Effect of Temperature on Dezincification of Galvanized Scrap in a Protective Atmosphere

Through the fire dezincification method in the protective atmosphere of galvanized steel scrap thermal state experiments, using scanning electron microscopy (SEM), energy spectrometer analysis (EDX), spectral analyzer (XRF) and other methods to analyze the protective atmosphere conditions of the temperature of galvanized steel scrap dezincification, to explore the changes in the zinc and the substrate in the protective atmosphere, from the point of view of the rate of evaporation of the metal and the rate of diffusion of the analysis of the dezincification mechanism. The results show that: in the protective atmosphere, when the temperature reaches 850 ℃, the surface of galvanized scrap is oxidized by residual oxygen, and yellow zinc oxide begins to appear on the surface; at 925 ℃, local bubbles appear on the surface, and as the temperature continues to rise, the zinc oxide decreases, and then the zinc disappears from the galvanized scrap surface at 1,000 ℃. Galvanized steel scrap quality and thickness with the oxidation of zinc in 850 ℃ began to increase, to 950 ℃ when the zinc was removed, galvanized steel scrap quality and thickness decreased dramatically, galvanized steel scrap outermost surface zinc mass fraction from 65.69% to 4%, the rate of dezincification is 93.9%. In a certain range of temperature on galvanized scrap dezincification was positively correlated with the increase in temperature, dezincification effect is significantly enhanced, when the temperature rises to the boiling point of zinc zinc rapidly gasification rupture of the oxide film, dezincification area continues to expand, and ultimately the surface of the zinc detachment, the comprehensive consideration of industrial costs, the optimal dezincification temperature of 950 ℃.