Talc Ore Research Articles

High-efficiency luminescent Eu3+ heavily doped glass prepared from black talc: A promising material for significant applications in W-LED illumination

As a distinguished luminescent matrix, rare earth (RE)-doped glass has garnered considerable attention across lighting, display, laser, and related domains. Nonetheless, the limited luminescent efficiency of such glass imposes constraints on its extensive utilization. In addressing this challenge, we have developed a novel formulation involving heavily Eu3+-doped black talc glass, boasting exceptional optical characteristics. Structural examination has validated the successful synthesis of the parent glass matrix comprising [SiO4] and [AlO4] units. With the escalating of Eu3+ doping concentrations, the glass manifested an upward trend in both density and refractive index. Under the excitation of 393 nm light, the glass exhibited strong red light emission, demonstrating a high internal quantum efficiency (IQE) of up to 84.67 %, surpassing markedly other Eu3+-doped glass variants. Furthermore, even under elevated temperatures reaching 150 °C, the glass retained 86.2 % of its luminescent intensity at room temperature, indicative of superior thermal resilience vis-à-vis alternative glass systems. As a proof-of-concept, we encapsulated a white light-emitting diode (W-LED) assembly employing a 395 nm LED chip, Eu3+-doped glass, BaMgAl10O17:Eu2+ blue phosphor, and Ba2SiO4:Eu2+ green phosphor. The resultant device exhibited favorable chromaticity coordinates (0.3566, 0.3994), boasting a correlated color temperature (CCT) of 4791K and a high color rendering index (CRI) of 91. In summary, this investigation employs black talc ore to synthesize luminescent glass, thereby not only diversifying the application scope of black talc but also augmenting its additional value, while notably enhancing the luminescent efficiency of the glass through heavy Eu3+ doping. Through empirical validation, the significant potential benefits of Eu3+-doped black talc glass in the realm of W-LED lighting were convincingly demonstrated.

Bilyeli Değirmen ve Karıştırmalı Değirmen Kombinasyonu ile Çok İnce Talk Üretimi

In this study, it was investigated that talc ore could ground to very fine sizes using a combination of conventional ball mill and vertical stirred mill. Firstly, the conventional ball mill parameters such as mill speed (% of critical speed), material filling ratio (Jb), ball filling ratio (fc), ball size distribution (10-20-30-40 mm, %), grinding aid ratio (% of powder) and grinding time (min.) were optimized using classic experimental design. As a result of the optimization, fine talc product was obtained with d90=93.52 µm particle size. In the second stage, the ball mill product was re-milled using a stirred mill. As a result of study, a final ultra-fine talc powder was obtained after 60 minutes grinding time with d50=1.85 µm particle size and 14058 cm2/g total surface area. It has been seen that the conventional ball mill+stirred mill combination effective a process to obtain talc powder that suitable for industrial use.

Application of factorial model for an optimization of partial replacement of feldspar by talc on the sintering process

AbstractThis research used a factorial model containing two levels and three variables to evaluate the partial substitution of sodium feldspar (albite) by a talc ore found in abundance in the region of Itaiacoca—Brazil. The model can also be used to verify the influence of initial talc particle size, proportion, and sintering threshold temperature on the following physical properties, such as linear shrinkage, water absorption, bulk density, total porosity, and firing color. In this study, the mechanical strength of the compositions was evaluated by the flexural strength test. The factorial model indicated the sintering temperature as the variable that most affects the samples’ densification and the proportion of talc as the variable that changes the firing color. The experiment that used a higher sintering temperature combined with a coarser talc granulometry presented the highest mechanical strength. When more refined granulometry was used, there was the beginning of an overfire process. Water absorption values in the range of .04% and modulus of rupture of 49 MPa were obtained, confirming the talc's effectiveness as a secondary flux agent suitable for the formulation of ceramic bodies.

