Research on mine dustfall agents based on the mechanism of wetting and coagulation

Mine dust is classified as one of five natural coal mining disasters because it can harm the health of miners and poses a serious threat to the safety of the coal mine. Therefore, preparation of an effective dust suppression agent is highly desired. To improve the capture efficiency of fine dust, this study examines the dust suppression effects of various combinations of wetting agents, additives, and coagulation agents by using the optimum seeking method to reduce mine dust, particularly respirable particles. The optimal formula is shown to contain 10wt% fatty alcohol polyoxyethylene ether（JFC）, 4.96wt% cationic polyacrylamide, and 4wt% calcium chloride. The dust suppression effect can be achieved at 96.1% in 5 min by using the optimal formula.

A systematic review of occupational exposure to respirable coal mine dust(RCMD)in the U.S.mining industry

Cumulative inhalation of respirable coal mine dust(RCMD)can lead to severe lung diseases,including coal worker's pneu-moconiosis(CWP),silicosis,mixed dust pneumoconiosis,dust-related diffuse fibrosis(DDF),and progressive massive fibrosis(PMF).Statistics from the number of reported cases showed a significant decrease in the progression of respiratory diseases in the 1990s.However,an unexpected increase in the number of CWP cases was reported in the late 1990s.To date,there has been no comprehensive systematic review to assess all contributing factors to the resurgence of CWP cases.This study aims to investigate the effects of various mining parameters on the prevalence of CWP in coal mines.A systematic review using the preferred reporting items for systematic reviews and meta-analysis(PRISMA)method was conducted to investigate the health effects of RCMD exposure and identify the factors that may contribute to the recent resurgence of CWP cases.The systematic review yielded a total of 401 papers,which were added to the database.The total number of 148 and 208 papers were excluded from the database in the process of screening and eligibility,respectively.Then,18 papers were considered for data selection and full-text assessment.The review revealed that factors including geographic location,mine size,mining operation type,coal-seam thickness,coal rank,changes in mining practices,technology advancement,and engi-neering dust control practices are contributing to the recent resurgence of CWP among coal workers.However,the evidence for root causes is limited owing to the methodological constraints of the studies;therefore,further detailed studies are needed.

Assessment of Distribution and Composition of Quarry Mine Dust: Case of Pomona Stone Quarries, Harare

The study aimed at assessing the distribution and composition of dust produced at Pomona Stone Quarry mine in Harare, Zimbabwe. The source contribution to ambient PM2.5 and PM10 dust levels were quantified and their spatial distribution from the quarry to the receptor (community). The study also analysed the pH of soils around the mine, SiO2 and Al2O3 levels in quarry dust. Data was collected through direct observations, personal communications, experiments, soil and dust sampling and analyses. Dust sampling was done in January, April and August, to assess the effect of meteorological conditions on dust concentrations in two phases. Phase 1 was conducted during plant shut down (baseline measurements) while phase 2 was carried out during full plant operations (normal operating conditions), to assess the effect of quarry operations on the surrounding areas. Within the quarry production processes, crushing stage was the most dust emitting stage. Phase 1 dust results showed that both respirable (PM2.5) and inhalable (PM10) dust at all stages were below the legal limit, thus below 35 mg/m3 (respirable) and 180 mg/m3 (inhalable). Highest dust levels (209.9 mg/m3 inhalable and 69.01 mg/m3 respirable) were recorded in August, followed by April (206.9 mg/m3 inhalable and 67.52 mg/m3 respirable) then January (206.82 mg/m3 inhalable and 65.27 mg/m3 respirable). At all stages, highest dust concentrations for both parameters were recorded near the plant and decreased with increasing distance from the plant ( ranging from 209.9 mg/m3 - 19.41 mg/m3 inhalable and 69.01 mg/m3 - 14.23 mg/m3 respirable). This was attributed to the effect of particle size. August recorded the biggest area for both parameters falling within the non-permissible category, followed by April then January. The findings also revealed that the quarry dust contained higher levels of SiO2 (0.752 mg/cm3) which were 7 times higher than the recommended 0.1 mg/cm3 (NSSA). Low Al2O3 levels of 0.102 mg/cm3 were recorded and this was considered as environmentally safe. Soils were slightly acidic-alkaline and the t-test results at 95% confidence interval showed no significant difference between the results from site A and B (p = 0.526). It was concluded that quarry dust from Pomona had no significant effects on soil pH but possible health impacts on the receiving community. The study recommended that dust suppression systems such as water sprays, vegetation, air nets and enclosed production process must be implemented to curb dust emissions.

