Barrick’s Turquoise Ridge Gold Mine Optimizes Underground Production Scheduling Operations

2020 ◽  
Author(s):  
Andrea Brickey ◽  
Akshay Chowdu ◽  
Alexandra Newman ◽  
Marcos Goycoolea ◽  
Raphael Godard
Keyword(s):  
Production Scheduling ◽  
Time Horizon ◽  
Net Present Value ◽  
Resource Constraints ◽  
Three Dimensional ◽  
Mine Planning ◽  
Gold Mine ◽  
Mining Operations ◽  
Turquoise Ridge

Mining operations determine a long-term production schedule, often to maximize net present value. For a time horizon of between years and decades, optimization models seek the extraction times—with monthly or yearly fidelity—of three-dimensional, notional blocks of ore and waste within a deposit to satisfy spatial precedence constraints, as well as resource constraints on the amount of material extracted and sent to the mill. With algorithmic advances, as well as those in mine planning software and in hardware, we are able to solve instances with a decade-long horizon at daily fidelity. The resulting objective, repeatable, and defensible schedules inform production and maintenance supervisory decisions based on resource availability, that is, loaders, shovels, haul trucks, and mineral processors. We implement our solutions at the Turquoise Ridge underground gold mine in Nevada, United States. These solutions indicate more than a 2% increase in total ounces extracted over a decade while decreasing development footage by as much as 11% over the same time horizon. Furthermore, we are able to incorporate rules governing a shared resource and to evaluate binding versus nonbinding capacity constraints.

scholarly journals Incorporation of Geometallurgical Attributes and Geological Uncertainty into Long-Term Open-Pit Mine Planning

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 108 ◽  
Author(s):  
Nelson Morales ◽  
Sebastián Seguel ◽  
Alejandro Cáceres ◽  
Enrique Jélvez ◽  
Maximiliano Alarcón
Keyword(s):  
Production Scheduling ◽  
Programming Model ◽  
Mineral Resources ◽  
Mineral Deposit ◽  
Open Pit Mine ◽  
Mine Planning ◽  
Open Pit ◽  
Operational Parameters ◽  
Financial Outcomes

Long-term open-pit mine planning is a critical stage of a mining project that seeks to establish the best strategy for extracting mineral resources, based on the assumption of several economic, geological and operational parameters. Conventionally, during this process it is common to use deterministic resource models to estimate in situ ore grades and to assume average values for geometallurgical variables. These assumptions cause risks that may negatively impact on the planned production and finally on the project value. This paper addresses the long-term planning of an open-pit mine considering (i) the incorporation of geometallurgical models given by equiprobable scenarios that allow for the assessing of the spatial variability and the uncertainty of the mineral deposit, and (ii) the use of stochastic integer programming model for risk analysis in direct block scheduling, considering the scenarios simultaneously. The methodology comprises two stages: pit optimization to generate initial ultimate pit limit per scenario and then to define a single ultimate pit based on reliability, and stochastic life-of-mine production scheduling to define block extraction sequences within the reliability ultimate pit to maximize the expected discounted value and minimize the total cost of production objective deviations. To evaluate the effect of the geometallurgical information, both stages consider different optimization strategies that depend on the economic model to be used and the type of processing constraints established in the scheduling. The results show that geometallurgical data with their associated uncertainties can change the decisions regarding pit limits and production schedule and, consequently, to impact the financial outcomes.

scholarly journals Analysis of the variables: Commodity price and discount rate on long-term open pit mine planning

2021 ◽  
Vol 6 (2) ◽  
pp. 142-150
Author(s):  
Fontes MP ◽  
Koppe JC ◽  
Silva Neto JA
Keyword(s):  
Discount Rate ◽  
Net Present Value ◽  
Market Price ◽  
Commodity Price ◽  
Open Pit Mine ◽  
Mine Planning ◽  
Open Pit ◽  
Economic Criterion ◽  
Physical Constraints

Long-term open pit mine planning is a complex process which deals with numerous uncertainties, whether they are economical (commodity price, operational costs, production schedule, discount rate, inflation, among others); geological (grade distribution, density, hardness, etc); or physical constraints (property limits, environmental issues, legislation, etc). In this context, this paper aims to evaluate the effects of the variation of two important variables: commodity price and discount rate, with regard to the economic criterion, represented by the Net Present Value (NPV) of the mining business. Starting from a baseline value of US$ 80/t, the commodity (phosphate rock was used as a case study) price was varied within a 50% range, above and below the baseline value, obtained from historic values from the last 5 years. The discount rate values adopted in the analyses were 6%, 8%, 10%, 12%, 14%, 16%, 18% and 20%. The results showed increases in the market price yielded higher NPV and life of mine values. On the other hand, it was noted that increases in the discount rate can significantly alter the NPV, materially reducing the value of the mining undertaking. It is also worth noting that, in contrast to more robust approaches such as Real Options Theory (ROT), traditional Discounted Cash Flow (DCF) methods, such as NPV, assume variables, such as commodity price, to be fixed, which could either lead to the undervaluation or overvaluation of a project.

