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WO1994007658A1 - Agent de decapage et procede d'elimination de revetements - Google Patents

Agent de decapage et procede d'elimination de revetements Download PDF

Info

Publication number
WO1994007658A1
WO1994007658A1 PCT/NO1993/000137 NO9300137W WO9407658A1 WO 1994007658 A1 WO1994007658 A1 WO 1994007658A1 NO 9300137 W NO9300137 W NO 9300137W WO 9407658 A1 WO9407658 A1 WO 9407658A1
Authority
WO
WIPO (PCT)
Prior art keywords
blasting
blasting agent
agent
water
sulphate
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/NO1993/000137
Other languages
English (en)
Inventor
Udo Müller
Oddbjørn Steen LARSEN
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.)
Norsk Hydro ASA
Original Assignee
Norsk Hydro ASA
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 Norsk Hydro ASA filed Critical Norsk Hydro ASA
Priority to AU51196/93A priority Critical patent/AU5119693A/en
Publication of WO1994007658A1 publication Critical patent/WO1994007658A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/08—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for polishing surfaces, e.g. smoothing a surface by making use of liquid-borne abrasives
    • B24C1/086—Descaling; Removing coating films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C11/00—Selection of abrasive materials or additives for abrasive blasts

Definitions

  • the present invention relates to a blasting agent comprising a water-insoluble compound and a process for removing coatings, like paints, oxides, scales and the like from metal, alloys, composites and similar coating substrates by means of blasting media.
  • Sand blasting and other abrasive techniques are quite applicable on hard, durable substrate like granite or hard steel, but requires special arrangements to meet the specification related to environment and working conditions.
  • the main object of the present invention was to select blasting agents for cleaning and removing coatings where the agents also should be environmentally acceptable and not possess the limitations and disadvantages of known agents.
  • Another object was to arrive at an improved process for cleaning substrate without damaging, mechanically or chemically, the substrate surface.
  • the inventors were first of all looking for those applicable for removing coatings without damaging the surface of the substrate. It should also be possible to clean completely structures and equipment having complex geometrical configurations such as valves, bridges etc. having parts which were difficult to arrive at with the cleaning equipment or blasting jets. After having cleaned the substrate it should be easy to remove the cleaning agent together with the removed coating and the cleaning agent itself should be environmentally acceptable.
  • CaC0 3 is a precipitate or more precisely an agglomerate of small par ⁇ ticles.
  • the agglomerates were found to be predominantly of spherical shape and having a particle size range of 10-200 ⁇ m, the main fraction being in the range 40-80 ⁇ m.
  • the Mohs hardness of these agglomerates was in the same range as for dolomite, but in spite of that they proved to be far less damaging to the substrate surface when used as blasting agent.
  • the cleaning effect was surprisingly similar to that of crushed dolomite. The reason for this is not quite clear.
  • One possible explanation could be that the spherical shape of the particles results in less scratching of the surface.
  • Another explanation might be that the agglomerates partly disintegrate during the treatment and are less rough on the surface as it thereby is treated with rather small particles also.
  • Precipitated water-insoluble carbonates or mixtures thereof can easily be produced with various known methods. Also other types of precipitated water-insoluble carbonates than the so-called convertation lime were tested and found equally applicable as blasting agent.
  • the caking properties and flow characteristics of the precipi ⁇ tated carbonates were also tested and compared to those of sodium bicarbonate. These tests proved that the precipitated carbonates were free-flowing and no special anticaking agent was necessary for the conditions in question. This new blasting agent could easily be removed by flushing with water after treatment for removing the coating from the substrate.
  • the additional agent should be of a more crystalline nature and alkali sulphate, and/or magnesium sulphate were found to be suitable for this purpose. Magnesium sulphate in the form of kieserite was found to be particularly useful. The amount of the sulphate agent should not be too high as the sulphate tends to absorb water which may result in plugging of valves of the blasting equipment.
  • Applicable working pressures were found to be in the range of 25- 800 kPa, preferably 300-400 kPa.
  • the amount of agent should be in the range of 0.5-5 kg/min. from a 6 mm blasting nozzle, depending on the type of coating to be removed and the substrate. Blasting nozzles of 6-11 mm will be applicable.
  • the blasting media comprising a slurry of 200-1000 g/1 of particles in water.
  • the agent's particle size and its distribution were not found to be critical. For difficult coatings like rust it was preferred to use relatively large particles and high blasting pressure. The limitations were mainly in the blasting equipment, especially the nozzles, used.
  • the particle size should preferably be below 500 ⁇ m, preferably below lOO ⁇ m. Most advantageous particles are substantially spherical in shape and being agglomerates of particles of a size of less than 5 ⁇ m.
  • Figs. la,b show SEM pictures of unpurified crushed dolomite.
  • Figs. 2a,b show SEM pictures of unpurified precipi ⁇ tated CaC0 3 .
  • Figs, la and lb show SEM (scanning electromicroscope) pictures of crushed dolomite in which 1 cm represents lOO ⁇ m and l ⁇ m, respectively. The crystalline structure of the dolomite particles can clearly be seen from these SEM pictures, especially from Fig. lb.
  • Figs. 2a and 2b show similar SEM pictures of precipitated CaC0 3 , derived from the conversion of calcium nitrate from a nitrophos- phate process.
  • Fig. 2a 1 cm corresponds to lOO ⁇ m
  • Fig. 2b 1 cm corresponds to lO ⁇ m.
  • the particle shown in Fig. 2b is about 60 ⁇ m, and it can clearly be seen that it is an agglomerate of tiny particles. Further, the predominantly spherical shape of the precipitated calcium carbonate is clearly demonstrated by these pictures.
  • a galvanized metal sheet and a substrate of brass were treated by blasting with precipitated calcium CaC0 3 suspended in water.
  • the treatment was performed at a blasting pressure of 340 kPa and a water pressure of 4000 kPa.
  • the average particle size of the CaC0 3 particles was 60 ⁇ m and the Mohs hardness was 3.0.
  • the smoothness i.e. the average depth (Ra-value)
  • the Ra-value (DIN 4768/1) is the arithmetical mean for the depth of the grooves and is an expression for the roughness of the surface.
  • High Ra-values means deep grooves.
  • a painted metal sheet having a paint layer of 40 ⁇ m was treated as described in Example 1.
  • the paint layer was removed completely. No damage of the metal surface could be observed.
  • This example shows removal of graphite paint from stone (Mexi- stone) under the same conditions as in Example 1, except that the blasting pressure was 260 kPa.
  • This example shows removal of graphite paint from glazed roof tiles.
  • the treatment conditions were as stated in Example 1, except that the water pressure now was 4500 kPa.
  • the graphite was completely removed without any damage to the substrate surface.
  • This example shows removal of painting from a steel surface.
  • the treatment conditions were as stated in Example 1 except for the applied blasting agent.
  • the blasting agent consisted of 75 weight% CaC0 3 and 25 weight% magnesium sulphate in the form of kieserite having an average particle size of 300 ⁇ m and a Mohs hardness of 3 1/2.
  • the paint coating was easily stripped off and removed from the steel surface together with the blasting agent by flashing with a water jet leaving a very smooth surface on the substrate. No damage of the substrate surface due to the treatment was observed.
  • the investigations and examples disclosed in the preceding description show that the inventors have succeeded in providing an improved process by applying a new blasting agent.
  • the process is most flexible with regard to removing various types of coatings from substrates having hardness from that of steel to wood without causing damage to the substrate surface.
  • the blasting agent can easily be removed by flushing with water. The person carrying out the cleaning process is not exposed to any harm and the agent is acceptable from an environmental point of view.
  • the agent is also available in desired qualities, particle size etc. and is relatively cheap.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paints Or Removers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

