US2458663A - Molten salt baths - Google Patents
Molten salt baths Download PDFInfo
- Publication number
- US2458663A US2458663A US711795A US71179546A US2458663A US 2458663 A US2458663 A US 2458663A US 711795 A US711795 A US 711795A US 71179546 A US71179546 A US 71179546A US 2458663 A US2458663 A US 2458663A
- Authority
- US
- United States
- Prior art keywords
- bath
- molten salt
- sodium
- salt baths
- molten
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/28—Cleaning or pickling metallic material with solutions or molten salts with molten salts
Definitions
- This application relates to molten salt baths and more particularly to a process for maintaining such baths in satisfactory operating or functioning condition.
- molten salt baths of the type with which I am familiar namely, the non-electrolytic molten salt bath containing sodium hydroxide, sodium nitrate, and 4% or more of sodium chloride, or the electrolytic bath containing sodium hydroxide, sodium chloride, and at least one-half of one percent of sodium aluminate
- the functioning of the bath is impaired by the formation in the bath of objectionable compounds.
- such compounds are formed as reaction products of the molten salt with the surfaces of the metals being cleaned in such baths and with oxygen.
- the objectionable compound is in the form'of sodium ferrite.
- sodium ferrite in such a bath may be removed simply by bubbling moisture in the form of steam into the bath, using any suitable apparatus for such purpose.
- the bath contains objectionable compounds in the form of metal-alkali-oxide compounds, such as sodium ferrite.
- This has a formula of Na2Fe2O4. This is considered as if it were NazOIFezOs.
- NazOIFezOs By adding moisture, we form by hydrolysis a mixture of NazOzIhO and F8203. In this mixture, the FezOs is considered as having been released from the M120.
- the Fe2O3 is the objectionable metal oxide. It precipitates in the bath and drops to the bottom to form a sludge which can be removed by commonly known suitable mechanical means for removing sludge.
- the NazOIHzO returns to the bath in the form of NaOH, an original ingredient of the bath.
- a process for removing objectionable sodium ferrite from a, molten alkali-salt bath comprising molten alkali salts, molten sodium hydroxide and said objectionable sodium ferrite comprising passing steam into said bath to precipitate the ferrite, as a removable sludge, from the bath.
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
Patented Jan. 11, 1949 2,458,663 MOLTEN SALT BATHS Hugh G. Webster, Detroit, Mich., assignor to J. H. Shoemaker, Detroit, Mich.
No Drawing. Application November 22, 1946, Serial No. 711,795
1 Claim. 1
This application relates to molten salt baths and more particularly to a process for maintaining such baths in satisfactory operating or functioning condition.
I have discovered that in the use of molten salt baths of the type with which I am familiar, namely, the non-electrolytic molten salt bath containing sodium hydroxide, sodium nitrate, and 4% or more of sodium chloride, or the electrolytic bath containing sodium hydroxide, sodium chloride, and at least one-half of one percent of sodium aluminate, the functioning of the bath is impaired by the formation in the bath of objectionable compounds. I havediscovered that such compounds are formed as reaction products of the molten salt with the surfaces of the metals being cleaned in such baths and with oxygen. In the case of a molten sodium salt bath used in cleaning ferrous work pieces, the objectionable compound is in the form'of sodium ferrite. In this application, I disclose that sodium ferrite in such a bath may be removed simply by bubbling moisture in the form of steam into the bath, using any suitable apparatus for such purpose.
For an understanding of the operation of the moisture for this purpose, let us consider the following. The bath contains objectionable compounds in the form of metal-alkali-oxide compounds, such as sodium ferrite. This has a formula of Na2Fe2O4. This is considered as if it were NazOIFezOs. By adding moisture, we form by hydrolysis a mixture of NazOzIhO and F8203. In this mixture, the FezOs is considered as having been released from the M120. The Fe2O3 is the objectionable metal oxide. It precipitates in the bath and drops to the bottom to form a sludge which can be removed by commonly known suitable mechanical means for removing sludge. The NazOIHzO returns to the bath in the form of NaOH, an original ingredient of the bath.
Now having described the herein disclosed method for maintaining a bath satisfactorily, I claim the following:
A process for removing objectionable sodium ferrite from a, molten alkali-salt bath comprising molten alkali salts, molten sodium hydroxide and said objectionable sodium ferrite comprising passing steam into said bath to precipitate the ferrite, as a removable sludge, from the bath.
HUGH G. WEBSTER.
REFERENCES CITED The following references are of record in the file of this patent: I
Mellor, Inorganic and Theoretical Chemistry, vol. 13, page 906.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US711795A US2458663A (en) | 1946-11-22 | 1946-11-22 | Molten salt baths |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US711795A US2458663A (en) | 1946-11-22 | 1946-11-22 | Molten salt baths |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2458663A true US2458663A (en) | 1949-01-11 |
Family
ID=24859561
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US711795A Expired - Lifetime US2458663A (en) | 1946-11-22 | 1946-11-22 | Molten salt baths |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2458663A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2644775A (en) * | 1950-07-01 | 1953-07-07 | Hooker Electrochemical Co | Method of bright annealing and cleaning |
| US2738294A (en) * | 1951-09-13 | 1956-03-13 | Diamond Alkali Co | Salt bath system and method for treating metals |
| US2847374A (en) * | 1956-06-12 | 1958-08-12 | Kolene Corp | Metal processing |
-
1946
- 1946-11-22 US US711795A patent/US2458663A/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| None * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2644775A (en) * | 1950-07-01 | 1953-07-07 | Hooker Electrochemical Co | Method of bright annealing and cleaning |
| US2738294A (en) * | 1951-09-13 | 1956-03-13 | Diamond Alkali Co | Salt bath system and method for treating metals |
| US2847374A (en) * | 1956-06-12 | 1958-08-12 | Kolene Corp | Metal processing |
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