scholarly journals Explosion Pressure and Minimum Explosible Concentration Properties of Metal Sulfide Ore Dust Clouds

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yun-zhang Rao ◽  
Chang-shun Tian ◽  
Wei Xu ◽  
Chun-yu Xiao ◽  
Bo-yun Yuan ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulfur Content ◽  
Metal Sulfide ◽  
Explosion Hazard ◽  
Factors Affecting ◽  
Explosion Pressure ◽  
Dust Clouds ◽  
Sulfide Ore ◽  
Before And After ◽  
Concentration Properties

The explosion pressure and minimum explosible concentration (MEC) properties of metal sulfide ore dust clouds are valuable for the prevention and control of metal sulfide ore dust explosions. In this study, a 20 L explosion sphere vessel was used to investigate the effect of sulfur content, particle size, and concentration on the explosion pressure and minimum explosible concentration of metal sulfide ore dust clouds. Four samples with different sulfur contents were selected (30%–40%, 20%–30%, 10%–20%, and 0%–10%). Before and after the explosion, samples were tested by X-ray diffraction. The results indicate that the metal sulfide ore dust is explosive dust with St1 grade explosion pressure. With an increase in concentration, the maximum explosion pressure increased at first and then decreased. With an increase in sulfide content, the explosion pressure of metal sulfide ore dust increased, while the minimum explosible concentration decreased. As particle size decreased, the MEC also decreased. The sulfur content, particle size, and concentration of metal sulfide ore dust were the main factors affecting the explosion hazard.

Factors Affecting Sulfur Reactions in High Sulfur Oil Shale Pyrolysis

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Omar S. Al-Ayed ◽  
Moh’d Matouq
Keyword(s):  
Particle Size ◽  
Water Vapor ◽  
Sulfur Content ◽  
Oil Shale ◽  
Operating Pressure ◽  
Shale Oil ◽  
Factors Affecting ◽  
X Ray ◽  
Oil Shale Pyrolysis ◽  
Sweeping Gas

Oil shale samples from the Ellajjun area south of Jordan were pyrolyzed in different conditions and environments. Sulfur of shale oil was determined using x-ray fluorescence (XRF). Generated products swept from the retort by several sweeping media; they include nitrogen, water vapor, hydrogen, and mixture of nitrogen and water vapor. Other conditions are 2–11 mm particle size, 1 atm operating pressure, and 410–550°C temperature range. The sulfur content of shale oil was found to be 12 wt % for hydrogen pyrolysis, while water vapor at 1 atm decreased this value to 7 wt %. Hydrogenation of oil shale resulted in 12 wt %. the sulfur content of shale oil being at 420°C, and then reduced to 10.3 wt % at temperatures higher than 470°C. When water vapor is added to nitrogen, the sulfur in the oil shale is increased by 4 wt %. Water vapor sweeping gas increased the sulfur of the shale oil from 6.5 wt % to 8.1 wt % compared with a nitrogen pyrolyzing medium. Retorted shale analysis showed 44 wt %, and 31 wt % is left in the retorted shale of the original 4.5 wt %. Sulfur found in the raw oil shale is unretorted for nitrogen and hydrogen sweeping gases. On the other hand, increasing particle size from 2 mm to 11 mm did not have any significant influence on the sulfur content of the produced shale oil.

scholarly journals Study of Explosion Characteristics of the Wheat Flour Dust Clouds in Dependence of the Particle Size Distribution

2019 ◽  
Vol 27 (44) ◽  
pp. 65-71
Author(s):  
Richard Kuracina ◽  
Zuzana Szabová ◽  
Eva Buranská
Keyword(s):  
Particle Size ◽  
Wheat Flour ◽  
Pressure Rise ◽  
Median Particle Size ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
Dust Clouds ◽  
Median Particle ◽  
Flour Dust

Abstract Fire protection is an important part of the industry where flammable and explosive dusts are found. Production, storage and transport of food powders such as flour can be very dangerous in terms of explosiveness. The article deals with the measurement of explosion characteristics of wheat flour dust. The measurements were carried out according to EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds and the maximum rate of explosion pressure rise according to EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds. A sample of wheat flour with a median particle size 84 μm exhibits the maximum explosion pressure 7.00 bar at the concentration of 600 g.m−3 and then explosion constant is 16.9 bar.s−1.m. A sample of wheat flour with a median particle size 50 μm exhibits the maximum explosion pressure 7.97 bar at the concentration of 1000 g.m−3 and the explosion constant 54.9 bar.s−1.m.Based on the results of the measurements, we found that the particle size distribution has a significant influence on the explosion parameters of the wheat flour samples.

