Red mud treatment method

Abstract

The invention provides a red mud treatment method. The treatment method effectively solves the problems that in the prior art, red mud is complex in component, poor in economical efficiency, poor in red mud magnetic concentrate grade and low in iron recovery rate, magnetic tailing resources are not fully utilized, the cost is low, and the like through electromagnetic magnetization pre-reduction roasting treatment, magnetic separation enrichment of iron concentrate powder, smelting reduction iron extraction, smelting tailings building application and magnetic separation tailing enrichment and aluminum extraction. The method solves the problems of difficulty in operation of a melting ironmaking process and poor building material performance of slag in the prior art, so that iron and aluminum in the red mud are fully recycled, and the economic benefit of red mud treatment is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of red mud recycling, and in particular to a method for treating red mud. Background Art

[0002] Red mud is a solid waste discharged when the aluminum industry extracts alumina. It is an alkaline bulk industrial solid waste. The large-scale storage of red mud brings huge environmental pollution problems and safety hazards to the ecological environment. At the same time, red mud is also a very valuable resource. The recovery of red mud valuable metals is an important method to solve the red mud pollution problem, safety hazards and achieve red mud reduction, resource utilization and harmlessness.

[0003] However, there are the following problems in the recycling of valuable metals from red mud:

[0004] (1) The grade of red mud magnetic concentrate is poor and the iron recovery rate is low. The selectable iron in red mud comes from the iron oxide in bauxite, the raw material for alumina production, and has a wide range of particle size distribution. The iron oxide after hydrolysis of some sodium ferrite cannot be effectively flocculated and has a relatively fine particle size. Even after roasting and reduction to form magnetic oxides, it is extremely difficult to recycle. In addition, the traditional magnetic separation process has the disadvantages of long process, low magnetic separation grade, low iron recovery rate, and poor economic efficiency of magnetic separation technology. In order to improve the magnetic selectability of iron resources in red mud and solve the problem of poor magnetic selectability and difficulty in enrichment of red mud raw materials, relevant patents have been developed to carry out low-temperature pre-reduction roasting treatment to convert iron oxides into magnetic iron oxides to improve the magnetic separation effect. However, due to the small size of red mud particles, only through low-temperature pre-reduction roasting treatment, even with magnetization pretreatment, the iron grade of magnetic iron concentrate is still limited (generally TFe: 45~55%), and the iron recovery rate is not high (45~65%).

[0005] (2) Magnetic tailings resources have not been fully utilized. The utilization value of tailings after traditional red mud beneficiation is low and still needs to be stored and disposed of, which fails to achieve the goal of comprehensive utilization of all components of red mud.

[0006] (3) Red mud has complex composition and poor economic efficiency. The phase change process of iron in bauxite is:

[0007] Fe2O3+Na2CO3→Na2O·Fe2O3+CO2 (1)

[0008] Na2O·Fe2O3+2H2O→Fe2O3·H2O +2NaOH (hydrolysis) (2)

[0009] The iron oxide deposited by hydrolysis is the main reason for the brown-red color of red mud; from the analysis of the phase change of the reaction, it can be inferred that this part of the iron oxide is a goethite phase. The iron and alkali content in red mud is high, resulting in the presence of compound alkali in the iron selected from the red mud. The presence of compound alkali will corrode the lining material (i.e., refractory material) of the smelting furnace (including top-blown furnace, side-blown furnace, electric furnace, medium-frequency furnace and other pyrometallurgical furnaces), affecting the service life of the furnace body. In addition, the high sodium and aluminum content in red mud leads to a short service life of the refractory material, a high flux rate, and a large amount of slag. In short, the composition of red mud is complex, and the traditional red mud ironmaking process has poor results. In addition, after the red mud is batched, the iron content in the furnace mixture is low, which makes the final red mud ironmaking technology less economical.

[0010] (4) The smelting ironmaking process is difficult to operate. The iron in the traditional red mud beneficiation iron concentrate is mainly in the form of magnetite. During the smelting reduction ironmaking process, a sufficient amount of reducing agent must be added to improve the efficiency of further reducing the iron to metallic iron. Magnetic iron reacts violently during the smelting reduction process. When the reducing agent is added, a large amount of CO and CO2 bubbles will be produced along with the iron reduction, and even foamy slag will be produced, which brings difficulties to the operation of the smelting ironmaking process.

[0011] (5) Poor performance of slag building materials. In the preparation of traditional red mud building materials, due to the presence of insoluble alkali (sodium), the material performance indicators of red mud direct building materials are poor, and there is alkali blooming, which not only affects the use of building materials, but also pollutes the environment. Although the slag left by traditional red mud smelting ironmaking can be used to prepare building materials, the activity of building material powder can be improved and sodium can be solidified by high-temperature molten glass phase, but for slag with high sodium content, there is still alkali blooming in high-sodium slag building materials.

[0012] A Chinese patent with publication number CN110004263B discloses a process for producing iron ore concentrate by a red mud fluidized bed method, comprising the steps of diluting and screening a red mud slurry; obtaining coarse iron powder by a pretreatment method of gravity separation, magnetic separation or a combination of gravity separation and magnetic separation; drying; controlling the fluidized reduction reaction temperature of the reduction fluidized bed at 450-550°C, reducing the coarse iron powder using coal gas with a volume ratio of CO+H2 of 40-50% in the reduction fluidized bed, and controlling the reduction reaction time at 8-15 minutes to obtain reduced magnetized coarse iron powder; grinding the reduced magnetized coarse iron powder to a size less than 100 mesh, and then performing physical separation to obtain iron ore concentrate with a grade of more than 61%.

[0013] The technical solution has the following main defects: (1) The process is relatively simple and has poor adaptability to red mud. When the iron content in red mud fluctuates greatly, it is impossible to ensure that the iron content in the iron powder product meets the standard; (2) Due to the physical method of iron selection, the grade of the iron powder product is generally low, 50~55%, and most of them are ferric oxide type. This kind of iron powder can only be used as a batching material for producing low-end iron products. (3) The high-temperature reduction amount of red mud is large, the efficiency is low, the energy consumption is large, and the economy is poor; (4) All red muds are fluidized, and the inclusion effect between red muds is significant, and the mutual influence is large, resulting in reduced reduction efficiency; (5) The magnetic separation intensity after reduction is high, reaching 5000~15000G, and the energy consumption is high. The Chinese patents with publication numbers CN219117519U, CN115058587B, CN107385197B, and CN104694760B have also made improvements to the above problems respectively, but they still cannot solve the above defects at the same time.

