Method for comprehensive utilization of high-iron bauxite by lattice activation pretreatment

Abstract

The application discloses a method for comprehensively utilizing high-iron bauxite by means of lattice activation pretreatment, and belongs to the technical field of metallurgy, which comprises the following steps: crushing and finely grinding high-iron bauxite and mineralizing agents respectively to obtain raw materials with uniform particle size; uniformly mixing the treated high-iron bauxite, the mineralizing agents and lattice modification agents according to a set liquid-solid ratio to obtain mixed ore slurry; performing ultrasonic wave reinforced mineral lattice modification treatment on the mixed ore slurry to obtain pretreated ore slurry; performing drying treatment on the pretreated ore slurry to obtain pretreated ore; performing decomposition activation treatment on the pretreated ore to obtain activated ore and the like. The method adopts a synergistic process of lattice modification, decomposition activation, high-temperature dissolution and magnetic separation, realizes efficient coupling with an existing Bayer process system, improves the actual dissolution rate of aluminum oxide to more than 95%, improves the iron recovery rate to more than 70%, and obtains high-quality iron concentrate with a Tfe content of more than or equal to 60% and an Al2O3 content of less than or equal to 3%, so that the amount of red mud is greatly reduced and the red mud is utilized in a high-value manner from the source, and the method has the advantages of environmental protection and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a method for the comprehensive utilization of high-iron bauxite through lattice activation pretreatment. Background Technology

[0002] my country is the world's largest producer of alumina, but its bauxite resources are relatively scarce, and mainly consist of low-grade, complex bauxite. Low-grade high-iron bauxite is an important resource, with proven reserves exceeding 1 billion tons domestically. However, this type of resource generally has a low aluminum-silicon ratio and complex iron-aluminum mineral intercalation, making it a typical difficult-to-process ore. Meanwhile, my country imports a large amount of foreign bauxite annually, reaching 200 million tons by 2025, primarily high-iron bauxite. This high-iron bauxite contains large amounts of aluminum hematite and aluminum goethite, and is generally characterized by Al... 3+ For Fe 3+ Isomorphic substitution leads to difficulties in the dissociation of iron and aluminum mineral monomers.

[0003] For the aforementioned high-iron bauxite, the current mainstream processing technology is direct leaching using the Bayer process, followed by iron recovery from the leached red mud using strong magnetic separation. However, the current processing technology primarily focuses on alumina extraction, neglecting the efficient comprehensive utilization of iron and aluminum minerals. This results in low alumina leaching rates, low-grade iron concentrate obtained from magnetic separation (only 40%–50%), ultimately leading to low overall recovery rates of iron and aluminum elements, large red mud emissions, and poor overall economic efficiency. To address this challenge, it is urgent to develop a process that simultaneously improves the utilization rate of iron and aluminum elements at the source.

[0004] Patent [CN113683106A] proposes a method for producing alumina using the Bayer process with no or low calcium. This method targets gibbsite-type bauxite and uses iron powder and ether cellulose as additives to reduce or avoid the adverse effects of lime in the alumina production process. However, it generates a large amount of hydrogen gas during the reduction and leaching stage, which not only places higher demands on the pressure resistance of the equipment but also poses certain safety hazards.

[0005] Patent [CN118594752A] proposes a method for the graded utilization of high-iron bauxite. This method involves grinding and gravity separation of the high-iron bauxite to obtain high-alumina, high-iron, low-silica, and low-titanium slurry and low-alumina, low-iron, high-silica, and high-titanium slurry, which are then processed using high-temperature and low-temperature Bayer processes, respectively. While this method can improve the alumina leaching rate of the high-temperature Bayer process, it suffers from problems such as a long process flow and low ore utilization.

[0006] Patent [CN102583477A] proposes a comprehensive utilization method for low-grade bauxite with high iron content. This method achieves efficient separation and comprehensive recovery of aluminum and iron, and the material is recycled within the system, improving resource utilization. However, this method has a complex process flow, high energy consumption, and relies on excessive lime and reducing agents, and still faces significant challenges in terms of equipment investment, operating costs, and environmental protection. Summary of the Invention

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for the comprehensive utilization of high-iron bauxite through lattice activation pretreatment. This method employs a lattice modification strategy, directionally embedding specific lattice modifiers into the mineral lattice of high-iron bauxite, pre-constructing lattice defects, and disrupting the integrity of its structure. This expands the interplanar spacing and increases the specific surface area, achieving efficient dissociation of aluminum minerals and directional magnetization of iron minerals. It also promotes the decomposition of goethite to release alumina, thereby increasing the dissolution rate. Goethite, aluminum goethite, and hematite are transformed in situ into magnetite and maghematite, achieving efficient cascade utilization of iron and aluminum elements. The method includes the following steps:

[0008] Step (1) Raw material preparation: The high-iron bauxite and mineralizing agent are crushed and finely ground separately to obtain raw materials with uniform particle size for later use;

[0009] Step (2) Slurry mixing: The treated high-iron bauxite, mineralizer, and lattice modifier are mixed uniformly according to the set liquid-solid ratio to obtain a mixed slurry; Optionally, an enhancing agent to improve the lattice modification effect can be added during the mixing process;

[0010] Step (3) Lattice modification: The mixed slurry is subjected to ultrasonic-enhanced mineral lattice modification treatment to obtain pretreated slurry;

[0011] Step (4) Slurry drying: Using the tail gas generated in the decomposition and activation process in step (5) as a heat source, the pretreated slurry is dried to obtain pretreated ore;

[0012] Step (5) Decomposition and activation: Using the residual heat generated from the aluminum hydroxide roasting process in the Bayer process as a heat source, the pretreated ore is decomposed and activated to obtain activated ore;

[0013] Step (6) High-temperature leaching: The activated mineral is leached at high temperature, and after the reaction, solid-liquid separation is performed to obtain the leaching liquid and the structured red mud mainly composed of magnetic iron minerals;

[0014] Step (7) Separation and recovery: The leachate enters the Bayer process for conventional alumina production; the structural red mud is separated by magnetic separation to obtain iron concentrate and magnetic separation tailings. Optionally, the magnetic separation tailings are separated by secondary magnetic separation.

[0015] Step (1) The content of Al2O3 in high-iron bauxite is 25-50%, the content of Fe2O3 is 20-40%, the content of SiO2 is 1-15%, the content of TiO2 is 1-5%, and the part with a particle size ≤100μm accounts for ≥90% of the total mass.

[0016] The mineralizer mentioned in step (1) is one or more of industrial lime, carbide slag, and calcium aluminate. There is no limit to the proportion between the various mineralizers. The amount added is 0.1% to 10% of the mass fraction of high-iron bauxite, and the portion with a particle size ≤100μm accounts for ≥90% of the total mass.

[0017] The lattice modifier in step (2) is a hydroxyl polymer, including but not limited to polyols, starch and its modified forms, and its addition amount is 0.1% to 10% of the dry weight of high-iron bauxite. During the mixing process, one or more reinforcing agents selected from organic alcohols, amines or ketones may be added, and their addition amount is 5% to 20% of the weight of the lattice modifier, thereby improving the lattice modification effect. The liquid-solid ratio is controlled at 1 to 2.

[0018] In step (3), the ultrasonic power used for the lattice modification treatment is 300~500W, and the treatment time is 15~60min.

[0019] In step (5), the activation temperature is 120-300℃ and the activation time is 30-120min.

[0020] In step (6), the concentration of caustic soda in the circulating mother liquor used in the high-temperature dissolution process is 140~240g / L, the molecular ratio is 2.6~3.2, the dissolution temperature is 220~280℃, and the dissolution time is 15~90min.

[0021] The phase composition of the structural red mud in step (6) includes, but is not limited to, magnetite, maghemite, hematite, hydrated sodium aluminosilicate, and hydrated garnet.

[0022] The number of magnetic separations in step (7) is one or more, the magnetic field strength is 5000~20000Oe, and the number of pulses is 50~300 times / minute.

[0023] In step (7), the iron concentrate contains ≥60% TFe and ≤3% Al2O3 by mass percentage; the actual alumina dissolution rate is ≥95% and the iron recovery rate is ≥75%.

[0024] The beneficial effects of this invention are:

[0025] (1) Based on the design concept of comprehensive utilization of iron and aluminum minerals, this invention breaks through the limitation of traditional methods that only focus on the extraction of alumina from high-iron bauxite, and realizes the gradient and efficient utilization of iron and aluminum minerals.

[0026] (2) The present invention employs a synergistic process of lattice modification, decomposition activation, high-temperature leaching, and strong magnetic separation; the lattice modifier significantly enhances the reactivity of aluminum minerals by directionally increasing the interplanar spacing and specific surface area of ​​minerals; the reinforcing agent enhances the modification effect of the lattice modifier on the mineral lattice by improving the stability and surface adsorption capacity of the lattice modifier; the mineralizing agent simultaneously induces the iron minerals to be directionally transformed into a strongly magnetic phase, which facilitates subsequent magnetic separation.

