CN106283112A - The electrochemical purification method of fused salt - Google Patents
The electrochemical purification method of fused salt Download PDFInfo
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- CN106283112A CN106283112A CN201510237627.3A CN201510237627A CN106283112A CN 106283112 A CN106283112 A CN 106283112A CN 201510237627 A CN201510237627 A CN 201510237627A CN 106283112 A CN106283112 A CN 106283112A
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Abstract
The invention discloses the electrochemical purification method of fused salt.The invention provides a kind of electrochemical purification method of fused salt, step (1): use three electrodes: negative electrode, anode and reference electrode, determine melted fused salt to be clean electrochemical window and in melten salt electriochemistry window to be clean the electrochemical reduction spike potential of impurity；With graphite as anode material, with inert metal as cathode material, described inert metal is the metal not reacted with fused salt to be clean；Step (2): to bear than the electrochemical reduction spike potential of the impurity determined in step (1), to be electrolysed more than or equal to the voltage of the electrochemical window of fused salt to be clean.The method of the present invention, not only it is suitable for Chlorides molten salts, it is also suitable fluoride smelt salt, single experiment operation i.e. reaches to purify metal cation impurity and oxo-anions impurity in removing fused salt simultaneously, and being not required to add other chemical reagent at molten salt system, purification process will not produce secondary pollution to fused salt.
Description
Technical field
The present invention relates to the electrochemical purification method of fused salt.
Background technology
Many productions of rare earth metal in commercial production and scientific research, the refine of refractory metal, with
And plating and plating etc. are required to use all kinds of fuse salt as electrolyte.High-temperature fuel cell and atomic energy
Industry is also commonly used fuse salt as conducting medium or solvent.
During the use of fused-salt medium, generally high temperature, corrosive environment, in fused salt, trace is miscellaneous
The existence of matter is likely to affect experimental result or production process, must carry out fused salt only the most before use
Change processes.Electrolyte itself and application thereof is depended in requirement to fused salt degree of purification.In application water absorption
Strong salt and when carrying out the research of electrode process the high purification of solvent seem particular importance.In this situation
The methods such as the most available vacuum dehydration, active gases process and active metal dehydration.These methods general and
Speech needs exacting terms and equipment, and requirement to using material is higher, to institute in processing procedure
The chemical raw material used and the consumption of the energy are bigger；Especially when the impurity in fused salt be relatively active metal from
The period of the day from 11 p.m. to 1 a.m, now suitable by conventional processing method, or the effect purified is poor.Additionally,
Also have employing two-probe method to carry out electrolytic cleaning fused salt, the accurate current potential that two-probe method reacts for anode and cathode without
Method accurately controls, and especially in the occasion having high-quality to require fused salt, is extremely difficult to preferable remove impurity effect
Really.In the case, the purification pretreatment to fused salt needs to consider especially.Therefore, technological process is found
Short, simple to operation, material and energy resource consumption are few, and good purification is suitable for large-scale use
The purifying treatment method of fused salt is to be badly in need of at present solving the technical problem that.
Summary of the invention
The technical problem to be solved is to overcome the purification method pair of fused salt in prior art
Appointed condition requires that current potential harsh, for anode and cathode reaction cannot accurately control, especially to fused salt
There is the occasion that high-quality requires, be extremely difficult to the defects such as preferable impurity-eliminating effect and provide a kind of fused salt
Electrochemical purification method, the electrochemical process for treating of the present invention, it is to avoid introduce chemical raw material, technological process
Short, simple to operation, material and energy resource consumption are few, and anode and cathode can be electrolysed removing impurity simultaneously, purify
Effective, it is suitable for large-scale use.
The invention provides a kind of electrochemical purification method of fused salt, it comprises the following steps:
Step (1): use three electrodes: negative electrode, anode and reference electrode, determines melted to be clean
The electrochemical window of fused salt and in melten salt electriochemistry window to be clean the electrochemical reduction spike potential of impurity；
With graphite as anode material, with inert metal as cathode material, described inert metal is not with to be clean
The metal that fused salt reacts；
Step (2): bear with the electrochemical reduction spike potential than the impurity determined in step (1), be more than
Or be electrolysed equal to the voltage of the electrochemical window of fused salt to be clean.
