Combined process for comprehensive utilization of red mud

Abstract

The invention relates to the technical field of magnetic separation of red mud, and discloses a comprehensive utilization combined process of red mud, which specifically comprises the following steps: 1, a gravity and magnetic separation stage: firstly, extracting iron ore concentrate containing 50% of iron TFe and iron middling containing 45% of iron TFe, increasing the content of Al2O3 in residual about 60% red mud to 25%, and reducing the content of iron to 30%-32%; 2, a high-temperature dissolution stage: carrying out high-temperature dissolution, and increasing the iron content of a slag phase to 40-42% of TFe while utilizing the aluminum oxide; by means of the optimized technological process, efficient recycling of various valuable elements in the red mud is achieved, the comprehensive utilization rate, the recycling level and the comprehensive emission reduction rate of the red mud are remarkably increased, efficient separation and enrichment of aluminum oxide and iron minerals in the red mud are achieved, the purity and the recovery rate of products are increased, and the method is suitable for industrial production. The method not only solves the problem of environmental pollution caused by red mud treatment, but also realizes efficient recovery of valuable elements in the red mud, and has remarkable economic, social and environmental benefits.

Description

Technical Field

[0001] The invention relates to the technical field of red mud magnetic separation, and in particular to a combined process for comprehensive utilization of red mud. Background Art

[0002] Red mud is the polluting waste residue discharged when the aluminum industry extracts alumina. Generally, for every ton of alumina produced, 1.0 to 2.0 tons of red mud are produced. As the world's fourth largest alumina producer, China discharges millions of tons of red mud every year. When red mud passes through the magnetic field of the magnetic separator during magnetic separation, it is simultaneously subjected to the combined action of magnetic force and mechanical force (gravity, centrifugal force, medium resistance, friction, etc.). The magnetic force on the mineral particles with strong magnetism is greater than the mechanical force they are subjected to, while the magnetic force on the non-magnetic mineral particles is very small, so the mechanical force prevails. Since the combined force of the magnetic force and mechanical force acting on various mineral particles is different, their movement trajectories are also different, thereby achieving the final separation of minerals. In order to successfully separate the magnetic mineral particles, the necessary condition is that the magnetic force on the magnetic mineral particles must be greater than the combined force of the mechanical force in the opposite direction.

[0003] The existing magnetic separation or magnetic recombination process technology utilizes the iron minerals contained in red mud, but it is difficult to achieve multi-element recycling of red mud solid waste resources. The utilization rate is low, and the general emission reduction rate is between 10% and 25%. The comprehensive emission reduction rate is low. The current red mud solid waste development and utilization path is not coordinated with the development of the alumina industry. The contradiction between the stock not decreasing and the incremental increase is more prominent, which seriously restricts and affects the development of the alumina industry chain.

[0004] To this end, we propose a combined process for comprehensive utilization of red mud. Summary of the invention

[0005] The present invention mainly solves the technical problems existing in the above-mentioned prior art and provides a combined process for comprehensive utilization of red mud.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme, a combined process for comprehensive utilization of red mud, which specifically comprises the following steps:

[0007] Step 1: Gravity and magnetic stage: first extract iron concentrate containing 50% TFe (yield of about 35%) and iron ore containing 45% TFe (yield of about 5%-7%), and the remaining 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%;

[0008] Step 2: High temperature dissolution stage: Entering high temperature dissolution, while realizing the utilization of alumina, the iron content of slag phase is increased to TFe40%-42%;

[0009] Step 3: Chemical beneficiation stage: After chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate is more than 80%, obtaining dissolution solution, high-grade iron ore concentrate and tailings;

[0010] Step 4: Alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition method;

[0011] Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking;

[0012] Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The resulting tailings can be used as building materials or as fillers.

[0013] Preferably, the gravity magnetic stage in the first step adopts wet high-intensity magnetic separation technology, and the magnetic iron minerals in the red mud are effectively separated by adjusting the magnetic field intensity and the mineral processing concentration.

[0014] Preferably, the dissolution agent used in the high-temperature dissolution stage in the second step is NaOH solution, the dissolution temperature is controlled between 180-220°C, and the dissolution time is 1-3 hours to ensure efficient dissolution of alumina and enrichment of iron.

