Search Results (15)

As the world’s largest open-pit coal producer, China faces severe dust pollution in mining operations. Cabins of mining equipment (electric shovels, haul trucks, drills) exhibit unique micro-environmental contamination due to dual-source pollution (external infiltration and internal secondary dust generation), posing severe health risks to miners. This study focused on electric shovel cabins at the Heidaigou open-pit coal mine to address cabin dust pollution. Through analysis of dust physicochemical properties, a pollution characteristic database was established. Field measurements and statistical methods revealed temporal–spatial variation patterns of dust concentrations, quantifying occupational exposure risks and providing theoretical foundations for dust control. A novel gradient-pressurized air purification system was developed for harsh mining conditions. Key findings include the following. (1) Both coal-shovel and rock-shovel operators were exposed to Level I (mild hazard level), with rock-shovel operators approaching Level II (moderate hazard level). (2) The system reduced respirable dust concentrations from 0.313 mg/m³ to 0.208 mg/m³ (≥33.34% improvement) in coal-shovel cabins and from 0.625 mg/m³ to 0.421 mg/m³ (≥32.64% improvement) in rock-shovel cabins. These findings offer vital guidance for optimizing cabin design, improving dust control, and developing scientific management strategies, thereby effectively protecting miners’ health and ensuring operational safety. Full article

Phytostabilization of metals involves the inactivation of metals in the soil through the use of various materials as soil amendments, which reduces the bioavailability of metals, and then the introduction of vegetation. There are limited data comparing the effectiveness of different phytostabilization amendments under the same soil and environmental conditions. Therefore, the aim of this research was to compare the effectiveness of a range of soil amendments on reducing the extractability of metals, metal uptake by plants, microbial activity in soil and nutrient availability to plants. Eight materials potentially limiting metal availability were used in a pot experiment: two composts (CG, CM), municipal biosolids (SB), bentonite (BEN), phosphorus fertilizer (PF), amorphous iron oxide (FE), waste rock material (WR), calcium carbonate (LM); and these materials were compared with typical fertilization (NPK) and an untreated soil as the control (CTL). The following trace metal-contaminated soils were used in the pot experiment: soil taken from the area of strong dust fall from the zinc and lead smelter (soil P); soil taken from an outcrop of ore-bearing rocks near a smelter waste heap (soil H); soil artificially polluted through smelter dust spill in the 1990s (soil S). In general, the greatest yields of plants (oat and white mustard) were recorded for compost-treated soils. Changes in the solubility of zinc (Zn) and cadmium (Cd) after the application of various amendments largely reflected changes in soil pH. Biosolids caused a significant increase in extractable Zn and Cd, which was related to the decrease in soil pH, while a significant reduction in Cd extractability was observed across soils after the application of both composts, especially the compost characterized by alkaline pH. Interestingly, low extractability of Cd in the soil with the addition of another compost was observed, despite the pH decrease, as compared to the control pots. This fact proves the high sorption capacity of the compost towards Cd. The microbiological analyses revealed the highly beneficial effect of composts for dehydrogenases and nitrification activities, and for soil respiration, whereas soil amendment with iron oxide caused an increase in respiration activity across soils. Full article

This study investigates the correlations between the wear conditions of conical pick cutters and key variables such as the physical properties (shape, aspect ratio, roughness), explosive potential, health and safety implications, and particle size distribution of coal dust and larger fragments using the linear cutting machine (LCM). This research was conducted within the framework of recent regulatory developments, notably implementing the new silica rule in the mining and construction sectors and climate change consideration. This study reveals critical insights into optimizing operational processes while adhering to stringent health and safety regulations. The findings indicate that as cutting tools wear, there is a significant increase in generated fine particles, including respirable crystalline silica (RCS), which elevates the risk of respiratory diseases and, in the case of coal dust, a higher potential for explosions. The results show that the silica content in respirable dust is a function of rock mineralogy; however, the results showed that the absolute amount of silica-containing dust increased with bit wear in rocks containing pertinent minerals. For the larger fragments, the new bit produced a 1699 fragment count, while the completely worn-out bit produced a 5608 count. The results of the dust concentration show that the new bit produces 89.2 mg/m³ (17.84%); the moderate bit produces 165.1 mg/m³ (33.03%), and the worn-out bit produces 245.6 mg/m³ (49.13%). Moreover, this study highlights the impact of bit wear on the production of larger fragments, which decreases with tool degradation, further contributing to dust generation. These results suggest the necessity for proactive equipment maintenance, enhanced dust control measures, and continuous monitoring of cutting tool wear to ensure compliance with regulatory standards and to protect workers’ health and safety. Full article

