CN110194475B - High-low temperature roasting system and method for producing alumina from crystalline aluminum chloride - Google Patents
High-low temperature roasting system and method for producing alumina from crystalline aluminum chloride Download PDFInfo
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- CN110194475B CN110194475B CN201910549724.4A CN201910549724A CN110194475B CN 110194475 B CN110194475 B CN 110194475B CN 201910549724 A CN201910549724 A CN 201910549724A CN 110194475 B CN110194475 B CN 110194475B
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- 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 76
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 title claims abstract description 74
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 6
- 238000000034 method Methods 0.000 claims abstract description 18
- 239000010881 fly ash Substances 0.000 claims abstract description 9
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 63
- 239000003546 flue gas Substances 0.000 claims description 63
- 238000001816 cooling Methods 0.000 claims description 34
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 239000002994 raw material Substances 0.000 claims description 15
- MXRIRQGCELJRSN-UHFFFAOYSA-N O.O.O.[Al] Chemical compound O.O.O.[Al] MXRIRQGCELJRSN-UHFFFAOYSA-N 0.000 claims description 14
- 239000002737 fuel gas Substances 0.000 claims description 13
- 239000007787 solid Substances 0.000 claims description 13
- 230000009471 action Effects 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 10
- 239000000498 cooling water Substances 0.000 claims description 7
- 238000000354 decomposition reaction Methods 0.000 claims description 7
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 7
- 238000007599 discharging Methods 0.000 claims description 6
- 239000002910 solid waste Substances 0.000 claims description 6
- 238000002485 combustion reaction Methods 0.000 claims description 5
- 239000007790 solid phase Substances 0.000 claims description 5
- 230000008569 process Effects 0.000 abstract description 10
- 238000000605 extraction Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 3
- 238000004064 recycling Methods 0.000 abstract description 2
- 229940063656 aluminum chloride Drugs 0.000 description 25
- 239000002245 particle Substances 0.000 description 15
- 239000007789 gas Substances 0.000 description 7
- JGDITNMASUZKPW-UHFFFAOYSA-K aluminium trichloride hexahydrate Chemical compound O.O.O.O.O.O.Cl[Al](Cl)Cl JGDITNMASUZKPW-UHFFFAOYSA-K 0.000 description 5
- 239000002918 waste heat Substances 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229940009861 aluminum chloride hexahydrate Drugs 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 238000001354 calcination Methods 0.000 description 2
- 238000005243 fluidization Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000010883 coal ash Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 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
- C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
- C01F7/306—Thermal decomposition of hydrated chlorides, e.g. of aluminium trichloride hexahydrate
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Fluidized-Bed Combustion And Resonant Combustion (AREA)
- Chimneys And Flues (AREA)
- Crucibles And Fluidized-Bed Furnaces (AREA)
Abstract
The invention relates to a high-low temperature roasting system and a method for producing alumina by crystallizing aluminum chloride, which belong to the technical field of recycling fly ash resources. The method provides important guarantee for the productivity of industrial grade alumina in China, and adopts a process route for producing alumina by roasting crystalline aluminum chloride at high and low temperatures, and the process route has the advantages of high extraction rate, high product yield, low system energy consumption, high product quality and the like.
Description
Technical Field
The invention relates to a high-low temperature roasting system and a method for producing alumina by crystallizing aluminum chloride, which belong to the technical field of recycling fly ash resources.
Background
Alumina is an important raw material for the industries of electrolytic aluminum, ceramics, fire resistance, heat preservation, medicine, electronics, machinery and the like. At present, the domestic alumina productivity is seriously insufficient, and a large amount of alumina is required to be imported from abroad every year, so that the development of the domestic alumina industry is directly influenced.
Disclosure of Invention
The technical solution of the invention is as follows: a high-low temperature roasting system and method for producing alumina from crystalline aluminium chloride is provided.
