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

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.

Hydrometallurgical Molybdenum Recovery from Spent Catalyst Using Tartaric Acid Derived from Agrifood Waste

“…Thus, the recovery process through recycling or other more sustainable methods can reduce the environmental impact of metal production. Additionally, metal recovery requires less energy compared to extracting metals from ore, leading to lower energy consumption and carbon emissions . The Global molybdenum reserve base in 2022 was 12000000 mt, with distribution predominantly from Chile, Peru, U.S.A., and China .…”

“…Additionally, metal recovery requires less energy compared to extracting metals from ore, leading to lower energy consumption and carbon emissions. 14 The Global molybdenum reserve base in 2022 was 12000000 mt, with distribution predominantly from Chile, Peru, U.S.A., and China. 4 This critical aspect in the supply chain stability and recovering metals from existing sources can help to ensure a stable supply of metals by reducing reliance on a sole ore source (International Molybdenum Association reported that global molybdenum extracted in 2022 was 286440 tonnes from mine production only and does not include material recovered from spent catalysts).…”

A Review of Traditional and Intensified Hydrometallurgy Techniques to Remove Chromium and Vanadium from Solid Industrial Waste

“…Interestingly, with the depletion of high-grade natural ore reserves, recycling industrial waste can serve dual purposes. It not only allows for the utilization of waste as alternative materials to incorporate bulkily in existing matrices (building materials for instance) but also enables energy-efficient recovery of metals . A notable example is Boliden Rönnskär, a Swedish company that found the energy required to extract metals from e-waste was only 10 to 15% compared to smelting and refining metal ore concentrates .…”

“…It not only allows for the utilization of waste as alternative materials to incorporate bulkily in existing matrices (building materials for instance) but also enables energy-efficient recovery of metals. 57 A notable example is Boliden Ronnskar, a Swedish company that found the energy required to extract metals from e-waste was only 10 to 15% compared to smelting and refining metal ore concentrates. 5 Similarly, the efficient extraction of Cr from industrial waste like steel slag can resolve environmental issues while producing valuable products such as Na 2 Cr 2 O 7 and Cr 2 O 3 , widely used in several industrial sectors.…”

Solidification Mechanism of Pb and Cd in S2−-Enriched Alkali-Activated Municipal Solid Waste Incineration Fly Ash

“…There are three main methods for solidifying heavy metals in MSWI fly ash, including electrochemical extraction [ 6 , 7 ], solidification by cementitious materials [ 8 , 9 , 10 ], and melting vitrification [ 11 , 12 , 13 ]. Solidification by cementitious materials is considered the most suitable method for MSWI fly ash because of its simple treatment and sound economic and environmental effects [ 14 ].…”