The Back-Longmenshan tectonic belt presents favorable conditions for gold mineralization and has yielded promising outcomes in gold exploration in recent years. Notable gold deposits, including Taiyangping, Dingjialin, and Dongjiayuan, have been successively identified. The Xinjiazui gold mining area, situated in the northeastern segment of the tectonic belt, exhibits well-developed regional stream sediment gold anomalies. Nevertheless, significant progress in mineral exploration has not yet been achieved. To efficiently and effectively assess the mineralization potential of the Xinjiazui area and delineate favorable zones for mineral exploration, a 1∶10 000 soil geochemical survey methodology was selected as the preliminary approach, drawing on previous work experience. Utilizing mathematical statistical methods to analyze and synthesize the dispersion patterns and combination characteristics of element enrichment, geochemical anomalies of elements were delineated and subsequently verified. Two gold deposits were identified in the Ht-5 comprehensive anomaly area, with an inferred gold resource of 3.72 metric tons. Additionally, a gold mineralization body was located in the Ht-2 comprehensive anomaly area. The findings indicate that the soil in this region predominantly originates from the differentiation of in-situ bedrock, with minimal contamination from external substances. The comprehensive soil anomaly is primarily characterized by the presence of gold （Au）, while arsenic （As）, antimony （Sb）, and silver （Ag） are closely associated with gold and serve as key indicator elements for gold prospecting. The gold mineralization is situated within a brittle-ductile shear zone at the interface between the northeast-trending Niutitang Formation and the Maoxian Group. The soil geochemical measurement technique proves to be highly effective for mineral exploration and is considered one of the most efficient methods for gold exploration in the vegetation-covered landscape of the Back-Longmenshan area.
The Wangjiaping gold deposit, situated in the northern segment of the South Qinling orogenic belt, constitutes a recently identified medium-sized, tectonically influenced, micro-disseminated gold deposit. The orebodies are hosted within interlayer fractures of the Upper Devonian Xinghongpu Formation carbonate rocks, which exhibit intricate structural features such as branching, compounding, tip termination and reappearance, and expansion-contraction characteristics. These features indicate a significant structural control on mineralization, corroborated by the multi-phase hydrothermal superposition mineralization observed in the deposit. To assess the deep exploration potential of the deposit, a comprehensive geochemical investigation was conducted on the primary orebody(Ⅱ-1), employing elemental geochemical analysis, structural superposition halo analysis, and tectonic control factor analysis. The findings reveal distinct geochemical zonation patterns：leading-edge halo elements (As, Sb, Hg), proximal ore elements(Au, Ag, W), and trailing halo elements(Bi, Mo, with minor Cu, Pb, Zn), all exhibiting pronounced axial zoning. The spatial distribution analysis of the Ⅱ-1 ore body reveals that anomalies of antimony(Sb), mercury(Hg), and silver(Ag) are notably more extensive and elevated than the orebody itself, overlapping with proximal ore elements. Conversely, anomalies of copper(Cu), lead(Pb), and zinc(Zn) are predominantly concentrated in the central to lower sections of the orebody, while bismuth(Bi) and molybdenum(Mo) are primarily distributed in the lower parts, demonstrating varying degrees of superposition with leading-edge and proximal ore elements. Two critical predictive signatures, namely the “coexistence of front and tail halos” and “strong front and weak tail halos” were identified, indicating the potential presence of blind orebodies at depth. These signatures, in conjunction with the geological structural characteristics, facilitated the delineation of two prospective target zones for further exploration. Subsequent drilling confirmed the predicted target zone C2, with drill hole ZK4302 intersecting the Ⅱ-1 gold orebody at an elevation of 500 m. The intersection yielded a gold grade ranging from 1.16×10-⁶ to 4.21×10-⁶ and a thickness of 3.95 m, thereby validating the exploration model and underscoring the efficacy of the predictive approach. This study elucidates the practical significance of the tectonic superposition halo model in ore prospecting and prediction, while also serving as a valuable reference for deep exploration within the Wangjiaping mining area. Additionally, the findings offer critical insights into the exploration of analogous micro-disseminated gold deposits in the South Qinling orogenic belt, thereby enhancing the understanding of the regional metallogenic framework and augmenting the potential for future discoveries.
