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1

Evaluation of a novel depressant PMAA for the separation of fluorite from calcite using NaOl as a collector

Zhang Xiaofeng, Li Qi, Qin Wenqing, Liu Cheng, Yang Siyuan

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 3

art. no. 188272

EN

It is challenging to separate fluorite from calcite due to their same calcium activated sites on their surfaces. The copolymer of maleic and acylic acid (PMAA) was used to inhibit the calcite in the flotation of fluorite. Micro-flotation results exhibited that sodium oleate (NaOl) had a good ability to collect fluorite and calcite in the scope of pH 7-10. The PMAA treatment prior to NaOl selectively depressed the floatability of calcite while allowed the flotation of fluorite, and the artificial minerals mixture plotted that fluorite/calcite could be effectively separated in the presence of PMAA/NaOl. Zeta potential results suggested that NaOl collector was absorbed on the PMAA-conditioned calcite surface but did not adsorb on the PMAA-conditioned fluorite surface. XPS results and calculational chemistry revealed the chemical interaction occurred between calcite surface and PMAA which was attributed to the calcium ions of calcite surface interacting with -COOH group of PMAA.

2

Numerical simulation study on NO oxidation by OH radical clusters in flue gas

Wen Zhengcheng, Zhang Xiaofeng, Huang Ju, Yang Zhengyin

Environment Protection Engineering

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2023

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Vol. 49, nr 3

69--82

EN

Fenton reaction is an important method to remove NO from flue gas. •OH radicals generated in the Fenton reaction can effectively oxidize NO to NO2, which is absorbed and removed by alkali sorbent. To supply guidance for engineering research, numerical simulation of NO oxidation by •OH radical clusters in flue gas has been carried out using Fluent software. The average concentration of NO on the cross sections at various positions of a cylindrical pipe with a circular surface was calculated by simulation. Under various working conditions (temperature, •OH/NO molar ratio, NO concentration in flue gas, and jet velocity), NO oxidation efficiency by •OH radical was simulated and the key factors affecting NO oxidation were analyzed. The results show that temperature and •OH/NO molar ratio are the key factors affecting the oxidation of NO by •OH radicals. The injection velocity has also a significant effect on the oxidation efficiency while the moisture and oxygen content are minor factors influencing the process. The optimum oxidation efficiency of NO is obtained at 473–523 K, the molar ratio of •OH/NO ca. 1.4, the jet velocity 10 m/s, and the flue gas velocity of 3 m/s.

3

Comparison of the Bending Resistance Properties of Carbon Fiber/Foam Sandwich Structural Composites with Different Laying Angles

Zhu Lvtao, Cao Shengbin, Zhang Xiaofeng, Shen Wei, Zhu Chengyan

Fibres & Textiles in Eastern Europe

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2022

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Vol. 30, no. 2

75--81

EN

This research aimed to explore the influence of fiber laying angles on the bending resistance properties of carbon fiber/foam sandwich structural composites. Four kinds of composites with the following laying angles: [0°]8, [0°/45°/90°/-45°]s, [0°/90°]4 and [45°/-45°]4 were prepared and tested in three-point bending experiments. The results obtained showed that the bending resistance performance was the best when the laying angle was [0°]8, while it was the worst when the laying angle was [45°/-45°]4. Besides, it was found that the tensile performance was the best when the fibers were arranged in the 0° direction when the strength utilisation rate was the highest. In addition, by observing the failure morphologies of the composites, the delamination and foam cracking were found in the four groups of composites. In contrast, the phenomenon of significant fracture was found on composites with a laying angle of [45°/-45°]4 only, indicating it had a poor bending resistance performance.

4

Bending Failure Behavior of the Glass Fiber Reinforced Composite I-Beams Formed by a Novel Bending Pultrusion Processing Technique

Zhu Lvtao, Cao Shengbin, Zhang Xiaofeng, Li Lei

Autex Research Journal

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2022

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Vol. 22, no. 2

172--176

EN

The glass fiber reinforced resin matrix composite I-beams were designed and formed via a type of novel bending pultrusion processing technique, and the three-point bending tests were carried out to analyze the mechanical bending performances. The obtained results show that the main failure mode of the composite I-beam under the bending load is the upper structure (top flange) cracks along the length direction of the fibers, and the cracks simultaneously propagate downwards in the vertical direction. The bifurcated cracks can be found at the junction area between the top flange and web. In addition, the main bending failure mechanism of the composite I-beam includes the matrix cracking, propagation of cracks, and final fracture failure. In particular, noting that when the crack reaches the I-shaped neck position, the lateral bifurcation occurs, and the resulting secondary cracks further extend in two directions, which leads to the serious damage between the top flange and web, and the ultimate fracture failure occurs.