CN111943244A - Method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder - Google Patents
Method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder Download PDFInfo
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- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 62
- 239000010703 silicon Substances 0.000 title claims abstract description 62
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 title claims abstract description 56
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 239000010436 fluorite Substances 0.000 title claims abstract description 53
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 title claims abstract description 47
- 239000000843 powder Substances 0.000 title claims abstract description 42
- 238000001035 drying Methods 0.000 title claims abstract description 36
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 30
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 89
- 239000007789 gas Substances 0.000 claims abstract description 79
- 238000006243 chemical reaction Methods 0.000 claims abstract description 63
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 62
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims abstract description 62
- 239000002253 acid Substances 0.000 claims abstract description 48
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 40
- 238000000746 purification Methods 0.000 claims abstract description 33
- 238000005406 washing Methods 0.000 claims abstract description 33
- 238000010438 heat treatment Methods 0.000 claims abstract description 25
- 239000003595 mist Substances 0.000 claims abstract description 12
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims abstract description 9
- 238000001816 cooling Methods 0.000 claims abstract description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- 239000000377 silicon dioxide Substances 0.000 claims description 16
- PVNIIMVLHYAWGP-UHFFFAOYSA-N Niacin Chemical compound OC(=O)C1=CC=CN=C1 PVNIIMVLHYAWGP-UHFFFAOYSA-N 0.000 claims description 12
- 229910052681 coesite Inorganic materials 0.000 claims description 11
- 229910052906 cristobalite Inorganic materials 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 11
- 229910052682 stishovite Inorganic materials 0.000 claims description 11
- 229910052905 tridymite Inorganic materials 0.000 claims description 11
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical group [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 9
- 238000005554 pickling Methods 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 238000003786 synthesis reaction Methods 0.000 claims description 7
- 229960003512 nicotinic acid Drugs 0.000 claims description 6
- 235000001968 nicotinic acid Nutrition 0.000 claims description 6
- 239000011664 nicotinic acid Substances 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 abstract description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 14
- 229910004014 SiF4 Inorganic materials 0.000 description 13
- 239000012535 impurity Substances 0.000 description 10
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 description 9
- 239000002994 raw material Substances 0.000 description 7
- 229910003638 H2SiF6 Inorganic materials 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 239000000428 dust Substances 0.000 description 5
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 5
- ZEFWRWWINDLIIV-UHFFFAOYSA-N tetrafluorosilane;dihydrofluoride Chemical compound F.F.F[Si](F)(F)F ZEFWRWWINDLIIV-UHFFFAOYSA-N 0.000 description 5
- 239000002699 waste material Substances 0.000 description 5
- 229910004074 SiF6 Inorganic materials 0.000 description 4
- 229910020439 SiO2+4HF Inorganic materials 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- HIFJUMGIHIZEPX-UHFFFAOYSA-N sulfuric acid;sulfur trioxide Chemical compound O=S(=O)=O.OS(O)(=O)=O HIFJUMGIHIZEPX-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 229910052593 corundum Inorganic materials 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- 239000010865 sewage Substances 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910000329 aluminium sulfate Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 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 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 229910021502 aluminium hydroxide Inorganic materials 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 229910052925 anhydrite Inorganic materials 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000003682 fluorination reaction Methods 0.000 description 1
- 229910001679 gibbsite Inorganic materials 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 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
- C01F7/48—Halides, with or without other cations besides aluminium
- C01F7/50—Fluorides
-
- 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
Abstract
The invention relates to the technical field of aluminum fluoride production, in particular to a method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder comprises the following steps: reacting the mixed sulfuric acid and the high-silicon fluorite powder in an external heating type rotary reaction furnace to obtain crude hydrogen fluoride gas; introducing the crude hydrogen fluoride gas into a pre-purification tower, fully contacting with pre-purification acid flowing reversely for pre-purification, cooling to 40-60 ℃, sequentially introducing into a water washing tower and an acid washing tower, and finally separating acid mist by a demister to obtain purified hydrogen fluoride gas; introducing the purified hydrogen fluoride gas into a fluidized bed reactor, and reacting with aluminum hydroxide to obtain the dry-process aluminum fluoride. When the fluorite powder with high silicon content is adopted to produce the aluminum fluoride, the utilization rate of the hydrogen fluoride gas is improved, the production cost is greatly reduced, the quality of the aluminum fluoride product is ensured, and the normal use of the electrolytic aluminum production can be met.
