This study investigates the extrusion-based 3D printing response of hybrid geopolymer-cement mortars formulated with copper mine tailings and silt as alternative raw materials. A Taguchi design was employed to evaluate the effects of extrusion pressure, nozzle diameter-to-layer height (ND/LH) ratio, and print speed under varying Z-Max settings on print quality, dimensional accuracy, and defect formation. Twenty-seven experimental runs using a hollow cylindrical geometry were conducted, with both qualitative and quantitative assessments of surface finish, layer consistency, and dimensional errors. Results showed that a Z-Max setting of 413 mm yielded the highest print success rate, while settings between 412.7 and 412.9 mm led to frequent failures due to over-extrusion, under-extrusion, and poor interlayer adhesion. The ND/LH ratio was identified as the most statistically significant factor, strongly affecting total height (p = 0.000) and outer diameter (p = 0.002), whereas extrusion pressure had minimal influence. Best parameters for height and dimensional accuracy were 2.5 bar pressure, a 4:1 ND/LH ratio, and 20 mm/s print speed. For improved inner and outer diameter control, 2 bar pressure, a 2:1 ND/LH ratio, and 15 mm/s proved more effective. A demonstration block printed using the best-performing settings confirmed the influence of path design on geometric fidelity. Notable defects such as edge curvature, center voids, and inconsistent layering underscore the importance of refined path coding. In summary, the findings support the viability of mine tailings and silt in 3D-printable construction applications and highlight the critical role of process parameter optimization in achieving geometric precision.

Plasma treatment of ores, and ore concentrates is used most often to improve the separation performance of ore minerals and non-metallic gangue, as well as for the “plasma grinding” (softening) of ores to reduce the time of subsequent mechanical grinding and energy costs. Non-equilibrium, low-temperature plasma of dielectric barrier discharge (LTP-DBD), characterized by high pressure (hundreds of Torr), high electron temperatures (electron temperatures can reach several electron volts), and low temperature of the process gas (close to the temperature of dielectric barriers) [1] is considered the most precise, efficient, and safe tool for modifying the composition, structure, and properties of the surfaces of various materials, including geomaterials [2–5]. A DBD occurs in a gas under the action of an alternating voltage applied to the conducting electrodes, provided that at least one electrode is covered with a dielectric layer on the side of the discharge gap. The discharge can be carried out in oxygen or air at atmospheric pressure, room temperature, and natural air humidity, i.e., under normal conditions and without the use of a special plasma gas. For practical applications, the problem of obtaining a diffuse discharge in air at atmospheric pressure is relevant, since in this case the effect of the DBD plasma spreads uniformly over the largest possible area [1,3]. During the our experiments, the mineral samples filled the gap between the active metal electrode and the dielectric barrier and were separated from the electrode by a small air gap. The mineral particles were affected by the following DBD factors: a high-strength pulsed electric field, ionic wind, and low-temperature plasma products in the form of chemically active compounds, such as ozone O₃, and other agents. When conducting experiments on the effect of DBD on the structural and physicochemical properties of minerals, the following rational parameters of pulses initiating a barrier discharge we established in [3]: duration of the leading edge of the pulse 250–300 ns, pulse duration 8µs, voltage on the electrodes in the barrier discharge cell 20 kV, repetition frequency of the pulses initiating the discharge ~15 kHz, time range of plasma minerals treatment was t_treat=10–150 s. The dimensions of the electrodes of the DBD discharge cell significantly exceeded the length of the interelectrode gap, which was 5mm. According to SEM, defects of a regular triangular shape formed on the surface of galena samples due to the removal of microcrystalline fragments due to ponderomotive forces in the region of a strong electric field. On the surface of chalcopyrite, the formation of irregularly shaped defects was observed, and on the surface of sphalerite, microchannels of electrical breakdown formed, bordered by the sinter formation material of oxide microphases. The change in the morphology of the surface of sulfides caused softening, and a significant decrease in the microhardness of minerals as a whole by 20–30%. Short (t_treat=10 s) treatment of pyrrhotite caused a shift in the electrode potential of the mineral to negative values (φ=−60mV, at pH 9.7–12) [4], which predetermines the effect of reducing the sorption activity of pyrrhotite with respect to xanthate, hence its flotation recovery reduction. In [5] rational conditions were determined for t_treat=30–40s) plasma pretreatment, in which the efficiency of pyrite and arsenopyrite separation in monomineral flotation increased considerably: an increase in pyrite recovery was 27% while the yield of arsenopyrite decreased by 10–12%. Thus, the method of plasma-chemical processing of geomaterials with using of DBD has great prospects for practical applications in the processes of selective separation of semiconductor ore minerals (sulfides, oxides). In rock-forming minerals, the following features of changes in surface properties when exposed to DBD were established [3]. With increasing plasma treatment time of the quartz samples t_treat=10–150s, smoothing of surface irregularities and the formation of microdefects of irregular shape (≤3µm) occurred This caused weakening and a monotonous decrease in the microhardness of the mineral from 1420 up to 1320 kgf/mm² in the original and modified at t_treat=150 s states, respectively. The maximum relative change (decrease) in microhardness ∆HVmax was ~7%. The contact angle of wetting the quartz surface with water changed nonmonotonically. As a result of short-term exposure (t_treat=10–30s), the contact angle increased from 44° to 53°, which indicates an increase in the hydrophobicity of the mineral’s surface, while with an increase in t_treat, a gradual decrease in the contact angle was observed to initial values. The possibility of modifying the hydrophobicity of quartz by energy impacts can be used in industrial processes for separating the mineral from impurities and selective (reverse) flotation of ferruginous quartzites.

