Design of open pit coal mine slopes: An integrated approach

ABSTRACT

Many of the coal deposits of Western Canada exhibit intensely folded and/or faulted strata. Geological evaluation of such deposits is often difficult and uncertain, and interpretations are subject to significant modifications throughout the exploration, development and mining phases. Design and excavation of open pit slopes under such conditions can present a variety of operational and slope stability problems. Slope design approaches and excavation procedures which are flexible and capable of adapting to changing conditions are essential for rational slope development

This paper examines the problems associated with open pit coal mine slope design in complex geologic environments. A systematic approach to slope design which incorporates engineering geology assessments, slope stability analyses, economic evaluations and mining operational constraints is presented:, Slope design concepts which utilize a variety of slope development techniques, Including benching and artificial support are developed. The design process continues throughout the mining phase in an iterative cycle whereby slope designs are prepared and implemented, remedial measures are applied, existing slopes are documented and evaluated, and slope design concepts and subsequent slope designs are updated and modified as necessary.     

A stochastic optimization approach to mine truck allocation

Abstract

In the mining industry, truck assignment is an important and complex process and an optimal truck allocation can result in significant savings. In this paper, a truck allocation model is formulated using a chance-constrained, stochastic optimization approach that can accommodate uncertain parameters such as truckload and cycle time. A real-time hauling framework, which consists of the chance-constrained optimization model and a model updater, is developed to compensate for changes in the uncertain key operating parameters. The use of the model updater helps the truck allocation system to adapt to random operational changes. The effectiveness of the chance-constrained approach in dealing with uncertain process parameters, when coupled with model updating, is shown to be a viable implementation framework in the dispatching operation.     

Improving mine-to-mill by data warehousing and data mining

ABSTRACT

Mining is an interdisciplinary industry that utilises equipment and technology intensively in daily operations. Mine-to-Mill is considered as a key concept for metal mining recently. Impact of underperformed basic upstream operations such as drilling and blasting will sustain this inefficiency in downstream processes, such as mineral processing. Data provided for each of these operations from software and hardware utilised on field reached a level where advanced data analytics becomes applicable. Data warehousing and data mining are alternative tools that rely on a robust data structure. This study gives insight into a data-driven framework for modern mines and presents a data mining implementation on real-time mining-related data for prediction of blasting performance. Random forest and adaptive boosting algorithm were utilised on an integrated data warehouse to discover major operational parameters for efficient blasting. The implementation on site improved the performance of drilling and blasting. The variables highlighted as important by random forest and adaptive boosting algorithm directed the experts of mine-to-mill on site to focus on the close control and detailed analysis of certain drilling- and blasting-related parameters.     

A robust mixed integer linear programming framework for underground cut-and-fill mining production scheduling

ABSTRACT

A review of general optimization studies that have been proposed for underground mining shows that previous works lack flexibility, operability and practicality in relation to cut-and-fill mining production scheduling. This paper presents a robust mixed integer linear programming (MILP) formulation for underground cut-and-fill mining. The objective function of the model is to maximize the net present value (NPV) of the operation while meeting all mining and processing operational and technical constraints. The MILP model features stope development and extraction sequencing constraints, mining and processing tonnage fluctuation constraints, and extraction duration and active levels control constraints. These features make the model more practical and expandable. The MILP model is verified and validated with two case studies from an existing mine and the results are compared with the actual mining strategy. The comparison shows a 9% to 17% improved NPV in both case studies resulting from mining higher grades and processing less tonnes thereby generating a better cash flow.     

Selecting Environmental Water Tracers to Understand Groundwater around Mines: Opportunities and Limitations