[0014] Therefore, how to rationally design the treatment process to achieve large-scale disposal of red mud and comprehensive utilization of all components has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0015] The main purpose of the present invention is to provide a method for treating red mud to solve the problems in the prior art that iron and aluminum in red mud are difficult to fully recycle and the economic benefits of red mud treatment are poor.

[0016] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a method for treating red mud, comprising the following steps: step S1, mixing red mud with a first solid reducing agent for granulation to obtain pellets, performing a first roasting on the pellets at 700-1000°C, and performing electromagnetic induction treatment to obtain electromagnetic magnetized products; or, performing a second roasting on the red mud at 500-800°C in an atmosphere including a first gaseous reducing agent, and performing electromagnetic induction treatment to obtain electromagnetic magnetized products; step S2, performing magnetic separation on the electromagnetic magnetized products to obtain magnetically separated iron ore concentrate and magnetically separated tailings; step S3, performing smelting reduction on the magnetically separated iron ore concentrate to obtain molten slag and pig iron; step S4, performing quenching treatment and grinding on the molten slag to obtain active micropowder for building materials; step S5, extracting aluminum from the magnetically separated tailings.

[0017] Furthermore, in step S1, the first solid reducing agent includes one or more of anthracite, coke and graphite, and the molar ratio of the first solid reducing agent to red mud is (15-35):100.

[0018] Further, in step S1, the first gaseous reducing agent includes one or more of carbon monoxide, hydrogen, water gas, ammonia and carbon dioxide; and / or, the molar ratio of the first gaseous reducing agent to red mud is (20-40):100.

[0019] Furthermore, the volume percentage of the first gaseous reducing agent in the atmosphere is 20-40%.

[0020] Furthermore, in step S1, the D50 of the pellets is 5-30 mm; and / or, in terms of weight percentage, the moisture content of the pellets is less than 5%.

[0021] Furthermore, in step S1, the heating power of electromagnetic induction is 5-25KW.

[0022] Furthermore, in step S1, the temperature of the first calcination is 750-850° C.; and / or the time of the first calcination is 0.5-1.5 h.

[0023] Furthermore, in step S1, the temperature of the second calcination is 650-700° C.; and / or the time of the second calcination is 0.5-2 h.

[0024] Furthermore, in step S1, the electromagnetic magnetization product includes an iron-containing phase, the iron-containing phase includes a magnetically selectable iron phase, and the weight percentage of the magnetically selectable iron phase in the iron-containing phase is ≥75%.

[0025] Furthermore, in step S2, the magnetic field strength of the magnetic separation is 2000-8000 Oersted.

[0026] Further, in step S2, the magnetic separation is one-stage magnetic separation or two-stage magnetic separation, the one-stage magnetic separation is direct weak magnetic separation, and the two-stage magnetic separation includes strong magnetic separation and weak magnetic separation performed sequentially.

[0027] Furthermore, in step S2, the iron grade of the magnetically separated iron concentrate is greater than 60%, and the iron recovery rate is greater than 85%; and / or, the iron grade of the magnetically separated tailings is less than 10%; and / or, the weight percentage of aluminum in the magnetically separated tailings is 20-35%.

[0028] Furthermore, in step S3, a flux and a second reducing agent are added to perform melt reduction, the flux rate is 3-10%, and the second reducing agent rate is 5-8%.

[0029] Further, in step S3, the second reducing agent includes one or more of anthracite, coke, lignite and biomass; and / or the temperature of the smelting reduction is 1450-1550°C.

[0030] Furthermore, in step S3, the molten slag is CaO-SiO2-Al2O3; and / or the basicity of the molten slag is 1-1.2; and / or the weight percentage of Al2O3 in the molten slag is 5-15%.

[0031] The present invention combines the characteristics of red mud components, aims at the recovery of valuable metal iron and aluminum resources, and the comprehensive utilization of all components of red mud, and proposes a technical scheme of "electromagnetic magnetization pre-reduction roasting treatment - magnetic separation enrichment of iron ore concentrate - molten reduction to extract iron - application of smelting tailings as building materials - magnetic separation tailings enrichment and aluminum extraction" to achieve the purpose of large-scale disposal of red mud and comprehensive utilization of all components.

[0032] The processing method of the present invention has strong adaptability to red mud raw materials, is not limited to the range of iron content in red mud, and is applicable to both low-iron and high-iron red mud. The processing method of the present invention adopts an electromagnetic magnetization selective semi-melting method, and uses electromagnetic induction to selectively and efficiently heat the magnetic iron-containing particles, so that they are quickly melted, aggregated, and grown, providing process conditions for subsequent magnetic separation, so that the iron grade of magnetic iron concentrate is greatly improved, and the iron content in the magnetic separation tailings is significantly reduced. After magnetization, the magnetism of elemental iron is improved, and the particle size is increased, which is conducive to separating the magnetic elemental iron, thereby improving the economy of magnetic separation technology. In addition, in the magnetic separation tailings after the iron is separated, the aluminum element is enriched, which can be returned as an aluminum ore resource to extract aluminum metal again, thereby fully recovering the aluminum element.

[0033] In addition, the iron grade of magnetic iron concentrate is high. As the raw material for the molten reduction iron extraction process, it improves the iron grade of pig iron and effectively improves the economic efficiency. The iron in the magnetic iron concentrate mainly exists in the form of elemental iron, which effectively reduces the reducing agent rate, flux rate and smelting energy consumption in the molten reduction iron extraction process, improves the reaction efficiency of ironmaking, and reduces the amount of smelting slag. Moreover, the sodium content in the magnetic iron concentrate is relatively low, which effectively solves the problem of raw material corrosion to refractory materials during the molten reduction process. Secondly, the molten slag obtained after molten reduction can be used as active micropowder for building materials after treatment, which effectively improves the performance of building materials and makes full use of magnetic tailings resources.