In the present invention, described fused salt method for cleaning impurity is preferably comprised step (3): checked for impurities
Content, requiring if reaching to purify, purifying and terminating, the fused salt after being purified；If not up to purifying requirement
Then repeating step (2) until reaching to purify requirement, during repetition, preferably means are replacing cathode material,
Anode material and reference electrode can be changed or be changed without.
In step of the present invention (1), described fused salt to be clean can be molten chloride and/or fluorine
Compound fused salt, described molten chloride can be lithium chloride, potassium chloride, sodium chloride, magnesium chloride and chlorination
One or more in calcium；Described fluoride molten salt can be in sodium fluoride, lithium fluoride and potassium fluoride
Kind or multiple, or the mixture of one or more in sodium fluoride, lithium fluoride and potassium fluoride and calcium fluoride.
Step of the present invention (1) is carried out the most under anaerobic.
In step of the present invention (1), the impurity cationic contained in described fused salt to be clean can
Think metal cation, the described metal in metal cation can be Fe, Cr, Ni, Cu, Pb,
One or more in Al, Zn and Zr etc.；Described impurity anions can be O2-Deng.Described
In fused salt to be clean, the weight/mass percentage composition of impurity anions is preferably no greater than 5%, is more preferably not more than
1%；Described weight/mass percentage composition refers to that the quality of anion accounts for the percentage of fused salt gross mass to be clean and contains
Amount；In described fused salt to be clean, the weight/mass percentage composition of impurity cationic is preferably no greater than 10%, more
It is not more than 3% goodly；Described weight/mass percentage composition refers to that the quality of cation accounts for the total matter of fused salt to be clean
The percentage composition of amount.
In step of the present invention (1), the fusing point of described fused salt to be clean is not higher than reference electrode
Effectively use temperature, preferably less than 1000 DEG C.
In step of the present invention (1), described melted fused salt to be clean can be by be clean molten
Salt is melted to be obtained, and described melting can realize by the way of heating.
In step of the present invention (1), described fused salt to be clean can such be grasped in the art
Melting in the conventional vessel made, described conventional vessel can select according to the fusing point of fused salt to be clean
Select；Preferably crucible, described crucible is preferably graphite crucible or corundum crucible.
In step of the present invention (1), described melted temperature is more than or equal to fused salt to be clean
Fusing point.
In step of the present invention (1), described inert metal is preferably in platinum, molybdenum and tungsten
One or more.
In step of the present invention (1), described reference electrode can be such electrolysis in this area
The conventional reference electrode of operation, can be typically metal reference electrode, chloride system reference electrode or fluorine
Salt system reference electrode；Described metal reference electrode is preferably platinum electrode；Described chloride system is
Refer to the salt that metal ion is formed with chloride ion；Described fluoric-salt system refers to that metal ion is formed with fluorion
Salt；Described metal ion can be the common metal ion in this area, preferably Ag+Or
Ni2+；Described chloride system is preferably silver chloride；Described fluoric-salt system is preferably Nickel difluoride.
In step of the present invention (1), described method of testing can be test electrification in this area
Learn window and the traditional test methods of electrochemical reduction spike potential, preferably cyclic voltammetry.Work as employing
When cyclic voltammetry test electrochemical window and electrochemical reduction spike potential, scanning voltage is preferably
The electrochemical window (nagative potential) of 0V～fused salt to be clean, scanning speed is preferably 0.01V/s～1V/s,
It is more preferably 0.1V/s.
In step of the present invention (2), the electrode potential used during described electrolysis is than the electricity of impurity
Electrode potential is born, but does not include the situation identical with the electrode potential of impurity, preferably than electrode potential
The electrode potential of negative impurity is more negative, is more preferably that the electrode potential of the impurity more negative than electrode potential is born
100mV～500mV.The electrode potential used during described electrolysis is more than or equal to the electricity of fused salt to be clean
Chemistry window (nagative potential).
