Mineralogical Analyses Research Articles

Evaluation of long-term properties and life cycle assessment of alkali-activated concrete with varying fiber inclusions

The potential for using alkali-activated concrete (AAC) as a sustainable substitute for Portland cement (PC) concrete is a topic of ongoing research interest. The uncertainties in the raw material composition, the reportedly low tensile strength of AAC, and the lack of relevant standard codes of practice further inhibit wider industrial usage of AACs. Fiber inclusions reportedly enhance the tensile properties of traditional PC concrete. However, there is no long-term data available for fiber-reinforced alkali-activated concrete (FRAAC) mixtures. Hence, the present study is aimed at investigating the long-term mechanical properties of ambient-cured FRAAC with GGBS as the sole precursor. Four different types of fibers, viz., steel (SF), polyvinyl alcohol (PVAF), polypropylene (PPF) and glass (GF) are used in this research as reinforcements in AAC. Tests for compressive strength (fc′), splitting tensile strength (fsp) and flexural strength (fr) are conducted for FRAAC containing varying fiber contents of 0.1–0.3%. The findings demonstrated that fiber additions do not have any noticeable influence on the compressive strength of AAC. However, relative to the plain mix, the fsp and fr of FRAACs were enhanced by up to 32% and 29%, respectively. The formation of the hardened calcium aluminosilicate matrix and evolution of the fiber-matrix bonding over time was evident from the scanning electron microscopy (SEM) images. The related molecular bonds over a period of 7-d to 360-d was identified through mineralogical and chemical analyses. Furthermore, to validate its environmental sustainability, life cycle assessments were conducted. The AACs exhibited at least 43% lesser impacts than PC concrete on the ecosystem. FRAACs had only slightly higher (≤ 7% increase across all fiber types) impacts than plain AAC.

Alteration in the Raman spectra of characteristic rock‐forming silicate mixtures due to micrometeorite bombardment

AbstractInnovative techniques are required for the in situ investigation of the surfaces of planetary bodies when landings are planned. Raman spectroscopy turned out as an excellent tool for fast mineralogical analyses on space missions. Contribution from a photoluminescence signal is not unexpected and is likely to be even more pronounced on celestial surfaces with a dilute or absent atmosphere exposed to strong space weathering, for example, micrometeorite bombardment. Such signals were found, for example, in Raman analysis of the probes from sample‐return missions. While photoluminescence is generally considered as an accompanying undesired product in the Raman spectral measurement, our studies show that some analytical information can be derived from this signal, and even more, due to the specific correlation of luminescence intensity with space weathering products. Therefore, we investigate the Raman spectra alteration of characteristic rock‐forming mineral mixtures (olivine, pyroxene and plagioclase) by micrometeorite bombardment, which is simulated by nanosecond‐pulse laser irradiation. The changes in the minerals are strongly dependent on the composition and structure. They range from disappearing changes in the minerals with simple chemistry and structure to complete amorphization of minerals with relatively low melting enthalpy. With Raman spectroscopy, we found out that the photoluminescence signals show resonant or anti‐resonant changes to specific mineral phases and amorphization. Furthermore, ablation‐induced iron nanoparticles of minerals containing Fe are detectable by Raman spectroscopy due to their alteration into iron oxides. Trapped volatiles in the matrices are analysed due to the formation of the compounds containing them. This broad spectrum of results indicating specific change phenomena due to space weathering can be effectively used for in situ Raman analysis in planetary missions.

Study about the rehydration of phosphogypsum hemihydrate in tropical soil mixtures

ABSTRACT The objective of this paper is to verify the occurrence of phosphogypsum hemihydrate (PG-HH) rehydration and its influence on the mechanical behaviour in tropical soil mixtures. The studies were carried out in mixtures with lateritic clay, PG and Portland cement. Were carried out microstructural and mineralogical analyses with scanning electron microscopy and X-ray diffraction experiments, compaction tests at different setting times and unconfined compressive strength tests on saturated samples subjected to weathering. This study showed that PG-HH can rehydrate when it is in contact with water. This fact changes its crystals’ shape and impacts the mechanical behaviour of tropical soil mixtures. Saturated samples exposed to weathering presented strength reduction. However, the strength of mixtures with PG-HH, even when rehydrated, is superior to the strength of mixtures with PG-DH. The incorporation of PG-HH in mixtures with tropical soil and cement in geotechnical works is possible despite its rehydration.