A novel category of Nb-Ta-bearing greisenization rocks has been recently identified within the iron ore concentration district of the Anshan-Benxi area, located at the northeastern margin of the North China Craton. These rocks are predominantly found within the Qidashan open-pit mine, where traditional geological survey methods have proven inadequate for assessing the potential of associated strategic metal mineral resources. Consequently, the development and utilization of these Nb-Ta resources have been limited. Through a comprehensive study of the geological and geophysical characteristics of high-grade magnetite ore, greisenization rocks, chlorite schist, and granite, which host the associated Nb-Ta ore, particularly focusing on the distinct variations in electrical parameters among these rocks, a combined exploration strategy was employed. This strategy integrates the high-density resistivity method, utilizing small electrode spacing and multiple electrodes, with the audio-frequency magnetotelluric method, employing medium-to-high-frequency signals to effectively delineate the shape and scale of the Nb-Ta -bearing greisenization rocks. The findings demonstrate that both the high-density resistivity method and the audio-frequency magnetotelluric method are effective in precisely delineating the morphology and scale of Nb-Ta-bearing greisenization rocks, with thicknesses ranging from 40 to 60 meters and depths exceeding 150 meters. This indicates a significant potential for critical metal resources. Additionally, these geophysical techniques are capable of intricately detecting the geological structure of high-grade magnetite ore deposits and the demarcation between iron ores and various surrounding rocks. This provides essential data and empirical evidence for optimizing the design of safe and efficient mining operations, thereby facilitating the integrated development of iron ore and associated Nb-Ta resources.
The Tengjia gold deposit, a recently identified super-large alteration-type gold deposit, is located within the Zhaoping metallogenic belt. The gold orebodies are predominantly situated within fracture zones of the Late Jurassic Linglong granite. The mining area is characterized by the extensive presence of mafic dikes. This study is the first to report the discovery of gold orebodies within these mafic dikes, with a gold grade of 1.50×10-6. To elucidate the genetic relationships among petrogenesis, formation ages, and mineralization processes, a comprehensive investigation was conducted, incorporating petrogeochemical analysis, zircon U-Pb geochronology, and Lu-Hf isotopic analyses were conducted on both gold-bearing and barren mafic dike varieties. The analytical findings indicate that the dikes are characterized by enrichment in large-ion lithophile elements （LILE） and light rare earth elements （LREE）, along with depletion in high-field-strength elements （HFSE） and heavy rare earth elements （HREE）. Combined with negative εHf（t） values, these characteristics suggest that the magmas were primarily derived from an enriched lithospheric mantle source with contributions from ancient lower crustal materials, likely related to the subduction of the Pacific Plate beneath the North China Craton. Gold-bearing dikes exhibit an average Ce-U-Ti oxygen fugacity proxy （ΔFMQ） of +0.89, whereas barren dikes display a lower average ΔFMQ of -0.96. This observation implies that melts with elevated oxygen fugacity are characterized by enhanced metallogenic potential. The dikes contain zircons with evidence of multiple stages of inheritance. U-Pb dating reveals that the emplacement history of the dikes encapsulates geological events experienced by the North China Craton during the Neoarchean, Mesoproterozoic, and Neoproterozoic eras, as well as events associated with the Sulu orogenic belt in the Triassic period. The youngest zircon age from post-mineralization dikes is indicative of their crystallization age, suggesting that the most recent gold mineralization at the Tengjia gold deposit occurred no later than （117.5±1.6）Ma. The zircon U-Pb age of the gold-bearing dikes is （154.4±1.3）Ma, corroborating the occurrence of a gold mineralization event in Jiaodong （eastern Shandong Peninsula） during the period of 162 Ma to 151 Ma.
