Effects of dust controls on respirable coal mine dust composition and particle sizes:case studies on auxiliary scrubbers and canopy air curtain

Control of dust in underground coal mines is critical for mitigating both safety and health hazards.For decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effectiveness of various dust control technologies in coal mines.Recent studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains(CACs)to reduce respirable dust in key operator positions.While detailed dust characterization was not a focus of such studies,this is a growing area of interest.Using preserved filter samples from three previous NIOSH studies,the current work aims to explore the effect of two different scrubbers(one wet and one dry)and a roof bolter CAC on respirable dust composition and particle size distribution.For this,the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive X-ray.Results indicate that dust composition was not appreciably affected by either scrubber or the CAC.However,the wet scrubber and CAC appeared to decrease the overall particle size distribution.Such an effect of the dry scrubber was not consistently observed,but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return air.Aside from the insights gained with respect to the three specific dust control case studies revisited here,this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.

Toxicity and horizontal transfer of bifenthrin and dimefluthrin against the red imported fire ant, Solenopsis invicta Buren(Hymenoptera: Formicidae), and the efficacy of their dust applications in the field

The red imported fire ant,Solenopsis invicta Buren,poses a significant threat to biodiversity,agriculture,and public health in its introduced ranges.While chemicals such as toxic baits and dust are the main methods for S.invicta control,toxic baits are slow,requiring approximately one or two weeks,but dust can eliminate the colony of fire ants rapidly in just three to five days.To explore more active ingredients for fire ant control using dusts,the toxicity of bifenthrin and dimefluthrin,the horizontal transfer of bifenthrin and dimefluthrin dust and their efficacy in the field were tested.The results showed that the LD50(lethal dose) values of bifenthrin and dimefluthrin were 3.40 and 1.57 ng/ant,respectively.The KT50(median knockdown time) and KT95(95%knockdown time) values of a 20μg mL^(–1)bifenthrin dose were 7.179and 16.611 min,respectively.The KT50and KT95of a 5μg mL^(–1)dimefluthrin dose were 1.538 and 2.825 min,respectively.The horizontal transfers of bifenthrin and dimefluthrin among workers were effective.The mortality of recipients (secondary mortality) and secondary recipients (tertiary mortality) were both over 80%at 48 h after 0.25,0.50 and 1.00%bifenthrin dust treatments.The secondary mortality of recipients was over 99%at 48 h after 0.25,0.50 and 1.00% dimefluthrin dust treatments,but the tertiary mortality was below 20%.The field trial results showed that both bifenthrin and dimefluthrin exhibited excellent fire ant control effects,and the comprehensive control effects of 1.00%bifenthrin and dimefluthrin dusts at 14 d post-treatment were 95.87 and 85.70%,respectively.

Filtration performance and modeling of granular bed for dust removal from coal pyrolytic vapors

Dust removal from pyrolytic vapors at high temperatures is an obstacle to the industrialization of the coal pyrolysis process.In this work,a granular bed with expanded perlites as filtration media was designed and integrated into a 10 t·d^(–1)coal pyrolysis facility.The testing results showed that around 97.56%dust collection efficiency was achieved.As a result,dust content in tar was significantly lowered.The pressure drop of the granular bed maintained in the range of 356 Pa to 489 Pa.The dust size in the effluent after filtration exhibited a bimodal distribution,which was attributed to the heterogeneity of the dust components.The effects of filtration bed on pyrolytic product yields were also discussed.A modified filtration model based on the macroscopic phenomenological theory was proposed to describe the performance of the granular bed.The computation results were well agreed with the experimental data.

Experimental and numerical simulation study on forced ventilation and dust removal of coal mine heading surface

In order to study the problems of unreasonable airflow distribution and serious dust pollution in a heading surface,an experimental platform for forced ventilation and dust removal was built based on the similar principles.Through the similar experiment and numerical simulation,the distribution of airflow field in the roadway and the spatial and temporal evolution of dust pollution under the conditions of forced ventilation were determined.The airflow field in the roadway can be divided into three zones:jet zone,vortex zone and reflux zone.The dust concentration gradually decreases from the head to the rear of the roadway.Under the forced ventilation conditions,there is a unilateral accumulation of dust,with higher dust concentrations away from the ducts.The position of the equipment has an interception effect on the dust.The maximum error between the test value and the simulation result is 12.9%,which verifies the accuracy of the experimental results.The research results can provide theoretical guidance for the application of dust removal technology in coal mine.

