Search Results (160)

This study proposed a mechanochemical activation strategy using ethanol-diisopropanolamine (EDIPA) to improve the grindability and hydration reactivity of basic oxygen furnace slag (BOFS), aiming for its large-scale industrial utilization. The incorporation of EDIPA significantly refined the particle size distribution and reduced the repose angle. As a result, the compressive strength of BOFS paste increased by 25.4 MPa at 28 d with only 0.08 wt.% EDIPA. Conductivity tests demonstrated that EDIPA strongly complexes with Ca²⁺, Al³⁺, and Fe³⁺, facilitating the dissolution of active mineral phases, such as C₁₂A₇ and C₂F, and accelerating hydration reactions. XRD and TG analyses confirmed that the incorporation of EDIPA facilitated the formation of Mc (C₄(A,F)ČH₁₁) and increased the content of C-S-H, both of which contributed to microstructural densification. Microstructural observations further revealed that EDIPA refined Ca(OH)₂ crystals, increasing their specific surface area from 4.7 m²/g to 35.2 m²/g. The combined effect of crystal refinement and enhanced hydration product formation resulted in reduced porosity and improved mechanical properties. Overall, the results demonstrated that EDIPA provided an economical, effective, and scalable means of activating BOFS, thereby promoting its high-value utilization in low-carbon construction materials. Full article

Volcanic rock is a natural mineral material which has garnered interest for its potential application in water treatment due to its unique physicochemical properties. In this study, we prepared a polysilicate aluminum chloride (PSAC) coagulant using volcanic rock which exhibited good coagulation–flocculation performance. Further investigation into the influence of synthetic parameters, such as calcination temperature, reaction time, and alkali types, on the structure and performance of a volcanic rock-derived coagulant was conducted. Techniques including Scanning Electron Microscopy, Energy-Dispersive Spectroscopy, Fourier-Transform Infrared Spectroscopy, and X-Ray Diffraction were utilized to characterize it. Also, a ferron-complexation timed spectrophotometric method was used to study the distribution of aluminum species in the coagulant. Results indicated that the volcanic rock that was treated with acidic and alkaline solutions had the potential to form PSAC with Al-OH, Al-O-Si, Fe-OH, and Fe-O-Si bonds, which influenced the coagulation–flocculation efficiency. An acid leaching temperature of 90 °C, 8 mL of 2 mol/L NaOH, a reaction time of 0.5 h, and a reaction temperature of 60 °C were conducive to the preparation. A higher temperature could result in a higher proportion of Alb species, and, at 100 °C, the Ala, Alc, and Alb were 29%, 24%, and 47%, respectively, achieving a residual turbidity lower than 1 NTU at an appropriate dosage, as well as a reduction of over 0.1 to 0.018 in the level of UV₂₅₄. The findings of this study provide a feasible method to prepare a flocculant using volcanic rock. Further application is expected to yield good results in wastewater/water treatment. Full article

The Tuztaşı low-sulfidation epithermal Au–Ag deposit (Biga Peninsula, Türkiye) records a multi-stage hydrothermal history that can be interpreted through the trace and rare-earth-element (REE) chemistry of quartz. High-precision LA-ICP-MS analyses of five representative quartz samples (23 ablation spots; 10 analytically robust) reveal two fluid stages. Early fluids were cold, dilute meteoric waters (δ¹⁸O₍H₂O₎ ≈ −6.8 to +0.7‰), whereas later fluids circulated deeper, interacted with felsic basement rocks, and evolved in composition. Mineralized quartz displays marked enrichment in As (raw mean = 2854 ± 6821 ppm; filtered mean = 70 ± 93 ppm; one spot 16,775 ppm), K (498 ± 179 ppm), and Sb (57.8 ± 113 ppm), coupled with low Ti/Al (<0.005) and elevated Ge/Si (0.14–0.65 µmol mol⁻¹). Chondrite-normalized REE patterns show pronounced but variable LREE enrichment ((La/Yb)_n ≤ 45.3; ΣLREE/ΣHREE up to 10.8) and strongly positive Eu anomalies (δEu ≤ 9.3) with slightly negative Ce anomalies (δCe ≈ 0.29); negligible Ce–Eu covariance (r² ≈ 0.05) indicates discrete redox pulses. These signatures indicate chemically evolved, reducing fluids conducive to Au–Ag deposition. By contrast, barren quartz is characterized by lower pathfinder-element contents, less fractionated REE profiles, higher Ti/Al, and weaker Eu anomalies. A composite exploration toolkit emerges: As > 700 ppm, As/Sb > 25, Ti/Al < 0.005, Ge/Si > 0.15 µmol mol⁻¹, and δEu ≫ 1 reliably identify ore-bearing zones when integrated with δ¹⁸O data and fluid-inclusion microthermometry from earlier studies on the same vein system. This study provides one of the first systematic applications of integrated trace-element and REE analysis of quartz to a Turkish low-sulfidation epithermal system, offering an applicable model for vectoring mineralization in analogous settings worldwide. Full article

