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Surface miner was introduced for coal extraction at Lakhanpur open cast project of Mahanadi Coalfields Limited in 1999 for the first time and owing to its success and benefits it offered like elimination of drilling and blasting, smooth and stable high wall, selective mining for quality control and uniform output fragment size (-100mm) etc. it was adopted in many open cast coal mines and now has become a disruptive mass production technology for coal mining in India. In terms of coal resources in the country, Odisha stands first with 88.104 BT resources but the coal seams in Odisha are characterized by its high ash content and interlaced dirt bands (10 cm to 1.5 m) often termed as rejects. For maintaining coal quality, these dirt bands predominantly of sandstone and shale are also cut by surface miners and are segregated at the time of loading and transported to reject dumps or overburden dumps. These dirt bands have a significant impact on the performance of surface miners and must be taken into account during their selection. The authors, based on the intensive field study undertaken at different opencast coal mines in Odisha highlighted the impact of in-seam dirt bands in coal seams on the performance indicators of surface miners which are normalized production rate, diesel and pick consumption for cutting 1000te of material in this paper. Pick consumption was found to vary linearly with the quantum of abrasive material cut. Empirical relations for estimating monthly normalized production, diesel consumption, and pick consumption of surface miners operating in coal seams with intermittent dirt bands with a coefficient of determination (R2) of 0.74, 0.84, and 0.73 respectively were also developed. The developed relations were validated with the field data and the % error was found to be within +20%. This study helps the coal mining companies in the selection of suitable surface miners for achieving targeted production and also for planning inventory of picks and diesel during its operation. [ABSTRACT FROM AUTHOR]

Open-pit coal mining accounts for 93% of India's total coal production, playing a significant role in meeting the nation's substantial energy needs. The success of an open-pit mine hinges on maintaining the steepest and deepest slopes that remain stable over the mine's lifespan. However, slope failure is a complex issue influenced by numerous factors. In the context of openpit coal mines, the rise side highwall involves cutting through a rock mass containing various elements like an unconsolidated weathered mantle of sandstone, sandy clay, clay, carbonaceous shale and coal. Some opencast mines within the Godavari Valley Coal Field (GVCF), India have encountered significant pit slope failures. This paper uses a numerical modelling approach aimed at effectively assessing the stability of the rise side highwall, leveraging available geotechnical data from one of GVCF's largest opencast coal mines. The research investigates the impact of seven detrimental factors on slope stability, including dynamic loading due to blasting, employing a methodical One-Factor-At-A-Time (OFAT) approach. The study utilises Rocscience Phase2 version 9.0, a Finite Element Method (FEM) based numerical modelling software to gauge the sensitivity of each factor on the Factor of Safety (FoS). The numerical modelling results indicate that there is a linear decrease in FoS corresponding to the reduction in cohesion and an exponential increase in the FoS as the angle of internal friction rises. Furthermore, the analysis reveals significant impacts on the FoS due to groundwater and seismic loading from the blasting. This approach aims to comprehensively analyse and understand the intricacies of slope stability in the specific context of open-pit coal mining. [ABSTRACT FROM AUTHOR]

Depillaring by conventional techniques created many irregular shaped pillars, mainly located at shallow depths in different coalfields of India. Continuous Miner Technology (CMT) has been introduced to extract these coal pillars scientifically with safety and productivity with greater depth. Leaving a proper sized rib or snook is a legal requirement as it decides the efficiency and safety of the pillar. However, CMT of square/rectangular shaped pillars created irregular shaped rib and snook. With the conventional empirical formula it is difficult to estimate the strength of such ribs or snooks. These ribs or snooks should be of sufficient size to protect the adjacent slicing operation and junction as well as they should fail in a controlled manner when machines shift inside the extraction. Field studies of different mines found several factors affecting the design of rib or snook. They are various types of induced stress, geological disturbances, manner of extraction etc. Proper assessment of the performance of different sizes and shapes of ribs and snooks in the field is complex due to the problematic underground mining environment for depillaring. For successful operation of the CMT required to study every depending parameter scientifically. Therefore, a numerical model is conducted to estimate the factor of safety of rib and snook to calculate the rib and snook stability. Results of field and simulation studies are presented and discussed in this paper to determine the rib's stability in the continuous miner panel to create a safe environment for the men and machines. [ABSTRACT FROM AUTHOR]