Description
Technical Field
The invention relates to the technical field of aluminum fluoride production, in particular to a method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder.
Background
The dry-method aluminum fluoride production mainly comprises two parts of hydrogen fluoride preparation and aluminum fluoride synthesis. When the fluorite is used for preparing the hydrogen fluoride, the impurity silicon content in the fluorite is higher, so that the silicon content of the hydrogen fluoride is higher, and the ductility and the flexibility of an aluminum fluoride product are influenced. Therefore, on one hand, the impurity silicon content in fluorite needs to be strictly controlled; on the other hand, the hydrogen fluoride needs to be desiliconized and purified.
The prior hydrogen fluoride desiliconization methods comprise a fluidized bed desiliconization method and a gas guide tube desiliconization method.
The principle of the fluidized bed desilication method is as follows: SiF4+2H2O←→SiO2+4 HF. Wherein, the acid adding in the elevated tank can accelerate the specific gravity rise of the pre-purified acid, and the adjustment of the proportion of the nicotinic acid and the sulfuric acid is added to further accelerate the specific gravity rise of the pre-purified acid to achieve the SO in the nicotinic acid before the gas reaches the fluidized bed3 2-Is not covered by H2The purpose of O absorption. SO (SO)3 2-SO after entering fluidized bed3 2-+H2O→H2SO4Absorbing water in the fluidized bed to obtain SiO2+4HF←→SiF4+2H2O fluidized bed SiO2Conversion to SiF4Thereby achieving the purpose of removing Si.
However, the fluidized bed desilication method has the following drawbacks:
(1) the fluidized bed desiliconization method must use a large amount of nicotinic acid to generate free SO to achieve the ideal desiliconization effect3 2-A great deal of waste of nicotinic acid can be caused;
(2) sulfuric acid reacts with alumina, 3H2SO4+Al2O3→Al2(SO4)3+3H2O, Al formed2(SO4)3Not only can lead to SO in the finished product sample4 2-Excessive standard, no temperature rise of the fluidized bed, Al2(SO4)3Too high a level may also lead to dead beds in the fluidized bed, resulting in SO in the finished sample4 2-The product is unqualified due to overhigh temperature;
(3) reaction of silicon dioxide with Hydrogen fluoride gas, SiO2+4HF←→SiF4+2H2O, conversion of large amounts of HF gas to SiF4Enters tail gas absorption to cause a large amount of HF gas waste, and CaF in fluorite2The content is high, and the total yield is not increased;
(4) when SiF4After entering an atmospheric condensing tower, the reaction product reacts with water to obtain SiF4+2H2O←→SiO2+4HF, resulting in F in atmospheric condensation columns-Greatly improves the quality, needs a large amount of lime for neutralization, generates a large amount of sewage and increases the sewage treatment cost.
The principle of the desiliconization method of the air duct is as follows: si and SiO in a reaction furnace2Generated SiF4In case of excess HF, SiF4+2HF→H2SiF6. When reactant gas passes through the gas guide tube and is sprayed by mixed acid from the mixed acid kettle, fluosilicic acid is generated. When the temperature of the gas-guide tube is lower than 108.5 ℃, a large amount of H exists2SiF6Is sprayed and flows back to the reaction furnace and is gradually taken away by tailings.
However, the airway desiliconization method has the following disadvantages:
(1) under heating, H2SiF6→SiF4+2HF, too, will cause a large amount of HF gas waste, the waste degree is more serious than fluidized bed Si removal method;
(2) the tail slag smoke is very large and is contrary to the current safe environment-friendly situation.
