A method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources

Abstract

A method for extracting aluminum and producing iron concentrate from low-quality, complex iron-aluminum paragenetic resources belongs to the field of metallurgy technology. The method comprises the following steps: mechanically activating the iron-aluminum paragenetic ore, a reducing agent, a calcium additive, and a flux, then uniformly mixing them to form a raw meal; then employing a two-stage reduction sintering process, with the first stage sintering at a temperature of 600°C to 800°C and the second stage sintering at a temperature of 850°C to 1100°C; finely grinding the reduction sintered product and subjecting it to atmospheric leaching; rapidly separating the leached slurry into a sodium aluminate solution; and desiliconizing the sodium aluminate solution under atmospheric pressure to obtain a refined sodium aluminate solution; then subjecting the refined sodium aluminate solution to controlled carbonation and decomposition to produce high-white aluminum hydroxide. The decomposed mother liquor is then returned to the process flow for leaching the reduction sintered product, and the leached residue is subjected to weak magnetic separation to obtain an iron concentrate and magnetic separation tailings. The method achieves efficient and low-energy recovery of iron and aluminum from iron-aluminum paragenetic ore resources, achieving aluminum oxide and iron recovery rates of ≥82%, a TFe content of ≥72%, and an Al2O3 content of ≤2.5% in the iron concentrate.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources. Background Art

[0002] There is an urgent need in this field for a method to efficiently extract aluminum and beneficiate iron from low-quality, complex iron-aluminum symbiotic ores for comprehensive utilization.

[0003] Early research on the comprehensive utilization of iron-aluminum symbiotic ores mainly focused on the technical route of "sintering-blast furnace smelting for iron extraction-calcium aluminate slag extraction". This process involves mixing the ore with limestone, coal powder and quicklime in a certain proportion, sintering it to obtain sintered ore, and then feeding the sintered ore into a blast furnace for smelting with coke. In the blast furnace, the iron minerals are reduced to produce molten iron, and the aluminum minerals are converted into calcium aluminate slag.

[0004] Patent CN103757165A describes a process where sintered high-iron bauxite and hot-pressed high-iron bauxite are thoroughly mixed and then alternately placed with coke in a blast furnace for 8 to 10 hours at 1450°C to 1600°C to obtain molten iron and slag. This process can produce valuable metals such as iron, aluminum, vanadium, and gallium through blast furnace smelting. However, the process is complex, involves long high-temperature smelting time, and has high production costs and a high coke ratio, making it difficult to apply in areas where coke is scarce.

[0005] Patent CN102605185A describes a process where iron-aluminum symbiotic ore powder is mixed with water to form pellets, which are then dried. The pellets are placed in a reduction reaction at 850-1050℃ and pulverized coal is injected. The reduced ore and lime are then reacted in a reduction melting furnace at 1450-1650℃ to obtain molten iron and aluminum-containing slag. This technology uses reasonably priced and widely applicable pulverized coal, resulting in low production costs, and the generated gas can be further recycled. However, the batching process is wet, the drying process consumes a large amount of energy and prolongs the sintering cycle, and lime needs to be added a second time during the high-temperature melting and separation process, making the operation complex. Furthermore, the resulting product is still molten iron, and it is subject to steel production capacity limits.

[0006] The aforementioned patents all achieve efficient utilization of iron and aluminum resources in the recovery of iron-aluminum symbiotic ores, but the melting and separation temperature has risen to about 1550℃, resulting in high energy consumption. While technically feasible, they are economically unreasonable and do not conform to the "dual-carbon" green development concept. Summary of the Invention

[0007] To address the aforementioned problems, this invention proposes a method for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources. The method involves uniformly mixing the iron-aluminum symbiotic ore, reducing agent, calcium additive, and flux. Mechanical activation enhances the reactivity of the iron-aluminum symbiotic ore, allowing the solid-phase reaction to occur at a lower temperature. Simultaneously, the addition of flux further reduces the sintering temperature, promotes the formation of active calcium aluminate, and facilitates the directional reconstruction of the iron phase. The reduction process employs a continuous two-stage reduction sintering method, suppressing the generation of byproducts during sintering, achieving energy cascade utilization, and simplifying 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 a uniformly mixed raw material for later use;

[0010] (2) Press the raw material 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 of reduction sintering, and after the first stage of reduction sintering is completed, continue to heat up for the second stage of reduction sintering, and then cool with the furnace to obtain the reduction sintering product.

