CN113371745B - System and method for producing high-purity alumina by recycling fly ash - Google Patents
System and method for producing high-purity alumina by recycling fly ash Download PDFInfo
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- CN113371745B CN113371745B CN202110427862.2A CN202110427862A CN113371745B CN 113371745 B CN113371745 B CN 113371745B CN 202110427862 A CN202110427862 A CN 202110427862A CN 113371745 B CN113371745 B CN 113371745B
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- reactor
- desilication
- fly ash
- purification
- hydroxide
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- 239000010881 fly ash Substances 0.000 title claims abstract description 65
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 47
- 238000004064 recycling Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 14
- 238000000746 purification Methods 0.000 claims abstract description 68
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 56
- 239000002253 acid Substances 0.000 claims abstract description 50
- 238000002386 leaching Methods 0.000 claims abstract description 50
- 238000001354 calcination Methods 0.000 claims abstract description 48
- 235000014413 iron hydroxide Nutrition 0.000 claims abstract description 35
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims abstract description 35
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 32
- 230000004913 activation Effects 0.000 claims abstract description 26
- 239000007788 liquid Substances 0.000 claims abstract description 23
- 238000003837 high-temperature calcination Methods 0.000 claims abstract description 21
- 239000012190 activator Substances 0.000 claims abstract description 12
- 238000004062 sedimentation Methods 0.000 claims description 58
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 42
- 239000000378 calcium silicate Substances 0.000 claims description 40
- 229910052918 calcium silicate Inorganic materials 0.000 claims description 40
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 claims description 39
- 239000002244 precipitate Substances 0.000 claims description 35
- 229960004887 ferric hydroxide Drugs 0.000 claims description 31
- 239000006228 supernatant Substances 0.000 claims description 30
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims description 29
- 238000007599 discharging Methods 0.000 claims description 26
- 239000000047 product Substances 0.000 claims description 25
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 24
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 24
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 24
- 238000000926 separation method Methods 0.000 claims description 21
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 19
- 230000035484 reaction time Effects 0.000 claims description 19
- 230000003213 activating effect Effects 0.000 claims description 17
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 239000000292 calcium oxide Substances 0.000 claims description 15
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 15
- 239000012629 purifying agent Substances 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 14
- 230000003472 neutralizing effect Effects 0.000 claims description 14
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 13
- 239000000843 powder Substances 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 11
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 9
- 238000000227 grinding Methods 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- 239000010703 silicon Substances 0.000 claims description 9
- 235000017550 sodium carbonate Nutrition 0.000 claims description 9
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 8
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 8
- 229910017604 nitric acid Inorganic materials 0.000 claims description 8
- 235000006408 oxalic acid Nutrition 0.000 claims description 8
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 8
- 239000000243 solution Substances 0.000 claims description 8
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 5
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims description 4
- 238000004090 dissolution Methods 0.000 claims description 4
- 235000021110 pickles Nutrition 0.000 claims description 4
- 239000011736 potassium bicarbonate Substances 0.000 claims description 4
- 235000015497 potassium bicarbonate Nutrition 0.000 claims description 4
- 229910000028 potassium bicarbonate Inorganic materials 0.000 claims description 4
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 4
- 235000011181 potassium carbonates Nutrition 0.000 claims description 4
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims description 4
- 238000007873 sieving Methods 0.000 claims description 4
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 4
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 4
- 239000007795 chemical reaction product Substances 0.000 claims description 3
- 238000010979 pH adjustment Methods 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 238000000605 extraction Methods 0.000 abstract description 19
- 239000012535 impurity Substances 0.000 abstract description 9
- 239000002910 solid waste Substances 0.000 abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 22
- 239000000741 silica gel Substances 0.000 description 16
- 229910002027 silica gel Inorganic materials 0.000 description 16
- 230000008569 process Effects 0.000 description 12
- 229910052782 aluminium Inorganic materials 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 238000005259 measurement Methods 0.000 description 10
- 239000012530 fluid Substances 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 239000011734 sodium Substances 0.000 description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 7
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical group [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 7
- 239000000920 calcium hydroxide Substances 0.000 description 7
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- 238000009413 insulation Methods 0.000 description 5
- 239000013049 sediment Substances 0.000 description 5
- 235000012239 silicon dioxide Nutrition 0.000 description 5
- 239000002274 desiccant Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 4
- 229910052664 nepheline Inorganic materials 0.000 description 4
- 239000010434 nepheline Substances 0.000 description 4
- 238000004806 packaging method and process Methods 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 239000003513 alkali Substances 0.000 description 3
- 239000000084 colloidal system Substances 0.000 description 3
- 229910052863 mullite Inorganic materials 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000010992 reflux Methods 0.000 description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 3
- 238000004846 x-ray emission Methods 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- -1 aluminum ions Chemical class 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 230000004580 weight loss Effects 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000159 acid neutralizing agent Substances 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/08—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals with sodium carbonate, e.g. sinter processes
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
- C01B33/141—Preparation of hydrosols or aqueous dispersions
- C01B33/142—Preparation of hydrosols or aqueous dispersions by acidic treatment of silicates
- C01B33/143—Preparation of hydrosols or aqueous dispersions by acidic treatment of silicates of aqueous solutions of silicates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/24—Alkaline-earth metal silicates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
- C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/02—Oxides; Hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Dispersion Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Compounds Of Iron (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention relates to a system and a method for producing high-purity alumina by recycling fly ash, wherein the system comprises a grinder, a predesilica reactor, an activation calcination reactor, an acid leaching reactor, an iron hydroxide purification reactor, a neutralization reactor and a high-temperature calcination reactor which are sequentially connected along the direction of extracting alumina, wherein the predesilica reactor is also connected with a predesilica agent doser, the activation calcination reactor is also connected with an activator doser, the acid leaching reactor is also connected with an acid leaching liquid doser, the iron hydroxide purification reactor is also connected with an iron hydroxide purification doser, and the neutralization reactor is also connected with a neutralizer doser. Compared with the prior art, the invention realizes the comprehensive utilization of the fly ash, the extraction of high-purity alumina and the grading purification of impurity removal products, and truly realizes the concept of recycling solid wastes.
