Volatilization and leaching behavior of heavy metals in MSW incineration fly ash in a DC arc plasma furnace

Abstract

Keywords:MSW incineration fly ash Heavy metals Volatilization and leaching behavior DC arc plasma CaO -Al 2 O 3 -SiO 2 (CAS) A B S T R A C T Three fly ash samples collected from different waste incinerators were vitrified using a direct current arc plasma furnace at 1250-1400°C. The influence of water-wash extraction and wrapping pretreatment on the volatilization and leaching behavior of heavy metals was investigated. Results showed: After thermal arc plasma treatment, the volume reduction and weight loss of fly ash were in the range of 68.7-82.2% and 23.8-56.7%, respectively. The residual fractions (wt.%) of heavy metals in slag are in the following sequence: Cr < Ni < Cd < Pb < Cu < Zn. Water-washing could reduce the volatilization rate of heavy metals due to some volatile salts removed by washing, while wrapping of fly ash could most effectively resist heavy metals against volatilizing, especially for Zn and Ni. The possible CaO -Al 2 O 3 -SiO 2 (CAS) ratio for successful melting of fly ash is suggested to be CaO in range of 20-48%, Al 2 O 3 in range of 10-15%, and SiO 2 in range of 40-65%. Moreover, toxicity characteristic leaching procedure results showed that the leaching of heavy metals in slags was much lower than the standard limit of toxicity characteristic leaching procedure (TCLP).

Incineration Fly Ash and Its Treatment to Possible Utilization: A Review

“…The high-energy-density and high-temperature of a plasma flame can promote the melting/vitrification reactions and reduce the residence time of MSWI fly ash. Related research [169][170][171][172] has shown, after plasma melting/vitrification treatment, the volume reduction of MSWI fly ash. The volatilization and leaching characteristics of heavy metals before and after plasma melting/vitrification [169][170][171]173] determined that most heavy metals sealed in vitreous slag are Cr, and Ni, which are low volatile heavy metals.…”

Theoretical and experimental investigations on the combustion characteristics of three components mixed municipal solid waste

“…As the value of is very large [41], e dT e is assumed. Re-arranging and integrating equation (6), the following equation can be obtained:…”

“…Landfill is the traditional method of MMSW disposal [5]. Due to land occupation and underground water pollution, it has been gradually replaced by incineration process [6]. The incineration process can produce energy while eliminating MMSW and has become the most popular way of waste disposal [7][8][9].…”

Review of harmless treatment of municipal solid waste incineration fly ash

“…The high-energy-density and high-temperature of a plasma flame can promote the melting/vitrification reactions and reduce the residence time of MSWI fly ash. Related research [37,38,163,164] has shown that after plasma melting/vitrification treatment, the volume reduction of MSWI fly ash is between 60% and 82.2%, and the mass reduction is between 10% and 56.7%. The analysis of melting products [36,38,164] revealed that the density is mostly concentrated between 2.75 and 2.9 g/cm 3 , and the hardness is in the range of 6-7 GPa.…”