Dust Concentration Values Research Articles

CFD MODELLING OF THE DUST AND AIR VELOCITY BEHAVIOUR AT AN UNDERGROUND COAL MINE ROADWAY

Dust pollution for ventilation systems is a big problem for mine workers in underground coal mines. The respirable dust concentration is important to the physical and spiritual health of miners. It is hazardous up to 2 mg/m3in the air in underground coal galleries. In the present work, the airflow velocity and dust concentration values were measured at Çay 1-Kartiye roadway in Kozlu, Zonguldak. The goal of this research is modelling to the dust concentration and airflow velocity values by the computational fluid dynamics (CFD) method. An airflow and dust fluid and solid model was done using the Eularian-Granular multiphase method with the k-epsilon two-equation model. The results showed that dust concentration values were too low and fixed. The error percentage of airflow velocity values changed between 5% and 17%. Thus, this roadway is safe for coal dust explorations.

A novel approach to forecast dust concentration in open pit mines by integrating meteorological parameters and production intensity.

Mine dust pollution poses a hindrance to achieving green and climate-smart mining. This paper uses weather forecast data and mine production intensity data as model inputs to develop a novel model for forecasting daily dust concentration values in open pit mines by employing and integrating multiple machine learning techniques. The results show that the forecast model exhibits high accuracy, with a Pearson correlation coefficient exceeding 0.87. The PM2.5 forecast model performs best, followed by the total suspended particle and PM10 models. The inclusion of production intensity significantly enhances model performance. Total column water vapor exerts the most significant impact on the model's predictive performance, while the impacts of rock production and coal production are also notable. The proposed daily forecast model leverages production intensity data to predict future dust concentrations accurately. This tool offers valuable insights for optimizing mine design parameters, enabling informed decisions based on real-time forecasts. It effectively prevents severe pollution in the mining area while maximizing the use of natural meteorological conditions for effective dust removal and diffusion.

Analysis of the dust-methane two-phase coupling blowdown effect at different air duct positions in an excavation anchor synchronous tunnel.

Bolter miners are being increasingly used. Unfortunately, this mining technology causes a considerable amount of air pollution (especially by methane and dust) during excavation. In this study, the multiphase coupling field of airflow-dust-methane for different distances between the pressure air outlet and the working face (Lp) was simulated by using the FLUENT software. The migration law of pollutants in the multiphase coupling field was analyzed, and the distance parameters between the pressure air outlet and the working face were optimized. Finally, the simulation results were verified based on the field measurement results. We found that the blowdown effect was more obvious when 14m ≤ Lp < 16m compared with other conditions. The peak value of dust concentration within this distance range was the smallest (44.4% lower than the highest peak value, which was verified when Lp = 18m), while the methane concentration was < 0.6%. A high-concentration area (where methane concentration > 0.75%), identified near the walking part of the bolter miner, was 13m shorter than the largest (when Lp = 18m). Therefore, we determined that the optimal blowdown distance would be 14m ≤ Lp < 16m. Within this range, the dust removal and methane dilution effects are optimal, effectively improving the tunnel air quality and providing a safe and clean environment for mine workers.

Estimation of dust concentration by a novel machine vision system

The dust phenomenon is one of the main environmental problems that it reversely affects human health and economical and social activities. In the present research, a novel algorithm has been developed based on image processing to estimate dust concentration. An experimental setup was implemented to create airborne dust with different concentration values from 0 to 2750 µg.m−3. The images of the different dust concentration values were acquired and analyzed by image processing technique. Different color and texture features were extracted from various color spaces. The extracted features were used to develop single and multivariable models by regression method. Totally 285 single variable models were obtained and compared to select efficient features among them. The best single variable model had a predictive accuracy of 91%. The features were used for multivariable modeling and the best model was selected with a predictive accuracy of 100% and a mean squared error of 1.44 × 10−23. The results showed the high ability of the developed machine vision system for estimating dust concentration with high speed and accuracy.

