49085

Drying process for waste zinc phosphate sludge  

June 20, 2008

The removal of zinc phosphate have become a nightmare with rising costs, is there any one attempting to dry this waste off before it consigning out, if so I would interested to know what method would best be used, remembering Health and safety practices.
Many Thanks

Pauline Burley
Process Technician e-coat - UK

Look into filter presses. Phosphate precipitates are a slimy mess, so watch which filter "cloth" you use. Also consider using magnesium oxide for the initial portion of the neutralization. ( a less messy precipitate) It is barely soluble, but will react fairly well with acids, so it will work well to say a pH of 5. Polish the pH with lime or with caustic soda.
A small filter press should work for you. See if you can find a used one that is in good condition with a warranty on the pump. If you can get to Sur-Fin, you can get a great discount on their show units because they do not have to ship them home. OOPs, you are in the UK. There should be a major show in Europe somewhere this summer.

James Watts
- Navarre, Florida

The only thing I can add to Mr. Watts' excellent advice is to use a diatomaceous earth precoat on the filter press plates. This always improves the ease of cake release from the press plates, and can help with the clarity of the press return water.

Dave Wichern - Bronx, NY, USA