In step of the present invention (2), the time of described electrolysis is preferably 1 hour～20 little
Time, it is more preferably 4 hours～8 hours.
In step of the present invention (3), the method for described checked for impurities content can be this area
In such detection conventional method, preferably use online cyclic voltammetry scanning impurity electric current density,
Or off-line sampling mode, utilizes chemical method checked for impurities concentration.
In step of the present invention (3), the reduction peak current of impurity in the described fused salt after purification
Density is generally less than 30mA/cm2, preferably less than 10mA/cm2～30mA/cm2, more preferably less than
10mA/cm2。
Without prejudice to the field on the basis of common sense, above-mentioned each optimum condition, can combination in any, obtain this
Invent each preferred embodiments.
Agents useful for same of the present invention and raw material are the most commercially.
The most progressive effect of the present invention is:
1. the present invention uses the method for electrochemistry that fused salt is purified, in fused salt, introduce it avoiding
Its chemical composition and reach while causing secondary pollution to purify purpose.
2. the electrode material employed in the present invention is respectively inert metal and graphite, and therefore the present invention is not only
The reduction process that can utilize in electrolytic process on negative electrode remove metal cation impurity in fused salt (Fe,
One or more in Cr, Ni, Cu, Pb, Al, Zn and Zr), it is also possible to utilize the oxidation on anode
Process removes the anionic impurities such as the oxonium ion in fused salt.
3. the fused salt container and the electrode material that use due to the present invention can preferably tolerate invading of fused salt
Erosion, is therefore not only applicable to Chlorides molten salts, is applied equally to the stronger fluoride of corrosivity and melts
Salt system.
4. present invention process flow process is short, simple to operation, and material and energy resource consumption are few, is suitable for advising greatly
Mould uses.
Accompanying drawing explanation
Fig. 1 is the cyclic voltammetry curve figure before and after the FLINAK melten salt electriochemistry method purification of embodiment 1.
Detailed description of the invention
Further illustrate the present invention below by the mode of embodiment, but the most therefore limit the present invention to
Among described scope of embodiments.The experimental technique of unreceipted actual conditions in the following example, according to often
Rule method and condition, or select according to catalogue.
Embodiment 1: fused salt kind to be clean be LiF-NaF-KF eutectic eutectic fused salt (FLINAK,
Fusing point 454 DEG C, boiling point 1570 DEG C), proportioning is 46.5:11.5:42 (mol%).System purified treatment temperature
Degree is 550 DEG C, and in fused salt to be clean, dominant cation impurity is the metal ions such as ferrum, nickel, chromium, aluminum,
The total weight/mass percentage composition of impurity cationic is not more than 1%.
Melten salt electriochemistry purification method, mainly comprises the steps that
(1) fused salt to be clean is placed in cylindrical graphite crucible.Use high-density graphite material, molten
Salt useful load is liquid height about 2cm time melted.
(2) in crucible and fused salt are placed in airtight molten salt electrochemical experimental apparatus, (this device is by the Chinese Academy of Sciences
Shanghai Applied Physics Research Institute, according to application number: the Chinese patent report of 201320023881.X
Prepared by method), it is isolated with outside air environment.
(3) using burner hearth evacuation and be passed through argon as protection gas.Burner hearth is heated to 350 DEG C also
It is incubated 3 hours.One air inlet and gas outlet are set, persistently will use inert gas purification device (purity
7N) protection gas after purification is passed through and discharges, and the gas in fused salt solid to be clean and moisture is carried out
Go.
(4) burner hearth is warming up to 550 DEG C, and is incubated and within more than 3 hours, guarantees that fused salt to be clean all melts.
(5) with graphite as anode material, with metal platinum as cathode material, with metal platinum as reference electrode,
First with measuring instruments such as electrochemical workstations, melted fused salt to be clean is circulated voltammetry to sweep
Retouch, determine that the electrochemical window current potential of melted fused salt to be clean is-1.95V, major impurity reduction peak electricity
Position is-1.6V and about-1.0V, and sweep speed is 0.1v/s.
