Method for extracting aluminum and co-producing iron ore concentrate from low-quality complex iron-aluminum symbiotic resources

Abstract

A method for extracting aluminum and co-producing iron ore concentrate from low-quality complex iron-aluminum symbiotic resources belongs to the technical field of metallurgy, and comprises the following steps: mechanically activating iron-aluminum symbiotic ore, a reducing agent, a calcium additive and a fluxing agent, uniformly mixing to prepare a raw material, and performing two-stage reduction sintering at the first-stage sintering temperature of 600-800 DEG C and the second-stage sintering temperature of 850-1100 DEG C; carrying out normal-pressure leaching after the reduction sintering product is finely ground, carrying out rapid liquid-solid separation on leached slurry to obtain a sodium aluminate solution, and carrying out normal-pressure desiliconization on the sodium aluminate solution to obtain a sodium aluminate refined solution; the sodium aluminate refined liquid is subjected to carbonation controlled decomposition to prepare high-whiteness aluminum hydroxide, decomposition mother liquid is blended and then returned to the technological process for reduction sintering product leaching, and leaching residues are subjected to low-intensity magnetic separation to obtain iron ore concentrate and magnetic separation tailings. According to the method, efficient and low-energy-consumption iron and aluminum recovery of iron and aluminum paragenic ore resources is achieved, the recovery rates of aluminum oxide and iron are both larger than or equal to 82%, the TFe content of iron ore concentrate is larger than or equal to 72%, and the Al2O3 content is smaller than or equal to 2.5%.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and particularly relates to a method for extracting aluminum from low-quality complex iron-aluminum symbiotic resources and co-producing iron concentrate. Background Art

[0002] The reserve levels of bauxite resources and iron ore resources in China are low, and they are mainly low-quality mineral resources, resulting in more than 60% of bauxite and more than 85% of iron ore relying on imports, seriously affecting the national resource security guarantee. However, China has rich reserves of iron-aluminum symbiotic resources. Only in Guangxi, the proven reserves of iron-aluminum symbiotic ore exceed 1 billion tons, and the predicted total resources are more than 3 billion tons. The contents of alumina and iron oxide reach more than 65% - 80%. However, due to the close embedding of iron compounds and aluminum-silicon minerals in the ore, there is a large amount of Al 3+ substituting for Fe 3+ isomorphic structure, resulting in a low degree of monomer dissociation, making the iron-aluminum symbiotic ore a typical refractory and stagnant ore in China. Therefore, there is an urgent need in this field for a method for efficient comprehensive utilization of aluminum extraction and iron separation from low-quality complex iron-aluminum symbiotic ore.

[0003] The early research on the comprehensive utilization of iron-aluminum symbiotic ore mainly focused on the technical route of "sintering - iron extraction by blast furnace smelting - aluminum extraction from calcium aluminate slag". In this process, the ore is evenly mixed with limestone, pulverized coal, and white lime in proportion and sintered to obtain sintered ore. The sintered ore is sent to a blast furnace for smelting with coke. In the blast furnace, the iron minerals are reduced to produce molten iron, and the aluminum minerals form calcium aluminate slag.

[0004] Patent CN103757165A fully mixes high-iron bauxite sintered ore and high-iron bauxite hot-pressed briquettes, and then alternately places them with coke in a blast furnace for smelting at 1450°C - 1600°C for 8 h - 10 h to obtain molten iron and slag; this process can obtain valuable metals such as iron, aluminum, vanadium, and gallium through blast furnace smelting, but the process flow is complex, the high-temperature smelting time is long, the production cost is high, the coke ratio is high, and it is difficult to apply in areas lacking coke.

[0005] Patent CN102605185A makes iron-aluminum symbiotic ore powder into pellets by adding water and then drying them. The pellets are placed in a reduction reaction for reduction at 850 - 1050°C and pulverized coal is sprayed in. Then, the reduced ore and lime are put into a reduction smelting furnace at 1450°C - 1650°C for reaction to obtain molten iron and aluminum-containing slag. This technology uses pulverized coal with a suitable price and wide application range, and the production cost is relatively low. The generated gas can be further recycled. However, the batching process belongs to wet batching, the drying process consumes a large amount of energy and prolongs the sintering cycle. Lime needs to be added twice during the high-temperature melting and separation process, and the operation process is complex. In addition, the obtained product is still molten iron, and it is restricted by the steel production capacity index.

[0006] The above patents have all achieved the efficient utilization of iron and aluminum resources from iron-aluminum symbiotic ores, but the melting and separation temperature has risen to about 1550 °C, resulting in high energy consumption. Although technically feasible, it is economically unreasonable and does not conform to the "dual carbon" green development concept. Summary of the Invention

[0007] To solve the above problems, the present invention proposes a method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources. The iron-aluminum symbiotic ore, reducing agent, calcium additive, and flux are uniformly mixed, and the reaction activity of the iron-aluminum symbiotic ore is enhanced through mechanical activation, enabling solid-phase reactions to occur at lower temperatures. Meanwhile, a flux is added to further reduce the sintering temperature, promote the formation of active calcium aluminate, and the directional reconstruction of the iron ore phase. The reduction process adopts a continuous two-stage reduction sintering to inhibit the generation of by-products during the sintering process, achieve cascaded energy utilization, and simplify the operation process.

[0008] A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources specifically includes the following steps:

[0009] (1) Mechanically activate the iron-aluminum symbiotic ore, reducing agent, calcium additive, and flux to obtain uniformly mixed raw materials for standby;

[0010] (2) Press the raw materials obtained in step (1) into pellets with a diameter of 1 cm to 3 cm, place them in a reduction sintering kiln for the first-stage reduction sintering. After the first-stage reduction sintering is completed, continue to heat up for the second-stage reduction sintering, and then cool with the furnace to obtain a reduction sintering product;

[0011] (3) Place the reduction sintering product into a ball mill or lattice mill, add sodium carbonate solution for atmospheric leaching while grinding, and perform rapid liquid-solid separation on the obtained leaching slurry to obtain sodium aluminate solution and leaching residue;

[0012] (4) Add lime milk slurry to the sodium aluminate solution for atmospheric desilication, and perform solid-liquid separation on the desilicated slurry to obtain a refined sodium aluminate solution;

[0013] (5) Perform carbonation decomposition on the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The decomposition mother liquor generated by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration, and the adjusted sodium carbonate solution is returned to step (3) for leaching the reduction sintering product;

[0014] (6) After formulating the leaching residue obtained in step (4) into a slurry, perform weak magnetic separation to obtain iron concentrate and magnetic separation tailings.

