CN111874927A - Carbon method aluminum oxide energy-saving emission-reducing production method - Google Patents
Carbon method aluminum oxide energy-saving emission-reducing production method Download PDFInfo
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- CN111874927A CN111874927A CN202010575442.4A CN202010575442A CN111874927A CN 111874927 A CN111874927 A CN 111874927A CN 202010575442 A CN202010575442 A CN 202010575442A CN 111874927 A CN111874927 A CN 111874927A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 103
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 103
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims description 44
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 title claims description 24
- 239000012452 mother liquor Substances 0.000 claims abstract description 91
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 85
- 239000003546 flue gas Substances 0.000 claims abstract description 78
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 76
- 238000001704 evaporation Methods 0.000 claims abstract description 36
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims abstract description 35
- 230000008020 evaporation Effects 0.000 claims abstract description 35
- 238000005194 fractionation Methods 0.000 claims abstract description 14
- 239000007787 solid Substances 0.000 claims description 26
- 238000000926 separation method Methods 0.000 claims description 20
- 239000000428 dust Substances 0.000 claims description 17
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 claims description 11
- 229910001388 sodium aluminate Inorganic materials 0.000 claims description 11
- 239000000706 filtrate Substances 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 10
- 239000003513 alkali Substances 0.000 claims description 9
- 238000000354 decomposition reaction Methods 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000002994 raw material Substances 0.000 claims description 8
- 238000005507 spraying Methods 0.000 claims description 6
- 229910052593 corundum Inorganic materials 0.000 claims description 3
- 238000004134 energy conservation Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 claims description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 3
- 239000004480 active ingredient Substances 0.000 claims description 2
- 239000000725 suspension Substances 0.000 claims description 2
- 239000010413 mother solution Substances 0.000 claims 2
- 239000000243 solution Substances 0.000 claims 1
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 239000002918 waste heat Substances 0.000 abstract description 5
- 238000004064 recycling Methods 0.000 abstract description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 8
- 239000000047 product Substances 0.000 description 5
- RAHZWNYVWXNFOC-UHFFFAOYSA-N sulfur dioxide Inorganic materials O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 3
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 3
- 239000003518 caustics Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 229910001570 bauxite Inorganic materials 0.000 description 2
- JHLNERQLKQQLRZ-UHFFFAOYSA-N calcium silicate Chemical compound [Ca+2].[Ca+2].[O-][Si]([O-])([O-])[O-] JHLNERQLKQQLRZ-UHFFFAOYSA-N 0.000 description 2
- 229910052918 calcium silicate Inorganic materials 0.000 description 2
- 235000012241 calcium silicate Nutrition 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- WPUINVXKIPAAHK-UHFFFAOYSA-N aluminum;potassium;oxygen(2-) Chemical compound [O-2].[O-2].[Al+3].[K+] WPUINVXKIPAAHK-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- 239000012716 precipitator Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 231100000241 scar Toxicity 0.000 description 1
- 239000011265 semifinished product Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- 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
-
- 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
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
- C01F7/141—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by neutralisation with an acidic agent
- C01F7/142—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by neutralisation with an acidic agent with carbon dioxide
-
- 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
- C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/004—Systems for reclaiming waste heat
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention belongs to the technical field of alumina production, and particularly discloses a carbon fractionation alumina energy-saving emission-reduction production method obtained by improving the traditional carbon fractionation alumina production process. The invention improves the existing alumina production process, and directly mixes and exchanges heat between the carbonation mother liquor after decomposing aluminum hydroxide by carbonation and alumina roasting flue gas to obtain concentrated carbonation mother liquor and clean flue gas, thereby realizing the recycling of flue gas waste heat, simultaneously obviously reducing the evaporation energy consumption of the carbonation mother liquor, improving the cycle efficiency of an alumina production system, and realizing the standard emission of the flue gas.
Description
Technical Field
The invention relates to the technical field of alumina production, in particular to a carbon fractionation alumina energy-saving emission-reduction production method obtained by improving the traditional carbon fractionation alumina production process.