The technical scheme of the invention is as follows:
A high-low temperature roasting system for producing alumina by crystallizing aluminum chloride comprises a dryer, a low-temperature circulating fluidized bed, a high-temperature circulating fluidized bed, a first cyclone separator, a second cyclone separator and a cooling bed;
the dryer has a top end outlet, a side inlet and a bottom end inlet;
The low-temperature circulating fluidized bed is provided with a side inlet, a bottom outlet and a top outlet;
the high-temperature circulating fluidized bed is provided with a side inlet, a bottom outlet and a top outlet;
The first cyclone separator is provided with a top end outlet, a bottom end outlet and a side surface inlet;
The second cyclone separator is provided with a top end outlet, a bottom end outlet and a side surface inlet;
the cooling bed is cooled by cooling air and circulating cooling water;
The second cyclone separator is cooled by cold air;
the fuel gas and the air are combusted by a burner at the bottom end of the low-temperature circulating fluidized bed to form high-temperature flue gas to provide heat for the low-temperature circulating fluidized bed;
The fuel gas and the air are combusted by a burner at the bottom end of the high-temperature circulating fluidized bed to form high-temperature flue gas to provide heat for the high-temperature circulating fluidized bed;
The top outlet of the dryer is connected with the side inlet of the first cyclone separator through a pipeline;
the top outlet of the low-temperature circulating fluidized bed is connected with the bottom inlet of the dryer through a pipeline;
the bottom outlet of the first cyclone separator is connected with the side inlet of the low-temperature circulating fluidized bed through a belt;
the bottom outlet of the low-temperature circulating fluidized bed is connected with the side inlet of the high-temperature circulating fluidized bed through a pipeline;
the top outlet of the high-temperature circulating fluidized bed is connected with the side inlet of the low-temperature circulating fluidized bed through a pipeline;
the bottom outlet of the high-temperature circulating fluidized bed is connected with the side inlet of the second cyclone separator through a pipeline;
The top outlet of the second cyclone separator is connected with the side inlet of the high-temperature circulating fluidized bed through a pipeline;
The bottom outlet of the second cyclone separator is connected with the cooling bed through a pipeline.
A high and low temperature calcination process for producing alumina from crystalline aluminum chloride, the process comprising the steps of:
(1) The raw material of the crystalline aluminum chloride is divided into two paths, wherein one path enters a low-temperature circulating fluidized bed, and the other path enters a dryer. Simultaneously, the fuel gas and the combustion-supporting air generate high-temperature flue gas in the low-temperature circulating fluidized bed, and under the action of the high-temperature flue gas, the crystalline aluminum chloride entering the low-temperature circulating fluidized bed is subjected to decomposition reaction to generate amorphous aluminum oxide;
(2) The amorphous alumina generated by entrainment of high-temperature flue gas in the low-temperature circulating fluidized bed is separated under the action of a cyclone separator in the low-temperature circulating fluidized bed, the high-temperature flue gas is discharged from the top outlet of the low-temperature circulating fluidized bed and enters the dryer, and the amorphous alumina is discharged from the bottom outlet of the low-temperature circulating fluidized bed and enters the high-temperature circulating fluidized bed. Simultaneously, fuel gas and combustion-supporting air generate high-temperature flue gas in a high-temperature circulating fluidized bed, and amorphous alumina is subjected to lattice transformation under the action of the high-temperature flue gas in the high-temperature circulating fluidized bed to generate industrial alumina;
the high-temperature flue gas entering the dryer is fully mixed with the crystalline aluminum chloride entering the dryer, exchanges heat and carries out chemical reaction, and the waste heat of the high-temperature flue gas is fully utilized. The reacted flue gas entraining solid phase is discharged from the top outlet of the dryer and enters the first cyclone separator for gas-solid separation;
(3) The high-temperature flue gas in the high-temperature circulating fluidized bed is entrained with industrial alumina to be separated under the action of a cyclone separator of the high-temperature circulating fluidized bed, and the industrial alumina with a set amount of high-temperature flue gas is discharged from a top outlet of the high-temperature circulating fluidized bed and enters the low-temperature circulating fluidized bed. The rest industrial alumina is separated by the cyclone separator, one part of the industrial alumina returns to the high-temperature circulating fluidized bed for circulation, and the other part of the industrial alumina is discharged by the discharge valve and enters the second cyclone separator;
(4) After the industrial alumina entering the second cyclone separator is cooled and separated in the second cyclone separator, the separated high-temperature air is discharged through the top outlet of the second cyclone separator and enters the high-temperature circulating fluidized bed for supporting combustion, and the separated industrial alumina is discharged through the bottom outlet of the second cyclone separator and enters the cooling bed;
(5) And cooling the industrial alumina entering the cooling bed by cooling air and circulating cooling water, and discharging to obtain the product alumina.