[0027] (3) The process flow of the present invention is highly compatible with the existing Bayer process system. Only key steps such as lattice modification are introduced to achieve close coupling with the mainstream leaching system. It has the advantages of strong engineering adaptability and low modification cost, and is easy to promote industrialization.

[0028] (4) This invention achieves a comprehensive breakthrough in core resource recovery indicators. The actual alumina leaching rate is increased from the conventional 75%~90% to over 95%, and the iron recovery rate is significantly increased from 20%~50% to over 75%. Moreover, the obtained iron concentrate is of excellent quality, with a stable TFe grade of ≥60% and an Al2O3 content of ≤3%.

[0029] (5) The process of this invention realizes a significant reduction and high-value utilization of red mud from the source. While significantly reducing the stockpile, it transforms iron resources into high-quality ironmaking raw materials, which has both outstanding environmental and economic benefits. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process for the comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to the present invention. Detailed Implementation

[0031] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] This invention provides a method for the comprehensive utilization of high-iron bauxite through lattice activation pretreatment, comprising the following steps:

[0033] Step (1) Raw material preparation: The high-iron bauxite and mineralizer are crushed and finely ground to increase the specific surface area of ​​the ore, improve the reaction contact area and activity, and obtain raw materials with uniform particle size for later use; the mineralizer induces the iron mineral to transform into a magnetic phase in subsequent steps to promote the separation of iron and aluminum.

[0034] Furthermore, the high-iron bauxite contains 25-50% Al2O3, 20-40% Fe2O3, 1-15% SiO2, and 1-5% TiO2, with the portion having a particle size ≤100μm accounting for ≥90% of the total mass.

[0035] Furthermore, the mineralizer is one or more of industrial lime, carbide slag, and calcium aluminate. There is no limit to the proportion between the various mineralizers. The amount added is 0.1% to 10% of the mass fraction of high-iron bauxite, and the portion with a particle size ≤100μm accounts for ≥90% of the total mass.

[0036] Step (2) Slurry mixing: The treated high-iron bauxite, mineralizer, and lattice modifier are uniformly mixed according to the set liquid-solid ratio to obtain a mixed slurry; the lattice modifier is embedded in the mineral lattice, constructs defects, expands the interplanar spacing, increases the specific surface area, and improves the mineral reactivity; the reinforcing agent improves the stability and adsorption capacity of the modifier; the mineralizer assists in the transformation of iron minerals. This step lays the foundation for lattice activation pretreatment.

[0037] Furthermore, the lattice modifier is a hydroxyl-based polymer, including but not limited to polyols, starch, and their modified forms, and its addition amount is 0.1% to 10% of the dry weight of high-iron bauxite. During the mixing process, one or more reinforcing agents selected from organic alcohols, amines, or ketones may be added, and their addition amount is 5% to 20% of the weight of the lattice modifier, thereby improving the lattice modification effect. The liquid-solid ratio is controlled at 1 to 2.

[0038] Step (3) Lattice modification: The mixed slurry is subjected to ultrasonic-enhanced mineral lattice modification treatment to obtain pretreated slurry; the ultrasonic power used for lattice modification treatment is 300~500W, and the treatment time is 15~60min; the ultrasonic wave generates cavitation effect, which promotes the directional embedding of lattice modifier into the iron-aluminum mineral lattice, destroys the structural integrity, expands the inter-crystal spacing, and improves the subsequent dissolution activity.

[0039] Step (4) Drying: The tail gas generated in the decomposition and activation process in step (5) is used as a heat source to dry the pretreated slurry to obtain pretreated ore; the waste heat in the system (such as tail gas such as CO2 and H2O) is used to realize energy recycling and reduce energy consumption; after drying, the slurry is converted into a solid state, which improves the activation efficiency.

[0040] Step (5) Decomposition and Activation: Using the residual heat generated from the aluminum hydroxide roasting process in the Bayer process system as a heat source, the pretreated ore is decomposed and activated to obtain activated ore; the activation temperature is 120-300℃ and the activation time is 30-120min. This step utilizes the residual heat to achieve coupling with the Bayer process and decomposes the modifier into reducing organic matter.

