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Cleaning & Pretreating without the production of waste water a gentle way of preserving freshwater resources

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Lecture given at ECCA Autumn Congress - Brussels, Nov 23, 2010

Lecture given at ECCA Autumn Congress - Brussels, Nov 23, 2010

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  • This lecture is not about conversion coatings. Since already a few decades most of you make use of no-rinse conversion coatings, which are applied by chemcoater and dried in-place.
    This is all about the cleaning stage. Since the very beginning of our industry, when Joseph Hunter developed his first machines in the ’30s of the previous century, cleaning already took place with ”water & soap”, the so-called alkaline cleaners. Ever since alkaline cleaner are the industrial standard, however:

Transcript

  • 1. 1 Cleaning & Pretreating without the production of waste water a gentle way of preserving freshwater resources Environmental sound pretreatment system asEnvironmental sound pretreatment system as developed bydeveloped by Coil Coating Technologies BVCoil Coating Technologies BV Barry GroeneveldBarry Groeneveld
  • 2. 2 Cleaning & Pretreating without the production of waste water. • Clean water is essential for life as we know • 71% of earth surface is covered with water • only 0.6% is available as freshwater • Agriculture is using 70% of the freshwater resources • Presence of clean, potable water will be scarce • Existing sources should be protected well • Industrial processes should be minimised in water consumption • Effluents should be clean, but better not produce any effluents at all FACTSFACTS
  • 3. 3 Cleaning & Pretreating without the production of waste water. • they require very thorough rinsing, because • alkaline residues are detrimental for paint adhesion • initially excessive attack on aluminium → smut and fast build-up of aluminium in bath solution • tendency to form scale deposits at equipment, heating spirals, pipes, nozzles, etc. • regular dumps of bath needed (or even continuous overflow) • maintenance Alkaline cleaners are the industrial standard, however:
  • 4. 4 Cleaning & Pretreating without the production of waste water. • Especially developed by CCT for the Coil Coating Industry • Driving forces: waste reduction; environmental protection • Reduction of industrial water consumption with more then 95% • NO WASTE WATER dumps • Highly effective surfactants secure a good quality cleaning • 30 years of practical experience Acid Cleaning System (ACS)
  • 5. 5 Cleaning & Pretreating without the production of waste water. • Water based process, no VOCs • Liquid chemicals only → easy bath maintenance and adjustments • Easy process automation • Intermediate bath temperature; low energy consumption • Very long bath life span • Low chemicals consumption Acid Cleaning System (ACS)
  • 6. 6 Cleaning & Pretreating without the production of waste water. • Water refreshment of final rinse is regulated by evaporation losses of cleaning and rinsing baths. Conductivity final rinse is kept below 20 µS/cm • Preferably double set of squeegee rolls after each bath • Rinse water is counter cascaded to Cleaner bath (back-flow) • Composition of ACS chemical bath is compatible with conversion coating • No drain ! Acid Cleaning System (ACS) THE PRINCIPLESTHE PRINCIPLES
  • 7. 7 Cleaning & Pretreating without the production of waste water. • All baths are made up and replenished with DI water • Requires Stainless Steel equipment • Equilibrium drag-out  back-flow will be reached • Cleaner bath kept in good shape by continuous oil removal (oil separator) • Acidic solution preferentially dissolves Al-oxides and metallic impurities, without etching the Aluminium substrate • In practice Aluminium content in cleaner bath remains < 2.0 grams/liter Acid Cleaning System (ACS)
  • 8. 8 Cleaning & Pretreating without the production of waste water. • Mild acidic cleaner for steel and multi-metal lines (pH ~ 4.0) • Strong acidic cleaner for dedicated aluminium lines (pH ~ 2.0) • Initially fluoride-free. Complex fluorides may be added separately if additional etching is required (“dirty substrate”) Acid Cleaning System (ACS) TWO FLAVOURSTWO FLAVOURS
  • 9. 9 Cleaning & Pretreating without the production of waste water. • Often etching of aluminium is advised to remove metallic impurities in outer surface layer of the aluminium substrate • CCT has developed thick conversion coatings, with layer weight up to 1000 mg/m2 that incorporate the metallic impurities • These coatings contain complex fluorides, which etch the surface before the actual conversion coating is formed • As a result, the negative influence of alloying elements on the corrosion resistance is greatly neutralised • Application by chemcoater process → dried-in-place, no-rinse, no-waste • Adhesion properties comparable or better than conventional chromate + organic paint primer What about corrosion resistance?
  • 10. 10 Cleaning & Pretreating without the production of waste water. For a cleaner environment… without compromising cleaning quality… and with lower applied costs per sqm.
  • 11. 11 Cleaning & Pretreating without the production of waste water. QUESTIONS?
  • 12. 12 Cleaning & Pretreating without the production of waste water. THANK YOU!