Production method of high-alumina fly ash and method for extracting aluminum from aluminum-rich coal

Abstract

The invention discloses a production method of high-alumina fly ash and a method for extracting aluminum from aluminum-rich coal, and relates to the technical field of valuable metal extraction.The production method of the high-alumina fly ash comprises the following steps that S10, raw coal, a silicon collecting agent and auxiliaries are mixed, reverse flotation is conducted, tailings are collected, and an aluminum-rich coal product is obtained; s20, the aluminum-rich coal product is subjected to centrifugal sedimentation, filter pressing and drying, and a coal cake is obtained; and S30, burning the coal cake to obtain the high-alumina fly ash. According to the method, the aluminum-rich coal is used as a raw material, and after the aluminum-rich coal is subjected to reverse flotation desiliconization, the content of combustible bodies is increased, so that the calorific value of the coal is increased, part of silicon is removed, and the aluminum-silicon ratio in the coal ash formed after the coal is fired is increased.

Description

Technical Field

[0001] The invention relates to the technical field of valuable metal extraction, and in particular to a method for producing high-aluminum fly ash and a method for extracting aluminum from aluminum-rich coal. Background Art

[0002] Bauxite is a scarce bulk mineral in my country. my country's bauxite reserves are small and the demand is large, resulting in a high degree of external dependence on bauxite and great pressure on aluminum resources. Therefore, finding raw materials that can replace bauxite is of great significance to alleviating the pressure on aluminum resources.

[0003] Fly ash is a fine solid particle collected from the flue gas generated during the coal combustion process. Its main components are mullite and amorphous silicon dioxide. It is one of the bulk industrial solid wastes in my country and is mainly used in building materials such as cement concrete. More than 85% of fly ash is composed of alumina and silicon dioxide, and the aluminum-silicon ratio, that is, the mass ratio of aluminum oxide to silicon dioxide in fly ash, is about 0.8.

[0004] Since the aluminum-silicon ratio is the most important parameter to measure the quality of bauxite, and the characteristics of high aluminum and low silicon in aluminum-rich coal have the potential for aluminum extraction, extracting alumina from fly ash becomes another option besides extracting aluminum from bauxite.

[0005] However, the aluminum-silicon ratio in fly ash not only affects the amount of raw materials used in the aluminum extraction process, but also affects the recovery rate of alumina. Therefore, how to improve the aluminum-silicon ratio in fly ash is an important issue. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for producing high-aluminum fly ash and a method for extracting aluminum from aluminum-rich coal, aiming to solve the problem of low aluminum-silicon ratio in existing fly ash.

[0007] To achieve the above object, the present invention provides a method for producing high-aluminum fly ash, which comprises the following steps:

[0008] S10, mixing the raw coal with the silicon collector and the auxiliary agent, performing reverse flotation, collecting the tailings, and obtaining an aluminum-rich coal product;

[0009] S20, subjecting the aluminum-rich coal product to centrifugal sedimentation, filter pressing, and drying to obtain coal cakes;

[0010] S30, burning the coal cakes to obtain high-aluminum fly ash.

[0011] In one embodiment, step S10 includes:

[0012] S101, crushing and grinding raw coal to obtain raw coal particles;

[0013] S102, mixing the raw coal particles and water to obtain a mixed solution, adjusting the pH of the mixed solution to 3-12 with a pH adjuster, mixing a silicon collector with the mixed solution, and shearing and stirring to obtain a raw coal particle suspension;

[0014] S103, mixing the raw coal particle suspension with a silicon collector and an auxiliary agent, performing reverse flotation, collecting tailings, and obtaining an aluminum-rich coal product.

[0015] In one embodiment, in step S101, the volume average particle size Dv90 of the raw coal particles is ≤300 mesh; and / or,

[0016] In step S102, the mass proportion of the raw coal particles in the raw coal particle suspension is 5% to 20%; and / or,

[0017] In step S102, the pH adjusting agent includes one or more of hydrochloric acid, sulfuric acid, nitric acid, calcium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; and / or,

[0018] In step S102, the shear stirring speed is 8000s -1 ~20,000s -1 and / or,

[0019] In step S102, the shear stirring time is 1 min to 20 min.

[0020] In one embodiment, the ratio of the mass of the silicon collector in step S102 to the mass of the silicon collector in step S103 is (2-5):(5-8).

[0021] In one embodiment, the silicon collector comprises an amine cationic collector, and the amine cationic collector comprises one or more of a quaternary ammonium salt collector, a linear alkylamine salt collector, a tertiary amine salt collector, and a polyamine salt collector, wherein:

[0022] The quaternary ammonium salt collector includes one or more of dodecyltrimethylammonium chloride, alkylbenzylpyridine and imidazoline quaternary ammonium salt;

[0023] The linear alkylamine salt collector includes one or more of dodecylamine hydrochloride, tetradecylamine hydrochloride and hexadecylamine hydrochloride;

[0024] The tertiary amine salt collector includes one or more of N,N-diethyldodecylamine, N,N-dibenzyldodecylamine and hexadecylmorpholine;

[0025] The polyamine salt collector includes one or more of N-dodecylethylenediamine, N-dodecyl-1,3-propylenediamine and undecylethylenediamine.

[0026] In one embodiment, in step S10, the auxiliary agent includes a foaming agent and an inhibitor, wherein:

[0027] The foaming agent includes one or more of pine oil, octanol and methyl isobutyl carbinol; and / or,

[0028] The inhibitor comprises one or more of corn starch, naphthalene-based dispersants, and metal salts; and / or,

[0029] The mass ratio of the raw coal to the inhibitor is 100:(0.01-0.5); and / or,

[0030] The mass ratio of the raw coal to the foaming agent is 100:(0.005-0.1).

[0031] In one embodiment, in step S10, the mass ratio of the raw coal to the silicon collector is 100:(0.01-0.4); and / or,

[0032] In step S20, the water content of the aluminum-rich coal product after centrifugal sedimentation is 40% to 60%; and / or,

[0033] In step S20, the water content of the aluminum-rich coal product after the filter press treatment is 10% to 30%; and / or,

[0034] In step S20, the water content of the coal cake is 0.1% to 10%; and / or,

[0035] In step S20, the rotation speed of the centrifugal sedimentation is 1000 r / min to 5000 r / min; and / or,

[0036] In step S20, the filtration is performed using a plate and frame filter press; and / or,

[0037] In step S20, the drying temperature is 100° C. to 180° C.; and / or,

[0038] In step S20, the drying time is 2 hours to 6 hours; and / or,

[0039] In step S30, the combustion temperature is 600°C to 1000°C; and / or,

[0040] In step S30, the ignition loss of the high-alumina fly ash is 6% to 12%.

[0041] The present invention also provides a method for extracting aluminum from aluminum-rich coal, the method for extracting aluminum from aluminum-rich coal comprising the following steps:

[0042] According to the above-mentioned production method of high-aluminum fly ash, high-aluminum fly ash is obtained;

[0043] Aluminum is extracted from the high-aluminum fly ash to obtain alumina.