The raw material crystalline aluminum chloride is obtained by extracting solid waste fly ash, and the extraction method is an acid method or an alkali method;
The separation efficiency of the cyclone separator in the high-temperature circulating fluidized bed is 50% -80%;
The separation efficiency of the cyclone separator in the low-temperature circulating fluidized bed is 95% -98%;
In the step (3), the set quantity of the industrial alumina with the set quantity of the high-temperature flue gas is determined according to the separation efficiency of a cyclone separator in the high-temperature circulating fluidized bed;
the flow ratio of one path of the raw material crystalline aluminum chloride entering the low-temperature circulating fluidized bed to one path of the raw material crystalline aluminum chloride entering the dryer is 3-6:1, a step of;
the temperature of the high-temperature flue gas entering the low-temperature circulating fluidized bed is 850-950 ℃;
The temperature of the high-temperature flue gas at the outlet of the high-temperature circulating fluidized bed is 950-1050 ℃;
The outlet pipeline at the bottom end of the low-temperature circulating fluidized bed is provided with a feed back valve, and the ratio of the quantity of the alumina which returns to the low-temperature circulating fluidized bed to participate in circulation to the flow of the alumina which enters the high-temperature circulating fluidized bed can be controlled through the feed back valve.
The outlet pipeline at the bottom end of the high-temperature circulating fluidized bed is provided with a feed back valve, and the proportion of the alumina quantity returned to the high-temperature circulating fluidized bed to participate in circulation to the alumina flow entering the second cyclone separator can be controlled through the feed back valve.
Advantageous effects
(1) The raw material crystalline aluminum chloride is obtained by extracting solid waste fly ash, and the solid waste is fully utilized;
(2) The method provides important guarantee for the productivity of industrial grade alumina in China, adopts a process route for producing alumina by roasting crystalline aluminum chloride at high and low temperatures, and has the advantages of high extraction rate, high product yield, low system energy consumption, high product quality and the like;
(3) In the method, raw material crystalline aluminum chloride is fed in two ways, one of the raw material crystalline aluminum chloride is directly fed into a low-temperature circulating fluidized bed, the low-temperature circulating fluidized bed adopts a low-circulation-rate circulating fluidized bed mode, high-temperature flue gas generated by fuel gas combustion is fed into the low-temperature circulating fluidized bed as primary air (fluidizing air), and the high-temperature flue gas is directly contacted with the crystalline aluminum chloride in the bed to generate chemical reaction, so that amorphous aluminum oxide is generated. The alumina carried by high-temperature flue gas generated after the reaction enters a cyclone separator of a low-temperature circulating fluidized bed, wherein solid phase enters a feed back valve through the separator, a part of materials in the feed back valve are returned to the low-temperature circulating fluidized bed for material circulation, and a part of materials enter the high-temperature circulating fluidized bed through a regulating valve on the feed back valve for high-temperature roasting. And (3) feeding the discharged high-temperature flue gas of the low-temperature circulating fluidized bed into a dryer to be fully mixed with another strand of crystalline aluminum chloride, exchanging heat and carrying out chemical reaction, and carrying out waste heat utilization on the high-temperature flue gas. Solid particles generated in the dryer enter a low-temperature circulating fluidized bed through a cyclone separator, gas phase high-temperature flue gas containing HCL gas is reacted with aluminum chloride hexahydrate and then cooled to a certain temperature, and the gas phase high-temperature flue gas enters a subsequent system after being dedusted through the separator.