In addition, the existing production method requires that the content of silicon as an impurity of fluorite is lower than 1.0 percent, so that a good desiliconization effect can be achieved during the desiliconization of hydrogen fluoride. Patent CN2011101311998 discloses a production method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder, which comprises the steps of preparing hydrogen fluoride gas, purifying the hydrogen fluoride gas, and reacting the hydrogen fluoride gas with aluminum hydroxide to prepare dry-process aluminum fluoride, wherein the dry-process aluminum fluoride is prepared by improving the technology and adjusting the technology of SiO in fluorite2The mass content is improved to 1.2-1.7%, and qualified aluminum fluoride can still be produced. But when SiO is present in fluorite2When the mass content is higher than 1.7 percent, even reaches 2.5 percent, the method cannot achieve good desiliconization effect. In view of the high cost of low-silicon fluorite, further research is needed on how to produce qualified dry-process aluminum fluoride from fluorite powder with higher silicon impurity content.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder, which not only improves the utilization rate of hydrogen fluoride gas and greatly reduces the production cost, but also ensures the quality of aluminum fluoride products and can meet the normal use of electrolytic aluminum production when the high-silicon content fluorite powder is used for producing the aluminum fluoride.
The invention relates to a method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder, which comprises the following steps:
(1) preparing hydrogen fluoride: reacting the mixed sulfuric acid and the high-silicon fluorite powder in an external heating type rotary reaction furnace to obtain crude hydrogen fluoride gas;
(2) hydrogen fluoride purification: introducing the crude hydrogen fluoride gas into a pre-purification tower, fully contacting with pre-purification acid flowing reversely for pre-purification, cooling to 40-60 ℃, sequentially introducing into a water washing tower and an acid washing tower, and finally separating acid mist by a demister to obtain purified hydrogen fluoride gas;
(3) aluminum fluoride synthesis: introducing the purified hydrogen fluoride gas into a fluidized bed reactor, and reacting with aluminum hydroxide to obtain the dry-process aluminum fluoride.
The mixed sulfuric acid in the step (1) is 98 wt% of sulfuric acid and 105 wt% of nicotinic acid which are mixed according to the mass ratio of 1.5-4.5: 1.
In the step (1), the high-silicon fluorite powder is SiO2Fluorite powder with a content higher than 1.7 wt%, preferably 1.7 wt% < SiO2Fluorite powder with content less than 2.5 wt%.
The mass ratio of the mixed sulfuric acid to the high-silicon fluorite powder in the step (1) is 1.2-1.25: 1.
The rotating speed of the external heating type rotary reaction furnace in the step (1) is 1.8-2 rpm.
The outlet temperature of the mixing chamber of the external heating type rotary reaction furnace in the step (1) is 580-.
Wherein, the chemical equation of the reaction of the mixed sulfuric acid and the high-silicon fluorite powder is as follows:
H2SO4+CaF2＝2HF+CaSO4。
the pre-purified acid in the pre-purifying tower in the step (2) is a mixed solution of 98 wt% sulfuric acid and water, and the content of the pre-purified acid is 12-18 wt%.
In the pre-purification tower, the crude hydrogen fluoride gas is fully contacted with the pre-purification acid flowing reversely, so that dust, sulfuric acid mist, water and partial impurities in the crude hydrogen fluoride gas can be washed away.
In the step (2), the water washing liquid of the water washing tower is a sodium carbonate solution with the concentration of 10-20 wt%; the pickling solution of the pickling tower is 98 wt% of sulfuric acid.
