Method for producing aluminum-containing material

Abstract

The present invention relates to a method for producing aluminum-containing materials, particularly aluminum oxyhydroxy chloride and alpha alumina. The method includes a step of supplying an aluminum-containing raw material and separating the aluminum-containing raw material to obtain a pregnant liquor. The pregnant liquor is concentrated to obtain a saturated aluminum solution, and a crystallization process is applied. The aluminum chloride hexahydrate crystal slurry is cooled, and the crystals are separated from the spent liquor. The aluminum chloride hexahydrate crystals are heated under a controlled air flow to obtain dehydrated aluminum oxyhydroxy chloride. Optionally, the aluminum chloride hexahydrate crystals may be dried under at least partial vacuum before being heated under a controlled air flow. The aluminum oxyhydroxy chloride may then be decomposed and calcined mainly to form alpha alumina.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an aluminum-containing material. In particular, the present invention relates to a method for manufacturing aluminium oxyhydroxychlorides and alpha alumina.

Background Art

[0002] Several manufacturing methods are known for producing aluminum oxide or alumina. These manufacturing methods are based on alkali extraction processes such as the Bayer process or acid extraction processes. In particular, acid extraction processes have been used for the extraction of aluminum from non-bauxite materials.

[0003] In 1927, the United States Bureau of Mines published a comparative study on the extraction of aluminum from non-bauxite substances such as kaolinitic clay using strong acids such as sulfuric acid, nitric acid, and hydrochloric acid.

[0004] In 1946, the United States Bureau of Mines published a paper describing the development of a hydrochloric acid process for manufacturing alumina from clay. The basic process is described in the above paper and subsequent publications as follows: · A step of treating an aluminum-containing material such as a kaolinitic material (by grinding, air suspension, etc.) as necessary to reduce the particle size and increase the aluminum content. · A step of roasting (also called calcination or thermal dehydration oxidation) the kaolinitic material to produce metakaolin that is more soluble in dilute acid than kaolin. · A step of decomposing (also known as leaching or acid dissolution) the aluminum-containing material with hydrochloric acid to form a slurry. · A step of filtering the slurry to separate the solid phase and the liquid phase, where the solid contains insoluble siliceous substances and the pregnant liquor contains a solution containing aluminum and soluble impurities. ·A step of precipitating aluminum chloride hexahydrate crystals (crystallization, recrystallization, and salting out are also synonymous) by the diffusion of hydrogen chloride gas, and crystallizing aluminum chloride hydrate (aluminum chloride hexahydrate). ·A step of firing (igniting, heating, decomposing, thermally decomposing, or hydrothermally decomposing are also synonymous) aluminum chloride hexahydrate to give alumina, and ·A step of recovering (recycling is also synonymous) hydrogen chloride for reuse as a leaching acid, a washing liquid, and a gas for crystallizing aluminum chloride hexahydrate.

[0005] Subsequent research has mainly focused on identifying the range of conditions at various stages of the entire alumina manufacturing process in order to optimize the hydrochloric acid extraction of alumina from kaolinite clay.

[0006] However, there are numerous problems in the prior art. For example, the particle size of alumina produced by the current method may be too large for some applications, in which case it is necessary to grind the alumina to the desired particle size. However, when using a grinding process, there is a risk of contamination with substances that are difficult to remove from the final product, and additional energy needs to be input into the system.

[0007] Furthermore, in the current manufacturing method, the residual chloride content may be high, and as a result, materials, especially aluminum chloride hexahydrate, may not easily pass through the reaction vessel, solidify and coat the surface of the reaction vessel, and the heating of the decomposing substances becomes insufficient and uneven. When gaseous hydrogen chloride is released during drying, the reaction vessel where thermal decomposition occurs may corrode, requiring expensive maintenance and the purchase of customized drying equipment.

[0008] Furthermore, although gaseous hydrogen chloride is valuable as a recyclable chemical substance, it is difficult to capture or recycle gaseous hydrogen chloride when producing aluminum oxide or alumina from clay, and existing methods such as those disclosed in JP2013 - 203598 require a temperature higher than the optimal temperature for capture.

[0009] Furthermore, aluminum chloride hexahydrate, which is an intermediate reaction product, is hygroscopic, unstable, adhesive, and has extremely poor fluidity. It may release gaseous hydrogen chloride during storage, which is dangerous to the human body and highly corrosive.

[0010] Furthermore, in the prior art process, contaminants such as chromium, magnesium, and phosphorus cannot be effectively reduced to the level of high-purity alumina (purity exceeding 99.99%) required by users. Such contaminants are commonly found in aluminum-containing raw materials having a sufficient aluminum content for producing alumina. It is clear that when prior art documents are referred to in this specification, it is not admitted that such documents constitute a part of the common general knowledge in the relevant technical field in Australia or other countries.

Prior Art Documents

Non-Patent Documents

[0011]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0012] Embodiments of the present invention provide a method for manufacturing an aluminum-containing material that can at least partially solve one or more of the above-mentioned problems or defects, or provide useful options or commercial options for the general public.

[0013] As used herein, the term "oxyhydroxychlorides" is intended to refer to intermediate products formed by heating aluminum chloride hexahydrate crystals at low temperatures during the formation of alumina. Oxyhydroxychlorides contain a mixture of dehydrated aluminum oxychloride species containing low concentrations of free chloride, are generally chemically stable, and have good fluidity.

[0014] As used herein, the term "at least partial vacuum" means that the pressure inside the container is lower compared to the pressure outside the container. It will be understood that the term "at least partial vacuum" generally refers to a pressure below atmospheric pressure.

[0015] As used herein, the term "calcination" is intended to refer to a heating process that causes dehydroxylation of a mineral-containing raw material. This is generally also referred to as firing or thermal dehydroxylation.

[0016] As used herein, the term "decomposition" is intended to refer to a solvent extraction process using strong acids or bases to decompose or leach minerals from a mineral-containing raw material. This is generally also referred to as leaching or acid dissolution.

[0017] As used herein, the term "precipitation" is intended to refer to a process in which solid substances are separated from a solution. This is generally also referred to as crystallization, recrystallization, or salting out.

[0018] As used herein, the term "firing" is intended to refer to a high-temperature heating process in which a mineral-containing substance is converted into an oxide form. This is generally also referred to as ignition, heating, decomposition, pyrolysis, or hydrothermal decomposition.

[0019] As used herein, the term "recovery" is intended to mean recovering a solvent for reuse. This is generally also referred to as recycling.

