CN-122012916-A - Method for separating and recovering iron, aluminum and titanium from red mud based on multistage vertical electrophoresis acid-base regeneration technology

CN122012916ACN 122012916 ACN122012916 ACN 122012916ACN-122012916-A

Abstract

The invention discloses a method for separating and recovering iron, aluminum and titanium in red mud based on multistage vertical electrophoresis acid-base regeneration. The method couples red mud recycling and a flue gas desulfurization process, and realizes online controllable regeneration of acid-base reagents and gradient selective extraction of elements. The key of the method is that the acid liquor and alkali liquor regeneration and gradient leaching-selective precipitation of the multistage vertical electrophoresis separation unit are combined, so that the recycling of sulfuric acid/alkali is realized, the consumption of additional reagents is reduced, the high-selectivity recovery of aluminum, iron and titanium is realized, the process closed loop degree is high, the concept of treating waste by waste is outstanding, and the method has obvious recycling and environment treatment synergistic benefits. The method is suitable for large-scale treatment of red mud and co-production of flue gas desulfurization, and has good engineering popularization value.

Inventors

ZHOU JITI
LI LEI
TIAN TIAN
JIN RUOFEI

Assignees

大连理工大学

Dates

Publication Date: 20260512
Application Date: 20260304

Claims (4)

