Ore Block Research Articles

Prediction of the height of caving zone above the undercut in block caving mining method

The block caving is one of the most commonly used methods in underground mining of massive, low/high grades, and deep deposits. As a result of undercutting, caving occurs and propagates toward the upper part of the ore block. It is essential to predict the height of caved ore and its volume based on shape of the caved zone to make an economic decision. This paper describes the mechanism of height of the caving zone development. Consequently, four new mathematical models (prismatic, parabolic, cubic, and hemispheric) are proposed to estimate the height of this caving zone. The results are compared with the existing approaches. The proposed methods have proven that the height of caving zone has a linear relationship with the uniaxial tensile and compressive strengths and the height of undercut as well. Also, the height of the caving zone has a negative exponential relationship with unit weight of undercut roof materials and its expansion factor. The Height of the caving zone of the prismatic model is 1.5 times higher than the parabolic model and 1.3 times higher than the hemispheric model. The cubic model estimates the lowest height of the caving zone (0.3 times the height estimated by the prismatic model). The average height of the caving zone, taking the average unit weight of 27 KN/m3 into account, is about 69.4 times the tensile strength, 5.8 times the uniaxial compressive strength of the rock mass, and 18.8 times the height of the undercut.

Experimental study of the influence of borehole parameters on prompt fission neutron uranium logging and its corrections

In prompt fission neutron uranium logging, borehole environmental parameters affect the measured results and must be corrected. In order to explore the influence of borehole parameters on the interpretation of logging results, this paper builds a sandstone type uranium ore block model to simulate the field production drilling device based on the “Epithermal/Thermal neutron counting rate ratio” (E/T) theory. The effects of borehole diameter, thickness of iron tube and well fluid on the decay rate of epithermal and thermal neutrons and their uncertainty correction methods were investigated. The results show that the effect of borehole diameter on E/T is negligible. The iron tube thickness has a certain effect on the moderation and absorption of epithermal and thermal neutrons, and its E/T increases slightly with increasing thickness. The influence of iron tube thickness on E/T is corrected and the relative uncertainty is less than 5%. The well fluid thickness also affects the decay rate of epithermal and thermal neutrons, and its E/T follows the law of negative exponential attenuation. The influence of well fluid thickness on E/T is corrected and the relative uncertainty is less than 5%. This study provides technical guidance for field well survey of uranium deposit.

Genesis of the Supergiant Shuangjianzishan Ag–Pb–Zn Deposit in the Southern Great Xing’an Range, NE China: Constraints from Geochronology, Isotope Geochemistry, and Fluid Inclusion

The supergiant Shuangjianzishan (SJS) Ag–Pb–Zn deposit, located in the southern Great Xing’an Range (SGXR), is the largest Ag deposit in China. The SJS deposit can be divided into two ore blocks: the Shuangjianzishan ore block and the Xinglongshan ore block. Given the importance of the Xinglongshan ore block in the SJS deposit, our work is focused on the Xinglongshan ore block. The vein orebodies in the Xionglongshan ore block mainly occur in the NW-, NNW-, and NNE-trending fault zones, and its mineralization is mainly related to a deep concealed syenogranite. Here, we present new geochronology, isotope geochemistry, and fluid inclusion data for the Xinglongshan ore block and provide additional insights into the metallogenic mechanism of the deposit. The dating results show that the syenogranite related to the mineralization formed at approximately 137 Ma, which is coherent with some previous age determinations in sulfides from the ore deposit. The mineralization of the Xinglongshan ore block can be divided into four stages: sphalerite–arsenopyrite–pyrite–chalcopyrite–quartz stage (stage I), sphalerite–galena–pyrite–silver-bearing mineral–quartz stage (stage II), sphalerite–galena–silver-bearing mineral–quartz–calcite stage (stage III), and weakly mineralized quartz–calcite stage (stage IV). Four types of fluid inclusions (FIs) have been identified within quartz and calcite veins: liquid-rich, gas-rich, pure-liquid, and pure-gas FIs. The homogenization temperatures in the four stages exhibit a gradual decrease, with stage I ranging from 253 to 302 °C, stage II from 203 to 268 °C, stage III from 184 to 222 °C, and stage IV from 153 to 198 °C, respectively. The salinity for stages I, II, III, and IV falls within the ranges of 3.4–6.6 wt% NaCl eqv., 2.6–7.2 wt% NaCl eqv., 2.9–7.0 wt% NaCl eqv., and 1.2–4.8 wt% NaCl eqv., respectively, indicative of a low-salinity ore-forming fluid. The δ18Owater and δD values of the ore-forming fluid span from −13.9‰ to 7.4‰ and −145‰ to −65‰, with δ13CV-PDB values between −11.0‰ and −7.9‰. These values suggest that the ore-forming fluid predominantly originated from a mixture of magmatic and meteoric water. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of sulfides range from 18.278 to 18.361, 15.530 to 15.634, and 38.107 to 38.448, respectively. These ratios imply that the ore-forming material was primarily derived from the Early Cretaceous granitic magma, which resulted from the mixing of depleted mantle- and crustal-derived magmas. The fluid mixing was the dominant mechanism for mineral precipitation. The Xinglongshan ore block belongs to a magmatic-hydrothermal vein-type deposit related to the Early Cretaceous syenogranite, and the Shuangjianzishan ore block belongs to an intermediate sulfidation epithermal deposit related to coeval subvolcanic rocks. The Ag–Pb–Zn mineralization at Shuangjianzishan is genetically related to the Early Cretaceous volcanic–intrusive complex.

