Effect Of Granulometric Composition Research Articles

Effect of Granulometric Composition of the Soil on the Occurrence of Carrion Beetles (Coleoptera: Silphidae)

The entomological material was collected in the years 2009–2012 and 2014 from 13 different habitat types from three localities in south-eastern Poland. In total, 11,095 Silphidae were collected. This study examined whether the percentage of individual soil granulometric fractions was significantly related to the total abundance of collected Silphidae and individual carrion beetle species. A positive correlation and a statistically significant correlation were found between the total number of specimens collected and the share of the mechanical fraction with a diameter of 0.05–0.002 mm (silt fraction). In three species, a statistically significant correlation was demonstrated between the number of collected Silphidae and the share of the mechanical fraction with a diameter of 2–0.05 mm (sand fraction). The two species Phosphuga atrata atrata and Nicrophorus vespilloides the correlation was positive. A statistically significant relationship was also observed for Thanatophilus sinuatus, but the correlation was negative. With regard to the mechanical fraction with a diameter <0.002 mm (clay fraction), a statistically significant relationship was demonstrated for Oiceoptoma thoracicum and for Nicrophorus vespilloides for which the correlation was negative. However, a positive correlation was found for T. sinuatus in this case.

Study of the effect of vibrocompaction modes, shape of particles and their size distribution on packing density

The results have been described of experimental studies of the influence of vibrocompaction modes, shape of particles and their size distribution on the relative package density. The glass spheres with diameters distributed from 0.4 to 0.9 mm and from 0.63 to 0.8 mm, containing a fraction of nonspherical particle inclusions of about 30 % have been taken as the research object. Also in the experiments the powder was used of electrocorundum with particle size of 0.63-0.8 mm. This choice was aimed at bringing the particles characteristics to those of a real granular material and no separation of particles into spherical and non-spherical was planned. The experiments on vibrating packing have been performed with the help of dynamic “Revolution” powders rheometer. The modes of compaction vibration varied over a wide range of frequencies and amplitudes: from 5 to 475 Hz and from 106 to 1062 µm, respectively. The vibration frequency has shown to exert a greater effect on relative density as compared to that of the amplitude. The dependence of relative density on vibration frequency exhibits several local maxima for all vibration amplitudes. The maximum relative packing density of 0.64 ... 0.65 is achieved at a combination of high amplitude (850, 1062 µm ) and high frequency (300 ... 350 Hz). Effect of granulometric composition on relative packing spheres density is less pronounced than that of the vibration frequency and approximately equals to than of the amplitude. Increasing the deviations of the particles size is accompanied by increasing frequencies leading to maximum packing density. The particles shape affects the level of packing density, thereby remaining the same character of dependence of relative density on vibration frequency for both spherical and non-spherical particles of similar particle size distribution.

Investigation of pelletization stage and its role in the formation of catalyst quality indices

The results of complex and systematic investigations of the pelletization stage are generalized by the example of commercial Cu-Zn-Al catalysts of carbon conversion (SNK-2) and methanol synthesis (SNM-U) produced during a period of 1.5 years. Flowability of precipitated Cu-Zn-Al catalyst masses at different stages of their preparation for pelletization as well as the effect of granulometric composition on the flowability are studied. Flowability of the catalyst mass is shown to depend, first of all, on the concentration of the fine fraction (<0.25 mm): it increases with a decrease in the number of fine particles. The statistical data which characterize nonuniformity of the height, diameter, mass and strength of the pellets of commercial SNM-U and SNK-2 catalysts are obtained for 600–1000 pellets (Performance Specifications (TU) provide for estimating the average values based on 30 pellets). The effect of the compacting pressure on the mechanical strength, density, and bulk weight of the pellets is investigated. The effect of the mass humidity and duration of the compacting force increase on the pellet mechanical strength is demonstrated. The coefficient of a linear dependence of the pellet size increase after the compacting load is removed is experimentally determined for precipitated Cu-Zn-Al disperse masses. A porous structure of pellets with different strengths is investigated. The activity of SNM-U and SNK-2 samples produced at different compacting pressures, whose pellets differ in density and strength, is determined. The present study has resulted in specifying the admissible amounts of water and graphite introduced into the process of pelletization. The revealed laws allow producing changes in the existing process regulations for catalyst production at the stage of pelletization and adjusting parameters of the manufacturing process to provide for optimal indices of catalyst quality and to avoid spoilage. The obtained data can be used for designing engineering equipment and pelletization machines.

Filtration through hydraulic embankments made of colliery spoil: model tests

Model embankments made of colliery spoil and fuel ash were investigated in a hydraulic channel. Seven models of colliery spoil with or without additional sealing elements from the ash, as well as one of ash itself, were constructed. The effect of granulometric composition, compaction, different types of sealings, and the silting-up process on embankment perme ability was ascertained. Embankment slope stability was also analysed with respect to seepage pressure and strength param eters of the slope material. The effect of granulometric com position, thickness of sealing elements, and silting-up on water seepage through the embankments was significant. On the other hand, compaction had less influence than the above mentioned factors. The effect of seepage pressure on slope stability of the embankment made from fuel ash was failure. General recommendations for building hydraulic earth structures using the materials investigated are pre sented.