Sand Powder Research Articles

Influence of the Motion Behavior on the Contact Heat Transfer Between the Covered Wall and Solid Bed in Rotary Kilns

The effect of the transverse motion behavior on contact heat transfer was experimentally investigated in an indirectly heated batch rotary drum. Inside the drum, one rotating and one stationary measuring rod were installed, each assembled with 16 K-type thermocouples to measure temperatures. Thus, the radial and circumferential temperature gradients within the solid bed were measured, and the contact heat transfer was determined. As test materials, quartz sand, alumina, and cement powder were used, and the parameters filling degree (10–20%) and rotational speed (1–6 rpm) were varied.

Coupled fluid and solid evolution in analogue volcanic vents

AbstractVolcanic eruptions emit rock particulates and gases at high speed and pressure, which change the shape of the surrounding rock. Simplified analytical solutions, field studies, and numerical models suggest that this process plays an important role in the behavior and hazards associated with explosive volcanic eruptions. Here we present results from a newly developed laboratory‐scale apparatus designed to study this coupled process. The experiments used compressed air jets expanding into the laboratory through fabricated rock analogue material, which evolves through time during the experiment. The compressed air was injected at approximately 2.5 times atmospheric pressure. We fabricated rock analogues from sand and steel powder samples with a three‐dimensional printing process. We studied the fluid development using phase‐locked particle image velocimetry, while simultaneously observing the solid development via a video camera. We found that the fluid response was much more rapid than that of the solid, permitting a quasi‐steady approximation. In most cases, the solid vent flared out rapidly, increasing its diameter by 20 to 100%. After the initial expansion, the vent and flow field achieved a near‐steady condition for a long duration. The new expanded vent shapes permitted lower vent exit pressures and larger jet radii. In one experiment, after an initial vent shape development and establishment of steady flow behavior, rock failure occurred a second time, resulting in a new exit diameter and new steady state. This second failure was not precipitated by changes in the nozzle flow condition, and it radically changed the downstream flow dynamics. This experiment suggests that the brittle nature of volcanic host rock enables sudden vent expansion in the middle of an eruption without requiring a change in the conduit flow.

Influence of Hot Asphalt Concrete Preparation Technology on its Strength

<p>Asphaltic concrete is a composite material in which its mineral components: gravel, quartz sand and mineral powder is coupled by using bitumen. The experimentally determined that the quality of adhesion depends on the temperature at which all components had been mixing of hot asphalt mixes. However, the influence heating time remains unexplored. In this work the strength of compound was investigated on the samples of granite glued with using bitumen in a large range of temperature and time. It has been found that at a temperature of 140 degrees the strength increases significantly with time, but then starts to decline. The authors argue that the process of formation and destruction of adhesive compound bitumen and minerals can be described by the thermofluctuational theory of strength. Bitumen molecules on the boundary surface of the mineral become in a compressed state. The thickness of this layer can achieve 100 µm. The durability of road surfaces and the bond strength of all components asphalt concrete depends from quality of this indicator. Researches were conducted of the influence of the same temperature and time on the mechanical properties of the bitumen, but don’t found significant changes.</p>

The Research of Hydrolysis Test of Silicone Water Repellent for Protecting Reinforced Concrete

It is one of the measures of improving durability of concrete structure that apply silicone water repellent on concrete surface. The characteristic of silicone water repellent is to keep the respiratory function of concrete, not to change the original appearance of the concrete, have good hydrophobic performance and can resist to chloride ion penetration. This paper studies the hydrolysis of silicone water repellents solutions with different pH by measuring the electrical conductivity, pH value, and surface tension of the solution. The results show that silicone water repellent is hydrolyzing quickly very much. The hydrolysis time will extend with the increase of the concentration of silicone water repellent. By means of impregnating sand, rubble, cement pieces and calcium carbonate (CaCO3) powder with silicone water repellents, the water absorption at different temperature and humidity are studied and compared with the same material but not impregnated. The results indicate that the water absorption of impregnated material decreases and the silicone water repellent has hydrophobicity. The higher humidity can help hydrolysis and adhesion of silicone water repellent. The higher temperature may increase water absorption of base materials impregnated with low molecule weight silicone water repellent. Low molecule weight silicone water repellent liquid is residue on the calcium carbonate powder surface.

