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João Geraldo Martins De Souza - One of the best experts on this subject based on the ideXlab platform.
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Argamassa baritada : teste da proporção e da espessura do revestimento, para uso como barreira de proteção para raios-x de 30K e V de energia efetiva, em clinicas odontologicas
[s.n.], 2018Co-Authors: João Geraldo Martins De SouzaAbstract:Orientador: Frab Norberto BoscoloDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O presente estudo teve o propósito de determinar a proporção ideal do mineral barita em argamassa de revestimento. E a espessura necessária e equivalente à espessura de chumbo para barrar ou absorver raios-X de aproximadamente 30keV de energia efetiva, para blindagens em clinicas de radiologia odontológica. Foram confeccionados blocos de argamassa baritada com 150x150mm e espessuras de 1.4 a 15.1mm. Foi utilizado como fonte de radiação um a aparelho GE 100 modelo A0061. Os feixes incidentes e emergentes de radiação, foram medidos por meio de dosimetros termoluminescentes de Fluoreto de Litio 700, e por câmara de ionização e eletrometro Victoreen modelos 600-4 e 600 respectivamente, e ainda foi feito um cálculo teórico a partir dos elementos componentes da argamassa, para uma comparação com os resultados nos testes. Os resultados evidenciaram que a barita, numa proporção de 60%, em relação aos demais componentes da argamassa estudada, para raios-X de aproximadamente 30keV de energia efetiva (93.7 kVp), foi obtido por meio de um fator de conversão de 5.6 da espessura da argamassa para espessura necessária de chumbo. A camada semi-redutora (HVL) da argamassa baritada foi de 1.24mm e a camada semi-redutora (HVL) do chumbo foi de O.22mm. Assim sendo, para cada milímetro de chumbo seria necessário 5.6mm da argamassa de revestimento para uma proteção eficienteAbstract: The present paper has the aim of determine the ideal portion of baryte mineral in plaster and the necessary equivalent thickness of plumbum to absorb or stop x-rays in nearly 30keV effective energy, in isolating odontological clinics. Baryte plaster boards were made at 150x150mm and from 1.4 to 15.1mm of thick. As a radiation source, a GE 100, model A0061 device was used. The incidental and emergent radiadion beams were measured with Lithium Fluoride 700 dosimeter and ionization chamber and Victoreen electrometer models 600-4 and 600 respectively. A theo cal calculus was also done from the plaster compound elements for a testing result comparison. The results highlighted that baryte in 60% portion related to the other studied plaster compounds for x-rays nearly 30keV effective energy (93.7kVp) was obtained through a convertion factor of 5.6 in the plaster thickness for the plumbum necessary thickness. The baryte plaster half-value-layer (HVL) was 1.24mm and the plumbum half-value-layer was 0.22mm. Hence, for each plumbum milimeter it would be necessary 5.6mm of plaster for an efficient protectionMestradoRadiologiaMestre em Odontologi
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Argamassa baritada : teste da proporção e da espessura do revestimento, para uso como barreira de proteção para raios-x de 30K e V de energia efetiva, em clinicas odontologicas
2017Co-Authors: João Geraldo Martins De SouzaAbstract:Resumo: O presente estudo teve o propósito de determinar a proporção ideal do mineral barita em argamassa de revestimento. E a espessura necessária e equivalente à espessura de chumbo para barrar ou absorver raios-X de aproximadamente 30keV de energia efetiva, para blindagens em clinicas de radiologia odontológica. Foram confeccionados blocos de argamassa baritada com 150x150mm e espessuras de 1.4 a 15.1mm. Foi utilizado como fonte de radiação um a aparelho GE 100 modelo A0061. Os feixes incidentes e emergentes de radiação, foram medidos por meio de dosimetros termoluminescentes de Fluoreto de Litio 700, e por câmara de ionização e eletrometro Victoreen modelos 600-4 e 600 respectivamente, e ainda foi feito um cálculo teórico a partir dos elementos componentes da argamassa, para uma comparação com os resultados nos testes. Os resultados evidenciaram que a barita, numa proporção de 60%, em relação aos demais componentes da argamassa estudada, para raios-X de aproximadamente 30keV de energia efetiva (93.7 kVp), foi obtido por meio de um fator de conversão de 5.6 da espessura da argamassa para espessura necessária de chumbo. A camada semi-redutora (HVL) da argamassa baritada foi de 1.24mm e a camada semi-redutora (HVL) do chumbo foi de O.22mm. Assim sendo, para cada milímetro de chumbo seria necessário 5.6mm da argamassa de revestimento para uma proteção eficienteAbstract: The present paper has the aim of determine the ideal portion of baryte mineral in plaster and the necessary equivalent thickness of plumbum to absorb or stop x-rays in nearly 30keV effective energy, in isolating odontological clinics. Baryte plaster boards were made at 150x150mm and from 1.4 to 15.1mm of thick. As a radiation source, a GE 100, model A0061 device was used. The incidental and emergent radiadion beams were measured with Lithium Fluoride 700 dosimeter and ionization chamber and Victoreen electrometer models 600-4 and 600 respectively. A theo cal calculus was also done from the plaster compound elements for a testing result comparison. The results highlighted that baryte in 60% portion related to the other studied plaster compounds for x-rays nearly 30keV effective energy (93.7kVp) was obtained through a convertion factor of 5.6 in the plaster thickness for the plumbum necessary thickness. The baryte plaster half-value-layer (HVL) was 1.24mm and the plumbum half-value-layer was 0.22mm. Hence, for each plumbum milimeter it would be necessary 5.6mm of plaster for an efficient protectio
Chunge Niu - One of the best experts on this subject based on the ideXlab platform.