[0041] The chemical reaction formula for the lattice modifier during the decomposition and activation process is as follows:

[0042] (R-CH2OH) n →nR-CH2OH;

[0043] R-CH2OH + O2 → R-CHO + H2O;

[0044] R-CH2OH + O2 → R-COOH + H2O;

[0045] R-CH2CH2OH→RC=CH2+H2O;

[0046] Where R is a non-characteristic functional group of the lattice modifier, and n is the degree of polymerization of the lattice modifier.

[0047] Step (6) High-temperature leaching: The activated ore is leached at high temperature. After the reaction, solid-liquid separation is performed to obtain the leaching solution and structural red mud mainly composed of magnetic iron minerals. The concentration of caustic soda in the circulating mother liquor used in the high-temperature leaching process is 140~240g / L, the molecular ratio is 2.6~3.2, the leaching temperature is 220~280℃, and the leaching time is 15~90min. Under high-temperature alkaline leaching, the activated ore aluminum minerals are efficiently dissociated (leaching rate ≥95%), and the iron minerals are converted in situ into magnetite / maghemite, improving the magnetic separation efficiency.

[0048] The chemical reaction formula that occurs during the high-temperature leaching process of activated minerals is as follows:

[0049] Al2O3·3H2O+NaOH→NaAl(OH)4;

[0050] FeOOH→α-Fe2O3+H2O;

[0051] R-CH2OH+α-Fe2O3→Fe3O4+γ-Fe2O3+CO2+H2O;

[0052] R-CH2OH+Fe x Al 1-x OOH→Fe3O4+γ-Fe2O3+Al2O3+CO2+H2O;

[0053] R-CHO+α-Fe2O3→Fe3O4+γ-Fe2O3+CO2+H2O;

[0054] R-CHO+ Fe x Al 1-x OOH→Fe3O4+γ-Fe2O3+Al2O3+CO2+H2O;

[0055] R-COOH+α-Fe2O3→Fe3O4+γ-Fe2O3+CO2+H2O;

[0056] R-COOH+ Fe x Al 1-x OOH→Fe3O4+γ-Fe2O3+Al2O3+CO2+H2O;

[0057] Where x represents the degree of aluminum substitution in alkyne goethite.

[0058] The phase composition of the structural red mud includes magnetite (Fe3O4), maghemite (γ-Fe2O3), hematite (α-Fe2O3), and hydrated sodium aluminosilicate (Na2O·Al2O3· x SiO2· y H2O), hydrous garnet (3CaO·Al2O3· m SiO2·(6-2 m (H2O), etc.

[0059] Step (7) Separation and recovery: The leaching solution enters the Bayer process system for conventional alumina production; the structural red mud is separated by magnetic separation to obtain iron concentrate and magnetic separation tailings. Optionally, the magnetic separation tailings are separated by secondary magnetic separation. The leaching solution has a low molecular weight, which is suitable for Bayer process seed decomposition, carbon separation and other steps. It is compatible with the existing system and does not require modification. The iron minerals in the structural red mud are strongly magnetic, and the magnetic separation can efficiently recover iron (recovery rate ≥75%), and the tailings are discharged in reduced quantities.

[0060] The magnetic separation is performed once or multiple times, with a magnetic field strength of 5000~20000 Oe and a pulse frequency of 50~300 times / minute; the iron concentrate contains ≥60% TFe and ≤3% Al2O3 by mass percentage; the actual alumina leaching rate is ≥95% and the iron recovery rate is ≥75%.

[0061] In this embodiment of the invention, the concentration of the circulating mother liquor caustic soda is the mass concentration of NaOH (calculated as Na2O).

[0062] In this embodiment of the invention, the main components of the iron concentrate are magnetite, maghemite, and hematite.

[0063] In this embodiment of the invention, the main components of the magnetic separation tailings are hydrated sodium aluminosilicate and hydrated garnet.

[0064] Example 1

[0065] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 37.57%, Fe2O3 33.76%, SiO2 1.98%, TiO2 3.36%, with an aluminum-silicon ratio of 18.97.

[0066] In this embodiment, the lattice modifier is polypropylene alcohol, and the reinforcing agent is glycerol, both with a purity ≥90%. The mineralizer is industrial lime with an effective CaO content of 85.12%.

[0067] This embodiment specifically includes the following steps:

[0068] High-speed bauxite and industrial lime are crushed and finely ground separately to obtain raw materials with uniform particle size for later use.

