CN116005007A - Method for preparing magnesium metal and magnesium aluminate spinel by aluminothermic reduction - Google Patents
Method for preparing magnesium metal and magnesium aluminate spinel by aluminothermic reduction Download PDFInfo
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- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 230000009467 reduction Effects 0.000 title claims abstract description 86
- 239000011777 magnesium Substances 0.000 title claims abstract description 79
- 229910052749 magnesium Inorganic materials 0.000 title claims abstract description 78
- 229910052596 spinel Inorganic materials 0.000 title claims abstract description 71
- 239000011029 spinel Substances 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 51
- -1 magnesium aluminate Chemical class 0.000 title claims description 36
- 238000006722 reduction reaction Methods 0.000 claims abstract description 102
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 81
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 62
- 239000002893 slag Substances 0.000 claims abstract description 55
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 50
- 238000007670 refining Methods 0.000 claims abstract description 43
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000001354 calcination Methods 0.000 claims abstract description 33
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims abstract description 32
- 239000000843 powder Substances 0.000 claims abstract description 30
- 239000001095 magnesium carbonate Substances 0.000 claims abstract description 29
- 235000014380 magnesium carbonate Nutrition 0.000 claims abstract description 29
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims abstract description 29
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims abstract description 29
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 238000004090 dissolution Methods 0.000 claims abstract description 21
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000002425 crystallisation Methods 0.000 claims abstract description 19
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 19
- 230000008025 crystallization Effects 0.000 claims abstract description 18
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 16
- 239000011775 sodium fluoride Substances 0.000 claims abstract description 16
- 235000013024 sodium fluoride Nutrition 0.000 claims abstract description 16
- 239000000463 material Substances 0.000 claims abstract description 15
- 239000007788 liquid Substances 0.000 claims abstract description 14
- 239000000203 mixture Substances 0.000 claims abstract description 14
- 238000003825 pressing Methods 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims abstract description 6
- 238000000227 grinding Methods 0.000 claims abstract description 5
- 230000007246 mechanism Effects 0.000 claims description 57
- 238000004519 manufacturing process Methods 0.000 claims description 19
- 239000000654 additive Substances 0.000 claims description 16
- 239000012530 fluid Substances 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 12
- 230000000996 additive effect Effects 0.000 claims description 9
- 239000003832 thermite Substances 0.000 claims description 9
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 230000035484 reaction time Effects 0.000 claims description 8
- 239000013078 crystal Substances 0.000 claims description 5
- 238000004891 communication Methods 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 2
- 238000003723 Smelting Methods 0.000 abstract description 14
- 239000004484 Briquette Substances 0.000 abstract description 2
- 239000012535 impurity Substances 0.000 description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- 230000008569 process Effects 0.000 description 12
- 239000000292 calcium oxide Substances 0.000 description 10
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 10
- 230000000694 effects Effects 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 239000011734 sodium Substances 0.000 description 8
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 6
- 239000003638 chemical reducing agent Substances 0.000 description 6
- 239000000377 silicon dioxide Substances 0.000 description 6
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 229910001629 magnesium chloride Inorganic materials 0.000 description 3
- 238000011946 reduction process Methods 0.000 description 3
- 239000011819 refractory material Substances 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052599 brucite Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a method for preparing magnesium metal and magnesia-alumina spinel by aluminothermic reduction, which comprises the following steps: calcining magnesite and grinding to obtain magnesia powder; uniformly mixing magnesium oxide powder, aluminum powder, sodium fluoride and anhydrous magnesium chloride to obtain a mixed material; pressing the mixture into a briquette; carrying out reduction reaction on the agglomerate under vacuum condition; reducing slag is obtained in the reduction zone, and a crystallization mixture is obtained by collecting in a crystallizer; placing the reducing slag in sodium hydroxide solution for dissolution reaction, and filtering after the reaction is finished to obtain filter residues; calcining the filter residue to obtain magnesia-alumina spinel; and (3) placing the crystallization mixture into a refining furnace for refining to obtain magnesium liquid and refining slag. The invention can greatly improve the purity of the magnesia-alumina spinel and improve the economical efficiency and feasibility of the reduction magnesium smelting of the low-grade magnesite Dan Lvre.
Description
Technical Field
The invention relates to the technical field of magnesium smelting. In particular to a method for preparing magnesium metal and magnesia-alumina spinel by aluminothermic reduction.
