Life cycle assessment of underground coal mining in China

Plasma club cell secretory protein reflects early lung injury: comprehensive epidemiological evidence

BACKGROUND

It is inaccurate to reflect the level of dust exposure through working years. Furthermore, identifying a predictive indicator for lung function decline is significant for coal miners. The study aimed to explored whether club cell secretory protein (CC16) levels can reflect early lung function changes.

METHODS

The cumulative respiratory dust exposure (CDE) levels of 1,461 coal miners were retrospectively assessed by constructed a job-exposure matrix to replace working years. Important factors affecting lung function and CC16 were selected by establishing random forest models. Subsequently, the potential of CC16 to reflect lung injury was explored from multiple perspectives. First, restricted cubic spline (RCS) models were used to compare the trends of changes in lung function indicators and plasma CC16 levels after dust exposure. Then mediating analysis was performed to investigate the role of CC16 in the association between dust exposure and lung function decline. Finally, the association between baseline CC16 levels and follow-up lung function was explored.

RESULTS

The median CDE were 35.13 mg/m3-years. RCS models revealed a rapid decline in forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and their percentages of predicted values when CDE exceeded 25 mg/m3-years. The dust exposure level (<5 mg/m3-years) causing significant changes in CC16 was much lower than the level (25 mg/m3-years) that caused changes in lung function indicators. CC16 mediated 11.1% to 26.0% of dust-related lung function decline. Additionally, workers with low baseline CC16 levels experienced greater reductions in lung function in the future.

CONCLUSIONS

CC16 levels are more sensitive than lung indicators in reflecting early lung function injury and plays mediating role in lung function decline induced by dust exposure. Low baseline CC16 levels predict poor future lung function.

Life cycle assessment of electrolytic manganese metal production

Manganese is an indispensable metal widely used in various fields. China ranks as the fourth-largest producer of manganese ore and the largest producer of electrolytic manganese metal (EMM). However, EMM production is linked to high energy consumption and pollution. This study conducts a life cycle assessment (LCA) of EMM production in the Manganese Triangle region of China to comprehensively evaluate its environmental impact. Results show that Human carcinogenic toxicity, mainly from electricity generation (65.3 %) and mining activities (24.4 %), is the most significant environmental impact. Chromium (VI) is identified as the predominant hazardous substance, contributing up to 91 % to Human carcinogenic toxicity. Endpoint results estimate that the production of 1 t of EMM results in 1.01E-02 DALY of harm to human health, 1.97E-05 species.yr of harm to the ecosystem, and $227.15 worth of resource depletion. Simulation scenarios demonstrate that replacing thermal power with hydropower can reduce environmental pollution by over 90 %. Finally, based on the findings, technical measures for promoting clean production of EMM were proposed.

Comparative analysis of life cycle assessment of biogas-powered and coal-powered power plant for optimized environmental operation

The major concerns that mankind faces today are limited reserves of conventional energy, growing energy demand, and environmental pollution. This study depicts a comparative analysis done for the life cycle assessment of the biogas-based plant and coal-based plant designed for Bikaji Foods International Ltd., India. OpenLCA version 1.11.0 software was used with the database ecoinvent 3.3 LCIA methods (ReCiPe Midpoint H) to analyze the environmental impact and investigate the effect of the biogas-based plant and the coal-based plant. The functional unit of 1 MJ of energy generated from biogas and coal was selected to represent the results of the production of 15,271,600 MJ of energy. The results for marine eutrophication, particulate matter formation, photochemical oxidant formation and terrestrial acidification for the biogas-based plant were 734.527 kg N-Eq, 6314.012 kg PM10-Eq, 1328.629 kg NMVOC and 3.933E04 kg SO2-Eq, respectively. Whereas, for coal-based plant, these values were 4919.442 kg N-Eq, 1.962E04 kg PM10-Eq, 6486.987 kg NMVOC and 13.448E04 kg SO2-Eq, respectively. The greenhouse gas emissions and fossil depletion from the biogas-based plant were found negligible as compared to the coal-based plant. Overall, it was found that the biogas-based plant has a more remunerative impact on the environment than the coal-based plant. This study recommends that local authorities and industrial communities should invest more and more in increasing the number of biogas plants at domestic as well as commercial levels and secure a clean and green future for coming generations.