[0015] Preferably, the chemical dissociator used in the chemical mineral processing stage in the third step is sulfuric acid or hydrochloric acid, and further enrichment of iron minerals can be achieved by adjusting the concentration and reaction time of the dissociator.

[0016] Preferably, the carbonization method used in the alumina extraction stage in the fourth step is to add an appropriate amount of sodium carbonate solution to the dissolution solution, and to achieve the precipitation of high-purity alumina by controlling the temperature and time of the carbonization reaction.

[0017] Preferably, the reduction roasting temperature used in the iron recovery stage in the fifth step is 800-1000° C. and the roasting time is 1-2 hours to ensure the reduction effect and magnetic separation efficiency of the iron concentrate.

[0018] Preferably, the water washing method adopted in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure sufficient removal of alkaline substances and improve the environmental performance of the tailings.

[0019] The present invention provides a combined process for comprehensive utilization of red mud, which has the following beneficial effects:

[0020] 1. This combined process for comprehensive utilization of red mud realizes the efficient recovery and utilization of multiple valuable elements in red mud through optimized process flow, significantly improves the comprehensive utilization rate, resource level and comprehensive emission reduction rate of red mud, realizes the efficient separation and enrichment of alumina and iron minerals in red mud, improves the purity and recovery rate of products, and not only solves the environmental pollution problem of red mud treatment, but also realizes the efficient recovery of valuable elements in red mud, with significant economic, social and environmental benefits.

[0021] 2. This combined process for comprehensive utilization of red mud, while realizing the resource utilization of red mud, effectively reduces environmental pollution and the negative impact of red mud stacking on the environment, and has good environmental benefits.

[0022] 3. This combined process for comprehensive utilization of red mud ensures the environmental performance of tailings through technical means such as multi-stage countercurrent washing, so that the tailings can be used as building materials or fillers, thus realizing the utilization of all components of red mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] Embodiment 1: A combined process for comprehensive utilization of red mud, such as Figure 1 As shown, it specifically includes the following steps: the first step: gravity magnetic stage: first extract iron concentrate containing 50% TFe (yield of about 35%) and iron ore containing 45% TFe (yield of about 5%-7%), and the remaining about 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%; the second step: high temperature dissolution stage: enter the high temperature dissolution, realize the utilization of alumina, and the iron content of the slag phase is increased to TFe40%-42%; the third step: chemical ore dressing stage: after chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate reaches more than 80%, and the dissolution solution, high-grade iron ore and tailings are obtained; the fourth step: alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition;

[0025] Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking;

[0026] Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The tailings obtained can be used as building materials or as fillers. In the first step, the heavy magnetic stage adopts wet strong magnetic separation technology. By adjusting the magnetic field strength and the beneficiation concentration, the magnetic iron minerals in the red mud can be effectively separated. In the second step, the high-temperature dissolution stage adopts the dissolution agent NaOH solution, the dissolution temperature is controlled between 180°C, and the dissolution time is 3 hours to ensure the efficient dissolution of alumina and the enrichment of iron. In the third step, the chemical dissociation agent used in the chemical beneficiation stage is sulfuric acid. By adjusting the concentration of the dissociation agent and the reaction time, the further enrichment of iron minerals can be achieved. In the fourth step, the carbonization method used in the alumina extraction stage is to add an appropriate amount of sodium carbonate solution to the dissolution solution. The temperature and time of the carbonization reaction are controlled to achieve the precipitation of high-purity alumina. The reduction roasting temperature used in the iron recovery stage in the fifth step is 800°C and the roasting time is 2 hours to ensure the reduction effect of the iron concentrate and the magnetic separation efficiency. The water washing method used in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure the full removal of alkaline substances and improve the environmental performance of the tailings. Through the optimized process flow, the efficient recovery and utilization of various valuable elements in red mud are achieved, which significantly improves the comprehensive utilization rate, resource level and comprehensive emission reduction rate of red mud, realizes the efficient separation and enrichment of alumina and iron minerals in red mud, and improves the purity and recovery rate of the product. It not only solves the environmental pollution problem of red mud treatment, but also realizes the efficient recovery of valuable elements in red mud, which has significant economic, social and environmental benefits.

