US3793208A - Method of rectifying commercial salt baths - Google Patents
Method of rectifying commercial salt baths Download PDFInfo
- Publication number
- US3793208A US3793208A US00320885A US3793208DA US3793208A US 3793208 A US3793208 A US 3793208A US 00320885 A US00320885 A US 00320885A US 3793208D A US3793208D A US 3793208DA US 3793208 A US3793208 A US 3793208A
- Authority
- US
- United States
- Prior art keywords
- percent
- bath
- rectifying
- weight
- carbonates
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/607—Molten salts
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D9/00—Nitrates of sodium, potassium or alkali metals in general
- C01D9/16—Purification
Definitions
- the present invention concerns a method of rectifying in situ a commercial salt bath containing undesirable carbonates and/or hydroxides impurities, comprising the steps of: maintaining the bath at a temperature from about 300F to about 600F; introducing into the bath, an aqueous solution consisting essentially of, about 0.1 percent to about 8 percent by weight free nitric acid, about 0.01 percent to about percent by weight non-ionic surface active agent means for deterring foaming of the bath and for assisting in rapid dispersion of the solution in the bath, and the balance water, to thereby rectify the bath.
- Nitrate-nitrite salt baths accumulate alkali and alkali carbonate impurities in use due either to thermal decomposition or drag-in from carbonate containing higher temperature baths.
- the alkali (sodium hydroxide or potassium hydroxide) or alkali carbonate (sodium carbonate or potassium carbonate) impurities are undesirable for efficient salt bath heating and quenching of steel.
- nitric acid content of the aqueous solution referred to above should preferably be maintained within the range of about 2 percent to about 7 percent and best results are obtained within the range of about 4 percent to about 6 percent free nitric acid by weight of said aqueous solution.
- the surface active agent means used in the inventive method herein should be non-ionic, low-foaming, and soluble in water and stable to dilute aqueous acids such as nitric acid.
- the surface active agent means should preferably be composed of carbon, hydrogen and oxygen to avoid undesirable residues in the rectified salt bath (that is undesirable residues such as phosphates or sulfates). Desirable surface active agent means for the purpose of carrying out the inventive discovery herein are as follows:
- the carbonates impurities referred to herein are normally salts of barium, sodium, potassium, or calcium and are normally present in the commercial salt bath from about 0.01 percent to about 3 percent by weight of the salt bath.
- the hydroxides impurities referred to herein are normally alkali hydroxides and may be present in the salt bath being rectified from about 0.01 percent to about 50 percent by weight.
- EXAMPLE A composition is prepared consisting of 5 percent by weight free nitric acid, 0.1 percent by weight of a surface active agent means (F68LF) and the balance water to percent by weight.
- a commercial salt bath (of approximately 1,000 pound size) to be rectified was first analyzed to determine the percentage of sodium carbonate therein in percent by weight. The percent by weight of sodium carbonate was determined to be approximately /2 percent by weight sodium carbonate.
- Approximately 14 gallons of the above rectifying composition is added to the commercial salt bath. The result is that the commercial salt bath is satisfactorily rectified by the addition of said 14 gallons of the rectifier composition above.
- a method of rectifying in situ a metal heat treating molten nitrate/nitrite salt bath containing undesirable carbonates and/or hydroxides impurities comprising the steps of:
- aqueous solution consisting essentially of, about 0.1 percent to about 8 percent by weight free nitric acid
- non-ionic surface active agent for deterring foaming of the bath and for assisting in rapid dispersion of the solution in the bath
- said nitric acid is present from about 2 percent to about 7 percent.
- said nitric acid is present from about 4 percent to about 6 percent.
- said temperature is from about 400 to about 600F.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Agronomy & Crop Science (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Detergent Compositions (AREA)
Abstract
A method of rectifying commercial salt baths which operate generally within the temperature range from about 300*-600* F, said rectifying being to remove undesirable carbonates and/or hydroxides impurities.
Description
United States Patent n91 Foreman l l 3,793,208 [4 1 Feb. 19,1974
METHOD OF RECTIFYING COMMERCIAL SALT BATHS Robert W. Foreman, Bloomfield Hills, Mich.
Assignee: Park Chemical Company, Detroit,
Mich.
