CN102180494B - Method for extracting alumina from coal ash - Google Patents
Method for extracting alumina from coal ash Download PDFInfo
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- CN102180494B CN102180494B CN2011100023033A CN201110002303A CN102180494B CN 102180494 B CN102180494 B CN 102180494B CN 2011100023033 A CN2011100023033 A CN 2011100023033A CN 201110002303 A CN201110002303 A CN 201110002303A CN 102180494 B CN102180494 B CN 102180494B
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Abstract
The invention discloses a method for extracting alumina from coal ash. The method comprises the following steps: mixing the coal ash with sodium carbonate in a certain proportion and then grinding; and then extracting the high-pure alumina from the coal ash through the steps such as roasting, circular leaching, precipitation and filtration, carbonating, carbon dioxide and auxiliary recovery, washing, calcination and the like. Compared with the other methods for extracting the alumina from the coal ash, the method in the invention has the advantages of high aluminum hydroxide extraction rate, small residue, low energy consumption, simple and direct technology process, low cost, recoverable and recyclable CO2 and used auxiliary raw material and the like, thereby breaking through the bottleneck of complicated technology and high cost in the existing process for extracting the alumina from the coal ash and creating a new way for development and utilization of high added value of the coal ash.
Description
Technical field:
The invention belongs to the multipurpose use of solid waste technical field of discharging in generating, metallurgy, the chemical industry synthetic production process, particularly a kind of method of from flyash, extracting aluminum oxide.
Background technology:
In the last few years, developing rapidly of the coal electricity industry of China, brought the rapid increase of solid waste flyash quantity discharged, the flyash total amount that discharge every year the coal-burning power plant increases year by year, nineteen ninety-five, the flyash quantity discharged reached 1.25 hundred million tons, was about 1.5 hundred million tons in 2000, by 2009, Coal Ash in China output reaches 3.75 hundred million tons, and the twice that is equivalent to Municipal Solid Waste in China total amount then is many.Because flyash is contaminate environment in a variety of forms, so its a large amount of dischargings are exerted heavy pressures on to the development of the national economy and the ecotope of China.Authoritative department statistics shows, the present practical efficiency of flyash less than 30% still, because China's supply of electric power is take the coal electricity as main, this situation can't change in a short time.
In order to reduce the stacking of flyash, be mainly used at present backfill, build the road, the aspect such as building, although larger with the ash amount, its digestion amount still is unable to catch up with the continuous growth of quantity discharged far away, and this economic benefit of mode of utilizing is also not obvious.Therefore, open up flyash better utilised approach, improve its utility value, become all the time the focus that people pay close attention to.Because the content of aluminum oxide is only second to silicon-dioxide in the flyash, alumina content reaches more than 35% even higher in the flyash of some areas.Therefore, the aluminum oxide in these aluminous fly-ashs if be extracted is used, to the minimizing that realizes the discharging of fine coal dust heap, innoxious and resource utilization is significant.
At present, the method of utilizing flyash to produce aluminum oxide mainly comprises limestone sintering method, ammonium sulfate sintering process, soda-lime sintering process, pickling process, Neutral ammonium fluoride hydrotropy method, solubilization of microwave method, integrated process, Bayer process and so-called non high temperature method etc., and constantly has new patent to produce.In above-mentioned existing each class methods, except Bayer process, all there is major defect: otherwise energy consumption is too high, is difficult to obtain benefit (techniques such as soda-lime sintering process, lime sinter process and solubilization of microwave method); The aluminum oxide leaching rate is excessively low, is difficult to equally obtain benefit (non high temperature method); Bed drain purge is excessive, causes the discharging of too much solid waste, and serious environment pollution fundamentally, still is difficult to obtain benefit; Technical process is long and complicated, various, a lot of operation process of equipment checks and balance, and has simultaneously the problems (integrated process etc.) such as high energy consumption is expensive; It is adjuvant used that too strong and auxiliary agent acid recovery difficulty and its have had a strong impact on the popularization (pickling process, Neutral ammonium fluoride hydrotropy method, ammonium sulfate sintering process etc.) of its industrialization to a series of fatal shortcomings such as environment easily pollute to equipment corrosion.
