Nuray Demirel

Landuse change detection in a surface coal mine area using multi-temporal high-resolution satellite images

Surface mining activities, exploitation of ore, and stripping and dumping of the overburden cause changes in the land cover and land use of a mine area. The area of land disturbance can be very large in the case of surface coal mining, due to the nature of the coal extraction process. Sustainable mining requires continuous monitoring of changes in land cover and land use induced by the mining activities. This is essentially important for identifying the long-term impacts of mining on theenvironment and on land cover in order to provide necessary mine closure andreclamation measures. In this sense, digital image classification provides apowerful tool for obtaining rigorous data, and reduces the cost of field measurements in time and money, particularly when dealing with large areas. Various remote sense data records and image classification techniques serve different features for numerous purposes. The selection of a suitable data and image classification method is significant for ensuring the effective use of information extracted from the satellite images, e.g. land-use classes. This paper proposes a methodology for identifying land-use change in surface coal mines using multi-temporal high-resolution satellite images. The methodology has been implemented for identifying, quantifying and analysing the spatial response of landscape to surface mining activities in the Goynuk, Bolu surface mine in Turkey, from 2004 to 2008. The methodology essentially entails (i) acquiring data, (ii) preprocessing the data, (iii)image classification using the maximum likelihood classification algorithm (iv) accuracy assessment and (v) change detection analysis depending on class-based approaches. The results show that the methodology can be utilised effectively in monitoring land-use change in surface coal mining areas. It also provides essential input for planning mine reclamation and closure activities.

Dragline dynamic modelling for efficient excavation

Overburden excavation is an integral component of the surface mine production chain. In large mines, the walking dragline is a dominant strip mining machine. Production engineers and operators must be guided by appropriate strategies to preserve the structural and operating performance of this equipment to justify its high capital investment. The dragline performance mainly depends on the spatial kinematics and dynamics of its front-end assembly. In this study, the authors developed the dynamic modelling of a dragline front-end assembly incorporating 2-D kinematics and bucket-formation interaction using numerical methods and dynamic simulation environment. Detailed analysis of the simulation results show that the maximum closure error from the model validation function is 4×10 E−8. The angular accelerations of the drag and hoist ropes are close to zero. The respective maximum drag, cutting and hoist forces are 100 kN, 200 kN and 75 kN. The results indicate machine health and longevity within the simulated conditions.

System Reliability Investigation of Draglines Using Fault Tree Analysis

Functionality and reliability of a system can be investigated by fault tree analysis (FTA) which is a structured and deductive procedure frequently exploited in complex systems. This analysis technique is related to Boolean algebra and probability theory in capable of qualifying and quantifying the system failure behavior by utilizing basic symbols and probabilistic relations. In this manner, internal and external causes of failures which come out in the working elements of draglines and their occurrence probabilities can be also analyzed by FTA. This research study examines and evaluates the connections between prior and superior failures in dragline components which eventuate in different sub-systems of dragline and their contributions to overall system reliability using FTA. The study utilizes real-time failure data of two different draglines gathered by the technical staff in a coal mine site owned by Turkish Coal Enterprise (TKI).

Optimisation of dragline inspection intervals with time-counter algorithm

Abstract This research study proposed a novel algorithm, called time-counter, to optimise inspection intervals of production systems. The developed algorithm was applied to two active draglines. The algorithm evaluated random uptime/downtime characteristics of the draglines and the planned dragline halts in the mine. Physical and random non-physical costs were included and annual maintenance cost minimisation was achieved. Dragline-1 and Dragline-2 inspection intervals were optimised as 232 and 184 h and their maintenance costs were reduced by 5.9 and 6.2% compared to the current interval, respectively. This study is the first initiative in cost-effective inspection interval optimisation of a mining machinery.

A cost-effective simulation algorithm for inspection interval optimization

A simulation algorithm was developed for optimization of inspection intervals.A data acquisition strategy was presented to be utilized in the algorithm.The model was simulated for two currently-operating draglines.Sensitivities of corrective and preventive costs to the intervals were evaluated. In machinery maintenance policies, regular inspection intervals should be specified in such a way that the cumulative of direct and indirect financial consequences of maintenance activities should be minimized while supporting the functional health of system components. This study aims to develop a simulation algorithm, called the time-counter, to optimize inspection intervals. In the algorithm, uptime and downtime behaviors of the system components and production losses in the corrective repairs are considered random values. Delay time concept is regarded when estimating failure detection periods and deciding on the required maintenance type. In addition, the developed model is applied to two active draglines and their inspection intervals are optimized as 232 and 184h for Dragline-1 and Dragline-2, respectively. The optimized values are observed to decrease the total maintenance costs by 5.9 and 6.2 percent for the given draglines, compared to the current interval of 160h. The main novelties of the study are that (i) the proposed concept which allows for simultaneous assessment of system components in an incremental time span has not been proposed in the literature when deciding on optimal inspection intervals, (ii) it is the first initiative in inspection optimization of a mining machinery system, and (iii) it uses real datasets on lifetime, repair time, and financial values that are rarely observed in maintenance studies.

Determination of Optimal Time Intervals for the Dragline Maintenance Using Probabilistic Approaches

Identifying and quantifying the components failures and their occurrence frequencies in the system offer a statistically notable data for the assessment of machine behavior as a whole. Increase in the complexity of system boosts the severity of the time-dependent availability since many components may lead to breakdown of the system in short to long term. Draglines are massive and complex systems which embody different combinations of motor and generators, structural elements and numerous components enabling to perform the earthmoving operation. In this sense, evaluating the time-varying functional importance and priority of the working parts, optimal strategies and time periods may be generated for the machine maintainability. This paper presents statistical evaluations to acquire optimal maintenance intervals for two draglines operated in Tuncbilek mine site owned by Turkish Coal Enterprise, associated with the reliability and availability issues.

Energy-Efficient Mine Ventilation Practices

Energy efficiency in mine ventilation, which is responsible for a substantial amount of total energy consumption, is of paramount concern in underground mining. Achieving energy-efficient mine ventilation practices is not only important for reducing total operating and energy costs but is also potentially the most effective means of reducing greenhouse gas emissions and environmental and occupational health and safety. This chapter presents a comprehensive review of the literature on energy-efficient mine ventilation practices and approaches to provide the current knowledge and research frontiers on energy efficiency in mine ventilation. Successful case studies, which resulted in efficiency increases, are also included to illustrate already existing energy efficiency alternatives and energy-saving opportunities. This review is expected to provide mining professionals a tool for improving current operations and achieving best practices.

Simulation of an Active Maintenance Policy: A Preliminary Study in Dragline Maintenance Optimization

Current maintenance policies for draglines do not cover enough preventive measures. Preventive maintenance for these systems is generally implemented via inspections and corrective activities unfortunately keep their priorities in dragline maintenance. Moreover, optimalities of both inspection intervals and their implementation durations are generally underestimated and they are determined via rough estimations. However, sustainability of a dragline operation and health of system components can be improved through maintenance optimization studies including preventive activities. This type of studies requires development of representative and comparable models to measure the effectiveness of optimization. In this sense, this paper presents the simulation of current maintenance policy of the draglines in Tuncbilek coal mine in Turkey, as a preliminary stage of the maintenance optimization study. The established policy aims to reveal 1-year halt profiles of the draglines via combining deterministic halts in operations and random lifetime characteristics of the system components.