Background
The traditional industrial production process of alumina by carbon method is to mix CO2Introducing gas into the sodium aluminate fine liquid obtained by desiliconization and refining, carbonating the sodium aluminate fine liquid to decompose and separate out aluminum hydroxide, then filtering and washing to obtain aluminum hydroxide solid, and separating to obtain a liquid phase which is a carbon separation mother liquid; the aluminum hydroxide solid is sent to a roasting furnace to be roasted to obtain an aluminum oxide product, the carbon content mother liquor is evaporated and concentrated to obtain an evaporation mother liquor, and the evaporation mother liquor is continuously added to the raw material process for proportioning, namely is mixed with the bauxite. The main energy consumption links of the traditional carbon method alumina production process are the evaporation of carbon separation mother liquor and the roasting of aluminum hydroxide.
The aluminum hydroxide roasting furnace is one of core equipment for producing aluminum oxide and is also main energy-consuming equipment. The aluminum hydroxide roasting furnace usually takes natural gas, producer gas and coke oven gas as fuels, and has high energy consumption of about 2.8-3.3 GJ/t-alumina. The temperature of the flue gas of the aluminum hydroxide roasting furnace is 130-200 ℃, the water content in the flue gas is 30-40%, the water content in the flue gas is in an unsaturated state, and the flue gas of the roasting furnace contains CO2Gas content is about 10%. The flue gas produced by the roasting furnace at present is subjected to dust recovery by an electric precipitator, and the dust content is 100g/m3Reduced to 30mg/m3The following (part of the bag dust collector adopts a metal filter bag dust collector to reach 10mg/m3Below) and then vented to the atmosphere through a chimney. The existing roasting furnace flue gas treatment and discharge does not consider the utilization of the waste heat of the roasting furnace flue gas, thereby causing the waste of heat energy, and the content of flue gas dust also fails to meet the related requirements of ultralow discharge.
The existing carbonation decomposition of sodium aluminate fine liquid is to introduce high-concentration CO with the concentration of more than 30 percent into the sodium aluminate fine liquid2The gas is decomposed, and the sodium aluminate solution absorbs CO2About 90% of the alumina is precipitated as aluminum hydroxide, and the precipitated aluminum hydroxide passes throughAnd (4) carrying out liquid-solid separation to obtain a carbon content mother liquor and an aluminum hydroxide solid. On one hand, under the existing carbon content process condition, about 10% of alumina in the carbon content mother liquor is not decomposed and separated out, and the concentration of the alumina in the carbon content mother liquor is about 10-15 g/L. This portion of the alumina forms an inefficient cycle in the production process, causing a significant loss of energy. On the other hand, the carbon content mother liquor directly enters the evaporation process for evaporation, and Na in the carbon content mother liquor is used as Na2The concentration of O is low, and a large amount of steam is required to be consumed in the evaporation process, so that the method is an important energy consumption link in the production process of the alumina.
For the reasons, research and innovation are needed for the traditional industrial carbon fractionation alumina production process so as to reduce production energy consumption and improve energy utilization rate.
Disclosure of Invention
The invention mainly solves the technical problem of providing an energy-saving and emission-reducing production method of aluminum oxide by a carbon fractionation method.
In order to solve the technical problems, the invention adopts a technical scheme that: a carbon method alumina energy-saving emission-reducing production method comprises the following steps:
directly contacting the flue gas of the alumina roasting furnace with the carbon content mother liquor for heat exchange, raising the temperature of the carbon content mother liquor after heat exchange and improving the concentration of total alkali, and separating out aluminum hydroxide solid from the carbon content mother liquor after heat exchange;
carrying out solid-liquid separation on the carbon content mother liquor subjected to heat exchange to respectively obtain fine aluminum hydroxide solid and filtrate, and treating the filtrate to serve as evaporation mother liquor and sending the evaporation mother liquor to a raw material process for batching; sending the fine aluminum hydroxide solid to a carbon decomposition tank for use as seeds; or the fine aluminum hydroxide solid is sent to be mixed with the sodium aluminate solution after carbonation decomposition, and then the mixture is filtered and washed to obtain the aluminum hydroxide solid;
SO in flue gas of aluminum oxide roasting furnace after heat exchange2The concentration is reduced to 30mg/m3The dust content was reduced to 10mg/Nm3And then, the flue gas of the aluminum oxide roasting furnace after heat exchange is subjected to demisting and precipitation treatment and then is discharged.
