Search Results (22)

Mining activities can trigger geological disasters, including slope instability and surface subsidence, posing a serious threat to the surrounding environment and miners’ safety. Consequently, the development of reasonable, effective, and rapid deformation monitoring methods in mining areas is essential. Traditional synthetic aperture radar(SAR) satellites are often limited by their revisiting period and image resolution, leading to unwrapping errors and decorrelation issues in the central mining area, which pose challenges in deformation monitoring in mining areas. In this study, persistent scatterer interferometric synthetic aperture radar (PS-InSAR) technology is used to monitor and analyze surface deformation of the Jinchuan mining area in Jinchang City, based on SAR images from the small satellites “Fucheng-1” and “Shenqi”, launched by the Tianyi Research Institute in Hunan Province, China. Notably, the dual-star constellation offers high-resolution SAR data with a spatial resolution of up to 3 m and a minimum revisit period of 4 days. We also assessed the stability of the dual-star interferometric capability, imaging quality, and time-series monitoring capability of the “Fucheng-1” and “Shenqi” satellites and performed a comparison with the time-series results from Sentinel-1A. The results show that the phase difference (SPD) and phase standard deviation (PSD) mean values for the “Fucheng-1” and “Shenqi” interferograms show improvements of 21.47% and 35.47%, respectively, compared to Sentinel-1A interferograms. Additionally, the processing results of the dual-satellite constellation exhibit spatial distribution characteristics highly consistent with those of Sentinel-1A, while demonstrating relatively better detail representation capabilities at certain measurement points. In the context of rapid deformation monitoring in mining areas, they show a higher revisit frequency and spatial resolution, demonstrating high practical value. Full article

Against the backdrop of the increasing copper demand in a low-carbon economy, this work statistically forecasted the distribution of China’s copper tailings for the first time, and then characterized them as finely crushed and low-grade mining solid wastes containing copper mainly in the form of chalcopyrite, bornite, covelline, enargite and chalcocite based on available research data. China is the globally leading refined copper producer and consumer, where the typical commercial-scale bioleaching of copper tailings is conducted in the Dexing, Zijinshan and Jinchuan mining regions. And these leaching processes were compared in this study. Widely used chemolithoautotrophic and mesophilic bacteria are Acidithiobacillus, Leptospirillum, Acidiphilium, Alicyclobacillus and Thiobacillus with varied metal resistance. They can be used to treat copper sulfide tailings such as pyrite, chalcopyrite, enargite, chalcocite, bornite and covellite under sufficient dissolved oxygen from 1.5 to 4.1 mg/L and pH values ranging from 0.5 to 7.2. Moderate thermophiles (Acidithiobacillus caldus, Acidimicrobium, Acidiplasma, Ferroplasma and Sulfobacillus) and extreme thermophilic archaea (Acidianus, Metallosphaera, Sulfurococcus and Sulfolobus) are dominant in leaching systems with operating temperatures higher than 40 °C. However, these species are vulnerable to high pulp density and heavy metals. Heterotrophic Acidiphilium multivorum, Ferrimicrobium, Thermoplasma and fungi use organic carbon as energy to treat copper oxides (malachite, chrysocolla and azurite) and weathered sulfides (bornite, chalcocite, digenite and covellite) under a wide pH range and high pulp density. We also compared autotrophs in a planktonic state or biofilm to treat different metal sulfides using various sulfur-cycling enzymes involved in the polysulfide or thiosulfate pathways against fungi that produce various organic acids to chelate copper from oxides. Finally, we recommended a bioinformatic analysis of functional genes involved in Fe/S oxidization and C/N metabolism, as well as advanced representation that can create new possibilities for the development of high-efficiency leaching microorganisms and insight into the mechanisms of bioleaching desired metals from complex and low-grade copper tailings. Full article