Fostering green technology innovation with green credit: Evidence from spatial quantile approach

Green technology is an important path to achieve low-carbon development, and green credit provides financial support for green technology innovation. Existing literature often fails to pay attention to the important role of spatial factors and outliers in green technology innovation. Based on 2005-2022 provincial panel data in China, this paper uses a novel spatial lag quantile model to explore the impact of green credit on green technology innovation and its impact mechanism. The empirical results indicate that green credit exerts a greater positive impact on green technology in the provinces with moderate technical level. Technological innovation has the characteristic of spatial spillover. The spatial spillover of technology contributes more to green technology innovation in the provinces with low- and medium-tech level. This result has been proven even after robustness test of the changes in sample units, and the replacement of core variable values. Further mechanistic analysis demonstrates that banking market structure and enterprise R&D investment both produces the greater impact on green technology innovation in the low-tech provinces such as Qinghai, Ningxia, and Hainan. This article provides policy reference for local governments to formulate green finance policies and promote carbon neutrality strategies.

Assessing the environmental impact of gold production from double refractory ore in a large-scale facility

Despite the strict environmental management regulations, there is still a considerable adverse impact on the ecosystem and human health when it comes to large-scale gold mining operations. Gold mining is an energy-intensive process that can discharge substantial quantities of chemicals combined with gaseous emissions into the environment. Considering gold mining's significant role in Nevada's economy and the growing concern about climate change, it's necessary to investigate the environmental burdens of this sector. To provide a comprehensive environmental perspective on the large-scale gold mining operations in Nevada, this study used a life cycle assessment (LCA) approach to evaluate the environmental burdens of gold production from double refractory ores in the roasting process. The Tool for Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) method was used to evaluate the categories of acidification, ozone depletion, global warming, smog, carcinogenics, non-carcinogenics, respiratory effects, and fossil fuel depletion. Results showed that major contributors to greenhouse gas (GHG) emissions were grinding and off-gas treatment stages being responsible for 34.80 % and 56.10 % of the total global warming, respectively. The carbon footprint for producing one kg of gold was 12,200 kg CO2-eq. Sensitivity analysis was also employed on electricity to observe the influence of electricity on key contributor stages. A 10 % change in electricity reduced the GHG emissions in crushing and grinding by 12.2 % and 7.10 %, respectively, while delivering an insignificant effect on the off-gas treatment. Significantly, this study stands as the first initiative to apply LCA in the North American mining industry, with a unique focus on the off-gas treatment post-roasting and its associated emissions. Our findings can serve as a foundational database, aiding stakeholders in making informed decisions and enhancing sustainable practices in the gold mining industry.

Assessment of heavy metal contamination in street dust: concentrations, bioaccessibility, and human health risks in coal mine and thermal power plant complex

Coal mining has also been associated with adverse environmental and health impacts including cancer and respiratory disorders, with the presence of thermal power plants exacerbating the problem of heavy metal pollution. Minimal studies have been conducted on the environmental impacts, health risks, and bioaccessibility of heavy metals in coal mine areas. Consequently, samples of street dust were collected from different locations in the Singrauli mine complex and analysed. Heavy metals (Cu, Ni, Zn, Cr, Co, As, and Mo) were found to be higher than the background concentration, with the maximum concentration was found in areas close to the Thermal Power Plants, like Near Vindyachal TPP, Near Shakti Nagar TPP, and Anpara. The highest geo-accumulation index value was found for Co, Mo, Zn, and As, indicating moderate to strong pollution levels. Health risk assessment (for both adults and children) revealed that Cr and Fe posed significantly higher Hazard Quotient and Hazard Index (HI) values, indicating significant non-carcinogenic threats. Moreover, Carcinogenic Risk (CR) values for Cd, Cr, and Ni indicated a risk of carcinogenicity to the public exposed to road dust. The study also examined the bioaccessibility of the metals, which showed that the gastric phase accumulated a higher percentage of Ni (42.52%), Pb (34.79%), Co (22.22%), As (20%) and Cu (15%) than the intestinal phase. Strong positive correlation was observed between metal concentration (Cu, Pb, Cr, Fe, Zn, and Mn), HI, and CR of adult and child, while bioaccessibility of intestinal phase was positively correlated with gastric phase of metals (Cu, Ni, Co, As, and Mn).

