The Phapon gold deposit in Laos is situated within the northern segment of the Luang Prabang-Loei metallogenic belt. This deposit is distinguished by the spatial coexistence of hydrothermal gold ore bodies, which include coarse-grained calcite veins and orpiment-realgar quartz-calcite veins, alongside palaeokarst cave-hosted sedimentary-accumulated high-grade gold ore pod. Recently, a newly identified high-grade gold ore body, averaging 40.18×10-6 Au, has been discovered within that ore pod. This body is hosted by palaeokarst cave conglomerates and formed through sedimentary re-enrichment processes. Investigations into the occurrence of gold reveal that the interbedded sandstone and conglomerate are enriched with visible native gold. Larger gold particles, predominantly ranging from 2~10 μm, are located within the pores of detrital grains and exhibit slightly rounded but predominantly uneven edges with impact pits. In contrast, smaller particles, less than 1 μm in size, are embedded within clay and ferruginous mineral matrices and display relatively regular shapes. Comprehensive research on the source-to-sink mechanisms of gold suggests that the calcite-rich hydrothermal gold veins may have served as the source for the palaeokarst cave conglomerate-hosted ore bodies. The karst cave associated with the F1 palaeokarst unconformity created an advantageous environment for mineralization. The relatively coarse native gold originating from hydrothermal veins underwent reworking through karst processes, followed by mechanical transportation and sorting via surface runoff, ultimately leading to its deposition within the sand and gravel pores, resulting in the formation of larger gold particles （2~10 μm）. Additionally, some primary gold may have experienced remobilization and migration, subsequently undergoing adsorption and reprecipitation on the surfaces of clay and ferruginous minerals, thereby forming smaller gold particles （<1 μm）. The recent identification of a palaeokarst cave conglomerate-hosted high-grade gold ore body marks a significant advancement from the previous exploration paradigm, which concentrated exclusively on hydrothermal gold veins. Paleo-caves and other favorable karst landforms situated along the F1 paleokarst unconformity present substantial potential for accommodating large-scale karst sedimentary-accumulated type rich ore deposits.
The Lannigou gold deposit represents a quintessential“fault-controlled” large carlin-type gold deposit located within the “Golden Triangle”region encompassing Yunnan, Guizhou, and Guangxi. The gold ore body is stringently regulated by the fault zone.Previous research has extensively explored the relationship between the structural features and mineralization processes of the Lannigou gold deposit, yielding significant findings. However, recent years have witnessed a stagnation in exploration activities, adversely impacting the subsequent production and development of the mines. Consequently, there is a pressing need to reorganize the latest exploration data, further elucidate the structural control mechanisms governing the Lannigou gold deposit, and inform the strategic planning of future prospecting endeavors. This study employs the theoretical framework and methodologies of structural analysis of ore fields, leveraging the most recent exploration data to reconstruct the structural evolution of the Lannigou gold deposit. The investigation re-identifies the primary ore-controlling structures, synthesizes the principles of tectonic ore control, and delineates prospective target areas for exploration based on these tectonic ore-controlling principles. The findings indicate that the tectonic features within the Lannigou gold deposit area can be categorized into four distinct stages. During the D1 stage, extensional forces resulted in the formation of horizontal folds or folds with axial planes inclined towards the southwest, characterized by a gentle inclination of the axial plane. In the D2 stage, the region experienced NE-SW compressional forces, leading to the development of vertical or acute-angle folds with NE-SW oriented axial planes, alongside the F3 fault system. This stage reworked the folds formed in the D1 stage and marks the period of significant thrust nappe structure formation in the area. The D3 stage was characterized by NW-SE compressional forces, which reactivated existing faults and resulted in the formation of a series of minor thrust faults. Subsequently, during the D4 stage, N-NE oriented normal faults emerged, leading to minor-scale reconstruction of earlier fold and fault systems. Mineralization is predominantly associated with the reactivation of preexisting faults induced by the compressional forces of the D3 stage. The primary ore-controlling structure is the thrust nappe system, with the F7 fault serving as the principal ore-guiding structure, while the F3 fault functions as a secondary ore-bearing structure. This work not only provides a concrete basis for the further exploration of the Lannigou gold deposit, but also provides a typical example for the analysis of the carlin-type gold ore-controlling structure in the Yunnan, Guizhou and Guangxi areas.