scholarly journals Long-Term Planning for Open Pits for Mining Sulphide-Oxide Ores in Order to Achieve Maximum Profit

2017 ◽  
Vol 62 (4) ◽  
pp. 807-824 ◽  
Author(s):  
Daniel Kržanović ◽  
Vesna Conić ◽  
Dejan Stevanović ◽  
Božo Kolonja ◽  
Jovan Vaduvesković
Keyword(s):  
Development Strategy ◽  
Net Present Value ◽  
Planning Process ◽  
Acid Leaching ◽  
Optimal Recovery ◽  
Complex Nature ◽  
Mining Operations ◽  
Maximum Profit ◽  
Ore Processing

Abstract Profitable exploitation of mineralised material from the earth’s crust is a complex and difficult task that depends on a comprehensive planning process. Answering the question of how to plan production depends on the geometry of the deposit, as well as the concentration, distribution, and type of minerals in it. The complex nature of mineral deposits largely determines the method of exploitation and profitability of mining operations. In addition to unit operating costs and metal prices, the optimal recovery of and achievement of maximum profit from deposits of sulphide-oxide ores also depend, to a significant extent, on the level of technological recovery achieved in the ore processing procedure. Therefore, in defining a long-term development strategy for open pits, special attention must be paid to the selection of an optimal procedure for ore processing in order to achieve the main objective: maximising the Net Present Value (NPV). The effect of using two different processes, flotation processing and hydrometallurgical methods (bioleaching acid leaching), on determining the ultimate pit is shown in the case of the Kraku Bugaresku-Cementacija sulphide-oxide ore deposit in eastern Serbia. Analysis shows that the application of hydrometallurgical methods of processing sulphide-oxide ore achieved an increase in NPV of 20.42%.

scholarly journals A practical, long-term production scheduling model in open pit mines using integer linear programming

2020 ◽  
Vol 120 (12) ◽  
Author(s):  
J. Gholamnejad ◽  
R. Lotfian ◽  
S. Kasmaeeyazdi
Keyword(s):  
Linear Programming ◽  
Mathematical Programming ◽  
Integer Linear Programming ◽  
Production Scheduling ◽  
Mine Planning ◽  
Open Pit ◽  
Mixed Integer ◽  
Small Scale ◽  
Mining Equipment

SYNOPSIS Long-term production scheduling is a major step in open pit mine planning and design. It aims to maximize the net present value (NPV) of the cash flows from a mining project while satisfying all the operational constraints, such as grade blending, ore production, mining capacity, and pit slope during each scheduling period. Long-term plans not only determine the cash flow generated over the mine life, but are also the basis for medium- and short-term production scheduling. Mathematical programming methods, such as linear programming, mixed integer linear programming, dynamic programming, and graph theory, have shown to be well suited for optimization of mine production scheduling. However, the long-term plans generated by the mathematical formulations mostly create a scattered block extraction order on several benches that cannot be implemented in practice. The reason is the excessive movement of mining equipment between benches in a single scheduling period. In this paper, an alternative integer linear programming (ILP) formulation is presented for long-term production scheduling that reduced the number of active benches in any scheduling period. Numerical results of the proposed model on a small-scale open pit gold mine show a 34% reduction in the average number of working benches in a given scheduling period. Keywords: long-term production scheduling, mathematical programming, practical plans, equipment movements.

scholarly journals Impact in long-term planning of optimization algorithms and mineral deposit geometry

2013 ◽  
Vol 66 (1) ◽  
pp. 105-110
Author(s):  
Mateus Toniolo Candido ◽  
Rodrigo de Lemos Peroni ◽  
Daniel Hilário
Keyword(s):  
Three Dimensional ◽  
Mineral Deposit ◽  
Mine Planning ◽  
Commercial Software ◽  
Optimal Sequence ◽  
Mining Engineer ◽  
Phosphate Deposit ◽  
Block Models ◽  
Temporal Sequences

The main objective of mine planning is to determine ore quantity and quality distribution along a time sequence, i.e., scheduling the ore necessary to make the project technically and economically feasible. These temporal sequences are fundamental for the financial success of a mining activity and currently this optimal sequence can be obtained through various mining software. Most studies in mine planning present the final pit calculated by only one algorithm chosen by the mining engineer or simply by availability. Besides, technical constraints and geometrical aspects can be imposed promoting differences on the results of the project. There are many algorithms implemented in various commercial software for the ultimate pit calculation. One of the purposes of this work is to check the effectiveness of the algorithms that obtained greater recognition within the mineral industry and if there are differences related to the type of mineralization and deposit where they are applied. The comparison is performed using two commercial software, and two different algorithms to determine if differences can be observed from the different mineralization types. The implementation of the two algorithms in three-dimensional block models estimated and analyzed for three types of deposits: a massive disseminated copper orebody, a large igneous phosphate deposit and a subvertical gold vein type.