Wherein, the working principle of the water washing tower is as follows: introducing a sodium carbonate solution (10-20 wt%) from the top of the water washing tower, fully contacting with the hydrogen fluoride gas introduced from the bottom of the water washing tower, and carrying out hydrolysis reaction on silicon tetrafluoride in the hydrogen fluoride gas and water in the sodium carbonate solution, wherein the chemical equation is as follows:
SiF4+2H2O＝SiO2+4HF；
simultaneous SiF4With excess HF to form H2SiF6，H2SiF6Reacting with sodium carbonate solution to generate sodium fluosilicate colloidal crystal, wherein the chemical formula is as follows:
SiF4+2HF＝H2SiF6，
H2SiF6+NaCO3＝NaSiF6+H2O+CO2；
si, SiO in hydrogen fluoride gas2、NaSiF6And colloidal precipitate is formed and is discharged to a storage tank from a sewage port at the bottom of the washing tower.
The working principle of the pickling tower is as follows: the HF gas purified from the water washing tower enters from the bottom of the acid washing tower and contacts with the pre-purified acid introduced from the top of the acid washing tower to generate violent exothermic reaction, and the water contained in the purified HF gas is evaporated to achieve the aim of drying.
In the step (3), the top bed reaction temperature in the fluidized bed reactor is 380-500 ℃, the bottom bed reaction temperature is 580-640 ℃, the top bed reaction pressure is-15-22 Kpa, and the bottom bed reaction pressure is-15-0 Kpa.
Wherein, the chemical equation for synthesizing the aluminum fluoride is as follows:
Al(OH)3＝Al2O3+H2O，
6HF+Al2O3＝2AlF3+3H2O。
compared with the prior art, the invention has the following beneficial effects:
(1) the invention utilizes the water washing tower and the acid washing tower to purify and dry the crude hydrogen fluoride gas, thereby not only causing no burden to the pre-purification tower and the acid cooling discharge, but also causing no waste of HF gas and being beneficial to improving the yield;
(2) the invention can adopt SiO by technical improvement and process adjustment2The fluorite with the content higher than 1.7 wt% is used as a raw material to produce aluminum fluoride, and the produced aluminum fluoride product reaches the national standard AF-1 grade in the national standard GB/T4292-2007, and can meet the normal use of electrolytic aluminum production;
(3) the invention adopts fluorite with high impurity silicon content to produce low-silicon dry-method aluminum fluoride, thereby not only expanding the selectivity of raw material fluorite, but also reducing the cost of each ton of aluminum fluoride by about 300 yuan, saving the cost by 900 yuan each year by the productivity of 3 ten thousand tons/year, and improving the market competitiveness of the product.
Detailed Description
The present invention is further illustrated by the following examples, but the scope of the present invention is not limited thereto, and modifications of the technical solutions of the present invention by those skilled in the art should be within the scope of the present invention.
Example 1
The method for producing the low-silicon dry-process aluminum fluoride by using the high-silicon fluorite powder comprises the following steps:
(1) preparing hydrogen fluoride: mixing sulfuric acid (mixed acid of 98 wt% sulfuric acid and 105 wt% fuming sulfuric acid in a mass ratio of 2: 1) with high silica fluorite powder (SiO)2The content is 1.8wt percent) is added into an external heating type rotary reaction furnace according to the mass ratio of 1.2:1 to react to prepare crude hydrogen fluoride gas, the outlet temperature of a mixing chamber of the external heating type rotary reaction furnace is controlled to be 580 ℃, and the rotating speed of the external heating type rotary reaction furnace is 2 rpm.