Compare with existing additive method, although the bayer's process flow process is relatively simple, investment is relative with energy consumption minimum, have at present the aluminum oxide more than 90% to produce with Bayer process, but the critical defect of the method is the processing that is only applicable to the gibbsitic bauxite of high aluminium silicon ratio.And the aluminum oxide existence form in the flyash is neither the gibbsite type mineral, and alumina silica ratio (A/S) is low again, so the method can't be applied to the extraction to aluminum oxide in the flyash at all.
In sum, the key issue that needs at present to solve is how to reduce the emission problem of energy consumption and production cost, minimizing waste.The object of the invention is exactly to seek a kind ofly can be applicable to the method for extraction aluminum oxide that flyash can reduce again energy consumption and production cost, reduce the discharging of waste.
Summary of the invention:
The present invention compares with previous achievements, and its characteristics are by selecting suitable calcining temperature and calcination time, so that flyash and sodium carbonate mixture no longer produce sodium aluminium silicate (Na in the sintering rules
2OAl
2O
32SiO
2), thereby realized only with the sodium aluminate of the activation of the aluminium in the flyash for water soluble and alkaline solution, and siliceous composition wherein still is water insoluble and material alkaline solution, thereby avoided in the previous patent the sintering stage with flyash in the shortcoming that is activated simultaneously of aluminium and silicon, thereby just can directly realize the effective separation of silicon and aluminium in leaching stage.High, the Al of sintering temperature in the soda ash sintering process before like this, both having solved
2O
3Extraction yield is low, silicon can't directly separate with aluminium, and the key issue such as aluminum oxide poor quality, overcome again the harsh requirement of Bayer process to alumina silica ratio (A/S) and ore mineral type, the activation ratio that realized also simultaneously that sintering temperature is low, sintering time is short, can effectively control aluminium and silicon.Final so that utilize flyash to extract in the alumina process, energy consumption and production cost have obtained effective reduction, thus be technology popularization of the present invention and realize industrialization firm solid economic technology basic.The popularization of estimating present method realizes that industrialization obtains substantive breakthroughs so that flyash extracts aluminium hydroxide.
A kind of method of extracting aluminum oxide from flyash provided by the invention, purpose is to overcome existing flyash and extracts in the alumina producing technological method, has the shortcomings such as technological process is numerous and diverse, equipment requirements is high, production cost is high.Basic fundamental approach of the present invention is: with flyash and caustic soda (NaOH) by a certain percentage behind the mixed grinding, again through roasting, circulation leaching, sedimentation and filtration, auxiliary agent reclaim, the steps such as calcining of washing, extract the high purity aluminium oxide product.
Present method comprises the following steps:
(1) mixed grinding: according to mass percent, with flyash and Na
2CO
3Solid is in 1: 0.6-1: 2.5 ratio mixing also grinds to form 100 orders-250 purpose mixture;
(2) roasting: the mixture that step (1) is obtained roasting 10 minutes-60 minutes under 620 ℃ of-990 ℃ of temperature condition obtains the roasting grog.Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, and output gas can be directly used in carbon and divide;
(3) circulation leaching: add entry in the roasting grog that obtains to step (2) and leach.The leaching condition is: solid-to-liquid ratio 1: 6.0-1: 120,10 ℃-85 ℃ of leaching temperatures, leaching time 5 minutes-50 minutes.Filter after the leaching, obtain respectively filter residue and filtrate; Gained filtrate is recycled for the leaching to step (2) gained roasting grog, and the leaching condition is constant.Filter after the circulation leaching and obtain filter residue and circulation filtrate;
(4) sedimentation and filtration: stop circulation leaching after white precipitate is separated out when seeing in the circulation filtrate in the step (3), and with circulation filtrate be heated to temperature 60 C-100 ℃, insulation is filtered after 30 minutes-120 minutes, obtains respectively aluminium hydroxide and circulation filtrate.Circulation filtrate continues to be used to the circulation leaching of step (3) again, and the leaching condition is constant.
