EP1515923A1 - Procede permettant de reduire et de surveiller la concentration en hexafluorosilicate lors du polissage d'objets en verre dans un bain de polissage contenant de l'acide sulfurique ainsi que de l'acide fluorhydrique - Google Patents

Procede permettant de reduire et de surveiller la concentration en hexafluorosilicate lors du polissage d'objets en verre dans un bain de polissage contenant de l'acide sulfurique ainsi que de l'acide fluorhydrique

Info

Publication number
EP1515923A1
EP1515923A1 EP03740288A EP03740288A EP1515923A1 EP 1515923 A1 EP1515923 A1 EP 1515923A1 EP 03740288 A EP03740288 A EP 03740288A EP 03740288 A EP03740288 A EP 03740288A EP 1515923 A1 EP1515923 A1 EP 1515923A1
Authority
EP
European Patent Office
Prior art keywords
polishing
bath
sulfate
potassium
fluoride
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.)
Withdrawn
Application number
EP03740288A
Other languages
German (de)
English (en)
Inventor
Erich Sälzle
Marcus Sälzle
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of EP1515923A1 publication Critical patent/EP1515923A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C15/00—Surface treatment of glass, not in the form of fibres or filaments, by etching
    • C03C15/02—Surface treatment of glass, not in the form of fibres or filaments, by etching for making a smooth surface