Amorphous alumina from the low-temperature circulating fluidized bed directly enters the high-temperature circulating fluidized bed to carry out lattice transformation under the action of gravity to generate industrial grade alumina. The high-temperature circulating fluidized bed adopts a circulating fluidized bed structure with higher circulation rate, primary air of the high-temperature circulating fluidized bed and the cooling bed indirectly exchange heat and then enter the lower part of the high-temperature circulating fluidized bed to fluidize particles in the high-temperature circulating fluidized bed, and meanwhile, the primary air is combustion-supporting air. And after the secondary air is subjected to fluidization heat exchange with the cooling bed, the secondary air enters a cyclone separator to exchange heat with high-temperature alumina generated by the high-temperature circulating fluidized bed. The solid particles separated by the cyclone separator enter a cooling bed to further reduce the temperature, and the secondary air enters a high-temperature circulating fluidized bed to be used as combustion-supporting air. In order to recycle the waste heat of the high-temperature flue gas of the high-temperature circulating fluidized bed, part of solid particles carried by the high-temperature flue gas are returned to the low-temperature circulating fluidized bed to be used as secondary air, and a heat source is supplemented for the low-temperature circulating fluidized bed. The solid granular alumina exchanges heat with primary air, secondary air and cooling water in the cooling bed and is discharged to a finished alumina storage bin.
(4) The method adopts a high-low two-stage temperature roasting mode, low temperature Duan Tuoshui and degassing are adopted, and lattice conversion is carried out at a high temperature stage, so that industrial alumina can be produced; part of solid particles are entrained in high-temperature flue gas generated by the high-temperature circulating fluidized bed, and the low-temperature circulating fluidized bed heat source is supplemented by returning the low-temperature circulating fluidized bed, so that the high-temperature flue gas waste heat generated by the high-temperature circulating fluidized bed is effectively utilized; the energy is utilized in a cascade way by adopting a sectional feeding mode, so that the agglomeration risk caused by the fact that all materials enter one device is reduced, and the energy utilization rate is greatly improved; the high-temperature flue gas is effectively utilized through the dryer, so that the temperature of the flue gas is greatly reduced, the energy consumption of the system is reduced, and the economic performance is obviously improved.
Mine areas such as quaigler and the like are rich in coal resources and have a large amount of coal geological reserves. The coal is accompanied with rich nonferrous metals such as aluminum, gallium and the like, and after the coal is combusted by a boiler of a power plant, the obtained fly ash is enriched with a large amount of aluminum oxide, and the content is usually more than 50 percent, so that the coal ash is a potential resource for extracting the aluminum oxide. The fly ash is generally used as solid waste to be directly abandoned, so that the resource waste is caused, and in order to change waste into valuable, the pollution to the environment is reduced, and the alumina in the fly ash can be extracted and recycled.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
The total equation for the decomposition reaction of crystalline aluminum chloride is:
2AlCl 3.6H2O→Al2O3+9H2 O ++6 HCl +.. The decomposition reaction requires the absorption of a large amount of heat, most of the products are gases, and the harmful gas HCL is evolved. In the technical scheme, the decomposition reaction is mainly carried out in a low-temperature circulating fluidized bed and a dryer, and the lattice conversion reaction is carried out in a high-temperature circulating fluidized bed.
Aluminum chloride hexahydrate from the feeder is fed in two parts according to a certain proportion: one strand directly enters a low-temperature circulating fluidized bed roasting furnace to be in direct contact with high-temperature flue gas at 950 ℃, and after staying in the high-temperature circulating fluidized bed for a certain time, chemical reaction is carried out to generate amorphous alumina. The high-temperature flue gas at the temperature of about 350 ℃ generated after the reaction carries alumina into a cyclone separator of a low-temperature circulating fluidized bed, amorphous alumina particles enter the high-temperature circulating fluidized bed through the cyclone separator, and gas-phase high-temperature flue gas enters a dryer.
