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221 results on '"Qiu, Tingsheng"'

25. The Role of Fe(III) in Selective Adsorption of Pullulan on Calcite Surfaces: Experimental Investigation and Molecular Dynamics Simulation.

Author

Ding, Kaiwei, Qiu, Tingsheng, Qiu, Xianhui, Zhao, Guanfei, Jiao, Qinghao, Fang, Jiangjie, Lai, Ruisen, and Yang, Wenhui

Subjects
*POLYSACCHARIDES, *ZETA potential, *CALCITE, *ADSORPTION capacity, *FLUORITE
Abstract

The floatability of fluorite and calcite exhibit similar properties, rendering their flotation separation challenging. Macromolecular polysaccharide reagents containing the polyhydroxyl group have shown broad promising application. The selectivity of polysaccharide is relatively low. In this study, the introduction of Fe3+ was employed to enhance the selective adsorption capacity of Pullulan polysaccharide towards fluorite and calcite minerals, thereby achieving effective flotation separation. Furthermore, the mechanism underlying intramolecular interactions was elucidated. The DFT calculation and XPS analysis revealed that the adsorption of Fe3+ on the calcite surface was more favorable, leading to the formation of a Ca-O-Fe structure. The MD simulation, XPS analysis, and Zeta potential analysis revealed that the Fe-OH groups on the surface of calcite reacted with the -OH groups in Pullulan and formed bonds, resulting in the formation of a Calcite-Fe-Pullulan structure. This facilitated the attachment of a significant number of Pullulan molecules to the calcite surface. The formation of a hydrophilic layer on the outer surface of calcite by Pullulan, in contrast to the absence of such layer on fluorite's surface, results in an increased disparity in surface floatability between these two minerals, thereby enhancing the efficiency of flotation separation. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Effect of Activated Siliceous Wastes Incorporated as Mineral Admixtures on the Rheological Properties of Cement Paste: Insights into Their Physicochemical Interactions in Suspension.

Author

Shi, Linyun, Kuang, Jingzhong, and Qiu, Tingsheng

Subjects
MINE waste, SILICATE minerals, WASTE recycling, CEMENT industries, MINERAL properties, CEMENT admixtures
Abstract

Mechanical grinding is a common method used to enhance the pozzolanic activity of tailings, and these activated tailings can be used as supplementary cementitious materials in cement production. However, the addition of activated tailings usually reduces the workability of cement paste, and the mechanism of influence of different minerals in tailings on workability varies. In this study, three kinds of principal silicate minerals in tailings—quartz, feldspar, and mica—were mechanically activated. The influence of these activated minerals on the rheological properties of cement paste were studied in the absence or presence of PCE (polycarboxylate ether) superplasticizers, and the influence mechanism was investigated using rheology, TOC, contact angles, zeta potential, XPS, ICP-OES, and XRD. The results showed that quartz has the highest fluidity, and mica has the lowest. An increase in hydrophilicity decreased the flowability of the blended cement paste. The increase in the metal cation dissolution rate was the main reason for the decrease in the fluidity of PCE-blended cement pastes. The knowledge gained provides a valuable reference for the utilization of activated tailings in cement production. [ABSTRACT FROM AUTHOR]

Published
2024
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