Dopad změny frikčních parametrů do úpravárenského procesu

Abstract

The properties of the bulk material affect the transport, storage, and handling of the bulk material. It is therefore essential to know the parameters that affect these properties. Particle size, moisture content and particle shape are the basic parameters that can influence the above. Therefore, this paper focuses on the effect of changing these parameters of the bulk material. The regularity of change in moisture content and shape of the bulk particle was evaluated for 5 different particle size fractions. When moisture content was determined in the range of 0-30% and shape was assessed after grinding. For this purpose, the study deals with the measurement of mechanical and physical properties focusing on the angle of internal friction and flowability. Due to the different bulk storage pressures, measurements were made for four different normal loads. The findings were subsequently applied to research in the field of separation treatment using sieving technology. The effect of moisture content variation on the particle drop through the sieve mesh was investigated with respect to the change in size fraction and amplitude of the oscillation. The findings were applied to the material recycling process of tennis court surfaces composed of clay material. From the measured and evaluated data, the effect of the change in moisture content of the bulk material was most pronounced at the smallest size fraction, where even a very small change in moisture content of a few tenths of a percent steeply affected the flow rate as a function of internal friction. After an increase in moisture content of the order of percent, the flow condition stabilized. A threshold value was established above which water in the bulk material caused an improvement in flow properties and a reduction in the internal friction angle. For the larger size fractions, on the other hand, the effect of moisture content change was only apparent at their higher values (12.5%) and even at 30% there was no change in behavioral character. The effect of the change in normal load, on the other hand, becomes more pronounced with increasing particle size, which can be seen in the change in the character of the flow rate dependence on the angle of internal friction for the 1-1.4 mm fraction. The behavior of the bulk material during sieving reproduces the above results and thus establishes a measure of the efficiency of the process. The final recycling of the material shows deviations from the original material in the form of a reduction in the compressibility of the material.