Mining and metallurgical wastes contain reactive Fe-, Al-, Ca-, Mg-, and Mn-bearing phases. These phases can be used for water treatment. Their performance depends on mineral accessibility, processing history, and water chemistry rather than waste identity alone. This review compares tailings, slags, red mud, and leaching residues for inorganic and organic contaminant removal, focusing on mechanisms, modification intensity, and validation. Cations are removed by ion exchange, surface complexation, and precipitation, whereas anion removal relies on Fe/Al sites, Ca-mediated mineral formation, and redox reactions. Organic treatment proceeds through adsorption or catalytic transformation and generally requires activation or additional functional phases. Red mud and blast-furnace slag showed the broadest applicability across both pollutant classes, although no unchanged formulation was validated for both. Under favorable conditions, waste-derived sorbents can achieve pollutant-removal efficiencies approaching 100% in synthetic solutions. However, their performance generally decreases in real wastewater and under continuous or cyclic operating conditions, with reported efficiency losses reaching approximately 25 percentage points. Deployment and machine-learning-assisted selection require application-matched processing, real-water and static/dynamic validation, and standardized reporting of separation, regeneration, cyclic stability, mass loss, secondary leaching, and spent-material fate.

Knowledge of the heterogeneous composition of mineral substances and technogenic materials is vital in the development of technological designs and in environmental impact assessments. However, the simultaneous application of analytical methods often reveals discrepancies between different methods that cannot be explained by the commonly used scalar agreement metrics. The current study suggests the possibility of evaluating inter-methodical agreement in the compositional data of heterogeneous substances using the example of lead smelting slag compositional data. The compositional data of 96 samples of lead smelting slag were analyzed using independent methods of XRF, ICP-OES and AAS. The agreement between the obtained results was evaluated at three levels of hierarchy: element-wise bias and dispersion, structured variability between methods and preservation of covariance structure; PCA was used as the tool for the evaluation. High agreement between the ICP-OES and AAS methods was found for the transition metals (r ≈ 0.97–0.99), with negligible bias. The presence of increased dispersion and deviations in the inter-methodical agreement was found in the case of the methods compared with the XRF method, especially for the matrix components such as Si (r ≈ 0.92). Coefficients of variation for metallic elements stay between 12 and 15%, but XRF has shown consistently higher variability for certain elements. PCA results show that despite local differences, the main covariance structure was kept across methods, with the first two components explaining about 40–45% of total variance. These results clearly indicate that high correlation does not necessarily ensure methodological interchangeability. The hierarchical framework proposed here will provide a reproducible basis for cross-method validation and support reliable data integration in complex mineral systems.

This work investigated the extraction behavior of Zn, Cu, and Fe during sulfuric acid leaching of metallurgical waste from the Ust-Kamenogorsk zinc production plant. At the same time, the detailed kinetic analysis was restricted to Zn dissolution. This study aimed to determine the structural and morphological characteristics of metallurgical wastes and the extraction efficiencies of Zn, Cu, and Fe, and to evaluate the apparent kinetics of Zn dissolution comparatively. The phase composition of the initial and mechanically treated samples was studied by X-ray diffraction analysis, functional groups by FTIR spectroscopy, and morphological features by scanning electron microscopy. Leaching experiments were conducted to assess the effect of sulfuric acid concentration, temperature, and process duration. The results showed that mechanical treatment produced qualitative morphological and structural changes in the slag and was accompanied by improved extraction of Zn, Cu, and Fe during sulfuric acid leaching. The extraction behavior depended on the experimental variable investigated. In the sulfuric acid concentration series, extraction from the mechanically treated sample reached 70.55 ± 0.88% for Zn, 90.50 ± 0.47% for Cu, and 42.37 ± 0.47% for Fe at 1.0 M H₂SO₄. In the leaching time series conducted at 1.0 M H₂SO₄ and 75 °C, Zn extraction reached 78.06 ± 0.92% at 120 min after mechanical treatment, whereas Cu extraction reached its maximum of 90.78 ± 0.55% at 60 min. The time-dependent extraction behavior differed among the investigated metals, and no single leaching time maximized Zn, Cu, and Fe extraction simultaneously. Comparative analysis using Shrinking Core Model expressions indicated that both surface-reaction and product-layer-diffusion expressions provided comparable descriptions of the Zn leaching data; however, the limited number of kinetic data points does not allow definitive identification of a unique rate-controlling mechanism. For Zn dissolution, the apparent activation energies were 8.16 and 10.17 kJ mol⁻¹ for the surface chemical reaction expression and 14.37 and 17.81 kJ mol⁻¹ for the product-layer diffusion expression before and after mechanical treatment, respectively. A conceptual leaching pathway based on the available experimental observations was proposed to relate the observed structural and morphological changes to Zn extraction and the formation of a gypsum-containing solid residue. The results indicate that mechanical treatment is a promising pretreatment approach for improving the hydrometallurgical processing of the investigated metallurgical waste under the tested conditions.