[0044] In one embodiment, the step of extracting aluminum from the high-aluminum fly ash to obtain aluminum oxide comprises:

[0045] The high-alumina fly ash, limestone and water are mixed to obtain a mixed slurry, and the mixed slurry is sintered to obtain clinker;

[0046] The clinker is mixed with a sodium carbonate solution and leached to obtain a sodium aluminate solution;

[0047] Adding saturated limestone emulsion to the sodium aluminate solution, stirring and standing, and filtering to obtain sodium aluminate concentrate;

[0048] Carbon dioxide gas is introduced into the sodium aluminate semen to perform carbonation decomposition until the pH value reaches 10 to 10.5, and then the solid matter is obtained by filtering;

[0049] The solid material is washed and roasted to obtain alumina.

[0050] In one embodiment, the mass ratio of the high-alumina fly ash to the limestone is 1:(1-7); and / or,

[0051] The sintering temperature is 900° C. to 1400° C.; and / or,

[0052] The mass ratio of the clinker to the sodium carbonate solution is 1:(3-12); and / or,

[0053] The mass percentage concentration of the sodium carbonate solution is 5% to 20%; and / or,

[0054] The leaching temperature is 30°C to 100°C; and / or,

[0055] The temperature of the carbonation decomposition is 20°C to 100°C.

[0056] In the technical solution provided by the present invention, aluminum-rich coal is used as raw material, and the aluminum-rich coal is subjected to reverse flotation desiliconization, silicon minerals are floated out and enriched in the concentrate, aluminum minerals and coal particles are enriched in the tailings, and the tailings are collected to obtain an aluminum-rich coal product, so as to achieve desiliconization of the aluminum-rich coal; the aluminum-rich coal product after desiliconization is subjected to centrifugal sedimentation, filter pressing, and drying to obtain a coal cake with a low water content, which is convenient for combustion in subsequent processes; the fly ash obtained after the combustion of the coal cake not only has a high aluminum-silicon ratio of 4-10, but also the fly ash with the high aluminum-silicon ratio is used to extract aluminum oxide, which can improve the recovery rate of aluminum oxide. DETAILED DESCRIPTION

[0057] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0058] Fly ash is a fine solid particle collected from the flue gas generated during the coal combustion process. Its main components are mullite and amorphous silicon dioxide. It is one of the bulk industrial solid wastes in my country and is mainly used in building materials such as cement concrete. More than 85% of fly ash is composed of alumina and silicon dioxide, and the aluminum-silicon ratio, that is, the mass ratio of aluminum oxide to silicon dioxide in fly ash, is about 0.8.

[0059] Since the aluminum-silicon ratio is the most important parameter to measure the quality of bauxite, and the characteristics of high aluminum and low silicon in aluminum-rich coal have the potential for aluminum extraction, extracting alumina from fly ash becomes another option besides extracting aluminum from bauxite.

[0060] However, the aluminum-silicon ratio in fly ash not only affects the amount of raw materials used in the aluminum extraction process, but also affects the recovery rate of alumina. Therefore, how to improve the aluminum-silicon ratio in fly ash is an important issue.

[0061] In view of this, the present invention proposes a method for producing high-aluminum fly ash, aiming to solve the problem of low aluminum-silicon ratio in fly ash after burning existing aluminum-rich coal.

[0062] The production method of high-aluminum fly ash provided by the present invention comprises the following steps:

[0063] S10, mixing the raw coal with the silicon collector and the auxiliary agent, performing reverse flotation, collecting the tailings, and obtaining an aluminum-rich coal product;

[0064] S20, subjecting the aluminum-rich coal product to centrifugal sedimentation, filter pressing, and drying to obtain coal cakes;

[0065] S30, burning the coal cakes to obtain high-aluminum fly ash.

[0066] In the technical solution provided by the present invention, aluminum-rich coal is used as raw material, and the aluminum-rich coal is subjected to reverse flotation desiliconization, silicon minerals are floated out and enriched in the concentrate, aluminum minerals and coal particles are enriched in the tailings, and the tailings are collected to obtain an aluminum-rich coal product, so as to achieve desiliconization of the aluminum-rich coal; the aluminum-rich coal product after desiliconization is subjected to centrifugal sedimentation, filter pressing, and drying to obtain a coal cake with a low water content, which is convenient for combustion in subsequent processes; the fly ash obtained after the combustion of the coal cake not only has a high aluminum-silicon ratio of 4-10, but also the fly ash with the high aluminum-silicon ratio is used to extract aluminum oxide, which can improve the recovery rate of aluminum oxide.

[0067] It should be noted that the raw coal is aluminum-rich coal (high-aluminum coal), in which the aluminum oxide content is relatively high. High-aluminum coal is found in Inner Mongolia, Ningxia, Shanxi, Henan, Hebei and other places. Taking the Jungar coal in Inner Mongolia as an example, the average aluminum oxide content in the No. 6 coal seam of the Heidaigou open-pit mine and the Har Usu open-pit mine is 9.30% and 8.47% respectively, which is higher than the Chinese coal average of 5.98%, and the average silicon dioxide content is 4.48% and 4.06% respectively, which is lower than the Chinese coal average of 8.47%. The aluminum-silicon ratio is the most important parameter for measuring the quality of bauxite. The high aluminum and low silicon characteristics of high-aluminum coal make it have the potential for aluminum extraction.

[0068] Taking Jungar coal as an example, its inorganic minerals are mainly two kinds of aluminum-containing minerals, kaolinite and boehmite. Under a polarizing microscope, it can be observed that boehmite exists in two forms, intergrowth with kaolinite laminae or in agglomerate form. Among them, the agglomerate form of boehmite is conducive to the full dissociation of the two.

[0069] Directly mixing the raw coal with the collector and the auxiliary agent for reverse flotation may result in poor flotation effect due to the large size of the coal blocks. Therefore, the raw coal may be crushed and ground before reverse flotation. In some embodiments, step S10 may include:

[0070] The raw coal is crushed and ground to obtain raw coal particles. By crushing the raw coal, the particle size distribution of the coal sample can be accurately controlled, and the combustible body and various minerals can be fully dissociated.

[0071] Mixing the raw coal particles and water, shearing and stirring, to obtain a raw coal particle suspension;

[0072] The pH value of the raw coal particle suspension is adjusted to 3-12 by using a pH regulator, a silicon collector and an auxiliary agent are mixed with the raw coal particle suspension, reverse flotation is performed, and tailings are collected to obtain an aluminum-rich coal product.

[0073] Furthermore, in order to improve the effect of reverse flotation, in some other embodiments, step S10 includes:

[0074] S101, crushing and grinding raw coal to obtain raw coal particles;

[0075] By crushing the raw coal, the particle size distribution of the coal sample can be accurately controlled, and the combustible material and various minerals can be fully dissociated.