Shaft Wall Damage to High-Depth Inclined Ore Passes under Impact Wear Behavior

In order to study shaft wall damage resulting from ore drawing in ore passes, a theoretical model for predicting the shaft wall damage to high-depth inclined ore passes is constructed based on field surveys of 25 ore passes in a deep mine in Yunnan, China. The mathematical expression of the total shaft wall damage volume is derived using the contact mechanics theory. Considering the structural characteristics of ore passes, and taking No. 1, 2, 3, and 9 ore passes as examples, combined with numerical simulation and an engineering case, the rationality of the proposed theoretical model is verified with respect to the initial collision position and the damage conditions of the shaft wall. The influence of, and sensitivity to, the ore block size P and the structural parameters of high-depth inclined ore passes on the total shaft wall damage volume Qtol are quantitatively analyzed. The results show that the calculation results of the theoretical model and numerical simulation are in good agreement with the actual engineering situations. Moreover, the ore-pass dip angle θ and the inclined angle of the chute α have a significant impact on the damage to the shaft wall, while the effects of the ore-pass depth H and the shaft diameter D are comparatively minor. With an increase in θ or α, Qtol generally first increases and then decreases. Qtol increases exponentially with P and increases steadily with D. H affects Qtol by influencing the collision frequency between the ore and the shaft wall. Therefore, in the mining design of deep mines, θ and α should be minimized as much as possible or adjusted to approach 90°, thereby reducing damage to the shaft wall. Secondly, ore block size should be strictly controlled to prevent collapses in the shaft wall caused by large ore blocks. This work provides technical support for the long-term safe operation of high-depth inclined ore passes.

Mining and geological models of virtual complex ore blocks of the bench

Purpose. Creation of mining and geological models of virtual complex ore blocks of a bench to develop a basic methodology for determining the geological structure of complex structural sections of mineral deposits. Methodology. In the scientific and technical substantiation of mining and geological, mining and technical indicators of complex structural blocks in terms of ore saturation and complexity of the morphological structure of blocks of ledges, methods of complex and abstract-logical analysis, synthesis, systematization, the method of theoretical generalization, generalization of information sources and world experience in the field of geoinformation of complex structural deposits, statistical analysis, mathematical modeling, mining and geological modeling of mineral deposits were applied. Findings. Mining and geological models of virtual complex structure ore blocks (CSOB) of the bench have been created. The mining and geological characteristics of the blocks are analytically interconnected with the geometric parameters of the scattered ore bodies and the dimensions of the layer of admixed rock or lost ore. They determine the degree of complexity of the geological structure of the CSOB. According to the given sizes and location of disparate solid and dispersed ore bodies of virtual complex structural blocks, the numerical values of the mining and geological characteristics of ore blocks were calculated using the developed method. CSOB are subdivided into more ore-saturated, moderately ore-saturated, less ore-saturated as well as complex structural and more complex structural ones. Originality. For the first time in mining, the concepts of “virtual complex-structural ore blocks of a bench” and “mining and geological models of virtual complex-structural ore blocks of a bench” have been introduced. The set of geometrical parameters of the scattered ore bodies of the block and their mining and geological characteristics are presented as mining and geological models of the virtual CSOB of the bench. The developed models make it possible to establish patterns of changes in the mining and geological characteristics of complex ore blocks. Practical value. The developed mining and geological models of virtual complex structural blocks serve as the basis for creating mining and geological models of real complex ore blocks, models of CSOB in a blasted state. They will make it possible to develop a methodology for rationing losses and impoverishment of ores for real complex-structural blocks, to choose rational parameters for mining technologies for disparate ore bodies in specific mining and geological conditions, and to expand the use of waste-free, low-waste technologies in the development of complex-structural mineral deposits.

