Overburden Rocks Research Articles

Technological Ensuring of Production Competitiveness of Mining and Processing Enterprises

The significant reduction in the volume of production of concentrate at the Ordzhonikidzevsky mining and processing enterprise, which led to an increase in the cost of manganese ore and concentrate due to the increase in specific conditional-fixed costs for mining of overburden rocks by the bucket wheel complexes is analyzed. The dependencies between the cost of ore and concentrate on the volume of ore production and concentrate production are determined. As a result of the unevenness of production volumes and the unevenness of the volumes of shipment of production that do not coincide with each other, is substantiated that the mining and processing enterprise has to block certain amounts of funds, which leads to increased production costs.

Conditions and development case studies for mountainous deposits in Siberia

The article contains the materials on deposits development intensification under challenging climatic and mining conditions, including mountainous areas of Siberia. The exploitation case studies for mountainous deposits all over the world and in Russia have been described. The authors have been set out the factors impeding the development of such deposits, and the extent of mining and transportation equipment performance degradation is also indicated. There have been stated the characteristics and the description of one of the newly mountainous gold ore deposits in Siberia which is being developed at an altitude of 2684m. A number of specific factors concerning its development have also been introduced as well as the description of mining technologies engineered by Irkutsk National Research Technical University (IRNRTU) specialists. The depth and principal dimensions of the open pit together with the mining and transportation equipment and facilities have been justified. The prime cost analysis of mineral extraction has been made, which results showed the substantial growth in expenditures for the transportation of the overburden rocks and ores. In view of the above mentioned research, there appeared the necessity for the search of new and the enhancement of current transport vehicles and communications.

Use of overburden rocks from open-pit coal mines and waste coals of Western Siberia for ceramic brick production with a defect-free structure

The rational technology for the production of ceramic bricks with a defect-free structure from coal mining and processing wastes was developed. The results of comparison of physical and mechanical properties and the structure of ceramic bricks manufactured from overburden rocks and waste coal with traditional for semi-dry pressing mass preparation and according to the developed method are given. It was established that a homogeneous, defect-free brick texture obtained from overburden rocks of open-pit mines and waste coal improves the quality of ceramic wall materials produced by the method of compression molding by more than 1.5 times compared to the brick with a traditional mass preparation.

Особенности изменения гранулометрического состава мело-мергельных техногенных субстратов в районе Курской магнитной аномалии

As a result of mining of minerals by open method, formation of technogenic broken lands takes place. In the sediments of iron ore mines of Kursk magnetic anomaly (KMA), about 60-80 % of overburden rocks are sands and chalk. These rocks during mining and stripping operations is transported and stacked in piles. Chalk and chalk-marly rocks of KMA are extremely unfavorable on water-physical and agrochemical properties for growing woody and shrub vegetation. One of the ways to increase forest potential of edaphotopic layer of chalk and chalk-marly piles is formation of technogenic substrates by applying and blending chalk-marl with a variety of more fertile reclamation layers of varying thickness. Granulometric composition of technogenic substrates is an important genetic and isotopologues characteristic of habitat conditions of plants. The object of the study was reclaimed in 1974, chalk-marl phosphorite Schigrovsky mine, Kursk region. Particle size distribution was determined by pipette method by Kaczynski. Positive changes of granulometric composition of technogenic substrates on reclaimed area at the time of establishment and after 40 years of growth on them of forest plantations are shown. Application of drainage layer from 10 to 50 cm promotes the formation of lighter granulometric composition of technogenic soil. Over the 40 year period in the embodiments, when applying a layer of sandy deposits, technogenic substrate is transferred from the category of light clay to sandy loam, clay loam layer from the category of light clay to medium loam, and when applying the layer of humus soil in medium loam and sandy loam.

Syncline contribution to mountain peak building: examples from Western Zagros, Kurdistan Region, Northeastern Iraq