The Walegen gold deposit is currently the sole medium-sized gold mineralization identified within the Qinghai segment of the West Qinling orogenic belt. To elucidate its metallogenic chronology, tectonic affinity, and genetic model, zircon U-Pb geochronology and whole-rock geochemistry analyses were performed on both unmineralized and mineralized quartz porphyry samples from the ore district. The zircon U-Pb concordia ages obtained were (235.5±2.0) Ma for the barren quartz porphyry and (238.8±2.3)Ma for the mineralized quartz porphyry, suggesting emplacement during the Middle Triassic period. Geochemical analyses indicate that the quartz porphyries are characterized by elevated SiO2 and Al2O3 levels, alongside reduced concentrations of TFe2O3, MgO, and TiO2. They also exhibit enrichment in large-ion lithophile elements (LILEs, such as Rb, Th, U, K) and depletion in high-field-strength elements (HFSEs, including Nb, Ta, Ti, P, Ba, Sr). These geochemical characteristics classify the quartz porphyries as peraluminous, medium- to high-K calc-alkaline I-type granites. The formation of these quartz porphyries occurred within a transitional tectonic environment, evolving from subduction to collision of the Mianlue oceanic plate in the West Qinling orogen. This magmatic activity was instrumental in supplying the necessary thermal energy and contributing to the ore-forming fluids, thereby playing a pivotal role in the geological process es responsible for the genesis of the Walegen gold deposit.
The geochemical survey, recognized as a direct and efficient method for geochemical prospecting, is characterized by a well-established workflow and proven effectiveness in mineral exploration. The Heishantou area, located within the southern belt of the Beishan region in Gansu Province, is part of the Beishan denudation Gobi zone's geochemical landscape. Within this study area, sixteen composite anomalies were identified through a stream sediment survey conducted at a 1∶50 000 scale. To further refine these anomalies, investigate their underlying causes, and achieve significant breakthroughs in prospecting, the AS-13 anomaly was selected for a more detailed lithochemical geochemical survey at a 1∶10 000 scale. This surface sampling involved the collection of rock fragments or lithic debris ranging from 2 to 20 mm in size, utilizing sampling media that included weathered bedrock fragments, fault breccias, and altered lithic debris exhibiting significant mineralization. A comprehensive analysis was conducted on eleven elements, namely Au, Ag, Cu, Pb, Zn, W, Sn, Mo, As, Bi and Sb. Employing correlation analysis and R-type cluster analysis, the characteristics of element associations were examined and synthesized. Preliminary findings suggest that the regional element associations are characterized by: 1) Au, As, Cu, and Zn, indicative of the mineralization phase; and 2) W, Mo, Pb, and Ag, which are reflective of early-stage complex hydrothermal activity. The results reveal that anomalies of elements such as Au, As, Cu, and Mo within the study area exhibit strong spatial coherence, high intensity, distinct enrichment centers, and considerable potential for mineral exploration. Based on the element association characteristics and the geological framework, the anomalies are predominantly aligned along the NW-trending ductile shear zone. Verification through trenching exploration at the composite anomaly AR-5 identified five gold-mineralized bodies. These ore bodies have lengths ranging from 75 to 185 meters, thicknesses from 0.45 to 1.10 meters, and gold grades between 1.09×10-6 and 15.6×10-6. The ore type is classified as quartz vein-type. The gold mineralized bodies are located within a ductile shear zone and are closely associated with mineralization-alteration processes such as silicification, arsenopyritization, hematitization, and jarositization. By comparing the regional characteristics, geochemical signatures, orebody features, wall-rock alteration, and ore-controlling factors of typical gold deposits within this ductile shear zone, it is inferred that the Heishantou area holds significant potential for the formation of ductile shear zone-type gold deposits, with promising prospects for exploration. Our study concludes that the 1∶10 000 scale lithogeochemical survey has proven highly effective in verifying anomalies within the denuded Gobi regions of the Beishan area. This method facilitates rapid anomaly targeting and serves as a valuable complement to soil geochemical surveys, demonstrating strong prospecting efficiency in the denuded Gobi regions of the Beishan area in Gansu Province. This approach provides valuable references for geological prospecting in similar landscape regions.