(2) Hydrogen fluoride purification: crude hydrogen fluoride gas generated in the externally heated rotary furnace enters the pre-purification tower from the lower part of the tower and flows in the reverse direction with pre-purified acid (mixed solution of 98 wt% sulfuric acid and water) to control the water content in the pre-purified acid to 18wt%) to remove dust, sulfuric acid mist, water and partial impurities from the gas, introducing the pre-purified HF gas into a cooling device, cooling to 50 deg.C, introducing from the bottom of the water scrubber, and introducing NaCO flowing in the opposite direction3The solution (10 wt%) is contacted with hydrogen in HF gas2SiF6And SiO2Spraying and washing until the cone of the washing tower is formed into colloidal crystals, precipitating and then externally placing, wherein the liquid level of the washing tower is maintained at 40 percent, and the liquid level is not too high so as to ensure that HF gas is fully contacted with water and then is discharged out of the tower; the tower gas enters the pickling tower from the bottom and flows in the reverse direction with 98 wt% sulfuric acid (the flow is maintained at 20 m)3H) contacting, drying and evaporating redundant water, heating, separating acid mist carried by the purified hydrogen fluoride gas by a demister to obtain relatively pure hydrogen fluoride gas; wherein the acid liquor flowing out of the pre-purification tower and the acid washing tower flows into the mixed sulfuric acid after being dehydrated by the head tank, and is recycled as the raw material of the mixed sulfuric acid.
(3) Aluminum fluoride synthesis: introducing the purified hydrogen fluoride gas into the bottom of the fluidized bed reactor as fluidized gas, and reacting with aluminum hydroxide added at the upper part of the fluidized bed reactor to obtain dry-process aluminum fluoride, wherein the reaction heat released by the reaction maintains the temperature required by the chemical reaction, the top bed reaction temperature in the fluidized bed reactor is 460 ℃, the bottom bed reaction temperature is 620 ℃, the top bed reaction pressure is-10 Kpa, and the bottom bed reaction pressure is-5 Kpa.
Example 2
The method for producing the low-silicon dry-process aluminum fluoride by using the high-silicon fluorite powder comprises the following steps:
(1) preparing hydrogen fluoride: mixing sulfuric acid (mixed acid of 98 wt% sulfuric acid and 105 wt% fuming sulfuric acid in a mass ratio of 4.5: 1) with high silica fluorite powder (SiO2The content is 2.0wt percent) is added into an external heating type rotary reaction furnace according to the mass ratio of 1.22:1 to react to prepare crude hydrogen fluoride gas, the outlet temperature of a mixing chamber of the external heating type rotary reaction furnace is controlled to be 600 ℃, and the rotating speed of the external heating type rotary reaction furnace is 1.9 rpm.
(2) Hydrogen fluoride purification: crude hydrogen fluoride gas generated in the external heating type rotary furnace enters the pre-purification tower from the lower part of the pre-purification tower and flows in the reverse direction with the pre-purification acid(98 wt% of mixed solution of sulfuric acid and water, and the water content in the pre-purified acid is controlled to be 15 wt%) to make full contact, so as to wash away dust, sulfuric acid mist, water content and partial impurities in the gas, the pre-purified HF gas is fed into a cooling device, the temperature of the HF gas is reduced to 50 ℃, and then the HF gas is fed from the bottom of a water washing tower and flows in the reverse direction with the NaCO3The solution (15 wt%) is contacted with hydrogen in HF gas2SiF6And SiO2Spraying and washing until the cone of the washing tower is formed into colloidal crystals, precipitating and then externally placing, wherein the liquid level of the washing tower is maintained at 40 percent, and the liquid level is not too high so as to ensure that HF gas is fully contacted with water and then is discharged out of the tower; the tower gas enters the pickling tower from the bottom and flows in the reverse direction with 98 wt% sulfuric acid (the flow is maintained at 20 m)3H) contacting, drying and evaporating redundant water, heating, separating acid mist carried by the purified hydrogen fluoride gas by a demister to obtain relatively pure hydrogen fluoride gas; wherein the pre-purified acid flowing out of the pre-purification tower and the acid washing tower flows into the mixed sulfuric acid after being dehydrated by the head tank, and is recycled as the raw material of the mixed sulfuric acid.
(3) Aluminum fluoride synthesis: introducing the purified hydrogen fluoride gas into the bottom of the fluidized bed reactor as fluidized gas, and reacting with aluminum hydroxide added at the upper part of the fluidized bed reactor to obtain dry-process aluminum fluoride, wherein the reaction heat released by the reaction maintains the temperature required by the chemical reaction, the top bed reaction temperature in the fluidized bed reactor is 500 ℃, the bottom bed reaction temperature is 640 ℃, the top bed reaction pressure is-15 Kpa, and the bottom bed reaction pressure is-15 Kpa.