[0011] (3) Place the reduction sintering product into a ball mill or grid mill, add sodium carbonate solution and leach at normal pressure while grinding and leaching. The resulting leach slurry is subjected to rapid liquid-solid separation to obtain sodium aluminate solution and leaching residue.

[0012] (4) After adding lime slurry to sodium aluminate solution, desilication is carried out under normal pressure. After desilication, the slurry is separated into solid and liquid to obtain a refined sodium aluminate solution.

[0013] (5) The refined sodium aluminate solution is carbonated and decomposed to obtain high white aluminum hydroxide. The decomposition mother liquor produced by carbonation and decomposition is further supplemented with sodium carbonate to adjust the solution concentration. The adjusted sodium carbonate solution is returned to step (3) for leaching of reduction sintering products.

[0014] (6) After preparing the leaching residue obtained in step (4) into a slurry, iron concentrate and magnetic separation tailings are obtained by weak magnetic separation.

[0015] in:

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

[0017] In step (1), the reducing agent is a mixture of one or more substances selected from biomass, anthracite, lignite and long-flame coal. There is no limit to the proportion between the various 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 one or a mixture of ammonium bisulfate, ammonium sulfate, potassium chlorate, fluorite, sodium fluoride, borax and lithium metaborate. There is no limit to the proportion between the various fluxes, and the amount added is 3.0% to 8.0% of the mass of the iron-aluminum symbiotic mineral powder.

[0019] In step (1), the calcium additive is one or a mixture of two of carbide slag, limestone and phosphate lime. There is no limit to the proportion between the various calcium additives. The molar ratio of CaO content in the calcium additive to Al2O3, SiO2 and TiO2 content 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 crushed to a particle size ≤2 cm by a jaw crusher, and then ball milled by a high-energy ball mill at a ball milling rate of 400 rpm to 700 rpm and a ball milling time of 30 min to 150 min. The resulting 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 flame-insulating kiln or a two-stage rotary kiln. The first stage of reduction sintering is specifically carried out by heating the pellets to 600℃~800℃ at 10℃ / min and then performing the first stage of reduction sintering for 1 h~3 h.

[0022] In step (2), the second stage of reduction sintering of the pellets is specifically as follows: the pellets are heated to 850℃~1100℃ at 10℃ / min and then subjected to the second stage of reduction sintering for 0.5 h~2 h. After the second stage of reduction sintering is completed, the pellets are cooled to below 400℃ in the furnace.

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

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

[0025] 2CaO + SiO₂ → 2CaO·SiO 2。

[0026] In step (3), the reduced sintering product is finely ground until the particle size passes through a 100-mesh sieve, accounting for ≥90% of the total mass. The liquid-to-solid ratio of sodium carbonate solution to reduced sintering product is 2 L / kg~5 L / kg. Na2O is used as the solvent. CBased on content, the concentration of sodium carbonate solution is 100 g / L~160 g / L, the leaching temperature is 60℃~80℃, and the leaching time is 60 min~120 min.

[0027] In step (3), the liquid-solid rapid separation process of the leachate slurry is carried out using a settling tank, a filter, or a filter press.

[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 lime slurry is 100 g / L to 200 g / L, the CaO content in lime slurry is 6 g / L to 14 g / L, the desilication temperature under normal pressure is 80℃ to 110℃, the desilication time is 1 h to 3 h, and the silicon index 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℃~100℃, the decomposition time is 3h~7h, the CO2 aeration rate is 1 L / min~4 L / min, and the stirring speed is 400 r / min~700 r / min.

[0035] In step (5), based on Na2O, the mother liquor produced by carbonation decomposition is supplemented with sodium carbonate to adjust the concentration to 100 g / L~160 g / L, and then returned to step (3) for leaching of reduction sintering products.