Definitions

  • the present invention relates to a process for reducing and controlling the concentration of hexafluorosilicate ions formed when polishing glass objects in a polishing bath containing sulfuric acid and hydrofluoric acid, potassium fluoride, potassium sulfate, sodium fluoride, sodium sulfate or aluminum sulfate being added to the polishing bath or the sulfuric acid washing bath in such an amount that a Falling the fluoride ion concentration below the optimal working range is avoided.
  • a salt coating which essentially consists of sulfates, fluorides and silicon fluorides, is formed on the glass surface due to the reaction with the glass components during acid polishing of the cations contained in the glasses. This salt deposit must then be removed by a washing process in order not to hinder the further polishing process.
  • the glasses are usually immersed in an acid polishing bath which contains about 45-60% sulfuric acid and 2.5-5% hydrofluoric acid, and the salt coating which forms on the surface is then removed from the cuts and the like in a water bath or preferably in a sulfuric acid wash bath washed bare glass surface.
  • an acid polishing bath which contains about 45-60% sulfuric acid and 2.5-5% hydrofluoric acid
  • SiF 4 silicon tetrafluoride
  • H 2 SiF 6 hexafluorosilicic acid
  • Alkali potassium 7-13% and sodium 3-57%
  • K 2 SiF 6 sodium hexafluorosilicate
  • the excess silicon tetrafluoride extracts hydrofluoric acid from the polishing bath to form hexafluorosilicic acid and is dissolved both in the polishing bath and in the washing bath and accumulates in the baths over the course of several polishing cycles. Since the hexafluorosilicic acid is more dissociated than the hydrofluoric acid, the fluoride ion component is pushed back to the extent that the baths are used for a longer period of time so that a homogeneous attack on the glass surface no longer takes place. Since the proportion of hydrofluoric acid can no longer be increased, the polishing speed decreases considerably in the course of a shift.
  • the polishing process according to the prior art usually has to be interrupted because of the strong accumulation of salts and hexafluorosilicate, so that the potassium or sodium hexafluorosilicate which has not yet separated out at the polishing bath temperature is excreted after cooling.
  • the object of the invention is therefore to provide a method for reducing and controlling the hexafluorosilicic acid concentration when polishing glass objects in a polishing bath containing sulfuric acid and hydrofluoric acid, which has a high removal rate, while the working capacity of the polishing bath is extended.
  • Another object of the present invention is to increase the performance of the polishing bath and the sulfuric acid washing bath, while the consumption of sulfuric acid and hydrofluoric acid and special cleaning measures are to be kept as low as possible.
  • the method according to the invention is said to be particularly suitable for polishing glasses containing zinc or magnesium.
  • the object is achieved in that the polishing bath and / or
  • Sulfuric acid wash bath with potassium or sodium fluoride and / or potassium or sodium sulfate or aluminum sulfate is added.
  • potassium or sodium fluoride and / or potassium or sodium sulfate or aluminum sulfate is added.
  • the hexafluorosilicic acid or zinc hexafluorosilicate formed during the polishing process is precipitated, or the concentration is kept constant by the targeted precipitation.
  • the present invention is based on the finding that the dissolved and uncontrollably enriched hexafluorosilicic acid or the dissolved zinc hexafluorosilicate is the reason for the uncontrolled reduction in the dissociation of hydrofluoric acid and thus also for leaving the optimal concentration range in which the solubility of the formed Fluoride is no longer present. This manifests itself in a reduction in the reaction speed of the process.
  • the enrichment of the hexafluorosilicate during a shift takes place in an uncontrolled manner and can therefore only be countered with continuously extended polishing times and additional hydrofluoric acid additions per batch until the end of the shift.
  • hexafluorosilicic acid which is formed from silicon tetrafluoride, which forms during the polishing process in the polishing bath, and considerable amounts of hydrofluoric acid, is continuously or periodically removed from the solution by being precipitated by adding the metal fluorides or metal sulfates.
  • suitable for the process of the invention are those metal salts which are difficult to dissolve as metal hexafluorosilicate in the polishing bath and / or in the sulfuric acid wash bath, ie. H. cause a precipitation.
  • metal salts which are difficult to dissolve as metal hexafluorosilicate in the polishing bath and / or in the sulfuric acid wash bath, ie. H. cause a precipitation.
  • These include potassium fluoride, potassium sulfate, sodium fluoride, sodium sulfate and aluminum sulfate. Mixtures of different metal salts can also be used. It should be noted that the concentration of hexafluorosilicic acid must be reduced to such an extent that the control effect of the tartaric acid which may be used is not impaired.
  • the process according to the invention can be carried out both in the absence and in the presence of tartaric acid.
  • the hexafluorosilicic acid that forms during the polishing process is preferably precipitated as potassium hexafluorosilicate by adding potassium fluoride or potassium sulfate.
