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1

Influence of pH and salt solution on the sedimentation properties of finebauxite tailings

Yu Haihao, Bai Zhixiao

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 2

art. no. 186326

EN

Bauxite tailings slurry is a type of solid waste produced in the process of bauxite washing and beneficiation. It has poor engineering properties, that is, self-consolidation settlement unusually cannot be completed during several decades. To investigate the sedimentation properties of bauxite tailings, bauxite tailings slurry, phyllite residual soil, and kaolinite, we conduct sedimentation tests on these materials in varying pH and salt solution environments. The influence mechanism of the surface electrical properties of clay particles on the settlement of tailings slurry is investigated using the zeta potential test. The findings reveal that increases in the cation concentration and valence state lead to compression of the electric double layer on the surface of three types of soil particles, resulting in a decline in the repulsive potential energy and an increase in the gravitational potential energy. This in turn contributes to a reduction in the settling stable void ratio. As the pH increases, the zeta potentials of the three soils gradually decrease from positive to negative. A change in the pH at the isoelectric point, PZCedge, triggers the transformation of the kaolinite mineral arrangement. When the pH is either greater than or less than the isoelectric point, an increase or decrease in the pH results in expansion of the electric double layer of the clay particles and an increase in the pore content. The resultsof this study suggest that bauxite tailings mud is more likely to settle in an acidic environment than in an alkaline environment, thus an acidic settling environment should be utilized for bauxite tailings produced in industrial production.

2

Experimental and modelling analysis of the separation of ionic salts solution in nanofiltration process

Kowalik-Klimczak A., Zalewski M., Gierycz P.

Challenges of Modern Technology

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2015

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Vol. 6, no. 2

24--29

EN

This paper presents the possibility of the use of Donnan and Steric Partitioning Pore Model (DSPM) based on the extended Nernst-Planck equation for interpretation of the separation of chromium(III) and chloride ions from concentrated salt solution in nanofiltration process. Results of predictions obtained with the analyzed model showed the significant effect of the pore dielectric constant on separation of chromium(III) and chloride ions from concentrated salt solution on nanofiltration membranes. It was found that the increase of pore dielectric constant caused the decrease of chromium(III) and chloride ions separation. Additionally, the satisfactory agreement between experimental and predicted data was stated. The Donnan and Steric Partitioning Pore Model may be helpful for the monitoring of nanofiltration process applied for different industrial wastewater treatment.

3

Experimental knowledge of autothixotropy of water and its possible importance for the physics-chemical theory in environment

Vybíral B.

Proceedings of ECOpole

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2011

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Vol. 5, No. 2

461--466

EN

It is well known that water is the source of all life and therefore it is an important factor for the chemical-physics theory in environment. The article deals with phenomenon in water that was called „autothixotropy of water“. A history of the discovery of the phenomenon is connected with very fine gravimetric experiments which have been made by the author between the years 1978 and 1986. The independent phenomenon of autothixotropy of water was qualitatively explored in the period from 1991 to 1992 and quantitatively in period from 2003 to 2011. From the physical point of view the autothixotropy of water is a very weak macroscopic phenomenon that is observed in water that has remained at rest for a certain time (in about tens of hours or days) ie ‘standing’ water. For the experiments distilled water was used, re-boiled before use. Physically the phenomenon manifests itself by force (mechanical resistance) acting on a body immersed in ‘standing’ water in the direction of the tendency to change its position. The fundamental method of research of phenomenon is static method; it uses a moment of force that is necessary for a very distinctive turn of a stainless steel plate hung up on a very thin filament and immersed in examined water. With a certain angular torsion of the filament a certain moment of force is achieved when a state of stress reaches a critical value in ‘standing’ water. It is demonstrated with an expressive changing of angular position of the plate. When the direction of moment of force in ‘standing’ water is changed, it is reflected in a different angle rotation of the plate (the phenomenon of hysteresis was observed). The phenomenon of autothixotropy disappears for a certain time (in tens of minutes or hours), if ‘standing’ water is mechanically vigorous shaking or re-boiled. It is significant that the phenomenon of the autothixotropy is not present in deionised distilled ‘standing’ water. From the chemical-physics microscopic point of view the autothixotropy of water can be explained by a hypothesis of a cluster formation by H2O molecules in ‘standing’ water. As the phenomenon of autothixotropy is not present in ‘standing’ deionised water, it may be primarily caused by a presence of ions in water, as it was demonstrated in the experiment with a salt solution (NaCl). Environment and biophysical applications of the autothixotropy of water remain still open. Some possible applications of the phenomenon are outlined.

