Mica Content Research Articles

Influence of Mica Content on Shear Strength, Shear Modulus, and Damping Response of Micaceous Sand

Influence of Mica Content on Shear Strength, Shear Modulus, and Damping Response of Micaceous Sand

Relative importance of Asian-dust-derived micas estimated from oxygen isotopic analysis of fine quartz on specific retention of radiocesium in Andosols in Tohoku Region, Japan

ABSTRACT Andosols are the soil type that potentially has the highest radiocesium (RCs) transfer risk due to their deficiency in micaceous minerals (micas) that can strongly retain RCs in their interlayer sites. However, an exogeneous source of micas as a component of Asian dust may have contributed largely to increase the RCs retention ability for Andosols in Tohoku Region, Japan. We investigated 29 pasture soils with andic soil properties that were collected at various places across this region to clarify the provenance of micas whether they originated from Asian dust or local lithological materials. Mica content in bulk size fraction (<2.0 mm) positively and strongly correlated with the factor related to felsic elemental composition obtained by principal component analysis (r = 0.90, p < 0.01). Fine micas in the <20 µm fraction (Mica<20 µm) accounted for a large fraction (72 ± 16%) of the total mica contents and positively correlated with the content of fine quartz derived from Asian dust (Qzad_<20 µm) (r = 0.86, p < 0.01), which were distinguished from fine quartz derived from igneous bedrock materials (Qzig_<20 µm) by using the δ18O values for quartz isolated from the <20 µm fraction. Furthermore, Mica<20 µm correlated positively with radiocesium interception potential (RIP) of this fraction. These results for the first time demonstrated the importance of Asian-dust-derived micas relative to those from another local sources on the RCs retention abilities in Andosols in Tohoku, Japan.

Preparation of WO3-Mica Hybrid Coatings with Electrochromic Properties and Pearl Luster.

Tungsten oxide-mica composites were prepared by adding different amounts of commercial mica (alumina silicate) in order to provide high luster to electrochromic coatings. The mechanical stability was sustained for up to 50 weight % mica for application in aqueous medium. The electrochemical properties, coloration, and luster were investigated. The luster of the composites increased roughly linearly with increased mica content and was retained after coloration. The addition of 10 weight % mica was found to be optimal with respect to the compromise between electrochromic coloration and pearlescent luster. This is, to the best of our knowledge, the first report on the preparation and characterization of WO3-mica inorganic composites with high luster in both bleached and colored states.

Changes in Total and Available K Contents in Feldspar and Mica Co-pyrolyzed with Poultry Litter at Different Temperatures

Plant available potassium (K) content is very low in K-bearing mineral ores present in Sri Lanka and that restrict their use in crop production as K fertilizer sources. Heating of minerals can increase their plant available forms of nutrients. The objective of this experiment was to study the effect of direct heating of K-bearing minerals at different temperatures and co-pyrolyis with poultry litter (PL) at different rates on their total and available K contents. Poultry litter was co-pyrolyzed with 0, 1 and 5% (w/w) of feldspar and mica at 350, 500, 650 and 900 ℃. K-bearing minerals were also directly heated at these temperatures. With direct heating the mineral, total K contents of feldspar (6.2%) and mica (4.5%) were significantly (p&lt;0.001) increased by 10% and 18%, respectively at 500 ℃ and then decreased by 33 and 65%, respectively at 900 ℃. Available K contents in feldspar (0.05%) and in mica (0.03%) either decreased significantly (feldspar) or did not change (mica) upon direct heating. Increasing pyrolysis temperature up to 650 ℃ increased both total (4.2 to 6.4%), and available K (3.2 to 6.1%) contents in poultry litter biochar (PLB). Co-pyrolysis of PL with feldspar or mica at 1 or 5% rates did not improve the total or available K contents in PLB at these temperatures. We concluded that heat treatment of locally available feldspar and mica or co-pyrolyzing them with PL are not effective technologies to increase their utilization in agriculture.