The other strand of hexahydrate aluminum chloride is fully mixed with high-temperature smoke gas at 350 ℃ generated by a high-temperature circulating fluidized bed through a dryer, exchanges heat and undergoes decomposition reaction to generate amorphous aluminum oxide. After the solid particles are carried by the flue gas at about 220 ℃ after the reaction in the dryer and pass through the cyclone separator, the solid phase enters a low-temperature circulating fluidized bed, and the high-temperature flue gas containing HCL gas enters the cyclone and is introduced into a post-system.
Amorphous alumina from the low-temperature circulating fluidized bed enters the high-temperature circulating fluidized bed to carry out lattice conversion reaction, and the reaction temperature is not lower than 950 ℃. The high-temperature roasting furnace also adopts a circulating fluidized bed technology, the working temperature of the roasting furnace is not lower than 950 ℃, and the quality of the alumina is controlled by controlling the circulation rate of the alumina in the furnace. And carrying out high-temperature flue gas at 950 ℃ generated by the high-temperature circulating fluidized bed reaction to enter a low-temperature circulating fluidized bed with part of solid particles, and supplementing heat as secondary air of the low-temperature circulating fluidized bed. And (3) returning a part of the solid particles separated by the high-temperature circulating fluidized bed into the furnace, and conveying a part of the solid particles to a cooling bed for cooling. The tapping granule temperature was 950 ℃.
The heat exchange medium in the heat exchange tube is primary air of the high-temperature roasting furnace, and the primary air temperature is 300 ℃. The particle fluidization air in the cooling bed is the secondary air of the high-temperature circulating fluidized bed, and the secondary air enters the cyclone cooler after passing through the cooling bed to cool the high-temperature particles entering the cyclone, and the high-temperature air temperature at the cyclone outlet is 500 ℃. The primary air and the secondary air of the high-temperature circulating fluidized bed fully absorb the heat of the solid alumina particles, and the heat efficiency is improved. In order to reduce the temperature of the alumina particles to below 65 ℃, a water cooling pipe is arranged at the tail end of the cooling bed, and the particles are reduced to below 65 ℃ by a water cooling mode.
The technical grade alumina can be obtained by the technical proposal and can be used as a basic raw material of electrolytic aluminum. The technological scheme has simple control, less equipment, high heat efficiency, complete decomposing reaction and high product quality. The invention discloses a process scheme for producing industrial grade alumina by multistage roasting of aluminum chloride hexahydrate, and a fluidized roasting aluminum chloride hexahydrate process system is analyzed, developed and researched, and the process scheme has important significance for the development of the aluminum industry in China.
Examples
As shown in fig. 1, a high-low temperature roasting system for producing alumina from crystalline aluminum chloride comprises a dryer, a low-temperature circulating fluidized bed, a high-temperature circulating fluidized bed, a first cyclone separator, a second cyclone separator and a cooling bed;
the dryer has a top end outlet, a side inlet and a bottom end inlet;
The low-temperature circulating fluidized bed is provided with a side inlet, a bottom outlet and a top outlet;
the high-temperature circulating fluidized bed is provided with a side inlet, a bottom outlet and a top outlet;
The first cyclone separator is provided with a top end outlet, a bottom end outlet and a side surface inlet;
The second cyclone separator is provided with a top end outlet, a bottom end outlet and a side surface inlet;
the cooling bed is cooled by cooling air and circulating cooling water;
The second cyclone separator is cooled by cold air;
the fuel gas and the air are combusted by a burner at the bottom end of the low-temperature circulating fluidized bed to form high-temperature flue gas to provide heat for the low-temperature circulating fluidized bed;
The fuel gas and the air are combusted by a burner at the bottom end of the high-temperature circulating fluidized bed to form high-temperature flue gas to provide heat for the high-temperature circulating fluidized bed;
The top outlet of the dryer is connected with the side inlet of the first cyclone separator through a pipeline;
the top outlet of the low-temperature circulating fluidized bed is connected with the bottom inlet of the dryer through a pipeline;
the bottom outlet of the first cyclone separator is connected with the side inlet of the low-temperature circulating fluidized bed through a belt;
the bottom outlet of the low-temperature circulating fluidized bed is connected with the side inlet of the high-temperature circulating fluidized bed through a pipeline;
the top outlet of the high-temperature circulating fluidized bed is connected with the side inlet of the low-temperature circulating fluidized bed through a pipeline;
the bottom outlet of the high-temperature circulating fluidized bed is connected with the side inlet of the second cyclone separator through a pipeline;
The top outlet of the second cyclone separator is connected with the side inlet of the high-temperature circulating fluidized bed through a pipeline;
The bottom outlet of the second cyclone separator is connected with the cooling bed through a pipeline.