Impacts of high-quality coal mine drainage recycling for replenishment of aquatic ecosystems in arid regions of China: Bacterial community responses

Coal mine water is usually recycled as supplementary water for aquatic ecosystems in arid and semiarid mining regions of China. To ensure ecosystem health, the coal mine water is rigorously treated using several processes, including reverse osmosis, to meet surface water quality standards. However, the potential environmental impacts of this management pattern on the ecological function of receiving water bodies are unclear. In this study, we built several microcosm water ecosystems to simulate the receiving water bodies. High-quality treated coal mine drainage was mixed into the model water bodies at different concentrations, and the sediment bacterial community response and functional changes were systematically investigated. The results showed that the high-quality coal mine drainage could still shape bacterial taxonomic diversity, community composition and structure, with a concentration threshold of approximately 50%. Moreover, both the Mantel test and the structural equation model indicated that the salinity fluctuation caused by the receiving of coal mine drainage was the primary factor shaping the bacterial communities. 10 core taxa in the molecular ecological network influenced by coal mine drainage were identified, with the most critical taxa being patescibacteria and g_Geothermobacter. Furthermore, the pathway of carbohydrate metabolism as well as signaling molecules and interactions was up-regulated, whereas amino acid metabolism showed the opposite trend. All results suggested that the complex physical-chemical and biochemical processes in water ecosystems may be affected by the coal mine drainage. The bacterial community response and underlying functional changes may accelerate internal nutrient cycling, which may have a potential impact on algal bloom outbreaks.

Hydrogeochemical evolution induced by long-term mining activities in a multi-aquifer system in the mining area

The hydrogeochemical evolution of groundwater is related to and affected by long-term mining activities, which may deteriorate the quality of groundwater. The Fengfeng mine in Handan, North China has a 30-y history of coal mining with long-term mining activities and complex geological conditions, resulting in a complex hydrogeochemical environment in the mining region. In this study, the hydrogeochemical evolution mechanism of groundwater in a multi-aquifer system in the Fengfeng Mining Area was investigated using machine learning (self-organizing maps combined with K-means clustering) and sulfur and oxygen isotopes (δ34SSO4 and δ18OSO4). The hydrogeochemical characteristics of different aquifers in the mining area changed to different degrees after mining compared with the characteristics before mining. The spatiotemporal variations in groundwater components were found to be controlled by pyrite oxidation, gypsum dissolution, and carbonate dissolution, which are affected by mining activities. Pyrite oxidation primarily occurred in the Carboniferous thin-layer limestone aquifer (CLA) and Permian sandstone aquifer (PSA). The hydrogeochemical evolution in the Ordovician limestone aquifer (OLA), the main aquifer in the study area, was affected by leakage recharge from CLA and PSA caused by mining activities. The results showed that owing to the effects of long-term mining, the altered groundwater flow system affected the evolution of groundwater components in each aquifer, particularly the sulfate concentration. This study reveals a distinct hydrogeochemical evolution induced by mining activities, which can provide a basis for groundwater resource management in mining areas.

