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By D. Chakravarty, G. Samanta, B. Samanta

The present study highlights the planning and design aspects of a well-known openpit copper deposit in India. The mine has been operational since 1982 and presently reaches a depth of 168 m below the surface. The present planning effort has been given due consideration in view of the recent upsurge of copper prices in the global market. The prime focus of the study has been directed towards examining the possible extent of final pit beyond the current pit outline and generating an extraction sequence of future mining operations. To this end, an orebody model of the deposit has been developed and the optimized pit has been derived using L-G 3D algorithm. A sensitivity analysis has also been performed to scrutinize the possible effects of the changing economic scenarios on the ultimate pit configuration. It has been observed that with the current production rate, mine life can be extended another 40 years. With a five-year production plan, these materials can be extracted in eight push-back schemes. The extraction sequence of these push-backs has been outlined in this paper.

Jan 1, 2011

By G. C. S. Burns

"A system has been developed to simulate the mining of the Mufulira orebody. The main output from the system is a picture-gram from which the start date and effective life of all proposed mining faces can be measured. This information provides schedule dates for the completion of major capital development projects and stope preparation activities.The orebody must be divided horizontally into main levels and vertically into blocks of equal interval. Ore reserves are defined by specifying the tonnage contained in each block and main level. Mining faces are defined by their co-ordinates, and may themselves be split into sublevels. The simulation maintains an echelon between contiguous sublevels. Other face parameters control the speed of mining, the availability and relative priority of the face.The required production from each crusher/shaft system is specified. The technique of simulating the mining process in order to achieve the required production is described."

Jan 1, 2014

By Kadri Dagdelen

Recent trends of the mining project show that there will be more and more mechanized, largescale mining operations with complex process options to make low grade deposits economically feasible to develop. The global optimization of large scale, complex mine operations will become more important for the future mining. To serve the industry?s future needs, the OptiMine® software program is developed based on expertise gained at the Colorado School of Mines (CSM) for more than two decades, by using the special solution methodology based on the Mixed Integer Linear Programming (MILP) technique in the Operations Research (OR). The program has been beta-tested on more than 20 projects as a multi-time period scheduling and cutoff grade optimization tool that handles large scale open pit and underground mining operations involving complex process options, many stockpiles and dumps, blending requirements, and truck hour limitations. In each project, various operational options are evaluated in OptiMine® to develop strategic planning to help defining company?s strategies and directions. This paper demonstrates how the OptiMine® can be used to optimize a large scale, complex production scheduling problem on a case study coming from real world project. The case study describes multi-pit mine production scheduling optimization with pit backfills in such a fashion that acid generating waste rocks are encapsulated to minimize environmental impact.

Oct 1, 2009

By Leena Korkiala-Tanttu, Ilkka Vähäaho, Juha Forsman, Paavo Lahdenperä, Kalle Rantala, Osmo Korhonen

"District of Arabianranta (Helsinki, Finland) has been founded on an old seabed, which was filled with miscellaneous soil materials. The subsoil consists of very low shear strength clays and organic clays (gyttjas). The soil was moving towards the sea at a rate of 1050 mm/year, because of filling on top of the soft subsoil. In the middle of 1990’s it was decided to build a residential area to Arabianranta, because it is located only 5 km away from the downtown. To inhibit the movement of soil, it was planned to build this 700 m long deep mixed column-wall barrier along the shore of Arabianranta in the years 1997–2005. A lot of instrumentation and inclinometers were analyzed and it was noticed that the column-wall remains at its place and the displacement rate inside the wall has been only 0.44.6 mm/year after construction works. Nevertheless, the displacement of soil at the landward side of the column-wall is still 1.25.1 mm/year. The soil at the seaside of the barrier is also moving towards the sea 12.922.2 mm/year. Another problem might be displacements of soil near the places where the column-wall ends (tails).1. INTRODUCTIONArabianranta district (Helsinki, Finland) has been an industrial, storage and wasteland area for a long time. Developing this area into a residential area was earlier considered too expensive, so it has been constructed during last decade. The organic clay layers (gyttjas), which have weak shear strength and high water content, were covered by various layers of fillings done in different phases. Because of the fillings, the area was not only consolidating, but also moving horizontally 1050 mm/year towards the sea due to the fact that the frictional soil under clay layers slopes towards the sea. A trial deep mixed structure was constructed in 1997 to inhibit the horizontal displacements of soil. The actual construction of the columnwall was completed in 2000-2005 with overlapping deep mixed cement columns on the seaward boundary. The barrier was built so that the horizontal movements would not risk the pile foundations at Arabianranta. The length of the barrier is about 680 m and width varies between 1220 m. There is a great amount of instrumentation near the barrier (inclinometer casings and other measuring devices). All this measuring information has been collected and analysed at 2014 to find out how this deep mixed column-wall has affected the horizontal displacements."