[0034] In summary, the treatment method of the present invention effectively solves the problems in the prior art of complex red mud composition, poor economy, poor grade of red mud magnetic concentrate, low iron recovery rate, underutilized magnetic tailings resources, difficult operation of smelting ironmaking process and poor performance of slag as building materials, so that the iron and aluminum in red mud can be fully recovered and utilized, and the economic benefits of red mud treatment can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0036] Figure 1 The microscopic morphology of the red mud raw material according to Example 1 of the present invention at a magnification of 200 times is shown;

[0037] Figure 2 The microscopic morphology of the red mud raw material according to Example 1 of the present invention at a magnification of 500 times is shown;

[0038] Figure 3 The microscopic morphology of the red mud raw material according to Example 1 of the present invention at a magnification of 500 times is shown;

[0039] Figure 4 The Fe element distribution diagram of the red mud raw material according to Example 1 of the present invention at a magnification of 500 times is shown;

[0040] Figure 5 The optical macroscopic morphology of the electromagnetic magnetization product according to Example 1 of the present invention is shown;

[0041] Figure 6 The optical macroscopic morphology of the electromagnetic magnetization product according to Example 1 of the present invention is shown;

[0042] Figure 7 The microscopic morphology of the electromagnetic magnetization product according to Example 1 of the present invention at a magnification of 200 times is shown;

[0043] Figure 8 The microscopic morphology of the electromagnetic magnetization product according to Example 1 of the present invention at a magnification of 1000 times is shown;

[0044] Fig. 9 shows a microscopic morphology of the electromagnetic magnetization product according to Example 1 of the present invention at a magnification of 1000 times; and

[0045] Fig.10 The figure shows the distribution of Fe elements in the electromagnetic magnetization product according to Example 1 of the present invention at a magnification of 1000 times. DETAILED DESCRIPTION

[0046] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0047] Terminology explanation:

[0048] Reductant ratio: the molar ratio of reducing agent to red mud.

[0049] Flux ratio: the molar ratio of flux to red mud.

[0050] Basicity of molten slag: In this application, it is the molar ratio of CaO to SiO2.

[0051] Activity index: Replace cement with active micropowder in a certain proportion, compare with pure cement mortar or concrete, and test the compressive strength after 28 days. Activity index = (compressive strength of mortar or concrete mixed with active micropowder / compressive strength of pure cement mortar or concrete) × 100%.

[0052] As described in the background technology of the present invention, the prior art has problems such as difficulty in fully recycling iron and aluminum in red mud and poor economic benefits of red mud treatment, especially the complex composition of red mud and poor economy, poor grade of red mud magnetic concentrate and low iron recovery rate, under-utilization of magnetic tailings resources, difficult operation of smelting ironmaking process and poor performance of slag as building materials. In order to solve the above problems, in a typical embodiment of the present invention, a method for treating red mud is provided, comprising the following steps: step S1, mixing red mud with a first solid reducing agent for granulation to obtain pellets, performing a first roasting on the pellets at 700-1000°C, and performing electromagnetic induction treatment to obtain electromagnetic magnetized products; or, performing a second roasting on the red mud at 500-800°C in an atmosphere including a first gaseous reducing agent, and performing electromagnetic induction treatment to obtain electromagnetic magnetized products; step S2, performing magnetic separation on the electromagnetic magnetized products to obtain magnetically separated iron ore concentrate and magnetically separated tailings; step S3, performing molten reduction on the magnetically separated iron ore concentrate to obtain molten slag and pig iron; step S4, performing quenching treatment and grinding on the molten slag to obtain active micropowder for building materials; step S5, extracting aluminum from the magnetically separated tailings.

[0053] In the processing method of the present application, step S1 is an electromagnetic magnetization pre-reduction roasting treatment, and the roasting conditions and related granulation processes are defined according to the state of the reducing agent.

[0054] One is "electromagnetic magnetization solid base pre-reduction roasting treatment", first the raw red mud and the reducing agent are pressed into balls to granulate and obtain pellets; under medium temperature conditions of 700~1000℃, the pellets are roasted and subjected to electromagnetic induction treatment to pre-reduce the iron oxides (such as Fe3O4, etc.) in the red mud and convert them into elemental iron and magnetic iron (such as Fe2O3, Fe3O4, FeO, etc.) to obtain electromagnetic magnetization products.

[0055] The other is "electromagnetic magnetization gas-based pre-reduction roasting treatment", which pre-reduces the red mud raw material with a gas-based reducing agent and enters the electromagnetic magnetization section. The pre-reduction process reduces the iron oxide in the red mud to elemental iron and magnetic iron, and uses electromagnetic rapid semi-melting of iron-containing magnetic particles to aggregate and grow them, which can provide magnetic separation processability for subsequent mineral processing. In addition, the red mud raw material is fine powder particles in this process and does not need to be briquette.

[0056] The traditional magnetic separation process is long, the magnetic separation grade is low, the iron recovery rate is low, and the economic efficiency of magnetic separation technology is poor. In particular, although the traditional roasting and magnetization pretreatment method (low-temperature pre-reduction roasting treatment, such as 350~550℃) can realize the transformation of iron oxides into magnetic iron or elemental iron, the red mud itself has a small particle size. Even with magnetic pretreatment, it is difficult for iron-containing particles to aggregate at low temperatures, resulting in the inability to effectively separate the iron-containing particles during the magnetic separation process, resulting in limited iron grade of magnetically separated iron concentrate (generally TFe: 45~55%) and low iron recovery rate (45~65%).

[0057] Compared with the traditional magnetic iron magnetization process, the electromagnetic magnetization pre-reduction roasting process of the present application has a higher temperature. Combined with electromagnetic induction, the magnetic iron-containing particles in the electromagnetic magnetization product can be selectively and efficiently heated to quickly reach a liquid phase semi-molten state. Affected by the polymerization effect between the melts, the fine magnetic iron-containing metal particles aggregate and grow, which is beneficial to the effective separation of the magnetic iron-containing metal particles with increased particle size in the subsequent magnetic separation process, thereby facilitating the improvement of the iron grade of the magnetically separated iron concentrate in the subsequent magnetic separation process, and can effectively improve the iron recovery rate. It should be noted that the fine magnetic iron-containing particles inside the electromagnetic magnetization product form aggregated droplets. For example, the pellets as a whole do not form a melt and are still in a solid phase, which is beneficial to achieve the purpose of "electromagnetic induction selective reduction magnetization semi-molten" roasting pretreatment.

[0058] The roasting temperature is specially set in the present application. If the roasting temperature is too high, the energy consumption will be too large and the economy will be poor. If the roasting temperature is too low, the melting, aggregation and growth of the magnetic iron-containing particles will be slow, and the iron-containing particles with smaller particle size cannot be effectively separated, which is not conducive to the subsequent magnetic separation process. The magnetically separated iron concentrate obtained has a poor iron grade, a low iron recovery rate, and low production efficiency.