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

[0037] In step (6), the weak magnetic separation is performed once or multiple times, and the magnetic field strength is 1880 Oe~3140 Oe.

[0038] The iron concentrate obtained by the weak magnetic separation has the following composition by mass percentage: TFe≥72%, Al2O3≤2.5%, and the recovery rates of alumina and iron in the iron concentrate are both above 82%; the decomposition rate of the sodium aluminate refining solution is ≥91%, the whiteness of the high white aluminum hydroxide product is 95%~98%, and the average particle size is <50 μm.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) This invention utilizes mechanical activation to treat the mixture. During the mechanical activation process, the mixture is subjected to mechanical forces such as collision, friction, and extrusion, resulting in particle breakage, thereby reducing particle diameter and apparent density, increasing particle specific surface area, aluminum mineral defect concentration, and amorphization degree. At the same time, during the mechanical activation process, some mechanical energy is converted into activation energy, which improves the reactivity of the mixed raw materials, reduces the thermal stability of the reaction, accelerates the reaction process, and the addition of flux increases the amount of liquid phase generated in the system, thereby reducing the formation temperature of calcium aluminate and magnetic iron ore phases.

[0041] (2) The method used in this invention has high iron-aluminum separation efficiency and produces high-quality products. Among them, high-whiteness aluminum hydroxide can be widely used in flame retardant, electronic appliances and coatings. After hydrothermal conversion or atmospheric pressure calcium extraction, the magnetic separation tailings are used to prepare calcareous / siliceous materials. There is no solid waste discharge, realizing the high-value and full-scale utilization of iron-aluminum symbiotic minerals. Attached Figure Description

[0042] Figure 1 A process flow diagram for extracting aluminum and co-producing iron concentrate from low-quality complex iron-aluminum symbiotic resources according to the present invention. Detailed Implementation

[0043] The present invention is further illustrated below through specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0044] The raw material used in the embodiments of the present invention is an iron-aluminum symbiotic ore, whose main chemical components include 25%~50% Fe2O3, 25%~50% Al2O3, 5%~25% SiO2 and 1%~3% TiO2.

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

[0046] The carbon-alkali concentration (N) described in the embodiments of the present invention CThe concentration of Na2CO3 (calculated as Na2O) is the mass-volume concentration, and the liquid-solid ratio (L / S) is the ratio of the volume of the leaching alkaline solution to the mass of the clinker.

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

[0048] In the embodiments of the present invention, the main components of the reduction sintering product are calcium aluminate, magnetic iron, calcium titanate and calcium orthosilicate.

[0049] In this embodiment of the invention, rapid solid-liquid separation is achieved using a settling tank, a filter, or a filter press.

[0050] The main components of the leaching residue in this embodiment of the invention are magnetic iron, calcium orthosilicate and calcium carbonate.

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

[0052] Example 1

[0053] This embodiment uses Guigang iron-aluminum symbiotic ore, whose main chemical components (mass percentage, wt. / %) are: Fe2O3 43.21%, Al2O3 29.25%, SiO2 6.31% and TiO2 1.67%, with an aluminum-silicon ratio of 4.64.

[0054] In this embodiment, the calcium 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 matter 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 diagram of which is as follows: Figure 1 As shown, the specific steps include:

[0056] (1) Mix Guigang iron-aluminum symbiotic ore, anthracite and fluorite evenly, crush them separately to a particle size ≤2 cm using a jaw crusher, add limestone according to the proportion, mix evenly and then mechanically activate using a high-energy ball mill. The ball milling rate is 600 rpm and the ball milling time is 120 min to obtain raw material with a particle size ≤0.074 mm accounting for ≥90% of the total mass for later use.

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

[0058] The role of adding fluorite as a flux is to reduce the viscosity of the reducing material and the formation temperature of the target mineral phase, promote the formation of the liquid phase, the occurrence of the reduction sintering reaction and the reconstruction of the low-temperature mineral phase during the reduction sintering process, and achieve the initial separation and enrichment of iron and aluminum resources.