Distribution characteristics of an airflow–dust mixture and quantitative analysis of the dust absorption effect during tunnel sub-regional coal cutting

Optimizing the tunnel ventilation scheme is one of the main ways to achieve safe production in coal mines. Based on the actual production situation, computational fluid dynamics technology was used to study the distribution characteristics of an airflow–dust mixture for different air-absorption volumes (Qe) of the ventilation system during sub-regional coal cutting. According to the dust concentration values registered at different locations, the entropy weight method was applied to quantitatively analyze the dust absorption effect of the fan. The research results showed that: the dust distribution was jointly affected by the cutting unit and the completed cutting zone; moreover, the dust control effect was better in the middle cutting zones than in the others. Under the ventilation system, the overall distribution of dust in the tunnel could be roughly divided into three sections: the dust removal section (I), the dust blocking section (II), and the gentle section (III). The optimal Qe (575 m3/min) was determined based on the weight of the different zones. Finally, the entropy weight method was applied for determining the ideal mine ventilation system scheme and, hence, improve safety production in coal mines during sub-regional cutting dust production.

Experimental Research of Fibrous Materials for Two-Stage Filtration of the Intake Air of Internal Combustion Engines.

Pollutant properties in intake air to internal combustion engines were analyzed. Mineral dust particles’ influence on accelerated engine components’ wear was discussed. Dust concentration values in the air under various operating conditions in trucks and special vehicles were presented. The idea and necessity for using two-stage filters, operating in a “multi-cyclone–porous partition” system for vehicles operated in dusty air conditions, are presented. Information from the literature information has been presented, showing that impurities in small grain sizes reduce fiber bed absorbency. It has been shown that such a phenomenon occurs during filter material operation, located directly behind the inertial filter (multi-cyclone), which off-road vehicles are equipped with. It results in a greater pressure drop intensity increase and a shorter proper filter operation period. It has been shown that filter material selection for the motor vehicle air filter requires knowledge of the mass of stopped dust per filtration unit area (dust absorption coefficient km) determined for a given permissible resistance value Δpfdop. It has been shown that there is no information on absorption coefficient values for filter materials operating in a two-stage “multi-cyclone–porous partition” separation system. Original methodology and conditions for determining dust absorption coefficient (km) of a separation partition, operating under the conditions of two-stage filtration, were presented. The following characteristics were tested: separation efficiency, filtration performance, and pressure drop characteristics of three different filtration partitions. These were A (cellulose), B (cellulose and polyester), and C (cellulose, polyester, and nanofibers layer), working individually and in a two-stage system—behind the cyclone. Granulometric dust composition dosed into the cyclone and cyclone downstream was determined. During tests, conditions corresponding to air filter’s actual operating conditions, including separation speed and dust concentration in the air, were maintained. For the pressure drop values, the dust absorption coefficient (km) values of three different filtration partitions (A, B, and C), working individually and in a two-stage system—behind the cyclone—were determined experimentally.

Three-dimensional spatial and temporal distributions of dust in roadway tunneling

To study the three-dimensional spatial and temporal distributions of dust in tunneling roadways, and to solve the problems of inadequate time and limited number of monitoring points, this paper designs a device for the real-time monitoring and storage of data on the concentrations of dust at multiple measuring points in the same section of a tunnel. The proposed device can measure the total concentration of dust and that of respirable dust in real time at different instances and locations, and using different working procedures. These measurements are used to study the temporal and spatial migration of dust. The results show that there was a sharp fluctuation zone 0–25 m from the heading face, about 25–40 m was high speed subsidence, beyond 40 m was gentle subsidence, The change of respiratory dust is much smoother. At different distances from the heading face, the total dust concentration exhibited a process of “violent oscillation–rapid descent–stable descent,” while the respirable dust exhibited a process of “fluctuating ascent–gradual subsidence.” Changes in the concentrations of total dust and respirable dust dust were consistent at different positions in the same section of the tunnel. The concentration of dust near the wall was low, and those along the sidewalk and air duct of the roadway were slightly higher than in the middle. The concentration of dust farther down the air duct decreased more slowly than that in the remaining lines of measurement. Small amounts of dust featuring large particles settled quickly. High concentrations of dust were observed to be intermittent, and the background value of dust concentration within 100 m of heading face was between 0.5 and 3 mg/m3.

