Open Pit Mining Operations Research Articles

Improving productivity at an open-pit mine through enhanced short-term mine planning

Productivity is improved by increasing the ratio of output to input. In an operating open-pit mine, improving the productivity of heavy mining equipment (HME) enables the unit cost of production to be reduced. To optimize HME productivity, the Kolomela open-pit iron ore mine transitioned to an enhanced short-term mine planning (STMP) process that supports the application of a manufacturing-type operating model. At the core of the enhanced STMP process is a focus on integration across the open-pit mining value chain. The interdependencies between mining activities are highlighted and emphasized, thus ensuring that mining activities are synchronized. The improvements related to HME productivity were monitored from 2019 to 2020. The utilization of mining area in the Leeuwfontein pit improved from 71% to 90%, and the blasting frequency reduced by 14% while the average blast size increased by 17%. The distance travelled during shovel relocations between mining phases reduced by 16%, and the lost time associated with drills relocating reduced by 53%. These productivity improvements resulted in an 11% increase in the loading rate of the main waste shovel at Kolomela from 0.9 Mt/month in 2019 to 1.0 Mt/month in 2020. The enhanced STMP process can be adapted to other open-pit mining operations.

Operations Research in Underground Mine Planning: A Review

At the time of this writing, the U.S. Geological Survey estimates that the average American-born human will need millions of pounds of fuels, minerals, and other extracted resources in his or her lifetime. Mining is a critical global industry, spanning all but one continent (Antarctica), with the highest-producing countries being China, the United States, Russia, Australia, and India. Increasingly, this demand is driving mining companies to explore and pursue deeper mineral deposits as near-surface deposits deplete. Correspondingly, there has been a significant rise in industry interest in applying operations research techniques to improve underground mine planning. Newman et al. [Newman AM, Rubio E, Caro R, Weintraub A, Eurek K (2010) A review of operations research in mine planning. Interfaces 40(3):222–245] present a review of such techniques, applied to both open pit and underground mining operations. We focus here on the advancements since that publication and concentrate on underground applications in metalliferous deposits, such as copper, iron, and gold.

Estimate of geohydrodynamic mode in operation of open pit mines in Almalyk ore field

With a view to safe open pit mining, the anticipated water inflows in a pit during construction are estimated. A geopermeation model is built for the whole Almalyk or field. The numerical geopermeation modeling of open pit mining used Groundwater Modeling System (GMS) as the most widely applied software system in wide-range problem solution in practical hydrogeology. The test ore field features difficult geological and hydrological conditions (multilayered structure of water-containing stratum, horizontal and vertical lithological and facial variability of aquifers and impermeable beds which are hydraulically interconnected in a varying degree, local extension of this variability). The modeling determines that groundwater level within the limits of local open pit mines conforms with the general laws of fluid flow with minimum levels in the valleys and maximum values at the watersheds and on the hillslopes. The computer-aided geopermeation modeling enables more carful calculation to add the analytical research, which makes it possible to gain insight into essence of an object, its peculiarities and regular patterns which are often indistinguishable without numerical modeling. The studies allow confident affirmation that the hydrogeological model images all major mechanisms of ground water in Almalyk ore field and in adjacent areas, and is applicable for hydrogeological predictions. The latter can help immediately respond changes in the behavior of ground water and eliminate failure in service of mining facilities in the test territories.

Unveiling unknowns: Practical application of InSAR for slope performance monitoring and risk management across multiple surface mines

The ability to monitor and predict slope failures in a surface mining setting is paramount for safely executing economically feasible open pit slope designs. Ground-based monitoring systems have proven to be effective for decades; however, with the geographical extensive nature of some mineral deposits, multiple open pit mining operations typically incur additional challenges of deploying and maintaining ground-based systems (compared with a single, large open pit). Monitoring strategies in the 2020s have significant opportunity to integrate satellite based InSAR (interferometric synthetic aperture radar) as part of the control measures depending on the expected failure mechanisms and risk profile. This paper uses case studies to explore the practical application of InSAR to ‘unveil unknowns’ for multiple open pit mining operations where ground monitoring capacity was previously constrained. Case studies include the retrospective analysis of historic slope failures, improving understanding of existing geotechnical hazards and improving engineering geological and slope stability models based on real slope performance data.