Background
More than 85% of the magnesium metal in the world is currently produced by the Pidgeon process. The Pidgeon process is a vacuum silicon thermal reduction magnesium smelting method which takes dolomite as a raw material and ferrosilicon as a reducing agent; the method has the advantages of high energy consumption of magnesium metal production, large material consumption, high carbon emission and unavailable reducing slag; these drawbacks seriously affect the sustainable development of the magnesium industry; therefore, there is an urgent need to develop a new magnesium smelting technology with low energy consumption, low carbon emission and no waste residue emission.
Patent CN101942573B proposes a method for preparing magnesium metal and preparing magnesia-alumina spinel as a byproduct by using active magnesium oxide and aluminum or aluminum alloy as raw materials. The method comprises the steps of calcining magnesite or brucite to obtain magnesium oxide, then carrying out vacuum thermal reduction magnesium smelting by taking aluminum or aluminum alloy as a reducing agent, obtaining magnesium metal and reducing slag with magnesium aluminate spinel as a main component after reduction, and obtaining the high-density magnesium aluminate spinel refractory material after high-temperature calcination of the reducing slag. By using the method, the energy consumption in the magnesium smelting process can be reduced by more than 50% compared with the Pidgeon method, the raw material consumption is reduced by more than 50%, the carbon emission is reduced by 60%, and the reduction slag can be fully utilized.
The method for smelting magnesium has low energy consumption and low carbon emission, and the reducing slag can be used for preparing magnesia-alumina spinel refractory materials, thereby being a novel magnesium smelting technology with great prospect. However, since the high-quality magnesite in China is completely mined, the content of impurities in the currently mined magnesite is higher (mainly the content of silicon dioxide and calcium oxide is high), and impurities in the reduced magnesite are all remained in the reducing slag in the process of producing magnesium metal by using the method of the patent CN101942573B, so that the content of impurities in the reducing slag is higher, the content of magnesia-alumina spinel Dan Zazhi produced by taking the reducing slag as a raw material is high, and particularly the content of calcium oxide and silicon dioxide is more than 1%, so that the national standard of magnesia-alumina spinel is difficult to be reached, and the economical efficiency and feasibility of the technology are seriously reduced.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a method for preparing metal magnesium and 5-magnesia-alumina spinel by aluminothermic reduction, which aims to solve the problem of obtaining byproducts when low-quality magnesite is used as a raw material for smelting magnesium
The magnesia-alumina spinel has high impurity content and is difficult to reach the national standard of magnesia-alumina spinel.
In order to solve the technical problems, the invention provides the following technical scheme:
a method for preparing magnesium metal and magnesium aluminate spinel by aluminothermic reduction, comprising the following steps:
step (1), calcining low-grade magnesite and grinding to obtain magnesia powder;
step 0 (2), oxidizing aluminum powder serving as a reducing agent and sodium fluoride and anhydrous magnesium chloride serving as additives
Uniformly mixing magnesium powder, aluminum powder, sodium fluoride and anhydrous magnesium chloride to obtain a mixed material;
step (3), pressing the mixed material into a block at room temperature;
step (4), placing the agglomerate into a vacuum reduction tank, and carrying out reduction reaction under vacuum condition; and also (3) the method
After the original reaction is finished, reducing slag is obtained in a reduction zone, and a crystallization mixture is obtained by collecting in a crystallizer; step 5 (5), placing the reducing slag in sodium hydroxide solution to carry out dissolution reaction, and ending the dissolution reaction
Filtering to obtain filter residues;
calcining the filter residue to obtain magnesia-alumina spinel;
step (7), placing the crystallization mixture into a refining furnace for refining, and obtaining magnesium liquid and magnesium liquid after refining
Refining slag. The invention takes low-grade magnesite as a raw material, aluminum as a reducing agent, sodium fluoride and magnesium chloride 0 as additives to prepare magnesium metal and magnesium aluminate spinel as a raw material from magnesium smelting reducing slag; the basic principle is that
And adding an additive in the reduction process to enable the additive to react with impurities in the low-grade magnesite, converting the additive into a distillable substance for removal, and achieving the purpose of purifying the magnesia-alumina spinel.
In the method for preparing the magnesium metal and the magnesia-alumina spinel by aluminothermic reduction, in the step (1), the magnesite is prepared
The calcination temperature is 800-1100 ℃ and the calcination time is 0.5-4 h. If the calcining temperature of the magnesite is too low or the calcining time is too short, the calcining decomposition of the magnesite is not complete enough, and if the calcining temperature is too high or the calcining time is too long, the activity of the magnesia obtained by calcining is reduced; the calcining temperature of the magnesite is controlled at 800-1100 ℃ and the calcining time is controlled at 0.5-4 h, so that the magnesite can be fully decomposed, and the magnesia with higher activity can be obtained.