A comparative study of dust control practices in Chinese and Australian longwall coal mines

Mine dust is one of the main hazards in underground longwall mines worldwide.In order to solve the mine dust problem,a significant number of studies have been carried out regarding longwall mine dust control,both in China and Australia.This paper presents a comparative study of dust control practices in Chinese and Australian longwall mines,with particular references to statutory limits,dust monitoring methods and dust management practices,followed by a brief discussion on the research status of longwall mine dust control in both countries.The study shows that water infusion,face ventilation controls,water sprays,and deep and wet cutting in longwall shearer operations are commonly practiced in almost all underground longwall mines and that both Chinese and Australian longwall mine dust control practices have their own advantages and disadvantages.It is concluded that there is a need for further development and innovative design of more effective dust mitigation products or systems despite the development of various dust control technologies.Based on the examinations and discussions,the authors have made some recommendations for further research and development in dust control in longwall mines.It is hoped that this comparative study will provide beneficial guidance for scholars and engineers who are engaging in longwall mine dust control research and practice.

Micromorphology and physicochemical properties of hydrophobic blasting dust in iron mines

The micromorphology and physicochemical properties of hydrophobic blasting dust(HBD)from an iron mine were comprehensively analyzed by laser particle size analysis(LPSA),scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The results show that the HBD particles can be classified into three types based on their particle size(PS):larger particles(PS>10μm),medium particles(1μm≤PS≤10μm),and nanoparticles(PS<1μm).The cumulative volume of respirable dust(PS≤10μm)was 84.45%.In addition,three shapes of HBD were observed by SEM:prism,flake,and bulk.In particular,the small particles were mostly flaky,with a greater possibility of being inhaled.Furthermore,the body and surface chemical compounds of HBD were determined by XRD and XPS,respectively.Ammonium adipate(C6H16N2O4)was the only organic compound in the body of HBD,but its mass fraction was only 13.4%.However,the content of organic C on the surface of HBD was 85.35%.This study demonstrated that the small-particle size and large amount of organic matter on the surface of HBD are the main reasons for its hydrophobicity,which can provide important guidance for controlling respirable dust in iron mines.

Using self-determination theory to identify organizational interventions to support coal mineworkers’ dust-reducing practices

Advancing the application of safety and health(S&H)technologies is likely to remain a value in the mining industry.However,any information that technologies generate must be translated from the organization to the workforce in a targeted way to result in sustainable change.Using a case study approach with continuous personal dust monitors(CPDMs),this paper argues for an organizational focus on technology integration.Although CPDMs provide mineworkers with near real-time feedback about their respirable coal dust exposure,they do not ensure that workers or the organization will continuously use the information to learn about and reduce exposure sources.This study used self-determination theory(SDT)to help three mines manage and communicate about information learned from the CPDM technology.Specifically,35 mineworkers participated in two mixed-method data collection efforts to discuss why they do or do not use CPDMs to engage in dust-reducing practices.Subsequently,the data was analyzed to better understand how organizations can improve the integration of technology through their management systems.Results indicate that using the CPDM to reduce sources of dust exposure is consistent with mineworkers’self-values to protect their health and not necessarily because of compliance to a manager or mine.

A NEW TECHNIQUE FOR ROADWAY DUST CONTROL IN SURFACE MINE

This paper describes a new technique for the roadway dust control in surface mine. In the method, the emulsified tar liquid with low concentration and the super water-absorbing resin are taken as dust adhesive and sprayed on the roadway. After doing a large number of in-situ experiments, the technique has shown its excellent characteristics on sticking dust, preventing water evaporation and reducing the combined cost of truck transportation.