Case-based reasoning system for prediction of fuel consumption by haulage trucks in open-pit mines

The shovel-truck system is commonly used in open-pit mining operations. Truck haulage cost constitutes about 26% of open-pit mining costs as the trucks are mostly powered by diesel whose cost is escalating annually. Therefore, reducing fuel consumption could lead to a significant decrease in overall mining costs. Various methods have been proposed to improve fuel efficiency in open-pit mines. Case-based reasoning (CBR) can be used to estimate fuel consumption by haulage trucks. In this work, CBR methods namely case-based reasoning using forward sequential selection (CBR-FSS), traditional CBR, and Naïve techniques were used to predict fuel consumption by trucks operating at Orapa Mine. The results show that the CBR method can be used to predict fuel consumption by trucks in open-pit mines; the predicted values of fuel consumption using the CBR-FSS technique gave much lower absolute residual values, higher standardised accuracy values, and effect sizes than those of other prediction techniques on all the datasets used. The system will enable mine planners to know the fuel consumed per trip and allow them to take mitigation measures on trucks with high fuel consumption.

Measuring blast fragmentation at Nui Phao open-pit mine, Vietnam using the Mask R-CNN deep learning model

ABSTRACT Blast fragmentation size distribution is one of the most critical factors in evaluating the blasting results and affecting the downstream mining and processing operations in open-pit mines. Image-based methods are widely applied to address the problem but require heavy user interaction and experience. This study deployed a deep learning model Mask R-CNN to develop an automatic measurement method of blast fragmentation. The model was trained using images captured from real blasting sites in Nui Phao open-pit mine in Vietnam. The trained model reported high average precision scores (Intersection over Union, IoU = 0.5) 92% and 83% for bounding box and segmentation masks, respectively. The results lay a solid technical basis for the automated measurement of blast fragmentation in open-pit mines.

Cradle-to-gate life cycle assessment of beneficiated phosphate rock production in Tunisia

To improve the sustainable management of phosphorus, numerous LCA studies, using primary data, have been conducted for phosphorus recovery technologies from wastewater, but not for phosphate rock mining.This article addresses this issue by conducting a cradle to gate assessment of beneficiated phosphate rock production using primary data. This study aims to share an updated Life Cycle Inventory dataset of beneficiated phosphate rock production.The studied system is the open-pit mining operations and the wet beneficiation process located in the south of Tunisia. The functional unit is 1 kg of P2O5. Twelve environmental impact categories were assessed using the ReCiPe Midpoint method.The results of Life Cycle Inventory show that the average loss of phosphorus between mining operations, mechanical preparation, and the wet beneficiation is 0.3 kg of P2O5 per 1 kg P2O5. The losses occur mainly during the scrubbing and hydrocycloning. Compared to the production system in Florida, USA, according to the Ecoinvent database 3.4, the production of 1 kg P2O5 in Tunisia has higher Global Warming Potenzial, higher water depletion potential, higher PM10 emission, Photochemical oxidant formation, soil pollution potential, and human toxicity potential.In conclusion, primary data shows comparable results to the generic Life cycle Inventory of wet beneficiation phosphate rock in the Ecoinvent database. This study contributes to enlarge data about sedimentary phosphate rock extraction and beneficiation globally as currently only the USA and Morocco were reported in databases.

Development of new compositions for dust control in the mining and mineral transportation industry

Dust control in summer and winter periods is a topical problem associated with conducting open pit mining operations; however, at negative temperatures the additional requirements are imposed on dust suppressants. Preventive compositions are proposed, in which light and heavy gas oils, obtained from catalytic cracking and delayed coking, are used as base components. Involvement of heavy fractions allows to increase the flash point, thereby reducing the flammability of dust suppressant, improve its adhesion properties by increasing the content of polyaromatic hydrocarbons and reduce the cost of the final product. In order to improve low-temperature and adsorption properties of developed dust suppressants, heavy oil residues (cracking residue and tar) are included in their composition in various concentrations: 2-10 wt.%. Alternative compositions of dust suppressants, obtained by water emulsification of vinylated alkyd oligomer, are developed; the ability of this dispersion to form strong films on dusty surfaces is examined. The efficiency of using aqueous solution of vinylated alkyd oligomer as a summer dust suppressant is demonstrated. The results of this study include the development of new preventive compositions with improved low-temperature properties and confirmation of the theoretical part of the study by the results of performance tests on a laboratory facility.Alternative compositions of dust suppressors have been developed, which were obtained by emulsifying a vinyl alkyd oligomer (VAO) in water; the ability of this dispersion to form strong films on dusty surfaces has been studied. The efficiency of using an aqueous solution of vinyl alkyd oligomer in the summer period as a dust suppressant is shown. The results of this study are the development of new prophylactic formulations with improved low-temperature properties and confirmation of the theoretical part of the study by the results of tests of operational characteristics in a laboratory facility.