[0059] After the electromagnetic magnetization pre-reduction roasting treatment, the iron-containing phase in the electromagnetic magnetization product is mainly grown elemental iron particles (mainly, including magnetic and non-magnetic elemental Fe) and grown magnetic iron particles (a small amount, including Fe2O3, Fe3O4, FeO, etc. generated during the electromagnetic magnetization pre-reduction roasting treatment). Step S2, magnetic separation of the electromagnetic magnetization product to obtain magnetic iron concentrate and magnetic tailings. After magnetic separation, the iron content in the magnetic tailings is greatly reduced, and the relative content of other elements (such as Si, Al, Ca, Ti, etc.) is greatly increased. For example, the aluminum content in the magnetic tailings is relatively high (Al2O3 can reach 20~35%), which can be used as bauxite resources to return to alumina enterprises as raw materials to extract aluminum elements, so that the utilization value of the tailings is improved, and the comprehensive utilization rate of all components can also be improved.

[0060] Compared with red mud raw materials, the iron grade of magnetic iron concentrate is significantly improved, which can further improve the iron grade of pig iron. However, some components of magnetic iron concentrate are magnetic iron that is absorbed and introduced into elemental iron due to inclusion in elemental iron, such as Fe2O3, Fe3O4, FeO, etc. Step S3, melting and reducing the magnetic iron concentrate, can further reduce the iron-containing phase to elemental iron, thereby improving the iron grade, and can also precipitate elements such as Si and Al in solid form, and after cooling, molten slag and pig iron are obtained.

[0061] Correspondingly, the aluminum and sodium contents of magnetically separated iron ore concentrate are greatly reduced. On the one hand, it is beneficial to reduce the flux rate in the smelting reduction process, thereby effectively reducing the amount of slag introduced and improving economy. On the other hand, the sodium content in the molten slag is also significantly reduced, which can not only effectively reduce the influence of sodium on the service life of refractory materials, but also reduce the influence of sodium on the subsequent performance indicators of slag building materials. The smelting ironmaking process has low difficulty in operation and the smelting ironmaking technology has high economy.

[0062] Step S4, quenching the obtained molten slag and grinding it to obtain active micropowder. The building materials prepared from traditional red mud have poor performance indicators due to the presence of insoluble alkali (sodium), and there is alkali efflorescence, which affects the use of building materials and pollutes the environment. The slag obtained after traditional red mud smelting and ironmaking is used to prepare building materials. Although it can improve the activity of building material micropowders and use high-temperature molten glass phase to solidify sodium elements, it still fails to completely solve the alkali efflorescence phenomenon of high-sodium slag building materials for slag with high sodium content. Compared with the traditional process, the sodium content in the molten slag of the present application is reduced by about 50~70%, which can effectively solve the problem of alkali efflorescence of molten slag building materials. In addition, the glass phase of the molten slag is conducive to improving the activity of the active micropowder of the molten slag building materials, and can also achieve the performance indicators of the building materials.

[0063] In summary, the processing method of the present application has strong adaptability to red mud raw materials, is not limited to the range of iron content in red mud, and is applicable to both low-iron and high-iron red mud. The processing method of the present application adopts an electromagnetic magnetization selective semi-melting method, and uses electromagnetic induction to selectively and efficiently heat the magnetic iron-containing particles, so that they melt, aggregate, and grow rapidly, providing process conditions for subsequent magnetic separation, which can greatly improve the iron grade of magnetic iron concentrate and reduce the iron content in magnetic separation tailings. After magnetization, the magnetism of elemental iron is improved, and the particle size is increased, which is conducive to separating magnetic elemental iron, thereby improving the economy of magnetic separation technology. In addition, in the magnetic separation tailings after iron separation, aluminum is enriched, which can be returned as an aluminum ore resource to extract aluminum metal again, thereby fully recovering the aluminum element.

[0064] In addition, the iron grade of magnetic iron concentrate is high. As the raw material for the molten reduction iron extraction process, it can improve the iron grade of pig iron and effectively improve the economic efficiency. The iron in the magnetic iron concentrate mainly exists in the form of elemental iron, which can effectively reduce the reducing agent rate, flux rate and smelting energy consumption in the molten reduction iron extraction process, improve the reaction efficiency of ironmaking, and reduce the amount of smelting slag. Moreover, the sodium content in the magnetic iron concentrate is relatively low, which can effectively solve the problem of raw material corrosion to refractory materials during the molten reduction process. Secondly, the molten slag obtained after molten reduction can be used as active micropowder for building materials after treatment, which effectively improves the performance of building materials and makes full use of magnetic tailings resources.

[0065] In a preferred embodiment, in step S1, the first solid reductant includes one or more of anthracite, coke and graphite; and / or, the molar ratio of the first solid reductant to red mud is (15-35):100. In a preferred embodiment, the first gaseous reductant includes one or more of carbon monoxide, hydrogen, water gas, ammonia and carbon dioxide; and / or, the molar ratio of the first gaseous reductant to red mud is (20-40):100. In a preferred embodiment, the volume percentage of the first gaseous reductant in the atmosphere is 20-40%. Within the above range, iron oxides can be more fully converted into elemental iron, and a small part of them can be converted into magnetic iron, which is more conducive to improving the magnetic separation effect of elemental iron, improving the iron grade of magnetically separated iron concentrate and improving the iron recovery rate.

[0066] In order to facilitate the melting, aggregation and growth of iron-containing particles, in a preferred embodiment, in step S1, the D50 of the pellets is 5-30 mm, preferably 5-20 mm. In order to more effectively reduce the occurrence of side reactions and reduce energy consumption, thereby being more conducive to improving the iron grade of the electromagnetic magnetization product and improving economic efficiency, the moisture content of the pellets is less than 5% by weight.

[0067] The heating power of electromagnetic induction is closely related to the roasting temperature. If the roasting temperature is low, the heating power of electromagnetic induction needs to be increased to provide heat so that the pellets reach a semi-molten state more quickly. In a preferred embodiment, in step S1, the heating power of electromagnetic induction is 5~25KW, preferably 6~10KW. Under the above conditions, the speed and magnetic strength of the aggregation and growth of iron-containing particles can be further improved, and the electromagnetic magnetization product can also reach a semi-molten state more quickly, which is more conducive to improving the separation effect and production efficiency of magnetic separation, and improving the iron grade in the magnetic separation iron concentrate. If the heating power of electromagnetic induction is less than 5KW, it may cause the iron-containing particles to aggregate and grow slowly, thereby making the production efficiency low; if the heating power of electromagnetic induction is greater than 25KW, it is easy to cause large-area melting of the electromagnetic magnetization product, which is not easy to operate.

