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WO2003035934A1 - Procede et appareil de recyclage de solutions de decapage contenant du peroxyde - Google Patents

Procede et appareil de recyclage de solutions de decapage contenant du peroxyde Download PDF

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Publication number
WO2003035934A1
WO2003035934A1 PCT/CA2002/001598 CA0201598W WO03035934A1 WO 2003035934 A1 WO2003035934 A1 WO 2003035934A1 CA 0201598 W CA0201598 W CA 0201598W WO 03035934 A1 WO03035934 A1 WO 03035934A1
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WO
WIPO (PCT)
Prior art keywords
solution
acid
nanofiltration
pickling
peroxide
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.)
Ceased
Application number
PCT/CA2002/001598
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English (en)
Inventor
Craig J. Brown
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eco Tec Inc
Original Assignee
Eco Tec Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Eco Tec Inc filed Critical Eco Tec Inc
Publication of WO2003035934A1 publication Critical patent/WO2003035934A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027—Nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/04—Feed pretreatment
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/04—Specific process operations in the feed stream; Feed pretreatment

Definitions

  • the present invention relates to a process for pickling metals in acid solutions containing high concentrations of hydrogen peroxide. Means is provided to recover spent pickling solution that has become contaminated with dissolved metals.
  • the steel typically is rolled and then annealed to achieve the desired structure and material properties. Because annealing is carried out in the presence of air, a film of oxide forms on the surface of the steel.
  • the film of oxide is fairly porous and contains small cracks. A zone that is depleted of chromium is normally formed under the oxide film.
  • a process called pickling is used to clean and condition the surface of the metal after annealing.
  • the pickling of stainless steel requires three distinct processes. The first is removal of the thermally grown scale for appearance purposes and to facilitate cold working of the steel. The second process increases the corrosion resistance of the final product by dissolving the chromium-depleted layer. During the third process, a minimum amount of bulk steel is dissolved, giving the desired brightening effect to the final product.
  • the first, scale removal step is often accomplished using shot blasting or electrolytic pickling in neutral salt.
  • the remaining two pickling steps are traditionally carried out in mixed acid solutions which typically contain 90-160 g L nitric acid and 10-40 g/L hydrofluoric acid
  • ferric iron in solution Fe 3+
  • ferrous iron Fe 2+
  • a byproduct of reaction (2) is nitrogen oxide gas (NO) which is emitted from the solution into the atmosphere.
  • NO nitrogen oxide gas
  • Control of fuming from mixed acid pickling baths is a major environmental issue.
  • Various techniques are employed to control these emissions including water scrubbing, caustic scrubbing, urea addition, selective catalytic reduction and hydrogen peroxide addition. Because of the difficulty in controlling nitrogen oxide emissions, a considerable effort has been invested by the industry in developing alternative 'nitrate-free' pickle bath chemistries that do not generate an air pollution problem.
  • a further disadvantage of the mixed acid pickling process is the generation of spent pickle liquors containing residual concentrations of nitrate. Water pollution control by treatment of this nitrate is also problematic and a major disadvantage of the mixed acid pickling process.
  • Nitrate-free processes such as the Henkel Cleanox process utilize peroxide to re-oxidize the ferrous iron to ferric, but do not operate with excess peroxide in the bath. Although the details are beyond the scope of this invention, there are conditions where the pickling process would be enhanced if an appreciable residual of peroxide were present in the pickling solution.
  • the present invention is concerned with nitrate-free stainless steel pickling baths that contain a significant concentration of hydrogen peroxide.
  • the pickling solution which has accumulated dissolved metal contamination
  • the nanofiltration process is used to concentrate the metals in the rejected pickling solution.
  • the permeate solution from the nanofiltration process which has a reduced metal concentration, is recycled back to the pickling process for reuse.
  • the temperature of the solution being fed to the nanofiltration process is cooled to a temperature of less than 10°C.
  • the reject solution from the nanofiltration process can optionally be further processed by a sorption unit such as an acid retardation unit or a diffusion dialysis unit, capable of sorbing the acid values contained in the nanofiltration reject solution.
  • a sorption unit such as an acid retardation unit or a diffusion dialysis unit, capable of sorbing the acid values contained in the nanofiltration reject solution.
  • the acid that is sorbed is then recovered from the sorption unit by desorption with water.
  • the residual hydrogen peroxide in the reject must be reduced.
  • Nanofiltration membranes and most common construction materials are not chemically resistant to peroxide containing pickling solutions. Moreover, if dissolved metals are concentrated in the pickling solution by a process such as nanofiltration, the peroxide decomposes at an unacceptably high rate due to the catalytic effect of the metal ions.
