The concern for mine safety continues as, regardless of significant measures taken by Directorate General of Mines Safety, Dhanbad to reduce the mining fatalities, the number of accidents remains high. Hazard identification and risk assessment is the process by which mine management identify hazards present in mines, analyses the risks and assess the risks associated with the hazards in order to determine and implement controls to maintain risk to an acceptable level. The aim of the paper is to identify and evaluate mine hazards and risks using different risk assessment techniques like Failure Mode and Effect Analysis(FMEA) and Workplace Risk Assessment and Control (WRAC) in order to improve mine safety.Read more
Mining has been observed as a high-risk industry for a long time. Accident statistics of Indian mines still shows very high rate of injuries and fatalities. The current death rate per 1000 person employed in coal and non-coal mines is 0.27 and 0.40 respectively. The serious injury rate in the current year is also very high and unacceptable. More disturbing is the fact that a few causes are repeated for fatal, non-fatal and serious accidents. Even though all the accidents are being investigated by different agencies and recommendations are made against them in each cases but still similar accidents are repeated. Therefore question mark is automatically put against the effectiveness of present-day investigation methodology. In this paper a few recent fatal accidents in Indian mines have been reviewed and identified causes and recommendations analyzed. The review highlights certain deficiencies in the current investigation methodology of India. The aim of this study is to analyse the investigation report to identify the gaps in the current investigation procedure (i.e. where are we?) and suggest for changing the focus of investigation from human error to system deficiency i.e. where do we go from here?
Keywords: Accident; accident investigation; coal mine; gap analysis; system error
Introduction of new technology and mechanization in underground mine working, driven by increasing need of sustainable usage of mineral resources, yields a chance to exploit untouched resources at greater depth. The design of drives, pillars and other underground structures in hard rockmass such as quartz-biotite-chlorite-schist presents a major challenge to geologists and engineers. The complex structure and the composition of these materials, resulting from the deposition and tectonic history, make it quite difficult to be classified as by the widely used rockmass classification system. The rockmass property of quartzbiotite- chlorite schist of Singhbhum thrust belt has been determined in laboratory of IIT (ISM) Dhanbad. The dynamic and static properties of the rockmass such as uniaxial compressive strength (UCS), modulus of elasticity (E), Poisson’s ratio (v) and RMR for this geological formation are determined and presented in this paper. The outcome of the study may be of useful for the design of underground excavation in the mineral rich zone, particularly, in Jaduguda area, East Singhbhum, India. The result of this study may be implemented for excavation design using numerical method (FEM), empirical method and analytical techniques.
Keywords: deep mining, geo-mining parameters, rockmass characterization, RMR, quartz-biotite-chlorite schist
The paper deals with innovative drilling and blasting techniques that are used for mineral extraction at the deposit located at Kadapa district, whose mineralization belongs to Vempalle formations of Papaghni group of Cuddapah Super Group and occurs in Vempalle carbonate rock, which forms the host rock to the mineralization, is essentially stratabound type. The host rock is characterized by impure, siliceous, phosphatic, dolomitic limestone with stromatolites, ripple marks and mud cracks thus also named as dolostone. This dolostone is sandwiched between lower massive limestone and upper shale. In relation to drilling and blasting works are described the main technological parameters of existing mining method; room and pillar mining with backfilling. For purpose of higher effectiveness of drilling and blasting, the works are executed by the emulsion explosives and the jack hammer 1.8m -2.4m drilling length), low profile (4.2m drilling length) and extra low profile (3.2m drilling length) electro-hydraulic drill jumbo by modern drilling pattern (modified burn cut) with single deck charging, double deck charging and without deck charging). The mentioned changes are analyzed through techno-economic analysis. The repeated calculation of drilling and blasting parameters for each individual type of faces (declines, advance strike drive, stope drive, ramp) made it possible for the blast design engineers, to provide various corrections in a new blasting plan for faster advance, resulting in higher productivity, reduced production drilling cost and reduced overall blasting cost per blast.Read more
During bord and pillar depillaring with caving in underground coal mining, strata pressure in the goaf roof keeps on mounting with increasing span of goaf. The strata pressure may propagate into the workings in the form of dynamic loading effects carrying potency of premature collapses. The loading effect can be revealed at goaf edges and influenced zone of workings by strata control instrumentation monitoring for convergence, load, local induced stress etc. Such strata pressure reaches to a peak and is termed as ultimate induced stress, before main fall occurs in the goaf. When overlying rock formations are strong enough, it may lead to caving constraints and propagation of strata movement into workings may occur in a larger way, requiring proper control measures. Principal control measures include, adequate support provisioning in the vulnerable places including at goaf edges, proper methodology of extraction, artificial induced failure of goaf roof etc., which are possible, only when the peak strata movement is predicted in advance of roof fall. The objective of the study is to analyse the strata behaviour during peak loading hours and prediction of ultimate strata movement during extraction under strong roof conditions, using the already developed model of the author, ‘Roof Fall Warning Index’.
Keywords: Underground coal mining, strata pressure, dynamic loading effect and strata movement
The ore grade estimation requires accurate prediction of the grade at location from limited borehole information. It plays the dominant role in the decision-making process for investment and development of various mining projects and hence become an important and crucial stage.This paper evaluates the application of multi-layer perceptron neural network (MLP NN) architecture to improve the predictability in grade estimation from west coast limestone deposit, Chandrapur district, Maharashtra. The spatial variability of lithological information is incorporated as secondary information in the model for grade estimation. In this investigation the three dimensional spatial coordinates along with four underlying lithological units are taken as input variables and, the four grade attribute of limestone deposit such as CaO, Al2O3, Fe2O3, and SiO2 are taken as the output variable. The comparative analysis of these models have been carried out and the results obtained, are validated with geostatistical method ordinary Kriging (OK). The observed value of various performance criteria viz. regression coefficient and mean square error revealed that the MLP NN performed well as compared to OK in terms of generalization and predictability of ore grades.
Keywords: Grade estimation, multi-layer perceptron neural network (MLP NN), ordinary Kriging (OK), spatial uncertainty