Jan 1, 2015

By S. Odell

The Bureau of Land Management (BLM) has constructed two biochemical reactor systems (BCRs) to treat mining influenced water from the Forest Queen Mine near Silverton, CO. The bioreactors coupled with a natural wetland provide treatment to the Forest Queen Mine drainage. The central objective of this paper is to review the performance of the bioreactors and wetland treatment system. The bioreactors have been in operation for nine years and along with the natural wetland are still removing a high percentage of the influent metals.

Jan 1, 2010

By P. F. Ziemkiewicz

This project evaluated the performance of nine passive treatment methods by studying 137 treatment units in eight eastern states. Performance was normalized according to construction cost, projected service life and tons of acid load treated. Results were dimensioned as $/tons of acid load treated/year. These costs were then compared to those of chemical treatment. Sites that achieved acid load reductions at costs below those of chemical treatment were considered successful. In addition to evaluating the performance of the treatment methods, this paper describes the various passive treatment systems, their applications and performance data for individual treatment units.

Jan 1, 2003

By Spencer Ness, Yazen Khasawneh, William Tjaden, Mohammad Nassim

The evaluation of long-term performance of the wind turbine structures is essential in lowering the Levelized Cost of Electricity (LCOE) from wind sources. The required maintenance of the wind turbine foundation during the design-life time of the wind turbine may result in escalated cost, if not properly evaluated during the planning and designing phases. The degradation of the foundation soils’ stiffness due to the accumulation small plastic strains resulting from normal and/or extreme operating cyclic loading may result in escalating the O&M cost. The foundation’s stiffness degradation will result in a shift of the wind turbine system natural frequency, which may result in amplifying the vibrations generated at the hub. The anticipated shift of the wind turbine system natural frequency during the design-life time should be investigated through numerical simulations of the anticipated dynamic loading utilizing soil constitutive models that are capable of capturing the foundation stiffness degradation due to the accumulation of such small plastic strains. This study presents the validation of an element model that will be used to evaluate the performance of existing and/or proposed constitutive model.

Oct 1, 2022

By L. W. T. Weitzel

"This paper reviews the Falconbridge- SMRQ’s Raglan project in northern Quebec and the process that was used in developing its current long-term mine plan. Challenges were many and not only limited to the longevity of the project, numerous ore deposits (both underground and open pit), and a 40 km property strike length. As a result of its remote northern location, other factors such as progressive reclamation, leachable mine waste, water treatment, and waste management were also part of the plan. A combination of modern planning tools were used to formulate the plan including DataMine, Mine 2-4D, AutoMod Simulation, and an Excel-based financial spreadsheet to bring the total plan together. The focus of the paper is to show the complexity of modern mine planning and associated economic modelling of mine processes. IntroductionThe Raglan project is located 1660 km directly north of Quebec at the northern tip of the Quebec Peninsula in Nunavik. The main property is 40 km in length stretching from the Donaldson airport area at the eastern edge of the property to East Lake at the western edge. The Deception Bay port is 90 km north of the main complex/mill situated at Katinniq which lies approximately in the middle of the property (Fig. 1). The mine processes 1 000 000 tpy of ore from both open pit and underground sources. The mill is forecasted this year to produce more than 150 000 t of concentrate grading more than 18% nickel. All personnel and critical cargo are transported to the site via a company-leased 737 jet from Rouyn-Noranda where the main administration office is located. The majority of cargo is shipped to the site via Deception Bay from Quebec and on the return trip, nickel concentrate is shipped back. From Quebec, the nickel concentrate is sent by rail to the Falconbridge smelter in Sudbury and on the reverse rail haul, nickel matte from the smelter is sent to Norway via Quebec."