A high and low temperature calcination process for producing alumina from crystalline aluminum chloride, the process comprising the steps of:
(1) The raw material of the crystalline aluminum chloride is divided into two paths, wherein one path of aluminum chloride enters a low-temperature circulating fluidized bed, and the other path of aluminum chloride enters a dryer. Simultaneously, the fuel gas and the combustion air burn in 950 ℃ high-temperature flue gas generated in the low-temperature circulating fluidized bed. Under the action of high-temperature flue gas, the crystallization aluminum chloride entering the low-temperature circulating fluidized bed is subjected to decomposition reaction to generate amorphous aluminum oxide at 350 ℃;
(2) The amorphous alumina generated by entrainment of high-temperature flue gas at 350 ℃ in the low-temperature circulating fluidized bed is separated under the action of a cyclone separator in the low-temperature circulating fluidized bed, the high-temperature flue gas is discharged from a top outlet of the low-temperature circulating fluidized bed and enters a dryer, and the amorphous alumina is discharged from a bottom outlet of the low-temperature circulating fluidized bed and enters the high-temperature circulating fluidized bed. Simultaneously, fuel gas and combustion-supporting air generate high-temperature flue gas at 950 ℃ in a high-temperature circulating fluidized bed, and amorphous alumina is subjected to lattice transformation under the action of the high-temperature flue gas of the high-temperature circulating fluidized bed to generate industrial alumina;
the high-temperature flue gas entering the dryer at 350 ℃ is fully mixed with aluminum chloride with the flow rate of 13250kg/h entering the dryer, heat exchange and chemical reaction are carried out, and the waste heat of the high-temperature flue gas is fully utilized. The solid phase carried by the flue gas at 220 ℃ after the reaction is discharged from the top outlet of the dryer and enters the first cyclone separator for gas-solid separation;
(3) The high-temperature flue gas with 950 ℃ in the high-temperature circulating fluidized bed carries industrial alumina to be separated under the action of a cyclone separator of the high-temperature circulating fluidized bed, and the industrial alumina with a certain flow rate carried by the high-temperature flue gas is discharged from an outlet at the top end of the high-temperature circulating fluidized bed and enters the low-temperature circulating fluidized bed. The rest industrial alumina is separated by the cyclone separator, one part of the alumina returns to the high-temperature circulating fluidized bed for circulation, and the other part of the alumina is discharged by the discharge valve and enters the second cyclone separator;
(4) The 950 ℃ industrial grade alumina entering the second cyclone separator is cooled to 650 ℃ in the second cyclone separator and separated, the separated 500 ℃ high-temperature air is discharged through the top outlet of the second cyclone separator and enters the high-temperature circulating fluidized bed for supporting combustion, and the separated product alumina is discharged through the bottom outlet of the second cyclone separator and enters the cooling bed;
(5) And cooling the industrial grade alumina entering the cooling bed to 65 ℃ by cooling air and circulating cooling water, and discharging to obtain the product alumina.
