CN102180494A - Method for extracting alumina from coal ash - Google Patents
Method for extracting alumina from coal ash Download PDFInfo
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- CN102180494A CN102180494A CN2011100023033A CN201110002303A CN102180494A CN 102180494 A CN102180494 A CN 102180494A CN 2011100023033 A CN2011100023033 A CN 2011100023033A CN 201110002303 A CN201110002303 A CN 201110002303A CN 102180494 A CN102180494 A CN 102180494A
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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 comprehensive utilization technique field of the solid waste of being discharged in generating, metallurgy, the chemical industry synthetic production process, particularly a kind of method of alumina of from flyash, extracting.
Background technology:
In the last few years, developing rapidly of the coal electrician industry of China, brought the rapid increase of solid waste flyash quantity discharged, the flyash total amount that the coal-burning power plant is discharged every year 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, China's flyash output reaches 3.75 hundred million tons, and the twice that is equivalent to Chinese city domestic refuse total amount then is many.Because flyash is contaminate environment in a variety of forms, so its a large amount of dischargings exert heavy pressures on for the development of the national economy and the ecotope of China.Authoritative department statistics shows, the practical efficiency of flyash less than 30% still at present, because China's supply of electric power is based on the coal electricity, this situation can't change in a short time.
In order to reduce the stacking of flyash, be mainly used in backfill at present, build the road, aspect such as building, although bigger 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 the focus that people pay close attention to all the time.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 can be extracted out and be used, to the minimizing that realizes the discharging of fine coal dust heap, innoxious and resource utilization is significant.
At present, utilize flyash production method of alumina mainly to comprise limestone sintering method, ammonium sulfate sintering process, soda-lime sintering process, pickling process, Neutral ammonium fluoride hydrotropy method, microwave hydrotropy method, integrated process, Bayer process and so-called non high temperature method etc., and constantly have 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 (technologies such as soda-lime sintering process, lime sinter process and microwave hydrotropy method); The aluminum oxide leaching rate is low excessively, is difficult to obtain benefit (non high temperature method) equally; 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 problems (integrated process etc.) such as high energy consumption is expensive simultaneously; 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, though the bayer's process flow process is simple relatively, investment is relative with energy consumption minimum, have the aluminum oxide more than 90% to produce at present, but the critical defect of this method is the processing that only is applicable to the gibbsitic bauxite of high aluminium silicon ratio with Bayer process.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 this 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 cut down the consumption of energy and production cost, minimizing discharging wastes problem.The object of the invention is exactly to seek a kind ofly can be applicable to that flyash can cut down the consumption of energy again and production cost, reduce the extraction method of alumina of discharging wastes.
Summary of the invention:
The present invention compares with previous achievements, and its characteristics are by selecting suitable calcining temperature and calcination time, make 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 realize directly that in leaching stage silicon and the effective of aluminium separate.Sintering temperature height, Al 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 key issue such as aluminum oxide poor quality, overcome the harsh requirement of Bayer process again, the activation ratio that realized also simultaneously that sintering temperature is low, sintering time is short, can effectively control aluminium and silicon to alumina silica ratio (A/S) and ore mineral type.Final making utilizes flyash to extract in the alumina process, and energy consumption and production cost have obtained effective reduction, thus be technology popularization of the present invention and realization industrialization firm solid economic technology basis.The popularization of estimating present method makes flyash extraction aluminium hydroxide realize that industrialization obtains substantive breakthroughs.
A kind of method of alumina of extracting from flyash provided by the invention, purpose are to overcome existing flyash and extract in the alumina producing technological method, have shortcomings such as technological process is numerous and diverse, equipment requirements is high, production cost height.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 by 1: 0.6-1: 2.5 mixed 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 carbon branch pond during roasting, and output gas can be directly used in the carbon branch;
(3) circulation leaching: in the roasting grog that step (2) is obtained, add entry 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.The leaching after-filtration obtains filter residue and filtrate respectively; Gained filtrate is recycled the leaching that is used for step (2) gained roasting grog, and the leaching condition is constant.Circulation leaching after-filtration obtains filter residue and circulation filtrate;
(4) sedimentation and filtration: stop the circulation leaching after white precipitate is separated out when seeing in the circulation filtrate in the step (3), and circulation filtrate is heated to 60 ℃-100 ℃ of temperature, 30 minutes-120 minutes after-filtration of insulation, obtain aluminium hydroxide and circulation filtrate respectively.Circulation filtrate continues to be used to the circulation leaching of step (3) again, and the leaching condition is constant.
