低温焙烧法综合处理铬渣和皮革污泥的研究

Comprehensive treatment of COPR and tannery sludge by roasting process at low temperature

采用低温焙烧法综合处理铬渣和皮革污泥,对皮革污泥的热分解特性和铬渣中六价铬的还原规律进行实验研究。研究结果表明:在大于400℃的焙烧温度下,皮革污泥分解产生的CO、烷烃等还原性气体可将铬渣中的六价铬还原;焙烧温度、焙烧时间以及铬渣与皮革污泥的质量比(pm)对铬渣中六价铬的还原有重要影响,温度越高,焙烧时间越长,则铬渣中六价铬还原越彻底,增加皮革污泥的配量有利于铬渣中六价铬的彻底还原;在焙烧温度大于500℃,pm≤30的条件下,焙烧处理渣中六价铬的含量小于35 mg/kg,其毒性浸出试验浸出液中六价铬和总铬质量浓度分别小于0.3 mg/L和0.5 mg/L,符合解毒铬渣直接用于生产水泥、砖块等建筑材料的要求。

The pyrolysis characteristics of tannery sludge and the reduction law of the hexavalent chromium （Cr（Ⅵ）） in chromite ore processing residue （COPR） were investigated when the two sludge were mixed and subsequently roasted at low temperature. The results show that Cr（Ⅵ） in COPR can be reduced by the reductive gases such as carbon monoxide and alkanes released from tannery sludge with the roasting temperature above 400 ℃; roasting temperature, retention time and mass ratio （Pro） of COPR to tannery sludge play a significant role in Cr（Ⅵ） reduction; increasing roasting temperature and retention time improves the Cr（Ⅵ） reduction, and the higher dosage of tannery sludge in the mixture, the lower Cr（Ⅵ） content in the treated residue; when the roasting temperature is above 500 ℃ and thepm is less than 30, the Cr（Ⅵ） content in the treated residue can be less than 35 mg/kg, the Cr（Ⅵ） and total Cr concentration in the toxicity characteristic leaching procedure （TCLP） leachate of the treated residue are below 0.3 mg/L and 0.5 mg/L, respectively, which is far lower than the TCLP regulatory limit for the treated COPR used as raw material for producing construction materials such as block and cement.