To enhance the efficiency of gold exploration in areas characterized by complex landscapes, this study conducted a systematic evaluation of the effectiveness of multi-scale geochemical methods applied in the Tanjianshan region, located on the northern margin of the Qaidam Basin in Qinghai Province. The research elucidated the role and technical outcomes of geochemical techniques at various stages of exploration, with the objective of providing scientific guidance for gold prospecting in analogous geological and geomorphological settings. Initially, a 1∶200 000 scale regional geochemical survey was conducted, which enabled the rapid delineation of two gold anomalies in stream sediments through sparse sampling, thereby identifying key prospecting targets. Subsequently, a more detailed 1∶50 000 scale geochemical survey was performed to further resolve the anomaly structures, leading to the identification of eight sub-anomalies predominantly associated with gold. To validate these anomalies and delineate their extension along both strike and dip directions, extensive rock geochemical profiles at scales of 1∶5 000 and 1∶10 000 were developed. These were com-plemented by trenching exposure, adit engineering, and drilling verification. The findings reveal the discovery of two large-sized, two medium-sized, and four small-sized gold deposits within the study area, with the cumulative gold resources attaining a large-scale magnitude. This research substantiates that small-scale stream sediment surveys are effective for the rapid identification of geochemical anomalies and can guide the overall prospecting direction. In contrast, large-scale stream sediment surveys, combined with geochemical profile verification, can systematically refine prospecting targets. When integrated with engineering verification, these multi-scale geochemical methodologies prove to be highly effective in the discovery and delineation of ore bodies. This underscores their efficacy and practical significance in gold exploration within the Tanjianshan area and analogous regions.
The Early Permian granites of Heishishan are situated within the Late Paleozoic intracontinental rift in the southern region of Beishan Mountains. These granites have been inadequately studied, thereby limiting the understanding of the tectonic-magmatic evolutionary history of the Beishan area. This paper, presents findings from comprehensive field geological investigations, petrogeochemical analyses, isotopic chronology, and petrographic studies conducted on the Heishishan granite body. The results indicate that： the SiO2 content of the rocks consistently exceeds 70%. The A/CNK ratio of the difeldspar granite is greater than 1.1, classifying it as a strongly peraluminous granite. The geochemical parameter of alkalinity ranges from 0.49 to 0.67, identifying the granite as calc-alkaline with characteristics typical of S-type granites. Both the consolidation index and feldspar index suggest a high degree of fractional crystallization and separation in the granite. Additionally, the trace elements are enriched with large ion lithophile elements such as Rb, K, Ba, and La, while elements such as Ba, Sr, P, and Ti are notably depleted. The rare earth element（REE） distribution pattern exhibits a rightward inclination, characterized by a pronounced negative europium（Eu） anomaly. Zircon U-Pb geochronology results reveal that the diagenetic age of the rock mass is （284.8±3.9） Ma, corresponding to the Early Permian period. Tectonic environment analysis suggests formation within a stretched and thinned intra-plate rift, setting, indicative of a post-collisional extensional regime. The source rock is interpreted as a product of lower crustal melting, induced by the thermal influence of mantle-derived magmatic under plating. Considering the regional geological, context, it is postulated that the Beishan Mountains Southern Belt and its surrounding areas transitioned into a post-collisional rift extension phase during the late Early Permian. Consequently, the closure of the Central Asian Orogenic Belt likely occurred prior to the late Early Permian.
The Dayingezhuang gold deposit, located in the Jiaodong Peninsula, is primarily characterized by gold mineralization. However, the presence of significantly elevated silver（Ag） grades in the shallow sections suggests the possibility of overprinting by subsequent silver mineralization. Utilizing systematic core logging, microscopic ore petrography, electron probe microanalysis, and comprehensive geochemical data analysis, this study identifies a distinct silver mineralization event within the Dayingezhuang deposit. The findings indicate that silver enrichment is strictly confined to depths above -1 000 meters and is spatially segregated from the deeper gold orebodies. Silver predominantly occurs as intergranular silver（97.59%） within medium- to low-temperature sulfides, such as galena and sphalerite, forming an Ag-Pb-Zn elemental assemblage. The ore-forming fluids are characterized by a medium- to low-temperature, moderate- to low-salinity H2O-NaCl system, which is distinct from the CO2-rich, medium-temperature system associated with the primary stage of gold mineralization. It is concluded that the silver mineralization event transpired subsequent to the principal gold mineralization episode in the Early Cretaceous, was governed by NW-trending faults, and represents a product of medium-low temperature hydrothermal activity during a regional tectonic transition to strike-slip extension. This study not only advances the understanding of multistage mineralization processes in Jiaodong-type gold deposits but also provides significant constraints for the evaluation of associated silver resources and deep prospecting in the region.