Age, Fluid Inclusion, and H–O–S–Pb Isotope Geochemistry of the Superlarge Huaaobaote Ag–Pb–Zn Deposit in the Southern Great Xing’an Range, NE China

The superlarge Huaaobaote Ag–Pb–Zn deposit is located on the western slope of the southern Great Xing’an Range (SGXR). The deposit includes four ore blocks, namely, ore blocks I, II, III, and V. Except for the no. I orebody of ore block I, which is hosted in the contact zone between the Carboniferous serpentinized harzburgite and the Permian siltstone, the other orebodies all occur as veins controlled by faults. The mineralization process at the deposit can be divided into four stages: cassiterite–arsenopyrite–pyrite–quartz stage (stage I), cassiterite–chalcopyrite–pyrite–freibergite–arsenopyrite–pyrrhotite–quartz stage (stage II), sphalerite–galena–jamesonite–stibnite–freibergite–silver mineral–quartz–calcite–chlorite stage (stage III), and argentite–pyrargyrite–pyrite–quartz–calcite (stage IV). Cassiterite U–Pb dating of the Huaaobaote deposit yielded ages of 136.3–134.3 Ma, indicating that the deposit formed in the Early Cretaceous period. Two types of fluid inclusions (FIs), including liquid-rich and gas-rich FIs, have been distinguished in the quartz vein and sphalerite. The homogenization temperature during the four stages gradually decreases, with temperatures of 302–340 °C for stage I, 267–304 °C for stage II, 186–273 °C for stage III, and 166–199 °C for stage IV, respectively. The salinity (wt% NaCl eqv.) at stages I, II, III, and IV is 3.7–6.6, 0.2–4.5, 0.2–5.0, and 0.4–1.6, respectively, indicating that the ore-forming fluid is characterized by low salinity. The δ18Owater and δD values of the ore-forming fluid range from −11.9‰ to 7.9‰ and −168‰ to −76‰, respectively, indicating that the ore-forming fluid was dominantly derived from a mixture of magmatic and meteoric water. The calculated δ34SH2S values range from −3.6‰ to 1.2‰, indicating that the sulfur mainly came from granitic magma. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of sulfides are in the ranges of 18.195–18.317, 15.509–15.667, and 37.965–38.475, respectively, implying that the ore-forming material was mainly derived from felsic magma that may be formed by the partial melting of orogenic materials. Fluid mixing, cooling, and immiscibility were the three primary mechanisms for mineral precipitation in the Huaaobaote deposit.

High-Precision and Rapid In Situ Ore Element Detection Based on Laser-Induced Breakdown Spectroscopy

In most cases, in situ online composition detection is highly desirable for the iron and steel industry. High-precision prediction of the iron content of an iron ore is quite difficult due to the complexity of ore composition. Herein, an online composition analysis system based on laser-induced breakdown spectroscopy (LIBS) is built up for real-time Fe concentration determination. Subsequently, using the support vector machine (SVM) combined with multivariate partial least-squares regression (PLSR) to establish a linear relationship between the spectral data and typical element content, the iron content in the standard ore tablet is used as the true value to train the model, and the iron content in the raw ore block is predicted, with an error of 1.6%. By studying the elemental distribution content of the raw ore with repeated laser ablation, it is found that the internal element content of the ore changes at different depths from the surface, and the element content quickly stabilizes. The results demonstrate that the method can accurately and effectively predict iron content online, allowing the application of online detection of industrial ore composition.

