Open Pit Limits Research Articles

Open pit limit optimization considering the pumped storage benefit after mine closure: a case study

Repurposing a closed mine as lower reservoir is a cost-effective way for the construction of pumped storage hydropower (PSH) plant. This method can eliminate the expenses of mine reclamation, reservoir construction, and land acquisition, resulting in significant cost savings and benefits for the PSH project, known as the PSH benefit. The construction of PSH plants within a closed mine is divided into surface mode and semi-underground mode in this paper. Through a general comparison of two in-situ cases, the finding highlight that the surface mode can achieve a larger potential installed capacity and lower construction cost. Furthermore, the PSH benefit is quantified and internalized as an economic parameter in the ultimate pit limit (UPL) optimization by allocating it into unit ore. Taken an undisclosed open-pit iron mine as example, the UPL is optimized by considering the PSH benefit. The internalized PSH benefit is calculated to be 6.59 CN¥/t when the installed capacity is 2000 MW, and ore amount within the optimized UPL is increased by 1.4%. The results indicated that the PSH benefit does influence the shape and size of UPL, but not significantly. Besides, converting several bottoms in a single open-pit into lower and upper reservoirs presents more challenges for UPL optimization, which further explorations is needed.

Assessment of energy conservation potential and cost in open-pit metal mines: Bottom-up approach integrated energy conservation supply curve and ultimate pit limit

Mitigating energy consumption and greenhouse gas (GHG) emissions in the metal mining industry heavily depends on the employment of energy conservation technologies in each individual metal mine. However, predicting the energy conservation potential and associated cost for a specific mine is difficult, especially considering the interaction between technology employment and open-pit limit variation. Therefore, this study integrates the conventional energy conservation-supply-curve (CSC) approach with the ultimate-pit-limit (UPL) analysis in the estimation of energy conservation potential and cost due to technology application. The results from the case study show that conventional CSC analysis provides overestimated potential with underestimated cost under market-based promotion policy. On the other hand, a target-responsibility-system-based (TRS-based) provides underestimated potential with overestimated cost. Sensitivity analysis shows that energy price has the largest impact on the energy conservation potential and associated cost. The policies that raise energy and carbon prices contribute not only to mitigating energy consumption, but also to reducing associated costs, even though they are accompanied by a reduction in mineral supply. This study suggests that the policy that subsidizes conserved energy should be integrated with a TRS-based policy to mitigate the elimination of energy conservation potential due to expansion of the open-pit limit.

Extended Ultimate-Pit-Limit Methodology for Optimizing Surface-to-Underground Mining Transition in Metal Mines

The transition from surface mining to underground is a critical issue for metal mines. The commonly cited procedure cored by ultimate-pit-limit (UPL) methodology is restricted to maximize the profit from both surface and underground mining, due to the absence of the integration of the profit from either of them. Under the target for such maximization, this study proposes a new optimization approach, which directly relates the design of open-pit limit and underground stopes, by equalizing the marginal profit from either surface or underground mining. The variation of the crown pillar size is involved in this approach. The proposed approach is applied to the Dagushan iron mine, and results show the total profit increased from 3.79 billion CNYs (original design by conventional UPL methodology) to 4.17 billion CNYs (optimal design by the proposed approach), by 9.91%. Moreover, the marginal profit from surface and underground mining, as well as total profit, of all possible designs of surface-to-underground mining transition in Dagushan iron mine is calculated to validate the proposed approach. When the marginal profits satisfy the criterion of the proposed approach, the maximum value of the total profit appears, and this demonstrates the proposed approach is robust to maximize the total profit in surface-to-underground mining transition. This work contributes to existing literature studies primarily from practical aspect, by providing a unified approach to optimize the transition from surface to underground mining.

