CN102230195A - Method for dipping special graphite anode for rare earth electrolysis - Google Patents
Method for dipping special graphite anode for rare earth electrolysis Download PDFInfo
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- CN102230195A CN102230195A CN2011102055946A CN201110205594A CN102230195A CN 102230195 A CN102230195 A CN 102230195A CN 2011102055946 A CN2011102055946 A CN 2011102055946A CN 201110205594 A CN201110205594 A CN 201110205594A CN 102230195 A CN102230195 A CN 102230195A
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Abstract
The invention provides a method for dipping special graphite anode for rare earth electrolysis. The method for dipping the graphite anode at the upper part of a melt comprises the following steps: placing the graphite anode to be dipped in a vacuum tank; introducing the prepared sodium polymetaphosphate liquid into the vacuum tank under the action of negative pressure until the dipped height of the anode is 10-30cm; and pressurizing so that dipping solution fully enters lattices of the anode for curing, and then drying. The method for dipping the graphite anode at the lower part of the melt comprises the following steps: soaking the graphite anode in saturated solution prepared from poly-hydroxyl fluoride; taking out and keeping the graphite anode standing under a natural state for a certain period of time; and then placing the graphite anode in an oven for removing hydroxyl in the poly-hydroxyl fluoride. The method provided by the invention has the advantages of effectively preventing oxygen and carbon dioxide generated on the graphite anode from entering the graphite anode during the electrolysis process so as not to cause looseness and falloff of the anode, thus prolonging average service life of the graphite anode by 12-24 hours.
Description
Technical field
The present invention relates to a kind of dipping rare earth electrolysis special graphite anodic method, belong to the thermochemistry field.
Background technology
Graphite at roasting and graphite when handling, there is the pitch of considerable part to overflow with volatile matter, and staying a large amount of pores, total porosity can be up to 20%～30%, the existence of a large amount of pores, will inevitably produce certain influence to the physicochemical property of goods, its volume density is descended, and physical strength reduces, and resistivity rises, oxidation rate is accelerated, the erosion resistance variation.When carrying out, electrolysis produces oxygen and carbonic acid gas, enter into graphite anode inside by pore, secondary reaction takes place under hot conditions, the degree of oxidation of anode surface is much bigger during than its electrolysis to the etch of graphite anode, it can make, and graphite anode is loose to come off, cause reduce the work-ing life of graphite anode, also influenced quality product simultaneously, reduced production efficiency.
The secondary chemical equation is as follows:
CO
2+ C (anode) → 2CO ↑
O
2+ C (anode) → CO
2↑
O
2+ 2C (anode) → 2CO ↑
Summary of the invention
The purpose of this invention is to provide a kind of dipping rare earth electrolysis special graphite anodic method that can effectively stop the graphite anode oxidation rate under the high temperature and can effectively stop anodic secondary chemical reaction.
Dipping method of the present invention is as follows:
Graphite anode is divided into the dipping of melt top graphite anode and the dipping of melt bottom graphite anode:
(1) melt top graphite anode dipping:
The preparation of steeping fluid:
Use H
2S handles the suspension of cupric pyrophosphate, behind the elimination cupric sulfide, solution is filtered evaporative crystallization, the tetra-sodium (H that obtains
4P
2O
7), be heated 300～340 ℃ again after, slowly be cooled to 110～130 ℃, be incubated 5～6 hours, obtain 500 units or higher PO
3 -The polymetaphosphate of the unit, (HPO that will obtain again
3)
nNaCO with content 99at%
3With (1.5～2.5): (1～2) molar ratio reacts under 320 ℃ condition, until CO
2Thoroughly emit, and continue to be warmed up to 600～680 ℃, be incubated after 5～6 hours,, promptly obtain 500 units or higher PO with time quenching to 0～5 that are no more than 30 minutes ℃
3 -The vitreum of the polymetaphosphate sodium salt of unit, being mixed with quality with water under 80～100 ℃ situation is 85.5～95.5% solution than concentration;
Dipping method:
Impregnated graphite anode is put into vacuum tank, vacuumized 1.5～3 hours with vacuum pump, vacuum tightness is-0.06 to-0.09MPa, the pore of graphite is fully opened, the steeping fluid for preparing is introduced vacuum tank under the effect of negative pressure, it highly is 10～30 centimetres that anodic is soaked, under pressure 3～6MPa condition, pressurize then, be 4.5～6.5 hours clamping time, steeping fluid fully entered in the anodic lattice solidify, its rate of body weight gain 〉=23～27%;
(2) melt bottom graphite anode dipping:
The preparation of steeping fluid:
Earlier LiOH being made into quality is 14.5～16.5% saturated solution than concentration, and hydrofluoric acid and equivalent butyleneglycol being made into quality is 8.5～12.5% dilute solution than concentration again, with the HF-H for preparing
2O-HO-CH
2-CH
2-CH
2-CH
2-OH system places the vessel of tetrafluoroethylene, under agitation adds the saturated solution of LiOH, makes its temperature remain on 4.5～6.5 ℃, and mol ratio reaches (0.8～1): (1.5～2) back ageing is no less than 20 hours, obtains poly-hydroxy fluorochemical Li[F (OH)
n], it is made into quality than concentration 60～70% saturated solutions;
Dipping method: it is that 80～110 ℃ poly-hydroxy fluorochemical is made into saturated solution and soaked 0.5～1.5 hour that the graphite anode that will enter melt part is put into temperature, it is entered in the graphite anode lattice solidifies, its rate of body weight gain is 13.5～16.5%, the graphite anode that dipping is good takes out, placement is no less than 20 hours under state of nature, the hydroxyl in many hydroxyls fluorochemical is dried by the fire in 120 ℃～150 ℃ baking ovens.
