In order to deal with the problems of resource waste and environmental pollution caused by solid waste, iron tailings (mainly SiO₂, Al₂O₃ and Fe₂O₃) were used as the main raw material to create a type of lightweight and high-strength ceramsite. Iron tailings, dolomite (industrial grade, purity 98%) and a small amount of clay were combined in a N₂ atmosphere at 1150 °C. X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and a themogravimetric analysis (TGA) were performed and the specific surface area was analyzed to determine the strength and adsorption of the ceramsite. The results of the XRF showed that SiO₂, CaO and Al₂O₃ were the main components of the ceramsite, with MgO and Fe₂O₃ also included. The results of the XRD and SEM-EDS showed that the ceramsite contained several kinds of minerals and was mainly composed of akermanite, gehlenite and diopside, and that the morphology of the internal structure of the ceramsite was mainly massive and contained a small number of particles. The ceramsite could be used in engineering practice to improve the mechanical properties of materials and meet the requirements of actual engineering for the strength of materials. The results of the specific surface area analysis showed that the inner structure of the ceramsite was compact and that there were no large voids. The voids were mainly medium and large, with a high stability and strong adsorption ability. The TGA results showed that the quality of the ceramsite samples will continue to increase within a certain range. According to the XRD experimental results and experimental conditions, it was speculated that in the part of the ore phase containing Al, Mg or Ca in the ceramsite, the elements underwent relatively complex chemical reactions with each other, resulting in the formation of an ore phase with a higher molecular weight. This research provides the basis of characterization and analysis for the preparation of high-adsorption ceramsite from iron tailings and promotes the high-value utilization of iron tailings for waste pollution control.

Ferrochrome slag (FS) and tundish slag (TS) are two typical slags containing high contents of Cr₂O₃ (3.88 wt.%) and MnO (18.69 wt.%), respectively. In this study, batches of ceramics were prepared from FS and TS, and their Cr/Mn leaching behaviors, mechanical properties and microstructures were investigated. Results showed that ceramics with 80 wt.% FS or 85 wt.% TS had acceptable properties. By controlling its composition and sintering temperature, pyroxene or spinel phases could become the main crystalline phases of the fired ceramics containing either of the two slags. For both slag series, pyroxene phases contributed to higher bending strengths, whereas spinel phases led to lower Cr/Mn leaching rates. Both ceramic containing 20 wt.% FS and ceramic containing 85 wt.% TS had the main crystals of pyroxene phases and possessed the highest bending strengths (FS20: 114.52 MPa and TS85: 124.61 MPa). However, both ceramic containing 80 wt.% FS and ceramic containing 25 wt.% TS with main crystals from the spinel phases had the lowest Cr/Mn leaching rates (FS80: Cr 0.05% and TS25: Mn 0.43%). Therefore, optimum designs for the compositions of ceramics from different slags were achieved by changing the proportions of pyroxene and spinel phases to obtain a balance between the high strengths of materials and the stable retention of heavy metal ions. This study provides an important basis for long-term research on the large-scale reuse of heavy metal-containing slags in the ceramic industry.

The pozzolanic activity of lead–zinc tailings (LZTs) was enhanced through mechanical grinding, enabling the preparation of a lead–zinc tailing based composite cementitious material (LZTCC) by combining LZTs with ground granulated blast furnace slag (GGBS), steel slag (SS), and desulfurized gypsum (DG). The compressive strength of LZTCC was evaluated under varying water–cement ratios (W/C) and LZTs dosages. The hydration mechanism was studied via phase composition and microstructural analyses of hydration products. The results revealed that the 28-day pozzolanic activity of LZTs improved to 76% after 2 h of mechanical grinding. LZTCC formulated with 60% LZTs, 22% GGBS, 8% SS, and 10% DG achieved compressive strengths of 13.8 MPa at 7 days and 15.7 MPa at 28 days under a W/C ratio of 0.4. XRD and SEM characterization demonstrated that AFt and amorphous C-S-H gel, along with the unreacted LZT particles, contributed to the overall microstructure, while the former two phases played a significant role in the strength development of LZTCC mortar due to their cementitious reactivity. Heavy metal pollution levels were minimized throughout the process, and the research results could provide a scientific basis for the harmless treatment and resource utilization of LZTs.

The increasing accumulation of industrial solid waste and worsening groundwater pollution pose significant environmental challenges. This study introduces a Si-Ca-Fe-based ceramsite from solid wastes with exceptional Cd adsorption capacity. A comprehensive investigation was conducted on the phase evolution, adsorption properties, and underlying mechanisms of the synthesized ceramsite. The findings revealed that the optimum sintering temperature for the ceramsite, characterized by austenite and pyroxene, was 1140 °C, which balanced mechanical strength and Cd adsorption capacity. Remarkably, the ceramsite (6.0 g) was immersed in 5 L of a Cd(NO₃)₂ solution for 21 h under initial conditions (pH = 7 and temperature = 20 °C), and the ceramsite exhibited a notable Cd adsorption capacity of 5.47 mg/g (initial Cd concentration: 53.42 mg/L), with a maximum theoretical capacity of 9.32 mg/g according to the Langmuir isotherm. An in-depth analysis of adsorption kinetics, phase composition, and EDS data indicated that the primary adsorption mechanism was the zero-valent iron (ZVI) corrosion-driven reaction. This ZVI formed in situ under reducing conditions during the ceramsite’s preparation and subsequently aided in the precipitation of Cd(OH)₂. Additionally, the honeycomb structure of the ceramsite, containing fine pores (approximately 2–5 μm), enhanced physical adsorption via capillary action, further improving Cd removal. These insights offer a robust foundation for crafting efficient, solid waste-derived ceramsite tailored for heavy metal extraction from polluted water, presenting a compelling approach to concurrent waste recycling and environmental remediation.