Co-influencing mechanisms of physicochemical properties of blasting dust in iron mines on its wettability

This study explores the key physicochemical factors affecting the hydrophilic characteristics of iron mine blasting dust(BD). The BD is separated into an unwetted part(UWBD, hydrophobic part) and a wetted part(WBD, hydrophilic part). Its particle size, true density(TD), pore parameters, mineral composition, and surface compounds are comprehensively characterized and compared. The results indicate that a smaller particle size and more developed pore parameters are two key factors responsible for the strong hydrophobicity of the BD. The mineral composition of the BD has no direct effect on its wetting properties;however, it indirectly influences the deposition characteristics of the BD in water by affecting its TD. Unlike coal dust, the surface organic composition of the BD does not affect its wettability and the peak area of C–C/C–H hydrophobic groups in the C 1s X-ray photoelectron spectrum of the UWBD(45.03%) is smaller than that in the C 1s spectrum of the WBD(68.30%). Thus, eleven co-influencing processes of physicochemical properties of the BD on its wettability are summarized. This research sheds light on the key factors affecting the wettability of the BD.

Respirable Dust and Respirable Crystalline Silica Concentration in Workers of Copper Mine, Mongolia

Introduction: Prosperity in the mining industry in Mongolia has led to an increase in the number of mining workers, resulting in an increase in occupational exposures and the prevalence of occupational diseases and disabilities. The aim of this study was to assess the personal exposure of workers to respirable dust (RD) and respirable crystalline silica (RCS). Method: A cross-sectional study was conducted at the Erdenet Copper Ore Mining and included 581 personal samples of RD and 324 samples of RCS, collected in 2018-2020. Results: The study results revealed that the geometric mean (GM) of RD was 0.35 mg/m3 (95% CI 0.32 - 0.39). The RD concentration in 5.9% (n = 34) of all the samples exceeded the permissible exposure level (PEL) (3 mg/mg3). The GM of RCS was 0.012 mg/m3 (95% CI 0.010 - 0.016). In total, 12.0% (n = 39) of all RCS sample concentrations exceeded the PEL (0.1 mg/m3). Conclusion: Steel smelters, blasters, welders, and maintenance laborers were exposed to RD, while crushers, operators, drilling machinists, and maintenance laborers were exposed to RCS. Therefore, regular monitoring of the work environment, risk-based health examinations for dust-exposed workers, efficient support for dust mitigation, reduction measures at the source, and engineering controls are needed.

Does Dust from Arctic Mines Affect Caribou Forage?

This study explores how dust from the Ekati Diamond Mine potentially affects the availability and quality of forage on the seasonal range of the Bathurst caribou herd. Understanding the effects of dust as a source of disturbance is important because the Bathurst caribou population has declined by 93% since the middle 1980s and there are reports that caribou in general may avoid mining projects. There are several challenges for quantifying dust impacts: 1) Natural variations (e.g., topography, natural disturbance, and soil pH) may also impact forage availability and quality for caribou. To minimize their masking effect, we stratified survey sites into seven land cover classes and selected the most populous class (i.e., the dwarf shrub) for assessing the impact. 2) Within class variation (e.g., the proportion of area covered by rocks where vascular plants and lichen do not grow) can further skew the analysis. We eliminated this problem by examining only the area not covered by rocks. 3) Coarse and fine suspended particulates have different spatial coverages, chemical compositions, and pH values. Consequently, their impacts on caribou forage can be different. To distinguish their impacts, we sampled two areas: transects from the Misery Haul Road that has been in active use vs. those from a rarely used spur road outside the Misery Camp. We sampled percent vegetation cover, soil pH, and dust on leaves along these transects during the summers of 2015 and 2016. Our results indicated that the amount of dust on leaves in a zone of ~1000 m from the Misery Haul Road was 3 - 9 times than that of background sites. The zone of reduced lichen percent cover was also about 1000 m. In contrast, these road dust-induced changes in caribou forage were not observed for the dust-free transect from the spur road.