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Flotation studies of fluorite and Barite with sodium petroleum sulfonate and sodium hexametaphosphate
Elsevier, 2019Co-Authors: Zhijie Chen, Zijie Ren, Huimin Gao, Renji Zheng, Yulin Jin, Chunge NiuAbstract:The development of new collectors to separate fluorite from Barite is urgently needed in mineral processing. In this study, the flotation behavior of fluorite and Barite was studied using sodium petroleum sulfonate (SPS) as a collector with sodium hexametaphosphate (SHMP) as a depressant. The performance of reagents on minerals was interpreted by infrared spectroscopic analysis and zeta potential measurement. The flotation results showed that SPS performed well in a wide pH region (7–11) even at a low temperature (5 °C), while the flotability of fluorite and Barite were almost the same. At pH 11, the presence of SHMP obviously depressed fluorite rather than Barite and SHMP exhibited good selective inhibition to fluorite. Fourier-transform infrared spectra and zeta potential results showed that: (1) SPS can adsorb on fluorite and Barite surfaces and (2) SHMP had little effect on the adsorption of SPS on a Barite surface, although it interfered with the adsorption of SPS on a fluorite surface through strong adsorption. Keywords: Fluorite, Barite, Flotation, Sodium petroleum sulfonate, Sodium hexametaphosphat
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flotation studies of fluorite and Barite with sodium petroleum sulfonate and sodium hexametaphosphate
Journal of materials research and technology, 2019Co-Authors: Zhijie Chen, Zijie Ren, Huimin Gao, Renji Zheng, Yulin Jin, Chunge NiuAbstract:Abstract The development of new collectors to separate fluorite from Barite is urgently needed in mineral processing. In this study, the flotation behavior of fluorite and Barite was studied using sodium petroleum sulfonate (SPS) as a collector with sodium hexametaphosphate (SHMP) as a depressant. The performance of reagents on minerals was interpreted by infrared spectroscopic analysis and zeta potential measurement. The flotation results showed that SPS performed well in a wide pH region (7–11) even at a low temperature (5 °C), while the flotability of fluorite and Barite were almost the same. At pH 11, the presence of SHMP obviously depressed fluorite rather than Barite and SHMP exhibited good selective inhibition to fluorite. Fourier-transform infrared spectra and zeta potential results showed that: (1) SPS can adsorb on fluorite and Barite surfaces and (2) SHMP had little effect on the adsorption of SPS on a Barite surface, although it interfered with the adsorption of SPS on a fluorite surface through strong adsorption.
Allen Leigh - One of the best experts on this subject based on the ideXlab platform.