Underground mining operations have the potential to alter groundwater systems and facilitate hydraulic connections between surface water and groundwater. The nature and degree of these interactions need to be evaluated to identify mining risks to surrounding water resources and to predict potential operational effects and environmental impacts, such as hydraulic stress on local surface waters. Environmental water tracers (EWTs) are commonly used to study such interactions in mine water and hydrogeological studies. However, the opportunities presented by EWTs could be more widely utilised to benefit the mining industry and the environment. Some of the challenges faced include the lack of practical frameworks, the need for more examples of EWTs applications in mining, and the possibility of complex interpretation of tracer results. This paper reviews previous studies that have applied EWTs in groundwater systems within or near mine sites, mostly from Australia, China, and India. The EWTs used in these studies include water quality parameters, major ions, stable isotopes, radioisotopes, and dissolved gases. The opportunities of applying multiple EWTs to identify water sources, mixing, and determine recharge rates and groundwater residence times are discussed. Limitations of different EWTs in terms of their capabilities, reliability, cost of analysis, effort, and processing times are reviewed. Steps for selecting suitable EWTs for specific mine hydrogeology assessments should be commensurate with the risks. Finally, this paper provides an overview of suitable EWTs that will be a useful contribution to appropriate water resource management decisions around mines.

     

Implementation of a goal programming framework for production and dyke material planning

Abstract

In oil sands mining, due to limitations in lease areas, the pit phase development and the construction of in-pit and ex-pit tailings containment dykes are carried out simultaneously. The primary research objectives are to formulate, implement and verify a theoretical optimisation framework based on Mixed Integer Linear Goal Programming (MILGP) formulations to simultaneously schedule production and dyke material. The numerical modelling approach used in implementing the framework is presented. A case study was compared with industry standard software, Whittle. In contrast, the MILGP model scheduled for more ore in the early years contributing to an increased net present value.     

Opportunities for Sustainable Mining Pit Lakes in Australia

Abstract.  Due to operational and regulatory practicalities, pit lakes will continue to be common legacies of mine lease relinquishments. Unplanned or inappropriate management of these geographical features can lead to both short- and long-term liability to mining companies, local communities, and the nearby environment during mining operations or after lease relinquishment. However, the potential for pit lakes to provide benefit to companies, communities, and the environment is frequently unrecognised and yet may be a vital contribution to the sustainability of the open-cut mining industry. Sustainable pit lake management aims to minimise short and long term pit lake liabilities and maximise short and long term pit lake opportunities. Improved remediation technologies are offering more avenues for pit lakes resource exploitation than ever before, at the same time mining companies, local communities, and regulatory authorities are becoming more aware of the benefit these resources can offer.     

Mine system availability concepts

ABSTRACT

During the last few years, there has been a marked tendency in mining industry to adopt complex and sophisticated technology to make mining operations economically viable. The concepts of integrated operating systems are being gradually introduced with increasing pace of automation in mines. This paper discusses the concepts and various forms of system availabilities which can be used by mine engineers and managers for controlling the system performance. Examples are given to show the differences between these availabilities. The concept of availability target setting is also introduced in brief.     

Comparison of tripper-spreader combinations

ABSTRACT

In future, the volume of overburden to be dumped will further increase as mining operations have to go down to greater and greater depths in order to expose the mineral deposits to be extracted in open pit mining.

For this reason, the selection of the correct spreading system is becoming increasingly important. Thus, an optimal tripper-spreader combination has to be selected with regard to the actual dumping procedure and the geometry of the dump crosssection.

In order to guarantee economical mining of mineral deposits, despite the increasing costs of overburden removal, the machine system selected must also be examined with regard to its costs, operational safety and availability.

Because of the complexity of the subject matter and the limited size of this paper, this is a contribution only to give a brief overview of the machines more commonly combined as systems and to present their most significant features in terms of type, method of operation, mass and cost effectiveness.     

In-pit crushing and conveying technology in open-pit mining operations: a literature review and research agenda

ABSTRACT

In-Pit Crushing and Conveying (IPCC) systems are receiving more attention today due to current characteristics of open-pit mining operations and what is expected to occur in the future. Today, it has become more necessary than ever to reduce the cost of truck haulage, which accounts for roughly half the operating costs of mining operation. Trucking costs can be significantly reduced by bringing the crushers inside the pits. The present paper aims to provide a comprehensive literature review of all aspects of technical, economic and sustainable development of in-pit crushing systems along with a statistical analysis of the systems since 1956 to the present. The paper also presents the scope of future research and examines defects and flaws in the design and planning tasks that limit the IPCC system’s applications. Transition time from a pure-truck system to an alternative IPCC system, necessity of integration of production plan and IPCC plan, ultimate pit limit for fully mobile systems, capacity optimization, IPCC’s plan for waste material and optimum conveyor exit scheme are introduced as the main open problems that are worthy of future study.     

