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Optimisation in Underground Mining
Abstract
Efficient methods to model and optimise the design of open pit mines have been known for many years. Although the underground
mine design problem is conceptually more difficult it has a similar potential for optimisation. Recent research demonstrates
some useful progress in this topic. Here we provide an overview of some of this research.
... Literature reviews on the use of operations research in mining in general (e.g., Newman et al., 2010;Bjorndall et al., 2011;Kozan and Liu,2011), and below ground mining in particular (Alford et al., 2007), indicate that: while there is a wealth of research in the development of optimization models for strategic and tactical problems in mining, published work on scheduling models used at the operational scale have been much more scarce. The literature to be reviewed on this problem is therefore brief and shows a great diversity of models formulated for operational production planning. ...
... Constraint [4] is a standard flow balance equation for transition nodes in a network model. Equation [5] defines the terminal node and the mass of each material type demanded at the terminal node. Note that the total mass of each material type refers to the total mass of each material type that was mined during each period. ...
In underground mines, the problem of efficiently scheduling and allocating weekly operations has a major impact on the long-term productivity of the mine. The problem of selecting the optimal locations for operations in an underground gold mine is a complex task. It is not solved by simply selecting the levels with the richest grade because the transportation network for ore in an underground mine has a diverse set of capacity constraints that can frustrate immediate mining of all the richest levels. To solve this scheduling difficulty, we formulated a new mixed-integer network flow model of the problem of weekly allocating mining operations in an underground goldmine such that the total gold mined (in ounces) was maximized subject transportation capacity constraints. The model was applied an underground gold mine in Red Lake, Ontario, Canada. The results were compared to those of a two greedy heuristic models that were designed to represent the decision-making heuristics that are currently used at the mine. It was found that the new model yielded solutions that improved upon the two greedy heuristics by 14.7% and 6.0%, respectively. The results of this research illustrate that the development of this optimization model can support decisions to improve a gold mine’s productivity.
... In open-pit mining, mathematical programming techniques have been employed for production scheduling optimization problems, and they have also been used for similar applications in underground mining. For both short-and longterm underground mine planning and production scheduling problems, the following mathematical programming approaches including linear programming (LP), integer programming (IP), mixed-integer programming (MIP), mixed-integer linear programming (MILP), goal programming (GP), and quadratic programming (QP) have been employed (Alford et al. 2006;Newman et al. 2010;Nehring, Topal, Little 2010;Musingwini 2016;Appianing and Ben-Awuah 2018). ...
Extraction and development sequences must be scheduled strategically in order to maximize the life of mine. The complexities and computational difficulties associated with underground mine planning makes it challenging and open to further research. This paper presents a mathematical programming framework based on mixed-integer linear programming (MILP) formulation for integrated open stope development and production scheduling. Additionally, the MILP model incorporates backfilling, operational levels control, and stope extraction duration control during production scheduling. The MILP model generated a net present value of $244.7 M and determined the capital, ventilation, operational, and ore pass development schedules as well as mining and processing schedules for a gold project with 25 years mine life. A total of 2.48 Mt of material was extracted and processed out of 2.88 Mt mineralized material.
... In addition to precedence constraints, the authors considered the restriction of resource availability over time. Since then the RCPSP and its extensions have been used in a wide range of practical applications in diverse industries, such as supply chain [3], mining [4] and job-shop scheduling [5]. The RCPSP's vast range of applications, as well as its computational challenges (it is an NP-Hard problem [6]) has attracted the attention of many scholars [7]. ...
Scheduling projects under limited resource availability, which is called the resource-constrained project scheduling problem (RCPSP), has a wide range of real-world applications, e.g., in mining, manufacturing and supply chain. The RCPSP is NP-hard, and over the last five decades researchers attempted to propose various solution techniques for this challenging problem. The relax-and-solve (R&S) algorithm is a recently proposed method for solving various scheduling problems, such as job-shop and single and parallel machine scheduling problems. This research contributes to the existing research on the R&S by presenting an easy-to-implement and effective R&S method for solving RCPSP. Our R&S employs CPLEX CP optimizer as an optimization solver to generate and optimize schedules within a heuristic framework. We further improve the algorithm’s performance by employing forward–backward passes. The results of testing the algorithms on 1560 standard instances from the well-known PSPLIB show our heuristic delivers competitive results and outperforms state-of-the-art methods for solving the RCPSP.
