CN108914136B - Steel pipe galvanizing pretreatment process - Google Patents
Steel pipe galvanizing pretreatment process Download PDFInfo
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- CN108914136B CN108914136B CN201810862511.2A CN201810862511A CN108914136B CN 108914136 B CN108914136 B CN 108914136B CN 201810862511 A CN201810862511 A CN 201810862511A CN 108914136 B CN108914136 B CN 108914136B
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- acid
- pool
- solvent
- steel pipe
- acid pool
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- 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
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
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- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
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- 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
- C23G1/36—Regeneration of waste pickling liquors
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- 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
- C23G3/00—Apparatus for cleaning or pickling metallic material
- C23G3/04—Apparatus for cleaning or pickling metallic material for cleaning pipes
Abstract
The invention provides a steel pipe galvanizing pretreatment process which comprises an acid treatment process, a two-stage cleaning process and a solvent treatment process from front to back, wherein the acid treatment process comprises a new acid tank, an old acid tank and a waste acid tank; the solvent treatment process comprises a solvent pool and an online iron removal process, wherein the online iron removal process oxidizes and precipitates ferrous ions in the solvent pool; the steel pipe firstly passes through an old acid tank and a new acid tank to remove rust and oxide skin, then enters a two-stage dilute hydrochloric acid cleaning tank to wash away excessive acid and ferrous ions on the surface of the steel pipe, finally passes through a solvent tank to form a plating assistant film on the surface of the steel pipe, and then enters a galvanizing procedure. The method can reduce the consumption of acid, thoroughly remove industrial sewage and industrial sludge, realize the online iron removal function of the solvent and the post-treatment of the solvent sludge, and realize the green and environment-friendly recycling.
Description
Technical Field
The invention belongs to the technical field of steel pipe treatment, and particularly relates to a steel pipe galvanizing pretreatment process.
Background
After the steel pipe is rolled, rolled and welded, a layer of iron oxide is adhered to the surface of the steel pipe, and the iron oxide needs to be removed before galvanizing the steel pipe, otherwise galvanizing of the steel pipe is influenced.
At present, the traditional method for removing iron oxide on the surface of a steel pipe is to remove rust by hydrochloric acid and then use clear water for cleaning, so a large amount of water is needed, the sewage after cleaning the steel pipe needs to be treated, ferrous ions in the sewage are oxidized and precipitated by aeration at present, strong alkali sodium hydroxide is needed during precipitation, and the treated sewage returns to continuously clean the steel pipe. A large amount of industrial sludge is generated in the process of treating the ferrous ions in the sewage through oxidation and precipitation, and environmental pollution is caused.
After the steel pipe is cleaned by water, a solvent tank immersion process is carried out, a layer of uniform solvent film is formed on the surface of the steel pipe, when the solvent does not meet the use requirement in the use process, the solvent cannot be continuously used, the required solvent is introduced into a precipitation tank, hydrogen peroxide and ammonia water are added for mixing, then the mixture is conveyed into a filter press by a pump for solid-liquid separation, and the obtained regenerated solvent filtrate is returned to the solvent tank for continuous use.
The whole process has large water consumption, uses strong alkali and is unsafe; a large amount of sewage and sludge are generated, and the treatment cost is increased; the solvent can not be continuously used on line, and energy can be continuously used after intermittent treatment.
Disclosure of Invention
In view of the above, the present invention is directed to provide a steel pipe zinc plating pretreatment process, which can reduce the amount of acid and water, and does not use water as a cleaning agent, so that a sewage treatment process is not required, and industrial sludge is not generated. And realizes the on-line continuous use of the solvent.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a steel pipe galvanizing pretreatment process, which comprises an acid treatment process, a two-stage dilute hydrochloric acid cleaning process and a solvent treatment process from front to back,
the acid treatment process comprises a new acid pool, an old acid pool and a waste acid pool, wherein the new acid pool is injected with concentrated hydrochloric acid;
the two-stage dilute hydrochloric acid cleaning process comprises two-stage dilute hydrochloric acid pools;
the solvent treatment process comprises a solvent pool and an online iron removal process, wherein the online iron removal process is used for oxidizing and precipitating ferrous ions in the solvent pool and preparing ferroferric oxide;
the steel pipe flow is as follows:
the steel pipe firstly passes through an old acid tank and a new acid tank to remove rust and oxide skin, then enters a two-stage dilute acid tank to wash away excessive acid and ferrous ions on the surface of the steel pipe, finally passes through a solvent tank to enable a layer of uniform solvent film to be attached to the surface of the steel pipe, and then enters a galvanizing procedure;
the acid flow is as follows:
adding concentrated hydrochloric acid into a new acid pool, enabling the solution in the new acid pool to enter an old acid pool after use, enabling the solution in the old acid pool to enter a waste acid pool after reuse, enabling the recycled dilute hydrochloric acid obtained by the waste acid pool through a low-temperature distillation technology to enter a dilute acid pool for two-stage cleaning, and enabling the solution in the dilute acid pool to enter the new acid pool and the concentrated hydrochloric acid to prepare the new acid according to the proportion after use.
