CN101264917B - Method for producing large grain size cryolite - Google Patents
Method for producing large grain size cryolite Download PDFInfo
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- CN101264917B CN101264917B CN2008100496088A CN200810049608A CN101264917B CN 101264917 B CN101264917 B CN 101264917B CN 2008100496088 A CN2008100496088 A CN 2008100496088A CN 200810049608 A CN200810049608 A CN 200810049608A CN 101264917 B CN101264917 B CN 101264917B
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Abstract
The invention discloses a production method for a large grain size cryolite, which is characterized in that Bayer process concentrate solution, caustic soda, and hydrofluoric acid are used as raw materials, and the proportion of raw materials is represented in the equation that Al: Na: F equals to 1:1.8-3:5-6; when compounding, the caustic soda is added into the Bayer process concentrate solutionwith a temperature of 90-95 DEG C, and mixed evenly to obtain the composite solution; then, the composite solution and hydrofluoric acid are gradually added into a synthesis tank, and the material feeding and agitation are carried out in the meantime, the reaction temperature is maintained between 85 and 95 DEG C, and the PH value of the reaction solution is smaller than or equal to 2; after feeding materials, the mixture undergoes an ageing process for 20 to 30 minutes; finally, the slurry is filtered, the filter cake is dried until the water content drops below 0.2%, thus acquiring the finished cryolite. The production method has the advantages that: as wet method is adopted during the production, the reaction is conducted under normal temperature, the process is simple, and easy to operate and control; the heat source is derived from the reaction heat, and the need to add a heating apparatus is avoided; by adjusting the parameters, such as the reaction temperature, PH value and ageing time, the product D50 grain size can be increased by more than 10 Mu m compared with the prior art up to 26-30 Mu m; the molecular ratio of NaF to AlF3 is adjustable, thus meeting the demands of electrolytic aluminum industry.
Description
One, technical field:
The present invention relates to a kind of electrolysis of aluminum fusing assistant, particularly relate to a kind of production method of large grain size cryolite.
Two, background technology:
Cryolith is mainly used in electrolytic aluminum industry, as the fusing assistant of aluminium metallurgy.Traditional cryolith wet process technique mainly contains: aluminium hydroxide-hydrofluoric acid-soda ash method, Sodium Silicofluoride-aluminium hydroxide-soda ash method, Neutral ammonium fluoride-sodium aluminate method and sodium aluminate-hydrofluoric acid-soda processes etc., generally about 15 μ m, filter cake moisture content is generally 30～35% for these method synthetic sodium aluminum fluoride particle diameters D50; Because particle diameter is little, thin partially, so it is big to fly upward loss, it is low to separate efficient during filtration; Filter cake moisture content height in addition, required heat energy is big when being used to dry, and production cost is higher.
The disclosed sodium aluminum fluoride synthetic of Chinese invention patent file has: utilize the by product of producing molecular sieve to prepare the method (publication number 1085523) of sodium aluminum fluoride, produce the method (publication number 1116609) of aluminum fluoride and sodium aluminum fluoride with kaolin, the manufacture method of cryolite with high molecular ratio from (publication number 1117944), production of high molecular-ration cryolite by sodium-fluorosilicate sodium-aluminate method (publication number 1225897), one-step process for preparing cryolite with high molecular ratio from sodium fluosilicate (publication number 1300879).These methods all belong to hydrogen fluoride process and silicofluoric acid method two big classes, all generate in strong acidic environment, and product are Powdered, easily form powder and fly upward, and cause environmental pollution; Filter cake moisture content is higher, and it is big to be used for baking needed heat energy, and production cost is higher.
Application number is 03124693.1, publication number is that 1483674 patent application discloses a kind of particulate state sodium aluminum fluoride crystalline synthetic method, and this method is medium with the gel, spreads in gel, contacts and generate sodium aluminum fluoride by sodium, aluminium, fluorion.The sodium aluminum fluoride particle that this method is produced is bigger, but because the employing gel is a medium, the technology relative complex.
How obtaining the sodium aluminum fluoride of macrobead shape under mild condition, fly upward and financial loss to reduce powder, reduce environmental pollution, reduce production costs, is the problem that waits to solve.
Three, summary of the invention:
The technical problem to be solved in the present invention: overcome the shortcoming of prior art, proposed that a kind of method is simple, easy handling and fly upward loss less, large grain size cryolite production method that production cost is low.