In the method for preparing the magnesium metal and the magnesium aluminate spinel by aluminothermic reduction, in the step (2), the mass ratio of the magnesium oxide powder, the aluminum powder, the sodium fluoride and the anhydrous magnesium chloride is (2.0-5.0): 1 (0.03-0.20): 0.03-0.20; the reduction reaction efficiency is high and the impurity removing effect is good.
The method for preparing the magnesium metal and the magnesium aluminate spinel by the thermite reduction comprises the following steps of (1) preparing the magnesium metal and the magnesium aluminate spinel by the thermite reduction, wherein the particle size of magnesia powder is less than or equal to 0.15mm; in the step (2), the particle size of the mixed materials is less than or equal to 0.15mm; if the particle size of the raw material particles is too large, the reduction rate of magnesium oxide is lowered.
In the method for preparing the magnesium metal and the magnesium aluminate spinel by aluminothermic reduction, in the step (3), the pressing pressure is 100-200 MPa; if the pressing pressure is too high, the reduction rate of magnesium oxide is affected.
In the above method for preparing magnesium metal and magnesium aluminate spinel by aluminothermic reduction, in the step (4), the absolute pressure under vacuum condition is 0.01-30 Pa, if absoluteToo high pressure can affect the reduction rate of magnesium oxide; the temperature of the reduction reaction is 1100-1300 ℃, and the reaction time is 9-16 h. In the reduction process, magnesium oxide is reduced into gaseous magnesium metal by aluminum, the gaseous magnesium metal moves to a crystallization area to be crystallized on a crystallizer, and reducing slag is left in the reduction area; according to the different proportion of magnesium oxide and aluminum powder, the main component of the reduction slag is MgO-Al 2 O 3 +MgO or MgO.Al 2 O 3 +Al 2 O 3 。
In the course of the reduction reaction of the present invention, additives NaF and MgCl are added in addition to the reduction reaction of magnesium oxide 2 A series of reactions also occur. By these reactions, the reduction reaction can be accelerated, and most of the impurities CaO and SiO in the reducing slag are removed 2 The magnesium reduction rate is improved and the reduction slag is purified by removing. Additives NaF and MgCl 2 The main reactions that occur are shown in formulas 1-6, by which the majority of CaO impurities in the magnesia powder are converted to CaCl 2 Is distilled in vacuum and crystallized on a crystallizer, while SiO in the magnesia powder 2 Partial conversion of impurities to SiF 4 And (5) removing gas. The additive MgCl remaining during the reduction 2 And NaF, and react to form other components (metallic sodium and Na 3 AlF 6 ) Will also be distilled off in vacuo and crystallised on a crystalliser.
MgCl 2 +CaO＝CaCl 2 +MgO(1)
Al+6NaF＝3Na+Na 3 AlF 6 (2)
SiO 2 +4NaF＝2Na 2 O+SiF 4 (3)
3SiO 2 +2Na 3 AlF 6 ＝3Na 2 O+Al 2 O 3 +3SiF 4 (4)
2Na+MgO＝Na 2 O+Mg(5)
3Na 2 O+2Al＝6Na+Al 2 O 3 (6)
In the method for preparing the magnesium metal and the magnesium aluminate spinel by aluminothermic reduction, in the step (5), the mass fraction of sodium hydroxide in the sodium hydroxide solution is 1-10wt%; sodium hydroxide solution and reducing slag massThe ratio is (2-10) 1, the reducing slag obtained after reduction exists in the form of porous agglomerate; the temperature of the dissolution reaction is 10-80 ℃, the dissolution reaction time is 0.5-2 h, and the ideal dissolution effect can be obtained under the dissolution reaction condition. During the dissolution process, unreacted metal aluminum powder and part of SiO in the reducing slag 2 Is reacted with NaOH solution to be converted into sodium aluminate and sodium silicate, and enters the dissolution liquid to be separated from slag (as shown in the formulas 7 and 8):
SiO 2 +2NaOH＝Na 2 SiO 3 +H 2 O (7)
2Al+2NaOH+6H 2 O＝2NaAl(OH) 4 +3H 2 (8)。
in the method for preparing the magnesium metal and the magnesium aluminate spinel by the aluminothermic reduction, in the step (6), the calcining temperature is 1700-1800 ℃, the calcining time is 12-36 h, if the calcining temperature is lower than 1700 ℃, the density of the obtained magnesium aluminate spinel is unqualified, and if the calcining temperature is higher than 1800 ℃, the spinel is molten; if the calcination time is less than 12 hours, the obtained magnesia-alumina spinel density is also unqualified; the calcination time is higher than 36 hours, so that the unit consumption of the product is increased, and the cost is increased; the density of the high purity is 3.25 to 3.35g/cm after calcination 3 A finished magnesia-alumina spinel refractory product; in the step (7), the refining temperature is 700-750 ℃ and the refining time is 0.5-2 h; when the refining temperature is too low or the refining time is insufficient, the content of impurities after refining is high due to the high viscosity of the magnesium liquid, but when the refining temperature is too high or the refining time is too long, the burning loss of magnesium is serious and the magnesium yield is lowered. Magnesium metal and MgCl as additive remained in materials during reduction 2 And NaF, and react to form metallic sodium and CaCl 2 And Na (Na) 3 AlF 6 And crystallizing on a crystallizer, taking the crystallized mixture out of the crystallizer, and putting the crystallized mixture into a refining furnace for refining to obtain magnesium liquid and refining slag in the refining process.