A paleo-weathering crust predominantly composed of claystone has formed atop the Ordovician Majiagou Formation limestone in the Weibei region of Shaanxi. Through comprehensive geological and geochemical profiling, limited engineering exposure, and rigorous sample testing and analysis, this study has identified anomalous enrichment of strategic critical mineral resources, including rare earth elements（REE）, rutile, rubidium（Rb）, and lithium （Li）, within this weathering crust. Preliminary delineation has identified three surface areas enriched with rare earth elements, titanium, and lithium. Two weathering crust -type rare earth（mineralization） bodies have been preliminarily delineated, exhibiting total rare earth oxide（TREO） grades ranging from 0.0321% to 0.2723%. Additionally, two weathering crust sedimentary rutile -type titanium ore bodies have been identified, with titanium dioxide（TiO2） grades ranging from 1.16% to 2.81%, associated TREO content of 0.1009%, associated lithium oxide（Li2O） content of 0.332%, and a maximum rubidium content of 345×10-6. The ore-bearing lithology primarily comprises various claystones, with the predominant minerals being clay minerals such as kaolinite, illite, and montmorillonite, followed by hydromuscovite and limonite, and minor constituents including rutile and sphene. Typical geochemical profiles indicate that rare earth element（REE） mineralization is characterized by enrichment, with higher concentrations observed in the middle to lower sections, though（not exposed at the base）, and relatively elevated concentrations in the upper section. Titanium（Ti） mineralization is more enriched in the upper section, with relatively high enrichment in the middle to lower sections, also（not exposed at） the base. In contrast, lithium（Li） mineralization is localized. This is particularly evident in the pronounced fractionation among light rare earth elements（LREE）, while fractionation among heavy rare earth elements（HREE） is less distinct. Additionally, trace elements such as Th, Zr, Hf, and Rb are relatively enriched, whereas Nb, Ba, and Sr are relatively depleted. The combined proportion of praseodymium oxide （Pr6O11） and neodymium oxide（Nd2O3） in the rare earth ore varies from 14.68% to 23.63%, with an average value of 19.68%. In contrast, the proportion of terbium oxide（Tb4O7） and dysprosium oxide（Dy2O3） ranges from 1.45% to 5.54%, with an average of 2.85%. These compositional characteristics suggest that the deposit is classified as a low-praseodymium-neodymium, low-dysprosium-terbium, light rare earth element（LREE） deposit. This classification underscores the potential of the Weibei area in Shaanxi Province for the exploration of strategic key mineral resources, including weathering crust-type rare earth ore, sedimentary rutile-type titanium ore, and associated lithium and rubidium deposits. The initial discovery of weathering crust type rare earth ore and sedimentary rutile-type titanium ore holds significant implications for the exploration of strategic mineral resources in the Weibei area, providing valuable demonstration and guidance for future endeavors.
Green development encompasses the utilization of environmentally sustainable technologies and models characterized by minimal resource input, consumption, and pollution, while maximizing output and benefits. This approach aims to foster a development paradigm that is harmonious with both human and environmental well-being. Several foreign mining nations have pioneered the establishment of green exploration regulations, thereby amassing substantial practical experience. In response to the dual imperatives of ecological civilization and the assurance of national energy and resource security, green exploration has emerged as an essential strategy for the sustainable advancement of China’s geological exploration sector. An examination of the evolution of pertinent green exploration regulations and standards, both domestically and internationally, reveals that developed mining countries have instituted a comprehensive legal and management framework for green exploration. This framework is primarily characterized by stringent environmental permitting, rigorous oversight, differentiated governance, and the dynamic revision of regulations. Although the development of green exploration in China commenced relatively recently, it has achieved notable progress. National legislation and regulatory frameworks have laid the foundational design for environmentally sustainable exploration. Ministerial regulations have facilitated policy execution, while local regulations have bolstered enforcement efforts. Geological exploration units have implemented internal rules and regulations, and national standards for green exploration have provided essential guidance. Industry standards have further advanced the geological exploration sector towards environmental sustainability. Additionally, group and local standards have outlined specific methodologies for implementing green exploration practices. Consequently, China has established an initial regulatory framework encompassing state, ministerial, local, and enterprise levels, alongside a comprehensive standard system comprising national, sector, association, and local standards. Regulations furnish the foundational and obligatory framework for the development and enforcement of standards, whereas standards offer the technical support and operational pathways necessary for regulatory implementation. Together, standards and regulations collaboratively underpin efforts in green exploration. Currently, the regulatory framework and standards governing green exploration in China exhibit several deficiencies, including incomplete coverage, inadequate regulatory mechanisms, and a lack of effective incentive policies. To address these issues, it is recommended to enhance development strategies by refining the legal framework for green exploration, establishing a comprehensive standard system that encompasses the entire process, and innovating dynamic regulatory mechanisms to ensure the effective implementation of relevant regulations and standards. Additionally, the introduction of financial incentive policies is crucial to facilitate the iterative advancement of green exploration technologies, equipment, and associated regulations and standards. This study aims to provide a reference for further improvements in China’s green exploration laws and regulations, management oversight, and standard formulation and revision, thereby contributing to the advancement of national ecological civilization and the security of energy resources.