[0059] (2) The raw material obtained in step (1) is pressed into pellets with a diameter of 1 cm to 3 cm and fed into a two-stage rotary kiln. After heating to 780°C at 10°C / min, the first stage of reduction sintering is carried out for 2 h. After the first stage of reduction sintering is completed, the temperature is raised to 1050°C at 10°C / min and the second stage of reduction sintering is carried out for 1 h. After the second stage of reduction sintering is completed, the furnace is cooled to below 400°C to obtain the reduction sintered product.

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

[0061] The resulting leaching slurry was subjected to rapid liquid-solid separation using a filter. The resulting liquid phase was a sodium aluminate solution, and the solid phase was the leaching residue, whose main chemical components were dicalcium silicate, magnetic iron, calcium titanate, and calcium carbonate. The chemical reaction formula for the atmospheric pressure leaching process is as follows:

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

[0063] (4) Add lime slurry with a mass concentration of 150 g / L to sodium aluminate solution for desilication under normal pressure. The CaO content in the lime slurry is 11 g / L. The desilication temperature is 90℃ and the desilication time is 3 h. After desilication, the slurry is separated into solid and liquid to obtain a refined sodium aluminate solution. The silicon index of the refined sodium aluminate solution is 810 and the absorbance of the solution is 0.27.

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

[0065] The chemical reaction formula for the atmospheric pressure desilication process is as follows:

[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) High white aluminum hydroxide was prepared by carbonation decomposition of refined sodium aluminate solution. The carbonation decomposition temperature was 96℃, the decomposition time was 6 h, the CO2 aeration rate was 3.8 L / min, and the stirring speed was 650 r / min.

[0069] The mother liquor produced by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 120 g / L (calculated as Na2O). 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 with water until the pH value of the washing liquid is ≤9, and adjust it into a slurry with a mass concentration of 35%. The leaching residue is treated by weak magnetic separation in a drum magnetic separator to achieve efficient separation and enrichment of iron concentrate and magnetic separation tailings. The magnetic field strength is 2800 Oe. The main components of the magnetic separation tailings are CaCO3 and 2CaO·SiO2, which can be used to prepare calcareous / silica materials.

[0071] The obtained iron concentrate contains, by mass percentage: 72% TFe, 2.4% Al2O3, 82.9% alumina recovery, and 86% iron recovery. The decomposition rate of the sodium aluminate refining solution is 92%, and the whiteness of the high-white aluminum hydroxide product is 97%, with an average particle size of 45 μm.

[0072] Example 2

[0073] This embodiment uses Guizhou iron-aluminum symbiotic ore, whose main chemical components (mass percentage, wt. / %) are: Fe2O3 49.72%, Al2O3 31.65%, SiO2 5.87% and TiO2 2.31%, with an aluminum-silicon ratio of 5.39.

[0074] In this embodiment, the calcium additive is ordinary industrial-grade phosphate lime with a CaO content of 83%~86%; the reducing agent is ordinary industrial-grade lignite and biomass, with the industrial-grade lignite having an effective carbon content of 62%~70% and a volatile matter content of 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 Guizhou iron-aluminum symbiotic ore, lignite, biomass and fluorite evenly, crush them separately to a particle size ≤2 cm using a jaw crusher, add phosphate lime according to the proportion, mix evenly and then ball mill using a high-energy ball mill at a ball milling rate of 700 rpm for 90 min to obtain raw material with a particle size ≤0.074 mm accounting for 93% of the total mass for later use;

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

[0078] (2) The raw material obtained in step (1) is pressed into pellets with a diameter of 1 cm to 3 cm and fed into a two-stage rotary kiln. After heating to 800°C at 10°C / min, the first stage of reduction sintering is carried out for 2.5 h. After the first stage of reduction sintering is completed, the temperature is raised to 1100°C at 10°C / min and the second stage of reduction sintering is carried out for 2 h. After the second stage of reduction sintering is completed, the furnace is cooled to below 400°C to obtain the reduction sintered product.