The method for preparing the magnesium metal and the magnesium aluminate spinel by the thermit reduction is realized by a production system for preparing the magnesium metal and the magnesium aluminate spinel by the thermit reduction; the production system for preparing the magnesium metal and the magnesium aluminate spinel by aluminothermic reduction comprises a magnesium oxide production mechanism, a mixing mechanism, a forming mechanism, a reduction mechanism, a magnesium metal generating mechanism and a magnesium aluminate spinel generating mechanism; the magnesia discharge port of the magnesia production mechanism is communicated with the magnesia feed port of the mixing mechanism; the discharge port of the mixing mechanism is communicated with the feed port of the forming mechanism; the discharge port of the forming mechanism is adjacent to the feed port of the reduction mechanism; the crystal discharge port of the reduction mechanism is communicated with the feed port of the magnesium metal generating mechanism; and a reducing slag discharge port of the reducing mechanism is adjacent to a feed port of the magnesia-alumina spinel generating mechanism.
The method for preparing the magnesium metal and the magnesium aluminate spinel by the aluminothermic reduction comprises the steps of a magnesium oxide production mechanism comprising a crusher, a first calciner and a pulverizer; the discharge port of the crusher is communicated with the feed port of the first calciner through a first conveyor belt; the discharge port of the first calciner is communicated with the feed port of the pulverizer through a second conveyor belt;
the mixing mechanism comprises a feeder and a mixer; the discharge port of the feeder is positioned right above the additive feed port of the mixer; the magnesium oxide discharge port of the pulverizer is communicated with the magnesium oxide feed port of the mixer through a third conveyor belt;
the forming mechanism is a powder forming machine; the discharge port of the mixer is communicated with the feed port of the powder forming machine through a fourth conveyor belt;
the reduction mechanism is a vacuum reduction tank, and the vacuum reduction tank is provided with a crystallization area and a reduction slag area; the powder forming machine conveys the formed agglomerate to a position adjacent to a feed inlet of the vacuum reduction tank through a fifth conveyor belt;
the magnesium metal generating mechanism comprises a refining furnace; the crystal discharge port of the crystallization zone is communicated with the feed port of the refining furnace through a seventh conveyor belt;
the magnesia-alumina spinel generating mechanism comprises a solution pool, a filter and a second calciner; the fluid outlet end of the molten pool is in fluid communication with the fluid inlet end of the filter through a pipeline; the filter residue outlet end of the filter is communicated with the feed inlet of the second calciner through an eighth conveyor belt; and the reducing slag discharge port of the reducing slag zone conveys reducing slag to a position adjacent to the feed port of the molten pool through a sixth conveyor belt.
The reduction tank adopted in the reduction process is the same as the current Pidgeon magnesium smelting reduction tank; the refining process of the crystallized product is the same as that of the current Pidgeon process for smelting magnesium; the main composition of the magnesia-alumina spinel product is related to the proportion of the magnesia to the aluminum powder, and various magnesia-alumina spinel refractory materials with the alumina content of 0-95 wt% can be prepared by adjusting the proportion of the magnesia powder to the aluminum powder in the process of proportioning.
The technical scheme of the invention has the following beneficial technical effects:
in the invention, sodium fluoride and 5 magnesium chloride are added as additives in the aluminothermic reduction magnesium smelting process of low-grade magnesite, so that main impurities CaO and SiO in the reduced materials are reduced 2 React with the additive to generate
The materials are easy to distill and remove, and the reducing slag is further purified by alkali liquor leaching, so that the purity of the prepared magnesia-alumina spinel is greatly improved, and the economical efficiency and feasibility of reducing and smelting magnesium by low-grade magnesite Dan Lvre are improved.