Description
Technical Field
The invention belongs to the technical field of environmental protection, and relates to a system and a method for producing high-purity alumina by using fly ash as a resource.
Background
Fly ash has been the focus of environmental protection due to its complex composition and difficulty in handling and disposal, but at the same time, due to its unique physicochemical properties, and the rich variety of valuable metallic elements, as a potential resource, there is a need for rational resource utilization. At present, fly ash is applied to the production fields of building materials, ceramics and the like, but the utilization rate of the fly ash is low in a high value. In recent years, the extraction of valuable elements in fly ash has been used as a high-value utilization way, and has become a research hotspot for students at home and abroad. Particularly, the extraction of aluminum can solve the problem of accumulation of fly ash and effectively utilize a large amount of aluminum resources in the ash. In the extraction process, because alumina in the fly ash mainly exists in the form of mullite, corundum and other stable crystalline substances, the SiO in the fly ash is difficult to be directly damaged by adopting a common extraction process 2 -Al 2 O 3 Bond and mullite structure. In addition, due to extremely complex phase composition of the fly ash, the impurity removal process in the extraction process is also in need of improvement.
Disclosure of Invention
The invention aims to provide a system and a method for producing high-purity alumina by using fly ash as a resource, which realize the comprehensive utilization of the fly ash, the extraction of the high-purity alumina and the graded purification of impurity removal products, and really realize the concept of recycling solid wastes.
The aim of the invention can be achieved by the following technical scheme:
the invention provides a system for producing high-purity alumina by recycling fly ash, which comprises a grinder, a predesilica reactor, an activation calcination reactor, an acid leaching reactor, an iron hydroxide purification reactor, a neutralization reactor and a high-temperature calcination reactor which are sequentially connected along the direction of extracting alumina, wherein the predesilica reactor is also connected with a predesilica agent doser, the activation calcination reactor is also connected with an activator doser, the acid leaching reactor is also connected with an acid leaching liquid doser, the iron hydroxide purification reactor is also connected with an iron hydroxide purification doser, and the neutralization reactor is also connected with a neutralizer doser.
Furthermore, the liquid outlet of the pre-desilication reactor is also connected with a calcium silicate purification reactor, the calcium silicate purification reactor is also connected with a silicon removing agent feeder, and the liquid outlet of the calcium silicate purification reactor is also connected with the pre-desilication reactor in a return way. Furthermore, a second sedimentation tank is arranged between the calcium silicate purifying reactor and the pre-desilication reactor.
Further, a screen machine is arranged between the grinder and the pre-desilication reactor, wherein a coarse powder outlet of the screen machine is also connected with an inlet of the grinder in a return way.
Further, along the direction of extracting alumina, a first sedimentation tank is further arranged between the pre-desilication reactor and the activation calcination reactor, a third sedimentation tank is further arranged between the acid leaching reactor and the ferric hydroxide purification reactor, a fourth sedimentation tank is further arranged between the ferric hydroxide purification reactor and the neutralization reactor, and a fifth sedimentation tank is further arranged between the neutralization reactor and the high-temperature calcination reactor.
Further, the liquid outlet of the neutralization reactor is also connected back to the inlet of the ferric hydroxide purification reactor.
The second technical scheme of the invention provides a method for producing high-purity alumina by recycling fly ash, which comprises the following steps:
(1) Grinding the fly ash to be treated in a grinder, sieving to obtain fine powder particles, discharging the fine powder particles into a pre-desilication reactor, adding a pre-desilication agent for pre-desilication treatment, and discharging the precipitate into an activation calcination reactor after solid-liquid separation of the treated muddy water mixed solution;
(2) Adding an activating agent into an activating and calcining reactor, activating and calcining, and discharging the obtained calcined product into an acid leaching reactor;
(3) Adding acid leaching liquid into an acid leaching reactor for acid leaching reaction, settling and separating the obtained reaction product, and discharging supernatant into an iron hydroxide purification reactor;
(4) Adding an iron hydroxide purifying agent into an iron hydroxide purifying reactor for purifying treatment, and precipitating and separating the mixed solution after the treatment is finished, and continuously discharging the obtained supernatant into a neutralizing reactor;
(5) Adding a neutralizing agent into the neutralization reactor to continuously adjust the pH value, then settling and separating to obtain an aluminum hydroxide precipitate, and discharging the aluminum hydroxide precipitate into a high-temperature calcination reactor;
(6) And (3) calcining the aluminum hydroxide precipitate sent into the high-temperature calcining reactor at high temperature to obtain the high-purity aluminum oxide.
Further, in the step (1), the reaction time of the pre-desilication treatment is 30-1000min.
Further, in the step (2), the temperature of activation and calcination is 100-1500 ℃ and the time is 10-500min.
Further, in the step (3), the temperature of the acid dissolution reaction is 25-100 ℃ and the time is 30-600min.
Further, in the step (4), the purification treatment time is 30-500min.
Further, in the step (6), the high-temperature calcination temperature is 400-1500 ℃ and the time is 10-300min.
Further, the pre-desilication agent is one or more of sodium hydroxide, calcium oxide or potassium hydroxide.
