AT249471B - Process for reprocessing the caustic soda that occurs when steel is descaled - Google Patents
Process for reprocessing the caustic soda that occurs when steel is descaledInfo
- Publication number
- AT249471B AT249471B AT749864A AT749864A AT249471B AT 249471 B AT249471 B AT 249471B AT 749864 A AT749864 A AT 749864A AT 749864 A AT749864 A AT 749864A AT 249471 B AT249471 B AT 249471B
- Authority
- AT
- Austria
- Prior art keywords
- steel
- descaled
- reprocessing
- occurs
- caustic soda
- Prior art date
Links
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 title claims description 31
- 238000000034 method Methods 0.000 title claims description 6
- 235000011121 sodium hydroxide Nutrition 0.000 title description 8
- 229910000831 Steel Inorganic materials 0.000 title description 4
- 239000010959 steel Substances 0.000 title description 4
- 238000012958 reprocessing Methods 0.000 title 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 7
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 229910052938 sodium sulfate Inorganic materials 0.000 description 4
- 235000011152 sodium sulphate Nutrition 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000012312 sodium hydride Substances 0.000 description 2
- 229910000104 sodium hydride Inorganic materials 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Landscapes
- Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
Description
<Desc/Clms Page number 1>
Verfahren zur Aufarbeitung der beim Entzundern von
Stahl anfallenden Natronlauge
Beim Entzundern von Stahl durch Beizen mit Säuren entstehen saure Abwässer, die neutralisiert werden müssen. Die Reinhaltung der Gewässer erfordert, dass derartige Abwässer neutralisiert werden.
Die dadurch entstehenden Aufwendungen sind erheblich und machen einen grossen Teil der gesamten Beizkosten aus.
Es ist an sich bekannt, Stahl dadurch zu entzundern, dass man ihn in einer überwiegend aus Natriumhydroxyd bestehenden natriumhydridhaltigen Schmelze bei 3500 C behandelt. Bei unlegiertem oder niedrig legiertem Material ist hiebei erfahrungsgemäss eine Nachbeizung mit Säure nicht mehr notwendig. Beim Abschrecken und Waschen des im Natriumhydridbad entzunderten Materials entsteht verunreinigte Natronlauge.
Erfindungsgemäss wird nun vorgeschlagen, diese Natronlauge durch Waschen im Gegenstrom soweit anzureichern, dass nach Neutralisieren mit Schwefelsäure und Abkühlen festes, kristallisiertes Natriumsulfat entsteht.
Vorteilhaft wird bis zu einer solchen Konzentration angereichert, dass die Natronlauge etwa 300/0 NaOH enthält. Versetzt man diese Natronlauge mit konzentrierter Schwefelsäure, so erhält man eine Lösung, die ungefähr der Formel Na SO. 10 HO entspricht. Eine solche Lösung erstarrt beim Abkühlen zu festem, kristallisiertem Natriumsulfat.
Die konzentrierte Natriumsulfatlösung kann man in Blechtrommeln füllen, erstarren lassen und dann nach Verfahren, die für unverwertbare Chemikalien üblich sind, z. B. durch Versenken im Meer, beseitigen.
Bei dieser Arbeitsweise entsteht keine Abwässergefährdung ! es sind auch keine komplizierten, kostspieligen und reparaturanfälligen Anlagen zur Aufarbeitung von Abfallsäuren erforderlich, wie sie beim Beizen in Schwefelsäure oder Salzsäure unumgänglich nötig sind, um Verunreinigungen der Vorfluter mit Säure oder Eisenlösungen zu vermeiden.
PATENTANSPRÜCHE :
1. Verfahren zur Aufarbeitung der beim Entzundern von unlegiertem ader niedrig legiertem Stahl
EMI1.1
beim Abschrecken und Waschen des Materials anfallende Natronlauge durch Waschen im Gegenstrom bis zu einer solchen Konzentration angereichert wird, dass nach Neutralisieren mit Schwefelsäure und Abkühlen festes, kristallisiertes Natriumsulfat entsteht.
**WARNUNG** Ende DESC Feld kannt Anfang CLMS uberlappen**.
<Desc / Clms Page number 1>
Process for reconditioning the descaling of
Caustic soda produced in steel
When steel is descaled by pickling with acids, acidic wastewater is produced which must be neutralized. Keeping water bodies clean requires that such waste water be neutralized.
The resulting expenses are considerable and make up a large part of the total pickling costs.
It is known per se that steel can be descaled by treating it in a sodium hydride-containing melt at 3500 ° C. which consists predominantly of sodium hydroxide. In the case of unalloyed or low-alloy material, experience has shown that pickling with acid is no longer necessary. When quenching and washing the descaled material in a sodium hydride bath, contaminated sodium hydroxide is produced.
According to the invention, it is now proposed that this sodium hydroxide solution be enriched by washing in countercurrent to such an extent that solid, crystallized sodium sulfate is formed after neutralization with sulfuric acid and cooling.
It is advantageous to enrich up to a concentration such that the sodium hydroxide solution contains about 300/0 NaOH. If this sodium hydroxide solution is mixed with concentrated sulfuric acid, a solution is obtained which roughly has the formula Na SO. 10 HO corresponds. Such a solution solidifies to solid, crystallized sodium sulfate on cooling.
The concentrated sodium sulfate solution can be filled into metal drums, allowed to solidify and then after processes that are common for unusable chemicals, such. B. by sinking in the sea, eliminate.
There is no waste water hazard with this working method! There is also no need for complicated, costly and repair-prone systems for processing waste acids, as are inevitable for pickling in sulfuric acid or hydrochloric acid in order to avoid contamination of the receiving waters with acid or iron solutions.
PATENT CLAIMS:
1. Process for reconditioning the descaling of unalloyed or low-alloy steel
EMI1.1
The sodium hydroxide solution obtained during quenching and washing of the material is enriched by washing in countercurrent to such a concentration that solid, crystallized sodium sulfate is formed after neutralization with sulfuric acid and cooling.
** WARNING ** End of DESC field may overlap beginning of CLMS **.
Claims (1)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE249471X | 1963-10-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AT249471B true AT249471B (en) | 1966-09-26 |
Family
ID=5935760
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AT749864A AT249471B (en) | 1963-10-25 | 1964-08-31 | Process for reprocessing the caustic soda that occurs when steel is descaled |
Country Status (1)
| Country | Link |
|---|---|
| AT (1) | AT249471B (en) |
-
1964
- 1964-08-31 AT AT749864A patent/AT249471B/en active
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