Drawings
FIG. 1 is a schematic process flow diagram of a method for preparing metallic magnesium and magnesia-alumina spinel by aluminothermic reduction in an embodiment of the invention;
FIG. 2 is a schematic diagram of the structure of a production system for preparing metallic magnesium and magnesium aluminate spinel using thermite reduction in example 2 of the present invention.
The reference numerals in the drawings are as follows: 1-a crusher; 2-a first calciner; 3-pulverizing; 4-a feeder; 5-a mixer; 6-a powder forming machine; 7-a vacuum reduction tank; 8-a dissolving tank; 9-filtering machine; 10-a second calciner; 11-a first conveyor belt; 12-a second conveyor belt; 13-a third conveyor belt; 14-fourth conveyor belt; 15-a fifth conveyor belt; 16-sixth conveyor belt; 17-seventh conveyor belt; 18-eighth conveyor belt; 19-piping; 20-a refining furnace; 71-crystallization zone; 72-reducing slag zone; 81-sodium hydroxide solution.
Detailed Description
Example 1
In the embodiment, the technological process of the method for preparing the magnesium metal and the magnesium aluminate spinel through aluminothermic reduction is shown in a graph 0 1; the method specifically comprises the following steps:
calcining the low-grade magnesite at 1000 ℃ for 2 hours, and grinding the calcined magnesite until the particle size of the low-grade magnesite is smaller than or equal to 0.15mm to obtain magnesia powder; in the embodiment, the impurity content in the low-grade magnesite is high, the content of silicon dioxide is 1.00 weight percent, and the content of calcium oxide is 1.30 weight percent.
Step (2), using aluminum powder with the particle size smaller than or equal to 0.15mm as a reducing agent, using sodium fluoride with the particle size smaller than or equal to 5mm and anhydrous magnesium chloride as additives, and mixing magnesia powder, aluminum powder and sodium fluoride
Uniformly mixing the magnesium chloride and anhydrous magnesium chloride according to the mass ratio of 3:1:0.1:0.1 to obtain a mixed material;
step (3), pressing the mixed material into a block under the condition of 150MPa and room temperature to form the block;
step (4), placing the agglomerate into a vacuum reduction tank, and carrying out reduction reaction under vacuum conditions, wherein the absolute pressure in the vacuum reduction tank is 10Pa in the embodiment; the temperature of the reduction reaction is 1200 ℃, the reaction time is 12 hours, in other embodiments, the temperature of the reduction reaction can be any temperature between 1100 ℃ and 1300 ℃, the reaction time can be any time between 9 hours and 16 hours, and under the reaction condition, the reduction effect of the magnesium oxide is good and the production cost is low; after the reduction reaction is finished, reducing slag is obtained in a reduction zone, and a crystallization mixture is obtained by collecting in a crystallizer;
step (5), placing the reducing slag in a sodium hydroxide solution with the mass fraction of 5wt% for dissolution reaction, wherein the mass ratio of the sodium hydroxide solution to the reducing slag is 8:1; the temperature of the dissolution reaction is 25 ℃, and the dissolution reaction time is 1h; filtering after the dissolution reaction is finished to obtain filter residues; of course, in other embodiments, the mass ratio of the sodium hydroxide solution to the reducing slag can be selected to be any value between (2-10): 1, and the digestion effect of sodium hydroxide can be fully exerted, so that the aluminum metal powder and part S in the reducing slagiO 2 Fully reacting with NaOH solution; the mass fraction of the sodium hydroxide solution can be selected to be any concentration between 1 and 10 weight percent, and the sodium hydroxide solution with the concentration range has good dissolution effect and does not cause serious corrosion to equipment.
Step (6), placing filter residues at 1700 ℃ for calcination for 24 hours, and obtaining magnesia-alumina spinel after the calcination is finished; the density of the magnesia-alumina spinel prepared in this example is 3.30g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The content of calcium oxide in the magnesia-alumina spinel was 0.15wt% and the content of silica was 0.10wt%.
Step (7), placing the crystallization mixture into a refining furnace for refining, wherein the refining temperature is 720 ℃, and the refining time is 1.5h; and after refining, obtaining magnesium liquid and refined slag, and casting the magnesium liquid to obtain the metal magnesium ingot.