(6) use the instrument such as electrochemical workstation or potentiostat, with the material in step (5) be
Cathode and anode and reference electrode, the preelectrolysis impurity and purification carrying out fused salt to be clean process.In processing procedure
Selecting potentiostatic deposition pattern, electrolytic potential is set as-1.8V.Electrolysis time 5 hours.In the process
Melted fused salt to be clean is carried out continuously stirred, improves treatment effeciency.
(7) after step (6) terminates, change cathode electrode material, reuse in step (5)
Mode, the electrochemical window of the fused salt to be clean that detection is melted and main impurity electrochemical reduction peak electricity
Position, position and electric current density size, as shown in Figure 1.Use at the detection electrolysis impurity and purification of ICP-AES method
Concentration of metallic impurities in fused salt before and after reason, as shown in table 1.Various concentration of metallic impurities after purified treatment
Can reduce about two orders of magnitude, be below 100ppm, test result is shown in Table 1.The FLINAK of embodiment 1
Cyclic voltammetry curve figure before and after the purification of melten salt electriochemistry method is as shown in Figure 1.
(8), after impurity and purification process terminates, the fused salt after purifying carries out follow-up use.
In table 1:FLINAK fused salt, concentration of metallic impurities measures (ICP-AES)
| Element kind | Content (ppm) before electrolysis | Content (ppm) after electrolysis |
| Fe | 2850 | 95 |
| Cr | 740 | 11 |
| Ni | 340 | 4 |
Embodiment 2: fused salt kind to be clean be LiF-NaF-KF eutectic eutectic fused salt (FLINAK,
Fusing point 454 DEG C, boiling point 1570 DEG C), proportioning is 46.5:11.5:42 (mol%).System purified treatment temperature
Degree is about 550 DEG C, and in fused salt to be clean, dominant cation impurity is the metal ions such as ferrum, nickel, chromium, aluminum,
Main Anions impurity is oxonium ion.Wherein, the total weight/mass percentage composition of cation impurity less than 2%,
The total weight/mass percentage composition of anionic impurity is less than 1%.
Melten salt electriochemistry purification method, mainly comprises the steps that
(1) fused salt to be clean is placed in cylindrical graphite crucible.Use high-density graphite material, molten
Salt useful load is liquid height about 2cm time melted.
(2) in crucible and fused salt are placed in airtight molten salt electrochemical experimental apparatus, (this device is by the Chinese Academy of Sciences
Shanghai Applied Physics Research Institute, according to application number: the Chinese patent report of 201320023881.X
Prepared by method), it is isolated with outside air environment.
(3) using burner hearth evacuation and be passed through argon as protection gas.Burner hearth is heated to 350 DEG C also
It is incubated 3 hours.One air inlet and gas outlet are set, persistently will use inert gas purification device (7N)
Protection gas after purification is passed through and discharges, and the gas in fused salt solid to be clean and moisture is carried away.
(4) burner hearth is warming up to 550 DEG C, and is incubated and within more than 3 hours, guarantees that fused salt to be clean all melts.
(5) with graphite as anode material, with metal molybdenum as cathode material, with NiF2/ Ni is reference electrode,
First with measuring instruments such as electrochemical workstations, melted fused salt to be clean is circulated voltammetry to sweep
Retouch, determine that melted melten salt electriochemistry window current potential to be clean is-2.11V, major impurity reduction peak current potential
For about-1.3V, sweep speed is 0.1v/s.
(6) use the instrument such as electrochemical workstation or potentiostat, with the material in step (5) be
Anode and cathode and reference electrode, carry out the preelectrolysis impurity and purification process of the fused salt to be clean melted.Processed
Selecting potentiostatic deposition pattern in journey, electrolytic potential is set as-1.75V, and electrolysis time is 8 hours.?
During this, melted fused salt to be clean is carried out continuously stirred, improve treatment effeciency.
(7) after step (6) terminates, part fused salt is taken out, before utilizing oxygen content tester to processing
Oxygen content in rear fused salt detects, as shown in table 2.After purified treatment, oxygen content can be less than 200ppm.