[0069] Crushed high-iron bauxite, polypropylene alcohol, glycerol, and industrial lime were uniformly mixed at a liquid-to-solid ratio of 2 to obtain a slurry. The amount of polypropylene alcohol added was 10% of the dry weight of the high-iron bauxite; the amount of glycerol added was 10% of the weight of the lattice modifier; and the amount of industrial lime added was 1% of the weight of the high-iron bauxite.

[0070] The mixed slurry was subjected to ultrasonic-enhanced mineral lattice modification treatment to obtain pretreated slurry. The ultrasonic power was 400W and the treatment time was 60min.

[0071] The pretreated slurry is dried to obtain pretreated ore.

[0072] The pretreated ore was decomposed and activated at 240℃ for 60 min to obtain activated ore. The chemical reaction of the lattice modifier during the activation process is as follows:

[0073] HO-(CH(CH3)CH2O) n -H→nCH3CH(OH)CH2OH;

[0074] CH3CH(OH)CH2OH→(CH3)2CO+H2+H2O;

[0075] CH2(OH)CH(OH)CH2OH+O2→CH2=CHCOOH+H2O;

[0076] CH2=CHCOOH+O2→CO2+H2O;

[0077] The activated ore was subjected to high-temperature leaching under the conditions of a circulating mother liquor caustic soda concentration of 240 g / L, a molecular ratio of 2.61, a temperature of 240℃, and a time of 60 min. After the reaction, a leaching solution with a molecular ratio of 1.29 and structural red mud were obtained; the main phases of this red mud included magnetite, maghemite, hematite, hydrated sodium aluminosilicate, and hydrated garnet. The leaching solution was then used to produce alumina according to the conventional Bayer process.

[0078] The structural red mud was subjected to magnetic separation under a magnetic field strength of 11000 Oe and a pulse frequency of 150 times / minute to obtain iron concentrate and magnetic separation tailings. The main phases of the obtained iron concentrate were magnetite, maghemite, and hematite, while the main phases of the magnetic separation tailings were hydrated sodium aluminosilicate and hydrated garnet.

[0079] The actual alumina leaching rate was 96.14%. The resulting iron concentrate, by mass percentage, contained 63.12% TFe, 1.78% Al2O3, and had an iron recovery rate of 87.63%.

[0080] Example 2

[0081] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 35.57%, Fe2O3 32.76%, SiO2 2.57%, TiO2 2.96%, with an aluminum-silicon ratio of 13.84.

[0082] In this embodiment, the lattice modifier is polypropylene alcohol, and the reinforcing agent is acetone, both with a purity ≥90%. The mineralizer is industrial lime with an effective CaO content of 92.44%.

[0083] The method is the same as in Example 1, except that:

[0084] Crushed high-iron bauxite, polypropylene alcohol, acetone, and industrial lime were uniformly mixed at a liquid-to-solid ratio of 2 to obtain a slurry. The amount of polypropylene alcohol added was 6% of the dry weight of the high-iron bauxite; the amount of acetone added was 10% of the weight of the lattice modifier; and the amount of industrial lime added was 0.5% of the weight of the high-iron bauxite.

[0085] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 300W and a treatment time of 45min.

[0086] The pretreated ore was decomposed and activated at 220℃ for 75 minutes to obtain activated ore.

[0087] The activated ore was subjected to high-temperature leaching under the following conditions: a circulating mother liquor caustic soda concentration of 210 g / L, a molecular ratio of 2.65, a temperature of 250 °C, and a time of 60 min. After the reaction, a leaching solution with a molecular ratio of 1.30 and structural red mud were obtained.

[0088] The structural red mud was subjected to magnetic separation under the conditions of a magnetic field strength of 7000 Oe and a pulsation frequency of 200 times / minute.

[0089] The actual alumina dissolution rate was 97.36%. The iron concentrate, by mass percentage, contained 65.88% TFe, 2.11% Al2O3, and had an iron recovery rate of 85.06%.

[0090] Example 3

[0091] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 37.57%, Fe2O3 39.20%, SiO2 1.94%, TiO2 2.98%, with an aluminum-silicon ratio of 19.37.

[0092] In this embodiment, the lattice modifier is polybutanol with a purity ≥90%, and no reinforcing agent is used. The mineralizer is calcium carbide slag with an effective CaO content of 72.15%.

[0093] The method is the same as in Example 1, except that:

[0094] The crushed high-iron bauxite, polybutanol, and calcium carbide slag were uniformly mixed at a liquid-to-solid ratio of 1.8 to obtain a slurry. The amount of polybutanol added was 6% of the dry weight of the high-iron bauxite, and the amount of calcium carbide slag added was 0.5% of the weight of the high-iron bauxite.

