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1

Exploring the effect of sodium hexametaphosphate in coal slime flotation

Lu Tianshen, Deng Zhengbin, Tang Yun, Tang Haiwen

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 1

art. no. 162075

EN

In this paper, the influence of sodium hexametaphosphate (SHMP) in coal slime flotation was studied, and the interaction between SHMP and coal slime flotation particles was revealed through XRD test, contact angle measurement, zeta potential test, scanning electron microscopy analysis, XPS analysis, and DLVO theoretical calculation. The experimental results show that when the dosage of SHMP is 1500 g/t, the recovery rate of clean coal combustibles increases by 9.61 %. SHMP reduces the hydrophobicity of clay minerals (kaolinite) in coal slime flotation and also enhances the dispersibility of coal slime particle. Scanning electron microscopy and energy dispersive analysis showed that SHMP reduced the number of clay particles (kaolinite) on the coal surface, thereby reducing the ash content of the clean coal. In this paper, SHMP is mainly used to modify the surface of kaolinite so as to reduce the hydrophobicity of the mineral, that is, to improve the recovery rate of clean coal combustibles in coal slime flotation.

2

The effect of NaCl concentration on the interaction energy between feldspar minerale

Güven Onur, Can Muhammed Fatih, Karagüzel Cengiz

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 5

art. no. 151031

EN

The impact of the usage of monovalent ion concentration on the selective flotation of feldspar minerals has been receiving more attention in recent years. Although many experimental studies have been reported to justify its contribution to their flotation recovery, the effect of particle-particle interaction with theoretical calculations has rarely been studied. The objective of this study was, therefore, to explain the effect of monovalent ion concentration (in particular NaCl) on interactions between albite and microcline particles with a theoretical model based on the classical DLVO. The theoretical modeling results suggested that controlling the monovalent ion concentration not only adjusts the energy barrier between particles but also can be used to determine the critical salt concentration for further tests.

3

Diffuse-layer surface potentials of colemanites mined in Turkey

Senol-Arslan Dilek, Drelich Jaroslaw W.

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 5

art. no. 151933

EN

Colemanite crystal specimens were handpicked at Kestelek, Emet (Hisarcik, Espey), Bigadic mines in Turkey for characterization of their composition and surface potential. X-ray diffraction analysis revealed no differences in mineralogical makeup of the crystals, but elemental analysis indicated differences in the type of trace (<0.1 wt%) elements. Zeta potential measurements showed small differences in zeta potential values, with isoelectric points (iep) varying from about pH = 9.6 to pH = 10.2. However, no correlation was found between iep and the type of trace elements. Additionally, atomic force microscopy (AFM) was employed to measure the colloidal interactions between a silicon nitride (Si3N4) cantilever tip and colemanite crystal surfaces in 1 wt% colemanite-saturated aqueous solutions at three different pHs (8.4, 9.4 and 11). The Derjaguin-Landau-Verwey-Overbeek theory (DLVO) was applied to examine the AFM tip interactions with colemanite surfaces in an aqueous solution of colemanite saturated solutions. The results revealed attractive forces at pH = 8.4 and 9.4 and repulsive forces at pH = 11, confirming the location of an isoelectric point for colemanite specimens somewhere between pH = 9.5 and pH = 10.1. Theoretical analysis of the force curves using the DLVO theory allowed for assessment of both surface charge density and surface potential for colemanite specimens used in this study.

4

Effect of flow structure and colloidal forces on aggregation rate of small solid particles suspended in aqueous solutions

Tyl Grzegorz, Kondracki Juliusz, Jasińska Magdalena

Chemical and Process Engineering

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2021

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Vol. 42, nr 4

369-–389

EN

In this paper aggregation of small solid particles in the perikinetic and orthokinetic regimes is considered. An aggregation kernel for colloidal particles is determined by solving the convection-diffusion equation for the pair probability function of the solid particles subject to simple shear and extensional flow patterns and DLVO potential field. Using the solution of the full model the applicability regions of simplified collision kernels from the literature are recognized and verified for a wide range of Péclet numbers. In the stable colloidal systems the assumption which considers only the flow pattern in a certain boundary layer around central particle results in a reasonable accuracy of the particle collision rate. However, when the influence of convective motion becomes more significant one should take into account the full flow field in a more rigorous manner and solve the convection-diffusion equation directly. Finally, the influence of flow pattern and process parameters on aggregation rate is discussed.

