Channel: Mining Technology and Mine Management http://www.goldsci.ac.cn/hjkxjs EN-US http://www.goldsci.ac.cn/hjkxjs/EN/current.shtml http://www.goldsci.ac.cn/hjkxjs 5 Excavation disturbances induce high stress concentrations and stress redistribution within the mine rock body.Additionally锛宧ydraulic factors diminish the rock body鈥檚 strength.Mines situated in the southern region of China are particularly susceptible to disasters during the rainy season due to the influence of rainfall.Therefore锛宨nvestigating the combined effects of these factors on the mechanical properties of mine rock is of significant importance for ensuring the long-term stability of mine side slopes.The study utilized a slope rock body from the Yinshan Mine in Jiangxi Province as a sample and conducted a graded loading creep test based on a triaxial compression test to investigate the mechanical properties of millimeter-scale rock under the combined effects of excavation unloading and pore water pressure.The results indicate that锛寃ith increasing excavation unloading and pore water pressure锛宼he short-term peak strength and elastic modulus of the saturated millimeter-scale rock progressively decrease.Under identical excavation unloading conditions锛宎n increase in pore water pressure leads to a reduction in the strength of saturated millimeters due to the influence of the pore water pressure.This results in an increase in transient strain锛宎 decrease in the transient elasticity modulus锛宎nd a reduction in resistance to deformation.Additionally锛宐oth creep strain and steady-state creep plasticity exhibit exponential growth with the increase in axial stress up to a certain threshold.Under identical pore water pressure conditions锛宼he instantaneous strain and instantaneous elastic modulus of the excavation-disturbed specimen are lower than those of the undisturbed specimen.Additionally锛宼he creep strain and creep rate escalate with the increasing degree of unloading due to excavation.This observation suggests that excavation-induced disturbances diminish the rock strength锛宺endering the rock body more susceptible to deformation.The findings indicate that the rock strength of phyllite is diminished due to excavation disturbances锛宺endering the rock mass more susceptible to creep damage.The study further reveals that the combined effects of excavation unloading and pore water pressure exacerbate this reduction in strength.Consequently锛宼he rock mass becomes increasingly prone to creep damage锛宼hereby compromising the stability of slopes.

]]> To investigate the impact of freezing and thawing on the crack evolution characteristics during the fracture instabiligy processes of banded magnetite quartzite锛宮echanical and acoustic emission tests were conducted on the rock subjected to a temperature range of -20~20 鈩� and a maximum of 280 freeze-thaw cycles.The results indicate that the uniaxial compressive strength and modulus of elasticity decreased from 200.93 MPa and 21.67 GPa in the dry state to 106.64 MPa and 8.24 GPa after 280 freeze-thaw cycles锛宼he reduction in strength and modulus of elasticity exhibited a tendency to stabilize during the later stages of freeze-thaw cycles锛宺esulting in the establishment of a new dynamic equilibrium between the skeletal structure of the rock samples and their internal microcracks.Additionally锛寀nder conditions of low freeze-thaw cycles 锛坉efined as 鈮�40 cycles锛夛紝the evolution of cracks in the rock samples primarily involved the development of tensile and shear cracks锛寃ith crack rupture predominantly occurring during the accelerated expansion phase of microfracture. The high freeze-thaw cycle 锛坉efined as exceeding 40 cycles锛� significantly influences the crack evolution process in rock samples锛宲redominantly resulting in tensile cracks锛寃hile shear cracks are less prevalent compared to those observed in samples subjected to low freeze-thaw cycles.Notably锛宎s the number of freeze-thaw cycles increases锛宼here is a discernible trend toward a reduction in the overall cracking of the rock samples.Furthermore锛宒uring the accelerated expansion phase of microfractures in rock samples exposed to low freeze-thaw cycles锛宧igh and medium frequency signals emerge slightly earlier than their medium and low frequency counterparts锛宼he amplitude associated with the high-frequency bands was elevated.During the phase of accelerated microfracture expansion in rock samples subjected to extensive freeze-thaw cycles锛宼here was a simultaneous emergence of middle and high-frequency signals alongside middle and low-frequency signals.Furthermore锛宎s the freeze-thaw cycle period increased锛宼he amplitude corresponding to the ultra-high frequency in the rock samples progressively diminished.Under the influence of a low number of freeze-thaw cycles锛宧igh-energy signals predominantly emerge during the accelerated expansion phase of microfractures锛宑haracterized by a more concentrated distribution and increased frequency.Conversely锛寃ith a higher number of freeze-thaw cycles锛宼he distribution of high-energy signals becomes more dispersed锛宎nd their frequency diminishes as the number of cycles increases.These signals are observed throughout the entire loading process. The rock samples subjected to a low number of freeze-thaw cycles exhibit fewer microfractures during the compression stage锛宼he elastic deformation stage锛宎nd the microfracture development stage锛寃ith no apparent correlation to the location of fracture aggregation at the point of rupture.In contrast锛宖or rock samples exposed to a high number of freeze-thaw cycles锛宼here is a significant relationship between the cracks formed during the initial three stages and the locations where cracks aggregate at the time of rupture.The range of acoustic emission energy and the likelihood of high-energy acoustic emission events in rock samples subjected to a high number of freeze-thaw cycles were reduced compared to those subjected to a low number of freeze-thaw cycles.This observation further suggests that rock samples experiencing fewer freeze-thaw cycles are primarily characterized by the development of large and mesoscale fissures.In contrast锛宼hose subjected to more frequent freeze-thaw cycles are predominantly influenced by the expansion锛宮erging锛宎nd fusion of localized fissure networks.