The raw material crystalline aluminum chloride is obtained by extracting solid waste fly ash, and the extraction method is an alkaline method;
The separation efficiency of the cyclone separator in the low-temperature circulating fluidized bed is 95% -98%;
The bottom outlet pipeline of the low-temperature circulating fluidized bed is provided with a feed back valve, and amorphous alumina discharged from the bottom outlet of the low-temperature circulating fluidized bed can be controlled to enter the high-temperature circulating fluidized bed through the feed back valve;
The bottom outlet pipeline of the high-temperature circulating fluidized bed is provided with a feed back valve, and industrial alumina discharged from the bottom outlet of the high-temperature circulating fluidized bed can be controlled to enter the industrial alumina in the second cyclone separator through the feed back valve.
Claims (1)
1. A high-low temperature roasting system for producing alumina by crystallizing aluminum chloride is characterized in that: the system comprises a dryer, a low-temperature circulating fluidized bed, a high-temperature circulating fluidized bed, a first cyclone separator, a second cyclone separator and a cooling bed;
the dryer has a top end outlet, a side inlet and a bottom end inlet;
The low-temperature circulating fluidized bed is provided with a side inlet, a bottom outlet and a top outlet;
the high-temperature circulating fluidized bed is provided with a side inlet, a bottom outlet and a top outlet;
The first cyclone separator is provided with a top end outlet, a bottom end outlet and a side surface inlet;
The second cyclone separator is provided with a top end outlet, a bottom end outlet and a side surface inlet;
the cooling bed is cooled by cooling air and circulating cooling water;
The second cyclone separator is cooled by cold air;
the fuel gas and the air are combusted by a burner at the bottom end of the low-temperature circulating fluidized bed to form high-temperature flue gas to provide heat for the low-temperature circulating fluidized bed;
The fuel gas and the air are combusted by a burner at the bottom end of the high-temperature circulating fluidized bed to form high-temperature flue gas to provide heat for the high-temperature circulating fluidized bed;
The top outlet of the dryer is connected with the side inlet of the first cyclone separator through a pipeline;
the top outlet of the low-temperature circulating fluidized bed is connected with the bottom inlet of the dryer through a pipeline;
the bottom outlet of the first cyclone separator is connected with the side inlet of the low-temperature circulating fluidized bed through a belt;
the bottom outlet of the low-temperature circulating fluidized bed is connected with the side inlet of the high-temperature circulating fluidized bed through a pipeline;
the top outlet of the high-temperature circulating fluidized bed is connected with the side inlet of the low-temperature circulating fluidized bed through a pipeline;
the bottom outlet of the high-temperature circulating fluidized bed is connected with the side inlet of the second cyclone separator through a pipeline;
The top outlet of the second cyclone separator is connected with the side inlet of the high-temperature circulating fluidized bed through a pipeline;
The bottom outlet of the second cyclone separator is connected with the cooling bed through a pipeline;
the high-low temperature roasting method for producing alumina by crystallizing aluminum chloride by a high-low temperature roasting system comprises the following steps:
(1) The method comprises the steps that raw material crystalline aluminum chloride is divided into two paths, wherein one path enters a low-temperature circulating fluidized bed, the other path enters a dryer, and the crystalline aluminum chloride entering the low-temperature circulating fluidized bed and high-temperature flue gas undergo decomposition reaction to generate amorphous aluminum oxide;
(2) Separating the amorphous alumina generated by entrainment of high-temperature flue gas in the low-temperature circulating fluidized bed under the action of a cyclone separator in the low-temperature circulating fluidized bed, discharging the high-temperature flue gas from a top outlet of the low-temperature circulating fluidized bed, and entering a dryer, discharging the amorphous alumina from a bottom outlet of the low-temperature circulating fluidized bed, and entering a high-temperature circulating fluidized bed with the high-temperature flue gas, wherein the amorphous alumina undergoes lattice conversion in the high-temperature circulating fluidized bed to generate industrial alumina;
