Analytical studies on constrained particle settling velocity in a water suspension of fly ash from thermal power plants

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V.P.Nadutyi,, Institute of Geotechnical Mechanics named by N.Poljakov, Dnipro, Ukraine, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

V.S.Kurilov,, Institute of Geotechnical Mechanics named by N.Poljakov, Dnipro, Ukraine, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

O.G.Cholyshkina,, Interregional Academy of Personnel Management, Kyiv, Ukraine, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

V.F.Hankevych,, Dnipro University of Technology, Dnipro, Ukraine

повний текст / full article

Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu. 2021, (1): 032 - 038


To establish analytical dependences for calculating the characteristics of the ash suspension and the velocity of constrained settling of coal and quartz depending on the particle size and density of the medium, which is necessary for calculating the design and determining the operating modes of hydraulic devices for extracting coal from water mineral suspension of fly ash from thermal power plants.

The research was carried out on the basis of a cellular suspension model and classical concepts of constrained particle motion in laminar and turbulent flow. For analytical evaluation of the characteristics of the suspension, the defining correlations and the Wend formula for viscosity were used. The Ergun equation and correlation analysis methods were used to calculate and analyze the speed of constrained movement of ash suspension particles.

Approximating nonlinear functions are obtained for determining the speed of constrained movement of coal and quartz particle size up to 4 mm in an ash suspension with a density of 1.31.8 g/cm3. It is shown that, for both settling and ascending of coal, there is a direct relationship between the velocity and particle size, in both cases it is nonlinear. For any coal size, the speed of ascent depending on the suspension density is of extreme nature; the rational density range is 1.551.8 g/cm3 with a maximum of 1.65 g/cm3. The established dependencies allow us to determine the size of coal and quartz particles, taking into account the counter-flow of the liquid phase, as well as the boundary size.

For the regime of weak-turbulence flows there were established dependences and approximation equations of the constrained movement speed of coal and quartz particles the main components of the water suspension of fly ash from the Novo-Kramatorska TPP, depending on the size and density of the ash suspensions with changes in the characteristics of the medium depending on density. The frames of the Stokes description of processes are established. It is shown that the movement of the liquid phase in a counter-flow with precipitating particles is effective for surfacing of thin coal classes.

Practical value.
The described approach can be used for analytical evaluation of the characteristics and velocity of constrained movement in various water suspensions of discrete solid particles in weak-turbulence flows. The advantage is a wider coverage of hydraulic equipment operating modes. The results obtained are necessary for designing and determining the technological modes of operation of various hydraulic devices in the technology of complex processing of fly ash from TPPs.

mineral suspension, fly ash, density, velocity, settling, ascend


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