Jan 1, 2003

By G. McIsaac

This paper discusses the formulation of a linear program with the objective of maximizing the cash flow of the long-term plan of an underground operation. A mine is split into eleven independent ore zones, each characterized by its reserves, required development, and mining method. Based on practical considerations, maximum rates are set for each zone?s development and production capacity. For the total mine plan, a minimum daily production rate is set along with a minimum feed grade to the mill. A maximum daily development capacity is set based on the equipment and labour available. Proven and probable ore is mined preferentially over possible ore in the early years of the plan. Also, the fixed cost of operating the mine is taken into consideration whenever mining activities take place. Once the linear program is solved, it can be critically reviewed, and unrealistic results can be identified. Some resource allocations constraints can then be changed in certain sectors, and new results can be analyzed. ?Whatif? scenarios can also be examined, such as determining the impact of hiring a contractor to develop a given sector, or dropping an ore zone completely from the plan.

Sep 1, 2005

By G. McIsaac

"This paper discusses the formulation of a linear program with the objective of maximizing the cash flow of the long-term plan of an underground operation. A mine is split into eleven independent ore zones, each characterized by its reserves, required development, and mining method. Based on practical considerations, maximum rates are set for each zone’s development and production capacity. For the total mine plan, a minimum daily production rate is set along with a minimum feed grade to the mill. A maximum daily development capacity is set based on the equipment and labour available. Proven and probable ore is mined preferentially over possible ore in the early years of the plan. Also, the fixed cost of operating the mine is taken into consideration whenever mining activities take place.Once the linear program is solved, it can be critically reviewed, and unrealistic results can be identified. Some resource allocations constraints can then be changed in certain sectors, and new results can be analyzed. “Whatif” scenarios can also be examined, such as determining the impact of hiring a contractor to develop a given sector, or dropping an ore zone completely from the plan."

Jan 1, 2005

By D. E. Kraushaar

Ruhrkohle in West Germany evaluates and compares the net present values of long-term periods from its coal mines by a computer assisted long-term planning system. Two main parts of this system are computer programs for the prediction of: (a) mineable reserves and their distribution in longwall panels as a function of dependent geological variables; (b) daily outputs and costs of longwall panels as a function of dependent geo- logical, layout and operational variables. This paper describes the investigations, which ended in the above computer programs: ? the collection of information from past workings and their organization in databases; ? the statistical evaluation of the databases, and ? the resulting correlation formulas. The correlation formulas vary the mean dependent variables as a function of independent variables which can be indicated with high reliability for planning projects in the long run. The system thus serves the purpose of facilitating long-term planning and excluding biased individual judgement of local planning staffs.

Jan 1, 1987

By F. Leschhorn

A computer model for long-term production scheduling is presented. By combination of different operations research algorithms it has been possible to design a system which is able to solve difficult long-term planning problems. The practical application of the model by a west-german hard coal mine is shown. It is proven that the EDP-model provides substantial support to the planning engineer by solving complex optimization problems.

Jan 1, 1989

By Daryl E. Radcliffe

The Bureau of Mines, as part of an agreement with the Bear Coal Co., Somerset, Col o., evaluated the response of a coal mine roof to time lapse. Time lapse, the interval between exposure and support of the roof, was studied using both instrumentation and statistics. Instrumentation studies were designed to equate displacement and rates of displacement with areas of roof left unsupported from 15 minutes to more than 4 days. A statistical study was completed to compare roof fall occurrence with time lapse intervals encountered during normal room-and-pillar mining. Results from this investigation show time lapse, in the Bear mine, to he insignificant with respect to roof stability after installation of permanent support.