[0015] Among them:

[0016] In step (1), the chemical composition of the iron-aluminum symbiotic ore, calculated by mass fraction: Fe2O3 25% - 50%, Al2O3 25% - 50%, SiO2 5% - 25%, TiO2 1% - 3%.

[0017] In step (1), the reducing agent is one or a mixture of biomass, anthracite, lignite and long-flame coal. There is no proportion limit among multiple reducing agents. The molar ratio of the effective carbon content in the reducing agent to Fe2O3 in the iron-aluminum symbiotic ore is (0.8 - 1.3):1.

[0018] In step (1), the flux is a mixture of one or more of ammonium bisulfate, ammonium sulfate, potassium chlorate, fluorite, sodium fluoride, borax and lithium metaborate. There is no proportion limit among multiple fluxes. The addition amount is 3.0% - 8.0% of the mass of the iron-aluminum symbiotic ore powder.

[0019] In step (1), the calcium additive is a mixture of one or two of carbide slag, limestone and phosphorite. There is no proportion limit among multiple calcium additives. The molar ratio of the CaO content in the calcium additive to the contents of Al2O3, SiO2 and TiO2 in the iron-aluminum symbiotic ore is (3.8 - 5.1):1.

[0020] In step (1), the specific process of mechanical activation is as follows: The iron-aluminum symbiotic ore, reducing agent, calcium additive and flux are respectively crushed to a particle size ≤ 2 cm by a jaw crusher, and then ball milled by a high-energy ball mill. The ball milling rate is 400 rpm - 700 rpm, and the ball milling time is 30 min - 150 min. The particle size of the uniformly mixed raw material with a particle size ≤ 0.074 mm accounts for ≥ 90% of the total mass.

[0021] In step (2), the reduction sintering of the pellets is carried out in a muffle kiln or a two-stage rotary kiln. The first-stage reduction sintering is specifically as follows: The pellets are heated to 600°C - 800°C at a rate of 10°C / min and then subjected to the first-stage reduction sintering, and the sintering time is 1 h - 3 h.

[0022] In step (2), the second-stage reduction sintering of the pellets is specifically as follows: The pellets are heated to 850°C - 1100°C at a rate of 10°C / min and then subjected to the second-stage reduction sintering, and the sintering time is 0.5 h - 2 h. After the second-stage reduction sintering is completed, it is cooled in the furnace to below 400°C.

[0023] In step (2), the chemical reaction formula in the reduction sintering process is:

[0024] 12CaO + 7Al2O3 + X → 12CaO·7Al2O3 - X (X is boride, chloride, sulfate, fluoride);

[0025] 2CaO + SiO2 → 2CaO·SiO 2。

[0026] In step (3), the reduced sintered product is finely ground until the proportion of particles passing through a 100-mesh sieve accounts for ≥90% of the total mass, and the liquid-solid ratio of the sodium carbonate solution to the reduced sintered product is 2 L / kg - 5 L / kg; calculated by the content of Na2O C , the concentration of the sodium carbonate solution is 100 g / L - 160 g / L, the leaching temperature is 60°C - 80°C, and the leaching time is 60 min - 120 min.

[0027] In step (3), a settling tank, a filter press or a plate and frame filter press is used for the rapid liquid-solid separation of the leached slurry.

[0028] In step (3), the chemical reaction formula for the atmospheric pressure leaching process is:

[0029] Ca 12 Al 14 O 32 +12Na2CO3 + 4H2O → 14NaAlO2 + 12CaCO3 + 8NaOH.

[0030] In step (4), the mass concentration of the lime milk slurry is 100 g / L - 200 g / L, the CaO content in the lime milk slurry is 6 g / L - 14 g / L, the atmospheric pressure desilication temperature is 80°C - 110°C, the desilication time is 1 h - 3 h, the silicon modulus of the refined sodium aluminate solution obtained after desilication is ≥800, and the absorbance of the solution is <0.3.

[0031] In step (4), the chemical reaction formula for the atmospheric pressure desilication process is:

[0032] Ca(OH)2 + 2NaAl(OH)4 → 3CaO·Al2O3·6H2O + 2NaOH;

[0033] 3CaO·Al2O3·6H2O + xNa2SiO3 → 3CaO·Al2O3·xSiO2·(6 - 2m)H2O + 2xNaOH.

[0034] In step (5), the carbonation decomposition temperature of the refined sodium aluminate solution is 70°C - 100°C, the decomposition time is 3 h - 7 h, the CO2 ventilation rate is 1 L / min - 4 L / min, and the stirring speed is 400 r / min - 700 r / min.

[0035] In step (5), calculated by Na2O, the decomposition mother liquor produced by carbonation decomposition is supplemented with sodium carbonate and adjusted to a concentration of 100 g / L - 160 g / L, and then returned to step (3) for leaching of the reduced sintered product.

[0036] In the step (6), the process of preparing slurry from the leaching residue is as follows: hot water is added to the leaching residue, washed with water until the pH value of the washing liquid ≤ 9, and then formulated into a slurry with a mass concentration of 15% - 45%.

[0037] In the step (6), the low-intensity magnetic separation is carried out by one or multiple magnetic separations, and the magnetic field intensity is 1880 Oe - 3140 Oe.

[0038] In the iron concentrate obtained by the low-intensity magnetic separation, by mass percentage: TFe ≥ 72%, Al2O3 content ≤ 2.5%, and the recovery rates of alumina and iron in the iron concentrate both reach over 82%; the decomposition rate of the sodium aluminate refined solution ≥ 91%, the whiteness of the high-white aluminum hydroxide product is 95% - 98%, and the average particle size < 50 μm.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) The present invention uses mechanical activation to treat the mixed materials. During the mechanical activation process, the mixed materials are broken due to mechanical forces such as collision, friction, and extrusion, thereby reducing the particle diameter and apparent density, increasing the specific surface area of the particles, the defect concentration of aluminum minerals, and the degree of amorphization. At the same time, during the mechanical activation process, part of the mechanical energy is converted into activation energy, improving the reaction activity of the mixed raw meal, reducing the reaction thermal stability, accelerating the reaction process, adding a flux to increase the generation of liquid phase amount in the system, and reducing the formation temperature of calcium aluminate and magnetic iron ore phases.

