Study on ammoniacal leaching of zinc from sludges containing iron and zinc hydroxides

B. Kazinczy, L. Kótai, I. Gács, K. Szentmihályi, Z. Sándor, S. Holly

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10 Citations (Scopus)


In this paper a new ammoniacal leaching process for recovering zinc in hot dip galvanization sludge is presented. Experimental results indicate that the zinc can be efficiently leached at room temperature and atmospheric pressure. Two-third of the zinc could be recovered as tetraamminezinc(II)hydroxide in a one-hour extraction process if the sludge to the reagent (25%w/w NH4OH) ratio was 1:7.5. The tetraamminezinc(II)hydroxide formed was decomposed to hydrated zinc oxide and ammonia by means of a simple boiling process. The precipitated oxide was found to be free from heavy metals and can be converted to a crystalline form by dehydration at 200 °C. The ammonia released during boiling can be recycled via absorption into the leaching solution. The final residue with low zinc content may be utilized as an additive in the fertilizer industry.

Original languageEnglish
Pages (from-to)207-210
Number of pages4
JournalHungarian Journal of Industrial Chemistry
Issue number3
Publication statusPublished - Dec 1 2000

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Chemistry(all)
  • Chemical Engineering(all)

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