(5) carbon branch: stop leaching when the translucent crystallization of circulation filtrate adularescent is separated out in the step (4), and should circulation filtrate insert carbon branch pond and carry out the carbon branch.Bar carbon bulk-breaking is: 20 ℃-100 ℃ of carbon branch temperature, filtrate pH value 7-9 divide terminal point as carbon.Carbon divides after-filtration, obtains Na respectively
2CO
3Solution and aluminium hydroxide.
(6) auxiliary agent and water reclaim: with step (5) gained Na
2CO
3Crystallization of solution negative pressure evaporation and oven dry, promptly 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) 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 extenuate the insufficient problem of bauxite resource simultaneously so that solid waste coal ash obtains high value added utilization.In addition, the alumina loss rate is low in the production process, energy consumption is low, technological process is simple and direct, and equipment is not had particular requirement, and the CO that produces in the whole technological process
2And employed alkali and water is all recyclable and realize recycle in the extraction alumina process, reduced the discharging wastes amount simultaneously, therefore realize industrialization easily.
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, promptly 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 by 1: 0.6-1: 2.5 mixed 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 carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch;
The main chemical reactions that takes place 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 step (2) is obtained 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.The leaching after-filtration obtains filter residue and filtrate respectively; Gained filtrate is recycled the leaching that is used for step (2) gained roasting grog, and the leaching condition is constant.Circulation leaching after-filtration obtains 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 60 ℃-100 ℃ of temperature and being incubated 30 minutes-120 minutes, wherein contained sodium aluminate has 60-90% to transform to be decomposed to form Al (OH)
3Precipitation is separated out.After the filtration, obtain aluminium hydroxide and circulation filtrate respectively.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 branch pond and carry out the carbon branch.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 Na respectively
2CO
3Solution and aluminium hydroxide.
(6) with step (5) gained Na
2CO
3Crystallization of solution negative pressure evaporation and oven dry, promptly 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) 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) with coal-powder boiler flyash and yellow soda ash solid by 1: 0.6 mixed 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 standby that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch.
(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.The leaching after-filtration obtains filter residue and filtrate respectively.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.The leaching after-filtration obtains filter residue and circulation filtrate respectively; 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 of leaching back formation 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 and kept 120 minutes for 60 ℃, obtain aluminium hydroxide and circulation filtrate after the filtration respectively.Calculate by analysis, so far, 75% aluminum oxide is extracted out 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 branch pond with this filtrate, utilizes the CO of step (2) output
2Carry out the carbon branch.Carbon divides 20 ℃ of temperature, stops carbon branch and filtration after filtrate pH value reaches 7.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 out in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3Crystallization 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) 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) with coal-powder boiler flyash and yellow soda ash solid by 1: 2.5 mixed 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 standby that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch.
(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.The leaching after-filtration obtains filter residue and filtrate respectively.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.The leaching after-filtration obtains filter residue and circulation filtrate respectively; 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 of leaching back formation 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 temperature and kept 30 minutes for 100 ℃, obtain aluminium hydroxide and circulation filtrate after the filtration respectively.Calculate by analysis, so far, 76% aluminum oxide is extracted out 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 branch pond with this filtrate, utilizes the CO of step (2) output
2Carry out the carbon branch.Carbon divides 100 ℃ of temperature, stops carbon branch and filtration after filtrate pH value reaches 9.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 out in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3Crystallization 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) 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) with coal-powder boiler flyash and yellow soda ash solid by 1: 2.3 mixed 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 standby that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch.