La présente invention se rapporte à un agent de décapage destiné à éliminer des revêtements tels que de la peinture, des oxydes, des écailles de fer, et autres, de métaux, alliages, composites et substrats similaires, et à un procédé d'élimination de ces revêtements. L'agent de décapage comprend un précipité ou un agglomérat de carbonate de calcium insoluble dans l'eau, de carbonate de magnésium ou autres mélanges, et 0 à 30 % en poids de sulfate alcalin et/ou de sulfate de magnésium. L'agent de décapage préféré est du carbonate de calcium précipité ou des agglomérats de celui-ci ayant une granulométrie de 10 à 200 νm et se composant de particules de CaCO3 précipité d'une granulométrie supérieure à 5 νm. Pour des surfaces dures, 20 à 30 % en poids de l'agent de décapage comporteraient un agent sulfaté. Le procédé est effectué à une pression de décapage de 50 à 800 kPa, de préférence de 200 à 400 kPa.
PCT/NO1993/000137 1992-09-25 1993-09-17 Agent de decapage et procede d'elimination de revetements Ceased WO1994007658A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU51196/93A AU5119693A (en) 1992-09-25 1993-09-17 Blasting agent and a process for removing coatings

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO923725 1992-09-25
NO923725A NO175807C (no) 1992-09-25 1992-09-25 Fremgangsmåte for fjerning av belegg samt blåsemiddel for fjerning av belegg

Publications (1)

Publication Number Publication Date
WO1994007658A1 true WO1994007658A1 (fr) 1994-04-14

Family

ID=19895466

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1993/000137 Ceased WO1994007658A1 (fr) 1992-09-25 1993-09-17 Agent de decapage et procede d'elimination de revetements

Country Status (3)