Numerical Modeling of Dust Propagation in the Atmosphere of a City with Complex Terrain. The Case of Background Eastern Light Air

Micro-scale processes of dust distribution in the city of Tbilisi with very complex topography are modeled using a 3D regional model of atmospheric processes and numerical integration of the transport-diffusion equation of the impurity. The Terrain-following coordinate system is used to take into account the influence of a very complex relief on the process of atmospheric pollution. Modeling is carried out using horizontal grid steps of 300 m and 400 m along latitude and longitude, respectively. Cases of the stationary background eastern light air are considered. In the model, motor transport is considered as a nonstationary source of pollution from which dust is emitted into the atmosphere. Modeling of dust micro-scale diffusion process showed that the city air pollution depends on the spatial distribution of the main sources of city pollution, i.e. on vehicle traffic intensity, as well as on the spatial distribution of highways, and micro-orography of city and relief of the surrounding territories. It is shown that the dust pollution level in the surface layer of the atmosphere is minimal at 6 a.m. Ground-level concentration rapidly grows with the increase of vehicle traffic intensity and at 12 a.m. reaches maximum allowable concentration (MAC = 0.5 mg/m3) in the vicinity of central city mains. From 12 a.m. to 9 p.m. maximum dust concentration values are within the limits of 0.9 - 1.2 MAC. In the mentioned time interval formation of the high pollution zones, the slow growth of their areas and the value of ground-level concentrations take place. These zones are located in both central and peripheral parts of the city. Their disposition and area sizes depend on the spatial distribution of local wind-generated under the action of complex terrain, as well as on the processes of turbulent and advective dust transfer. From 9 p.m. to 24 p.m. reduction of dust pollution and ground-level concentration takes place. After midnight the city dust pollution process continues quasi-periodically.

Study on the applicability of key parameters from dust emission scheme in WRF/Chem over northwestern China

In order to more accurate quantitative simulation and forecast of sandstorm in northwest China, in this paper, the dust process occurred in northwest China was simulated by using the WRF/Chem model coupling of Shao2004 dust emission parameterization scheme. The influence of key parameter C in Shao2004 scheme is analyzed set at different values on simulated spatial and temporal dust concentration, estimated vertical dust flux and estimated PM10 and PM2.5 concentration of six stations in northwest China. And by comparing the concentration of PM concentration observed at the sites, the results were listed as: Parameter C has an significant influence on the simulation dust scope and maximum center value of dust concentration and vertical dust flux; Different C values can well simulate the variation trend of PM10 and PM2.5 concentration in dust weather, but only when the C value set as 1, this model can more accurately simulate the change of PM10 and PM2.5 concentration in the dust process in northwest China.

Study of dust diffusion at transfer point of belt conveyor based on FLUENT

The special working modes make transfer point of belt conveyor become one of the main dust sources in coal production. In this paper, the computational fluid dynamics software FLUENT was used to simulate the model of gas-solid two phases flow at transfer point. The distribution of velocity, dust particle and concentration were analysed. The results showed: the maximum value of dust concentration appeared along the tangential direction of the falling coal at the transfer point of the belt conveyor and raised the maximum height, the distribution of dust at transfer point was influenced by different airflows including belt induced flow and falling coal induced flow, and the latter was main factor, this study provided a theoretical basis for the dust treatment at transfer point of belt conveyor.

Shock focusing upon interaction of a shock with a cylindrical dust cloud

Propagation of a strong plane shock wave through air containing a cylindrical cloud of low-concentration quartz dust is numerically modeled using Euler’s equations. A one-velocity single-temperature model of dust-air mixture is used. Refraction of incident shock and formation and focusing of transversal shocks are described. Two qualitatively different interaction regimes–external and internal–are found to take place for different dust concentration values. The dependence of peak shock focusing point position and relative shock focusing intensity on volume concentration of dust in the range of from 0.01 to 0.15% is determined. With an increase of dust concentration, the peak focusing point draws near the cloud edge and moves inside the cloud, while focusing intensity significantly rises.

Climatic fluctuations inferred for the Middle and Late Pleniglacial (MIS 2) based on high-resolution (∼ca. 20 y) preliminary environmental magnetic investigation of the loess section of the Madaras brickyard (Hungary)

The Madaras brickyard section found at the northernmost fringe of the Backa loess plateau is one of the thickest and best-developed last glacial loess sequences of Central Europe. In the present work high-resolution magnetic susceptibility measurements (at 2 cm) were implemented on samples from the 10 m-section corresponding to a period between 29 and 11 KY cal b2K. One aim was to compare the findings with the ice core records of northern Greenland in order to establish a high-resolution paleoclimatic record for the last climatic cycle and with findings documented in other biotic and abiotic proxies so far. Our results revealed a strong variability of loess/paleosol formation during MIS 2. Millennial time-scale climatic events that characterize the North Atlantic during the last climatic cycle have been identified. From 29 ka up to the start of the LGM, the recorded MS values show a weak, negative correlation with the temperature proxy, and a weak positive correlation with the dust concentration of Greenland. A strong correlation was observed with the local paleotemperatures. Local climatic factors must have had a more prominent effect here on loess/paleosol development than the climate shifts over Greenland. During the LGM the same pattern is seen with a stronger correlation with the dust concentrations and a weaker correlation with the local temperature. Local climatic factors, plus dust accumulation, must have had a prominent influence on loess/paleosol development here. From the terminal part of the LGM a strong positive correlation of the MS values with the temperature proxy for Greenland accompanied by a strong negative correlation with the dust concentration values is observed. Correlation with local paleotemperatures is positive and moderate, strong. Here climate shifts over Greenland, as well as local endowments equally had an important role on the development of the MS signal.