[0076] S02, mixing the raw coal particles and water to obtain a mixed solution, adjusting the pH of the mixed solution to 3-12 with a pH adjuster, mixing a silicon collector with the mixed solution, and shearing and stirring to obtain a raw coal particle suspension;

[0077] S103, mixing the raw coal particle suspension with a silicon collector and an auxiliary agent, performing reverse flotation, collecting tailings, and obtaining an aluminum-rich coal product.

[0078] By mixing raw coal particles with water and shearing and stirring, the combustible components and inorganic mineral components in the coal particles are fully dispersed and suspended in the solution, and the mixing uniformity of the materials in the solution is improved, making the material particles finer and more dispersed.

[0079] Among them, the silicon collector added before shear stirring is adsorbed on the surface of the silicon mineral through electrostatic force or hydrogen bonding, which changes the surface properties of the silicon mineral from hydrophilic to hydrophobic, thereby facilitating the silicon mineral to be captured by bubbles and floated in the subsequent flotation process.

[0080] When the raw coal particles are mixed with water, some silicon collectors are first added for modification, and shearing and stirring are performed together. In the subsequent flotation process, silicon collectors are added for separation and strengthening, so that better capture and flotation effects can be obtained. In addition, shearing and stirring increase the probability of interaction and collision between silicon collectors and particles, thus achieving better capture and flotation effects.

[0081] In addition, the amount of silicon collector added before shear stirring will also affect the capture flotation effect. The ratio of the mass of the silicon collector in step S102 to the mass of the silicon collector in step S103 is (2-5): (5-8). Specifically, the mass ratio of the silicon collector added in the previous and next steps can be 2:8, 3:7, 4:6, 5:5, etc. Adding a small amount of collector during pre-mineralization in step S102 and adding a large amount of collector during flotation in step S103 can improve the flotation effect.

[0082] In some embodiments, the volume average particle size Dv90 of the raw coal particles is ≤300 meshes, so that the combustible body and various minerals are fully dissociated, and can be fully mixed with water and silicon collectors when mixed, thereby improving the modification effect of the silicon collector. It should be noted that the particle size corresponding to the cumulative particle size distribution percentage of the raw coal particles reaching 90% is Dv90.

[0083] In some embodiments, the mass proportion of the raw coal particles in the raw coal particle suspension is 5% to 20%; specifically, the mass proportion of the raw coal particles can be 5%, 10%, 15%, 20%, etc. By controlling the mass proportion of the raw coal particles in the raw coal particle suspension, the raw coal particles can be better dispersed in water.

[0084] In some embodiments, the pH regulator includes one or more of hydrochloric acid, sulfuric acid, nitric acid, calcium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate, and the mass of the pH regulator is 0.01% to 1% of the mass of the raw coal particles in the raw coal particle suspension to control the pH value of the mixed solution during reverse flotation to 3 to 12. The pH regulator can adjust the pH of the pulp, thereby controlling the chemical composition of the pulp and the surface characteristics of the ore particles and improving the flotation effect.

[0085] In some embodiments, the shear stirring speed is 8000s -1 ~20,000s -1 The shear stirring time is 1 min to 20 min. Controlling the shear stirring conditions within the above range can make the raw coal particles have a better dispersion effect.

[0086] It should be noted that the mixed liquid of the raw coal particles, water and the silicon collector can be sheared and stirred by a high shear disperser.

[0087] In some embodiments, the silicon collector includes an amine cationic collector, and the amine cationic collector includes one or more of a quaternary ammonium salt collector, a linear alkylamine salt collector, a tertiary amine salt collector, and a polyamine salt collector, wherein: the quaternary ammonium salt collector includes one or more of dodecyltrimethylammonium chloride, alkylbenzylpyridine, and imidazoline quaternary ammonium salt; the linear alkylamine salt collector includes one or more of dodecylamine hydrochloride, tetradecylamine hydrochloride, and hexadecylamine hydrochloride; the tertiary amine salt collector includes one or more of N,N-diethyldodecylamine, N,N-dibenzyldodecylamine, and hexadecylmorpholine; the polyamine salt collector includes one or more of N-dodecylethylenediamine, N-dodecyl-1,3-propylenediamine, and undecylethylenediamine. The above collector can selectively adsorb on the surface of silicon minerals, so that the silicon mineral particles are combined with foam, while the adsorption of other minerals such as aluminum minerals is weak, thereby achieving effective separation of silicon minerals from aluminum minerals. Preferably, straight-chain alkylamine salts are more selective for silicon-based minerals, thus having a better selection effect.

[0088] In some embodiments, the auxiliary agent includes a foaming agent and an inhibitor. The silicon collector strengthens the hydrophobicity of the silicon mineral surface through electrostatic force or hydrogen bonding, making the silicon mineral not easily wetted by water, so that it can be selectively enriched on the bubbles and float to the liquid surface to achieve separation from the aluminum mineral. The foaming agent is directional adsorbed and distributed on the water-gas interface, reducing the surface tension of the aqueous solution, so that the air filled into the water is dispersed into bubbles, and these bubbles are more stable, which helps to form stable bubbles during the reverse flotation process and provides a carrier for the floating of silicon minerals. The inhibitor can selectively increase the hydrophilicity of aluminum minerals such as diaspore, prevent the interaction between aluminum minerals and collectors, thereby inhibiting their floatability and avoiding being captured by the collector. The pH regulator can adjust the pH of the pulp, thereby controlling the chemical composition of the pulp and the surface characteristics of the mineral particles, and improving the flotation effect. In addition, the pH regulator can optimize the effects of the collector, foaming agent and inhibitor by adjusting the pH value of the pulp, thereby improving the efficiency and selectivity of reverse flotation desiliconization.

[0089] Among them, the foaming agent includes one or more of pine oil, octanol and methyl isobutyl carbinol; the mass ratio of the raw coal to the foaming agent is 100: (0.005-0.1); the inhibitor includes one or more of corn starch, naphthalene-based dispersants and metal salts; the mass ratio of the raw coal to the inhibitor is 100: (0.01-0.5).

[0090] The selection of the above-mentioned collector and the selection of the auxiliary agent can be used simultaneously or separately, and the present invention is not limited here. When corn starch is used as the inhibitor and dodecylamine hydrochloride is used as the collector, the flotation effect is better.

[0091] In some embodiments, in step S10, the mass ratio of the raw coal to the silicon collector is 100:(0.01-0.4). It should be noted that the amount of the silicon collector refers to the sum of the masses of the silicon collectors in S10. For example, when the mass ratio of the raw coal to the silicon collector is 100:0.04, 0.04 g of silicon collector is added for every 100 g of raw coal, which includes both the silicon collector added during pre-mineralization and the silicon collector added during flotation.

[0092] The silicon collector can be added before shear stirring for pre-mineralization, or added after shear stirring when the auxiliary agent is added for reverse flotation. The present invention is not limited here. It should be noted that compared with adding the silicon collector only after shear stirring when the auxiliary agent is added for reverse flotation, adding the silicon collector only before shear stirring or during shear stirring has a higher probability of interaction and collision between the silicon collector and the particles, so the flotation effect is better.