Valuing the unknown: could the real options have redeemed the ailing Western Australian junior iron ore operations in 2013–2016 iron price crash

ABSTRACT

The inability of existing analytical models to accurately predict future events has, at times, led to the economic failure of mining operations whose financial viabilities were determined based on static assumptions, leaving operational managers with little room to make future decisions. Therefore, the application of a robust decision-making tool, such as Real Options (RO) can minimise losses and more accurately express uncertainty. This paper has considered a stochastic simulation to analyse ROs for a real case iron ore mine, which closed in April 2016. In comparing the net present value from the traditional discounted cash flow (DCF) method to delay, to abandon the operations and to stage the investment options, the ROs method increased the project value by between 56% and 195% depending on the volatility. As a new contribution, a managerial flexibility domain map is proposed in this paper. Thus, flexibility in mining operations creates agility, increases value and mitigates financial losses.     

Benchmarking haulroad design standards to reduce transportation accidents

Abstract

Transport and tramming operations on South African mines are an area of considerable accident risk. In the context of surface mining, 74 percent of such accidents were associated with ore transfer by haul truck and service vehicle operations. However, the extent to which haul road design and operation activities impact on the overall safety of transport operations in mining was previously unclear, as was the status of road design activities for the various types of mining encountered

This paper presents some findings from die Safety in Mines Research Advisory Committee research project OTH308 which examined the role of haul road design in transportation accidents. The objective of research was to determine whether a relationship existed between haul road design, construction and maintenance practices and accidents. In the case of surface mines, the objective was addressed through an assessment of transportation accidents and incidents, together with an evaluation of formal haul road design activities and associated safety critical defects and accident potentials for the various classes of surface mines studied

It was concluded that whilst the overall contribution to transportation accidents derived from inadequate road design alone was small, low tonnage surface mining operations exhibited higher accident frequency rates than the industry average. Furthermore, there was clear evidence to suggest that there was no formal recognition of road design and management in transportation management, especially in the case of smaller surface mining and quarrying operations. To improve awareness of the role of good design in reducing transportation accidents, a mine haul road safety audit system was developed. A mine haul road safety audit system is described and recommended as a means to attaining a reduction in transportation accidents through the structured recognition and assessment of haulage hazards and the application of optimally safe designs for mine haul roads.     

Development of risk-informed,performance-based asset management in mining

This paper discusses possibilities of developing a holistic risk-informed, performance-based asset management in mining (RIPBAMM). This process would consist of modelling and probabilistic quantification regarding decision support performance indicators. It assists decision-makers in determining not only which mine improvement investment options should be implemented, but also how to prioritize resources for their implementation based on their predicted levels of profitability. The RIPBAMM approach will complement and integrate existing main mine activities such as exploration, ore body modelling, mine design, planning and scheduling, exploitation (all the phases of the mine life), mineral treatment, cost and market model, operational safety and health, environmental issues, mining equipment reliability and maintenance process, equipment selection model, security, etc. RIPBAMM will involve an integrated assessment of dominant influence factors and performance measures related to mining operations. This process is intended to maximize both net present value (NPV) of the mine, and long-term profitability through a continuous support to a decision-making process. It may be particularly useful while optimizing several mine sites belonging to the same mining company. Initial risk informed asset management (RIAM) applications have been initially developed for the nuclear power industry. Afterwards, this process has been adapted to provide decision-making support to other types of power stations, complex facilities (usually capital-intensive), or even groups of such facilities across a wide variety of industries. RIPBAMM is introducing numerous (stochastic) models and supporting performance metrics that can ultimately be employed in order to support decisions that affect the allocation and management of mine resources (i.e. financial support, employment, scheduling, etc.).     

