Water resistance and hydration mechanism of phosphogypsum cemented paste backfill under composite curing agent modification.

Viral-community-induced antibiotic resistance gene regulation throughout the process of sewage sludge composting and its subsequent application to a phosphate mining wasteland: A three-year, large-scale field study.

Abstract Background Phosphate mining is a vital industry in Egypt, yet it carries significant environmental and health challenges. Balancing the demand for phosphate with sustainable practices and worker safety is crucial for the future of this industry. Respiratory problems, particularly silicosis, remain the most common occupational diseases among mine workers. Health hazards that arise due to exposures to the dust vary due to its variable composition in different mines. Limited data exist on respiratory morbidity among phosphate miners in Upper Egypt. Therefore, the present study aimed to assess the prevalence and determinants of respiratory problems among phosphate mines workers. Methods A cross-sectional study was carried out in Abu Tartour Upper Egypt mines among 155 workers with a minimum of five years of exposure. The study instruments were a semi-structured questionnaire, chest examination, chest X-ray classified according to the International Labor Organization (ILO) System for Classification of Radiographs for Pneumoconiosis and pulmonary function tests (PFT). Results The mean age of the study workers was 45.25 ± 6.54, all the workers were males, with 41.9% being smokers. Pulmonary function abnormalities were detected among 51.6% of workers, predominantly restrictive defects (41.3%). Abnormal Chest radiographs were observed in 32.8%; with silicosis detected in 55% of these cases. Silicosis was significantly associated with older age ( p = 0.019) and longer work duration ( p = 0.003). Smoking was significantly associated with abnormal pulmonary function ( p = 0.042). Conclusions Exposure to dust released during phosphate mining affects the pulmonary function of the workers and increases the hazard to develop silicosis. Recommendations Regular medical surveillance and strict preventive and control measures must be provided to workers in the phosphate mines to reduce the occupational disease burden among the mine workers. Trial registration ClinicalTrials.gov. NCT05094076 Registered September 2021.

Reliable wireless communication is a critical enabler of digital transformation in the mining industry, particularly in phosphate and mineral extraction environments, where safety, monitoring, and automation depend on robust connectivity. However, underground and semi-enclosed mining settings introduce severe electromagnetic (EM) challenges, including signal attenuation, multipath fading, and interference from dense equipment and layered geological structures. Traditional substrate engineering methods—such as buried diffused layers (BDL), metallized grids, guard rings, and electromagnetic bandgap (EBG) structures—offer partial isolation but often fail to ensure stable performance in such harsh conditions. This paper proposes the application of a game-theoretic electromagnetic isolation framework to wireless communication systems in mining operations. By modeling isolation techniques as strategic players in a non-cooperative game, the framework derives equilibrium solutions that balance isolation, insertion loss, fabrication complexity, and deployment cost. Simulation studies across the 2–12 GHz band demonstrate that the proposed method achieves 25–30 dB improvements in coupling reduction compared to conventional approaches while maintaining practical scalability. These results highlight the potential of the framework to enable safe, interference-resilient, and efficient wireless connectivity for real-time monitoring, autonomous equipment control, and worker safety systems in phosphate and mineral mining environments.

Selective adsorption of phosphate by 2D thin-bladed ZIF-L in phosphate mining wastewater: An investigation of single phosphorus and phosphorus-chromium composite systems