  • Figs. 1 and 2 are graphs illustrating hydrogen peroxide decomposition over time.
  • Fig. 1 shows the results of an experiment that was conducted to show the effect of iron concentration on peroxide decomposition at a normal pickling bath temperature and
  • Fig. 2 is a similar graph showing the results of a laboratory test in accordance with the process according to the invention.
  • Fig. 3 is a schematic illustration of an apparatus according to a preferred embodiment of the invention.
  • Equation (5) also implies that the stability of peroxide is improved at higher acid concentration.
  • the potential advantage of improved peroxide stability by use of higher acidity solutions is also obviated by the increased cost of acid neutralization of the spent pickle liquor.
  • NF membranes have become commercially available which are capable of separating dissolved metal contamination from strong mineral acids.
  • spent pickle liquor is pumped past the membrane surface at high pressure.
  • the membrane allows free acid to permeate through, while metal salts are largely rejected.
  • the collected permeate contains free acid at about the original feed concentration and a metal concentration at about 10-30% of the initial level.
  • the permeate can be recycled back to the pickle bath.
  • the reject also contains free acid at about the original bath concentration, however the metal concentration can be increased several fold above the original level.
  • the reject is typically discarded as waste. Since the acid to metal concentration ratio in the reject is much less than the feed solution, the NF system can be a reasonably effective recovery system under many circumstances.
  • the NF process has a number of advantages over the acid retardation process for this application.
  • the flow rate of waste solution can be significantly less that the feed.
  • the flow rate of the waste is typically the same or greater than the feed flow.
  • NF has the ability to treat solutions containing relatively low metal concentrations.
  • Acid retardation systems on the other hand are sized based upon feed flow, independent of metal concentration. Generally speaking, acid retardation systems are more attractive at high pickle bath metal concentrations and NF systems are more attractive at low metal concentrations. Temperature has a well-known effect on pressure driven membrane processes such as reverse osmosis and nanofiltration.
  • the peroxide concentration reduction was less than 5% after four hours.
  • the spent pickle liquor is reduced in temperature, below normal pickling bath temperatures before being processed by the nanofiltration process. This avoids decomposition of the peroxide as the metal concentration is increased in the NF process.
  • acid resistant NF membranes include MPT-34 from Koch Membranes Systems, DS-5 from Osmonics and N30F from Nadir Systems. While these membranes have good tolerance to relatively high concentrations of acids such as sulfuric acid, their resistance to strong oxidizing agents is limited.
  • the experiment was conducted at ambient temperatures (20-25°C) and at 5°C.
  • the membrane samples were withdrawn and tested for flux and rejection efficiency.
  • Tests were conducted with a 1% Na 2 SO 4 solution at ambient temperatures. According to the manufacturer's catalog, new membrane has a flux of 40-70 1/h/m 2 and a rejection efficiency of 85-95% at 580 psi. After 36 days immersion at room temperature, the flux decreased to 23 1/h/m 2 and the rejection decreased to 28%. This is an indication of severe membrane degradation.
  • Tests were also conducted at 6°C. At this temperature the membrane was found to have a flux of 53 1/h/m 2 and a rejection efficiency of 89.5% at the same pressure, after the same time period. This is an indication of only minor amounts of degradation, if any.
  • the hydraulic equipment including pump, pressure vessels and piping of an NF system represents a significant portion of the equipment cost.
  • the preferred material of construction is an austenitic stainless steel such as alloy 316. Since the fluid being treated here is actually used to pickle 316 stainless steel, some other more corrosion resistant alloy would normally be considered. Hydraulic components fabricated in exotic alloys such as alloy 20 are much more expensive than 316 stainless steel, however. It has been found that if the temperature of the feed is reduced, the corrosion rate of 316 stainless steel can be reduced to an acceptable level. An experiment was conducted to determine the corrosion rate of 316L stainless steel in peroxide pickle liquors. Samples of the metal were immersed in solution of the following composition:
  • the dissolved metal concentration in the solution was then analyzed after a period of time. From this information, the corrosion rate can be calculated.
  • the experiment was conducted at ambient temperatures (20-25 °C) and 6°C.
  • the corrosion rate at ambient temperature was found to be 0.052 inches per year (52 mils per year).
  • the corrosion rate at 6°C was found to be only 12 mils per year. Normally an allowable rate of corrosion is considered to be less than 20 mils per year. This confirms that 316L stainless steel is not a suitable material at temperatures at or above ambient, however it indicates that if the temperature is reduced significantly below ambient temperatures, the corrosion rate is acceptable and the material can be used.