[0020] According to a first aspect of the present invention, there is provided a method for manufacturing an aluminum-containing material including the following steps. A step of supplying an aluminum-containing raw material; A step of separating the aluminum-containing raw material to obtain a pregnant solution; A step of concentrating the pregnant solution to obtain a saturated aluminum solution; A step of subjecting the saturated aluminum solution to a crystallization process, the crystallization process including: A step of heating the saturated aluminum solution; A step of diffusing gaseous hydrochloric acid into the saturated aluminum solution to form an aluminum chloride hexahydrate crystal slurry; A step of separating aluminum chloride hexahydrate crystals from the aluminum chloride hexahydrate crystal slurry to form a spent solution, and A step of heating the aluminum chloride hexahydrate crystals under a controlled air flow at a temperature of about 100°C to about 350°C to obtain dehydrated aluminum oxyhydroxy chloride.

[0021] It will be understood that the term "dehydrated aluminum oxyhydroxy chloride" is intended to refer to aluminum oxyhydroxy chloride from which at least some of the water has been removed. Any suitable amount of water may be removed to form the dehydrated aluminum oxyhydroxy chloride. For example, in some embodiments of the present invention, at least 10% w / w of the water associated with the aluminum oxyhydroxy chloride is removed to form the dehydrated aluminum oxyhydroxy chloride. More preferably, at least 25% w / w of the water associated with the aluminum oxyhydroxy chloride is removed to form the dehydrated aluminum oxyhydroxy chloride. More preferably, at least 50% w / w of the water associated with the aluminum oxyhydroxy chloride is removed to form the dehydrated aluminum oxyhydroxy chloride. More preferably, at least 75% w / w of the water associated with the aluminum oxyhydroxy chloride is removed to form the dehydrated aluminum oxyhydroxy chloride. More preferably, at least 90% w / w of the water associated with the aluminum oxyhydroxy chloride is removed to form the dehydrated aluminum oxyhydroxy chloride. In some embodiments, substantially all of the water associated with the aluminum oxyhydroxy chloride is removed to form the dehydrated aluminum oxyhydroxy chloride.

[0022] As described above, an aluminum-containing raw material can be prepared.

[0023] Any suitable type of aluminum-containing raw material can be used.

[0024] In some embodiments, the aluminum-containing raw material may be a source such as alumina, aluminum hydroxide, metallic aluminum, aluminum chloride hexahydrate, red mud, fly ash, aluminosilicate, kaolin, zeolite, feldspar, and the like.

[0025] In some embodiments, the aluminum-containing raw material may be roasted. In this case, it will be understood that the aluminum-containing raw material may have been subjected to a heating process to reduce impurities or to thermally dehydrate and oxidize the aluminum-containing raw material.

[0026] In other embodiments, the aluminum-containing raw material may be formed by dispersing the aluminum-containing raw material in a solvent.

[0027] Any suitable solvent can be used. Generally, the solvent may be sufficient to leach aluminum from the aluminum-containing raw material. For example, the solvent may be a strong acid such as hydrochloric acid, sulfuric acid, nitric acid, etc.

[0028] The aluminum-containing raw material may be at any suitable pulp concentration. For example, the aluminum-containing raw material may be at a pulp concentration of about 10%, about 15%, about 20%, or about 25%.

[0029] In a preferred embodiment, the aluminum-containing raw material may be at a pulp concentration of about 20%.

[0030] In some embodiments, the aluminum-containing raw material may be kaolin, which may be roasted to form metakaolin and then leached with hydrochloric acid to form the aluminum-containing raw material.

[0031] In some embodiments, the aluminum-containing raw material may be tailings or aluminum-containing waste, and may be leached with hydrochloric acid to extract aluminum.

[0032] As described above, the aluminum-containing raw material may be separated to obtain a pregnant solution.

[0033] The aluminum-containing raw material may be separated using any suitable method known in the art. Preferably, the separation method may be sufficient to separate the aluminum-containing raw material into pregnant liquor and solid residue. For example, the separation method may include a gravity sedimentation clarifier, sedimentation, decantation, centrifugation, filtration, and the like.

[0034] In some embodiments, the pregnant liquor may be purified.

[0035] The pregnant liquor may be purified or clarified using any suitable method known in the art. Preferably, the purification step may be sufficient to remove or reduce suspended solids such as fine precipitates and insoluble substances. In some embodiments, the pregnant liquor may be purified or clarified using a filtration process and / or a flocculant.

[0036] As shown, the pregnant liquor may be concentrated to obtain a saturated aluminum solution.

[0037] The pregnant liquor may be concentrated using any suitable method known in the art. Generally, the concentration method may be sufficient to increase the aluminum in the pregnant liquor to the saturation point without precipitating the aluminum as aluminum chloride hexahydrate crystals. For example, the pregnant liquor may be concentrated by heating the pregnant liquor to its boiling point, or by heating the pregnant liquor below its boiling point and evaporating it. The concentrated pregnant liquor may undergo a purification step to remove insoluble contaminants such as silicon dioxide and other precipitates.

[0038] Preferably, the pregnant liquor may be concentrated to the saturation point by evaporation.

[0039] The pregnant liquor may be concentrated by boiling the pregnant liquor at a temperature of about 75°C to about 130°C, about 85°C to about 120°C, preferably about 95°C to about 110°C. In some embodiments, the pregnant liquor may be concentrated by boiling it at a temperature of about 95°C to about 110°C.

[0040] However, it will be understood by those skilled in the art that the temperature may vary depending on several factors including whether the concentration is carried out under vacuum, the amount and type of impurities, and the molar concentration of hydrochloric acid.

[0041] In some embodiments, the pregnant solution may be concentrated to an aluminum concentration of up to about 60,000 ppm.

[0042] Advantageously, concentrating the pregnant solution may reduce the consumption of gaseous hydrogen chloride per unit of aluminum chloride hexahydrate precipitated during crystallization. Further, at the same gas flow rate, the seed nucleation stage is shortened compared to the growth stage, and the amount of impurities incorporated from the pregnant solution during nucleation is reduced, making it easier to capture.

[0043] As shown, the saturated solution may be subjected to a crystallization process.

[0044] Any suitable crystallization process may be used. Generally, the crystallization process may be sufficient to precipitate aluminum chloride hexahydrate crystals and minimize the precipitation of impurities.

[0045] Preferably, the crystallization process may include heating a saturated aluminum solution, diffusing gaseous hydrochloric acid into the saturated aluminum solution, crystallizing aluminum chloride hexahydrate crystals, and forming a slurry thereof.

[0046] Any suitable type of gaseous hydrochloric acid may be used. For example, the gaseous hydrochloric acid may be purified, concentrated, etc.

[0047] The saturated aluminum solution may be added to a stirred reaction vessel. In some embodiments, the stirred reaction vessel may be heated.

[0048] The saturated aluminum solution may be preheated to any suitable temperature. For example, the saturated aluminum solution may be preheated at a temperature of about 30°C to about 100°C, about 40°C to about 90°C, about 50°C to about 80°C, about 60°C to about 70°C.

[0049] In some embodiments, the saturated aluminum solution may be preheated to a temperature of about 60°C to about 70°C.