Filed: Jan. 4, 1973 Appl. No.: 320,885
Inventor:
US. Cl 252/71, 148/15, 148/22 Int. Cl C09k 3/02 Field of Search... 252/71; 148/15, 15.5, 22, 27,
References Cited UNITED STATES PATENTS 4/1876 Herrenschmidt 252/71 Primary ExaminerLcon D. Rosdol Assistant ExaminerHarris A. Pitlick Attorney, Agent, or Firm-Harness, Dickey & Pierce ABSTRACT A method of rectifying commercial salt baths which operate generally within the temperature range from about 300-600 F, said rectifying being to remove undesirable carbonates and/or hydroxides impurities.
7 Claims, No Drawings METHOD OF RECTIFYING COMMERCIAL SALT BATI-IS BACKGROUND OF THE INVENTION This invention broadly relates to a method of rectifying commercial salt baths. The state of the art is indicated by the following U. S. Pat. Nos: 2,278,297; 2,375,758; 2,375,759; 2,375,760; 2,375,761; Re 23,017; and 2,474,680.
Accordingly, it is a primary object of this invention to provide a new improved method of rectifying commercial salt baths to remove undesirable carbonates and/or hydroxides impurities therefrom.
Other objects, features, and advantages of the present invention will become apparent from the subsequent description and the appended claims.
SUMMARY OF THE INVENTION Briefly stated, the present invention concerns a method of rectifying in situ a commercial salt bath containing undesirable carbonates and/or hydroxides impurities, comprising the steps of: maintaining the bath at a temperature from about 300F to about 600F; introducing into the bath, an aqueous solution consisting essentially of, about 0.1 percent to about 8 percent by weight free nitric acid, about 0.01 percent to about percent by weight non-ionic surface active agent means for deterring foaming of the bath and for assisting in rapid dispersion of the solution in the bath, and the balance water, to thereby rectify the bath.
DESCRIPTION OF PREFERRED EMBODIMENTS The invention discovered and disclosed herein has been found to provide a surprisingly good and unex' pectedly advantageous way of rectifying commercial salt baths for the purpose of removing or converting undesirable carbonates and/or hydroxides impurities in these commercial salt baths, such that these impurities are no longer present in the bath or are present in such low amounts that they do not harmfully affect the operation of the bath.
Nitrate-nitrite salt baths accumulate alkali and alkali carbonate impurities in use due either to thermal decomposition or drag-in from carbonate containing higher temperature baths. The alkali (sodium hydroxide or potassium hydroxide) or alkali carbonate (sodium carbonate or potassium carbonate) impurities are undesirable for efficient salt bath heating and quenching of steel.
The discovery has been made in this invention that it is possible to eliminate difficult separation and removal of the carbonates or alkalis from molten nitrate/nitrite salt baths which operate at a temperature of about 300-600F. These carbonates or impurities are sparingly soluble in such baths at their usual operating temperatures (300-600F) and they interfere with both heat transfer and quenching efficiency.
In the past it has not been known that such salt baths could be rectified in situ, that is, in accordance with this invention it is not required to take the liquid bath material through any kind of an external treating system or the like. Furthermore it has been discovered in this invention that the concentration of the nitric acid used and referred to above is critical in successfully carrying out the invention herein. Still further in this invention the discovery has been made that unique results appear to be obtained through the use of a surface active agent means which are discussed and disclosed herein. The temperature at which the salt bath is maintained is also important. Below about 400F, heavy brown fumes are liberated if it is attempted to carry out the method herein and particularly if it is attempted to carry out the method herein below 300F then the heavy brown fumes liberated become very excessive. Preferably, the method herein should be carried out at a temperature range between about 400F and 400F.
The nitric acid content of the aqueous solution referred to above should preferably be maintained within the range of about 2 percent to about 7 percent and best results are obtained within the range of about 4 percent to about 6 percent free nitric acid by weight of said aqueous solution.
The surface active agent means used in the inventive method herein should be non-ionic, low-foaming, and soluble in water and stable to dilute aqueous acids such as nitric acid. The surface active agent means should preferably be composed of carbon, hydrogen and oxygen to avoid undesirable residues in the rectified salt bath (that is undesirable residues such as phosphates or sulfates). Desirable surface active agent means for the purpose of carrying out the inventive discovery herein are as follows:
Trade Name Supplier Physical-chemical Description Pluronic F68LF BASF/Wyandotte Condensate of ethylene oxide with hydrophobic bases formed by The carbonates impurities referred to herein are normally salts of barium, sodium, potassium, or calcium and are normally present in the commercial salt bath from about 0.01 percent to about 3 percent by weight of the salt bath. The hydroxides impurities referred to herein are normally alkali hydroxides and may be present in the salt bath being rectified from about 0.01 percent to about 50 percent by weight.