... As envoltórias fornecem uma referência para engenheiro de curto prazo projetar as posições finais do realce matemático (Alford et al., 2007). É importante se atentar que, a envoltória externa, apesar de retornar um menor valor financeiro, ele gera maior tonelagem de minério. ...
Na mineração a céu aberto, no horizonte de curto prazo, é realizado a subdivisão dos planos de lavra em trimestral, mensal, semanal e diário da operação. Em um horizonte mensal, um planejador de curto prazo define as poligonais, que compreende os sucessivos avanços de lavra, satisfazendo parâmetros de qualidade e tonelagem de minério fixadas previamente pela usina. As poligonais, tradicionalmente, são projetadas sem uma devida abordagem sistemática. Logo, as interações realizadas para obter as especificações exigidas pela usina é limitada. Portanto, há uma demanda por estudos envolvendo técnicas de otimização de unidades mínimas de lavra, auxiliando o delineamento do minério, de modo a minimizar a variabilidade em teor e maximizar a recuperação da usina, além de fornecer base quanto a tomada de decisão diária pelo planejador de curto prazo. Esse artigo propõe a adaptação de dois algoritmos de otimização – Cone Flutuante e Stope Flutuante, tradicionalmente utilizados para a definição de cavas e realces subterrâneos. Foi atribuído um valor de dimensão igual a zero para os pilares de sustentação, aproximando o método de câmaras e pilares a um método de bancadas, para configurar um comportamento próximo a lavra em céu aberto. O estudo comprovou que ambas as metodologias apresentaram resultados satisfatórios. Apesar da necessidade de ajustes manuais, descartando blocos compartilhados, o Cone Flutuante mostrou ser um sistema mais seletivo, principalmente para teores de corte mais elevado.
... modelling the interaction between man and the environment taking into account all activities related to natural resources and their use, to find alternative courses of action, and to obtain optimal solutions for various problems. A great number of papers regarding the application of operations research in the field of natural resources are published: in the field of agriculture (Agrell et al., 2004;Andrić-Gušavac et al., 2014Castrodeza et al., 2005;Epstein et al., 2007;Hameed et al., 2013;Hayashi, 2000;Marchamalo & Romero, 2007;Pacini et al., 2004;Peña et al., 2007;Romero, 2000;Romero & Rehman, 2003;Sørensen & Bochtis, 2010;Weintraub & Romero, 2006;Zekri & Boughanmi, 2007), forestry (Andalaft et al., 2003;Bjørndal et al., 2012;Church, 2007;Conrad et al., 2012;Gunn, 2007;Heinonen et al., 2009;Könnyű & Tóth, 2013;McDill et al., 2002;Tóth et al., 2011), water resources (Björndal et al., 2004;Herrero & Pascoe, 2003;Pascoe et al., 2001), and mining (Alford et al., 2007;Caccetta, 2007;Newman et al., 2010;Ramazan, 2007). ...
The elements of the supply and environmental chain are identified and connected through an operations research process. A framework is developed to include these chains into a process that deals with operations research problems within two different, complex areas: economic (supply) and natural systems (environmental), and emphasizes the influence of the solution on both systems and their performance. The framework helps researchers to get a better insight into the issues considering both environmental and industry aspects. The study proposes a causal relationship between the supply chain and environmental chain and begins to make a bridge between these two chains using operations research methods and techniques. In this context, a multi-period scenario-based stochastic model is developed. To deal with the uncertainties and to investigate the trade-offs between the objective functions, an interactive fuzzy multi-objective method is performed. In the case study section, reconcilement of the conflicting objectives in a waste management case is questioned and the future recommendations are highlighted.
