Recycling of the sludge produced in Zn phosphating Process

Recycling of the sludge produced in Zn phosphating process for aluminum car bodies has been studied in terms of fluxing application for aluminum molten metal. The sludge collected mainly consisted of Al-F composition containing cryolite Na₃AlF₆, which is quite similar to that of the flux for molten metal. In the case of higher F content ratio, there were no effects of the sludge addition (up to 10%) on fluxing performances with regard to on hydrogen degassing, impurities containing (ex. P, Fe, Zn, Cr) and metal loss ratio for aluminum molten metal. On the application of dross off agent for aluminum molten metal, 100% of the sludge had no effect use on metal loss ration and impurities containing independent of F content ratio.