  • the membranes are not resistant to peroxide under normal pickling conditions.
  • the concentration of peroxide in the reject was approximately 21% lower than that of the feed solution. This represents an apparent 21% rejection. A more likely explanation was that since the test was conducted at ambient temperatures, the peroxide partially decomposed due to the presence of a relatively high iron concentration in the feed solution.
  • a pilot plant was assembled containing a nanofiltration membrane element manufactured by Nadir with a surface area of 4.18 m 2 .
  • Acid pickling liquor containing hydrogen peroxide, sulfuric acid, hydrofluoric acid and iron was circulated through a chiller and the membrane module using a 316 stainless steel multi-stage centrifugal pump. The temperature of the solution was held at approximately 2-4°C and a back pressure of 518 psi was maintained on the membrane module. The average permeate flux was 10.6 L/m /h.
  • Table 2 No reduction in the hydrogen peroxide concentration in the feed solution was observed over the duration of the experiment. In addition, as can be seen from the data, there is no rejection of peroxide by the membrane.
  • U.S. patent 5,547,579 7 by the present inventor shows a way to integrate an acid sorption process such as acid retardation or diffusion dialysis with nanofiltration in order to increase the recovery efficiency of free acid.
  • Diffusion dialysis utilizes an ion exchange resin very similar to that employed in the acid retardation process.
  • the ion exchanger is in the form of a membrane, while in the acid retardation process, the ion exchanger is in particulate form.
  • the processes are analogous to each other in that acid is first sorbed into the ion exchanger and then extracted or eluted from the ion exchanger with water.
  • the reject from the nanofiltration process is treated by a sorption unit (ASU) such as an acid retardation unit like the Eco-Tec APU or a diffusion dialysis unit, in a similar way to that taught by U.S. patent 5,547,579, to improve the recovery efficiency of the acid.
  • ASU sorption unit
  • the NF reject stream feeding the ASU contains sulfuric acid, at about pickling bath concentration or slightly lower, and metal salt at an appreciably increased concentration.
  • the acid sorption unit will sorb the acid values.
  • the resulting solution leaving the ASU normally called the 'byproduct', will contain high concentrations of metal but very low concentrations of acid.
  • the byproduct normally is considered waste.
  • Water desorption of the ASU media will recover a solution called the 'product', which contains high concentrations of acid.
  • the ASU product could be recycled back to the pickle bath. Since the ASU product will contain small, but significant concentrations of metal, it could alternatively be fed back into the NF system.
  • FIG. 3 is a schematic illustration of an apparatus according to a preferred embodiment of this invention.
  • Stainless steel strip 1 is passed through a pickle bath comprising a tank 2 holding a peroxide containing pickling solution 3.
  • a pickle bath comprising a tank 2 holding a peroxide containing pickling solution 3.
  • Pickling solution is withdrawn from the pickling tank at 4 and its temperature is reduced by a chilling device 5.
  • the cooled pickling solution is then passed via line 6 to a nanofiltration system 7.
  • the permeate from the nanofilter containing a reduced metal concentration is recycled back to the pickling tank via line 8.
  • the peroxide As the metal is concentrated in the NF unit from an initial level of ⁇ 10 g/L (say 5 g/L) up to about 30 g/L, the peroxide remains stable and the permeate will contain peroxide at about the same level as present in the spent pickle liquor. The peroxide will begin to degrade however as the metal concentration is increased from say 30 g/L to 50 g/L. The permeate will not contain much peroxide at this point, however since by this time most of the peroxide has been recovered. The final NF reject has a high metal concentration say 30-50 g/L, but will contain little peroxide. Any residual peroxide can be removed by dosing with a chemical reducing agent such as sodium sulfite.
  • a chemical reducing agent such as sodium sulfite.
  • This reject solution is passed via line 9 to an acid sorption unit 10.
  • the reject solution from the NF can be held for a time in a tank and allowed to warm up a little, ensuring that any remaining peroxide will auto-decompose, so that the solution fed to the ASU will contain no peroxide. As a result, no chemicals will be required to destroy peroxide.
  • the acid in the solution fed to the ASU is taken up by the absorption media in the acid sorption unit and resulting byproduct solution 13 is collected as waste.
  • Water 11 desorbs acid from the acid sorption unit media and a product solution is collected and passes via line 12 back to the pickling tank.
  • this product solution which still contains some metal can be combined with the spent pickling solution and fed to the nanofiltration system again.
  • a significant portion of the operating cost of the system is associated with the energy to operate the chilling device. It will be apparent that the amount of energy will be reduced by using a heat exchanger in such a way so that the permeate from nanofiltration pre-cools the spent pickle liquor before passing to the chiller.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Nanotechnology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