(5) carbon divides: stop leaching in the step (4) during the translucent crystallization of circulation filtrate adularescent, and should circulation filtrate insert carbon minute pond and carry out carbon and divide.Bar carbon bulk-breaking is: 20 ℃-100 ℃ of carbon minute temperature, filtrate pH value 7-9 divide terminal point as carbon.Carbon divides rear filtration, obtains respectively Na
2CO
3Solution and aluminium hydroxide.
(6) auxiliary agent and water reclaim: with step (5) gained Na
2CO
3The crystallization of solution negative pressure evaporation and oven dry, i.e. recyclable yellow soda ash auxiliary agent, and can be directly used in step (1).Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank reclaims distilled water; Distilled water can be used for the leaching of aluminium hydroxide washing or step (3).
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain high purity aluminium hydroxide, further calcining obtains alumina product.
The present invention both can so that solid waste coal ash obtains high value added utilization, can extenuate the problem of the deficiency of bauxite resource simultaneously.In addition, the alumina loss rate is low in the production process, energy consumption is low, technological process is simple and direct, to equipment without particular requirement, and the CO that produces in the whole technological process
2And employed alkali and all recyclable and realization recycles of water in the extraction alumina process, reduce simultaneously the quantity discharged of waste, so realized easily industrialization.
Description of drawings:
Fig. 1 is a kind of method process flow sheet that extracts aluminium hydroxide from flyash.
Embodiment:
Below in conjunction with accompanying drawing the present invention is done and to describe in further detail:
Fig. 1 is one embodiment of the present of invention, i.e. a kind of method process flow sheet that extracts aluminium hydroxide from flyash.Specifically comprise the following steps.
(1) according to mass percent, with flyash and Na
2CO
3Solid is in 1: 0.6-1: 2.5 ratio mixing also grinds to form 100 orders-250 purpose mixture;
(2) mixture that step (1) is obtained roasting 10 minutes 60 minutes under 620 ℃ of-990 ℃ of temperature condition obtains the roasting grog; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides;
The main chemical reactions that occurs in the sintering process is as follows:
Al
2O
3+Na
2CO
3＝2NaAlO
2+CO
2↑
(3) adding entry in the roasting grog that obtains to step (2) leaches.The leaching condition is: solid-liquid mass ratio 1: 6.0-1: 120,10 ℃-85 ℃ of leaching temperatures, leaching time 5 minutes-50 minutes.Filter after the leaching, obtain respectively filter residue and filtrate; Gained filtrate is recycled for the leaching to step (2) gained roasting grog, and the leaching condition is constant.Filter after the circulation leaching and obtain filter residue and circulation filtrate;
Calculate Al in the bauxite according to following formula
2O
3Leaching rate G
G=(Al in the filtrate
2O
3Contained Al in the amount/bauxite
2O
3Total amount) * 100%; Wherein G is Al
2O
3Leaching rate.
(4) in circulation filtrate in the step (3), see white (Al (OH)
3) separate out after, circulation filtrate is filtered after being heated to temperature 60 C-100 ℃ and being incubated 30 minutes-120 minutes, wherein contained sodium aluminate has 60-90% to transform to be decomposed to form Al (OH)
3Precipitation.After the filtration, obtain respectively aluminium hydroxide and circulation filtrate.Circulation filtrate can continue to be used to the circulation leaching of step (3), and the leaching condition is constant.
(5) stop leaching in the step (4) during circulation filtrate NaOH supersaturation, and should circulation filtrate insert carbon minute pond and carry out carbon and divide.Carbon divides 20 ℃-100 ℃ of temperature, and filtrate pH value 7-9 divide terminal point as carbon.So far, remaining sodium aluminate also is converted into Al (OH) in the circulation filtrate
3Precipitated separating out.Filter and obtain respectively Na
2CO
3Solution and aluminium hydroxide.
(6) with step (5) gained Na
2CO
3The crystallization of solution negative pressure evaporation and oven dry, i.e. recyclable yellow soda ash.The yellow soda ash that reclaims can be directly used in step (1); Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank reclaims distilled water.Distilled water can be used for the leaching of aluminium hydroxide washing or step (3).