the high-temperature flue gas entering the dryer is fully mixed with the crystalline aluminum chloride entering the dryer, heat exchange and chemical reaction are carried out, and the reacted flue gas entrains solid phase to be discharged from an outlet at the top end of the dryer and enters the first cyclone separator for gas-solid separation;
(3) Separating industrial grade alumina carried by high-temperature flue gas in the high-temperature circulating fluidized bed under the action of a cyclone separator of the high-temperature circulating fluidized bed, discharging a set amount of industrial grade alumina carried by the high-temperature flue gas from a top outlet of the high-temperature circulating fluidized bed and entering the low-temperature circulating fluidized bed, separating the residual industrial grade alumina by the cyclone separator, returning a part of the separated industrial grade alumina to the high-temperature circulating fluidized bed for circulation, and discharging the other part of the industrial grade alumina to a second cyclone separator by a discharge valve;
(4) After the industrial alumina entering the second cyclone separator is cooled and separated in the second cyclone separator, the separated high-temperature air is discharged through the top outlet of the second cyclone separator and enters the high-temperature circulating fluidized bed for supporting combustion, and the separated industrial alumina is discharged through the bottom outlet of the second cyclone separator and enters the cooling bed;
(5) The industrial alumina entering the cooling bed is cooled by cooling air and circulating cooling water and then discharged, so that the product alumina is obtained;
the raw material crystalline aluminum chloride is obtained by extracting solid waste fly ash;
the separation efficiency of the cyclone separator in the high-temperature circulating fluidized bed is 50% -80%;
the separation efficiency of the cyclone separator in the low-temperature circulating fluidized bed is 95% -98%;
In the step (3), the set quantity of the industrial alumina with the set quantity of the high-temperature flue gas is determined according to the separation efficiency of a cyclone separator in the high-temperature circulating fluidized bed;
the flow ratio of one path of the raw material crystalline aluminum chloride entering the low-temperature circulating fluidized bed to one path of the raw material crystalline aluminum chloride entering the dryer is 3-6:1, a step of;
the temperature of the high-temperature flue gas entering the low-temperature circulating fluidized bed is 850-950 ℃;
The temperature of the high-temperature flue gas at the outlet of the high-temperature circulating fluidized bed is 950-1050 ℃;
the bottom outlet pipeline of the low-temperature circulating fluidized bed is provided with a feed back valve, and the ratio of the amount of alumina returned to the low-temperature circulating fluidized bed to participate in circulation to the flow of alumina entering the high-temperature circulating fluidized bed is controlled by the feed back valve;
A return valve is arranged on an outlet pipeline at the bottom end of the high-temperature circulating fluidized bed, and the ratio of the quantity of alumina returned to the high-temperature circulating fluidized bed to participate in circulation to the flow of alumina entering the second cyclone separator is controlled through the return valve;
In the step (1), high-temperature flue gas is generated by fuel gas and combustion-supporting air in a low-temperature circulating fluidized bed;
In the step (2), high-temperature flue gas is generated by fuel gas and combustion-supporting air in a high-temperature circulating fluidized bed.
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| CN102502744A (en) * | 2011-10-26 | 2012-06-20 | 北京航天动力研究所 | Slagging-free type and multilevel differential temperature fluidized roasting system for crystallized aluminum salt and method thereof |
| CN203529952U (en) * | 2013-07-04 | 2014-04-09 | 中国神华能源股份有限公司 | Aluminum chloride crystal roasting system |
| CN208856919U (en) * | 2018-07-06 | 2019-05-14 | 北京航天石化技术装备工程有限公司 | A kind of crystallization aluminium salt roasting prepares the integrating device of technical grade aluminium oxide |
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| CN102502744A (en) * | 2011-10-26 | 2012-06-20 | 北京航天动力研究所 | Slagging-free type and multilevel differential temperature fluidized roasting system for crystallized aluminum salt and method thereof |
| CN203529952U (en) * | 2013-07-04 | 2014-04-09 | 中国神华能源股份有限公司 | Aluminum chloride crystal roasting system |
| CN208856919U (en) * | 2018-07-06 | 2019-05-14 | 北京航天石化技术装备工程有限公司 | A kind of crystallization aluminium salt roasting prepares the integrating device of technical grade aluminium oxide |
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