The treatment with an alkali (sodium hydroxide) solution of acid-activated montmorillonite clay minerals resulted in a reduction in specific surface area. However, a significant enhancement in the removal of basic blue-41 dye solution was achieved compared to acid-activated samples only (first step of activation) and to the raw montmorillonite clay. The obtained products were characterized using different techniques. The results indicated that the acid-activated montmorillonites exhibited different physicochemical properties than the starting raw montmorillonite, with a reduction in the cation exchange capacity and improvements in the specific surface area (from 5 m²/g to 274 m²/g) and total pore volume (from 0.031 cm³/g to 0.450 cm³/g) due to the formation of the amorphous silica phase. However, the treatment with NaOH solution was accompanied by significant reductions in the specific surface area (from 274 m²/g to 18 m²/g) and total pore volume (from 0.450 cm³/g to 0.02 cm³/g) due to the dissolution of the formed amorphous silica phase, as confirmed through ²⁹Si MAS NMR and FTIR techniques. In addition, the SiO₂/Al₂O₃ molar ratios were close to those of the starting montmorillonite clay. The removal of the cationic basic blue-41 was optimized under different conditions, such as different initial concentrations, adsorbent doses, and pHs of the dye solution. The maximum removal capacities of acid-activated clays were in the range of 45 mg/g to 80 mg/g and decreased with the extent of the acid activation process. However, the capacities were enhanced after NaOH treatment and reached values in the range of 80 to 120 mg/g. Enhancing the surface area had less of an impact on the materials’ removal ability. The obtained materials performed well in seven adsorption–regeneration cycles, showing a 70% reduction in removal effectiveness. Full article

In this study, Bacillus amyloliquefaciens SQ-2, previously isolated from a commercial watercress paste, was investigated for its potential in promoting rice growth in Pb/Al-contaminated acidic soil, especially when used in conjunction with corn straw biochar. Firstly, the physiological properties of rice were enhanced, with the activities of catalase and superoxide dismutase increasing by 162.5% and 162.9%, respectively. Additionally, the total phenolic and chlorophyll contents of rice increased by 17.6% and 83.7%, respectively. Secondly, the nutrient content of the rice rhizosphere soil was improved. In particular, nitrate nitrogen, available potassium, and sucrase were enhanced by 9.4%, 45.9%, and 466.8%, respectively. Moreover, SQ-2–biochar was demonstrated to have a notable capacity for removing Pb²⁺ and Al³⁺. The mineralization of Pb²⁺ and Al³⁺ was achieved through the use of SQ-2–biochar, as revealed by SEM-EDS, XRD, XPS, and FT-IR analyses, with the main precipitates being Pb₃(PO₄)₂ and AlPO₄. Functional groups such as C-O-C, C=O, N-H, P-O, and -O-H on the microbial surface were found to be involved in the biosorption process of Pb²⁺ and Al³⁺. In summary, SQ-2–biochar can effectively mineralize Pb²⁺ and Al³⁺, enhance the physiological properties of rice, and improve soil nutrients, thereby augmenting the antioxidant capacity, photosynthesis, and stress resistance of rice and ultimately promoting rice growth. Full article

Pharmaceuticals such as diclofenac (DCF), a widely used anti-inflammatory drug, are frequently detected in water bodies and pose serious environmental and health risks due to their persistence and low biodegradability. Although ozonation is an effective method for pollutant removal, its efficiency is often limited by low ozone utilization and incomplete mineralization. In this work, CuO/Al₂O₃- and MnO₂/Al₂O₃-supported catalysts were prepared via an impregnation method and evaluated for their performance in catalytic ozonation of diclofenac (DCF) in an aqueous solution. The catalysts were characterized by TEM, N₂ adsorption–desorption, FTIR, and XPS analyses. The effects of catalyst type, dosage, initial pH, and ozone flow rate on degradation efficiency were systematically investigated. Under optimal conditions, the DCF removal efficiencies reached 73.99% and 76.33% using CuO/Al₂O₃ and MnO₂/Al₂O₃, respectively, while COD removal efficiencies were 77.6% and 89.3%. Quenching experiments indicated that hydroxyl radicals (•OH) were the predominant reactive species involved in the catalytic ozonation process. The results demonstrate that supported CuO and MnO₂ catalysts can effectively enhance diclofenac degradation by ozone, offering potential for advanced water treatment applications. Full article