OPTIMAL LOCATION OF AN UNDERGROUND CONNECTOR USING DISCOUNTED STEINER TREE THEORY

2020 ◽  
Vol 62 (3) ◽  
pp. 334-351
Author(s):  
K. G. SIRINANDA ◽  
M. BRAZIL ◽  
P. A. GROSSMAN ◽  
J. H. RUBINSTEIN ◽  
D. A. THOMAS
Keyword(s):  
Steiner Tree ◽  
Net Present Value ◽  
Optimal Location ◽  
Mine Planning ◽  
Gold Mine ◽  
Optimal Solutions ◽  
Present Value ◽  
Ore Body ◽  
Ore Bodies ◽  
Planning Problems

AbstractThe objective of this paper is to demonstrate that the gradient-constrained discounted Steiner point algorithm (GCDSPA) described in an earlier paper by the authors is applicable to a class of real mine planning problems, by using the algorithm to design a part of the underground access in the Rubicon gold mine near Kalgoorlie in Western Australia. The algorithm is used to design a decline connecting two ore bodies so as to maximize the net present value (NPV) associated with the connector. The connector is to break out from the access infrastructure of one ore body and extend to the other ore body. There is a junction on the connector where it splits in two near the second ore body. The GCDSPA is used to obtain the optimal location of the junction and the corresponding NPV. The result demonstrates that the GCDSPA can be used to solve certain problems in mine planning for which currently available methods cannot provide optimal solutions.

scholarly journals Simulation-based mine extraction sequencing with chance constrained risk tolerance

SIMULATION ◽  
2017 ◽  
Vol 93 (6) ◽  
pp. 527-539 ◽  
Author(s):  
Mustafa Kumral ◽  
Yuksel Asli Sari
Keyword(s):  
Monte Carlo ◽  
Production Scheduling ◽  
Net Present Value ◽  
Risk Tolerance ◽  
Chance Constrained Programming ◽  
Present Value ◽  
Parameter Uncertainties ◽  
Mining Operations ◽  
Context Mining

Technical and financial uncertainties present significant risks to the profitability and efficiency of mining operations. Unexpected realizations (e.g., price or grade) may result in catastrophic consequences. This phenomenon forces mining industries to use probabilistic decision-making tools to assess, mitigate, and manage the risks associated with these uncertainties. In this context, mining operations need robust schedules, which are insensitive to market changes and/or unexpected grade realizations. The mine production scheduling problem consists of three sub-problems: extraction sequencing (timing), ore-waste discrimination (classification) and production rates (utilization). The solutions to these problems are generated under significant parameter uncertainties. This paper proposes an extraction sequencing approach in which the net present value of a mining project is, for a given risk tolerance, maximized and the actual risk tolerance is then verified through Monte-Carlo simulations. The risk tolerance is a measure of uncertainty and that secures the project net present value with a given probability. Risk tolerance is derived through the use of standard deviations of block economic values in the medium of multiple grade and economic images of orebody. The proposed approach is demonstrated on a case study using gold mine data. The results of the case study show that the proposed approach, combining chance-constrained programming and Monte-Carlo simulation, can be used to solve the mine extraction sequencing problem in an uncertain financial and technical environment.

Practical electron tomography

1995 ◽  
Vol 53 ◽  
pp. 742-743
Author(s):  
C.L. Woodcock
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3D Shape ◽  
Computational Resources ◽  
Shape Of Particles

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.Tomographic reconstruction results in a three dimensional description of an individual EM specimen, most commonly a section, and is therefore applicable to problems in which ultrastructural details within the thickness of the specimen are obscured in single micrographs. Information that can be recovered using tomography includes the 3D shape of particles, and the arrangement and dispostion of overlapping fibrous and membranous structures.

Custom Presurgical Planning for Midfacial Reconstruction

2020 ◽  
Vol 36 (06) ◽  
pp. 696-702
Author(s):  
Nolan B. Seim ◽  
Enver Ozer ◽  
Sasha Valentin ◽  
Amit Agrawal ◽  
Mead VanPutten ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Functional Performance ◽  
Three Dimensional ◽  
Free Tissue Transfer ◽  
Long Term Effects ◽  
Presurgical Planning ◽  
Dental Rehabilitation ◽  
Midface Reconstruction ◽  
Reconstructive Algorithm

AbstractResection and reconstruction of midface involve complex ablative and reconstructive tools in head and oncology and maxillofacial prosthodontics. This region is extraordinarily important for long-term aesthetic and functional performance. From a reconstructive standpoint, this region has always been known to present challenges to a reconstructive surgeon due to the complex three-dimensional anatomy, the variable defects created, combination of the medical and dental functionalities, and the distance from reliable donor vessels for free tissue transfer. Another challenge one faces is the unique features of each individual resection defect as well as individual patient factors making each preoperative planning session and reconstruction unique. Understanding the long-term effects on speech, swallowing, and vision, one should routinely utilize a multidisciplinary approach to resection and reconstruction, including head and neck reconstructive surgeons, prosthodontists, speech language pathologists, oculoplastic surgeons, dentists, and/or craniofacial teams as indicated and with each practice pattern. With this in mind, we present our planning and reconstructive algorithm in midface reconstruction, including a dedicated focus on dental rehabilitation via custom presurgical planning.

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