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Wyświetlanie 1-5 z 5
Tytuł:
Effective parameters on generation of nanobubbles by cavitation method for froth flotation applications
Autorzy:
Pourkarimi, Z.
Rezai, B.
Noaparast, N.
Powiązania:
https://bibliotekanauki.pl/articles/110607.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
nanobubbles
cavitation
venturi
laser particle size analyzer
Opis:
The significant recovery increase in flotation of fine particles using nanobubbles has been one of the major topics in flotation science in recent years. Fine bubbles have an important effect on gas hold-up, which is necessary in froth flotation of minerals based on the process industries. At a given gas hold-up, using finer bubbles can reduce frother consumption. An exclusive nanobubble generation system has been developed in Iran Mineral Processing Research Center (IMPRC) to evaluate the effect of nanobubbles on the froth flotation performance. This device, which enhanced venturi tubes, works according to cavitation phenomena. The venturi tube is the most widely used hydrodynamic cavitation device, in which liquid flow increases in the conical convergent zone of the tube due to the thin diameter. The liquid in the cylindrical throat is higher in a flow velocity and lower in a pressure than the liquid in the entrance cylinder, which results in cavitation. In this research work, various factors such as the frother type and dosage, pH, compressed air flow, pressure in cavitation nozzle, gas types, temperature and venturi tube internal diameter were studied. For this purpose, a five-level central composite experimental design was used to check the influence of four important parameters on the median size and volume of nanobubbles. Online measurement of the bubbles size was implemented by a laser particle size analyzer (LPSA), according to standard BS ISO 13320-09. Due to the above parameters and obtained responses, the analysis of variance (ANOVA) was conducted with a suitable model to optimize the conditions, with the aim of minimizing the size of air bubbles. The optimal conditions were: frother (MIBC) dosage of 75.8 mg/dm3, air flow rate of 0.28 dm3/min, pressure of 324 kPa and pH of 9.5. The median bubble size d50 was equal to 203 nm. To validate the results, a test under optimum conditions was performed and the obtained results indicated that there was a good fit at the confidence interval of 95% and reflected the repeatability of the process.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 920-942
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research of nanobubbles enhanced reverse anionic flotation of a midlow grade phosphate ore
Autorzy:
Zhang, Tiebin
Zhang, Qin
Powiązania:
https://bibliotekanauki.pl/articles/2146853.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
nanobubbles
reverse anionic flotation
phosphate ore
dolomite
particle aggregation
Opis:
The reverse anionic flotation is commonly used to upgrade the mid-low grade phosphate ore in China. The mineral characterization of raw ore shows that carbonate and phosphate minerals combined with fine intergrowth, difficulty in upgrading. Flotation using nanobubbles (NBs) can significantly enhance the flotation efficiency of fine particles of minerals. To research the effect of NBs on the flotation process of this phosphate ore, two flotation tests with and without NBs were compared. The results show that the MgO removal had an increment of 10% in the case of NBs flotation versus conventional flotation in the approximate grade and recovery of P2O5. The foam product of NBs flotation had smaller dimensions than the conventional flotation. NBs enhanced the contact angle on dolomite surface from 45.8 ° to 64.5 °, and increases the d50 of dolomite from 20.49 µm to 30.43 µm.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 1; 113--125
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of dissolved air on bubble attachment to highly oriented pyrolytic graphite
Autorzy:
Krasowska, M.
Sellapperumage, P. M. F.
Ralston, J.
Beattie, D. A.
