低真空条件下温度对镀锌废钢脱锌的影响

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

利用火法脱锌直接还原法,在低真空和氧化气氛条件下对镀锌废钢试样进行热态实验,对比分析低真空条件下温度对镀锌废钢脱锌的影响。采用扫描电镜(SEM)、能谱仪分析(EDS)、光谱分析仪(XRF)等方法表征分析试样表面形貌及元素分布,探究镀锌废钢的最佳脱锌条件,并从热力学角度分析其脱锌原理。结果表明:一定范围内温度对镀锌废钢脱锌效果的影响呈正相关,温度越高脱锌效果越好,考虑到工业成本,最佳脱锌温度为950℃;氧化条件下950℃时,镀锌废钢最外层表面锌的质量分数降至5%、脱锌率为95%,产生的大面积氧化锌薄膜阻碍进一步的氧化反应;低真空条件下950℃时,镀锌废钢表面锌的质量分数不足1%、脱锌率达99%,外层不生成氧化膜,大部分锌由蒸汽形式挥发,脱锌深度大于前者,低真空条件在镀锌废钢脱锌方面更具优势。

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.