(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.The leaching after-filtration obtains filter residue and filtrate respectively.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.The leaching after-filtration obtains filter residue and circulation filtrate respectively; 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 of leaching back formation 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 and kept 40 minutes for 70 ℃, obtain aluminium hydroxide and circulation filtrate after the filtration respectively.Calculate by analysis, so far, 82% aluminum oxide is extracted out 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 branch pond with this filtrate, utilizes the CO of step (2) output
2Carry out the carbon branch.Carbon divides 25 ℃ of temperature, stops carbon branch and filtration after filtrate pH value reaches 8.8.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 out in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3Crystallization 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) 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) with fluid bed powder coal ash and yellow soda ash solid by 1: 0.6 mixed 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 standby that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch.
(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.The leaching after-filtration obtains filter residue and filtrate respectively.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.The leaching after-filtration obtains filter residue and circulation filtrate respectively; 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 of leaching back formation 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 and kept 120 minutes for 60 ℃, obtain aluminium hydroxide and circulation filtrate after the filtration respectively.Calculate by analysis, so far, 75% aluminum oxide is extracted out 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 branch pond with this filtrate, utilizes the CO of step (2) output
2Carry out the carbon branch.Carbon divides 20 ℃ of temperature, stops carbon branch and filtration after filtrate pH value reaches 7.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 out in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3Crystallization 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) 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) with fluid bed powder coal ash and yellow soda ash solid by 1: 2.5 mixed 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 standby that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch.
(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.The leaching after-filtration obtains filter residue and filtrate respectively.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.The leaching after-filtration obtains filter residue and circulation filtrate respectively; 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 of leaching back formation 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 temperature and kept 30 minutes for 100 ℃, obtain aluminium hydroxide and circulation filtrate after the filtration respectively.Calculate by analysis, so far, 74% aluminum oxide is extracted out 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 branch pond with this filtrate, utilizes the CO of step (2) output
2Carry out the carbon branch.Carbon divides 100 ℃ of temperature, stops carbon branch and filtration after filtrate pH value reaches 9.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 out in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3Crystallization 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) 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) with fluid bed powder coal ash and yellow soda ash solid by 1: 2.3 mixed 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 standby that the roasting grog is divided into some equal portions identical in quality; Roasting apparatus connects gas output tube and is connected with carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch.
(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.The leaching after-filtration obtains filter residue and filtrate respectively.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.The leaching after-filtration obtains filter residue and circulation filtrate respectively; 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 of leaching back formation 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 and kept 40 minutes for 70 ℃, obtain aluminium hydroxide and circulation filtrate after the filtration respectively.Calculate by analysis, so far, 75% aluminum oxide is extracted out 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 branch pond with this filtrate, utilizes the CO of step (2) output
2Carry out the carbon branch.Carbon divides 25 ℃ of temperature, stops carbon branch and filtration after filtrate pH value reaches 8.8.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 out in the circulation filtrate.
(6) with the supersaturation Na of step (5) gained
2CO
3Crystallization 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) distilled water wash step (4) that reclaims and the aluminium hydroxide that step (5) obtains, obtain the high purity aluminium oxide product.
Above content be in conjunction with concrete preferred implementation to further describing that the present invention did, 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 being submitted to.