Ion acoustic solitary waves in an adiabatic dusty plasma:Roles of superthermal electrons,ion loss and ionization

We investigate propagation of dust ion acoustic solitary wave(DIASW)in a multicomponent dusty plasma with adiabatic ions,superthermal electrons,and stationary dust.The reductive perturbation method is employed to derive the damped Korteweg-de Vries(DKdV)equation which describes DIASW.The result reveals that the adiabaticity of ions significantly modifies the basic features of the DIASW.The ionization effect makes the solitary wave grow,while collisions reduce the growth rate and even lead to the damping.With the increases in ionization cross sectionΔσ/σ_(0),ion-to-electron density ratioδ_(ie)and superthermal electrons parameterκ,the effect of ionization on DIASW enhances.

Separation of halogens and recovery of heavy metals from secondary copper smelting dust

The separation of halogens and recovery of heavy metals from secondary copper smelting(SCS)dust using a sulfating roasting−water leaching process were investigated.The thermodynamic analysis results confirm the feasibility of the phase transformation to metal sulfates and to gaseous HF and HCl.Under the sulfating roasting conditions of the roasting temperature of 250℃ and the sulfuric acid excess coefficient of 1.8,over 74 wt.%of F and 98 wt.%of Cl were volatilized into flue gas.Approximately 98.6 wt.%of Zn and 96.5 wt.%of Cu in the roasting product were dissolved into the leaching solution after the water leaching process,while the leaching efficiencies of Pb and Sn were only 0.12%and 0.22%,respectively.The mechanism studies indicate the pivotal effect of roasting temperature on the sulphation reactions from various metal species to metal sulfates and the salting out reactions from various metal halides to gaseous hydrogen halides.

Radiation Spectral Analysis of 3D Dust Molecular Clusters(PAHs)and Peptoids under Ionization and Electric Field in ISM

Polycyclic aromatic hydrocarbons(PAHs),PANHs,and peptoids dust spectral calculations from the interstellar medium(ISM)are important for dust observations and theory.Our goal is to calculate the radiation spectrum of spherical PAHs dust clusters in a vacuum containing ionized and applied in the presence of an electric field.We propose a new simple computational model to calculate the size of three-dimensional spherical dust clusters formed by different initial dust structures.By the Vienna Ab-initio Simulation Package code,the density functional theory with the generalized approximation was used to calculate the electron density gradient and obtain the radiation spectrum of dust.When the radius of spherical dust clusters is~[0.009-0.042]μm,the dust radiation spectrum agrees well with the Z=0.02 mMMP stellar spectra,and the PAHs radiation spectrum of NGC 4676 at wavelengths of(0-5]μm and(5-10]μm,respectively.In the ionized state,the N-PAH,C_(10)H_(9)N,2(C_(4)H_(4))^(1+),and peptoids 4(CHON),(C_(8)H_(10)N_(2)O_(5))^(1+)dust clusters at 3.3μm,while the 2(C_(22)H_(21)N_(3)O_(2))^(1+),4(CHON)dust clusters at 5.2μm have obvious peaks.There is a characteristic of part of PAHs and peptoids clusters radiation at the nearinfrared wavelength of 2μm.However,especially after applying an electric field to the dust,the emission spectrum of the dust increases significantly in the radiation wavelength range[3-10]μm.Consequently,the dust clusters of PAHs,PANHs,and peptoids of the radius size~[0.009-0.042]μm are likely to exist in the ISM.

Micro-Locational Fine Dust Prediction Utilizing Machine Learning and Deep Learning Models