PL

Woda jest źródłem życia i dlatego jest ona ważnym obiektem badań fizyki chemicznej środowiska. W artykule przedstawiono zjawisko zachodzące w wodzie, nazywane „autotiksotropią wody”. Historia jego odkrycia wiąże się z bardzo precyzyjnymi eksperymentami grawimetrycznymi, które zostały wykonane przez autora w latach 1978 i 1986. Ponadto zjawisko autotiksotropii wody zostało jakościowo zbadane w latach 1991/92 oraz ilościowo od 2003 do 2011 roku. Z fizykalnego punktu widzenia autotiksotropia wody jest bardzo subtelnym zjawiskiem makroskopowym, które obserwuje się w wodzie, pozostającej przez pewien czas w spoczynku (około kilkudziesięciu godzin), czyli wodzie „stojącej”. Zjawisko to przejawia się przez oporność mechaniczną działającą na ciało zanurzone w wodzie „stojącej”. Podstawę badania stanowi metoda statyczna, wykorzystująca moment siły, która umożliwia pomiar kąta skręcenia nierdzewnej blachy stalowej zawieszonej w badanej wodzie. Kiedy kierunek momentu siły w „stojącej” wodzie się zmienia, znajduje to odzwierciedlenie w różnych kątach obrotu tej płyty (zaobserwowano zjawisko histerezy). Zjawisko autotiksotropii znika po pewnym czasie (w kilkadziesiąt minut lub godzin), jeśli „stojąca” woda jest mieszana mechanicznie lub ogrzewana do wrzenia. Znamienne jest, że zjawisko autotiksotropii nie występuje w „stojącej” zdejonizowanej wodzie destylowanej. Zjawisko to może być wyjaśnione przez hipotezę powstawania „w wodzie stojącej” klastrów molekuł H2O. Zjawisko autotiksotropii nie jest obecne w zdejonizowanej wodzie „stojącej”, co może być spowodowane obecnością jonów w wodzie, jak to wykazano w eksperymencie z roztworem soli kuchennej (NaCl). Środowiskowe i biofizyczne wykorzystanie autotiksotropii wody nadal pozostają otwarte. Niektóre z możliwych zastosowań tego zjawiska są już opisane.

4

Weryfikacja zmian ściśliwości wody i roztworu soli NaCl pod wpływem wysokich ciśnień

Koszela J., Koszela-Marek E., Sysak Z.

Górnictwo i Geoinżynieria

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2008

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R. 32, z. 2

205-211

PL

Przedstawiono wyniki ściśliwości wody i roztworu soli NaCl (20 g/dm3) pod wpływem ciśnień hydrostatycznych od 50 do 400 MPa, przy temperaturze 21stopni Celsjusza. W zakresie tych ciśnień objętość wody zmniejszyła się od 2,1 do 9,4%, a roztworu soli od 1,6 do 6,9%. Niejednakowym i nieliniowym zmianom ulegały także współczynniki ściśliwości Beta. Badania przeprowadzono w specjalnie skonstruowanej aparaturze.

EN

Paper presents results of water and salt NaCl (20 g/dm3) solution compressibility under hydrostatic pressure from 50 up to 400 MPa, with 21degrees of Celsius temperature conditions. In the presented range of pressures water decreased in volume from 2,1 to 9,4%, NaCl solution from 1,6 to 6,9%. Coefficients of compressibility Beta are unequal and nonlinear. Examinations have been made in especially designed equipment.

5

The concentration of spent salt solutions by atmospheric evaporation

Gryta M.

Polish Journal of Chemical Technology

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2004

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Vol. 6, nr 3

9-12

EN

The studies concerning the application of atmospheric evaporation for the concentration of saline spent solution have been performed. The evaporation surface was created with the use of the Bialecki rings. The aim of the present work is restricted to the evaporation caused by a free convection over the wetted surface. The influence of the rate of salt concentration, the temperature and the humidity of the air on the evaporation rate was investigated.