scholarly journals Phase Planning for Open Pit Coal Mines through Nested Pit Generation and Dynamic Programming

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xiaowei Gu ◽  
Qing Wang ◽  
Xiaochuan Xu ◽  
Xiaoqian Ma
Keyword(s):  
Dynamic Programming ◽  
Net Present Value ◽  
Open Pit ◽  
Coal Deposit ◽  
Present Value ◽  
Coal Seams ◽  
Column Model ◽  
Coal Deposits ◽  
Coal Rock

This paper presents a phase planning method specially designed for coal deposits with nearly horizontal, bedded coal seams. The geology of this type of deposit is modeled into a column model, instead of a block model, to avoid coal-rock mixing in blocks. A nested pit generation algorithm is developed for producing a series of nested, least-strip ratio pits with a column model as its input. The algorithm completely overcomes the troublesome gap problem. Taking the least-strip ratio pits as possible phase states, a dynamic programming formulation is proposed to simultaneously optimize the number of phases, the phase-pits, and the ultimate pit, with an objective of maximizing the net present value. The merits and capability of the proposed method are demonstrated through a case study on a large coal deposit.

Simultaneous Optimization of Final Pit and Production Schedule in Open-Pit Coal Mines

2011 ◽  
Vol 323 ◽  
pp. 222-228
Author(s):  
Xiao Wei Gu ◽  
Peng Fei Wang ◽  
Qing Wang ◽  
You Yi Zheng ◽  
Jian Ping Liu ◽  
...  
Keyword(s):  
Dynamic Programming ◽  
Simultaneous Optimization ◽  
Open Pit ◽  
Production Schedule ◽  
Coal Deposit ◽  
Coal Seams ◽  
Sequencing Method ◽  
The One ◽  
Dynamic Sequencing ◽  
Dynamic Programming Scheme

A dynamic sequencing method has been developed that can simultaneously optimize the final pit and the production schedule of an open-pit coal mine. The method first establishes a geological seam model of a bedded coal deposit which estimates the relevant attributes of coal seams at the center of each block on the X-Y plane. Based on the seam model, a sequence of “geologically optimum final pits” is generated and, in each of these pits, a sequence of “geologically optimum push-backs” is generated. The geologically optimum push-backs are then put into a dynamic programming scheme and the best production schedule which has the highest NPV is obtained for each final pit. After the best production schedules for all the final pits are obtained, the one with the highest overall NPV is the optimum final pit and its associated best schedule is the overall best production schedule.

scholarly journals A sequentially advancing algorithm based on multi-value dynamic programming for the cut-off grade optimization in open-pit metalliferous deposits

2021 ◽  
Author(s):  
Pritam Biswas ◽  
Rabindra Kumar Sinha ◽  
Phalguni Sen
Keyword(s):  
Dynamic Programming ◽  
Net Present Value ◽  
Real Life ◽  
Surface Mining ◽  
Life Time ◽  
Copper Deposit ◽  
Early Years ◽  
Open Pit ◽  
Present Value ◽  
Copper Mine

Abstract In techno-economic concern, cut-off grade (COG) optimization is the key for efficient mineral liquidation from the huge metalliferous surface mining sector. In this paper, a sequentially advancing algorithm based on exact multi-value dynamic programming (MDP) has been developed to determine the optimum COG of an open-pit metalliferous deposit. The proposed COG optimization algorithm aims to overcome the limitations of straightforward classical techniques in determining the optimum COG. This discrete COG-MDP model is the first of its kind and has the novelty of dealing with the simulation of eight dynamic possibilities to achieve the maximal Net Present Value (NPV). A high-level programming language (Python) has been used to develop the computer model to deal with the complexity of handling a minimum of 500 series of dynamic variables with a precision value of 0.01% in grade bins. This model can generate results in polynomial-time from the complex mine, mill, and smelter and refinery system corresponding to various limiting conditions. The prime objective considered in the model is to optimize the COG of a metalliferous deposit. The model validation has been done using a real-life case study of an open-pit copper mine in India (Malanjkhand Copper Mine, HCL), considering the fixed yearly output of the mining, milling, and smelting and refining. In this study, the optimum COG for the Malanjkhand copper deposit has been found to be (0.33%, 0.23%, 0.52%, 0.26%, 0.27%, 0.22%, 0.24%) with a maximum NPV of ₹ (12204, 14653, 16948, 14609, 21454, 26717, 38821) million corresponding to various scenarios. The findings also show that the present value of net cash-flow grows in the early years, peaks at a specified mid-life time, and then drops as the reserve is depleted. The present value gradually hits zero after the project’s life cycle, confirming the typical pattern of other mining firms.