]]> To investigate the relationship between the strength of tailings filling bodies and the content of hydration products锛宮echanical experiments were initially performed to assess their uniaxial compressive strength.The content of various hydration products within the filling body test blocks was quantified using thermogravimetric-differential scanning calorimetry 锛圱G-DSC锛� experiments.Subsequently锛宺egression analysis was employed to examine the correlation between the uniaxial compressive strength of the filling body test blocks and the content of hydration products across different mass concentrations锛宼hereby establishing the relationship between these variables.The results of the strength tests indicate that the early-age strength of the cement powder test block is significantly greater than that of the conventional Portland cement test block.However锛宼his strength advantage diminishes over time.Nonetheless锛宎t 28 days of age锛宼he cement powder test block continues to exhibit superior strength compared to the ordinary Portland cement test block.Furthermore锛宼he thermal analysis experiment reveals that the test block incorporating cementitious powder as the binding material undergoes three distinct weight loss stages during the heating process锛宑orresponding to C-S-H dehydration锛孋aCO₃ decomposition锛宎nd a weight loss peak temperature between 1 144 鈩� and 1 176 鈩� .The test block utilizing ordinary Portland cement as the cementitious material experiences weight loss across the aforementioned three stages and undergoes the decomposition of Ca锛圤H锛夆倐.Regression analysis indicates a strong linear correlation between the strength of the cementitious powder test block and its C-S-H content.Furthermore锛宼he strength of the cement test blocks is associated with the levels of C-S-H and Ca锛圤H锛夆倐锛寃ith the influence of C-S-H content on strength being more pronounced than that of Ca锛圤H锛夆倐.

]]> Ion-type rare earth deposits锛寃hich are abundant in medium and heavy rare earth elements锛宑onstitute strategic mineral resources predominantly located in Jiangxi锛孎ujian锛孏uangxi锛宎nd several other southern provinces and regions.In these deposits锛宺are earth elements are adsorbed onto clay minerals as hydrated cations or hydroxyl hydrated cations.Due to this specific mode of occurrence锛宑onventional mining and beneficiation techniques are ineffective for their extraction.Consequently锛宼he in-situ leaching method is recommended for the efficient recovery of these elements.During the leaching process锛宎n electrolyte solution is introduced into the mineral soil to facilitate ion exchange leaching.Concurrently锛宧eavy metal ions present in the mine soil are mobilized and transported to adjacent farmland and water bodies along with the leaching solution.This migration poses a significant environmental impact on the surrounding areas of the mine.The resultant heavy metal contamination in the soil at the leaching site severely hinders the sustainable development of ion-type rare earth resources.During the in-situ leaching process锛宼he leaching solution engages in an ion exchange reaction with rare earth cations.Concurrently锛宼his process displaces certain heavy metal ions锛宭eading to the mobilization of these metals within the soil.Consequently锛宼his mobilization can result in the contamination of both soil and groundwater with heavy metals.In this study锛宻imulated leaching experiments of ion-type rare earth elements were conducted using three different concentrations of MgSO₄ solutions锛�3%锛�6%锛�9%锛�.The objective was to elucidate the impact of leaching solution concentration on the release of ion-type rare earth heavy metals锛宻pecifically Cu锛孼n锛孭b锛宎nd Tl.The content and influencing factors of these heavy metals were analyzed through correlation analysis and multiple linear regression analysis.The findings indicate that锛寀nder the influence of varying concentrations of MgSO₄锛宼he typical heavy metals exhibit a longitudinal migration trend.A negative correlation was observed between the concentrations of Cu锛孭b锛宎nd Tl and the concentration of MgSO₄锛寃hile no significant correlation was found between Zn and MgSO₄ concentration.Cu was predominantly enriched in the middle soil strata锛孼n in both the middle and lower soil strata锛宎nd Pb and Tl primarily in the lower soil strata.Additionally锛宎 significant negative correlation was identified between soil pH and Eh values.Furthermore锛宑orrelations were noted between soil pH and Eh values and the concentrations of typical heavy metals.The results of this study provide a theoretical basis for the prevention and control of heavy metal pollution and green mining in the mining area.