Carrying out exploitation in coal mines with a methane hazard imposes the use of special procedures and the analyses of numerous parameters in order to secure mining teams working underground. The article presents a method of coal seam exploitation design under conditions of a methane hazard for the newly prepared coal seams 404/1 and 403/1 in the years 2022 to 2030 in a coal mine in southern Poland as a case study. It primarily focuses on the preparation of the methane hazard prognosis. When adequately prepared, this is key to correctly designing the mining system in the newly opened parts of the deposit. Based on the obtained results, the appropriate methane drainage system and detection systems can be selected. The calculations led to the definition in which the longwall panel emissions of methane would be the highest. The estimates showed that, from 2022 to the beginning of 2028, even methane emissions between approximately 30 m3/min and 45 m3/min are forecast, with a significant increase for half of 2028 to a value between 57.58 m3/min and 100.00 m3/min. The highest value of methane emission was forecast for the A4 and A5 longwall panels in the 403/1 coal seam at 13.53 and 49.67 m3/min, respectively, and for the A2 and B1 longwall panels in the 404/1 seam at 41.85 m3/min and 25.46 m3/min, all with advance equal 7 m/d. Therefore, a drainage system will be required in all designed longwall panels. Considering the methane emission into the longwalls and the designed U-type ventilation, the calculated drainage effectiveness will vary between 38.3 and 40.6%. Higher effectiveness values require the application of a U-type ventilation with drainage, which allows obtaining effectiveness reaching 60.2%, with the methane emission between 20 and 30 m3/min, or even up to 62.6%, with the methane emission at the level of 30–40 m3/min. Another critical design stage is utilizing the gathered methane; the proposition is to use it in the cogeneration system. The heat generated by gas-powered engines should be used in the absorbent coolers that are used for chilling the water for the central air-conditioning system of the mine.
In the commonly used underground mine planning framework, mine design is first established and is the main input for the subsequent long-term mine production scheduling optimization. This sequential optimization approach cannot, therefore, capture the synergies between the involved planning steps, generating solutions that depart substantially from a global optimum. In addition, traditional underground mine planning methods for stope design and life-of-mine production scheduling are deterministic and are based on a single estimated orebody model. As a result, the uncertainty and variability in grades and material types are not incorporated into the optimization process, resulting in designs that misrepresent all high-, medium- and low-grade stoping volumes and production schedules with misleading forecasts. A two-stage stochastic integer program (SIP) for integrated optimization of stope and development network designs and an underground mine production scheduling are proposed for the sublevel open stoping mining method under grade uncertainty and variability, quantified by a set of geostatistical simulations of the mineral deposit considered. Assuming a mine is accessed through a shaft, the model defines a schedule of levels and stopes, which aims to maximize the discounted revenues, minimize development costs, and manage the risk of not meeting production targets, while satisfying geotechnical constraints. The practical aspects of the proposed method are presented through an application at an underground gold mine. A comparison with the stepwise framework, where the stope design is input to a subsequent optimization of the production schedule, shows that the proposed approach provides a physically different design and production schedule with an 11% higher net present value (NPV) and a life-of-mine that is two years shorter, affirming the advantages of the integrated optimization process.
This thesis is primarily concerned with mapping a path for industry to fully automated drill and blast, which despite the progress made with automation in the mining industry remains the hitherto unattainable ‘Holy Grail’ for mining. This would remove personnel from drill and blast zones, but in harmony with fully automated harvesting units like LHDs, would remove personnel from most operational areas in both open cut and underground mines, for hardrock and coal.
Fully automated drill and blast will not only improve safety but eliminate many of the safety and health management systems that are presently designed to protect personnel from operational risks. That is not to say that risk assessment and management will not be necessary in development or production areas once they are fully automated but keeping machinery safe from harm invokes a different view of the risks. Reducing the regulatory burdens reduces the overall costs of mining. It would also enable the exploitation of now difficult to mine resources and bring new mining methodologies to bear on existing mining operations. Fully automated drill and blast may see blasting return to underground coal mines to advance production rates above that presently gained with Longwalls and continuous miners – and all at an aggregate lower cost per tonne than now achieved.
Fully automating the drill function is conceptually not that difficult. There are many semiautomated drill rigs that can readily be made fully automated with robotics and AI. Fully automating the blast function is a somewhat more complex undertaking. It can be achieved by loading blast holes with prepackaged blast cartridges. Indeed, it can only be achieved in this way. The prepackaged blast cartridges will allow more precise blasting and with a lot less explosive than is now used. The days of loading blast holes with large volumes of expensive bulk explosives may be coming to an end. Conventional blast procedures may be likened to the muskets of old, where black powder is poured into the breach, a ball, and a wad inserted, then rammed home firm with a rod. A cap is then added at the firing end for initiation when the trigger is squeezed. Firing on full-automatic only became possible with the development of cartridge technology. There is no such animal as a musket machine gun!