Silica Sand Powder Mixed with Slag Powder Complex Technology Used for PHC Piles Production

Design concrete mix used in the PHC pile production, silica sand powder and slag powder as a concrete admixture, replace a certain percentage of Portland cement, under the premise of meeting the PHC pile production requirements. After the steam curing, determinate the demould strength of concrete and after autoclave curing, determinatie the compressive strength of concrete. Test results show that it is feasible for the use of silica sand powder and slag powder instead of Portland cement , in which the proportion of concrete admixtures up to 45%. Silica powder and the amount of slag powder were mixed with 150 kg/m3, 50 kg/m3, the concrete demould strength up to 49.1 MPa and the compressive strength after autoclave up to 89.0MPa, to achieve requirements of the national standard GB13476 .

The effect of the Basset history force on particle clustering in homogeneous and isotropic turbulence

We study the effect of the Basset history force on the dynamics of small particles transported in homogeneous and isotropic turbulence and show that this term, often neglected in previous numerical studies, reduces the small-scale clustering typical of inertial particles. The contribution of this force to the total particle acceleration is, on average, responsible for about 10% of the total acceleration and particularly relevant during rare strong events. At moderate density ratios, i.e., sand or metal powder in water, its presence alters the balance of forces determining the particle acceleration.

Development of SVM rapid prototyping for scaffold fabrication

Purpose – This paper aims to introduce selective vacuum manufacturing (SVM), a powder-based rapid prototyping (RP) technique, and the ongoing development to improve its capability to apply in temporary scaffold fabrication. Design/methodology/approach – SVM employs a combination of sand casting and powder sintering process to construct a prototype layer by layer. A dense layer of support material is prepared and selectively removed to create a cavity where part material is filled and sintered to form a solid layer. In order for SVM to be considered for scaffold fabrication, besides preparing poly-lactic acid (PLA) for part material, support material preparation and process parameters identification have been studied. Redesigning of SVM machine to be more suitable for the real usage has also been presented. Findings – Particle size of salt has been controlled, and its suitable composition with flour and water has been determined. Process parameters have been identified to scale down the size of scaffolds to meso-scale and to achieve mechanical requirement. Properties of fabricated scaffolds have been enhanced and can be used for soft tissue applications. A prototype of the medical SVM machine has been constructed and tested. An examination of scaffolds fabricated on this new machine also showed their qualification for soft tissue application. Research limitations/implications – Further study will be on conducting a direct cytotoxicity test to provide the evidence for tissue growth before the clinical usage, on continuing to scaling down the scaffold size, and on improving SVM to meet the requirement of hard tissue. Originality/value – This simple, inexpensive RP technique demonstrates its viability for scaffold fabrication.

Mechanical behaviour of cement-treated sand

A study has been conducted to investigate the mechanical behaviour of cement-treated sand under compression and tension. Cylindrical and notched beam specimens were made by using high early strength cement, sand, and limestone powder with varying ratios of water to cement (W/C), specific ratios of cement to sand (C/S), and limestone powder to cement (L/C). The influences of the material strength and height to diameter ratio (H/D) on the compressive and tensile strength, as well as the fracture energy were investigated. Stress strain relationships are proposed to predict the behaviour of cement-treated sands.

Analysis of Structural and Microstructure of Lanthanum Ferrite by Modifying Iron Sand for Microwave Absorber Material Application