Concentration of metallic impurities in fused salt before and after using the detection electrolysis impurity and purification of ICP-AES method to process, such as table 3
Shown in.After purified treatment, various concentration of metallic impurities can reduce about two orders of magnitude, is below 100ppm,
Test result is shown in Table 3.
(8) after impurity and purification process terminates, stopping heating, the fused salt after purifying is after cooled and solidified
Take out standby.
Determination of oxygen content in table 2:FLINAK fused salt
| Batch | Oxygen content (ppm) before electrolysis | Oxygen content (ppm) after electrolysis |
| 1 | 3000 | 199 |
| 2 | 600 | 123 |
In table 3:FLINAK fused salt, concentration of metallic impurities measures (ICP-AES)
| Element kind | Content (ppm) before electrolysis | Content (ppm) after electrolysis |
| Fe | 3400 | 81 |
| Cr | 580 | 10 |
| Ni | 250 | 3 |
Embodiment 3: fused salt kind to be clean is the eutectic eutectic fused salt (fusing point 355 DEG C) of LiCl-KCl,
Proportioning is 59:41 (mol%).System purified treatment temperature is about 450 DEG C, main sun in fused salt to be clean
Ionic impurity is the metal ions such as ferrum, nickel, chromium, aluminum, and the total weight/mass percentage composition of impurity cationic does not surpasses
Cross 3%.
Melten salt electriochemistry purification method, mainly comprises the steps that
(1) fused salt is placed in cylindrical corundum crucible.Fused salt useful load is for liquid height time melted about
2cm。
(2) in crucible and fused salt are placed in airtight molten salt electrochemical experimental apparatus, (this device is by the Chinese Academy of Sciences
Shanghai Applied Physics Research Institute, according to application number: the Chinese patent report of 201320023881.X
Prepared by method), it is isolated with outside air environment.
(3) using burner hearth evacuation and be passed through argon as protection gas.Burner hearth is heated to 300 DEG C also
It is incubated 23 hours.One air inlet and gas outlet are set, persistently will use inert gas purification device (7N)
Protection gas after purification is passed through and discharges, and the gas in fused salt solid to be clean and moisture is carried away.
(4) burner hearth is warming up to 450 DEG C, and is incubated and within more than 3 hours, guarantees that fused salt to be clean all melts.
(5) with graphite as anode material, with tungsten as cathode material, with AgCl/Ag as reference electrode,
First with measuring instruments such as electrochemical workstations, melted fused salt to be clean is circulated voltammetry to sweep
Retouch, determine that the electrochemical window current potential of melted fused salt to be clean is-2.40V, major impurity reduction peak electricity
Position is about-1.6V, and sweep speed is 0.1v/s.
(6) use the instrument such as electrochemical workstation or potentiostat, with the material in step (5) be
Anode and cathode and reference electrode, carry out the preelectrolysis impurity and purification process of the fused salt to be clean melted.Processed
Selecting potentiostatic deposition pattern in journey, electrolytic potential is set as-1.8V.Electrolysis time 5 hours.In this mistake
Melted fused salt to be clean is carried out continuously stirred by journey, improves treatment effeciency.
(7) after impurity and purification process terminates, stopping heating, the fused salt after purifying is after cooled and solidified
Take out standby.After purified treatment, various concentration of metallic impurities can reduce about two orders of magnitude, is below 100
ppm；After purified treatment, the concentration of oxygen is less than 200ppm.
Embodiment 4: fused salt kind to be clean is MgCl2-NaCl-CaCl2The eutectic eutectic fused salt of-KCl
(fusing point 571 DEG C), proportioning is 10:42.85:40:7.15 (wt%).System purified treatment temperature is about 700 DEG C,
In fused salt to be clean, dominant cation impurity is the metal ions such as ferrum, nickel, chromium, aluminum, and impurity cationic is total
Weight/mass percentage composition less than 2%.