[0095] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 350W and a treatment time of 20min.

[0096] The pretreated ore was decomposed and activated at 250℃ for 30 minutes to obtain activated ore.

[0097] The activated ore was subjected to high-temperature leaching under the conditions of a circulating mother liquor caustic soda concentration of 160 g / L, a molecular ratio of 2.91, a temperature of 260℃, and a time of 30 min. After the reaction, a leaching solution with a molecular ratio of 1.29 and structural red mud were obtained.

[0098] The structured red mud was subjected to magnetic separation under the conditions of a magnetic field strength of 9000 Oe and a pulsation frequency of 250 times / minute.

[0099] The actual alumina dissolution rate was 98.29%. The iron concentrate, by mass percentage, contained 66.14% TFe, 2.01% Al2O3, and had an iron recovery rate of 78.79%.

[0100] Example 4

[0101] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 49.22%, Fe2O3 23.71%, SiO2 7.57%, TiO2 1.06%, with an aluminum-silicon ratio of 6.50.

[0102] In this embodiment, the lattice modifier is polybutanol, and the reinforcing agent is triisopropanolamine, both with a purity ≥90%. The mineralizer is industrial lime with an effective CaO content of 90.22%.

[0103] The method is the same as in Example 1, except that:

[0104] Crushed high-iron bauxite, polybutanol, triisopropanolamine, and industrial lime were uniformly mixed at a liquid-to-solid ratio of 2 to obtain a slurry. The amount of polybutanol added was 8% of the dry weight of the high-iron bauxite; the amount of triisopropanolamine added was 20% of the weight of the lattice modifier; and the amount of industrial lime added was 6% of the weight of the high-iron bauxite.

[0105] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 500W and a treatment time of 30min.

[0106] The pretreated ore was decomposed and activated at 210℃ for 60 minutes to obtain activated ore.

[0107] The activated ore was subjected to high-temperature leaching under the following conditions: a circulating mother liquor caustic soda concentration of 240 g / L, a molecular ratio of 2.83, a temperature of 260 °C, and a time of 60 min. After the reaction, a leaching solution with a molecular ratio of 1.29 and structural red mud were obtained.

[0108] The structural red mud was subjected to magnetic separation under the conditions of magnetic field strength of 11000 Oe and pulsation frequency of 300 times / minute.

[0109] The actual alumina leaching rate was 96.71%. The iron concentrate, by mass percentage, contained 62.37% TFe, 2.61% Al₂O₃, and had an iron recovery rate of 77.67%.

[0110] Example 5

[0111] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 32.74%, Fe2O3 26.75%, SiO2 8.47%, TiO2 3.24%, with an aluminum-silicon ratio of 3.87.

[0112] In this embodiment, the lattice modifier is polypropylene alcohol, and the reinforcing agent is triethylenetetramine, both with a purity ≥90%. The mineralizing agent is calcium aluminate, with an effective CaO content of 50.07%.

[0113] The method is the same as in Example 1, except that:

[0114] Crushed high-iron bauxite, polypropylene alcohol, triethylenetetramine, and calcium aluminate were uniformly mixed at a liquid-to-solid ratio of 2 to obtain a slurry. The amount of polypropylene alcohol added was 5% of the dry weight of the high-iron bauxite; the amount of triethylenetetramine added was 20% of the weight of the lattice modifier; and the amount of calcium aluminate added was 5% of the weight of the high-iron bauxite.

[0115] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 330W and a treatment time of 60min.

[0116] The pretreated ore was decomposed and activated at 220℃ for 45 minutes to obtain activated ore.

[0117] The activated ore was subjected to high-temperature leaching under the following conditions: a circulating mother liquor caustic soda concentration of 226 g / L, a molecular ratio of 2.86, a temperature of 270℃, and a time of 45 min. After the reaction, a leaching solution with a molecular ratio of 1.30 and structural red mud were obtained.

[0118] The structural red mud was subjected to magnetic separation under the conditions of a magnetic field strength of 10000 Oe and a pulsation frequency of 200 times / minute.

[0119] The actual alumina dissolution rate was 96.79%. The iron concentrate, by mass percentage, contained 61.74% TFe, 2.51% Al2O3, and had an iron recovery rate of 77.44%.