Analysis crystal structure of lanthanum ferrite by modifying iron sand has been carried out. Lanthanum ferrite included one of the functional materials which had composition of ABO3 perovskite system. The lanthanum ferrite is prepared by iron sand and lanthanum oxide powders. The mixture was milled for 10h with the various composition of lanthanum content. The samples are sintered at a temperature of 1000 °C for 10h. The microstructure analyses showed that the particle shapes was polygonal with the varied particle sizes and uniform distribution on the surface of the sample. The phase composition of refinement result showed that the lanthanum ferrite formed empirical compound of La0.8Mg0.2Fe0.7Ti0.2Si0.1O3. The La0.8Mg0.2Fe0.7Ti0.2Si0.1O3 phase has a structure orthorombic (P b n m) with lattice parameters a = 5.513(1) Å, b = 5.549(1) Å and c = 7.849(2) Å, α = β = γ = 90°, the unit cell volume of V = 240.2(9) Å3, and the atomic density of ρ = 6.293 gr/cm3. We concluded that this study has been successfully synthesized lanthanum ferrite material from modifying iron sand and has been understood changes in the parameters of the crystal structure and phase composition of this material. It was a great opportunity that the material can be used as a material candidate of absorber electromagnetic waves.

Active Fluidization Storage Applications for CSP

The current paper proposes three thermal storage concepts for solar thermal power plants, which are all based on sand powder as storage medium. The solid powder is used in a manner similar to fluid storage media such as molten salt. Fluidization is needed in order to produce fluid-like behavior of the powder. Applying powders as storage media for thermal energy storages offers advantages such as low cost, no freezing danger and hence no melting effort, no corrosion, local availability and high allowable temperatures. The storage media demand for all three concepts is estimated.

Research on Simulation Test of Coal Similar Material

In order to study the coal and gas outburst similar simulation experiment, coal similar material was made up based on the similarity theory. Based on the previous similar material study, the cement, sand, water, activated carbon and coal powder was selected as the raw material of similar material. Meanwhile similar material matching program with 5 factors and 6 levels was designed by using Uniform Design Method. And the physical and mechanical properties of the similar material compressive strength was measured under different proportions circumstances. The relationship between similar material and the raw materials was analyzed. The results show that choosing different materials can compound different similar materials with different requirements. And the water-cement ratio plays a decisive influence on the compressive strength of similar material. The compressive strength of similar material decreases linearly when the water-cement ratio increases.

Laboratory investigation on measuring suspended sediment by portable laser diffractometer (LISST) focusing on particle shape

This paper deals with a laboratory investigation on measuring suspended sediment volume and mass concentration (SSC) and particle size distribution (PSD) by a portable submersible laser diffractometer (LISST-100X) focusing on effects of particle shape and inversion modes on the results. Experiments were carried out in a mixing tank using suspensions of glass beads, fine quartz sand, feldspar and mica powder particles of spherical, rounded, angular and flaky shapes respectively, at various SSCs. SSCs and PSDs measured by LISST were compared to SSCs from gravimetric analysis and to PSDs obtained from image analysis of dry particles and from a non-portable laser diffractometer. Experiments using spherical and rounded particles showed that LISST with the corresponding inversion modes, i.e. spherical and ‘random shaped’, provides PSD and SSC values similar to reference methods. For angular and flaky particles, however, SSCs were found to be overestimated by factors of 1.5 and 8 respectively. Measurements in a mixture of 70% feldspar and 30% mica powders showed that the SSC overestimation factor for mixed particle-type suspensions can be predicted as the weighted sum of the SSC factors of the components and their mixing ratio. For known highly non-spherical particle types, LISST SSCs can be corrected by a gravimetrically determined or predicted overestimation factor. Moreover, correction of overestimated contributions of lower size bins, the range of measureable SSC and time averaging of LISST measurements are addressed. Further investigations are necessary to assess effects of non-spherical particles and mixtures of various particle types on LISST SSC and PSD estimates.

Phase behavior of methane hydrate in silica sand

Two kinds of silica sand powder with different particle size were used to investigate the phase behavior of methane hydrate bearing sediment. In coarse-grained silica sand, the measured temperature and pressure range was (281.1 to 284.2)K and (5.9 to 7.8)MPa, respectively. In fine-grained silica sand, the measured temperature and pressure range was (281.5 to 289.5)K and (7.3 to 16.0)MPa, respectively. The results show that the effect of coarse-grained silica sand on methane hydrate phase equilibrium can be ignored; however, the effect of fine-grained silica sand on methane hydrate phase equilibrium is significant, which is attributed to the depression of water activity caused by the hydrophilicity and negatively charged characteristic of silica particle as well as the pore capillary pressure. Besides, the analysis of experimental results using the Gibbs–Thomson equation shows that methane hydrate phase equilibrium is related to the pore size distribution of silica sand. Consequently, for the correct application of phase equilibrium data of hydrate bearing sediment, the geological condition and engineering requirement should be taken into consideration in gas production, resource evaluation, etc.

