电镀污泥的热处理特性以及对金属回收的影响

焙烧-酸浸法可有效回收电镀污泥中的有价金属,而污泥的热处理特性是决定能否采用焙烧预处理的重要因素。研究了氧化焙烧和还原焙烧对污泥成分和金属浸出性的影响,并对焙烧前后的污泥进行了金属形态分析和X射线衍射(XRD)分析。结果表明,焙烧预处理实现了污泥减量和金属富集;ES1经氧化焙烧后金属浸出率接近原泥,Cu的浸出率达99%;ES2的还原焙烧效果优于氧化焙烧,特别是Cu的浸出率超过97%,XRD分析发现,还原焙烧过程中金属Cu被还原为铁铜合金;2种焙烧均造成了ES3中目标金属Ni的浸出率的降低;金属浸出性的下降与残渣态的形成有关。

Thermal disposal behavior of electroplating sludge and its effect on metals recovery

Valuable metals can be efficiently recovered from electroplating sludge by roasting-sulfuric acid leaching process, and thermal disposal behavior of sludge is the critical fact deciding whether to use roasting as pretreatment. The influences of oxidation-roasting and reduction-roasting on sludge composition and metals leaching property were investigated. In addition, the sludges before and after roasting were analyzed by X-ray diffractometry(XRD), while metal speciation was also determined. Results showed that roasting pretreatment reduced the quantity of sludge and enriched metals. Leaching rates of metals in the oxidation-roasted sludge ES1 were close to the raw sludge. For example, the leaching rate of copper was as high as 99%. For the sludge ES2, the effect of reduction-roasting was superior to oxidation-roasting, by which the copper leaching rate reached over 97%, meanwhile, XRD analysis discovered that copper was reduced to iron-copper alloy. The two kinds of roasting both decreased the leaching rate of target metal nickel in the sludge ES3. The decrease in metal leaching property was related to the formation of residual metal.