Bloomery iron production in the Holy Cross Mountains (Poland) area during the Roman period: conditions during the metallurgical process and their uniformity between locations

The study assessed the uniformity of the metallurgical process carried out during the period of Roman influence in Poland. The age of the investigated material was confirmed based on an analysis of the 12C/14C isotope ratio in the charcoal found in slag. The comparison was based on four Holy Cross Mountains (Poland) locations. The evaluation included smelting temperature, viscosity of the metallurgical melt, oxidation–reduction conditions, and slag cooling rate determined based on geochemical (XRF) and mineralogical (XRD, SEM, EPMA) analyses. Despite the distance between individual sampling sites, the conditions in which smelting was carried out were similar for all samples. The liquidus temperature of the analyzed slags was in the range of 1150–1200 °C. Oxidation–reduction conditions were determined through thermodynamic calculations using SLAG software. In the temperature range of 1150–1200 °C, the oxygen fugacity had to be below logP O2 = − 13.20 to − 12.53 atm to reduce iron oxides to metallic iron. The viscosity of the metallurgical melt was calculated and ranged from 0.15 to 1.02 Pa s, indicating a low viscosity. The slag cooling rate determined based on olivine morphology was in the range of > 5 to 300 °C/h. Smelting parameters were compared with other locations in Poland, and similar results were obtained for slags from Masovia and Tarchlice. In the case of one site (Opole), despite the higher maximum value of liquidus temperature, it was indicated that the process could have taken place in similar conditions, and the differences resulted from contamination of the slag with material from the furnace/pit walls.

Investigating the Characterization and Grindability Behaviour of Farin-lamba Cassiterite toward Effective Tin Oxide Production

Cassiterite has been an essential source of tin; its exploration and exploitation have become a priority worldwide. The effective beneficiation of cassiterite depends mainly on its grindability and effective liberation. The Modified Bond's grindability test is a method used to determine the work index, which is crucial in estimating the energy needed to grind an ore. This is crucial during mineral processing, as a slight deviation would affect the company's operating expenditure (OPEX). This study investigates the work index for Farin-Lamba cassiterite with reference to silica sand sourced from Igbokoda. The test ore (cassiterite) was analyzed using Energy Dispersed X-ray fluorescence spectrometer (ED-XRS), Petrographic Analysis, and Scanning Electron Microscope equipped with an Energy Dispersive Spectrum (SEM-EDS) to understand their chemical and mineralogical characteristics in relation to their grindability. The test ore and the reference material (silica sand) underwent comminution using 500g of each to a 100% passing 500 μm array of sieves arranged in (√2) series from 500μm to 63μm onto an automatic sieve shaker. The chemical and mineralogical analysis revealed the presence of gangue such as SiO2 and Al2O3, which increases the energy needed during communition; further, the presence of rough and large grain size in the ore also increases the energy needed for communition. The results were subjected to Gaudin Schuman's equation to determine the ore's work index, which was 14.664 KWh/ton for the test ore, which is standard for cassiterite, which ranges from 10-15 kWh/ton. Further, the energy needed for comminution was calculated to be 33.7272 Kwh, providing valuable insights into the energy efficiency of the grinding process. The evaluation of the grindability of Farin-Lamba cassiterite in relation to the reference ore not only contributes toward understanding the ore processing dynamics but also provides information needed for the optimization of energy consumed during the process of tin oxide production.

THE STUDYOF INSULATING PROPERTIES OF REFRACTORY BRICKS PRODUCED USING MELON SEED HUSKSAS POREFORMER

This study investigated the physical, mechanical and thermal characteristics of insulating refractory bricks produced from Nigerian clay blended with melon seed husk. The aim is to reduce the cost of production which arises from importation. This is due to lack of high-quality domestic insulating refractory bricks in most high temperature industries in Nigeria. The test samples were produced by mixing clay and melon seed husk having grain sizes of 212 - 300 μm. The samples were oven dried and fired at temperatures 950℃ to 1150℃ at 50℃ intervals. Physical, mechanical, thermal tests, chemical compositions, Mineralogical and Microstructural analysis were conducted. The results showed that, clay with 25 and 30 wt.% melon seed husks possessed the required refractory properties with cold crushing strength above the recommended ASTM Standard of 1000 kN/m2.

