Process and equipment for phosphating metallic workpieces

摘要

In a process for the batchwise phosphating of metallic workpieces by means of a phosphating solution contained in a stock tank in a treatment vessel receiving a batch of the pretreated workpieces, it is provided, in order to avoid caking of phosphate sludge, that the phosphating solution is passed continuously into the treatment vessel and over the workpieces, the used solution continuously running out of the treatment vessel being passed into at least one settling stage, the entrained phosphate sludge is sedimented and the supernatant phosphate solution is recycled into the stock tank, while the sediment is drawn off as thin sludge from the settling stage into a neutralisation stage.