Melten salt electriochemistry purification method, mainly comprises the steps that
(1) fused salt is placed in cylindrical corundum crucible.Fused salt useful load is for liquid height time melted about
2cm。
(2) in crucible and fused salt are placed in airtight molten salt electrochemical experimental apparatus, (this device is by the Chinese Academy of Sciences
Shanghai Applied Physics Research Institute, according to application number: the Chinese patent report of 201320023881.X
Prepared by method), it is isolated with outside air environment.
(3) using burner hearth evacuation and be passed through argon as protection gas.Burner hearth is heated to 300 DEG C also
It is incubated 3 hours.One air inlet and gas outlet are set, persistently will use inert gas purification device (7N)
Protection gas after purification is passed through and discharges, and the gas in fused salt solid to be clean and moisture is carried away.
(4) burner hearth is warming up to 700 DEG C, and is incubated and within more than 3 hours, guarantees that fused salt to be clean all melts.
(5) with graphite as anode material, with metal molybdenum as cathode material, with AgCl/Ag as reference electrode,
First with measuring instruments such as electrochemical workstations, melted fused salt to be clean is circulated voltammetry to sweep
Retouch, determine that the electrochemical window current potential of melted fused salt to be clean is-1.53V, major impurity reduction peak electricity
Position is about-1.1V, and sweep speed is 0.1v/s.
(6) use the instrument such as electrochemical workstation or potentiostat, with the material in step (5) be
Anode and cathode and reference electrode, carry out the preelectrolysis impurity and purification process of the fused salt to be clean melted.Processed
Selecting potentiostatic deposition pattern in journey, electrolytic potential is set as-1.3V.Electrolysis time 5 hours.In this mistake
Melted fused salt to be clean is carried out continuously stirred by journey, improves treatment effeciency.
(7) after impurity and purification process terminates, stopping heating, the fused salt after purifying is after cooled and solidified
Take out standby.After purified treatment, various concentration of metallic impurities can reduce about two orders of magnitude, is below 100
ppm；After purified treatment, the concentration of oxygen is less than 200ppm.
Embodiment 5: fused salt kind to be clean is LiF-CaF2Eutectic eutectic fused salt (fusing point 760 DEG C),
Proportioning is 77:23 (mol%).System purified treatment temperature is 850 DEG C, in fused salt to be clean main sun from
Sub-impurity is the metal ions such as ferrum, nickel, chromium, aluminum, and the total weight/mass percentage composition of impurity cationic is less than
1%.
Melten salt electriochemistry purification method, mainly comprises the steps that
(1) fused salt to be clean is placed in cylindrical graphite crucible.Use high-density graphite material, molten
Salt useful load is liquid height about 2cm time melted.
(2) in crucible and fused salt are placed in airtight molten salt electrochemical experimental apparatus, (this device is by the Chinese Academy of Sciences
Shanghai Applied Physics Research Institute, according to application number: the Chinese patent report of 201320023881.X
Prepared by method), it is isolated with outside air environment.
(3) using burner hearth evacuation and be passed through argon as protection gas.Burner hearth is heated to 350 DEG C also
It is incubated 3 hours.One air inlet and gas outlet are set, persistently will use inert gas purification device (purity
7N) protection gas after purification is passed through and discharges, and the gas in fused salt solid to be clean and moisture is carried out
Go.
(4) burner hearth is warming up to 850 DEG C, and is incubated and within more than 3 hours, guarantees that fused salt to be clean all melts.
(5) with graphite as anode material, with metal platinum as cathode material, with metal platinum as reference electrode,
First with measuring instruments such as electrochemical workstations, melted fused salt to be clean is circulated voltammetry to sweep
Retouch, determine that the electrochemical window current potential of melted fused salt to be clean is-2.10V, major impurity reduction peak electricity
Position is-1.5V and about-0.9V, and sweep speed is 0.1v/s.
(6) use the instrument such as electrochemical workstation or potentiostat, with the material in step (5) be
Cathode and anode and reference electrode, carry out the preelectrolysis impurity and purification process of the fused salt to be clean melted.Process
During select potentiostatic deposition pattern, electrolytic potential is set as-1.75V.Electrolysis time 5 hours.?