Jan 1, 1980

This paper describes modern long-term mine scheduling and gives an example of its application. It then discusses the obstacles to the implementation of such schedules.

Sep 26, 2011

By J. F. T. Agapito

Two flat-lying trona seams 3-to 3.5-m thick, approximately 10 m apart, and at depths of 250 m are mined by room-and-pillar at OCI's Big Island Mine in Wyoming. Continuous miners and a yielding pillar system have contributed to improvements in resource recovery and productivity. Long-term stability with minimal subsidence is needed for a large portion of the mine beneath the Green River channel. This was investigated by computer modeling in 1990. Although results of the study indicated good long-term stability, recommendations were made for stress determinations to verify the model. Stress determinations made in 1997 showed pillar stresses 10% to 20% higher than the model stresses, and barrier pillar stresses 10% to 15% lower. This implies that higher panel stresses will be transmitted from the upper to the lower seam. A stability evaluation of the lower seam is planned before two-seam mining to assess entry widths and support requirements.

Jan 1, 1999

By Bruce H. Gardner, Stephen A. Miller, Shosei Serata

The Bryan Mound salt dome in Freeport, Texas, has some of the largest and oldest solution caverns in the U.S. There are a total of five caverns of varying shapes and sizes randomly distributed throughout the salt dome. When the caverns were converted from a brine production to an oil storage operation, the effects on long-term stability of the caverns and inter-cavern behavior were analyzed to evaluate the future safety of the storage operation. The analysis was based on a worst-possible-case scenario, including accidental wellhead pressure loss. The impact of this pressure loss upon the thinnest partition between the two closest caverns was analyzed, using a case example of storing lightest weight LPG, thereby creating maximum differential pressures between these two caverns. The finite element method with the REM computer code was utilized for this analysis. Results of the analysis illustrate the basic mechanisms of the long-term behavior of the multiple caverns in the LPG storage operation.

Jan 1, 1985

By R. L. Thoms

Compressed air energy storage (CAES) has been initiated recently in West Germany with a 290 MW peaking-power facility utilizing twin cavities with volumes of 150,000 m3 each in the Huntorf salt dome (1). The implementation of CAES in several geologic media is being studied carefully in the United States (2); however, the use of cavities for CAES in salt domes or salt anticlines and the associated long-term stability of these cavities is the specific topic of this paper (3). The cavities represent an essential element in a CAES plant, and thus should be designed and operated to perform with "stability" over the planned life of the overall facility. As employed herein, cavity stability implies the extent to which an acceptable amount of cavity storage volume can be utilized with economic maintenance over the planned life of the overall facility. In this sense stability is relative to the planned use of a storage cavity. Figure 1. depicts the salt deposits of the United States (U.S.) (4). The Gulf Coast region includes the only confirmed salt dome basin in the U.S., although salt structures also exist as anticlines in the Paradox Basin of Utah and Colorado. Because of the relatively small amount of elevation change within the Gulf Coast, CAES in salt dome cavities appears to hold considerably more potential for energy storage in this region than more traditional "pumped hydro" systems.

Jan 1, 1979

By D Craw

Bulk ore tailings from the Macraes gold mine gold extraction process are stored in a large (ca 0.6 km2, 80 m deep) mixed tailings impoundment whose pH is maintained near 8 by natural rock neutralizing capacity. The mixed tailings will be stored in this impoundment in perpetuity after mining ceases. Confidence in the long term environmental stability of these tailings can be gained from examination of mineralogically and chemically similar geological situations in the immediate vicinity. A sequence, typically about 5 m thick, of sands and gravels derived from the Macraes mineralized zone 12 000 to 28 000 years ago contains rounded detrital sulphide mineral grains which are unoxidized despite close proximity to the surface and occasional incursion of oxygenated waters. Saturating water pH is currently 7-8. Sands with 0.2 to 0.8 wt % organic carbon host sulphate-reducing bacteria (SRB), and localized cementation by authigenic framboidal pyrite has occurred. Comparison of the 28 000 year-old sediments with the modem tailings suggests that similar chemistry will prevail, possibly with deposition of authigenic pyrite in the tailings, in the long term. As long as the present slightly anoxic and circumneutral pH environmental conditions are maintained in the mixed tailings dam, sulphide decomposition and acidification are unlikely. These sediments provide a plausible geological analogue for long-term benign storage of the mixed tailings impoundment.