  • An advantage of the invention is that by precipitation of hexafluorosilicic acid with the help of potassium fluoride or potassium sulfate, the original state of the polishing bath or. of the sulfuric acid wash bath, ie, for example, as when starting with a fresh polishing bath, can be permanently preserved. This significantly improves the performance of the baths.
  • Precipitation of hexafluorosilicic acid with the aid of sodium fluoride, sodium sulfate or aluminum sulfate is somewhat more complex, since most of the hydrofluoric acid required for the process is also precipitated if the hexafluorosilicic acid ion is not exactly determined before the precipitation.
  • precipitation with aluminum sulfate has the advantage that the resulting Al 2 (SiF 6 ) 3 is much more insoluble than K 2 SiF 6 .
  • the sodium ion or potassium ion that forms during the polishing process is likewise precipitated by the dissolved hexafluorosilicic acid as sodium hexafluorosilicate or as potassium hexafluorosilicate.
  • An advantage of the present invention is that, in the absence of hexafluorokiseic acid in the polishing bath, the proportion of fluoride in the polishing bath can be significantly lower
  • Glass removal can then be controlled better and thus be lower with a better surface quality of the glass.
  • the polishing bath or the sulfuric acid washing bath is 2 to 10 g, preferably 2.5 to 4.5 g of metal fluoride or 3 to 15 g, preferably 5 to 8 g of metal sulfate per liter of polishing bath or sulfuric acid washing bath in a batch size between 150 and 500 glasses added.
  • metal fluoride or 3 to 15 g of metal sulfate are added to a polishing bath containing 45 to 65% by weight of sulfuric acid and 0.8 to 3.6% by weight of hydrofluoric acid
  • Metal fluoride or 5 to 8 g of metal sulfate particularly preferably 2.5 to 4.5 g of potassium fluoride.
  • metal fluorides and metal sulfates can also be used simultaneously.
  • the values given for the preferred quantities refer to certain basket sizes and thus batch sizes (vary between 150 to 500 glasses). Such a basket size holds e.g. B. about 200 champagne glasses with long stems or about 500 whiskey glasses, and requires one
  • Acid polishing volume from about 1000 to 1300 l polishing acid.
  • the transfer to other basket batch sizes is familiar to the person skilled in the art.
  • Another advantage of the present invention is that, with a low hydrofluoric acid content, the number of alternating treatments between the polishing bath and the washing bath can be significantly reduced. On the one hand, this can significantly reduce acid consumption, and on the other hand, the overall process of the polishing process can be significantly shortened.
  • the number of change treatments according to the pre-program (three special changes) can be reduced from 6 to 8 changes to 1 to 4 changes.
  • hydrofluoric acid concentration can be reduced from 3-5% to 1-3% in most polishing positions in the polishing bath.
  • evaporation of the hydrofluoric acid is considerably reduced by the lower hydrofluoric acid concentration, and thus the acid consumption is further reduced.
  • an advantage of the method according to the invention is that the polishing of the cut can be produced more quickly by the hydrofluoric acid attack, which is easier to control in the absence of disruptive hexafluorosilicates, and thus the total glass removal from approximately 5-6% to 3-5% with better results Surface quality can be reduced.
  • optimal polishing results can be achieved efficiently and inexpensively.
  • the hexafluorosilicic acid is preferably neutralized in the polishing bath with potassium fluoride and in the sulfuric acid wash bath with potassium sulfate.
  • This has the advantage that, by using potassium fluoride, more than a third of the hydrofluoric acid required for the polishing process is introduced via the solid potassium fluoride dissolved in sulfuric acid. This is done without the sulfuric acid-consuming entry of 25-30% water when using 70-75% hydrofluoric acid in the polishing bath.
  • the metal salts in particular potassium sulfate or potassium fluoride, can also be added after the polishing process in a rest step in the working container, settling container or storage container.
  • the working container is the reaction container for the polishing process or the working container for the sulfuric acid wash bath in the polishing systems.
  • additional settling tanks for the polishing acid and the sulfuric acid wash bath for sedimentation of the floating lead sulfate salts or other insoluble salts and, after cooling, for the separation of some of the dissolved salts are provided in almost all dipping and drum systems.
  • neutralization with potassium fluoride can take place in separate settling tanks, and the potassium hexafluorosilicate can be obtained very pure and as a valuable salt be given to the enamel or wood preservative industry.
  • Neutralization can also take place during the rest phase in the baths or in the settling tanks. To do this, air must be blown in for at least 10 minutes after adding the potassium sulfate or potassium fluoride to complete the reaction. Targeted neutralization also greatly reduces the amount of waste acid to be discarded.
  • hexafluorosilicic acid About 50% of the hydrofluoric acid used is usually absorbed in the absorption water of the absorption system as hexafluorosilicic acid. KF can be used to separate hexafluorosilicic acid from hydrofluoric acid.
  • the circulating water contains approx. 15-20% hexafluorosilicic acid and approx. 3-6% HF. If only 85-90% of the hexafluorosilicic acid is neutralized and no soluble KF is present, the solution can be used again to absorb the silicon tetrafluoride. This eliminates the difficult neutralization of the absorption water with lime milk and the expensive disposal of the pressed lime cake in a special landfill because of the high fluoride content.