L'invention concerne un procédé et un appareil permettant de recycler une liqueur usée qui contient de l'acide et du peroxyde d'hydrogène, provenant d'un procédé de décapage de métal. La température de la liqueur de décapage usée est réduite à une température inférieure à celle du procédé de décapage, puis la liqueur est ensuite traitée au moyen d'un procédé de nanofiltration afin que soit obtenue une solution de perméat présentant une concentration en métal réduite, qui est récupérée après le procédé de nanofiltration et recyclée pour le procédé de décapage de métal.
PCT/CA2002/001598 2001-10-25 2002-10-24 Procede et appareil de recyclage de solutions de decapage contenant du peroxyde Ceased WO2003035934A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US33057201P 2001-10-25 2001-10-25
US60/330,572 2001-10-25

Publications (1)

Publication Number Publication Date
WO2003035934A1 true WO2003035934A1 (fr) 2003-05-01

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PCT/CA2002/001598 Ceased WO2003035934A1 (fr) 2001-10-25 2002-10-24 Procede et appareil de recyclage de solutions de decapage contenant du peroxyde

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010082194A2 (fr) 2009-01-13 2010-07-22 B.P.T. Bio Pure Technology Ltd. Membranes stables aux solvants et aux acides, leurs procédés de fabrication et leurs procédés d'utilisation entre autres pour séparer des ions métalliques de courants de traitement liquides
DE102007007324B4 (de) * 2006-02-27 2013-10-17 Andritz Ag Verfahren zur Entstickung der Abgase aus Glüh- und Beizlinien, sowie Glüh- und Beizlinie, insbesondere für Edelstahl-Warm- oder Kaltband

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0654546A1 (fr) * 1993-11-24 1995-05-24 Piet De Vries Procédé et installation de décapage
US5547579A (en) * 1995-01-20 1996-08-20 Eco-Tec Limited Process and apparatus for purification of contaminated acids
DE19740164A1 (de) * 1997-09-12 1999-03-18 Steuler Industriewerke Gmbh Verfahren zur Aufbereitung von metallhaltigen Säurelösungen aus Oberflächenbehandlungsanlagen
DE19829592C1 (de) * 1998-07-02 1999-12-09 Umweltanalytisches Zentrum Gro Verfahren zur Aufbereitung metallhaltiger Mineralsäuren

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0654546A1 (fr) * 1993-11-24 1995-05-24 Piet De Vries Procédé et installation de décapage
US5547579A (en) * 1995-01-20 1996-08-20 Eco-Tec Limited Process and apparatus for purification of contaminated acids
DE19740164A1 (de) * 1997-09-12 1999-03-18 Steuler Industriewerke Gmbh Verfahren zur Aufbereitung von metallhaltigen Säurelösungen aus Oberflächenbehandlungsanlagen
DE19829592C1 (de) * 1998-07-02 1999-12-09 Umweltanalytisches Zentrum Gro Verfahren zur Aufbereitung metallhaltiger Mineralsäuren

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007007324B4 (de) * 2006-02-27 2013-10-17 Andritz Ag Verfahren zur Entstickung der Abgase aus Glüh- und Beizlinien, sowie Glüh- und Beizlinie, insbesondere für Edelstahl-Warm- oder Kaltband
WO2010082194A2 (fr) 2009-01-13 2010-07-22 B.P.T. Bio Pure Technology Ltd. Membranes stables aux solvants et aux acides, leurs procédés de fabrication et leurs procédés d'utilisation entre autres pour séparer des ions métalliques de courants de traitement liquides
US9205383B2 (en) 2009-01-13 2015-12-08 Ams Technologies Int. (2012) Ltd Solvent and acid stable membranes, methods of manufacture thereof and methods of use thereof inter alia for separating metal ions from liquid process streams
US9943811B2 (en) 2009-01-13 2018-04-17 Ams Technologies In. (2012) Ltd Solvent and acid stable membranes, methods of manufacture thereof and methods of use thereof inter alia for separating metal ions from liquid process streams

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