On the origin and morphology of Z-shaped splitting of coal deposits (on the example of Eastern Donbass)

Статья посвящена выявлению морфологии и происхождения распространенных во многих угольных регионах мира уникальных углепородных структур – Z-образных расщеплений угольных залежей, впервые обнаруженных автором в Восточном Донбассе. Актуальность работыопределяется необходимостью разработки научных основ угленакопления для определения промышленной ценности и минерагенических перспектив территорий. Цель работы. Совершенствование теории угленакопления и первичного структурообразования в осадочных формациях в целом. Методы работы. Вещественно-структурный анализ пересекающихся геологических разрезов угленосной территории западной части Восточного Донбасса известными литолого-структурными методами, сопоставление выявленного Z-объекта с аналогичными структурами других угольных регионов и гипотез о формировании Z-расщеплений. Результаты работы. Обнаружено и исследовано первое в Восточном Донбассе Z-образное расщепление угольной залежи. Залежь k2н каменской свиты С25 каменноугольной системы у г. Красный Сулин асимметрична в разрезе и плане. Высота Z-объекта составляет первые десятки метров, площадь – многие десятки км2, протяженность с севера на юг превышает 20 км. Объект имеет угольные основание и свод в плане, сопряжение их угольным соединением. Z-образность объекта проявляется в субмеридиональных сечениях. Уникальны односторонняя – с запада – замкнутость соединения, наличие угольных пачек-перемычек, неразвившихся до соединения. Выявлена этапность формирования объекта. На конкретном примере определены условия развития Z-объектов: попеременное фронтальное поступление крупных сбалансированных порций в основном растительного или растительно-минерального материала на смежные участки территории с разных сторон с частичным заходом языка минеральных осадков на покрытый углематеринской массой один из них. Нарушение условий приводит к отклонению облика структуры от типовой либо прекращению ее образования. Механизм поступления материала – разливы рукавов палеодельты. Односторонняя замкнутость соединения в плане вызвана поступлением локальных потоков минерального материала. Ниша седиментации создана процессами тектонического относительного опускания смежных участков территории. Исследованная структура возникла в условиях сочетания тектонических и седиментационных предпосылок, главный вклад в ее формирование принадлежит деятельности палеорусел. В этой связи структура отнесена к аккумулятивному типу. Приведены примеры других Z-объектов. Z-структуры развиты на различных масштабных уровнях. Результаты исследований имеют значение для различных регионов угленакопления и решения общих вопросов седиментации. The article is dedicated to the identification of the morphology and origin of unique coal-bearing structures common in many coal regions of the world - Z-shaped splitting of coal deposits, first discovered by the author in the Eastern Donbass. The relevance of the work is determined by the need to develop the scientific foundations of coal accumulation to determine the industrial value and mineragenic prospects of the territories. Aim. Improvement of the theory of coal accumulation and primary structure formation in sedimentary formations in general. Methods. Material-structural analysis of intersecting geological sections of the coal-bearing territory of the western part of the Eastern Donbass using well-known lithological-structural methods, comparison of the identified Z-object with similar structures of other coal regions and hypotheses about the formation of Z-splits. Results. The first Z-shaped splitting of a coal deposit in the Eastern Donbas was discovered and investigated. The k2n deposit of the Kamenskaya suite C25 of the Carboniferous system near the town of Krasny Sulin is asymmetric in section and plan. The height of the Z-object is the first tens of meters, the area is many tens of km2, and the length from north to south is 20 km wide. The object has a coal base and a vault in plan, their conjugation with a carbon connection. The Z-shape of the object appears in submeridional sections. Unique is the one-sided - from the west - closed connection, the presence of coal bundles-bridges that did not develop before the connection. The stages in the formation of the object are revealed. On a specific example of the conditions for the development of Z-objects: the transverse frontal supply of large balanced portions of mainly plant or plant-mineral material in different parts of the territory from different mineral sediments with a partial entry of the tongue onto one of them covered with a source coal mass. Violation of the conditions leads to a deviation of the structure from the typical one or to the termination of its formation. The mechanism of material receipt is the spill of the paleodelta arms. One-sided closedness of the connection is in terms of providing local flows of mineral material. The sedimentation niche was created by the processes of tectonic relative subsidence of additional areas of the territory. The investigated structure arose under the conditions of a combination of tectonic and sedimentation prerequisites; the main contribution to its formation was the activity of the paleochannels. In this regard, the structure is classified as an accumulative type. Examples of other Z - objects are given. Z-structures are developed at various levels. Research results are of significance for different regions of coal accumulation and solution of general sedimentation issues.

Hydroacoustic study of the basin of Biryuzovoe Karyernoe lake (Korsakovsky district, Sakhalin Island)

For the first time, the paper presents the results of a detailed hydroacoustic study of the basin of the Biryuzovoe Karyernoe Lake (Novikovo village, Korsakovsky District, Sakhalin Region), formed after the conservation of the germaniferous coal deposit of the same name. On the basis of 12 hydroacoustic profiles, a detailed bathymetric scheme of the lake was compiled, its main morphometric parameters were calculated, and the morphological appearance was described. Preliminary conclusions have been made about the rates of sedimentation within the basin of the lake, and perspective points for monitoring the dynamics of bottom and slope sedimentation have been established. Based on the results of the chemical analysis of the lake waters, a conclusion was made on the prospects of its use for tourist and recreational purposes.