5

Improved flotation of heat treated lignite with saline solutions containing mono and multivalent ions

Ozdemir O., Ersoy O. F., Guven O., Turgut H., Cinar M., Çelik M. S.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1070--1082

EN

Flotation of lignites is inherently difficult. However, pre-heat treatment of coal is also known to make coal surfaces more hydrophobic possibly through removal of water entrapped in the structure of coal. In this context, the objective of this study was, therefore, to determine changes in the hydrophobicity of some lignites under moderately controlled heat treatment and correlate the flotation response of lignites in different salt solutions of NaCl, KCl, CaCl2, and MgCl2 without using any reagent. The results of flotation tests suggested that under the present test conditions, it was possible to float thermally pre-treated lignite samples of partially hydrophobic character in salt solutions in the absence of collector and frother. In addition, the effect of heat treatment on hydrophobicity, and in turn flotation was explained by a theoretical model based on extended DLVO interactions to quantify the effects of both heat treatment and salt concentration on bubble-particle interactions. The results of theoretical modeling suggested that the removal of hydrogen containing groups from coal surfaces significantly contribute to the electrical double layer and hydrophobic forces that govern the magnitude of energetic barrier and also the extent of bubble-particle attachment.

6

Interaction between mineral particles during ascharite flotation process and direct force measurement using AFM

Li Z., Han Y., Li Y., Gao P.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1161--1174

EN

Interaction between mineral particles during ascharite flotation was investigated by flotation, zeta potential, Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, atomic force microscope (AFM) and SEM-EDS tests. Flotation results showed that the ascharite recovery decreased significantly in the presence of serpentine. In order to improve the ascharite recovery, negative charged quartz was used to limit the detrimental effect of serpentine on ascharite flotation in this research. The effect of quartz on improving ascharite recovery was attributed to the particle surface interactions. The DLVO theory was applied to study the particles interaction in the aqueous solution. The fitting curves showed that serpentine could attach to the surface of quartz easily, and quartz would be well dispersed with ascharite. Therefore, quartz can improve the ascharite flotation performance effectively by interaction between particles. Zeta potential tests showed the opposite charges on the surfaces of mineral particles, which was the basic reason leading to particles interaction. The force measurement results of AFM indicated that the attraction force existed between serpentine and ascharite, as well as serpentine and quartz, but the force between quartz and ascharite was repulsive. The DLVO theory was in a good agreement with the results of AFM. Eventually, particles coating were observed by SEM-EDS, which supported the results of DLVO theory and AFM measurements. During the flotation process, addition of quartz would lead to attachment of serpentine to the quartz surface, so the adverse effect of serpentine on decreasing floatability of ascharite was weakened.

7

Proces formowania granulowanego osadu w warunkach tlenowych: przegląd literaturowy

Kończak B., Miksch K.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2011

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Vol. 20, No. 1

43--51

PL

Granulowany osad czynny pracujący w warunkach tlenowych jest nową, obiecującą technologią dla kompaktowych oczyszczalni ścieków. System ten, w odróżnieniu od konwencjonalnego układu z osadem czynnym, posiada wiele zalet, takich jak wysoki stopień retencji biomasy, wysoka efektywność oczyszczania ścieków, mniejsza produkcja osadów nadmiernych, doskonałe właściwości sedymentacyjne oraz odporność na substancje toksyczne. Tlenowe granule z sukcesem udało się pozyskać w reaktorach sekwencyjnych typu SBR (Sequencing Batch Reactor). Na formowanie tlenowych granul ma wpływ: kompozycja pożywki, warunki „uczta-głód”, siły hydrodynamiczne, krótki czas sedymentacji, wysoka zawartość polimerów zewnątrzkomórkowych, a także inkluzje kationów dwuwartościowych. W tym przeglądzie przedstawiono dotychczasową wiedzę dotyczącą procesu formowania tlenowych granul.

EN

The aerobic granular activated sludge process is a promising technology for compact wastewater treatment plants. This system is superior to conventional activated sludge processes, in terms of high biomass retention, high conversion capacity, less biomass production, excellent settleabilty and resistance to inhibitory and toxic compounds. Aerobic granules were successfully cultivated in a sequencing batch reactor (SBR). These systems fulfil most of the requirements for their formation as: substrate composition, feast-famine regime, hydrodynamic shear force, short settling time, high extracellular polymeric substances (EPS) content, inclusion of divalent cations. In this review the current knowledge of aerobic granules formation is present.