Unusual hard metal lung disease: bronchiolocentric interstitial pneumonia.

A 38-year-old woman experienced a persistent dry cough and progressively worsening dyspnoea for 2 years. Spirometry testing revealed a moderate-to-severe restrictive abnormality. High-resolution chest computed tomography showed diffuse reticulonodular opacities. A lung biopsy disclosed alveolar parenchymal inflammation and fibrosis with bronchiolocentric features, prompting consideration of interstitial pneumonia. Following a thorough investigation of her occupational history and an on-site inspection, it was discovered that the patient had been grinding drill bits designed for printed circuit boards for 8 years, exposing her to hard metals. Mineralogical analyses confirmed excessive tungsten in urine, serum and hair, leading to a diagnosis of hard metal lung disease due to tungsten carbide-cobalt exposure. After discontinuing exposure and commencing corticosteroid therapy, her symptoms, pulmonary function and imaging showed modest improvement. This case highlights the significance of assessing occupational history in patients with interstitial pneumonia and understanding industrial hazards for accurate diagnosis and care.

Diagenetic iron-oxyhydroxides formed in suboxic to anoxic mine-impacted lake sediments near Sudbury, Ontario

Iron-oxyhydroxides are common in lake sediments, typically forming in oxidizing conditions near the sediment-water interface. However, in the mine-tailings-impacted sediment delta at Long Lake near Sudbury, Ontario, diagenetic Fe-oxyhydroxides are formed in suboxic-anoxic conditions. Geochemical and mineralogical techniques were applied to investigate the diagenetic transformations of tailings-derived oxidation products following burial in the sediment delta. Two sets of vertical cores were collected, one from a shallow-water location in the sediment delta near the lake shore and the other from a deeper-water location, approximately 90 m north from the mouth of the active channel. One core from each location was sectioned in the field into 0.1 m intervals using an anaerobic globe bag and porewater was extracted for aqueous geochemical analysis. The second core from each location was dried anaerobically and sub-sampled for solid-phase geochemical and mineralogical analyses. The aqueous concentrations of As, Fe, and SO4 are elevated near the sediment-water interface at both locations but at the shallow location they decline to the lowest observed concentrations at depth in the natural sediment. The decline in their concentrations may be enhanced by bacterial SO4 reduction and precipitation of Fe- and As-sulfides which were observed in mineralogical analysis. The mine-impacted sediment consists of numerous fragments of tailings-derived ferric-arsenate-cemented crusts. Compared to the cemented crusts that occur in the tailings, these fragments exhibit partial-dissolution features and SEM-EDS analyses demonstrate that they have relatively low As/Fe ratios suggesting the occurrence of selective As(V) dissolution during diagenesis. Diagenetic Fe-oxyhydroxides occur throughout the mine-impacted sediment, including zones that contain diagenetic Fe- and As-sulfides, suggesting they may have formed in suboxic-anoxic conditions. They occur proximal to, but separate from, the fragments of tailings-derived crusts and display diverse morphologies, including what may be a previously unreported spherulitic form. Individual Fe-oxyhydroxides range in size from nm to μm but they mostly occur in delicate clusters suggesting they are autochthonous. Compared to the cemented crusts from the tailings, they contain very small amounts of As. Analysis of one spherule indicates it contains lepidocrocite microcrystals with amorphous SiO2.nH2O in the interstitial spaces. The microcrystals contain a mixture of Fe(III) and Fe(II), with Fe(III)/ΣFe = approximately 0.8. We interpret them to have formed by burst nucleation from Fe(III)-supersaturated solution, with subsequent aggregation of crystallites to form spherules.