In order to further illustrate the invention the following example is provided. It is to be understood however that the example is included for illustrative purposes and is not intended to be limiting of the scope of the invention as set forth in the subjoined claims.
EXAMPLE A composition is prepared consisting of 5 percent by weight free nitric acid, 0.1 percent by weight of a surface active agent means (F68LF) and the balance water to percent by weight. A commercial salt bath (of approximately 1,000 pound size) to be rectified was first analyzed to determine the percentage of sodium carbonate therein in percent by weight. The percent by weight of sodium carbonate was determined to be approximately /2 percent by weight sodium carbonate. Approximately 14 gallons of the above rectifying composition is added to the commercial salt bath. The result is that the commercial salt bath is satisfactorily rectified by the addition of said 14 gallons of the rectifier composition above. It has been found that approximately 2.8 gallons of said above rectifier composition will normally rectify the undesirable carbonate impurity in a 1,000 pound nitrate commercial salt bath per each 1/10 percent by weight of sodium carbonate impurity in said bath. Additional amounts of said rectifying composition may be necessary to rectify the undissolved carbonates impurities lying at the bottom of the commercial salt bath which undissolved carbonates will not go into solution in the bath unless and until the already dissolved carbonates in the bath are rectified or removed from the bath through addition of said rectifying composition.
While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated it will be appreciated that the invention is susceptible to modification, variation, and change without departing from the proper scope or fair meaning of the subjoined claims.
What is claimed is:
l. A method of rectifying in situ a metal heat treating molten nitrate/nitrite salt bath containing undesirable carbonates and/or hydroxides impurities, comprising the steps of:
maintaining the bath at a temperature from about 4 300F to about 600F; introducing into the bath, an aqueous solution consisting essentially of, about 0.1 percent to about 8 percent by weight free nitric acid,
about 0.01 percent to about 5 percent by weight non-ionic surface active agent for deterring foaming of the bath and for assisting in rapid dispersion of the solution in the bath,
and the balance water, to thereby rectify the bath.
2. The method of claim 1 wherein,
said nitric acid is present from about 2 percent to about 7 percent.
3. The method of claim 1 wherein,
said nitric acid is present from about 4 percent to about 6 percent.
4. The method of claim 1 wherein,
said temperature is from about 400 to about 600F.
0.01 percent to about 50 percent by weight.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 793, 208 Dated February 19, 1974 Inventor(s) Robert W. Foreman It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:
Front Page, Column References, last reference, "R23, 017
should be "R623, 017
Column 2, line 10, second occurrence of "'4c00 F" should be Signed and sealed this 21st day off-lay 19724;.
SEAL) 17:. t t 6 S t LDI'IARD II .FLETGHLIPL, J1 v C II AHSEIALL DA SIN Attesting Officer Commissioner of Patents F ORM PO-IOSO (10-69)
Claims (6)
- 2. The method of claim 1 wherein, said nitric acid is present from about 2 percent to about 7 percent.
- 3. The method of claim 1 wherein, said nitric acid is present from about 4 percent to about 6 percent.
- 4. The method of claim 1 wherein, said temperature is from about 400* to about 600*F.
- 5. The method of claim 4 wherein, said nitric acid is present from about 4 percent to about 6 percent.
- 6. The method of claim 1 wherein, said surface active agent is selected from at least one of the group consisting of a polyethenoxy ether liquid and an alkyaryl polyether liquid.