Substantiation of the optimal mining sequence of an ore deposit under conditions of high stress and low rock mass strength

Introduction. When choosing the mining sequences of an ore deposit, technological and organizational factors are mostly taken into account. However, when using systems with caving which involve considerable mined-out spaces, the geomechanical factor, which determines stability of mine workings, plays a determining role. The research objective is to reveal the dependence between the stability of the development and face-entry headings within the mined-out space influence zone and the excavation sequence of the isolated ore block under conditions of high stress and low ore and rock mass strength. Methods of research. Numerical modeling of the enclosing ore and rock mass secondary stressstrain state formation was carried out by the finite element method in the Rocscience RS3 program together with the original FEM software package. Modeling was performed for two variants of block excavation – from the center to the flanks and from one flank to the other along the strike. For the analysis, we proposed a coefficient representing the product of compressive stress concentration zones length by their existence duration. Results. Based on the analysis of the maximum stress concentration areas distribution in the marginal rock mass, as well as the time of their influence, the optimal sequence of actual mining was substantiated according to the factor of influence on bottom workings stress-strain state – from flank to flank along the strike. Conclusions. The obtained result confirms the model representations about the mechanism of rock mass stressed redistribution in the process of lens-shaped deposit excavation. The representations suggest that during mined-out space development along the strike, compressive stresses concentrate at its ends. However, the intensity of end sections expansion in the flank to flank variant is two times as high as in the center to flank variant. The duration of the stress concentration zones impact on the bottom workings is therefore less, which is indicated by the proposed coefficient.

Preliminary application of grade equivalent theory in a local section of a mine and economic estimation of the deposit

By introducing the practical application of grade equivalent theory in a copper -cobalt mine, it can show the maximum economic value of the individual ore block and the mine, maximize the comprehensive utilization of limited resources and contains positive significance for extending the service life of the mine. Briefly introducing the steps of Micromine software in the process of reserve estimation and the feasibility of displaying the economic value of individual ore blocks. Estimation of reserve can be completed objectively and scientifically by Micromine software, grade and economic value of ore blocks can be displayed in three-dimensional image.

ФОРМИРОВАНИЕ ВЫЕМОЧНЫХ БЛОКОВ ПРИ СЕЛЕКТИВНОЙ ОТРАБОТКЕ С УЧЕТОМ ПРОМЫШЛЕННОГО ТИПА ЗОЛОТОСОДЕРЖАЩИХ РУД НА ПРИМЕРЕ ОЛИМПИАДИНСКОГО МЕСТОРОЖДЕНИЯ

This article is devoted to the selective-combined mining of ore blocks of the Olimpiada deposit and displays its main disadvantages and advantages over the current technology. The main purpose of the work is to substantiate the effectiveness of the use of selective-combined mining of ore blocks. The method of carrying out the work is mathematical calculations and graphical modeling. According to the results of the research work, it is expedient to test the technology at the production site of the Olimpiada deposit. The results can be used in mining of gold deposits with various ore types.

High-Precision Geochronology of the Xiaojiayingzi Mo Skarn Deposit: Implications for Prolonged and Episodic Hydrothermal Pulses