  • the removal of hexafluorosilicic acid can be accelerated by blowing in the air, in particular filtered air.
  • Air blowing is decomposed into silicon tetrafluoride and hydrofluoric acid by locally generated negative pressure hexaflurosilicic acid and discharged with the exhaust air. This can be done both during and after the polishing process.
  • the method according to the invention can contain the additional step of adding oxalic acid.
  • This is particularly useful for glasses that contain zinc or magnesium.
  • glass melt different amounts of zinc and magnesium to reduce the lead immission were added.
  • Zinc oxide forms readily soluble silicon fluoride during the polishing process and magnesium is precipitated as insoluble MgF 2 .
  • the hexafluorosilicate content thus increases to the same extent with the enrichment of the zinc. Therefore, an increasing proportion of dissolved zinc hexafluorosilicate requires higher concentrations of hydrofluoric acid for the polishing process. This means that much higher hydrofluoric acid concentrations are required in both the polishing and sulfuric acid wash baths. The result is an approximately 20-30% higher consumption of hydrofluoric acid and an extension of the polishing time by up to 50%. In most cases, the positive advantages of the melting process had to be dispensed with.
  • Zinc ions and the corresponding hexafluorosilicate ions are jointly precipitated and thus removed by the targeted addition of potassium oxalate.
  • the zinc ions with oxalic acid and the hexafluorosilicic acid with KF can alternatively also be precipitated individually, with the addition of oxalic acid only being carried out to precipitate the zinc ions.
  • An excess of oxalic acid should be avoided due to the resulting undesirable known control function for fluoride and sulfate ions.
  • the determination of the preferably usable amounts of oxalic acid can be determined in the preliminary test by adding to the polishing bath up to the precipitation limit. It is preferred to add 0.05 to 1 g of oxalic acid per liter of polishing bath / batch for a batch size between 150 and 500 glasses to the polishing bath. Potassium oxalate (K 2 C 2 O 4 ) can also be added.
  • glasses with any zinc or magnesium content can be acid-polished without difficulty. This enables significant advantages in the melting process and in reworking.
  • Example 1 Precipitation / neutralization of H 2 SiF 6 with potassium fluoride or potassium sulfate
  • a goblet weighs on average between 300 and 400 g.
  • the glass removal during the polishing process averages between 5 and 6%.
  • the glass removal is between 15 to 18 g / glass for 300 g glasses and between 20 and 25 g / glass for 400 g glasses.
  • With an average loading of approx. 200 glasses per batch between 3000 and 4800 g glass per batch of 200 glasses are removed.
  • the proportion of Si0 2 in lead glasses is usually between 50 and 55%. This means that approximately 1500 to 2640 g Si0 2 are removed per batch.
  • hydrofluoric acid consumption is consequently reduced by 1 to 2 liters of hydrofluoric acid. Since approx. 50% of the silicon tetrafluoride escapes through evaporation in the absorption systems for the exhaust air, approx. 1.2 to 2 kg KF is required for the neutralization of the hexafluorosilicic acid.
  • the H 2 SiF 6 can also be precipitated using Al 2 (SO 4 ). Since the solubility of Al 2 SiF 6 is significantly lower than that of K 2 SiF 5 , precipitation with Al 2 (SiF 6 ) 3 would be preferable. However, since the solubility of AIF 3 as compared to KF is very low, the proportion of H 2 SiF 6 before the precipitation must be accurately determined in the precipitation of Al 2 (SO 4) 3, not the free and for polishing required HF coprecipitate. Precipitation of the H 2 SiF 6 with KF is not as effective, but without problems with the co-precipitation of the fluoride.
  • the proportion of zinc oxide is currently 1.0 to 2.5% in the known glass compositions.
  • the glass removal during the polishing process averages between 5 and 6%.
  • the glass removal is between 15 and 18 g / glass for 300 g glasses and between 20 and 25 g / glass for 400 g glasses.
  • With an average loading of approx. 200 glasses per batch between 3000 and 4800 g glass per batch of 200 glasses are removed.
  • the proportion of ZnO in lead glasses is usually between 1.0 and 2.5%. This means that approx. 30 to 120 g ZnO are removed per batch.
  • potassium oxalate K 2 C 2 O 2
  • 45 g ZnO can also be precipitated with approx. 50 g oxalic acid (or with 133 g oxalic acid for 120 g ZnO).
  • the corresponding proportion of silicon fluoride can be precipitated separately with KF. Approx.
  • Oxalic acid can be added to the baths. Since the proportion of zinc oxide is relatively small, the rapidly increasing stabilization of the hexafluorosilicication only becomes noticeable after the baths have been used for a long time. With regular precipitation of the zinc by adding appropriate amounts of oxalic acid, the H 2 SiF 6 concentrations remain stable both in the polishing bath and in the sulfuric acid wash bath and the polishing speed is no longer reduced by the zinc content in the glass. Zinc precipitation also avoids the susceptibility to pimples on the uncut glass surface.
  • the SiF 4 and HF evaporating in the absorption systems is absorbed there as H 2 SiF 6 and can be pumped out after reaching the permissible concentration of 15-20% and the H 2 SiF 6 can be precipitated separately with KF there and thus separated from the free HF , The released HF can in turn be used for the absorption of the SiF 4 .