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium hydroxide product, further calcining obtains aluminum oxide.
Below be the embodiment that the contriver provides, need to prove that these embodiment are some more excellent examples, the invention is not restricted to these embodiment.
Embodiment 1
(1) coal-powder boiler flyash is mixed in 1: 0.6 ratio with the yellow soda ash solid and grind to form 100 purpose mixtures.
(2) mixture that step (1) is obtained roasting 60 minutes under 620 ℃ of temperature condition obtains the roasting grog.It is for subsequent use that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides.
(3) add an amount of water in first part of roasting grog, and to make the solid-liquid mass ratio be 1: 6, leaching is 50 minutes under 10 ℃ of temperature condition.Filter after the leaching, obtain respectively filter residue and filtrate.After measured, aluminum oxide leaching rate 70% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
With the 2nd part of roasting grog insert proceed in the gained filtrate leaching, the leaching condition is constant.Filter after the leaching, obtain respectively filter residue and circulation filtrate; After measured, aluminum oxide leaching rate 72% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
Utilize the circulation filtrate that forms after leaching to continue by part the roasting grog to be leached, the leaching condition is constant.After measured, the aluminum oxide leaching rate remains on 75%-80%, and other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
(4) the circulation leaching is to the 7th part of roasting grog, and circulation filtrate is seen Al (OH)
3Separate out, heat this filtrate to temperature 60 C and kept 120 minutes, obtain respectively aluminium hydroxide and circulation filtrate after the filtration.Calculate by analysis, so far, 75% aluminum oxide is extracted in the material.
(5) the circulation leaching is to the 10th part of roasting grog, and sodium hydroxide supersaturation in the circulation filtrate is inserted carbon minute pond with this filtrate, utilizes the CO of step (2) output
2Carrying out carbon divides.Carbon divides 20 ℃ of temperature, stops carbon after filtrate pH value reaches 7 and divides and filter.Filtrate is Na
2CO
3Solution, filter residue are aluminium hydroxide.Calculate by analysis, remaining aluminum ion also is converted into aluminium hydroxide and is extracted in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3The crystallization of circulation filtrate negative pressure evaporation and oven dry are recovered to yellow soda ash.Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank is recovered to distilled water.
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Embodiment 2:
(1) coal-powder boiler flyash is mixed in 1: 2.5 ratio with the yellow soda ash solid and grind to form 250 purpose mixtures.
(2) mixture that step (1) is obtained roasting 10 minutes under 990 ℃ of temperature condition obtains the roasting grog.It is for subsequent use that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides.
(3) add an amount of water in first part of roasting grog, and to make the solid-liquid mass ratio be 1: 120, leaching is 5 minutes under 85 ℃ of temperature condition.Filter after the leaching, obtain respectively filter residue and filtrate.After measured, aluminum oxide leaching rate 75% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
With the 2nd part of roasting grog insert proceed in the gained filtrate leaching, the leaching condition is constant.Filter after the leaching, obtain respectively filter residue and circulation filtrate; After measured, aluminum oxide leaching rate 77% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
Utilize the circulation filtrate that forms after leaching to continue by part the roasting grog to be leached, the leaching condition is constant.After measured, the aluminum oxide leaching rate remains on 77%-80%, and other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
(4) the circulation leaching is to the 21st part of roasting grog, and circulation filtrate is seen Al (OH)
3Separate out, heat this filtrate to 100 ℃ of temperature and kept 30 minutes, obtain respectively aluminium hydroxide and circulation filtrate after the filtration.Calculate by analysis, so far, 76% aluminum oxide is extracted in the material.
(5) the circulation leaching is to the 23rd part of roasting grog, and sodium hydroxide supersaturation in the circulation filtrate is inserted carbon minute pond with this filtrate, utilizes the CO of step (2) output
2Carrying out carbon divides.Carbon divides 100 ℃ of temperature, stops carbon after filtrate pH value reaches 9 and divides and filter.Filtrate is Na
2CO
3Solution, filter residue are aluminium hydroxide.Calculate by analysis, remaining aluminum ion also is converted into aluminium hydroxide and is extracted in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3The crystallization of circulation filtrate negative pressure evaporation and oven dry are recovered to yellow soda ash.Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank is recovered to distilled water.
