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    Wyświetlanie 1-8 z 8
    Tytuł:
    Leaching of chalcopyrite concentrate in hydrogen peroxide solution
    Autorzy:
    Agacayak, T.
    Aras, A.
    Aydogan, S.
    Erdemoglu, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/110645.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    chalcopyrite
    dissolution
    hydrogen peroxide
    leaching
    extraction
    Opis:
    The leaching conditions of chalcopyrite (CuFeS2) concentrate in a hydrogen peroxide medium were investigated by studying the effects of its leaching parameters, such as stirring speed, temperature, hydrogen peroxide concentration and the particle size of the concentrate on Cu extraction. It was found that stirring speed has no effect on the leaching. Copper extraction from chalcopyrite is directly proportional to hydrogen peroxide concentration, but the extraction decreases at temperatures above 60°C. The maximum copper extraction was obtained with the following conditions without stirring: 240 min of leaching time, 3.0 M hydrogen peroxide concentration, 40°C leaching temperature and 53-75 m particle size fraction.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2014, 50, 2; 657-666
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanism and leaching kinetics of molybdenite concentrate in a hydrogen peroxide-acid system
    Autorzy:
    Aracena, Alvaro
    Azocar, Alan
    Ibáñez, Juan Patricio
    Jerez, Oscar
    Powiązania:
    https://bibliotekanauki.pl/articles/110193.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    molybdenite concentrate
    hydrogen peroxide
    kinetics
    mechanism of reaction
    Opis:
    The mechanism and leaching kinetics of a molybdenite concentrate in a H2O2-H2SO4 system were studied. The experimental work was performed in a batch reactor equipped with a condenser, a mechanical agitator and a temperature control system. The effects of the temperature, H2O2 and H2SO4 concentrations, particle size, liquid/solid ratio and agitation speed on the Mo recovery were investigated. The thermodynamic results showed that the leaching mechanism it was governed by several intermediate reactions; however, the influences of sulfuric acid and passivation were not observed in the reaction. The most predominant experimental result was the maximum Mo recovery of 81.3% by leaching 64 μm particles at 333 K (60 °C) for 5400 s (90 min). The molybdenum recovery was generally enhanced by increasing the H2O2 and H2SO4 concentrations. However, at H2SO4 concentrations higher than 1.0 mol/dm3, the Mo recovery decreased. Although the agitation speed affected the Mo recovery considerably, high recoveries could be still obtained without mixing. The experimental results and XRD analysis confirmed the reaction mechanisms. The leaching kinetics were analyzed using a shrinking core model in which the rate was controlled by diffusion through a porous layer with radius ro. The reaction rate orders were 1.0 and 0.2 for the H2O2 and H2SO4 concentrations, respectively, and the rate was inversely proportional to the square of the initial particle radius. The calculated activation energy was 75.2 kJ/mol in the temperature range of 278-333 K (5-60 °C).
