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By Jorge Armstrong, Sean Warren, JOSEF BOURGEOIS

The paper investigates the influence of slope height, slope angle, slope material, and rock size on rockfall runout distance in openpit mines. Using statistical analysis and simulation, the study aims to improve rockfall hazard assessment and catch bench design by identifying key variables affecting rockfall behavior.

Oct 1, 2023

By Anthony Iannacchione, Tim Miller, Nicole Evanek

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport Limestone near Petersburg, OH. In February 2018, mine management began implementing a new mine layout to better control the negative effects of excessive levels of horizontal stress. Almost immediately, the conditions in the headings improved. Conversely, and as expected, stress-related damage was concentrated within crosscuts. Over the last 18 months, the mine operator has diligently experimented with different techniques/methods to lessen the impact of the instabilities in the outby crosscuts. The range of controls used by the mine operator include angled crosscuts, crosscut offsets, increased distance between crosscuts, arched crosscuts, cable-bolted crosscuts, altered blasting pattern, and windows. A window is used to resist roof deformation by leaving a strong brow of roof rock within the crosscuts.

By S. Kelebek, G. W. Smith

Four samples of galena, each prepared differently, dry ground chalcopvrite and real gar have shown various quantities of liberated sulfur corresponding up to nine equivalent monolavers on their surfaces as determined by the solvent extraction/UV analysis of sulfur using ethanol. The pretreatment of a dry ground galena sample with acidified ammonium chloride or neutral, saturated sodium chloride solutions rendered the mineral readily floatable. The collectorless floatabilities of galena pretreated with the former solution and of drv ground chalcopvrite have been evaluated in reference to the natural floatability of sulfur using the critical surface tension of floatability approach with aqueous methanol solutions. It is shown that the amount of sulfur- on these samples can be correlated with their flotation rate, which was found to he first order within the critical surface tension range. The larger the concentration of surface sulfur, the faster the sulfide mineral floats, thus, the greater its flotation rate constant.

Jan 1, 1990

By M. E. Breitrick

Newmont Gold Company began full production in early 1995 at the Carlin East underground mine. The mine is currently producing at the rate of 900 tpd (1.000 stpd). for an annual production of 150.000 ounces. Approximately one hundred twenty five hourly and salary personnel are employed at the project for the estimated six-year mine life. Two mining methods are currently utilized at the mine. Longhole stoping with cemented backfill accounts for 70% of the total mine production. Conventional underhand drift and cemented fill accounts for the balance of the daily tonnage. In December 1996. Newmont purchased a new AC-Eickhoff ET-210 Roadheader. The machine went into service in mid-June of 1997 and is used in both longhole stope topcut development and cut and fill production at a rate of 225 tpd (250 stpd). The Carlin East mine is operated by Newmont Gold Company. The mine is one of four underground gold mines in production in northeastern Nevada owned by Newmont Gold.

Jan 1, 1998

By Yi Luo, Jian Yang, YUJIA LIAN

Scale physical models, constructed according to the principle of similarity theory, are widely used to simulate the mining disturbances to surrounding strata and to evaluate the effectiveness of implemented ground-control techniques. This technique has also been used for studying mining-induced surface and subsurface subsidence. The movements of the observation points installed on the physical model at different mining stages are currently measured using a total station, which is time consuming and inaccurate, especially on small-scale models.

By Chris Howell

PotashCorp?s Aurora phosphate mine, in Beaufort County, NC, operates four low pressure boilers and four high pressure boilers to meet its process steam requirements. Maintaining these boilers is critical to meeting production demands. Processing phosphate ore into phosphoric acid requires large amounts of sulfuric acid and steam. Ore is mined from the phosphate deposit with large bucket excavators after 9 to 30 m (30 to 100 ft) of overburden is removed. The phosphate ore is mixed with water to make a slurry that is pumped to the mill. Elemental sulfur is burned in the presence of air to make sulfuric acid. This process is highly exothermic and boilers produce steam while cooling the process. The phosphate ore is reacted with sulfuric acid and the resulting products are refined into different grades of phosphoric acid for fertilizers, feed stock and food additives. Plant operators at the mine were challenged with boiler feed water that was high in silica and other contaminants. As a result, boiler operations were experiencing difficult, labor-intensive operations and equipment deterioration. This resulted in higher operating costs and diminished processing performance. The facility was operating an aged boiler feedwater pretreatment system that included warm lime softening followed by pressure filtration and a cation/anion/mixed bed demineralizer system. The demineralizer required frequent regeneration and chemical usage was high and costs were difficult to predict. Depressurized well water (DPW water), used for plant utility water and boiler makeup, is very high in silica, in the range of 60-70 ppm. Silica can form scale at pressures below 600 psig. Above 600 psig, silica starts to volatize, carrying over with steam to potentially form deposits on downstream equipment and processes. Mine officials decided to upgrade the boiler feedwater pretreatment system to a state-of-the-art reverse osmosis (RO) membrane system. This new system, which started up in March 2009, has improved operating performance and reduced water consumption and overall operating expenditures.