[0068] In order to more effectively improve the extraction efficiency of red mud iron resources, in a preferred embodiment, in step S1, the temperature of the first roasting is 750-850°C; and / or, the time of the first roasting is 0.5-1.5h. In a preferred embodiment, the temperature of the second roasting is 650-700°C; and / or, the time of the second roasting is 0.5-2h. Under the above conditions, it is more conducive to increasing the size of the pre-reduced metal particles, and thus more conducive to improving the subsequent magnetic separation metal recovery rate.

[0069] In a preferred embodiment, in step S1, the electromagnetic magnetization product includes an iron-containing phase, the iron-containing phase includes a magnetically selectable iron phase, and the weight percentage of the magnetically selectable iron phase in the iron-containing phase is ≥75%. Under the above conditions, it is more conducive to improving the magnetic separation effect. In a preferred embodiment, the size of the electromagnetic magnetization product is 5~100μm; and / or, the roasting is carried out in a heating furnace, and the heating furnace includes one or more of a medium frequency furnace, a gas rotary kiln, an electromagnetic rotary kiln, a graphite kiln, a tunnel kiln and a reduction shaft furnace. In a preferred embodiment, in step S2, the heating furnace and the electromagnetic induction heating area can be an integrated equipment or a combination of separate equipment. It should be noted that when the heating furnace and the electromagnetic induction heating area are a combination of separate equipment, the temperature of the electromagnetic induction heating area is the same as the roasting temperature.

[0070] In a preferred embodiment, in step S2, the magnetic field strength of the magnetic separation is 2000-8000 oersteds. In a preferred embodiment, the magnetic separation is one-stage magnetic separation or two-stage magnetic separation, one-stage magnetic separation is direct weak magnetic separation, and the two-stage magnetic separation includes strong magnetic separation and weak magnetic separation performed in sequence. Under the above conditions, energy consumption is smaller, the magnetic separation effect is better, the iron grade of the magnetic separation iron concentrate is higher, the iron content in the magnetic separation tailings is less, and the iron recovery rate is higher.

[0071] In a preferred embodiment, the iron grade of the magnetic iron concentrate is greater than 60%, and the iron recovery rate is greater than 85%; and / or, the iron grade of the magnetic tailings is less than 10%; preferably, the iron grade of the magnetic tailings is less than 5%; and / or, the weight percentage of aluminum in the magnetic tailings is 20-35%. As mentioned above, by adopting the preparation method of the present application, the magnetic iron concentrate obtained has a high iron grade and a high iron recovery rate, and the iron grade of the magnetic tailings is low.

[0072] In a preferred embodiment, in step S3, a flux and a second reducing agent are added for smelting reduction, the flux rate is 3-10%, and the second reducing agent rate is 5-8%. In a preferred embodiment, the second reducing agent includes one or more of anthracite, coke, lignite and biomass; and / or, the smelting reduction is carried out in a smelting reduction furnace, and the smelting reduction furnace includes one or more of an electric furnace, a side-blown furnace and an intermediate frequency furnace; and / or, the temperature of the smelting reduction is 1450-1550°C.

[0073] Compared with the traditional process, in the process of molten reduction iron extraction, the content of the second reducing agent added to the reduction reaction of the present application is significantly reduced, the effect of separating elemental iron is better, and the risk of producing foamy slag due to the violent reaction of magnetic iron in the molten reduction process can be more effectively reduced, thereby further reducing the difficulty of operation of the molten ironmaking process. In addition, the comprehensive energy consumption of the molten ironmaking process can be more effectively reduced. Under the above conditions, the molten reduction reaction is more sufficient, the flux rate and the reducing agent rate are lower, and the introduced impurities are less, which is more conducive to reducing the influence of sodium on the service life of refractory materials, reducing the influence of sodium on the subsequent slag building material performance indicators, and improving the iron grade of the furnace mixture, which is more conducive to improving the economy of molten ironmaking technology and the recovery rate of iron.

[0074] In order to further achieve full recovery of aluminum in red mud, in a preferred embodiment, the molten slag is CaO-SiO2-Al2O3; and / or the basicity of the molten slag (i.e., the molar ratio of CaO and SiO2) is 1-1.2; and / or the weight percentage of Al2O3 in the molten slag is 5-15%; and / or the iron grade of the molten slag is less than 2%; and / or the iron recovery rate of pig iron is greater than 92%.

[0075] In a preferred embodiment, the specific surface area of ​​the active micropowder is 443-501 m 2 / kg, the 7-day activity index is 58-70%, the 28-day activity index is 85-108%, the initial setting time ratio is 110-120%, and the activity index after steaming at 80°C for 12 hours is 127-135%. As mentioned above, due to the presence of the glass phase in the molten slag of this application, the active micropowder has good activity and can meet the performance index requirements of building materials.

[0076] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0077] The chemical composition of Guinea high-iron red mud (dry basis) is shown in Table 1, and the chemical composition of low-iron red mud (dry basis) is shown in Table 2, calculated by weight percentage.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] Example 1

[0083] The red mud raw material is Guinea high iron red mud. The microscopic morphology of the red mud raw material at 200 times magnification is shown in Figure 1 The microscopic morphology of red mud raw material at 500 times magnification is shown in Figure 2 The microscopic morphology of red mud raw material at 500 times magnification is shown in Figure 3 The Fe element distribution diagram of red mud raw material at 500 times magnification is shown in Figure 4 .

[0084] Step S1, pre-reduction roasting treatment: red mud and a reducing agent (anthracite, in molar ratio, the reducing agent rate is 25%) are mixed, granulated, and dried to obtain pellets, the D50 of the pellets is 15 mm, and the moisture content of the pellets is 3% by weight percentage; the heating furnace and the electromagnetic induction heating area are integrated into one equipment (intermediate frequency furnace), and the pellets are roasted and magnetized by the intermediate frequency furnace to perform electromagnetic magnetization roasting pre-reduction treatment, wherein the heating power of the intermediate frequency furnace is 8KW, the roasting temperature is 800°C, and the roasting time is 1h to obtain an electromagnetic magnetization product. The electromagnetic magnetization product includes an iron-containing phase, and the iron-containing phase includes a magnetically selectable iron phase, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 85%.