As a preferred embodiment, the flue gas of the alumina roasting furnace directly contacts with the carbon content mother liquor for heat exchange by adopting a reverse spraying method or a direct introducing method.
Preferably, the flue gas of the alumina roasting furnace directly contacts with a carbon content mother liquor by a reverse spraying method for heat exchange, and the carbon content mother liquor contacts with the flue gas of the alumina roasting furnace at least once. The carbon content mother liquor and the flue gas of the alumina roasting furnace can be contacted for many times, for example, the carbon content mother liquor after one-time contact heat exchange is introduced into next-stage spraying equipment and is contacted with the fresh flue gas from the alumina roasting furnace for heat exchange again, so that the carbon content mother liquor is further evaporated and concentrated.
Optionally, the flue gas of the alumina roasting furnace is any one of flue gas of an alumina gaseous suspension roasting furnace, flue gas of an alumina circulating fluidized roasting furnace and flue gas of an alumina fluidized flash roasting furnace.
Preferably, the flue gas indexes of the alumina roasting furnace are as follows: 36-40% of water vapor and CO26-10% of SO2The content of the active ingredient is 10-200 mg/m3The dust content is 5-100 mg/Nm3And the temperature of the flue gas is 130-200 ℃.
Preferably, the carbon content of the carbon content mother liquor is 90-110 g/L, the Nk content is 8-15 g/L, and Al is contained in the carbon content mother liquor2O3The content is 6-15 g/L.
Preferably, the carbon content mother liquor Al after heat exchange2O3The content is less than 5 g/L.
Preferably, the filtrate is treated to serve as evaporation mother liquor to be sent to a raw material process for batching, and the treatment is evaporation treatment. The carbon content mother liquor after the contact heat exchange with the flue gas of the alumina roasting furnace is obtained, then the solid-liquid separation is carried out to obtain filtrate, the filtrate can be evaporated by adopting the traditional evaporation treatment method, and the filtrate is taken as the evaporation mother liquor to be sent to the raw material process for batching after the requirement of the evaporation mother liquor is met. Because the flue gas of the alumina roasting furnace is subjected to contact heat exchange, the energy consumption required during evaporation is obviously reduced compared with that of the traditional process.
The production process flow chart of the alumina produced by the carbon method is shown in figure 1, and the production process comprises the following steps: bauxite and a certain amount of soda, evaporation mother liquor and lime (or limestone) are prepared into raw slurry, the raw slurry is sintered at high temperature, so that silicon oxide and lime are synthesized into water-insoluble calcium orthosilicate, aluminum oxide and soda are synthesized into water-soluble solid sodium aluminate or potassium aluminate, and iron oxide and soda are synthesized into sodium ferrite which can be hydrolyzed; when the sintered product (clinker) is dissolved out by using a dilute alkali solution, solid sodium aluminate enters the solution, sodium ferrite is hydrolyzed to release alkali, and ferric oxide enters the red mud together with calcium orthosilicate by using hydrate; decomposing the sodium aluminate solution by carbon dioxide to separate out aluminum hydroxide; filtering the decomposed slurry to obtain aluminum hydroxide solid and carbon content mother liquor; roasting the aluminum hydroxide to obtain a product aluminum oxide; the carbon content mother liquor is evaporated to become evaporation mother liquor and returns to the ingredients.
The function of the alumina roasting furnace is to roast the aluminum hydroxide into the product alumina, the adopted fuel is generally natural gas, coke oven gas or generator gas, and the smoke components are relatively pure; the solid particle components in the flue gas are single, mainly comprise aluminum hydroxide and a small amount of aluminum oxide, and are semi-finished products and products produced by the aluminum oxide. The flue gas of the alumina roasting furnace has great utilization value.