Purpose. The accurate estimation of mineral reserves is a critical step in the planning and development of mining operations, particularly for phosphate deposits. This study aims to enhance reserve estimation for the Bled El-Hadba phosphate deposit (eastern Algeria) by combining geostatistical and probabilistic approaches. Methodology. The proposed method integrates ordinary kriging (OK) with Monte Carlo simulation (MCS) to better evaluate the reserves of the main mineralized layer. Ordinary kriging was applied on a 5  5 m grid to generate estimation maps of P2O5 grades and layer thicknesses, serving as a spatial model of the deposit. The kriging outputs (mean and variance) were then used as inputs for a Monte Carlo simulation involving 20 million iterations, preserving the statistical characteristics of the original data. Findings. The combined use of OK and MCS reduced the fluctuations typically observed in kriging-based estimates and led to more stable and robust reserve values. The application of P90 and P50 probability categories contributed to more conservative and reliable classifications of mineral reserves, improving the assessment of proven and probable categories essential for economic decision-making. Originality. This study introduces a novel integration of kriging with large-scale Monte Carlo simulation to manage uncertainty in phosphate reserve estimation. The approach enables a more precise characterization of spatial variability and supports probabilistic interpretations of resource quantities. Practical value. The methodology offers a valuable tool for mine planners and decision-makers by improving confidence in reserve estimates and supporting sound economic evaluations. Its application to the Bled El-Hadba deposit demonstrates its effectiveness and potential for broader use in phosphate mining projects.

ABSTRACT In 1993, the government of the Pacific Island of Nauru was casting around for a new investment opportunity. Having made millions from global exports of guano – the phosphate-rich bird excrement used as fertiliser that had fortuitously gathered around its cliffs for generations – it was time to diversify national income for the inevitable day when demand outstripped supply. The cabinet lighted on the unlikely idea of investing in a West End musical about the Renaissance polymath Leonardo da Vinci, a decision that heralded disastrous consequences. This article situates the ecological impact of open-strip phosphate mining in conversation with the covert toxicity of musical theatre investment in an attempt to make sense of the uncomfortable relationship between culture and capital.

Synergistic mechanisms of plant-endophyte detoxification of Cr(VI) in phosphate mining wastelands based on 16S rDNA analysis and metabolomics

Development of phosphate mine waste-based geopolymer by mechanosynthesis

Selective recycling of critical metals from the dolomitic limestone waste through multi-step alkaline precipitation integrated with CO2 carbonation.

Two Gram-staining-positive, non-motile and non-spore-forming bacterial strains, designated as 9H2T and YDN13, were isolated from a phosphate mine in Yunnan Province, China. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strains 9H2T and YDN13 belong to the genus Microbacterium. Results show that strains 9H2T and YDN13 occupied a distinct position within the genus Microbacterium and showed the highest 16S rRNA gene sequence similarity of 97.6% with the type strains of Microbacterium thalassium CCTCC AB 2020140T, followed by 97.5% with Microbacterium hydrocarboxydans DSM 16089T and 97.3% with Microbacterium stercoris CCTCC AA 2018028T. In the phylogenetic trees based on 16S rRNA gene sequences, strains 9H2T and YDN13 were closely related to M. stercoris CCTCC AA 2018028T and Microbacterium sediminicola YM 10-847T. Strains 9H2T and YDN13 showed the highest values of an orthologous average nucleotide identity (84%) and a digital DNA-DNA hybridization (49%) with M. stercoris CCTCC AA 2018028T, followed by an orthologous average nucleotide identity of 76.0% and a digital DNA-DNA hybridization value of 17.9% with M. thalassium CCTCC AB 2020140T. The respiratory menaquinones were MK-11, MK-12, MK-10 and MK-13. The major fatty acid profile contained anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, three unidentified phospholipids and one unidentified glycolipid. The whole-cell sugars included galactose and glucose. The peptidoglycan hydrolysate contained glutamate, glycine, ornithine and alanine. The DNA G+C contents were 71.1 mol%. Phenotypic, phylogenetic, chemotaxonomic and genomic analyses revealed that strains 9H2T and YDN13 represent a novel species of Microbacterium, for which the name Microbacterium phosphatis sp. nov. was proposed. The type strain is 9H2T (MCCC 1K08680T=KCTC 59053T=CGMCC 1.60061T).