Current regulations mandate the monitoring of respirable coal mine dust (RCMD) mass and crystalline silica in underground coal mines to safeguard miner health. However, other RCMD characteristics, such as particle size and chemical composition, may also influence health outcomes. This study collected RCMD samples from two underground coal mines and performed detailed chemical speciation. Source apportionment was used to estimate RCMD and silica contributions from various sources, including intake air, fire suppression limestone dust, coal dust, diesel engine exhaust, and rock strata. The mine dust mass-based size distributions were comparable to those recorded over a decade ago, with a peak around 10 μm and the majority of the mass in the supermicron size range. The current mine conditions and mining practices do not appear to have significantly increased the generation of smaller particles. Limestone rock dust was prevalent in many locations and, along with coal dust, was the main contributor to RCMD at high-concentration locations. Silica accounted for over 10% of RCMD mass at several active mining locations, primarily from limestone and rock strata dust. Reducing the concentration of limestone dust and its silica content could reduce RCMD and silica levels. Further cleaning of the intake air could also improve the overall mine air quality. Full article

China faces a challenge in the sustainable development of the coal industry due to pneumoconiosis problems. Dust control technologies are crucial for safe production and miners’ health, ensuring the industry’s longevity. This article reviews the development process of dust prevention and control in underground coal mines in China, summarizes various technologies, and divides them into dust suppression, open-space dust reduction, and mine dust collectors according to different stages and environments of use. In dust suppression technologies, coal-seam water injection can reduce total dust generation by 60%, wet rock drilling can reduce drilling dust in the presence of stable water sources and high-pressure bearing equipment, and water-seal blasting can reduce blasting dust by 50–70%. In open-space dust reduction technologies, spray dust suppression can remove total dust by 50–95% and the removal efficiencies of foam dedusting for total and respirable dust are reported to reach 95% and 85% under the right conditions, respectively. In dust collector technologies, dry collectors can remove 80–95% of total dust. Wet collectors achieve up to 90% efficiency, dependent on water supply and waste processing. This article also discusses vapor heterogeneous condensation technology as a promising method for improving respirable dust removal in humid mine environments. Full article

Respirable coal mine dust (RCMD) exposure is one of the utmost health hazards to the mining community causing various health issues, including coal worker pneumoconiosis (CWP). Considering multiple potential sources of RCMD having different physicochemical properties within the same mine suggests a wide range of health impacts that have not yet been studied extensively. In this work, we investigate the toxicity of lab-created RCMD based on different sources: coal seam, rock dust, host floor, and host roof collected from the same mine. Comparative samples obtained from several mines situated in various geographic locations were also assessed. This work quantifies metal leaching in simulated lung fluids and correlates dissolution with in vitro immune responses. Here, dissolution experiments were conducted using two simulated lung fluids; Gamble solution (GS) and artificial lysosomal fluid (ALF). In vitro studies were performed using a lung epithelial cell line (A549) to investigate their immune responses and cell viability. Si and Al are the most dissolved metals, among several other trace metals, such as Fe, Sr, Ba, Pb, etc. RCMD from the coal seam and the rock dust showed the least metal leaching, while the floor and roof samples dissolved the most. Results from in vitro studies showed a prominent effect on cell viability for floor and roof dust samples suggesting high toxicity. Full article

Respirable crystalline silica is now considered to be a major culprit of resurgent lung disease among US coal miners—especially in central Appalachia—though questions remain regarding the specific circumstances around exposure to it. As part of a larger investigation of dust in 15 US coal mines, a recent study examined the silica content in both the respirable mine dust samples and the samples of respirable dust generated in the laboratory from primary source materials (i.e., coal and rock strata and rock dusting products). It concluded the rock strata that is being drilled for roof bolting or is being cut along with the coal is the most significant source of respirable silica in many mines, which is consistent with the expectations based on other scattered datasets. However, little information is available on the characteristics of respirable silica particles which might be important for understanding the exposure risks better. In the current study, which represents another part of the aforementioned investigation in 15 mines, scanning electron microcopy with energy dispersive X-ray spectroscopy (SEM–EDX) were used to analyze the size and surface condition (i.e., degree of surface-associated clay) of 1685 silica particles identified in 58 respirable mine dust samples. The results indicated that silica is typically finer in locations nearby to drilling and cutting activities than it is in other locations within a mine, but the silica in the Central Appalachian mines is not necessarily finer than it is in the mines in other regions. An analysis of the particle surfaces revealed that respirable silica in coal mines often does not occur as “free”, high-purity particles. Rather, there can be a range of occurrences including silica particles having a thin “occlusion” layer of clay, silica within agglomerates that can also contain other particle types including clays, or even silica ingrained within other particles such as coal. Full article