A Dynamic-Programming Based Model for Phase-Mining Optimization in Open-Pit Metal Mines

2013 ◽  
Vol 316-317 ◽  
pp. 896-901
Author(s):  
Qing Wang ◽  
Xiao Chuan Xu ◽  
Xiao Wei Gu
Keyword(s):  
Dynamic Programming ◽  
Net Present Value ◽  
Open Pit ◽  
Present Value ◽  
Dynamic Nature ◽  
Time And Space ◽  
Full Account ◽  
Metal Mines

Three important aspects of phase-mining must be optimized: the number of phases, the geometry and position of each phase-pit (including the ultimate pit), and the ore and waste quantities to be mined in each phase. A model is presented in this paper in which, a sequence of geologically optimum pits are first generated and then dynamically evaluated to simultaneously optimize the above three aspects, with the objective of maximizing the overall net present value. The model takes into full account of the dynamic nature of the problem with respect to both time and space, and is robust in accommodating different pit wall slopes and different bench heights.

Undersaturated Hydrocarbon Reservoir Waterflooding: A simulation Approach to Performance Assessment

2021 ◽  
Author(s):  
Adekunle Tirimisiyu Adeniyi ◽  
Miracle Imwonsa Osatemple ◽  
Abdulwahab Giwa
Keyword(s):  
Oil Recovery ◽  
Net Present Value ◽  
Oil Production ◽  
Base Case ◽  
Present Value ◽  
Sweep Efficiency ◽  
Recovery Method ◽  
Solution Approach ◽  
Hydrocarbon Reservoir

Abstract There are a good numbers of brown hydrocarbon reservoirs, with a substantial amount of bypassed oil. These reservoirs are said to be brown, because a huge chunk of its recoverable oil have been produced. Since a significant number of prominent oil fields are matured and the number of new discoveries is declining, it is imperative to assess performances of waterflooding in such reservoirs; taking an undersaturated reservoir as a case study. It should be recalled that Waterflooding is widely accepted and used as a means of secondary oil recovery method, sometimes after depletion of primary energy sources. The effects of permeability distribution on flood performances is of concerns in this study. The presence of high permeability streaks could lead to an early water breakthrough at the producers, thus reducing the sweep efficiency in the field. A solution approach adopted in this study was reserve water injection. A reverse approach because, a producing well is converted to water injector while water injector well is converted to oil producing well. This optimization method was applied to a waterflood process carried out on a reservoir field developed by a two - spot recovery design in the Niger Delta area of Nigeria that is being used as a case study. Simulation runs were carried out with a commercial reservoir oil simulator. The result showed an increase in oil production with a significant reduction in water-cut. The Net Present Value, NPV, of the project was re-evaluated with present oil production. The results of the waterflood optimization revealed that an increase in the net present value of up to 20% and an increase in cumulative production of up to 27% from the base case was achieved. The cost of produced water treatment for re-injection and rated higher water pump had little impact on the overall project economy. Therefore, it can conclude that changes in well status in wells status in an heterogenous hydrocarbon reservoir will increase oil production.

Creating continuous areas of old forest in long-term forest planning

2000 ◽  
Vol 30 (11) ◽  
pp. 1817-1823 ◽  
Author(s):  
Karin Öhman
Keyword(s):  
Net Present Value ◽  
Problem Formulation ◽  
Core Area ◽  
Northern Sweden ◽  
Present Value ◽  
The Core ◽  
Long Range Planning ◽  
The Cost

Harvest activities tend often to create landscapes where the old forest is fragmented into isolated patches that provide marginal conditions for species that inhabit forest interiors. This paper presents a long-range planning model designed to maximize the net present value and to create continuous patches of old forest. In this model, the spatial structure of old forest is controlled by core area and edge habitats. Core area is defined as the area of old forest that is free of edge effects from surrounding habitats. The core area requirement is set to a fixed value for each of a number of time periods, whereas the area of edge habitats, which should be as small as possible, is weighted against the net present value. The model is applied in a case study to an actual landscape consisting of 755 stands of forest in northern Sweden and solved using simulated annealing. The results show that distinct continuous patches of old forest are created when both a core area requirement and consideration of the amount of edge habitats are included in the problem formulation. The cost of creating continuous areas of old forest was found to be significant.