[0093] Furthermore, the collector is divided into two parts, and a part of the silicon collector is first added before or during shear stirring for pre-mineralization, and then the silicon collector is added when the auxiliary agent is added after shear stirring for reverse flotation. The addition of the collector during pre-mineralization can selectively modify the surface of the particles, and the collector added during the reverse flotation separation process can further promote the enrichment of the modified particles to the selected layer, thereby further improving the flotation effect.

[0094] In step S10, the raw coal particle suspension is mixed with a silicon collector and an auxiliary agent for reverse flotation, and silicon-containing minerals such as kaolinite and quartz in the raw coal particles are enriched and removed to obtain a silicon-rich product, while aluminum-containing boehmite and combustibles are discharged from the bottom of the separation tower to obtain an aluminum-rich coal product; the aluminum-rich coal product is used for combustion in subsequent processes to obtain fly ash, and the silicon-rich product can be recovered for silicon due to its high silicon content after combustion.

[0095] After reverse flotation pre-desiliconization treatment, the silicon mineral content in the aluminum-rich coal product is greatly reduced. The aluminum-rich coal product is burned to generate electricity. After the organic matter in the coal is burned out, sufficient energy can be released to generate electricity. The non-combustible minerals are mainly aluminum-containing minerals, which are converted into alumina after high-temperature oxidation to obtain fly ash with high aluminum content.

[0096] However, the aluminum-rich coal product obtained by reverse flotation has too high a moisture content and cannot be used directly for combustion. Therefore, the aluminum-rich coal product needs to be centrifuged to remove most of the moisture, and then subjected to filter press treatment to obtain a high-solid content coal product, which is then dried with hot air to obtain coal cakes with low moisture content, and then the coal cakes are burned.

[0097] Furthermore, in some embodiments, the water content of the coal cake is 0.1% to 10%; the water content of the aluminum-rich coal product after the filter press treatment is 10% to 30%; the water content of the aluminum-rich coal product after centrifugal sedimentation is 40% to 60%. By controlling the water content of each section, the drying uniformity and dryness of the obtained coal cake are improved, so that it can be better burned in the subsequent process and improve the combustion efficiency. Preferably, the water content of the coal cake is less than 8%, which is more conducive to the combustion of the subsequent process.

[0098] Furthermore, in some embodiments, the rotation speed of the centrifugal sedimentation is 1000r / min~5000r / min to obtain a better centrifugal sedimentation effect; the drying temperature is 100℃~180℃, and the drying time is 2h~6h. Within the above drying temperature and drying time range, a better drying effect can be obtained; in addition, the filtration can be performed using a plate and frame filter press.

[0099] Furthermore, during the combustion of the briquettes, the combustion temperature is 600-1000° C. Specifically, the combustion temperature may be 600° C., 700° C., 800° C., 900° C., 1000° C., etc. Combustion at the above temperature may make the combustibles in the briquettes burn as fully as possible.

[0100] Furthermore, the ignition loss of the fly ash is 6% to 12%. It should be noted that the ignition loss of the fly ash refers to the percentage of the difference between the mass of the fly ash before combustion and the mass of the fly ash after combustion as a percentage of the mass of the fly ash before combustion when the fly ash is fully burned to a constant weight. The smaller the ignition loss of the fly ash, the more fully the briquettes burn.

[0101] The present invention also provides a method for extracting aluminum from aluminum-rich coal, comprising the following steps:

[0102] According to the above-mentioned production method of high-aluminum fly ash, high-aluminum fly ash is obtained;

[0103] Aluminum is extracted from the high-aluminum fly ash to obtain alumina.

[0104] In the technical solution provided by the present invention, aluminum-rich coal is used as raw material, and the aluminum-rich coal is subjected to reverse flotation desiliconization, silicon minerals are floated out and enriched in the concentrate, aluminum minerals and coal particles are enriched in the tailings, and the tailings are collected to obtain an aluminum-rich coal product, so as to achieve desiliconization of the aluminum-rich coal; the aluminum-rich coal product after desiliconization is subjected to centrifugal sedimentation, filter pressing, and drying to obtain a coal cake with a low water content, which is convenient for combustion in subsequent processes; the fly ash obtained after the combustion of the coal cake not only has a high aluminum-silicon ratio of 4-10, but also the fly ash with the high aluminum-silicon ratio is used to extract aluminum oxide, which can improve the recovery rate of aluminum oxide.

[0105] It is understandable that the silicon content in the concentrate after flotation is very high, and centralized recovery and treatment of the fly ash after the combustion of the clean coal is conducive to the efficient recycling of silicon resources; secondly, the calorific value of the aluminum-rich coal after desiliconization increases, which can improve the combustion efficiency during combustion; in addition, the aluminum-silicon ratio in the high-aluminum fly ash formed after the desiliconized aluminum-rich coal is burned is greatly increased, thereby reducing the output of low-value by-products in the subsequent process of extracting alumina, reducing the discharge of wastewater and waste liquid, and making the process greener. Therefore, this application improves the aluminum-silicon ratio in aluminum-rich coal by reverse flotation, thereby increasing the aluminum-silicon ratio in fly ash, which can not only optimize the process of extracting aluminum oxide from aluminum-rich coal, but also significantly improve the economy of the aluminum recovery process.

[0106] After reverse flotation pre-desiliconization treatment, silicon minerals in coal can be fully removed to obtain coal with high aluminum content, and the calorific value can be increased by 10% to 20%, which can not only improve the efficiency of coal-fired power generation, but also the fly ash obtained after the coal cake is burned out has a high aluminum-silicon ratio of 4-10, and no acid leaching or alkali washing treatment is required. Aluminum can be directly extracted by limestone method, Bayer method or acid leaching method, which greatly saves operating costs and reduces the amount of sewage treatment, while reducing pollution to the environment. Therefore, the method for extracting aluminum from aluminum-rich coal provided by the present invention can improve the high processing cost and high-risk wastewater treatment problems faced by traditional fly ash aluminum extraction processes.

[0107] The method for extracting aluminum from the high-aluminum fly ash can adopt limestone sintering method, Bayer process and acid leaching method, etc.

[0108] In some embodiments, extracting aluminum from the high-aluminum fly ash comprises the following steps:

[0109] The fly ash, limestone and water are mixed to obtain a mixed slurry, and the mixed slurry is sintered to obtain clinker; under high temperature conditions, mullite (3Al 2 O 3 ·SiO 2 ), silicon dioxide (SiO 2 ) and limestone (Ca 2 CO 3 ) The sintered / calcined product lime (CaO) reacts to form calcium aluminate (12CaO·7Al 2 O 3 ) and dicalcium silicate (2CaO·SiO 2 ).

