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    Wyświetlanie 1-8 z 8
    Tytuł:
    Gold leching from a Saudi ore by the nonpolluting thiosulfate process
    Autorzy:
    Mahmoud, M. H. H.
    Awad, H. M.
    Elhabib, O. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/110379.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold
    extraction
    leaching
    thiosulfate
    Saudi ore
    Opis:
    In all working Saudi gold mines, ores are treated using the hazardous cyanidation process. Some Saudi gold ores, such as Al-Amar, is known to be refractory to cyanidation. In this work, we have examined the extraction of gold from Al-Amar gold ore by the much environmentally safer and efficient thiosulfate process. The run of mine (ROM) and carbon-in-leach (CIL) feed, that is obtained after separation of copper concentrate from ROM, samples were found to contain 6.5 and 3.6 ppm gold, respectively. The mineralogical microscopic investigations of ROM samples confirmed that fine gold specks were scattered and encapsulated inside sulfide or quartz base minerals. This could explain the expected reason of the difficult leaching of gold by cyanidation. The X-ray diffraction analysis showed that the CIL feed contained quartz, pyrite, sphalerite and chlorite minerals. After detailed leaching studies of CIL feed, almost 70% of gold could be extracted at 0.2 M ammonium thiosulfate and 0.3 M ammonium hydroxide after 24 h. Addition of copper(II) as <0.2 mM only slightly enhanced the gold leaching in the ammoniacal thiosulfate solution. Gold leaching drastically decreased as the concentration of copper(II) increased 0.2 mM due to the degradation of S2O3²¯.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 1; 59-72
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Geochemical characters of the Gabbroic Rocks in ophiolite sequences of north Hatta area, United Arab Emirates
    Autorzy:
    El Tokhi, M.
    El Din Mahmoud Amin, B.
    Arman, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1070383.pdf
    Data publikacji:
    2016-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    91.62.Rt
    92.20.Ny
    Opis:
    The ophiolite sequences of UAE, as a part of Oman ophiolite, represent both, mantle section and crustal section. The crustal part of the ophiolite sequences, consists of a layered series (cumulate peridotites and gabbros). This paper aims to overview geochemical character and some mechanical and physical features of the gabbroic rocks. The gabbros comprise troctolite, olivine gabbro, normal gabbro, gabbronorite, and uralitized gabbros. Geochemical features indicate that they are tholeiitic and are formed in an arc-related tectonic setting. On NMORB normalized pattern of gabbros, the HFS-elements (P, Zr, Sm, Ti, and Y) show a flat pattern parallel to NMORB. In contrast, the LIL-elements (Rb, Ba, Th, Sr) are relatively more enriched than NMORB. The enrichment of LIL-elements over the HFS-elements and the depletion of Nb relative to other HFS-elements suggest involvement of subduction component in the depleted mantle source, and suggest that these rocks were formed in a supra-subduction zone tectonic setting.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 1; 17-22
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microanalysis study of Al-Amar rock and leaching behavior of its tailings for recovery of gold and silver
    Autorzy:
    Mahmoud, M. H. H.
    Awad, H. M.
    Altalhi, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/109620.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold
    silver
    tailings
    mineralogy
    extraction
    thiosulfate
    Opis:
    Some Saudi gold ores, such as that at Al-Amar mine, suffer from low leaching efficiency using the toxic cyanidation process. Only about 60% of the gold and 26% of the silver in the feed ore can be extracted at 0.2% CN– after 24 h and the rest percentages of these metals remained in leaching residues (tailings). These tailings contained 1.1 ppm Au and 4.3 ppm Ag. Reprocessing of tailings serves both for economic and environmental reasons. A petrography analysis of the mineral constituents indicated that the rock samples consisted primarily of sphalerite, chalcopyrite, pyrite and galena in decreasing order of abundance. An electron probe microanalysis quantitatively showed that gold and silver were finely distributed in the grain boundaries and within sphalerite, chalcopyrite, pyrite, and quartz. The dissemination of gold and silver in these hard minerals may be the main reason for their low recovery by cyanidation. Open air roasting of the tailings can release amounts of the disseminated gold and silver which can be extracted during leaching with the harmless thiosulfate ion S2O32–. After studying the different parameters, we found that the maximum possible extraction of gold and silver from the tailings roasted for 2 h at 400°C reached about 50% at 0.2 M ammonium thiosulfate, 0.3 M ammonium hydroxide, solid–liquid ratio ½ for 24 h. These achievements represent a possible exploitation of the accumulated 1.65 million Mg tailing waste containing significant amounts of gold and silver valued at about $73 million.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 2; 527-537
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improved recovery of gold and silver from thiosulfate solution on activated carbon in presence of ammonium persulfate
    Autorzy:
    Mahmoud, Mohamed H. H.