Unlike most other metals, tungsten does not form rich ores. As known tungsten deposits are depleted, the profitability of tungsten production declines. The transition to underground processing of tungsten ores makes it possible to overcome this negative trend. To achieve this, tungsten ore is ground in a ball mill, flooded by a water-salt solution with an intermediate density between the valuable mineral and the waste rock. Thus, as the gangue components are released from the intergrowths with the valuable ore minerals, this ballast floats up, avoiding the energy cost of additional size reduction. After the separation products have been extracted, they are wringed out in a centrifuge and the last remnants of the liquid phase are regenerated from the wet surface. The water-salt solution, regenerated to its original density, is returned to the head of the process. As a working medium for carrying out such a process, aqueous-salt solutions based on heteropolytungstates are used.

Hydrodynamic cavitation (HC) is gaining traction in the mining industry as an effective means to improve flotation performance, particularly for fine and ultrafine minerals [1, 2]. While HC has shown promising results in industrial flotation circuits, the lack of mechanistic understanding has hindered its optimal implementation. In particular, the specific ways in which HC influences key subprocesses – such as bubble–particle attachment – remain insufficiently explored. This study addresses this gap by investigating how HC alters the physicochemical environment of flotation systems, focusing on the role of soluble gases and the formation of surface nanobubbles (NBs).

We hypothesize that HC enhances flotation primarily by increasing dissolved gas concentrations in water and facilitating the nucleation and stabilization of interfacial nanobubbles. These NBs can alter surface properties by increasing hydrophobicity and strengthening hydrophobic interactions [3, 4], thereby improving the efficiency of bubble–particle attachment – a crucial step in flotation that dictates recovery and kinetics. Despite the increasing application of HC in industry, this surface-science-based mechanism has not been systematically studied or linked to flotation outcomes.

To test this hypothesis, two complementary experimental systems were used. A modified laboratory-scale mechanical flotation cell was applied to coal, representing an industrially relevant mineral system. In parallel, a modified Hallimond tube was employed to float hydrophobized silica particles under controlled conditions, allowing for assessment of the attachment process. Both systems were tested with and without HC treatment to distinguish their specific effects on flotation performance and surface interactions.

The results confirm that HC significantly enhances flotation outcomes. In the coal system, flotation recovery improved by 11% using HC-treated water, and by 15% when particles were directly exposed to HC, with marked increases in flotation rate and collection efficiency. In the silica system, recovery rose by 21%, and attachment efficiency increased by more than threefold. These improvements were associated with larger particle aggregates, greater bubble wrap angles, elevated gas solubility, reduced surface tension, and disappearance of SFG (Sum-Frequency-Generation Vibrational Spectroscopy) peak at 3700 cm^-1 of the free OH dangling at the bubble surface – all indicative of favorable conditions for nanobubble formation and enhanced surface hydrophobicity [5].

This work provides compelling evidence that the flotation benefits of HC are underpinned by its effects on surface chemistry – specifically, the generation of soluble gases and interfacial nanobubbles that promote more efficient bubble–particle interactions. By bridging industrial flotation performance with fundamental surface science, this study offers novel insights into the mechanisms of HC-enhanced flotation. These findings lay the groundwork for more rational design and optimization of cavitation-based technologies in mineral processing, advancing the development of efficient and sustainable flotation strategies.

This study aims to quantify the amount of iron recoverable from iron ore tailings through physical separation methods applied both individually and in combined sequences. The separation techniques employed include the Humphrey spiral concentrator, magnetic drum separator, and shaking table, all widely used for fine mineral processing. The experiments were designed to evaluate the iron content recovered using each method separately and all six possible combinations of the three techniques in different sequences. For each configuration, tailings samples were processed, and the resulting concentrate was analyzed to determine iron recovery efficiency, yield, and grade. The results showed that while individual methods such as the shaking table or magnetic separation yielded moderate iron recoveries, sequential processing— particularly combinations starting with gravity concentration (Humphrey spiral) followed by magnetic separation—produced significantly higher iron recovery rates. The study demonstrates that proper sequencing of physical separation techniques can substantially enhance the beneficiation potential of iron ore tailings, contributing to resource recovery and environmental demage mitigation.