Further, the activator is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, and the adding amount of the activator is 10-300g/L.
Further, the pickle liquor is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid.
Further, the ferric hydroxide purifying agent is one or more of sodium hydroxide, potassium hydroxide, calcium oxide, sodium bicarbonate or sodium carbonate.
Further, the neutralizer is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid.
In the step (1), the supernatant obtained by solid-liquid separation of the muddy water mixture is subjected to desilication treatment and then returned to the inlet of the pre-desilication reactor.
Further, in the step (2), the supernatant obtained after the pH adjustment and the sedimentation separation in the neutralization reactor is also refluxed to the inlet of the iron hydroxide purification reactor.
Compared with the prior art, the invention has the following advantages:
(1) The process universality is strong, and the alumina can be extracted by high-valued utilization of the circulating fluidized bed fly ash or pulverized coal furnace fly ash, and the alumina extraction rate is not lower than 86%.
(2) The high-efficiency removal, separation and purification of impurities are realized through the processes of pre-desilication, deep desilication, step-by-step precipitation and the like, the treatment and disposal pressure of the solid waste of the fly ash of the coal-fired power plant is relieved, and the complete recycling of the fly ash is realized.
(3) The reflux calcium silicate purifying reactor and the alkali liquor generated by the neutralizing reactor avoid the generation of waste liquor and realize zero emission in the process of extracting aluminum from fly ash.
(4) The purity of the products such as calcium silicate, silica gel, ferric hydroxide and the like generated in the extraction process is high, the calcium silicate can be recovered as a heat insulation material, the silica gel can be recovered as a high-activity adsorption material, and the ferric hydroxide can be recovered as a pigment or water purifying agent raw material. And no secondary solid waste is generated in the alumina extraction process, so that the high-value utilization of the fly ash is truly realized.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a diagram of the calcium silicate, silica gel, iron hydroxide and alumina products recovered in example 2;
FIG. 3 is a graph showing the optimized reaction conditions of the pre-desilication process of fly ash and the extraction process of calcium silicate;
FIG. 4 shows the optimized reaction conditions of the pre-desilication fly ash activation calcination process and the acid leaching process.
The figure indicates:
1-grinding machine, 2-screen machine, 3-pre-desilication reactor, 4-first sedimentation tank, 5-calcium silicate purifying reactor, 6-second sedimentation tank, 7-activation calcining reactor, 8-acid leaching reactor, 9-third sedimentation tank, 10-ferric hydroxide purifying reactor, 11-fourth sedimentation tank, 12-neutralization reactor, 13-fifth sedimentation tank, 14-high temperature calcining reactor, 15-pre-desilication agent doser, 16-desilication agent doser, 17-activator doser, 18-acid leaching liquor doser, 19-ferric hydroxide purifying agent doser and 20-neutralizer doser.
Detailed Description
The system for producing high-purity alumina by recycling the fly ash of the invention is described in detail below.
In the description of the present invention, it should be noted that the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In order to truly realize solid waste recycling, the invention provides a system for producing high-purity alumina by recycling fly ash, which is structurally shown in figure 1, and comprises a grinder 1, a predesilica reactor 3, an activated calcination reactor 7, an acid leaching reactor 8, an iron hydroxide purification reactor 10, a neutralization reactor 12 and a high-temperature calcination reactor 14 which are sequentially connected along the direction of extracting alumina, wherein the predesilica reactor 3 is also connected with a predesilica agent doser 15, the activated calcination reactor 7 is also connected with an activator doser 17, the acid leaching reactor 8 is also connected with an acid leaching liquor doser 18, the iron hydroxide purification reactor 10 is also connected with an iron hydroxide purification agent doser 19, and the neutralization reactor 12 is also connected with a neutralizer doser 20.
The grinding machine 1 in the invention is a device for grinding materials, which is commonly used in the field, in addition, fine powder particles obtained by sieving after grinding and coarse powder particles are relatively "fine" and "coarse" so as to be convenient for distinguishing, and the specific particle size range is determined according to practical requirements.
In some embodiments, the liquid outlet of the pre-desilication reactor 3 is also connected with a calcium silicate purification reactor 5, the calcium silicate purification reactor 5 is also connected with a silicon removing agent adder 16, and the liquid outlet of the calcium silicate purification reactor 5 is also connected with the pre-desilication reactor 3 in a return way. Furthermore, a second sedimentation tank 6 is arranged between the calcium silicate purifying reactor 5 and the pre-desilication reactor 3.
In some embodiments, a screen 2 is further provided between the grinder 1 and the pre-desilication reactor 3, wherein the coarse powder outlet of the screen 2 is also connected back to the inlet of the grinder 1. The number of the screen meshes on the screen machine 2 can be designed to be 5-1500 meshes according to actual requirements.
In some embodiments, along the alumina extraction direction, a first sedimentation tank 4 is further arranged between the pre-desilication reactor 3 and the activation calcination reactor 7, a third sedimentation tank 9 is further arranged between the acid leaching reactor 8 and the ferric hydroxide purification reactor 10, a fourth sedimentation tank 11 is further arranged between the ferric hydroxide purification reactor 10 and the neutralization reactor 12, and a fifth sedimentation tank 13 is further arranged between the neutralization reactor 12 and the high-temperature calcination reactor 14.
In some embodiments, the liquid outlet of the neutralization reactor 12 is also connected back to the inlet of the ferric hydroxide purification reactor 10.
The method for producing high-purity alumina by recycling the fly ash of the invention is continuously described in the following.
