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By B. Basim

Novel chemicals that can be used for increasing the efficiency of fine coal dewatering were developed at Virginia Tech. Reagent A was tested on three different coal samples in laboratory vacuum filtration tests. These included flotation products from Middle Fork plant, Elkview Mining Company, and CONSOL, Inc. The tests conducted with the Middle Fork coal sample (100 mesh x 0) showed that cake moisture can be reduced by more than 10% beyond what can be achieved without using dewatering aid. This improvement was achieved at 1 lb/ton of Reagent A and 0.1 inch cake thickness. At 0.5 inches of cake thickness, the improvement was limited to 8% at the same reagent dosage. The results obtained with the Elkview coal (28 mesh x 0) showed similar advantages in using the novel dewatering aid. Depending on the reagent dosage, cake thickness, drying cycle time and temperature, it was possible to reduce the cake moisture to 12 to 14% range. In addition to achieving lower cake moisture, the use of Reagent A substantially decreased the cake formation time, indicating that the reagent improves the kinetics of dewatering. The test results obtained with CON SOL coal were not as good as with the other coals tested in the present work, which may be attributed to possible oxidation and/or contamination.

Jan 1, 1998

"Controlling dust generation and keeping it below permissible limits at the working face of a room and pillar mine is a challenge for mine operators. With the recent changes in the respirable-dust regulation, it has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) stated that a flooded-bed scrubber, under its optimum condition, can achieve cleaning efficiencies between 58 and 90 percent. The performance of such a system can be maintenance intensive. Other industries face similar dust control issues. The University of Kentucky partnered with Toyota Motor Manufacturing for the development of a novel wet scrubber for capturing paint overspray, with capture efficiencies in excess of 98 percent and minimal maintenance. The aim of this study is to assess the ability of this novel wet scrubber to capture respirable dust in an underground coal mine. This paper presents the conceptual design and the computational fluid dynamics (CFD) modeling of this novel wet scrubber. It discusses the results of the CFD simulation performed on the novel wet dust scrubber. INTRODUCTION Dust generation from underground coal mining is an inescapable phenomenon. No matter the practices employed, it inevitably occurs. Elevated concentrations of coal dust are potential health and safety hazards. Although dust in an underground coal mine cannot be completely avoided, its influence can be mitigated through good engineering practices. The effect of dust on the health of mining personnel has had a significant impact. The prolonged exposure of airborne respirable dust (< 5 µm) can cause coal workers’ pneumoconiosis (CWP), silicosis, emphysema, and chronic bronchitis, collectively known as black lung (U.S. Department of Labor, 2014). According to the National Institute for Occupational Safety and Health, black lung has killed more than 10,000 miners between 1995 and 2004 (NIOSH, 2008). In addition to being a health issue, coal dust is also a safety issue to the underground coal miners. The generated dust, if not captured, is dispersed into the mine air through the ventilating air and deposited downwind on the return entries’ surfaces. In the event of a methane explosion, the coal dust, if insufficiently diluted with rock dust, triggers a coal dust explosion which is much more severe than a methane explosion and causes more damage (Kenneth et al, 2006). The Jim Walters No. 5 Mine and the Upper Big Branch Mine disasters which together killed 42 people and resulted in damage worth millions of dollars in property are the examples of coal dust explosions (U.S. Department of Labor, 2001 & 2010)."

Jan 1, 2016

By Spencer R. Titley

Nearly three decades of intense research, corresponding with a period of unparalleled discovery and the advent of scientific advances and hypotheses of ore formation, has resulted in a great body process-focused research concerning how ore deposits form. The development of process models and their application has proceeded more or less in step. Discoveries have been made in mineralized regions such as provinces and districts but generally without a comparably developed understanding of why provinces and ore bodies exist and, except in general terms, where ore deposits are within districts and regions. The process of discovery is still referred to as search and exploration budgets are heavily weighted toward exploration drilling.

Jan 1, 1995

By P. Zhang, D. W. H. Su, M. Van Dyke, H. Dougherty

This paper describes the scientific data acquisition, data interpretation, and sophisticated 3-dimensional modeling processes of an ongoing gas well stability research program by the National Institute for Occupational Safety and Health (NIOSH). Results from the NIOSH field instrumentation programs and the parallel 3-dimensional numerical modeling programs indicate that overburden depth, overburden geology, surface topographic relief, strata dip of the coal measure rocks, and casing cementing alternatives are the dominant factors affecting longwall-induced subsurface deformations and gas well casing stresses. Topographic relief could produce localized longwall-induced deformations if weak-to-strong rock interfaces are present near the bottom of stream valleys. Strata dip has significant impact on longwall-induced subsurface deformations. Cementing alternatives are found to have significant impacts on longwall-induced deformations and gas well casing stresses.

