1104results about "Aluminium oxide/hydroxide preparation" patented technology

The invention provides a method for producing aluminum oxide and co-producing active calcium silicate through high-alumina fly ash. The method comprises the following steps that: the high-alumina fly ash firstly reacts with a sodium hydroxide solution to carry out pre-desilication to obtain a liquid-phase desiliconized solution and a solid-phase desiliconized fly ash; lime cream is added to the liquid-phase desiliconized solution to carry out a causticization reaction, the resulting solid phase is active calcium silicate which is prepared through carrying out filter pressing, flash evaporation and drying to obtain the finished product; limestone and a sodium carbonate solution are added to the desiliconized fly ash to blend qualified raw slurry, then the blend qualified raw slurry is subjected to baking into the clinker, the liquid phase generated from dissolution of the clinker is a crude solution of sodium aluminate; the crude solution of the sodium aluminate is subjected to processes of first-stage deep desilication, second-stage deep desilication, carbonation, seed precipitation, baking and the like to obtain the metallurgical grade aluminum oxide meeting requirements. According to the present invention, the defects in the prior art are overcome; purposes of less material flow and small amount of slaggling are achieved; energy consumption, material consumption and production cost are relative low; extraction rate of the aluminum oxide is high; the calcium silicate with high added value is co-produced; the method provided by the present invention can be widely applicable for the field of chemical engineering.

The invention discloses a preparation method for aluminum oxide by a direct forming method. The method is characterized in that the aluminum oxide is directly formed by a wet filter cake, wherein pore volume is 0.3-0.8ml/g; a specific surface area is 150-300 m<2>/g; and crushing strength is 30-120 N/particle; the preparation process comprises the steps: a) meta-aluminate containing aluminum or a strong acid salt compound is neutralized with a precipitator solution at a temperature of 30-80 DEG C and pH of 6-9; accessory ingredient is added in a neutralizing process; mixture is aged for at least 10min after neutralizing; b) prepared aluminium hydroxide gel is washed by de-ionized water for 4-10 times; dosage of the de-ionized water for each time is 10-40 times of mass of a dried substrate of prepared aluminium hydroxide; a hydrated alumina filter cake is obtained after washing and filtering; content of the aluminium hydroxide in the filter cake is controlled to be 5-50%; and c) the accessory ingredient is added into one or various liquid in the step a) and step b); the filter cake after washing is formed by a normal forming method; and the formed filter cake is dried at a temperature of 80-120 DEG C and calcined at a temperature of 450-1000 DEG C to obtain a finished product of the aluminum oxide.

The invention provides a method for preparing aluminum oxide and other products from aluminiferous materials such as bauxite, high iron bauxite, alunite, kaoline, alumina, fly ash, coal gangue, aluminum ash, nepheline, clay and the like. The method comprises the following steps: (1) crushing, grinding and mixing the aluminiferous materials with ammonium sulfate and then roasting; (2) dissolving the roasted product (clinker aggregate) in water, and filtering to obtain aluminum ammonium sulfate solution and filter residues; (3) carrying out deferrization, aluminum deposition or recrystallization on the aluminium ammonum sulfate solution with ammonia to prepare aluminum oxide, and meanwhile, recycling the ammonium sulfate; (4) preparing silicon dioxide from the filter residues, and taking the remaining residues containing ferrum as the raw material for ironmaking. The method is suitable for treating various aluminiferous materials, has the advantages of simple technical process, simple equipment, no emission of solid, liquid and gas wastes, and no secondary pollution, and realizes the high-added-value green complex utilization of the aluminiferous materials such as bauxite, high ironbauxite, alunite, kaoline, alumina, fly ash, coal gangue, aluminum ash, nepheline, clay and the like.

A process for extracting aluminum oxide from powdered coal ash includes such steps as grinding, calcining, mixing with H2SO4 solution, heating while reaction for extracting aluminum oxide, boiling in water, concentrating, cooling while educing out aluminum sulfate crystals, heating for dewatering, heating for decomposing to obtain gamma-Al2O3, and further preparing metallurgy-class aluminum oxide.

The process of preparing alumina includes: the reaction of flyash from circular fluidizing bed and acid to obtain aluminum chloride solution, eliminating silicon impurity, concentrating to crystallize and heating to decompose and to obtain crude alumina product; reaction of crude alumina product and hot alkali solution to obtain sodium aluminate solution; eliminating iron, titanium and other impurity, adding aluminum hydroxide crystal seed into sodium aluminate solution for seed separating decomposition to obtain aluminum hydroxide precipitate; and final calcining aluminum hydroxide to obtain metallurgical alumina. The normal pressure process has no any cosolvent added, and the alumina product has Al2O3 content up to 98 %. The process has small sodium hydroxide consumption, reuse of most of sodium hydroxide, simple operation, low cost, low power consumption, capacity of reducing flyash pollution and other advantages.