Based on the system, the invention also provides a method for producing high-purity alumina by recycling fly ash, the specific flow can be seen in FIG. 1, and the method comprises the following steps:
(1) Adding fly ash to be treated into a grinder 1 for grinding treatment, sieving to obtain fine powder particles, discharging the fine powder particles into a pre-desilication reactor 3, adding a pre-desilication agent for pre-desilication treatment, and discharging precipitate into an activation calcination reactor 7 after solid-liquid separation of the treated muddy water mixed solution;
(2) Adding an activating agent into the activating and calcining reactor 7, activating and calcining, and discharging the obtained calcined product into the acid leaching reactor 8;
(3) Adding acid leaching solution into an acid leaching reactor 8 for acid leaching reaction, settling and separating the obtained reaction product, and discharging supernatant into an iron hydroxide purification reactor 10;
(4) Adding ferric hydroxide purifying agent into the ferric hydroxide purifying reactor 10 for purifying treatment, precipitating and separating the treated mixed solution, and continuously discharging the obtained supernatant into the neutralizing reactor 12;
(5) Adding a neutralizing agent into the neutralization reactor 12 to continuously adjust the pH, then settling and separating to obtain an aluminum hydroxide precipitate, and discharging the aluminum hydroxide precipitate into the high-temperature calcination reactor 14;
(6) And (3) calcining the aluminum hydroxide precipitate sent into the high-temperature calcination reactor 14 at high temperature to obtain the high-purity aluminum oxide.
In some embodiments, in step (1), the pre-desilication treatment has a reaction time of 30 to 1000 minutes.
In some embodiments, in step (2), the activation calcination is performed at a temperature of 100 to 1500 ℃ for a time of 10 to 500 minutes.
In some embodiments, in step (3), the temperature of the acid dissolution reaction is 25-100 ℃ for 30-600min.
In some embodiments, in step (4), the time of the purification treatment is 30-500 minutes.
In some embodiments, in step (6), the high temperature calcination is at a temperature of 400 to 1500 ℃ for a time of 10 to 300 minutes.
In some embodiments, the pre-desilication agent is one or more of sodium hydroxide, calcium oxide or potassium hydroxide, and is added in the form of solution or slurry, wherein the mass percentage of the pre-desilication agent is 5-50%, and the addition amount of the pre-desilication agent is 100-50000mL. The pre-desilicating agent is preferably calcium hydroxide or sodium hydroxide, in admixture with calcium oxide or calcium hydroxide.
In some embodiments, the activator is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, and the mass ratio of the activator to the precipitate obtained after pre-desilication is 0.5-3.0.
In some embodiments, the pickle liquor is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid, the mass percentage is 5% -20%, corresponding to 5-1000g of fly ash, and the addition amount is 100-50000mL.
In some embodiments, the iron hydroxide purifying agent is one or more of sodium hydroxide, potassium hydroxide, calcium oxide, sodium bicarbonate or sodium carbonate, and the adding amount is 5-100g/L, wherein the adding amount is that 5-100g of the iron hydroxide purifying agent is correspondingly added to each 1L of the supernatant obtained in the step (3).
In some embodiments, the neutralizing agent is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid, and the adding amount is 5-200g/L.
In some embodiments, in step (1), the supernatant obtained by solid-liquid separation of the slurry-water mixture is further returned to the inlet of the pre-desilication reactor 3 after desilication treatment. The treatment time in the desilication treatment is 10-500min, and the desilication agent is one or more of calcium oxide, calcium hydroxide, calcium chloride or calcium fluoride, and the dosage is 5-200g/L.
In some embodiments, in step (2), the supernatant obtained after the pH adjustment and sedimentation separation in the neutralization reactor 12 is also refluxed to the inlet of the iron hydroxide purification reactor 10.
The reaction principle of each part of the invention is as follows:
1) Pre-desilication stage: firstly, primarily removing impurity silicon in the fly ash, dissolving part of silicon dioxide by adding strong alkali, and then adding calcium salt to obtain high-purity calcium silicate. The reaction formula is shown in (1) - (3).
2) Calcination activation: the addition of the activating agent and the high-temperature calcination can convert mullite in the fly ash into nepheline, so that the activity is greatly improved, the subsequent aluminum extraction difficulty is reduced, and the aluminum extraction rate is improved. The reaction formula is shown in (4) - (8).
3Na 2 CO 3 +Al 6 Si 2 O 13 →NaAlSiO 4 +4NaAlO 2 +3CO 2 (4)
SiO 2 +Na 2 CO 3 →2NaSiO 3 +CO 2 ↑ (5)
Al 2 O 3 +Na 2 CO 3 →2NaAlO 2 +CO 2 ↑ (6)
Fe 2 O 3 +Na 2 CO 3 →Na 2 O·Fe 2 O 3 +CO 2 ↑ (7)
4Fe 3 O 4 +6Na 2 CO 3 +O 2 →6Na 2 O·Fe 2 O 3 +6CO 2 ↑ (8)
3) Silica gel purification stage: the addition of acid dissolves and activates the calcined nepheline and iron oxide, thereby obtaining a high purity silicic acid colloid. The reaction formula is shown in (9) - (11).
2NaAlSiO 4 +8H + →2H 2 SiO 3 ↓+2Na + +2Al 3+ +2H 2 O (9)
Na 2 O·Fe 2 O 3 +8H + →2Na + +Fe 3+ +4H 2 O (11)
3) And (3) ferric hydroxide purification: the addition of the alkali can directly convert aluminum ions into metaaluminate ions, and convert iron ions into ferric hydroxide precipitates for recovery.
2Fe 3+ +6OH - →2Fe(OH)3↓ (13)
4) Neutralization reaction stage: and adding acid into the solution to adjust the pH to about 8, so that the metaaluminate can be converted into aluminum hydroxide precipitate.
