic cell (such as figure 1 ), electrolyzed in the red mud leaching solution at 50 °C, and controlled the initial current density to 500 mA / cm 2 , the electrolysis time is 2h. The red mud in the anode chamber after the reaction is taken out and filtered to complete the separation of the slag phase and the liquid phase, and the slag phase Na after dealkalization 2 The O content was 0.6%, and the pH of the treated alkaline waste was 8.1.

Embodiment 2

[0042] The raw material is Bayer process red mud from an alumina plant in Shanxi, the main content of each component is Na 2 O 8.44%, SiO 2 16.97%, Al 2 O 3 24.15%, CaO 6.32%, Fe 2 O 3 16.97%.

[0043] Mix 1kg of red mud and 5kg of water evenly, leaching for 0.5h in a homogeneous reactor at 90°C, and then place it in the anode chamber of the electrolytic cell (such as figure 1 ), electrolyzed in the red mud leaching solution at 70 °C, and controlled the initial current density to 300 mA / cm 2 , the electrolysis time is 2h. The red mud in the anode chamber after the reaction is taken out and filtered to complete the separation of the slag phase and the liquid phase, and the slag phase Na after dealkalization 2 The O content was 1.5%, and the pH of the treated alkaline waste was 8.5.

Embodiment 3

[0045] The raw material is Bayer process red mud from an alumina plant in Henan, the main content of each component is Na 2 O 6.0%, SiO 2 21.30%, Al 2 O 3 22.20%, CaO 11.43%, Fe 2 O 3 13.97%.

[0046] 1kg red mud, 5kg water and 0.6kg CaCl 2 Mix evenly, leaching for 2 hours at 70°C and 200r / min stirring speed, and then place it in the anode chamber of the electrolytic cell (such as figure 1 ), electrolyzed in the red mud leaching solution at 50 °C, and controlled the initial current density to 800 mA / cm 2 , the electrolysis time is 1.5h. The red mud in the anode chamber after the reaction is taken out and filtered to complete the separation of the slag phase and the liquid phase, and the slag phase Na after dealkalization 2 The O content was 0.5%, and the pH of the treated alkaline waste was 7.9.

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Abstract

The invention discloses an electrochemistry-based alkaline waste residue dealkalization method. The method comprises the following steps: carrying out uniform mixing and leaching treatment on an alkaline waste residue raw material and water to obtain a leached slurry, and putting and electrolyzing the leached slurry into an electrolytic cell. The content of Na2O in the alkaline waste residue treated by the method is less than or equal to 1.5%, and the pH value of the dealkalized waste residue is less than or equal to 8.5. The method is simple in step, no new waste is generated in the whole process, electric energy is clean and easy to transmit, the dealkalized alkaline waste residue can be directly used for producing building materials or realizing on-site soil treatment, and the utilization rate of the alkaline waste residue reaches 100%.

Description

technical field [0001] The invention relates to a method for dealkalization of alkaline waste residue, in particular to a method for realizing red mud or other alkali leaching waste residue dealkalization by an electrochemical method, and belongs to the technical field of comprehensive utilization of metallurgical solid waste. Background technique [0002] Red mud is a strong alkaline solid waste produced after the production of alumina or aluminum hydroxide from bauxite. According to different raw materials and production processes, about 1-2.5t of red mud is produced for every 1t of alumina produced. At present, the global red mud reserves are estimated to have exceeded 3.6 billion tons, and it is increasing at a rate of more than 120 million tons every year. The average utilization rate of red mud in the world is 15%. The cumulative stockpile of red mud in China has grown to 600 million tons, and the utilization rate of red mud is only 4%. Most of the red mud is still d...

Claims

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Application Information

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IPC IPC(8): C25B1/16C25B9/08B09B3/00C25B9/19
CPCC25B1/16B09B3/00C25B9/19
Inventor 王艳秀孙伟岳彤王丽韩海生
Owner CENT SOUTH UNIV
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