Further, the HCl concentration of the new acid pool is kept at 12% -18%, when the acid Baume degree of the new acid pool reaches 30, the new acid pool is judged to be an old acid pool, the acid Baume degree of the old acid pool is larger than 40, and when the acidity of the acid is detected to be smaller than 1, the new acid pool is judged to be a waste acid pool, the acid of the waste acid pool is distilled at a low temperature of 110 ℃, dilute hydrochloric acid is distilled out, the distilled recycled dilute hydrochloric acid returns to the dilute acid pool, and residual liquid containing ferrous chloride after distillation is crystallized to obtain ferrous chloride solid.
Furthermore, the dilute acid pool comprises a dilute acid pool I and a dilute acid pool II, the steel pipe firstly enters the dilute acid pool I after coming out of the new acid pool and then enters the dilute acid pool II, and the recycled dilute hydrochloric acid distilled from the waste acid pool enters the dilute acid pool II.
Further, in the online iron removal process, the solvent is mixed with hydrogen peroxide and ammonia water online in the process of being introduced into the sedimentation tank from the solvent tank through a pipeline, the pH value is controlled to be 4.8-5.0, iron hydroxide precipitation is formed, then the mixture is introduced into the solvent tank for plate-type filter pressing, the filtrate returns to the solvent tank to form circulation, and a filter cake, namely the solvent mud, is also obtained.
Further, the solvent pool contains 170-210 g/L NH4Cl, ZnCl of 210-250 g/L2。
Further, the adding molar ratio of the hydrogen peroxide to the ammonia water is 1: 4.
furthermore, the mixing time of the solvent, hydrogen peroxide and ammonia water in the pipeline is not less than 3 minutes, so that ferrous ions are completely oxidized into ferric ions, the pH value is adjusted by the ammonia water, ferric hydroxide precipitate is generated and separated into filtrate solvent for recycling, and the filter cake is solvent mud.
Further, the solvent mud is dissolved by waste acid, and is converted into ferroferric oxide (iron black) after alkali is added and the temperature is raised.
In the whole process, the trend of the steel pipe is opposite to that of the acid.
The sequence of the steel pipe passing through the acid tank is as follows: the waste acid pool is formed by distilling the waste acid pool, the distilled recycled dilute hydrochloric acid enters the dilute acid pool II, and the dilute hydrochloric acid in the dilute acid pool II flows to the dilute acid pool I, so that acid circulation is formed.
When the steel pipe passes through the solvent tank, acid and ferrous ions on the surface of the steel pipe enter the solvent tank along with the steel pipe. And the solvent, ferrous ions and acid in the solvent pool enter a buffer tank through a pipeline for precipitation, then enter a plate filter press, are mixed with hydrogen peroxide and ammonia water in the pipeline on line, the ferrous ions are oxidized into ferric ions by the hydrogen peroxide, then the ferric ions form a precipitate under the action of the ammonia water, and the filtrate filtered by the plate filter press is recycled into the solvent pool for utilization.
Compared with the prior art, the steel pipe galvanizing pretreatment process has the following advantages:
the steel pipe galvanizing pretreatment process saves water, eliminates the discharge of waste water and eliminates the generation of industrial sludge through the circular arrangement of acid. The online deironing process of the solvent enables the solvent pool to be recycled, improves the deironing speed and the working efficiency, and reduces the energy loss.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic flow chart of a steel pipe galvanizing pretreatment process according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Take a galvanized steel pipe with a daily yield of 300 tons as an example.