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 1; 140-152
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New insights into pyrite-hydrogen peroxide interactions during froth flotation: experimental and DFT study
    Autorzy:
    Cao, Qinbo
    Yan, Wenchao
    Wen, Shuming
    Liu, Dianwen
    Li, Yanjun
    Powiązania:
    https://bibliotekanauki.pl/articles/2200334.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    hydrogen peroxide
    oxidization
    pyrite flotation
    adsorption models
    DFT
    Opis:
    Hydrogen peroxide (H2O2) is an efficient depressant for pyrite (FeS2) flotation. However, the depressing mechanism of H2O2 is not fully understood. In this paper, the depressing capacity of H2O2 for pyrite was examined by flotation tests. Results revealed that pyrite flotation could be inhibited by H2O2 at pH 6.4. The pyrite powder in H2O2 solution enhanced the release of O2 from H2O2. However, the O2 concentration in the solution was less than that of H2O2; thus, H2O2 is the major oxidant in the solution. Moreover, density functional theory calculations were performed to study the interactions between H2O2 and hydrated pyrite (100) surface. The H2O2 molecule tended to react with the pyrite surface to generate one S=O bond and an H2O molecule. The possible binding models of O2 molecules on the pyrite (100) surface were also studied for comparison. The O2 dissociation on the pyrite surface was more favorable than the adsorption of O2 as a whole. In addition, the orbital interaction in the S=O bond raised from the reaction of H2O2/O2 with the pyrite surface was also investigated by the density states analysis. These results provide some insights into the oxidizing effect of H2O2 in pyrite flotation.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 157409
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Degradation of toluene using UV/hydrogen peroxide process
    Autorzy:
    Cai, Shaokang
    Sun, Yue
    Gao, Canzhu
    Li, Pengfei
    Cheng, Zhongfa
    Powiązania:
    https://bibliotekanauki.pl/articles/2032937.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    AOP
    toluene
    hydrogen peroxide
    spectrofotometer
    toluen
    nadtlenek wodoru
    spektrofotometria
    Opis:
    Toluene in wastewater is volatile and difficult to degrade, and the longer it stays in the water, the higher is the risk. An advanced oxidation process (AOPs) has been used to degrade toluene rapidly and efficiently in wastewater by using ultraviolet light and hydrogen peroxide. Toluene in solution (initial concentration – 180 mg/dm3) with hydrogen peroxide (H2O2 dose – 2022 mg/dm3) was almost decomposed within 150 min. pH as well as the presence of various ions in waste water did not affect the degradation process. However, under strongly acidic conditions (pH less than 3), the chloride ions reduced the degradation efficiency of toluene. Based on the UV spectrophotometer and GC-MS analyses, the degradation pathways were observed: first, the methyl group was oxidized leading to the generation of benzoic acid, the benzene ring was subsequently opened by the action of hydroxyl radical, followed by the gradual decomposition of the intermediate products into small molecules such as water and carbon dioxide.
    Źródło:
    Environment Protection Engineering; 2021, 47, 1; 5-15
    0324-8828
    Pojawia się w:
    Environment Protection Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of pre-aeration on cyanide leaching of a non-refractory sulphide gold and silver ore
    Autorzy:
    Aydin, B.
    Basturkcu, H.
    Gul, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/951867.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    nonrefractory sulphide gold–silver
    cyanidation
    lead nitrate
    hydrogen peroxide
    aeration
    Opis:
    The leaching behaviour of a sulphide gold-silver ore was investigated in terms of a relationship between gold and silver extractions and cyanide consumption. Ninity five Au % and 88.0% Ag extractions were obtained under the determined conditions of 24 h leaching duration, -74 μm particle size, 40% solids ratio, 4 g/dm3 NaCN concentration, and 450 rpm stirring speed with NaCN consumption of 3.35 g/dm3. Since the NaCN consumption was higher than in industrial applications, Pb(NO3)2 and H2O2 additions and aeration using an air pump were tested during leaching in order to decrease the consumption. While Pb(NO3)2 addition with aeration caused a decrease in the metal extractions, the individual or combined additions of H2O2 and aeration could not provide a reduction in the cyanide consumption. Therefore, the effect of the pre-aeration followed by cyanidation was tested. Eventually, applying 4 h of pre-aeration before a shorter leaching duration of 12 h provided 92.0% Au and 90.5% Ag extractions with a reduced NaCN consumption of 2.44 g/dm3.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 2; 647-660
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Removal of methylene blue by natural and Ca and K-exchanged zeolite treated with hydrogen peroxide
    Autorzy:
    Canli, M.
    Abali, Y.
    Bayca, S. U.