Study on the Effect of Interfacial Modification on the Properties of Super Standard Mica Sand Cement-Based Materials

Mica is a harmful substance in sand and occurs frequently. The application of super standard mica sand is a difficult problem in large-scale engineering. In this work, the effects of an interface modifier, mineral admixture, and a curing system on the properties of cement-based materials with super standard mica sand were studied. The strength of cement-based materials linearly decreases with the mica content in sand. When the mica content in sand exceeds 6%, the compressive strength of mortar and concrete at 28 d decreases by more than 22.3% and 33.5%, respectively. By adding the silane coupling agent (SCA) of 50% mica mass and curing in natural conditions, the compressive strength of mortar increases by 10.9%. The cement-based materials with the SCA are more suitable for curing in natural conditions, and the performance of the SCA will not be affected by adding appropriate amounts of mineral admixture. The drying shrinkage strain of the concrete, with the sand containing high mica content modified by SCA, is reduced by 10.5%, and the diffusion of chloride ions in concrete is reduced. The XRD results show that the addition of the interfacial agent does not change the hydration products. The MIP and SEM results show that the SCA can form a bridge structure between the hydration products and the mica, improve the bonding strength of the interface zone, and reduce the number of harmful pores.

Thermophysical properties and geochemical characteristics of granites in the Tengchong area: indications for resource potential of hot dry rocks

Ascertaining regional radiogeochemical characteristics and lithospheric thermal structure characteristics is paramount for identifying the resource potential of hot dry rocks. This study conducted thermal conductivity testing and whole-rock analyses of outcrop granites of different formation epochs from the Tengchong area. Moreover, combined with the previously published whole-rock data and the data related to radioactive heat production rates, this study conducted geological, geophysical and geothermal analyses. Key findings are: (1) Granites in the Tengchong area exhibit an average radioactive heat generation rate of 5.54 μ W m −3 . Among them, the Late Cretaceous granites have an average radioactive heat generation rate of 8.08 μ W m −3 , suggesting high heat production granites. (2) Granites in the Tengchong area present an average thermal conductivity of 3.135 W.m −1 K −1 , relatively akin to the average values of granitic rocks worldwide. Compared to granites of other epochs, the Late Cretaceous granites manifest significantly higher thermal conductivities, with an average of 3.28 W.m −1 K −1 . (3) There is a negative correlation between the mica content and the thermal conductivity of the granites in the Tengchong area. (4) The Tengchong area holds potential for hot dry rocks exploitation and is inferred to have a lithospheric structure characterized by hot mantle and cold crust.

Mineral chemistry evolution of magmatic Li-bearing micas and Li-loss during postmagmatic phengitization in an A-type sieno-monzogranite: A mass balance approach at La Chinchilla pluton, Sierra de Velasco, La Rioja, Argentina

La Chinchilla granite (∼3.75 km2) is an epizonal pluton intruded during the Lower Carboniferous in Sierra de Velasco, Sierras Pampeanas, northwestern Argentina. Three facies have been distinguished in the pluton (equigranular, porphyritic and fine-grained border zone facies), being equigranular and porphyritic the main two granite types, which host abundant millimeter to < 2 m sized miarolitic pegmatites and pockets of simple granitic mineralogy (quartz + albite + microcline + micas) ± beryl. Micrometer-sized accessory magmatic species are monazite-(Ce), several high field strength element oxide species, ilmenite, cassiterite (1), fluorapatite and fluorite. Primary Li-bearing micas with variable degrees of late to postmagmatic replacement occur in abundances that range from ∼2 to 7 %. Textural evidence and mineral chemistry allow to distinguish between early granitic and late bladed miarolitic micas. The mineral chemistry composition of the primary micas shows members of the siderophyllite-polylithionite series. Replacing phases are Li-muscovite (phengite). Electron probe microanalyses of primary micas of both main granite types suggest that these are compositionally distinct intrusives. According to mica chemistry, the porphyritic unit is more enriched in Li than the equigranular granite. The equigranular unit with interconnected miarolitic texture was more intensely affected by fluid-rock interaction processes and is significantly richer in U and Be. An F–Na rich fluid phase caused strong albitization during late miarolitic stages, along with crystallization of polylithionite, fluorite, pyrochlore group species and cassiterite (2). In terms of mass balance, the phengite replacement process is characterized by the conservation of Si, Al and K, a slight gain of Na and Ba, and a systematic loss of orderly decreasing Fe > F > Li > Mn > Ti > Mg > Zn. Likely, the muscovite-forming fluid was the same simultaneously involved in the hydrothermal alteration of high field strength element accessory species, largely included in primary micas, which generated secondary U- and Nb-rich species such as carlosbarbosaite. The hydrothermal late miarolitic to postmagmatic fluid-mineral replacement of primary magmatic micas released significant amounts of Li, of which about 59 wt % of the Li2O content of protholithic micas (i.e., 1 to 2.4 wt % Li2O) was inherited by replacing Li-bearing muscovite and the remaining 41 wt % was released from the system. It is calculated that ∼1.5 km3 of La Chinchilla body would have expelled ∼0.38 million tons of Li2O, just considering than only 30 % of primary siderophyllite-polylithionite was muscovitized. Such a Li2O tonnage was likely transferred to the paleohydrological cycle during Carboniferous times, when the La Chinchilla stock was still undergoing its cooling down path. Currently, evidence of the final fate of mobilized Li is lacking.