[0050] Gaseous hydrochloric acid may be diffused into the saturated aluminum solution at a reaction temperature of about 40°C to about 120°C, about 50°C to about 110°C, about 60°C to about 100°C, preferably about 70°C to 90°C.

[0051] In some embodiments, gaseous hydrochloric acid may be diffused into the saturated aluminum solution at a reaction temperature maintained at about 60°C to about 70°C.

[0052] Gaseous hydrochloric acid may be diffused into the saturated aluminum solution until the hydrochloric acid concentration in the saturated aluminum solution reaches about 20 wt% to about 45 wt%, about 25 wt% to about 40 wt%, preferably about 30 wt% to about 35 wt%.

[0053] In some embodiments, gaseous hydrochloric acid may be diffused into the saturated aluminum solution until the hydrochloric acid concentration in the saturated aluminum solution reaches about 30 wt% to about 34 wt%.

[0054] Advantageously, preheating the saturated aluminum solution before the diffusion of gaseous hydrochloric acid slows down crystallization and reduces the nucleation rate, so that the amount of contaminants such as phosphorus and magnesium incorporated into the precipitate is reduced. Furthermore, preheating the saturated aluminum solution before the diffusion of gaseous hydrochloric acid increases the purity achieved during crystallization and can reduce the number of required recrystallization steps.

[0055] In some embodiments, the slurry of aluminum chloride hexahydrate crystals may be subjected to one or more recrystallization steps. Generally, those skilled in the art will understand that recrystallization of the crystals formed by the crystallization method may be carried out, and impurities in the compound obtained from crystallization can be reduced or removed.

[0056] In this case, it is considered that the slurry of aluminum chloride hexahydrate crystals obtained from the crystallization of an aluminum chloride hexahydrate saturated solution may be subjected to one or more recrystallization steps before undergoing thermal decomposition.

[0057] The slurry of aluminum chloride hexahydrate crystals may be recrystallized using any suitable method known in the art. Generally, the recrystallization process may be sufficient to precipitate purified aluminum chloride hexahydrate crystals and minimize the precipitation of impurities.

[0058] The recrystallization process may include the steps of separating and washing the precipitated crystals, and then dissolving the washed precipitated crystals in a solvent (such as ultrapure water, demineralized water, etc.) to form a feed solution. The feed solution may undergo a purification step to remove insoluble contaminants such as silica. The feed solution may then be heated, gaseous hydrochloric acid diffuses, and aluminum chloride hexahydrate crystals may be precipitated.

[0059] In some embodiments, the aluminum chloride hexahydrate crystal slurry may be cooled before the aluminum chloride hexahydrate crystals are separated from the spent solution. Preferably, the aluminum chloride hexahydrate solution may be cooled during the final crystallization and / or recrystallization step.

[0060] The aluminum chloride hexahydrate solution may be cooled using any suitable method. For example, the aluminum chloride hexahydrate solution may be actively cooled, such as by refrigeration. Alternatively, the aluminum chloride hexahydrate solution may be cooled by removing the heat source and allowing the aluminum chloride hexahydrate solution to cool to ambient temperature over a period of time. Advantageously, cooling the aluminum chloride hexahydrate solution improves the recovery rate of hydrogen chloride.

[0061] The aluminum chloride hexahydrate solution may be cooled to any suitable temperature. Generally, the aluminum chloride hexahydrate solution may be cooled to a temperature sufficient for relatively small aluminum chloride hexahydrate crystals to crystallize without crystallizing impurities.

[0062] In some embodiments, the aluminum chloride hydroxide solution may be cooled to a temperature below about 0 °C. More preferably, the aluminum chloride hydroxide solution may be cooled to a temperature below about -5 °C. More preferably, the aluminum chloride hydroxide solution may be cooled to a temperature below about -10 °C. Even more preferably, the aluminum chloride hydroxide solution may be cooled to a temperature below about -15 °C. Even more preferably, the aluminum chloride hydroxide solution may be cooled to a temperature below about -20 °C. Most preferably, the aluminum chloride hydroxide solution may be cooled to a temperature below about -25 °C. The aluminum chloride hexahydrate solution may be stirred during cooling. In practice, it is believed that stirring the solution during cooling can avoid the formation of aggregates and promote the formation of smaller particles.

[0063] Advantageously, cooling the aluminum chloride hexahydrate solution to a sufficiently low temperature and stirring the solution during cooling produces crystals with a smaller particle size (less than about 10 μm as opposed to an average particle size of about 20 μm to about 100 μm) than conventional methods, and increases the nucleation rate rather than the crystal growth rate.

[0064] The precipitate may be separated using any suitable method known in the art. Preferably, the separation method may be sufficient to separate the precipitate from the spent liquid. For example, the separation method may include a gravity sedimentation clarifier, sedimentation, decantation, centrifugation, filtration, and the like.

[0065] The precipitate may be washed to separate aluminum chloride hexahydrate crystals from impurities in the precipitate.

[0066] The precipitate may be washed with any suitable washing liquid. Generally, the washing liquid may be sufficient to redissolve soluble contaminants and the like from the crystals. The washing liquid may also be sufficient to remove the entrained contaminated supernatant and replace it with a less contaminated washing liquid.

[0067] In some embodiments, the washing liquid may be hydrochloric acid, spent liquid, and the like. The washing liquid used to wash the precipitate obtained by crystallization of the saturated solution may be the same as or different from the washing liquid used to wash the precipitate obtained by recrystallization of the feed liquid.

[0068] The aluminum chloride hexahydrate crystals may be separated from excess hydrochloric acid using any suitable method known in the art. For example, the separation method may include a gravity sedimentation clarifier, sedimentation, decantation, centrifugation, filtration, and the like.

[0069] As shown, the aluminum chloride hexahydrate crystals may be heated under a controlled air flow at a temperature of about 100°C to about 350°C to obtain aluminum oxyhydroxy chloride.

[0070] The aluminum chloride hexahydrate crystals may be heated using any suitable method known in the art. Generally, the heating method may be sufficient to provide a heating profile that dries the aluminum chloride hexahydrate and produces dehydrated aluminum oxyhydroxy chloride.

[0071] Preferably, the aluminum chloride hexahydrate crystals may be heated under controlled airflow conditions. For example, the aluminum chloride hexahydrate crystals may be heated directly or indirectly. The heat source may include forced air dryers, flash dryers, fluid bed dryers, microwave ovens, rotary kilns, tunnel furnaces, fluid bed reactors, far infrared rays, high frequencies, etc. Those skilled in the art will understand that under controlled airflow conditions, air is introduced into the container to contact the aluminum chloride hexahydrate crystals and facilitate the removal of water and hydrochloric acid vapor from the container.