Dust-induced shading on photovoltaic modules

The effect of dust on photovoltaic modules is investigated with respect to concentration and spectral transmittance. Samples were collected in the form of raw dust as well as accumulated dust on exposed sheets of glass at different tilt angles. Spectral transmittance of the samples was determined. Transmittance variation between top, middle and bottom was identified for samples collected at different inclinations, where the worst case was seen at a tilt angle of 30o with a non-uniformity of 4.4% in comparison with 0.2% for the 90° tilt. The measured data showed a decrease in transmittance at wavelengths <570 nm. Integrating this with measured spectral responses of different technologies demonstrates that wide band-gap thin-film technologies are affected more than, for example crystalline silicon technologies. The worst case is amorphous silicon, where a 33% reduction in photocurrent is predicted for a dust concentration of 4.25 mg/cm2. Similarly, crystalline silicon and CIGS technologies are predicted to be less affected, with 28.6% and 28.5% reductions in photocurrent, respectively. The same procedure was repeated with varying Air Mass (AM), tilt angle and dust concentration values to produce a soiling ratio table for different technologies under different AM, tilt angle and dust concentration values. Copyright © 2012 John Wiley & Sons, Ltd.

석영 라만 채널을 이용한 황사 후방 산란 계수 산출

We present a retrieval method to obtain dust backscatter coefficient from the mixed Asian dust and pollutant layer. In the present study, vertically resolved quartz (silicon dioxide, silica) concentration was calculated using Raman scattering signals from quartz at 546 nm. Dust concentration was obtained based on typical mass percentage of quartz in Asian dust. The highest value of dust concentration at 3.7 km in March 21, 2010 was 22.3 and 10.9 according to the quartz percentage in Asian dust as 65 and 30% based on literature survey, respectively. OPAC (Optical Properties of Aerosol and Clouds) simulations were conducted to calculate dust backscatter coefficient. The retrieved dust concentration was used as an input parameter for the OPAC calculations. Utilization of quartz Raman channel in Lidar measurements is considered useful for distinguishing optical properties of dust and nondust aerosol in the mixing state of Asian dust.

Air Quality Modeling for of a Strong Dust Event in East Asia in March 2010

In 19 and 20 March 2010, the annual strongest dust event occurred over East Asia, for the reports from National Meteorological Center of CMA (China Meteorological Administration) showed that 16 provinces (cities) of China were affected by the dust storm, and the air pollution index (API) given by Ministry of Environment Protection of China exceeded 300 in 13 Chinese cities. An air quality modeling system RAMS-CMAQ was employed to simulate the spatial and temporal features of this dust event, and analyze its impacts on air quality and regional radiative effect in East Asia. The modeled mass concentrations and aerosol optical depth (AOD) of dust and other aerosol species are generally in good agreement with surface observations and satellite measurements. Numerical analysis shows that the dust storm generated over Mongolia and west of Inner Mongolia, and swept central, eastern and southern China, also including the East China Sea. The highest value of dust concentration exceeded 3000 μg/m3 in the source area and waved from 200 to 1000 μg/m3 in the downstream areas. The high AOD values mainly contributed by dust ranged from 0.5 to 1.5, which means the regional visibility and radiation would be significantly impacted by the dust particles. The direct radiative forcing of dust was also obviously strong with values from –5 to –30 W/m2 appeared over the regions where dust storm swept. This value is almost equal to the radiative effect of total aerosol components over these areas.