1. A method for separating and recovering iron, aluminum and titanium from red mud based on a multistage vertical electrophoresis acid-base regeneration technology is characterized by comprising the following steps of (1) preparing red mud into slurry, carrying out wet desulphurization reaction with sulfur-containing industrial flue gas to fix sulfur dioxide in the flue gas, carrying out solid-liquid separation after the wet desulphurization reaction to respectively obtain a sodium sulfate-based desulfurization solution and desulfurization tailings rich in iron, aluminum and titanium, (2) carrying out acid-base regeneration, namely continuously introducing the desulfurization solution obtained in the step (1) into a first-stage vertical electrophoresis separation unit of a multistage vertical electrophoresis system, wherein the first-stage vertical electrophoresis separation unit is used for primarily separating the desulfurization solution mainly comprising sodium sulfate into regenerated acid solution and regenerated alkali solution; (3) Step-by-step acid leaching, namely leaching the desulfurization tailings obtained in the step (1) under the normal temperature condition by using the regenerated acid liquor with the concentration of 1-1.5 mol/L obtained in the step (2) to selectively extract aluminum so as to obtain an aluminum-rich leaching solution; leaching the leached residual solid by adopting regenerated sulfuric acid with the concentration of not less than 4 mol/L at the temperature of 100-120 ℃ to obtain leaching solution rich in iron and titanium, (4) step-by-step precipitation, namely, a) adding regenerated alkaline liquor into the aluminum-rich leaching solution to adjust the pH to 4-4.5, continuously adjusting the pH to 5-6 after impurities are removed by precipitation to obtain aluminum hydroxide, b) adding EDTA with the same molar quantity with iron into the leaching solution rich in iron and titanium, adjusting the pH to 1.5-2, reacting for 2 hours at the temperature of 80-100 ℃, precipitating to obtain meta-titanic acid, then adjusting the pH to 3-3.5 at normal temperature, continuously adjusting the pH to be more than or equal to 12, precipitating to obtain ferric hydroxide, (5) material reflux, wherein the regenerated sulfuric acid obtained in the step (2) is respectively recycled to step-by-step acid leaching in the step-by-step pH precipitation in the step (3), the mother liquor which takes sodium sulfate as a main component after aluminum precipitation is refluxed to a vertical separation unit of a multistage vertical electrophoresis system as a first-stage separation unit, and is used as a solution, the recycled sodium sulfate, and the residual sodium chloride is recycled in the step-by-step precipitation system along with the precipitation of the precipitation system of the sodium chloride and the subsequent precipitation of the recycled alkaline solution (the recycled sodium chloride and the residual solution is used in the step-enriched solution is recycled by the step of the step 4), the solution is dissolved or prepared and then flows back to the multistage vertical electrophoresis separation unit for regeneration, thus forming a closed cycle process of desulfurizing liquid/sodium sulfate solution-multistage vertical electrophoresis regenerated acid-alkali-regenerated acid for leaching-regenerated alkali for precipitation-mother liquor backflow regeneration, and (6) the product calcination is carried out, namely the aluminum hydroxide, ferric hydroxide and metatitanic acid precipitate obtained in the step (4) are respectively calcined, thus obtaining aluminum oxide, ferric oxide and titanium oxide products.
2. The method for separating and recovering iron, aluminum and titanium from red mud based on the multistage vertical electrophoresis acid-base regeneration technology according to claim 1, wherein the specific implementation process of the acid-base regeneration in the step (2) is as follows: Continuously introducing the desulfurization solution obtained in the step (1) into a one-stage vertical electrophoresis separation unit of a multi-stage vertical electrophoresis system, and under the action of an external electric field perpendicular to the liquid flow direction, enabling sodium ions in the desulfurization solution to migrate towards the cathode and be enriched at the cathode side, and enabling sulfate ions to migrate towards the anode and be enriched at the anode side; simultaneously combining hydroxide ions and hydrogen ions generated by electrode reaction to form sodium hydroxide solution on the cathode side and sulfuric acid solution on the anode side respectively, so as to realize in-situ conversion of salt in desulfurization solution and synchronous regeneration of acid solution and alkali solution, enabling regenerated alkali solution obtained by the first-stage vertical electrophoresis separation unit to enter the next-stage vertical electrophoresis separation unit of an alkali branch, enabling regenerated acid solution obtained by the first-stage vertical electrophoresis separation unit to enter the next-stage vertical electrophoresis separation unit of an acid branch, enabling the subsequent vertical electrophoresis separation units to operate in cascade in the same mode, enabling the regenerated alkali solution to be concentrated step by step along the alkali branch, enabling the regenerated acid solution to be concentrated step by step along the acid branch, enabling a cathode-side product flow of the first-stage vertical electrophoresis separation unit to flow back to the liquid inlet end of the first-stage vertical electrophoresis separation unit when the concentration of the acid solution produced by one-stage vertical electrophoresis separation unit of the acid branch does not reach a set value, enabling the anode-side product flow back to enter the first-stage vertical electrophoresis separation unit of the acid branch to be separated after being mixed with the feed from the last-stage vertical electrophoresis separation unit of the acid branch, enabling the anode-side product flow to enter the next-stage vertical electrophoresis separation unit to be concentrated continuously, and (3) mixing the mixed solution with the feed from the upper-stage vertical electrophoresis separation unit of the alkali branch, then re-entering the present-stage vertical electrophoresis separation unit for separation, and sending the product flow on the cathode side into the lower-stage vertical electrophoresis separation unit of the alkali branch for concentration until regenerated acid liquor and regenerated alkali liquor meeting the concentration required by the subsequent step acid leaching and step precipitation processes are obtained.
3. The method for separating and recovering iron, aluminum and titanium from red mud based on the multistage vertical electrophoresis acid-base regeneration technology according to claim 1, wherein the multistage vertical electrophoresis system is formed by cascading more than two vertical electrophoresis separation units, wherein each stage of vertical electrophoresis separation unit comprises a power supply part, a vertical electrophoresis separation chamber, a sample input part, a sample collection part and a gas collection part.
4. The method for separating and recovering iron, aluminum and titanium from red mud based on the multistage vertical electrophoresis acid-base regeneration technology according to claim 1, which is characterized in that, The power supply part comprises a stabilized DC power supply, the anode and the cathode of which are respectively connected with the anode plate and the cathode plate, and the stabilized DC power supply is used for providing a stabilized electric field perpendicular to the flowing direction of the liquid for the vertical electrophoresis separation chamber; The vertical electrophoresis separation chamber is of a rectangular cavity structure, two evenly distributed water outlets are arranged at the bottom of the vertical electrophoresis separation chamber, a sample inlet is arranged at the top of the vertical electrophoresis separation chamber, and gas collection ports are respectively arranged at positions close to the anode and the cathode; Quartz sand with the grain diameter of 0.01-3 mm is filled in the vertical electrophoresis separation chamber as a supporting medium; The vertical electrophoresis separation chamber is provided with a cooling medium circulation device, a cooling medium circulation device and a cooling medium circulation device, wherein the cooling medium circulation device is used for cooling the cooling medium, and the cooling medium circulation device is used for cooling the cooling medium; The sample input part comprises a sample solution storage container and a single-channel peristaltic pump, and the sample solution is conveyed to a sample inlet at the top of the vertical electrophoresis separation chamber through the single-channel peristaltic pump; The sample collecting part comprises a water outlet collecting container and a multichannel peristaltic pump, the solutions at the water outlets are respectively collected at the same flow rate through the multichannel peristaltic pump, and the total water outlet flow of each water outlet is equal to the sample feeding flow so as to maintain the stable liquid level in the separation chamber; The gas collecting part comprises a gas collecting bag and a gas transmission pipe, the gas transmission pipe is respectively connected with the gas collecting port 7 and the gas collecting bag, and the liquid level of the separation chamber is lower than the position of the gas transmission pipe in the operation process.