The method comprises the steps of firstly enabling a steel pipe to enter an old acid pool to be soaked to remove oxide skins and impurities on the surface, then enabling the steel pipe to enter a new acid pool to further remove the oxide skins, enabling the oxide skins of the steel pipe to be reacted with acids in the old acid pool and the new acid pool to generate ferrous ions, leading concentrated hydrochloric acid into the new acid pool to enable the HCl concentration of the new acid pool to be kept within 12% -18%, enabling the surfaces of the steel pipe to have higher-concentration acid and ferrous ions after the steel pipe is thoroughly treated in the new acid pool, then enabling the steel pipe to be cleaned by high-concentration acid and ferrous ions on the surface of the steel pipe through a dilute acid pool I and a dilute acid pool II, enabling the steel pipe after the steel pipe passes through the dilute acid pool II to be attached with a small amount of acid and a small amount of ferrous chloride, enabling the steel pipe to enter a solvent pool, and enabling the solvent pool to have 190g/L of NH4Cl and ZnCl of 220g/L2After the steel pipe enters the solvent pool, acid and ferrous chloride attached to the surface of the steel pipe are dissolved in the solvent pool to pollute the solvent, the polluted solvent in the solvent pool enters the pipeline and is mixed with hydrogen peroxide and ammonia water on line in the pipeline, and hydrogen peroxide is consumed0.08t, 0.16t of ammonia water is consumed, simultaneously 0.15t of filtrate is rinsed by adding solvent mud, ferrous ions are oxidized into ferric ions through the joint reaction of hydrogen peroxide and ammonia water, the ferric ions are hydrolyzed to obtain ferric hydroxide precipitate, and acid reacts with the ammonia water to generate ammonium chloride.
Obtaining a filter cake, namely solvent mud, by a plate filter press: precipitating ferric hydroxide for 0.2t, and returning the filtrate to the solvent pool. And (3) carrying out three-stage rinsing and filter pressing on the solvent mud in an iron black workshop, returning the rinsing filtrate of the solvent mud to a solvent tank of a production line, dissolving the obtained filter cake by waste acid, adding alkali, heating, and then converting to generate iron black (ferroferric oxide), thereby realizing zero discharge of sludge.
The fresh acid pool, the old acid pool and the waste acid pool are operated along with the process, wherein the Baume degree of the acid is changed along with the operation of the process, when the Baume degree of the acid in the fresh acid pool reaches 30, the fresh acid pool becomes the old acid pool, when the Baume degree of the acid in the old acid pool reaches 40, the waste acid pool is formed, the waste acid pool is distilled at low temperature, the distilled recycled dilute hydrochloric acid enters the dilute acid pool II, the Baume degree of the dilute acid pool II is kept to be smaller than 8, the dilute hydrochloric acid in the dilute acid pool II flows to the dilute acid pool I through a connected pipeline by utilizing the static pressure of the liquid level, the Baume degree of the dilute acid pool I is kept to be smaller than 15, the dilute hydrochloric acid in the dilute acid pool I flows to the new acid pool through the connected pipeline by utilizing the static pressure of the liquid level, and is mixed with the concentrated hydrochloric acid in the fresh acid pool, and the HCl concentration of the. No additional water is added into the system during the production process except that new concentrated hydrochloric acid is added into the system. Meanwhile, sewage is not discharged outside, and zero discharge of water is realized. The produced solvent mud is rinsed, filter-pressed and recycled to rinse filtrate, waste acid is added into filter cakes to dissolve, alkali is added to heat up to prepare ferroferric oxide (iron black), thereby changing waste into valuable and not discharging sludge.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (7)
1. A steel pipe galvanizing pretreatment process is characterized in that: comprises an acid treatment process, a two-stage dilute hydrochloric acid cleaning process and a solvent treatment process from front to back,
the acid treatment process comprises a new acid pool, an old acid pool and a waste acid pool, wherein the new acid pool is injected with concentrated hydrochloric acid;
the two-stage dilute hydrochloric acid cleaning process comprises two-stage dilute acid pools;
the solvent treatment process comprises a solvent pool and an online iron removal process, wherein the online iron removal process is used for oxidizing and precipitating ferrous ions in the solvent pool and preparing ferroferric oxide;