[0041] (2) The method adopted by the present invention has a high iron-aluminum separation efficiency and high-quality products. Among them, the high-white aluminum hydroxide can be widely used in fields such as flame retardants, electronic appliances, and coatings. After the magnetic separation tailings are subjected to hydrothermal conversion or calcium extraction under normal pressure, they are used to prepare calcium-based / silica-based materials, and no solid waste is discharged, realizing the high-value and full-quantification utilization of iron-aluminum symbiotic ores. Brief Description of the Drawings

[0042] Figure 1 Process flow chart of a process for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources of the present invention. Detailed Embodiments

[0043] The following further elaborates the present invention through specific embodiments. These embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0044] The raw materials used in the embodiments of the present invention are iron-aluminum symbiotic ores, and the main chemical components include 25% - 50% of Fe2O3, 25% - 50% of Al2O3, 5% - 25% of SiO2, and 1% - 3% of TiO2.

[0045] In the embodiments of the present invention, the raw material crushing process uses a jaw crusher, and the grinding process uses a high-energy ball mill.

[0046] In the embodiment of the present invention, the carbon-alkali concentration (N C ) is the mass-volume concentration of Na2CO3 (calculated as Na2O), and the liquid-solid ratio (L / S) is the ratio of the volume of the leaching alkali solution to the mass of the clinker.

[0047] In the embodiment of the present invention, the reduction equipment adopts a two-stage rotary kiln.

[0048] In the embodiment of the present invention, the main components of the reduced sintered product are calcium aluminate, magnetic iron, calcium titanate, and calcium metasilicate.

[0049] In the embodiment of the present invention, rapid solid-liquid separation adopts a settling tank, a filter press, or a plate-and-frame filter press.

[0050] In the embodiment of the present invention, the main components of the leaching residue are magnetic iron, calcium metasilicate, and calcium carbonate.

[0051] In the embodiment of the present invention, the main components of the magnetic separation tailings are calcium metasilicate and calcium carbonate.

[0052] Example 1

[0053] In this example, Guigang iron-aluminum symbiotic ore is used, and its main chemical components (mass percentage, wt. / %) are: Fe2O3 43.21%, Al2O3 29.25%, SiO2 6.31%, and TiO2 1.67%, and the aluminum-silicon ratio is 4.64.

[0054] In this example, the calcareous additive is ordinary industrial-grade lime with a CaO content of 56% - 61%; the reducing agent is ordinary industrial-grade low-sulfur anthracite with an effective carbon content of 60% - 65% and a volatile content of 23% - 27%.

[0055] A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources, the process flow chart of which is as Figure 1 shown, specifically including the following steps:

[0056] (1) Mix the Guigang iron-aluminum symbiotic ore, anthracite, and fluorite evenly, and use a jaw crusher to crush them to a particle size of ≤2 cm respectively. Add limestone according to the ratio, mix evenly, and then use a high-energy ball mill for mechanical activation. The ball milling rate is 600 rpm, and the ball milling time is 120 min to obtain raw materials with a particle size of ≤0.074 mm accounting for ≥90% of the total mass for standby;

[0057] Among them, the molar ratio of the effective carbon content in anthracite to Fe2O3 in the iron-aluminum symbiotic ore is 1:1. The mass of fluorite added is 8% of the mass of the iron-aluminum symbiotic ore powder, the mass of lime added is 71% of the mass of the iron-aluminum symbiotic ore powder, the molar ratio of the CaO content in limestone to the Al2O3 content in the iron-aluminum symbiotic ore is CaO:Al2O3 = 1.7:1, and the molar ratio of the CaO content in lime to the SiO2 and TiO2 contents in the iron-aluminum symbiotic ore is CaO:(SiO2 + TiO2) = 3.0:1.

[0058] The function of adding the flux fluorite is as follows: to reduce the viscosity of the reduction materials and the formation temperature of the target mineral phase, to promote the formation of liquid phase, the occurrence of reduction sintering reaction and the reconstruction of low-temperature mineral phase during the reduction sintering process, and to realize the preliminary separation and enrichment of iron-aluminum resources.

[0059] (2) Press the green material obtained in step (1) into pellets with a diameter of 1 cm to 3 cm and send them into a two-stage rotary kiln. Heat it to 780 °C at a rate of 10 °C / min and then carry out the first-stage reduction sintering, with the sintering time being 2 h; after the end of the first-stage reduction sintering, raise the temperature to 1050 °C at a rate of 10 °C / min and then carry out the second-stage reduction sintering, with the sintering time being 1 h; after the end of the second-stage reduction sintering, cool it in the furnace to below 400 °C to obtain the reduction sintering product.

[0060] (3) Place the reduction sintering product into a ball mill, add sodium carbonate solution for atmospheric leaching while grinding, grind the reduction sintering product finely until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass, and the liquid-solid ratio of the sodium carbonate solution to the reduction sintering product is 3 L / kg; based on the Na2O C content, the concentration of the sodium carbonate solution is 120 g / L, control the leaching temperature at 80 °C, and the leaching time at 120 min. During the atmospheric leaching process, 12CaO·7Al2O3 in the reduction sintering product reacts with sodium carbonate to form NaAlO2 and CaCO3. NaAlO2 is easily soluble in the leaching solution to form a sodium aluminate solution, and insoluble phases such as CaCO3, magnetic iron ore phase and 2CaO·SiO2 form a solid slag phase.

[0061] The obtained leaching slurry is subjected to rapid liquid-solid separation by a filter press. The obtained liquid phase is a sodium aluminate solution, and the solid phase is the leaching residue, whose main chemical components are dicalcium silicate, magnetic iron, calcium titanate and calcium carbonate. The chemical reaction formula for the atmospheric leaching process is:

[0062] Ca 12 Al 14 O 32 + 12Na2CO3 + 4H2O → 14NaAlO2 + 12CaCO3 + 8NaOH.