To address the stress–structural failure phenomenon that can be induced by the excavation of a left-side tunnel section of a 610 m crushing station, an unmanned aerial vehicle was used in this study to collect the geological conditions and rock mass information of the working face, and important geometric information such as the attitude and spacing of rock mass were extracted. Based on the identified attitude and spacing information, a three-dimensional rock mass structure and numerical simulation model of the 610 m crushing station left-side tunnel section were constructed using discrete element numerical simulation software (3DEC) (version 5.0). The results show that the surrounding rock instability of the left-side tunnel section of the 610 m crushing station is controlled by both the stress field in the contact zone between reddish-brown granite stratum and the gray-black-gray gneiss stratum. The cause of stress–structural failure is that the joint sets (JSet #2 and JSet #3) are most likely to form unfavorable blocks with the excavation surface due to unloading triggered by the excavation. Therefore, stress–structural failure disasters in jointed strata sections are one of the key issues for surrounding rock stability during crushing station excavation. It is suggested to adopt ‘optimized excavation parameters + combined support forms’ to systematically control stress–structural failure after unloading due to the excavation from three levels: surface, shallow, and deep. The stress–structural failure mechanism of deep rock mass is generally applicable to a large extent, so the results of this research have reference value for engineering projects facing similar problems around the world. Full article

The stability of the cemented paste backfill roof (CPB roof) is critical to safe production in mines using the underhand drift cut-and-fill stopping. To investigate the scientific and reasonable design method of key parameters (size and strength) of the CPB roof and the stress state of the CPB roof during the mining process, field measurements were carried out with Jinchuan Group’s third mining area as the engineering background. Based on the measurement results, a mechanics model was constructed based on the thick plate theory. The field measurement results show that the overlying load on the CPB roof tends to increase first and then decrease with the gradual mining of the stope, and the maximum overlying load values of the two CPB roofs measured are 0.240 MPa and 0.244 MPa, respectively. With the gradual mining of the stope, the deformation of the CPB roof shows a trend of increasing first and then stabilizing. Based on the thick plate theory, the stress model of the CPB roof is constructed, and the error between the calculation results of the model and the field measurement results does not exceed 5%. Applying the research results to the three mines of Jinchuan Group, the span of the stope can be expanded from 5 m to 6 m under the existing strength standard of the filling body, which can increase its mining capacity by 20%. This study is the first to measure the overlying load and the tensile stress value on the CPB roof, which is an important guideline for related theoretical research. Full article

For the underhand cut-and-fill mining method, to ensure safe and economic mining, a key issue is to correctly determine the required strength of the artificial roof made of cemented paste backfill (CPB). However, the determination of the required strength is typically based on historical experience and analytical beam formulas, resulting in the obtained required strength being unsuitable for the actual situation. Therefore, in order to determine the required strength of the CPB roof reasonably and accurately, field measurements based on sensors were proposed and carried out in the Jinchuan mine, and then formulas based on thick plate theory were derived to verify the measured results. The results show that the required strength obtained by field measurement is 0.325 MPa and that obtained by thick plate theory is 0.304 MPa, with an error of 6.78% between them, verifying the accuracy of the measurements. However, the strength standard currently used by Jinchuan is 0.59 MPa, which far exceeds the optimal strength and results in many additional, unnecessary expenses. To ensure economical mining, the span of the drift was enlarged from 5.0 m to 6.0 m based on the results of the actual measurements and the current production status of the mine. The measurements show that the maximum cumulative subsidence of the drift roof is 11.69 mm and the maximum convergence deformation of the sidewalls is 8.34 mm, which indicates that the stability of the span-enlarged drift is satisfactory. Meanwhile, enlarging the drift span allows for a 20% increase in production capacity per mining cycle. This field measurement method and theoretical analysis model can be used as an efficient guide to facilitate the design of underhand cut-and-fill mining. Full article