Open pit limit optimization considering economic profit, ecological costs and social benefits

Pit limit design has, up to date, focused mainly on maximization of economic profit alone, with environmental and social issues largely ignored. This paper focuses on incorporating both environmental and social issues in the pit limit design process and provides an approach to pit limit optimization that is in compliance with sustainable development. The case study demonstrates that ecological costs have a substantial down-sizing effect and social benefits have a substantial up-sizing effect on the optimal pit limit. When the ecological costs are factored in, the optimal pit limit is 37.5% smaller than the economically optimal pit limit. However, when the social benefits are factored in, the optimal pit limit is 48.3% larger than the economically optimal one. The overall optimal pit limit, with the economic profit, ecological costs and social benefits simultaneously considered, is a result of balancing conflicting goals of maximizing economic profit, minimizing ecological cost, and maximizing social benefit.

Method for optimizing the shell of open pit mines based on parallel computing

One of the main stages in design of mineral development process is solution of finding optimal open pit problem. It is necessary to take into account the spatial distribution of mineral components and the allowable slope angles of the sides during solving this problem. The basis for performing calculations to optimize the extraction of reserves is a digital block model of the mineral deposit. The larger and more accurate block model of the ore deposit requires more computationally complex calculation process. In this regard, using of parallel computing in this area is very relevant. The importance of solving this problem determined by the need to have an accurate model of the open pit at various stages of its development. This model depends from current cost of useful components and the costs of their extraction. This task formulated as the Ultimate Pit Problem (UPIT). Existing approaches for solving this problem does not use modern high-performance computing approaches. This complicates analysis of large models using existing methods. The long data processing time makes it difficult to increase the accuracy of the constructed quarry models, which in turn negatively affects decision-making on the field development plan and entails lost profit. In this paper analysed the methods of computer modelling open pits from the position of parallelizing computations during profit optimization and proposes a mathematical formulation of the problem of searching for open pit limits based on block extraction order graph.

Разработка web-приложения для оптимизации и визуализации форм карьеров рудных месторождений

Разработка web-приложения для оптимизации и визуализации форм карьеров рудных месторождений

Research of Optimal Transition Depth in opencast-underground combined mining

It will be of great significance to the accurate evaluation of the deposit’s economic potential and the improvement of economic performance and production capacity for mining enterprise, if the border was considered scientifically. Open-pit limit was optimized by mining software on the basis of combined mining cost analysis. The principal of combined mining transition depth determination was confirmed through the comparison of open-pit mining and underground mining costs. This paper will provide a reference for the practical application of combined mining transition depth determination.

A review of underground stope boundary optimization algorithms

Optimization is a key aspect of the mine design and planning process. A number of algorithms and techniques have been developed to optimize mines. However, most of these techniques focus on open pit optimization to an extent that some authors argue that open pit limit optimization has reached saturation level. Optimization of underground mines only received attention in recent decades and has been focused on three main areas including stope boundary optimization. This paper reviews and analyzes literature on algorithms developed to date for stope boundary optimization. There has been an increase in the number of algorithms developed to optimize stope layout. Most of these algorithms are heuristic, consider stope dimension as one of the constraints and optimize layouts in three dimensional space. However, all these algorithms are based on deterministic orebody models, therefore, fail to consider uncertainty intrinsic in ore deposits. Also, none of these algorithms guarantee optimal stope layout solution in three dimension. Consequently, there is a need for further research in the field of stope boundary optimization.

МОДЕЛИРОВАНИЕ КАРЬЕРОВ РУДНЫХ МЕСТОРОЖДЕНИЙ НА ВЫСОКОПРОИЗВОДИТЕЛЬНЫХ ГИБРИДНЫХ ВЫЧИСЛИТЕЛЬНЫХ СИСТЕМАХ

This paper describes the principles of supercomputer simulations of the searching open pit limits on high performance hybrid computing systems using parallel genetic algorithm.

Optimising open pit mine scheduling taking into consideration time value of money and mining restrictions

In an earlier study, the authors introduced the new algorithm that allows for a definition of open pit limits taking into consideration time value of money. This study presents further expansion of this algorithm that allows determining the optimum mining sequence and optimum width of pushbacks, in a manner that maximises the net present value (NPV) of a deposit. The algorithm combines dynamic programming and mining heuristic, and allows for incorporation of price vectors, costs, cut-off grades and other mine design parameters. Test runs of the algorithm conducted by the authors have led consistently to pits and mining sequences with higher NPV values than those generated using parametric techniques.