An ongoing resurgence of occupational lung disease among coal miners in the United States has been linked to respirable crystalline silica (RCS). To better protect miners, a deeper understanding of key exposure factors is needed. As part of a larger investigation of RCS in 15 coal mines, this paper describes analysis of silica mass content in two types of samples: (1) respirable coal mine dust (RCMD) collected in standardized locations in each mine; and (2) respirable dust generated in the laboratory from primary source materials, including coal and rock strata being mined at the production face, material obtained from the dust collection system on roof bolter machines, and rock dust products being applied by the mine. As expected, results indicate that rock strata drilled for roof bolting or being extracted along with the coal are a major source of RCS in many coal mines—although the coal seam itself can contain significant silica in some mines. While silica content of rock strata encountered in central Appalachian mines is not necessarily higher than in other regions, the sheer abundance of rock being extracted in thin-seam central Appalachian mines can explain the relatively higher silica content typically observed in RCMD from this region. Full article

Respirable rock dust poses serious long-term health complications to workers in environments where mechanical rock excavation is utilized. The purpose of this study is to characterize respirable dust generated by cutting limestone with new, partially worn, and fully worn conical pick wears. Characterizing limestone respirable dust can aid in decision making for respirable dust suppression levels and exposures throughout the lifetime of a pick in underground mining and engineering activities. The methods include full scale cutting of a limestone sample in the laboratory with three conical picks at different stages of wear. Dust samples were collected during cutting with various instruments connected to pumps and subsequently analyzed to determine the concentrations, mineralogy, particle shapes, and particle size distributions. The results show that the worn pick generated the highest concentration of dust, all picks generated dust containing quartz, all three picks generated dust particles of similar shapes, and all three picks generated various particle size distributions. In conclusion, a preliminary suite of respirable dust characteristics is available and with further future additional studies, results could be used for the evaluation of possible strategies and methods of dust suppression and exposures during mining, tunneling, or drilling activities. Full article

Snow cover in environmental monitoring is a valuable resource for information on sources of air pollutants and the level of air pollution. Research in areas of intense industrial pressure without systematic air quality control is of particular importance in this aspect. This is the case in the vicinity of Łagów (an urban–rural municipality) in the eastern part of the Świętokrzyskie Mountains (southern Poland), where rock mining fields have been created over a large area. Limestone, marly limestone and dolomite are mined in this area. The carbonate dust accumulated during the two-week deposition significantly altered the physicochemical and chemical properties of the snow cover. An inductively coupled plasma-mass spectrometer-time-of-flight (ICP-MS-TOF), Dionex 3000 ion chromatograph and Hach HQ2200 water quality meter were used for chemical analyses. The pH, electric conductivity (EC), major ions and selected heavy metals (HM) were determined in water samples obtained after snow melt in two measurement campaigns. The comparative analysis performed showed an increase in pH, EC, Cl, Ca, NO₃, SO₄ and heavy metals in samples from the two-week old cover (second series) compared to fresh snow (first series). The conducted research indicates a potential hazard for the inhabitants of Łagów due to respirable dusts released into the atmosphere during extraction, processing and transport of rock materials. Full article

An experimental study on the flow rate and atomization characteristics of a new gas–liquid two-phase flow nozzle was carried out to use high-concentration respirable dust in the workplace of high-efficiency sedimentation coal production based on the gas–liquid two-phase flow nozzle technology. The simulation roadway of dust fall in large coal mines was constructed, and the respirable rock dust produced by fully mechanized mining surfaces was chosen as the research object. The effects of humidity on the capture effect of respirable rock dust were analyzed in the experimental study. The results demonstrated that: (1) the distribution range of the particle size of fogdrops declines with the reduction in fogdrops D₅₀, D_[3,2] and D_[4,3], which are produced by gas–liquid two-phase flow nozzles. (2) The initial ambient humidity in the simulated roadway was 64.8% RH. After the gas–liquid two-phase flow spray was started, the ambient humidity was elevated by 23.2 to 23.5% RH within 840s and tended to be stable and no longer grew after reaching 88.0–88.3% RH. The initial growth rate of the ambient humidity in the simulated roadway was high, and then was gradually slowed down. (3) Humidity is an important factor influencing the collection of respirable dust. The humidity at 10.0 m leeward of the dust-producing point was increased by 19.6% RH, and the sedimentation rate of respirable dust was increased by 6.73%; the two growth rates were 13.1% RH and 9.90% at 20.0 m; 16.4% RH and 15.42% at 30.0 m; 18.4% RH and 11.20% at 40.0 m. In practical applications of the gas–liquid two-phase flow nozzle in coal mining activities, attention shall be paid to not only the influences of its atomization characteristics on the capture effect of respirable dust but also the influences of the flow rate of the nozzle on the humidity of the working surface. Appropriate gas and water supply pressures shall be chosen according to the space and respirable dust concentration on the working surface to realize a better dust removal effect. Full article