Filling slurry can inevitably cause irreversible wear to the pipeline, which represents great costs to mines. This study aims to propose an extended set pair analysis (SPA) for the wear risk evaluation of backfill pipeline. First, to fully describe the wear risk of backfill pipeline, an evaluation index system was established from the aspects of slurry characteristics, pipeline properties, and slurry flow state. Then, the experts grading method was modified with probabilistic linguistic term sets (PLTSs) to obtain subjective weights. Meanwhile, the criteria importance through intercriteria correlation (CRITIC) approach was used to calculate objective weights. By introducing a preference coefficient, they were integrated to determine the comprehensive weights. After that, the classical SPA was extended with membership functions and fuzzy entropy theory, so that the wear risk of backfill pipeline can be evaluated from the perspectives of both the risk level and complexity. Finally, the proposed methodology was applied to assess the wear risk in the Jinchuan nickel mine, Dahongshan copper mine, Hedong gold mine, and Xincheng gold mine. The reliability of evaluation results was further verified through sensitivity and comparative analyses. Results indicate that the proposed methodology is feasible for the wear risk evaluation of backfill pipeline, and can provide guidance on the wear risk management. Full article

The world-renowned Jinchuan Cu-Ni-(PGE) sulfide deposit consists of four mainly independent intrusive units from west to east, namely Segments III, I, II-W, and II-E, and the main sulfide types are the disseminated, net-textured, massive, and Cu-rich ores. Due to the similar geochemical characteristics of each segment, there is no convenient method to distinguish them and explain their respective variations. Meanwhile, considering that the division of different types of ores is confusing and their formation is still controversial, direct classification using elemental discrimination maps can facilitate subsequent mining and research. In this paper, we report the new major and trace elements data from the Jinchuan deposit and collect the published data to construct a database of 10 major elements for 434 samples and 33 trace elements for 370 samples, respectively, and analyze the data based on multivariate statistical analysis for the first time. Robust estimation of compositional data (robCompositions) was applied to investigate censored geochemical data, and the input censored data were transformed using the centered log-ratios (clr) to overcome the closure effect on compositional data. Exploratory data analysis (EDA) was used to characterize the spatial distribution and internal structural features of the data. The transformed data were classified by partial least squares-discriminant analysis (PLS-DA) to identify different compositional features for each segment and ore type. The receiver operator characteristic (ROC) curve was used to verify the model results, which showed that the PLS-DA model we constructed was reliable. The main discriminant elements were obtained by PLS-DA of the major and trace elements, and based on these elements, we propose the plot of SiO₂ + Al₂O₃ vs. CaO + Na₂O + K₂O and Cs + Ce vs. Th + U to discriminate the different segments of the Jinchuan deposit, and the Al₂O₃ + CaO vs. Fe₂O₃^T + Na₂O and Co + Cu vs. Rb + Th + U to discriminate the different ore types. In addition, we predict that there are still considerable metal reserves at the bottom of Segment I. Full article

Mining-induced ground movement is a complicated nonlinear process and a regional geological hazard. Time series in Earth sciences are often characterized as self-affine, long-range persistent, where the power spectra exhibit a power-law dependence on frequency. Whether there exists a periodic signal and a fundamental frequency in the time series is significant in analyzing ground-movement patterns. To evaluate whether a power law describes the power spectra of a ground-movement time series and whether a fundamental frequency exists, GPS monitoring records taken over 14.5 years describing ground movement in the Jinchuan Nickel Mine, China, were analyzed. The data sets consisted of 500 randomly selected GPS monitoring points, spanning the April 2001–October 2015 time period. Whether a periodic signal in the ground movements existed was determined through the autocorrelation function. The power spectra of the ground-movement time series were found to display power-law behavior over vastly different timescales. The spectral exponents of the horizontal and vertical displacements ranged from 0.47 to 3.58 and from 0.43 to 3.37, with mean values of 2.05 and 1.79, respectively. The ground movements of minefields No.1 and No.2 had 1.1-month and 1.4-month fundamental periods, respectively. Together with a discussion of the underlying mechanisms of power-law behavior and relevant influencing factors, these results indicate that ground-movement time series are a type of self-affine time series that exhibit long-range persistence and scale invariance and show a complex periodicity. These conclusions provide a basis for predicting land subsidence in the study area over a timescale. Full article

