Study of the heavy metals residual in the incineration slag of textile dyeing sludge

• High temperature was conducive to the enrichment of Cu, Zn and Ni.
• Moisture content and CaO inhibited volatilization of Cd, Pb and Zn.
• Cu and Cr were least volatilized from the incinerated sludge.
• The residual ratio of Zn was the lowest under different time and moisture content.

The effects of various incineration conditions on the residual ratios of Cu, Cr, Cd, Pb, Ni and Zn in the slag of textile dyeing sludge were investigated. The results indicated that higher temperatures (1000–1100 °C) were conducive to the solidification of Cu, Ni and Zn in the slag and that a lower temperature (700 °C) was conducive to the solidification of Cr, Cd and Pb. The residual ratios of Cu, Cr, Cd and Ni exhibited similar tendencies as the residence time increased, but Pb exhibited a negative correlation. The residual ratios of Cu, Cr, Ni and Zn were relatively stable as the moisture increased except for those of Cd and Pb. The residual ratios of Cr, Zn, Pb and Cd increased as the CaO dosage increased, but Cu exhibited a negative correlation. For XRD analysis, a higher temperature and the CaO additive had a positive effect on the crystallization of heavy metals during incineration.