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1
Content available Current status of research on nanobubbles in particle flotation
Chen Jian, Chen Jun, Cheng Yali
Physicochemical Problems of Mineral Processing
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2024
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Vol. 60, iss. 1
art. no. 183613
EN
Froth flotation, as one of the most widely used separation approaches in mineral processing, is commonly used to recover valuable components from minerals. However, maintaining high flotation efficiencies is a serious challenge for conventional froth flotation in the face of decreasing particle size of the minerals to be sorted. To date, there have been plenty of reports on the software of nano-bubbles (NBS) in flotation, and the experimental consequences show that nano-bubbles' introduction has given rise to improvement's different grades in the recovery of varieties of minerals, which highlights the great potential of nano-bubbles for mineral flotation. Nanobubbles have smaller bubble radii and unusually high stability compared to conventional flotation bubbles, and their related behavior in flotation has been a hot research topic. This paper reviews some of the methods of preparing nanobubbles, equipment techniques for characterizing nanobubbles, factors affecting their stability, and some of the popular doctrines. In particular, the reinforcing mechanism of nanobubbles in the particle flotation process is discussed, first, the nanobubbles improve the electrostatic attractiveness with the particles by achieving the charge inversion while the nanobubbles that was adsorbed on the particles' surface will cover a share of the charge, which decreases the electrostatic repulsive force between the particles; and second, the nanobubbles can act as a bridge between the surfaces of the two particles, which advances the agglomeration between the particles. This review aims to be able to further advance the research related to the industrialization of nanobubbles.
2
Content available Study of flocculation performance and mechanism of ultrafine montmorillonite particles with NPAM
Wang Lujun, Min Fanfei, Chen Jun, Wang Ting, Zhou Zhuang
Physicochemical Problems of Mineral Processing
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2022
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Vol. 58, iss. 3
art. no. 147790
EN
Ultrafine montmorillonite particles are the main clay minerals in industrial wastewater. In order to explore the flocculation performance and mechanism of flocculant with montmorillonite, the effects of nonionic polyacrylamide (NPAM) dosage and molecular weight on flocculation effect were studied using a flocculation sedimentation experiment. The morphology of flocs was observed by metallographic microscope and scanning electron microscope, and the microscopic adsorption mechanism was studied utilizing density functional theory (DFT). The results show that the best reagent system for the montmorillonite sample is that the molecular weight of NPAM is 14 million and the added amount is 100 g/t. The floc size increases with rising NPAM dosage, forming a unique multi-level compact space network structure through polymer bridging. The adsorption energy of acrylamide on the Na-(001) surface of montmorillonite is -108.81 kJ/mol, which is significantly higher than -50.66 kJ/mol on the None-(001) surface. Hydrogen bonding is not the main reason for the adsorption of acrylamide on the montmorillonite surface. NPAM mainly causes the flocculation and sedimentation of montmorillonite through the processes of polymer bridging and electrostatic attraction. This study can provide a theoretical basis for the design and synthesis of new flocculants.
3
Content available Experimental study on the effect of ions on the surface hydration characteristics of fine quartz
Liu Chunfu, Min Fanfei, Liu Lingyun, Chen Jun, Ren Bao, Lv Kai, Tan Yujiao
Physicochemical Problems of Mineral Processing
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2022
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Vol. 58, iss. 4
art. no. 150280
EN
The fine quartz particle hydration and effects of metal ions on the hydration characteristics of fine quartz surface are investigated using the rheological experiment. Several important factors affecting hydration factors, such as particle sphericity, solution pH, ion species, ion concentration were investigated. The results show that viscosity and hydration factor of fine quartz suspension increase with the increase of solution pH. wherein quartz particles have more negative charges on the surface in alkaline environment and strong hydration repulsion; The introduction of metal ions enhances the hydration strength of fine quartz surface to a certain extent. In contrast, high valence and high concentration will increase the viscosity of fine quartz suspension, and the hydration factors of particle surface also increase. At the same ion concentration, the order of influence on the hydration factors of fine quartz particles is Mg2+ > Ca2+ > Na+ > K+. This finding has been attributed to the combination of metal ion hydration and its adsorption on the mineral surface. This study will provide the theoretical guiding significance for the refractory coal slime water and other mineral processing wastewater containing quartz particles.
4
Content available remote Effect of Na+, Ca2+ on the hydration properties of quartz surface: a molecular dynamics simulation study
Liu Chunfu, Min Fan-fei, Chen Jun, Liu Ling-yun, Ren Bao, Lv Kai
Physicochemical Problems of Mineral Processing
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2022
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Vol. 58, iss. 3
art. no. 147452
EN
Effects of metal ions on the surface hydration of fine quartz are investigated by the theoretical methodologies. The hydration layer on the quartz surface is made up of three layers of water molecules, about 8-10 Å. The interaction energy of ions changes from -1.071 eV in water to -1.821 eV (Na+) and -1.896 eV (Ca2+) when ions are present. Metal ions improve the interaction of water molecules with the quartz surface, allowing more water molecules to enter the second and third hydration layers. In the presence of Na+, the diffusivity of water molecules is greater than in Ca2+ solutions. Increased interaction between water molecules and surfaces in the order Ca2+ > Na+ is consistent with metal ions’ propensity to hydrate.