A Cl-rich annitic mica is present in zones in taxitic gabbro–dolerite enriched in base metal sulfides in the eastern portion of the Oktyabrsky deposit in the Norilsk complex (Russia). Other Cl-enriched minerals in the assemblage include hastingsite (4.06 wt.% Cl), ferro-hornblende (2.53 wt.%), and chlorapatite (>6 wt.%). New wavelength-dispersive electron probe analyses reveal compositions with up to 7.75 wt.% Cl, corresponding to the formula K_0.742Na_0.047Ca_0.007)_Σ0.796 (Fe²⁺_2.901Mg_0.078Mn_0.047Ti_0.007Cr_0.003)_Σ3.036 (Si_3.190Al_0.782)_Σ3.972O₁₀ (Cl_1.105OH_0.854F_0.041)_Σ2.000 based on 22 negative charges per formula unit, in which OH(calc.) = 2 − (Cl + F). Unfortunately, the grain size of the Cl-dominant mica precluded a single-crystal X-ray diffraction study even though its EBSD pattern confirms its identity as a member of the Mica group. We present results of a refinement of a crystal from the same mineralized sample containing 0.90(6) apfu Cl [R1 = 7.89% for 3720 unique reflections]. The mica is monoclinic, space group C2/m, a 5.3991(4), b 9.3586(6), c 10.2421(10) Å, β 100.873(9)°, V = 508.22(7) ų, Z = 2. We also describe physical properties and provide a Raman spectrum. Among the mica compositions acquired from the same sample, a high Cl content is correlated with relative enrichment in Si, Mn, and Na and with a depletion in Al, Mg (low Mg#), K, Cr, and Ti. The buildup in Cl in the ore-forming environment is ultimately due to efficient fractional crystallization of the basic magma, with possible contributions from the Devonian metasedimentary sequences that it intruded. Full article

In recent years, domestic research on the ion substitution behavior and chromaticity of the mineral composition of “Ya’an Green” remains insufficient, while there is almost no relevant research on “Ya’an Green” abroad. In this study, X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), infrared spectroscopy (IR), ultraviolet–visible spectroscopy (UV-Vis), and colorimetry were employed. The results indicate that the green and yellow matrices of “Ya’an Green” are primarily composed of muscovite, with rutile also present in the yellow matrix. In contrast, the white–green samples are mainly composed of quartz, with muscovite as a secondary mineral. Additionally, it was observed that the (004) crystal plane of muscovite exhibits a peak shift to lower 2θ angles, attributed to the substitution of Al³⁺ by ions with larger radii, such as Ba²⁺, Cr³⁺, and Fe²⁺, leading to an increase in unit cell parameters and a consequent shift in the peak to lower wavenumbers. The main elements of “Ya’an Green” are Al, Si, and K, with minor elements including Na, Fe, and Cr. Furthermore, Mg²⁺, Ca²⁺, Ti⁴⁺, Cr³⁺, and Fe²⁺ in the samples can substitute for Al³⁺ through isomorphic substitution. The infrared spectrum of muscovite in the ‘Ya’an Green’ sample shows three typical absorption peaks, 422 cm⁻¹ and 513 cm⁻¹ caused by Si-O bending vibration, 697 cm⁻¹ and 837 cm⁻¹ caused by Si-O-Al vibration, 948 cm⁻¹ caused by O-H bending vibration, and 3647 cm⁻¹ caused by O-H stretching vibration. The peak at 837 cm⁻¹ exhibits varying degrees of shift due to the substitution of Al³⁺ by ions with larger radii. The ultraviolet–visible spectra display two broad absorption bands at 422 nm and 615 nm, which are caused by Cr³⁺ transition, indicating that Cr is the chromogenic element responsible for the green color. A correlation was observed between the Cr³⁺ content and the hue angle h in “Ya’an Green” samples: the higher the Cr³⁺ content, the closer the hue angle is to 136^°, resulting in a darker green color, while lower Cr³⁺ content leads to a deviation from the dark green hue. This study establishes for the first time the correlation between the mineral composition of ‘Ya’an Green’ and its chromatic parameters and explores the linear relationship between its color and the number of color-causing elements and elemental substitution, which provide data support and theoretical models for the study of the color of seal stones. Full article