Abstract This study investigated the mechanical, microstructural, and thermal properties of Na‐based geopolymer foams (GPFs) reinforced with varying amounts of two types of reinforcements: raw phosphate mine waste rock (PMWR) as a particulate filler, and natural (hemp) or synthetic (basalt) fibers. The phase composition and microstructural changes of PMWR‐reinforced geopolymer have been examined using XRD, TGA/DTG/DSC and SEM/EDS techniques, to assess any possible interaction of these wastes with the alkaline system. Further investigation into the effects of PMWR, alone and in combination with fibers, on the pore structure and morphology of GPFs was conducted and correlated with mechanical strength and thermal properties. The reinforcement mechanisms provided by the PMWR particulates and each fiber type are discussed, along with the synergistic effects of their combined incorporation. Improved flexural properties were identified in composites with higher particulate content (15 wt%) and fiber content (5 wt%), with 3‐point flexural strengths ranging from 5 to 13.5 MPa. The effect of fillers on pore structure was most evident at higher loading rates, leading to significant changes in pore size, shape, and connectivity of the GPF matrix, thereby impacting its thermal insulation capacity. The dual reinforcement of geopolymer foams with PMWR particulates and fibers offers a promising approach to enhance the material performance while using low‐cost and readily available resources. This approach also presents a sustainable and ecofriendly strategy for repurposing raw PMWRs, supporting circular economy practices.

Abstract The extraction and processing of naturally occurring phosphate deposits have significantly intensified the mobilization of potentially toxic elements (PTEs), resulting in their pervasive release into the environment. Accordingly, this study investigated the environmental impact of phosphate mining at Sebaiya East area (Egypt), analyzing 24 surface sediment samples for PTEs via ICP-OES, supported by statistical analysis (descriptive and multivariate), pollution indices (individual, composite, and ecological), and health risk assessments (carcinogenic and non-carcinogenic) to understand the release, distribution, accumulation, and geochemical behavior of contaminants. The median values of PTEs were lower than their maximum concentrations, highlighting localized hotspots. Cd’s average level consistently exceeded all geochemical reference values. The individual contamination grades, based on average Igeo and CF values, ranked as Cd > As > Cr > Ni > Zn > Cu > Pb. Samples showed overall contamination (mean PLI: 1.79, mean Cdeg: 20.45, mean PINemerow: 4.29), with 29.2% severely polluted (PLI > 2) and 37.5% highly contaminated (Cdeg ≥ 24), localized near mining activities. The mean RI value of 383.9 indicated a considerable ecological risk (300 < RI < 600) throughout the study area. Weak Pearson correlations observed for As and Cd with other PTEs indicated distinct geochemical behavior and anthropogenic origins. PCA revealed the mixed origin of Pb, Cu, Zn, As, and Ni in PC1 (weathering of local bedrock and diffuse deposition from mining activities) and the anthropogenic origin of Cd in PC2. Cr and As posed the highest carcinogenic (CR: 3.64E + 02) and non-carcinogenic risks (HQ: 3.04E + 05), respectively, exceeding safety thresholds.

Developing green mining technology for medium-to low-grade mines requires achieving minimal or no damage to the mining area’s ecological environment. A medium-to low-grade phosphate mine in Hubei Province was taken as the research object in this study. The tailings were selected as the main filling aggregate. Indoor tests and theoretical analysis were conducted to analyze the influence of curing age, the water–cement ratio, the cement–sand ratio, and slurry concentration on the strength of the cemented backfill. Furthermore, a multi-factor non-linear mathematical model of the strength of the cementitious filler was established. The study results indicated that the strength of backfill increased linearly with the increase in the curing age, decreased negatively with the increase in the water–cement ratio, and increased exponentially with the increase in the cement–sand ratio and the slurry concentration. The multivariate non-linear prediction model of the strength of the filling body at different ages was also established based on the test results. This predictive model could effectively predict the strength of the cemented backfill, and the error value was not larger than 4%. Our research results can lay a theoretical foundation for developing medium-to low-grade phosphate mine filling with tailings as the main filling aggregate.