Technical scheme of the present invention is:
Method of the present invention is to be the raw material synthetic cryolite with Bayer process seminal fluid, hydrofluoric acid and caustic soda, and its reaction equation is: Na
2O.Al
2O
3+ 4NaOH+12HF → 2Na
3AlF
6↓+8H
2O
Concrete production method may further comprise the steps,
(1) be raw material with Bayer process seminal fluid, caustic soda and hydrofluoric acid, the feed molar proportioning is Al: Na: F=1: 1.8～3: 5～6;
Add caustic soda when (2) producing in temperature is 90～95 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) described complex liquid and hydrofluoric acid are progressively added the production groove, stir while feeding in raw material, the control feed rate makes that temperature of reaction remains between 85～95 ℃, reaction solution pH≤2; Reinforced back termination reaction, the ageing 20～30min again of finishing;
(4) cryolite slurry after the ageing is filtered filter cake and filtrate, then filter cake is dried to water ratio below 0.2% under 150～300 ℃ of conditions, promptly get the sodium aluminum fluoride product; Described sodium aluminum fluoride product D
50Particle diameter is 26～30 μ m.
Described Bayer process seminal fluid causticity compares α
k=1.5～～2.0, wherein contain Al
2O
3=140～150g/L, SiO
2＜0.6g/L, Fe
2O
3＜0.03g/L; Described caustic soda mass percent 〉=96%.
Described hydrofluoric acid mass percent is 25～32%, wherein H
2SiF
6Mass percent＜0.3%.
Square position filtration, press filtration or ion filter are adopted in described filtration; Described dry air-flow expansion drying or the rotary kiln heat drying of adopting, drying temperature is 150～300 ℃.
Described filtrate is returned the hydrogen fluoride absorption system, recycle.
Beneficial effect of the present invention:
(1) the inventive method is a wet production, reaction is carried out at normal temperatures and pressures, technology is simple, be easy to operate and control, thermal source need not to increase heating installation from reaction heat, adjusts parameters such as temperature of reaction, pH and digestion time by need, product D50 particle diameter ratio traditional method increases more than the 10 μ m, and the D50 particle diameter can reach 26～30 μ m; NaF and AlF in the product
3Molecular ratio adjustable, can be adjusted to 1.7～2.9, more can satisfy the needs of aluminum electrolysis industry development.
(2) good product mobility of the inventive method production is flown upward loss and is lacked; Easily filter, filter cake moisture content is 15～20%, and water ratio is lower, can save a large amount of oven dry expenses, saves production cost; Filtrate is returned the recycle of hydrogen fluoride absorption system; The sodium aluminum fluoride product yield is more than 95%; This product meets national standard, referring to table one, table two.
(3) method of the present invention is polluted and is lacked, and does not need the three wastes to handle, and helps environmental protection.
Table one: sodium aluminum fluoride product of the present invention, the result of laboratory test data following (the quality percentage composition, %):
| Sequence number | Composition | F | Al | Na | SiO 2 | Fe 2O 3 | SO 4 2- | CaO | P 2O 5 | H 2O | Igloss | D50 |
| 1 | Content | 54.50 | 14.50 | 25.10 | 0.22 | 0.04 | 0.55 | 0.18 | 0.02 | 0.20 | 1.90 | 29 |
| 2 | Content | 53.00 | 13.80 | 28.90 | 0.23 | 0.04 | 0.56 | 0.19 | 0.02 | 0.20 | 1.60 | 28 |
| 3 | Content | 52.30 | 12.70 | 30.20 | 0.23 | 0.04 | 0.56 | 0.18 | 0.02 | 0.19 | 1.30 | 29 |
Table two: sodium aluminum fluoride product national standard (GB/T4291-2007):
Annotate: the condition of igloss is 550 ℃, 30min in table one, the table two, and the unit of D50 is μ m in the table one.
Contrast as seen, large grain size cryolite quality product of the present invention reaches the GB/T4291-2007 standard.
Four, description of drawings:
Fig. 1: the technological process of production figure of large grain size cryolite
Five, embodiment:
Embodiment one: the production method of large grain size cryolite, referring to accompanying drawing 1, may further comprise the steps,
(1) raw material and consumption: with Bayer process seminal fluid, caustic soda and hydrofluoric acid is raw material, and the feed molar proportioning is Al: Na: F=1: 3: 6; Be Al
3+: Na
+: F
-=1: 3: 6;
Require: Bayer process seminal fluid causticity compares α
k=1.5～2.0, wherein contain Al
2O
3140～150g/L, SiO
2＜0.6g/L, Fe
2O
3＜0.03g/L; The mass percent of NaOH 〉=96% in the caustic soda; Hydrofluoric acid is absorbed through water by HF and forms, and wherein the HF mass percent is 25～32%, wherein H
2SiF
6Mass percent＜0.3%.