Environmental impact of mining and beneficiation of copper sulphate mine based on life cycle assessment

China is a major producer of copper concentrate as its smelting capacity continues to expand dramatically. The present study analyzes the life cycle environmental impact of copper concentrate production, along with selection of a typical copper sulphate mine in China. Life cycle assessment (LCA) was conducted using SimaPro with ReCiPe 2016 method. The midpoint and endpoint results were performed with uncertainty information based on Monte Carlo calculation. Normalization of midpoint results revealed that impact from the marine ecotoxicity category was the largest contributor to the total environmental impact, followed by freshwater ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity, and terrestrial ecotoxicity. The mining activity, backfilling activity, and electricity generation were proved to be the dominant factors. In addition, main processes and substances to the identified key categories were also classified. Specifically, the cement production in the backfilling process, blasting activity, on-site emission, and electricity generation was regarded as the critical processes. Copper to air and zinc emission to water were considered the critical substances. The sensitivity analysis revealed the most effective measure to solve the environmental problems caused by the concentrate production process, which is controlling on-site emissions and reducing pollution from cement production. Finally, the corresponding technical and management measures were proposed to facilitate the development of cleaner metal industry.

Allocating environmental costs of China's rare earth production to global consumption

China provides over 80% of global rare earth (RE) that caused serious domestic environmental impacts. However, how much RE-related pollution was transferred to China along global supply chain remains poorly understood. Here we, for the first time, established the RE industry-specific input-output approaches to trace environmental costs transfer through China's RE exports from whole supply chain perspective. We found that foreign consumption contributed over half of the environmental costs from China's RE production, with a gross value increasing from $4.8 billion (65% of total environmental costs) in 2010 to $5.4 billion in 2015 (74% of total environmental costs). Countries in the East Asia (i.e., Japan and South Korea) made the largest contribution (27-37%) to the exports induced environmental costs, followed by North America (i.e., the United States, Mexico, and Canada) with a contribution of 20-27% and the rest East Asia (including countries in Asia-Pacific except China Mainland, by 16-23%). Exports induced environmental costs were mainly from RE raw materials (60%) and high value-added products (22%). Suggestions such as rationalizing RE cost as well as production- and consumption-based measures to mitigate environmental impacts were proposed to enhance RE utilities for global sustainable development.

Landscape Pattern Evolution in a Mining City: An Urban Life Cycle Perspective

Quantitative studies on how mining activities shape the evolution of regional landscape patterns can contribute to the scientific understanding of how mining cities develop. Based on the theories of life cycle and landscape ecology, this paper takes Jixi, a typical Chinese mining city, as a case study to analyze the landscape pattern features at different mining city development stages. First, we constructed a mining city development cycle index system. Second, the optimal granularity for landscape pattern analysis was determined. Finally, landscape evolution was analyzed at the type and landscape levels based on the mining city development cycle. The main conclusions are: (1) Jixi has gone through four stages since 1990: lead-in (1990–1998), development (1998–2009), maturity (2009–2016), and transition (2016–2020); (2) the optimal grain size for landscape pattern analysis is 90 m; (3) through the various development stages, the landscape fragmentation degree, complexity, and diversity show a tendency to rise first and then fall. Thus, mining cities should carry out sustainable development planning from the perspective of industrial transformation in the early stages, and policy orientation in the development process should have different emphases according to each stage.

Ecological Impact Prediction of Groundwater Change in Phreatic Aquifer under Multi-Mining Conditions

In aeolian sandy grass shoal catchment areas that rely heavily on groundwater, mining-induced geological deformation and aquifer drainage are likely to cause irreversible damage to natural groundwater systems and affect the original circulation of groundwater, thus threatening the ecological environment. This study aimed to predict the impact of groundwater level decline on vegetation growth in the Hailiutu River Basin (HRB), which is a coal-field area. Based on remote-sensing data, the land use/cover change was interpreted and analyzed, and the central areas of greensward land in the basin were determined. Subsequently, the correlation between groundwater depth and grassland distribution was analyzed. Then, the groundwater system under natural conditions was modeled using MODFLOW, and the groundwater flow field in 2029 was predicted by loading the generalized treatment of coal mine drainage water to the model. The change in groundwater depth caused by coal mining and its influence on the grassland were obtained. The results show that coal mining will decrease the groundwater depth, which would induce degradation risks in 4 of the original 34 aggregation centers of greensward land that originally depended on groundwater for growth in HRB because they exceeded the groundwater threshold. The prediction results show that the maximum settlement of groundwater level can reach 5 m in the northern (Yinpanhao), 6 m in the eastern (Dahaize), and 10 m in the southern (Balasu) region of HRB. Attention should be paid to vegetation degradation in areas where groundwater depth exceeds the minimum threshold for plant growth.