Given the increasing number of countries reporting degraded air quality,effective air quality monitoring has become a critical issue in today’s world.However,the current air quality observatory systems are often prohibitively expensive,resulting in a lack of observatories in many regions within a country.Consequently,a significant problem arises where not every region receives the same level of air quality information.This disparity occurs because some locations have to rely on information from observatories located far away from their regions,even if they may be the closest available options.To address this challenge,a novel approach that leverages machine learning and deep learning techniques to forecast fine dust concentrations was proposed.Specifically,continuous location features in the form of latitude and longitude values were incorporated into our models.By utilizing a comprehensive dataset comprising weather conditions,air quality measurements,and location properties,various machine learning models,including Random Forest Regression,XGBoost Regression,AdaBoost Regression,and a deep learning model known as Long Short-Term Memory(LSTM)were trained.Our experimental results demonstrated that the LSTM model outperforms the other models,achieving the best score with a root mean squared error of 23.48 in predicting fine dust(PM10)concentrations on an hourly basis.Furthermore,the fact that incorporating location properties,such as longitude and latitude values,enhances the overall quality of the regression models was discovered.Additionally,the implications and contributions of our research were discussed.By implementing our approach,the cost associated with relying solely on existing observatories can be substantially reduced.This reduction in costs can pave the way for economically efficient fine dust observation systems,ensuring more widespread and accurate air quality monitoring across different regions.

Climatic and Environmental Impacts of Dust over the Tibetan Plateau: An Overview

The Tibetan Plateau (TP), located at a height of nearly 4000 m above sea level, has a unique setting that effects the environment of the whole of northern hemisphere. It acts as the “water reservoir” of Asia as several important rivers originate from this region. Therefore, even slight alternations in the TP’s hydrological cycle may have profound ecological and social impacts. However, it is experiencing a significant increase in accumulation of dust from local and global sources. The impact of dust on the region’s climate has become an active area of research. Further, the study of sources of dust arriving at the TP is also critical. Accumulation of dust is impacting temperature, snow cover, glaciers, water resources, biodiversity and soil desertification. This manuscript tries to provide a comprehensive summary of the impact of dust on weather, climate, and environmental components of the TP. The impact of dust on clouds, radiative energy, precipitation, atmospheric circulation, snow and ice cover, soil, air quality, and river water quality of the TP are discussed. It further discusses the steps immediately needed to mitigate the devastating impact of dust on the fragile ecosystem of the TP.

Toxicity Evaluation of Different Exposure Scenarios of Road Dust Using Daphnia magna and Artemia salina as Aquatic Organisms, and Prosopis cineraria and Vachellia tortilis as Native Plant Species

Particulate matter (PM10) deposited as road dust is considered an important source of contamination from atmosphere. However, there are limited studies on the toxicity of road dust as such on different organisms. This study evaluates the toxicity of road dust using different extraction scenarios on Daphnia magna and Artemia salina as aquatic organisms and also on Prosopis cineraria and Vachellia tortilis as local plant species. Chemical analysis of different extracts shows considerable amount of trace metals, however the trace metals in the dust extract associated with suspended sediment were not absorbed by the receptors. On the other hand, the concentration of trace metals in the artificial mixture was found bioavailable and absorbed causing a high percentage of mortality. In the plant assay, significant difference was obtained in the germination percentage between the control and three different extraction exposures in both plant species. The mean root length of P. cineraria and V. tortilis were higher in 20% and 50% extracts than the control probably due to the availability of nutrients from the dust extract. Interestingly however, the seedling vigor index was the opposite with higher index in the control and lower in dust extracts that contain heavy metals.

Assessment of Heavy Metals Contamination of Topsoil and Street Dust around Cement Factory in Southern Jordan

Evaluation of assessment of the metal processes governing the metals distribution in soil and dust samples is very significant and protects the health of human and ecological system. Recently, special attention has given to the assessment of metals pollution impact on soil and dust within industrial areas. This study aims to assess the metal contamination levels in the topsoil and street dust around the cement factory in Qadissiya area, southern Jordan. The levels of seven metals (namely Fe, Zn, Cu, Pb, Cr, Cd, and Mn) were analyzed using Flame Atomic Absorption Spec-trophotometer (FAAS) to monitor, evaluate, and to compare topsoil and road dust pollution values of metals of the different types of urban area. The physicochemical parameters which believed to affect the mobility of metals in the soil of the study area were determined such as pH, EC, TOM, CaCO3 and CEC. The levels of metal in soil samples are greater on the surface but decrease in the lower part as a result of the basic nature of soil. The mean values of the metals in soil can be arranged in the following order: Zn > Pb > Mn > Fe > Cu > Cr > Cd. The relatively high concentration of metals in the soil sample was attributed to anthropogenic activities such as traffic emissions, cement factory and agricultural activities. Correlation coefficient analysis and the spatial distribution of indices and the results of statistical analysis indicate three groups of metals: Fe and Mn result by natural origin, Zn, Pb, Cu and Zn result by anthropogenic origin (mainly motor vehicle traffic and abrasion of tires) while Cd is mixed origin. The higher content level values of metals of anthropogenic source in soil samples indicate that it is a source of contamination of air in the studied area. .