A novel approach towards parametric assessment of reliability and resilience of high voltage mica‐based insulation systems by statistical analysis of experimental failure data

AbstractInsulation systems in high‐voltage electric machines play a pivotal role in the reliable operation and longevity of the equipment. Mica‐based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation degradation. Numerous qualifications tests, such as voltage endurance, are outlined in IEC and IEEE standards. The authors, however, take a different parametric approach, opting for reliability assessment of insulation systems using derived three‐parameter Weibull models. Therefore, instead of simple pass–fail criteria, empirical data is employed to determine failure rate probabilities quantitatively and objectively. Experimental data, including breakdown, dissipation factor, and partial discharge measurements, are used to construct the Weibull distribution model to predict fault and failure rates and calculate hazard functions. The rigorous examinations interpreted through the analytical model help assess insulation system resilience and particularly the impact of electrical field stress and mica content. Variation of electrical stress from 66.75 to 71.20 V/mil demonstrated how the mean time to failure of the system changed from 146.4 to 85.1 at 3 Un, hence identifying opportunities for design improvement and uncovering performance boundaries. Ultimately, the developed framework enhances comprehension of insulation system failure probabilities, guiding design decisions and ensuring a secure and reliable operation of electrical machines across applications.

VO2 nano-rod coated mica composite pearlescent pigment for temperature control packaging

A temperature control mica/VO2 functional pearlescent pigment was designed for the packaging industry. Firstly, a layer of VO2 nanorod film was coated on the surface of flake mica powder by hydrothermal method. Then, the surface of pure mica was modified by silane coupling agent KH-570 and sandwiched between inorganic powders to strengthen the combination. Secondly, the mica/VO2 composite pearlescent powder with gray-green pearlescent effect were successfully obtained by thermal annealing. The crystal structure of the VO2 coating and the chemical valence state of vanadium were verified by X-ray diffraction and X-ray photoelectron spectroscopy. Finally, powders were mixed with polyurethane resin to obtain a functional film. The infrared transmittance of film at 28 °C and 70 °C showed that the composite film with mica content of 3 g had greater temperature control properties, and the difference between high and low temperature transmittance was about 16%. Most importantly, the shiny decorative effect of pearlescent pigment can be still be maintained after being endowed with temperature control property. This work proposes the preparation of functional mica/VO2 composite with pearlescent effect and temperature control property.

Relationship of lithological data with the sedimentation environment of the Upper Batian deposits of the Kogalym region