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

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

[0081] (5) High white aluminum hydroxide was prepared by carbonation decomposition of refined sodium aluminate solution. The carbonation decomposition temperature was 98℃, the decomposition time was 6.5 h, the CO2 aeration rate was 4 L / min, and the stirring speed was 700 r / min.

[0082] The mother liquor produced by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 120 g / L (calculated as Na2O). The adjusted 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 with water until the pH value of the washing liquid is ≤9, adjust it into a slurry with a mass concentration of 30%, and obtain iron concentrate and magnetic separation tailings by weak magnetic separation with a magnetic field strength of 3100 Oe.

[0084] The obtained iron concentrate contains, by mass percentage: 73% TFe, 2.1% Al2O3, 84.2% alumina recovery, and 88% iron recovery. The decomposition rate of the sodium aluminate refining solution is 93%, and the whiteness of the high-white aluminum hydroxide product is 98%, with an average particle size of 46 μm.

[0085] Example 3

[0086] This embodiment uses Guangxi iron-aluminum symbiotic ore, whose main chemical components (mass percentage, wt. / %) are: Fe2O3 48.05%, Al2O3 32.66%, SiO2 8.31% and TiO2 1.35%, with an aluminum-silicon ratio of 3.93.

[0087] In this embodiment, the calcium additive is ordinary industrial-grade calcium carbide slag with a CaO content of 65%~72%; the reducing agent is ordinary industrial-grade low-sulfur anthracite powder with an effective carbon content of 60%~63% and a volatile matter content of 25%~29%.

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

[0089] (1) Mix Guangxi iron-aluminum symbiotic ore, anthracite and fluorite evenly, crush them separately to a particle size ≤2 cm using a jaw crusher, add carbide slag according to the proportion, mix evenly and then ball mill using a high-energy ball mill at a ball milling rate of 600 rpm for 120 min to obtain raw material with a particle size ≤0.074 mm accounting for 90% of the total mass for later use;

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

[0091] (2) The raw material obtained in step (1) is pressed into pellets with a diameter of 1 cm to 3 cm and fed into a two-stage rotary kiln. After heating to 770°C at 10°C / min, the first stage of reduction sintering is carried out for 1.5 h. After the first stage of reduction sintering is completed, the temperature is raised to 1080°C at 10°C / min and the second stage of reduction sintering is carried out for 1.5 h. After the second stage of reduction sintering is completed, the furnace is cooled to below 400°C to obtain the reduction sintered product.

[0092] (3) Place the reduction sintered product into a ball mill, add sodium carbonate solution for atmospheric pressure leaching while grinding and leaching, and finely grind the reduction sintered product until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass. The liquid-solid ratio of sodium carbonate solution to reduction sintered product is 5 L / kg; use Na2O C The concentration of sodium carbonate solution was 130 g / L, the leaching temperature was controlled at 78℃, the leaching time was 100 min, and the resulting leaching slurry was subjected to rapid liquid-solid separation using a filter. The obtained liquid phase was sodium aluminate solution, and the solid phase was leaching residue.

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

[0094] (5) High white aluminum hydroxide was prepared by carbonation decomposition of refined sodium aluminate solution. The carbonation decomposition temperature was 93℃, the decomposition time was 5.8 h, the CO2 aeration rate was 3.5 L / min, and the stirring speed was 690 r / min.

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

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

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

[0098] Example 4

[0099] This embodiment uses Guangxi iron-aluminum symbiotic ore, whose main chemical composition (mass percentage, wt. / %) is: Fe2O3 43.56%, Al2O3 35.76%, SiO2 8.58% and TiO2 2.76%, with an aluminum-silicon ratio of 4.16.

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

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

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

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

[0104] (2) The raw material obtained in step (1) is pressed into pellets with a diameter of 1 cm to 3 cm and fed into a two-stage rotary kiln. After heating to 700°C at 10°C / min, the first stage of reduction sintering is carried out for 3 h. After the first stage of reduction sintering is completed, the temperature is raised to 1080°C at 10°C / min and the second stage of reduction sintering is carried out for 1.5 h. After the second stage of reduction sintering is completed, the furnace is cooled to below 400°C to obtain the reduction sintered product.