]]> The process of material particle fragmentation in impact crushers is inherently complex锛宲osing challenges in quantifying and characterizing particle crushing behavior.This study aims to investigate the influence of crushing parameters on the impact crushing characteristics and energy consumption of material particles锛宼hereby elucidating the underlying crushing mechanisms of impact crushers.An analytical method grounded in an active impact crushing experiment was proposed to examine the crushing characteristics of material particles. Firstly锛宼o address the discrepancy between passive impact experiments锛寃hich are commonly employed锛宎nd the active impact crushing behavior of materials in impact crushers锛宼his study involves the design and development of an active impact crushing experimental apparatus powered by compressed air.This device is intended to investigate the impact crushing behavior of material particles under active impact conditions. Subsequently锛宨mpact crushing experiments were conducted utilizing limestone particles of varying initial sizes as test subjects.These experiments were performed under different impact velocities to analyze the crushing patterns of the limestone particles锛宼he degree of fragmentation锛宼he sand formation rate锛宎nd the specific energy consumption per unit of produced sand. The findings indicate that an increase in impact velocity leads to the formation of a greater number of cracks upon impact锛宼hereby resulting in finer fragmented particles. The impact velocity exerts a substantial influence on the average particle size of the crushed product. As the impact velocity increases锛宼here is a corresponding reduction in particle size锛宭eading to a gradual decrease in the average particle size.The most pronounced reduction is observed within the velocity range of 22.4 m/s to 34.0 m/s and particle size range of 22 mm to 25 mm. Beyond this range锛宎s the impact velocity continues to rise锛宼he rate of sand formation deceleration becomes evident. Notably锛寃hen the impact velocity exceeds 55.0 m/s锛宼here is a marked increase in the specific energy consumption per unit of sand produced.Taking into account both the rate of sand formation and the specific energy consumption锛宼he optimal impact effect for limestone particles is attained at an impact velocity of approximately 55.0 m/s.

]]> With the increasing trend of deep resource mining in China鈥檚 alpine regions锛宼he issue of suboptimal outcomes following charge blasting with various coupling medium frequently arises.To investigate the energy distribution of explosives in these alpine environments锛宎nd in alignment with the principles of precision blasting锛宼his study first analyzed the explosion pressure transfer characteristics of different coupling media charges based on explosion dynamics theory.Subsequently锛寀sing LS-DYNA finite element software锛宎 single-hole decoupling charge blasting funnel model for air锛寃ater锛宎nd ice was established.Secondly锛宐ased on the explosion damage cloud map锛宼he volume of the blasting funnel for the uncoupled medium charge was determined.The attenuation characteristics of the explosion pressure and the energy absorption by the rock mass were subsequently analyzed.Finally锛宎n optimization scheme was proposed based on the research findings and was implemented in on-site blasting operations.The results indicate that锛寀nder identical coupling coefficients锛宼he initial pressure peak at the hole wall for water medium decoupling charge blasting increases by a factor of 1.14 to 2.60 compared to air decoupling charge blasting.Additionally锛宼he radius of the blasting funnel crushing zone expands by a factor of 1.04 to 1.11锛宎nd the radius of the fracture zone enlarges by a factor of 1.19 to 1.48.For ice medium decoupling charge blasting锛宼he radius of the blasting funnel crushing zone increases by a factor of 1.02 to 1.12锛宎nd the radius of the fracture zone expands by a factor of 1.15 to 1.48.The explosion pressure of uncoupled charge in air锛寃ater and ice media has an exponential relationship with the distance from the explosion center锛寃hen the coupling medium is water medium.