Research subject. Upper Batian deposits (formation U2) of the Eastern part of the Kogalym region, within the North Nizhnevartovsk monocline. Aim. Reconstruction of the sedimentation environment of the U2 formation in the Kogalym region. Materials and methods. The reconstruction of sedimentation environments was conducted based on a macroscopic description of core samples with identification of structural and textural features of rocks from 35 wells. The clarification of sedimentation settings was carried out based on the description of 41 thin sections and a granulometric analysis of the clastic part of the studied rocks. Results. According to the macroscopic study, the U2 layer is composed of an uneven alternation of silty-argillaceous and silty-sandy rocks with coal interlayers. The rocks are of a polyfacial nature, represented by deposits of continental, transitional, and marine genesis. The thickness of the deposits varies markedly depending on the paleorelief of the area. The optical petrographic study revealed the polymictic composition of the studied rocks, which, according to the classification by V.D. Shutova, correspond to the arkose (graywacke arkose), less often graywacke (feldspar-quartz, quartz-feldspar greywackes) group. Cement most often exhibits a carbonate-clay composition. Rocks of marine genesis are characterized by a decrease in the proportion of rock fragments and an increase in the proportion of mechanically stable accessory minerals (zircon, garnet, tourmaline). The rocks of continental genesis are characterized by the maximum content of micas and plant detritus. An increase in the content of pyrite is noted in the sediments transitional from the continent to the sea. The grain-size analysis data of reservoir rocks of the U2 formation showed that both coastal-marine and channel deposits were formed in environments with active hydrodynamics of the medium, when the dynamic processing of clastic material exceeded the intensity of its supply. Conclusions. The performed lithofacies studies made it possible to reconstruct the sedimentation environment, as well as to reveal specific features in the distribution of the silty-sandy rock components of the U2 formation.

Meteoric water effect of diagenesis processes in deep carbonate reservoirs

As the world’s main oil and gas resource, the deep carbonate reservoir has great exploration-development potential. However, it is difficult to make development and exploration due to its complex diagenesis processes. During the formation of carbonate reservoirs, the effect of meteoric water forms karst holes for oil and gas reservoirs, but the complex internal mechanism severely restricts the exploration and development of carbonate reservoirs. This paper takes the deep carbonate reservoirs in the Tarim Basin as the research object, studies the diagenesis processes in deep carbonate reservoirs through geological survey, analyzes the effect of meteoric water on porosity and mineral changes in carbonate reservoirs at different diagenetic stages by using laboratory test, theoretical analysis, and numerical simulation research methods. The numerical simulation method is used to simulate the porosity changes and mineral evolution of reservoirs in different diagenetic stages, and the conclusion is drawn that meteoric water has an impact on reservoir minerals and porosity. The results show that the carbonate reservoirs in the Tarim Basin have high porosity and good permeability, and the reservoirs have experienced deposition, compaction, dissolution, and hydrothermal stages, and have experienced meteoric water effects for a long time, resulting in rock dissolution, regenerative precipitation and chemical reaction; Quartz and feldspar minerals are the most in the sample through laboratory tests, the content of quartz decreased first, then increased and decreased, and the content of chlorite and mica changed little during the whole diagenesis processes. With the injection of organic acid, the porosity of the reservoir increases, with the continuous increase of temperature and pressure, the porosity decreases. After the second injection of organic acid, the porosity increases continuously, and finally, the porosity decreases. TOUGHREACT is used to simulate the static reaction of water and rock, simulating six diagenetic stages. With the injection of organic acid, the porosity increases continuously and then reaches equilibrium. The sudden increase in temperature and pressure leads to an increase in porosity, and the porosity of the reservoir changes little during the second injection of organic acid, and the porosity decreases in the final stage. The research results provide theoretical data support for guiding oil and gas exploration in deep carbonate reservoirs.

Characteristics and control factors of feldspar dissolution in gravity flow sandstone of Chang 7 Member, Triassic Yanchang Formation, Ordos Basin, NW China

To clarify the formation and distribution of feldspar dissolution pores and predict the distribution of high-quality reservoir in gravity flow sandstone of the 7th member of Triassic Yanchang Formation (Chang 7 Member) in the Ordos Basin, thin sections, scanning electron microscopy, energy spectrum analysis, X-ray diffraction whole rock analysis, and dissolution experiments are employed in this study to investigate the characteristics and control factors of feldspar dissolution pores. The results show that: (1) Three types of diagenetic processes are observed in the feldspar of Chang 7 sandstone in the study area: secondary overgrowth of feldspar, replacement by clay and calcite, and dissolution of detrital feldspar. (2) The feldspar dissolution of Chang 7 tight sandstone is caused by organic acid, and is further affected by the type of feldspar, the degree of early feldspar alteration, and the buffering effect of mica debris on organic acid. (3) Feldspars have varying degrees of dissolution. Potassium feldspar is more susceptible to dissolution than plagioclase. Among potassium feldspar, orthoclase is more soluble than microcline, and unaltered feldspar is more soluble than early kaolinized or sericitized feldspar. (4) The dissolution experiment demonstrated that the presence of mica can hinder the dissolution of feldspar. Mica of the same mass has a significantly stronger capacity to consume organic acids than feldspar. (5) Dissolution pores in feldspar of Chang 7 Member are more abundant in areas with low mica content, and they improve the reservoir physical properties, while in areas with high mica content, the number of feldspar dissolution pores decreases significantly.