Platinum group metals (PGMs) have gained prominence as globally strategic critical minerals due to their dual characteristics of industrial utility and investment value. In China, the scarcity of PGMs resources and the country’s significant reliance on external sources pose both theoretical and practical challenges for academia and industry. Traditional analyses of industry chain s often focus on the existing structure of a single chain. In contrast, this research adopts a complex network approach, examining the layers of spatial resource distribution, financial investment in mining, and international mineral trade. By constructing a global industry perspective of PGMs and analyzing global trade data for four representative PGMs products from 1990 to 2023, this study provides a comprehensive analysis of the trade patterns and evolution of these products from an industrial standpoint. The findings reveal that the trade network for PGMs was relatively straightforward in its early stages. Over time, the capacity of the global PGMs trade system has expanded, leading to increasingly interconnected trade links among nations. Resource-rich countries such as South Africa and Russia continue to exert substantial control over the primary supply of resources necessary for mining production. In contrast, developed nations like the United Kingdom and the United States maintain dominance in the PGMs trade through their extensive global holdings of mineral rights and sophisticated financial trading mechanisms. Additionally, the global PGMs trade network demonstrates characteristics of a homologous network, and the trend towards anti-globalization has exacerbated conflicts between regional cooperation organizations and the global mineral resources trade. This research provides a theoretical foundation and practical insights for China to formulate trade policies related to PGMs, establish a stable trade cooperation network, select suitable trade partners, and mitigate risks associated with the industrial supply chain.
Fluorite, the sole naturally occurring mineral form of calcium fluoride (CaF₂), has been classified as a “strategic mineral” or “critical mineral” byseveral nations due to its essential role as a raw material in emerging industries such as hydrogen fuel cells, lithium batteries, and semiconductor cleaning agents. The stability of fluorite supply and its price volatility are intrinsically linked to the security of the new energy and semiconductor sectors. However, existing researchpredominantly emphasizes the assessment of resource status and analysis of supply-demand dynamics, while largely neglecting the quantitative characterization of trade dependency relationships and their dynamic effects on pricing mechanisms. To address thisresearch gap, the present study employs fluorite trade data spanning from 2010 to 2024, sourced from the United Nations Commodity Trade Statistics Database(UN Comtrade), to develop a global fluorite trade dependency network. This network is constructed using the preference matching index(PMI) as edge weights. This study comprehensively evaluates import demand levels, export supply capacity, and bilateral trade preferences through a detailed analysis of network structure evolution using trade dependency network indicators. A panel vector autoregression (PVAR) model is subsequently developed to assess these dynamics. By integrating impulse response functions, the research investigates the dynamic response and duration of fluctuations in fluorite trade prices when trade network topology indicators experience shocks. The findings reveal that: (1)The global trade dependency network is characterized by diversification and fragmentation, with China and the Netherlands emerging as central hubs. Although Germany remains influential, its intermediary control capacity is gradually diminishing. (2)Isolated subgroups have formed at the network’s periphery, comprising countries such as Rwanda, Argentina, and Paraguay, highlighting the ongoing interplay between globalization and geopolitical tensions in the evolution of the fluorite trade network. (3)The pricing of fluorite in trade markets is influenced not only by traditional supply and demand dynamics but also significantly shaped by the structure of trade networks. The effects of weighted out-degree and weighted in-degree on pricing reveal asymmetric impulse responses, with local clustering exerting a more substantial short-term impact on prices than the control power of hubs. By integrating resource dependency theory with complex network analysis, this study transcends the limitations of conventional analyses based solely on trade volume or value, thereby making significant theoretical contributions. The findings offer novel insights into the dynamic evolution of global fluorite resource allocation and provide practical implications for optimizing industrial structures and enhancing supply chain stability in strategic emerging industries.