Evaluation of asbestos exposure resulting from simulated application of spiked talcum powders

This study characterizes airborne asbestos exposures resulting from the adult application of cosmetic talc body powders spiked with known concentrations of tremolite. Raw talc ores were spiked with 0.005% and 0.1% asbestiform or non-asbestiform tremolite. Personal samples were collected during 16 simulated events, including puff and shaker application and associated clean-up activities. Airborne fiber levels (PCM) were not significantly different for simulations involving talc spiked with asbestiform and non-asbestiform tremolite (p = 0.6104). For application and clean-up of talc spiked with 0.005% asbestiform tremolite, 2 of 24 (8.3%) samples were above the LOD for TEM (0.003 f/cc). For application of talc spiked with 0.1% asbestiform tremolite, 21 of 24 (87.5%) were above the LOD for TEM. The corresponding mean PCME asbestos concentrations were 0.016 f/cc for puff and shaker for samples collected in the first 15 min, 0.002 f/cc for puff and 0.004 f/cc for shaker in the second 15 min, and 0.005 f/cc for puff and 0.013 f/cc for shaker for the full 30 min. Mean PCME concentrations for samples collected during clean-up following application of talc spiked with 0.1% asbestiform tremolite were 0.003 f/cc for samples collected in the first 15 min following puff application, 0.005 f/cc for samples collected in the second 15 min following shaker application, and 0 f/cc for the remaining clean-up samples. Using the EPA’s exposure factors, we determined the range of cumulative asbestiform fiber exposures that would result from product use, assuming asbestiform tremolite was present at 0.1%.

Influence of Bacillus subtilis on the surface behavior and separation of talc and chlorite minerals

Abstract Bacillus subtilis was used as a bio-surface modifier to improve the floatability of talc mineral (Mg3Si4O10(OH)2) in the talc ore. The surface behavior of chlorite mineral as the main associated gangue with talc mineral was studied in the presence of B. subtilis using zeta potential, scanning electron microscopy, and Fourier-transform infrared spectroscopy techniques. The floatability of both minerals was investigated as a function of pH, contact time, and concentration of B. subtilis. The results showed that the zeta potential of the talc mineral was strongly influenced by the treatment with B. subtilis. The maximum separation efficiency of talc from chlorite was achieved at pH 4. A talc concentrate with 98% quality and about 95% recovery was prepared from a binary talc-chlorite mixture containing 85% talc under optimum conditions of 8 × 105 cells/mL B. subtilis, pH 4, 35°C, and a contact time of 10 min.

Upgrading of a Nigerian Vermiculite-Phillipsite Rich Talc Ore by Flotation-Cum-Acid Leaching Routes for Industrial Applications

Upgrading of a Nigerian Vermiculite-Phillipsite Rich Talc Ore by Flotation-Cum-Acid Leaching Routes for Industrial Applications

The Differences in Evaluation of Flotation Kinetics of Talc Ore Using Statistical Analysis and Response Surface Methodology

This paper investigates the effect of sodium hexametaphosphate (SHMP) depressant/dispersant in the presence of methyl isobutyl carbinol (MIBC) frother and soluble starch (SS) depressant on the flotation kinetics of talc ore. Emphasis is on a comparison between the evaluation of a custom design of experiment (DoE) using the multilinear regression analysis (MRA) and response surface methodology (RSM) approach. Although analysis of variance (ANOVA) is a good first step in the evaluation of the effect of factors on froth flotation processing, it nonetheless only reveals the effects that are the same under all conditions. In the case of SHMP, its effect on separation efficiency is positive; however, if it is used along with SS, the effect is negative. Moreover, if a higher frother dosage is used, the effect of SHMP on separation efficiency is negligible.