Damping materials based on plasticized polybutyl methacrylate, polymethyl methacrylate and polyvinyl acetate

The purpose of the presented work is to investigate by DMA method the influence of the composition of filled and unfilled plasticized compositions based on polyvinyl acetate (PVA), polybutyl methacrylate (PBMA) and polymethyl methacrylate (PMMA) on their damping characteristics. It was found that when plasticizer is introduced into the polymer, the value of the mechanical loss coefficient first increases, reaches its maximum, and begins to decrease with further increase in the plasticizer content. The maximum effect is observed at a plasticizer/polymer volume ratio of 0.2-0.4. Two other dissipative characteristics, the temperature interval of effective damping and the integral coefficient of mechanical losses, are changing similarly. It is established that the additives of chlorinated paraffins in compositions based on PVA and PBMA can significantly improve their vibration absorbing characteristics. Introduction of mica filler into the composition of plasticized compositions based on PVA and PBMA does not lead to the appearаnсe of additional relaxation mechanisms. With increasing of the content of mica, the elastic modulus of compositions increases in the entire temperature range (especially significantly for compositions with a high content of plasticizer), the coefficient of mechanical losses slightly decreases, and the temperature practically does not change at which the maximum damping is observed.

Whole-Rock Geochemistry and Mica Compositions in Lijiagou Pegmatite Spodumene Deposit, Western Sichuan, China

The Lijiagou pegmatite spodumene deposit, located in the middle of the Songpan–Garze Fold Belt and southeast of the Ke’eryin ore field, is a newly discovered super-large deposit. In order to reveal the metallogenic tectonic environment and evolution process of pegmatite, based on the study of the geological characteristics of pegmatite, we carried out a whole-rock geochemical analysis of Ke’eryin two-mica granite and Lijiagou pegmatite and carried out a detailed electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis of mica minerals in each zonal pegmatite. The results show that the Ke’eryin two-mica granite is mainly formed in the transition period from syn-collision to post-collision. After the end of the continental collision, the crust is squeezed and thickened in the post-collision extensional transition tectonic environment. Mica from the microcline pegmatite zone (MP) to the albite spodumene pegmatite zone (ASP) in pegmatite show different compositions and structural characteristics, with the evolution trend in the direction from muscovite to Li-bearing mica. The type of mica from MP to AP is mainly muscovite, and Li-bearing mica appears in ASP, which is secondary and metasomatic at the edge of primary muscovite. From MP to ASP, there was a negative correlation between Nb/Ta, K/Rb and the Li, Rb, and Cs contents of mica, while the contents of Li, Rb, Cs, and F in the Li-bearing mica of ASP increased sharply. This evidence illustrates that the favorable tectonic environment contributed to the formation of the Lijiagou pegmatitic spodumene deposit. Lijiagou pegmatite experienced the magmatic–hydrothermal evolution process and has a high degree of differentiation and evolution from MP to ASP, which gradually increased. Combined with the change in mica type, it is considered that ASP formed from the stage of magmatic transition to hydrothermal and was a hydrothermal environment, and Li, Rb, and Cs mainly began to enrich at the stage of magmatic–hydrothermal transition.

Effects of latex type and processed-mica waste loading on the structural and thermo-physical properties of natural rubber latex foam composites