[0027] Embodiment 2: A combined process for comprehensive utilization of red mud, such as Figure 1 As shown, it specifically includes the following steps: the first step: gravity magnetic stage: first extract iron concentrate containing 50% TFe (yield of about 35%) and iron ore containing 45% TFe (yield of about 5%-7%), and the remaining about 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%; the second step: high temperature dissolution stage: enter the high temperature dissolution, realize the utilization of alumina, and the iron content of the slag phase is increased to TFe40%-42%; the third step: chemical ore dressing stage: after chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate reaches more than 80%, and the dissolution solution, high-grade iron ore and tailings are obtained; the fourth step: alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition;

[0028] Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking;

[0029] Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The tailings obtained can be used as building materials or as fillers. In the first step, the heavy magnetic stage adopts wet strong magnetic separation technology. By adjusting the magnetic field strength and beneficiation concentration, the magnetic iron minerals in the red mud are effectively separated. In the second step, the high temperature dissolution stage adopts NaOH solution as the dissolution agent, the dissolution temperature is controlled between 190℃, and the dissolution time is 2.5 hours to ensure the efficient dissolution of alumina and the enrichment of iron. In the third step, the chemical dissociation agent used in the chemical beneficiation stage is hydrochloric acid. By adjusting the concentration of the dissociation agent and the reaction time, the In order to further enrich the iron minerals, the carbonization method used in the alumina extraction stage in the fourth step is to add an appropriate amount of sodium carbonate solution to the dissolution solution, and to achieve the precipitation of high-purity alumina by controlling the temperature and time of the carbonization reaction. The reduction roasting temperature used in the iron recovery stage in the fifth step is 850°C, and the roasting time is 1.5 hours to ensure the reduction effect and magnetic separation efficiency of the iron concentrate. The water washing method used in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure the full removal of alkaline substances and improve the environmental protection performance of the tailings. While realizing the resource utilization of red mud, it effectively reduces environmental pollution and reduces the negative impact of red mud stacking on the environment, with good environmental benefits.

[0030] Embodiment 3: A combined process for comprehensive utilization of red mud, such as Figure 1 As shown, it specifically includes the following steps: the first step: gravity magnetic stage: first extract iron concentrate containing 50% TFe (yield of about 35%) and iron ore containing 45% TFe (yield of about 5%-7%), and the remaining about 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%; the second step: high temperature dissolution stage: enter the high temperature dissolution, realize the utilization of alumina, and the iron content of the slag phase is increased to TFe40%-42%; the third step: chemical ore dressing stage: after chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate reaches more than 80%, and the dissolution solution, high-grade iron ore and tailings are obtained; the fourth step: alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition;

[0031] Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking;

[0032] Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The tailings obtained can be used as building materials or as fillers. In the first step, the heavy magnetic stage adopts wet strong magnetic separation technology. By adjusting the magnetic field strength and beneficiation concentration, the magnetic iron minerals in the red mud can be effectively separated. In the second step, the high temperature dissolution stage adopts NaOH solution as the dissolution agent, the dissolution temperature is controlled between 200℃, and the dissolution time is 2 hours to ensure the efficient dissolution of alumina and the enrichment of iron. In the third step, the chemical dissociation agent used in the chemical beneficiation stage is sulfuric acid. By adjusting the concentration of the dissociation agent and the reaction time, the iron minerals can be separated. In the fourth step, the carbonization method used in the alumina extraction stage is to add an appropriate amount of sodium carbonate solution to the dissolution solution, and the precipitation of high-purity alumina is achieved by controlling the temperature and time of the carbonization reaction. The reduction roasting temperature used in the iron recovery stage in the fifth step is 900°C, and the roasting time is 1.5 hours to ensure the reduction effect and magnetic separation efficiency of the iron concentrate. The water washing method used in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure the full removal of alkaline substances and improve the environmental protection performance of the tailings. The environmental protection performance of the tailings is ensured through technical means such as multi-stage countercurrent washing, so that the tailings can be used as building materials or fillers, realizing the full component utilization of red mud.