    Awad, Hesham M.
    Powiązania:
    https://bibliotekanauki.pl/articles/110611.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    activated carbon
    adsorption
    gold
    silver
    thiosulfate
    ammonium persulfate
    Opis:
    Thiosulfate (TS) process for extraction of gold and silver is a promising alternative to the highly toxic cyanidation process. One of the main reasons caused limiting the practical application of the TS process is the poor recovery of gold and silver on the commonly used activated carbon (AC). Increasing amounts of TS ions greatly inhibited the adsorption of gold and silver from synthetic solutions. No adsorption was obtained when the TS concentration reached 0.8 M after 5 h. The adsorption efficiency from real leach liquor initially contained 0.2 M TS was as low as 40-50%, after a long time of 15 hours. We have suggested that the removal of the residual TS ions in leach liquor through an interaction with an oxidizing agent such as ammonium persulfate (APS) would improve the adsorption of gold and silver on AC. Increasing the APS concentrations from 0.0 M to 0.01 M drastically improved the gold adsorption efficiency from 5% to 85% after only 10 min. Almost 95% of both metals was adsorbed after 90 min. EDXRF chart confirmed the adsorption of gold and silver on AC. A process flowsheet was proposed for an integrated TS leaching and recovery of gold and silver from Al Amar tailing including adsorption on AC in presence of APS.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 5; 1271-1285
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physicochemical properties of pseudobrookite Fe2TiO5 synthesized from ilmenite ore by co-precipitation route
    Autorzy:
    Mahmoud, Mohamed H. H.
    Hessien, Mahmoud M.
    Alhadhrami, Abdulrahman
    Gobouri, Adel A.
    Powiązania:
    https://bibliotekanauki.pl/articles/109822.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    ilmenite ore
    pseudobrookite
    Co-precipitation
    nanocrystalline
    magnetic properties
    Opis:
    Pseudobrookite (Fe2TiO5) is a semiconductor with numerous potential applications. Low-grade ilmenite ore has been used as an inexpensive source of Fe and Ti for preparation of Pseudobrookite. Ilmenite was first leached with 20% hydrochloric acid for 3 h at 70°C. Co-precipitation of soluble Fe and Ti from the rich filtrate was carried out at pH ≥ 9.1 followed by calcination at different temperatures (900-1300oC) for 2 h. X-ray diffraction patterns (XRD) showed that a single-phase nanocrystalline pseudobrookite powder was produced. The pH was a critical parameter for the evolution of formation the different sizes, structural morphology, and the magnetic properties of the product. Scanning electron microscope (SEM) images showed that particles synthesized at pH 11.2 contained more agglomerations and were more porous than those synthesized at pH 9.1. As the calcination temperature increases, the Fe2TiO5 changes from a small rod-like structure to an elongated rod-like structure, and finally to interconnected aggregated crystals. The magnetization of the synthesized Fe2TiO5 was measured using a vibrating sample magnetometer (VSM) and was found steadily increase with increasing calcination temperature from 1000 (≈9 emu/g) to 1300°C (16 emu/g). Such a large saturation of magnetization might be due to the high phase purity and well-defined crystallinity of Fe2TiO5.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 1; 290-300
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A two-stage stochastic programming approach for production planning system with seasonal demand
    Autorzy:
    Mahmoud, Asmaa A.
    Aly, Mohamed F.
    Mohib, Ahmed M.
    Afefy, Islam H.
