On the question of the appointment of separate parameters of the roadheaders gathering-stars loading organs

Most modern roadheaders of selective action are equipped with loading devices with gathering-stars, which have a simpler drive design and increased reliability. As a result of the experimental studies carried out at SRSPU (NPI), it was found that under certain conditions, it is possible to transfer large lump material of a pile into a fluidized state, which reduces the energy consumption of material loading. An increase in the number of beams of the gathering-stars reduces the influence of the other parameters of the loader. Analysis of the process of interaction of the gathering-star’s beam with the receiving conveyor’s side edge to avoid jamming of the picking gathering-star by a lump of material with the implementation of high dynamic loads, it is necessary to set the gathering-beams at an angle of at least 60 degrees against rotation.

Stages of technological process of high anisotropy formation of magnetic properties under «dry» pressing of powder products

The article proposes the description of technological production process of anisotropic products from powders of high materials which provides powders preparation and products made of them. It has been shown that the main drawback of «wet» pressing technology is low accuracy at dosing wet charge. To eliminate warping and cracking of briquettes obtained by «wet» pressing during the sintering, they are subjected to air drying at room temperature within 48-72 hours. However, the percentage of product failure due to mechanical and magnetic characteristics remains high. Practically all the drawbacks of «wet» pressing can be eliminated by reverse to dry powder pressing, which allows to obtain low mass magnets without additional final finishing machining, to avoid warping and cracking of the product, and to reduce sintering time. Nevertheless, under the dry powder pressing the magnetic characteristics of products are significantly lower than under the wet pressing. When working with disperse materials, a promising direction is to converse them into fluidized state. To obtain the fluidized state of powder materials, vibrational technologies are used, involving the transfer of a wide range of energy to the powder material, i.e. mechanical, acoustic, electric and magnetic energy.

Effect of microstructural anisotropy on the fluid–particle drag force and the stability of the uniformly fluidized state

Lattice-Boltzmann simulations of fluid flow through sheared assemblies of monodisperse spherical particles have been performed. The friction coefficient tensor extracted from these simulations is found to become progressively more anisotropic with increasing Péclet number, $Pe= \dot {\gamma } {d}^{2} / D$, where $\dot {\gamma } $ is the shear rate, $d$ is the particle diameter, and $D$ is the particle self-diffusivity. A model is presented for the anisotropic friction coefficient, and the model constants are related to changes in the particle microstructure. Linear stability analysis of the two-fluid model equations including the anisotropic drag force model developed in the present study reveals that the uniformly fluidized state of low Reynolds number suspensions is most unstable to mixed mode disturbances that take the form of vertically travelling waves having both vertical and transverse structures. As the Stokes number increases, the transverse-to-vertical wavenumber ratio decreases towards zero; i.e. the transverse structure becomes progressively less prominent. Fully nonlinear two-fluid model simulations of moderate to high Stokes number suspensions reveal that the anisotropic drag model leads to coarser gas–particle flow structures than the isotropic drag model.

Extended Validation of a Model of Segregating Fluidization of Homogeneous Two-Solid Beds

In the industrial processes that employ the fluidized bed technology (gasification of coal or biomasses, polymerization, etc.), solids of various kinds are simultaneously subjected to fluidization. Due to the fact that solids that differ in density and/or size differently react to the frictional force exerted by the gas stream, mixtures of two solids tend to form, when fluidized, segregated layers rich in either of their components. A peculiar case, in this frame, is that of homogeneous mixtures whose denser component is also the smaller one and achieves the fluidized state at the bottom of the column, while the other solid, bigger and lighter, forms a packed layer on top of it.With reference to this special type of binary systems, several series of experiments are presented that provide their initial and final fluidization velocities at varying composition. Following what done in a recent study on beds of two solids differing in density or size, it is shown that the theoretical equations for calculating uif and uff keep their validity even when applied to mixtures that exhibit an unusual fluidization pattern. Calculated values of the initial and final fluidization velocities are characterized by a low error level, fully comparable with that encountered with other types of binary beds.

Principle and Applications of Grinding Wheel Regenerator

Grinding wheel regenerator is composed of grinding wheel, fluidized bed, airblower, motor and dust-removal system. After being put into regenerator, used-sand is in the fluidized state under the action of airflow. Grinding wheel, buried into sand, rotates with high speed. During above process, strong collision and friction are caused between sand and high-speed rotating grinding wheel, machine body and sands, which make adhesive film peeled off and used-sand regenerated. The paper introduces operation principle of grinding wheel regenerator and studies experimentally about the influence of regenerator’s rotate speed on sand breakage rate. The study reveals that rotate speed has effect on breakage rate of reclaimed sand. Sand breakage rate increases with the raising of rotate speed.