[0085] The optical macroscopic morphology of the electromagnetic magnetization product is shown in Figure 5 and Figure 6 The microscopic morphology of the electromagnetic magnetization product at a magnification of 200 times is shown in Figure 7 The microscopic morphology of the electromagnetic magnetization product at a magnification of 1000 times is shown in Figure 8 The microscopic morphology of the electromagnetic magnetization product at a magnification of 1000 times is shown in Fig. 9 The Fe element distribution diagram of the electromagnetic magnetization product at 1000 times magnification is shown in Fig.10 .Will Figure 1 and Figure 7 By comparison, it can be seen that after magnetization and calcination, the size of the iron-containing particles in the electromagnetic magnetization product increases significantly.

[0086] Step S2, magnetic separation and enrichment of iron ore concentrate: under the condition that the magnetic field strength of the magnetic separation is 3000 oersted, the electromagnetic magnetization product is directly subjected to weak magnetic separation to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate is 69.65%, and the iron grade of the magnetically separated tailings is 5.01%. After magnetic separation, the iron recovery rate is 97.19%.

[0087] Step S3, smelting reduction to extract iron: an electric furnace is used, and a flux (limestone) and a second reducing agent (anthracite) are added for smelting reduction. The flux rate is 7%, and the second reducing agent rate is 7%. At a temperature of 1500°C, the magnetically separated iron concentrate is smelted and reduced to obtain molten slag and iron. The molten slag is a CaO-SiO2-Al2O3 slag type with a basicity of 1.1 and a molar ratio of Al2O3 in the molten slag of 10%. The iron grade of the molten slag is 0.52%. After smelting reduction, the iron recovery rate of pig iron is 96%.

[0088] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0089] Step S5, enriching the tailings with magnetic separation and then extracting aluminum: extracting aluminum from the tailings with magnetic separation.

[0090] Example 2

[0091] The only difference from Example 1 is:

[0092] Step S3, smelting reduction to extract iron: a side-blown smelting furnace is used to smelt and reduce the magnetically separated iron concentrate at a temperature of 1500°C to obtain molten slag and iron. The molten slag is a CaO-SiO2-Al2O3 slag type with a basicity of 1.1 and a molar ratio of Al2O3 in the molten slag of 10%. The iron grade of the molten slag is 1.37%. After smelting reduction, the iron recovery rate of the pig iron is 94%.

[0093] Example 3

[0094] The only difference from Example 1 is:

[0095] The red mud raw material is Guinea low-iron red mud.

[0096] Step S1, electromagnetic magnetization pre-reduction roasting treatment: red mud and a reducing agent (coke, in molar ratio, the reducing agent rate is 15%) are mixed, granulated, and dried to obtain pellets, the pellets have a D50 of 5 mm, and the moisture content of the pellets is 4% by weight. The pellets are heated and magnetized by an electromagnetic rotary kiln to perform electromagnetic magnetization roasting pre-reduction treatment, the heating power is 6KW, the roasting temperature is 750°C, and the roasting time is 1.5h to obtain an electromagnetic magnetization product. The electromagnetic magnetization product includes an iron-containing phase, the iron-containing phase includes a magnetically selectable iron phase, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 75%.

[0097] Step S2, magnetic separation and enrichment of iron ore concentrate: Under the condition of a magnetic separation intensity of 2000 oersteds, the electromagnetic magnetization product is magnetically separated to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate is 62%, and the iron grade of the magnetically separated tailings is 9.8%. After magnetic separation, the iron recovery rate is 87%.

[0098] Step S3, smelting reduction to extract iron: an electric furnace is used, and a flux (limestone) and a second reducing agent (anthracite) are added for smelting reduction. The flux rate is 5%, and the second reducing agent rate is 6.5%. At a temperature of 1450°C, the magnetically separated iron concentrate is smelted and reduced to obtain molten slag and iron. The molten slag is a CaO-SiO2-Al2O3 slag type with a basicity of 1. The molar ratio of Al2O3 in the molten slag is 5%; the iron grade of the molten slag is 1.5%. After smelting reduction, the iron recovery rate of pig iron is 94%.

[0099] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0100] Example 4

[0101] The only difference from Example 1 is:

[0102] Step S1, electromagnetic magnetization pre-reduction roasting treatment: red mud and a reducing agent (graphite, in molar ratio, the reducing agent rate is 35%) are mixed, granulated, and dried to obtain pellets, the pellets have a D50 of 20 mm, and the moisture content of the pellets is 4.5% by weight percentage. The pellets are heated and magnetized by a reduction shaft furnace to perform electromagnetic magnetization roasting pre-reduction treatment, the heating power is 10KW, the roasting temperature is 850°C, and the roasting time is 0.5h to obtain an electromagnetic magnetization product. The electromagnetic magnetization product includes an iron-containing phase, the iron-containing phase includes a magnetically selectable iron phase, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 80%.

[0103] Step S2, magnetic separation and enrichment of iron ore concentrate: Under the condition of a magnetic separation intensity of 3500 oersteds, the electromagnetic magnetization product is magnetically separated to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate is 60%, and the iron grade of the magnetically separated tailings is 9.2%. After magnetic separation, the iron recovery rate is 90%.

[0104] Step S3, smelting reduction to extract iron: a side-blown furnace is used, and a flux (limestone) and a second reducing agent (coke) are added for smelting reduction. The flux rate is 8%, and the second reducing agent rate is 6.5%. At a temperature of 1550°C, the magnetically separated iron concentrate is smelted and reduced to obtain molten slag and iron. The molten slag is a CaO-SiO2-Al2O3 slag type with a basicity of 1.2 and a molar ratio of Al2O3 in the molten slag of 15%. The iron grade of the molten slag is 1.8%. After smelting reduction, the iron recovery rate of pig iron is 95%.

[0105] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0106] Example 5

[0107] The red mud raw material is high iron type Guinea red mud.

[0108] Step S1, pre-reduction roasting treatment: the red mud powder raw material is directly added to the fluidized bed, the pre-reduction temperature of the fluidized bed is controlled at 650°C, and the reducing atmosphere is controlled by external gas distribution (the volume content of CO in the atmosphere is 35%, and the molar ratio of CO to red mud is 25:100), and roasting is carried out for 2 hours. The red mud powder flowing out of the fluidized bed is treated in the electromagnetic induction heating zone, and the magnetically selected iron-containing particles in the red mud powder are rapidly heated by electromagnetic selectivity. Under the conditions of electromagnetic magnetization power of 25KW, magnetization temperature of 800°C, and magnetization time of 30min, the metallization rate of iron reaches 75%, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 85%.