Structural-Morphological Types and Localization Conditions of the Apocarbonate Talc Mineralization in the Beloretsk District of the Western Urals Province

The structural–morphological types and localization conditions of talc occurrences in the Beloretsk district of the Western Urals talc province are discussed. The talc mineralization is represented by low-iron talcites and talc stones in the Riphean clastic–carbonate complexes of the Bashkirian Meganticlinorium. Prospective talc objects in the Beloretsk district are classified as apocarbonate, to be distinguished from the apoultramafic deposits, which are predominant in the Urals. The hydrothermal–metasomatic genesis of the talc ores, their association with the metamorphosed dolomite-bearing members of the Lower and Middle Riphean Kyzyltash and Avzyan formations, the cooccurrence with magnesite deposits, and the absence of relationship with granitoid magmatism are established. The inner resources of the Riphean sedimentary basins, activated by metamorphic processes, are viewed as the sources of ore-forming fluids. The flanks of magnesite bodies in dolomite sequences near contacts with silicate interbeds are considered as the lithological settings favorable for talcite formation. The presence of the stacks of interbedded magnesian–carbonate and aluminosilicate rocks in the Riphean sequences facilitates the silica–magnesium bimetasomatism but leads to the formation of predominantly lean talc–chlorite stone varieties. The morphological types of mineralization are represented by the stratiform bed-like talcite and talc stone bodies; the saddle-like and ribbon-like talcite bodies confined to monoclines and fold hinges and limbs; and the fault controlled steeply dipping linear bodies of rich talc ores.

The occurrence of Hg, Se, S, Ni, Cr, and Th in Talc Ore: A scanning electron microscopy (SEM) study of historical samples from the Willow Creek Mine, Montana

Due to short timeframes over which small-scale talc mines operate (approximately 1 to 10 years), detailed characterization of their mineralogy and geochemistry in the peer-reviewed literature is limited. Investigation of sample 1497 of the Willow Creek Mine, Montana by scanning electron microscopy using back scatter detection (SEM-BSD) indicates a complex minor mineral assemblage. Hg-Se-S minerals are associated with graphite whereas Zn-Cr-Ni minerals and Th minerals are dispersed in the talc matrix. Notably, Hg, Se, Zn, Cr, and Ni are of human health concern. Minerals with these elements are ~ 20 to 0.4 µm in diameter, and all have examples in the PM10 or PM2.5 size fraction. These minerals would likely not be separated out during processing of talc ore and would be inhalable. Results indicate a need for detailed SEM-BSD investigations of historic talc products from the Willow Creek Mine and for investigating ore from similar settings in Montana.

Inhalation Toxicity of Talc.

Respirable talc powder (RTP) is a complex mineral mixture of talc along with accessory minerals, including tremolite, anthophyllite, quartz, magnesite, dolomite, antigorite, lizardite, and chlorite. The industrial mining, milling, and processing of talc ore is associated with elevated incidences of fibrotic and neoplastic diseases, which are also seen among workers exposed to RTP in secondary industries and individuals using processed cosmetic talc for personal use. There is controversial evidence of a link between the talc-induced lung diseases and a potential contamination with asbestos fibers. This controversy is fueled by inadequate exposure data and the complex mineralogy and terminology of the accessory minerals. Talc aerosols exhibit a wide range of mineral habits, including particulates and fibrous structures that have dimensional and compositional characteristics related to the development of asbestos-related lung disease. The inhalation toxicology of RTP is based on the analysis of occupational hygiene and animal inhalation studies conducted between the 1940s and the 1990s and more recent mechanistic studies conducted both in vivo and in vitro. The review of talc toxicity studies reveals that the occupational studies provide only equivocal links between any of the components of the aerosols and the development of pulmonary cancer; however, there is substantial evidence of an association between the aerosols and pleural and pulmonary fibrosis and the development of nonmalignant respiratory disease. The animal inhalation and implantation studies appear to be less than optimal, which also appears to be true for the in vivo and in vitro studies. The mechanistic studies have identified the key pathogenic characteristics of asbestos to be long and thin fibers that are durable in lung tissues and fluids. Talc toxicity studies show that talc particles and fibers are durable and can remain in the lung for up to 40 years after the end of exposure. This extended tissue residence is considered to constitute a continuing tissue exposure that is capable of inducing the documented inflammatory and proliferative response. There is less consensus as to whether there is a threshold fiber length effect, as long, thin fibers (>5 μm) form only a small fraction of talc aerosols and the possible role of fibers >5 μm in the translocation from the lung to the pleura and their association with pleural fibrotic and carcinogenic lesions. Long, thin fibers are preferentially deposited in hot spots in the lung, such as airway bifurcations, areas typically associated with the development of lung cancer. The platy structures typical of talc can form oblate structures behaving more as fibers in the air stream, and these have also been shown to deposit preferentially in such locations. The review of the inhalation toxicity of talc provides a plausible explanation for the carcinogenic potential of RTP.