During this, melted fused salt to be clean is carried out continuously stirred, improve treatment effeciency.
(7), after impurity and purification process terminates, the fused salt after purifying carries out follow-up use.Purified treatment
Rear various concentration of metallic impurities can reduce about two orders of magnitude, is below 100ppm；Oxygen after purified treatment
Concentration less than 200ppm.
Comparative example: fused salt kind to be clean is the eutectic eutectic fused salt of LiF-NaF-KF
(FLINAK, fusing point 454 DEG C, boiling point 1570 DEG C), proportioning is 46.5:11.5:42 (mol%).Body
Be that purified treatment temperature is about 550 DEG C, in fused salt to be clean dominant cation impurity be ferrum, nickel, chromium,
The metal ions such as aluminum, the total weight/mass percentage composition of impurity cationic is less than 1%.
Melten salt electriochemistry purification method, mainly comprises the steps that
(1) fused salt to be clean is placed in cylindrical graphite crucible.Use high-density graphite material, molten
Salt useful load is liquid height about 2cm time melted.
(2) in crucible and fused salt are placed in airtight molten salt electrochemical experimental apparatus, (this device is by the Chinese Academy of Sciences
Shanghai Applied Physics Research Institute, according to application number: the Chinese patent report of 201320023881.X
Prepared by method), it is isolated with outside air environment.
(3) using burner hearth evacuation and be passed through argon as protection gas.Burner hearth is heated to 350 DEG C also
It is incubated 3 hours.One air inlet and gas outlet are set, persistently will use inert gas purification device (purity
7N) protection gas after purification is passed through and discharges, and the gas in fused salt solid to be clean and moisture is carried out
Go.
(4) burner hearth is warming up to 550 DEG C, and is incubated and within more than 3 hours, guarantees that fused salt to be clean all melts.
(5) with graphite as anode material, with metal platinum as cathode material, use electrochemical workstation or
The instruments such as person's potentiostat, carry out the preelectrolysis impurity and purification process of the fused salt to be clean melted.Processed
Selecting potentiostatic deposition pattern in journey, bath voltage is set as 2.5V.Electrolysis time 5 hours.At this
During melted fused salt to be clean is carried out continuously stirred, improve treatment effeciency.
(6) after step (5) terminates, before using the detection electrolysis impurity and purification of ICP-AES method to process
After fused salt in concentration of metallic impurities, as shown in table 4.Compared with table 1, after purified treatment, various metals are miscellaneous
Matter concentration is the highest.
In table 4:FLINAK fused salt, concentration of metallic impurities measures (ICP-AES)
| Element kind | Content (ppm) before electrolysis | Content (ppm) after electrolysis |
| Fe | 2300 | 252 |
| Cr | 900 | 71 |
| Ni | 430 | 30 |
Claims (10)
1. the electrochemical purification method of a fused salt, it is characterised in that it comprises the following steps:
Step (1): use three electrodes: negative electrode, anode and reference electrode, determines melted to be clean
The electrochemical window of fused salt and in melten salt electriochemistry window to be clean the electrochemical reduction spike potential of impurity；
With graphite as anode material, with inert metal as cathode material, described inert metal is not with to be clean
The metal that fused salt reacts；
Step (2): bear with the electrochemical reduction spike potential than the impurity determined in step (1), be more than
Or be electrolysed equal to the voltage of the electrochemical window of fused salt to be clean.
