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保护性气氛下温度对镀锌废钢脱锌的影响

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

  • 摘要: 采用火法脱锌方法在保护性气氛下对镀锌废钢进行热态实验,结合扫描电镜(SEM)、能谱仪分析(EDX)、光谱分析仪(XRF)等方法分析保护性气氛条件下温度对镀锌废钢脱锌的影响,探究保护性气氛下锌及基体的变化,从金属蒸发速率和扩散速率角度分析镀锌废钢的脱锌机理。结果表明:在保护性气氛下,当温度达到850 ℃,镀锌废钢表面局部被残氧氧化,表面开始出现黄色氧化锌;925 ℃时表面出现局部鼓泡,随着温度的继续升高氧化锌逐渐减少,至1 000 ℃时镀锌废钢表层锌完全消失。镀锌废钢质量、厚度随锌的氧化在850 ℃后开始增加,至950 ℃时因锌被脱除,镀锌废钢质量、厚度大幅下降,镀锌废钢最外层表面锌的质量分数由65.69%降至4.00%,脱锌率为93.9%。在一定范围内温度对镀锌废钢脱锌的影响呈正相关性,随温度的升高,脱锌效果显著增强,当温度升至锌的沸点时锌迅速气化冲破氧化膜,脱锌区域不断扩大,最终表面锌脱离,综合考虑工业成本,最佳脱锌温度为950 ℃。

     

    Abstract: 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 ℃.

     

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