5) Alumina extraction stage: and (3) carrying out high-temperature roasting on the aluminum hydroxide precipitate to obtain high-purity aluminum oxide.
2Al(OH) 3 →Al 2 O 3 +3H 2 O(g) (15)
In order to more clearly illustrate the examples of the present invention or the implementation methods in the prior art, the following description will briefly explain the flame retardant properties of the examples and desulfurization wastewater desulfurization precipitate, the examples and the drawings described below are only some examples of the present invention, and other examples or drawings can be obtained according to these drawings without making any inventive effort for a person skilled in the art.
Example 1:
a system and a method for producing high-purity alumina by recycling fly ash are shown in figure 1, wherein the extraction flow is shown as the accompanying drawing, and the system comprises a grinder 1, a screen machine 2, a pre-desilication reactor 3, a first sedimentation tank 4, a calcium silicate purification reactor 5, a second sedimentation tank 6, an activation calcination reactor 7, an acid leaching reactor 8, a third sedimentation tank 9, a ferric hydroxide purification reactor 10, a fourth sedimentation tank 11, a neutralization reactor 12, a fifth sedimentation tank 13 and a high-temperature calcination reactor 14 which are connected in sequence. Wherein, the pre-desilication reactor 3 is also connected with a pre-desilication agent doser 15, the calcium silicate purification reactor 5 is also connected with a desilication agent doser 16, the activation calcination reactor 7 is also connected with an activation agent doser 17, the acid leaching reactor 8 is also connected with an acid leaching solution doser 18, the ferric hydroxide purification reactor 10 is also connected with a ferric hydroxide purification agent doser 19, and the neutralization reactor 12 is also connected with a neutralization agent doser 20.
The method comprises the following specific steps:
(1) Adding the fly ash to be treated into a grinder 1 for grinding, then feeding the fly ash into a screen machine 2, discharging fine powder particles separated by screening of the screen machine into a pre-desilication reactor 3, and discharging the coarse powder particles back into the grinder 1 for continuous grinding;
(2) Adding a pre-desilication agent into the pre-desilication reactor 3 for pre-desilication treatment, performing solid-liquid separation on the treated muddy water mixed solution in a first sedimentation tank 4, discharging the obtained precipitate into an activation calcination reactor 7 for activation calcination, discharging the supernatant into a calcium silicate purification reactor 5 for adding a desilication agent, performing sedimentation separation in a second sedimentation tank 6, and refluxing the supernatant into the pre-desilication reactor 3, wherein the precipitate is calcium silicate solid;
(3) After adding an activating agent into the activating and calcining reactor 7, calcining and activating the mixture, converting mullite in the fly ash into nepheline, improving the activity of the nepheline so as to promote the subsequent leaching of aluminum, and discharging a calcined product into the acid leaching reactor 8;
(4) Adding acid leaching solution into an acid leaching reactor 8 for acid leaching reaction, settling and separating in a third sedimentation tank 9, and discharging supernatant into an iron hydroxide purification reactor 10, wherein the sediment is silica gel;
(5) Adding an iron hydroxide purifying agent into an iron hydroxide purifying reactor 10 for reaction, settling and separating in a fourth sedimentation tank 11, and discharging supernatant into a neutralizing reactor 12 to obtain precipitate, namely iron hydroxide;
(6) Adding a neutralizing agent into the neutralization reactor 12, continuously adjusting the pH, settling and separating by a fifth sedimentation tank 13, refluxing supernatant to the ferric hydroxide purification reactor 10, discharging aluminum hydroxide precipitate into a high-temperature calcination reactor 14, and calcining to obtain a high-purity aluminum oxide product.
Example 2:
on the basis of the alumina extraction process of example 1, the operating process parameters of this example are as follows:
table 1 fly ash chemical composition of certain electric power plant in inner Mongolia
| Chemical composition | Al 2 O 3 | SiO 2 | Fe 2 O 3 | CaO | MgO | Na 2 O | K 2 O |
| Wt％ | 29.64 | 48.26 | 5.54 | 9.66 | 1.20 | 1.44 | 0.90 |
The fly ash to be treated is taken from a coal-fired power plant of inner Mongolia, and the chemical composition of the fly ash is shown in table 1. From X-ray fluorescence spectroscopy (XRF), the fly ash belongs to low-aluminum high-calcium fly ash.
In this example, 30g of fly ash treated by the mill 1 and the screen 2 was weighed, wherein the screen 2 used had a mesh size of 200 mesh (80 μm). The reaction time in the pre-desilication reactor 3 is 60min, the pre-desilication agent is 600mL of sodium hydroxide with the mass fraction of 20%, the supernatant fluid is discharged into the calcium silicate purification reactor 5 after sedimentation and separation in the second sedimentation tank 4, the reaction time is 30min, the calcium silicate purification agent is calcium oxide, the adding amount of the calcium silicate purification agent is 20g/L, the supernatant fluid flows back to the inlet of the pre-desilication reactor 3 after sedimentation and separation in the second sedimentation tank 6, the obtained calcium silicate precipitate can be recycled as a heat insulation product, and each measurement index is compared with the national standard (calcium silicate heat insulation product) (GB/T10699-2015) as shown in the table 2.
Table 2 comparison of measurement index of calcium silicate insulation product
The pre-desilication fly ash sediment generated in the second sedimentation tank 4 is sent into an activation calcination reactor 7, the reaction time is 120min, the used activating agent is sodium carbonate, and the mass ratio of the adding amount to the pre-desilication fly ash sediment is 1.2:1. After calcination, the activated product is sent to an acid leaching tank 8.