Study on the Economic Stripping Ratio in Oil Shale Open-Pit Mine Used in Refinery

The number of oil shale mines which adopted open pit mining increased with the increasing of oil price, in recent years. The economic stripping ratio is an important basis to determine open pit limit. Since there is no national or occupational standard about economic stripping ratio in open-pit oil shale mine, the economic stripping ratio has calculated by adopting refined oil price. This research has guiding significance for oil shale open-pit mine exploitation.

Effect of highwall parameters on the open pit operation and limits

The article addresses the open pit mining of lightly pitching coal below different surface topography. Based on the analysis of the effect exerted by highwall angle on the current stripping ratio, suggestions are made on possible improvement in the open pit mine performance and extension of its life by changing the slope angle of the open pit highwall.

露天採掘技術の最近の動向と将来設計 ＩＩ‐３ オープンピット最終形状の最適化手法（ＢＰＩＴＣ法）の提案と金属品位推計シミュレーションデータを用いた初期Ｆ／Ｓ

露天採掘技術の最近の動向と将来設計 ＩＩ‐３ オープンピット最終形状の最適化手法（ＢＰＩＴＣ法）の提案と金属品位推計シミュレーションデータを用いた初期Ｆ／Ｓ

The MCS/MFNN algorithm for open pit optimization

ABSTRACT Many algorithms and their modifications have been used to design and optimize open pit limits. These algorithms have provided mine planning engineers with pertinent information in designing, optimizing and extracting ore reserves by open pit technology. However, they do not address the random field properties associated with the ore grades and reserves, and thus, fail to yield the truly optimized pit limits in any time horizon. In this paper, a new algorithm, MCS/MFNN, which overcomes these limitations is developed to optimize open pit limits. The random field properties of the ore grade and reserves have been modelled using the modified conditional simulation based on the best linear unbiased estimation and local average subdivision techniques. Artificial neural networks are then used to classify the blocks based on their conditioned economic block values. The error back propagation algorithm, in the neural networks, is used to optimize the pit limits by minimizing the desired and actual outputs error in a multilayer perceptron under the pit wall slope constraints. The MCS/MFNN algorithm is used to optimize a section of the gold deposit of the Sabi Heap Leaching Gold Project in Zimbabwe. The results of this algorithm are the same as that obtained from the Lerchs-Grossman's 2D algorithm, but in random multivariable states, the MCS/MFNN algorithm is the most suitable for pit optimization. The method is also fast since it mimics the operation of the brain in the solution of the pit optimization problem.

Optimization of open pit limit with dynamic-economy analysis

Abstract The common weakness for various existed optimum methods of open pit limit design lies in the application of static-economy analysis without taking into account the time value of money. The principle and method for dynamic optimization of open pit limit analysis comprehensively with other decision-making factors are brought out. A mathematical model series for surface mine long term planning (SMLTP) have been developed as a strong tool for solving this problem. Further application of comprehensively dynamic optimization method in place of traditional isolated, static method for open pit limit analysis is in prospect.

The economics of computerized open-pit design

ABSTRACT This paper presents the economic aspects of computerized open-pit design. The objectives of open-pit design and the design methods are reviewed. Factors to be considered in establishing the profit matrix are detailed and the implications of uncertainties discussed. A simplified case study illustrates particular aspects of establishing the profit matrix and the resultant open-pit limits achieved by varying the input parameters within the ranges of possible values.

Dynamic programming with colour graphics smoothing for open-pit design on a personal computer

Dynamic programming is a technique which has been used to design the optimum final surface mining pit limit. In using dynamic programming there is a trade-off: if the geometric constraints are specified too strictly, the pit limit will not be the optimum, but if they are specified more loosely, then the computed pit contours must be smoothed. The smoothing process has usually been manual and is time consuming. In this paper a colour graphics computer routine is presented. This not only facilitates the smoothing but also has the following benefits: open-pit limits can be designed interactively on a personal computer; pit designs that are closer to the economic optimum can be obtained; and the engineer can bring his or her own experience and intuition to bear on the final open-pit design.