Economics of a nest-box program for the conservation of an endangered species: a reappraisal

2001 ◽  
Vol 31 (11) ◽  
pp. 1992-2003 ◽  
Author(s):  
Daniel A Spring ◽  
Michael Bevers ◽  
John OS Kennedy ◽  
Dan Harley
Keyword(s):  
Net Present Value ◽  
Population Recovery ◽  
Optimal Management ◽  
Present Value ◽  
Eucalyptus Regnans ◽  
Nest Boxes ◽  
Mountain Ash ◽  
Local Abundance ◽  
Leadbeater's Possum

An optimization model is developed to identify timing and placement strategies for the installation of nest boxes and the harvesting of timber to meet joint timber–wildlife objectives. Optimal management regimes are determined on the basis of their impacts on the local abundance of a threatened species and net present value (NPV) and are identified for a range of NPV levels to identify production possibility frontiers for abundance and NPV. We apply the model to a case study focusing on an area of commercially productive mountain ash (Eucalyptus regnans F. Muell.) forest in the Central Highlands region of Victoria, Australia. The species to be conserved is Leadbeater's possum (Gymnobelideus leadbeateri McCoy), which is locally limited by a scarcity of nesting hollows. The modeling is exploratory but indicates that nest boxes may offer a promising population recovery tool if consideration is taken of their placement and areal extent through time.

Increasing ewe genetic fecundity improves whole-farm production and reduces greenhouse gas emissions intensities: 2. Economic performance

2014 ◽  
Vol 54 (9) ◽  
pp. 1248 ◽  
Author(s):  
C. K. M. Ho ◽  
T. Jackson ◽  
M. T. Harrison ◽  
R. J. Eckard
Keyword(s):  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Net Present Value ◽  
Stocking Rate ◽  
Present Value ◽  
Gas Emissions ◽  
High Fecundity ◽  
Farm Profit ◽  
Baseline System

Ewes with the fecundity Booroola (FecB) gene produce more lambs per ewe on average than ewes without the gene and offers a potential way to decrease greenhouse gas emissions (net and per unit animal product) without reducing lamb production if the lambs can be reared to market weights. Using a case study farm in south-west Victoria, a biophysical modelling study has previously showed that increased ewe fecundity from 1 to 1.5 lambs per ewe increased production by 27% and reduced net farm emissions by 21% for the same long-term stocking rate. In this study, a whole-farm economic analysis was used to investigate the relative merit of the same case study farm, with high-fecundity ewes, compared with a baseline system that represented a typical prime lamb enterprise in the region. An additional system comprising ewes with high fecundity at a lower stocking rate than the case study farm was also examined. The analysis was undertaken to establish which farm systems represented the most economically efficient use of all the resources that are employed over a run of years, and involved estimating the net present value of annual profits earned by the farm in each scenario, taking into account the total value of capital used. The potential revenue from the sale of carbon credits through the Carbon Farming Initiative was also investigated. After accounting for the additional costs involved, increasing ewe fecundity resulted in an increase in annual whole-farm profit compared with the baseline system, but risk, considered as the variability in farm profit, also increased. Decreasing stocking rate for the high-fecundity system reduced annual operating profit and net present value at a 5% discount rate, but had less risk compared with the higher stocking rate system. While both systems that incorporated high-fecundity ewes reduced greenhouse gas emissions, revenue from the sale of carbon credits was small compared with revenue from the sale of lambs, wool and culled ewes. Despite this, and assuming the required increases in fertility and weaning rates could be achieved consistently on-farm, ewes with high fecundity may offer producers the opportunity to increase production and profit as well as decrease greenhouse gas emissions.

A dynamic programming algorithm for optimization of uneven-aged forest stands

1994 ◽  
Vol 24 (9) ◽  
pp. 1758-1765 ◽  
Author(s):  
David J. Anderson ◽  
B. Bruce Bare
Keyword(s):  
Dynamic Programming ◽  
Interest Rates ◽  
Net Present Value ◽  
Initial Conditions ◽  
Dynamic Programming Algorithm ◽  
Basal Area ◽  
Management Problem ◽  
Present Value ◽  
Stand Management ◽  
The Impact

A deterministic dynamic programming formulation of the transition uneven-aged stand management problem is presented. Using a previously published northern hardwoods growth model, a forward recursive, discrete, two-state problem that maximizes the net present value of harvested trees at each stage is developed. State variables represent the total number of trees and the total basal area per acre. A neighborhood storage concept previously published is used to reduce the number of states considered at each stage. Two harvest allocation rules are used to assign the harvested basal area to individual diameter classes. Terminal end point conditions and stage to stage sustainability are not required. Results from four base runs of the model are presented and compared with previously published results. Each run produces significantly different optimal paths, with one showing a higher net present value than any previously published. Sensitivity runs illustrate the impact of changes in interest rates, width of neighborhood storage class, and initial conditions. Dynamic programming offers promise for analyzing uneven-aged stand management problems.

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