By V. Srivastava, T. Ghosh

"Modeling and Simulation of SAG Mill has been widely used in design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents by solving Whiten’s first order contents based model in Matlab/Simulink environment. The parameters in the model such as breakage rate (S), discharge rate (D) and appearance function (A) were estimated utilizing process and design data collected from a gold mine operating in Alaska coupled with nonlinear parameter estimation scheme. This model is then utilized to predict dynamic response of other key operational variables such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated utilizing dynamic response data from the plant to encompass operational characteristics of SAG Mill behavior. Keywords: SAG Mill, Dynamic Modeling, Simulation, Nonlinear Parameter Estimation. INTRODUCTION Grinding in mineral industry is one the most important steps in the process of size reduction and plays a crucial role in determining the overall economics of the milling plant. Much of the efforts focused on improving the process efficiency using modeling and simulation have been practiced by researcher and engineers. However, up till now these models were simulated under steady state approximation because of their complex nature and difficulty in programming them in a dynamic framework. Steady state simulations have been successfully utilized in circuit designing, capacity planning and pre-flowsheet optimization. The maturity in steady state models is because of its applicability and regular use in steady state simulation packages such as JKSimMet, Limn, ModSim, etc. With the advent of equipment such as SAG and AG mill has been a recent shift in the simulating these models using dynamic approach. Because of the economic benefits of these devices and ability to act both as a primary grinding device and as secondary or tertiary crushing device they have gained a large popularity and are now universal to any milling plant. However, these device poses a real challenge to engineers and researchers in terms of operation and control. The major reason attributed to problems faced is because the ore constitutes the major portion of the charge in these devices when compared to ball and rod mill. This rock charge is subjected to disturbance such as changes in feed size distribution and ore hardness which results in unstable operation and frequent mill stoppages. One way to prevent this is to measure and control these external variables, however, lack of available instrumentation and unavailability of sensors to measure these variables has foiled the understanding of complete process occurring inside the mill thereby, inhibiting development of proper control system."

Jan 1, 2017

By Thomas N. Walthier

Exploration is the systematically financed and technically oriented search for mineral wealth. Almost all established mining companies have an exploration department. The size of a company&apos;s search varies over the years as the company&apos;s profits, or the corporate philosophy change. While the established mining companies have exploration departments, they are also alert to acquiring discoveries made by others -- especially by prospectors and small companies without the resources to develop their find. The emphasis in some large companies stresses self-generated discoveries while others rely heavily on acquisitions; again, over the years the emphasis may alternate. In the last analysis, essentially all new mineral wealth was found through someone&apos;s exploration effort. Before we discuss how exploration is financed, it will be informative to analyze how discoveries have been made and by whom. Recently, the author conducted a survey of randomly selected major mining companies to answer these questions. Most companies responded and many went to considerable effort to give complete and detailed answers. I thank all for their help and cooperation. The questionnaire is attached as Appendix I. Appendix II is a list of the 400 companies that replied in a complete enough manner and format to be analyzed here. The results of the questionnaire are given in Table 1. Over 57% of the new orebodies acquired by 40 major mining companies during the past quarter of a century were generated

Jan 1, 1977

By J. K. Ross, K. O. Hoal, S. K. Appleby

Understanding ore variability is a key factor in the geometallurgical analysis of a deposit and is beneficial to process development and mine planning. Ore variability is a function of the mineralogy of a deposit, in terms of both ore and gangue minerals and their textural relationships. This study integrates optical microscopy and quantitative mineral analysis to characterize the mineralogy and texture from 13 samples from different lithologic units at the Bingham Canyon Mine. The analysis identified several parameters, such as modal mineralogy, alteration assemblages, distribution of mineral phases and alteration assemblages and microfracture and void space distribution. These parameters can have an impact on the materials’ behavior during processing. This study demonstrates that quantitative mineralogical analysis can provide detailed information for improved understanding of ore variability.

