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Decontaminating galvanizing flux in situ
In the use of zinc ammonium chloride preflux in jobbing hot dip galvanizing, poor rinsing before flux dipping can result in contaminated flux. This then translates to higher Fe in flux solution causing excessive ash and dross production, consuming expensive zinc. The answer is prevention - by proper rinsing. But once the flux is contaminated, rectification is expensive also. Dumping the tank and making up a new solution costs in disposal, and new chemicals.
But is there a way to remove Fe and HCl from the flux in situ? (while retaining ther longer term usefulness of the flux)
Westfield, Scotland, UK
Iron content in preflux should not be exceed from 10g/L and also the ph should be maintain with in 4.0~5.5 if the ph below 4.0 the insoluble iron oxide covert in to soluble iron . oxidation of soluble iron content to be done by air continuous air purging or by using hydrogen peroxide treatmentSyed Kazmi
It is better to make a prevention action for the contamination of the flux tank from the first step of treatment.
You have to clean the surface very well before the fluxing step.
In the fluxing tank you have to add a wetting agent.
1)It dissolves light oxides that may have formed since pickling.
2)promotes fast drying thus increasing production and stop excessive sputtering and spitting as the steel enters the molten zinc.
Ahmed Fouad Serag Eldin
Ein Shams - Cairo - Egypt