Table 3 comparison of silica gel desiccant measurement indicators for packaging
| Index (I) | Silica gel product | GB 10455-1989 |
| Content (including structural water,%) | 98.2 | ≥98 |
| pH | 4.3 | 4-8 |
| Specific resistance (omega cm) | 2740 | ≥2000 |
| Weight loss on drying (%) | 2.3 | ≤2.5 |
The reaction time in the acid leaching tank 8 is 30min, the used acid leaching liquid is 200mL 1mol/L sulfuric acid, the sulfuric acid leaching can remove the residual impurity silicon in the form of silicic acid colloid, the residual impurity silicon is precipitated and separated by the third precipitation tank 9, the supernatant fluid is discharged into the ferric hydroxide purification reactor 10, the obtained silica gel precipitate can be used as a silica gel drying agent for recycling, and the measurement indexes of the silica gel precipitate and the national standard silica gel drying agent for packaging (GB 10455-1989) are shown in the table 3.
The effluent of the third sedimentation tank 9 enters an iron hydroxide purification reactor 10, the reaction time is 25min, the iron hydroxide purifying agent is sodium hydroxide, the adding amount is 5g/L, the supernatant fluid is discharged into a neutralization reactor 12 after sedimentation and separation in a fourth sedimentation tank 11, and the obtained precipitate is iron hydroxide.
The effluent of the fourth sedimentation tank 11 enters a neutralization reactor 12, the reaction time is 30min, the neutralizing agent is hydrochloric acid, the adding amount is 80g/L, the supernatant fluid flows back to the ferric hydroxide purification reactor 10 after sedimentation and separation by a fifth sedimentation tank 13, and the obtained precipitate is aluminum hydroxide.
The aluminum hydroxide precipitate produced in the fifth sedimentation tank 13 is discharged into a high-temperature calcination reactor 14, the reaction time is 90min, the calcination temperature is 1200 ℃, the calcination product is high-purity alumina, and the indexes and the national standard alumina (GB/T24487-2009) are shown in a table 4.
Table 4 comparison of alumina measurement index
| Chemical composition (wt%) | Alumina product | GB/T 24487-2009 |
| Al 2 O 3 | 98.6 | ≥98.4 |
| SiO 2 | 0.04 | ≤0.06 |
| Fe 2 O 3 | 0.01 | ≤0.03 |
| Na 2 O | 0.59 | ≤0.7 |
| Burning loss | 0.9 | ≤1.0 |
Fig. 2 is a diagram of the recovered calcium silicate, silica gel, ferric hydroxide and alumina products, and it can be seen from the diagram that the quality of each product recovered by the process is better, and various other high-value byproducts can be simultaneously extracted on the basis of alumina extraction, so that the high-value utilization of the fly ash is realized.
FIG. 3 shows the results of an experiment for optimizing partial reaction conditions in a pre-desilication reactor and a calcium silicate purification reactor, and by optimizing the addition amount of the pre-desilication agent (FIG. 3 (a)), the silicon dioxide in the fly ash can be maximally initially dissolved, the loss of aluminum in the pre-desilication process can be reduced, and the influence of the aluminum on the subsequent purification process can be reduced. By optimizing the amount of the calcium silicate purifying agent added (fig. 3 (b)), the extraction of calcium silicate can be realized, and the purity of the silicon product can be ensured.
FIG. 4 shows the results of an experiment for optimizing the partial reaction conditions in the activation calcination reactor 7 and the acid leaching reactor 8, and the optimum reaction conditions were established by examining the influence of the reaction temperature, the reaction time, and the addition amount of the activator on the leaching effect of the subsequent oxidized aluminate (FIG. 4 (a)). By examining the effect of the concentration of the pickling solution, the pickling temperature and the pickling time on the leaching effect of alumina (fig. 4 (b)), the maximum leaching of alumina in the pickling reactor is ensured.
Example 3:
compared to example 2, the vast majority are identical, except in this example: the fly ash to be treated was obtained from a power plant in the Shanghai and its chemical composition is shown in Table 5. According to X-ray fluorescence spectrum analysis (XRF), the fly ash belongs to high-aluminum low-calcium fly ash.
TABLE 5 fly ash chemical composition for Shanghai certain Power plant
| Chemical composition | Al 2 O 3 | SiO 2 | Fe 2 O 3 | CaO | MgO | TiO 2 | K 2 O |
| Wt％ | 39.73 | 50.67 | 3.86 | 2.48 | 0.533 | 1.44 | 0.788 |
In this example, 30g of fly ash treated by the mill 1 and the screen 2 was weighed, wherein the screen 2 used had a mesh size of 400 mesh (40 μm). The reaction time in the pre-desilication reactor 3 is 50min, the pre-desilication agent is 600mL of sodium hydroxide with mass fraction of 15%, the supernatant fluid is discharged into the calcium silicate purification reactor 5 after sedimentation and separation in the second sedimentation tank 4, the reaction time is 25min, the used calcium silicate purification agent is calcium hydroxide, the dosage of the calcium silicate purification agent is 25g/L, the supernatant fluid flows back to the inlet of the pre-desilication reactor 3 after sedimentation and separation in the second sedimentation tank 6, the obtained calcium silicate precipitate can be recycled as a heat insulation product, and the measurement indexes of the calcium silicate precipitate are compared with those of the national standard (GB/T10699-2015) as shown in Table 6.