[0105] (3) Place the reduction sintered product into a ball mill, add sodium carbonate solution for atmospheric pressure leaching while grinding and leaching, and finely grind the reduction sintered product until the particle size passing through a 100-mesh sieve accounts for ≥90% of the total mass. The liquid-solid ratio of sodium carbonate solution to reduction sintered product is 4.5 L / kg; use Na2O C The concentration of sodium carbonate solution was 160 g / L, the leaching temperature was controlled at 80℃, the leaching time was 100 min, and the resulting leaching slurry was subjected to rapid liquid-solid separation using a filter. The obtained liquid phase was sodium aluminate solution, and the solid phase was leaching residue.

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

[0107] (5) High white aluminum hydroxide was prepared by carbonation decomposition of refined sodium aluminate solution. The carbonation decomposition temperature was 97℃, the decomposition time was 6.8 h, the CO2 aeration rate was 3.8 L / min, and the stirring speed was 650 r / min.

[0108] The mother liquor produced by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 150 g / L (calculated as Na2O). The adjusted 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 with water until the pH value of the washing liquid is ≤9, adjust it into a slurry with a mass concentration of 35%, and obtain iron concentrate and magnetic separation tailings by weak magnetic separation with a magnetic field strength of 3050 Oe.

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

[0111] Example 5

[0112] This embodiment uses iron-aluminum symbiotic ore from Chongzuo, Guangxi, whose main chemical components (mass percentage, wt. / %) are: Fe2O3 46.11%, Al2O3 29.65%, SiO2 11.23% and TiO2 2.12%, with an aluminum-silicon ratio of 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 with an effective carbon content of 60%~72% and a volatile matter content of 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 Chongzuo iron-aluminum symbiotic ore, lignite and fluorite evenly, crush them separately to a particle size ≤2 cm using a jaw crusher, add limestone according to the proportion, mix evenly and then ball mill using a high-energy ball mill at a ball milling rate of 630 rpm and a ball milling time of 110 min to obtain raw material with a particle size ≤0.074 mm accounting for 93% of the total mass for later use;

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

[0117] (2) The raw material obtained in step (1) is pressed into pellets with a diameter of 1 cm to 3 cm and fed into a two-stage rotary kiln. After heating to 780°C at 10°C / min, the first stage of reduction sintering is carried out for 2.7 h. After the first stage of reduction sintering is completed, the temperature is raised to 1050°C at 10°C / min and the second stage of reduction sintering is carried out for 2 h. After the second stage of reduction sintering is completed, the furnace is cooled to below 400°C to obtain the reduction sintered product.

[0118] (3) The reduction sintered product was placed in a ball mill, and sodium carbonate solution was added for atmospheric pressure leaching while grinding. The reduction sintered product was finely ground until the particle size passed through a 100-mesh sieve, accounting for 92% of the total mass. The liquid-solid ratio of sodium carbonate solution to reduction sintered product was 4.5 L / kg. Na2O was used as the solvent. CThe concentration of sodium carbonate solution was 135 g / L, the leaching temperature was controlled at 75℃, the leaching time was 100 min, and the resulting leaching slurry was subjected to rapid liquid-solid separation using a filter. The obtained liquid phase was sodium aluminate solution, and the solid phase was leaching residue.

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

[0120] (5) High white aluminum hydroxide was prepared by carbonation decomposition of refined sodium aluminate solution. The carbonation decomposition temperature was 97℃, the decomposition time was 6.5 h, the CO2 aeration rate was 3.2 L / min, and the stirring speed was 610 r / min.

[0121] The mother liquor produced by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 120 g / L (calculated as Na2O). The adjusted 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 with water until the pH value of the washing liquid is ≤9, adjust it into a slurry with a mass concentration of 30%, and obtain iron concentrate and magnetic separation tailings by weak magnetic separation with a magnetic field strength of 3120 Oe.