The current study focuses on roles of the synclines in building mountains of the Zagros Fold-Thrust Belt from Northeastern Iraq, Kurdistan Region. The studied area is located in the Imbricated Zone, which is a continuation of Simply Folded Zone of Iran. In some parts of this zone, the synclines contribute to building nearly half of the mountains and increase the relief contrast of the landscapes. The role of syncline in building mountains is opposite to its apparent intrinsic shape which is located in low land and normally forms synclinal valleys. In studied area, this phenomenon is observable in the areas that are complexly deformed, deeply exhumed, and predominately composed of the carbonate rocks. In these areas, exhumation and stream erosion have removed high thickness of overburden rocks and the tectonic stresses have crenulated carbonate rocks in the synclines. Due to these processes, these synclines are observable on the peak of the mountains now. The contribution of synclines in mountain building is related to three properties: the first is folding of synclines in confined condition (relative to anticlines) by which they have transformed to highly compact and stiff rocks. The second is accumulation of hydrothermal or meteoric water in the synclines due to its downward bending which aids precipitation of minerals and heals the possible tectonically and lithostatically induced fractures. The third is ductile deformation of synclines in confined and deeper level as compared to brittle deformation of anticlines in relatively shallower level and unconfined condition during deformation. Consequently, these factors result in an inversion of topography by which synclines are remained as mountains (high topography) above surface during exhumation while erosion removes anticlines. The result of this study is applicable for geological, geomorphological, and structural mapping in highly deformed and deeply exhumed terrains. The possible prediction of geomorphological position of synclines and anticlines on the mountain peaks and valley bottoms respectively is the applicable result in the above terrains.

Tracking changes in the specific storage of overburden rock during longwall coal mining

The hydraulic properties of geologic formations, such as specific storage and hydraulic conductivity, are known to vary spatially due to formation heterogeneity; however, they may also change temporally if the formation undergoes mechanical disturbance such as occurs during mining. Characterising changes in hydraulic properties is important for groundwater systems that are disturbed by mining. Conventional hydrogeological investigations rely on literature derived values or limited programs of field testing (e.g. pumping test) to define specific storage; but these approaches do not consider the change in compressibility that may occur due to mechanical disturbance. This paper presents, for the first time, direct in situ measurements of the changes in compressibility, and consequently specific storage, as a result of mechanical disturbance within geologic formations overlying underground mining operations. The in situ measurements of compressibility are derived in this study from the pore-pressure response to barometric loading or strains induced by earth tides. Even prior to disturbance, the compressibility obtained from in situ measurements was found to be an order of magnitude lower than that measured on core samples by unconfined strength test in the laboratory. The differences in compressibility for the intact formation are likely due to sample disturbance and the differences in strain level imposed by the field and laboratory methods. The increase in compressibility of the overburden rock varied with the location of the monitoring site relative to longwall extraction and the level of strain the formation sustained. The study found that quantifying the changes in compressibility, and consequently specific storage, as a result of mine-induced disturbance is critical to our understanding of subsidence, the extent of depressurization, and the impact that mining may have on regional groundwater flow systems.

An Image Analysis-Based Methodology for Chromite Exploration through Opto-Geometric Parameters; a Case Study in Faryab Area, SE of Iran

Traditional methods of chromite exploration are mostly based on geophysical techniques and drilling operations. They are expensive and time-consuming. Furthermore, they suffer from several shortcomings such as lack of sufficient geophysical density contrast. In order to overcome these drawbacks, the current research work is carried out to introduce a novel, automatic and opto-geometric image analysis (OGIA) technique for extracting the structural properties of chromite minerals using polished thin sections prepared from outcrops. Several images are taken from polished thick sections through a reflected-light microscope equipped with a digital camera. The images are processed in filtering and segmentation steps to extract the worthwhile information of chromite minerals. The directional density of chromite minerals, as a textural property, is studied in different inclinations, and the main trend of chromite growth is identified. Microscopic inclination of chromite veins can be generalized for exploring the macroscopic layers of chromite buried under either the surface quaternary alluvium or overburden rocks. The performance of the OGIA methodology is tested in a real case study, where several exploratory boreholes are drilled. The results obtained show that the microscopic investigation outlines through image analysis are in good agreement with the results obtained from interpretation of boreholes. The OGIA method represents a reliable map of the absence or existence of chromite ore deposits in different horizontal surfaces. Directing the exploration investigations toward more susceptible zones (potentials) and preventing from wasting time and money are the major contributions of the OGIA methodology. It leads to make an optimal managerial and economical decision.

Distinguishing the effect of diapir growth on magnetic fabrics of syn‐diapiric overburden rocks: Basque–Cantabrian basin, Northern Spain

AbstractAn analysis of Anisotropy of Magnetic Susceptibility was done on Aptian–Albian sediments from the Basque–Cantabrian basin. Samples were collected from 39 sites in the halokinetic sequences of the Bakio, Bermeo, Guernica and Mungia diapirs; 28 sites were sampled close to diapirs, and 11 sites were far from the diapir edges. The magnetic foliation is parallel to bedding, suggesting it reflects depositional and compaction processes, whereas the orientation of magnetic lineation varies. Far from the diapir edges, the magnetic lineation is interpreted as being related to the regional Pyrenean compression. Close to diapir edges, the observed behaviour shows that diapirs, predominantly formed by rigid ophites, have acted as buttresses, with shadow areas at their northern faces being protected from the Pyrenean compression. The high sensitivity of AMS makes it a very useful tool to distinguish deformation in halokinetic sequences related to diapir growth from that related to subsequent compression.