Abstract The timescales and duration of ore-forming processes in skarn systems are not well constrained. To better understand this, we present high-precision chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb zircon and isotope dilution-negative-thermal ionization mass spectrometry (ID-N-TIMS) Re-Os molybdenite geochronology of the Xiaojiayingzi Mo skarn deposit (0.13 Mt Mo at 0.22 wt %), northeastern China. The Xiaojiayingzi deposit is related to an intrusive complex composed of gabbroic diorite, monzodiorite, and granite porphyry. Molybdenite mineralization occurred in two ore blocks, Xiaojiayingzi (0.11 Mt Mo) and Kangzhangzi (0.02 Mt Mo). In the Kangzhangzi ore block, Mo mineralization is concentrated in skarn adjacent to a deep-seated granite porphyry, with minor disseminated and quartz veinlet mineralization within the granite porphyry. In contrast, economic Mo mineralization in the Xiaojiayingzi ore block is concentrated in skarns located between the contact of steeply dipping monzodiorite and the Mesoproterozoic Wumishan Formation, with minor Mo mineralization found in quartz and endoskarn veins hosted in the monzodiorite. Skarn mineralization in both ore blocks converges downward into the mineralized granite porphyry. In the Kangzhangzi ore block, skarn is zoned from deep proximal dark red-brown garnet to shallow distal dark-green pyroxene. In the Xiaojiayingzi ore block, proximal skarn is garnet rich, whereas pyroxene increases away from the monzodiorite-Wumishan Formation contact. In addition, pyroxene becomes more Fe and Mn rich with distance from the intrusions; Pb, Zn, and Ag increase toward the top of the system; and Mo and Fe increase with depth. High-precision CA-ID-TIMS U-Pb zircon geochronology indicates the gabbroic diorite crystallized at 165.359 ± 0.028/0.052/0.18 Ma (uncertainties presented as analytical/+ tracer/+ decay constant uncertainties), with subsequent crystallization of the monzodiorite and granite porphyry at 165.361 ± 0.040/0.059/0.19 and 165.099 ± 0.026/0.051/0.18 Ma, respectively. High-precision ID-N-TIMS Re-Os molybdenite geochronology indicates molybdenite mineralization at Xiaojiayingzi occurred in at least three discrete magmatic-hydrothermal pulses (nominally between 165.48 ± 0.09–165.03 ± 0.13, 163.73 ± 0.09, and 163.11 ± 0.11 Ma). The first episode of molybdenite mineralization formed in exoskarns, endoskarns, and quartz veins and had a minimum duration of 450 ± 40 k.y., between 165.48 ± 0.09/0.68/0.85 and 165.03 ± 0.13/0.67/0.85 Ma. It is likely that skarn ore represents a composite series of mineralization events, more than the three events capable of identification within analytical uncertainty of these high-precision data. Finally, Re-Os dating of quartz Mo veins cutting the monzodiorite and granite porphyry indicates that some mineralization postdated the observed intrusions, between 163.73 ± 0.09/0.70/0.86 and 163.11 ± 0.11/0.70/0.86 Ma, interpreted to be the result of deeper, unobserved intrusions. Collectively, these ages indicate that protracted, pulsed Mo mineralization at the Xiaojiayingzi deposit occurred over a period of at least 2.4 m.y. These data suggest that individual magmatic and/or skarn garnet ages may significantly underestimate the full duration of mineralization. In addition, this study highlights that systematically identifying skarn deposits associated with multiphase intrusive systems may reveal targets for future exploration, as it may point to previously undiscovered mineral resources.

Geochronology, geochemistry, and Sr-Nd-Hf isotopic compositions of Permian granitoids from the South Altay, NW China: Implications for tungsten-copper skarn mineralization

The Bastielieke deposit is a W polymetallic skarn deposit discovered in the South Altay, Northwest China. W polymetallic mineralization mainly occurs within the contact zone between the Permian intrusions and the Kangbutiebao Formation (Fm.) metamorphic volcanic-sedimentary rocks. Permian granitoids associated with W (Cu) mineralization include several phases of granite: biotite granite (G1), monzogranite (G2) and two-mica monzogranite (G3) in L2 ore block, biotite monzogranite (G4) in L3 ore block. We obtained zircon U-Pb ages of G3, G4, and barren porphyritic monzogranite (G5) from Lamazhao granite of 275.0 Ma, 275.4 Ma, and 277.0 Ma, respectively. All samples from G3, G4, G5 show enrichment of SiO2, weakly peraluminous, enriched in light rare earth elements (LREE), and depleted in high field strength elements (HFSE). These Permian granitoids were mainly derived from mantle magma, and mixed with some lower crust components, although the Sr-Nb-Hf characteristics are slightly differences. G1, G2, and G4 were involvement of more mantle components than G3 and G5. G1 and G5 have experienced more obviously fractional crystallization than G2, G3, and G4, and G5 displays the highest fractionated degree. Moreover, G5 has the highest magmatic oxygen fugacity compared with G1, G2, G,3 and G4 according to variable △FMQ values (G1: −2.75 to 1.42, G2: −3.14 to 2.23, G3: −3.15 to 0.70, G4: −2.92 to 1.36, and G5: −1.63 to 2.82, respectively), as well as δEu values, δCe values, and Ce/Nd ratios. Thus, we proposed that tungsten skarn mineralization in the Bastielieke deposit area is mainly controlled by high fractional crystallization, and the contribution of magma source and oxidation state cannot be neglected. In addition, the copper could be offered by oxidized fluids exsolved from mafic magmas or Cu-bearing immiscible magmatic sulfides in copper-rich tungsten skarn system.

