Shevchenko Н., Cholyshkina V., Kurilov V., Lіpska H., Havrosh O. Patterns of constrained particle settling in water mineral suspensions of different densities

Geoteh. meh. 2024, 169, 140-152

 

PATTERNS OF CONSTRAINED PARTICLE SETTLING IN WATER MINERAL SUSPENSIONS OF DIFFERENT DENSITIES

Shevchenko Н., Cholyshkina V., Kurilov V., Lіpska H., Havrosh O.

M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine

UDC 532.5.011: 622.33: 622.752.3

Language: English

Abstract. The settling velocity of particles in mineral suspensions is a crucial parameter for calculating the design of various hydraulic devices and equipment used for mineral pulp benefication. In studies of gravity separation of heterogeneous particles by settling, the determination of mass settling velocity, the influence of suspension density on the process, and the applicability of classical hydrodynamics laws remain the least explored aspects. Often, free settling conditions are used for calculating hydraulic separation processes, but this introduces significant error in the velocity magnitude, as, in practice, the process occurs under constrained conditions. The purpose of this work was to analyze the patterns of constrained settling using the example of coal particle settling in fly ash suspensions from thermal power plants. The article employs an original method for calculating the characteristics of suspensions and the velocity of constrained settling depending on the density. Experimental data on the mass settling velocity of natural fly ash are presented, which indicate the order of velocities and give grounds for the velocity calculation. Given the fine particle size of the ash, the main focus was on the settling of fine coal in the ash. The analysis covered a database in which the characteristics of suspensions and the velocity of constrained coal settling were determined by varying the density of the ash suspension from 1.05 g/cm³ to 1.3 g/cm³ and the size of the settling coal from 0.01 mm to 4 mm. The database was analyzed using the Reynolds number and the applicability of Stokes' law and Lyashenko's law. It was found that the more dilute is the suspension, the smaller is the particle size that follows Stokes' law, and the smaller is the range of particle sizes that Stokes' law covers, and vice versa. For fine coal fractions of 0.001–0.1 mm, the numerical coefficient in Stokes' law decreases according to an inverse power law depending on the pulp density. The ratio of free to constrained settling velocities decreases according to a power law, similar to Lyashenko's law for porosity. The conducted research expands scientific understanding of the processes of constrained settling, facilitates engineering calculations when designing hydraulic devices, and optimizes their operational modes.

Keywords: suspension, fly-ash, density, speed, constrained deposition.

 

REFERENCES

1. Babii, K., Ikol, O., and Malieiev, Y. (2019), "Substantiating a technique to process hard rock involving extraction of valuable components and use of wastes to form mesorelief", E3S Web of Conferences, vol. 109, 00003 https://doi.org/10.1051/e3sconf/201910900003

2. Koshlak, G.V. and Pavlenko, A.M. (2021), "Prospects for the production of TES ash for the preparation of household materials", Ecological safety and balanced resource consumption, no 1 (23), рр. 92–101.

3. Khudyakova, L.I., Zalutskiy, A.V. and Paleev, P.L. (2019), "Use of ash and slag waste from thermal power plants", J. XXI century. Technosphere safety, no 4(3), рр. 375–391, https://doi.org/10.21285/2500-1582-2019-3-375-391

4. State building committee (1991), Interstate standard GOST 25818-91. Тhermal plant fly-ashes for concretes. Specification, Moscow, USSA, 12 p., available at: https://www.gostrf.com/normadata/1/ 4294853/4294853144.pdf (Accessed 12 August 2024).

5. Shevchenko, G.O., Usov, O.A., Cholishkina, V.V. and Kurilov, V.S. (2024), "Efficiency of hydraulic separation of TТРs fly-ash", Proceedings of the XXI International Scientific and Technical Conference "Poturaevskiy reading"", 23 February, Dnipro: NTU "Dnipro Polytechnic", р. 36, available at: https://gmi.nmu.org.ua/ua/nauka/vibro/%D0%A2%D0%B5%D0%B7%D0%B8%20%D0%
9F%D0% A7%202024%201.pdf (Accessed 17 June 2024).

6. Bogdanov, O.S. and Olevsky, V.A. (1972), Spravochnik po Obogascheniju rud. Tom.1 [Handbook for ore dressing], vol.1, Nedra, Moscow, USSA, pp. 229 –233.

7. Nadutyi, V.P., Kurilov, V.S., Cholyshkina, O.G. and Hankevych, V.F. (2021), "Analytical studies on constrained particle settling velocity in a water suspension of fly ash from thermal power plants", Naukovyi Visnyk Natsionalnoho Hirnychoho Uni-versytetu, no. 1(181), рр.32-39, https://doi.org/10.33271/nvngu/2021-1/032

8. Bulat, A.F., Shevchenko, G.O., Cholishkina, V.V. and Kurilov, V.S. (2023), "Experimental determination of the solid phase density of thermal power plant ash", Geo-Technical Mechanics, no.167, pp. 110-118, https://doi.org/10.15407/geotm2023.167.110

 9. Shevchenko, G.O., Cholyshkina, O.G., Sukharyev, V.V. and Kurilov, V.S. (2023), " Mathematical model for determining the hydraulic characteristics of finely dispersed water mineral suspensions", Geo-Technical Mechanics, no.163, pp. 155-164, https://doi.org/10.15407/geotm2022.163.155

10. Shevchenko, G.O., Cholyshkina, V.V., Sukharyev, V.V., Kurilov, V.S. and Lebed, H. B. (2023), "The rate of con-strained particles deposition in a wide range of suspension density in the laminar -turbulent operating modes", Geo-Technical Mechanics, no.164, pp. 103-116, https://doi.org/10.15407/geotm2023.164.103

 

About the authors:

Shevchenko Heorhii, Doctor of Technical Sciences (D.Sc.), Head of Department of Mechanics of Mineral Processing Machines and Processes, M. S. Poliakov Institute for Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it. , ORCID 0000-0002-8047-7014

Cholyshkina Valentyna, Candidate of Technical Sciences (Ph.D.), Senior Researcher of Department of Mechanics of Mineral Processing Machines and Processes, M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it. , ORCID 0000-0002-1612-5591

Kurilov Vladyslav, Junior Researcher of Department of Mechanics of Mineral Processing Machines and Processes, M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dniprо, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it. , ORCID 0000-0003-3202-9003

Lipska Halyna, Chief Designer of Department of Mechanics of Mineral Processing Machines and Processes, M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dniprо, Ukraine,   This email address is being protected from spambots. You need JavaScript enabled to view it. , ORCID 0009-0002-6370-8690

Havrosh Oleksandr, Leading Engineer of Department of Mechanics of Mineral Processing Machines and Processes, M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dniprо, Ukraine, pozltag7@ukr.net, ORCID 0009-0006-2292-9090