A pilot-scale study and evaluation of the melting process and vitrification characteristics of electroplating sludge by oxygen enrichment melting

Melting/vitrification is an effective method for harmless and rapid disposal of electroplating sludge (EPS) on a large scale. In our work, oxygen enrichment melting was proposed to reduce the high energy consumption during EPS melting. The melting and vitrification process of EPS can be divided into water evaporation, chemical decomposition and formation, crystal phase transition and vitrification. The addition of quartz sand (QS) promotes silicate formation and the crystal phase transition process, resulting the highest value vitrification rate (99.54%) of EPS slag. The results of heavy metal leaching of both water-quenched and air-cooled slags meet the national standard. The increase of oxygen concentration reduces the operation cost by 48.3%. The operation cost continues to reduce when the QS addition is 5%, wherein the lowest operation cost was 217.23 dollars/ton EPS. The emissions of SO2 and NOx with the addition of 5% of QS are the lowest among all experiment conditions. All results indicate that the oxygen enrichment melting technology is a promising method. 5% of QS addition during EPS melting with 90% oxygen concentration is the best operation condition in terms of the vitrification rate, heavy metal solidification and leaching, flue gas emission, and operation cost.