64. How is zinc ash formed? What are its components?

Zinc ash, or zinc oxide, forms rapidly during hot-dip galvanizing, typically appearing immediately after each coating pass. This occurs because zinc liquid reacts with atmospheric oxygen to produce zinc oxide. Simultaneously, when the solvent from the steel pipe to be galvanized is immersed in the zinc bath, it activates the zinc adsorption process on the iron surface, resulting in the formation of zinc ash and solvent residues. The zinc ash primarily consists of a mixture of zinc oxide, metallic zinc particles, chlorides, and other acid-insoluble impurities. The zinc oxide in the ash includes both pure zinc oxide and compounds with other oxides. Small metallic zinc particles typically account for 15-35% of the total zinc ash content, while larger particles may reach 30-60% or even 70-75% depending on the galvanizing equipment used.