    Powiązania:
    https://bibliotekanauki.pl/articles/109770.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    dye adsorption
    methylene blue
    adsorption
    isotherms
    zeolite
    aluminosilicate
    hydrogen peroxide
    Opis:
    A comparison was made of influence of physically adsorbed methylene blue (MB) dye on the physicochemical properties of Manisa-Akdere zeolite (natural zeolite) and zeolite modified with K and Ca (all samples treated with hydrogen peroxide before modification) using batch adsorption technique. After elementary characterization of this adsorbent, the effects were investigated of initial MB concentration, pH, contact time, stirring rate, adsorbent dosage and temperature on the selectivity and sensitivity of the removal process. A larger adsorption of the dye was observed for modified zeolite (42.7 mg/g) than for natural zeolite (28.6 mg/g) per gram of an adsorbent after all zeolite samples treated with hydrogen peroxide. Zeolite treated with H2O2 showed higher adsorption capacity than untreated zeolite samples. The Langmuir model (R2 values between 0.959 and 0.996) fitted the experimental data better than the Freundlich model (R2 values between 0.804 and 0.988). The adsorption process was found to be slightly influenced by adsorbent dosage, contact time and temperature. Optimum pH for adsorption of MB was found to be at 7. Adsorption equilibrium attained within 30 minutes. The sorption of MB increased slightly with rising temperature. In addition, adsorption values rose with modification Ca-Exchanged (after H2O2 treatment) > K-Exchanged (after H2O2 treatment) > Zeolite treated with H2O2 > Ca-Exchanged >K-Exchanged >Natural Zeolite.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2013, 49, 2; 481-496
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Recovery of copper from copper slag and copper slag flotation tailings by oxidative leaching
    Autorzy:
    Urosevic, D. M.
    Dimitrijevic, M. D.
    Jankovic, Z. D.
    Antic, D. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/109899.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    copper slag
    copper slag flotation tailings
    leaching
    sulphuric acid
    ferric sulphate
    hydrogen peroxide
    Opis:
    Copper smelter slag and copper smelter slag flotation tailings were leached using sulphuric acid solutions, without or with the addition of either ferric sulphate or hydrogen peroxide. Copper extraction from the slag was typically found to be twice as high as that from the slag flotation tailings. Hydrogen peroxide was determined to be the best lixiviant. Thus, copper and iron extractions were 63.4% and 48.6%, respectively, when leaching the slag with 3 M H2O2, after 120 minutes of reaction at room temperature. Copper dissolution was generally found to be the dominant process within the first 60 minutes of reaction, whereas iron dissolution dominated afterwards.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 1; 73-82
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Seasonal variability of antibiotic resistance and biodiversity of tap water bacteria in Wrocław, Poland
    Autorzy:
    Siedlecka, Agata
    Wolf-Baca, Mirela
    Piekarska, Katarzyna
    Powiązania:
    https://bibliotekanauki.pl/articles/208044.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    hydrogen peroxide
    kinetic model
    water
    organic pollutant
    nadtlenek wodoru
    model kinetyczny
    woda
    zanieczyszczenia organiczne
    Opis:
    Antibiotic resistance of bacteria has become a worldwide problem. Drinking water distribution systems (DWDSs) can be regarded as reservoirs of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study aims to provide a preliminary evaluation of seasonal changes in the occurrence of ARB and ARGs in Wrocław tap water samples. It also investigates the biodiversity of bacterial communities dwelling in Wrocław DWDS and compares them with worldwide literature reports. Third generation cephalosporins resistant bacteria were present in each season, with relative abundances reaching from 40.46% in spring to 99.86% in summer. β-lactams and tetracyclines resistant bacteria were present only in spring and autumn samples, with relative abundances reaching from 0.51% to 3.80%. Relative abundances of ARB fluctuated across the year, and no season-dependent trend was found. This suggests that other factors influenced the resistance phenomenon in Wrocław tap water. The investigated resistomes were represented only by several ARGs (qnrB, tetW, ermB,qacEΔ1). Class 1 integrons gene intI1 was also detected. Biodiversity of bacteria collected from large amounts of tap water was similar to that reported previously for Wrocław and worldwide DWDSs, with a prevalence of Proteobacteria, followed by Actinobacteria, Cyanobacteria, and Firmicutes.
    Źródło:
    Environment Protection Engineering; 2020, 46, 2; 93-109
    0324-8828
    Pojawia się w:
    Environment Protection Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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