]]> This study addresses the issue of suboptimal blasting efficacy in water hole blasting within open-pit mines by investigating the impact of detonation modes on rock mass damage.Utilizing a water interval charge configuration at the bottom of the borehole锛宎 numerical simulation model was developed to analyze how variations in the initiation point鈥檚 location and initiation height affect the meso-damage锛宻tress variations锛宎nd energy transfer characteristics of the rock mass.The employed image processing technique facilitates the binarization of rock mass damage images锛宔nabling an analysis of the distribution characteristics of rock mass damage and fragmentation post-blasting.The effectiveness of the blasting process was assessed by incorporating a block evaluation index in conjunction with field testing.The findings indicate that variations in the detonation point position influence the energy distribution and stress propagation post-explosion锛宺esulting in differential rock mass damage.Notably锛宒uring reverse detonation锛宼he rock at the orifice experiences uniform fragmentation锛寃hich is advantageous for subsequent excavation activities.The presence of a water interval at the bottom of the hole extends the duration of energy and stress exerted on the hole鈥檚 base.Consequently锛宼he damage area of the rock mass under reverse initiation increases by 19.76% compared to forward initiation and by 5.78% compared to central initiation.When the water interval at the bottom of the hole measures 0.5 meters锛宼he initiation height is set at twice the interval length from the water interval锛宺esulting in a distance of 1 meter.Under these conditions锛宼he rock mass damage increases by 2.3%锛寃hile explosive unit consumption decreases by 3%~4%.The bulk size锛宐lock unevenness coefficient锛宎nd bulk rate are significantly reduced锛宺esulting in enhanced blasting efficiency and improved blasting outcomes.This research offers valuable insights for optimizing charge structure and adjusting blasting parameters in engineering applications.

]]> In the context of underground mining in metal mines锛宲erforated blasting constitutes a critical component of the operational process.Currently锛宼he design of fan-shaped medium-deep hole blasting charges involves considerable repetitive tasks.Manual interactive adjustments merely satisfy the fundamental design requirements锛宺esulting in significant subjective variability.Both domestic and international scholars have conducted extensive research on the design methodologies for medium-deep hole charges in underground mining.Regarding the application of the empirical rule formula锛宔xperts have undertaken comprehensive research on the ring blasting load spacing in underground stopes锛宱ptimizing drilling and blasting parameters to furnish a scientific foundation for blasting operations in subterranean mines.In the context of CAD auxiliary tools锛宑ertain scholars have employed Visual Lisp and other programming tools to enhance CAD鈥檚 secondary development capabilities锛宼hereby enabling the automated design of sector medium-deep hole charges.In the domain of numerical simulation锛宼he parameters are established through an integration of blasting tests and LS-DYNA numerical simulation analysis锛宭eading to the effective optimization of design parameters for fan-shaped medium-deep hole blasting.Regarding intelligent algorithm research锛宔nhanced extreme learning machine 锛圗LM锛夛紝backpropagation锛圔P锛� neural networks锛宎nd other algorithms are employed to construct a blasting design model锛宖acilitating the intelligent determination of blasting parameters and optimization of charge. Nonetheless锛宼hese methodologies are relatively simplistic and donot incorporate the principles of systems engineering.Therefore锛宼his paper investigated the integration of system engineering optimization methods with the application of blasting design engineering锛宻pecifically focusing on the parametric design methodology for medium-deep hole charges in the context of underground mining.The overarching approach is as follows锛欱y considering the spatial constraints of the blasting boundary and the requisite blasting parameters锛宎 mathematical model was formulated based on the principles of parametric charge design.This model was subsequently solved using operations research techniques to derive the optimal charge design.The research findings were developed and implemented using a digital mining software platform.The formulated charging optimization model was applied to the charging design of medium-deep boreholes in an underground mining context.The results indicate that the proportion of ore fragments in the field锛寃hen utilizing the parameterized charging design锛宨s significantly lower compared to the man-machine interactive charging design under analogous geological and charging conditions.The proposed method for optimizing the charging design of fan-shaped medium-deep holes in underground mines significantly reduces the workload of design technicians and maximizes the uniformity of energy distribution among the holes. This approach effectively enhances the quality of blasting operations.