[0110] The clinker is mixed with a sodium carbonate solution and leached to obtain a sodium aluminate solution; the activated clinker (i.e., the product after sintering / calcining) is passed through a Na 2 CO 3 The solution is leached, calcium aluminate reacts with sodium carbonate to form sodium aluminate, and most of the dicalcium silicate is filtered out in the form of precipitation. About 2-3% of the dicalcium silicate reacts with sodium carbonate to form sodium silicate and enters the solution.

[0111] Saturated limestone emulsion is added to the sodium aluminate solution, stirred, allowed to stand, and then filtered to obtain sodium aluminate concentrate; the main component of the saturated limestone emulsion is calcium hydroxide (Ca(OH) 2 ), by adding calcium hydroxide (Ca(OH) 2 ) reacts with sodium silicate to form insoluble calcium feldspar (CaO·Al 2 O 3 ·2SiO 2 ) to remove sodium silicate.

[0112] Carbon dioxide gas is introduced into the sodium aluminate semen to perform carbonation decomposition, and when the pH value reaches 10 to 10.5, the solution is filtered to obtain a solid substance; the carbon dioxide reacts with hydroxide ions and aluminate ions in the sodium aluminate solution to generate aluminum hydroxide precipitate, which is filtered to obtain a solid aluminum hydroxide.

[0113] Subsequently, the solid material is washed and calcined to obtain alumina.

[0114] In some embodiments, the mass ratio of the high-aluminum fly ash to the limestone is 1:(1-7); specifically, the mass ratio of the high-aluminum fly ash to the limestone is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, etc. Within the above range, the aluminum oxide and silicon oxide in the fly ash can react more fully with the lime.

[0115] The mass ratio of the clinker to the sodium carbonate solution is 1:(3-12). The mass ratio of the clinker to the sodium carbonate solution within the above range can have a better leaching effect.

[0116] The concentration of the sodium carbonate solution is 5% to 20%. The sodium carbonate concentration within the above range can have a better leaching effect.

[0117] In some embodiments, the sintering temperature is 900°C to 1400°C; specifically, the sintering temperature can be 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, etc. Within the above temperature range, more limestone can be converted into calcium oxide and alumina and silicon oxide in fly ash can react more fully with calcium oxide.

[0118] In some embodiments, the leaching temperature is 30°C to 100°C; specifically, the leaching temperature can be 30°C, 40°C, 50°C, 80°C, 100°C, etc.

[0119] In some embodiments, the temperature of the carbonation decomposition is 20° C. to 100° C. Specifically, the temperature of the carbonation decomposition may be 20° C., 40° C., 50° C., 80° C., 100° C., etc. Within the above temperature range, the formation of aluminum hydroxide precipitation can be promoted.

[0120] In some other embodiments, the Bayer process or the acid leaching process may also be used to extract alumina.

[0121] The method for extracting aluminum from aluminum-rich coal provided by the present invention has the following beneficial effects:

[0122] 1. The inorganic mineral components in raw coal are mainly aluminum-containing minerals and silicon-containing minerals. The development of this process can get rid of excessive dependence on bauxite resources, make coal the main supply resource of aluminum, and ensure sufficient supply of raw materials.

[0123] 2. Combine coal reverse flotation pre-desiliconization treatment with combustion power generation and utilize fly ash aluminum extraction process to replace the acid leaching and alkali washing pre-desiliconization process of traditional fly ash aluminum extraction process, providing a new desiliconization idea for fly ash aluminum extraction process, while greatly reducing treatment costs and reducing wastewater treatment volume.

[0124] 3. The coal crushing and grinding process can increase the specific surface area of ​​the combustible body, and the reverse flotation pre-desiliconization process will increase the combustible body content of the clean coal, thereby improving the efficiency of coal-fired power generation.

[0125] 4. The reverse flotation pre-desiliconization process separates the aluminum-containing minerals and silicon-containing minerals in the inorganic minerals, and can realize the recycling of aluminum resources and silicon resources respectively.

[0126] 5. The aluminum-rich coal product after reverse flotation desiliconization treatment has a higher aluminum-silicon ratio in the fly ash obtained after combustion, which can significantly reduce the amount of limestone added during aluminum extraction, reduce the output of low-value by-product cement, reduce the discharge of wastewater and waste liquid, and significantly improve the economy of the aluminum recovery process, making the process greener.

[0127] 6. Compared with other desiliconization methods, this process does not require high-energy heating processes, nor does it require conventional acid leaching and alkali washing pre-desiliconization processes. It also improves the efficiency of coal-fired power generation. The process is simple, highly operable, and the overall recovery and processing cost is relatively low.

[0128] 7. The fly ash obtained through the coal flotation pre-desiliconization process after full combustion and heat release can increase its aluminum-silicon ratio by 4 to 10 times. At the same time, the thermal efficiency of the combustion process is improved and the ash emissions are reduced. Combined with the fly ash aluminum extraction process, the operating costs can be greatly reduced, ensuring the economy and greenness of the fly ash aluminum extraction process.

[0129] The present invention also proposes an application of the above-mentioned method for extracting aluminum from aluminum-rich coal in coal combustion power generation. The method for extracting aluminum from aluminum-rich coal provided by the present invention can, on the one hand, increase the aluminum-silicon ratio in fly ash, reduce the output of low-value byproduct cement and the generation of waste solid and waste liquid in the process of extracting aluminum from fly ash, and is conducive to the recycling of silicon; on the other hand, grinding can make the particle size of the combustible body finer, and flotation can increase the content of the combustible body. The combination of the two is conducive to improving the efficiency of coal-fired power generation when coal cakes are burned to produce fly ash. Compared with existing coal combustion power generation, the method provided by the present invention is more economical and more environmentally friendly.

[0130] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0131] Example 1

[0132] Provided is a method for producing high-aluminum fly ash, comprising the following steps:

[0133] S101, taking 100 g of dry-based Geer coal from Inner Mongolia Autonomous Region as raw coal (raw coal dry-based ash content is 15.84%), crushing the raw coal with a jaw crusher, and grinding it with a planetary ball mill until Dv90 is greater than 300 meshes, to obtain raw coal particles;

[0134] S102, mixing the above raw coal particles with water, adjusting the pH to 5.00 with hydrochloric acid, adding 0.01 g of dodecylamine hydrochloride, and using a high shear disperser at 12000 s -1 The raw coal particles were sheared and pre-mineralized at a speed of 3 minutes to obtain a raw coal particle suspension; (the mass proportion of the raw coal particles in the raw coal particle suspension is 10%).

[0135] S103. Mix the above raw coal particle suspension with 0.03g dodecylamine hydrochloride, 0.08g corn starch and 0.01mL 2-octanol in a single-slot flotation machine for flotation separation, collect the tailings, and obtain an aluminum-rich coal product; the silicon-rich product is dried as a floating material to a water content of 2.08%, with a mass of 38.2g and an ash content of 17.05%.