Materials and associated processes for making the materials. For example the material may include alpha alumina crystalline whiskers. The process may include conducting the process as hydrothermal, and producing the whiskers to have a length to diameter aspect ratio of at least two.

The invention relates to a method to withdraw silicon and aluminum in sequence from coal ash; a NaOH solution with a mass concentration larger than 40 percent is used for leaching the coal ash, the silicon of the coal ash is dissolved in the form of sodium silicate, and after being separated, sodium silicate solutions and alkaline leaching residues with a ratio between aluminum and silicone more than or equal to 2 are produced; the dissolved sodium silicate solution is condensed into sodium silicate solutions of different concentrations, or used for preparing white carbon through a carbonation method; the alkaline residues are used for producing Al(OH)3 through a sodalime sintering method or limestone sintering method and further producing Al2O3, and the residues after the aluminum being extracted are made into stuff or used for producing concrete. The invention breakthroughs the original idea of directly extracting Al2O3 from the coal ash, and adopts the wholly novel technical route of extracting silicon first and aluminum secondly, thereby enhancing the aluminum silicon ratio of the alkali leached residues, simplifying the technique of extracting Al2O3, and increasing the extracting rate of aluminum from the coal ash.

The invention discloses a method for producing alumina by disposing and utilizing industrial solid wastes, in particular to a method for preparing alumina by fly ash, comprising the steps as follows: the fly ash is mechanically activated; the activated fly ash, water and concentrated sulfuric acid react in a reaction kettle under the conditions of heating and pressurizing; the solid is separated from the liquid after the temperature of the reaction is reduced so as to gain aluminium sulfate liquid; the aluminium sulfate liquid is evaporated, concentrated and cooled so as to precipitate aluminium sulphate crystals; the aluminium sulphate crystals are dehydrated and decomposed to gain gama-Al2O3 and SO3; coarse gama-Al2O3 is dissolved in alkaline solution; after the solid is separated from the liquid, the pure sodium aluminate solution is gained; aluminum hydroxide crystal seed is added to the sodium aluminate solution so as to precipitate the aluminum hydroxide; the coarse gama-Al2O3 can be prepared by circularly dissolving the seed-precipitated alkaline solution after vaporization-concentration; the metallurgical alumina can be gained by baking the prepared aluminum hydroxide. The method adds no additive, can lead the alumina in the fly ash to be effectively leached out with the leaching rate more than 90% and saves the energy resource.

The invention discloses a method for producing alumina and white carbon black by utilizing red mud and flyash, which is characterized by taking the flyash and the red mud as the raw materials, fully utilizing the resources of Al2O3, SiO2 and Na2O in the flyash and the red mud, mixing the flyash and the red mud with sodium hydroxide or sodium carbonate according to certain proportion and preparing the alumina and the white carbon black through calcining, acid leaching, concentrating, crystallizing, thermal decomposition, water washing, seed precipitation, roasting, etc. The acid in the process is recycled and the waste residues can be used as the raw materials of the cement and ironmaking. The method realizes changing wastes into valuables and changing harm into valuables and reduces the pollution of the red mud and the flyash to the environment. China is short of alumina resources. The development and utilization of the flyash and the red mud lay the foundation for sustainable development of the aluminum industry in China. The method is a new breakthrough in red mud resource utilization, is simple in the process flow of producing the alumina and the white carbon black, utilizes the wastes and is low in production cost.

The invention provides a method to extract aluminum oxide from a fly ash, and relates to a technological method which is to extract aluminum oxide from the fly ash and comprehensively utilize the residue after extracting aluminum oxide. The invention is characterized in the method which is as follows: ammonium sulfate is mixed into the fly ash to sintering, and the solid is dissolved to obtain the solution containing aluminum-ammonium sulfate; the solution is crystallized to form solid aluminium-ammonium sulfate; solid aluminium-ammonium sulfate reacts with ammonia gas to obtain aluminium hydroxide and ammonium sulfate, and aluminium hydroxide and ammonium sulfate are washed and filtrated to obtain solid aluminium hydroxide; solid aluminium hydroxide is calcined to obtain aluminum oxide; ammonium sulfate can be circularly used after being evaporated in the liquid phase. The ammonium sulfate which is used by the method of the invention is weak acidic, the corrosiveness on the equipment is small, and the ammonium sulfate can be used circularly. The whole process is easy to industrial application. The requirement of the corrosion resistance on the equipment is low. The amount of the residue is small which is beneficial to the comprehensive utilization of the residue after extracting the aluminum oxide.