[0072] In some embodiments, the container may be heated. Preferably, the aluminum chloride hexahydrate crystals may be heated in a heated container under a heated and / or dried airflow.

[0073] The aluminum chloride hexahydrate crystals may be heated at any suitable holding temperature. However, those skilled in the art will understand that the holding temperature may vary depending on several factors, including the holding time, the state of the airflow, the amount and type of liquid present in the crystals, and the desired final properties of the aluminum oxyhydroxy chloride formed.

[0074] The aluminum chloride hexahydrate crystals may be heated at a holding temperature of about 100°C to about 350°C, about 150°C to about 280°C, about 170°C to about 250°C, preferably about 180°C to about 230°C. Most preferably, the aluminum chloride hexahydrate crystals may be heated at a holding temperature of about 230°C.

[0075] Preferably, the aluminum chloride hexahydrate crystals are heated under a controlled airflow at a temperature of about 180°C to 230°C to obtain dehydrated aluminum oxyhydroxy chloride.

[0076] In some embodiments, the aluminum chloride hexahydrate crystals may be heated at a holding temperature below about 230°C.

[0077] By heating aluminum chloride hexahydrate crystals at these relatively low drying temperatures, it is believed that gaseous hydrochloric acid can be recovered from the drying process using any suitable method. Recovering the gaseous hydrochloric acid may generate useful heat, thereby reducing the requirements for energy input while also making it possible to recover the reagent for further use.

[0078] Furthermore, by drying aluminum chloride hexahydrate crystals under a controlled air flow, the recovery rate of hydrochloric acid can be improved, and condensation of the acid on the reactor surface (which results in corrosion) can be reduced or eliminated.

[0079] To reach the holding temperature, any suitable rate of temperature increase (the rate of change of temperature over time) may be used. For example, the rate of temperature increase may be about 10 °C / min, about 20 °C / min, about 30 °C / min, about 40 °C / min, about 50 °C / min, about 75 °C / min, about 100 °C / min, or higher.

[0080] In practice, it is believed that the rate of temperature increase may be selected to reach the holding temperature as quickly as possible.

[0081] The aluminum chloride hexahydrate crystals may be heated at the holding temperature for any suitable period of time. However, it will be understood by those skilled in the art that the holding time may vary depending on several factors including the holding temperature, the state of the air flow, and the amount and type of liquid present in the crystals.

[0082] For example, the aluminum chloride hexahydrate crystals may be heated at the holding temperature for at least about 30 minutes, at least about 60 minutes, at least about 90 minutes, at least about 2 hours, at least about 3 hours, at least about 4 hours, at least about 5 hours, at least about 6 hours, or longer.

[0083] Preferably, the aluminum chloride hexahydrate crystals may be stirred while being heated under controlled airflow conditions. In practice, it is considered that when the crystals are stirred while being heated, the formed aggregates are decomposed, which can promote the reduction of the particle size of the crystals. Further, heating the aluminum chloride hexahydrate crystals under controlled airflow conditions can promote the deaggregation of the crystals and / or the reduction of the particle size by introducing high-speed air into the container. In other embodiments, the aluminum chloride hexahydrate crystals may undergo a particle size reduction process before, during, or after heating under controlled airflow conditions.

[0084] In some embodiments, the aluminum oxyhydroxy chloride formed by heating the aluminum chloride hexahydrate crystals contains residual chloride at a level of about 2 wt% to about 10 wt% of the aluminum oxyhydroxy chloride.

[0085] In some embodiments, the aluminum oxyhydroxy chloride contains particles that can pass through a mesh opening of up to about 10 μm, preferably up to about 5 μm, more preferably up to about 2 μm.

[0086] Advantageously, heating the aluminum chloride hexahydrate crystals under controlled airflow conditions causes condensation in the heating device, leading to the formation of solidified and adherent substances, and removes the entrained liquid that may lead to non-uniform drying and decomposition of the aluminum chloride hexahydrate crystals.

[0087] Advantageously, aluminum chloride hexahydrate is corrosive and hygroscopic and can release gaseous hydrogen chloride over time. Thus, if aluminum chloride hexahydrate decomposes to form dehydrated aluminum oxyhydroxy chloride, there is an advantage that a more stable alumina precursor can be obtained. Further, aluminum chloride hexahydrate easily absorbs ambient moisture, and as a result, can retain more chloride, making heating quite difficult and forming hard aggregates that result in uncontrollable variability. Further, dehydrated aluminum oxyhydroxy chloride is a free-flowing material that is easy to handle and may be stable even upon long-term storage.

[0088] Preferably, the method for producing an aluminum-containing material according to the first aspect of the present invention further includes the following steps. A step of drying aluminum chloride hexahydrate crystals at a temperature of about 50°C to 150°C under at least partial vacuum, and then heating the aluminum chloride hexahydrate crystals under a controlled air flow at a temperature of about 100°C to about 350°C to obtain dehydrated aluminum oxyhydroxy chloride.

[0089] The aluminum chloride hexahydrate crystals may be dried under any suitable pressure. Generally, partial vacuum may be sufficient to facilitate water removal by lowering the boiling point of water.

[0090] In some embodiments, the aluminum chloride hexahydrate crystals may be dried at a pressure of about 50 mBar to about 1000 mBar, more preferably about 100 mBar to about 900 mBar, more preferably about 150 mBar to about 800 mBar, more preferably about 200 mBar to about 700 mBar, even more preferably about 250 mBar to about 600 mBar, even more preferably about 300 mBar to about 500 mBar, and most preferably about 350 mBar to about 400 mBar.

[0091] The aluminum chloride hexahydrate crystals may be dried at a temperature of about 50°C to about 150°C, about 60°C to about 140°C, preferably about 80°C to about 130°C.

[0092] Preferably, the aluminum chloride hexahydrate crystals may be dried at a temperature of about 80°C to 130°C under at least partial vacuum.

[0093] In some embodiments, the aluminum chloride hexahydrate crystals contain residual chloride at a level of about 30 wt% to about 45 wt% of the aluminum chloride hexahydrate crystals after the step of drying the aluminum chloride hexahydrate crystals under at least partial vacuum.

[0094] In some embodiments, the aluminum chloride hexahydrate crystals are substantially free of residual moisture.

[0095] Preferably, the step of drying the aluminum chloride hexahydrate crystals at a temperature of about 50°C to 150°C under at least partial vacuum is performed after the step of cooling the aluminum chloride hexahydrate crystal slurry and separating the aluminum chloride hexahydrate crystals from the spent liquor, and before the step of heating the aluminum chloride hexahydrate crystals under a controlled air flow at a temperature of about 100°C to about 350°C to obtain dehydrated aluminum oxyhydroxy chloride.