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Embodiment 3:
(1) coal-powder boiler flyash is mixed in 1: 2.3 ratio with the yellow soda ash solid and grind to form 150 purpose mixtures.
(2) mixture that step (1) is obtained roasting 50 minutes under 720 ℃ of temperature condition obtains the roasting grog.It is for subsequent use that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides.
(3) add an amount of water in first part of roasting grog, and to make the solid-liquid mass ratio be 1: 15, leaching is 40 minutes under 20 ℃ of temperature condition.Filter after the leaching, obtain respectively filter residue and filtrate.After measured, aluminum oxide leaching rate 79% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
With the 2nd part of roasting grog insert proceed in the gained filtrate leaching, the leaching condition is constant.Filter after the leaching, obtain respectively filter residue and circulation filtrate; After measured, aluminum oxide leaching rate 80% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
Utilize the circulation filtrate that forms after leaching to continue by part the roasting grog to be leached, the leaching condition is constant.After measured, the aluminum oxide leaching rate remains on 81%-84%, and other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
(4) the circulation leaching is to the 15th part of roasting grog, and circulation filtrate is seen Al (OH)
3Separate out, heat this filtrate to temperature 70 C and kept 40 minutes, obtain respectively aluminium hydroxide and circulation filtrate after the filtration.Calculate by analysis, so far, 82% aluminum oxide is extracted in the material.
(5) the circulation leaching is to the 18th part of roasting grog, and sodium hydroxide supersaturation in the circulation filtrate is inserted carbon minute pond with this filtrate, utilizes the CO of step (2) output
2Carrying out carbon divides.Carbon divides 25 ℃ of temperature, stops carbon after filtrate pH value reaches 8.8 and divides and filter.Filtrate is Na
2CO
3Solution, filter residue are aluminium hydroxide.Calculate by analysis, remaining aluminum ion also is converted into aluminium hydroxide and is extracted in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3The crystallization of circulation filtrate negative pressure evaporation and oven dry are recovered to yellow soda ash.Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank is recovered to distilled water.
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Embodiment 4:
(1) fluidization bed fly ash is mixed in 1: 0.6 ratio with the yellow soda ash solid and grind to form 100 purpose mixtures.
(2) mixture that step (1) is obtained roasting 60 minutes under 620 ℃ of temperature condition obtains the roasting grog.It is for subsequent use that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides.
(3) add an amount of water in first part of roasting grog, and to make the solid-liquid mass ratio be 1: 6, leaching is 50 minutes under 10 ℃ of temperature condition.Filter after the leaching, obtain respectively filter residue and filtrate.After measured, aluminum oxide leaching rate 72% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
With the 2nd part of roasting grog insert proceed in the gained filtrate leaching, the leaching condition is constant.Filter after the leaching, obtain respectively filter residue and circulation filtrate; After measured, aluminum oxide leaching rate 73% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
Utilize the circulation filtrate that forms after leaching to continue by part the roasting grog to be leached, the leaching condition is constant.After measured, the aluminum oxide leaching rate remains on 75%-78%, and other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
(4) the circulation leaching is to the 7th part of roasting grog, and circulation filtrate is seen Al (OH)
3Separate out, heat this filtrate to temperature 60 C and kept 120 minutes, obtain respectively aluminium hydroxide and circulation filtrate after the filtration.Calculate by analysis, so far, 75% aluminum oxide is extracted in the material.
(5) the circulation leaching is to the 10th part of roasting grog, and sodium hydroxide supersaturation in the circulation filtrate is inserted carbon minute pond with this filtrate, utilizes the CO of step (2) output
2Carrying out carbon divides.Carbon divides 20 ℃ of temperature, stops carbon after filtrate pH value reaches 7 and divides and filter.Filtrate is Na
2CO
3Solution, filter residue are aluminium hydroxide.Calculate by analysis, remaining aluminum ion also is converted into aluminium hydroxide and is extracted in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3The crystallization of circulation filtrate negative pressure evaporation and oven dry are recovered to yellow soda ash.Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank is recovered to distilled water.