The invention discloses a method for preparing spherical alumina particles by an alginic acid auxiliary forming method. The method includes the following steps of firstly, taking pseudo-boehmite, adding water for dispensing, and then adding a sodium alginate aqueous solution to stir to form a sodium-alginate-pseudo-boehmite suspension; secondly, dropping the sodium-alginate-pseudo-boehmite suspension into an aqueous solution of aluminum, calcium, barium, copper, zinc, manganese or cobalt metal ion, and forming alginic-acid-pseudo-boehmite rubber composite pellets in a gel mode; and thirdly, subjecting the alginic-acid-pseudo-boehmite rubber composite pellets to a washing by water, a drying and a calcination to obtain the spherical alumina particles. According to the method for preparing the spherical alumina particles, the forming of the particles is performed in mild aqueous phase, the energy consumption is low, the pollution is absent during a preparation process, the production efficiency is high, the specific surface area, the pore volume, the pore diameter and the metallic oxide content of the spherical alumina can be conveniently adjusted, the preparation process is simple, the operation is convenient, and the industrial production is easy to achieve.

A method of producing nanocrystalline ceramic powder by creating a plasma stream in a reactor vessel, and physically converting a ceramic precursor material into ceramic particles suspended in the vessel, using the plasma stream. A metallic reactant may additionally be introduced into the vessel using the plasma stream, wherein the metallic reactant forms ceramic particles having the same composition as the ceramic particles of the physical converting step. The plasma stream is created using an electrothermal gun. The gun may use a ceramic barrel which is eroded by the plasma stream. Alternatively (or additionally), the ceramic precursor material may be injected as particulates into the plasma stream, wherein the ceramic precursor particulates are micron-sized or larger. A novel electrothermal gun design may optionally use a replaceable insert constructed of the ceramic precursor material.

The disclosure related to a method for making a nanowire structure. The method includes fabricating a free-standing carbon nanotube structure, introducing reacting materials into the carbon nanotube structure, and activating the reacting materials to grow a nanowire structure.

The invention relates to a solid phase preparation method for gamma-alumina with gradient distribution holes. The method comprises: adopting a solid phase reaction to obtain a precursor ammonium aluminum carbonate hydroxide, and carrying out calcination to obtain gamma-alumina with a high specific surface area, gradient distribution holes and a large pore volume. The most prominent characteristic of the present invention comprises adopting a raw material solid phase reaction synthesis technology and controlling the property of the resulting gamma-alumina through synthesis conditions. In addition, the method of the present invention has characteristics of simpleness, easy operation, no requirement of addition of a pore-expanding agent, and cost saving, and is suitable for industrial mass production.

The invention discloses a method to produce highly pure Alumina powder. The steps are as follows: deploying Aluminium hydroxide which is produced in the process of manufacturing alumina using sintering process to be solution, disposing of impurity, adding seed crystal to prepare highly pure aluminium hydroxide; removing Na in the solution, getting highly pure bodhmite after hydrothermal synthesis; and after washing and baking, highly pure Alumina can be obtained. The cost is about 15 thousand per ton, which is far less than current market price, 40-60 thousand per ton. It can put into production in a large scale and it is easy to reach 1-5 thousand ton per year. With a low cost, no pollution and high purity (over 99.99 percent), the production is widely used in rare earth fluorescence materials, high voltage Na lamp and other relative special Alumina fine ceramics field.

The invention discloses a method for extracting high-purity alumina and silica gel from the flyash. The method includes calcining and activating the powdered coal at low temperature; water extracting the alumina; acid extracting the alumina and the silica gel; separating the alumina and the silica gel; separating the alumina and the iron; recycling and reutilizing the CO2 generated during the calcining and recycling the alkali, the sodium chloride, the acid and the water during the extractions. The extracted alumina and silica gel have high purity and are used as high added value products. The separation extraction rates of the alumina and the silica gel in the fly ash reach more than 90%. The residue amount obtained after extracting the alumina and the silica gel from the fly ash is less than 10% of the fly ash. The entire technological process is carried out under the normal pressure, therefore the method has low requirement for equipment. Since the CO2 generated during the calcining and the alkali and the acid used in the extraction can be reutilized, the method can realize zero discharge without secondary pollution.