Example 3
The method for producing the low-silicon dry-process aluminum fluoride by using the high-silicon fluorite powder comprises the following steps:
(1) preparing hydrogen fluoride: mixing sulfuric acid (mixed acid of 98 wt% sulfuric acid and 105 wt% fuming sulfuric acid in a mass ratio of 1.5: 1) with high silica fluorite powder (SiO2The content is 2.5wt percent) is added into an external heating type rotary reaction furnace according to the mass ratio of 1.25:1 to react to prepare crude hydrogen fluoride gas, the outlet temperature of a mixing chamber of the external heating type rotary reaction furnace is controlled to be 610 ℃, and the rotating speed of the external heating type rotary reaction furnace is 1.8 rpm.
(2) Hydrogen fluoride purification: crude fluorination in externally heated rotary furnacesHydrogen gas enters the pre-purification tower from the lower part of the pre-purification tower, fully contacts with pre-purification acid (mixed solution of 98 wt% sulfuric acid and water, and the water content in the pre-purification acid is controlled to be 12 wt%) flowing reversely, removes dust, sulfuric acid mist, water and partial impurities in the gas, enters a temperature reduction device for the pre-purified HF gas, reduces the temperature of the HF gas to 50 ℃, enters from the bottom of a water washing tower and flows reversely with NaCO3The solution (20 wt%) is contacted with hydrogen in HF gas2SiF6And SiO2Spraying and washing until the cone of the washing tower is formed into colloidal crystals, precipitating and then externally placing, wherein the liquid level of the washing tower is maintained at 40 percent, and the liquid level is not too high so as to ensure that HF gas is fully contacted with water and then is discharged out of the tower; the tower gas enters the pickling tower from the bottom and flows in the reverse direction with 98 wt% sulfuric acid (the flow is maintained at 20 m)3H) contacting, drying and evaporating redundant water, heating, separating acid mist carried by the purified hydrogen fluoride gas by a demister to obtain relatively pure hydrogen fluoride gas; wherein the pre-purified acid flowing out of the pre-purification tower and the acid washing tower flows into the mixed sulfuric acid after being dehydrated by the head tank, and is recycled as the raw material of the mixed sulfuric acid.
(3) Aluminum fluoride synthesis: introducing the purified hydrogen fluoride gas into the bottom of the fluidized bed reactor as fluidized gas, and reacting with aluminum hydroxide added at the upper part of the fluidized bed reactor to obtain dry-process aluminum fluoride, wherein the reaction heat released by the reaction maintains the temperature required by the chemical reaction, the top bed reaction temperature in the fluidized bed reactor is 380 ℃, the bottom bed reaction temperature is 580 ℃, the top bed reaction pressure is 10Kpa, and the bottom bed reaction pressure is 0 Kpa.
Comparative example 1
The method in patent CN2011101311998 is adopted to utilize high-silicon fluorite powder (SiO)2Content of 2.0 wt%) to produce dry-process aluminium fluoride, and its preparation method includes the following steps:
(1) preparing hydrogen fluoride: mixing sulfuric acid (mixed acid of 98 wt% sulfuric acid and 105 wt% fuming sulfuric acid in a mass ratio of 2: 1) with high silica fluorite powder (SiO)22.0 percent of the raw material is added into an external heating type rotary reaction furnace according to the mass ratio of 1.2:1 for reaction to prepare crude hydrogen fluoride gas, the outlet temperature of a mixing chamber of the external heating type rotary reaction furnace is controlled at 600 ℃, and the external heating type rotary reaction furnace is externally heatedThe furnace speed was 2 rpm.