Jan 1, 2010

By W. R. Reed, S. Klima, J. Driscoll, T. W. Beck

"Tests were conducted to determine properties of four foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with the Mine Safety and Health Administration’s lower coal mine respirable dust standard of 1.5 mg/m3. Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used low-pressure air generated by a blower and water pressure using a foam generator developed by the U.S. National Institute for Occupational Safety and Health. Foam property tests, consisting of a foam expansion ratio test and a water drainage test, were conducted to classify foams. Compressed-air-generated foams tended to have low expansion ratios, from 10 to 19, with high water drainage. Blower-air-generated foams had higher foam expansion ratios, from 30 to 60, with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The test results eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control. IntroductionAbout one-half of U.S. underground coal is produced by longwall mining, which allows for mining high volumes of coal but generates significant amounts of coal mine dust. This can lead to overexposures for longwall miners and possibly occupational respiratory diseases, including black lung and silicosis, which have no cure and can be disabling or fatal. The only method to avoid these occupational illnesses is through elimination of exposure to respirable coal mine dust and crystalline silica (quartz). The current occupational exposure limit for respirable coal mine dust is 1.5 mg/m3 during each shift that a miner is exposed in the active workings of the mine or in mine facilities (Mine Safety and Health Administration (MSHA), 2015a). When respirable quartz is present, the mine must maintain average concentrations at or below 0.1 mg/m3. If the mine exceeds the 0.1 mg/m3 respirable quartz dust concentration, then the applicable respirable dust standard is reduced, calculated as 10 divided by the percent quartz present (MSHA, 2015b)."

Jan 1, 2018

By Raymond E. Langen

Uranium exploration in the Powder River Basin of northeastern Wyoming has been intensive since 1966 and in 1968 produced significant discoveries of reduced uranium ore by Humble Oil & Refining Company and others. Substantial reserves have been established in the area. High-grade carnotite ore was discovered in 1951 near Pumpkin Buttes in the central part of the basin (Fig. 1). Other mineralized areas were soon established from Pumpkin Buttes south to Monument Hill and Box Creek. Total production from these shallow oxidized deposits in the lower Eocene Wasatch formation was small. The AEC reports total production of 520,000 tons of ore averaging 0.19% U3O8. The authors are indebted to many people within Humble Oil & Refining Company and Esso Production Research Company for their assistance and guidance. SUMMARY AND CONCLUSIONS The Highland ore deposit, discovered in 1968, is a large uranium occurrence located in the southern part of the Powder River Basin. Uranium mineralization consists of sooty, black uraninite and coffinite coating sand grains and is concentrated along the margins of Tertiary fluvial sandstones. Uranium was transported by oxidizing solutions roving through the buried sandstones and spreading into less permeable channel-edge sandstones to form typical rolls and tabular deposits. Unaltered sandstones are light gray to gray-buff where the sandstones have been oxidized, the colors are various shades of red, yellow, and yellowish brown. An Oligocene tuffaceous source for the uranium is proposed; however, leaching of the arkosic and tuffaceous host sediments may also have provided a source.

Jan 1, 1971

By X. Meng

A kinetic model for batch leaching of various metals with different lixiviants has been developed. Overall material balances for reactants and products at the solid/liquid interface were formulated with various types of heterogeneous reactions in place at the interface. The solutions to these mass balances have been identified analytically as well as numerically using a Runge-Kutta method. Applications of these numerical solutions to various leaching systems using the rotating disc or powders have been discussed. Examples of the metal dissolution systems considered in this study include cobalt, nickel, copper and gold in acid, cyanide or ammoniacal solutions.

Jan 1, 1994

By S. B. Keith

Cerro de Pasco Corporation operates five large base metal mines in Peru having a combined production of some three million tons of ore a year. An integrated complex of concentrators, smelters and refineries produces annually about 25,600 short tons of copper, 48,100 short tons of lead, 60,500 short tons of zinc metal, 102,300 short tons of zinc concentrate, 8,272,000 ounces of silver and substantial amounts of bismuth, cadmium and selenium. Geology plays an important role in these operations. The organization of detail geologic work in and around the Cerro mines was set up by John M. Boutwell in 1918 and a geology department was established in 1920. Growing through the years, the department technical staff now numbers over thirty men and. their work covers all phases of geological investigations. Many outstanding geologists of the past and present, too numerous to name here, have studied and contributed to the knowledge of the deposits and the ever growing list of Cerro "alumni" must rival that of any other mining organization. Numerous papers on the geology of Cerro&apos;s mines can be found in the technical literature and several doctoral theses have been presented on Cerro subjects as indicated in the attached bibliography, Specimens of Cerro&apos;s ores can be found in museum, college and university collections throughout the world. Yet, as with all mines and mining districts, the geologic knowledge of Cerro&apos;s deposits in Peru is being revised and added to constantly. This presentation cannot hope to cover adequately all the phases of the geology and mineralization. For a more complete background and discussion of the mine you are referred to the bibliography. Here I shall outline only briefly the more important geologic features and describe some of the newer developments of recent years The credit for the data presented here belongs to the many geologists who have worked or are now working for Cerro de Pasco Corporation, but I must assume sole responsibility for any omissions or variations in the interpretation of their work.