- 7. The method of claim 1 wherein, said carbonates are salts of barium, sodium, potassium or calcium and are present in the bath from about 0.01 percent to about 3 percent by weight, and said hydroxides are present in the bath from about 0.01 percent to about 50 percent by weight.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US32088573A | 1973-01-04 | 1973-01-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3793208A true US3793208A (en) | 1974-02-19 |
Family
ID=23248242
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00320885A Expired - Lifetime US3793208A (en) | 1973-01-04 | 1973-01-04 | Method of rectifying commercial salt baths |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3793208A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3966508A (en) * | 1973-08-09 | 1976-06-29 | Ekkehard Mohr | Treating waste discharge liquids from metal hardening baths, particularly containing nitrite and nitrate compounds |
| US4019928A (en) * | 1973-03-05 | 1977-04-26 | Duetsche Gold- Und Silber-Scheideanstalt Vormals Roessler | Process for nitriding iron and steel in salt baths regenerated with triazine polymers |
| US4149702A (en) * | 1976-03-25 | 1979-04-17 | Park Chemical Company | Method and apparatus for recycling heat treating salts |
| US4717429A (en) * | 1985-09-24 | 1988-01-05 | Degussa Aktiengesellschaft | Process for the removal of alkali metal nitrite from nitrate containing salt baths |
| US6117249A (en) * | 1998-02-13 | 2000-09-12 | Kerk Motion Products, Inc. | Treating metallic machine parts |
| US20130264514A1 (en) * | 2012-04-10 | 2013-10-10 | Basf Se | Nitrate salt compositions comprising alkali metal carbonate and their use as heat transfer medium or heat storage medium |
| WO2014114508A1 (en) * | 2013-01-23 | 2014-07-31 | Basf Se | Method for improving nitrate salt compositions by means of nitric acid in the use thereof as a thermal transfer medium or as a thermal accumulator medium |
| CN105803165A (en) * | 2016-05-31 | 2016-07-27 | 梁辉章 | Quenching medium |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US23017A (en) * | 1859-02-22 | Cricket-bat | ||
| US183804A (en) * | 1876-10-31 | Improvement in baths for tempering articles of iron and steel | ||
| US2205180A (en) * | 1935-09-24 | 1940-06-18 | Corning Glass Works | Method of tempering glass articles |
| US2278297A (en) * | 1941-10-16 | 1942-03-31 | Socony Vacuum Oil Co Inc | Handling thermophore mixtures |
| US2375759A (en) * | 1940-09-28 | 1945-05-15 | Socony Vacuum Oil Co Inc | Treatment of heat transfer salts |
| US2375761A (en) * | 1944-10-18 | 1945-05-15 | Houdry Process Corp | Treatment of alkali metal salts |
| US2375758A (en) * | 1940-09-27 | 1945-05-15 | Houdry Process Corp | Control of heat transfer salts |
| US2375760A (en) * | 1942-01-09 | 1945-05-15 | Socony Vacuum Oil Co Inc | Treatment of heat transfer salts |
| US2857301A (en) * | 1956-02-23 | 1958-10-21 | Reed Roller Bit Co | Method of surface-hardening steel, and a quenching medium therefor |
| US3220893A (en) * | 1963-11-29 | 1965-11-30 | Union Carbide Corp | Metal quenching medium |
-
1973
- 1973-01-04 US US00320885A patent/US3793208A/en not_active Expired - Lifetime
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US23017A (en) * | 1859-02-22 | Cricket-bat | ||
| US183804A (en) * | 1876-10-31 | Improvement in baths for tempering articles of iron and steel | ||
| US2205180A (en) * | 1935-09-24 | 1940-06-18 | Corning Glass Works | Method of tempering glass articles |
| US2375758A (en) * | 1940-09-27 | 1945-05-15 | Houdry Process Corp | Control of heat transfer salts |
| US2375759A (en) * | 1940-09-28 | 1945-05-15 | Socony Vacuum Oil Co Inc | Treatment of heat transfer salts |
| US2278297A (en) * | 1941-10-16 | 1942-03-31 | Socony Vacuum Oil Co Inc | Handling thermophore mixtures |
| US2375760A (en) * | 1942-01-09 | 1945-05-15 | Socony Vacuum Oil Co Inc | Treatment of heat transfer salts |
| US2375761A (en) * | 1944-10-18 | 1945-05-15 | Houdry Process Corp | Treatment of alkali metal salts |
| US2857301A (en) * | 1956-02-23 | 1958-10-21 | Reed Roller Bit Co | Method of surface-hardening steel, and a quenching medium therefor |