Preparation and evaluation of GCD-1 lunar regolith simulant based geopolymer activated by solid sodium silicate

In this study, a new lunar regolith simulant, named "GCD-1", was formulated by combining various minerals, such as anorthite, albite, pyroxene, ilmenite, slag, and fly ash. Through X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) analysis, it was verified that the main mineral composition of GCD-1 was basically the same as that of the lunar soil at the Apollo 14 landing site, in which the deviation in the main compound (i.e., SiO2 and Al2O3) was within 0.5%. Furthermore, GCD-1 based geopolymer was prepared by the one-part method, which was a mixture of solid GCD-1 precursor, solid sodium silicate (SS) activator, and water. The average daytime temperature at the lunar equator, which was calculated to be 60°C, was set as the curing temperature for the GCD-1 based geopolymer. The strength development of the GCD-1 based geopolymer was then characterized by unconfined compressive strength (UCS) for 3, 7, and 12 curing days to consider the effectiveness of the factors (solid SS to lunar regolith simulant [S/L] and water to binder ratio [W/B]). The micro-analysis tests including scanning electron microscope-energy dispersive spectrometer (SEM-EDS), mercury intrusion porosimetry (MIP), and brunner-emmet-teller (BET), were further conducted to investigate the microstructural development of the GCD-1 based geopolymer. Results showed that the increase of the W/B ratio in the GCD-1 based geopolymer tended to increase the total porosity of the sample, thereby inducing a lower UCS. At the same time, for a fixed W/B ratio, the higher S/L ratio had a certain inhibition effect on the hydration reaction, which caused the reduction in the UCS of the sample. The highest UCS of the GCD-1 based geopolymer reaching 30.54MPa, was achieved under the simulated lunar equatorial daytime temperature for 12 days with W/B and S/L ratios set at 0.25 and 0.18, respectively. Microstructure and mineralogy analyses indicated that the hydrated sodium aluminosilicate (N-A-S-H) gels contributed to reducing the sample's porosity, thereby enhancing the UCS. The relationship between the UCS and total porosity of GCD-1 based geopolymer was then derived. The results of the current study are crucial for lunar base construction with in-situ resources.

Review of: Mineralogical Analysis Applied to Forensics

Review of: Mineralogical Analysis Applied to Forensics: A Guidance on Mineralogical Techniques and Their Application to the Forensic Field, edited by Mariano Mercurio, Alessio Langella, Rosa Maria Di Maggio, and Piergiulio Cappelletti REFERENCE: Mariano Mercurio, Alessio Langella, Rosa Maria Di Maggio, and Piergiulio Cappelletti. Mineralogical Analysis Applied to Forensics: A Guidance on Mineralogical Techniques and Their Application to the Forensic Field. Springer Nature, 2022; 311 pp.

Study on Mechanisms for Improving Quality and Whiteness of Phosphogypsum Based on Process Mineralogy Analysis

Because of its low whiteness, complex composition, radioactivity and high impurity percentage, the usage of phosphogypsum (PG) resources is limited. A theoretical foundation for upgrading and bleaching PG can be obtained by researching the presence and status of impurities in the material and its symbiotic connection with gypsum. This paper makes use of an automatic mineral phase analyzer, optical microscope, XRF, XRD and SEM-EDS. After analyzing the chemical makeup of PG, phase composition and particle size composition, the distribution law and symbiotic interaction between impurities and gypsum in various particle sizes were discovered. Using a flotation test, the process mineralogy analysis results were confirmed. According to the XRF and XRD study results, the primary impurity elements in PG are Si, P and F. Si is more abundant in PG that is between +850 μm and −37.5 μm in size. The concentrations of gypsum and quartz in PG are 82.59% and 8.73%, respectively, according to the results of XRD and process mineralogy. The monomer dissociation degree of the gypsum mineral phase is as high as 90.47%. Gibbsite and pyrite are the primary causes of the low whiteness of PG and are clearly related to the quartz mineral phase. The coupling process of “flotation + pickling” produced purified PG with a purity of 95.35%, whiteness of 70.76% and SiO2 content of 2.73%. The quality met the first-class index standards of PG in GB/T23456-2018.

