The large-scale stacking of iron tailings poses challenges to the eco-environment and mining industry. Materializing tailings treatment is an effective way to solve this bulk solid waste problem. In this study, using iron tailings rich in hematite and calcite as the main raw material, we prepared a cementitious material with about 80wt% iron tailings content by mechanical ball milling and alkali activation, with the addition of cement and slag powder. Elemental analysis of the raw materials revealed Fe, Ca, and Si contents in the iron tailings of 41.248%, 33.949%, and 20.211%, respectively, and the main mineral phases were calcite, hematite, and quartz. Our research demonstrated that mortar made from iron tailings ball-milled for 15 min exhibited the best properties, with an activity index of 108.1%. When the alkali activator content was 6%, the compressive strength of the test blocks was optimal, reaching 7.9 MPa after 28-day curing. We also conducted tests on standard consistency, setting time, and hydraulic properties, confirming the potential activity of iron tailings. Using orthogonal experiments, we optimized the proportions of each component and explored the effects of tailings content and water - binder ratio on the mechanical properties of the samples. Furthermore, we analyzed the microstructure of the cementitious material with different tailings contents and curing ages using FTIR and XRD and proposed its hydration mechanism.

Electrolytic manganese residue (EMR), an acidic by-product from manganese production, presents dual challenges of environmental pollution and resource waste. This study developed a silicon–manganese organic compound fertilizer (SMOCF) via the aerobic fermentation of EMR supplemented with bagasse, molasses, and activated sludge. The physicochemical analysis revealed that the EMR’s composition was dominated by silicon (7.1% active Si), calcium, sulfur, and trace elements. Critical parameters during composting—including water-soluble Mn (1.48%), organic matter (8.05%), pH (7.4), moisture (20.28%), and germination index (GI = 87.78%)—met organic fertilizer standards, with the GI exceeding the phytotoxicity threshold (80%). The final SMOCF exhibited favorable agronomic properties: neutral pH, earthy texture, and essential macronutrients (1.36% K, 1.11% N, 0.48% P). Heavy metals (As, Cd, Cr, Pb) in the SMOCF predominantly existed in stable residual forms, with total concentrations complying with China’s organic fertilizer regulations (GB/T 32951-2016). The ecological risk assessment confirmed a minimal mobilization potential (risk assessment code < 5%), ensuring environmental safety. This work demonstrates a circular economy strategy to repurpose hazardous EMRs into agriculturally viable fertilizers, achieving simultaneous pollution mitigation and resource recovery. The optimized SMOCF meets quality benchmarks for organic fertilizers while addressing heavy metal concerns, providing a scalable solution for industrial EMR valorization. Further studies should validate the field performance and long-term ecological impacts to facilitate practical implementation.

This study develops a one-pot anodic templating electrodeposition strategy using dual-cation-crosslinking and interpenetrating networks, coupled with pulsed electrical signals, to fabricate a vessel-mimetic multilayered tubular hydrogel. Typically, the anodic electrodeposition is performed in a mixture of sodium alginate (SA) and carboxymethyl chitosan (CMC), with the ethylenediaminetetraacetic acid calcium disodium salt hydrate (EDTA·Na₂Ca) incorporated to provide a secondary ionic crosslinker (i.e., Ca²⁺) and modulate the cascade reaction diffusion process. The copper wire electrodes serve as templates for electrochemical oxidation and enable a copper ion (i.e., Cu²⁺)-induced tubular hydrogel coating formation, while pulsed electric fields regulate layer-by-layer deposition. The dual-cation-crosslinked interpenetrating hydrogels (CMC/SA-Cu/Ca) exhibit rapid growth rates and tailored mechanical strength, along with excellent antibacterial performance. By integrating the unique pulsed electro-fabrication with biomimetic self-assembly, this study addresses challenges in vessel-mimicking structural complexity and mechanical compatibility. The approach enables scalable production of customizable multilayered hydrogels for artificial vessel grafts, smart wound dressings, and bioengineered organ interfaces, demonstrating broad biomedical potential.