| US3220893A (en) * | 1963-11-29 | 1965-11-30 | Union Carbide Corp | Metal quenching medium |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4019928A (en) * | 1973-03-05 | 1977-04-26 | Duetsche Gold- Und Silber-Scheideanstalt Vormals Roessler | Process for nitriding iron and steel in salt baths regenerated with triazine polymers |
| US3966508A (en) * | 1973-08-09 | 1976-06-29 | Ekkehard Mohr | Treating waste discharge liquids from metal hardening baths, particularly containing nitrite and nitrate compounds |
| US4149702A (en) * | 1976-03-25 | 1979-04-17 | Park Chemical Company | Method and apparatus for recycling heat treating salts |
| US4158579A (en) * | 1976-03-25 | 1979-06-19 | Park Chemical Company | Method for recycling heat treating salts |
| US4717429A (en) * | 1985-09-24 | 1988-01-05 | Degussa Aktiengesellschaft | Process for the removal of alkali metal nitrite from nitrate containing salt baths |
| US6117249A (en) * | 1998-02-13 | 2000-09-12 | Kerk Motion Products, Inc. | Treating metallic machine parts |
| US20130264514A1 (en) * | 2012-04-10 | 2013-10-10 | Basf Se | Nitrate salt compositions comprising alkali metal carbonate and their use as heat transfer medium or heat storage medium |
| US9133382B2 (en) * | 2012-04-10 | 2015-09-15 | Basf Se | Nitrate salt compositions comprising alkali metal carbonate and their use as heat transfer medium or heat storage medium |
| WO2014114508A1 (en) * | 2013-01-23 | 2014-07-31 | Basf Se | Method for improving nitrate salt compositions by means of nitric acid in the use thereof as a thermal transfer medium or as a thermal accumulator medium |
| AU2014210130B2 (en) * | 2013-01-23 | 2017-08-31 | Basf Se | Method for improving nitrate salt compositions by means of nitric acid in the use thereof as a thermal transfer medium or as a thermal accumulator medium |
| CN105803165A (en) * | 2016-05-31 | 2016-07-27 | 梁辉章 | Quenching medium |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3793208A (en) | Method of rectifying commercial salt baths | |
| US2377876A (en) | Metal cleaning process and composition | |
| US2564549A (en) | Pickling treatment | |
| CN108624935A (en) | A kind of closing process of alkali resistance confining liquid and aluminum alloy surface oxidation film | |
| US3121026A (en) | Descaling metals and alloys with aqueous potassium hydroxide at relatively low temperature | |
| US9752238B2 (en) | Method and formulations for removing rust and scale from steel and for regenerating pickling liquor in hot-dip galvanization process | |
| CA1046387A (en) | Method and composition for cleaning the surface of ferrous metal | |
| US2538702A (en) | Metal surface cleaning | |
| US4549985A (en) | Waste disposal process | |
| US4149702A (en) | Method and apparatus for recycling heat treating salts | |
| US2408424A (en) | Pickling steels | |
| US3721626A (en) | Descaling method and composition of alkali metal hydroxide | |
| JPH0765204B2 (en) | Method for dissolving and removing iron oxide | |
| US2562169A (en) | Method of purifying alkali metal hydroxides | |
| US2353026A (en) | Metal-cleaning process and composition | |
| KR950013314B1 (en) | Retreatment method for sludge containing fluorine | |
| US2419076A (en) | Removal of carbonaceous deposits | |
| US2935428A (en) | Method and composition for subjecting metals to reducing conditions | |
| JPH03265514A (en) | Method for treatment of etching waste liquid containing fluorine compd. | |
| US2893863A (en) | Process for removing aluminum coatings | |
| JPS5841112B2 (en) | Hiion sponge cutlet seizaigan Yuuhaisuinoshiyorihouhou | |
| US3027310A (en) | Cleaning bath and method of cleaning moving metal strip | |
| US3218254A (en) | Treatment of toxic copper-containing solutions | |
| US2764470A (en) | Purification of uranium peroxide | |
| US4557835A (en) | Process for removal of dissolved oxygen from steam generation systems |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AS | Assignment |
Owner name: SECURITY PACIFIC NATIONAL BANK, AS ADMINISTRATIVE Free format text: SECURITY INTEREST;ASSIGNOR:PARK CHEMICAL COMPANY;REEL/FRAME:005224/0544 Effective date: 19890628 |
|
| AS | Assignment |
Owner name: PARK CHEMICAL COMPANY, MICHIGAN Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:SECURITY PACIFIC NATIONAL BANK;REEL/FRAME:005461/0651 Effective date: 19900605 |