Modeling of the in situ state of stress in elastic layered rock subject to stress and strain-driven tectonic forces

Abstract. In this study we describe and compare eight different strategies to predict the depth variation of stress within a layered rock formation. This reveals the inherent uncertainties in stress prediction from elastic properties and stress measurements, as well as the geologic implications of the different models. The predictive strategies are based on well log data and in some cases on in situ stress measurements, combined with the weight of the overburden rock, the pore pressure, the depth variation in rock properties, and tectonic effects. We contrast and compare stresses predicted purely using theoretical models with those constrained by in situ measurements. We also explore the role of the applied boundary conditions that mimic two fundamental models of tectonic effects, namely the stress- or strain-driven models. In both models, layer-to-layer tectonic stress variations are added to initial predictions due to vertical variation in rock elasticity, consistent with natural observations, yet describe very different controlling mechanisms. Layer-to-layer stress variations are caused by either local elastic strain accommodation for the strain-driven model, or stress transfers for the stress-driven model. As a consequence, stress predictions can depend strongly on the implemented prediction philosophy and the underlying implicit and explicit assumptions, even for media with identical elastic parameters and stress measurements. This implies that stress predictions have large uncertainties, even if local measurements and boundary conditions are honored.

Justification of the Optimal Granulometric Composition of Crushed Rocks for Open-Pit Mine Road Surfacing

The specific weight of the open coal mining method in Kuzbass is constantly growing due to higher hazard and low profitability of the under-ground mining method. It is possible to reduce the cost of open-pit coal mining using overburden rock in constructing temporary pit roads. The purpose of the work is to justify the possibility of using overburden rock for the construction of temporary technological roads. To this end, we set the tasks to determine the rational granulometric composition of crushed rock, dependences of its unit weight, static elastic modulus, and ultimate shear resistance. This study justifies the most efficient granulometric composition of crushed rock based on theoretical studies of the optimal structure of granular materials, taking into account the probability theory of particle-particle packing, laboratory studies of the dependence of the unit weight and the static elastic modulus on the content of par-ticles of different sizes, and also the calculation of ultimate shear resistance of crushed rocks. As a result of the conducted studies, it has been established that the optimal granulometric composition of crushed rock, which at the same time ensures high values of unit weight, static elastic modulus and ultimate shear re-sistance, is achieved when the content of particles larger than half of the maximum is 40 to 55% and increases integrally with decreasing of the average particle diameter.

A new methodology for estimating field horizontal stress from microseismic focal mechanisms

The full stress state in a formation is characterized by the directions and magnitudes of the three principal stresses. It is common practice to take the vertical stress, ϭv, and the minimum and maximum horizontal stresses, ϭhmin and ϭHmax, as the principal stresses in unconventional reservoirs. Considering the relatively high depth of most unconventional reservoirs, which results in a very high vertical stress magnitude, this assumption holds true in most cases unless a geological feature such as a fault or fold changes the stresses locally. The magnitude of vertical stress can easily be determined by integrating the density of overburden rocks from density logs. A good estimate of ϭhmin magnitude can be obtained from well test results such as a mini-frac test or a diagnostic fracture injection test. The magnitude of ϭHmax, however, remains the most challenging stress component to determine.

Using of Wide Stopes in Coalless Zones Mined by Shovels and Backhoes

The examples of mining rock panels by different types of equipment are given in this paper. In such conditions, it is most expedient to use wide stopes to improve the productivity of equipment by reducing the time for auxiliary works. Also technological schemes of equipment operation in different conditions for several quarries of the Kuzbass are proposed. The coal-bearing zone is worked “layer by layer” with one or two benches or subbenches. The bottom of the quarry in this case is flat, without leaving “peak” of overburden rocks in the pillars. Cutting of the benches is carried out by trench with a wide bottom on the side of the roof of the coal bed and simultaneously working it with the same excavator or with setting up a additional excavator for coal mining operations. Interbeds are mined out with the use of wide stopes, often to the theirs entire horizontal width. Complex rock-and-coal blocks, including one-three coal beds, are also worked out by wide stopes.