scholarly journals Study of Explosion Characteristics of Wood Dust Clouds in Dependence of the Particle Size Distribution

2017 ◽  
Vol 25 (40) ◽  
pp. 17-23 ◽  
Author(s):  
Richard Kuracina ◽  
Zuzana Szabová ◽  
Matej Menčík
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Maximum Rate ◽  
Pressure Rise ◽  
Wood Dust ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
Dust Clouds

Abstract The article deals with the measurement of explosion characteristics of wood dust. The measurements were carried out according to STN EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds and the maximum rate of explosion pressure rise according to STN EN 14034-2+A1:2012 Determination of explosion characteristics of dust clouds - Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds. On the basis of measurements, we found that the distribution of the particles has a significant impact on the parameters of wood dust samples.

scholarly journals The Maximum Explosion Pressure of Lignite in Dependence on Particle Size

2019 ◽  
Vol 27 (44) ◽  
pp. 57-64
Author(s):  
Richard Kuracina ◽  
Zuzana Szabová
Keyword(s):  
Particle Size ◽  
Coal Dust ◽  
Underground Mines ◽  
Explosion Pressure ◽  
Maximum Explosion Pressure ◽  
Dust Clouds ◽  
Potential Safety ◽  
Fire Properties ◽  
Explosion Accidents

Abstract Floating coal dusts are always produced during coal mining process in the underground mines. In a coal mine and other coal processing or utilizing industries, there are always some potential safety problems, such as coal dust explosion accidents.[1,2] During lignite mining and processing, flammable coal dust is produced. Fire properties of coal dust depend on the particle size. The article deals with the measurement of explosion characteristics of lignite in dependence of particle size at three various concentrations. The measurements were carried out according to EN 14034-1+A1:2011 Determination of explosion characteristics of dust clouds. Part 1: Determination of the maximum explosion pressure pmax of dust clouds. Tests of the lignite dust clouds explosions showed that the maximum value of the pressure was reached at the concentrations of 500 g.m−3 and the particle size between 0 – 56 µm. At this concentration, the highest explosion pressure of 8.25 bar was reached.

An Empirical Investigation of Factors Affecting Stock Prices in Vietnam

2014 ◽  
pp. 74-89 ◽  
Author(s):  
Vinh Vo Xuan
Keyword(s):  
Exchange Rates ◽  
Crude Oil ◽  
Foreign Exchange ◽  
Stock Prices ◽  
Global Financial Crisis ◽  
Oil Prices ◽  
Foreign Exchange Rates ◽  
Factors Affecting ◽  
Crude Oil Prices ◽  
Before And After

This paper investigates factors affecting Vietnam’s stock prices including US stock prices, foreign exchange rates, gold prices and crude oil prices. Using the daily data from 2005 to 2012, the results indicate that Vietnam’s stock prices are influenced by crude oil prices. In addition, Vietnam’s stock prices are also affected significantly by US stock prices, and foreign exchange rates over the period before the 2008 Global Financial Crisis. There is evidence that Vietnam’s stock prices are highly correlated with US stock prices, foreign exchange rates and gold prices for the same period. Furthermore, Vietnam’s stock prices were cointegrated with US stock prices both before and after the crisis, and with foreign exchange rates, gold prices and crude oil prices only during and after the crisis.

scholarly journals A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110178
Author(s):  
Zhengang Liu ◽  
Weinan Diao ◽  
Zhenxia Liu ◽  
Fei Zhang
Keyword(s):  
Particle Size ◽  
Particle Deposition ◽  
Numerical Study ◽  
Stokes Number ◽  
Capture Efficiency ◽  
Particle Capture ◽  
Factors Affecting ◽  
Pressure Surface ◽  
Deposition Area ◽  
Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

scholarly journals Physicochemical factors affecting the wettability of copper mine blasting dust

2021 ◽  
Author(s):  
Longzhe Jin ◽  
Jianguo Liu ◽  
Jingzhong Guo ◽  
Jiaying Wang ◽  
Tianyang Wang
Keyword(s):  
Particle Size ◽  
Physicochemical Properties ◽  
Pore Structure ◽  
Total Pore Volume ◽  
Open Pit ◽  
X Rays ◽  
Factors Affecting ◽  
Copper Mine ◽  
Mineral Components ◽  
Hydrophobic Component