Dust-Holding Capacity and Bio-Chemical Changes of Plant Species Growing in an Around Opencast Mining Area of Bundelkhand Region of Uttar Pradesh, India

The present study has been carried out on a total of 50 available plant species to assess their dust-capturing capacity and biochemical performances in and around open cast granite mine areas of Jhansi district and Bundelkhand University campus treated as control site. Plant species existing under a polluted environment for a long time may be considered as potentially resistant species and recommended for green belt design in mining areas, especially to cope with dust pollution. Results showed the pollution level, especially of mining-originated dust particles holding capacity of leaves and effects of different biochemical parameters (Total Chlorophyll, Protein and Carotenoid) of existing plant species both from mining areas as well as from Bundelkhand University campus. Based on their performances, Tectona grandis L., Ficus hispida L., Calotropis procera Aiton., Butea monosperma Lam. and Ficus benghalensis L., etc. are highly tolerant species while Ficus infectoria L., Artocarpus heterophyllus Lam., Ipomoea purpurea L., Allianthus excelsa Roxb. and Bauhinia variegata L. are intermediate tolerant species. T. grandis had shown the highest dust-holding capacity (2.566 ± 0.0004 mg/cm2) whereas Albizia procera (0.018 ± 0.0002 mg/cm2) was found to be the lowest dust-holding capacity. Our findings also showed that the T. grandis and F. hispida have significant dust deposition with minimal effect of dust on their leaf chlorophyll (17.447 ± 0.019 mg/g and 14.703 ± 0.201 mg/g), protein (0.699 ± 0.001 mg/g and 0.604 ± 0.002 mg/g) and carotenoid (0.372 ± 0.003 mg/g and 0.354 ± 0.003 mg/g) content respectively among all selected plant species. Therefore, in the present investigation, plant species with high tolerance to high dust-holding capacity on their leaf surfaces are preferable for green corridors as open cast granite mines and their adjacent areas.

An analysis of contributing mining factors in coal workers’pneumoconiosis prevalence in the United States coal mines,1986-2018

In the United States,an unexpected and severe increase in coal miners’lung diseases in the late 1990s prompted researchers to investigate the causes of the disease resurgence.This study aims to scrutinize the effects of various mining parameters,including coal rank,mine size,mine operation type,coal seam height,and geographical location on the prevalence of coal worker’s pneumoconiosis(CWP)in surface and underground coal mines.A comprehensive dataset was created using the U.S.Mine Safety and Health Administration(MSHA)Employment and Accident/Injury databases.The information was merged based on the mine ID by utilizing SQL data management software.A total number of 123,589 mine-year observations were included in the statistical analysis.Generalized Estimating Equation(GEE)model was used to conduct a statistical analysis on a total of 29,707,and 32,643 mine-year observations for underground and surface coal mines,respectively.The results of the econometrics approach revealed that coal workers in underground coal mines are at a greater risk of CWP comparing to those of surface coal operations.Furthermore,underground coal mines in the Appalachia and Interior regions are at a higher risk of CWP prevalence than the Western region.Surface coal mines in the Appalachian coal region are more likely to CWP development than miners in the Western region.The analysis also indicated that coal workers working in smaller mines are more vulnerable to CWP than those in large mine sizes.Furthermore,coal workers in thin-seam underground mine operations are more likely to develop CWP.

综采工作面超前支护负压喷雾集尘器除尘效果分析

为减少超前支护粉尘,基于计算流体力学(CFD)离散粒子模型对集尘器作用下的粉尘扩散规律的数值模拟结果,结合实验测量和现场试验,研制了一种针对综采环境下超前支护粉尘源的负压喷雾集尘器。模拟结果表明:液压支架在距离液压支架迎风面0~9 m处的人行道附近形成了浓度高达1000 mg/m^(3)的高浓度粉尘带,并逐渐扩散到0~36 m处;采用负压喷雾除尘器后,液压支架背风面粉尘带浓度降至300 mg/m^(3)以下,扩散范围缩小至采煤机背风侧0~5 m;人行道附近的粉尘带形态也转变为低浓度的粉尘带。经室内试验,选择超声雾化喷嘴作为最终喷嘴,在相同的水气压力为0.4 MPa的条件下,使用该喷嘴配备的负压喷雾集尘器,有效范围为5.03 m,雾化角为71°。将研制的负压喷雾捕集器应用于塔山煤矿5110综采环境中,有效降低靠近人行道作业区推进支架的粉尘浓度,平均总降尘率和呼吸降尘率分别达到81.5%和79.1%,证实了该装置具有良好的降尘效果。