2. the electrochemical purification method of fused salt as claimed in claim 1, it is characterised in that:
Described fused salt method for cleaning impurity includes step (3): checked for impurities content, if reaching to purify
Require then to purify to terminate, the fused salt after being purified；Requiring if not up to purifying, repeating step (2)
Until reaching to purify requirement；During repetition, preferably means are electric for changing cathode material, anode material and reference
Pole is changed or is changed without；
In described step (3), the method for described checked for impurities content is that online cyclic voltammetry is swept
Retouch the electric current density of impurity, or off-line sampling mode, utilize chemical method checked for impurities concentration；
In described step (3), in the described fused salt after purification, the reduction peak current density of impurity is little
In 30mA/cm2, preferably less than 10mA/cm2～30mA/cm2, more preferably less than 10mA/cm2。
3. the electrochemical purification method of fused salt as claimed in claim 1 or 2, it is characterised in that: institute
In the step (1) stated, described fused salt to be clean is molten chloride and/or fluoride molten salt, described
Molten chloride be preferably the one in lithium chloride, potassium chloride, sodium chloride, magnesium chloride and calcium chloride
Or it is multiple；Described fluoride molten salt is preferably the one in sodium fluoride, lithium fluoride and potassium fluoride or many
Kind or sodium fluoride, lithium fluoride and potassium fluoride in one or more mixture with calcium fluoride；Described
Step (1) is carried out the most under anaerobic.
4. the electrochemical purification method of fused salt as claimed in claim 1 or 2, it is characterised in that: institute
In the step (1) stated, the impurity cationic contained in described fused salt to be clean is metal cation,
The described metal in metal cation is the one in Fe, Cr, Ni, Cu, Pb, Al, Zn and Zr
Or it is multiple；Described impurity anions is O2-；The quality of impurity anions in described fused salt to be clean
Percentage composition is preferably no greater than 5%；Described weight/mass percentage composition refers to that the quality of anion accounts for and treats only
Change the percentage composition of fused salt gross mass；The weight/mass percentage composition of impurity cationic in described fused salt to be clean
It is preferably no greater than 10%；It is total that described weight/mass percentage composition refers to that the quality of cation accounts for fused salt to be clean
The percentage composition of quality；The fusing point of described fused salt to be clean is preferably less than 1000 DEG C.
5. the electrochemical purification method of fused salt as claimed in claim 1 or 2, it is characterised in that: institute
In the step (1) stated, described inert metal is one or more in platinum, molybdenum and tungsten.
6. fused salt method for cleaning impurity as claimed in claim 1 or 2, it is characterised in that: described
In step (1), described reference electrode is metal reference electrode, chloride system reference electrode or fluorine
Salt system reference electrode；Described metal reference electrode is preferably platinum electrode；Described chloride system is
Refer to the salt that metal ion is formed with chloride ion；Described fluoric-salt system refers to that metal ion is formed with fluorion
Salt；Described metal ion is preferably Ag+Or Ni2+。
7. the electrochemical purification method of fused salt as claimed in claim 6, it is characterised in that: described
Chloride system is silver chloride；Described fluoric-salt system is Nickel difluoride.
8. the electrochemical purification method of fused salt as claimed in claim 1 or 2, it is characterised in that: institute
In the step (1) stated, described method of testing is cyclic voltammetry；When using cyclic voltammetry test
When electrochemical window and electrochemical reduction spike potential, scanning voltage is preferably 0V～fused salt to be clean
Electrochemical window, scanning speed is preferably 0.01V/s～1V/s, is more preferably 0.1V/s.
9. the electrochemical purification method of fused salt as claimed in claim 1 or 2, it is characterised in that: institute
In the step (2) stated, the impurity that the electrode potential that uses during described electrolysis is more negative than electrode potential
Electrode potential is born, and the electrode potential of preferably more negative than electrode potential impurity bears 100mV～500mV；
The electrode potential used during described electrolysis is more than or equal to the electrochemical window of fused salt to be measured.
10. the electrochemical purification method of fused salt as claimed in claim 1 or 2, it is characterised in that: institute
In the step (2) stated, the time of described electrolysis is 1 hour～20 hours, preferably 4 hours～
8 hours.
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| CN110289408A (en) * | 2019-06-26 | 2019-09-27 | 东北大学 | Nano-silicon and silicon/carbon composite and preparation method and application based on cutting scrap silicon |
| EP3578691A1 (en) * | 2018-06-08 | 2019-12-11 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Methods for reducing the corrosiveness of a fluid material for a high-temperature range and devices therefore |
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| WO2020193305A1 (en) * | 2019-03-22 | 2020-10-01 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Engineering process for halogen salts, using two identical electrodes |
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