To investigate the instability risk of waste dump slopes under the influence of rainfall seepage, a risk analysis coupling model was developed, integrating the bow-tie model with a fuzzy Bayesian network. This model encapsulates the instability risk factors associated with waste dumps, encompassing internal, environmental, and managerial factors. The bow-tie model for slope instability was constructed utilizing both fault tree and event tree models. Through the event tree analysis, four potential damage outcomes were identified: the emergence of potential hazards within the waste dump, progression of damage, increased water content and self-weight, and eventual slope instability. Consequently, four safety barriers are proposed to mitigate and manage damage and instability in waste dumps: risk identification and damage assessment, investigation of latent hazards such as structural defects and weak water-bearing surfaces within the waste dump, implementation of drainage systems, and remediation of waste dump damage. A Bayesian network model, grounded in the bow-tie model, was developed to characterize the polymorphism and uncertainty associated with factors contributing to slope instability. To address the probabilities of model nodes, a triangular fuzzy number and a modified weighted similarity aggregation method were employed. This approach mitigates the subjectivity inherent in expert assessments and overcomes the challenges of accurately quantifying various probabilities. Risk prediction was executed through forward inference using the Bayesian network model, while risk diagnosis was performed via reverse reasoning. Key factors influencing instability were identified through importance analysis. The study utilized a metal mine waste dump slope in Inner Mongolia as a case study, wherein enterprise experts were invited to provide scores. GeNIe software was employed to compute the prior probability, posterior probability, and the significance of each factor contributing to the risk of slope damage in the waste dump. A quantitative study was conducted to examine the relationship between damage and influencing factors in the context of waste dump slope backgrounds. The study identified key factors contributing to waste dump slope damage under rainfall seepage conditions, including rainfall-induced seepage erosion, the self-weight of the waste dump slope, internal defects, high water content, and the failure of emergency response mechanisms. Based on the analysis results, targeted instability control measures were proposed. The analysis of engineering case studies demonstrates that this model aligns with the approach of advancing safety production protocols. It effectively describes the impact and probability of various factors contributing to damage occurrence under rainfall seepage conditions. This model holds significant reference value for the risk management of geological disasters in waste dump slopes.
In order to examine the progression of damage and the propensity for rockburst in deep granite subjected to high geothermal temperatures, triaxial compression tests were performed on granite specimens at three distinct temperatures: ambient(25 ℃), 55 ℃, and 75 ℃, utilizing the MTS 815 Flex GT rock mechanics testing system. The study employed acoustic emission(AE) monitoring and scanning electron microscopy(SEM) to conduct a comprehensive analysis of the mechanical behavior, AE characteristics, and failure patterns of granite under varying thermal conditions. Additionally, the brittleness index and impact energy index were utilized to quantitatively assess the rockburst tendency. The findings demonstrate that temperature significantly influences the acoustic emission(AE) characteristics, failure modes, and rockburst propensity of granite. Under ambient temperature conditions, granite predominantly undergoes intergranular brittle failure, characterized by smooth fracture surfaces, and the AE signals are marked by abrupt high-energy bursts preceding the peak stress. The brittleness index at this temperature is 0.62, indicating a pronounced rockburst tendency. At 55 ℃, the specimens exhibit fragmented failure features, and the AE signals reveal staged energy surges. Although the brittleness index decreases to 0.30, the rockburst tendency remains pronounced. At 75 ℃, the fracture surfaces display densely distributed and disordered microcracks, with AE signals transitioning to continuous emissions, and the brittleness index further decreases to 0.25. The impact energy index decreases to 1.94, indicating a diminished tendency for rockburst occurrence. These results demonstrate that increased temperature enhances the initiation and propagation of internal microcracks, facilitating progressive energy dissipation. Consequently, this process reduces the accumulation and abrupt release of elastic energy, thereby transitioning granite from high to low brittleness and ultimately mitigating the risk of rockburst. This study offers theoretical support for predicting and mitigating rockburst hazards in deep, high-temperature geological settings.