Typical greisen-type ore samples from northeastern Tasmania were investigated for their critical metal potential. The samples contain zinnwaldite (KLiFe²⁺Al(AlSi₃O₁₀)(F,OH)₂), a lithium-bearing mica that is prone to excessive breakage during conventional processing, leading to the generation of very-fine-sized particles (i.e., slimes, <20 µm), eventually ending up in tailings and resulting in lithium (Li) loss. To assess whether the natural grain size of valuable minerals could be preserved, the samples were processed using electric pulse fragmentation (EPF). The results indicate that EPF preferentially fragmented along mica-rich veins, maintaining coarse grain sizes, although a lower degree of liberation was observed in fine-grained, massive samples. In addition, the critical metal distribution within zinnwaldite was examined using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) techniques. The results reveal differences in Li content between groundmass zinnwaldite and vein-hosted zinnwaldite and that the zinnwaldite contains the critical elements rubidium (Rb), cesium (Cs), and rare earth elements (REEs: La, Ce, Pr, and Nd). Vein-hosted zinnwaldite has a higher average Li content, whereas groundmass mica contains higher concentrations of Rb, Cs, and REEs. Both mica types host inclusions of bismuth–copper–thorium–arsenic (Bi-Cu-Th-As), which are more abundant in vein-hosted mica. In some of the samples, Bi, Cu, Th, and REEs also occur along the mica cleavage planes, as well as in mineral inclusions. The Li, Rb, and Cs grades are comparable to those of European deposits, such as Cínovec and the Zinnwald Lithium Project. Full article

This study utilizes the temperature–pressure reactor to simulate the real conditions of the reservoir to study rock dissolution and scale formation caused by strong and weak alkali during the ASP flooding in an oilfield in China. Mercury injection experiments showed that the porosity and permeability of rock increased by 10.3% and 15.3% under the action of strong alkali, while they increased by 7.2% and 10.1% under the action of weak alkali, indicating that both strong and weak alkali can cause rock dissolution. The structural morphology of the rock demonstrated that the clay content between the grains decreased significantly. The semi-quantitative analysis of XRD indicated that the content of kaolinite decreased from the initial 7% to 0%. The recrystallized carbonate was found, and the carbonate content increased from the initial 0% to 12%. According to the SEM, EDS, and Raman analyses of the scale, the scale formation was complex in the strong alkaline system, including silicate scale, carbonate scale, and hydroxide scale. In contrast, only carbonate scale was found in the weak alkaline system. The ICP-AES test for the liquid system revealed that the rock dissolution releases substantial Ca²⁺, Mg²⁺, Fe²⁺, SiO₃²⁻ and AlO₂⁻ ions, among which Si concentration can reach around 560 ppm. The chemical mechanism of rock dissolution and scale formation by strong and weak alkali includes the exchange of mineral cations by Na⁺ and the destruction of Si-O and Al-O bonds by OH⁻. These released ions migrate with the composite fluid, then recrystallize under the saturation state to form the scale. The dissolution of rock by strong alkali is more intense, while the dissolution of weak alkali is relatively mild. Moreover, the scale type in the weak alkaline system is simpler, which would be convenient to develop inhibitors. Full article

Taranakite is a mineral consisting of a hydrated layered aluminum phosphate, with the formula K₃Al₅(PO₃OH)₆(PO₄)₂·18H₂O; its structure belongs to the R-3C group. If the mineral grows in an environment rich in bat and bird guano, the high nitrogen guano content induces the intercalation of NH₄⁺ into the structure, replacing the potassium ion. The thermal decomposition of guano-derived taranakite releases water and ammonia. The aim of this work is to confirm the presence of ammonium in the guano-derived taranakite. Thermogravimetric analysis (TGA) was performed on taranakite collected in Pollera Cave (Liguria), and the gases evolved during its decomposition were analyzed by Fourier-transform infrared (FT-IR) spectroscopy. All the samples were characterized before and after thermal analysis by means of powder X-ray diffractometry (PXRD) and scanning electron microscopy (SEM). The release of crystallization water occurs at a temperature below 200 °C; further ammonia can be detected above 200 °C. Full article

A gold mine located in western China is facing the problem of a low concentrate grade, significantly hindering its economic benefits. Preliminary assessments indicate that this is caused by gangue minerals that are prone to floating and sliming, necessitating suppression in the flotation process. The effect of fenugreek polysaccharide gum (FGM) upon the flotation separation of arsenopyrite (representative of Au-bearing minerals) and pyrophyllite (a typical gangue mineral) was investigated; its industrial potential was verified through actual ore flotation and pilot plant testing. Additionally, the selective inhibition mechanism of FGM on pyrophyllite was elucidated. The flotation tests of pure minerals indicated that pyrophyllite has a high natural floatability; thus, it cannot be separated from arsenopyrite at low alkaline pH (7–9); smaller pyrophyllite particle sizes, especially −0.038 mm fractions, significantly decreased the arsenopyrite recovery; FGM can eliminate this adverse effect to a large extent through its selective depression of the flotation of pyrophyllite. For real ore systems, FGM also exhibited superior performance compared with the commonly used silicate and SHMP; closed-circuit flotation tests showed that the gold grade of the concentrate increased by 3.90 g/t and the enrichment ratio increased by 2.53 with the addition of FGM. As of now, FGM has increased the profits by USD 1.715 M in the past two years by improving concentrate grade and recovery efficiency. According to the results of contact angle, zeta potential, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), the selective adsorption of FGM onto the pyrophyllite surface was the reason for the positive effect; the interaction primarily involved the Al sites on the pyrophyllite surface and the –OH on FGM molecules. Full article