]]> As shallow resources become depleted and the complexity of underground mining increases锛宼he incidence of accidents in underground mines has risen锛宲resenting significant challenges to mine safety management.Concurrently锛宲ropelled by national policies and the inexorable trend towards smart mine construction锛宎n information platform focused on risk grading control and hazard identification and management emerges is a novel approach for the establishment of mine safety management systems.Firstly锛宼his paper commences with an exploration of the theoretical framework underpinning the dual-prevention mechanism锛宔mphasizing the critical importance of risk grading control and hazard identification and management in the context of mine safety management.In alignment with the 鈥淐lassification of Occupational Injuries and Diseases鈥漚nd the 鈥淩equirements for Occupational Health and Safety Management Systems鈥濓紝mining enterprises are required to establish a systematic and standardized risk assessment system锛宻o this study integrates multiple risk identification methodologies锛宨ncluding the Safety Check List锛圫CL锛夛紝the Likelihood of Exposure Consequences锛圠EC锛� analysis锛宎nd the Fault Tree Analysis锛團TA锛�.By identifying锛宑lassifying锛宎nd controlling risks锛宎s well as implementing closed-loop management for hazard identification and rectification锛宼he comprehensiveness and effectiveness of the safety management system are ensured.This article subsequently provides a detailed description of the steps involved in system construction锛寃hich include the demarcation of operational units锛宺isk identification锛宺isk grading锛宺isk control锛宎nd the critical stages of hazard identification and rectification.The paper delineates the control measures applicable to various risk levels and the closed-loop process for the investigation and management of latent hazards锛宱ffering practical guidance for mining enterprises.Concentrating on the engineering context of the Tiaoshuihe phosphorus mine锛宼his study elaborates on the informatization construction of the mine safety dual-control platform.Through a comprehensive analysis of current safety management systems and remote intelligent monitoring facilities in mining operations锛宻everal critical issues have been identified锛宨ncluding the insufficient implementation of safety risk control measures and the vague specification of risk responsibility systems.In response to these findings锛宎n information management platform has been developed to meet functional锛寀ser锛宎nd business requirements.This platform encompasses multiple modules锛宨ncluding system auxiliary management锛宨nformation dissemination锛宻afety training锛宺isk grading control锛宎nd hazard identification.Employing JavaEE technical standards in conjunction with the SpringCloud and Alibaba microservices framework ensures the system鈥檚 flexibility锛宔fficiency锛宎nd scalability.The platform鈥檚 operational examples illustrate fundamental functionalities such as user authentication锛宺isk assessment锛宧azard source identification锛宮ajor risk statistics锛宎nd the documentation of hazard information.These functionalities are supported by visual interfaces that facilitate data-driven decision-making processes.Furthermore锛宼he platform鈥檚 design incorporates considerations such as data access efficiency锛宒evelopment convenience锛宮aintenance simplicity锛宎nd system operational security锛宼hereby creating a highly efficient and reliable safety management tool for mining enterprises.In summary锛宼his paper examines the dual-prevention mechanism and system construction for mine safety锛宎s well as its practical application at the Tiaoshuihe Phosphorus Mine.It provides theoretical foundations and practical approaches for improving safety management in the mining industry锛寃ith the aim of preventing and reducing accidents.This facilitates the modernization of safety management practices within mining enterprises锛宻afeguards employee lives锛宎nd promotes sustainable corporate development through the implementation of a dual-control mechanism.

]]> This study investigates the relationship between executive compensation incentives and the total factor productivity of resource-based enterprises锛寀tilizing data from China Shanghai-Shenzhen A-share resource-based listed companies from 2012 to 2023.The findings indicate that锛氾紙1锛塃xecutive compensation incentives exhibit an inverted U-shaped effect on the total factor productivity of resource-based enterprises.This impact is particularly pronounced in non-state-owned enterprises锛宔nterprises situated downstream in the industrial chain锛宎nd resource-based enterprises during their growth and decline phases.锛�2锛塖trategic change serves as an intermediary mechanism linking executive compensation incentives to the total factor productivity of resource-based enterprises.Appropriately calibrated executive compensation incentives facilitate strategic change within these enterprises锛宻ubsequently enhancing their total factor productivity.Conversely锛宔xcessively high executive compensation incentives may impede strategic change锛宼hereby diminishing total factor productivity.锛�3锛� Product market competition exhibits an inverted U-shaped moderating effect on the relationship between executive compensation incentives and the total factor productivity of resource-based enterprises.This competition smooths the curve and shifts the turning point to the right.Enhancing the level of competition within the product market can optimize the efficacy of executive compensation incentives锛宮itigate the rate of detrimental effects锛宎nd support the long-term strategic role of these incentives.The conclusion have important decision enlightenment for resource-based enterprises to reasonably formulate incentive contract of executive compensation and improve total factor productivity.

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