Generally, shallow deposits are mined through open-pit mining and where the deposits are extended to a substantial depth, there is a potential for a combination of open-pit and underground mining methods. In this case, mine planning and optimisation play a significant role in the decision-making. This paper proposes a mixed-integer programming model to obtain the optimal transition point and the transition period from open-pit to underground mining, maximizing the project net present value considering crown pillar placement and development cost. An implementing at a three-dimensional case study generates the optimal transition point and period and an optimal production schedule for both open-pit and underground operations. The implementation considers three scenarios: transition point only (scenario 1), transition point and period without production delay (scenario 2), and transition point and period with two-period production delay during the transition (scenario 3). The optimal transition point for scenario 1 is 315 m and for scenarios 2 and 3 is 360 m below the surface.
A discussion about the optimization of cut-off grade at mount Isa Mines Limited's Enterprise mine by using a commercially available software, is presented. The steps taken to determine the cut-off grade for each orebody include, creating the cut-off grade design models, scheduling the cut-off grade designs and optimum cut-off grade determination by evaluating economics of schedules. The designing stopes for each cut-off grade models are also discussed.
The value of a mining project is based upon a quantitative model of material of value in the ground, a block model of the deposit, and a schedule for extracting this material including relevant revenues and costs. The schedule usually attempts to maximise the net present value (NPV) of the project over the life of the mine. Frequently, a block model is the result of a smooth interpolation, such as kriging, of data collected from holes drilled throughout the orebody. More drill holes will lead to greater certainty in the contents of block models and from these 'more accurate' block models, schedules of greater ultimate value may be realised. We discuss how conditional simulations can assist with rigorously valuing the trade-off between the cost of extra drilling and the schedules of greater value that may be constructed from the resultant block models of greater accuracy.
Generally, production planning is con-cerned with the best use of fixed resources to deter-mine a production schedule for one or more production units supplying one or more markets. Production scheduling determines when each production unit will be used and its production level. However, the produc-tion scheduling problems are intimately associated with the location of existing or new production units and processing facilities. Normally, mine location allows only a limited choice; processing plant types and locations are considerably more flexible. This paper presents a generalized multiperiod MIP model as an aid in determining the mine production schedule and the processing plant types and location to satisfy multiple markets. A brief description of MZP and how it has been applied in the mineral and other industries is discussed. A complete description of the model with an application to a coal preparation plant system is presented.
This paper examines the problem of optimising the life-of-mine costs of an underground mine, focussing particularly on the costs associated with the underground development needed to provide access to and haulage from the ore zones. This mine optimisation problem is modelled as a network and a solution technique is outlined. The effectiveness of this solution technique is then demonstrated by applying it to a prototype test example and some actual case studies. Finally, extensions of this technique to other underground mining problems are discussed.
Although there are now many tools and techniques available for optimising various parts of the mining and processing stream in isolation, so far an integrated approach that simultaneously addresses the various components has not been available. In the last four years Jeff Whittle has focused on expanding the boundaries of integrated optimisation for the resource industry. The result is an approach that applies business and operational modelling techniques to construct integrated geological, mining, processing, transport and market models, which are then optimised by allowing powerful optimisation algorithms to control the values of those variables that are considered negotiable. Confidently referred to as Global Optimisation, due to the number of variables that are simultaneously controlled, the result is a powerful business tool that can be used as a platform to support strategic decision-making at many levels. In this paper, the author outlines a variety of modelling techniques applied during recent projects, the optimisation mathematics employed and the typical characteristics of a Globally Optimised business plan. PROFILE Whittle Consulting is a private venture by Jeff, Ruth and Gerald Whittle, which combines expertise in research, mathematics, computing and business planning. The focus is on developing and applying new procedures to identify opportunities and increase understanding of the management of portfolios of mineral and technical plant assets.