Papers by Keyword: Fine Particle

Abstract: The influence of the fine particle content on the rheological properties of the fresh concrete mixture was studied. The change of cement together with sand particles up to 0.25 mm in mixture composition was taken into the consideration. The amount of fine particles in mixture composition varied in the range from 402 to 639 kg per one cubic meter of the concrete mixture. Technological properties of the concrete mixture were established according to the standardized requirements, rheological properties: yield stresses and viscosity of conventional concrete mixture were calculated based on analytical formulas. According to obtained test results, the increase of fine particle content from 481 to 520 kg in mixture reduced the yield stresses from about 557 to 132 Pa. Further increase of fine particle content from 600 to 639 kg showed the rise of yield stress by 3.87 times. On the other hand, the viscosity of concrete mixture gradually decreased (ca. 5.6 times). To sum up, the rheological properties of the concrete mixture were significantly influenced by the content, packing density, fineness, surface texture and particle size distribution of fine particles.

Abstract: Drying is an important way to improve the quality of lignite with high moisture. In this paper, a single-shaft paddle dryer experimental system was built to investigate the drying characteristics of fine-particle lignite with diameter 0-5mm. The experimental results show that with the increasing in shaft rotation speed the flow rate of lignite increases linearly approximately and the residence time decreases correspondingly. Increasing the inclination angle of dryer frame helps increase the flow rate. Both shaft rotation speed and heating source (heat transfer oil) temperature have significant effects on outlet moisture content of lignite. Shaft rotation speed affects the average heat transfer coefficient greatly and heating source temperature affects it weakly for specified conditions. It is found that for 5-12mm coarse-particle lignite, flow is not smooth and the average heat transfer coefficient is much less than that of fine-particle lignite. This research shows that it is feasible technically to dry fine-particle lignite by using paddle dryers, but not suitable to dry coarse-particle lignite.

Abstract: The study was performed with male Wistar rats who individually received nano (NPs) or fine (FPs) titanium dioxide (TiO₂) particles with an attractive food for 7 days. Two doses of TiO₂ NPs (200 and 400 mg/kg) and one dose of TiO₂ FPs (200 mg/kg) were used. The macroscopic status of the gastric mucosa as well as the pro-and antioxidant activity of the adherent mucus layer were examined. Our experiments showed that a chronic (7-day) oral administration of TiO₂ nanoor microparticles increased the area of erosive lesions and the amount of mucosal hemorrhages with respect to control. However, the damage mechanisms in the group “TiO₂ FPs 200 mg/kg” were different from those in the groups “TiO₂ NPs 200 mg/kg” and “TiO₂ NPs 400 mg/kg”. The oxidative damage of glycoproteins occurred in the gastric mucus of animals who received TiO₂ NPs; this led to degradation of the adherent mucus layer and deterioration of its protective properties. Therewith, a dose-dependent reaction was not observed at the indicated doses of TiO₂ NPs. The oxidative damage of glycoproteins was not found in the gastric mucus of animals who received TiO₂ FPs; erosive lesions and mucosal hemorrhages could be induced by TiO₂ FPs as the mechanical and chemical agent that does not provoke oxidative stress at the indicated dose. Our study demonstrated that the use of TiO₂ in any form for increasing the attractivity of foodstuffs can be harmful for the digestive tract.

Abstract: Bag filter is one of the most effective methods of dust catcher, and the filter medias is the core part of bag filters. In this paper, we studied the filtration performance of several common filter medias comparatively through experimental methods, and the results can provide certain basis for the dust removal performance improvement of filter medias.

Abstract: It is the most effective way to study the effect of global warming on plant morphology by analyzing a plant species on a mount along altitudinal gradients. Altitudinal increase means decrease of temperature and metabolic rate as well. This might affect the leaf morphology greatly. The SEM study reveals that the size of nanopore on the epidermis changes gradually along altitudinal gradients, and the absorbed fine particles on the leaf have almost same size, exhibiting high selectivity over other particles. The study gives a strong proof that morphology change links to global warming.

Abstract: Particles come in a wide range of sizes. Fabric filter with different structure shows different filtration performances on fine particle. In the paper, two types of filter media structure, i.e. non-woven structure and membrane structure are compared and studied. It can be seen that the pressure drop of membrane filter is apparently much higher than that of non-woven structure for it owns a density membrane. Membrane structure gives apparently higher efficiency for fine particle than non-woven structure.

Abstract: Adsorption of fine particles in air by a leaf is studied experimentally. It is found that each leaf can absorb only a kind of particles with almost same size, and it also exhibits high selectivity over other particles. The SEM study reveals that the size of nanopore on the epidermis is a main factor of the highly selective adsorption; the smaller nanopores can absorb larger nanoparticles in air. The morphology of a lotus leaf, which is waterproof and dustproof, has, on the other hand, many short nanofibrils instead of nanopores. It is concluded that the nanoscale geometrical structure of a surface affects its attraction/repulsion property. The experiment also shows that one square millimeter surface with nanopores in diameter of 18 nm can absorb 2 million nanoparticles of about 200 nm in diameter from air in 24 hours. A better understanding of the adsorption/repulsion mechanism could help the further design of bio-mimetic waterproof/dustproof artificial materials and artificial porous materials/fabrics/nonwovens for adsorption of nanoparticles in air.

Abstract: The fine oolitic hematite ore (<20µm) is easily covered by the ore slime, therefore, it is processed very difficultly with traditional crafts, for example, gravity treatment, magnetic separation, and flotation. The tiny iron ore is unable to recycle effectively, bring about a large of useful minerals running off. It is indicated that the selective flocculation is effective separation craft in many research works. The good dispersion of fine particles is the selective flocculation essential condition, the excessive dispersion will destroy the selective flocculation, at the same time it can be influenced by the water quality, pH, the mixing time, the shear rate and the dispersing agent dosage. In this paper, to oolitic hematite ore, the chemistry dispersion research is conducted to provide the foundation for further selective flocculation separation.

Abstract: Industrial dust emission is one of the main sources of fine particle especially for PM2.5 in atmosphere. Filter media is the key component for baghouse. In the paper, several normal needle felt filters and membrane filter are studied through experiments. The performances of filter such as resistance, capture efficiency for total particle and number counting efficiency for fine particle are tested.The experimental results show that the resistance of filter increase after aging, the resisitance increasing rate of membrane filter is the smallest; The efficiencies for total particles of normal filter are above 99.9% at clean state, and 99.99% at stable state after aging; Although the filters have high efficiency for total particle, but the number counting efficiency for 10μm particle is 94%-99%, and 52%-92% for 2μm particles. New filters for fine particles are needed.