Due to obvious differences in the properties of the filling body and surrounding rock, deformation always develops near the contact zone. Thus, determining the damage and failure characteristics of the contact zone between the backfill and surrounding rock is a precondition for safe production in mines. Taking Jinchuan mine as study area, the backfill-surrounding rock contact zones are divided into three models according to their different geometric shapes, namely, a linear model, embedded model, and multiple broken line model. A combined numerical simulation and physical model test method was adopted in this study. The research results show that the damage in the linear model begins at the seam, the failure is mainly concentrated in the filling body, and shear failure is dominant. The damage in the embedded model initially occurs around the inflection points, while the damage in the multiple broken line model initially occurs at the seams, and cracks always appear on the vertical contact surface first. Among the three contact models, the stability increases as follows: embedded > multiple broken line > linear. Moreover, the filling body enclosed by surrounding rock is the most stable, and the surrounding rock located in the footwall is more stable than the filling body located in the footwall. The conclusions of this study provide a theoretical basis for designing a mining scheme for Jinchuan mine and other mines with similar geological conditions and mining methods, and they provide a reference for studying the mechanical properties and stability of composite materials. Full article

The backfill mining method transports treated tailings to the mined-out area, which not only improves the surrounding environment of the mine but also enables the mined-out area to continue mining and production under the support of the filling body. However, with the growth in the depth and scale of mining, ground subsidence, and backfill deformation are becoming increasingly serious problems. As an example, in the Jinchuan mine, a typical multi-stage filling mining mine in China, the deformation law of surface rock mass and backfill are studied through a method combining field monitoring and numerical simulation. The major findings are as follows: (a) A settlement funnel is formed on the ground, and its radius gradually expands with continuous mining and filling. The location of the settlement center moves toward the surface above the footwall of the ore body, and the maximum subsidence reaches 739 mm in 14.5 years. (b) Three-section mining significantly affects the surface deformation, and the single subsidence center on the upper wall develops into the double subsidence center with the mining and filling. When the three-section mining is finished, the maximum value of the surface subsidence reaches about 1.35 m and the mining area is still in a relatively stable state. (c) The whole filling body presents obvious subsidence, with the development of the multi-stage mining and filling. Bed separation phenomena are found between the filling layers, and the closer to the interior, the more obvious it becomes. The backfill’s subsidence characteristics are similar to the surface’s; that is, both the subsidence amount and speed are higher on the hanging wall than on the footwall. (d) The backfill mainly shrinks inward in the horizontal direction, and the deformation is mainly manifested as an internal uplift and an external subsidence in the vertical direction. The mass instability of the backfill is difficult because of the insufficient deformation space, and the influence of large-scale deformation on the mining and overlying strata needs to be considered, as well as the local deformation near the rock contact zone surrounding the backfill. The results provide technical support for filling mining in the Jinchuan mine and provide a reference for other projects with similar engineering conditions. Full article

This paper (Part II), right after the Part I, also as an information article, introduces the recent progress of “green mine construction” in China. China is a big country in resource exploitation, but there are serious problems such as hidden danger, environmental pollution and resource waste in the exploitation of mineral resources in China. Therefore, the promotion of “green” mining technology, the implementation of “green mine construction” and the promotion of small- and medium-sized mines to green non-waste mining mode transformation and upgrading are crucial measures on the road of China’s mining development, with very important practical significance. Therefore, this information paper of our Chinese mining research mainly reviews the key progress in the construction and development of green mines and introduces four typical green mine examples in China: (1) the mine with the best green environment in China: Jinhui Mining Co., Ltd., Jiuquan, Gansu Province; (2) the most advanced mine in China: Jinchuan Group Company, Jinchang, Gansu Province; (3) the oldest green mine in China: the Suichang gold mine, Lishui, Zhejiang Province; and (4) the most mechanized mine in China: the Pingshuo Coal Co., Ltd., Shuozhou, Shanxi Province. In the abstract, we claim that Part II serves as a guide to begin a conversation and to encourage experts and scholars to engage in the research of this field. Full article