The engineering challenges associated with instability in rock slope excavation due to unloading effects have become increasingly significant. Traditional stability assessments frequently neglect the dynamic deterioration of the mechanical properties of rock masses during the unloading process. This study aims to elucidate the impact of unloading magnitude on the shear strength parameters of rock masses and their corresponding engineering response behaviors. To achieve this, graded unloading tests were conducted on three distinct rock types. The results indicate that an increase in the magnitude of single-step unloading results in an exponential decline in rock cohesion and internal friction angle, with the coefficient of determination（R²） for the exponential fit ranging from 0.944 to 1.000. Additionally, substantial variations in the amplitude of parameter degradation were observed across different lithologies. The study confirms that the strength of rock masses is influenced by both the strength of structural planes and the intrinsic strength of the rock itself. Utilizing the Hoek-Brown strength criterion and an analysis of data from 110 hydropower projects, a significant power-law relationship was identified between the rock mass disturbance factor （D） and the cumulative unloading amount （A）. The results of the analysis suggest that 66% of the cumulative unloading amount can be considered an empirical threshold. A revised methodology was developed for calculating the rock mass disturbance factor （D）, which incorporates the effects of unloading specifically for Class Ⅲ and Ⅳ rock masses. This method reveals a power-law relationship between the magnitude of unloading and the disturbance factor （D）, indicating that lower Geological Strength Index （GSI） values are associated with increased sensitivity to disturbances induced by unloading. Through a comparative analysis of representative slope engineering cases, the evaluation methodology that incorporates excavation techniques and unloading effects offers a more accurate reflection of engineering realities. The findings of this research furnish a theoretical foundation for optimizing rock slope excavation design and conducting precise stability assessments.
Cold shock induces substantial thermal stress in hot dry rock （HDR）, effectively promoting fracturing and enhancing permeability within HDR reservoirs. To elucidate the impact of cold shock on the fracture properties and damage characteristics of HDR, cyclic loading-unloading three-point bending tests were performed on granite specimens subjected to high-temperature cooling（at 400 ℃, utilizing both water and liquid nitrogen as cooling） agents. These tests employed varying upper load limits（80%, 85% and 90% of the peak load）. The study analyzed the variation in type Ⅰ fracture toughness in relation to the cooling methods and upper load limits, and further examined the 3D topography and microstructural features of the fracture surfaces. The findings indicate that, in comparison to water cooling, liquid nitrogen cooling results in a more pronounced reduction in the Mode Ⅰ fracture toughness of granite relative to its natural state, with the maximum reduction reaching 47.95%. Additionally, a linear relationship was observed between type Ⅰ fracture toughness and the upper load limit for granite in both its natural state and under different cooling methods, wherewith fracture toughness increasing as the upper load limit rises. When the upper load limit ranges from 85% to 90%, there is a significant increase in the fracture surface roughness of granite subjected to both water cooling and liquid nitrogen cooling. Post high-temperature cooling, the internal crack propagation mode in granite transitions from transgranular to intergranular. The fracturing of granite under varying cooling methods and cyclic loading-unloading is attributed to the synergistic effect of the inhomogeneous thermal expansion of internal mineral particles and external loads, resulting in the formation of through-cracks that predominantly contribute to specimen failure. This study examines the mechanical properties and fracture characteristics of granite under the combined influence of high-temperature cold shock and cyclic loading. The findings offer theoretical support for the application of cyclic fracturing technology in enhancing HDR reservoir stimulation.
An advanced control methodology, utilizing a five-layer fuzzy neural network PID controller, is introduced to address the technical challenges associated with hysteresis nonlinearity and low control accuracy in the spiral powder metering control system within metal mine filling technology. This approach integrates the inferential capabilities of fuzzy logic with the self-learning attributes of neural networks, thereby facilitating the online adaptive tuning of PID parameters through a structurally equivalent fuzzy neural network architecture. A five-layer network configuration was developed, with mathematical formulations delineated for each layer, and these formulations were subsequently validated and analyzed using Python software. Drawing upon the expertise gained from adjusting the parameters of the spiral scale, a fuzzy inference mechanism and a comprehensive fuzzy rule library were constructed, culminating in the establishment of an automated model for the spiral weighing system. Stability simulations were conducted employing both MATLAB and Python to ensure robustness and reliability. In comparison to traditional PID controllers, the proposed FNN-PID controller demonstrated substantial improvements in overshoot (1% compared to 12.5%), adjustment time (3.8 seconds versus 6.2 seconds), and anti-interference performance, as evidenced by a Lyapunov exponent of -0.42, which confirms the global exponential stability of the system. To enhance the efficiency of the PLC, a lookup table method is employed in lieu of complex operations. The rule layer is derived from fuzzy rule tables and implemented via the lookup table method in the PLC. By precomputing membership functions and rule outputs, the real-time computational workload is significantly reduced. The parameter learning cycle is configured to 100 milliseconds, while the communication update cycle is set at 500 milliseconds. Industrial application verification indicates that the algorithm utilizes only 3%~5% of CPU resources, thereby ensuring robust control performance and uninterrupted operation over a 12 -month period without program failures. The system’s conveying capacity exceeds 50 000 tons. This control system effectively stabilizes the measurement accuracy of cementitious materials within ± 2.0%, offering a viable technical solution for addressing high-precision powder measurement control challenges.