[0096] In operation, heating the aluminum chloride hexahydrate crystals at low temperature under at least partial vacuum may promote the reduction of entrained liquid, including water, within the crystals and is thought to produce stabilized dehydrated aluminum chloride hexahydrate. The stabilized dehydrated aluminum chloride hexahydrate may then be dried to obtain aluminum oxyhydroxy chloride. In this case, it will be understood that the low temperature heating of the aluminum chloride hexahydrate crystals functions as a further pyrolysis step in the process of converting aluminum chloride hexahydrate to alpha alumina.

[0097] Advantageously, drying the aluminum chloride hexahydrate crystals at low temperature under partial vacuum to reduce the entrained liquid prior to drying the crystals at high temperature can improve the energy efficiency of the drying stage compared to using a direct thermal drying process.

[0098] Aluminum chloride hexahydrate crystals may be heated using any suitable method known in the art. Generally, the heating method may be sufficient to provide a heating profile that promotes the reduction of entrained liquid within the aluminum chloride hexahydrate crystals without decomposing the crystals. For example, the aluminum chloride hexahydrate crystals may be dried using a vacuum dryer, a microwave dryer, a microwave vacuum dryer, or other suitable indirect drying methods under vacuum.

[0099] In some embodiments of the present invention, the aluminum chloride hexahydrate crystals may be heated using a rotary kiln, a tunnel furnace, a fluidized bed reactor, microwave vacuum drying, far infrared, high frequency, etc.

[0100] According to a second aspect of the present invention, there is provided a method for producing an aluminum-containing material, comprising the following steps. Supplying an aluminum-containing raw material; Separating the aluminum-containing raw material to obtain a pregnant solution; Concentrating the pregnant solution to obtain a saturated aluminum solution; Subjecting the saturated aluminum solution to a crystallization process, the crystallization process comprising: Heating the saturated aluminum solution; Diffusing gaseous hydrochloric acid into the saturated aluminum solution to form an aluminum chloride hexahydrate crystal slurry; Separating aluminum chloride hexahydrate crystals from the aluminum chloride hexahydrate crystal slurry to form a spent solution; Drying the aluminum chloride hexahydrate crystals at a temperature of about 50°C to 150°C under at least partial vacuum; and Heating the aluminum chloride hexahydrate crystals under a controlled air flow at a temperature of about 100°C to about 350°C to obtain aluminum oxyhydroxy chloride.

[0101] Preferably, the method for producing an aluminum-containing material according to the first or second aspect of the present invention further comprises the following steps. Decomposing the aluminum oxyhydroxy chloride at a temperature of about 800°C to about 980°C to form mainly amorphous alumina; Firing the amorphous alumina at a temperature of about 1,100°C to about 1,300°C to obtain mainly alpha alumina.

[0102] As shown, an aluminum-containing material containing aluminum oxyhydroxy chloride may be decomposed at a temperature of about 800°C to about 980°C to form mainly amorphous alumina, and the amorphous alumina may be fired at a temperature of about 1,100°C to about 1,300°C to obtain mainly alpha alumina.

[0103] An aluminum-containing material containing aluminum oxyhydroxy chloride may be decomposed at a high temperature (e.g., by a rotary kiln, fluidized bed, etc.) and may transition to an alumina phase such as gamma alumina or amorphous alumina.

[0104] Aluminum oxyhydroxy chloride may be decomposed at any suitable temperature. Generally, the decomposition temperature may be a temperature sufficient to remove most of the residual chloride. However, those skilled in the art will understand that the decomposition temperature may vary depending on several factors including the decomposition time, heat transfer rate, particle size of the aluminum chloride hexahydrate crystals, and whether the container is agitated.

[0105] Aluminum oxyhydroxy chloride may be heated at a decomposition temperature of about 600°C to about 1,200°C, about 700°C to about 1,100°C, or about 800°C to about 1,000°C.

[0106] In some embodiments, aluminum oxyhydroxy chloride may be heated at a decomposition temperature of about 800°C.

[0107] Aluminum oxyhydroxy chloride may be heated at the decomposition temperature for any suitable time.

[0108] For example, aluminum oxyhydroxy chloride may be heated for at least about 30 minutes, at least about 60 minutes, at least about 90 minutes, at least about 2 hours, at least about 3 hours, at least about 4 hours, at least about 5 hours, at least about 6 hours, or more at the decomposition temperature.

[0109] In some embodiments, the step of decomposing the aluminum-containing material comprising aluminum oxyhydroxy chloride may include a step of controlling the humidity within the container. In practice, controlling the humidity of the container is thought to promote the removal of chloride prior to the firing step.

[0110] In some embodiments, the amorphous alumina and gamma alumina formed by decomposing the aluminum-containing material comprising aluminum oxyhydroxy chloride contain residual chloride at a level of about 1.5 wt% or less, preferably about 1.0 wt% or less, more preferably about 0.4 wt% or less of the amorphous alumina and gamma alumina.

[0111] Advantageously, reducing the residual level of chloride in the amorphous alumina and gamma alumina reduces the potential cause of corrosion of the container during firing. As a result, the options for materials used in the construction of containers, kilns, firing furnaces, etc. where thermal decomposition occurs are expanded.

[0112] Dividing the decomposition process into a low-temperature heating stage and a high-temperature decomposition stage can effectively divide the process into two pieces of equipment, and each piece of equipment can be designed to suit a narrower range of operating conditions, so the stress on each piece of equipment is reduced, and the possibility of equipment failure is also reduced.

[0113] As shown, the amorphous alumina and gamma alumina may be fired at a high temperature (for example, using a rotary kiln, a fluidized bed, a firing furnace, etc.) to obtain alumina. Preferably, the resulting alumina may substantially comprise alpha alumina.

[0114] Amorphous alumina and gamma alumina may be fired at any suitable temperature. Generally, the firing temperature may be a temperature sufficient to convert amorphous alumina and gamma alumina to alpha alumina. However, those skilled in the art will understand that the firing temperature may vary depending on several factors, such as the residence time in the firing furnace, the capacity of the apparatus, and the sintering temperature.

[0115] Amorphous alumina and gamma alumina may be heated at a firing temperature of about 950 °C to about 1,300 °C, preferably about 1,100 °C to about 1,300 °C.

[0116] In some embodiments, amorphous alumina and gamma alumina may be heated at a firing temperature of about 1,100 °C to about 1,300 °C.

[0117] Amorphous alumina and gamma alumina may be heated at the firing temperature for any suitable time.

[0118] For example, amorphous alumina and gamma alumina may be heated at the firing temperature for at least about 30 minutes, at least about 60 minutes, at least about 90 minutes, at least about 2 hours, at least about 3 hours, at least about 4 hours, or more.

[0119] In some embodiments, the step of firing amorphous alumina and gamma alumina may include a step of controlling the humidity within the container.

[0120] Preferably, the pregnant liquor may be concentrated to the saturation point by evaporation.

[0121] Preferably, the slurry of aluminum chloride hexahydrate crystals may be subjected to one or more recrystallization processes.