Evaluation of the Influence of In Situ Stress on the Stability of Mine Pit Walls: A Case Study of Songwe Mine

The investigation of the influence of in situ stress in Open Pit Mine (OPM) projects has not been accorded a deserved attention despite being a fundamental concern in the design of underground excavations. Hence, its long-term potential adverse impacts on pit slope performance are overly undermined. Nevertheless, in mines located in tectonically active settings with a potential high horizontal stress regime like the Songwe mine, the impact could be considerable. Thus, Using FLAC3D 5.0 software, based on Finite Difference Method (FDM) code, we assessed the role of stress regimes as a potential triggering factor for slope instability in Songwe mine. The results of the evaluated shearing contours and quantified strain rate and displacement values reveal that high horizontal stress can reduce the stability performance of the pit-wall in spite of the minimal change in Factor of Safety (FoS). Since mining projects have a long life span, it would be recommendable to consider “in situ stress-stability analyses” for OPM operations that would be planned to extend to greater depths and those located in tectonically active regions.

Optimisation of shovel-truck haulage system in an open pit using queuing approach

Open-pit mining operations involve loading and hauling of material from the pit to the processing plant or waste dump depending on the ore grade. These two activities account for more than 50% of total operating costs of the mine. There are several loading and hauling systems that are employed depending on the geometry of the ore body. This study applies a shovel-truck haulage system in a limestone open-pit mine to optimise the productivity of the plant using queuing theory technique. This study developed a model using Mat-lab software to calculate the inter-arrival rate and service rate for different numbers of trucks subjected to the same haulage system. The current system used at the limestone cement plant quarry has an inter-arrival rate of 24 trucks/hour and a service rate of 10 trucks/hour with 16 trucks and 2 shovels in the system. Using this data on the developed model, it is evident that when the number of trucks increases to 12, the system daily production increased up to an optimal point of 7644.52 tonnes/day. Thereafter, an increase in the number of trucks reduced the truck productivity, hence reducing the system production and increasing the cost per tonne of material hauled.

Investment appeal assessment of Pt-rich and Cu-Ni deposits of Monchegorsky ore district in current conditions

Development potential and investment attractiveness of PGM deposits (Monchegorsky ore district) are discussed. By the late 2020, the reserves of these deposits were approved based on results of a feasibility study review assessment in the State Reserve Commission and TsNIGRI approval. In current mineral market conditions (including high Pd price), the most attractive development projects are Vuruchuaivench deposit comprising 4 areas (Plast 300, Vuruchuaivench, Yuzhnosopchinsky and Arvarench), NittisKumuzhya-Travyanaya occurrence and Loipishnyun area. In terms of reserves, ore grades and proximity to processing plants, these potential mining projects are less expensive if developed concurrently. The paper presents recommendations for PGM deposit opening, development and mining using advanced mining equipment in open-pit and underground mining operations, ore conveying and processing plant tailings disposal to infill underground workings. Economic estimates were made supporting development viability of the above deposits within Monchegorsky ore district.

Optimization-based dispatching policies for open-pit mining

We propose, implement, and test two approaches for dispatching trucks in an open-pit mining operation. The first approach relies on a nonlinear optimization model that incorporates queueing effects to set target average flow rates between mine locations. The second approach is based on a time-discretized mixed integer programming (MIP) model. The MIP model is difficult to solve exactly in real-time operations, so we present a heuristic that quickly produces high-quality feasible solutions. We test the dispatching policies by building a discrete-event simulation model of an open-pit mine. We present a full computational study of the two policies in which we perform output analysis on key metrics of the open-pit mine simulation. Results indicate that the MIP-based dispatching policy consistently outperforms the more commonly-used average flow rate dispatching policy on open-pit mines in a wide variety of operations settings.

