Effect of sintering temperature on lightweight aggregates manufacturing from copper contaminated soil. Issue 22 (15th November 2021)

• Record Type: Journal Article
• Authors: Li, Baodong; Jian, Shouwei; Zhu, Jiaoqun; Gao, Xin; Gao, Wenbin
• Is Part Of: Ceramics international. Volume 47:Issue 22(2021)
• Page Start: 31319
• Page End: 31328
• Publication Date: 2021-11-15
• Subjects: Lightweight aggregates -- Immobilization -- Copper -- Contaminated soil -- Micro-CT; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.08.005
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Manufacturing lightweight aggregate (LWA) at high temperature is an effective way to immobilize heavy metals in solid waste. This work investigated the performance and solidification mechanism of LWA prepared from copper contaminated soil. The volume expansion of LWA could reach a maximum of 28%, and its lowest density accounted of 1.5 g/cm 3, which met the standard requirements. Optical microscope and micro-CT test illustrated that the addition of Cu leaded to obvious phase separation in LWA. The Cu leaching result of LWA first increased and then dropped with the temperature. The XRD test found that the main formation phase of Cu in LWA were t-CuFe2 O4 and amorphous phase that they had different acid resistance ability. XPS revealed that the main cause of the agglomeration of liquid phase in LWA was the chain broken reaction between Cu and Si–O tetrahedron. SEM-EDS results showed that the distribution of Cu and Si had a strong correlation, which meant that Cu mostly formed amorphous phase. This work showed the uniqueness of Cu in the high temperature immobilization and pointed out the best immobilization target phase. Graphical abstract: Image 1 Highlights: LWA phase separation due to the high temperature fracturing function of Cu on Si–O tetrahedron. Abnormal increase of Cu leaching in LWA by the sintering temperature around 1120 °C. The negative influence of amorphous phase on immobilization of Cu. The immobilization mechanism was analyzed comprehensively.