the steel pipe flow is as follows:
the steel pipe firstly passes through an old acid tank and a new acid tank to remove rust and oxide skin, then enters a two-stage cleaning process, acid and ferrous ions on the surface of the steel pipe are washed away by using a dilute acid tank, finally a layer of uniform solvent film is formed on the surface of the steel pipe by passing through a solvent tank, and then the steel pipe enters a galvanizing process;
the acid flow is as follows:
adding concentrated hydrochloric acid into a new acid pool, enabling the solution in the new acid pool to enter an old acid pool after use, enabling the solution in the old acid pool to enter a waste acid pool after reuse, enabling recycled dilute hydrochloric acid obtained by the waste acid pool through a low-temperature distillation technology to enter a dilute acid pool for two-stage cleaning, and enabling the solution in the dilute acid pool to enter the new acid pool and the concentrated hydrochloric acid after use to prepare the new acid according to a proportion;
the HCl concentration of the new acid pool is kept at 12% -18%, when the acid Baume degree of the new acid pool reaches 30, the new acid pool is judged to be an old acid pool, the acid Baume degree of the old acid pool is larger than 40, and when the acidity in the acid is detected to be smaller than 1, the new acid pool is judged to be a waste acid pool, the acid in the waste acid pool is distilled out of dilute hydrochloric acid through a low-temperature distillation technology at 110 ℃, the distilled dilute hydrochloric acid returns to the dilute acid pool for recycling, and the residual liquid containing ferrous chloride after distillation is crystallized to obtain ferrous chloride solid.
2. The steel pipe galvanizing pretreatment process according to claim 1, characterized in that: the dilute acid pool comprises a dilute acid pool I and a dilute acid pool II, the steel pipe firstly enters the dilute acid pool I after coming out of the new acid pool and then enters the dilute acid pool II, and the recycled dilute hydrochloric acid distilled from the waste acid pool enters the dilute acid pool II.
3. The steel pipe galvanizing pretreatment process according to claim 1, characterized in that: the on-line iron removal process is that the solvent is mixed with hydrogen peroxide and ammonia water on line in the process of introducing the solvent into a sedimentation tank from a solvent tank through a pipeline, the pH value is controlled to be 4.8-5.0 to form ferric hydroxide precipitate, then the ferric hydroxide precipitate is introduced into a plate type filter press to be subjected to filter pressing, the filtrate returns to the solvent tank to be recycled, and simultaneously, a filter cake, namely the solvent mud, is obtained.
4. The steel pipe galvanizing pretreatment process according to claim 1, characterized in that: the solvent pool contains 170-210 g/L NH4Cl, ZnCl of 210-250 g/L2。
5. The steel pipe galvanizing pretreatment process according to claim 3, characterized in that: the adding molar ratio of hydrogen peroxide to ammonia water is 1: 4.
6. the steel pipe galvanizing pretreatment process according to claim 3, characterized in that: the solvent is mixed with hydrogen peroxide and ammonia water in the pipeline for not less than 3 min.
7. The steel pipe galvanizing pretreatment process according to claim 3, characterized in that: dissolving the solvent mud by waste acid, adding alkali, heating, and converting to generate iron black.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810862511.2A CN108914136B (en) | 2018-08-01 | 2018-08-01 | Steel pipe galvanizing pretreatment process |
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| CN201810862511.2A CN108914136B (en) | 2018-08-01 | 2018-08-01 | Steel pipe galvanizing pretreatment process |
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| CN108914136A CN108914136A (en) | 2018-11-30 |
| CN108914136B true CN108914136B (en) | 2020-08-18 |
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| CN108842130B (en) * | 2018-07-12 | 2020-05-12 | 中国航发哈尔滨轴承有限公司 | Method for modifying surface of spherical roller by using special tool for chemical heat treatment of spherical roller |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN204779769U (en) * | 2015-06-17 | 2015-11-18 | 北京钢研新冶精特科技有限公司 | Hot dip galvanization line |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN204779769U (en) * | 2015-06-17 | 2015-11-18 | 北京钢研新冶精特科技有限公司 | Hot dip galvanization line |
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