Mine waste remains a persistent challenge for the minerals industry, posing significant environmental concerns if not properly managed. The 1996 Marcopper mining disaster in Marinduque, Philippines, left a legacy of mine tailings that continue to threaten local ecosystems and communities. This study investigates the valorization and stabilization of Marcopper river sediments contaminated with mine tailings using a combined geopolymerization and cement hydration approach. Hybrid mortar samples were prepared with 7.5%, 15%, 22.5%, and 30% mine tailings by weight, incorporating potassium hydroxide (KOH) at 1M and 3M concentrations as alkaline activators, along with ordinary Portland cement (OPC). The mechanical properties of the hybrid geopolymer-cement mortars were evaluated through unconfined compressive strength tests, while their crystalline structure, phase composition, surface morphology, and chemical bonding characteristics were also analyzed. Static leaching tests were conducted to assess the mobility of heavy metals within the geopolymer matrix. Compressive strengths ranged from 24.22 MPa to 53.99 MPa, satisfying ASTM C150 requirements. In addition, leaching results confirmed effective heavy metal encapsulation and immobilization, demonstrating the potential of this method for mitigating environmental risks associated with mine tailings.

Picui is one of the most traditional municipality of mineral producing of serido region, state of Paraiba, Brazil, where the mining prospector dates back to the late 19th century. Occupies a significant portion of the of Pegmatític Borborema Province, of immense geological diversity. Supracrustal rocks of the Seridó Group (schists, quartzites and gneisses) were affected by granitic, pegmittic and volcanic magmatic events, imprinting batholiths, plugs dikes, sills and veins. The set was subordinated to compressional tectonic events evidenced by the Picuí-João Câmara, Frei Martinho and Santa Mônica shear zones, imprinting failed and folded fractures. Various metallic and nonmetallic minerals are extracted economically of pegmatite bodies, such is quartz, feldspar, muscovite, beril, tantalite, spodumene (used in the manufacture of batteries for electric cars), in addition to granites for ornamental stone and civil construction and clays for red pottery, completing the mineral production chain. The Mining forms the basis of the economy of the region, especially in periods of major droughts, when agricultural activities become impractical. The artisanal mining (“garimpo”)  is the principal activity on region, causing significant environmental degradation due to lack of planning and specialized professionals.  Development in technology, increasing environmental awareness of the public and private sectors and the implementation of new Laws must inevitably be applied of the mineral sector to adhere to the principles of sustainability of clean development. This work presents the many faces of the small mining of  Picui and offers challenges, questions and opportunities for mining support.

Gem mining in Sri Lanka has been a cornerstone of the nation's economy for centuries, renowned globally for its high-quality gemstones. However, this thriving industry generates vast quantities of waste, with most of it being discarded or used for backfilling, leading to severe environmental degradation and loss of valuable resources. My research has revealed that this so-called waste is, in fact, an untapped secondary resource for critical rare earth elements (REEs), essential for high-tech industries and the global transition towards green energy. This study presents a transformative model for sustainable REE recovery from gem mining waste, aligning with circular economy principles in mineral processing. It focused on the gem mining waste at the basin of Kulu river, Sri Lanka, where the organic-rich clay layer beneath the gem-bearing gravel exhibited a total REE concentration of 5095 mg/kg, with a nearly balanced distribution of light (LREEs) and heavy REEs (HREEs). Through a combination of advanced chemical leaching using H2SO4 and optimized physical upgrading techniques, it is achieved an exceptional REE recovery of 94%. The leaching process was determined to be controlled by lixiviant diffusion through unreacted particles, providing valuable insights for process scaling. Furthermore, simple wet sieving and density separation for gem-bearing gravel layer enhanced the REE content to a remarkable 3.0% REO in the concentrate. However, the detection of high uranium levels (up to 814 mg/kg) in the concentrate emphasizes the need for responsible waste management and radiation safety protocols. Beyond technical innovation, this research aligns with Environmental, Social, and Governance (ESG) principles, offering a model for responsible and sustainable resource management in the mining industry. These findings unlock the economic potential of gem mining waste in Sri Lanka and provide a blueprint for sustainable REE recovery from gem mining waste worldwide. This study demonstrates how a circular economy approach can transform waste into a strategic resource, supporting global efforts to secure REE supply chains, minimize environmental impacts, and promote sustainable development.

This study investigates the effects of incorporating iron ore tailings in their raw (as-received) state as a partial substitute for natural sand and stone powder in the production of interlocking concrete blocks. The research aims to evaluate the technical viability and environmental benefits of utilizing this mining residue as an alternative fine aggregate. Granulometric analyses were conducted to determine the compatibility of the tailings with standard grading curves recommended by Brazilian technical norms. Experimental concrete mixes were formulated with varying replacement percentages (6%, 13%, and 20%) of the tailings, and corresponding curves were compared to reference limits for block production. The results demonstrated that the inclusion of iron ore tailings from 6% up to 20% maintained the granulometric conformity necessary for non-structural concrete block fabrication and testing the bloc's compression resistence for 30 days as brazilian normatives indicate . This approach offers a sustainable and cost-effective solution by valorizing mining waste and reducing the demand for virgin raw materials.