[0136] S20, centrifugally sedimenting, filtering and drying the aluminum-rich coal product to obtain coal cakes, wherein the water content of the coal cakes is 1.95%, the mass of the coal cakes is 60.9 g, and the ash content is 15.28%;

[0137] S30, burning the coal cake at 850° C. for 60 min to obtain high-aluminum fly ash (the fly ash ignition loss is 8%, and the aluminum-silicon ratio in the fly ash is 5.32).

[0138] Example 2

[0139] S101, taking 100 g of dry-based Geer coal from Inner Mongolia Autonomous Region as raw coal (raw coal dry-based ash content is 15.84%), crushing the raw coal with a jaw crusher, and grinding it with a planetary ball mill until Dv90 is greater than 300 meshes, to obtain raw coal particles;

[0140] S102, mixing the above raw coal particles with water, adjusting the pH to 5.00 with hydrochloric acid, adding 0.015 g of dodecylamine hydrochloride, and using a high shear disperser at 12000 s -1 The raw coal particles were sheared and pre-mineralized at a speed of 3 minutes to obtain a raw coal particle suspension; (the mass proportion of the raw coal particles in the raw coal particle suspension is 10%).

[0141] S103. Mix the above raw coal particle suspension with 0.025g dodecylamine hydrochloride, 0.08g corn starch and 0.01mL 2-octanol in a single-slot flotation machine for flotation separation, collect the tailings, and obtain an aluminum-rich coal product; the silicon-rich product is dried as a floating material to a water content of 2.03%, with a mass of 35.8g and an ash content of 17.66%.

[0142] S20, centrifugally sedimenting, filtering and drying the aluminum-rich coal product to obtain coal cakes, wherein the water content of the coal cakes is 1.88%, the mass of the coal cakes is 63.0 g, and the ash content is 15.11%;

[0143] S30, burning the coal cake at 850° C. for 60 min to obtain high-aluminum fly ash (the fly ash ignition loss is 7%, and the aluminum-silicon ratio in the fly ash is 5.19).

[0144] Example 3

[0145] Provided is a method for producing high-aluminum fly ash, comprising the following steps:

[0146] S101, taking 100 g of dry-based Geer coal from Inner Mongolia Autonomous Region as raw coal (raw coal dry-based ash content is 15.84%), crushing the raw coal with a jaw crusher, and grinding it with a planetary ball mill until Dv90 is greater than 300 meshes, to obtain raw coal particles;

[0147] S102, the raw coal particles and water are mixed, the pH is adjusted to 5.00 with hydrochloric acid, 0.02 g of dodecylamine hydrochloride is added, and the mixture is dispersed by a high shear disperser at 12000 s -1 The raw coal particles were sheared and dispersed at a speed of 30° for 3 minutes to obtain a raw coal particle suspension; (the mass proportion of the raw coal particles in the raw coal particle suspension is 10%).

[0148] S103. Mix the above raw coal particle suspension with 0.02g dodecylamine hydrochloride, 0.08g corn starch and 0.01mL 2-octanol in a single-slot flotation machine for flotation separation, collect the tailings, and obtain an aluminum-rich coal product; the silicon-rich product is dried as a floating material to a water content of 1.73%, with a mass of 34.6g and an ash content of 17.11%.

[0149] S20, centrifugally sedimenting, filtering and drying the aluminum-rich coal product to obtain coal cakes, wherein the water content of the coal cakes is 1.79%, the mass of the coal cakes is 64.7 g, and the ash content is 15.33%;

[0150] S30, burning the coal cake at 850° C. for 60 min to obtain high-aluminum fly ash (the fly ash ignition loss is 8%, and the aluminum-silicon ratio in the fly ash is 4.91).

[0151] Example 4

[0152] S101, taking 100 g of dry-based Geer coal from Inner Mongolia Autonomous Region as raw coal (raw coal dry-based ash content is 15.84%), crushing the raw coal with a jaw crusher, and grinding it with a planetary ball mill until Dv90 is greater than 300 meshes, to obtain raw coal particles;

[0153] S102, mixing the raw coal particles with water, adjusting the pH to 5.00 with hydrochloric acid, adding 0.03 g of dodecylamine hydrochloride, and dispersing the mixture at 12000 s with a high shear disperser. -1 The raw coal particles were sheared and pre-mineralized at a speed of 3 minutes to obtain a raw coal particle suspension; (the mass proportion of the raw coal particles in the raw coal particle suspension is 10%).

[0154] S103. Mix the above raw coal particle suspension with 0.01g dodecylamine hydrochloride, 0.08g corn starch and 0.01mL 2-octanol in a single-slot flotation machine for flotation separation, collect the tailings, and obtain an aluminum-rich coal product; the silicon-rich product is dried as a floating material to a water content of 1.88%, with a mass of 32.9g and an ash content of 17.45%.

[0155] S20, centrifugally sedimenting, filtering and drying the aluminum-rich coal product to obtain coal cakes, wherein the water content of the coal cakes is 1.89%, the mass of the coal cakes is 66.7 g, and the ash content is 15.14%;

[0156] S30, burning the coal cake at 850° C. for 60 min to obtain high-aluminum fly ash (the fly ash ignition loss is 8%, and the aluminum-silicon ratio in the fly ash is 4.88).

[0157] Example 5

[0158] Provided is a method for producing high-aluminum fly ash, comprising the following steps:

[0159] S10, taking 100 g of dry-based Geer coal from Inner Mongolia Autonomous Region as raw coal (raw coal dry-based ash content is 15.84%), crushing the raw coal with a jaw crusher, and grinding it with a planetary ball mill until Dv90 is greater than 300 meshes, to obtain raw coal particles;

[0160] The raw coal particles were mixed with water, the pH was adjusted to 5.00 with hydrochloric acid, 0.04 g of dodecylamine hydrochloride was added, and the mixture was dispersed in a high shear dispersing machine at 12000 s. -1 The raw coal particles were sheared and dispersed at a speed of 30° for 3 minutes to obtain a raw coal particle suspension; (the mass proportion of the raw coal particles in the raw coal particle suspension is 10%).

[0161] The raw coal particle suspension was mixed with 0.08g corn starch and 0.01mL 2-octanol in a single-slot flotation machine for flotation separation, and the tailings were collected to obtain an aluminum-rich coal product; the silicon-rich product was dried as a floating material to a moisture content of 1.97%, with a mass of 29.3g and an ash content of 17.91%.

[0162] S20, centrifugally sedimenting, filtering and drying the aluminum-rich coal product to obtain coal cakes, wherein the water content of the coal cakes is 1.97%, the mass of the coal cakes is 70.2g, and the ash content is 15.09%;

[0163] S30, burning the coal cake at 850° C. for 60 min to obtain high-aluminum fly ash (the fly ash ignition loss is 7%, and the aluminum-silicon ratio in the fly ash is 4.82).