[0063] (4) Add lime milk slurry with a mass concentration of 150 g / L to the sodium aluminate solution for atmospheric pressure desilication. The CaO content in the lime milk slurry is 11 g / L, the desilication temperature is 90 °C, and the desilication time is 3 h. After desilication, the slurry is subjected to solid-liquid separation to obtain a refined sodium aluminate solution. The silicon modulus of the refined sodium aluminate solution is 810, and the absorbance of the solution is 0.27.

[0064] During the atmospheric pressure desilication process, the lime milk slurry first reacts with the sodium aluminate solution to form water and tricalcium aluminate (3CaO·Al2O3·6H2O), and then water and tricalcium aluminate react with Na2SiO3 in the solution to form hydrogarnet.

[0065] Among them, the chemical reaction formula for the atmospheric pressure desilication process is:

[0066] Ca(OH)2 + 2NaAl(OH)4 → 3CaO·Al2O3·6H2O + 2NaOH;

[0067] 3CaO·Al2O3·6H2O + xNa2SiO3 → 3CaO·Al2O3·xSiO2·(6 - 2m)H2O + 2xNaOH.

[0068] (5) Carbonate decompose the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The carbonate decomposition temperature is 96 °C, the decomposition time is 6 h, the CO2 ventilation rate is 3.8 L / min, and the stirring speed is 650 r / min;

[0069] The decomposition mother liquor produced by carbonate decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 120 g / L (calculated as Na2O), and the adjusted sodium carbonate solution is returned to step (3) for leaching of the reduction sintering product.

[0070] (6) Add hot water to the leaching residue obtained in step (4), wash it until the pH value of the washing liquid ≤ 9, and prepare a slurry with a mass concentration of 35%. Through a drum magnetic separator, weakly magnetic separation is carried out on the leaching residue to achieve efficient separation and enrichment of iron concentrate and magnetic separation tailings. The magnetic field strength is 2800 Oe. Among them, the main components of the magnetic separation tailings are CaCO3 and 2CaO·SiO2, which can be used to prepare calcareous / siliceous materials.

[0071] In the obtained iron concentrate, by mass percentage: TFe is 72%, containing 2.4% Al2O3, the recovery rate of alumina in the iron concentrate is 82.9%, and the recovery rate of iron in the iron concentrate is 86%; the decomposition rate of the refined sodium aluminate solution is 92%, the whiteness of the high-whiteness aluminum hydroxide product is 97%, and the average particle size is 45 μm.

[0072] Example 2

[0073] In this embodiment, Guizhou iron-aluminum symbiotic ore is used, and its main chemical components (mass percentage, wt.%) are: Fe2O3 49.72%, Al2O3 31.65%, SiO2 5.87%, and TiO2 2.31%, and the aluminum-silicon ratio is 5.39.

[0074] In this embodiment, the calcium additive is ordinary industrial-grade phosphorite, and the CaO content is 83% - 86%; the reducing agent is ordinary industrial-grade lignite and biomass, and the effective carbon content of industrial-grade lignite is 62% - 70%, and the volatile content is 13% - 16%.

[0075] A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources specifically includes the following steps:

[0076] (1) Mix the Guizhou iron-aluminum symbiotic ore, lignite, biomass, and fluorite evenly, and use a jaw crusher to crush them to a particle size of ≤ 2 cm respectively. Add phosphorite according to the ratio, mix evenly, and then use a high-energy ball mill for ball milling. The ball milling rate is 700 rpm, and the ball milling time is 90 min to prepare raw materials with a particle size of ≤ 0.074 mm accounting for 93% of the total mass for standby;

[0077] Among them, the molar ratio of the effective carbon content of lignite to Fe2O3 in the iron-aluminum symbiotic ore is 1:1. The added mass of fluorite is 7% of the mass of the iron-aluminum symbiotic ore powder, the added mass of phosphorite is 71% of the mass of the iron-aluminum symbiotic ore powder, and the molar ratio of the CaO content of phosphorite to the contents of Al2O3, SiO2, and TiO2 in the iron-aluminum symbiotic ore is 4.6:1.

[0078] (2) Press the raw materials obtained in step (1) into pellets with a diameter of 1 cm - 3 cm and send them into a two-stage rotary kiln. Heat to 800°C at a rate of 10°C / min and then carry out the first-stage reduction sintering, and the sintering time is 2.5 h; after the first-stage reduction sintering is completed, heat to 1100°C at a rate of 10°C / min and then carry out the second-stage reduction sintering, and the sintering time is 2 h; after the second-stage reduction sintering is completed, cool with the furnace to below 400°C to obtain the reduction sintering product.

[0079] (3) Place the reduction sintering product into a ball mill, add sodium carbonate solution for atmospheric leaching while grinding, finely grind the reduction sintering product until the particle size passes through a 100-mesh sieve and accounts for ≥ 90% of the total mass. The liquid-solid ratio of the sodium carbonate solution to the reduction sintering product is 5 L / kg; based on the Na2O C content, the concentration of the sodium carbonate solution is 140 g / L. Control the leaching temperature at 75°C and the leaching time at 90 min. The obtained leaching slurry is subjected to rapid liquid-solid separation using a filter press. The obtained liquid phase is sodium aluminate solution, and the solid phase is leaching residue.

[0080] (4) Add lime milk slurry with a mass concentration of 170 g / L to the sodium aluminate solution for atmospheric pressure desilication. The CaO content in the lime milk slurry is 12 g / L, the desilication temperature is 95 °C, and the desilication time is 2.5 h. After desilication, the slurry is subjected to solid-liquid separation to obtain a refined sodium aluminate solution. The silicon modulus of the refined sodium aluminate solution is 803, and the absorbance of the solution is 0.28.

[0081] (5) Carbonate decompose the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The carbonate decomposition temperature is 98 °C, the decomposition time is 6.5 h, the CO2 ventilation rate is 4 L / min, and the stirring speed is 700 r / min;

[0082] The decomposition mother liquor produced by carbonate decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 120 g / L (calculated as Na2O), and the prepared sodium carbonate solution is returned to step (3) for leaching of the reduction sintering product.