Excellent electrochemical properties of graphene-like carbon obtained from acid-treating natural black talc as Li-ion battery anode

Because the commercialized graphitic carbon as an anode material is still limited by low capacities and poor long cyclic stability, new carbonaceous materials with good electrochemical performance are still needed to be sought. In the present work, a new fluorinated carbon material was obtained from natural black talc ore by HF acid-treating method. The influences of heat treatment on the composition, morphology and structure characteristics of the fluorinated carbon were investigated and possible fluorination/defluorination mechanisms were proposed. As an anode material for Li-ion battery, the electrochemical performance of the samples was greatly influenced by their surface characteristics. The fluorinated carbon showed high capacities of ∼756 mAh/g and ∼620 mAh/g at rate of 0.1 C and 0.2 C, which resulted from more active sites provided by plenty of fluoride groups on the surface of the fluorinated carbon. In contrast, the sample annealed at 800 °C exhibited relatively high capacity of ∼477 mAh/g at rate of 0.1 C with excellent rate performance due to its better electrical conductivity caused by the removal of the fluorine groups. The present work provides a new direction for the application of black talc and other similar natural minerals.

Ore Genesis and Geochemical Characteristics of Carbonate‐Hosted Talc Deposits in Nangarhar Province, Afghanistan

AbstractTalc deposits in Nangarhar Province, are hosted by Paleoproterozoic carbonate rocks, metamorphosed to amphibolite facies in the east–west (E–W) trending Spinghar Fault Block. Many deposits in this province have potential economic importance. However, detailed geologic and petrological studies on ore genesis are still lacking. In this study, eight talc deposits and two prospects of the Spinghar Fault Block were investigated. Talc is mainly formed by alteration of the host dolomite marble, magnesite rocks, and tremolitite. Talc ore bodies occur parallel to subparallel to the beddings of the host carbonate rocks. Dolerite occur as dikes and sills and are mostly metamorphosed to amphibolite. Although the amphibolite occurs mostly parallel to subparallel to the beddings of the host carbonate rocks, and talc orebodies, it partly crosscuts the host rocks. Massive layers of tremolitite were observed with most of the talc ore bodies. Quartz veins occur along the gneissosity of gneiss all over the study area. SiO2 and MgO content in talc rocks from all deposits ranged from 49.1 to 65.1 wt% and from 26.1 to 32.9 wt%, respectively. CaO content in talc rocks and magnesite rocks are less than 1 wt%. ƩREE content in talc rocks ranged from 0.1 to 8.9 ppm. Chemical compositions of host carbonate rocks are close to the ideal composition. Concentrations of Al, Ta, Hf, Zr, Th, Cr, Ni, Co, and ƩREE in talc ores and host carbonate rocks were very low and inconsistent with mafic and ultramafic rocks protolith. Therefore, the metamorphosed sedimentary carbonate rocks were likely to be the protolith of the talc ores. The occurrence of parallel to subparallel quartz veins to the gneissosity of gneiss, as well as the presence of hydrous minerals in host carbonate rocks, suggested that hydrothermal fluids were most probably supplied through the gneiss.