(2) complex liquid preparation: add caustic soda when synthetic in temperature is 90 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) sodium aluminum fluoride is synthetic: complex liquid and hydrofluoric acid are under agitation progressively added synthetic groove in proportion, control feed rate in the reinforced process, make temperature of reaction between 90～95 ℃, reaction solution pH≤2; Reinforced back termination reaction, the ageing 20min again of finishing;
(4) cryolite slurry after the ageing is filtered with horizontal table filter, get filter cake and filtrate, filter cake moisture content is 15%; Then with filter cake under 280 ℃ of conditions, the air-flow expansion drying promptly gets the sodium aluminum fluoride finished product to water ratio 0.2% (mass ratio); Filtrate is returned the hydrofluoric acid absorption cell, as hydrofluoric absorption liquid, recycles.The sodium aluminum fluoride product yield is 98.5%.
Embodiment two: the production method of large grain size cryolite, no longer repeat with embodiment one something in common, and difference is,
(1) raw material and consumption: with Bayer process seminal fluid, caustic soda and hydrofluoric acid is raw material, and the feed molar proportioning is Al: Na: F=1: 3: 5;
(2) complex liquid preparation: add caustic soda when synthetic in temperature is 95 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) sodium aluminum fluoride is synthetic: add the filtrate of partly circulating in synthetic groove, add-on reaches the height of stir shaft with amount of filtrate, under constantly stirring, simultaneously in proportion progressively adds in synthetic groove by scale tank complex liquid and hydrofluoric acid, the control feed rate makes temperature of reaction between 85～90 ℃; Reaction end pH≤3, ageing 30 minutes;
(4) with the cryolite slurry press filtration after the ageing, get filter cake and filtrate, filter cake moisture content is 20%; Then with filter cake under 300 ℃ of conditions, rotary kiln direct drying to water ratio is 0.2% (mass ratio), promptly gets the sodium aluminum fluoride finished product.The sodium aluminum fluoride product yield is 95.7%.
Embodiment three: the production method of large grain size cryolite, no longer repeat with embodiment one something in common, and difference is,
(1) raw material and consumption: with Bayer process seminal fluid, caustic soda and hydrofluoric acid is raw material, and the feed molar proportioning is Al: Na: F=1: 2: 6;
(2) complex liquid preparation: add caustic soda when synthetic in temperature is 90 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) sodium aluminum fluoride is synthetic: complex liquid and hydrofluoric acid are under agitation progressively added synthetic groove in proportion, and temperature of reaction is 88～90 ℃; Ageing 25 minutes;
(4) with the cryolite slurry press filtration after the ageing, get filter cake and filtrate, filter cake moisture content is 16%; Then with filter cake under 160 ℃ of conditions, rotary kiln direct drying to water ratio is 0.19% (mass ratio), promptly gets the sodium aluminum fluoride finished product.The sodium aluminum fluoride product yield is 96.8%.
Embodiment four: the production method of large grain size cryolite, no longer repeat with embodiment one something in common, and difference is,
(1) raw material and consumption: with Bayer process seminal fluid, caustic soda and hydrofluoric acid is raw material, and the feed molar proportioning is Al: Na: F=1: 2.5: 5;
(2) complex liquid preparation: add caustic soda when synthetic in temperature is 91 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) sodium aluminum fluoride is synthetic: complex liquid and hydrofluoric acid are under agitation progressively added synthetic groove in proportion, and temperature of reaction is 90～94 ℃; Reaction end pH≤3, ageing 28 minutes;
(4) the cryolite slurry press filtration after the ageing is got filter cake and filtrate, filter cake moisture content is 18%; Then with filter cake under 280 ℃ of conditions, the rotary kiln direct drying to water ratio at 0.19% (mass ratio), promptly get the sodium aluminum fluoride finished product.The sodium aluminum fluoride product yield is 97.3%.