[0083] (6) Add hot water to the leaching residue obtained in step (4), wash it until the pH value of the washing liquid ≤ 9, and prepare a slurry with a mass concentration of 30%. After weak magnetic separation, iron concentrate and magnetic separation tailings are obtained, and the magnetic field intensity is 3100 Oe.

[0084] In the obtained iron concentrate, by mass percentage: TFe is 73%, containing 2.1% of Al2O3, the recovery rate of alumina in the iron concentrate is 84.2%, and the recovery rate of iron in the iron concentrate is 88%; the decomposition rate of the refined sodium aluminate solution is 93%, the whiteness of the high-whiteness aluminum hydroxide product is 98%, and the average particle size is 46 μm.

[0085] Example 3

[0086] In this example, a Guangxi iron-aluminum symbiotic ore is used, and its main chemical components (mass percentage, wt. / %): Fe2O3 is 48.05%, Al2O3 is 32.66%, SiO2 is 8.31%, and TiO2 is 1.35%, and the aluminum-silicon ratio is 3.93.

[0087] In this example, the calcium additive is selected as ordinary industrial grade carbide slag, and the CaO content is 65% - 72%; the reducing agent is selected as ordinary industrial grade low-sulfur anthracite coal powder, and the effective carbon content of industrial grade anthracite is 60% - 63%, and the volatile content is 25% - 29%.

[0088] A method for extracting aluminum from low-quality complex iron-aluminum symbiotic resources and co-producing iron concentrate specifically includes the following steps:

[0089] (1)Mix the iron-aluminum symbiotic ore in Guangxi, anthracite, and fluorite evenly, and use a jaw crusher to crush them to a particle size of ≤2 cm respectively. Add carbide slag according to the proportion, mix evenly, and then use a high-energy ball mill for ball milling. The ball milling rate is 600 rpm, and the ball milling time is 120 min to prepare raw materials with a particle size of ≤0.074 mm accounting for 90% of the total mass for standby.

[0090] Among them, the molar ratio of the effective carbon content in anthracite to Fe2O3 in the iron-aluminum symbiotic ore is 1.3:1. The added mass of fluorite is 7.5% of the mass of the iron-aluminum symbiotic ore powder. The added mass of carbide slag is 71% of the mass of the iron-aluminum symbiotic ore powder. The molar ratio of the CaO content in carbide slag to the Al2O3 content in the iron-aluminum symbiotic ore is CaO:Al2O3 = 1.6:1. The molar ratio of the CaO content in carbide slag to the SiO2 and TiO2 contents in the iron-aluminum symbiotic ore is CaO:(SiO2 + TiO2) = 3.0:1.

[0091] (2)Press the raw materials obtained in step (1) into pellets with a diameter of 1 cm - 3 cm and send them into a two-stage rotary kiln. Heat them to 770℃ at a rate of 10℃ / min and then carry out the first-stage reduction sintering. The sintering time is 1.5 h. After the first-stage reduction sintering is completed, heat it to 1080℃ at a rate of 10℃ / min and then carry out the second-stage reduction sintering. The sintering time is 1.5 h. After the second-stage reduction sintering is completed, cool it in the furnace to below 400℃ to obtain the reduction sintering product.

[0092] (3)Place the reduction sintering product into a ball mill, add sodium carbonate solution for atmospheric leaching while grinding. Grind the reduction sintering product finely until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass. The liquid-solid ratio of the sodium carbonate solution to the reduction sintering product is 5 L / kg. Calculated by the Na2O C content, the concentration of the sodium carbonate solution is 130 g / L. Control the leaching temperature at 78℃ and the leaching time at 100 min. The obtained leaching slurry is quickly separated by a filter press. The obtained liquid phase is sodium aluminate solution, and the solid phase is leaching residue.

[0093] (4)Add lime milk slurry with a mass concentration of 160 g / L to the sodium aluminate solution for atmospheric desilication. The CaO content in the lime milk slurry is 13 g / L. The desilication temperature is 105℃ and the desilication time is 2.7 h. After desilication, the slurry is separated by solid-liquid separation to obtain a refined sodium aluminate solution. The silicon modulus of the refined sodium aluminate solution is 810, and the absorbance of the solution is 0.27.

[0094] (5)Carry out carbonation decomposition on the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The carbonation decomposition temperature is 93℃, the decomposition time is 5.8 h, the CO2 ventilation rate is 3.5 L / min, and the stirring speed is 690 r / min;

[0095] The decomposition mother liquor produced by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 145 g / L (calculated as Na2O), and the prepared sodium carbonate solution is returned to step (3) for leaching the reduction sintering product.

[0096] (6) Add hot water to the leaching residue obtained in step (4), wash it until the pH value of the washing liquid ≤ 9, and prepare a pulp with a mass concentration of 42%. After weak magnetic separation, iron concentrate and magnetic separation tailings are obtained, and the magnetic field intensity is 3000 Oe.

[0097] In the obtained iron concentrate, by mass percentage: TFe is 74.2%, containing 2.32% of Al2O3. The recovery rate of alumina in the iron concentrate is 82.8%, and the recovery rate of iron in the iron concentrate is 83.76%; the decomposition rate of the sodium aluminate refining solution is 92.86%, the whiteness of the high-white aluminum hydroxide product is 96%, and the average particle size is 47.5 μm.

[0098] Example 4

[0099] In this example, the Guangxi iron-aluminum symbiotic ore is used, and its main chemical components (mass percentage, wt. / %): Fe2O3 is 43.56%, Al2O3 is 35.76%, SiO2 is 8.58%, and TiO2 is 2.76%, and the aluminum-silicon ratio is 4.16.

[0100] In this example, the calcium additive is selected as ordinary industrial-grade limestone, and the CaO content is 72% - 79%; the reducing agent is selected as ordinary industrial-grade long-flame coal, and the effective carbon content of the industrial-grade long-flame coal is 76% - 82%, and the volatile content is 28% - 36%.