The invention improves the existing alumina production process, and directly mixes and exchanges heat between the carbonation mother liquor after decomposing aluminum hydroxide by carbonation and alumina roasting flue gas to obtain concentrated carbonation mother liquor and clean flue gas, thereby realizing the recycling of flue gas waste heat, simultaneously obviously reducing the evaporation energy consumption of the carbonation mother liquor, improving the cycle efficiency of an alumina production system, and realizing the standard emission of the flue gas.
The carbon content mother liquor and the alumina roasting furnace flue gas are directly contacted and mixed, on the one hand, the heat exchange is realized, the flue gas waste heat can be fully recycled, the temperature of the carbon content mother liquor is improved, the carbon content mother liquor is concentrated, the concentration and the temperature of the solution entering the carbon content mother liquor evaporation process are improved, the energy consumption of the carbon content mother liquor evaporation can be obviously reduced, and the purpose of reducing the water evaporation amount in the carbon content mother liquor evaporation process and even canceling the carbon content mother liquor evaporation process can be achieved.
In the second aspect, the carbon content mother liquor also contains a small amount of caustic alkali and alumina, and the caustic alkali in the carbon content mother liquor reacts with carbon dioxide in the flue gasThe CO in the flue gas of the alumina roasting furnace2The gas is absorbed by the carbonation mother liquor, so that the alumina in the carbonation mother liquor is promoted to be continuously decomposed, the deep decomposition of the alumina in the carbonation mother liquor is realized, the carbonation decomposition rate is improved, the circulation efficiency of an alumina production system is improved, and the yield of the alumina is also improved.
In the third aspect, by utilizing the alkali-containing characteristic of the carbon content mother liquor, sulfur dioxide and nitrogen oxides in the flue gas of the alumina roasting furnace are fully absorbed in the direct contact with the carbon content mother liquor, and SO discharged by the flue gas2The concentration is obviously reduced, the flue gas desulfurization is realized, and the flue gas can reach the standard and be discharged; the flue gas of the alumina roasting furnace contains dust, the dust is mainly alumina particles, the alumina dust contained in the flue gas is collected by using the carbon content mother liquor, and the alumina particles enter the carbon content mother liquor, so that the alumina particles can be further separated to obtain aluminum hydroxide solid, the emission of the flue gas dust is reduced, the ultralow emission is realized, the alumina in the flue gas can be recovered, and the recovery rate of the alumina is improved.
Tests show that the method provided by the invention is adopted, namely, the alumina roasting flue gas and the carbon content mother liquor obtained after decomposing aluminum hydroxide by carbon content are directly mixed for heat exchange, the temperature of the carbon content mother liquor obtained after heat exchange can be increased from 70-90 ℃ to 80-100 ℃, the concentration of the carbon content mother liquor obtained after heat exchange changes along with the different proportion of the carbon content mother liquor and the flue gas, the concentration of the carbon content mother liquor can be increased by 1% -15%, the alumina which is not decomposed in the carbon content mother liquor is further decomposed, the carbon content mother liquor obtained after heat exchange concentration is subjected to liquid-solid separation is a solution, the alumina content is less than 5g/L, and the solution can be sent to a carbon content evaporation process for evaporation and then used for preparing alumina raw. The flue gas after direct contact heat exchange can realize the ultra-low emission of dust (less than 10 mg/m)3) And ultralow emission of sulfide in the flue gas of the roasting furnace can be realized. And no scar is formed in the operation process, and no influence is caused on an alumina production system. The energy-saving emission-reducing production method of the alumina by the carbon fractionation method is suitable for the reconstruction of the existing devices of the alumina production enterprises by the original sintering method or the original combination method and the implementation of new design projects, and can realize the effects of energy conservation and emission reduction.
Drawings
FIG. 1 is a flow chart of a production process for producing alumina by a conventional carbon separation method;
FIG. 2 is a flow chart of a process for producing alumina by a carbon separation method provided by the invention.
Detailed Description
The technical solution of the present invention will be explained in detail below.