[0033] Embodiment 4: A combined process for comprehensive utilization of red mud, such as Figure 1 As shown, it specifically includes the following steps: the first step: gravity magnetic stage: first extract iron concentrate containing 50% TFe (yield of about 35%) and iron ore containing 45% TFe (yield of about 5%-7%), and the remaining about 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%; the second step: high temperature dissolution stage: enter the high temperature dissolution, realize the utilization of alumina, and the iron content of the slag phase is increased to TFe40%-42%; the third step: chemical ore dressing stage: after chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate reaches more than 80%, and the dissolution solution, high-grade iron ore and tailings are obtained; the fourth step: alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition;

[0034] Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking;

[0035] Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The tailings obtained can be used as building materials or as fillers. In the first step, the heavy magnetic stage adopts wet strong magnetic separation technology. By adjusting the magnetic field strength and beneficiation concentration, the magnetic iron minerals in the red mud can be effectively separated. In the second step, the high temperature dissolution stage adopts NaOH solution as the dissolution agent, the dissolution temperature is controlled between 210℃, and the dissolution time is 1.5 hours to ensure the efficient dissolution of alumina and the enrichment of iron. In the third step, the chemical beneficiation stage adopts chemical The dissociator is hydrochloric acid. By adjusting the concentration of the dissociator and the reaction time, the iron minerals can be further enriched. The carbonization method used in the alumina extraction stage in the fourth step is to add an appropriate amount of sodium carbonate solution to the dissolution solution, and the precipitation of high-purity alumina is achieved by controlling the temperature and time of the carbonization reaction. The reduction roasting temperature used in the iron recovery stage in the fifth step is 950°C, and the roasting time is 1.5 hours to ensure the reduction effect and magnetic separation efficiency of the iron concentrate. The water washing method used in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure the full removal of alkaline substances and improve the environmental protection performance of the tailings.

[0036] Embodiment 5: A combined process for comprehensive utilization of red mud, such as Figure 1 As shown, it specifically includes the following steps: the first step: gravity magnetic stage: first extract iron concentrate containing 50% TFe (yield of about 35%) and iron ore containing 45% TFe (yield of about 5%-7%), and the remaining about 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%; the second step: high temperature dissolution stage: enter the high temperature dissolution, realize the utilization of alumina, and the iron content of the slag phase is increased to TFe40%-42%; the third step: chemical ore dressing stage: after chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate reaches more than 80%, and the dissolution solution, high-grade iron ore and tailings are obtained; the fourth step: alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition;

[0037] Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking;

[0038] Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The tailings obtained can be used as building materials or as fillers. In the first step, the heavy magnetic stage adopts wet strong magnetic separation technology. By adjusting the magnetic field strength and beneficiation concentration, the magnetic iron minerals in the red mud can be effectively separated. In the second step, the high temperature dissolution stage adopts NaOH solution as the dissolution agent, the dissolution temperature is controlled between 220℃, and the dissolution time is 1 hour to ensure the efficient dissolution of alumina and the enrichment of iron. In the third step, the chemical beneficiation stage adopts chemical The dissociator is sulfuric acid. By adjusting the concentration of the dissociator and the reaction time, the iron minerals can be further enriched. The carbonization method used in the alumina extraction stage in the fourth step is to add an appropriate amount of sodium carbonate solution to the dissolution solution, and the precipitation of high-purity alumina is achieved by controlling the temperature and time of the carbonization reaction. The reduction roasting temperature used in the iron recovery stage in the fifth step is 1000°C and the roasting time is 1 hour to ensure the reduction effect and magnetic separation efficiency of the iron concentrate. The water washing method used in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure the full removal of alkaline substances and improve the environmental protection performance of the tailings.