[0101] A method for extracting aluminum from low-quality complex iron-aluminum symbiotic resources and co-producing iron concentrate specifically includes the following steps:

[0102] (1) Mix the Guangxi iron-aluminum symbiotic ore, long-flame coal, and fluorite evenly, and use a jaw crusher to crush them to a particle size ≤ 2 cm respectively. Add limestone according to the proportion, mix evenly, and then use a high-energy ball mill for ball milling. The ball milling rate is 640 rpm, and the ball milling time is 110 min to prepare raw materials with a particle size ≤ 0.074 mm accounting for 91% of the total mass for standby;

[0103] Among them, the molar ratio of the effective carbon content of the long-flame coal to Fe2O3 in the iron-aluminum symbiotic ore is 0.9:1, the added mass of fluorite is 6.5% of the mass of the iron-aluminum symbiotic ore powder, the added mass of limestone is 72% of the mass of the iron-aluminum symbiotic ore powder, and the molar ratio of the CaO content of the limestone to the contents of Al2O3, SiO2, and TiO2 in the iron-aluminum symbiotic ore is 4.6:1.

[0104] (2)Press the green meal obtained in step (1) into pellets with a diameter of 1 cm to 3 cm and feed them into a two-stage rotary kiln. Heat it to 700 °C at a rate of 10 °C / min and then carry out the first-stage reduction sintering for 3 h. After the first-stage reduction sintering is completed, heat it to 1080 °C at a rate of 10 °C / min and then carry out the second-stage reduction sintering for 1.5 h. After the second-stage reduction sintering is completed, cool it in the furnace to below 400 °C to obtain the reduction sintering product.

[0105] (3)Place the reduction sintering product into a ball mill, add sodium carbonate solution and carry out leaching under atmospheric pressure while grinding. Grind the reduction sintering product finely until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass. The liquid-solid ratio of the sodium carbonate solution to the reduction sintering product is 4.5 L / kg. Calculated by the content of Na2O C the concentration of the sodium carbonate solution is 160 g / L. Control the leaching temperature at 80 °C and the leaching time at 100 min. The obtained leaching slurry is subjected to rapid liquid-solid separation by a filter press. The obtained liquid phase is sodium aluminate solution and the solid phase is leaching residue.

[0106] (4)Add lime milk slurry with a mass concentration of 190 g / L to the sodium aluminate solution for desilication under atmospheric pressure. The content of CaO in the lime milk slurry is 14 g / L. The desilication temperature is 110 °C and the desilication time is 2.4 h. After desilication, the slurry is subjected to solid-liquid separation to obtain a refined sodium aluminate solution. The silicon modulus of the refined sodium aluminate solution is 815 and the absorbance of the solution is 0.26.

[0107] (5)Carry out carbonation decomposition on the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The carbonation decomposition temperature is 97 °C, the decomposition time is 6.8 h, the CO2 ventilation rate is 3.8 L / min, and the stirring speed is 650 r / min;

[0108] The decomposition mother liquor generated by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 150 g / L (calculated by Na2O), and the prepared sodium carbonate solution is returned to step (3) for leaching of the reduction sintering product.

[0109] (6)Add hot water to the leaching residue obtained in step (4), wash it until the pH value of the washing liquid ≤9, and prepare it into a slurry with a mass concentration of 35%. Carry out weak magnetic separation to obtain iron concentrate and magnetic separation tailings, and the magnetic field intensity is 3050 Oe.

[0110] In the obtained iron concentrate, by mass percentage: TFe is 74.3%, containing 2.26% of Al2O3. The recovery rate of alumina in the iron concentrate is 84.14%, and the recovery rate of iron in the iron concentrate is 82.57%; the decomposition rate of the refined sodium aluminate solution is 91.5%, the whiteness of the high-whiteness aluminum hydroxide product is 97%, and the average particle size is 44.5 μm.

[0111] Example 5

[0112] In this embodiment, the iron-aluminum symbiotic ore from Chongzuo, Guangxi is adopted, and its main chemical components (mass percentage, wt.%) are: Fe2O3 46.11%, Al2O3 29.65%, SiO2 11.23%, and TiO2 2.12%, and the aluminum-silicon ratio is 2.64.

[0113] In this embodiment, the calcium additive is ordinary industrial-grade limestone with a CaO content of 73% - 82%; the reducing agent is ordinary industrial-grade lignite, and the effective carbon content of industrial-grade lignite is 60% - 72%, and the volatile content is 29% - 35%.

[0114] A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources specifically includes the following steps:

[0115] (1) Mix the iron-aluminum symbiotic ore from Chongzuo, lignite, and fluorite evenly, and use a jaw crusher to crush them to a particle size of ≤2 cm respectively. Add limestone according to the ratio, mix evenly, and then use a high-energy ball mill for ball milling. The ball milling rate is 630 rpm, and the ball milling time is 110 min to prepare raw materials with a particle size of ≤0.074 mm accounting for 93% of the total mass for standby;

[0116] Among them, the molar ratio of the effective carbon content in lignite to Fe2O3 is 1.2:1, the added mass of fluorite is 7.8% of the mass of the iron-aluminum symbiotic ore powder, the added mass of limestone is 71% of the mass of the iron-aluminum symbiotic ore powder, the molar ratio of the CaO content in limestone to the Al2O3 content in the iron-aluminum symbiotic ore is CaO:Al2O3 = 1.6:1, and the molar ratio of the CaO content in lime to the SiO2 and TiO2 contents in the iron-aluminum symbiotic ore is CaO:(SiO2 + TiO2) = 3.1:1.

[0117] (2) Press the raw materials obtained in step (1) into pellets with a diameter of 1 cm - 3 cm and send them into a two-stage rotary kiln. Heat them to 780°C at a rate of 10°C / min and then conduct the first-stage reduction sintering, and the sintering time is 2.7 h; after the end of the first-stage reduction sintering, heat it to 1050°C at a rate of 10°C / min and then conduct the second-stage reduction sintering, and the sintering time is 2 h; after the end of the second-stage reduction sintering, cool it in the furnace to below 400°C to obtain the reduction sintering product.