Example 2
The production system for preparing the metal magnesium and the magnesium aluminate spinel by using the thermite reduction is used for realizing the preparation of the metal magnesium and the magnesium aluminate spinel by using the thermite reduction; the production system is shown in fig. 2; as can be seen from fig. 2, the production system of the present embodiment includes a magnesium oxide production mechanism, a mixing mechanism, a molding mechanism, a reduction mechanism, a magnesium metal generation mechanism, and a magnesium aluminate spinel generation mechanism; the magnesium oxide production mechanism comprises a crusher 1, a first calciner 2 and a pulverizer 3; the mixing mechanism comprises a feeder 4 and a mixer 5; the forming mechanism is a powder forming machine 6; the reduction mechanism is a vacuum reduction tank 7, and the vacuum reduction tank 7 is provided with a crystallization area 71 and a reducing slag area 72; the magnesium metal generating mechanism comprises a refining furnace 20; in other embodiments, the magnesium metal generating mechanism further includes a magnesium liquid casting apparatus, the fluid outlet of the refining furnace 20 being in fluid communication with the fluid inlet of the magnesium liquid casting apparatus; the magnesia-alumina spinel generating mechanism comprises a solution pool 8, a filter 9 and a second calciner 10.
The discharge port of the crusher 1 is communicated with the feed port of the first calciner 2 through a first conveyor belt 11; the discharge port of the first calciner 2 is communicated with the feed port of the pulverizer 3 through a second conveyor belt 12; the discharge port of the pulverizer 3 is communicated with the magnesia feed port of the mixer 5 through a third conveyor belt 13; the discharge port of the feeder 4 is positioned right above the additive feed port of the mixer 5; the discharge port of the mixer 5 is communicated with the feed port of the powder forming machine 6 through a fourth conveyor belt 14; the powder forming machine 6 conveys the formed briquette to a position adjacent to a feed port of the vacuum reduction tank 7 by a fifth conveyor 15;
the crystal outlet of the crystallization zone 71 is communicated with the inlet of the refining furnace 20 through a seventh conveyor belt 17; the reducing slag discharge port of the reducing slag zone 72 conveys the reducing slag to a position adjacent to the feed port of the solution tank 8 by the sixth conveyor 16; the fluid outlet end of the bath 8 is in fluid communication with the fluid inlet end of the filter 9 via a pipe 19; the filter residue outlet end of the filter 9 is communicated with the feed inlet of the second calciner 10 through an eighth conveyor 18. In this embodiment, the molten pool 8 has a sodium hydroxide solution 81 of 1 to 10wt% in mass fraction.
The method for preparing the magnesium metal and the magnesium aluminate spinel by aluminothermic reduction in the embodiment specifically comprises the following steps:
step (1), crushing low-grade magnesite in a crusher 1, conveying the crushed low-grade magnesite to a first calciner 2 through a first conveyor belt 11, calcining the crushed low-grade magnesite in the first calciner 2 at 1100 ℃ for 1h, conveying the crushed low-grade magnesite to a pulverizer 3 through a second conveyor belt 12, and grinding the crushed low-grade magnesite to a particle size of less than or equal to 0.15mm to obtain magnesia powder; in the embodiment, the impurity content in the low-grade magnesite is high, the content of silicon dioxide is 1.10 weight percent, and the content of calcium oxide is 1.80 weight percent.
Step (2), conveying the magnesia powder processed by the pulverizer 3 into a mixer 5 through a third conveyor belt 13, simultaneously adding aluminum powder with the particle size smaller than or equal to 0.15mm into the mixer 5 through a feeder 4 as a reducing agent, taking sodium fluoride and anhydrous magnesium chloride with the particle size smaller than or equal to 0.15mm as additives, controlling the mass ratio of the magnesia powder, the aluminum powder, the sodium fluoride and the anhydrous magnesium chloride in the mixer 5 to be 5:1:0.2:0.2, and uniformly mixing in the mixer 5 to obtain a mixed material;
step (3), the mixed material is conveyed into a powder forming machine 6 through a fourth conveyor belt 14, and is pressed in the powder forming machine 6 under the conditions of 200MPa and room temperature to obtain a block mass;
step (4), conveying the agglomerate to a position adjacent to a feed inlet of a vacuum reduction tank through a fifth conveyor belt 15, placing the agglomerate into the vacuum reduction tank 7, and carrying out reduction reaction under vacuum conditions, wherein the absolute pressure in the vacuum reduction tank is maintained at 20Pa in the embodiment; the temperature of the reduction reaction is 1100 ℃, and the reaction time is 15 hours; after the reduction reaction is finished, reducing slag is obtained in a reducing slag area 72, and a crystallization mixture is obtained by collecting in a crystallization area 71;
step (5), conveying the reducing slag into a molten pool 8 by a sixth conveyor belt 16, and enabling the reducing slag to be dissolved in 10wt% sodium hydroxide solution in the molten pool 8, wherein the mass ratio of the sodium hydroxide solution to the reducing slag is 10:1; the temperature of the dissolution reaction is 40 ℃, and the dissolution reaction time is 0.5h; after the dissolution reaction is finished, conveying the reaction mixed liquid into a filter through a pipeline 19 for filtering to obtain filter residues;
step (6), the filter residues are conveyed into a second calciner 10 through an eighth conveyor belt 18 and are calcined for 14 hours at the temperature of 1800 ℃, and magnesia-alumina spinel is obtained after the calcination is finished; the density of the magnesia-alumina spinel prepared in this example is 3.35g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The content of calcium oxide in the magnesia-alumina spinel was 0.15wt% and the content of silica was 0.20wt%.