[0039] Working principle of the present invention: The working principle of the present invention is based on the separation and enrichment of different components in red mud. Through a series of physical and chemical treatment steps, efficient extraction of alumina, iron and other valuable elements is achieved. Red mud is a solid waste generated in the process of bauxite processing. It is rich in metal elements such as alumina and iron, but also contains a large amount of impurities such as silicon and titanium. The present invention not only improves the utilization rate of resources, but also reduces environmental pollution by optimizing the process flow. In the first step of the heavy magnetic stage, wet high-intensity magnetic separation technology is used to adjust the magnetic field intensity and the mineral processing concentration to achieve effective separation of magnetic iron minerals in red mud. The magnetic iron minerals are extracted as high-grade iron concentrate and iron ore, while the remaining red mud is rich in alumina. In the second step of the high-temperature dissolution stage, NaOH solution is used as a dissolving agent. By controlling the dissolution temperature and time, efficient dissolution of alumina and enrichment of iron are achieved. The dissolving solution is rich in alumina and iron, while the slag phase is rich in iron minerals. In the third step of the chemical mineral processing stage, a chemical dissociation agent (such as sulfur) is added to the ore. Acid or hydrochloric acid), adjust the concentration of the dissociator and the reaction time to further enrich the iron minerals. Through chemical dissociation, the iron minerals are converted into soluble salts, thereby achieving separation from impurities. In the fourth step, the alumina extraction stage, by adding an appropriate amount of sodium carbonate solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition. The temperature and time of the carbonization reaction are strictly controlled to ensure the precipitation efficiency and purity of the alumina. In the fifth step, the iron recovery stage, the high-grade iron concentrate obtained in the chemical beneficiation stage is subjected to reduction roasting, and then the iron grade is further improved by magnetic separation to finally obtain iron concentrate. The optimization of the reduction roasting temperature and time ensures the reduction effect and magnetic separation efficiency of the iron concentrate. In the sixth step, the tailings treatment stage, the tailings remaining after the chemical beneficiation are subjected to multi-stage countercurrent washing to remove residual alkaline substances, and then dried. The treated tailings can be used as building materials or as fillers, realizing the full component utilization of red mud and improving the environmental protection performance of the tailings.

[0040] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A combined process for comprehensive utilization of red mud, It is characterized in that The specific steps include: Step 1: Gravity and magnetism stage: first extract the iron concentrate containing 50% TFe and the iron middling containing 45% TFe, and the remaining 60% red mud Al2O3 is increased to 25%, and the iron content is reduced to 30%-32%; Step 2: High temperature dissolution stage: Entering high temperature dissolution, while realizing the utilization of alumina, the iron content of slag phase is increased to TFe40%-42%; Step 3: Chemical beneficiation stage: After chemical dissociation, the iron content is increased to more than 45%, and the comprehensive emission reduction rate is more than 80%, obtaining dissolution solution, high-grade iron ore concentrate and tailings; Step 4: Alumina extraction stage: by adding an appropriate amount of Na2CO3 solution, the alumina in the dissolution solution is converted into sodium aluminate, and then a high-purity alumina product is extracted by carbonization or seed decomposition method; Step 5: Iron recovery stage: The high-grade iron concentrate obtained in the chemical beneficiation stage is reduced and roasted, and then the iron grade is further improved through magnetic separation, and finally iron concentrate is obtained, which can be used as raw material for ironmaking; Step 6: Tailings treatment stage: The tailings remaining after chemical beneficiation are washed with water to remove residual alkaline substances, and then dried. The resulting tailings can be used as building materials or as fillers.

2. The combined process for comprehensive utilization of red mud according to claim 1, Features: In the first step, the gravity magnetic stage adopts wet high-intensity magnetic separation technology to achieve effective separation of magnetic iron minerals in red mud by adjusting the magnetic field intensity and mineral processing concentration.

3. The combined process for comprehensive utilization of red mud according to claim 1, Features: The dissolution agent used in the high-temperature dissolution stage of the second step is NaOH solution, the dissolution temperature is controlled between 180-220°C, and the dissolution time is 1-3 hours to ensure efficient dissolution of alumina and enrichment of iron.

4. The combined process for comprehensive utilization of red mud according to claim 1, Features: The chemical dissociation agent used in the chemical mineral processing stage in the third step is sulfuric acid or hydrochloric acid. By adjusting the concentration and reaction time of the dissociation agent, further enrichment of iron minerals can be achieved.

5. The combined process for comprehensive utilization of red mud according to claim 1, Features: The carbonization method used in the alumina extraction stage in the fourth step is to add an appropriate amount of sodium carbonate solution to the dissolution solution, and to achieve the precipitation of high-purity alumina by controlling the temperature and time of the carbonization reaction.

6. The combined process for comprehensive utilization of red mud according to claim 1, Features: The reduction roasting temperature used in the iron recovery stage in the fifth step is 800-1000° C. and the roasting time is 1-2 hours to ensure the reduction effect and magnetic separation efficiency of the iron concentrate.

7. The combined process for comprehensive utilization of red mud according to claim 1, Features: The water washing method adopted in the tailings treatment stage in the sixth step is multi-stage countercurrent washing to ensure the full removal of alkaline substances and improve the environmental performance of the tailings.

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