[0118] (3) Place the reduction sintering product into a ball mill, add sodium carbonate solution for atmospheric leaching while grinding, finely grind the reduction sintering product until the particle size passes through a 100-mesh sieve and accounts for 92% of the total mass, and the liquid-solid ratio of the sodium carbonate solution to the reduction sintering product is 4.5 L / kg; with Na2O CA content meter, the concentration of the sodium carbonate solution is 135 g / L, the leaching temperature is controlled at 75 °C, the leaching time is 100 min, and the obtained leached slurry is subjected to rapid liquid-solid separation by a filter press. The obtained liquid phase is a sodium aluminate solution, and the solid phase is a leaching residue.

[0119] (4) Add lime milk slurry with a mass concentration of 180 g / L to the sodium aluminate solution for atmospheric pressure desilication. The CaO content in the lime milk slurry is 13 g / L, the desilication temperature is 110 °C, the desilication time is 2 h. After desilication, the slurry is subjected to solid-liquid separation to obtain a refined sodium aluminate solution. The silicon modulus of the refined sodium aluminate solution is 820, and the absorbance of the solution is 0.25.

[0120] (5) Carbonate decompose the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The carbonate decomposition temperature is 97 °C, the decomposition time is 6.5 h, the CO2 ventilation rate is 3.2 L / min, and the stirring speed is 610 r / min;

[0121] The decomposition mother liquor generated by carbonate decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 120 g / L (calculated as Na2O), and the prepared sodium carbonate solution is returned to step (3) for leaching of the reduction sintering product.

[0122] (6) Add hot water to the leaching residue obtained in step (4), wash it until the pH value of the washing liquid ≤ 9, and prepare a slurry with a mass concentration of 30%. After weak magnetic separation, iron concentrate and magnetic separation tailings are obtained, and the magnetic field intensity is 3120 Oe.

[0123] In the obtained iron concentrate, by mass percentage: TFe 76.3%, containing Al2O3 1.97%, the recovery rate of alumina in the iron concentrate is 85.52%, and the recovery rate of iron in the iron concentrate is 82.85%; the decomposition rate of the refined sodium aluminate solution is 93%, the whiteness of the high-whiteness aluminum hydroxide product is 96%, and the average particle size is 44.8 μm.

[0124] Example 6

[0125] In this example, the Guangxi Pingguo iron-aluminum symbiotic ore is used, and its main chemical components (mass percentage, wt. / %): Fe2O3 36.77%, Al2O3 46.83%, SiO2 13.06%, and TiO2 1.94%, and the aluminum-silicon ratio is 3.59.

[0126] In this example, the calcium additive is selected as ordinary industrial grade carbide slag, and the CaO content is 68% - 72%; the reducing agent is selected as ordinary industrial grade lignite, and the effective carbon content of the industrial grade lignite is 67% - 75%, and the volatile content is 21% - 26%.

[0127] A method for extracting aluminum from low-quality complex iron-aluminum symbiotic resources and co-producing iron concentrate specifically includes the following steps:

[0128] (1) Mix the bauxite-iron symbiotic ore, lignite, and fluorite evenly, and use a jaw crusher to crush them to a particle size of ≤2 cm respectively. Add carbide slag according to the proportion, mix evenly, and then use a high-energy ball mill for ball milling. The ball milling rate is 700 rpm, and the ball milling time is 150 min to prepare raw materials with a particle size of ≤0.074 mm accounting for 95% of the total mass for standby;

[0129] Among them, the molar ratio of the effective carbon content in lignite to Fe2O3 is 1:1. The added mass of fluorite is 8% of the mass of the bauxite-iron symbiotic ore powder. The added mass of carbide slag is 70% of the mass of the bauxite-iron symbiotic ore powder. The molar ratio of the CaO content in carbide slag to the Al2O3 content in the bauxite-iron symbiotic ore is CaO:Al2O3 = 1.6:1. The molar ratio of the CaO content in carbide slag to the SiO2 and TiO2 contents in the bauxite-iron symbiotic ore is CaO:(SiO2 + TiO2) = 3.0:1.

[0130] (2) Press the raw materials obtained in step (1) into pellets with a diameter of 1 cm - 3 cm and send them into a two-stage rotary kiln. Heat them to 800 °C at a rate of 10 °C / min and then carry out the first-stage reduction sintering. The sintering time is 2.5 h; after the first-stage reduction sintering is completed, raise the temperature to 1000 °C at a rate of 10 °C / min and then carry out the second-stage reduction sintering. The sintering time is 2 h; after the second-stage reduction sintering is completed, cool it in the furnace to below 400 °C to obtain the reduction sintering product.

[0131] (3) Place the reduction sintering product into a ball mill, add sodium carbonate solution for atmospheric leaching while grinding. Grind the reduction sintering product finely until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass. The liquid-solid ratio of the sodium carbonate solution to the reduction sintering product is 4.7 L / kg; in terms of the Na2O C content, the concentration of the sodium carbonate solution is 160 g / L. Control the leaching temperature at 80 °C and the leaching time at 110 min. The obtained leaching slurry is subjected to rapid liquid-solid separation using a filter press. The obtained liquid phase is sodium aluminate solution, and the solid phase is leaching residue.

[0132] (4) The mass concentration of the lime milk slurry is 180 g / L. Add lime milk slurry with a CaO content of 13 g / L to the sodium aluminate solution for atmospheric desilication. The desilication temperature is 105 °C, and the desilication time is 3 h. After desilication, the slurry is subjected to solid-liquid separation to obtain a refined sodium aluminate solution. The silicon modulus of the refined sodium aluminate solution is 810, and the solution absorbance is 0.28.

[0133] (5) Carry out carbonation decomposition on the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The carbonation decomposition temperature is 99 °C, the decomposition time is 7 h, the CO2 ventilation rate is 4 L / min, and the stirring speed is 700 r / min;

[0134] The decomposition mother liquor generated by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 125 g / L (calculated as Na2O), and the prepared sodium carbonate solution is returned to step (3) for leaching of the reduction sintering product.

[0135] (6) Add hot water to the leaching residue obtained in step (4), wash it until the pH value of the washing liquid ≤ 9, and prepare it into a pulp with a mass concentration of 38%. After weak magnetic separation, iron concentrate and magnetic separation tailings are obtained, and the magnetic field intensity is 3140 Oe.