Coal is still a staple energy resource in India meeting over 50% of its energy requirement. Eastern Indian states are particularly blessed with coal with vast availability in Odisha, Jharkhand, West Bengal and Chhattisgarh. It has some major coalfields like Jharia, East and West Bokaro, Raniganj, Barakar, Karnpura, Ib valley, Talcher and Korba coalfields to name a few. Incidentally the land undulations, rivers, forest and geography render a climate range that supports soil fertility with rich promises of agricultural harvest. An additional booty of highly rich ecosystem services and aesthetics are offered due to pristine forest in the region. A balance has always been in the wish list that may bring inclusion and sustainability but so far been lurking. Mining companies must encompass sustainability as its key governing principle in corporate philosophy. Sustainability encompasses harmony in dimensions of society, economy and ecology (SEE) to be incorporated in its entire operating practices (exploration to mine closure) in order to realize sustainable and inclusive growth. The essence of the paper can be summarized by quoting a shloka from Atharva Veda: "What of thee, I dig out Let that quickly grow over Let me not hit, thy vitals, thy heart!". In order to meet ever evolving aspirations of growing population, adaptation to practices of sustainable agriculture appears a must. Meeting the need of food, feed, fiber and fuel for human and live-stocks, maintaining the sustainable balance among its various parameters extending to land, water, soil, biodiversity, agro biodiversity and agro ecosystem appears sine-qua-non. In totality, it constitutes the base of entire gamut of natural resources. [ABSTRACT FROM AUTHOR]

Subsidence is the motion of a surface as it shifts downward relative to a datum caused by various manmade and natural activities. Most of the coalfields of India are facing significant subsidence problem due to underground coal mining. Extraction of thick seams at shallow depths has damaged the ground surface in the form of subsidence and formation of cracks reaching up to the surface, enhancing the chances of spontaneous heating of coal seams leading to mine fires. A proposed alignment of Giridih-Koderma broad gauge (BG) railway track neat Giridih Railway station lies above old, abandoned underground coal mine workings. This site lies at the southern fringe of the Giridih coalfield (also known as Karharbari formation). The mining was commenced in 1871, first by the Bengal Coal Co., then by the National Coal Development Corporation (NCDC) and lastly by the East India Railway and it was closed in 1936. Bord and pillar mining method was practiced in this mine and it was closed without any de-pillaring and backfilling. The present undulating topography depicts the existence of subsidence at different parts of the coalfield. Total 117 boreholes were drilled for investigating the ground condition and to evaluate ground stability for laying railway tracks to run MBG (1987) train load along the proposed layout above the basin. The paper deals with the causes and subsidence potentiality over old abandoned underground coal mines neat Giridih town of Karharbari formation. [ABSTRACT FROM AUTHOR]

The interest to develop a benign mining under least environmental impact in the coal mining sector with due regard to safety, hassled to the birth of Talabira mining operation -first blast-free opencast coal mine in India and first private captive coal mining in Orissa through ripper dozer and surface miner technology. The mine is situated in the IB valley coalfields, odisha. The mine is owned by Hindalco Industries Ltd and it caters to the needs of captive power plant located at Hirakud, Sambalpur, Odisha. The mine is surrounded in south and west side by backwaters of Hirakud dam. As the coal mining takes place below the highest flood level of hirakud reservoir water, blasting is prohibited in the mine. The mine has adopted innovative ripper dozer-surface mining technology for ripping of sand stone parting and other hard intrabands, surface miner is being used for cutting of coal; hence totally avoiding the blasting. The mine has started production in September 2003. Due to initial apprehensions about the success of technology as well as less coal requirement of the power plant, mine started with 0.4Mtpa capacity. With expansion of power plant mine capacity also expanded in stages from 0.4 Mtpa to 1.5 Mtpa and now the capacity is 3.0 Mtpa. Till date cumulative production achieved from the mine is 13.65 Mt. The paper deals in the experiences of blast free coal mining in the mine and how the increased confidence in the technology has led to increase in production and productivity as well as mining of thin & thick seam at the mine. [ABSTRACT FROM AUTHOR]