[0109] Step S2, magnetic separation and enrichment of iron ore concentrate: through two-stage magnetic separation treatment (strong magnetic separation 8000 oersted + 3000 oersted), the roasting product is magnetically separated to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate reaches 61.02%, the iron grade of the magnetically separated tailings is 9.77%, and the iron recovery rate reaches 98.23%.

[0110] Step S3, smelting reduction iron extraction: an electric furnace is used, and a flux (limestone) and a second reducing agent (anthracite) are added for smelting reduction. The flux rate is 7%, the second reducing agent rate is 6.5%, and when the molten slag temperature is controlled at 1500°C, the iron grade of the molten slag is 0.39%, and the metal Fe recovery rate is 97%.

[0111] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0112] Step S5, enriching the tailings with magnetic separation and then extracting aluminum: extracting aluminum from the tailings with magnetic separation.

[0113] Example 6

[0114] The only difference from Example 5 is that:

[0115] Step S1, pre-reduction roasting treatment: the red mud powder raw material is directly added to the fluidized bed, the pre-reduction temperature of the fluidized bed is controlled at 500°C, and the reducing atmosphere is controlled by external gas distribution (the volume content of CO in the atmosphere is 40%, and the molar ratio of CO to red mud is 30:100), and roasting is carried out for 2 hours. The red mud powder flowing out of the fluidized bed is treated in the electromagnetic induction heating zone, and the magnetically selected iron-containing particles in the red mud powder are rapidly heated by electromagnetic selectivity. Under the conditions of electromagnetic magnetization power of 25KW, magnetization temperature of 1000°C, and magnetization time of 30min, the metallization rate of iron reaches 85%, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 95%.

[0116] Step S2, magnetic separation and enrichment of iron ore concentrate: through two-stage magnetic separation treatment (strong magnetic separation 8000 oersted + 3000 oersted), the roasting product is magnetically separated to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate reaches 68%, the iron grade of the magnetically separated tailings is 8.5%, and the iron recovery rate reaches 98%.

[0117] Step S3, smelting reduction iron extraction: adopt side-blowing smelting reduction iron extraction test, when the slag temperature is controlled at 1500°C, the slag contains TFe: 1.58%, and the metal Fe recovery rate is more than 95%.

[0118] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0119] Step S5, enriching the tailings with magnetic separation and then extracting aluminum: extracting aluminum from the tailings with magnetic separation.

[0120] Example 7

[0121] The red mud raw material is high iron type Guinea red mud.

[0122] Step S1, pre-reduction roasting treatment: the red mud powder raw material is directly added to the fluidized bed, the pre-reduction temperature of the fluidized bed is controlled at 500°C, and the reducing atmosphere is controlled by external gas distribution (the volume content of hydrogen in the atmosphere is 40%, and the molar ratio of hydrogen to red mud is 30:100), and roasting is carried out for 2 hours. The red mud powder flowing out of the fluidized bed is treated in the electromagnetic induction heating zone, and the magnetically selected iron-containing particles in the red mud powder are rapidly heated by electromagnetic selectivity. Under the conditions of electromagnetic magnetization power of 5KW, magnetization temperature of 800°C, and magnetization time of 30min, the metallization rate of iron reaches 72%, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 83%.

[0123] Step S2, magnetic separation and enrichment of iron ore concentrate: through a magnetic separation treatment (strong magnetic separation 8000 oersted), the roasting product is magnetically separated to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate reaches 60.9%, the iron grade of the magnetically separated tailings is 9.87%, and the iron recovery rate reaches 97.5%.

[0124] Step S3, smelting reduction to extract iron: an electric furnace is used, and a flux (limestone) and a second reducing agent (lignite) are added for smelting reduction. The flux rate is 3%, the second reducing agent rate is 8%, and when the molten slag temperature is controlled at 1450°C, the iron grade of the molten slag is 0.29%, and the metal Fe recovery rate is 98%.

[0125] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0126] Step S5, enriching the tailings with magnetic separation and then extracting aluminum: extracting aluminum from the tailings with magnetic separation.

[0127] Example 8

[0128] The red mud raw material is high iron type Guinea red mud.

[0129] Step S1, pre-reduction roasting treatment: the red mud powder raw material is directly added to the fluidized bed, the pre-reduction temperature of the fluidized bed is controlled at 700°C, and the reducing atmosphere is controlled by external gas distribution (the volume content of water gas in the atmosphere is 20%, and the molar ratio of water gas to red mud is 20:100), and roasting is performed for 0.5h. The red mud powder flowing out of the fluidized bed is treated in the electromagnetic induction heating zone, and the magnetically selected iron-containing particles in the red mud powder are rapidly heated by electromagnetic selectivity. Under the conditions of electromagnetic magnetization power of 25KW, magnetization temperature of 800°C, and magnetization time of 30min, the metallization rate of iron reaches 77%, and the weight ratio of the magnetically selectable iron phase in the iron-containing phase is 87%.

[0130] Step S2, magnetic separation and enrichment of iron ore concentrate: through two-stage magnetic separation treatment (strong magnetic separation 8000 oersted + 3000 oersted), the roasting product is magnetically separated to obtain magnetically separated iron ore concentrate and magnetically separated tailings; the iron grade of the magnetically separated iron ore concentrate reaches 61.02%, the iron grade of the magnetically separated tailings is 8.6%, and the iron recovery rate reaches 98.3%.

[0131] Step S3, smelting reduction to extract iron: an electric furnace is used, and a flux (limestone) and a second reducing agent (coke) are added for smelting reduction. The flux rate is 10%, the second reducing agent rate is 5%, and when the molten slag temperature is controlled at 1550°C, the iron grade of the molten slag is 0.42%, and the metal Fe recovery rate is 96.5%.

[0132] Step S4, application of smelting tailings into building materials: quenching the molten slag with water and grinding it to obtain active micro powder.

[0133] Step S5, enriching the tailings with magnetic separation and then extracting aluminum: extracting aluminum from the tailings with magnetic separation.

[0134] The characteristic parameter test results of the magnetically separated iron concentrate, molten slag and pig iron prepared in the above examples are shown in Table 3, and the characteristic parameter test results of the active micropowder are shown in Table 4.

[0135] Test method:

[0136] Activity index test: refer to GB / T 18046-2017 Granulated blast furnace slag powder for cement, mortar and concrete for testing.