A comprehensive utilization method of high-ferrum and low-grade bauxite belongs to the technical of metallurgy and is carried out according to the steps as follows: a large proportion of aluminium oxide is extracted through a Bayer process technology that excess lime is added, produced low-alkali red mud is pre-reduced through a coal-based rotary furnace process technology, then high-temperature melting separation of aluminium slag/ferrum is realized by adopting a ferrum bath oxygen coal jetting technology, formed aluminium slag generates calcium aluminate cement after being quenched and tempered, calcium aluminate cement slag is leached with low sodium carbonate solution, a part of leached crude solution and digestion slurry by the Bayer process are mixed and enter a Bayer process system to extract aluminium oxide, and the other part is desilicated and then is resolved in a carbonation manner, aluminum hydrate, which is the decomposition product, is conveyed to the Bayer process system as seed crystal, and resolved mother liquid is used for leaching calcium aluminate cement slag after being mixed. The method provided by the invention can not only ensure efficient dissociation extraction of ferrum and aluminium, but also be practicable in technology and economic benefit, thereby comprehensively utilizing high-ferrum bauxite resource of China effectively.

The invention discloses a preparation method for an alumina carrier, which includes the following steps: (1) dry pseudoboehmite gel powder and extrusion aid are uniformly mixed and then added into aqueous solution in which physical pore-expanding agent and chemical pore-expanding agent are dissolved; (2) the material obtained in step 1 is uniformly mixed and molded by extrusion on an extruder; (3) the material obtained in step 2 is dried and baked, and thereby the finished alumina carrier is prepared. The alumina carrier prepared by the method has large pore volume and pore diameter, centrally distributed pores and high mechanical strength, and is applicable to the preparation of heavy oil and residual oil hydrodemetallization catalysts and other fields.

The invention provides a method for comprehensively extracting aluminum and lithium from coal ash. The method is characterized by comprising the following technological steps which are carried out in sequence: (A) desiliconizing and magnetically separating; (B) roasting; (C) primary dipping by alkali; (D) secondary dipping by alkali; (E) carbonizing, and precipitating aluminum; (F) purifying lithium mother liquor; and (G) evaporating, concentrating and precipitating lithium. The method has the advantages that silicon, iron, aluminum and lithium are sequentially extracted from the industrial coal ash, so that the waste is turned into treasure, the cost of the raw materials is reduced, the technological operation is simple and convenient, and the comprehensive extracting rate of aluminum lithium resources can be maximized; and the method is an ideal method for comprehensively extracting aluminum and lithium from the coal ash.

The invention relates to a preparation method of low-sodium fine grain alumina, in particular to a preparation method of low-sodium submicro grain alumina used for electronic ceramics, microcrystalline ceramics, fine polishing, catalyst carriers and the like. The preparation method is characterized by taking industrial aluminium hydroxide as a raw material in the preparation process and comprising the following steps of: firstly carrying out hydrothermal phase inversion processing on aluminium hydroxide to obtain low-sodium fine grain alumina monohydrate with sodium oxide content being less than 500ppm; briquetting the obtained low-sodium fine grain alumina monohydrate, and then roasting to obtain low-sodium fine grain alumina; and finally grinding and grading, thus obtaining low-sodium submicro alumina. The preparation method of low-sodium fine grain alumina has the advantages of simple production process, wide raw material sources, low production cost, environment friendliness and the like, and can combine with the existing alumina production process and equipment to carry out hydrothermal processing, thus effectively simplifying the production process and lowering the production cost. The method is ideal for preparing ultra-low-sodium boehmite and alumina.

A process for extracting aluminum oxide from high-Al powdered coal ash and using the residual dregs to prepare cement includes such steps as mixing with lime and water, steam pressure reaction to generate the resultant containing hydrated calcium silicoaluminate and calcium hydroxide, calcining, extracting in sodium carbonate solution to obtain aluminum oxide, desiliconizing, carbonizing, calcining to obtain high-purity aluminum oxide, and using the SiCa dregs to prepare cement.

The invention provides a technical method for comprehensively extracting aluminum and lithium from coal ash through an acid process. The method is characterized by comprising the following technological steps which are carried out in sequence: (A) desiliconizing and magnetically separating; (B) thermally processing; (C) acidizing and roasting; (D) leaching; (E) removing residues; (F) carbonizing, and precipitating aluminum; (G) purifying lithium mother liquor; and (H) evaporating, concentrating and precipitating lithium. The method has the advantages that the silicon, iron, aluminum and lithium are sequentially extracted from the industrial coal ash, so that the waste is turned into treasure, the cost of the raw materials is reduced, the technological operation is simple and convenient, and the comprehensive extracting rate of aluminum source and lithium resources can be maximized; and the method is an ideal method for comprehensively extracting aluminum and lithium from the coal ash through the acid process.

The present invention features that through the reaction of choline and pure aluminium to produce aluminum cholinide, hydrolyzing cholinide to produce aluminium hydroxide and choline, washing, filtering, calcining and grinding aluminum hydroxide, high-purity alpha alumina is prepared. The present invention has the advantages of high product purity, environment friendship, no pollution, low cost, etc. The high-purity alumina may be used in high-voltage sodium lamp tube, light-emitting RE material, high-grade grinding material, fine ceramics and other fields.