5
Content available Experimental study of dam-break-like tsunami bore impact mechanism on a container model
Chen Cheng, Chen Jun, Lin Peng, Chen Chiwei, Chen Haozhe
Polish Maritime Research
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2020
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nr 1
53--59
EN
Tsunami disasters have frequently occurred in recent years. More and more researchers are focusing on this topic. To investi-gate the tsunami bore impact mechanism on a container model, a multi-functional slope-changing tsunami flume is built in this study. To simulate a tsunami bore, a dam-break wave was generated by a free-falling gate in a reservoir. A needle water level gauge and a high-speed camera were used to measure the tsunami wave heights and velocities for different storage water levels in the test flume, and the corresponding Froude numbers of tsunami waves were also calculated. The factors af-fecting the movement distance of the tsunami wave impacting the container model are explored in this experiment, and the results show that the movement distance is positively correlated with the storage water level, and negatively correlated with the container density and the coast slope.
6
Content available Effect of ultrasonic pre-treatment on coal slime flotation
Lv Wenbao, Chen Jun, Min Fanfei, Hou Baohong, Liu Chunfu
Physicochemical Problems of Mineral Processing
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2020
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Vol. 56, iss. 1
173--183
EN
Combined with the characteristics of flotation feed originating from China’s Panyidong Coal Preparation Plant, the ash, zeta potential, X-ray fluorescence spectroscopy and contact angle test were used to study changes in the surface properties of flotation feed under ultrasonic pre-treatment, and its effect on flotation of coal slime. Results show that Preferred pre-treatment process is ultrasonic secondary treatment, ultrasonic secondary pre-treatment can remove most of the high-ash fine mud for instance kaolinite, montmorillonite and quartz in the coal slurry, reduce the surface electronegativity of coal particles, and increase the contact angle of coal particles. Thus, the concentrate ash content decreases to 13%, the recovery rate, yield of flotation concentrate and combustible matter recovery reach 92.6%, 90.9% and 97.6%, respectively.
7
Content available Adsorption of methylamine cations on kaolinite basal surfaces : A DFT study
Chen Jun, Min Fan-fei, Liu Ling-yun, Jia Fei-fei
Physicochemical Problems of Mineral Processing
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2020
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Vol. 56, iss. 2
338--349
EN
To explore the interaction of alkylamine surfactants with kaolinite, the density functional theory (DFT) method was used to calculate the single adsorption of different methylamine cation on kaolinite basal surfaces and the competitive adsorption of methylamine cation and water molecule on kaolinite basal surfaces, respectively. Different methylamine cations can adsorb on kaolinite basal surfaces by electrostatic interaction and hydrogen bonds, and the methylamine cations more easily adsorbed on kaolinite Si-O surface. In the case of competitive adsorption with water molecule, the methylamine cation is capable of flushing out the surrounding water molecule to get rid of its steric effect and stably adsorbing on kaolinite basal surfaces, and the adsorption state of the competitive adsorption system is more stable. The adsorption mechanism of methylamine cation on kaolinite basal surface should be the result of electrostatic interaction and hydrogen bonds, and the electrostatic interaction plays the main role.
8
Content available remote Mechanical performance of overlap connections with grout-filled anchor reinforcements in embedded metal corrugated pipe
Chen Jun, Chen Xulin, Ding Fa-xing, Xiang Ping, Yang Cai-qian, Liu Yilong, Xu Fu
Archives of Civil and Mechanical Engineering
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2020
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Vol. 20, no. 4
456--467
EN
To study the mechanical performances of a new kind of overlapping connection with grouted anchor reinforcements in embedded metal corrugated pipes, a total of 24 groups of 72 specimens were prepared and tested. The overlap connection performance of grouting anchor reinforcements in embedded metal corrugated pipes was studied by bi-directional tension test. The factors such as the diameter of anchor reinforcements, anchor length and location of reinforcements were taken into account. The results show that the bi-directional tension test method can effectively reflect the actual stress state of the overlap connection. When the connection satisfies the structural requirements, the location of the reinforcement has little influence on the anchorage performance of the connection. Under the same conditions, the failure load of the specimens will increase with the increase of the diameter of reinforcements and the anchorage length. Meanwhile, under the same conditions, the average bond stress decreases with the increase of the reinforcement diameter and the anchorage length. Experimental results and analysis show that overlap connection with grout-filled anchor reinforcements in embedded metal corrugated pipe has good anchoring performances, and also has the advantages of simple structure and convenient construction.
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