Prediction of air flow, methane, and coal dust dispersion in a room and pillar mining face

In underground coal mines, uncontrolled accumulation of methane and fine coal dust often leads to serious incidents such as explosion. Therefore, methane and dust dispersion in underground mines is closely monitored and strictly regulated. Accordingly, significant efforts have been devoted to study methane and dust dispersion in underground mines. In this study, methane emission and dust concentration are numerically investigated using a computational fluid dynamics(CFD) approach. Various possible scenarios of underground mine configurations are evaluated. The results indicate that the presence of continuous miner adversely affects the air flow and leads to increased methane and dust concentrations.Nevertheless, it is found that such negative effect can be minimized or even neutralized by operating the scrubber fan in suction mode. In addition, it was found that the combination of scrubber fan in suction mode and brattice results in the best performance in terms of methane and dust removal from the mining face.

我国金属矿山采—装—运过程中粉尘职业危害防控技术进展与展望

在高温、噪声、粉尘、有毒有害气体等金属矿山主要的职业病危害因素中,由粉尘引起的尘肺病在职业病病例中占比最大,为不断推进粉尘职业健康防护研究,保障金属矿山人员、生产与环境安全,概述了金属矿山尘源与扩散理论以及粉尘职业健康职业防护研究现状,基于安全工程系统性原理,分别从源头治理、过程控制以及个体防护3个维度分析了我国金属矿山采—装—运过程中粉尘职业危害防控技术进展。在此基础上,剖析了目前存在的不足,并展望了未来发展方向。认为现阶段存在的不足在于金属矿山粉尘控制理论体系尚未成熟,金属矿山粉尘智能化监测预警技术研究有待加强,不同粉尘治理技术交叉性、协同性研究与应用较薄弱,以及以现场人员舒适性为导向的个体呼吸防护设备研发需要进一步加强,未来可从完善金属矿山粉尘控制理论体系,开发适用于金属矿山产尘特性的智能化防尘监测预警技术,注重粉尘治理技术的交叉性、协同性研究与应用,以及研发更符合人体工程学的个体防护设备等方面进一步开展工作。

Diesel engine exhaust exposures in two underground mines

Exposure to diesel engine exhaust(DE) is a major concern in underground mines. It has been linked to cardiopulmonary diseases and is classified as a human carcinogen. The goal of this study is to assess DE exposures in workers at two underground gold mines, to compare exposure levels within and between the mines, and to compare different methods of measuring DE exposures, namely respirable combustible dust(RCD), elemental carbon(EC) and total carbon(TC). Ambient and personal breathing zone(PBZ) measurements were taken. Side-by-side monitoring of RCD and of the respirable fraction of EC and TC(EC_Rand TC_R) was carried out in the workers' breathing zone during full-shift work.Regarding ambient measurements, in addition to EC_R, TC_Rand RCD, a submicron aerosol fraction(less than 1 mm) of EC and TC was also sampled(EC_1and TC_1). Average ambient results of 240 mg/m^3 in RCD, 150 mg/m^3 in EC_Rand 210 mg/m^3 in TC_Rare obtained. Average PBZ results of 190 mg/m^3 in RCD,84 mg/m^3 in EC3Rand 150 mg/min TC_Rare obtained. Very good correlation is found between EC_Rand EC_1 with a Pearson correlation coefficient of 0.99(p < 0.01) calculated between the two logtransformed concentrations. No differences are reported between EC_Rand EC_1, nor between TC_Rand TC_1, since ratios are equal to 1.04, close to 1, in both cases. Highest exposures are reported for loadhaul-dump(LHD) and jumbo drill operators and conventional miners. Significant exposure differences are reported between mines for truck and LHD operators(p < 0.01). The average TC_R/EC_Rratio is 1.6 for PBZ results, and 1.3 for ambient results. The variability observed in the TC_R/EC_Rratio shows that interferences from non-diesel related organic carbon can skew the interpretation of results when relying only on TC data.