Microfacies and mineralogical analyses of the late cretaceous carbonate rocks from The Central Benue Trough, Nigeria

The Cretaceous limestone facies from Yandev section in the central Benue Trough, Nigeria constitutes parts of the potential reservoirs  and sources rocks for petroleum prospects in the basin. The central Benue Trough is the least studied basin among its contemporaries  due to lack of subsurface data. Detailed mineralogical, facies analysis and diagenesis of these carbonate rocks in the basin have not  received significant study. The aim of this study was to employed multifaceted methodology such as sedimentological, facies analysis  petrographic and geochemical approaches which was lacking in previous research in the trough. The sedimentological analysis was done  to evaluate fabrics grain sizes, and lithology types. For petrographic analysis, thin sections were prepared and examined under a  petrographic microscope and categorized according to Dunham's classification. Geochemical analysis involved X-ray fluorescence (XRF),  X-ray diffraction (XRD), and scanning electron microscope - energy dispersive X-ray spectroscopy (SEM-EDX) techniques to unveil  mineralogical, oxide, and elemental compositions. The sedimentological results revealed light to dark grey medium to fine-grained limestone facies with intercalation of dark grey shales and siltstones. The XRD mineralogy data, revealed calcite (60.00 - 64.10%), quartz  (14.30 - 51.00%), albite (12.30 - 19.00%), and chlorite (6.30 - 8.10%). Microfacies results revealed distinct sandy bioclastic wackstone and  sparitic intraclastic packstone, as well as micritic intraclastic wackestone and sparitic bioclastic packstone. SEM images highlighted the  intricate composition, including elongated structures, whites and dark spots suggesting varying conditions of deposition. Elemental  analysis through EDX emphasized significant proportions of carbon, oxygen, sodium, potassium, calcium, silicon, aluminum, iron, and  magnesium. Based on sedimentological, biofacies, lithofacies and geochemical evidence we infer that the carbonate sediments were  mainly deposited in a shallow marine depositional environment (inner to outer neritic).

Recovery of Apatite from Magnetic Concentration Tailings by Flotation

Iron concentration tailings contain many valuable minerals, including apatite, which is not currently being recovered despite its use to make fertilizers and chemicals. This article proposes a flotation circuit to recover apatite from tailings generated by mining in Chile, based on laboratory tests and using the “Split Factor” method. The iron tailings were characterized by granulometry, chemical and mineralogical analyses, zeta potential, and contact angle. The effect of the collector, frother, and dispersant dose, along with the number of flotation stages, on both the grade and recovery of P2O5 were studied. The results indicate that it is possible to produce concentrates with a P2O5 grade of 29.1% and 89.6% recovery in a flotation circuit that includes the rougher–scavenger–cleaner stages. To obtain these results, it is only necessary to condition the iron tailings with 400 gt−1 of Atrac-2600, 400 gt−1 of sodium silicate, 10 min of conditioning time, pH adjustment to 10, and a time for the rougher, cleaner, and scavenger stages set at 10, 7.6, and 6.8 min, respectively. A chemical interaction is suggested, where the collector is specifically adsorbed onto the apatite surface.

Occurrence and mobility of thiolated arsenic in legacy mine tailings

We studied the occurrence of dissolved thiolated Arsenic (As) in legacy tailings systems in Ontario and Nova Scotia, Canada, and used aqueous and mineralogical speciation analyses to assess its governing geochemical controls. Surface-accessible and inundated tailings in Cobalt, Ontario, contained ∼1 wt-% As mainly hosted in secondary arsenate minerals (erythrite, yukonite, and others) and traces of primary sulfide minerals (cobaltite, gersdorffite and others). Significant fractions of thiolated As (up to 5.9 % of total dissolved As) were detected in aqueous porewater and surface water samples from these sites, comprising mostly monothioarsenate, and smaller amounts of di- and tri-thioarsenates as well as methylated thioarsenates. Tailings at the Goldenville and Montague sites in Nova Scotia contained less (<0.5 wt-%) As, hosted mostly in arsenopyrite and As-bearing pyrite, than the Cobalt sites, but exhibited higher proportions of dissolved thiolated As (up to 17.3 % of total dissolved As, mostly mono- and di-thioarsenate and traces of tri-thioarsenate). Dissolved thiolated As was most abundant in sub-oxic porewaters and inundated tailings samples across the studied sites, and its concentrations were strongly related to the prevailing redox conditions and porewater hydrochemistry, and to a lesser extent, the As-bearing mineralogy. Our novel results demonstrate that thiolated As species play an important role in the cycling of As in mine waste systems and surrounding environments, and should be considered in mine waste management strategies for high-As sites.