Description

Method for separating and recovering iron, aluminum and titanium from red mud based on multistage vertical electrophoresis acid-base regeneration technology Technical Field The invention belongs to the technical field of separation and purification in recycling of solid wastes, and relates to a method for separating and recovering iron, aluminum and titanium from red mud based on a multistage vertical electrophoresis acid-base regeneration technology. Background Red mud is a solid waste which is high in alkalinity and rich in various metal elements and is generated in the production process of alumina. With the surge of global aluminum alloy demand, the annual red mud production has reached about 1.8 hundred million tons, with accumulated stockpiles exceeding 40 hundred million tons. However, the recycling rate of the red mud is less than 4%, most of the red mud is still treated in an open-air stacking or landfill mode, and the long-term and serious pollution threat to soil, water and ecological environment is formed. Although red mud is regarded as waste, the contained abundant metal resources (the valuable metals such as iron, aluminum, titanium and the like account for 40% -80% of the total amount) make the red mud an important associated mineral source. Is expected to relieve the pressure of increasingly exhausted natural ore resources. Aiming at the occurrence form, the acid leaching method is an effective way for extracting the metals, has the characteristics of simple process and high recovery rate, and can realize high added value recovery of the metals and reduce environmental risks. However, the method still faces a core bottleneck in industrial scale application, namely, the consumption of inorganic acid is huge, so that the cost is high, secondary pollution is generated, and the recycling benefit of the red mud is obviously restricted. In order to break through the bottleneck of acid-base consumption and realize recycling, the vertical electrophoresis technology has revolutionary potential. The technology follows the green chemistry principle, forms a porous network structure by filling a fine supporting medium in a separation channel, effectively inhibits ion diffusion, and realizes high-efficiency separation by taking electromigration as a core driving force. Under the action of an external electric field, anions and cations in the solution reversely migrate and are respectively enriched near the electrodes, so that the in-situ one-step regeneration of acid and alkali is realized, and a green and efficient acid-base circulating system is constructed. Compared with the traditional membrane separation technology (such as membrane electrodialysis and bipolar membrane electrodialysis), the vertical electrophoresis does not need an ion exchange membrane, so that the problems of membrane pollution, scaling, concentration polarization and other long-term puzzled industries are fundamentally avoided, the operation and maintenance cost is greatly reduced, and the method is particularly suitable for a high-salt system and has excellent stability and economy. The technology has excellent process compatibility and can be coupled with the flue gas desulfurization and acid leaching metal process. The acid can be efficiently regenerated by introducing the desulfurization waste liquid into a vertical electrophoresis system, and the regenerated acid is recycled for leaching the desulfurization slag or the metal-containing solid, so that an acid-base self-circulation path is built in the system. The innovative coupling mode can not only remarkably reduce the acid-base consumption in the red mud recycling process, but also provide a new technical approach for the efficient separation and recovery of multiple metals. Disclosure of Invention The invention provides a method for separating and recovering iron, aluminum and titanium from red mud based on a multistage vertical electrophoresis acid-base regeneration technology. The method combines wet desulfurization of red mud with acid-base regeneration-stepwise acid leaching-base extraction processes, drives directional electromigration of sodium ions and sulfate ions in sodium sulfate solution through multistage vertical electrophoresis, realizes regeneration of sulfuric acid and sodium hydroxide, and forms a self-maintained acid-base supply system by means of material circulation in a system, thereby remarkably reducing consumption of external acid-base reagents. By adjusting the working voltage and the operation level of the vertical electrophoresis system, the concentration of regenerated acid and alkali can be flexibly controlled, different acidity requirements of the valuable metals in the red mud for step leaching are met, and conditions are created for obtaining high-purity single metal products through pH regulation and precipitation in the follow-up process. In the whole, the method constructs a technical path of treating waste with waste and changing wast