[0122] Advantageously, the method of the present invention provides improved contamination control in the production of high-purity alumina. In particular, the present invention provides improved control of impurities such as silica, phosphorus, chromium, magnesium, etc.

[0123] Furthermore, the method of the present invention provides improved control of particle size during the formation of aluminum chloride hexahydrate. Advantageously, improving the control of particle size reduces the need for post-firing treatments such as grinding that can introduce substantially non-removable contaminants. Additionally, reducing the need for post-firing treatments reduces the need for additional energy input into the system.

[0124] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the present invention.

[0125] References to the prior art herein do not admit or suggest in any way that the prior art forms part of the ordinary general knowledge and should not be so construed.

[0126] The preferred features, embodiments, and variations of the present invention can be understood from the following "Modes for Carrying Out the Invention", which provide sufficient information for those skilled in the art to practice the present invention. The "Modes for Carrying Out the Invention" should not be regarded as limiting the scope of the foregoing summary of the invention in any way. In the "Modes for Carrying Out the Invention", the following drawings are referred to.

Brief Description of the Drawings

[0127]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0128] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0129] A method (100) for producing an aluminum-containing material as shown in FIG. 1 will be described in detail herein. Preferably, the aluminum-containing material contains aluminum oxyhydroxy chloride.

[0130] In step 10, an aluminum-containing raw material is supplied.

[0131] Any suitable type of aluminum-containing raw material can be used.

[0132] In some embodiments, the aluminum-containing raw material may be a raw material such as alumina, aluminum hydroxide, metallic aluminum, aluminum chloride hexahydrate, red mud, fly ash, aluminosilicate, kaolin, zeolite, feldspar, etc.

[0133] The aluminum-containing raw material may be formed by dispersing the aluminum-containing raw material in a solvent.

[0134] Any suitable solvent can be used. Generally, the solvent may be sufficient to leach aluminum from the aluminum-containing raw material. For example, the solvent may be a strong acid such as hydrochloric acid, sulfuric acid, nitric acid, etc.

[0135] In step 20, the aluminum-containing raw material is separated to obtain a pregnant solution.

[0136] The aluminum-containing raw material may be separated using any suitable method known in the art. Preferably, the separation method may be sufficient to separate the aluminum-containing raw material into a pregnant solution and a solid residue. For example, the separation method may include a gravity sedimentation clarifier, sedimentation, decantation, centrifugation, filtration, etc.

[0137] In step 30, the precious liquid is concentrated to obtain a saturated aluminum solution.

[0138] Any suitable method known in the art may be used to concentrate the precious liquid. Generally, the concentration method may be sufficient to increase the aluminum in the precious liquid to the saturation point without precipitating aluminum as aluminum chloride hexahydrate crystals.

[0139] Preferably, the precious liquid may be concentrated to the saturation point by evaporation.

[0140] In some embodiments, the precious liquid may be concentrated by boiling the precious liquid at a temperature of about 95°C to about 110°C.

[0141] In some embodiments, the precious liquid may be concentrated to an aluminum concentration of about 60,000 ppm.

[0142] In step 40, the saturated solution may be subjected to a crystallization process.

[0143] Any suitable crystallization process may be used. Preferably, the crystallization process may include heating the saturated aluminum solution, diffusing gaseous hydrochloric acid into the saturated aluminum solution to cause crystallization of aluminum chloride hexahydrate crystals, and forming a slurry of the crystals.

[0144] In some embodiments, the saturated aluminum solution may be preheated to a temperature of about 60°C to about 70°C.

[0145] In some embodiments, gaseous hydrochloric acid maintained at a reaction temperature of about 60°C to about 70°C is diffused into the saturated aluminum solution.

[0146] In some embodiments, gaseous hydrochloric acid is diffused into the saturated aluminum solution until the hydrochloric acid concentration of the saturated aluminum solution reaches about 30 wt% to 34 wt%.

[0147] In some embodiments, the slurry of aluminum chloride hexahydrate crystals may be subjected to one or more recrystallization steps. In this case, it is considered that the slurry of aluminum chloride hexahydrate crystals obtained by crystallization of the aluminum chloride hexahydrate saturated solution may be subjected to one or more recrystallization steps before undergoing thermal decomposition.

[0148] The slurry of aluminum chloride hexahydrate crystals may be recrystallized using any suitable method known in the art. Preferably, the recrystallization process may include the steps of separating and washing the precipitated crystals, and then dissolving the washed precipitated crystals in a solvent (such as ultrapure water, demineralized water, etc.) to form a feed solution. The feed solution may undergo a purification step to remove insoluble contaminants such as silica. Then, the feed solution may be heated and gaseous hydrochloric acid may be diffused to precipitate aluminum chloride hexahydrate crystals.

[0149] In step 50, the slurry of aluminum chloride hexahydrate crystals may be cooled and the precipitated aluminum chloride hexahydrate crystals may be separated from the spent solution.

[0150] The slurry of aluminum chloride hexahydrate crystals may be cooled before the aluminum chloride hexahydrate crystals are separated from the spent solution. Preferably, the aluminum chloride hexahydrate solution may be cooled during the final crystallization step and / or the recrystallization step.

[0151] The aluminum chloride hexahydrate solution may be cooled to any suitable temperature. Preferably, the aluminum chloride hexahydrate solution may be cooled to less than about -10°C.

[0152] The aluminum chloride hexahydrate solution may be stirred during cooling. In practice, it is considered that stirring the solution during cooling can avoid the formation of aggregates and promote the formation of smaller particles.

[0153] Advantageously, when an aluminum chloride hexahydrate solution is cooled to a sufficiently low temperature and the solution is stirred during cooling, crystals having a smaller particle size than those obtained by the conventional method (less than about 10 μm as opposed to an average particle size of about 20 μm to about 100 μm) are produced, increasing the rate of nucleation rather than crystal growth.

[0154] The precipitate may be separated using any suitable method known in the art. Preferably, the separation method may be sufficient to separate the precipitate from the spent liquor. For example, the separation method may include a gravity settling clarifier, sedimentation, decantation, centrifugation, filtration, and the like.

[0155] The precipitate may be washed to separate the aluminum chloride hexahydrate crystals from the impurities in the precipitate.

[0156] The precipitate may be washed with any suitable washing liquid. Generally, the washing liquid may be sufficient to redissolve soluble contaminants and the like from the crystals. The washing liquid may be sufficient to remove the entrained contaminated supernatant and replace it with a less contaminated washing liquid.

[0157] In some embodiments, the washing liquid may be hydrochloric acid, the spent liquor, or the like. The washing liquid used to wash the precipitate obtained from the crystallization of the saturated solution may be the same as or different from the washing liquid used to wash the precipitate obtained from the recrystallization of the feed solution.