[0164] Example 6

[0165] Provided is a method for producing high-aluminum fly ash, comprising the following steps:

[0166] S10, taking 100 g of dry-based Geer coal from Inner Mongolia Autonomous Region as raw coal (raw coal dry-based ash content is 15.84%), crushing the raw coal with a jaw crusher, and grinding it with a planetary ball mill until Dv90 is greater than 300 meshes, to obtain raw coal particles;

[0167] The raw coal particles and water are mixed and dispersed in a high shear disperser at 12000s. -1 The raw coal particles were sheared and dispersed at a speed of 30° for 3 minutes to obtain a raw coal particle suspension; (the mass proportion of the raw coal particles in the raw coal particle suspension is 10%).

[0168] The pH value of the raw coal particle suspension is adjusted to 5.00 with hydrochloric acid, and then mixed with 0.04g of dodecylamine hydrochloride, 0.08g of corn starch and 0.01mL of 2-octanol in a single-slot flotation machine for flotation separation. The tailings are collected to obtain an aluminum-rich coal product; the silicon-rich product is dried as a floating material to a water content of 1.77%, with a mass of 44.5g and an ash content of 16.03%.

[0169] S20, centrifugally sedimenting, filtering and drying the aluminum-rich coal product to obtain coal cakes, wherein the water content of the coal cakes is 1.83%, the mass of the coal cakes is 55.2 g, and the ash content is 15.75%;

[0170] S30, burning the coal cake at 850° C. for 60 min to obtain high-aluminum fly ash (the fly ash ignition loss is 9%, and the aluminum-silicon ratio in the fly ash is 4.51).

[0171] Example 7

[0172] A method for producing high-aluminum fly ash is provided, wherein the steps are the same as those of Example 6 except that the amount of dodecylamine hydrochloride added is changed to 0.01 g when the raw coal particle suspension is mixed with dodecylamine hydrochloride, corn starch and octanol in a single-tank flotation machine for flotation separation. (Wherein, the water content of the coal cake is 1.77%, the mass of the coal cake is 74.5 g, and the ash content is 15.79%; the aluminum-silicon ratio in the obtained fly ash is 3.01.)

[0173] Example 8

[0174] A method for producing high-aluminum fly ash is provided, wherein the steps are the same as those of Example 6 except that the amount of dodecylamine hydrochloride added is changed to 0.4 g when the raw coal particle suspension is mixed with dodecylamine hydrochloride, corn starch and octanol in a single-tank flotation machine for flotation separation. (Wherein, the water content of the coal cake is 1.84%, the mass of the coal cake is 43.4 g, and the ash content is 15.88%; the aluminum-silicon ratio in the obtained fly ash is 2.86.)

[0175] Example 9

[0176] 5.0042 g of high-alumina fly ash obtained in Example 1, 11.5008 g of limestone and water were mixed to obtain a mixed slurry, which was sintered at 1300° C. for 2 h to obtain clinker; the clinker was heated at 60° C. in a liquid-to-solid ratio of 8:1 in a 12% Na 2 CO 3 The solution was leached for 40 minutes, filtered to obtain a sodium aluminate solution; a saturated limestone emulsion was added to the obtained sodium aluminate at a volume ratio of 5%, stirred and allowed to stand for 20 minutes, and then filtered to obtain a sodium aluminate concentrate. At a temperature of 70°C, carbon dioxide gas was introduced into the sodium aluminate solution at a rate of 60 mL / min to perform carbonation decomposition until the pH reached 10.5, and then filtered to obtain an aluminum hydroxide precipitate; the aluminum hydroxide precipitate was washed and dried, and then calcined at 1200°C for 2 hours to obtain α-alumina (α-Al 2 O 3 ). The mass of the obtained aluminum oxide is 4.0139.

[0177] Comparative Example 1

[0178] Provided is a method for producing high-aluminum fly ash, comprising the following steps:

[0179] 100 g of dry standard Geer coal from Inner Mongolia Autonomous Region was taken as raw coal. After the raw coal was fully burned, the loss on ignition of fly ash was 13.8%, and the aluminum-silicon ratio in the fly ash was 1.2.

[0180] Since the aluminum-silicon ratio of fly ash is relatively low at this time, the fly ash is pre-desiliconized by sodium hydroxide alkali washing. In an alkaline solution with a NaOH mass concentration of 150g / L, the liquid-solid ratio is 3:1, and the temperature is 90℃. Chemical desiliconization is carried out for 3 hours, and then filtered and washed three times to obtain desiliconized fly ash; (the desiliconization rate reaches 26.87%, and the aluminum-silicon ratio in the desiliconized fly ash is increased to 2.01);

[0181] Comparative Example 2

[0182] 5.0027 g of fly ash obtained in Comparative Example 1, 11.5032 g of limestone and water were mixed to obtain a mixed slurry, and the mixed slurry was sintered at 1300° C. for 2 h to obtain a clinker; the clinker was heated at 60° C. in a liquid-to-solid ratio of 8:1 in a 12% Na 2 CO 3 The solution was leached for 40 minutes, filtered to obtain a sodium aluminate solution; a saturated limestone emulsion was added to the obtained sodium aluminate at a volume ratio of 5%, stirred and allowed to stand for 20 minutes, and then filtered to obtain a sodium aluminate solution. Carbon dioxide gas was introduced into the sodium aluminate solution at a temperature of 70°C for carbonation decomposition until the pH reached 10.5, and then filtered to obtain a solid substance; the solid substance was washed and roasted to obtain aluminum oxide. The mass of the obtained aluminum oxide was 2.8325g.

[0183] Performance Testing

[0184] 1. X-ray fluorescence spectroscopy was performed on the desiliconized aluminum-rich fly ashes in Examples 1 to 4 and Comparative Example 1 to obtain the aluminum-silicon ratio in each aluminum-rich fly ashes, as shown in Table 1.

[0185] Table 1 Aluminum-silicon ratio of aluminum-rich fly ash obtained in Examples 1 to 4 and Comparative Example 1

[0186]

[0187]

[0188] As can be seen from Table 1, the aluminum-silicon ratio of the high-aluminum fly ash obtained by the production method of high-aluminum fly ash used in Examples 1 to 8 of the present invention is higher than that of Comparative Example 1, indicating that the production method of high-aluminum fly ash provided by the present invention can increase the aluminum-silicon ratio in the fly ash;

[0189] In Examples 1 to 5, the collector was added before shear dispersion, and the aluminum-silicon ratio in the obtained fly ash was higher than that in Example 6, indicating that shear dispersion can further enhance the interaction between the collector and the particle surface, thereby improving the collection effect;

[0190] The aluminum-silicon ratio in the fly ash obtained in Examples 1 to 3 is higher than that in Examples 4 to 5, indicating that the mass ratio of the collector added during pre-mineralization to the collector added during reverse flotation is (2 to 5): (5 to 8), which can have a better collection effect.

[0191] 2. The alumina recovery rate of fly ash extraction and the amount of raw fly ash required to produce each ton of alumina in Example 9 and Comparative Example 2 were calculated. The results are shown in Table 2.