Land reclamation and restoration of natural ecosystem: A case study from opencast mines of North Eastern Coalfields of India

ABSTRACT

Coal mining authorities of North Eastern Coalfields have been facing serious challenges of reclamation of the mine lands and restoration of natural ecosystem as a result of opencast mining operations on densely forested hills In Assam. Having regard to present operations, locations of opencast mining and particularly importance of Assam Coal and its potential use In steel industry and environmental restoration/ reclamation treasures taken by the NEC authorities, it is justified to continue present opencast mining cperations. This case study attenpts to present sincere efforts being carried out in environmental restoration by NEC authorities. Background of mining, geology, climate and ecology in the region and also Impacts of opencast mining operations have been described in this paper. Slope stability and aspects of control of soil wash off are also dealt with particularly civil engineering and mechanical measures such as terracing. bamboo barricading in the slopes, stone-barriers at the toe of dumps. revetment and retaining walls. Check-dams in the channels and valleys and gully-plugging etc. Vegetation restoration through plantation of various selected species Including turfing/transplantation etc are also presented. Solt quality aspects of In-situ soils dealt with. Vegetation results obtained have been quite successful with survival of diverse species at the rate of over 90%. The aspects of restoration of natural ecosystem restoration in this region of subtropical climate have also been described.     

Development of an air attenuation model for noise prediction in surface mines and quarries

ABSTRACT

Surface mining and quarrying produces a complex noise field. The noise generated by mining operations changes with time and is affected by the changing meteorological conditions in situ. Theoretical research on the attenuation of noise in air has formed the basis for the development of an air attenuation model. The methodology developed by the authors accounts for the prevailing temperature and relative humidity conditions in the area. The model also includes the evaluation of ray path curvature directly from long-term experimental wind velocity and temperature data, or indirectly in terms of the Net Solar Index and the wind velocity. This paper describes the air attenuation model, which was developed as an integral part of an environmental noise prediction system.     

An application of closed queueing networks theory in truck-shovel systems

ABSTRACT

Primary applications of queueing networks theory have been in the area of computer systems and computer communication networks analysis and performance. The application introduced here is a steady state analysis of a generalized truck-shovel system in a typical open pit mine. The service time distributions of each activity are assumed to be of a general form. The approach used here minimizes the error of performance parameter estimates of the most saturated service center. The formulation allows one to obtain estimates of systemparameters relatively fast and very close to those obtained by simulation. The relative error of the criticalperformance parameter estimates as compared to those obtained by simulation do not exceed 5%. The output of the model can be used within various optimization schemes for design and operational control of open pit mining systems.     

Evaluating the effect of rock parameters on surface mine blasting by finite element analysis

ABSTRACT

The blasting process in surface mines involves extremely complex interactions. Utilizing Finite Element (FE) analysis, the affect of rock mass properties and discontinuity data can be fairly idealized and assessed. The purpose of this paper is to present the application of finite element methods to fragmentation due to blasting in surface mining operations. As a result, the prediction and extent of blasting will help the engineers engaged in surface mining and construction operations to use explosives efficiently.     

Geotechnical and mine planning considerations in structurally thickened coal deposits at Smoky River Coal Limited,Alberta

ABSTRACT

Structurally thickened coal deposits often form attractive surface mining targets. At Smoky River Coal Limited (SRCL), economic occurrences of structurally thickened coal are found in folded and faulted strata due to the mechanisms of hinge zone dilation and imbricate thrusting (duplexes) respectively. The characteristic features of these steeply dipping and complexly structured deposits require that special attention be given to pit wall design and operational practices.

This paper examines the characteristics of structurally thickened coal deposits at SRCL that affect the surface mining process and explains relevant geotechnical parameters and operational considerations that are used to mine these deposits. Three case histories are also examined to illustrate design and monitoring methods that are employed.     

New trends in drilling and blasting technology

ABSTRACT

The mining industry is poised on the threshold of some exciting opportunities. It has been realized that the unit operations such as drilling, blasting, excavation, loading, hauling and crushing are interrelated variables in the total cost equation. The development, advancement and utilization of the innovative technologies are very important for the mining industry to be cost effective. In order to improve performance, the drilling and blasting industry is rapidly adopting technology in all forms. In the modem mines it is very common to encounter the latest forms of laser measurement technologies, global positioning systems (GPS), communication technology and computer systems. The developments in the areas of planning and design of blasts, drill monitoring, drillhole deviation, drill machine navigation systems and laser profiling systems have been discussed in this paper. The innovative practices in the areas of bulk loading of explosives, controlled blasting, explosive performance measurement and the evaluation of blast outcome and productivity have been outlined. The role to be played by the electronic detonators in the next millennium to improve blasting efficiency and mining economics has been described.