[0136] In the obtained iron concentrate, by mass percentage: TFe is 73.5%, containing 2.08% of Al2O3. The recovery rate of alumina in the iron concentrate is 85.83%, and the recovery rate of iron in the iron concentrate is 84.79%; the decomposition rate of the sodium aluminate refined solution is 92.5%, the whiteness of the high-white aluminum hydroxide product is 97%, and the average particle size is 48.7 μm.

Claims

1. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources, characterized in that, Specifically, it includes the following steps: (1) Mechanically activate the iron-aluminum symbiotic ore, reducing agent, calcium additive and flux to obtain uniformly mixed raw materials for standby; (2) Press the raw materials obtained in step (1) into pellets with a diameter of 1 cm to 3 cm, place them in a reduction sintering kiln for the first-stage reduction sintering. After the first-stage reduction sintering is completed, continue to heat up for the second-stage reduction sintering, and then cool with the furnace to obtain a reduction sintering product; (3) Put the reduction sintering product into a ball mill or lattice mill, add sodium carbonate solution for atmospheric leaching while grinding, and quickly separate the liquid and solid of the obtained leaching slurry to obtain sodium aluminate solution and leaching residue; (4) Add lime milk slurry to the sodium aluminate solution for atmospheric desilication, and separate the solid and liquid of the desilicated slurry to obtain a refined sodium aluminate solution; (5) Carry out carbonation decomposition on the refined sodium aluminate solution to obtain high-whiteness aluminum hydroxide. The decomposition mother liquor generated by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration, and the adjusted sodium carbonate solution is returned to step (3) for leaching the reduction sintering product; (6) After formulating the leaching residue obtained in step (4) into a slurry, carry out weak magnetic separation to obtain iron concentrate and magnetic separation tailings.

2. The method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that, In step (1), the chemical composition of the iron-aluminum symbiotic ore is by mass fraction: Fe2O3 25% - 50%, Al2O3 25% - 50%, SiO2 5% - 25%, TiO2 1% - 3%; The reducing agent is a mixture of one or more of biomass, anthracite, lignite and long-flame coal. There is no proportion limit between multiple reducing agents. The molar ratio of the effective carbon content in the reducing agent to Fe2O3 in the iron-aluminum symbiotic ore is (0.8 - 1.3):1; The flux is a mixture of one or more of ammonium bisulfate, ammonium sulfate, potassium chlorate, fluorite, sodium fluoride, borax and lithium metaborate. There is no proportion limit between multiple fluxes, and the addition amount is 3.0% - 8.0% of the mass of the iron-aluminum symbiotic ore powder; The calcium additive is a mixture of one or two of carbide slag, limestone and phosphorite. There is no proportion limit between multiple calcium additives. The molar ratio of the CaO content in the calcium additive to the contents of Al2O3, SiO2 and TiO2 in the iron-aluminum symbiotic ore is (3.8 - 5.1):

1.

3. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that, In step (1), the specific process of mechanical activation is as follows: Crush the iron-aluminum symbiotic ore, reducing agent, calcium additive and flux to a particle size ≤ 2 cm respectively by a jaw crusher, and then carry out ball milling by a high-energy ball mill. The ball milling rate is 400 rpm - 700 rpm, and the ball milling time is 30 min - 150 min. The particle size of the obtained uniformly mixed raw material with a particle size ≤ 0.074 mm accounts for ≥ 90% of the total mass.

4. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that In step (2), the reduction sintering of the pellets is carried out in a muffle kiln or a two-stage rotary kiln. The first-stage reduction sintering is specifically: Heat the pellets at 10°C / min to 600°C - 800°C and then carry out the first-stage reduction sintering, and the sintering time is 1 h - 3 h.

5. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that, In the step (2), the second-stage reduction sintering of the pellet is specifically as follows: the pellet is heated to 850°C - 1100°C at a rate of 10°C / min and then undergoes second-stage reduction sintering. The sintering time is 0.5 h - 2 h. After the second-stage reduction sintering is completed, it is cooled in the furnace to below 400°C.

6. The method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, wherein, In the step (3), the reduced sintered product is finely ground until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass, and the liquid-solid ratio of the sodium carbonate solution to the reduced sintered product is 2 L / kg to 5 L / kg; based on the content of Na2O C the concentration of the sodium carbonate solution is 100 g / L to 160 g / L, the leaching temperature is 60°C to 80°C, and the leaching time is 60 min to 120 min; The liquid-solid rapid separation process of the leaching slurry uses a settling tank, a filter press or a plate filter press.

7. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that, In the step (4), the mass concentration of the lime milk slurry is 100 g / L - 200 g / L, the CaO content in the lime milk slurry is 6 g / L - 14 g / L, the atmospheric pressure desilication temperature is 80°C - 110°C, the desilication time is 1 h - 3 h, the silicon modulus of the refined sodium aluminate solution obtained after desilication is ≥800, and the solution absorbance is <0.

3.

8. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that In the step (5), the carbonation decomposition temperature of the refined sodium aluminate solution is 70°C - 100°C, the decomposition time is 3 h - 7 h, the CO2 ventilation rate is 1 L / min - 4 L / min, and the stirring speed is 400 r / min - 700 r / min; calculated by Na2O, the decomposition mother liquor generated by carbonation decomposition is supplemented with sodium carbonate and formulated to a concentration of 100 g / L - 160 g / L, and then returned to the step (3) for leaching of the reduction sintering product.

9. A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that In the step (6), the process of preparing the slurry from the leaching residue is as follows: hot water is added to the leaching residue, washed until the pH value of the washing liquid is ≤9, and then formulated into a slurry with a mass concentration of 15% - 45%. The weak magnetic separation is single or multiple magnetic separations, and the magnetic field intensity is 1880 Oe - 3140 Oe.

10. The method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to claim 1, characterized in that, In the iron concentrate obtained by the weak magnetic separation, by mass percentage: TFe≥72%, Al2O3 content ≤2.5%, and the recovery rates of alumina and iron in the iron concentrate both reach over 82%; the decomposition rate of the refined sodium aluminate solution is ≥91%, the whiteness of the high-white aluminum hydroxide product is 95% - 98%, and the average particle size is <50 μm.

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