Relationships between bright amplitudes in overburden rocks and leakage from underlying reservoirs on the Norwegian Continental Shelf

Identification of the locations where hydrocarbon traps leak is of significant practical importance, especially if the leakage controlled the present-day fluid contacts. We have investigated the fluid contacts of five structural traps offshore Norway that are dry or underfilled, and which have apparently had larger hydrocarbon columns in the past. The main focus of our work was to apply observations of bright amplitudes in overburden rocks in order to identify the most likely positions for vertical leakage, and to compare and contrast these observations from different parts of the Norwegian Continental Shelf. It was seen that bright amplitudes were present in overburden rocks above likely leakage locations in all of the investigated structures. The bright amplitudes line up along fault planes in some of the traps and, in other cases, are clustered along fault intersections. The leakage-related brights were only noted in parts of the overburden sequences, presumably because most of the overburden rocks did not have sufficient permeability to host the gas quantities that are needed for seismic imaging. We conclude that analyses of overburden brights above likely leakage locations can contribute to improved prediction of hydrocarbon–water contacts in the subsurface.

The use of seismic interpretations to discover and evaluate the new hydrocarbon prospects of Jurassic formations in JG field, NEAG concession, North Western Desert

Khatatba Formation is Middle Jurassic and act as a completely hydrocarbon system in the Northeast Abu Gharadig basin (NEAG) especially in JG field. This study is an attempt to discover and evaluate the new hydrocarbon prospects in Khatatba Formation and define the nature of the source rock in this investigation area. This study was done by interpreting forty (40) 3D seismic sections in addition eight wells drilled in this area. The geochemical reports of many samples from JG-1 well have been carried out to identify the maturity of the source rock. Four horizons are interpreted from this study and represented as two way time (TWT) and depth structure contour maps. These horizons are arranged from the top to the bottom as; top Masajid, top Khatatba, Top Kabrit and top lower Safa. The lower Safa sand member in JG1-ST well act as the main reservoir in Khatatba Formation that is characterized by high porosity 22%, low GR and SW is 12% that is led to the presence of oil zone. The lower Safa depth is ranges between 3120m in the southern part of the JG field and gradually increases toward the northwest to 3580m and to 3680m in the northeast part of the study area. Two main faults are interpreted in the NE-SW and in NW-SE directions and form a pattern of horst and graben blocks. Four and three-way dip structural closures (A, B, C and D) are representing the fruitful locations for high production and new prospect wells in the JG oil field. The Khatatba Formation consists of organic-rich shales, revealing mainly type II-III and type III kerogen and TOC content ranges from 2.7 to 4.98wt%. Vitrinite reflectance data indicate the mature to over mature stages of oil window for significant hydrocarbon generation. The overburden rocks of Masajid carbonates perform sufficient levels of thermal maturity for hydrocarbon generation.

Numerical analysis of longwall mining layout for a Wyoming Trona mine

At Solvay Mine, located in southwestern Wyoming, a subhorizontal trona seam is mined at depths of between 460 and 490m using mechanized room-and-pillar and longwall mining methods. The stratigraphy at the mine generally consists of horizontally laminated (i.e., bedded) sedimentary rocks comprised mostly of shales and sandstones with significantly contrasting mechanical properties. Most notably, a 43–82m-thick massive, brittle sandstone unit (Tower Sandstone), located approximately 100m above the mining level, has a tendency to promote stress arching within the overburden rock that can bridge over panel-scale mine instabilities and can lead to violent multi-panel collapse failure. One such violent collapse is the 5.1 magnitude seismic event due to a 1×2km multi-panel failure on February 3, 1995. It has proven difficult to account for this arching behavior with conventional mine design methods, such as the tributary area method. Therefore, over the past two decades or more, Solvay Mine has been utilizing numerical modeling techniques along with field instrumentation/monitoring as part of an integrated program to gain an enhanced understanding of the complex response of the overlying stratigraphy (i.e., arching) to mining. In 2005 and 2006, several longwall panels in the northwest and southeast areas of the mine were instrumented and monitored during mining. Two- and three-dimensional numerical models were developed and calibrated on the basis of the instrumentation data, and these models were then used for mine design verification (e.g., pillar and panel dimensions). This mining case study illustrates the complex excavation response due to the contrasts in stratigraphy at Solvay Mine and presents a numerical modeling study that captures the dominant aspects of these conditions.