Effect of Ball Milling Methods on the Properties of Quartz Sand Powder Materials from the Yangtze River

In order to lay raw materials foundation for increasing the performance of insulating brick with the low grade quartz sand along the Yangtze River, the effect of ball milling methods on the properties of quartz sand powder was researched via the ball milling method in this paper. The results show the mean grain size of quartz powders are 11.25μm via a roller ball milling, the mean grain size of quartz powders are 7.37μm via a planetary ball milling, and the particle size distribution of quartz powders milled via a roller ball milling is wider than that of quartz powders milled via a planetary ball milling. The ball milling strength of planetary ball milling is higher than that of roller ball milling. The planetary ball milling use more electronic energy than the roller ball milling in the same time. The output of powder using the roller ball milling is more than that of powder using the planetary ball milling. when the raw materials of quartz building materials is low particle size remand, and the output is more, the roller ball milling methods is suitable to prepare the raw materials of quartz building materials.

Effect of Ball Milling Rotate Speed on the Properties of Quartz Sand Powder Materials

In order to lay raw materials foundation for increasing the performance of insulating brick with the low grade quartz sand along the Yangtze River, the effect of ball milling time on the properties of quartz sand powder was researched via the ball milling method in this paper. The results show the grain diameter of quartz sand powder is gradually decreased, the grain fineness distribution is tapered narrowing. The liquidity of quartz sand powders is became poor with an increaseding the ball milling rotate speed, howerver, the tendency of variation is gradually relaxative. The vibration compaction density is decreased with an increaseding the ball milling rotate speed, but the fall amplitude difference is gradually shrinked. The ball milling rotate speed for 250r/min is better through the whole cost performance analysis.

Dependence of thermal conductivity in micro to nano silica

This work presents the measurement of thermal conductivity of nano-silica particles using needle probe method. The validation test of thermal probe was conducted on ice and THF hydrates using our experimental set up and the results are satisfactory when compared with the literature data. The nano silica used in this study is with particle sizes in the range 50–1000 nm. The sand powders sieved in different sizes <75 and 75 μ m > d > 250 μ m were also studied to probe the particle size dependence on thermal conductivity. Thermal conductivity decreased by about 70% in silica nano powders.

Effect of a binder system on the low-pressure powder injection moulding of water-soluble zircon feedstocks

Abstract Micronized natural zircon sand powders were used as a raw material to conduct low-pressure powder injection moulding (LPPIM) processes. PIM could lead to new technological applications for this mineral, which has very stable dimensional behaviour with changing temperature. Zircon powders that have unconventional attributes for PIM (in terms of size and morphology) were mixed with poly(ethylene glycol) (PEG) based binders. Combinations of this water-soluble substance with different polymers, including low-density polyethylene (LDPE) and several types of acetate butyrate celluloses (CAB), were investigated. The influence of acetyl, butyryl and hydroxyl groups on the behaviour of the created feedstocks at different process stages and on the final piece properties were studied. The higher affinity of CAB with PEG and zircon powders compared with LDPE could result in improved densification and properties, but the butyryl, acetyl and hydroxyls groups affect the processability of these feedstocks.