[0120] Example 6

[0121] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 30.28%, Fe2O3 39.80%, SiO2 9.60%, TiO2 1.24%, with an aluminum-silicon ratio of 3.15.

[0122] In this embodiment, the lattice modifier is starch, and the reinforcing agent is triethanolamine, both with a purity ≥90%. The mineralizer is carbide slag with an effective CaO content of 70.01%.

[0123] The method is the same as in Example 1, except that:

[0124] Crushed high-iron bauxite, starch, triethanolamine, and calcium carbide slag were uniformly mixed at a liquid-to-solid ratio of 2 to obtain a slurry. The amount of starch added was 10% of the dry weight of the high-iron bauxite; the amount of triethanolamine added was 5% of the weight of the lattice modifier; and the amount of calcium carbide slag added was 8% of the weight of the high-iron bauxite.

[0125] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 350W and a treatment time of 30min.

[0126] The pretreated ore was decomposed and activated at 200℃ for 60 minutes to obtain activated ore.

[0127] The activated ore was subjected to high-temperature leaching under the following conditions: a circulating mother liquor caustic soda concentration of 200 g / L, a molecular ratio of 2.97, a temperature of 280℃, and a time of 45 min. After the reaction, a leaching solution with a molecular ratio of 1.30 and structural red mud were obtained.

[0128] The structural red mud was subjected to magnetic separation under the conditions of a magnetic field strength of 8000 Oe and a pulsation frequency of 250 times / minute.

[0129] The actual alumina dissolution rate was 96.27%. The iron concentrate, by mass percentage, contained 61.26% TFe, 2.87% Al₂O₃, and had an iron recovery rate of 76.14%.

[0130] Example 7

[0131] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 26.35%, Fe2O3 38.77%, SiO2 6.60%, TiO2 3.98%, with an aluminum-silicon ratio of 3.99.

[0132] In this embodiment, the lattice modifier is polypropylene alcohol, and the reinforcing agent is triethanolamine, both with a purity ≥90%. The mineralizing agent is calcium aluminate, with an effective CaO content of 75.78%.

[0133] The method is the same as in Example 1, except that:

[0134] Crushed high-iron bauxite, polypropylene alcohol, triethanolamine, and calcium aluminate were uniformly mixed at a liquid-to-solid ratio of 1 to obtain a slurry. The amount of polypropylene alcohol added was 0.5% of the dry weight of the high-iron bauxite; the amount of triethanolamine added was 10% of the weight of the lattice modifier; and the amount of calcium aluminate added was 8% of the weight of the high-iron bauxite.

[0135] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 500W and a treatment time of 15min.

[0136] The pretreated ore was decomposed and activated at 120℃ for 120 min to obtain activated ore.

[0137] The activated ore was subjected to high-temperature leaching under the following conditions: a circulating mother liquor caustic soda concentration of 220 g / L, a molecular ratio of 2.78, a temperature of 240℃, and a time of 60 min. After the reaction, a leaching solution with a molecular ratio of 1.30 and structural red mud were obtained.

[0138] The structural red mud was subjected to magnetic separation under the conditions of a magnetic field strength of 8000 Oe and a pulsation frequency of 250 times / minute.

[0139] The actual alumina leaching rate was 95.97%. The iron concentrate, by mass percentage, contained 61.71% TFe, 2.46% Al₂O₃, and had an iron recovery rate of 77.89%.

[0140] Example 8

[0141] The chemical composition of the raw material high-iron bauxite in this embodiment is (mass percentage, wt. / %): Al2O3 32.43%, Fe2O3 35.15%, SiO2 1.89%, TiO2 2.10%, with an aluminum-silicon ratio of 17.16.

[0142] In this embodiment, the lattice modifier is polybutanol, and the reinforcing agent is butanone, both with a purity ≥90%. The mineralizer is industrial lime with an effective CaO content of 91.57%.

[0143] The method is the same as in Example 1, except that:

[0144] Crushed high-iron bauxite, polybutanol, methyl ethyl ketone (MEK), and industrial lime were uniformly mixed at a liquid-to-solid ratio of 2 to obtain a slurry. The amount of polybutanol added was 0.1% of the dry weight of the high-iron bauxite; the amount of MEK added was 8% of the weight of the lattice modifier; and the amount of industrial lime added was 0.5% of the weight of the high-iron bauxite.

[0145] The ultrasonic lattice modification treatment of the mixed slurry was performed with an ultrasonic power of 300W and a treatment time of 60min.