Table 6 comparison of measurement index of calcium silicate insulation product
| Index (I) | Calcium silicate products | GB/T 10699-2015 |
| Density (kg/m) 3 ) | 232 | ≤240 |
| Average resistanceCompressive strength (MPa) | 0.67 | ≥0.65 |
| Average flexural strength (MPa) | 0.34 | ≥0.33 |
| Coefficient of thermal conductivity (100 ℃, W/(m.K)) | 0.054 | ≤0.065 |
| Mass water content (%) | 2.56 | ≤7.5 |
| Dimensional stability (%) | 0.9 | ≤1.0 |
| Linear shrinkage (%) | 1.8 | ≤2.0 |
The pre-desilication fly ash sediment generated in the second sedimentation tank 4 is sent into an activation calcination reactor 7, the reaction time is 120min, the used activating agent is sodium carbonate, and the mass ratio of the adding amount to the pre-desilication fly ash sediment is 1.4:1. After calcination, the activated product is sent to an acid leaching tank 8.
The reaction time in the acid leaching tank 8 is 25min, the used acid leaching liquid is 200mL 1mol/L hydrochloric acid, the residual impurity silicon can be removed in the form of silicic acid colloid by leaching of the hydrochloric acid, the residual impurity silicon is precipitated and separated by the third precipitation tank 9, the supernatant is discharged into the ferric hydroxide purification reactor 10, the obtained silica gel precipitate can be used as a silica gel drying agent for recycling, and various measurement indexes of the silica gel precipitate are shown in a table 7 in the specification of national standard silica gel drying agent for packaging (GB 10455-1989).
Table 7 comparison of silica gel desiccant measurement indicators for packaging
| Index (I) | Silica gel product | GB 10455-1989 |
| Content (including structural water,%) | 98.1 | ≥98 |
| pH | 4.1 | 4-8 |
| Specific resistance (omega cm) | 2639 | ≥2000 |
| Weight loss on drying (%) | 2.4 | ≤2.5 |
The effluent of the third sedimentation tank 9 enters an iron hydroxide purification reactor 10, the reaction time is 25min, the iron hydroxide purifying agent is sodium hydroxide, the adding amount is 10g/L, the supernatant fluid is discharged into a neutralization reactor 12 after sedimentation and separation in a fourth sedimentation tank 11, and the obtained precipitate is iron hydroxide.
The effluent of the fourth sedimentation tank 11 enters a neutralization reactor 12, the reaction time is 45min, the neutralizing agent is hydrochloric acid, the adding amount is 75g/L, the supernatant fluid flows back to the ferric hydroxide purification reactor 10 after sedimentation and separation by a fifth sedimentation tank 13, and the obtained precipitate is aluminum hydroxide.
The aluminum hydroxide precipitate produced in the fifth sedimentation tank 13 is discharged into a high-temperature calcination reactor 14, the reaction time is 120min, the calcination temperature is 1100 ℃, the calcined product is high-purity alumina, and the indexes and the national standard alumina (GB/T24487-2009) are shown in a table 8.
Table 8 comparison of alumina measurement index
| Chemical composition (wt%) | Alumina product | GB/T 24487-2009 |
| Al 2 O 3 | 98.4 | ≥98.4 |
| SiO 2 | 0.05 | ≤0.06 |
| Fe 2 O 3 | 0.02 | ≤0.03 |
| Na 2 O | 0.65 | ≤0.7 |
| Burning loss | 1.0 | ≤1.0 |
The treatment reagents and the corresponding treatment process conditions used in the above examples may be optionally adjusted (i.e., may be adjusted to any one of the end values or any one of the intermediate point values) within the following ranges according to the actual conditions:
the reaction time of the pre-desilication treatment is 30-1000min;
the activation and calcination temperature is 100-1500 ℃ and the time is 10-500min;
the temperature of the acid dissolution reaction is 25-100 ℃ and the time is 30-600min;
the purification treatment time of ferric hydroxide is 30-500min.
The high-temperature calcination temperature is 400-1500 ℃ and the high-temperature calcination time is 10-300min;
the pre-desilication agent is one or more of sodium hydroxide, calcium oxide or potassium hydroxide, the pre-desilication agent is added in the form of solution or slurry, the corresponding mass percentage is 5-50%, and the corresponding mass percentage is 5-1000g of fly ash, the addition amount is 100-50000mL, and the pre-desilication agent is preferably calcium hydroxide or sodium hydroxide and is mixed with calcium oxide or calcium hydroxide;
the activating agent is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, and the mass ratio of the activating agent to the precipitate obtained after pre-desilication is 0.5-3.0;
the pickle liquor is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid, the mass percentage is 5% -20%, corresponding to 5-1000g of fly ash, and the addition amount is 100-50000mL;
the ferric hydroxide purifying agent is one or more of sodium hydroxide, potassium hydroxide, calcium oxide, sodium bicarbonate or sodium carbonate, the adding amount is 5-100g/L, namely 5-100g of ferric hydroxide purifying agent is correspondingly added to each 1L of supernatant obtained in the step (3);
the neutralizing agent is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid, and the adding amount is 5-200g/L;
in the step (1), supernatant obtained by solid-liquid separation of the muddy water mixed solution is subjected to desilication treatment and then returned to the inlet of the pre-desilication reactor, the treatment time in the desilication treatment is 10-500min, and the desilication agent is one or more of calcium oxide, calcium hydroxide, calcium chloride or calcium fluoride, and the adding amount is 5-200g/L.