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Surface Treatment Of Glass (AREA)
  • ing And Chemical Polishing (AREA)

Abstract

L'invention concerne un procédé permettant de réduire et de surveiller la concentration en ions hexafluorosilicate lors du polissage d'objets en verre dans un bain de polissage contenant de l'acide sulfurique ainsi que de l'acide fluorhydrique. L'invention est caractérisée en ce que du fluorure de potassium, du sulfate de potassium, du fluorure de sodium, du sulfate de sodium ou du sulfate d'aluminium est ajouté au bain de polissage ou au bain de lavage à l'acide sulfurique, selon une quantité qui permet d'empêcher que la concentration en ions fluorure ne chute en dessous de la plage d'opération optimale.
EP03740288A 2002-06-24 2003-06-18 Procede permettant de reduire et de surveiller la concentration en hexafluorosilicate lors du polissage d'objets en verre dans un bain de polissage contenant de l'acide sulfurique ainsi que de l'acide fluorhydrique Withdrawn EP1515923A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10228116 2002-06-24
DE10228116A DE10228116A1 (de) 2002-06-24 2002-06-24 Verfahren zum Polieren von Glasgegenständen
PCT/EP2003/006487 WO2004000747A1 (fr) 2002-06-24 2003-06-18 Procede permettant de reduire et de surveiller la concentration en hexafluorosilicate lors du polissage d'objets en verre dans un bain de polissage contenant de l'acide sulfurique ainsi que de l'acide fluorhydrique

Publications (1)

Publication Number Publication Date
EP1515923A1 true EP1515923A1 (fr) 2005-03-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP03740288A Withdrawn EP1515923A1 (fr) 2002-06-24 2003-06-18 Procede permettant de reduire et de surveiller la concentration en hexafluorosilicate lors du polissage d'objets en verre dans un bain de polissage contenant de l'acide sulfurique ainsi que de l'acide fluorhydrique

Country Status (7)

Country Link
US (1) US20050230355A1 (fr)
EP (1) EP1515923A1 (fr)
JP (1) JP2005534595A (fr)
CN (1) CN1662464A (fr)
AU (1) AU2003279390A1 (fr)
DE (1) DE10228116A1 (fr)
WO (1) WO2004000747A1 (fr)

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JP4324742B2 (ja) * 2006-04-28 2009-09-02 シャープ株式会社 研磨ガラス基板の製造方法
FR2929609B1 (fr) * 2008-04-07 2010-05-28 Seppic Sa Composition de depolissage de verre exempte d'ions ammonium et d'ions bifluorure
JP5392576B2 (ja) * 2008-07-09 2014-01-22 滋 木谷 けい素、チタンおよびふっ素の回収方法
CN103086608A (zh) * 2011-11-04 2013-05-08 景志杰 一种手机屏幕玻璃蒙砂粉
US9926225B2 (en) * 2011-12-30 2018-03-27 Corning Incorporated Media and methods for etching glass
CN104045241B (zh) * 2014-06-16 2016-09-14 刘存海 一种微氟玻璃蚀刻抛光方法
US10144850B2 (en) * 2015-09-25 2018-12-04 Versum Materials Us, Llc Stop-on silicon containing layer additive
CN105330165B (zh) * 2015-10-19 2018-04-17 上海光和光学制造大丰有限公司 一种用于加工防眩玻璃的蚀刻液及其制备方法
CN105330166B (zh) * 2015-11-24 2018-03-06 陈锋 一种环保型的玻璃蒙砂液及其制备方法
JPWO2017111091A1 (ja) * 2015-12-24 2018-03-29 パナソニック株式会社 ガラス用研磨液および研磨方法
CN107098595B (zh) * 2017-04-20 2019-11-05 通威太阳能（合肥）有限公司 一种提高刻蚀药液寿命的工艺
CN107737764A (zh) * 2017-10-25 2018-02-27 信利半导体有限公司 一种去除玻璃蚀刻残留物的方法
CN109777670A (zh) * 2019-03-14 2019-05-21 惠州市清洋实业有限公司 一种清洗液及其制备方法
CN114380304B (zh) * 2022-01-21 2023-05-30 云南磷化集团有限公司 一种对氟硝基苯用原料氟化钾的短流程制备方法

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US3560281A (en) * 1967-10-02 1971-02-02 Owens Illinois Inc Process for regenerating an acid bath
GB1309333A (en) * 1970-01-19 1973-03-07 Glaverbel Process for bending glass
DE3120711C2 (de) * 1979-12-07 1983-09-01 Erich Dr. 8000 München Sälzle Verfahren zum Polieren von Glasgegenständen
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Also Published As

Publication number Publication date
JP2005534595A (ja) 2005-11-17
AU2003279390A1 (en) 2004-01-06
CN1662464A (zh) 2005-08-31
US20050230355A1 (en) 2005-10-20
DE10228116A1 (de) 2004-01-29
WO2004000747A1 (fr) 2003-12-31

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