A mathematical model for open pit mine production scheduling with Grade Engineering® and stockpiling

This paper presents the development and implementation of an innovative mixed integer programming based mathematical model for an open pit mining operation with Grade Engineering framework. Grade Engineering comprises a range of coarse-separation based pre-processing techniques that separate the desirable (i.e. high-grade) and undesirable (i.e. low-grade or uneconomic) materials and ensure the delivery of only selected quantity of high quality (or high-grade) material to energy, water, and cost-intensive processing plant. The model maximizes the net present value under a range of operational and processing constraints. Given that the proposed model is computationally complex, the authors employ a data pre-processing procedure and then evaluate the performance of the model at several practical instances using computation time, optimality gap, and the net present value as valid measures. In addition, a comparison of the proposed and traditional (without Grade Engineering) models reflects that the proposed model outperforms the traditional formulation.

Impact of Coal Mining on the Moisture Movement in a Vadose Zone in Open-Pit Mine Areas

Long-term dewatering of groundwater is a necessary operation for mining safety in open-pit coal mines, as extensive dewatering might cause ecological problems due to dramatic changes in moisture movement in the soil, especially in ecologically fragile areas. In order to evaluate the impact of the coal mining operation on moisture movement in the vadose zone and vegetation, this paper presents a quantitative methodology and takes the Baorixile open-pit coal mine as a study example. A long-term in situ experiment (from 2004 to 2018), laboratory analysis, and numerical modelling were conducted to analyze the mechanisms and relationship among the dropping groundwater level, the vadose-zone moisture, and the ecological responses in the grassland area. The experiment data and modelling results suggest that groundwater level dropping during open-pit mining operation has limited influence on the vadose zone, exhibiting a variation of capillary water zone within a depth of 3 m while the vadose zone and soil water zone were at least 16 m deep. The critical evaporation depth of ground water is 8 m. The long-term influence radius of groundwater dewatering is about 2.72 km during the Baorixile mining operation, and the groundwater level change mainly influences the lower part of the intermediate vadose zone and the capillary water zone below 16 m, with little influence on the moisture contents in the soil water zone where the roots of shallow vegetation grow. The results from this study provide useful insight for sustainable development of coal mining in ecologically fragile areas.

Recycling of marls from phosphate by-products to produce alkali-activated geopolymers

During open-pit mining operations of phosphates, huge volume of rocks by products are accumulated and deposited in the mine site. The aim of this paper is to investigate the use of marls as an only aluminosilicate precursor to produce alkali-activated geopolymers. Marls from Moroccan phosphate basins are composed of carbonates, quartz and clays. Raw marl was dried, grinded and calcined at 750 °C. After the heat treatment, the calcined powder was activated using a strong alkali solution, which is a mixture of sodium hydroxide and sodium silicate with a ratio of 0.5. The physical and chemical properties of raw and calcined marls were analyzed using TGA, BET, Pycnometer, particle size analyzer, XRF, XRD, FTIR and SEM. Furthermore, elaborated geopolymers were characterized after 7 and 120 days of curing at ambient temperature using XRD, XRF, TGA, SEM and the mechanical behavior was tested by measuring the compressive strength. The results showed the formation of both; C-A-S-H (Calcium aluminum silicate hydrate) and N-A-S-H (Calcium aluminum silicate hydrate) gels with a compressive strength of 38 MPa confirming that marls from phosphate extraction by-products could be used as a source for the elaboration of geopolymers.

A mixed integer programming based cut-off grade model for open-pit mining of complex poly-metallic resources

The mineral supply chain in an ideal open-pit mining operation constitutes a set of sequential stages including a surface mine or an open-pit, a processing plant and a refinery or market. Cut-off grade defines the flow of materials from the mine to subsequent stages within this mineral supply chain. This underlines the significance of cut-off grades in establishing the economic viability of an operation. However, only heuristic methods are available for defining the cut-off grade policy for complex mineral resources (orebodies) that constitute multiple economic minerals. This article proposes a new mixed integer programming based mathematical model that generates an optimal cut-off grade policy for open-pit mining operations that mine, process and refine or market multiple metal products. An implementation of the new method in three separate case studies reflects better performance (i.e., 24%, 36% and 27% higher net present value) against available heuristics.

Safe Operation of All-Wheel Drive Articulated Dump Trucks on Large Slopes in Deep Open-Pit Mines

The analysis have been carried out for the production of all-wheel drive articulated dump trucks. The practical experience of operation of dump trucks as open-pit transport has been analyzed. The paper describes the technical characteristics of some models of articulated dump trucks of Russian and Belarusian production. The paper describes the examples of transportation of rock mass at enterprises of Russia and abroad. The paper points up the special aspects for making the organizational, technological and design decisions in the implementation of articulated dump trucks. The paper shows the experience of operation of all-wheel drive articulated dump trucks in open-pit mining. It has been established that articulated dump trucks allow to increase the efficiency of mine development at the stage of construction and commissioning of mining and processing plants, especially in geographically remote and inaccessible territories The measures have been developed for safe operation of all-wheel drive articulated dump trucks in open-pit mining at the development of deep-seated mineral deposits.To implement the program of import substitution of all-wheel drive articulated dump trucks it is necessary to perform market research to study the possible market of consumption of vehicles of this class at open-pit mining operations in order to justify the prospects for provision of the Russian production market.