This study examines the impact of cut-off grade characteristics on ore dilution and loss performance in multi-drift ore drawing under sublevel caving without a sill pillar, a prevalent mining technique for underground metal deposits in China. Utilizing a combination of physical model tests and PFC3D three-dimensional numerical simulations, the research is anchored in the context of a substantial vanadium-titanium magnetite mine in Sichuan Province. We conducted specific physical model tests for ore drawing, developed a robust numerical calculation model for multi-drift ore drawing, and investigated the influence mechanisms of varying cut-off grades on ore dilution and loss indices within the multi-drift ore drawing production framework. The results from both the tests and simulations indicate that the cut-off grade exerts a highly significant controlling effect on the indices of ore dilution and loss. For each 1% increment in the cut-off grade, there is a corresponding decrease of 5.38% in ore recovery rate, a 6.88% reduction in the waste rock mixing rate, and a 4.29% decrease in ore dilution rate. Conversely, the run-of-mine grade exhibits an opposite trend, increasing by 1.74%. Through multi-objective optimization analysis based on empirical testing and simulation data, an optimal cut-off grade of 18% has been identified for the mine under study. This determination is anticipated to significantly enhance the comprehensive economic benefits of the mine’s routine underground operations. The findings of this research elucidate the relationship between dilution and loss indices and variations in cut-off grade, thereby providing a robust theoretical foundation for the scientific management of ore extraction.
Spodumene is presently the most critical raw material for lithium extraction, with over 60% of China’s spodumene resources situated in plateau regions exceeding 4 200 meters in altitude. The extreme environmental conditions in these areas—characterized by low atmospheric pressure, low temperatures, and severe water scarcity—pose significant challenges to the application of conventional flotation techniques. Consequently, flotation-based beneficiation in high-altitude regions is often associated with elevated operating costs, inconsistent reagent performance, limited process controllability, and inadequate environmental adaptability. To address these challenges, China has established its inaugural 10 000 t/a heavy-media spodumene concentrator in Dahongliutan. While the implementation of dense-medium separation has effectively reduced beneficiation costs, the resulting heavy-media lithium concentrate typically contains substantial amounts of high -density dark gangue minerals, limiting its Li₂O grade to a pproximately 5%. This not only diminishes the value of the product but also escalates transportation costs over long distances for mining operations situated on remote plateaus. To enhance the grade of heavy-media concentrate, this study investigates the feasibility of employing color sorting technology, leveraging the color contrast between light-colored spodumene and dark gangue minerals. The experimental program comprised trials of binary mixture sorting, comparative asse-ssments of whole-size versus size-fraction sorting, and an evaluation of the effects of particle size on detection sensitivity and separation performance. The objective was to develop a color-sorting flowsheet capable of achieving stable and efficient upgrading under the challenging conditions of high-altitude lithium beneficiation. The findings indicate that particle size classification is crucial in improving optical recognition accuracy and sorting efficiency. In processing heavy-media concentrate with an initial Li2O grade of 5.10%, a flowsheet integrating size classification with one rougher and one cleaner optical sorting stage yielded a final concentrate containing 6.02% Li2O with a lithium recovery rate of 83.17%. In comparison to whole-size sorting, the concentrate grade exhibited an enhancement of 0.46 percentage points, while recovery increased by 6.92 percentage points, indicating a significant improvement in separation performance and the overall beneficiation index. This study provides compelling evidence that color sorting is a technically feasible and economically advantageous method for upgrading lithium concentrate in plateau regions. As a dry, reagent-free, and low-energy separation process, it circumvents the limitations associated with flotation, reduces carbon emissions, and decreases the volume of material requiring transportation. The proposed color sorting strategy presents a sustainable, cost-effective, and environmentally friendly solution for enhancing the utilization efficiency of spodumene resources in high-altitude mining areas. Furthermore, it holds substantial engineering potential to support the industrial development of lithium resources in western China.
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