Synergistic Stabilization/Solidification of Heavy Metal Ions in Electrolytic Manganese Solid Waste and Phosphogypsum

The α-calcium sulfate hemihydrate whiskers (α-CSHWs) were first prepared using phosphogypsum (PG) and electrolytic manganese residue (EMR) as raw materials for coating urea, demonstrating excellent controlled-release properties. The effects of different reaction conditions on α-CSHWs, achieved by optimizing the reaction time, the concentrations of NH4+, Mn2+, and other factors, were discussed. Results showed that when the EMR content was 25 wt%, the reaction temperature was 100 °C, and the reaction time was 3 h, α-CSHWs with a length-to-diameter ratio of 39 were obtained. Through experiments and density functional theory (DFT), the mechanism of α-CSHWs preparation was elucidated. The results show that the addition of EMR reduces the content of impurity ions PO43− and F− in PG while introducing NH4+ and Mn2+. Interestingly, both NH4+ and Mn2+ can reduce the nucleation time of α-CSHWs, while PO43−, Mn2+, and F− are more likely to adsorb on the (0 0 6) crystal plane of α-CSHWs, NH4+ readily adsorbs on the (4 0 0) crystal plane. The controlled-release performance of modified α-CSHWs incorporated into polyurethane-coated urea (PCU) was investigated, and it was found that the addition of Mα significantly prolonged the nutrient release period, with the period extending up to 116 days for coatings of 5wt% and above. This work not only enhances the efficiency of PG and EMR utilization but also serves as a reference for the straightforward synthesis and application of α-CSHWs.

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Treatment Methods for Harmful Impurities in Phosphogypsum and Their Applications in Road Engineering: A State-of-the-Art Review

Liu,

He,

Dang

et al. 2024

Preprint

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Phosphogypsum (PG), a significant by-product of the wet phosphoric acid production process, poses environmental and utilization challenges due to its harmful impurities, including heavy metals, fluorides, and phosphates. This review aims to evaluate the stabilization/solidification (S/S) methods for these hazardous impurities to enhance PG recycling in road engineering and other applications. A comprehensive bibliometric analysis was conducted using data from the Web of Science Core Collection, covering publications from 1985 to 2024. The review assesses the types and impacts of PG impurities on composite material performance and environmental health, detailing various S/S methods and their underlying mechanisms. Key findings suggest that blending PG with inorganic cementitious materials, incorporating additives, and using PG-based geopolymers are effective strategies for S/S. Blending PG with electrolytic manganese residue (EMR) and granulated blast furnace slag (GBFS) shows significant potential in immobilizing heavy metals and reducing environmental risks. The use of polymer materials, surface modifiers, and curing agents enhances the physical encapsulation and chemical stabilization of harmful impurities. PG-based geopolymers, formed through unique hydration reactions, offer robust encapsulation and adsorption capabilities for heavy metals. Additionally, biological treatment methods and biochar adsorption present innovative approaches for PG remediation. The main S/S mechanisms include physical encapsulation, chemical precipitation, ion exchange, and adsorption. Future research should focus on optimizing these S/S techniques, exploring synergistic combinations, and developing cost-effective and scalable solutions to improve PG recycling and promote sustainability in industrial practices.

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Synergistic Stabilization/Solidification of Heavy Metal Ions in Electrolytic Manganese Solid Waste and Phosphogypsum

Cited by 3 publications

References 33 publications

A Research Progress on Stabilization/Solidification of Electrolytic Manganese Residue

A Research Progress on Stabilization/Solidification of Electrolytic Manganese Residue

Synergistic preparation and application in PCU of α-calcium sulfate hemihydrate whiskers from phosphogypsum and electrolytic manganese residue

Treatment Methods for Harmful Impurities in Phosphogypsum and Their Applications in Road Engineering: A State-of-the-Art Review

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