Embodiment five: the production method of large grain size cryolite, no longer repeat with embodiment one something in common, and difference is,
(1) raw material and consumption: with Bayer process seminal fluid, caustic soda and hydrofluoric acid is raw material, and the feed molar proportioning is Al: Na: F=1: 1.8: 5;
(2) complex liquid preparation: add caustic soda when synthetic in temperature is 93 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) sodium aluminum fluoride is synthetic: complex liquid and hydrofluoric acid are under agitation progressively added synthetic groove in proportion, and temperature of reaction is 86～89 ℃; Reaction end pH≤3, ageing 22 minutes;
(4) with the cryolite slurry press filtration after the ageing, get filter cake and filtrate, filter cake moisture content is 17%; Then with filter cake under 260 ℃ of conditions, rotary kiln direct drying to water ratio is 0.19% (mass ratio), promptly gets the sodium aluminum fluoride finished product.The sodium aluminum fluoride product yield is 95.4%.
Embodiment six: the production method of large grain size cryolite, no longer repeat with embodiment one something in common, and difference is,
(1) raw material and consumption: with Bayer process seminal fluid, caustic soda and hydrofluoric acid is raw material, and the feed molar proportioning is Al: Na: F=1: 2.2: 6;
(2) complex liquid preparation: add caustic soda when synthetic in temperature is 90 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) sodium aluminum fluoride is synthetic: complex liquid and hydrofluoric acid are under agitation progressively added synthetic groove in proportion, and temperature of reaction is 90～95 ℃; Reaction end pH≤3, ageing 23 minutes;
(4) with the cryolite slurry press filtration after the ageing, get filter cake and filtrate, filter cake moisture content is 16%; Then with filter cake under 200 ℃ of conditions, the rotary kiln direct drying to water ratio below 0.2% (mass ratio), promptly get the sodium aluminum fluoride finished product.The sodium aluminum fluoride product yield is 97.4%.
Claims (6)
1. the production method of a large grain size cryolite is characterized in that: may further comprise the steps,
(1) be raw material with Bayer process seminal fluid, caustic soda and hydrofluoric acid, the feed molar proportioning is Al: Na: F=1: 1.8～3: 5～6;
Add caustic soda when (2) producing in temperature is 90～95 ℃ Bayer process seminal fluid, stir, mixing gets complex liquid;
(3) described complex liquid and hydrofluoric acid are progressively added the production groove, stir while feeding in raw material, the control feed rate makes that temperature of reaction remains between 85～95 ℃, reaction solution pH≤2; Reinforced back termination reaction, the ageing 20～30min again of finishing;
(4) cryolite slurry after the ageing is filtered filter cake and filtrate, then filter cake is dried to water ratio below 0.2% under 150～300 ℃ of conditions, promptly get the sodium aluminum fluoride product; Described sodium aluminum fluoride product D
50Particle diameter is 26～30 μ m.
2. the production method of large grain size cryolite according to claim 1, it is characterized in that: described Bayer process seminal fluid causticity compares α
k=1.5～～2.0, wherein contain Al
2O
3=140～150g/L, SiO
2＜0.6g/L, Fe
2O
3＜0.03g/L.
3. the production method of large grain size cryolite according to claim 1 is characterized in that: described caustic soda mass percent 〉=96%.
4. the production method of large grain size cryolite according to claim 1, it is characterized in that: described hydrofluoric acid mass percent is 25～32%, wherein H
2SiF
6Mass percent＜0.3%.
5. according to the production method of each described large grain size cryolite of claim 1～4, it is characterized in that: square position filtration, press filtration or ion filter are adopted in described filtration; Described dry air-flow expansion drying or the rotary kiln heat drying of adopting, drying temperature is 150～300 ℃.
6. according to the production method of each described large grain size cryolite of claim 1～4, it is characterized in that: described filtrate is returned the hydrogen fluoride absorption system, recycle.
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|---|---|---|---|
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|---|---|---|---|
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| CN101264917B true CN101264917B (en) | 2010-06-16 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN86105321A (en) * | 1985-09-06 | 1987-03-04 | 皮奇尼铝业公司 | The recovery method of sodium aluminate in the red soil |
| CN1231990A (en) * | 1999-01-28 | 1999-10-20 | 李世江 | Production of cryolite by hydrofluoric acid and sodium aluminate method |
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2008
- 2008-04-23 CN CN2008100496088A patent/CN101264917B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN86105321A (en) * | 1985-09-06 | 1987-03-04 | 皮奇尼铝业公司 | The recovery method of sodium aluminate in the red soil |
| CN1231990A (en) * | 1999-01-28 | 1999-10-20 | 李世江 | Production of cryolite by hydrofluoric acid and sodium aluminate method |
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