Effect of Temperature on Dezincification of Galvanized Scrap Steel under Low Vacuum Condition

Using the direct reduction method of fire dezincification, hot state experiments were conducted on galvanized scrap steel samples under low vacuum and oxidation atmosphere conditions to compare and analyze the effect of temperature on the dezincification of galvanized scrap steel under low vacuum conditions. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), spectral analyzer (XRF) and other methods were used to characterize and analyze the surface morphology and distribution of surface element of the samples, and to explore the optimal dezincification conditions for galvanized scrap steel, and to analyze its dezincification principle from a thermodynamic perspective.The results show that the effect of temperature within a certain range on the dezincification effect of galvanized scrap steel is positively correlated. The higher the temperature, the better the dezincification effect. Considering industrial costs, the optimal dezincification temperature is 950 ℃. At 950 ℃ under oxidation conditions, the mass fraction of zinc on the outermost surface of galvanized scrap steel decreases to 5%, and the dezincification rate is 95%, resulting in further reaction between the inner layer of the large area zinc oxide film and the outside world. At 950 ℃ under low vacuum conditions, the mass fraction of zinc on the surface of galvanized scrap steel is less than 1%, and the dezincification rate reaches 99%. The outer layer does not form an oxide film, and the depth of dezincification is greater than that of the former, and most Zn evaporates in the form of steam. Therefore, low vacuum conditions have more advantages in dezincification of galvanized scrap steel.