The Changjiang mineral concentration area in northern Guangdong is a significant production region for granite-hosted uranium deposits in China, notably housing the Mianhuakeng deposit, the nation’s sole super large-scale hard-rock uranium deposit. Uranium mineralization in this area is primarily influenced by near north-south trending fault zones, which are characterized by considerable thickness, high grade, and strong continuity. In order to assess the deep prospecting potential in the northern extension faults of the Changjiang mineral concentration area, the Libiling segment was selected due to its analogous uranium metallogenic conditions to the Mianhuakeng deposit. This segment was subjected to integrated surveys utilizing RaA radon gas measurement and partial extraction geochemical prospecting methods. The aim of this study was to further enhance prospecting outcomes associated with the north-south trending fault zones. The feasibility study of this methodological combination and subsequent exploration practice in the Libiling segment demonstrated the efficacy of integrating RaA radon gas measurement with partial extraction geochemical prospecting methods for predicting deeply concealed uranium deposits. This integrated approach leverages the convenience and immediacy of RaA radon gas measurements alongside the reliability of partial extraction geochemical prospecting in detecting anomalies associated with mineralization. Research indicates that concealed uranium ore bodies are typically situated within composite anomalies of key pathfinder elements, such as uranium (U), radon (Rn), beryllium (Be), and molybdenum (Mo). This pattern is governed by the metallogenic characteristics of hydrothermal uranium deposits, specifically the “synergistic migration and enrichment of multiple elements”，which inevitably results in a composite altered geochemical field exhibiting significant spatial correlation with uranium. In response to the presence of weak anomalies of pathfinder elements in some uranium-prospective locations within the area, a comprehensive prediction index (H) for favorable uranium mineralization areas is proposed by the use of a multi-element combination. This index is designed to address potential oversights in identifying favorable mineralization sites that may occur when relying exclusively on uranium (U) and radon (Rn) composite anomalies for targeting concealed ore bodies. The objective is to “enhance weak anomalies and extract effective information indicative of concealed mineralization”, thereby reducing the likelihood of missing concealed ore bodies in the Libiling segment. Based on the analysis conducted, and with a threshold value of H≥28.1 for the composite predictive index, four composite anomalies (designated as No. ZH-1 to No. ZH-4) were identified, taking into account the geological context of the study area. Among these, the No. ZH-3 anomaly, which exhibits the largest area and highest concentration, was selected for drilling verification. The results revealed an industrial-grade uranium orebody with a cumulative apparent thickness of 8.80 meters and an average grade of 0.085%. This orebody is closely associated with silicification, hematitization, and purplish-black fluoritization within fault belts No.14 and No.19. These findings not only confirm that the deep part of the Libiling segment possesses considerable uranium prospecting potential but also expand the prospecting space in the northern part of the Changjiang mineral concentration area. Furthermore, it provides a scientific reference for deep uranium prospecting prediction in adjacent regions.
Blasting vibrations in open-pit mines can potentially lead to damage in surrounding rock formations，slope instability，ground fissures，and structural damage to buildings. Additionally，these vibrations may disrupt the daily activities and safety of nearby residents and facilities. Accurate prediction of blasting vibrations is essential for scientifically assessing their impact on the surrounding environment and infrastructure，optimizing blasting design parameters，ensuring construction safety，and providing informed decision-making support. Currently，in China，the assessment and verification of blasting vibration safety primarily focus on peak particle velocity and particle frequency. However，relying solely on these parameters as safety criteria is insufficiently reliable. A comprehensive evaluation of the entire blasting vibration process is necessary to objectively assess its characteristics and effects. Consequently，the prediction of blasting vibration waveforms has emerged as a significant area of research. The waveform of blasting vibrations in open-pit mines is influenced by various factors，including geological terrain，blasting parameters，and charge structure.Accurately predicting the waveform of blasting vibrations holds significant practical importance for the analysis of blasting vibration velocity，frequency，duration，and the design and evaluation of safety measures. To facilitate the prediction of blasting vibration waveforms in open-pit mines，this study proposes a novel method that integrates the characteristic value U， representing the distance from the blast source（R）， with principal component analysis （PCA） and a backpropagation（BP） neural network. Initially，this method involves extracting the extreme values from the blasting vibration waveform data and defining an idealized feature value U for R， establishing a corresponding relationship between R and the vibration signal waveform. PCA is employed to conduct a principal component analysis on variables such as step height，R，and explosive consumption，ultimately reducing these variables to two principal components. These components， combined with U， serve as input parameters for the BP neural network，while the corresponding vibration velocities at each time point in the waveform are utilized as output parameters. Extreme value prediction was conducted on the blasting vibration waveform，and the predicted waveform was derived through interpolation calculations. The findings of the study demonstrate that，when comparing the predicted results with the empirical data，the PCA-BP model exhibits a closer approximation to zero than the BP model in terms of root mean square error （RMSE） and mean absolute error （MAE）. Furthermore，the relative error in the peak vibration velocity predicted by the PCA-BP model is less than 11%，and the absolute error in the main frequency is less than 10 Hz. The predictive accuracy of the PCA-BP model surpasses that of the BP model，thereby confirming the model’s accuracy and reliability. This method offers an enhanced capability for predicting blasting vibration waveforms in open-pit mines under consistent topographical，geomorphological，and geological conditions，thereby providing a significant reference for blasting design and safety assessment.