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Embodiment 2:
(1) fluidization bed fly ash is mixed in 1: 2.5 ratio with the yellow soda ash solid and grind to form 250 purpose mixtures.
(2) mixture that step (1) is obtained roasting 10 minutes under 990 ℃ of temperature condition obtains the roasting grog.It is for subsequent use that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides.
(3) add an amount of water in first part of roasting grog, and to make the solid-liquid mass ratio be 1: 120, leaching is 5 minutes under 85 ℃ of temperature condition.Filter after the leaching, obtain respectively filter residue and filtrate.After measured, aluminum oxide leaching rate 72% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
With the 2nd part of roasting grog insert proceed in the gained filtrate leaching, the leaching condition is constant.Filter after the leaching, obtain respectively filter residue and circulation filtrate; After measured, aluminum oxide leaching rate 74% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
Utilize the circulation filtrate that forms after leaching to continue by part the roasting grog to be leached, the leaching condition is constant.After measured, the aluminum oxide leaching rate remains on 73%-76%, and other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
(4) the circulation leaching is to the 21st part of roasting grog, and circulation filtrate is seen Al (OH)
3Separate out, heat this filtrate to 100 ℃ of temperature and kept 30 minutes, obtain respectively aluminium hydroxide and circulation filtrate after the filtration.Calculate by analysis, so far, 74% aluminum oxide is extracted in the material.
(5) the circulation leaching is to the 23rd part of roasting grog, and sodium hydroxide supersaturation in the circulation filtrate is inserted carbon minute pond with this filtrate, utilizes the CO of step (2) output
2Carrying out carbon divides.Carbon divides 100 ℃ of temperature, stops carbon after filtrate pH value reaches 9 and divides and filter.Filtrate is Na
2CO
3Solution, filter residue are aluminium hydroxide.Calculate by analysis, remaining aluminum ion also is converted into aluminium hydroxide and is extracted in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3The crystallization of circulation filtrate negative pressure evaporation and oven dry are recovered to yellow soda ash.Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank is recovered to distilled water.
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Embodiment 6:
(1) fluidization bed fly ash is mixed in 1: 2.3 ratio with the yellow soda ash solid and grind to form 150 purpose mixtures.
(2) mixture that step (1) is obtained roasting 50 minutes under 720 ℃ of temperature condition obtains the roasting grog.It is for subsequent use that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides.
(3) add an amount of water in first part of roasting grog, and to make the solid-liquid mass ratio be 1: 15, leaching is 40 minutes under 20 ℃ of temperature condition.Filter after the leaching, obtain respectively filter residue and filtrate.After measured, aluminum oxide leaching rate 75% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
With the 2nd part of roasting grog insert proceed in the gained filtrate leaching, the leaching condition is constant.Filter after the leaching, obtain respectively filter residue and circulation filtrate; After measured, aluminum oxide leaching rate 80% in the filtrate, other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
Utilize the circulation filtrate that forms after leaching to continue by part the roasting grog to be leached, the leaching condition is constant.After measured, the aluminum oxide leaching rate remains on 75%-76%, and other composition leaching rates such as silicon-dioxide, ferric oxide are zero.
(4) the circulation leaching is to the 15th part of roasting grog, and circulation filtrate is seen Al (OH)
3Separate out, heat this filtrate to temperature 70 C and kept 40 minutes, obtain respectively aluminium hydroxide and circulation filtrate after the filtration.Calculate by analysis, so far, 75% aluminum oxide is extracted in the material.
(5) the circulation leaching is to the 18th part of roasting grog, and sodium hydroxide supersaturation in the circulation filtrate is inserted carbon minute pond with this filtrate, utilizes the CO of step (2) output
2Carrying out carbon divides.Carbon divides 25 ℃ of temperature, stops carbon after filtrate pH value reaches 8.8 and divides and filter.Filtrate is Na
2CO
3Solution, filter residue are aluminium hydroxide.Calculate by analysis, remaining aluminum ion also is converted into aluminium hydroxide and is extracted in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3The crystallization of circulation filtrate negative pressure evaporation and oven dry are recovered to yellow soda ash.Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank is recovered to distilled water.