Challenging the universality of the Anthropocene Epoch, this article argues for a new conceptualization of the planetary situation focused on the landscape complexities of the Holocene/Anthropocene boundary event . I ground this perspective with a historical and ethnographic tour of Lake Somerset, a water-filled phosphate pit in Central Florida that has become habitat for a colony of endangered wood storks. Displaced from their native Everglades, these storks utilize the lake's spoil-pile islands for their rookery. I argue that Lake Somerset, and the Holocene/Anthropocene transition generally, become legible by attending to processes of creative niche destruction: capital-generating disturbances that irreversibly alter the biophysical structure of space. At Lake Somerset, phosphate mining has locally eradicated the Holocene ecologies that came before and replaced them with pits and piles of mutilated soil that recolonize with invasive plants. The diasporic wood storks exemplify what I call a Holocene fragment–– a long-established ecological form that survives in the ruins of the Anthropocene. Utilizing tools of natural history observation, ethnography, and environmental history, I argue that multispecies researchers are uniquely positioned to track the Holocene/Anthropocene transition across the earth's surface––a critical practice for understanding shifting patterns of life and livability in this time of radical change.

The rheological properties of soft rocks significantly affect the long-term stability of deep roadways. As the fundamental units of rocks, the mineral components play a crucial role in the time-dependent failure process of soft rocks. In order to study the instability mechanism of the red shale roadways in Kaiyang phosphate mining area, this study conducted red shale mineral nanoindentation rheological tests after drying and soaking in water for 24 h, revealing the impact of hydration on the rheological properties of main minerals in red shale. The X-ray diffraction tests showed that the red shale is mainly composed of quartz, plagioclase, chlorite, and illite. The nanoindentation experiment showed that the hardness of quartz increases slightly after soaking in water for 24 h, and after soaking in water for 24 h, the hardness of plagioclase sharply decreases, indicating that water has a significant impact on the hardness of plagioclase. For chlorite and illite, the hardness of both clay minerals decreases slightly after soaking in water, indicating that hydration will further aggravate the deterioration of the internal pores of clay minerals, which will reduce their hardness. In addition, the nanoindentation creep process of minerals is divided into two stages, namely the deceleration creep stage and the constant velocity creep stage. The creep rate of minerals first decreases with increasing time and then remains basically stable. The initial creep rate of each mineral is greater than 20 nm/s.

Phosphogypsum (PG), a byproduct of phosphate mining, contains sulfate that can be leached and converted to elemental sulfur, thus offering a sustainable opportunity to recover sulfur (S) as a step toward a circular economy. Calcium, at ~15 mM in PG leachate, creates inorganic precipitation that interferes with biological sulfate reduction, the first step of S recovery. Here, we evaluated the effectiveness of using cation-exchange to lower the calcium concentration in water-leached PG (PG water) delivered to a H2-based membrane biofilm reactor (H2-MBfR) employed to reduce sulfate to sulfide. A high sulfate flux (1 gS/m2-day) and 65% sulfate reduction were achieved despite a high pH (10) resulting from base production during sulfate reduction. However, soluble sulfide was only 20% of the reduced S, possibly due to precipitation of sulfide, iron, and phosphate, and alkalinity analysis revealed possible formation of polysulfides. Shallow metagenomics of the biofilm documented that Desulfomicrobium was the dominant sulfate-reducing bacterium, while Thauera, a mixotroph capable of sulfate reduction and sulfide oxidation, also was an important genus. The metagenomics also revealed the presence of methanogens and acetogens that competed for H2 and CO2. Although calcium removal from PG water improved sulfate reduction and reduced inorganic precipitation in the H2-MBfR, soluble sulfide generation must be improved by supplying sufficient CO2 to moderate pH increase due to sulfate reduction and by controlling the H2-delivery capacity to limit methanogens and acetogens.