To investigate the blasting effects of continuous and segmented charges, a two-dimensional numerical model of single-hole blasting was developed by utilizing ANSYS/LS-DYNA finite element software. This model employed both the finite element method (FEM) and the smooth particle hydrodynamics-finite element method (SPH-FEM) coupling technique to simulate the rock mass’s single-hole blasting process. Initially, a two-dimensional numerical model was constructed to assess the feasibility and advantages of the SPH-FEM coupling method. Subsequently, using the SPH-FEM coupling approach, three-dimensional numerical models for continuous and segmented charges were developed. The models facilitated a comparative analysis of vibration velocity, pressure fields, effective stress distribution, and damage characteristics of the rock located 1 meter from the blast hole.The study reveals that within the two-dimensional model, the simulation outcomes of the two algorithms exhibit a similar trend, with the damage range being largely consistent. Notably, the SPH-FEM coupling method demonstrates crack propagation with greater clarity, and the simulation results for the crushing area and it more accurately reproduces the dynamic response process of rock mass blasting. The final ejection velocity of the sectional charge rock reached 69.6 m/s, representing a 12.3% increase compared to the continuous charge. Additionally, the stress peak of the free plane mass point, located 1 meter from the blast center, increased by 646 MPa. Under identical blasting parameters, the segmented charge structure yields superior blasting performance and effectiveness.
The transition from open-pit deep mining to underground mining presents significant challenges in managing ground pressure and ensuring production safety due to the nonlinear deformation of the overlying rock and its roof. To investigate the stability of high, steep rock slopes at varying angles, as well as the dynamic deformation, failure characteristics, and evolution ary patterns of the roof and overlying rock in underground mines, the open-pit to underground filling method employed at Kunyang Phosphate Mine No. 2 was selected as the focus of this study. A 200-meter high steep slope model was developed through a combination of field investigations, laboratory rock mechanics tests, and MatDEM numerical simulations. The study examined stress and displacement variations of the slope at three different angles —35 °, 45 °, and 55 °—in addition to analyzing the dynamic stress and displacement of the underground mining area’s roof and overlying rock, there by elucidating their evolutionary patterns. The findings of the study demonstrate that during the transition from open-pit to underground filling mining, the displacement of the mining area’s roof evolves dynamically from localized settlement to a comprehensive settlement of the overlying rock, particularly during the backfilling of the mining pillar. An “elliptical arch” subsidence zone, centered on the stope and oriented perpendicular to the ore layer’s dip direction, progressively enlarges as the working face advances. The range of stress disturbance during the backfilling and filling of the mining room extends from the roof of the mining area to encompass the entire overlying rock during the backfilling and filling of the mining pillars. The stress variations within the mining site are dynamically modulated by the mining face, undergoing four primary stages: stress redistribution, stress concentration, filling pressure adjustment, and stress equilibrium. The mining activities have induced a parabolic vertical displacement curve at the slope waist, resulting in varying degrees of tensile fracture damage. Consequently, the displacement at the slope waist has significantly decreased, leading to the occurrence of small-scale landslides. The study observed differential unloading phenomena at the midsection of the slope, with stress initially decreasing before subsequently increasing. The overlying rock of stope and the roof both exhibit a pattern where a larger slope angle leads to a greater range of displacement and subsidence, as well as an increased variation in stress. The findings offer valuable insights for transitioning open-pit mines to underground mining under similar occurrence conditions.
In addressing the issue of multiple localized small-scale failures on the slope of an open-pit mine, this study utilized numerical simulation methods to examine the dynamic response characteristics and stability of a three-dimensional slope under blasting conditions. Initially, an analysis was conducted on the slope’s vibration velocity, displacement, and plastic zone, based on the existing blasting process parameters of the mine. Subsequently, the study investigated the impact of variations in single-stage explosive charge on the blasting vibration velocity and safety factor of the three-dimensional slope, thereby establishing the relationship between single-stage charge, slope dynamic response, and safety factor, and optimizing the maximum single-stage charge. Finally, the dynamic response characteristics of the three-dimensional slope under the optimized maximum single-stage charge were analyzed, and a comprehensive stability evaluation of the slope was performed by considering both the safety factor and the peak particle vibration velocity. The findings demonstrate that, under the initial single-stage charge, blasting exerted the most pronounced effect on horizontal vibration velocity, with a principal-direction peak vibration velocity of 16.40 cm/s, surpassing the safe allowable threshold. The maximum horizontal displacement of the slope reached 2.94 cm, and the slope safety factor was calculated at 1.13, falling short of regulatory standards and indicating a state of localized instability. The plastic zone exhibited interconnectivity at the slope toe, suggesting localized failure in that region. As the single-stage charge was increased, the peak vibration velocity consistently escalated, while the safety factor progressively diminished. Specifically, when the single-stage charge was augmented from 75 kg to 225 kg, the vibration velocity rose from 2.73 cm/s to 12.54 cm/s, and the safety factor decreased from 1.38 to 1.17. Through optimization analysis, the maximum permissible single-stage charge was identified as 200 kg. Under these conditions, the principal-direction peak vibration velocity was 10.60 cm/s, remaining within the safe allowable range, and the slope safety factor improved to 1.20, thereby satisfying regulatory requirements and indicating a stable state.The research results provide a scientific basis for blasting construction and stability control of the open-pit mine slope, offering valuable insights for similar engineering projects. Additionally, the study reveals the specific mechanisms of blasting vibration effects on slope dynamic response, providing important theoretical support for mine safety production and slope stability management.