Boehmite is an aluminum oxyhydroxide (AlO(OH)) and one of bauxite’s main mineral phases. This mineral is highly valued as an important source of aluminum for the metallurgical industry. However, the formation of synthetic boehmite has been observed in water treatment when aluminum anodes are used for electrocoagulation. This boehmite occurs in flocs that capture impurities from the water, but removing these flocs is a slow process. Therefore, the froth-flotation method was employed in the present study to float synthetic boehmite. This was achieved by evaluating the particle size of synthetic boehmite, generating microbubbles, and using an anionic collector system in a novel experimental setup. The results show that the surfactants sodium dodecyl sulfate (SDS) and potassium oleate (PO) favor the recovery of synthetic boehmite in different particle sizes, with the particle size favored related to the bubble size generated. It was noted that increasing the SDS concentration enabled the microbubbles to recover up to 95% of boehmite particles with diameters of less than 30 microns. Full article

Spodumene (LiAlSi₂O₆) is a member of pyroxene-group minerals. It has the highest theoretical lithium abundance among all of the Li-bearing minerals. In the present work, in situ high-pressure Raman spectroscopic investigation of natural spodumene have been conducted up to 19.04 GPa. Unheated spodumene and spodumene recovered after heat treatments (up to 1000 °C) have also been analyzed by X-ray diffraction and infrared spectroscopy. The results indicate that spodumene, after the displacive C2/c–P2₁/c transformation triggered at ~3.2 GPa, remains stable at pressures up to 19 GPa at ambient temperature without undergoing decomposition, amorphization, or a second phase transition. The major OH bands of the spodumene samples are observed within the wavenumber range of 2580–3220 cm⁻¹, implying a strong hydrogen bond interaction. The water content of the spodumene is estimated to be 19–97 ppm wt. H₂O based on the integrated absorption area of the OH bands. The FTIR analysis of the spodumene samples recovered after heat treatments implies that spodumene can retain a significant amount of water (up to ~100 ppm H₂O by weight) under high-temperature conditions up to 1000 °C. This suggests that spodumene in subducted slabs is unlikely to undergo dehydration at temperatures below 1000 °C, and is therefore not expected to trigger partial melting. Thus, spodumene may serve as a key carrier for Li, transporting it into the deep mantle without releasing Li into melts during subduction. Full article

We herein present a comprehensive investigation of the eudialyte group minerals from the nepheline syenites of Rouma Island in the Los Archipelago, Conakry region, Guinea. Two distinct mineral phases were identified: an oneillite-like phase, associated with the agpaitic rock suite, and, for the first time in this locality, kentbrooksite, occurring in pegmatites. The oneillite-like phase crystallizes in the trigonal system (space group R3), with unit cell parameters a = 14.1489(2) Å, c = 30.1283(5) Å and an idealized crystal chemical formula of Na₁₅(Mn,REE)₃(Ca,Mn)₃(Fe,Mn)₃Zr₃(Zr,Si,Al,Nb,Ti)₁ (Si₂₅O₇₃)(O,OH,H₂O)₃(OH,Cl,F)₂. Kentbrooksite also exhibits trigonal symmetry (space group R3m), with unit cell parameters a = 14.2037(3) Å c = 30.1507(9) Å and an idealized formula of (Na,REE)₁₅(Ca,Mn)₆(Mn,Fe)₃Zr₃(Nb,Si)₁(Si₂₅O₇₃)(O,OH,H₂O)₃(F,Cl,OH)₂. Compared to the oneillite-like phase, kentbrooksite is markedly enriched in Mn and rare earth elements (REE). This geochemical distinction aligns with the progressive mineralogical evolution of the system, transitioning from the miaskitic to agpaitic suite (oneillite-like phase) and subsequently to pegmatites (kentbrooksite). These findings are consistent with the broader-scale observations regarding the syenite ring structure of the Los Archipelago. Full article