Jan 1, 1965

By Wade W. Bristol

The Jerritt Canyon Joint Venture project is located about 80 km (50 miles) north of Elko, NV. It produces approximately 9.3 t/a (300,000 oz/year) of gold. The joint venture is 70% owned by Independence Mining and 30% by Meridian Gold. Independence Mining is the operator. The Jerritt Canyon Joint Venture started operations in 1980 by mining a series of open-pit mines. The discovery of deeper ores during early 1990s made it neccessary for the operation to mine a large portion of its annual production by underground mining methods. Underground production started in 1993 at the West Generator Mine. This was followed by the Murray Mine in late 1994. Two additional underground projects are being developed. Underground mining at Jerritt Canyon is scheduled to produce about 3.9 t (128,000 oz) in 1997.

Jan 1, 1997

By Walter M. Chapman

The National Lead Company operates its MacI tyre Development at Tahawus, New York for the production of ilmenite and. magnetite. The heavy ore of titanium and iron is mined from the open pit mine at an average rate of 7,000 tons per day, and the development waste is removed at an average rate of 10,000 tons per day. The mine working benches are spaced, at 35-foot vertical intervals, and 6 ½ inch blast holes are drilled 39-feet deep with 18-foot burden and spacing by down-the-hole drills. Waste is loaded with a 6 yeard shovel and ore with 2 ½ yard shovels into 22-ton rear dump trucks. A good account of the history of MacIntyre drilling and. blasting was presented to this assembly two years ago, by F. R. Jones. (1) Most of the blasting since the start of the mine in 1941 was done with 90% gelatin dynamite until 1955, when relatively insensitive canned blasting agents were adopted.. In 1956, 9-inch blast holes drilled with down-the-hole drills. In 1956, also, the first experimental trials of prilled ammonium nitrate fertilizer and fuel oil (hereafter called fertilizer) was made following the lead of Cleveland-Cliffs operations in the Hibbing district. Since that trial did not, as some local skeptics predicted, make grass grown on the bluff, but resulted in a well-broken shot, further tests were conducted in dry holes. I Observations of those tests indicated that the fertilizer did its share of the work. If anything, it produced better fragmentation than the normal load di in neighboring wet holes.

Jan 1, 1958

By A. M. Gaudin

The recent study by R. M. Hays(l) prompted the study summarized in this paper. In his Interesting paper, Mr. Hays shows fine results to be attainable by a relatively complex flowsheet on a semi-taconite, a manifestly difficult ore to treat. We obtained a semi -taconite from Minnesota, and treated this sample by wet magnetic separation alone. The device in which the separation was accomplished is the standard pilot-plant, laboratory separator in use at Magnetic Engineering Associates&apos; laboratory (MEA) in Cambridge, Massachusetts. It consists of a cylindrical space which can be magnetized by turning on the magnet of the separator. In this cylindrical space, there is a canister which provides the special configuration of the magnetic field and magnetic field gradients that MEA considers to be required. The ore pulp is made to flow through the canister while the current is on. A portion of the pulp is retained in the canister, and the rest is evolved as a non-magnetic fraction. The laboratory device is cyclic, but it accurately predicts the results obtainable by an Industrial unit of either cyclic or continuous type (moving matrix). The ore tested was 99.5°%o -325 mesh, and approximately 75% -500 mesh. The concentrate from this ore was, therefore, eminently suitable for pelletizing. In passing the ore through the magnet, we had the choice of repeatedly passing the concentrate from the first step through the operation, or of repeatedly passing the non-magnetics. In our experiments, the first method was clearly superior from the stand¬point of the cleanliness of concentrate. Of the many tests which we have made, we think that we have to retain two which