Jan 1, 2000

By Gennaro Gerald Marino

Vast improvement in methods of design and analysis of the long- term stability of overburden above room and pillar mines is needed. Improved methods are vital for planning and land development and for prediction above existing, presently stable, room and pillar mines. As shown on the flow chart in [Figure 1], the assessment of the long-term stability is an integral part of the site investigation process regarding mitigation of surface damage effects. In Illinois, flat farmlands with subjacent coal reserves cover vast areas. In some of these areas high extraction of the underlying coal layer(s) may not be possible since the resulting surf ace subsidence combined with a pre-existing shallow water table would make the land too wet. Thus recovery of this coal might only be accomplished by room and pillar mining where the ground surface does not subside and the hydraulics of the overburden are not significantly affected.

Jan 1, 1986

By C. P. Newman, T. Gray, G. Beale, T. Cluff

Predictive geochemical and limnologic modeling of pit lakes is an important aspect of modern permitting. One of the key assumptions of many predictive pit-lake models is that highwalls and pit backfill become unreactive once submerged by the filling pit lake. Existing pit lakes provide useful data to test this assumption. The Sleeper pit lake (northwestern Nevada) is near hydrologic equilibrium and contains good-quality water that generally meets regulatory requirements for pit lakes. Despite the overall stable geochemical composition, seasonal trends in the hypolimnion indicate the generation of solutes and fluctuations in pH. This work applies mass balance, analysis of subaqueous pyrite oxidation, and trends in solute concentrations to evaluate the potential causes of long-term solute generation in the hypolimnion of the Sleeper pit lake. Results will aid in refining the effect that inundation of highwalls and waste rock has on ultimate pit lake chemistry and long-term closure planning. In the case of the Sleeper pit lake, ongoing solute loading does not substantially change the closure plan at this time as influent groundwater contains abundant alkalinity. INTRODUCTION As mine pit lakes become more widespread, regulatory agencies are increasingly requiring advanced predictive modeling of pit-lake geochemistry during permitting. The end goal of all those involved in these permitting actions (i.e., the mining company, the regulatory agencies, and the public) is to have pit lakes become geochemically and hydrologically stable for the long term, which may then allow mining permits to be relinquished. The modeling endeavors therefore are important to inform long-term closure of pit lakes. The conceptual models and numerical methods used to predict pit-lake water quality are complex and require substantial amounts of data and a variety of assumptions (Castendyk et al., 2015). One of the common modeling assumptions is that solute generation via acid mine drainage is eliminated (or at least decreased) by the filling of the pit lake and inundation of highwalls and any in-pit waste rock. However, few studies have reported on observations that support or refute this assumption. The water-quality record of the Sleeper pit lake is an ideal dataset with which to test these assumptions. The former Sleeper mine is located in northwestern Nevada (Fig. 1), and has been inactive (in terms of ore extraction) since 1996. The mine extracted Au and Ag from the famous high-grade Sleeper vein and associated widespread stockwork mineralization (Nash et al., 1995). Water quality in the pit lake has been monitored since the cessation of dewatering in 1996. The current pit lake actually occupies three separate sub-pits, the Sleeper, Wood, and Office pits (Fig. 1). The Sleeper and Wood pits undergo regular water-column monitoring using a conductivity-temperature-depth (CTD) probe, and sampling for dissolved inorganic constituents at several depths (~10, ~130, and ~330 ft. below lake surface). Groundwater quality is also monitored using a series of wells (Fig. 1).

Jan 1, 2019