(7) washing and calcining.With step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Above content is the further description of the present invention being done in conjunction with concrete preferred implementation, can not assert that the specific embodiment of the present invention only limits to this.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to the present invention and determine scope of patent protection by claims of submitting to.
Claims (4)
1. a method of extracting aluminum oxide from flyash is characterized in that, comprises the following steps:
(1) mixed grinding: according to mass percent, with flyash and Na
2CO
3Solid mixes in the ratio of 1:0.6-1:2.5 and grinds to form 100 orders-250 purpose mixture;
(2) roasting: the mixture that step (1) is obtained under 620 ℃ of-990 ℃ of temperature condition roasting 10-60 minute obtains the roasting grog; Roasting apparatus connects gas output tube and is connected with a carbon minute pond during roasting, reclaims carbon dioxide and is directly used in carbon and divides;
(3) circulation leaching: add entry in the roasting grog that obtains to step (2) and leach; The leaching condition is: solid-to-liquid ratio 1:6.0-1:120,10 ℃-85 ℃ of leaching temperatures, leaching time 5 minutes-50 minutes; Filter after the leaching, obtain respectively filter residue and filtrate; Gained filtrate is recycled for the leaching to step (2) gained roasting grog, and the leaching condition is constant; Filter after the circulation leaching and obtain filter residue and circulation filtrate;
(4) sedimentation and filtration: stop circulation leaching after white precipitate is separated out when seeing in the circulation filtrate in the step (3), and with circulation filtrate be heated to temperature 60 C-100 ℃, insulation is filtered after 30 minutes-120 minutes, obtains respectively aluminium hydroxide and circulation filtrate; Circulation filtrate continues to be used to the circulation leaching of step (3) again, and the leaching condition is constant;
(5) carbon divides: stop leaching in the step (4) during the translucent crystallization of circulation filtrate adularescent, and should circulation filtrate insert carbon minute pond and carry out carbon and divide; Carbon minute condition is: 20 ℃-100 ℃ of carbon minute temperature, and filtrate pH value 7-9 divide terminal point as carbon; Carbon divides rear filtration, obtains respectively Na
2CO
3Solution and aluminium hydroxide;
(6) auxiliary agent and water reclaim: with step (5) gained Na
2CO
3The crystallization of solution negative pressure evaporation and oven dry are namely reclaimed the yellow soda ash auxiliary agent, and can be directly used in step (1); Na
2CO
3In the solution heating negative pressure evaporation process, evaporation equipment connects condensing works and storage tank reclaims distilled water; Distilled water is used for the leaching of aluminium hydroxide washing or step (3);
(7) washing and calcining: with step (6) the distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain high purity aluminium hydroxide, further calcining obtains alumina product.
2. the method for claim 1, it is characterized in that: the circulation leaching method described in the step (3) and leaching condition thereof: the leaching condition is solid-to-liquid ratio 1:15-1:120,20 ℃-85 ℃ of leaching temperatures, leaching time 5 minutes-40 minutes; Filter after the leaching, obtain respectively filter residue and filtrate; Gained filtrate is recycled for the leaching to step (2) gained roasting grog, and the leaching condition is constant.
3. the method for claim 1, it is characterized in that, described step (4) is obtained the method for aluminium hydroxide by sedimentation and filtration: after seeing that white precipitate is separated out in the circulation filtrate in the step (3), filter after circulation filtrate is heated to temperature 70 C-100 ℃ and was incubated 40 minutes-120 minutes, obtain respectively aluminium hydroxide and circulation filtrate.
4. the method for claim 1 is characterized in that, stops leaching when seeing that white precipitate is separated out in the step (4), and should circulation filtrate inserts carbon minute pond and carry out carbon and divide; Carbon minute condition is: 25 ℃-100 ℃ of carbon minute temperature, and filtrate pH value 7-8.8 divide terminal point as carbon; Carbon divides rear filtration, obtains respectively Na
2CO
3Solution and aluminium hydroxide.
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