Jan 1, 1971

By M. J. Gula

In the solvent extraction -electrowinning recovery of copper from oxide or sulfide ores there is a continuous transfer of iron and other impurities from the primary leach solution to the copper electrowinning electrolyte via chemical transfer or mechanical entrainment. Iron is the principal impurity that has to be controlled in the electrolyte by a "bleeding" of the electrowinning solution. This bleeding transfers copper and sulfuric acid back to the primary leach circuit along with the iron. Copper is recovered via the solvent extraction process and generally the sulfuric acid is used as a reagent in leaching. Unfortunately, cobalt, which is added to the electrowinning solution to modify the anodic process, is irreversibly lost through the bleeding operation. This cobalt loss represents a significant operating cost to SX-EW copper producers. DiphonixTM ion exchange resin contains diphosphonic acid and sulfonic acid functional groups on a polystyrene-divinyl benzene matrix. This resin has been found to strongly and selectively extract ferric ion from copper sulfate -sulfuric acid solutions containing cobalt. Thus, an ion exchange process using DiphonixTM resin for the control of iron has been developed to replace the conventional bleed stream process. The new process minimizes the loss of cobalt from the electrowinning circuit and strips the iron into a sulfate based solution suitable for leach solution makeup. In addition, this process can effect a lowering of the total iron concentration in the electrolyte circuit with an associated increase in current efficiency. In this paper, data on the loading and elution of iron are presented. Laboratory and pilot scale data will be discussed along with information on process design and comparative economics.

Jan 1, 1996

By J. A. Herbst

Successful transitions from micro- to macro-engineering are the keys to effective technology transfer between research and development organizations and industrial end users. At the same time, it has proven to be one of the most difficult tasks that the minerals industry has had to manage. Typically, developers of fundamental information concerning how mineral processing subsystems work have been academics and government scientists. These are the individuals giving the most important input to micro-engineering models that can benefit industrial operations. Publication is the usual route for "attempting" to transfer this technology to the end users. Unfortunately, with such publications, very little direct communication occurs concerning real industry needs or the future steps required to make the particular micro-engineering model useful. In the past, the industry has relied on in-house R&D groups and plant metallurgists to "translate" publications, to provide useful macro-engineering tools for plant applications. To some extent, engineering companies have also been asked to serve this function. However, these firms have been rather ineffective in this area since their conservative nature has caused them to look rather suspiciously at new technology. This approach to technology transfer has worked, albeit clumsily, for the last several decades. This communication system is now on the verge of total collapse due to conditions of the minerals industry. Mining companies can no longer afford the significant overhead expenses of specialized technical staffs. Universities are finding it extremely difficult to interest US students in mineral engineering programs, and funding for such programs is weak. Faculty members involved in micro-engineering research today tend to focus on pure (non-application-oriented) research.

Jan 1, 1992

By J. R. Patts, A. B. Cecala

"After industrial sand has been mined and processed, the finished product is typically loaded into small bags of 45 kg (100 lb) or less, large bulk bags of 454 to 1,361 kg (1,000 to 3,000 lb), or vehicles such as trucks or trains for transport to end users. As the sand is being transferred and loaded, dust can be released into the work environment, potentially exposing workers to respirable crystalline silica. A number of control technologies have been developed and utilized in an effort to reduce dust liberation during loading operations. For bulk loading into trucks or trains, the U.S. National Institute for Occupational Safety and Health (NIOSH) evaluated one of these technologies, the Dust Suppression Hopper (DSH), at two industrial sand processing plants. Results from these case studies show that the DSH reduced airborne respirable dust levels by 39 to 88 percent, depending upon the product size being loaded.IntroductionInhalation of respirable crystalline silica dust can lead to the development of silicosis, a disabling and potentially fatal lung disease. Once contracted, there is no cure for silicosis, so the goal is to prevent the development of the disease by limiting exposure to respirable dust containing crystalline silica at or below the exposure limit of 50 µg/ m3 recommended by the U.S. National Institute for Occupational Safety and Health (NIOSH, 2002). At industrial silica sand operations, the product contains high levels of crystalline silica, so effective control technologies are needed to minimize the respirable dust exposure of workers.NIOSH, in partnership with the Industrial Minerals Association–North America, published a dust control handbook (NIOSH, 2012) focused upon control technologies for industrial- mineral mining and processing operations. One chapter in this handbook discussed technologies for controlling dust liberated during bulk loading, including telescoping loading spouts, dust collection systems for loading spouts, enclosures for load-out areas and a newer technology known as Dust Suppression Hopper (DSH)."

Jan 9, 2018

An open pit production planning method for stage mining is presented in this paper. The method brings solutions to the four most important parameters in stage mining : 1) the number of stages, 2) the size and geometry of each stage pit, 3) the mining sequence of the benches in the stage pits, and 4) the time of transition from one stage to the next. The method can also simultaneously optimize the ultimate pit, mine life, and production rate in each stage.