[0146] The pretreated ore was decomposed and activated at 120℃ for 120 min to obtain activated ore.

[0147] The activated ore was subjected to high-temperature leaching under the following conditions: a circulating mother liquor caustic soda concentration of 140 g / L, a molecular ratio of 2.98, a temperature of 280℃, and a time of 60 min. After the reaction, a leaching solution with a molecular ratio of 1.30 and structural red mud were obtained.

[0148] The structured red mud was subjected to magnetic separation under the conditions of a magnetic field strength of 5000 Oe and a pulsation frequency of 150 times / minute.

[0149] The actual alumina leaching rate was 98.41%. The iron concentrate, by mass percentage, contained 66.14% TFe, 2.42% Al₂O₃, and had an iron recovery rate of 78.25%.

[0150] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any modifications, alterations, substitutions, and variations made by those skilled in the art to the above embodiments are within the scope of the present invention.

Claims

1. A method for the comprehensive utilization of high-iron bauxite through lattice activation pretreatment, characterized in that, Includes the following steps: Step (1) Raw material preparation: The high-iron bauxite and mineralizing agent are crushed and finely ground separately to obtain raw materials with uniform particle size for later use; Step (2) Slurry mixing: The treated high-iron bauxite, mineralizer, and lattice modifier are mixed uniformly according to the set liquid-solid ratio to obtain a mixed slurry; during the mixing process, an enhancing agent to improve the lattice modification effect is added; Specifically, the lattice modifier is a hydroxyl polymer, including polyols, starch and their modified forms; the reinforcing agent is one or more of organic alcohols, amines or ketones. Step (3) Lattice modification: The mixed slurry is subjected to ultrasonic-enhanced mineral lattice modification treatment to obtain pretreated slurry; Step (4) Slurry drying: Using the tail gas generated in the decomposition and activation process in step (5) as a heat source, the pretreated slurry is dried to obtain pretreated ore; Step (5) Decomposition and activation: Using the residual heat generated from the aluminum hydroxide roasting process in the Bayer process as a heat source, the pretreated ore is decomposed and activated to obtain activated ore; Step (6) High-temperature leaching: The activated mineral is leached at high temperature, and after the reaction, solid-liquid separation is performed to obtain the leaching liquid and the structured red mud mainly composed of magnetic iron minerals; Step (7) Separation and recovery: The leachate enters the Bayer process for conventional alumina production; The structural red mud was separated by magnetic separation to obtain iron concentrate and magnetic separation tailings. The magnetic separation tailings were then separated by secondary magnetic separation.

2. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: Step (1) The content of Al2O3 in high-iron bauxite is 25-50%, the content of Fe2O3 is 20-40%, the content of SiO2 is 1-15%, the content of TiO2 is 1-5%, and the part with a particle size ≤100μm accounts for ≥90% of the total mass.

3. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: The mineralizer mentioned in step (1) is one or more of industrial lime, carbide slag, and calcium aluminate. There is no limit to the proportion between the various mineralizers. The amount added is 0.1% to 10% of the mass fraction of high-iron bauxite, and the portion with a particle size ≤100μm accounts for ≥90% of the total mass.

4. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: In step (2), the amount of lattice modifier added is 0.1% to 10% of the dry weight of high-iron bauxite; the amount of reinforcing agent added is 5% to 20% of the weight of lattice modifier; and the liquid-solid ratio is 1 to 2.

5. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: In step (3), the ultrasonic power used for the lattice modification treatment is 300~500W, and the treatment time is 15~60min.

6. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: In step (5), the activation temperature is 120-300℃ and the activation time is 30-120min.

7. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: In step (6), the concentration of caustic soda in the circulating mother liquor used in the high-temperature dissolution process is 140~240g / L, the molecular ratio is 2.6~3.2, the dissolution temperature is 220~280℃, and the dissolution time is 15~90min.

8. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: The phase composition of the structural red mud in step (6) includes, but is not limited to, magnetite, maghemite, hematite, hydrated sodium aluminosilicate, and hydrated garnet.

9. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: The number of magnetic separations in step (7) is one or more, the magnetic field strength is 5000~20000Oe, and the number of pulses is 50~300 times / minute.

10. The method for comprehensive utilization of high-iron bauxite through lattice activation pretreatment according to claim 1, characterized in that: In step (7), the iron concentrate contains ≥60% TFe and ≤3% Al2O3 by mass percentage; the actual alumina dissolution rate is ≥95% and the iron recovery rate is ≥75%.

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