In the present paper, a route for the simultaneous recovery of Fe, Cu, and Zn from the leaching filtrate of copper flotation tailings through controlled co-precipitation into a single magnetic ferrite-like product is proposed. Unlike conventional sequential recovery of individual metals, the filtrate was used as a combined precursor for substituted magnetite and a Cu–Zn-containing spinel. Across a series of 20 samples, the Fe:(Cu+Zn) molar ratio ranged from 2.05 to 2.47, with a mean value of 2.25, corresponding to the solid-solution region between MFe₂O₄ and Fe₃O₄. As the pH increased, iron precipitated first, followed by copper and zinc; at pH 9.5, Fe and Cu were almost completely co-precipitated, while Zn recovery reached approximately 98%. Calcination of the dried precipitate at 600 °C induced crystallization of the spinel phase, consolidation, and partial sintering of the aggregates. A predominantly magnetite-like spinel product was retained under nitrogen, whereas calcination in air resulted in the formation of a substantial hematite fraction. At a magnetic flux density of 1050 mT, the recoveries of the as-dried precipitate, the nitrogen-calcined product, and the air-calcined product were approximately 86%, 96%, and 90%, respectively.

This study presents an integrated approach for the processing of technogenic tailings from the Balkhash concentrator, combining hydrocyclone classification, microfluidic separation, bioleaching, and geopolymer synthesis. The tailings are characterized by a fine-dispersed silicate matrix and low concentrations of valuable metals, which limit the efficiency of conventional processing methods. Hydrocyclone classification enables effective size separation and stabilization of particle size distribution, providing suitable feed for downstream processes. Microfluidic separation demonstrated selective concentrations of copper, increasing its content in the central fraction up to 0.52–0.58% with recovery up to 70–75% under optimal flow conditions. Bioleaching experiments using acidophilic microorganisms (Acidithiobacillus ferrooxidans and A. thiooxidans) revealed strong dependence on process parameters, achieving maximum recoveries of Cu (63%), Zn (58%), and Fe (43%) at pH 1.8–1.9 and 31–32 °C. The solid residues after bioleaching, composed mainly of aluminosilicates, were successfully utilized for geopolymer synthesis. The obtained geopolymer samples exhibited low water absorption (not exceeding 9.1%) and high compressive strength, meeting the requirements of Kazakhstan standard 26633-2015 (ISO 22965-1). The production of geopolymer materials from these residues contributes to the environmental rehabilitation of tailings storage facilities. The novelty of this work lies in the integration of microfluidic separation with bioleaching for fine tailing processing, enabling both selective metal recovery and subsequent conversion of residues into functional geopolymer materials. The proposed approach provides a sustainable pathway for simultaneous resource recovery and waste valorization, contributing to circular economy strategies in the metallurgical industry.

The dump slags of copper smelters contain considerable amounts of Cu and Zn, but hydrometallurgical valorization is hindered by the co-dissolution of iron. The present work investigates the effects of acid concentration, temperature and hydrogen peroxide on the distribution of Cu and Zn relative to Fe during atmospheric sulfuric acid leaching of a fayalitic dump slag from the Balkhash copper smelter (Kazakhstan; 0.9 wt% Cu, 3.7 wt% Zn, 36.7 wt% Fe). At 1.5 mol/L H₂SO₄, 60 °C and 180 min, 87.1% Cu and 76.4% Zn were extracted together with 16.5% Fe, corresponding to a Cu/Fe extraction ratio of 5.3. Raising the temperature to 80 °C nearly doubled Fe dissolution (32.3%), whereas 2.0% (v/v) H₂O₂ enhanced Cu and Zn extraction by just 5.7 and 9.9 percentage points, respectively, but enhanced Fe extraction to 52.7%, reducing the Cu/Fe ratio to 1.8. The first stage (X < 0.65) followed the chemical-control variant of the shrinking-core model with apparent activation energies of 29.6 (Cu) and 26.9 kJ/mol (Zn) compatible with mixed control. Eyring analysis showed ΔH^‡ of 27.0 and 24.2 kJ/mol and ΔS^‡ of −236 and −244 J/(mol·K); the similar rate constants and statistically indistinguishable activation energies for Cu and Zn are compatible with release via a single rate-limiting process. For this slag type, metal-to-iron selectivity is highest for non-oxidative leaching at moderate temperatures rather than oxidant-assisted leaching.