Jan 1, 1996

By Tamás Megyeri, Dániel Borbély, Vera Szánto, László Kovács

"Upon completion, the Bátaapáti deep underground radioactive waste repository complex (National Radioactive Waste Repository - NRWR) will provide safe final disposal for low and medium-level radioactive waste from the Paks Nuclear Power Plant in Hungary. The waste emplacement is in progress and one of the main concerns related to the development is ensuring a feasible plan is in place for permanent repository closure. Detailed hydrogeological observations and safety assessments revealed that the clay filled fault zones penetrated with the access tunnels play determinant role in the long-term confinement performance of NRWR, so they need to be plugged. Detailed mechanical analysis and numerical modelling of the tunnel constructed through a fault zone is presented here to gain a better understanding of the rock mass and rock support behavior. The effect of stress reflection is demonstrated and its consequences are described in detail. A recommendation is given for tunnel support design in such conditions. INTRODUCTION Crossing fault zones is a challenging task during tunnel construction and can lead to failure if not properly accounted for during design and construction. These failures are can be caused by high water inflow or stability loss of the rock mass surrounding of the tunnel (examples can be found in CEDD, 2015). The prediction of the magnitude and development of displacement has a considerable impact on issues during tunnel construction. Changes of rock mass stiffness or structure ahead of the face, to a great extent influencing stresses in the vicinity of the tunnel and thus deformations (Steindorfer, 1998). Further research with numerical simulations was carried out, and the qualitative and quantitative evaluation of displacement vector is presented in (Grossauer et al, 2005). The concern associated with crossing fault zones was considered during the design of the Bátaapáti deep underground radioactive waste repository complex (NRWR) in Hungary. In the case of NRWR project, the fault zones have an impact on maintaining the stability of the surrounding rock mass as well as the final sealing of the repository. As part of the final closure design, a complex numerical modelling program was completed to gain a better understanding of the mechanical behavior of the rock mass and the monitoring observations during construction. Even though the need for the presented study is closely related to the NRWR project, the results can be used in any project related to fault zone crossing. The methodology used to better understand the impact of crossing fault zones for the NRWR project is presented in this paper. First the project background is introduced including an overview of the underground facilities, the aim of the repository, and the construction experience gained from the first crossings of the fault zones. After that the in-situ and laboratory testing is summarized. The numerical modelling methodology is detailed in the next section. Not only the outcome of the model is presented, but the results are compared with the experience and observations made on site. Since a good agreement is found between the actual and the modelled behavior, the conclusions are based on the validated result. To fulfill the aim of the paper, the stress reflection concept is introduced to explain the mechanical behavior of the fault zone and the rock support; furthermore straightforward suggestions are made for rock support design."

Jan 1, 2016

By H. Burton

"The selection of the ultimate pit shell has a major impact on the overall value of a mining project. The size and shape of this pit drives the selection of pushbacks, equipment, and project strategy, each of which are significant in their own right. Optimization of the ultimate pit shape is typically done using the Lerchs-Grossman algorithm with inputs of production costs, commodity prices, and pit slope constraints. This method ensures that every tonne mined is profitable but does not take into consideration the timing of material release. This timing is essential when calculating the Net Present Value (NPV) of the project, which is one of the most popular metrics for valuing deposits. Often, when the mining schedule and discounting are applied, material that was considered profitable before discounting becomes sterilized. The objective of this paper is to show the methodology for improving ultimate pit selection by considering the production schedule. Application of this technique will generally produce a smaller and higher-value pit than using the Lerchs-Grossman algorithm alone. INTRODUCTION The Lerchs-Grossman Algorithm was developed in the 1960s and exists to produce a mathematically optimum shape for open pit mines (1). This algorithm is now an industry leading technique for producing the theoretical optimum shape for open pits and is used in many popular pit optimization and strategic planning software packages, such as GEOVIA’s Whittle. The Lerchs-Grossman (LG) Algorithm is based on graph theory and optimizes on the assumption of non-discounted cash flows. This produces a mathematically optimum shape, but does not consider the timing with which the material will be removed from the ground. This is an important consideration, given that one of the most popular metrics for evaluating mining projects is Net Present Value (NPV) (2), which relies on the timing of cash flows as a major differentiator between options. This paper will discuss issues inherent in the use of ultimate pit selection based on undiscounted economic factors and illustrate a simple technique in Whittle, a leading software package, which can be used to improve the NPV of projects."

Jan 1, 2015