In InSAR processing, optimizing baselines by selecting appropriate interferometric pairs is crucial for ensuring interferogram quality and improving InSAR monitoring accuracy. However, in multi-temporal InSAR processing, the quality of interferometric pairs is constrained by spatiotemporal baseline parameters and surface scattering characteristics. Traditional selection methods, such as those based on average coherence thresholding, consider only a single factor and do not account for the interactions among multiple factors. This study introduces a principal component analysis (PCA) method to comprehensively analyze four factors: temporal baseline, spatial baseline, NDVI difference, and coherence, scientifically setting weights to achieve precise selection of interferometric pairs. Additionally, the GACOS (Generic Atmospheric Correction Online Service) atmospheric correction product is applied to further enhance data quality. Taking the Haikou Phosphate Mine area in Kunming, Yunnan, as the study area, surface deformation information was extracted using the SBAS-InSAR technique, and the spatiotemporal characteristics of subsidence were analyzed. The research results show the following: (1) compared with other methods, the PCA-based interferometric pair optimization method significantly improves the selection performance. The minimum value decreases to 0.248 rad, while the mean and standard deviation are reduced to 1.589 rad and 0.797 rad, respectively, effectively suppressing error fluctuations and enhancing the stability of the inversion; (2) through comparative analysis of the effective pixel ratio and standard deviation of deformation rates, as well as a comprehensive evaluation of the deformation rate probability density function (PDF) distribution, the PCA optimization method maintains a high effective pixel ratio while enhancing sensitivity to surface deformation changes, indicating its advantage in deformation monitoring in complex terrain areas; (3) the combined analysis of spatial autocorrelation (Moran’s I coefficient) and spatial correlation coefficients (Pearson and Spearman) verified the advantages of the PCA optimization method in maintaining spatial structure and result consistency, supporting its ability to achieve higher accuracy and stability in complex surface deformation monitoring. In summary, the PCA-based baseline optimization method significantly improves the accuracy of SBAS-InSAR in surface subsidence monitoring, fully demonstrating its reliability and stability in complex terrain areas, and providing a solid technical support for dynamic monitoring of surface subsidence in mining areas.

With the increasing depth of mining operations, the geological conditions of deep roadways have become increasingly complex. Among these complexities, the issues of fractured zones and groundwater are particularly critical, significantly contributing to the reduced stability of the surrounding rock. This study focuses on the challenging support problem associated with water-bearing fractured surrounding rock in the Y1# belt conveyor roadway of the Wengfu phosphate mine. Through theoretical calculation, laboratory testing, numerical simulation, and field monitoring, the range and displacement of the broken zone in the broken surrounding rock roadway are studied and analyzed. The results show that the physical and mechanical properties of the broken surrounding rock mass are weakened by water, and the range and deformation of the broken zone of the surrounding rock of the water-bearing roadway increase. In response to the failure characteristics of the water-bearing fractured surrounding rock in the Y1# belt conveyor roadway, an optimized support scheme was developed. A combined support system of steel arch frames and localized grouting was proposed to enhance the control of the surrounding rock. Field monitoring data confirmed that the optimized support scheme achieved satisfactory control effectiveness, effectively addressing the stability challenges posed by water-bearing fractured rock masses.

Radon is a radioactive gas and a decay product of uranium. This gas poses a potential health risk to humans. This study aimed to assess preliminary indoor radon concentration at homes in Minjingu village and use the results of measurements to estimate the annual effective dose received by the dwellers and the associated excess lifetime cancer risk. The measurements were conducted in selected 22 houses using Professional Radon gas Monitor, AlphaGUARD from the Tanzania Atomic Energy Commission Laboratory. Results indicated that the radon concentration ranged from 33±4 Bq/m3 to 1080 ±57 Bq/m3 with the mean of 161±12 Bq/m3. The inhalation dose ranged from 0.8mSv.y-1 to 27.2 mSv.y-1 with the average of 4.1 mSv.y-1. The excess lifetime cancer risk (ELCR) ranged from 0.3 to 10.5%, with the average of 1.6%. Since some of the observed readings in this study are higher than the recommended levels of 300 Bq/m3, it is recommended to improve the ventilation system of the houses. Also, the long-term measurement of radon in this area is recommended in order to take into consideration the long-term variation of meteorological parameters such as temperature, relative humidity and pressure which are known to affect indoor radon levels. Regulatory measures for the areas with elevated levels of radon should be implemented, and a public health campaign to provide awareness about the effects of radon and its mitigation in homes should be given to the dwellers.