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    Wyświetlanie 1-6 z 6
    Tytuł:
    Kinetics study and reaction mechanism for titanium dissolution from rutile ores and concentrates using sulfuric acid solutions
    Autorzy:
    Ismael, Mohamed H.
    Mohammed, Hesham S.
    El Hussaini, Omneya M.
    El-Shahat, Mohamed F.
    Powiązania:
    https://bibliotekanauki.pl/articles/2146851.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    leaching kinetics
    leaching mechanism
    titanium
    rutile concentrate
    leaching design
    shrinking
    core model
    Opis:
    Recent developments of acid leaching of titanium concentrates and ores have produced renewed industrial and commercial interest. However, the leaching kinetics and mechanism of these concentrates and ores had received little attention. This work, therefore, addresses the leaching kinetics and mechanism of Ti from a rutile concentrate in sulfuric acid solution. The leaching reaction was controlled by diverse parameters like temperature, particle size, acid concentration, liquid/solid (L/S) ratio, and stirring speed. The leaching kinetics was investigated using the Shrinking Core Model in order to determine the optimum criteria which control the reaction. The kinetics analysis showed that the rate of dissolution of Ti increased by increasing reaction temperature, L/S ratio, and stirring speed, while it decreased upon increasing particle size. The kinetics analysis revealed that the dissolution reaction is controlled by the chemical reaction at the rutile particle surface. Applying the Arrhenius relation, the apparent energy of activation Ea for the leaching reaction was calculated to be 23.4kJ/mol. A semi-empirical overall rate equation was introduced to describe the combined effects of the process variables upon the rate of the dissolution reaction: 〖1-(1-x)〗^(1/3)=k_0 〖 C〗_([H2SO4])^0.803 〖 (dp)〗^(-0.518) 〖(L/S)〗^0.793 〖(w)〗^0.668 e^((-23400/RT)) t
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 1; 138--148
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pressure oxidation of pyrite-arsenopyrite refractory gold concentrate
    Autorzy:
    Rusanen, L.
    Aromaa, J.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/110051.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold ore
    hydrometallurgy
    leaching
    factorial design
    Opis:
    Refractory gold ores have poor gold recoveries with direct cyanide leaching. Typically the refractoriness is due to encapsulation of the gold particles inside the host mineral. To liberate gold for leaching the host mineral must be broken by mechanical or chemical means. The aim of this study was to study the effect of temperature, oxygen partial pressure and slurry density on pressure oxidation of pyrite-arsenopyrite gold concentrate. Batch oxidation tests in an autoclave were done using a factorial design. Different responses were measured and analysed to study effect of the three factors and oxidation kinet-ics. Generally, high slurry density required high temperature and oxygen partial pressure to reach com-plete oxidation. Oxidation kinetics at 225°C temperature, with 1050 kPa oxygen partial pressure and 15% slurry density was found to be fastest resulting in complete conversion of sulfides in 30 minutes. At 195°C, 700 kPa oxygen partial pressure and 10% slurry density, the oxidation kinetics for complete sul-fide conversion was about 60 minutes. Slurry densities above 10% had an adverse effect on the oxidation rate, when the temperature was below 225°C and oxygen partial pressure below 1050 kPa.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2013, 49, 1; 101-109
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Extraction and optimization of Mucuna pruriens for dyeing of leather
    Autorzy:
    Sundari, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/779092.pdf
    Data publikacji:
    2015
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    leaching
    Mucuna pruriens
    extraction
    Box-Behnken design
    dyeing of leather
    Opis:
    The present study reports on the leaching of natural pigment from Mucuna pruriens for dyeing of chrome tanned leather samples. The experiments were performed at temperature (30-70°C), time (30-90 min), feed to solvent ratio (1:3-1:7) and particle size (0.25-0.75 mm) using ethanol as solvent. The influence of process variables on percentage yield has been studied and the conditions were optimized using Box-Behnken design. The optimized conditions for intensified extraction was found to occur at a temperature of 60°C, extraction time of 1 hr, for a feed to solvent ratio of 1:5 and 0.75 mm particle size. The % yield under optimized conditions was found to be 47%. The extraction results were found to agree well with the statistical model (R2 = 0.9740). The colouring ability of extracted dye has been tested on wet blue goat leathers. The dyed leather exhibited a better colour value, strength and fastness properties as inferred from reflectance and visual assessment tests.