Control of the Dust Vertical Distribution over Western Africa by Convection and Scavenging

Saharan dust represents more than 50%of the total desert dust emitted around the globe and its radiative effect significantly affects the atmospheric circulation at a continental scale.Previous studies on dust vertical distribution and the Saharan Air Layer(SAL)showed some shortcomings that could be attributed to imperfect representation of the effects of deep convection and scavenging.The authors investigate here the role of deep convective transport and scavenging on the vertical distribution of mineral dust over Western Africa.Using multi-year(2006-2010)simulations performed with the variable-resolution(zoomed)version of the LMDZ climate model.Simulations are compared with aerosol amounts recorded by the Aerosol Robotic Network(AERONET)and with vertical profiles of the Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP)measurements.LMDZ allows a thorough examination of the respective roles of deep convective transport,convective and stratiform scavenging,boundary layer transport,and advection processes on the vertical mineral dust distribution over Western Africa.The comparison of simulated dust Aerosol Optical Depth(AOD)and distribution with measurements suggest that scavenging in deep convection and subsequent re-evaporation of dusty rainfall in the lower troposphere are critical processes for explaining the vertical distribution of desert dust.These processes play a key role in maintaining a well-defined dust layer with a sharp transition at the top of the SAL and in establishing the seasonal cycle of dust distribution.This vertical distribution is further reshaped offshore in the Inter-Tropical Convergence Zone(ITCZ)over the Atlantic Ocean by marine boundary layer turbulent and convective transport and wet deposition at the surface.

Research Progress and Prospect of Road Dust Suppressants

Road dust has great adverse effects on traffic quality,traffic safety,atmospheric environment quality,and human health.Therefore,with the continuous development of modern science and technology,the research of road dust suppressants is also progressing.To promote the rational application and development of road dust suppressants,the research progress and prospects of them are analyzed in this paper.It includes a basic overview of road dust suppressants,the main types,the usage and precautions,and the main development direction.It is hoped that this analysis can provide some reference for further research and development of road dust suppressants.

Overview of Factors Affecting Dust Deposition on Photovoltaic Cells and Cleaning Methods

Dust deposition on the surface of photovoltaic (PV) cells poses a significant challenge to their efficiency, especially in arid regions characterized by desert and semi-desert conditions. Despite the pronounced impact of dust accumulation, these regions offer optimal solar radiation and minimal cloud cover, making them ideal candidates for widespread PV cell deployment. Various surface cleaning methods exist, each employing distinct approaches. Choosing an appropriate cleaning method requires a comprehensive understanding of the mechanisms involved in both dust deposition on module surfaces and dust adhesion to PV cell surfaces. The mechanisms governing dust deposition and adhesion are complex and multifaceted, influenced by factors such as the nature and properties of the dust particles, environmental climatic conditions, characteristics of protective coatings, and the specific location of the PV installation. These factors exhibit regional variations, necessitating the implementation of diverse cleaning approaches tailored to the unique conditions of each location. The first part of this article explores the factors influencing dust deposition on PV cell surfaces, delving into the intricate interplay of environmental variables and particle characteristics. Subsequently, the second part addresses various cleaning methods, offering an analysis of their respective advantages and disadvantages. By comprehensively examining the factors influencing dust accumulation and evaluating the effectiveness of different cleaning strategies, this article aims to contribute valuable insights to the ongoing efforts to optimize the performance and longevity of photovoltaic systems in diverse geographical contexts.

Design and Numerical Simulation of Dust Removal System for Sutomotive Iongitudinal Beam Plasma Cutting

To improve the poor efficiency of the dust removal system in the plasma cutting station of automotive longitudinal beams,and reduce the cutting surface quality degradation due to dust,a bottom-side suction dust removal system is designed,and the dust removal effect is optimized through the setting of the following dampers and diversion plates.The result of numerical simulation indicates that the particle collection rate can reach 99.44%,and the field test also proves the effectiveness of the dust removal system,which is of guiding significance for the transformation of other similar dust removal systems.

