Rinse water quality is essential in metal finishing. Excessive water hardness and high total dissolved solids (TDS) in the water can seriously impair coating performance. TDS are likely to be deposited on the metal parts during the rinsing process. Chlorides, sulfates, calcium, along with other minerals and chemicals can stick to the metal substrate as water evaporates. Water softening isn’t the solution because this merely replaces calcium and magnesium with sodium, which serves as the catalyst for premature corrosion, coating delamination, and other expensive coating failures.
Additionally, these contaminants can result in huge waste water disposal during the recovery process. Most recovery technologies carry with it the drag-out from the bath process to the rinse water. The contaminants from this drag-out, in turn, accumulate levels high enough to cause bath chemistry failure and huge solution disposal.
Careful monitoring is essential to limit these contaminants within the system but rinse water issues are rarely detected with casual inspection. So, in order to avoid contamination problems, finishers must first ensure the quality of their incoming water. Water to be used for bath and rinse recovery can be rid of these damaging contaminants using an industrial reverse osmosis system.
An industrial reverse osmosis system removes TDS concentrations that exist in the source water. It works by forcing the source water through a semi-permeable membrane using high pressure generated from a pump. The membrane only permits water molecules to pass through, filtering out dissolved contaminants. With this technology, not only is the coating performance significantly improved, it is also possible now to return the recovered chemical solution to the process bath and reuse the cleansed rinse water like new. By reusing valuable process chemicals, less fresh water is needed and less waste water has to be disposed of—resulting in a process that becomes more efficient and cost-effective.
Reverse osmosis is widely used in metal finishing operations like zinc, copper, nickel electroplating, nickel acetate seal, and black dye. But aside from this, it’s also used in other industries, such as food and beverage, pharmaceuticals, boiler feed water treatment for plantations and microelectronics.
Other systems have also been used for water desalination, specifically in states with coastal areas, such as California. If you’re interested to know more about how your metal finishing business can benefit from industrial reverse osmosis, manufacturers like AXEON Water Technologies can help design the system to fit your water filtration need.
Source: The Effect of Rinse Water Quality on Powder Coating Corrosion Resistance, Publisher, Paint and Coating Industry
Source: Recovery/Recycling Methods for Metal Finishers, Products FinishingGet a Quote