Ambiência aérea em maternidade e creche de suínos

A suinocultura brasileira é uma atividade importante para o agronegócio do País. Embora o uso de tecnologia nos vários segmentos dessa atividade envolva a substituição do trabalho humano pela automatização de tarefas, o uso da mão de obra humana ainda é significativo. O trabalhador no setor suinícola está exposto a uma série de fatores de risco na execução de suas atividades, dentre os quais a exposição a gases nocivos. O presente trabalho teve por objetivo avaliar a qualidade do ar em instalações de maternidade e creche suinícolas, em duas granjas, com diferentes características (G1 e G2). Para tanto, foram avaliadas concentração de gases (NH3, CO2 e CO) e poeira respirável durante o período de atividades dos trabalhadores. As concentrações dos gases avaliados estiveram dentro dos limites recomendados pela NR-15 (1978) e ACGIH (2001). O gás que apresentou maior concentração foi NH3 no galpão de creche, que atingiu a concentração de 10 ppm, não ultrapassando os limites recomendados. As concentrações de poeira respirável mantiveram-se dentro dos limites estabelecidos pelas normas ACGIH (2001), NR-15 (1978) e NIOSH (1994), não havendo diferença significativa entre os galpões avaliados.

Evaluation of Occupational Exposures to Respirable Dust in Underground Coal Mines

Dust can be produced by almost all mining operations in underground coal mines and seen all around the mine. Different occupational groups get exposed to different dust levels and in order to minimize the probability of developing coal workers' pneumoconiosis (CWP), it is necessary to investigate the workers exposed to dust. This study aimed to evaluate the dust concentration conditions in underground coal mines and also the occupational health risks associated with exposures to respirable dust. The data obtained from the dust measurement studies conducted in various underground coal mines between the years 1978-2006 was evaluated by using analysis of variance (ANOVA) and Tukey-Kramer procedure. In the statistical analyses, the comparison of dustiness between mines and their mining regions were made by using the average dust concentration values. In addition, the numbers of workers with doubtful pneumoconiosis diagnosis were evaluated according to the occupational job category by using the number of the workers with the job illness. It was concluded that the production regions have the higher dust concentration levels and the CWP is mostly diagnosed in the workers working in production regions.

Saharan dust levels in Greece and received inhalation doses

Abstract. The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×108 tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in the south European Region and especially in urban areas, where there is also significant contribution from anthropogenic sources. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM10 concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM10 concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by more than 20% to the annual number of exceedances – PM10 values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region) and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those received during exposure in heavily polluted urban or smoking areas.

Numerical study of a very intensive eastern Mediterranean dust storm, 13–16 March 1998

Presented herein is an analysis of an exceptionally intensive central and eastern Mediterranean dust intrusion of 15–16 March, 1998. The intrusion has been associated with development of an intense cyclone over Africa. The weather and dust development processes were simulated with the Eta weather and dust prediction model. Also presented is a comparison of the model results with the Total Ozone Mass Spectrometer Aerosol Index (TOMS AI) pictures as well as with those of the surface and weather observations. The roles of the main processes responsible for the dust plume development and associated dust intrusion to the eastern Mediterranean (EM) are studied. The observation data as well as the model‐simulated parameters are jointly analyzed. The analysis also includes the data from the back‐trajectory computations. With the aid of the model‐produced dust profiles we studied the significant variation in the altitudes of the dust layers within the cyclone sectors. In the warm sector of the cyclone located over the Mediterranean Sea the dust layer extended up to 8–10 km. Relatively low dust concentration values were found here. In the area of the cold front over Africa the dust was restricted to the lower troposphere and the planetary boundary layer. Here the model simulated high values of the dust concentrations. The sharp TOMS AI increase over Israel and the eastern Mediterranean up to 5.0 units, further away from the dust sources, is explained by the strong winds, by the increased cyclone convergence, and the formation of a two‐layer dust plume.

Individual Dust Loading of Workers in Longwall Faces

Abstract In Polish coal mining the gravimetric dust sampling system has been obligatory since 1980, after a 5-year transition period between conimetric and gravimetric systems. The dust concentrations are measured in fixed points, mainly in outlet air stream in longwalls and on machine operator positions in headings. The dust sampler used is a gravimetric instrument, Barbara 3A, with an air flow of 5 L/min. The sample is taken on the membrane filter. Long-term observations showed that in almost 90 percent of longwalls and 80 percent of headings the dust concentration values are higher than allowable. The number of new cases of pneumoconiosis is about 600 to 900 every year. It appears that a new approach to the respirable dust problem is necessary. The Polish coal industry tends toward the calculation of individual dust loading. The preliminary estimations of differences between individual and fixed-point sampling were made with the use of the CIP-10 personal dust sampler. The goal of the measurement campa...