Example 1
As shown in fig. 2, it is a process flow chart of the alumina production by the carbon separation method provided by the present invention, and the following improvements are made on the basis of the existing process flow of the alumina production by the carbon separation method, i.e. the process flow shown in fig. 1:
the flue gas of the alumina roasting furnace and the carbon content mother liquor are reversely sprayed, contacted and heat exchanged, because the water in the flue gas of the alumina roasting furnace is in an unsaturated state, part of the water in the carbon content mother liquor is evaporated into the flue gas in the spraying process, the temperature and the concentration of the carbon content mother liquor are increased, the particulate matters in the flue gas mainly comprise aluminum hydroxide or aluminum oxide, the aluminum hydroxide or the aluminum oxide enters the carbon content mother liquor, and caustic alkali in the carbon content mother liquor and CO in the flue gas2The reaction is carried out, and Al in the original carbon content mother liquor is separated2O3Further precipitation is carried out. The carbon content mother liquor which has absorbed the waste heat contains certain particulate matters Al (OH)3After the carbon content mother liquor passes through a filter press or a leaf filter device, solid-liquid separation is realized. Filtering and washing the filter cake to obtain fine aluminum hydroxide solid. The fine aluminum hydroxide solid can be sent to a carbon decomposition tank to be used as seeds; or the mixture is sent to be mixed with the sodium aluminate solution after carbonation decomposition, and then the aluminum hydroxide solid is obtained after filtration and washing. The filtrate obtained by solid-liquid separation of the carbon content mother liquor through a filter press or a leaf filter device is sent to an evaporation process, evaporated and then taken as evaporation mother liquor to be sent to a raw material process for batching.
SO in flue gas of aluminum oxide roasting furnace after heat exchange2The concentration is reduced to 30mg/m3The dust content was reduced to 10mg/Nm3And then, the flue gas of the aluminum oxide roasting furnace after heat exchange is subjected to demisting treatment and then is discharged.
Taking a certain alumina production enterprise as an example, the flue gas indexes of a 1500t/d type alumina roasting furnace are as follows: moisture content 37.17%, CO2Content 8.1%, SO2The content is 100mg/m3Dust content 100 mg-Nm3The temperature of the flue gas is 180 ℃, and the amount of the flue gas is 13.7 ten thousand Nm3/h。
The indexes of the carbon content mother liquor are as follows: nc content 103g/L, Nk content 9g/L, Al2O3The content is 6.8g/L, and the carbon content mother liquor flow is 100m3H, temperature 80 ℃.
By adopting the method of the embodiment, the flue gas of the alumina roasting furnace and the carbon content mother liquor are subjected to two-stage reverse spray contact heat exchange, the carbon content mother liquor is firstly subjected to one-time contact heat exchange with the fresh flue gas coming out of the alumina roasting furnace, then the carbon content mother liquor subjected to one-time contact heat exchange is introduced into the next-stage spray equipment, is subjected to contact heat exchange with the fresh flue gas coming out of the alumina roasting furnace again, and is further subjected to evaporation concentration on the carbon content mother liquor.
After two-stage reverse spray contact heat exchange, the flue gas index of the roasting furnace becomes: water vapor content 40%, CO2Content 7.74% SO2The content is less than or equal to 30mg/m3The dust content is less than or equal to 10mg/Nm3The flue gas temperature is 90 ℃, and the flue gas amount is changed into 14.37 ten thousand Nm3/h。
After heat exchange, about 5.2t/h of water in the carbonation mother liquor is evaporated and enters the flue gas, the concentration of total alkali (NC + Nk) is increased by 5.48 percent after evaporation, the NC content is 117g/L, the Nk content is 1g/L, and Al2O3The content was 1g/L and the temperature was 90 ℃. The carbon content mother liquor can obtain about 600kg of fine aluminum hydroxide solid after liquid-solid separation, the carbon content mother liquor after liquid-solid separation is sent to an evaporation process for re-evaporation, and then is used as the evaporation mother liquor for raw material blending.