Effect of illite on the mechanical properties of subgrade soil under varying surcharge loads

Due to its non-expanding properties, presence of Illite mineral in subgrade soil is investigated particularly on California bearing ratio (CBR), resilient modulus (MR) and swell potential. Multiple samples of stiff and weak subgrade soils with varying illite percentages were tested under six different surcharge loads ranging from 2.27 to 13.8 kg. Mineralogical analysis is performed using X-ray diffractometer and MR of soil is assessed using Ultrasonic pulse velocity (UPV) technique. Results showed a positive correlation between Illite percentage and both CBR and MR value. The soil with higher Illite content tends to exhibit higher CBR and MR values while those with higher montmorillonite content show lower values even with more Illite content. The CBR and MR values increases from 8.4% to 19 % and 139 MPa–315 MPa for stiff soil and 3.8%–11.7 % and 23 MPa–83 MPa for weak soil, respectively when the surcharge load was increase from to 2.27–13.8 kg. Additionally, a decrease in swell potential was observed from 1.64% to 1.09 % for stiff soil and 1.39%–0.84 % for weak soil with an increase in Illite percentage. The study also developed an improved relationship for predicting resilient modulus based on CBR value, showing a strong correlation with equations developed by many researchers in the past.

Exploring pottery origin by composition and technique comparison: a case study at the Daqu burial site, Beijing, China

Scientific analysis of excavated pottery reveals critical archaeological insights, yet data on Han Dynasty pottery remains limited. This study focuses on pottery artifacts excavated from the Daqu burial site in Beijing, renowned for their polychrome decorations and size. Utilizing optical microscopy (OM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray Fluorescence (XRF), this study examined five substrate samples sourced from fragments of pottery towers and ellipse-shaped dishes. All samples exhibited similar inclusions and the same firing atmosphere. The mineralogical analysis indicated that quartz and feldspar are predominant components, with minor constituents like chlorite and kaolinite observed in the coarse pottery of the ellipse-shaped dish. Minor mineral variations suggest differences in firing temperatures. The resemblance between low-value pottery cups and delicate polychrome towers suggests they were crafted locally. These findings advance our understanding of ceramic materials and techniques in late Eastern Han Dynasty Beijing, providing crucial insights for future studies on ancient Chinese economy and society.

Understanding arsenic behavior in alluvial aquifers: Evidence from sediment geochemistry, solute chemistry and environmental isotopes

The hydro-geochemistry and isotopic variations in groundwater, coupled with sediment geochemistry, were investigated in the Middle Gangetic Plain, India, to better understand the aquifer dynamics that influence the arsenic (As) evolution and mobilization. Eighty-four groundwater samples, thirteen River water samples, and two sediment cores (33 mbgl) were studied. The samples were analyzed for major ions and trace metals, including As and stable isotopic variability (δ2H, δ18O, and δ13C). The study area was categorized into older and younger alluvium based on existing geomorphological differences. Younger alluvium exhibits higher As enrichment in sediment and groundwater, ranging of 2.59–31.52 mg/kg and bdl to 0.62 mg/L. Groundwater samples were thermodynamically more stable with As(OH)3 species ranging from 88.5% to 91.4% and FeOOH from 69% to 81%, respectively. PHREEQC and mineralogical analysis suggested goethite and siderite act as a source and sink for As. However, statistical analysis suggested reductive dissolution as the primary mechanism for As mobilization in the study area. Spatio-temporal analysis revealed elevated concentrations of As in the central and northeastern regions of the study area. Stable isotope (δ2H and δ18O) analysis inferred active recharge conditions primarily driven by precipitation. The depleted d-excess value and enriched δ18O in the groundwater of younger alluvium indicate the effect of groundwater recharge with significant evaporation enrichment. Groundwater recharge potentially decreased the quantity of arsenic in groundwater, whereas evaporation enrichment increased it. Rainwater infiltration during recharge introduces oxygenated water into the aquifer, leading to changes in the redox conditions and facilitating biogeochemical reactions. The carbon isotope (δ13C) results suggest that high microbial activity in younger alluvium promotes As leaching from sediment into the groundwater.