Ground pressure and overlying strata structure for a repeated mining face of residual coal after room and pillar mining

To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis. The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting conditions of the repeated mining face were obtained. The results indicate that when the repeated mining face passes the residual pillars, the sudden instability causes fracturing in the main roof above the old goaf and forms an extra-large rock block above the mining face. A relatively stable “Voussoir beam” structure is formed after the advance fracturing of the main roof. When the repeated mining face passes the old goaf, as the large rock block revolves and touches gangue, the rock block will break secondarily under overburden rock loads. An example calculation was performed involving an integrated mine in Shanxi province, results showed that minimum working resistance values of support determined to be reasonable were respectively 11,412kN and 10,743kN when repeated mining face passed through residual pillar and goaf. On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.

Development of Methods of Determination and Recovery of Strategic Metals from Overburden Rocks in Coal Beds

The study covers the possibilities of analysis of overburden rocks in the south of the Far East - a new alternative source of strategic metals - by plasma spectrometry. A rational sample preparation procedure based on melting samples with lithium metaborate was used to define macro and trace elements (from major up to Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, Mo, Cd, Sn, Cs, Ba, Hf, Ta, W, Pb, Th, U and rare earths) from one weighed portion. The concentration of noble metals was defined by the neutron activation analysis. The distribution of commercial elements at various stages of overburden rock processing was studied. The development of new analytical and beneficiation methods allows to outline solutions for the issue of developing a technology of extraction of commercial elements from overburden rocks in coal beds.

Mechanical Activation of the Phosphorites (Karatau Pool) by using Organic-Mineral Co-Activators for Multicomponent Mineral Fertilizers

Deficiency of mineral fertilizers in the agricultural sector for last 15–20 years has decreased. Therefore with the purpose of partial reduction of this deficiency it was developed a new polycomponent NPK fertilizer, which contains humate and vermiculite. The given fertilizer has been produced from the natural South<br />Kazakhstan raw materials in accordance with an acid-free way. The given article contains the data and physicochemical properties of initial materials prepared on the basis of phosphorite fines of Zhanatas and Chulaktau deposits and sinter return. Characteristics of vermiculite and the internal overburden rocks formed at the mining brown coal on the Lenger deposit are represented. During the experimental research except the above-stated natural raw materials the following substances were used at manufacture of the polycomponent fertilizer: ammonia saltpeter, ammonium sulphate produced by the OJSC “Grodno-Azot”, halurgical potassium chloride produced by “Belaruskaliy” and potassium hydroxide, a chemical reagent of a grade “pure”. The given article contains the data about the chemical composition of initial raw materials and conditions of mechanical-chemical activation of the<br />initial materials at various values of components concentration, temperature and time at the polycomponent fertilizer manufacture. The plan and research results of phosphorite’s activation with the analysis of a disperse structure of nonactivated and activated Zhanatas phosphorite are represented. The determination of nonactivated and activated phosphorites specific surface was performed with use of a device PSH-8A according to the method based on the measurement of hydraulic resistance<br />of a powder material’s layer at filtration of an air low-pressure stream.

Processes and behaviors of block topple avalanches resulting from carbonate slope failures due to underground mining

Major rock landslides are the main type of geological hazards in the mountainous areas of southwestern China, in which failure modes and behaviors are compounded. In this study, field surveys, centrifuge modelling, and numerical simulations were utilized to analyze the failure process of a steep-dip and layered carbonate slope which was induced by underground goaf. These included gravitational bending, interlayer faulting, topple failure of the upper blocks due to underground mining, shearing through the underlying slide-resistant rocks, and catastrophic avalanches. It was concluded that the bending and compaction of the weak interbedded coal seam had occurred on the slope with the effects of gravity. The support for the overburden rocks was lost following the underground mining activities, which led to bedding separation and the generation of cracks. The upper blocks acted on blocks at the toe, and shear failure at the toe was initiated when the force along the joints exceeded the anti-shear strength, which gradually formed an intact failure surface. Then, a rock slide took place which transformed into a catastrophic rock avalanche. The failure process was validated using a FLAC3D simulation and centrifuge testing.

Mining Wastes in the Buryat Republic and Prospects of their Use

Case study of prospects of use of mining wastes in the Buryat Republic. High quality heavy weight concretes can be produced with the use of refuse from the tungsten and molybdenum refining plant. Brown coals, being one of overburden rocks of coal pits, are a good raw material for organic-mineral fertilizers, as well as for new sorbents. Ash and slag wastes generated by burning of solid fuels are widely used in production of construction materials. Separation of ashes into magnetic and non-magnetic, which allows to expand their application scope, is deemed promising.