[0192] The calculation method of alumina recovery rate in aluminum extraction from fly ash is: mass of alumina / mass of alumina in aluminum-rich fly ash.

[0193] The calculation method for the amount of raw fly ash required to produce each ton of alumina is: 1 / (alumina content in aluminum-rich fly ash × alumina recovery rate of fly ash extraction).

[0194] Table 2 Related data of aluminum extraction from fly ash in Example 9 and Comparative Example 2

[0195]

[0196] As can be seen from Table 2, the production index of the method for extracting aluminum from aluminum-rich coal adopted in Example 9 of the present invention is significantly better than that of Comparative Example 2, which is specifically reflected in that: based on the recovery rate of aluminum oxide in extracting aluminum from fly ash, the recovery rate of aluminum oxide in Example 9 is 10.54% higher than that in Comparative Example 2, and based on the amount of raw fly ash required to produce each ton of aluminum oxide, the amount of fly ash required in Example 9 is 40.8% lower than that in Comparative Example 2. This shows that the method for extracting aluminum from aluminum-rich coal provided in this application can not only have a good desiliconization effect, but also improve the recovery rate of aluminum oxide, and can significantly reduce the energy consumption and the amount of wastewater and waste residue in the process by reducing the amount of raw materials required.

[0197] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for producing high-aluminum fly ash, characterized in that: The following steps are involved: S10, mixing the raw coal with the silicon collector and the auxiliary agent, performing reverse flotation, collecting the tailings, and obtaining an aluminum-rich coal product; S20, subjecting the aluminum-rich coal product to centrifugal sedimentation, filter pressing, and drying to obtain coal cakes; S30, burning the coal cakes to obtain high-aluminum fly ash.

2. The method for producing high-aluminum fly ash according to claim 1, characterized in that: Step S10 includes: S101, crushing and grinding raw coal to obtain raw coal particles; S102, mixing the raw coal particles and water to obtain a mixed solution, adjusting the pH of the mixed solution to 3-12 with a pH adjuster, mixing a silicon collector with the mixed solution, and shearing and stirring to obtain a raw coal particle suspension; S103, mixing the raw coal particle suspension with a silicon collector and an auxiliary agent, performing reverse flotation, collecting tailings, and obtaining an aluminum-rich coal product.

3. The method for producing high-aluminum fly ash according to claim 2, characterized in that: In step S101, the volume average particle size of the raw coal particles is Dv90≤300 mesh; and / or, In step S102, the mass proportion of the raw coal particles in the raw coal particle suspension is 5% to 20%; and / or, In step S102, the pH adjusting agent includes one or more of hydrochloric acid, sulfuric acid, nitric acid, calcium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; and / or, In step S102, the shear stirring speed is 8000s -1 ~20,000s -1 and / or, In step S102, the shear stirring time is 1 min to 20 min.

4. The method for producing high-aluminum fly ash according to claim 2, characterized in that: The ratio of the mass of the silicon collector in step S102 to the mass of the silicon collector in step S103 is (2-5):(5-8).

5. The method for producing high-aluminum fly ash according to any one of claims 1 to 4, characterized in that: The silicon collector includes an amine cationic collector, and the amine cationic collector includes one or more of a quaternary amine salt collector, a linear alkylamine salt collector, a tertiary amine salt collector, and a polyamine salt collector, wherein: The quaternary ammonium salt collector includes one or more of dodecyltrimethylammonium chloride, alkylbenzylpyridine and imidazoline quaternary ammonium salt; The linear alkylamine salt collector includes one or more of dodecylamine hydrochloride, tetradecylamine hydrochloride and hexadecylamine hydrochloride; The tertiary amine salt collector includes one or more of N,N-diethyldodecylamine, N,N-dibenzyldodecylamine and hexadecylmorpholine; The polyamine salt collector includes one or more of N-dodecylethylenediamine, N-dodecyl-1,3-propylenediamine and undecylethylenediamine.

6. The method for producing high-aluminum fly ash according to claim 5, characterized in that: In step S10, the auxiliary agent includes a foaming agent and an inhibitor, wherein: The foaming agent includes one or more of pine oil, octanol and methyl isobutyl carbinol; and / or, The inhibitor comprises one or more of corn starch, naphthalene-based dispersants, and metal salts; and / or, The mass ratio of the raw coal to the inhibitor is 100:(0.01-0.5); and / or, The mass ratio of the raw coal to the foaming agent is 100:(0.005-0.1).

7. The method for producing high-aluminum fly ash according to claim 1, characterized in that: In step S10, the mass ratio of the raw coal to the silicon collector is 100:(0.01-0.4); and / or, In step S20, the water content of the aluminum-rich coal product after centrifugal sedimentation is 40% to 60%; and / or, In step S20, the water content of the aluminum-rich coal product after the filter press treatment is 10% to 30%; and / or, In step S20, the water content of the coal cake is 0.1% to 10%; and / or, In step S20, the rotation speed of the centrifugal sedimentation is 1000 r / min to 5000 r / min; and / or, In step S20, the filtration is performed using a plate and frame filter press; and / or, In step S20, the drying temperature is 100° C. to 180° C.; and / or, In step S20, the drying time is 2 hours to 6 hours; and / or, In step S30, the combustion temperature is 600°C to 1000°C; and / or, In step S30, the ignition loss of the high-alumina fly ash is 6% to 12%.

8. A method for extracting aluminum from aluminum-rich coal, characterized in that: The following steps are involved: According to the method for producing high-aluminum fly ash according to any one of claims 1 to 7, high-aluminum fly ash is obtained; Aluminum is extracted from the high-aluminum fly ash to obtain alumina.

9. The method for extracting aluminum from aluminum-rich coal according to claim 8, characterized in that: The step of extracting aluminum from the high-aluminum fly ash to obtain aluminum oxide comprises: The high-alumina fly ash, limestone and water are mixed to obtain a mixed slurry, and the mixed slurry is sintered to obtain clinker; The clinker is mixed with a sodium carbonate solution and leached to obtain a sodium aluminate solution; Adding saturated limestone emulsion to the sodium aluminate solution, stirring and standing, and filtering to obtain sodium aluminate concentrate; Carbon dioxide gas is introduced into the sodium aluminate semen to perform carbonation decomposition until the pH value reaches 10 to 10.5, and then the solid matter is obtained by filtering; The solid material is washed and roasted to obtain alumina.

10. The method for extracting aluminum from aluminum-rich coal according to claim 9, characterized in that: The mass ratio of the high-alumina fly ash to the limestone is 1:(1-7); and / or, The sintering temperature is 900° C. to 1400° C.; and / or, The mass ratio of the clinker to the sodium carbonate solution is 1:(3-12); and / or, The mass percentage concentration of the sodium carbonate solution is 5% to 20%; and / or, The leaching temperature is 30°C to 100°C; and / or, The temperature of the carbonation decomposition is 20°C to 100°C.

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