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (7)
1. The system for producing the high-purity alumina by recycling the fly ash is characterized by comprising a grinder, a predesilica reactor, an activation calcination reactor, an acid leaching reactor, an iron hydroxide purification reactor, a neutralization reactor and a high-temperature calcination reactor which are sequentially connected along the direction of extracting the alumina, wherein the predesilica reactor is also connected with a predesilica agent doser, the activation calcination reactor is also connected with an activator doser, the acid leaching reactor is also connected with an acid leaching solution doser, the iron hydroxide purification reactor is also connected with an iron hydroxide purification agent doser, and the neutralization reactor is also connected with a neutralizer doser;
the liquid outlet of the pre-desilication reactor is also connected with a calcium silicate purification reactor, the calcium silicate purification reactor is also connected with a silicon removing agent adder, and the liquid outlet of the calcium silicate purification reactor is also connected with the pre-desilication reactor in a return way;
a second sedimentation tank is also arranged between the calcium silicate purification reactor and the pre-desilication reactor;
along the direction of extracting alumina, a first sedimentation tank is further arranged between the pre-desilication reactor and the activation calcination reactor, a third sedimentation tank is further arranged between the acid leaching reactor and the ferric hydroxide purification reactor, a fourth sedimentation tank is further arranged between the ferric hydroxide purification reactor and the neutralization reactor, and a fifth sedimentation tank is further arranged between the neutralization reactor and the high-temperature calcination reactor.
2. The system for producing high-purity alumina by recycling fly ash according to claim 1, wherein a screen machine is further arranged between the grinder and the pre-desilication reactor, and wherein a coarse powder outlet of the screen machine is further connected with an inlet of the grinder in a return manner.
3. The system for producing high purity alumina by recycling fly ash according to claim 1, wherein the liquid outlet of the neutralization reactor is also connected back to the inlet of the iron hydroxide purification reactor.
4. A method for producing high purity alumina from fly ash as a resource, which is realized based on the system as claimed in any one of claims 1 to 3, characterized in that the method comprises the following steps:
(1) Grinding the fly ash to be treated in a grinder, sieving to obtain fine powder particles, discharging the fine powder particles into a pre-desilication reactor, adding a pre-desilication agent for pre-desilication treatment, and discharging the precipitate into an activation calcination reactor after solid-liquid separation of the treated muddy water mixed solution;
(2) Adding an activating agent into an activating and calcining reactor, activating and calcining, and discharging the obtained calcined product into an acid leaching reactor;
(3) Adding acid leaching liquid into an acid leaching reactor for acid leaching reaction, settling and separating the obtained reaction product, and discharging supernatant into an iron hydroxide purification reactor;
(4) Adding an iron hydroxide purifying agent into an iron hydroxide purifying reactor for purifying treatment, and precipitating and separating the mixed solution after the treatment is finished, and continuously discharging the obtained supernatant into a neutralizing reactor;
(5) Adding a neutralizing agent into the neutralization reactor to continuously adjust the pH value, then settling and separating to obtain an aluminum hydroxide precipitate, and discharging the aluminum hydroxide precipitate into a high-temperature calcination reactor;
(6) And (3) calcining the aluminum hydroxide precipitate sent into the high-temperature calcining reactor at high temperature to obtain the high-purity aluminum oxide.
5. The method for producing high-purity alumina by recycling fly ash according to claim 4, wherein in the step (1), the reaction time of the pre-desilication treatment is 30-1000min;
in the step (2), the temperature of activation and calcination is 100-1500 ℃ and the time is 10-500min;
in the step (3), the temperature of the acid dissolution reaction is 25-100 ℃ and the time is 30-600min;
in the step (4), the purification treatment time is 30-500min;
in the step (6), the high-temperature calcination temperature is 400-1500 ℃ and the time is 10-300min.
6. The method for producing high-purity alumina by recycling fly ash according to claim 4, wherein the pre-desilicating agent is one or more of sodium hydroxide, calcium oxide or potassium hydroxide;
the activator is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, and the adding amount of the activator is 10-300g/L;
the pickle liquor is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid;
the ferric hydroxide purifying agent is one or more of sodium hydroxide, potassium hydroxide, calcium oxide, sodium bicarbonate or sodium carbonate;
the neutralizing agent is one or more of hydrochloric acid, sulfuric acid, nitric acid or oxalic acid.
7. The method for producing high-purity alumina by recycling fly ash according to claim 4, wherein in the step (1), supernatant obtained by solid-liquid separation of the slurry-water mixture is returned to the inlet of the pre-desilication reactor after desilication treatment;
in the step (2), the supernatant obtained after the pH adjustment and the sedimentation separation in the neutralization reactor is also refluxed to the inlet of the ferric hydroxide purification reactor.
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| CN110577231A (en) * | 2019-09-06 | 2019-12-17 | 于谦 | method for extracting aluminum oxide and coproducing silicon oxide and ferric oxide from fly ash |
| CN215048708U (en) * | 2021-04-21 | 2021-12-07 | 上海电力大学 | System for fly ash resourceful production high-purity alumina |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103303952A (en) * | 2012-03-06 | 2013-09-18 | 中国科学院过程工程研究所 | Method for linked preparation of sodium aluminate and production of silica-based material by means of high-alumina fly ash low-temperature liquid-phase alkali dissolving |
| CN102897810A (en) * | 2012-11-06 | 2013-01-30 | 大唐国际发电股份有限公司 | Method for producing aluminum oxide by using fly ash |
| CN108622920A (en) * | 2018-05-30 | 2018-10-09 | 大唐国际发电股份有限公司高铝煤炭资源开发利用研发中心 | A kind of method of aluminous fly-ash extraction aluminium oxide |
| CN110577231A (en) * | 2019-09-06 | 2019-12-17 | 于谦 | method for extracting aluminum oxide and coproducing silicon oxide and ferric oxide from fly ash |
| CN215048708U (en) * | 2021-04-21 | 2021-12-07 | 上海电力大学 | System for fly ash resourceful production high-purity alumina |
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