To ensure the safety and stability of sandstone surrounding rock in deep metal mining environments, this study systematically examined the mechanical behavior and energy evolution characteristics of sandstone subjected to varying degrees of damage under cyclic loading and unloading conditions. Standard cylindrical sandstone specimens underwent pre-loading treatment to induce different damage levels, which were subsequently verified through ultrasonic P-wave velocity tests. Following this, cyclic loading tests were performed under a consistent stress path to thoroughly assess the mechanical response and energy dissipation behavior of the specimens. The findings reveal that as the degree of damage increases, the strength and stiffness of the sandstone progressively diminish. Compared to the undamaged samples, the peak strength values of the damaged specimens decreased by 3.648%, 7.116%, 19.921% and 28.492%, respectively. Furthermore, the stress-strain curves demonstrated a transition from brittle to ductile failure modes. Furthermore, as the degree of damage increased, the average elastic modulus of the sandstone specimens exhibited a significant decline. This suggests that specimens with higher levels of damage are more susceptible to crack penetration and micro-fracture propagation. An analysis of the energy dynamics revealed that both strain energy and dissipated energy during cyclic loading generally followed a pattern characterized by an “initial drastic fluctuation followed by subsequent stabilization”. For specimens exhibiting low damage levels, strain energy remained relatively high during the stabilization phase, and the proportion of dissipated energy was low, indicating limited crack development. Conversely, specimens with high levels of damage displayed well-developed cracks, with energy distribution shifting predominantly towards dissipation. This shift renders them more vulnerable to internal fracturing and deformation-induced instability, as evidenced by a higher proportion of dissipated energy. The proportion of dissipated energy increased with the degree of damage, accompanied by a notable rise in both damping energy and damage energy contributions. The energy damage ratios for sandstone specimens at varying levels of damage were observed to be 15.030%, 15.978%, 17.508% and 23.899%, respectively. These findings suggest that as the degree of damage increases, there is a corresponding rise in the proportion of irreversible energy consumption attributable to microcrack propagation and plastic deformation. This results in heightened vulnerability and an increased potential risk of instability during cyclic loading. The mechanical weakening mechanism of damaged sandstone is primarily influenced by the interplay of local stress concentration induced by microcrack propagation, cooperative crack networking, and irreversible energy dissipation. This degradation process is characterized by distinct nonlinear and staged features. The outcomes of this study enhance the understanding of the nonlinear weakening mechanisms of damaged sandstone under cyclic loading, and provide essential theoretical insights and practical support for the design of support structures and the management of rock mass stability in deep metal mining environments.
In the context of the mine support project, the mechanical properties of metal trays are significantly influenced by corrosion due to the surrounding harsh working conditions, resulting in their gradual degradation. To investigate the damage evolution of metal trays in corrosive environments, this study focuses on the saucer tray used in mine pipe-seam bolts. It comprehensively considers the factors of temperature and pH value and conducts salt spray accelerated corrosion tests and mechanical performance assessments in a controlled laboratory setting. The impact of varying corrosion conditions on tray performance was systematically evaluated by analyzing the apparent corrosion morphology, mass loss rate, and compressive strength attenuation. The results indicate that: (1) At the beginning of the test, the tray exhibited a rapid corrosion rate, with corrosion products quickly adhering to its surface, leading to the formation of expansion bubbles containing the corrosive liquid. The internal corrosion liquid facilitates secondary corrosion of the tray, ultimately leading to the development of expansion bubbles to a certain extent. These bubbles are interconnected, resulting in an increased area and depth of the corrosion layer. (2) The effect of temperature on the corrosion mass loss rate and the compressive strength of the tray is in consistent. As temperature rises, corrosion products become relatively loose and prone to detachment, promoting overall uniform corrosion, and the mass loss rate gradually increases with temperature. The compressive strength is influenced by the overall structure of the tray, with the depth of the corrosion pits being a decisive factor. (3) In a strong acidic environment, when the H+ concentration is excessively high, the impact of temperature rise on the dissolution of corrosion products is not significant. However, as acidity decreases and H+ concentration diminishes, the influence of temperature on compressive strength slightly increases. The acidic environment is the predominant factor determining the tray’s mechanical properties. (4) The influence of pH value on the corrosion behavior of trays manifests in several dimensions. In acidic solutions, an elevated concentration of H+ ions enhances proton activity and decreases the activation energy required for the anodic reaction, thereby facilitating the anodic dissolution of the metal surface. Concurrently, the heightened H+ concentration augments the driving force of the cathodic reaction, further accelerating the overall corrosion process. Moreover, the acidic environment increases the solubility of corrosion products. This study elucidates that pH value is the primary factor affecting the degradation of the mechanical properties of pallets post-corrosion, while an increase in temperature predominantly contributes to mass loss by promoting uniform corrosion.