Uncovering Hidden Microbial Diversity in Nitrate/Iodide Deposits (NIDs) in the Domeyko District, Atacama Desert, Chile

Unique worldwide, nitrate/iodine deposits (NIDs) are located along a 700 km geological belt in the Atacama Desert, Chile. They serve as the primary source of mineral ores for the extraction of iodine, sodium, and potassium nitrates. NIDs have been relatively underexplored from a biological perspective. To address this, we collected sixteen soil samples from abandoned mines in Oficinas Pissis and Savona for chemical, mineralogical, and metagenomic analyses. The soils primarily consisted of halite and darapskite, with only one sample being predominantly composed of thenardite. Deliquescence and water activity measurements yielded values ranging from 0.02% to 0.40% and 0.47 to 0.62, respectively. To investigate the presence, identification, relative abundance, and diversity of microbial life in NID soils, we employed MiSeq high-throughput sequencing and bioinformatic tools. The dominant phyla observed were Firmicutes and Proteobacteria, with Actinobacteria and Cyanobacteria being predominant in two soil samples. Furthermore, we detected nitrate/perchlorate-reducing bacterial activity in enriched cultures from the soil samples. This study sheds light on the resilience of microbial life in the Atacama Desert NIDs, providing compelling evidence for its existence and offering insight into factors that could facilitate it within this unique environment.

A comprehensive study of melt foaming in E‐glass batch‐to‐melt conversion process: Effects of sulfate content and chemistry of raw materials

AbstractControl of sulfate‐induced melt fining without excessive foaming is one of the critical steps in maintaining the stability of E‐glass fiber manufacturing processes. Besides, the efficiency of combustion or energy utilization is directly affected by the extent of the melt‐foaming. A fundamental understanding of key factors affecting melt foaming under the simulated oxy‐fuel combustion environment will enable commercial E‐glass fiber production to optimize both batch chemistry and operation conditions to achieve adequate furnace control. In this study, six types of E‐glass batches with the same target glass composition were prepared by using four different CaO sources; calcined limes with different SO3 contents, limestone, limestone with sodium sulfate, and a mixture of limestone and calcined lime. All batch samples were examined by HTMOS‐EGA system (high temperature melting observation system with evolved gas analysis). HTMOS enables monitoring batch‐to‐melt conversation steps by using a high‐resolution camera and EGA detects the evolved reaction gaseous, such as CO, CO2, and SO2 via an Fourier transform infrared (FTIR) gas analyzer. Gases of water vapor, N2, and O2 were introduced accordingly into the fused quartz crucible to simulate similar oxy‐fuel atmosphere of the furnace operation. This study aimed to investigate the effects of different SO3 contents in batches and different raw material chemistries on the foam formation in E‐glass melts under the oxy‐fuel atmosphere. Different raw materials were characterized by mineralogical analysis, chemical analysis, particle size distribution, chemical oxygen demanding (COD) level, and Brunauer–Emmett–Teller (BET) analysis. Although some of the batches contained the same SO3 content, different foam formations resulted from the effect of the batch chemistry. Our detailed HTMOS‐EGA investigations show that not only SO3 content in the batch affects foam formation in E‐glass melts, but also raw material chemistry and particle size have strong effects on the melt foaming in E‐glass batch melting, especially for those of ingredients having hydroxide phases and/or finer particles with higher specific areas.

Structural Characterisation of End-of-Life Cement–Asbestos Materials from Lithuania

Asbestos is a widely used name for natural silicate minerals with fibrous properties. Asbestos minerals were one of the most popular and cheapest raw materials used in the construction industry in the past when they was used in the form of cement–asbestos composite material. Nowadays, we know that asbestos possesses carcinogenic properties. Due to this fact, asbestos was banned in many countries including Lithuania. All asbestos-containing materials are considered waste and stored in special landfills, which causes significant environmental pollution. One of the methods proposed to solve the asbestos problem may be thermal treatment. In the present study, asbestos-containing wastes in the form of cement–asbestos materials were examined. These asbestos-containing materials were characterised via chemical analysis (XRF) connected with mineralogical phase analysis with powder X-ray diffraction (XRD) as well as scanning electron microscopy (SEM). The thermal decomposition of samples was studied via differential thermal analysis (DTA) and thermogravimetric measurements with evolved gas analysis (TG–EGA). It was found that thermal treatment is a possible way to destroy asbestos contained in cement–asbestos wastes and convert it into new mineral phases. The work also compared the obtained characteristics of asbestos waste with the characteristics of waste produced in other countries.