Application of fine, inert ‘rock dust’ (RD) to the surfaces in underground coal mines is a common method for mitigating coal dust explosion hazards. However, due to its size, RD has the potential to contribute to the respirable coal mine dust (RCMD) concentration. Though the RD component of RCMD does not appear to pose the sort of health hazards associated with other components such as crystalline silica, understanding its relative abundance may be quite helpful for evaluating and controlling primary dust sources. Given that RD products are frequently comprised of high-purity limestone (i.e., primarily calcite mineral), calcite may serve as a suitable proxy for measuring RD. To estimate the mass percentage of calcite in RCMD samples, this study demonstrates the successful application of direct-on-filter (DOF) Fourier-transform infrared (FTIR) spectroscopy. Incidentally, DOF FTIR has been the focus of recent efforts to enable rapid measurement of crystalline silica in RCMD. Concurrent measurement of other constituents such as calcite is thus a logical next step, which can allow a broader interpretation of dust composition and source contributions. Full article

Respirable coal mine dust represents a serious health hazard for miners. Monitoring methods are needed that enable fractionation of dust into its primary components, and that do so in real time. Near the production face, a simple capability to monitor the coal versus mineral dust fractions would be highly valuable for tracking changes in dust sources—and supporting timely responses in terms of dust controls or other interventions to reduce exposures. In this work, the premise of dust monitoring with polarized light microscopy was explored. Using images of coal and representative mineral particles (kaolinite, crystalline silica, and limestone rock dust), a model was built to exploit birefringence of the mineral particles and effectively separate them from the coal. The model showed >95% accuracy on a test dataset with known particles. For composite samples containing both coal and minerals, the model also showed a very good agreement with results from the scanning electron microscopy classification, which was used as a reference method. Results could further the concept of a “cell phone microscope” type monitor for semi-continuous measurements in coal mines. Full article

Respirable coal mine dust (RCMD) particles, particularly the nano-sized fraction (<1 μm) of the RCMD if present, can cause severe lung diseases in coal miners. Characterization of both the particle size and chemical composition of such RCMD particles remains a work in progress, in particular, with respect to the nano-sized fraction of RCMD. In this work, various methods were surveyed and used to obtain both the size and chemical composition of RCMD particles, including scanning electron microscopy (SEM), scanning transmission electron microscopy (S-TEM), dynamic light scattering (DLS), and asymmetric flow field-flow fractionation (AsFIFFF). It was found that the micron-sized fraction (>1 μm) of RCMD particles collected at the miner location, from an underground coal mine, contained more coal particles, while those collected at the bolter location contained more rock dust particles. Two image processing procedures were developed to determine the size of individual RCMD particles. The particle size distribution (PSD) results showed that a significant amount (~80% by number) of nano-sized particles were present in the RCMD sample collected in an underground coal mine. The presence of nano-sized RCMD particles was confirmed by bulk sample analysis, using both DLS and AsFIFFF. The mode particle size at the peak frequency of the size distribution was found to be 300–400 nm, which was consistent with the result obtained from SEM analysis. The chemical composition data of the nano-sized RCMD showed that not only diesel particles, but also both coal and rock dust particles were present in the nano-sized fraction of the RCMD. The presence of the nano-sized fraction of RCMD particles may be site and location dependent, and a detailed analysis of the entire size range of RCMD particles in different underground coal mines is needed. Full article

The South African mining industry is one of the largest producers of platinum (Pt) in the world. Workers in this industry are exposed to significant amounts of dust, and this dust consists of particles sizes that can penetrate deep inside the respiratory region. A cross-sectional study was conducted to evaluate dust exposure risk at two Pt mine waste rock crusher plants (Facility A and B) in Limpopo, South Africa. Workers’ demographic and occupational information was collected through a structured questionnaire, a walk-through observation on facilities’ processes, and static dust sampling for the collection of inhalable and respirable dust particles using the National Institute for Occupational Safety and Health (NIOH) 7602 and the Methods for Determination of Hazardous Substance (MDHS) 14/4 as guidelines. Only 79% of Pt mine workers, used their respiratory protective equipment (RPE), sixty-five percent were exposed to work shifts exceeding the recommended eight hours and 8.8% had been employed for more than ten years. The mean time-weighted average (TWA) dust concentrations between Facility A and B showed a significant difference (p < 0.026). The Pt mine’s inhalable concentrations (range 0.03–2.2 mg/m³) were higher than the respirable concentrations (range 0.02–0.7 mg/m³), however were all below the respective international and local occupational exposure limits (OELs). The Pt mine’s respirable crystalline silica (SiO₂) quartz levels were all found below the detectable limit (<0.01 mg/m³). The Pt miners had increased health risks due to accumulated low levels of dust exposure and lack of usage of RPE. It is recommended that an improved dust control program be put in place which includes, but is not limited to, stockpile enclosures, tire stops with water sprays, and education on the importance of RPE usage. Full article