澳炉协同处置废弃电路板过程铜冶炼烟尘二噁英再合成研究

Research on the resynthesis of dioxins from copper smelting dust during collaborative waste circuit board disposal in an Ausmelt furnace

废弃电路板与铜精矿在澳斯麦特炉中协同处置,既可作为燃料,又能回收金属资源,但其产生的铜冶炼烟尘中可能存在二噁英的再合成,从而增加烟气二噁英排放.为探究铜冶炼烟尘二噁英再合成特性及其影响因素,本文采用实验室燃烧反应装置,选取国内某铜精矿冶炼厂的铜冶炼烟尘(余热锅炉底灰、电除尘灰)开展实验,研究了不同物料、温度、金属催化剂等反应条件下铜冶炼烟尘二噁英再合成特性以及SO2抑制效果.结果表明,加热条件下余热锅炉底灰二噁英浓度随温度升高呈先上升后下降趋势,350℃时PCDD/Fs的产量达到最大,PCDD/PCDF的比例随温度升高而降低,400℃工况相较于300℃降低了14%;余热锅炉底灰二噁英再合成能力弱于电除尘灰;余热锅炉底灰中加入含量为0.1%的金属催化剂CuCl2后,气相和固相毒性当量分别增长了9倍和20倍,而通入SO2气氛后,固相和气相二噁英毒性当量浓度分别下降了60.67%和21.84%;结合SEM、XPS等表征分析发现,金属催化剂被钝化是其主要的抑制路径.本文研究结果可为高含硫铜精矿协同处置废弃电路板提供技术支撑.

Waste circuit boards can serve dual purposes as fuel and as a source for metal recovery during their co-processing with copper concentrate in an Ausmelt furnace.However,this process may facilitate the re-synthesis of dioxins within the smelting dust,potentially augmenting dioxin emissions in the flue gas.This study aims to delineate the characteristics and determinants of dioxin re-synthesis emanating from smelting dust.Employing a laboratory-scale combustion reactor,we selected smelting dust samples(comprising waste heat boiler bottom ash and electrostatic precipitator ash)from a domestic copper concentrate smelting facility for experimentation.We examined the re-synthesis dynamics of dioxins in copper smelting dust and the mitigative impact of SO2 under various experimental conditions,including different materials,temperatures,and metal catalysts.Our findings reveal that the concentration of dioxins in waste heat boiler bottom ash initially escalates before diminishing with an increase in temperature.The production of PCDD/Fs peaked at 350℃,while the PCDD/PCDF ratio declined as temperature increased,noting a 14%reduction at 400℃compared to 300℃.The propensity for dioxin synthesis in waste heat boiler bottom ash was found to be less pronounced than in electrostatic precipitator fly ash.Introducing 0.1%metal catalyst CuCl2 to the waste heat boiler bottom ash significantly increased the toxic equivalent of both the gaseous and solid phases by ninefold and twentyfold,respectively.Conversely,the introduction of an SO2 atmosphere resulted in a 60.67%and 21.84%reduction in the toxic equivalent concentration of solid and gaseous phase dioxins,respectively.Characterization analyses,including SEM and XPS,identified metal catalyst passivation as the primary inhibitory mechanism.The insights gained from this study will provide technical strategies for the co-processing of waste circuit boards with high-sulfur copper concentrate.