Melting reconstruction features and solidification mechanism of heavy metal-containing slag

Abstract

The relationships between microstructure and melting temperature of slag containing different heavy metals (Zn, Cu, Pb and Cr) were studied. Furthermore, the corresponding solidification mechanism and rule of heavy metals were analyzed by microscopic tests during melting and reconstructing process. Based on preliminary results, three conclusions were derived. Firstly, pure slag would begin to melt when the temperature reached 1 180 °C; however, Zn did not play any fluxing action. Secondly, upon adding Cu and Pb, the initial melting temperature of slag decreased by 5–8 °C and their fluxing effect was observed. Thirdly, the initial melting temperature and the reaction time for slag decreased by 22 °C and 6 s respectively after adding Cr; the fluxing action was significant under Cr. The results of X-ray diffraction (XRD) and Fourier transform infrared spectroscope (FTIR) analyses showed that the above heavy metals had little influence on the reconstruction of slag. Toxicity characteristic leaching procedure (TCLP) leaching tests showed a good solidification effect of the heavy metals with melting slag, fixation rate of Zn, Cu, Pb and Cr was 36.3%, 24.6%, 9.2% and 93.2%, respectively. The leaching toxicity of the heavy metals met the requirements for environmental emission after solidification treatment.

Keywords

water quenching slag / melting / heavy metals / solidification / TCLP

References

[1] Sakai S, Urano S, Takatsuki H Leaching Behavior of PCBs and PCDDs/DFs from Some Waste Materials[J]. Waste Management, 2000, 20: 241-247.

[2] Luo Z-t, Xiao Y-l, Yang J-j, . Progress on Solidification of Toxic Heavy Metals in Municipal Solid Waste Incineration Fly Ash[J]. Environmental Pollution and Control, 2012, 34(8): 58-62.

[3] Sakai S, Hiralka M Municipal Solid Waste Incinerator Residue Recycling by Thermal Processes[J]. Ash Management, 2000, 20: 249-258.

[4] Du Y-z, Zhang L, Gao Xuan Advances in Melting Technology about Ash of MSW Incinerator[J]. Energy Engineering, 2006, 1: 36-40.

[5] Cui S-p, Lan M-z, Zhang J, . Effect and Incorporation Mechanism of Heavy Metal Elements in Hazardors Industrial Wastes During Clinker Formation[J]. Journal of The Chinese Ceramic Society, 2004, 32(10): 1 264-1 270.

[6] Li R-d, Nie Y-feng Influence of Liquid Ceramic Additive on Binding of Heavy Metal during the Vitrification of Fly Ash from Municipal Solid Waste Incinerator[J]. Environmental Science, 2004, 25(5): 168-171.

[7] He X-h, Hou H-b, Zhang D-jie Study on Cement Solidification of Municipal Solid Waste Incineration Fly Ash[J]. Environmental Pollution & Control., 2006, 28(06): 425-428.

[8] Wang X-t, Jin B-sheng Effects of Melting Temperature Experimental Property of Fly Ash from Municipal Solid Waste Incinerator during Wwirling Melting Process[C]. Proceedings of the CSEE, 2007, 27(20): 46-51.

[9] Sun J-y, Wang Z-x, Qiao Yan Research of a Solidifying Agent Containing Mineral Slag to Consolidate Heavy Metals in Mineral and Municipal Wastes[J]. Wuhan University of Technology, 2007, 29(3): 71-74.

[10] Masa-aki O, Haruki W, Bernd W Characteristics of Heavy Metal Release from Incinerated Ash, Melted Slag and Their Re-products[J]. Water Science and Technology, 1997, 36(11): 267-274.

[11] Chong YR, Seong KK, Chang EK Investigation of the Stability of Hardened Slag Paste for the Stabilization/Solidification of Wastes Containing Heavy Metal Ions[J]. Journal of Hazardous Materials, 2000, B73: 255-267.

[12] Masaki T, Nobuo T, Satoshi M The Behavior of Heavy Metals and Phosphorus in an Ash Melting Process[J]. Water Science and Technology, 1997, 36(11): 275-282.

[13] Kyung-jin H, Shuzo T, Toshio K Extraction of Heavy Metals from MSW Incinerator Fly Ashes by Chelating Agents[J]. Journal of Hazardous Materials, 2000, B75(1): 57-73.

[14] Barton R G, Clark WD, Seeker WR Fate of Metals in Waste Combustion Systems. Combust. Sci. and Tech., 1990, 74(1): 327-342.

[15] Chan C CY, Kirk D W Behavior of Metals under the Conditions of Roasting MSW Incinerator Fly Ash with Chlorinating Agents[J]. Journal of Hazardous Materials, 1999, 64(8): 75-89.

[16] Park YJ, Heo J Vitrification of Fly Ash from Municipal Solid Waste Incinerator[J]. Journal of Hazardous Materials, 2002, B91(1–3): 83-93.

[17] Thipse SS, Drezin EL Metal Partitioning in Products of Incineration of Municipal Solid Waste[J]. Chemophere, 2002, 46(6): 837-849.