Country Link
AU (1) AU5119693A (fr)
NO (1) NO175807C (fr)
WO (1) WO1994007658A1 (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2325000A (en) * 1997-05-09 1998-11-11 Stephen William Rudman Blast cleaning using calcium carbonate
WO1998051901A1 (fr) * 1997-05-14 1998-11-19 Sofitech N.V. Materiau et procede de recurage pour tubes
WO2003061908A1 (fr) * 2002-01-24 2003-07-31 Exa Sa Procede de traitement d'une surface
WO2004084851A3 (fr) * 2003-03-24 2004-11-11 Exa Sa Composition de traitement
FR2875719A1 (fr) * 2004-09-28 2006-03-31 Appia Procede pour modifier la surface d'une couche d'asphalte
EP1647363A1 (fr) * 1998-12-04 2006-04-19 Farrow System Limited méthode pour enlever des revètements de la surface
EP2113339A1 (fr) 2008-04-30 2009-11-04 Omya Development AG Carbone de terre alcaline contenant un minéral pour le nettoyage de surface
EP1607373A4 (fr) * 2003-02-27 2011-10-26 Okutama Kogyo Co Ltd Carbonate de calcium spherique et procede de production associe
EP3045503A1 (fr) 2015-01-15 2016-07-20 Omya International AG Carbonate de calcium traité en surface avec une stabilité améliorée dans des environnements ayant un pH de 4,5 à 7

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL91624C (fr) * 1900-01-01
SE371668B (fr) * 1973-03-30 1974-11-25 Producem Ab
EP0374291A1 (fr) * 1988-12-21 1990-06-27 JOS Verwaltungs-GmbH & Co. Gesellschaft für Reinigungsverfahren KG Méthode pour le nettoyage de surfaces, en particulier de surfaces délicates
WO1990011163A2 (fr) * 1989-03-14 1990-10-04 Church & Dwight Co., Inc. Procede d'elimination de revêtements sur des substrats sensibles, et milieux de projection abrasifs utiles dans ledit procede

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL91624C (fr) * 1900-01-01
SE371668B (fr) * 1973-03-30 1974-11-25 Producem Ab
EP0374291A1 (fr) * 1988-12-21 1990-06-27 JOS Verwaltungs-GmbH & Co. Gesellschaft für Reinigungsverfahren KG Méthode pour le nettoyage de surfaces, en particulier de surfaces délicates
WO1990011163A2 (fr) * 1989-03-14 1990-10-04 Church & Dwight Co., Inc. Procede d'elimination de revêtements sur des substrats sensibles, et milieux de projection abrasifs utiles dans ledit procede

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2325000B (en) * 1997-05-09 2000-12-06 Stephen William Rudman Blast cleaning
GB2325000A (en) * 1997-05-09 1998-11-11 Stephen William Rudman Blast cleaning using calcium carbonate
WO1998051901A1 (fr) * 1997-05-14 1998-11-19 Sofitech N.V. Materiau et procede de recurage pour tubes
US6032741A (en) * 1997-05-14 2000-03-07 Schlumberger Technology Corporation Abrasives for well cleaning
GB2325260B (en) * 1997-05-14 2000-06-07 Sofitech Nv Abrasives for well cleaning
AU751473B2 (en) * 1997-05-14 2002-08-15 Schlumberger Technology B.V. Conduit cleaning material and process
EP1647363A1 (fr) * 1998-12-04 2006-04-19 Farrow System Limited méthode pour enlever des revètements de la surface
EP1666203A1 (fr) * 2002-01-24 2006-06-07 Exa SA Procédé d'enlèvement d'une couche d'une surface
WO2003061908A1 (fr) * 2002-01-24 2003-07-31 Exa Sa Procede de traitement d'une surface
EP1738872A1 (fr) * 2002-01-24 2007-01-03 Exa SA Agent pour l'exfoliation de peau
EP1607373A4 (fr) * 2003-02-27 2011-10-26 Okutama Kogyo Co Ltd Carbonate de calcium spherique et procede de production associe
WO2004084851A3 (fr) * 2003-03-24 2004-11-11 Exa Sa Composition de traitement
FR2875719A1 (fr) * 2004-09-28 2006-03-31 Appia Procede pour modifier la surface d'une couche d'asphalte
EP2113339A1 (fr) 2008-04-30 2009-11-04 Omya Development AG Carbone de terre alcaline contenant un minéral pour le nettoyage de surface
WO2009133173A1 (fr) * 2008-04-30 2009-11-05 Omya Development Ag Minéral contenant du carbonate alcalino-terreux pour nettoyage de surface
RU2498891C2 (ru) * 2008-04-30 2013-11-20 Омиа Девелопмент Аг Минерал, содержащий карбонат щелочноземельного металла, для очистки поверхности
US8597077B2 (en) 2008-04-30 2013-12-03 Omya International Ag Alkaline earth carbonate containing mineral for surface cleaning
CN102026776B (zh) * 2008-04-30 2015-11-25 Omya国际股份公司 用于表面清理的包含碱土金属碳酸盐的矿物
EP3045503A1 (fr) 2015-01-15 2016-07-20 Omya International AG Carbonate de calcium traité en surface avec une stabilité améliorée dans des environnements ayant un pH de 4,5 à 7
WO2016113285A1 (fr) 2015-01-15 2016-07-21 Omya International Ag Carbonate de calcium traité en surface doté d'une stabilité améliorée dans des environnements ayant un ph de 4,5 à 7

Also Published As

Publication number Publication date
NO923725L (no) 1994-03-28
AU5119693A (en) 1994-04-26
NO175807B (no) 1994-09-05
NO175807C (no) 1994-12-14
NO923725D0 (no) 1992-09-25

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