Step (7), conveying the crystallization mixture to a refining furnace 20 for refining through a seventh conveying belt 17, wherein the refining temperature is 750 ℃, and the refining time is 1h; and after refining, obtaining magnesium liquid and refined slag, and casting the magnesium liquid to obtain the metal magnesium ingot.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While the obvious variations or modifications which are extended therefrom remain within the scope of the claims of this patent application.
Claims (10)
1. A method for preparing magnesium metal and magnesium aluminate spinel by aluminothermic reduction, which is characterized by comprising the following steps:
calcining magnesite and grinding to obtain magnesia powder;
uniformly mixing magnesia powder, aluminum powder, sodium fluoride and anhydrous magnesium chloride to obtain a mixed material;
step (3), pressing the mixed material into a block at room temperature;
step (4), placing the agglomerate into a vacuum reduction tank, and carrying out reduction reaction under vacuum condition; after the reduction reaction is finished, reducing slag is obtained in a reduction zone, and a crystallization mixture is obtained by collecting in a crystallizer;
step (5), placing the reducing slag in a sodium hydroxide solution for dissolution reaction, and filtering after the dissolution reaction is finished to obtain filter residues;
calcining the filter residue to obtain magnesia-alumina spinel;
and (7) placing the crystallization mixture into a refining furnace for refining, and obtaining magnesium liquid and refining slag after refining.
2. The method for preparing magnesium and magnesia-alumina spinel by aluminothermic reduction according to claim 1, wherein in the step (1), the calcining temperature of the magnesite is 800-1100 ℃ and the calcining time is 0.5-4 h.
3. The method for producing metallic magnesium and magnesium aluminate spinel according to claim 1, wherein in the step (2), the mass ratio of the magnesium oxide powder, the aluminum powder, the sodium fluoride and the anhydrous magnesium chloride is (2.0 to 5.0): 1 (0.03 to 0.20): 0.03 to 0.20.
4. The method for preparing magnesium metal and magnesium aluminate spinel by thermite reduction according to claim 1, wherein in the step (1), the particle size of the magnesia powder is less than or equal to 0.15mm; in the step (2), the particle size of the mixed materials is less than or equal to 0.15mm.
5. The method for preparing magnesium metal and magnesium aluminate spinel by thermite reduction according to claim 1, wherein in the step (3), the pressing pressure is 100-200 MPa.
6. The method for preparing magnesium metal and magnesium aluminate spinel by thermite reduction according to claim 1, wherein in the step (4), the absolute pressure under vacuum condition is 0.01 to 30Pa; the temperature of the reduction reaction is 1100-1300 ℃, and the reaction time is 9-16 h.
7. The method for preparing magnesium metal and magnesium aluminate spinel by aluminothermic reduction according to claim 1, wherein in step (5), the mass fraction of sodium hydroxide in the sodium hydroxide solution is 1 to 10wt%; the mass ratio of the sodium hydroxide solution to the reducing slag is (2-10): 1; the temperature of the dissolution reaction is 10-80 ℃, and the time of the dissolution reaction is 0.5-2 h.
8. The method for preparing magnesium and magnesia-alumina spinel by aluminothermic reduction according to claim 1, wherein in the step (6), the calcination temperature is 1700-1800 ℃ and the calcination time is 12-36 h; in the step (7), the refining temperature is 700-750 ℃ and the refining time is 0.5-2 h.