Advantage of the present invention is: the oxygen and the carbonic acid gas that have produced on the graphite anode when dipping by method of the present invention has effectively stoped electrolysis enter graphite anode inside, cause the loose of anode interior and come off, make on average prolong 12～24 hours the work-ing life of graphite anode.Improve the output capacity of metal, reduce the replacing number of times of graphite anode, reduce working strength of workers, save energy.
Description of drawings
Fig. 1 is the schema of melt of the present invention top graphite anode dipping;
Fig. 2 is the schema of melt of the present invention bottom graphite anode dipping.
Embodiment
The configuration of graphite anode steeping fluid and dipping method, graphite anode are divided into melt two portions dipping up and down:
One, (melt is with the top) of graphite anode dipping
(1) steeping fluid preparation:
1, uses H
2S handles the suspension of cupric pyrophosphate, behind the elimination cupric sulfide, solution is filtered evaporative crystallization, the tetra-sodium (H that obtains
4P
2O
7), be heated 300～340 ℃ again after, slowly be cooled to 110～130 ℃, be incubated 5～6 hours, obtain 500 units or higher PO
3 -The polymer metaphosphoric acid of unit.
(the HP O that n 〉=500 will obtain again
3)
nNaCO with content 99at%
3With (1.5～2.5): (1～2) molar ratio reacts under 320 ℃ condition, until CO
2Thoroughly emit, and continue to be warmed up to 600～680 ℃, be incubated after 5～6 hours, quenching to 0～5 ℃ promptly obtain 500 units or higher PO
3 -The vitreum of the polymetaphosphate sodium salt of unit, being mixed with quality with water under 80～100 ℃ situation is 85.5～95.5% solution than concentration.
2, work as PO
3 -Unit is less than 500 or when lower, its antioxidant property reduces greatly.
3, the HP O in preparation solution
3Content when surpassing 3～5at%, it is unfavorable then the rare earth oxide fused salt electrolysis process to be produced the graphite anode of rare earth metal, has accelerated anodic corrodibility (being different from the electrolysis of chloride).
(2) dipping method:
1, graphite anode is put into vacuum tank, with vacuum pump vacuumize 1.5～3 hours (vacuum tightness for-0.06 to-0.09MPa), the pore of graphite is fully opened;
2, the liquid for preparing is introduced vacuum tank under the effect of negative pressure, make anodic be soaked highly about 10～30 centimetres;
3, under pressure 3～6MPa condition, be about 4.5～5.5 hours clamping time, make steeping fluid fully enter in the anodic lattice its rate of body weight gain 〉=23～27%.
The G-----rate of body weight gain
W
0--weight Kg before----dipping
W
1------dipping back weight Kg
Two, (melt is with the lower section) of graphite anode dipping
(1) steeping fluid preparation:
Earlier LiOH being made into quality is 14.5～16.5% saturated solution than concentration, the butyleneglycol of hydrofluoric acid and equivalent is made into 8.5～12.5% dilute solution, with the HF-H for preparing again
2O-HO-CH
2-CH
2-CH
2-CH
2-OH system places the vessel of tetrafluoroethylene, under agitation slowly adds the saturated solution of LiOH, makes its temperature remain on 4.5～6.5 ℃, and mol ratio reaches (0.8～1): (1.5～2) back ageing 24 hours obtains poly-hydroxy fluorochemical Li[F (OH)
n], it is made into quality than concentration 60～70% saturated solutions.
(2) dipping method:
1, to put into temperature be that 80～110 ℃ poly-hydroxy fluorochemical is made into saturated solution and soaked 0.5～1.5 hour to the graphite anode that will enter melt part, and its rate of body weight gain is 13.5～16.5%.
2, will flood good graphite anode and take out, and transfer to deposit in state of nature and placed 24 hours.