[0123] The obtained iron concentrate contains, by mass percentage: 76.3% TFe, 1.97% Al2O3, 85.52% alumina recovery, and 82.85% iron recovery. The decomposition rate of the sodium aluminate refining solution is 93%, and the whiteness of the high-white aluminum hydroxide product is 96%, with an average particle size of 44.8 μm.

[0124] Example 6

[0125] This embodiment uses iron-aluminum symbiotic ore from Pingguo, Guangxi, whose main chemical components (mass percentage, wt. / %) are: Fe2O3 36.77%, Al2O3 46.83%, SiO2 13.06% and TiO2 1.94%, with an aluminum-silicon ratio of 3.59.

[0126] In this embodiment, the calcium additive is ordinary industrial-grade calcium carbide slag with a CaO content of 68%~72%; the reducing agent is ordinary industrial-grade lignite with an effective carbon content of 67%~75% and a volatile matter content of 21%~26%.

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

[0128] (1) Mix Pingguo iron-aluminum symbiotic ore, lignite and fluorite evenly, crush them separately to a particle size ≤2 cm using a jaw crusher, add carbide slag according to the proportion, mix evenly and then ball mill using a high-energy ball mill at a ball milling rate of 700 rpm and a ball milling time of 150 min to obtain raw material with a particle size ≤0.074 mm accounting for 95% of the total mass for later use;

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

[0130] (2) The raw material obtained in step (1) is pressed into pellets with a diameter of 1 cm to 3 cm and fed into a two-stage rotary kiln. After heating to 800°C at 10°C / min, the first stage of reduction sintering is carried out for 2.5 h. After the first stage of reduction sintering is completed, the temperature is raised to 1000°C at 10°C / min and the second stage of reduction sintering is carried out for 2 h. After the second stage of reduction sintering is completed, the furnace is cooled to below 400°C to obtain the reduction sintered product.

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

[0132] (4) The mass concentration of lime slurry is 180 g / L. Lime slurry with CaO content of 13 g / L is added to sodium aluminate solution for desilication under normal pressure. The desilication temperature is 105℃ and the desilication time is 3 h. After desilication, the slurry is separated into solid and liquid to obtain a refined sodium aluminate solution. The silicon index of the refined sodium aluminate solution is 810 and the absorbance of the solution is 0.28.

[0133] (5) High white aluminum hydroxide was prepared by carbonation decomposition of refined sodium aluminate solution. The carbonation decomposition temperature was 99℃, the decomposition time was 7 h, the CO2 aeration rate was 4 L / min, and the stirring speed was 700 r / min.

[0134] The mother liquor produced by carbonation decomposition is further supplemented with sodium carbonate to adjust the solution concentration to 125 g / L (calculated as Na2O). The adjusted 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 with water until the pH value of the washing liquid is ≤9, adjust it into a slurry with a mass concentration of 38%, and obtain iron concentrate and magnetic separation tailings by weak magnetic separation with a magnetic field strength of 3140 Oe.

[0136] The obtained iron concentrate contains, by mass percentage: 73.5% TFe, 2.08% Al2O3, 85.83% alumina recovery, and 84.79% iron recovery. The decomposition rate of the sodium aluminate refining solution is 92.5%, and the whiteness of the high-white aluminum hydroxide product is 97%, with an average particle size of 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, The specific steps include: (1) Mechanically activate the iron-aluminum symbiotic ore, reducing agent, calcium additive and flux to obtain a uniformly mixed raw material for later use; The chemical composition of the iron-aluminum symbiotic ore, by mass fraction, is: Fe2O3 25%–50%, Al2O3 25%–50%, SiO2 5%–25%, TiO2 1%–3%; The reducing agent is a mixture of one or more substances selected from biomass, anthracite, lignite, and long-flame coal. There is no limit to the proportion between the various 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 one or a mixture of ammonium bisulfate, ammonium sulfate, potassium chlorate, fluorite, sodium fluoride, borax and lithium metaborate. There is no limit to the proportion between the various fluxes, and the amount added is 3.0% to 8.0% of the mass of the iron-aluminum symbiotic mineral powder. The calcium additive is one or a mixture of two of carbide slag, limestone and phosphate lime. There is no limit to the proportion between the various calcium additives. The molar ratio of CaO content in the calcium additive to Al2O3, SiO2 and TiO2 content in the iron-aluminum symbiotic ore is (3.8~5.1):