In Situ U-Pb Geochronology of Calcite from the World’s Largest Antimony Deposit at Xikuangshan, Southern China

The Xikuangshan antimony (Sb) deposit is the world’s largest known Sb deposit. Due to the lack of suitable minerals for reliable high-precision radiometric dating, it remains difficult to determine the exact age of Sb mineralization in this deposit. Here, we report the first LA-MC-ICP-MS U-Pb ages of syn-stibnite calcite from this deposit. The dating results indicate the presence of at least two stages of Sb mineralization in the Xikuangshan ore district. The calcite-stibnite veins in the Daocaowan ore block probably formed during the Paleocene (58.1 ± 0.9 Ma), representing an early stage of Sb mineralization, while the quartz-stibnite vein in the Feishuiyan ore block probably formed during the Eocene (50.4 ± 4.4 Ma, 50.4 ± 5.0 Ma, and 51.9 ± 1.6 Ma), representing a late stage of Sb mineralization. The new calcite U-Pb ages are significantly younger than the calcite Sm-Nd ages (124.1 ± 3.7 Ma, 155.5 ± 1.1 Ma) reported by previous researchers. We suggest that Sb mineralization of the South China antimony metallogenic belt may be related to tectono-thermal events during Paleogene, possibly linked to high heat flow during the subduction (ca. 60–40 Ma) of the Pacific Plate beneath the Eurasian Plate and/or the Indo–Asian Collision (began at ca. 61 Ma). The young in situ U-Pb ages of calcite challenge the idea of late Mesozoic Sb mineralization in the South China antimony metallogenic belt, suggesting the requirement for more high-precision dating studies.

Monitoring rock movement and—controlling ore loss and dilution associated with blasting at Geita and North Mara Gold mines, Tanzania

ABSTRACT We present findings from a blast movement monitoring research conducted as a part of mine to mill campaign at the Geita Gold Mine—and additional data from blast monitoring practices at North Mara Gold Mine. These include measurement of the blast-induced rock movement and perimeter translation after blast derived from a blast shot at Nyankanga pit (Geita Gold Mine) and three other shots at the Nyabirama pit (North Mara Gold Mine). Using Blast Movement Technology, 34 movement-monitoring balls installed in 13 blast-monitoring boreholes made possible estimation of the average vertical and horizontal ore movements in the studied blast shots. Recorded ore movement estimates average horizontal and vertical movements of 3.69 and 1.56 m, respectively, at the Nyabirama pit and average horizontal and vertical movements of 4.5 and 2.48 m, respectively, at the Nyankanga pit. Based on the estimated material movements, zones of ore losses and dilution are established and new dig lines are proposed from successful ore block translation in all blast shots.

Development and Testing of a Method to Estimate the Mineral Composition of Ore from Chemical Assays with a View toward Geometallurgy: Application to an Iron Ore Concentrator

For complex orebodies in which the valuable metal is carried by several minerals that respond differently to the concentration process, an ore block model should not be characterized solely with elemental assays, as this information is not sufficient to anticipate the mill performances. Data from an iron ore concentrator is used to demonstrate the idea. A method is then proposed to estimate the mineral contents of ore samples from elemental assays. The method can readily be extended to combine the estimation of the mineral contents in the feed of the mill with an estimation of the recovery of these minerals into the products of the concentrator. These mineral recoveries can subsequently be incorporated into a block model to predict the concentrator response to the processing of an ore block.

