Anna Sandulyak

Magnetic separation of raw materials for glass and ceramic production: problems of ferruginous impurity control (review)

A large mass of data on magnetic separation of raw materials for the production of glass and ceramic is generalized using a key indicator — the separation efficiency (relative decrease of the ferruginous impurity content); the unsystematic variation of the data is determined. It is established that the results of conventional control (in terms of a “single” form of impurity Fe2O3), though providing a basis for judging the presence of a formal concentration dependence, nonetheless do not permit logical systematization of the accumulated mass of data by evaluating media with respect to their “proneness” to separation and evaluation of separators according to their address preference. The method of magnetic control is recommended for purposeful control of impurities which are active in a separator.

On the Issue of Choosing the Measuring Zones in a Faraday Balance When Studying Magnetic Susceptibility of Small Samples

By the example of polar pieces of spherical, conical and truncated conical shape, we substantiate and implement the approach to identifying a local, spatially limited, working zone (to position and examine magnetic susceptibility of ‘microsamples’) for the Faraday balance, viz. the zone with stable inhomogeneity of the field. It involves obligatory obtaining and analyzing coordinate characteristics of induction (intensity) in the interpolar area, at this, sinuous characteristics, i.e. the ones with an inflexion, should be give preference to out of the traditional nonlinear characteristics. Then, the well-linearized zone near the inflexion point (the corresponding derivative here demonstrates an extremum) most fully satisfies the requirement (to a working zone) for preserving the field inhomogeneity constancy. It is established that in comparison with the spherical polar pieces, the conical ones provide a working zone that is closer to the axial line, whereas the truncated conical polar pieces ensure the zone farther from their axial line.

Definition of Pore Tortuosity in Granular Medium Ply Based on Model of Quasi-Faceted Cells and Pore-Tubes

An approach to obtaining data on the tortuosity kZ of polyspherical media with ordered packing of spheres, characterized by definite values of the porosity ω and/or packing density γ, is shown using models of quasi-faceted cells and tubular pores. Presented in the form of graphical and analytical dependences these data make it possible to judge the value of kZ for a granular medium on the basis of the actual value of ω and/or γ for it.

Modeling of Tubular Pores in Free-Flowing Bulk Media on the Basis of Quasi-Facetted Cells of Such Media

On the basis of an unconventional model of quasi-facetted cells, which are responsible for the ordered structure of spheres, the possibility of modeling pores of such media (and on their basis different granular, grainy, powder media also) in the form of volume-equivalent cylindrical channel-tubes of definite diameter depending on the porosity of the medium (or its packing density) is examined.

Model of Quasifaceted Cells and Possibility of its Application to Free-Flowing Materials

A model of the ordered packing structure of free-flowing media (spheres) with cells in the form of conventionally cut-out (quasifaceted) parallelepipeds, whose vertices are located at the center of eight neighboring granules- spheres, is studied. Power-law and exponential dependences of the coordination number of the granules- spheres on the packing density γ and porosity ω of the medium are presented. More precise linear and nonlinear dependences are presented for comparatively narrow ranges of γ and ω which are characteristic for filling-media.

Results of Magnetic Control of Iron Impurities in Feldspar

It is shown that the empirical operating mass characteristic for magnetic control of iron impurities in feldspar plotted in semi-logarithmic coordinates contains a ‘kink’. A variant is given for obtaining information about the actual mass fraction of iron impurities, taking account of the iron impurity not separated after a finite number of control operations.

Magnetic Monitoring of Iron Impurities in Petroleum Products: Determination of Limiting Rate in an Analyzer

It is noted that the existing methods of magnetic monitoring of iron impurities in petroleum products need refinement, including validation of the specimen flow rate limits in the analyzer. Based on a simplified condition for the competition between magnetic and hydrodynamic forces, an expression has been derived to determine the limiting specimen flow rate in the analyzer. It is shown that the rate depends parabolically on the ratio of the size of the iron particle to the distance to the source of the field of the magnetic system in the analyzer.

Applied Model of Magnetization of a Granulated Material

Results of researches (of magnetic permeability) of elementary effective magnetic channel in porous (granulated) material are given. Such results permit to calculate a relative intensity of field between the grains.

Ferrous Material Fill: Magnetization Channels, Layer-by-Layer and Average Permeability, Element-to-Element Field

For the magnetic samples of heterogeneous (including bulk) ferrousmaterials, a qualitative, and according to the data on the demagnetization factor N of finely dispersed samples quantitative assessment of the volume fraction is provided for the characteristic intervals γ of the ferrous component. There are three intervals: the first one is γ ≤ 0.2, the second one is 0.2 0.4–0.45 (up to \( \gamma \cong 0.6 \) for a material filled with “densely packed” granules or grains). It should be noted that samples of heterogeneous ferrous materials within the third interval γ, according to the stabilization of N and its proximity to the N-value for a uniform sample (which indicates a “magnetic splicing” of the ferroelements in the heterogenous material), possess the features of a uniform magnetic sample and, therefore, they fully correspond to the notion of a quasi-uniform object. Special attention is paid to filling of granules or grains (with their inherently stable value of γ) as a completely independent class of heterogeneous ferrous materials.

Convergence Check of Data from Step-by-Step Experimental-Computational Magnetic Control of Iron Impurities in Raw Materials Using Different Field Sources

The mass-operational characteristics of magnetic control of iron impurities in raw materials (silica sand, feldspar, gypsum), following an exponential law both fully and partially (tail section), when an experimental-computational model of control of iron impurities is possible taking account of the appropriate corrections, are analyzed. It is shown for different sources of the field that the results of magnetic control performed with a limited number of operations differ considerably between one another while for an unlimited number of operations (operational-computational method) they remain practically identical even though the form of the mass-operational characteristic changes.