    Powiązania:
    https://bibliotekanauki.pl/articles/952860.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    process manufacturing system
    two-stage stochastic programming
    sampling average approximation
    Opis:
    Seasonality is a function of a time series in which the data experiences regular and predictable changes that repeat each calendar year. Two-stage stochastic programming model for real industrial systems at the case of a seasonal demand is presented. Sampling average approximation (SAA) method was applied to solve a stochastic model which gave a productive structure for distinguishing and statistically testing a different production plan. Lingo tool is developed to obtain the optimal solution for the proposed model which is validated by Math works Matlab. The actual data of the industrial system; from the General Manufacturing Company, was applied to examine the proposed model. Seasonal future demand is then estimated using the multiplicative seasonal method, the effect of seasonality was presented and discussed. One might say that the proposed model is viewed as a moderately accurate tool for industrial systems in case of seasonal demand. The current research may be considered a significant tool in case of seasonal demand. To illustrate the applicability of the proposed model a numerical example is solved using the proposed technique. ANOVA analysis is applied using MINITAB 17 statistical software to validate the obtained results.
    Źródło:
    Management and Production Engineering Review; 2020, 11, 1; 31--42
    2080-8208
    2082-1344
    Pojawia się w:
    Management and Production Engineering Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of probiotic and yeast culture supplementation on selected biochemical and immunological parameters of growing lambs
    Autorzy:
    Mahmoud, M.M.
    Youssef, I.M.I.
    Abd El-Tawab, M.M.
    Bakr, H.A.
    Eissa, N.A.
    Hassan, M.S.
    Giadinis, N.D.
    Milewski, S.
    Baumgartner, W.
    Sobiech, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/2087359.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lambs
    probiotic
    yeast culture
    Saccharomyces cerevisiae
    immunoglobulins
    Źródło:
    Polish Journal of Veterinary Sciences; 2020, 23, 1; 5-12
    1505-1773
    Pojawia się w:
    Polish Journal of Veterinary Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Plants take action to mitigate salt stress: Ask microbe for help, phytohormones, and genetic approaches
    Autorzy:
    Hewedy, Omar A.
    Mahmoud, Ghada Abd-Elmonse
    Elshafey, Naglaa F.
    Khamis, Galal
    Karkour, Ali M.
    Abdel Lateif, Khalid S.
    Amin, Basma H.
    Chiab, Nour
    El-Taher, Ahmed M.
    Elsheery, Nabil I.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174285.pdf
    Data publikacji:
    2022
    Wydawca:
    Instytut Technologiczno-Przyrodniczy
    Tematy:
    Bacillus
    ion homeostasis
    osmoprotectants
    osmotic stress
    photosynthesis
    ROS scavenging
    Opis:
    Global agriculture is a pivotal activity performed by various communities worldwide to produce essential human food needs. Plant productivity is limited by several factors, such as salinity, water scarcity, and heat stress. Salinity significantly causes short or long-term impacts on the plant photosynthesis mechanisms by reducing the photosynthetic rate of CO2 assimilation and limiting the stomatal conductance. Moreover, disturbing the plant water status imbalance causes plant growth inhibition. Up-regulation of several plant phytohormones occurs in response to increasing soil salt concentration. In addition, there are different physiological and biochemical mechanisms of salt tolerance, including ion transport, uptake, homeostasis, synthesis of antioxidant enzymes, and osmoprotectants. Besides that, microorganisms proved their ability to increase plant tolerance, Bacillus spp. represents the dominant bacteria of the rhizosphere zone, characterised as harmless microbes with extraordinary abilities to synthesise many chemical compounds to support plants in confronting salinity stress. In addition, applying arbuscular mycorrhizal fungi (AMF) is a promising method to decrease salinity-induced plant damage as it could enhance the growth rate relative to water content. In addition, there is a demand to search for new salt-tolerant crops with more yield and adaptation to unfavourable environmental conditions. The negative impact of salinity on plant growth and productivity, photosynthesis, stomatal conductance, and changes in plant phytohormones biosynthesis, including abscisic acid and salicylic acid, jasmonic acid, ethylene, cytokinins, gibberellins, and brassinosteroids was discussed in this review. The mechanisms evolved to adapt and/or survive the plants, including ion homeostasis, antioxidants, and osmoprotectants biosynthesis, and the microbial mitigate salt stress. In addition, there are modern approaches to apply innovative methods to modify plants to tolerate salinity, especially in the essential crops producing probable yield with a notable result for further optimisation and investigations.
    Źródło:
    Journal of Water and Land Development; 2022, 55; 1--16
    1429-7426
    2083-4535
    Pojawia się w:
    Journal of Water and Land Development
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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