Doctor of Technical Science, Prof. Baidzhanov D.O., Sainov A.B.

Karaganda State Technical University, Kazakhstan

Evaluation of slag cohesive particles’ size grinded on Shock Pulse Meal (SPM)

In the General theory of shock - Shock Pulse is regarded as a measure of the mechanical interactions of bodies during the impact. Elementary acts of the collision of two atomic particles (i.e. atoms, molecules, electrons or ions) at which the constitution and the structure of nuclei do not change, the total kinetic energy of the colliding particles remains the same - it is only redistributed among the particles, and the direction of particles’ motion is changed. Collisions of atoms are determined by the transfer of phenomena in gases or in weakly ionized plasma.

Particles undergo scattering events in the collision of other particles. That prevent their free movement and thus prevents the increase of kinetic energy and temperature. The most significant influence on the movement of the particles is scattering events in which its direction of motion varies considerably. Therefore, the diffusion coefficients - the transfer of particles, momentum transfer, thermal conductivity - energy transfer, and other gas transport coefficients expressed in terms of effective section, collision, and the scattering atoms.

Grinding, manufactured at shock pulse mill is 50-80% higher than activation made on traditional equipment with the same granulometric size. This work was fully confirmed at the laboratory of Department “Technology of Construction Materials and products”. Shock pulse mill leads to an increase in specific surface of cohesive materials, change in the surface structure of particles, the appearance of physical defects in the sublattices and lattices of minerals that accelerate elementary interaction between layers and water. There is a reduction of time to achieve grade strength and a more complete use of the chemical energy of cohesive material.

Activation occurs when the rate of accumulation of defects exceeds the rate of their disappearance. This is implemented in the energy-loaded devices which create shock pulse. The design of the mill consists of two counter-rotating rotor, put on a separate coaxial shaft and encased. The rotors are located on the geometrical axis, each with a separate drive. There are rows of rods (finger-beat) so that every row of the fingers of one rotor can freely cross between two rows of fingers of the other rotor, arranged in concentric circles on the rotor shaft. Grinded material is delivered into the initial part of the rotor and moving to the periphery, it is subjected to the repeated hits of fingers, rotating at opposite directions. Each particle collides with an impact-finger consistently experiencing high-energy mechanical effects of impact, leading to rapid destruction of the material and reduces the fineness of grind.

The solid, having the same direction with the velocity vector of the finger, from which it was hit, crosses the trajectory with the second row of fingers which are moving in the opposite direction. Getting hit by the second row of fingers, the solid rebounds from it, changing the velocity vector, and ejected from the trajectory of the second series of fingers further, crossing the path of the third row. Such variable-opposite movement of grains of loose material and accordingly its grinding, continuous up until the grain will be thrown out of trajectory of the rotor.

A feature of this grinding method is the destruction of the material in the field of structural defects, as well as primarily a fragmented form of particles. Also, to the undoubted benefits of grinding and fine grinding in the Shock pulse mill may be included a small percentage of crushed material, no flakes, adhesions, clots and other neoplasms, usually occurring with increasing fineness of grinding, as well as self-cleaning effect of the casing of the material prone to adhesion. This pattern of motion occurs in an adiabatic process, which provides diffraction of microparticles in which the physical system does not receive a heat and does not give it, all this processes are running in the system, surrounded by heat-insulating (adiabatic) shell.

Due to the linear speed of 80 ... 320 m / sec and special impact-fingers process occurs so rapidly that during the time of its implementation heat exchange between the body and the environment (the system) does not happen. At such speeds, the compression of gas occurs by shock pulse and sequentially the scattering of electrons, neutrons, atoms and other microparticles and destroyed particles are created form the initial particles, the direction and intensity of which depends on the structure of the scattering object. In the interaction of particles with the crystal, the energy of the molecule is changed: it added to the potential energy of this interaction, which leads to changes in particle motion and therefore change the nature of the spread of the associated wave, this is in accordance with principles common to all waves. At the same time the gas has no time get rid of the released heat and its temperature increases (boundary heating is not yet established).

To estimate the size of the particles of given cohesive was carried out electron microscopy with help of “TASKAN” microscope and "Morphology" software module.

An area of 452.4 square micrometers was randomly selected in the sample. Fig. 3 and 4 shows the results of "delineation” of the particles obtained with the help of the "Morphology" software module. Particles are colored differently, according to their areas (table that corresponds to the areas and the colors shown in Fig. 5). Particles directly attached to the borders of the image are not classified, as they are shown in the picture not completely.

363 particles were analyzed in total, and for each of them three morphological parameters have been calculated: length, width and area.

Table 1. Morphological parameters of the particles cohesive material.

	Area, µm^2	Length, µm	Width, µm
Average	541,238	27,900	22,117
Standard deviation	666,396	20,105	16,851
Minimum	1,567	1,770	0,885
Maximum	4097,242	86,690	76,511

From the above we can conclude that using a mill of the shock pulse is increased activity of the cement crushing particles of material to the micro and nano dimensions. This allows us to accelerate the elementary interaction layer of material (particles) with water. Increases the speed of hydration and through more compact packing structure of the concrete strength increases markedly.

Fig. 3 Randomly chosen sample area, equals 462.4 µm^2	Fig. 4 Contouring of the particles on the image have done with the help of software module “Morphology”. All particles are given by various colors in compliance with their surface area
Fig. 5 Equivalence between particles’ color (Fig. 4) and their size range, µm^2

Fig. 6 Placement of particles by the area (along the axis OY placed amount of particles with given area)

Fig. 7 Placement of particles by length (along the axis OY placed amount of particles with given length)