[0158] The aluminum chloride hexahydrate crystals may be separated from the excess hydrochloric acid using any suitable method known in the art. For example, the separation method may include a gravity settling clarifier, sedimentation, decantation, centrifugation, filtration, and the like.

[0159] In step 60, to obtain dehydrated aluminum oxyhydroxy chloride, the aluminum chloride hexahydrate crystals may be heated under a controlled air flow at a temperature of about 100 °C to about 350 °C.

[0160] Preferably, the aluminum chloride hexahydrate crystals may be heated under controlled air flow conditions. Preferably, the aluminum chloride hexahydrate crystals may be heated in a heated container under a heated air flow and / or a dried air flow.

[0161] The aluminum chloride hexahydrate crystals may be heated at any suitable holding temperature. Preferably, the aluminum chloride hexahydrate crystals are heated under a controlled air flow at a temperature of about 180 °C to 230 °C to obtain dehydrated aluminum oxyhydroxy chloride.

[0162] The aluminum chloride hexahydrate crystals may be heated at the holding temperature for any suitable time. Preferably, the aluminum chloride hexahydrate crystals may be stirred while being heated under controlled air flow conditions.

[0163] In some embodiments, the dehydrated aluminum oxyhydroxy chloride formed by heating the aluminum chloride hexahydrate crystals contains residual chloride at a level of about 2 wt% to about 10 wt% of aluminum oxyhydroxy chloride.

[0164] In some embodiments, the aluminum oxyhydroxy chloride contains particles that can pass through a mesh opening of up to about 10 μm, preferably up to about 5 μm, more preferably up to about 2 μm.

[0165] A method (200) for manufacturing an aluminum-containing material as shown in FIG. 2 will be described in detail here. Preferably, the aluminum-containing material mainly contains alpha alumina. The method shown in FIG. 2 and described herein is the same as the method shown in FIG. 1 and described herein, except that additional processing steps 80 and 90 are applied to the aluminum-containing material containing aluminum oxyhydroxy chloride. The method shown in FIG. 2 completely encompasses the method shown in FIG. 1. The aluminum oxyhydroxy chloride, which is an intermediate product in FIG. 2, may be the same as the final product in FIG. 1.

[0166] In this embodiment, the method (200) of the present invention provides a three-step pyrolysis for converting aluminum chloride hexahydrate to alpha alumina, and it will be understood that the three-step pyrolysis includes steps 60, 80, and 90.

[0167] In step 80, the aluminum-containing material comprising aluminum oxyhydroxy chloride may be decomposed at a temperature of about 800 °C to about 980 °C to form mainly amorphous alumina.

[0168] Aluminum oxyhydroxy chloride may be decomposed at any suitable temperature. Preferably, aluminum oxyhydroxy chloride may be heated at a decomposition temperature of about 800 °C to about 980 °C.

[0169] In some embodiments, the step of decomposing the aluminum-containing material comprising aluminum oxyhydroxy chloride may include a step of controlling the humidity inside the container.

[0170] In some embodiments, the amorphous alumina and gamma alumina formed by decomposing the aluminum-containing material comprising aluminum oxyhydroxy chloride contain less than about 1.5 wt%, preferably less than about 1.0 wt%, more preferably less than about 0.4 wt% of residual chloride of amorphous alumina and gamma alumina.

[0171] In step 90, the amorphous alumina and gamma alumina may be calcined at a high temperature to obtain alumina. Preferably, the obtained alumina may substantially comprise alpha alumina.

[0172] The amorphous alumina and gamma alumina may be calcined at any suitable temperature. Preferably, the amorphous alumina and gamma alumina may be heated at a calcination temperature of about 1,100 °C to about 1,300 °C.

[0173] A method (300) for producing an aluminum-containing material as shown in FIG. 3 will be described in detail here. Preferably, the aluminum-containing material contains aluminum oxyhydroxy chloride. As shown in FIG. 3 and described herein, the method is the same as the method shown in FIG. 1 and described herein, except that an additional processing step 70 is used to produce an aluminum-containing material containing aluminum oxyhydroxy chloride.

[0174] Before the heating step 60, a drying step 70 is used.

[0175] In step 70, aluminum chloride hexahydrate crystals are dried at a temperature of about 50°C to about 150°C under at least partial vacuum, and then the aluminum chloride hexahydrate crystals are heated under a controlled air flow at a temperature of about 100°C to about 350°C to obtain aluminum oxyhydroxy chloride.

[0176] Preferably, the aluminum chloride hexahydrate crystals may be dried at a pressure of about 50 mBar to about 1000 mBar.

[0177] Preferably, the aluminum chloride hexahydrate crystals may be dried at a temperature between about 80°C and about 130°C under at least partial vacuum.

[0178] In some embodiments, after the step of drying the aluminum chloride hexahydrate crystals under at least partial vacuum, the aluminum chloride hexahydrate crystals contain residual chloride at a level of about 30 wt% to about 45 wt% of the aluminum chloride hexahydrate crystals.

[0179] In some embodiments, the aluminum chloride hexahydrate crystals are substantially free of residual moisture.

[0180] During execution, when aluminum chloride hexahydrate crystals are heated at a low temperature under at least partial vacuum, it is possible to promote the reduction of the entrained liquid including water within the crystals, and a stabilized dehydrated aluminum chloride hexahydrate is produced, which is then dried to obtain aluminum oxyhydroxy chloride. Advantageously, the low-temperature drying step (step 70) under at least partial vacuum shortens the high-temperature drying time (step 60) of the aluminum chloride hexahydrate crystals and improves the energy efficiency compared to using a one-step drying process alone.

[0181] A method (400) for manufacturing an aluminum-containing material as shown in FIG. 4 will be described in detail below. Preferably, the aluminum-containing material mainly comprises alpha alumina. The method shown in FIG. 4 and described herein is the same as the method shown in FIG. 3 and described herein, except that an additional treatment steps 80 and 90 are applied to the aluminum-containing material including aluminum oxyhydroxy chloride. The method shown in FIG. 4 completely encompasses the method shown in FIG. 3. The intermediate product aluminum oxyhydroxy chloride in FIG. 4 may be the same as the final product in FIG. 3.

[0182] In this embodiment, it will be understood that the method (400) of the present invention provides a four-step thermal decomposition for converting aluminum chloride hexahydrate to alpha alumina, and the four-step thermal decomposition includes steps 60, 70, 80, and 90.

[0183] Steps 10, 20, 30, 40, 50, 60, 70 of the method shown in FIG. 4 correspond to steps 10, 20, 30, 40, 50, 60, 70 of the method shown in FIG. 3.

[0184] In step 80, the aluminum-containing material including aluminum oxyhydroxy chloride may be decomposed at a temperature of about 800 °C to about 980 °C to mainly form amorphous alumina.