Mica waste, a type of commercial waste produced in bulk quantities by the mica mining industry, was processed and added to Natural Rubber Latex Foams (NRLF) made of centrifuged and creamed latex. Following the Dunlop method, NRLF composites with various Processed Mica Waste (PMW) loadings (0, 2, 4, 6, 8, and 10 Phr) were prepared, and the thermo-physical characteristics were compared. Thermal conductivity, electrical resistivity of NRLF against the latex type and mica loading were compared for the first time. NRLFs prepared using creamed latex exhibit 33 and 50 μm (width and height) cell diameter, 3 ibf hardness, 281 % swelling index improvements and 0.05 Wm−1K−1 thermal conductivity, and 1 °C glass transition temperature (Tg) reductions than centrifuged NRLF and indistinguishable electrical resistivity. With the addition of mica (0–10 Phr), both NRLF types showed a similar ascending trend in hardness (42 ibf), water absorption (16 %), Tg (7 °C), thermal conductivity (0.54 Wm−1K−1), electrical resistivity (69 × 103 Ω m) with decreasing gel time (3 min) and swelling index (550 %). The key objective of this research was to prepare PMW-filled NRLF and compare structural, electrical and thermo-physical properties, for the first time, against mica content and latex type.

Features of the mineralogical composition of solod and solod meadow-chestnut soil, the case of soils of the liman depression at Dzhanybek research station of the Institute of Forest Science RAS

The structure of the soil cover at the territory of the clayey semidesert of the Northern Caspian Sea is represented by triparted soil complex and peculiar soils like solod. Solods are formed in relief elements that are constant for this territory – mesodepressions, which are referred to limans. Two soil profiles were studied in the bottom of the liman – solod, and on its peripheral part – solodized meadow-chestnut soil. The formation of the solod profile occurs because of periodic moistening with fresh water and systematic flooding during the snowmelt period. The second soil is in the zone of transit of surface water to the liman. The soil profiles have the same type of eluvialilluvial distribution of the clay fraction, while differentiation is more distinct in solod. Mineralogical analysis established the same type of qualitative composition of clay and clastogenic minerals in both soils. Clay minerals are represented by illite, smectite, mixed-layer illite-smectite, accompanied by kaolinite and chlorite. Clastogenic minerals are represented by quartz, mica, K-feldspar, plagioclase, and chlorite. Quartz and feldspars are accumulated in the solodized horizons of the soil profiles; the content of quartz and feldspars decreases in the textural horizons, while the content of mica and chlorite increases. The distribution of the smectite phase in the solod profile reveals a difference in the ratio of illite-smectite packets, structures with a low content of smectite packets predominate in the solod part of the profile, and the proportion with a swelling packet in mixed-layer minerals increases in textural horizons. The solodized meadow-chestnut soil is distinguished by a smaller thickness of the solodized horizon, a higher content of the smectite component, and a calm character of the profile differentiation of clay and clastogenic minerals. In both soils, labile minerals with signs of superdispersion are recorded in the solodized and textural horizons. The superdispersion of labile minerals has different causes. In solod, it is associated with the action of low-mineralized water and the hydrolysis of soil minerals during the wet seasons of the year, as well as with the intense regime of intrasoil weathering in situ, and in the solodized meadow-chestnut soil, with the passage of the stage of solonetz soils. Differences in the smectite component were also revealed: in the solodized horizons of solod, it is represented by individual smectite and the mixed-layer phase of illitesmectite; and in the meadow-chestnut soil – by mixed-layer illite-smectite.

Engineering geological characterization of micaceous residual soils considering effects of mica content and particle breakage

The engineering geological characteristics of micaceous residual soil (MRS), which is prevalent in subtropical regions, are markedly influenced by the presence and breakage of mica particles. Nevertheless, a comprehensive understanding of the underlying mechanisms responsible for these effects remains elusive. In this study, a series of experimental tests were conducted on two groups of reconstituted MRS samples. These samples were prepared by mixing natural MRS, from which the original mica had been removed, with intact and crushed mica powder, respectively. The aim was to investigate the effect of the mica content and particle breakage on the physical and mechanical properties of MRS. Scanning electron microscopy was employed to scrutinize the microstructural alternations of mica particles at different states of breakage, and a conceptual model was proposed based on the observations. The findings revealed that the presence of mica considerably altered the physical properties of MRS, resulting in higher Atterberg limits but lower plasticity, along with unfavorable mechanical properties, including high compressibility and swelling potential, low compactability, stiffness, strength, and ductility. The microstructural analysis elucidates that these effects stem from the resilient nature of layered mica flakes with high water-retention capacity. On the other hand, the breakage of mica particles changed these effects. The disappearance of interlayered voids following mica particle breakage leads to reduced Atterberg limits and enhanced compaction efficiency of the mixture. Moreover, MRS with a higher proportion of crushed mica exhibited more significant deformation and compression during shearing. This behavior can be attributed to the diminished stiffness of crushed mica and weaker interparticle contacts within the soil matrix. This study provided a multi-scale insight into how mica affected the engineering geological properties of MRS and proposes references for more effectively incorporating of MRS into engineering construction projects.