    Źródło:
    Polish Journal of Chemical Technology; 2015, 17, 2; 57-63
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Parametric optimization of coal desulfurization through Alkaline leaching
    Autorzy:
    Rehman, F.
    Ahmad, S. W.
    Zafar, M. S.
    Ahmad, S.
    Zia-Ul-Haq, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/779964.pdf
    Data publikacji:
    2018
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Desulfurization
    Alkaline leaching
    Response surface methodology
    ANOVA
    Central Composite design
    Opis:
    Desulfurization of Pakistani coal has been carried out through alkaline leaching. During present experimental investigation, the effect of operating parameters like alkali concentration, time, temperature and particle size has also been analyzed, graphically represented and critically discussed. Parametric optimization of leaching process has been carried out by using response surface methodology (RSM) based on central composite design (CCD). The analysis of variance (ANOVA) was performed in order to assess the highest level interactions of variables and three way interactions were observed significant. Further, the optimum value of total sulfur removal was observed as 53% when the operatic conditions fixed at 10% W/V, 60 min, 80°C and 140 mesh for alkaline concentration, leaching time, temperature and particle size, respectively.
    Źródło:
    Polish Journal of Chemical Technology; 2018, 20, 3; 103-109
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pressure acid leaching of sphalerite concentrate. Modeling and optimization by response surface methodology
    Autorzy:
    Guler, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/110475.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    pressure leaching
    sphalerite concentrate
    optimization
    response surface methodology
    central composite rotatable design
    Opis:
    The zinc leaching from sphalerite concentrate using oxygen under pressure in sulfuric acid solution was primarily studied and evaluated. The effects of important leaching parameters such as oxygen partial pressure, temperature, solid/liquid ratio and leaching time on leaching efficiency, Zn concentration and Fe extraction were investigated. Response surface methodology based on central composite rotatable design technique was used to optimize the leaching process parameters in order to obtain a suitable leach solution with high Zn leaching efficiency considering further processes such as precipitation of contaminating metal ions and electrolysis. The optimum leaching condition for maximum Zn leaching efficiency and Zn concentration with minimum Fe extraction was determined as follows: oxygen partial pressure of 12 bars, temperature of 150 °C, solid/liquid ratio of 0.20 and leaching time of 89.16 minutes. The achieved experimental results for Zn leaching efficiency, Zn concentration and Fe extraction under the optimum conditions were as 94%, 80 g/dm3 and 8.1% respectively. The experimental results corresponded well with the predicted results of quadratic polynomial models.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2016, 52, 1; 479-496
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Recovery of vanadium and tungsten from spent selective catalytic reduction catalyst by alkaline pressure leaching
    Autorzy:
    Liu, Nana
    Xu, Xinyang
    Liu, Yuan
    Powiązania:
    https://bibliotekanauki.pl/articles/110694.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    spent SCR catalyst
    alkaline pressure leaching
    response surface method
    Box-Behnken design
    Opis:
    Improving the efficiency of precious metal recovery from spent Selective Catalytic Reduction (SCR) catalyst provides economic benefits and promises sustainable use of resources. Here we demonstrate highly efficient alkaline pressure leaching method for the extraction of vanadium (V) and tungsten (W) from spent SCR catalyst. We analyzed the effects of experimental parameters such as the stirring speed, leaching agent concentration, leaching temperature, liquid-to-solid ratio, and leaching time. The Box-Behnken design of experiments and the response surface methodology have been employed to understand the impact of the leaching parameters and the impact of their interactions on the leaching rate of V and W. The results showed that the leaching agent concentration significantly promoted the recovery of V and W; the influence of the reaction temperature and leaching time moderately increased the leaching rate of the metals. Moreover, the efficiency of the alkaline pressure leaching technique was determined by the interactions between leaching time and reaction temperature, and the relationships between reaction temperature and leaching agent concentration. By using the response surface methodology, the optimal leaching conditions were found that the leaching agent concentration was 4.75 molL-1, the leaching temperature was 190 °C, and the reaction time was 44.5 min, and the predicted values of V and W leaching rates were 95.76% and 98.36%, respectively. Based on the excellent fitting between modeling and experimental results demonstrated in this work, we conclude that our study can shed light on the development of highly efficient and sustainable metal recovery strategies for practical applications.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 3; 407-420
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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