Methane Injury-Risk at the Russian Mines

Conditions are given concerning the development of methane-bearing coal seams in Russia, the chronology of injuries from explosions and outbreaks of methane-air mixtures at the Russian mines for a quarter of a century of developing coal seams at the nine deposits. The emergency was studied in 174 mine incidents, which occurred mainly at the mines of Kuzbass, Vorkuta coal deposit, Eastern Donbass, Chelyabinsk basin, Primorye and Sakhalin. Emergency objects - excavation areas, preparation faces and mined-out areas of the mines. The sources of ignition of methane-air mixture are drilling and blasting works in the faces, malfunctioning of electrical equipment, frictional sparking, endogenous fires, and smoking in the mines. The most injury-risk for methane are steep and steeply inclined mines. The need in the scientific substantiation of the decisions taken for prevention or reduction of the methane injury-risk at the mines is noted in the article. An important role is assigned to the choice of ways to achieve this goal considering the geological and mining conditions of the development of gas-bearing coal seams. As an example, the conditions, methods, and parameters of mining operations at the excavation areas of four mines are given, where occurred the catastrophic explosions of methane-air and methane-dust-air mixtures. The reasons are gross violations of safety rules during mining operations, incompetence of the mine engineering personnel, design, and control organizations in matters of safety during the underground work at the gas-hazardous mines with an extensive network of workings. This resulted in the death of miners and mine rescuers, the destruction of mine workings, equipment and devices, underground fires. Recommendations are given for reducing the level of methane injury-risk at the methane-rich mines.

Engineering and Geocryological Conditions of the Elginsky Deposit

The paper analyses engineering and geocryological conditions of the Elginsky coal deposit in terms of their impact on the development technology. Based on the analysis of the temperature and humidity conditions of rocks at the Elginsky deposit, it was established that the blasted rocks may re-freeze during the drilling and blasting stage, which is also confirmed by practical experience. Groundwater is present throughout the field, and the water content of the lower levels in the central part of the deposit may impede mining operations and require advance measures to lower the water table. Isomorphic maps of permafrost and glacial sediments in the northwestern part of the Elginsky coal field were created using the Mineframe software. Distribution patterns of these zones were established within the rock mass along the strike and in depth, which will make it possible to make reasonable adjustments to the field development technology.

Phase Planning for Open Pit Coal Mines through Nested Pit Generation and Dynamic Programming

This paper presents a phase planning method specially designed for coal deposits with nearly horizontal, bedded coal seams. The geology of this type of deposit is modeled into a column model, instead of a block model, to avoid coal-rock mixing in blocks. A nested pit generation algorithm is developed for producing a series of nested, least-strip ratio pits with a column model as its input. The algorithm completely overcomes the troublesome gap problem. Taking the least-strip ratio pits as possible phase states, a dynamic programming formulation is proposed to simultaneously optimize the number of phases, the phase-pits, and the ultimate pit, with an objective of maximizing the net present value. The merits and capability of the proposed method are demonstrated through a case study on a large coal deposit.

Density - A contentious issue in the evaluation and determination of Resources and Reserves in coal deposits

SYNOPSIS The initial evaluation of a coal deposit often raises uncertainty with regard to the accuracy of the reported Resources and Reserves. Reconciliation of results from mining and beneficiation with the original raw field data highlights deficiencies in original estimations. Credible Resource and Reserve estimation forms the basis on which an entire mining enterprise is motivated, initiated, funded, and established as a commercially viable proposition. This is required for sustainable extraction purposes and to support vital downstream industries such as power generation. Accurate determination of the density of the matrix of the material being evaluated is the key to credible values being obtained for Resources and Reserves. Losses between 15% and 20% of the Resource/Reserve can be realized if incorrect densities are applied to the tonnage derivation. Coal plies and particles have different relative densities, determined by the maceral composition, rank, and mineral and moisture content. These factors in turn contribute to the moisture, volatile matter, ash and carbon contents of a coal, which affect the overall density of the raw coal. More specifically, the relationship of ash to density and the effective matrix porosity were found to be critical in solving the greater majority of the problems in predictive calculations. A major deficiency identified is the inability to determine effective porosity, allowing absorption of adventitious moisture and altering the mass of the core sample. Although the volume of the raw material is altered through crushing, the change in mass after controlled air-drying, used with the original geometrical volume of the raw material, provides a credible air-dry density and allows the determination of the volumetric change related to effective porosity. This parameter can be validated through the evaluation of proximate ash using the ash-adjusted algorithm and a correction for the inherent moisture applied to also give a credible relative density value for an air-dried sample. A combination of theoretical, empirical, and reconciliatory evaluations of the available data, taken from the exploration phase through the mining process to final production, has shown that an integrated approach using the ash-adjusted density (AAD) methodology, in conjunction with other evaluative techniques, provides credible results with a considerably higher degree of accuracy than is currently possible. Keywords: coal, deposit evaluation, Resources, Reserves, density determination, ash-adjusted density.