3, in 120 ℃～150 ℃ baking ovens, the hydroxyl in many hydroxyls fluorochemical is dried by the fire.
Because steeping fluid fully soaks the pore of full graphite anode, enter in the lattice of graphite anode and solidify.In the rare earth oxide electrolytic process, oxygen under high temperature and carbonic acid gas and graphite anode are done the time spent, it can effectively stop oxygen and the carbonic acid gas that produces on anode, play shielding effect, reduced the oxidation rate of graphite anode, improved the work-ing life of graphite anode greatly, can make graphite anode on average prolong 12～24 hours.
The vitreum of the polymetaphosphate sodium salt on impregnated graphite anode fused salt top is in molten state, gradually with P in electrolytic process
2O
5Form overflow, and do not pollute melt and metal in the electrolyzer.And toast in 120 ℃～150 ℃ baking ovens impregnated graphite anode fused salt lower section, and the hydroxyl in many hydroxyls fluorochemical is dried by the fire with the form of water, can not influence electrolytical composition.
Below introducing the present invention produces the specific examples of testing in the rare earth metal production in the rare earth electrolytic process and is described in detail.
Case 1, on praseodymium neodymium Metal Production, test, according to the selected electrolytic furnace of practical situation, the graphite anode of a slice through dipping is installed, its excess-three sheet uses common anode to test, show that through the test-results statistics common graphite anode was changed once in 12 hours, impregnated graphite anode was changed once in 30 hours, get the fused salt analysis in this process of the test, the result shows the composition that does not have steeping fluid in the fused salt.For verifying this result, we put into 2 impregnated graphite anodes in an electrolytic furnace, test according to adjacent, symmetrical manner, and effect is the same with the impregnated graphite anode result of monolithic.Four anodes all change impregnated graphite anode into the most at last, and about the many 120Kg of its praseodymium neodymium alloy rate ratio common graphite anode, product detects carbon content by analysis and decreases, and does not have the element of steeping fluid in the product.
Test in case 2, the battery grade mischmetal production, a slice is installed on electrolytic furnace flooded anode, its excess-three sheet uses common anode to test, and finds that in test it is more serious that common anode is washed away by fused salt, anode strip was remembered to change about 10 hours, and impregnated graphite anode does not have considerable change, and the impregnated graphite anode replacement cycle prolongs, and changes once in 34 hours, in process of the test, fused salt is detected, do not detect the relevant ions of steeping fluid in the fused salt.After analysis of experiments, in an electrolytic furnace, put four impregnated graphite anodes simultaneously, analyze by statistics, not only improved anode work-ing life, more than produce battery grade mischmetal 110Kg, yield improves two percentage points.
Case 3, on the Dy-Fe alloy production line, test
Test method and case 1 are similar, at electrolytic furnace the graphite anode of a slice through dipping is installed earlier, its excess-three sheet uses common anode to test, after in process of the test, finding 14 hours, the erosion of fused salt and the vestige that washes away are arranged at impregnated graphite anode top, common anode was changed at 10 hours, impregnated graphite anode is after 20 hours, be subjected to the erosion of fused salt more obvious with the vestige that washes away, the anode of this moment can also continue to use, 26 as a child bottom anode consume, top anode loss is also relatively more serious, can not continue to use.Use the graphite anode of four dippings to produce Dy-Fe alloy rate ratio common anode output increase 70--90Kg.In process of the test the Dy-Fe alloy of fused salt and production is inspected by random samples, analytical results is the same with the Dy-Fe alloy result that common anode is produced, and fused salt and Dy-Fe alloy do not have contaminated.
My company is on the bases of a large amount of tests, and the graphite anode of dipping is applied on praseodymium neodymium metal, Dy-Fe alloy, battery grade mischmetal and lanthanoid metal, neodymium metal production line.