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Precipitation and Growth of Barite within Hydrothermal Vent Deposits from the Endeavour Segment, Juan de Fuca Ridge
DigitalCommons@University of Nebraska - Lincoln, 2016Co-Authors: Jamieson, John William, Hannington, Mark D., Tivey, Margaret K., Hansteen Thor, Williamson, Nicole M.-b., Stewart Margaret, Fietzke Jan, Butterfield David, Frische Matthias, Allen LeighAbstract:Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, Barite (BaSO4) is unique because it requires the direct mixing of Ba-rich hydrothermal fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, Barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of hydrothermal Barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, in order to determine the physical and chemical conditions under which Barite precipitates within seafloor hydrothermal vent systems. Petrographic analyses of 22 Barite-rich samples show a range of Barite crystal morphologies: dendritic and acicular Barite forms near the exterior vent walls, whereas larger bladed and tabular crystals occur within the interior of chimneys. A two component mixing model based on Sr concentrations and 87Sr/86Sr of both seawater and hydrothermal fluid, combined with 87Sr/86Sr data from whole rock and laser-ablation ICP-MS analyses of Barite crystals indicate that Barite precipitates from mixtures containing as low as 17% and as high as 88% hydrothermal fluid component, relative to seawater. Geochemical modelling of the relationship between aqueous species concentrations and degree of fluid mixing indicates that Ba2+ availability is the dominant control on mineral saturation. Observations combined with model results support that dendritic Barite forms from fluids of less than 40% hydrothermal component and with a saturation index greater than ~0.6, whereas more euhedral crystals form at lower levels of supersaturation associated with greater contributions of hydrothermal fluid. Fluid inclusions within Barite indicate formation temperatures of between ~120 ˚C and 240 ˚C during Barite crystallization. The comparison of fluid inclusion formation temperatures to modelled mixing temperatures indicates that conductive cooling of the vent fluid accounts for 60–120 ˚C reduction in fluid temperature. Strontium zonation within individual Barite crystals records fluctuations in the amount of conductive cooling within chimney walls that may result from cyclical oscillations in hydrothermal fluid flux. Barite chemistry and morphology can be used as a reliable indicator for past conditions of mineralization within both extinct seafloor hydrothermal deposits and ancient land-based volcanogenic massive sulfide deposits
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Precipitation and growth of Barite within hydrothermal vent deposits from the Endeavour Segment, Juan de Fuca Ridge
'Elsevier BV', 2015Co-Authors: Jamieson, John W., Hannington, Mark D., Tivey, Margaret K., Hansteen Thor, Williamson, Nicole M.-b., Stewart Margaret, Fietzke Jan, Frische Matthias, Butterfield, David A., Allen LeighAbstract:Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 173 (2016): 64-85, doi:10.1016/j.gca.2015.10.021.Hydrothermal vent deposits form on the seafloor as a result of cooling and mixing of hot hydrothermal fluids with cold seawater. Amongst the major sulfide and sulfate minerals that are preserved at vent sites, Barite (BaSO4) is unique because it requires the direct mixing of Ba-rich hydrothermal fluid with sulfate-rich seawater in order for precipitation to occur. Because of its extremely low solubility, Barite crystals preserve geochemical fingerprints associated with conditions of formation. Here, we present data from petrographic and geochemical analyses of hydrothermal Barite from the Endeavour Segment of the Juan de Fuca Ridge, northeast Pacific Ocean, in order to determine the physical and chemical conditions under which Barite precipitates within seafloor hydrothermal vent systems. Petrographic analyses of 22 Barite-rich samples show a range of Barite crystal morphologies: dendritic and acicular Barite forms near the exterior vent walls, whereas larger bladed and tabular crystals occur within the interior of chimneys. A two component mixing model based on Sr concentrations and 87Sr/86Sr of both seawater and hydrothermal fluid, combined with 87Sr/86Sr data from whole rock and laser-ablation ICP-MS analyses of Barite crystals indicate that Barite precipitates from mixtures containing as low as 17% and as high as 88% hydrothermal fluid component, relative to seawater. Geochemical modelling of the relationship between aqueous species concentrations and degree of fluid mixing indicates that Ba2+ availability is the dominant control on mineral saturation. Observations combined with model results support that dendritic Barite forms from fluids of less than 40% hydrothermal component and with a saturation index greater than ~0.6, whereas more euhedral crystals form at lower levels of supersaturation associated with greater contributions of hydrothermal fluid. Fluid inclusions within Barite indicate formation temperatures of between ~120 and 240°C during Barite crystallization. The comparison of fluid inclusion formation temperatures to modelled mixing temperatures indicates that conductive cooling of the vent fluid accounts for 60 – 120°C reduction in fluid temperature. Strontium zonation within individual Barite crystals records fluctuations in the amount of conductive cooling within chimney walls that may result from cyclical oscillations in hydrothermal fluid flux. Barite chemistry and morphology can be used as a reliable indicator for past conditions of mineralization within both extinct seafloor hydrothermal deposits and ancient land-based volcanogenic massive sulfide deposits.This work was supported by an NSERC PGS scholarship to JWJ and NSERC Discovery Grant to MDH. MKT acknowledges funding from NSF OCE- 1130019. DAB acknowledges funding from NSF OCE-0731947 and the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) under NOAA Cooperative Agreement NA10OAR4320148
Zhiheng Sui - One of the best experts on this subject based on the ideXlab platform.