AbstractTo investigate the factors affecting the wettability of copper mine blasting dust, the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust (HLBD) and hydrophobic blasting dust (HBBD) using water flotation method. The physicochemical properties of HLBD and HBBD were measured and compared with each other. The properties included particle size distributions (PSDs), micromorphologies, pore structures, mineral components and surface organic carbon functional groups. The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability. Specifically, particle size of HBBD is smaller than that of HLBD, and their respiratory dust (less than 10 µm) accounts for 61.74 vol% and 53.00 vol%, respectively. The pore structure of HBBD is more developed, and the total pore volume of HBBD is 1.66 times larger than that of HLBD. The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction (XRD); however, the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD, this may be the reason for the poor wettability of HBBD. This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

Effect of particle size and delignification on the rate of digestion of hemicellulose and cellulose by cellulase in mature pangola grass stems

1983 ◽  
Vol 34 (3) ◽  
pp. 241 ◽  
Author(s):  
CW Ford
Keyword(s):  
Particle Size ◽  
Cell Walls ◽  
Trichoderma Viride ◽  
Structural Features ◽  
Cell Wall Polysaccharides ◽  
Particle Size Reduction ◽  
Digitaria Decumbens ◽  
Hemicellulose Degradation ◽  
Before And After ◽  
The Difference

Stem cell walls of pangola grass (Digitaria decumbens) were ground to two particle sizes (c. 1 and 0.1 mm diameter), and incubated with cellulase (ex. Trichoderma viride) for varying times before and after delignification. Total cell walls finely ground (0.1 mm) with a Spex Shatterbox mill were initially degraded more rapidly (to 24 h) than delignified 1 mm particles. Thereafter the delignified material was solubilized to a greater extent. Subsequent specific determinations of cell wall polysaccharides indicated that delignification increased the rate of hemicellulose degradation to a greater extent than did particle size reduction, whereas the opposite was found for cellulose. The difference between delignified and Spex-ground residues, in terms of the amount of polysaccharide digested, was much greater for cellulose than hemicellulose. It is concluded that structural features play a more important role in limiting cellulase degradation of cellulose than does association with lignin, the reverse being so for hemicellulose.

Factors Affecting Eyelid Crease Formation Before and After Silicone Frontalis Suspension for Adult-Onset Myogenic Ptosis

2015 ◽  
Vol 31 (3) ◽  
pp. 227-232 ◽  
Author(s):  
Richard C. Allen ◽  
Esther S. Hong ◽  
M. Bridget Zimmerman ◽  
Leslie A. Morrison ◽  
Jeffrey A. Nerad ◽  
...  
Keyword(s):  
Adult Onset ◽  
Factors Affecting ◽  
Before And After ◽  
Frontalis Suspension

scholarly journals Experimental Investigation of Wave Velocity-Permeability Model for Granite Subjected to Different Temperature Processing

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Guanghui Jiang ◽  
Jianping Zuo ◽  
Teng Ma ◽  
Xu Wei
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Wave Velocity ◽  
Pore Fluid ◽  
Rock Matrix ◽  
Permeability Model ◽  
Wave Velocities ◽  
Before And After ◽  
Different Temperatures ◽  
Increasing Temperature

Understanding the change of permeability of rocks before and after heating is of great significance for exploitation of hydrocarbon resources and disposal of nuclear waste. The rock permeability under high temperature cannot be measured with most of the existing methods. In this paper, quality, wave velocity, and permeability of granite specimen from Maluanshan tunnel are measured after high temperature processing. Quality and wave velocity of granite decrease and permeability of granite increases with increasing temperature. Using porosity as the medium, a new wave velocity-permeability model is established with modified wave velocity-porosity formula and Kozeny-Carman formula. Under some given wave velocities and corresponding permeabilities through experiment, the permeabilities at different temperatures and wave velocities can be obtained. By comparing the experimental and the theoretical results, the proposed formulas are verified. In addition, a sensitivity analysis is performed to examine the effect of particle size, wave velocities in rock matrix, and pore fluid on permeability: permeability increases with increasing particle size, wave velocities in rock matrix, and pore fluid; the higher the rock wave velocity, the lower the effect of wave velocities in rock matrix and pore fluid on permeability.

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