Metallogenic model of the Shuangjianzishan Ag-Pb-Zn district, Northeast China: Revealed from integrated geophysical investigation

The Shuangjianzishan deposit in Inner Mongolia is a typical Ag-Pb-Zn deposit of the southern Great Xing’an Range. Proven reserves of Ag, Pb, and Zn in this deposit have reached the scale of super-large deposits, with favorable metallogenic conditions, strong prospecting signs, and high metallogenic potential. This paper reports a study involving integrated geophysical methods, including controlled-source audio-frequency magnetotelluric, gravity, magnetic, and shallow-seismic-reflection methods, to determine the spatial distribution of ore-controlling structures and subsurface intrusive rock for a depth range of <2000 m in the Shuangjianzishan ore district. The objective of this study is to construct a metallogenic model of the ore district and provide a scientific basis for the exploration of similar deposits in the deep and surrounding regions. We used three-dimensional inversion for controlled-source audio-frequency magnetotelluric data based on the limited memory quasi-Newton algorithm, and three-dimensional physical-property inversion for the gravity and magnetic data to obtain information about the subsurface distribution of ore-controlling structures and intrusive rocks. Under seismic reflection results, regional geology, petrophysical properties, and borehole information, the geophysical investigation shows that the Dashizhai group, which contains the main ore-bearing strata in the ore district, is distributed within a depth range of <1239 m, and is thick in the Xinglongshan ore block and the eastern part of the Shuangjianzishan ore block. The mineralization is spatially associated with a fault system characterized by NE-, NW-, and N-trending faults. The magnetic and electrical models identify large, deep bodies of intrusive rock that are inferred to have been involved in mineralization, with local shallow emplacement of some intrusions. Combining the subsurface spatial distributions of ore-bearing strata, ore-controlling faults, and intrusive rock, we propose two different metallogenic models for the Shuangjianzishan ore district, which provide a scientific basis for further prospecting in the deep regions of the ore district and surrounding areas.

Multi-stage dumping sequence - a feasible waste management alternative for open pit mining

Abstract Waste management and environmental aspects are progressively gathering attention in the mining industry. Mine planners must deal with increasingly complex tasks to balance between ore block schedules, waste disposal, operational cost and environmental reclamation. The mine incomes are generally related to mining and processing of the ore, thus most optimization researches regarding strategic mining usually focus mainly on ore extraction. Nevertheless, waste sequencing and disposal play an important role given that, in several situations in open pit mining, waste volumes are generally larger than ore volumes and must be moved to reach the buried and deeper ore bodies. In some cases, a significant percentage of operational costs is represented by waste haulage and disposal. Thus a careful planning strategy must be considered to minimize unnecessary expenses. Selecting locations for waste dumps is also a challenge. Many operational and technical aspects must be considered, not to mention the increasingly limiting environmental constraints. This definition can be very time consuming, and if it is not properly studied, may negatively impact the mine operation during its lifetime. This article investigates a new approach for mine waste management called the multi-stage dumping sequence (MSDS), suggesting the use of temporary waste dumps along the way to the final dump destination. Although this method requires material re-handling, which is considered a paradigm in mine industry, it certainly provides additional time to design and permit the final waste dump site and, if well planned, might even result in profit increases by reducing haulage distances in the first years of operation.

S-Pb isotopes and tectono-geochemistry of the Lunong ore block, Yangla large Cu deposit, SW China: Implications for mineral exploration