Powiązania:
https://bibliotekanauki.pl/articles/110554.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bubble attachment
hydrophobic surface
van der Waals interaction
nanobubbles
dissolved air
Opis:
The effect of air, dissolved in 0.1 M KCl solution, on bubble attachment to the smooth hydrophobic surface of highly oriented pyrolytic graphite was studied. The stability of a wetting film in such a system is governed by surface forces, i.e. electrostatic and van der Waals interactions. At the high ionic strength investigated, the electric double layer forces are both weak and of short range, therefore the stability of the wetting film is dominated by van der Waals interactions. The Hamaker coefficient for the highly oriented pyrolytic graphite-KCl aqueous solution-air system is negative and hence van der Waals interactions are repulsive. A repulsive force should stabilize the wetting film, preventing its rupture and bubble attachment to the highly oriented pyrolytic graphite surface. Many experimental studies have found that wetting films are not stable at graphite or coal surfaces, and air bubbles attach. In the present experiments, the stability of the wetting films decreased with increasing amount of dissolved air. The time required for film drainage, rupture, and air bubble attachment was shortened by two orders of magnitude when the experiments were performed in air saturated 0.1 M KCl solution. This instability was attributed to an increasing number of nano- and submicron- bubbles nucleated at the graphite surface. The Hamaker coefficient across the air-KCl aqueous solution-air system is positive and hence van der Waals interactions are attractive, resulting in wetting film rupture and macroscopic air bubble attachment to a highly oriented pyrolytic graphite surface decorated with resident nano- and submicro-metre bubbles.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 1; 163-173
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of effective parameters on generating submicron (nano)-bubbles using the hydrodynamic cavitation
Autorzy:
Nazari, Sabereh
Shafaei, Sied Ziaedin
Hassanzadeh, Ahmad
Azizi, Asghar
Gharabaghi, Mahdi
Ahmadi, Rahman
Shahbazi, Behzad
Powiązania:
https://bibliotekanauki.pl/articles/1845212.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coarse quartz particles
bulk nanobubbles (NBs)
fractional factorial design
frother type
temperature
Opis:
Although submicron (nano)-bubbles (NBs) have been broadly used in the laboratory flotation processes, the role of critical factors in their generation is not adequately explored in the literature. The present study investigates the effect of six key factors on generating submicron-sized bubbles and its application to coarse-sized quartz flotation. Interaction of influential factors is highlighted, which was generally overlooked in previous studies. These parameters i.e. frother type (MIBC and A65), frother dosage (50-130 mg/L), air flow rate (0.1-0.4 L/min), pressure in Venturi tube (250-400 kPa), liquid temperature (22-42 °C) and pH (6-10) were evaluated through software based statistical fractional factorial design. The size distribution of NBs produced by the principle of hydrodynamic cavitation was measured using a laser particle size analyzer (LPSA), and Sauter mean bubble diameter (d32) was considered as the response of experimental design. Batch flotation experiments were performed with and without the A65 and MIBC-NBs. The results of experimental design showed that relative intensity of the main factors followed the order of air flow rate>temperature>frother type as the most effective parameters on the bubble size. It was revealed that the lowest air flow rate (0.1 L/min) produced the smallest bubbles. Meanwhile, the d32 decreased as the liquid temperature increased, and the bubble size strongly was related to the frother type and its concentration. Indeed, with changing frother from MIBC to A65, the reduction in mean bubble size was two-fold. Interaction of frother type with its dosage, air flow rate and pressure were statistically recognized significant on the mean bubble size, which was confirmed by p-values. Finally, flotation recovery of quartz particles improved ca. 22% in the presence of NBs compared to the conventional flotation.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 5; 884-904
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanobubbles effect on the mechanical flotation of phosphate ore fine particles
Autorzy:
Pourkarimi, Z.
Rezai, B.
Noaparast, M.
Powiązania:
https://bibliotekanauki.pl/articles/110797.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
fine particles
phosphate
nanobubbles
hydrodynamic cavitation
Venturi
LPSA
Flo-Y-S
Opis:
Froth flotation is one of the main methods for processing of phosphate ores. However, flotation of fine particles, especially phosphate ores, has always been one of the fundamental problems. For example, about 10% of Esfordi phosphate processing plant ore with a grade of more than 16% P2O5 and d80 of less than 30 μm is sent to the tailing dam. Flotation using nanobubbles generated by hydrodynamic cavitation is one of the latest industrial techniques to recycle fine particles of minerals. A significant recovery increment in flotation of fine particles using nanobubbles has been one of the main topics of flotation science in recent years. Fine bubbles have important effects on the gas holdup, which is necessary in the froth flotation cell of mineral based process industries. At a given gas holdup, using finer bubbles can reduce frother consumption. An exclusive nanobubble generation system has been developed at Iran Mineral Processing Research Center (IMPRC) for evaluating the effect of nanobubbles on froth flotation. This device enhances venturi tubes and works based on cavitation phenomena. In this study, a comparison of conventional flotation and nanobubble enhanced flotation in mechanical cells was carried out on two types of phosphate ore samples. As a result, the flotation recovery had a significant increment of more than 30% in the case of using nanobubbles versus conventional flotation in the same grade of P2O5.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 278-292
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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