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origin of the carbonate hosted danaopo zn pb deposit in western hunan province china geology and in situ mineral s pb isotope constraints
Ore Geology Reviews, 2021Co-Authors: Zhilong Huang, Chen Wei, Jun Chen, Mu Yang, Zaifei Yan, Zhiheng SuiAbstract:Abstract The western Hunan-eastern Guizhou (WHEG) Pb-Zn metallogenic belt hosts around 300 carbonate-hosted Pb-Zn deposits (total Pb-Zn metal reserve: >20 Mt), accounting for a major proportion of Pb-Zn resource in China. The origin and ore-forming process of these Pb-Zn deposits are still under debate. The newly-discovered Danaopo Zn-Pb deposit (~150 Mt ore @ 2.58% Zn and 0.48% Pb), which was formed during the Early Devonian orogenic event (~410 Ma), is one of the largest Zn-Pb deposits in the region. In this study, LA-MC-ICP-MS S-Pb isotope analyses were performed on sulfides (pyrite, sphalerite, and galena) and sulfate (Barite) from the Danaopo Zn-Pb deposit. δ34SVCDT values of the diagenetic and late hydrothermal Barites are of +36.5 to +36.9‰ and +27.1 to +28.1‰, respectively. The sulfides δ34SVCDT values (+23.5 to +35.5‰) imply a thermochemical sulfate reduction (TSR) origin from coeval seawater sulfates, as supported also by the dissolution cavities of diagenetic Barite and the nodular and stripe-textured calcite. Furthermore, in-situ sulfide Pb isotopic ratios of different ore-forming stages and altitudes are highly similar: 206Pb/204Pb = 18.144–18.254, 207Pb/204Pb = 15.718–15.797, and 208Pb/204Pb = 38.378–38.605. Such narrow Pb isotopic ranges suggest well-mixing of multiple Pb sources, which likely include the Lower Cambrian Niutitang Fm. (LCNF) black shale, Proterozoic Banxi Group metamorphic basement rocks, and the Lower Cambrian Qingxudong Fm. (LCQF) reef limestone. Considering the deposit geological and S-Pb isotopic features, we suggest that the hydrothermal fluids may have circulated and extracted metals from various sequences in the basin. The fluids then ascended along the Huayuan-Zhangjiajie fault zone and mixed with reduced sulfur-bearing fluids from ore-bearing strata and precipitated the sulfide ores. Mineralization at the Danaopo deposit is thus best classified as Mississippi Valley Type (MVT), which is controlled by the ore-hosting reef limestone and various fault structures.
Strivay David - One of the best experts on this subject based on the ideXlab platform.
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Barite concrete for 252Cf spontaneous neutron shielding based on Monte Carlo computation
2020Co-Authors: Guembou Shouop, Cébastien Joel, Bak Sang-in, Ndontchueng Moyo Maurice, Nguelem, Eric Jilbert, Strivay DavidAbstract:peer reviewedaudience: researcher, professionalRecently, neutron applications as neutron imaging widespread and safety issue related to high neutron penetration is still a concern in neutron industry. Especially, the design of a structure to shield neutron requires structural stability, high-density material, and large fast-neutron removal cross-section while it must be cost-benefit evaluated and using available materials. In this regard, attention has been paid on different Barite composite shielding material and their neutron attenuation property based on the Monte Carlo calculation using Particle and Heavy Ion Transport code System. Different types of material as Barites aggregate, Barites cement, and Barites concrete were investigated to find the most appropriate for fast neutron shielding, especially spontaneous neutron emitted from the Cf-252 source. Preliminary results obtained from the geometry presented in Fig. 1 are displayed in Fig. 2. As the Barite concrete has high density compared to other materials, and high removal cross-section, the dose computation throughout the geometry and in different tallies show that it is the most appropriate neutron shielding in this case. Besides, gamma radiations generated by neutron interaction are easily shielded by Barite concrete. Fast neutron shielding properties obtained by Monte Carlo simulation here are comparable to the experimental value described by William J. Grantham (1961). Barite concrete fast-neutron attenuation good properties were expected as it is the material with the highest removal cross-section among the investigated compound
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Barite concrete for 252Cf spontaneous neutron shielding based on Monte Carlo computation
2020Co-Authors: Guembou Shouop, Cébastien Joel, Bak Sang-in, Ndontchueng Moyo Maurice, Nguelem, Eric Jilbert, Strivay DavidAbstract:Recently, neutron applications as neutron imaging widespread and safety issue related to high neutron penetration is still a concern in neutron industry. Especially, the design of a structure to shield neutron requires structural stability, high-density material, and large fast-neutron removal cross-section while it must be cost-benefit evaluated and using available materials. In this regard, attention has been paid on different Barite composite shielding material and their neutron attenuation property based on the Monte Carlo calculation using Particle and Heavy Ion Transport code System. Different types of material as Barites aggregate, Barites cement, and Barites concrete were investigated to find the most appropriate for fast neutron shielding, especially spontaneous neutron emitted from the Cf-252 source. Preliminary results obtained from the geometry presented in Fig. 1 are displayed in Fig. 2. As the Barite concrete has high density compared to other materials, and high removal cross-section, the dose computation throughout the geometry and in different tallies show that it is the most appropriate neutron shielding in this case. Besides, gamma radiations generated by neutron interaction are easily shielded by Barite concrete. Fast neutron shielding properties obtained by Monte Carlo simulation here are comparable to the experimental value described by William J. Grantham (1961). Barite concrete fast-neutron attenuation good properties were expected as it is the material with the highest removal cross-section among the investigated compoundsPeer reviewe