[0185] In some embodiments, the step of decomposing the aluminum-containing material comprising aluminum oxyhydroxy chloride may include a step of controlling the humidity inside the container.

[0186] In some embodiments, the amorphous alumina and gamma alumina formed by decomposing the aluminum-containing material comprising aluminum oxyhydroxy chloride contain less than about 1.5% by weight, preferably less than about 1.0% by weight, more preferably less than about 0.4% by weight of residual chloride of the amorphous alumina and gamma alumina.

[0187] In step 90, in order to obtain alumina, the amorphous alumina and gamma alumina may be fired at a high temperature. Preferably, the obtained alumina may substantially contain alpha alumina.

[0188] The amorphous alumina and gamma alumina may be fired at any suitable temperature. Preferably, the amorphous alumina and gamma alumina may be heated at a firing temperature of about 1,100 °C to about 1,300 °C.

[0189] The alpha alumina may undergo one or more additional processing steps such as pelletizing, sintering, grinding, etc. to create a product having a specific density, particle size, and / or shape.

[0190] As used herein and in the claims (where applicable), the term "comprising" and its derivatives (including "comprises" and "comprise") include the recited individual amounts, but do not exclude the inclusion of one or more other amounts.

[0191] Throughout this specification, when reference is made to "one embodiment" or "an embodiment", it means that the particular features, structures, or characteristics described in connection with that embodiment are included in at least one embodiment of the invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner, in one or more combinations.

[0192] In accordance with statute, the invention is described in terms that are almost exclusively specific to structural or methodological features. It should be understood that the means described herein include preferred forms for carrying out the invention, but that the invention is not limited to the specific features shown or described. Accordingly, the invention is claimed as such, or in any modified form, within the appropriate scope of the appended claims (where applicable) as properly construed by those skilled in the art.

Claims

1. The process of supplying aluminum-containing raw materials, A step of separating the aluminum-containing raw material to obtain a noble liquid, The steps include: concentrating the aforementioned noble liquid to obtain a saturated aluminum solution, A step of subjecting the saturated aluminum solution to a crystallization process, wherein the crystallization process is: The steps include heating the saturated aluminum solution, The process involves diffusing gaseous hydrochloric acid into the saturated aluminum solution to form an aluminum chloride hexahydrate crystalline slurry. The process includes the step of separating aluminum chloride hexahydrate crystals from the aluminum chloride hexahydrate crystal slurry to form a used liquid, A step of heating the aluminum chloride hexahydrate crystals under a controlled airflow at a temperature of approximately 100°C to approximately 350°C to obtain dehydrated aluminum oxyhydroxycyclolide, A method for producing an aluminum-containing material.

2. The method for producing an aluminum-containing material according to claim 1, further comprising the steps of drying the aluminum chloride hexahydrate crystals at a temperature of about 50°C to 150°C under at least partial vacuum, and then heating the aluminum chloride hexahydrate crystals at a temperature of about 100°C to about 350°C under a controlled airflow to obtain the dehydrated aluminum oxyhydroxycyclolide.

3. A method for producing an aluminum-containing material according to claim 2, wherein the step of drying the aluminum chloride hexahydrate crystals at a temperature of about 50°C to 150°C under at least partial vacuum is performed using microwave vacuum drying.

4. The method for producing an aluminum-containing material according to claim 1, wherein the aluminum chloride hexahydrate crystal slurry is subjected to one or more recrystallization processes.

5. The method for producing an aluminum-containing material according to claim 1, wherein the aluminum-containing raw material includes an aluminum-containing substance comprising aluminum hydroxide, metallic aluminum, aluminum chloride hexahydrate, red clay, fly ash, mineral treatment waste flow, aluminosilicate, kaolin, zeolite, or feldspar.

6. The method for producing an aluminum-containing material according to claim 1, wherein the aluminum-containing raw material is formed by dispersing an aluminum-containing substance in a solvent.

7. The method for producing an aluminum-containing material according to claim 1, wherein the noble liquid is concentrated so that the aluminum concentration of the saturated aluminum solution is about 50,000 ppm to 70,000 ppm.

8. The method for producing an aluminum-containing material according to claim 1, wherein the saturated aluminum solution is preheated to a temperature of about 50°C to about 80°C.

9. A method for producing an aluminum-containing material according to claim 1, wherein gaseous hydrochloric acid is diffused into the saturated aluminum solution until the saturated aluminum solution reaches a hydrochloric acid concentration of about 30% to 35% by weight.

10. The method for producing an aluminum-containing material according to claim 1, wherein the aluminum chloride hexahydrate crystal slurry is cooled to a temperature of less than about -10°C before separating the aluminum chloride hexahydrate crystals from the used liquid.

11. A method for producing an aluminum-containing material according to claim 1, comprising stirring the aluminum chloride hexahydrate crystal slurry while it is being cooled to produce aluminum chloride hexahydrate crystals with a particle size of less than approximately 10 μm.

12. A method for producing an aluminum-containing material according to claim 1, wherein the aluminum chloride hexahydrate crystals are heated in a forced-air drying oven, a flash dryer, or a fluidized bed dryer.

13. A method for producing an aluminum-containing material according to claim 1, comprising heating the aluminum chloride hexahydrate crystals at a heating rate of at least about 75°C / min to reach a temperature at which aluminum oxyhydroxycyclolide can be obtained.

14. The method for producing an aluminum-containing material according to claim 1, wherein the aluminum chloride hexahydrate crystals are stirred during heating to promote the deaggregation and / or reduction of particle size of the crystals.

15. The method for producing an aluminum-containing material according to claim 1, wherein the aluminum oxyhydroxycyclolide formed by heating the aluminum chloride hexahydrate crystals contains residual chloride at a level of about 2% to about 12% by weight of the dehydrated aluminum oxyhydroxycyclolide.

16. The method according to claim 2, wherein the aluminum chloride hexahydrate crystals are dried under a pressure of about 250 mBar to about 600 mBar.

17. The method according to claim 2 or claim 16, wherein, after the step of drying the aluminum chloride hexahydrate crystals under at least partial vacuum, the aluminum chloride hexahydrate crystals contain residual chloride at a level of about 30% to about 45% by weight of the aluminum chloride hexahydrate crystals.

18. A step of obtaining dehydrated aluminum oxyhydroxycyclolide by the method of any one of Claims 1 to 17, A step of decomposing the aluminum oxyhydroxycyclolide at a temperature in the range of approximately 800°C to approximately 980°C to mainly form amorphous alumina, A process of firing the amorphous alumina at a temperature of approximately 1,100°C to approximately 1,300°C to obtain mainly alpha alumina, A method for producing an aluminum-containing material according to claim 1 or 2, further comprising:

19. The method according to claim 18, wherein the amorphous alumina and the gamma alumina contain residual chloride at a level of less than about 0.4% by weight.

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