Recycling phosphogypsum to produce artificial lightweight aggregates via stirring and pelleting all-in-one technique: Technical assessment and performance optimization

IF 9.7 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Journal of Cleaner Production Pub Date : 2024-10-21 DOI:10.1016/j.jclepro.2024.144052

Chao Zhang, Zhijuan Hu, Chiqiu Wu, Tao Yu, Xujiang Wang, Jingwei Li, Wei Lv, Xiangkun Zhang, Wenlong Wang

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Abstract

Currently, production of artificial lightweight aggregates (ALAs) is becoming one of the most promising approaches for solid wastes recycling via pelletization technique. In this study, an innovative stirring and pelleting all-in-one technique (S-pelleting) was employed to prepare the ALAs by using phosphogypsum (PG). The effects of different pelleting techniques on properties of the ALAs were investigated. Furthermore, the NaHCO₃, Al₂(SO₄)₃+CaCO₃ (Al-Ca) and foamed particles (FP) were introduced as foaming agents to optimize the performance of the ALAs. The specific strength was used as the main assessment index for performance of the aggregates. The results indicated that the specific strength of the aggregates was improved to 10.96 MPa⋅cm³/g by S-pelleting, which was 60.7 % and 35.6 % higher than that of one-step pelleting or double-step pelleting technique. Compared to NaHCO₃, the Al-Ca was more conducive to the specific strength development of the aggregates, and the FP addition could further improve the specific strength of the ALAs. When the concentration of Al-Ca was 7% and the mass fraction of FP was 10%, the ALAs with high specific strength of 9.6 MPa⋅cm³/g were obtained in this study. Moreover, the mineral composition, microstructure and pore structure of the ALAs were analyzed and the results reveled that the Al-Ca could promote to form more ettringite and reduce the proportion of harmful pores in the aggregates, which was responsible for the improvement in specific strength. The FP acted as a lightweight skeleton supported inside the aggregates and the well bonded ITZ between FP and the matrix could further improve the specific strength of the ALAs. Finally, the durability and environmental impact of the ALAs were evaluated acceptable. Overall, this study not only provided a green approach for PG recycling, but also presented a new technical scheme for more efficient production of ALAs.

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通过搅拌和造粒一体化技术回收磷石膏，生产人工轻质骨料：技术评估和性能优化

目前，通过造粒技术生产人工轻质骨料（ALAs）正成为固体废物回收利用中最有前景的方法之一。本研究采用创新的搅拌造粒一体化技术（S-造粒），利用磷石膏（PG）制备人工轻质骨料。研究了不同制粒技术对 ALAs 性能的影响。此外，还引入了 NaHCO3、Al2(SO4)3+CaCO3 (Al-Ca) 和发泡颗粒 (FP) 作为发泡剂，以优化 ALAs 的性能。比强度是集料性能的主要评估指标。结果表明，S-造粒技术可将骨料的比强度提高到 10.96 MPa⋅cm3/g，比一步造粒技术和双步造粒技术分别高出 60.7% 和 35.6%。与 NaHCO3 相比，Al-Ca 更有利于聚集体比强度的提高，FP 的加入可进一步提高 ALAs 的比强度。当 Al-Ca 的浓度为 7%、FP 的质量分数为 10%时，本研究获得了比强度高达 9.6 MPa⋅cm3/g 的 ALAs。此外，还对 ALAs 的矿物组成、微观结构和孔隙结构进行了分析，结果表明，Al-Ca 可促进形成更多的乙长石，减少聚集体中有害孔隙的比例，从而提高了比强度。FP作为轻质骨架支撑在聚合体内部，FP与基体之间良好粘结的ITZ可进一步提高ALAs的比强度。最后，对 ALAs 的耐久性和环境影响进行了评估，结果是可以接受的。总之，这项研究不仅为 PG 循环利用提供了一种绿色方法，还为更高效地生产 ALAs 提出了一种新的技术方案。

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来源期刊

Journal of Cleaner Production 环境科学-工程：环境

CiteScore

20.40

自引率

9.00%

发文量

4720

审稿时长

111 days

期刊介绍： The Journal of Cleaner Production is an international, transdisciplinary journal that addresses and discusses theoretical and practical Cleaner Production, Environmental, and Sustainability issues. It aims to help societies become more sustainable by focusing on the concept of 'Cleaner Production', which aims at preventing waste production and increasing efficiencies in energy, water, resources, and human capital use. The journal serves as a platform for corporations, governments, education institutions, regions, and societies to engage in discussions and research related to Cleaner Production, environmental, and sustainability practices.