Intelligent Measurement of Coal Moisture Based on Microwave Spectrum via Distance-Weighted kNN

Realizing the rapid measurement of coal moisture content (MC) is of great significance. However, existing measurement methods are time-consuming and damage the original properties of the samples. To address these concerns, a coal MC intelligent measurement system is designed in this study that integrates microwave spectrum analysis and the distance-weighted k-nearest neighbor (DW-kNN) algorithm to realize rapid and non-destructive measurement of coal MC. Specifically, the measurement system is built using portable microwave analysis equipment, which can efficiently collect the microwave signals of coal. To improve the cleanliness of modeling data, an iterative clipping method based on Mahalanobis distance (MD-ICM) is used to detect and eliminate outliers. Based on multiple microwave frequency bands, various machine learning methods are evaluated, and it is found that coal MC measurement using broad frequency signals of 8.05–12.01 GHz yields the best results. Experiments are also carried out on coals from different regions to examine the regional robustness of the proposed method. The results of on-site testing with 27 additional samples show that the method based on the combination of microwave spectrum analysis and DW-kNN has a potential application prospect in the rapid measurement of coal MC.

Wet wastes to bioenergy and biochar: A critical review with future perspectives

The ever-increasing rise in the global population coupled with rapid urbanization demands considerable consumption of fossil fuel, food, and water. This in turn leads to energy depletion, greenhouse gas emissions and wet wastes generation (including food waste, animal manure, and sewage sludge). Conversion of the wet wastes to bioenergy and biochar is a promising approach to mitigate wastes, emissions and energy depletion, and simultaneously promotes sustainability and circular economy. In this study, various conversion technologies for transformation of wet wastes to bioenergy and biochar, including anaerobic digestion, gasification, incineration, hydrothermal carbonization, hydrothermal liquefaction, slow and fast pyrolysis, are comprehensively reviewed. The technological challenges impeding the widespread adoption of these wet waste conversion technologies are critically examined. Eventually, the study presents insightful recommendations for the technological advancements and wider acceptance of these processes by establishing a hierarchy of factors dictating their performance. These include: i) life-cycle assessment of these conversion technologies with the consideration of reactor design and catalyst utilization from lab to plant level; ii) process intensification by integrating one or more of the wet waste conversion technologies for improved performance and sustainability; and iii) emerging machine learning modeling is a promising strategy to aid the product characterization and optimization of system design for the specific to the bioenergy or biochar application.

Digital Eco-Design and Life Cycle Assessment—Key Elements in a Circular Economy: A Case Study of a Conventional Desk

In recent times, there has been an indisputable need to move towards a more sustainable economy, known as a circular economy, which is basically aimed at reducing the consumption of newly extracted raw materials to manufacture products, and thus, reduces waste generation by recycling products beyond their useful life to ultimately close the economic flow of the product. For the economy generated by products to close the circle, it is essential to tackle the problem at the source, that is, the process to achieve the desired product should be conducted by designing the product with environmental criteria (eco-design) and analysing its life cycle from the extraction process to the point when it ends its useful life (LCA). This article presents an ECO + LCA methodology that provides designers with an easy way of visualising the effect of their design decisions on the final environmental impact of the product. This methodology was tested on a case study of a conventional desk, with four alternative scenarios presented and an assessment of their final impact with a cradle-to-grave perspective. The final design obtained reduces the environmental impact by more than 30% and reduces costs by more than 11%.