Reactivity of meta-talc in sodium hydroxide medium

This work deals with the reactivity of XRD amorphous delaminated and dehydroxylated talc phase (meta-talc), in alkali medium. Talc ore Luzenac H70 was treated in a stirred ball mill (attritor) for 30; 60 and 90 min with subsequent thermal treatment at 700°C; 750°C and 800°C. Reactivity of mechanochemically and thermally treated talc ore in NaOH solution was studied using isothermal calorimetry. An influence of material crystallinity and amount of water coordinated in material structure after milling on its reactivity in alkali medium was studied.

Preparation of mesoporous silica from a Nigerian talc ore by acetic acid treatment

A study on the preparation of porous silica from a Nigerian talc ore by acetic acid leaching was investigated. The initial and leached talc products were characterized by Energy Dispersive X-ray fluorescence EDXRF , X-ray diffraction XRD , Scanning Electron Microscopy SEM with Energy Dispersive spectroscopy EDS and the N2 adsorption techniques. The influence of acetic acid concentration, reaction temperature and particle size on the ore leaching kinetics were examined. The results of the dissolution rates were found to be significantly influenced by leachant concentration, temperature and decreasing particle size. The dissolution mechanism process followed the diffusion control shrinking core model with the calculated activation energy of 34.53 kJ/mol supporting the proposed mechanism. The leached product has a specific surface area increased to 2.056 m2 /g from the initial ore surface area of 0.15 m2 /g. At optimal leaching conditions, the pore size distribution calculated by Barret-Joyner-Halenda BJH method based on N2 gas isotherms showed the presence of peaks from micropores and mesopores formation, indicating the porous nature of the leached product.

Current issues with purported "asbestos" content of talc: Asbestos nomenclature and examples in metamorphic carbonate and ultramafic hosted talc ores

Current issues with purported "asbestos" content of talc: Asbestos nomenclature and examples in metamorphic carbonate and ultramafic hosted talc ores

Impact of Talc Ore Mining on Periphyton Community Structure and Water Environment

In order to explore the impact of Talc ore mining on aquatic ecosystems, periphyton communities and environmental factors from control portion, impacted portion and recovery portion separately were investigated and analyzed. Samples were collected from upstream Tanghe River (an important tributary of Tazi River) in November 2015, April 2016, and July 2016. Mann-Whitney U test was applied to compare the differences in environmental factors and periphyton community structures among three portions. Spearman correlation analysis, canonical correspondence analysis, and t-value biplot analysis were used to determine the relationship between the environmental factors and periphyton community structures. In the control and recovery portions, mass concentrations of magnesium (Mg), selenium (Se), arsenic (As), iron (Fe), molybdenum (Mo), bicarbonate ion (HCO3-), nitrate ion (NO3-), power of hydrogen (pH) and electric conductivity (EC), were the highest, and in the impacted portion, mass concentrations of potassium(K), sodium (Na), strontium (Sr), barium (Ba), silicon dioxide (SiO2), and dissolved oxygen (DO) were the lowest. The mass concentrations of Mg, Mo, As, EC, and HCO3- were significantly different (P<0.05) among the three portions. In control and recovery portions, the periphyton density, species richness, diatom siltation index, and relative abundance of Achnanthes sp. were the highest, while in the impacted portion, the percentage of handle diatom, the relative abundance of Surirella sp., and relative abundance of Navicula sp. were the lowest. Species richness of periphyton was significantly different (P<0.05) among the three portions. In summary, Mg, EC, and HCO3- from Talc Ore mining had significant impacts on periphyton assemblage structure.