To examine the crushing characteristics, particle size distribution, and manganese enrichment of manganese ore under impact conditions, a series of impact crushing experiments were conducted using a falling weight apparatus. The particle size distribution of the crushed products, subjected to varying specific impact energies and initial particle sizes, was systematically analyzed through sieving. This analysis aimed to elucidate the effects of specific impact energies and particle sizes on the crushing behavior of manganese ores. Additionally, the manganese content in the crushed products of each particle size was quantified using X-ray fluorescence （XRF） analysis. The findings indicate a correlation between the crushing degree of manganese ore and both specific impact energy and particle size, with the degree of crushing increasing alongside specific impact energy. Subsequently, a detailed regression analysis was performed on the experimental data, and a tn -t 10 particle size distribution prediction model was developed, accompanied by the construction of a series of tn curves representing the size distribution of crushed products. Experimental validation demonstrated that the model effectively predicts the particle size distribution of the se products. This model not only elucidates the crushing behavior of single-particle manganese ore under impact conditions but also serves as a foundation for predicting the particle size distribution of crushed materials. X-ray fluorescence （XRF） analysis indicates that manganese is predominantly concentrated in the fine particles （-0.630+0.075 mm）, with the highest concen-tration observed in the grain size range of -0.315+0.160 mm. Conversely, manganese enrichment in the coarse particles （-5.00+0.63 mm） decreases progressively as particle size increases. This research offers theoretical insights for enhancing the resource utilization of manganese ores.
As advancements in mining processes persist, tailings are increasingly characterized by finer granularity. Nevertheless, the homogenization of ultra-fine tailings presents challenges, including uneven mixing, limited flowability, and particle agglomeration. To address these challenges, a mixing tank device with dimensions of Φ2 m×2 m was designed using SolidWorks, and its homogenization was analyzed through Fluent numerical simulation. The Multiple Reference Frame （MRF） method was utilized to solve the model, examining two materials with viscosities of 0.40 Pa·s and 0.55 Pa·s to assess the impact of various mixing parameters on ultra-fine tailings. The simulation focused on evaluating the effects of impeller type, diameter, and installation height on mixing homogenization. Additionally, a model featuring co-rotating twin impellers was developed for further analysis, employing stirring velocity contour plots from both front and top views to assess stirring performance quality. The study’s findings reveal that optimal stirring is achieved with a six-blade turbine, an impeller diameter of 0.9 m, and an installation height of 0.35 m. The axial and radial movement of materials within the stirring tank is vigorous and encompasses a wide range, facilitating uniform mixing. As the viscosity of ultra-fine tailings increases, there is a notable reduction in the area of maximum velocity distribution, necessitating an increase in both stirring speed and duration to achieve improved homogenization. An industrial trial was subsequently conducted using tailings from a gold mine to validate these findings. The mixing parameters for the trial’s mixing tank were established based on the research outcomes, with a mixing speed set at 180 revolutions per minute for a duration of 2 minutes. Upon solidification of the underground backfill slurry, the sample tests indicated satisfactory uniformity, effective water retention, minimal bleeding, absence of significant large bubbles, and a compressive strength exceeding 1 MPa after three days, thereby meeting the criteria for mine backfilling. These research findings offer valuable insights into the homogenization mixing parameters for ultra-fine tailings.