Existing state of potassium chloride in agglomerated sintering dust and its water leaching kinetics

In order to examine the leaching rate of potassium chloride from the sintering dust by water,surface morphology and inner structure of the dust,especially the existing state of potassium chloride,were observed by scanning electron microscopy（SEM） and linear scanning technique via energy dispersive spectroscopy（EDS）.The characterization shows that the sintering dusts are mostly porous composites or agglomerates of the fine dust particles with size less than 10 μm,and the potassium chloride and sodium chloride particles are partly covered by other water insoluble matters in the dust which consist of elements iron,calcium and etc.Exposure of potassium chloride in the agglomerated dust matrix of this kind suggests that the leaching can be simply perceived as the dissolution of water soluble matters in the dust.On-line monitor of specific electrical conductivity of the leaching system verifies the prediction that leaching kinetics of potassium chloride from the sintering dust fits dissolution model well.Leaching equilibrium can be reached within 5 min with potassium leaching ratio more than 95%.

Water leaching kinetics and recovery of potassium salt from sintering dust

Surface morphology and inner structure of the dust were observed by ICP-AES, SEM-EDS and XRD to examine the strengthening measures of leaching potassium salt from the sintering dust by water. The results showed that the main component of the sintering dust was iron-oxygen compound, with KCl adsorbed on its surface. Leaching experiments showed that the KCl in the ESP dust could be separated and recovered by water leaching and fractional crystallization. The yield of K-Na vaporized crystalline salt was 18.56%, in which the mass fractions of KCl, NaCl, CaSO4 and K2SO4 were about 61.21%, 13.40%, 14.62%and 10.86%, respectively. The leaching kinetics of potassium salt from the sintering dust fits the external diffusion model well. The leaching speed and the leaching rate of the potassium salt can be increased by increasing the leaching temperature, strengthening the stirring speed and increasing the liquid-solid ratio.

Dielectric properties and temperature increase characteristics of zinc oxide dust from fuming furnace

Cavity perturbation method was used to determine the dielectric properties （ε′,ε″, and tanδ） of zinc oxide dust in different apparent densities. The process was conducted to study the microwave-absorption properties of zinc oxide dust and the feasibility of microwave roasting zinc oxide dust to remove fluorine and chlorine. The dielectric constant, dielectric loss, and loss tangent were proportional to the apparent density of zinc oxide dust. The effects of sample mass and microwave power on the temperature increase characteristics under the microwave field were also studied. The results show that the apparent heating rate of the zinc oxide dust increases with the increase in microwave roasting power and decreases with the increase in the sample mass. The temperature of the samples reaches approximately 800 ＆#176;C after microwave treatment for 8 min, which indicates that the zinc oxide dust has strong microwave-absorption ability.

In-Situ Measuring the Particle Mean Size and Dust Concentration by Near-Forward Small Angle Light Scattering

This paper presents a method of measuring the particle mean size and dust concentration by small angle near forward light scattering optics and the extinction theory. Its theory is based on Fraunhofer diffraction theory which is the approximation of Mie scattering within the forward Fraunhofer diffraction lobe, and Rosin Rammler function is introduced to describe the particle size distribution in two phase flow in advance. Compared with the values by the sample weight method, the measurement results have a reasonable agreement. The present work has demonstrated that this method will be probably used to monitor the parameters of two phase flow.

尺度适应性起沙机制在CMA-CUACE/Dust中的应用

沙尘暴是影响我国重要的灾害性天气之一,针对中国气象局亚洲沙尘暴数值预报系统CMA-CUACE/Dust(China Meteorological Administration Unified Atmospheric Environment for Dust)的沙尘质量浓度在中亚高估、蒙古北部低估、在我国消散过快以及极端沙尘暴预报峰值偏低等问题,应用与模式格距匹配的尺度适应性起沙机制并更新风蚀资料库对模式进行改进。对2021年3月13—17日东亚最强沙尘暴个例和2023年3—5月与业务运行环境一致的连续预报试验表明,改进后的模式(CMA-CUACE/Dust V1.5)有效改善了上述不足,极端沙尘暴过程传输至我国后的沙尘质量浓度峰值与观测接近。连续预报试验TS(threat score)评分显示:CMA-CUACE/Dust V1.5预报一致性和连续性较好,1~5 d不同时效预报TS评分明显高于改进前和韩国模式ADAM(the Asian Dust Aerosol Model),漏报率明显降低,对2023年5次沙尘过程的4次预报TS评分高于0.3,部分过程超过0.5。