Circular Valorization of Multi-Source Solid Wastes: Resource Recovery, Organo-Mineral-Based Materials and Low-Carbon Technologies

Dear Colleagues,

The resource value of solid residues is governed by more than their bulk composition. Mineral phases, particle associations, reaction history, and the compatibility of one residue with another determine whether a waste stream can be redirected into a useful material cycle. This perspective is particularly relevant to residues generated across mining, metallurgy, energy production, construction, agriculture, and forestry, where materials with markedly different origins may contain complementary sources of silicon, aluminum, calcium, magnesium, iron, phosphorus, alkalis, carbon, and valuable trace elements. Mine tailings, waste rock, coal gangue, fly ash, slags, bauxite residue, phosphogypsum, construction residues, biomass ash, crop residues, forestry residues, and related byproducts therefore merit consideration not only as disposal burdens but also as secondary resources whose mineralogical and chemical features can be deliberately matched. Cross-sector combinations offer a route to reduce dependence on virgin raw materials, improve the use efficiency of difficult residues, and create forms of industrial symbiosis that are difficult to achieve when each waste stream is treated in isolation.

This Special Issue focuses on the scientific and technological basis for utilization of such multi-source solid wastes, with particular attention paid to mineralogical characterization, phase transformation, selective separation, resource recovery, and the design of useful products from residual matrices. Contributions may address process mineralogy, physical beneficiation, hydrometallurgy, pyrometallurgy, bioleaching, mechanochemical treatment, hydrothermal conversion, thermal activation, chemical activation, and hybrid process routes for recovering critical metals, strategic elements, phosphorus, silicon, aluminum, calcium, magnesium, and other valuable components. Studies that clarify how mineral occurrence, intergrowth, amorphous content, surface chemistry, or reaction pathways control separation efficiency and extraction selectivity are especially relevant. Work on detoxification and impurity control is also encouraged where it is directly linked to resource recovery or subsequent material use, including the stabilization of potentially hazardous elements and the management of salts, sulfides, or other phases that can constrain large-scale utilization.

Equal emphasis is placed on transforming the remaining mineral matrix into products with measurable technical and environmental value. Relevant topics include supplementary cementitious materials, alkali-activated binders, geopolymers, ceramics, glass ceramics, mine backfill, adsorbents, catalysts, mineral carbon composites, soil and environmental amendments, and other mineral-based functional materials derived from single or blended waste streams. Low-carbon pathways form an important part of this theme and include carbon dioxide mineralization, accelerated carbonation, low-temperature activation, energy-efficient processing, heat and mass integration, and process configurations that reduce both landfill demand and greenhouse gas emissions. Life-cycle assessment, techno-economic analysis, material flow analysis, industrial symbiosis, and data-driven process optimization can provide the system-level evidence needed to judge whether a laboratory route is practical beyond the laboratory. Original research articles and critical reviews that connect mineralogical understanding with recovery performance, material function, carbon reduction, environmental safety, and circular economy outcomes are welcome, particularly studies that reveal transferable principles for coupling agricultural and forestry residues with mineral-rich industrial or mining wastes.

Dr. Wei Zhang
Dr. Yaguang Wang
Guest Editors

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