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Author Moreno, E.; Rezakhah, M.; Newman, A.; Ferreira, F. pdf  doi
openurl 
  Title Linear models for stockpiling in open-pit mine production scheduling problems Type
  Year 2017 Publication European Journal Of Operational Research Abbreviated Journal Eur. J. Oper. Res.  
  Volume 260 Issue 1 Pages 212-221  
  Keywords OR in natural resources; Stockpiling; Linear and integer programming; Mine planning; Open pit mining  
  Abstract The open pit mine production scheduling (OPMPS) problem seeks to determine when, if ever, to extract each notional, three-dimensional block of ore and/or waste in a deposit and what to do with each, e.g., send it to a particular processing plant or to the waste dump. This scheduling model maximizes net present value subject to spatial precedence constraints, and resource capacities. Certain mines use stockpiles for blending different grades of extracted material, storing excess until processing capacity is available, or keeping low-grade ore for possible future processing. Common models assume that material in these stockpiles, or “buckets,” is theoretically immediately mixed and becomes homogeneous. We consider stockpiles as part of our open pit mine scheduling strategy, propose multiple models to solve the OPMPS problem, and compare the solution quality and tractability of these linear-integer and nonlinear-integer models. Numerical experiments show that our proposed models are tractable, and correspond to instances which can be solved in a few seconds up to a few minutes in contrast to previous nonlinear models that fail to solve. (C) 2016 Elsevier B.V. All rights reserved.  
  Address [Moreno, Eduardo; Ferreira, Felipe] Univ Adolfo Ibanez, Fac Sci & Engn, Avda Diagonal Torres 2700, Santiago, Chile, Email: eduardo.moreno@uai.cl;  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0377-2217 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000396952000018 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 715  
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Author Rezakhah, M.; Moreno, E.; Newman, A. pdf  doi
openurl 
  Title Practical performance of an open pit mine scheduling model considering blending and stockpiling Type
  Year 2020 Publication Computers & Operations Research Abbreviated Journal Comput. Oper. Res.  
  Volume 115 Issue Pages 12 pp  
  Keywords Stockpiling; Linear and integer programming; Mine planning; Open pit mining; Software  
  Abstract Open pit mine production scheduling (OPMPS) is a decision problem which seeks to maximize net present value (NPV) by determining the extraction time of each block of ore and/or waste in a deposit and the destination to which this block is sent, e.g., a processing plant or waste dump. Spatial precedence constraints are imposed, as are resource capacities. Stockpiles can be used to maintain low-grade ore for future processing, to store extracted material until processing capacity is available, and/or to blend material based on single or multiple block characteristics (i.e., metal grade and/or contaminant). We adapt an existing integer-linear program to an operational polymetallic (gold and copper) open pit mine, in which the stockpile is used to blend materials based on multiple block characteristics, and call it ((P) over cap (la)). We observe that the linear programming relaxation of our objective function is unimodal for different grade combinations (metals and contaminants) in the stockpile, which allows us to search systematically for an optimal grade combination while exploiting the linear structure of our optimization model. We compare the schedule of ((P) over cap (la)) with that produced by (P-ns) which does not consider stockpiling, and with ((P) over tilde (la)), which controls only the metal content in the stockpile and ignores the contaminant level at the mill and in the stockpile. Our proposed solution technique provides schedules for large instances in a few seconds up to a few minutes with significantly different stockpiling and material flow strategies depending on the model. We show that our model improves the NPV of the project while satisfying operational constraints. (C) 2019 Elsevier Ltd. All rights reserved.  
  Address [Rezakhah, Mojtaba] Tarbiat Modares Univ, Engn Dept, POB 14115411, Tehran, Iran, Email: m.rezakhah@modares.ac.ir;  
  Corporate Author Thesis  
  Publisher Pergamon-Elsevier Science Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0305-0548 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000514218600009 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 1161  
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