9. The method for preparing metal magnesium and magnesium aluminate spinel by aluminothermic reduction according to claim 1, wherein the preparation of metal magnesium and magnesium aluminate spinel by aluminothermic reduction is realized by a production system; the production system for preparing the magnesium metal and the magnesium aluminate spinel by aluminothermic reduction comprises a magnesium oxide production mechanism, a mixing mechanism, a forming mechanism, a reduction mechanism, a magnesium metal generating mechanism and a magnesium aluminate spinel generating mechanism; the magnesia discharge port of the magnesia production mechanism is communicated with the magnesia feed port of the mixing mechanism; the discharge port of the mixing mechanism is communicated with the feed port of the forming mechanism; the discharge port of the forming mechanism is adjacent to the feed port of the reduction mechanism; the crystal discharge port of the reduction mechanism is communicated with the feed port of the magnesium metal generating mechanism; and a reducing slag discharge port of the reducing mechanism is adjacent to a feed port of the magnesia-alumina spinel generating mechanism.
10. The method for preparing magnesium metal and magnesium aluminate spinel by thermite reduction according to claim 9, characterized in that the magnesia production mechanism comprises a crusher (1), a first calciner (2) and a pulverizer (3); the discharge port of the crusher (1) is communicated with the feed port of the first calciner (2) through a first conveyor belt (11); the discharge port of the first calciner (2) is communicated with the feed port of the pulverizer (3) through a second conveyor belt (12);
the mixing mechanism comprises a feeder (4) and a mixer (5); the discharge port of the feeder (4) is positioned right above the additive feed port of the mixer (5); the magnesia discharge port of the pulverizer (3) is communicated with the magnesia feed port of the mixer (5) through a third conveyor belt (13);
the forming mechanism is a powder forming machine (6); the discharge port of the mixer (5) is communicated with the feed port of the powder forming machine (6) through a fourth conveyor belt (14);
the reduction mechanism is a vacuum reduction tank (7), and the vacuum reduction tank (7) is provided with a crystallization area (71) and a reducing slag area (72); the powder forming machine (6) conveys the formed agglomerates by a fifth conveyor belt (15) to a feed opening adjacent to the vacuum reduction tank (7);
the magnesium metal generating mechanism comprises a refining furnace (20); the crystal discharge port of the crystallization zone (71) is communicated with the feed port of the refining furnace (20) through a seventh conveyor belt (17);
the magnesia-alumina spinel generating mechanism comprises a solution tank (8), a filter (9) and a second calciner (10); the fluid outlet end of the molten pool (8) is in fluid communication with the fluid inlet end of the filter (9) through a pipeline (19); the filter residue outlet end of the filter (9) is communicated with the feed inlet of the second calciner (10) through an eighth conveyor belt (18); the reducing slag outlet of the reducing slag zone (72) conveys reducing slag via a sixth conveyor (16) to a feed opening adjacent to the bath (8).
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| CN101942573A (en) * | 2010-08-13 | 2011-01-12 | 东北大学 | Method for preparing magnesium metal and magnesia-alumina spinel from active magnesium oxide and aluminum or aluminum alloy |
| CN101942572A (en) * | 2010-04-12 | 2011-01-12 | 东北大学 | Method for preparing magnesium metal with vacuum reduction by using material with MgO/CaO molar ratio of more than 1 as raw material |
| CN102864315A (en) * | 2012-09-13 | 2013-01-09 | 东北大学 | Vacuum magnesium making method using magnesium-silicon alloy as reducing agent |
| JP2014205133A (en) * | 2013-04-12 | 2014-10-30 | サム サム カンパニー, リミテッドSAM SAM Co., Ltd. | Slag treatment method for extraction of silica and magnesia |
| WO2018000587A1 (en) * | 2016-06-29 | 2018-01-04 | 狄保法 | Vacuum induction furnace, electric arc furnace vacuum magnesium refining system and magnesium refining method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101942572A (en) * | 2010-04-12 | 2011-01-12 | 东北大学 | Method for preparing magnesium metal with vacuum reduction by using material with MgO/CaO molar ratio of more than 1 as raw material |
| CN101942573A (en) * | 2010-08-13 | 2011-01-12 | 东北大学 | Method for preparing magnesium metal and magnesia-alumina spinel from active magnesium oxide and aluminum or aluminum alloy |
| CN102864315A (en) * | 2012-09-13 | 2013-01-09 | 东北大学 | Vacuum magnesium making method using magnesium-silicon alloy as reducing agent |
| JP2014205133A (en) * | 2013-04-12 | 2014-10-30 | サム サム カンパニー, リミテッドSAM SAM Co., Ltd. | Slag treatment method for extraction of silica and magnesia |
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