A mining operation in Xinjiang is transitioning its extraction technique from open-stope to backfill mining. This study aims to examine the effects of mass fraction（A）, sand-to-cement ratio（B）, waste rock particle size（C）, and their interactions on the rheological properties of waste rock-unclassified tailings backfill slurry. To achieve this, response surface methodology（RSM） was utilized in conjunction with a Box-Behnken experimental design to quantitatively assess rheological parameters through L-shaped pipeline simulation tests. Seventeen experimental groups were established based on a three-factor, three-level design, employing an L-shaped pipeline apparatus with an inner diameter of 50 mm and a bend line ratio of 3.13. Yield stress and viscosity coefficient were determined using static equilibrium and shear stress equations. A quadratic regression model was constructed and analyzed for variance using Design-Expert 13 software. The experimental findings demonstrated a significant positive correlation between yield stress/viscosity coefficient and mass fraction. Variance analysis revealed that the primary effects were ranked in the order of A>C>B, corresponding to mass fraction>waste rock particle size > sand-to-binder ratio. The interaction effects were ranked as AC>BC>AB, with the AB interaction having no significant impact on yield stress. Dynamic sensitivity analysis showed that a decrease in mass fraction led to a gradual weakening of the influence of waste rock particle size on yield stress and the viscosity coefficient. Similarly, the effect of the sand-to-binder ratio on the viscosity coefficient also diminished. When the waste rock particle size was small, the influence of the sand-to-binder ratio on viscosity coefficient was reduced. Likewise, at lower sand-to-binder ratios, the impact of waste rock particle size on yield stress and the viscosity coefficient became less significant. Response surface methodology （RSM） optimization identified the optimal mix ratio as a mass fraction of 86%, a sand-to-binder ratio of 7.427, and a waste rock particle size of -5 mm. Under these conditions, the relative error between the predicted rheological parameters and the average values from five validation tests was less than 5%, confirming the model’s high predictive accuracy. This study offers significant insights into optimizing the mix ratios of mine waste rock-tailings cemented fill slurry, thereby providing a solid theoretical basis for achieving low-resistance and high-stability backfill in practical engineering applications.
With the ongoing development of China’s gold resources, there is an increasing prevalence of low-grade gold deposits. Consequently, the implementation of advanced and efficient mineral processing technologies is crucial for optimizing the recovery and utilization of gold. This study focuses on a ductile shear zone gold deposit located in JiangxiProvince as the subject of investigation. Utilizing the mineralogical characteristics of the raw ore, the study explores the optimal flotation process and reagent system to address variations in gold recovery associated with different flotation methodologies. Comparative experiments were conducted between rapid flotation and conventional flotation processes. The findings from the process mineralogy analysis reveal that the ore’s metallic minerals are predominantly pyrite and arsenopyrite, while the gangue minerals are primarily quartz and muscovite. Gold, with a grade of 3.36×10-6, is identified as the most valuable component, whereas the concentrations of other potentially useful components are relatively low and donot meet the criteria for economic recovery. The gold minerals are characterized by fine granularity, con-sisting mainly of grained and microgranular gold. The primary gold-bearing minerals are pyrite and arse-nopyrite, with approximately 95% of gold minerals being closely associated with metal sulfides. Optimization experiment s indicate that the optimal flotation performance is achieved under conditions where the grinding fineness is -74 μm, accounting for 75%, of the material. This is accomplished by using 300 g/t of sodium carbonate as a pH regulator, a combination of 80+20 g/t sodium isoamyl xanthate and ammonium dibutyl dithiophosphate as collectors, 24 g/t of No.2 oil as a foaming agent, and a cumulative flotation time of no less than 14 minutes. Results from closed-circuit test ing demonstrate that employing rapid flotation technology yields two types of gold concentrate products, with gold recovery rates of 75.73% and 18.16%, and gold grades of 67.93×10-6 and 46.39×10-6, respectively. The overall gold recovery rate for the gold concentrate is 93.89%, with a gold grade of 62.33×10-6. In contrast, the conventional flotation process produces a gold concentrate with a grade of 62.9×10-6 and a gold recovery rate of 92.44%. There is a slight difference in the beneficiation indicators between the two processes. The rapid flotation process proves advantageous in enhancing the gold recovery rate, by adhering to the principle of early recovery if possible. This approach minimizes the recirculation of gold minerals within the flotation system, facilitates on-site regulation, and ensures stable flotation indicators. Consequently, it can be recommended as an efficient method for the recovery of gold minerals.
