Solidification of Municipal Solid Waste Incineration Fly Ash through Co-Mechanical Treatment with Circulation Fluidized Bed Combustion Fly Ash.

Zhengzhen Yao,Ran An,Yu Li,Qin Shuai,Xin Jiang,Zhonghui Xu,Zao Jiang,Xiaoyue Chen,Xi Peng,Han Li

doi:10.3390/ma13010141

Abstract

This study aims to explore the solidification performance of municipal solid waste incineration fly ash (MSWIFA) through co-mechanical treatment with circulation fluidized bed combustion fly ash (CFBCFA). The mineral characterization, physical properties, and leaching resistance of the solidified bodies are investigated by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry-differential thermal analysis (TG-DTA), compressive strength, porosity, and leaching test, respectively. C–S–H, ettringite (AFt), and Friedel’s salt (FS) are the predominant hydrate products in the CFBCFA based solidified bodies, which are similar to the cement based solidified bodies. However, CFBCFA based solidified bodies exhibit higher compressive strength (36.7 MPa) than cement based solidified bodies (11.28 MPa), attributing to the three reasons: lower porosity and more compact internal structure of CFBCFA based solidified bodies; large amounts of Ca(OH)2 originating from MSWIFA are conducive to promoting the hydration reaction extent and compressive strength of the CFBCFA based solidified bodies; excessive Ca(OH)2 would cause compressive strength deterioration for the cement based solidified bodies. The heavy metals (Zn, Cu, Cr, Cd, and Pb) concentrations in the extraction solution of the CFBCFA based solidified bodies are far below the requirements of Chinese National Standard GB 5085.3-2007. The solidification of MSWIFA through co-mechanical treatment could be an ideal substitute for cement solidification technology.

Highlights

municipal solid waste incineration fly ash (MSWIFA) generates from waste incinerators, which is regarded as hazardous solid waste due to the enrichment of leachable heavy metals and, in some cases, potentially organic pollutants [1].To safely handle and dispose of MSWIFA, various treatment have been proposed including recovery of valuable component, stabilization with wood pellet ash, and solidification with cement [2,3].Currently, cement solidification technology is widely proposed and investigated to deal with MSWIFA owing to its technical feasibility [4,5]
MPa), which is correlated to the lower porosity of circulation fluidized bed combustion fly ash (CFBCFA) and cement based solidified bodies are 18% and 24.5%, respectively, which could porosity of CFBCFA and cement based solidified bodies are 18% and 24.5%, respectively, which could more compact ofand
The results prove that the solidification of MSWIFA through co-mechanical treatment could be an ideal substitute for cement solidification technology

Summary

Introduction

MSWIFA generates from waste incinerators, which is regarded as hazardous solid waste due to the enrichment of leachable heavy metals and, in some cases, potentially organic pollutants [1].To safely handle and dispose of MSWIFA, various treatment have been proposed including recovery of valuable component, stabilization with wood pellet ash, and solidification with cement [2,3].Currently, cement solidification technology is widely proposed and investigated to deal with MSWIFA owing to its technical feasibility [4,5]. MSWIFA generates from waste incinerators, which is regarded as hazardous solid waste due to the enrichment of leachable heavy metals and, in some cases, potentially organic pollutants [1]. To safely handle and dispose of MSWIFA, various treatment have been proposed including recovery of valuable component, stabilization with wood pellet ash, and solidification with cement [2,3]. Cement solidification technology is widely proposed and investigated to deal with MSWIFA owing to its technical feasibility [4,5]. More suitable material should be considered to replace cement to solidify MSWIFA. The fly ash coming from circulation fluidized bed combustion boilers could encapsulate the heavy metals effectively due to the pozzolonicity and self-gelling properties and has the potential to be Materials 2020, 13, 141; doi:10.3390/ma13010141 www.mdpi.com/journal/materials

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