Wet-mix shotcrete has been widely used to support roadways during the excavation of underground mining. In practice, the mix proportion of wet-mix shotcrete plays a key role in later successful application. To obtain an optimal mix proportion, a large number of trial physical experiments should be carried out. Therefore, in this paper, a new ANN–PSO model is proposed to obtain the mix proportion of wet-mix shotcrete quickly, precisely and economically. The artificial neural network (ANN) model was used to establish the objective functions for particle swarm optimization (PSO) optimization, while the PSO was adopted to optimize mix proportions of wet-mix shotcrete to achieve optimal objectives. This hybrid model was applied to optimize mix proportions of wet-mix shotcrete in the Jinchuan mine. The results revealed that the ANN model yielded a mean relative error (MRE) of 2.755% and an R² of 0.980, indicating an excellent prediction to establish the reasonable objective function. Additionally, PSO spent less than 60 s obtaining an optimal mix proportion of wet-mix shotcrete required by the mine. Consequently, this ANN–PSO model can be used as an efficient design guide to facilitate decision making, prior to the construction phase. Full article

The use of waste rock as an aggregate in mining backfill is environmentally friendly and cost-saving. The backfill slurry flow property varies with the change in aggregate, binder content, solid concentration, and additives. The slurry flow in a pipeline is governed by its properties, which makes it crucial to study the flow properties and their effects. One example is a fly ash-waste rock mixed slurry in Jinchuan Nickel, China. Tests on the slump, slump flow, mortar consistency, layering degree, and bleeding rate are performed to reveal the effects of the slurry concentration, binder content, and fly ash addition on the flow properties. Those relations are analyzed, and two new indices are derived (F₁ and F₂) using the principal component analysis method. Finally, the application results show that F₁ > 0 indicates a nonhomogeneous flow; F₁ < 0 and F₂ > 0 indicates a high-density slurry flow; F₁ < 0 and F₂ < 0 indicates a paste slurry flow. Full article

The safety of underground roadways is a major issue in mining engineering, with economic impacts and potential threats to the lives of workers. Elucidating the deformation failure mechanisms is necessary to solve these problems. The deformation failure modes and characteristics of roadways buried at various depths were investigated using a detailed field survey in the Jinchuan nickel mine. At greater depths, roadway deformation was more serious, the creep phenomena were more prominent, and support structures were more prone to failure. Numerical simulations were performed on the roadways under various geo-stresses and rock mass structures, which indicated that the roadway deformation mode was mainly controlled by a rock mass structure in a lower stress environment and the control effect was weakened with the gradual increase of ground stress. Six deformation failure types were proposed to examine roadway deformation failure mechanisms. Field representation of each failure type was characterized under natural or induced conditions. The findings provide a reference for stability evaluation and support the design of roadway engineering under similar geological conditions. Full article

In order to understand the heavy metal pollution status and ecological effect in aquatic environment around copper mine areas, seven heavy metals (Cd, Cd, Cr, Cu, Hg, Zn, the Ni, and Pb) in aquatic environments in seven representative copper mine regions were selected from the literature in 2005–2013 for ecological risk assessment by using potential ecological risk index, geoaccumulation index, nemerow index and species sensitivity distribution method (Potential Affected Fraction (PAF) and Multi-Substance PAF (MSPAF)). The results of sediment ecological risk analysis showed that Cd, Cu and Pb were the main pollutants in sediments. The results of species sensitivity distribution analysis showed that the HC5 values (Hazardous Concentration for 5% of species) of seven heavy metals were different with order Zn > Cr > Cd > Pb > Cu > Ni > Hg. The MSPAF of seven copper mines in the following order with species sensitivity distribution method was as follows: Dabaoshan (99%) = Dahongshan (99%) = Baiyin (99%) > Dexing (97%) > Jinchuan (92%) > Tongling (39%) > Daye (24%). This study analyzes the impact of copper mining on the aquatic environment, and the results of this study will be great value for the comprehensive pollution governance of mining. Full article