The effect of geometric structure on stiffness and damping factor of wood applicable to machine tool structure

Stiffness and vibration damping capability are important criteria in design of machine tool structure. In other sides, the weight of machine tool structure must be reduced to increase the handling capability. This paper presents an analysis of the effect of geometric structure on stiffness and vibration damping of wood structure. The stiffness was analysed using numerical method, so called finite element method (FEM), while the vibration damping capability was experimentally tested. Vibration testing was also performed to wood structures with sand powder filled into its rectangular hole to observe the its effect on damping factor. Simulation results show that the cross ribs structure yielded minimum mass reduction ratio compared to the three square holes as well as the single rectangular hole structures. While the vibration test results explained that the damping factor of Shorea laevis wood was higher than that Hevea braziiensis wood. The use of sand powder as vibrating mass in closed-box structure effectively increased the damping capability, for single rectangular hole structure the damping factor was increased from 0.048 to 0.079 doi : http://dx.doi.org/10.12777/ijse.4.2.2013.57-60 [ How to cite the article: Widyanto, S. A., Widodo, A., Nugroho, S., & Siahaan, D. (2013). The effect of geometric structure on stiffness and damping factor of wood applicable to machine tool structure. INTERNATIONAL JOURNAL OF SCIENCE AND ENGINEERING , 4 (2), 57-60. doi: http://dx.doi.org/10.12777/ijse.4.2.2013.57-60 ]

Continuous float–sink density separation of lump iron ore using a dry sand fluidized bed dense medium

A continuous separator based on float–sink density separation using a gas–solid fluidized bed dense medium was used to upgrade iron ore. The separator has three devices for (A) conveying floaters, (B) recovering floaters, and (C) conveying and recovering sinkers. The optimum speeds of these devices were investigated using density adjusted spheres of the diameter=30mm in the range of 2400–3300kg/m3 in density increments of 100kg/m3. A mixture of zircon sand and iron powder was used as the fluidized medium to adjust the fluidized bed density to produce a separation density=2850kg/m3, a typical separation density for lump iron ore wet separation. The recovery of the spheres as floaters or sinkers depended on the speed of the devices, because the recovery was affected by the number density of spheres directly under the feeder, the local fluidized bed density, and flow currents in the medium derived from the movement of the devices. The optimum speeds were determined to be 3.5cm/s for (A), 2.0rpm for (B) and 1.0cm/s for (C), respectively. Continuous separation experiments were conducted on lump iron ore particles in the size range of +11.1–31.5mm in the fluidized bed with medium density of 2850kg/m3 and feed rate of 200kg/h. Comparison of the feed rate and the recovery rate indicated that the feed and the recovery were in equilibrium after 10min of operation. The experiments resulted in nearly perfect separation; 98.4% of the ore with density greater than 2850kg/m3 was recovered. The Fe, Al and Si content of the feed ore particles (before the separation) and the floaters and sinkers (after the separation) was measured using inductively coupled plasma spectrometry. The separator produced an upgrade in iron content of 3.3wt% and reduced the Al and Si content by 44%.

Cost-effective therapeutic hypothermia treatment device for hypoxic ischemic encephalopathy

Despite recent advances in neonatal care and monitoring, asphyxia globally accounts for 23% of the 4 million annual deaths of newborns, and leads to hypoxic-ischemic encephalopathy (HIE). Occurring in five of 1000 live-born infants globally and even more in developing countries, HIE is a serious problem that causes death in 25%–50% of affected neonates and neurological disability to at least 25% of survivors. In order to prevent the damage caused by HIE, our invention provides an effective whole-body cooling of the neonates by utilizing evaporation and an endothermic reaction. Our device is composed of basic electronics, clay pots, sand, and urea-based instant cold pack powder. A larger clay pot, lined with nearly 5 cm of sand, contains a smaller pot, where the neonate will be placed for therapeutic treatment. When the sand is mixed with instant cold pack urea powder and wetted with water, the device can extract heat from inside to outside and maintain the inner pot at 17°C for more than 24 hours with monitoring by LED lights and thermistors. Using a piglet model, we confirmed that our device fits the specific parameters of therapeutic hypothermia, lowering the body temperature to 33.5°C with a 1°C margin of error. After the therapeutic hypothermia treatment, warming is regulated by adjusting the amount of water added and the location of baby inside the device. Our invention uniquely limits the amount of electricity required to power and operate the device compared with current expensive and high-tech devices available in the United States. Our device costs a maximum of 40 dollars and is simple enough to be used in neonatal intensive care units in developing countries.