Fine particulate gold, which is challenging to recover, is anticipated to become a primary resource for future utilization as larger and more easily processed gold deposits are increasingly depleted. Traditional flotation methods exhibit limited efficacy in collecting fine-grained minerals due to the large size and specific surface area of conventional flotation bubbles. To address this limitation, nanobubble flotation technology has been implemented to enhance the recovery of fine particulate gold-bearing pyrite. This study examines the distinctions between traditional bubble flotation and nanobubble flotation for fine particulate gold-bearing pyrite through a series of flotation experiments, laser particle size analyses, and calculations of particle size recovery. Experimental investigations into grinding fineness reveal that nanobubble flotation technology consistently achieves a higher recovery index compared to traditional flotation methods, even when, dealing with relatively finer particle sizes. Additionally, nanobubble flotation demonstrates superior selectivity in the flotation process. Nanobubble flotation has demonstrated a significant reduction in the required dosages of collectors and frothers while still achieving higher-grade concentrates, even under conditions of increased pulp concentration. The flotation kinetics experiments indicate that nanobubble flotation completes the process 70 seconds faster than traditional flotation methods, with an 8% improvement in concentrate recovery. Fur-thermore, when achieving equivalent concentrate grades, the recovery rate with nanobubble flotation is notably superior to that of conventional flotation techniques. Particle size analysis of the flotation concentrate reveals that the lower limit of flotation particle size decreases from 2.6 μm to 0.2 μm in the presence of nanobubbles, compared to traditional bubble flotation, and the average particle size is reduced from 99 μm to 26 μm. This effectively facilitates the efficient recovery of fine particle gold. Additionally, nanobubbles decrease the surface potential of pyrite and increase the contact angle on the pyrite surface. In the absence of nanobubbles, the surface potential of pyrite decreases by 5.36 mV, and the surface contact angle increases by 10°. This indicates that the presence of nanobubbles mitigates the electrostatic repulsion among pyrite particles while enhancing hydrophobic attraction. Consequently, this leads to the formation of more stable hydrophobic aggregates of fine particle gold-bearing pyrite, thereby maintaining a larger apparent size of fine-grained loaded pyrite and increasing the likelihood of flotation interactions between bubbles and particles.Thus, the presence of nanobubbles significantly enhances the recovery of fine particle gold -bearing pyrite.
To evaluate the current state of ecological destruction and pollution at historical abandoned mines in the Gansu section of the Yellow River Basin, and to facilitate comprehensive ecological assessments and remediation strategies, this study introduces a robust evaluation methodology for the mining ecological environment, employing the analytic hierarchy process（AHP）. This methodology meticulously accounts for intricate geological conditions, land degradation, pollution levels, and other vital ecological, factors pertinent to mining sites. It is specifically tailored to ensure that the evaluation outcomes align with the multifaceted requirements of natural resource management, forestry and grassland management, and ecological environment authorities. Initially, twelve evaluation indicators were identified across three dimensions: ecological damage, vegetation destruction, and pollution status. A scientifically rigorous indicator system was developed based on empirical field survey data of the mining ecological environment within the study area. Subsequently, judgment matrices were formulated using the analytic hierarchy process, integrating insights from regional mining ecological environment surveys. Scripts were developed using MATLAB software to compute the eigenvectors, eigenvalues, and consistency indices of the matrices. The execution of these scripts resulted in the determination of weight coefficients for each evaluation indicator. Subsequently, the evaluation results were validated through cross-verification with actual survey data and preliminary assessment grades from historical abandoned mining areas within the Yellow River Basin in Gansu Province. This process established definitive threshold values for grading the overall assessment levels. The method facilitates a comprehensive evaluation and grading of mining-related ecological environment issues, thereby providing theoretical support for the formulation of differentiated remediation strategies. The feasibility of the method was demonstrated using Lanzhou as a representative case study, where the evaluation results exhibited a high degree of concordance with on-site investigations. The findings indicate that among the 34 townships affected by mining activities, 10 were classified as severely impacted, 13 as moderately impacted, and 11 as lightly impacted, based on the degree of influence. Consequently, recommendations for ecological restoration strategies that emphasizegraded control and optimized sequencing have been proposed. This approach offers a scientific framework for the implementation of targeted ecological management interventions in mining areas situated within ecologically fragile zones.
Rare earth elements constitute a critical strategic mineral resource, and the stability of the global rare earth industry chain has emerged as a focal point of international concern amid geopolitical dynamics. Utilizing data on China’s rare earth import and export trade spanning from 2013 to 2023, this study examines the evolution of China’s trade dependence on rare earth products, the changing patterns of the trade dependence network, and the primary influencing factors. The findings reveal significant disparities in the product structure of China’s rare earth import and export activities, characterized by a trade pattern of “low-value imports and high-value exports.” From the perspective of trade dependence, China’s dominant position in the global rare earth trade has been reinforced. In terms of degree centrality, node connection intensity, and betweenness centrality within the global rare earth trade dependence network, China has progressively ascended in ranking and has emerged as one of the core countries in the network of trade dependence for rare earth products. Furthermore, factors such as trade partnerships, levels of economic development, trade dependence, economic proximity, and institutional frameworks significantly influence the majority of rare earth products. In light of these findings, several recommendations are proposed: to optimize the import patterns of resource-based products at the upstream segment of the rare earth industry chain, to strengthen the technical advantages in smelting and separation processes at the midstream segment, and to fully leverage the scale advantages of magnetic material products at the downstream segment of the industry chain.
甘公网安备 62010202000672号