Claims (8)
1. The carbon method aluminum oxide energy-saving emission-reducing production method is characterized by comprising the following steps: directly contacting the flue gas of the alumina roasting furnace with the carbon content mother liquor for heat exchange, raising the temperature of the carbon content mother liquor after heat exchange and improving the concentration of total alkali, and separating out aluminum hydroxide solid from the carbon content mother liquor after heat exchange;
carrying out solid-liquid separation on the carbon content mother liquor subjected to heat exchange to respectively obtain fine aluminum hydroxide solid and filtrate, and treating the filtrate to serve as evaporation mother liquor and sending the evaporation mother liquor to a raw material process for batching; sending the fine aluminum hydroxide solid to a carbon decomposition tank for use as seeds; or the fine aluminum hydroxide solid is sent to be mixed with the sodium aluminate solution after carbonation decomposition, and then the mixture is filtered and washed to obtain the aluminum hydroxide solid;
SO in flue gas of aluminum oxide roasting furnace after heat exchange2The concentration is reduced to 30mg/m3The dust content was reduced to 10mg/Nm3And then, the flue gas of the aluminum oxide roasting furnace after heat exchange is subjected to demisting and precipitation treatment and then is discharged.
2. The energy-saving and emission-reducing production method of alumina by the carbon fractionation method according to claim 1, wherein the flue gas of the alumina roaster is directly contacted with the carbon fractionation mother liquor for heat exchange by a reverse spraying method or a direct introduction method.
3. The energy-saving and emission-reducing production method of the aluminum oxide by the carbon separation method according to claim 2, wherein the flue gas of the aluminum oxide roasting furnace directly contacts with a carbon separation mother solution by a reverse spraying method for heat exchange, and the carbon separation mother solution contacts with the flue gas of the aluminum oxide roasting furnace at least once.
4. The carbon fractionation method alumina energy conservation and emission reduction production method according to any one of claims 1 to 3, wherein the alumina roasting furnace flue gas is any one of alumina gas suspension roasting furnace flue gas, alumina circulating fluidized roasting furnace flue gas and alumina fluidized flash roasting furnace flue gas.
5. The carbon fractionation method aluminum oxide energy-saving emission-reducing production method according to claim 4, wherein the flue gas indexes of the aluminum oxide roasting furnace are as follows: 36-40% of water vapor and CO26-10% of SO2The content of the active ingredient is 10-200 mg/m3The dust content is 5-100 mg/Nm3And the temperature of the flue gas is 130-200 ℃.
6. The carbon separation method aluminum oxide energy-saving emission-reduction production method according to claim 5, wherein the carbon content in the carbon separation mother liquor is 90-110 g/L, the Nk content is 8-15 g/L, and Al is2O3The content is 6-15 g/L.
7. The carbon fractionation method alumina energy conservation and emission reduction production method according to claim 6, wherein the heat-exchanged carbon fractionation mother liquor Al2O3The content is less than 5 g/L.
8. The carbon fractionation alumina energy-saving emission-reducing production method according to claim 1, wherein the filtrate is treated and then sent to a raw material process as an evaporation mother liquor for batching, and the treatment is evaporation treatment.
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| WO1985005349A1 (en) * | 1984-05-19 | 1985-12-05 | Showa Aluminum Industries, K. K. | Alumina for semiconductor memory cell package and process for its production |
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| CN105399118A (en) * | 2015-11-27 | 2016-03-16 | 中国铝业股份有限公司 | Production method for alumina through sintering method |
| CN105692658A (en) * | 2016-01-19 | 2016-06-22 | 中国铝业股份有限公司 | Method for recycling potassium carbonate from aluminum oxide production process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1985005349A1 (en) * | 1984-05-19 | 1985-12-05 | Showa Aluminum Industries, K. K. | Alumina for semiconductor memory cell package and process for its production |
| CN1594092A (en) * | 2004-06-25 | 2005-03-16 | 中国铝业股份有限公司 | Process for recovering aluminum hydroxide from carbon liquor by sintering method |
| CN1868881A (en) * | 2005-05-25 | 2006-11-29 | 贵阳铝镁设计研究院 | Technological process method of producing aluminium oxide using high aluminium slag |
| CN105399118A (en) * | 2015-11-27 | 2016-03-16 | 中国铝业股份有限公司 | Production method for alumina through sintering method |
| CN105692658A (en) * | 2016-01-19 | 2016-06-22 | 中国铝业股份有限公司 | Method for recycling potassium carbonate from aluminum oxide production process |
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