Evaluation of the 20 L dust explosibility testing chamber and comparison to a modified 38 L vessel for underground coal

The phenomenon of combustible dust explosions is present within many industries. Tests for explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower explosibility index values when compared to the 20 L chamber.

Aeolian Dust Forecast in Arid and Semiarid Regions of Peru and Chile and Their Contribution over Particulate Matter Concentration

The dust generated in arid areas of the planet is a very important source of particulate matter in the air, especially favoured by the presence of winds that can raise erodible material from the surface. These particles have an important influence when making an assessment of the air quality, due to its direct and indirect impact on public health. In this work, we reproduce episodes of aeolian dusts in the desert areas of Peru and Chile, where high dust concentration events are common and many mining industries are located. The differentiation of the contribution of particulate matter from Aeolian dusts and mining activities of the area is an important issue, as well as trying to forecast these events. For this purpose, we have calculated an erodibility factor at high resolution that, combined with WRF meteorological output and the GOCART dust scheme, gives the emission of particulate matter. We have introduced the emissions in the photochemical model CMAQ, which determines the concentrations in the different domains, and we have observed that the natural dust contributes greatly to pollution in the area, exceeding permissible limit values in the area of Paracas in Peru, and with contributions of up to 23% of the total particulate matter in the city of Calama in Chile, resulting non-negligible values for the evaluation of air quality.

我国非煤矿山职业健康防控技术研究现状、挑战及展望

矿业是现代工业的粮食,在国民经济发展中发挥着不可替代的作用,但采矿过程伴随众多职业危害因素,给工人职业健康与安全造成极大影响。采用文献查阅、现场调研、访谈交流等方法,并基于团队已有研究积累,对新中国成立以来我国非煤矿山职业健康防控技术研究现状进行了综述,并分析了当前面临的主要挑战。结果表明:我国非煤矿山职业危害主要涉及粉尘、噪声、高温等7类因素,存在“点多、面广、源强”的显著特点,防治难度大;在7类职业危害因素中,粉尘危害最为突出,且爆破粉尘、强疏水性微细粉尘、井下喷浆粉尘与高寒、低气压、超大规模开采粉尘防治是目前面临的主要挑战。在上述分析的基础上,指出我国非煤矿山职业健康防护技术未来发展方向为健全非煤矿山职业危害监管体系、强化职业危害控制科技创新与实践、推行职业危害防控专业化社会服务、坚持职业危害个性化与综合防治、探索职业危害智能化防治技术,逐步形成以监管落实为驱动、科技创新为抓手、社会服务为目标的科学发展模式,切实提高非煤矿山职业危害因素防治效果,保障工人职业健康与安全。

Development of Emission Factors for Quantification of Blasting Dust at Surface

Environmental impact assessment (EIA) and environmental management plan (EMP) is a statutory requirement for execution of new mining projects or for expansion of the operating projects. For this purpose, quantification of blasting dust emission is required. This can be done by developing emission factors for blasting. The concept is similar to that of specific charge in blasting. For mining operations other than blasting, quantification of dust can be done using emis- sion factors. Emission estimation techniques are very limited for blasting. In this study, the emission factors were de- veloped by carrying out a detailed field study at one of the largest opencast coal mines of India in all four seasons. Da- ta on atmospheric and meteorological conditions were generated by installing sodar and automatic weather station at the mine site. Respirable dust samplers were installed for monitoring of the dust emitted during coal or overburden bench blasting. Emission factors for dust concentrations were developed in gram per cubic meter of rock excavated. The developed emission factors were used to estimate dust emissions for adjacent mines due to similarity in mining and meteorological conditions. Seasonal variations in moisture contents in benches, where dust was monitored, indicated the lowest emission factors in monsoon due to high moisture in the bench materials. Similar field studies were also conducted at another coalfield of India for two seasons. It was found that the emission factors are site-specific.