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    Wyświetlanie 1-4 z 4
    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:
    Study on leaching kinetics of laterite ore using hydrochloric acid
    Autorzy:
    Li, Jinhui
    Xu, Zhifeng
    Wang, Ruixiang
    Gao, Yang
    Yang, Yang
    Powiązania:
    https://bibliotekanauki.pl/articles/110911.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    nickel laterite
    hydrochloride acid
    kinetics analysis
    hydrometallurgy
    leaching mechanism
    Opis:
    The process of atmosphere-pressure acid leaching of laterites has attracted considerable attention in the nickel industry in recent years. However, the leaching kinetics of laterite using hydrochloride acid has not yet been fully researched. In this paper, the mineral analysis of the ore was carried out, and the leaching mechanism of different minerals at different time was studied comprehensively. The kinetics analysis of the leaching process of nickel, cobalt and manganese showed that the kinetics model of diffusion controlling was suitable and could be described by the linear equation, 1-3(1-a)2/3+2(1-a)=k2t. Based on the linear equation and the Arrhenius equation, the values of activation energy of metal leaching can be deduced (11.56 kJ/mol for nickel, 11.26 kJ/mol for cobalt and 10.77 kJ/mol for manganese). Study of leaching mechanism shows that the order of these minerals dissolution is: goethite, lizardite, magnetite and hematite. Due to the original or product of silica, magnetite, hematite and talc, they can form the solid film which hinders the leaching of valuable metals. Thus, the diffusion controlling step is inner diffusion, namely solid film diffusion controlling.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 3; 711-720
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Immobilization of Cadmium from Contaminated Sediment Using Cardboard Mill Sludge
    Autorzy:
    Prica, M.
    Dalmacija, M.
    Dalmacija, B.
    Pesic, V.
    Krcmar, D.
    Becelic, M.
    Milosevic, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/204907.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    zanieczyszczenia osadów
    kadm
    rekultywacja
    stabilizacja
    mechanizm ługowania
    contaminated sediment
    cadmium
    remediation
    stabilization
    cardboard mill sludge
    leaching mechanism
    leaching test
    Opis:
    Sludge from cardboard mill is most commonly landfilled, but it could also be recycled on-site into production or reused in some other way. In this study the use of sludge from cardboard mill as stabilizing agent in the stabilization treatment of cadmium polluted sediment was examined. The effectiveness of treatment and long-term leaching behavior of cadmium was evaluated by determining the cumulative percentage of cadmium leached, diffusion coefficients (De) and by applying different leaching tests (semi-dynamic test, toxicity characteristic leaching procedure, waste extraction test). In order to simulate the “worst case” leaching conditions, the semi-dynamic leaching test was modified using 0.014 M acetic acid (pH = 3.25) and humic acids solution (20 mg l-1 TOC) as leachants instead of deionized water. A diffusion-based model was used to elucidate the controlling leaching mechanisms. Applied treatment was effective in immobilizing cadmium irrespective of high availability in the untreated sample. The controlling leaching mechanism appeared to be diffusion, which indicates that a slow leaching of cadmium could be expected when the cardboard mill sludge as stabilization agent is applied.
    Źródło:
    Archives of Environmental Protection; 2012, 38, 4; 109-118
    2083-4772
    2083-4810
    Pojawia się w:
    Archives of Environmental Protection
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Seepage mechanism during in-situ leaching process of weathered crust elution-deposited rare earth ores with magnesium salt
    Autorzy:
    Liu, Defeng
    Zhang, Zhenyue
    Chi, Ruan
    Powiązania:
    https://bibliotekanauki.pl/articles/110849.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    seepage mechanism
    weathered crust elution-deposited rare earth ores
    in-situ leaching
    magnesium salt
    Opis:
    To reveal seepage mechanism during in-situ leaching process of weathered crust elution deposited rare earth ores with magnesium salt, the effects of particle gradation, particle migration, Atterberg limit on the permeability coefficient were investigated, and the relation between the particle size and rare earth content was discussed. The results showed that the ore in the humic layer (HL) with high porosity and permeability was uniformly graded particles. The ore in the completely weathered layer (CWL) with low porosity and permeability belonged to dense-graded particles. The ore in the partly weathered layer (PWL) was open-graded particles, whose permeability fell in between the HL and the PWL. The change of -0.075mm particles content was the largest in the leaching process. When - 0.075mm particle content was less than 30%, the migration ability of fine particles and the permeability coefficient decreased gradually. On the contrary, the migration ability of fine particles gradually remained stable, and the change in the permeability coefficient was not obvious. The liquid limit (LL) in the Atterberg limit of HL, CWL and PWL was inversely proportional to the permeability coefficient, and followed the order: LLHL < LLPWL < LLCWL. With the -0.075mm particle content increasing, the LL of the ore samples increased gradually and finally tended to be stable. The peak value of rare earth concentration appeared earlier and the rare earth content decreased gradually with the increase of the ore particle size. This work provided a theoretical basis for achieving high-efficient mining of weathered crust elution-deposited rare earth ores.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 2; 350-362
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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