Claims (7)
1. a method of extracting aluminium hydroxide from flyash is characterized in that, comprises the following steps:
(1) mixed grinding: according to mass percent, with flyash and Na
2CO
3Solid is by 1: 0.6-1: 2.5 mixed also grinds to form 50 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 carbon branch pond during roasting, reclaims carbon dioxide and is directly used in the carbon branch;
(3) circulation leaching: in the roasting grog that step (2) is obtained, add entry 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; The leaching after-filtration obtains filter residue and filtrate respectively; Gained filtrate is recycled the leaching that is used for step (2) gained roasting grog, and the leaching condition is constant; Circulation leaching after-filtration obtains filter residue and circulation filtrate;
(4) sedimentation and filtration: stop the circulation leaching after white precipitate is separated out when seeing in the circulation filtrate in the step (3), and circulation filtrate is heated to 60 ℃-100 ℃ of temperature, 30 minutes-120 minutes after-filtration of insulation, obtain aluminium hydroxide and circulation filtrate respectively; Circulation filtrate continues to be used to the circulation leaching of step (3) again, and the leaching condition is constant;
(5) carbon branch: stop leaching when the translucent crystallization of circulation filtrate adularescent is separated out in the step (4), and should circulation filtrate insert carbon branch pond and carry out the carbon branch; Bar carbon bulk-breaking is: 20 ℃-100 ℃ of carbon branch temperature, and filtrate pH value 7-9 divide terminal point as carbon; Carbon divides after-filtration, obtains Na respectively
2CO
3Solution and aluminium hydroxide;
(6) auxiliary agent and water reclaim: with step (5) gained Na
2CO
3Crystallization of solution negative pressure evaporation and oven dry are promptly 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 can be used for the leaching of aluminium hydroxide washing or step (3);
(7) washing and calcining: with step (6) 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 is characterized in that: the mixed grinding condition in the described step (1): with flyash and yellow soda ash by 1: 0.6-1: 2.5 mixed also grinds to form 50 orders-250 purpose mixture.
3. the method for claim 1 is characterized in that the roasting condition in the described step (2): with in the step (1) mixture, under 620 ℃ of-990 ℃ of temperature condition roasting 10-60 minute.
4. the method for claim 1, it is characterized in that: circulation leaching method described in the step (3) and leaching condition thereof: the leaching condition is solid-to-liquid ratio 1: 6.0-1: 120,10 ℃-85 ℃ of leaching temperatures, leaching time 5 minutes-50 minutes; The leaching after-filtration obtains filter residue and filtrate respectively; Gained filtrate is recycled the leaching that is used for step (2) gained roasting grog, and the leaching condition is constant.
5. the method for claim 1, it is characterized in that, described step (4) is obtained method of alumina 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 60 ℃-100 ℃ of temperature and was incubated 30 minutes-120 minutes, obtain aluminium hydroxide and circulation filtrate respectively.
6. 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 branch pond and carry out the carbon branch; Bar carbon bulk-breaking is: 20 ℃-100 ℃ of carbon branch temperature, and filtrate pH value 7-9 divide terminal point as carbon; Carbon divides after-filtration, obtains Na respectively
2CO
3Solution and aluminium hydroxide.
7. the method for claim 1 is characterized in that: described flyash comprises the flyash of coal-powder boiler flyash, fluid bed powder coal ash and other types.
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| CN111072071A (en) * | 2019-12-13 | 2020-04-28 | 潘爱芳 | Method for producing polymeric aluminum ferric sulfate water purifying agent and silica gel by using iron tailings |
| CN114644928A (en) * | 2022-04-12 | 2022-06-21 | 中国环境科学研究院 | Process for producing and processing soil conditioner by taking fly ash as raw material |
| CN114735732A (en) * | 2022-05-06 | 2022-07-12 | 内蒙古工业大学 | Method for preparing alumina and silicon dioxide by using high-alumina fly ash |
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| CN101759210A (en) * | 2010-01-18 | 2010-06-30 | 马昱昭 | Method for extracting high purity alumina and silica gel from coal ash |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111072071A (en) * | 2019-12-13 | 2020-04-28 | 潘爱芳 | Method for producing polymeric aluminum ferric sulfate water purifying agent and silica gel by using iron tailings |
| CN111072071B (en) * | 2019-12-13 | 2020-11-03 | 潘爱芳 | Method for producing polymeric aluminum ferric sulfate water purifying agent and silica gel by using iron tailings |
| CN114644928A (en) * | 2022-04-12 | 2022-06-21 | 中国环境科学研究院 | Process for producing and processing soil conditioner by taking fly ash as raw material |
| CN114735732A (en) * | 2022-05-06 | 2022-07-12 | 内蒙古工业大学 | Method for preparing alumina and silicon dioxide by using high-alumina fly ash |
| CN114735732B (en) * | 2022-05-06 | 2023-10-27 | 内蒙古工业大学 | Method for preparing alumina and silicon dioxide from high-alumina fly ash |
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