Chemical features of dark miсas from calcite-nepheline-feldspar pegmatites of the Ilmenogorsky alkaline block (South Urals)

The composition and structure of micas of the annite–phlogopite and siderophyllite– eastonite series in calcite-nepheline-feldspar pegmatites of the Ilmenogorsky miaskite block are studied. The composition of mica of the annite–phlogopite series depends on the formation conditions of pegmatites. The nepheline-feldspar pegmatite with a rock-forming calcite (mine no. 125) contains annite with higher Fe content (Ftot 0.67–0.73). A pegmatite with late calcite (mine no. 16) contains less ferruginous annite (Ftot 0.52–0.63) and phlogopite (Ftot 0.32–0.50). The mica of the annite-phlogopite series exhibits a direct correlation between the Fetotal and Al contents. The mica of the siderophyllite–eastonite series in calcite-nepheline-feldspar pegmatites formed later in assemblage with minerals of the pyrochlore group, baddeleyite, calcite, fuorite, magnetite and Nb-bearing rutile. The Fe content of micas affects the shift of the Raman bands in the studied Samples. Ferruginous siderophyllite, eastonite and their barium varieties are identifed for the frst time for the Ilmenogosrky-Vishnevogorsky complex.

Design, Fabrication, and Performance Analysis of Fire‐resistant Damping Polyurethane

AbstractTo improve the noise reduction and fire resistance of marine coating materials, some fire‐resistant polyurethane damping materials were prepared by varying the ratio of esterified branched polyols (EBP) and the 1,4 butanediol (1,4 BD), the content, and the particle size of the mica filler. The effects of branch chain, mica filler content, and particle size in polyurethane structure on the mechanical, dynamic mechanical properties, and fire resistance of polyurethane and its polymerization process were studied. The experimental results showed that the effective damping temperature range of polyurethane material widened from 42.1 °C to 76.6 °C, and then narrowed to 31.2 °C with the increase in EBP ratio. And the maximum loss factor (tanδmax) of these samples is 0.989. The increase of mica content and the decrease of mica particle size in polyurethane damping materials make the dynamic mechanical properties of polyurethane damping materials present a trend of first improving and then impairing. Moreover, the mechanical properties of polyurethane enhanced with the increase of EBP and weakened with the increase of mica mass fraction. This research is expected to advance the development of marine coatings and address noise reduction and fire protection challenges for marine materials.

Characterization and Liberation Study of the Beauvoir Granite for Lithium Mica Recovery

A significant proportion of Europe’s lithium endowment is hosted by unconventional lithium resources such as rare-metal granites (RMG) of which the Beauvoir granite in France is a prime example. In such hard-rock deposits, where lithium is mostly hosted in micas (lepidolite, zinnwaldite), the ability to assess whether lithium can be extracted economically from the ore is essential and requires a comprehensive understanding of mineralogical properties and lithium deportment. Using three exploratory drill cores distributed along the North–South axis, a preliminary geometallurgical assessment of the granite has been conducted based on a combination of techniques including Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), Atomic Adsorption Spectroscopy (AAS), Electron Probe Microanalysis (EPMA), Scanning Electron Microscope (SEM) coupled with automated mineralogy software, X-Ray Diffraction (XRD), optical microscope and sieving. Lithium distribution appears to be variable, reflecting the evolution of the granite, with higher mica content in the southern area and higher Li grade towards the center of the orebody. The size of micas in the assessed sample does not vary significantly. The grindability and liberation size of micas varies in the different zones investigated, PERC S being the most difficult to grind. There is always more than 50 wt% of the micas that are liberated in the samples when crushed to 1 mm. Indirect estimation of Li content based on EPMA and SEM analysis suggests that the content of lithium inside mica crystals could vary. If this estimation is confirmed by direct Li measurement, it for sure makes the calculations of the Li deportment more challenging.