A simulated annealing based approach for open pit mine production scheduling with stockpiling option

Production scheduling plays a pivotal role in successfully executing any open-pit mining operation. It defines the most profitable extraction sequence of mineralized material from the ground subject to various physical and operational constraints. Different mathematical formulations have been proposed to achieve this goal; however, solving these models for real-sized deposits with multiple constraints is a challenging and computationally expensive task. Moreover, the inclusion of stockpiling option further complicates this task. The stockpile option adds flexibility to the operation by allowing excess low-grade ore storage for processing at a later stage when processing capacity is available. Accurate integration of stockpiling option in the production scheduling process through mathematical approaches leads to nonlinear constraints. This could further complicate the already challenging task since linear approximation of these nonlinear constraints could lead to sub-optimal results. Metaheuristic techniques could play an essential role in handling such situations. Though several attempts have been made to solve this problem through these techniques, little effort has been made to incorporate stockpiling option in the optimization process. This article presents a Simulated Annealing based approach for production scheduling of open-pit mines with stockpiling option. The proposed approach uses a stockpile and a greedy heuristic with a Simulated Annealing algorithm to achieve this goal. The greedy heuristic improves the Simulated Annealing algorithm's computational efficiency by managing its randomness. The proposed approach's performance and efficiency are demonstrated through three case studies (A, B, and C) under different algorithmic settings. Results of these case studies reveals that compared with the CPLEX solver, the proposed approach produced near optimal solution, within reasonable amount of time, proving the applicability of the proposed approach.

Determination of semi-mobile in-pit crushing and conveying (SMIPCC) system performance

In-pit crushing and conveying (IPCC) systems are currently receiving more attention as a result of the existing characteristics of open-pit mining operations and what is likely to happen in the future. The use of trucks and shovels for loading and hauling has been used as a dominant system in open-pit and open-cast mines due to their large-scale operations compared with other mining methods. Presently, it has become more required than ever to minimise the cost of truck haulage, which reports for approximately half of the operating costs of the mining operation. Therefore, trucking costs can be considerably minimised by installing the crushers inside the pits. With the increased popularity of IPCC systems, it is necessary to investigate the overall performance and productivity of the systems. This paper employs mine productivity index (MPi) to determine the productivity of semi-mobile IPCC. From this study, it is evident that a reduction of number of loading equipment necessitated an increase in shovel’s bucket size and reduction of the trucks by 33%. Additionally, this study found that the scenario with more than one loading equipment has a higher MPi of 71% compared with the scenario with one loading equipment having an MPi of 67%. Further, SMIPCC scenarios record better MPi compared with the current truck-shovel transportation system which has an MPi of 67.14%.

Risk-Based Thinking as a Basis for Efficient Occupational Safety Management in the Mining Industry

This article deals with the role and the place of risk-based thinking in today’s occupational safety and health (OSH) systems used by mining companies. A brief survey on modern challenges and pressures affecting companies, as well as on the structure of supply chains, is given. It is demonstrated that, despite all measures and actions that are being taken, occupational injuries in the mining sector: (a) remain a matter of serious concern and (b) should be examined and investigated through the lens of the company’s complexity. The objective of the article is two-fold: to trace the evolution of risk-based thinking from quality management systems towards OSH management systems and to demonstrate how this approach can be implemented by a company performing open-pit mining operations. The matrix method along with the Fine and Kinney’s method was used in assessing OSH risks, and the checklist method along with a Strengths-Weaknesses-Opportunities-Threats (SWOT)analysis was used while assessing OSH opportunities. The results of the study make it possible to conclude that risk-based thinking incorporated into an OSH management system can be a robust and efficient instrument for OSH planning and implementation. This article contains an example of assessing OSH risks and opportunities for a dragline operator and also discusses the possible ways of using the data on the OSH risks and opportunities that were identified in OSH activities. The final part also contains comments and reflections on various risks mining companies are facing nowadays.