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1

Influence of grinding methods on the preparation of ultra-clean coal from slime

Wang Ruiyang, Gao Liang, Liu Wenli, Zhuo Qiming

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 6

art. no. 151957

EN

This study discusses the technology of coal slime recovery for preparing ultra-clean coal (UCC). X-ray diffraction analysis (XRD) and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS) were used to analyze the characteristics of coal slime and to explore the types of minerals and embedded characteristics of coal slime. The particle interaction energy and contact angle analysis were used to determine the UCC preparation process through dry and wet grinding dissociation comparison and shear flocculation flotation tests, combined with zeta potential measurements. The results showed that the inorganic minerals in the slime were mainly kaolinite clay minerals, which were easy to mud in the pulp and needed grinding. The calculation results of the interaction energy indicated that the interaction force of dry-ground slime in the pulp was small, and flocculation was more likely to occur. The wet-ground product was subjected to three flotations to obtain UCC with an ash content of 0.95%.

2

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.

3

Efekt kooperatywności oddziaływań niekowalencyjnych w wybranych układach molekularnych stabilizowanych wiązaniami wodorowymi i halogenowymi

Domagała Małgorzata, Dominikowska Justyna, Palusiak Marcin

Wiadomości Chemiczne

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2019

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[Z] 73, 1-2

33--52

EN

Among various so-called weak interactions, a halogen bond [8 and references therein] is currently probably one of more explored by researchers. This is due to the fact that it has several properties in common with the hydrogen bonding, and thus, similarly as already well characterised H-bond, it may have a crucial role in different physical, chemical, and biological processes. This bond is formed due to stabilising interactions between a region of positive charge located on a surface of the halogen atom and the other atomic center possessing the electron charge surplus (e.g. a lone pair) [8]. The region of positive charge appears on the halogen atom surface due to deformation of its electron cloud resulting in its ellipsoidal shape with the short axis opposite the covalent bond and the long axis in the perpendicular direction [11]. This results in a particular distribution of local charges on the atomic surface, as shown in Figure 1. As a consequence the halogen atom may exhibit a dual character, acting as either electron charge donor or acceptor, depending on the type of interaction and the direction of the appearing interactomic contact. A good example of such situation is shown in Figure 2. Thus, one may consider the situation when two interactions are formed simultaneously and the halogen atom acts as an electron charge donor and acceptor at the same time. For such situation the synergism of both interactions may strengthen complexation. In order to analyze that case, various representative complexes were investigated [13, 17, 18, 20, 21] by means of many-body interaction approach [5, 6]. In general, it appears that as distinct to hydrogen bond [2–4], the synergism is rather weak, with some exceptions for iodine atom due to stronger halogen bonds formed by that atomic centre [13, 17, 18]. In the case of halo-amine tetramers [21] the additional stabilising effect derived from back bonding of π type was found – for the first time for a halogen bond.

4

Surface interaction energy simulation of ceramic materials with epoxy resin

Fei-Zhou L., Zheng-Lin L., Zhi-Huai Y., Kai Q.

Polimery

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2015

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T. 60, nr 7-8

468--471

EN

A new method to calculate the surface interaction energy of ceramic particles and epoxy resin network was investigated using the Material Studio software solution. Detailed simulations were performed with molecular dynamics (MD) method, using Amorphous Cell module, creating relatively simple surface models of polymer (epoxy resin) and ceramics (Al2O3, SiO2 and SiC). The surface models obtained were used to calculate properties and the surface interaction energy of the materials studied. The computed results are in good agreement with the experimental data, confirming the ability to employ the described simulation method in theoretical evaluation of interaction between various filler or reinforcing materials and the polymer matrix.

PL

Testowano nową metodę obliczania energii oddziaływań powierzchni cząstek ceramicznych z żywicą epoksydową. Obliczenia wykonywano korzystając z oprogramowania Material Studio. Szczegółowe symulacje prowadzono metodą dynamiki molekularnej (MD) za pomocą modułu Amorphous Cell, tworząc modele powierzchni polimeru (żywicy epoksydowej) imateriału ceramicznego (Al2O3, SiO2 lub SiC). Otrzymane modele posłużyły do obliczeń właściwości oraz energii oddziaływań powierzchni badanych materiałów. Uzyskano dobrą zgodność wyników symulacji zdanymi doświadczalnymi, co potwierdziło możliwość zastosowania opisanej metody symulacji do teoretycznej oceny oddziaływania różnych napełniaczy ceramicznych z matrycą polimerową.

5

Zinc ion adsorption on carbon nanotubes in an aqueous solution

Ansari A., Mehrabian M. A., Hashemipour H.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 3

29-37

EN

The literature devoted to numerical investigation of adsorption of heavy metal ions on carbon nanotubes is scarce. In this paper molecular dynamics is used to simulate the adsorption process and to investigate the effect of the infl uencing parameters on the rate of adsorption. The predictions of the molecular dynamics simulation show that the adsorption process is improved with increasing the temperature, pH of solution, the mass of nanotubes, and surface modifi cation of CNT using hydroxyl and carboxyl functional groups. The results predicted by the model are compared with the experimental results available in the literature; the close agreement validates the accuracy of the predictions. This study reveals that the water layers around the carbon nanotubes and the interaction energies play important roles in the adsorption process. The study also shows that electrostatic force controls the attraction of zinc ions on the nanotube sidewall.

6

New Medium - Size Basis Sets for Rare - Gas Atoms

Makarewicz J.

Computational Methods in Science and Technology

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2012

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Vol. 18, No. 2

XX-XX

EN

New medium-size basis sets are constructed for rare-gas (Rg) atoms and tested on their dimers Rg2. The main part of the these bases contains the standard aug-cc-pVTZ basis set modified and extended by the g- and h-polarization functions. Their optimization allows accurate calculations of the dispersion interaction without the involvement of the bond functions. A new convenient analytical potential function is invented to fit accurately the interaction energy. The potentials derived for Rg dimers predict the vibrational transition energies and rotational constants to accuracy of 1%.

7

Interface Phenomena and Interaction Energy at the Surface of Electroconductive Solids

Nahirnyj T., Tchervinka K.

Computational Methods in Science and Technology

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2008

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Vol. 14, nr 2

105-110

EN

For the local gradient approach in thermomechanics, the regularities of nearsurface nonhomogeneity in nonferromagnetic electroconductive solids, including the size effect of the ultimate stress limit are studied. It is noted that surface values of interaction energy and thermodynamic electric potential are determined by physical and geometrical properties of a body.

8

Isoelectronic dimers [(XH3)2, (YH2)2, (ZH)2, and (Rg)2] in the groups of the periodic system: ab initio quantum chemical calculations

Hobza P., Burda J.V., Zahradnik R.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 7S

1497-1504

EN

The (ZH)2, (YH2)2, (XH3)2 and (Rg)2 dimers [Z=F-At; Y=O.Po; X=N, Bi; Rg=rare gas] were studied ab initio using the CCSD(T) and MP2 procedures. Average relativistic effective potentials were used for all the halogens, while Stuttgart effective core potentials were used for the remaining non-hydrogen atoms. All the (HX)2 structure are H-bonded. All the stabilization energies mutually approach when passing down the group of the periodic system.