1. (2) Press the raw material obtained in step (1) into pellets with a diameter of 1cm to 3cm, place them in a reduction sintering kiln for the first stage of reduction sintering, and after the first stage of reduction sintering is completed, continue to heat up for the second stage of reduction sintering, and then cool with the furnace to obtain the reduction sintering product. The reduction sintering of the pellets is carried out in a flame-diverting kiln or a two-stage rotary kiln. The first stage of reduction sintering is specifically carried out by heating the pellets to 600℃~800℃ at 10℃ / min and then carrying out the first stage of reduction sintering for 1h~3h. The second stage of reduction sintering of the pellets is specifically as follows: the pellets are heated to 850℃~1100℃ at 10℃ / min and then subjected to second stage reduction sintering for 0.5h~2h. After the second stage of reduction sintering is completed, the pellets are cooled to below 400℃ in the furnace. (3) The reduction sintering product is placed into a ball mill or a grid mill, and sodium carbonate solution is added for atmospheric pressure leaching while milling and leaching. The resulting leaching slurry is subjected to rapid liquid-solid separation to obtain sodium aluminate solution and leaching residue. (4) After adding lime slurry to sodium aluminate solution, desilication is carried out under normal pressure. After desilication, the slurry is separated into solid and liquid to obtain refined sodium aluminate solution. (5) The refined sodium aluminate solution is carbonated and decomposed to obtain high white aluminum hydroxide. The decomposition mother liquor produced by carbonation and decomposition is further supplemented with sodium carbonate to adjust the solution concentration. The adjusted sodium carbonate solution is returned to step (3) for leaching of reduction sintering products. (6) After preparing the leaching residue obtained in step (4) into a slurry, iron concentrate and magnetic separation tailings are obtained by weak magnetic separation.

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

3. 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 (3), the reduction sintering product is finely ground until the particle size passes through a 100-mesh sieve, accounting for ≥90% of the total mass. The liquid-to-solid ratio of sodium carbonate solution to reduction sintering product is 2 L / kg to 5 L / kg. Na₂O C Based on content, the concentration of sodium carbonate solution is 100g / L~160g / L, the leaching temperature is 60℃~80℃, and the leaching time is 60min~120min; The liquid-solid rapid separation process of the leaching slurry adopts a settling tank, filter, or filter press.

4. 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 (4), the mass concentration of lime slurry is 100g / L to 200g / L, the CaO content in lime slurry is 6g / L to 14g / L, the desilication temperature under normal pressure is 80℃ to 110℃, the desilication time is 1h to 3h, and the silicon index of the refined sodium aluminate solution obtained after desilication is ≥800 and the absorbance of the solution is <0.

3.

5. 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 (5), the carbonation decomposition temperature of the refined sodium aluminate solution is 70℃~100℃, the decomposition time is 3h~7h, the CO2 aeration rate is 1L / min~4L / min, and the stirring speed is 400r / min~700r / min. Based on Na2O, the decomposition mother liquor produced by carbonation decomposition is supplemented with sodium carbonate to adjust the concentration to 100g / L~160g / L, and then returned to step (3) for leaching of the reduction sintering product.

6. 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 (6), the process of preparing slurry from leaching residue is as follows: hot water is added to the leaching residue, and the residue is washed until the pH value of the washing liquid is ≤9, and then the slurry is prepared with a mass concentration of 15% to 45%. The weak magnetic separation is a single or multiple magnetic separation, with a magnetic field strength of 1880 Oe to 3140 Oe.

7. 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, The iron concentrate obtained by the weak magnetic separation has the following composition by mass percentage: TFe ≥ 72%, Al2O3 ≤ 2.5%, and the recovery rates of alumina and iron in the iron concentrate are both above 82%; the decomposition rate of the sodium aluminate refining solution is ≥ 91%, the whiteness of the high-white aluminum hydroxide product is 95% to 98%, and the average particle size is < 50 μm.

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