Current issues with purported asbestos content of talc: Hydrothermal-hosted talc ores in southwest Montana

Current issues with purported asbestos content of talc: Hydrothermal-hosted talc ores in southwest Montana

Interstratification of graphene-like carbon layers within black talc from Southeastern China: Implications to sedimentary talc formation

Large deposits of unusual black talc interstratified with dolostone layers of the late Neoproterozoic Dengying Formation were discovered in Guangfeng County, Jiangxi Province, southeastern China. The black talc ore exhibits primarily oolitic structures and consists mainly of talc (30–70 wt%), dolomite, and quartz, with trace amounts of pyrite and apatite. The ooids are composed of nearly pure black talc crystals, most of which consist of ultrafine nano-plates. The black talc contains small amounts of carbon, which causes the black coloring. Raman spectra and X-ray photoelectron spectroscopy (XPS) results indicate structural disorder and chemical impurities within bonds (e.g., sp 3 hybridized carbon and C–O bonds) in the carbonaceous material, instead of perfectly structured graphite or graphene. Isolated graphene-like carbon interlayers are present in the talc nano-crystals, as shown by Z-contrast transmission electron microscope (TEM) imaging. Based on previous studies on Mg-silicate precipitation from surface water, we propose a sedimentary formation mechanism for the black talc, in which tetrahedral–octahedral–tetrahedral (T-O-T) layers of Mg-silicates, 1~2 unit-cells thick, co-precipitated with abundant organic matter derived from microorganisms thriving in locally Al-depleted sea water with high concentrations of Mg 2+ and SiO 2 (aq), in a shallow marine or lagoonal environment. The involvement of organic matter may have facilitated the precipitation of Mg-silicate. Further diagenesis and re-crystalliztion of the biomass-coated precursor resulted in the formation of graphene-like layers between neighboring talc nano-crystals with same orientation.

The Art of Talc Flotation for Different Industrial Applications

Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (25.40%), low SiO2 (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%), indicating its low grade. Attrition scrubbing of the crushed ores was found to be an unconventional process, not only for fine talc production, but also for proper separation of the harder carbonaceous gangue. Talc pre-concentrates, less than 0.074 μm, were prepared by attrition scrubbing in the laboratory having 8.40% L.O.I. with a yield reaching 74.70%. Cleaner talc concentrate with L.O.I. content averaging 6.70% was obtained by flotation in the presence of Aerofroth 71 with a yield reaching 64.71%. This was relatively improved by the use of a selective (quaternary amine) talc collector and in presence of a selective carbonate depressant (soda ash). Flotation of the fine ground talc (less than 22 μm) produced a talc concentrate assaying 6.90% L.O.I. with a yield recovery of 62.91%. However, different talc concentrates obtained by just natural floatability or by the use of small dose of Aerofroth 71, or by the application of quaternary amine in presence of carbonate depressant, satisfy the requirement of paper coating, ceramics production, functional filler, and pharmaceuticals applications. Tailings could also be used in carpets, roofs, and tiles production industries.

Optimization of operating variables for production of ultra-fine talc in a stirred mill. Specific surface area investigations

Due to its properties such as chemical inertness, softness, whiteness, high thermal conductivity, low electrical conductivity and adsorption properties talc has wide industrial applications in paper, cosmetics, paints, polymer, ceramics, refractory materials and pharmaceutical. The demand for ultra-fine talc is emerging which drives the mineral industry to produce value added products. In this study, it was investigated how certain grinding parameters such as mill speed, ball filling ratio, powder filling ratio and grinding time of dry stirred mill affect grindability of talc ore (d 97 =127 μm). A series of laboratory experiments using a 24 full factorial design was conducted to determine the optimal operational parameters of a stirred mill in order to minimize the specific surface area. The main and interaction effects on the volume specific surface area (SV, m2 .cm−3 ) of the ground product were evaluated using the Yates analysis. Under the optimal conditions at the stirrer speed of 600 rpm, grinding time of 20 min, sample mass of 5% and ball ratio of 70%, the resulting talc powder had larger volume specific surface area (i.e. , 3.48 m2 .cm−3 ) than the starting material (i.e. , 1.84 m2 .cm−3 ).