The Yangla Cu deposit is the largest Cu skarn deposit in the Jinshajiang Suture Zone, central Sanjiang region, SW China, with a total reserve of 150 Mt Cu @ 1.03%. The skarn orebodies are strictly controlled by the stratum, structure, and granitoid geometry, which are layered, lenticular, and vein-like within the contact or fracture zone between the granitoid and wall-rocks. Mineralization can be divided into three stages, pre-ore stage andradite and diopside, syn-ore stage sulfides-quartz-calcite, and supergene stage malachite, limonite, and azurite. In this study, the S-Pb isotopes and trace elements compositions of ore-related samples were determined. The S isotopes of pyrite, chalcopyrite, and pyrrhotite contained δ34S = -1.97 to 0.66‰, −2.48 to −1.76‰, and −1.93 to −1.67‰, respectively. This suggests that the S of hydrothermal minerals derived from granitic magma systems. The Pb isotopes of six sulfides consist of Pb isotope ratios of 206Pb/204Pb = 18.319 to 18.478, 207Pb/204Pb = 15.645 to 15.737, and 208Pb/204Pb = 38.516 to 38.799, respectively. This suggests that the granitic magma and host rocks contributed most of the Pb values, whereas the Beiwu Formation basalts have the least contribution to Cu mineralization. Hydrothermal fluid boiling is thought to be the most effective mechanism for the ore sulfide precipitation in the Yangla Cu deposit. Cluster analysis (CA) of the trace elements in ore-related samples indicates that trace elements may be divided into three groups: (i) Zn, Cd, Pb, Mo, and Ag; (ii) Ba, Tl, Cr, rare earth elements (REE), Hf, Nb, V, Sc, Li, Cs, Be, Ga, Ta, Rb, Th, Sr, and Zr; and (iii) Cu, In, Bi, Ge, Co, W, Sn, and U. Principal component (PC) analysis of trace elements suggests that trace elements can be divided into five principal components: PC1: Ga, Rb, Cs, Th, Be, Li, Ta, Ba, V, Sc, Hf, ∑REE2, and Tl; PC2: In, Cu, Sn, Ge, Bi, U, Co2, and W; PC3: Zn, Cd, Pb, Ag, Nb, Mo, and Tl2; PC4: Ni, Co, and (-Sn2); and PC5: Zr, Sr, ∑REE, Ta2, Cr, and Nb2. Combined with the geological setting and prospecting marks, structure, lithology, hydrothermal alteration, and tectono-geochemistry characteristics suggest that the key prospecting target areas D-1, D-2, and D-3 should be the significant mineral exploration targets. This constrains the future mineral exploration associated with Cu at the depths of the Lunong ore block, Yangla Cu deposit.

Collaborative Mining Sequence Optimization for Multiple Stopes under Intensive Mining

The optimization of a mining sequence not only reduces stress concentration in surrounding rock but also prevents underground debris flows, significantly improving safety. Firstly, the 870–898 m level of the eastern mining area in the Tiaoshuihe phosphate mine was divided into 25 ore blocks, and six different mining sequences were designed for this area. Then, it was calculated that five ore blocks must be processed simultaneously to reach the annual production output. The distances between the five simultaneously mined ore blocks will inevitably affect the efficiency of the equipment for any scheme. So, a collaborative model considering both the area stability and production capacity was established by combining the distance between the centers of the five ore blocks as an index. Differences in stability, deformation, and plastic zone size between the schemes are compared. The calculation results show that a mining scheme with a convex stepped shape produces the best results. These results provide a general method for entropy‐based mining sequence optimization and an optimal solution for the Tiaoshuihe phosphate mine.

Planning of ore shotpileselective mining by the geoinformation technologies in the condition of the Ferrexpo Eristovo Mining

Purpose. Develop method for predicting the displacement of ore contours in the shotpile after the explosion to planning the ore raw materials selective mining at the development of iron ore quarries. Research methodology. Actual surface measurements were used to determine the loosening coefficient for individual sections of rock mass collapse. The analytical methods were used to calculate the planes of the face sections before and after the explosion. Determination of the predicted position of the contours of iron ore in the shotpile was performed by the method of graphical selection. The results. It is established that the loosening coefficient of the rock is variable in individual parts of the ore block and can be used to determine the predicted position of the ore contour. The main difference of proposed predicting methods consist in establish the expected position of contact of rocks and geological markers in the field, which will allow in the regular mode to control the development of the face by a pit geologist. Scientific novelty. The dependence of the predicted position of the ore contour in the rock mass shotpile on the method of actual survey of the pit surface "before" and "after" the explosion when performing geometric constructions is established. Determined that the proposed method of prediction allow to minimize costs in the form of insignificant organizational changes at planning observance of qualitative indicators, reduction of risks and dangers at geological works is provided, and also efficiency of works on short-term planning system in rock mass shotpile increases. Practical value. A method for determining the position of the ore contour in the rock mass shotpile has been developed. The possibility of using the predicted position of the ore contour for planning the selective mining of ore shotpile has been established. The expected economic effect of the proposed solutions is achieved by reducing the cost on processing rocks and low-grade ore when they fall on the crusher due to erroneous classification during the selective development of ore deposits.