[0137] Table 3

[0138]

[0139] Table 4

[0140]

[0141] From the above, it can be seen that the present invention combines the characteristics of red mud components, aims at the recovery of valuable metal iron and aluminum resources, and the comprehensive utilization of all components of red mud, and proposes a technical scheme of "electromagnetic magnetization pre-reduction roasting treatment-magnetic separation enrichment of iron ore concentrate-molten reduction to extract iron-smelting tailings for building materials application-magnetic separation tailings enrichment and aluminum extraction" to achieve the purpose of large-scale disposal of red mud and comprehensive utilization of all components.

[0142] The processing method of the present invention has strong adaptability to red mud raw materials, is not limited to the range of iron content in red mud, and is applicable to both low-iron and high-iron red mud. The processing method of the present invention adopts an electromagnetic magnetization selective semi-melting method, and uses electromagnetic induction to selectively and efficiently heat the magnetic iron-containing particles, so that they are quickly melted, aggregated, and grown, providing process conditions for subsequent magnetic separation, which can greatly improve the iron grade of magnetic iron concentrate and reduce the iron content in magnetic separation tailings. After magnetization, the magnetism of elemental iron is improved, and the particle size is increased, which is conducive to separating magnetic elemental iron, thereby improving the economy of magnetic separation technology. In addition, in the magnetic separation tailings after iron separation, aluminum is enriched, which can be returned as an aluminum ore resource to extract aluminum metal again, thereby fully recovering the aluminum element.

[0143] In addition, the iron grade of magnetic iron concentrate is high. As the raw material for the molten reduction iron extraction process, it can improve the iron grade of pig iron and effectively improve the economic efficiency. The iron in the magnetic iron concentrate mainly exists in the form of elemental iron, which can effectively reduce the reducing agent rate, flux rate and smelting energy consumption in the molten reduction iron extraction process, improve the reaction efficiency of ironmaking, and reduce the amount of smelting slag. Moreover, the sodium content in the magnetic iron concentrate is relatively low, which can effectively solve the problem of raw material corrosion to refractory materials during the molten reduction process. Secondly, the molten slag obtained after molten reduction can be used as active micropowder for building materials after treatment, which effectively improves the performance of building materials and makes full use of magnetic tailings resources.

[0144] In summary, the treatment method of the present invention can effectively solve the problems in the prior art of complex red mud composition, poor economy, poor grade of red mud magnetic concentrate, low iron recovery rate, underutilized magnetic tailings resources, difficult operation of smelting ironmaking process and poor performance of slag as building materials, so that the iron and aluminum in the red mud can be fully recovered and utilized, and the economic benefits of red mud treatment can be significantly improved.

[0145] In addition, it can be seen that when all process parameters are within the preferred range of the present invention, the grade of magnetic concentrate is better, the iron recovery rate is higher, the building material performance of molten slag is better, and the magnetic tailings resources are more fully utilized.

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating red mud, characterized in that: The following steps are involved: Step S1, mixing the red mud with a first solid reducing agent to granulate to obtain pellets, performing a first roasting on the pellets at 700-1000° C., and performing electromagnetic induction treatment to obtain an electromagnetic magnetized product; or, performing a second roasting on the red mud at 500-800° C. in an atmosphere including a first gaseous reducing agent, and performing electromagnetic induction treatment to obtain an electromagnetic magnetized product; Step S2, performing magnetic separation on the electromagnetic magnetization product to obtain magnetically separated iron ore concentrate and magnetically separated tailings; Step S3, subjecting the magnetically separated iron concentrate to smelting reduction to obtain molten slag and pig iron; Step S4, quenching and grinding the molten slag to obtain active micropowder for building materials; Step S5, extracting aluminum from the magnetic separation tailings.

2. The processing method according to claim 1, characterized in that: In the step S1, The first solid reducing agent includes one or more of anthracite, coke and graphite; and / or, The molar ratio of the first solid reducing agent to the red mud is (15-35):

100.

3. The processing method according to claim 1, characterized in that: In the step S1, The first gaseous reducing agent includes one or more of carbon monoxide, hydrogen, water gas, ammonia and carbon dioxide; and / or, The molar ratio of the first gaseous reducing agent to the red mud is (20-40):

100.

4. The processing method according to claim 1 or 3, characterized in that: In the step S1, In the atmosphere, the volume percentage of the first gaseous reducing agent is 20-40%.

5. The processing method according to claim 1 or 2, characterized in that: In the step S1, The D50 of the pellets is 5 to 30 mm; and / or, Calculated by weight percentage, the moisture content of the pellets is less than 5%.

6. The processing method according to claim 1 or 2, characterized in that: In the step S1, The heating power of the electromagnetic induction is 5~25KW.

7. The processing method according to claim 1 or 2, characterized in that: In the step S1, The first calcination temperature is 750-850° C.; and / or, The first calcination time is 0.5-1.5h.

8. The processing method according to claim 1 or 3, characterized in that: In the step S1, The second calcination temperature is 650-700° C.; and / or, The second calcination time is 0.5 to 2 hours.

9. The processing method according to claim 1 or 2, characterized in that: In the step S1, The electromagnetic magnetization product includes an iron-containing phase, the iron-containing phase includes a magnetically selectable iron phase, and the weight percentage of the magnetically selectable iron phase in the iron-containing phase is ≥75%.

10. The processing method according to claim 1 or 2, characterized in that: In the step S2, The magnetic field strength of the magnetic separation is 2000~8000 Oersted.

11. The processing method according to claim 1 or 2, characterized in that: In the step S2, The magnetic separation is one-stage magnetic separation or two-stage magnetic separation, the one-stage magnetic separation is direct weak magnetic separation, and the two-stage magnetic separation includes strong magnetic separation and weak magnetic separation performed sequentially.

12. The processing method according to claim 1 or 2, characterized in that: In the step S2, The iron grade of the magnetically separated iron concentrate is greater than 60%, and the iron recovery rate is greater than 85%; and / or, The iron grade of the magnetic separation tailings is less than 10%; and / or, The weight percentage of aluminum in the magnetic separation tailings is 20-35%.

13. The processing method according to claim 1 or 2, characterized in that: In the step S3, A flux and a second reducing agent are added to carry out the molten reduction, the flux rate is 3-10%, and the second reducing agent rate is 5-8%.

14. The processing method according to claim 13, characterized in that: In the step S3, The second reducing agent comprises one or more of anthracite, coke, lignite and biomass; and / or, The temperature of the smelting reduction is 1450-1550°C.

15. The processing method according to claim 1 or 2, characterized in that: In the step S3, The molten slag is CaO-SiO2-Al2O3; and / or, The basicity of the molten slag is 1 to 1.2; and / or, The weight percentage of Al2O3 in the molten slag is 5-15%.

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