Claims (1)
1. one kind floods rare earth electrolysis special graphite anodic method, and it is characterized in that: dipping method of the present invention is as follows:
Graphite anode is divided into the dipping of melt top graphite anode and the dipping of melt bottom graphite anode:
(1) melt top graphite anode dipping:
The preparation of steeping fluid:
Use H
2S handles the suspension of cupric pyrophosphate, behind the elimination cupric sulfide, solution is filtered evaporative crystallization, the tetra-sodium (H that obtains
4P
2O
7), be heated 300～340 ℃ again after, slowly be cooled to 110～130 ℃, be incubated 5～6 hours, obtain 500 units or higher PO
3 -The polymetaphosphate of unit, (the HP O that will obtain again
3)
nNaCO with content 99at%
3With (1.5～2.5): (1～2) molar ratio reacts under 320 ℃ condition, until CO
2Thoroughly emit, and continue to be warmed up to 600～680 ℃, be incubated after 5～6 hours,, promptly obtain 500 units or higher PO with time quenching to 0～5 that are no more than 30 minutes ℃
3 -The vitreum of the polymetaphosphate sodium salt of unit, being mixed with quality with water under 80～100 ℃ situation is 85.5～95.5% solution than concentration;
Dipping method:
Impregnated graphite anode is put into vacuum tank, vacuumized 1.5～3 hours with vacuum pump, vacuum tightness is-0.06 to-0.09MPa, the pore of graphite is fully opened, the steeping fluid for preparing is introduced vacuum tank under the effect of negative pressure, it highly is 10～30 centimetres that anodic is soaked, under pressure 3～6MPa condition, pressurize then, be 4.5～6.5 hours clamping time, steeping fluid fully entered in the anodic lattice solidify, its rate of body weight gain 〉=23～27%;
(2) melt bottom graphite anode dipping:
The preparation of steeping fluid:
Earlier LiOH being made into quality is 14.5～16.5% saturated solution than concentration, and hydrofluoric acid and equivalent butyleneglycol being made into quality is 8.5～12.5% dilute solution than concentration again, with the HF-H for preparing
2O-HO-CH
2-CH
2-CH
2-CH
2-OH system places the vessel of tetrafluoroethylene, under agitation adds the saturated solution of LiOH, makes its temperature remain on 4.5～6.5 ℃, and mol ratio reaches (0.8～1): (1.5～2) back ageing is no less than 20 hours, obtains poly-hydroxy fluorochemical Li[F (OH)
n], it is made into quality than concentration 60～70% saturated solutions;
Dipping method: it is that 80～110 ℃ poly-hydroxy fluorochemical is made into saturated solution and soaked 0.5～1.5 hour that the graphite anode that will enter melt part is put into temperature, it is entered in the graphite anode lattice solidifies, its rate of body weight gain is 13.5～16.5%, the graphite anode that dipping is good takes out, placement is no less than 20 hours under state of nature, the hydroxyl in many hydroxyls fluorochemical is dried by the fire in 120 ℃～150 ℃ baking ovens.
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|---|---|---|---|
| CN2011102055946A CN102230195A (en) | 2011-07-15 | 2011-07-15 | Method for dipping special graphite anode for rare earth electrolysis |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112376081A (en) * | 2020-11-12 | 2021-02-19 | 奉新赣锋锂业有限公司 | Graphite anode dipping device for molten salt electrolysis of metal lithium and dipping method thereof |
| CN114293213A (en) * | 2021-12-29 | 2022-04-08 | 董凯 | Electrochemical cell reaction tank |
Citations (4)
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|---|---|---|---|---|
| JPH03140491A (en) * | 1989-10-27 | 1991-06-14 | Shin Etsu Chem Co Ltd | Rare earth metal and production of rare earth alloy |
| CN1763256A (en) * | 2005-09-30 | 2006-04-26 | 包头稀土研究院 | Graphite anode anti-oxidation coating for producing rare earth metal |
| CN1865514A (en) * | 2006-04-09 | 2006-11-22 | 包头市玺骏稀土有限责任公司 | Process for preparing cell-class mischmetal by fused salt electrolysis process and device therefor |
| CN101985764A (en) * | 2010-10-08 | 2011-03-16 | 九台市科工碳业有限责任公司 | Antioxidation processing method of graphite anode for preparing calcium by electrolysis |
-
2011
- 2011-07-15 CN CN2011102055946A patent/CN102230195A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03140491A (en) * | 1989-10-27 | 1991-06-14 | Shin Etsu Chem Co Ltd | Rare earth metal and production of rare earth alloy |
| CN1763256A (en) * | 2005-09-30 | 2006-04-26 | 包头稀土研究院 | Graphite anode anti-oxidation coating for producing rare earth metal |
| CN1865514A (en) * | 2006-04-09 | 2006-11-22 | 包头市玺骏稀土有限责任公司 | Process for preparing cell-class mischmetal by fused salt electrolysis process and device therefor |
| CN101985764A (en) * | 2010-10-08 | 2011-03-16 | 九台市科工碳业有限责任公司 | Antioxidation processing method of graphite anode for preparing calcium by electrolysis |
Non-Patent Citations (2)
| Title |
|---|
| 《天津冶金》 20031230 曾桂生等 "钙熔盐电解石墨阳极破损及防护研究" 第27-29，56-57页 1 , 第6期 * |
| 曾桂生等: ""钙熔盐电解石墨阳极破损及防护研究"", 《天津冶金》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112376081A (en) * | 2020-11-12 | 2021-02-19 | 奉新赣锋锂业有限公司 | Graphite anode dipping device for molten salt electrolysis of metal lithium and dipping method thereof |
| CN114293213A (en) * | 2021-12-29 | 2022-04-08 | 董凯 | Electrochemical cell reaction tank |
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Application publication date: 20111102 |