(2) Hydrogen fluoride purification: crude hydrogen fluoride gas generated in the external heating type rotary furnace enters the pre-purification tower from the lower part of the tower, fully contacts with pre-purification acid (mixed liquid of 98 wt% sulfuric acid and water, and the water content in the pre-purification acid is controlled to be 14 wt%), dust, sulfuric acid mist, water and partial impurities in the gas are washed away, and the purified hydrogen fluoride gas is separated from acid mist carried by the purified hydrogen fluoride gas through a demister to obtain relatively pure hydrogen fluoride gas; wherein the pre-purified acid flowing out of the pre-purification tower flows into the mixed sulfuric acid after being dehydrated by the head tank, and is recycled as the raw material of the mixed sulfuric acid.
(3) Aluminum fluoride synthesis: introducing the purified hydrogen fluoride gas into the bottom of the fluidized bed reactor as fluidized gas, and reacting with aluminum hydroxide added at the upper part of the fluidized bed reactor to obtain dry-process aluminum fluoride, wherein the reaction heat released by the reaction maintains the temperature required by the chemical reaction, the top bed reaction temperature in the fluidized bed reactor is 380 ℃, the bottom bed reaction temperature is 580 ℃, the top bed reaction pressure is 10Kpa, and the bottom bed reaction pressure is 0 Kpa.
The aluminum fluoride prepared in examples 1 to 3 and comparative example 1 was subjected to index testing in accordance with the national standard GB/T4292-2007, and the test results are shown in Table 1.
Technical indexes of aluminum fluoride prepared in examples 1 to 3 and comparative example 1
Claims (10)
1. A method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder is characterized by comprising the following steps:
(1) preparing hydrogen fluoride: reacting the mixed sulfuric acid and the high-silicon fluorite powder in an external heating type rotary reaction furnace to obtain crude hydrogen fluoride gas;
(2) hydrogen fluoride purification: introducing the crude hydrogen fluoride gas into a pre-purification tower, fully contacting with pre-purification acid flowing reversely for pre-purification, cooling to 40-60 ℃, sequentially introducing into a water washing tower and an acid washing tower, and finally separating acid mist by a demister to obtain purified hydrogen fluoride gas;
(3) aluminum fluoride synthesis: introducing the purified hydrogen fluoride gas into a fluidized bed reactor, and reacting with aluminum hydroxide to obtain the dry-process aluminum fluoride.
2. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: the mixed sulfuric acid in the step (1) is 98 wt% of sulfuric acid and 105 wt% of nicotinic acid which are mixed according to the mass ratio of 1.5-4.5: 1.
3. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: in the step (1), the high-silicon fluorite powder is SiO2Fluorite powder with content higher than 1.7 wt%.
4. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 3, which is characterized in that: in the step (1), the content of the high-silicon fluorite powder is more than 1.7 wt% and more than SiO2Fluorite powder with content less than 2.5 wt%.
5. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: the mass ratio of the mixed sulfuric acid to the high-silicon fluorite powder in the step (1) is 1.2-1.25: 1.
6. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: the rotating speed of the external heating type rotary reaction furnace in the step (1) is 1.8-2 rpm.
7. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: the outlet temperature of the mixing chamber of the external heating type rotary reaction furnace in the step (1) is 580-.
8. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: the pre-purified acid in the pre-purifying tower in the step (2) is a mixed solution of 98 wt% sulfuric acid and water, and the content of the pre-purified acid is 12-18 wt%.
9. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: in the step (2), the water washing liquid of the water washing tower is a sodium carbonate solution with the concentration of 10-20 wt%; the pickling solution of the pickling tower is 98 wt% of sulfuric acid.
10. The method for producing low-silicon dry-process aluminum fluoride by using high-silicon fluorite powder according to claim 1, which is characterized in that: in the step (3), the top bed reaction temperature in the fluidized bed reactor is 380-500 ℃, the bottom bed reaction temperature is 580-640 ℃, the top bed reaction pressure is-15-22 Kpa, and the bottom bed reaction pressure is-15-0 Kpa.
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