Jan 1, 2011

By Jean Dupéré

Introduction Before examining the current position of the asbestos industry and its market outlook, it is important to describe the product itself. If we are to understand the problems besetting this basic mining and manufacturing industry, and, more importantly, if we are to appreciate solutions to these problems, we had better view asbestos from the proper perspective. Asbestos has a unique combination of properties - properties not found in any other natural substance or man-made material. As a result, asbestos has found its way - in fact, is welcomed - into hundreds of applications. Properties and Products World production capacity of asbestos fiber is about 6.5 Mt (7.2 million st). Major producers and their approximate percentage share of actual production are: USSR, 47%; Canada, 24%; South Africa, 5%; Zimbabwe, 5%; Brazil, 4%; Italy, 3%; and others (including the US, China, and Greece), 12%. Although Canada accounts for less than one-third of the world's

Jan 7, 1984

By John Newby, Mahmood Khwaja, Bernard Theron, Janice McGovern, Bernard Catalano, Michael S. Schultz

Launching a full-size pressurized-face Tunnel Boring Machine (TBM) in difficult ground conditions is always challenging. Recently, few projects have innovated the process by scaling the trenchless method of pipe jacking, and modified steel bell approach, to facilitate the launching of a full-size TBM without the need for large and deep trenches, starter/tail tunnels, or for incrementally installing supporting gear as the machine advances. This paper presents three such projects; evaluates the post-bid contractor proposed modifications; details the innovative use of pre-cast pipe segments to facilitate machine launch; and, provides an overall assessment of the benefits, challenges and lessons learned related to the modified approach.

Jun 13, 2021

By Grover Wallace

At is important for today?s mining executives and leaders not to underestimate the fact that, while the recent downturn in the economy did take its toll on balance sheets and productivity, factors such as emerging countries, aging workforces, globalization and individual knowledge growth did not lay dormant while the economy was in a lull. It is key for mining leaders to be proactive in their talent strategies. Successful mining companies are developing a clear, concise and communicated strategy and placing a high priority on recruiting the right talent in global markets that parallels their business strategy. They are focused on placing the right people in the right jobs.

Jan 1, 2011

By C. Douglas Lee

This case study describes the work done at the University of Arizona on the development of a computer mine model for an irregularly shaped and spotty ore deposit. The purpose of the work was to develop techniques for modeling any highly irregular deposit, for which the regular 3D fixed block model is not well suited. The deposit contained complex geology consisting of sedimentary beds that had been faulted, thrusted, and intruded by igneous rocks (see Fig. 1). The physical dimensions of the modeled ore body were 1067 m (3500 ft) along the N-S direction and 914 m (3000 ft) along the E-W direction. Topographic relief in the modeled area was approximately 274 m (900 ft). The highest grade of ore was found near the surface with mineralization extending down to approximately 152 m (500 ft) below. Using a fixed bench height of 12 m (40 ft), the model required 25 levels with the highest elevation being at 1286 m (4220 ft). Fig. 2 shows a cross section of the developed computer model of the ore deposit. The particular modeling approach selected for this deposit was the 3D irregular block model.* This meant that only the dimension of bench height was fixed at 12 m (40 ft). Irregular size blocks in the form of polygons were adopted in the model to describe the ore zones and geologic contacts. The following sections of this chapter describe some of the techniques used in modeling.

Jan 1, 1979

By L. Evrard, M. Van Camp, J. Y. Yen, R. G. Reddy, D. Mantha

Viscosities of two industrial lead blast furnace slags have been experimentally determined as functions of composition and temperature. A Brookfield viscometer with alumina rods and crucibles were used. Experiments were carried out between 1200 and 1573 K in an argon atmosphere with up to 5% addition of FeO, MgO, and SiO2 to the slags. Results showed that 1) the viscosities of two slags decreased with increase in temperature; 2) addition of FeO decreased the slag viscosities; and 3) addition of MgO and SiO2 increased the slag viscosities. Use of the above slag compositions with the addition of FeO is recommended for successful lead smelter operation.

Jan 1, 2005

"A commercially available Through-the-Earth (TTE) communications system was evaluated at an active underground longwall mine in West Virginia. This TTE system uses electric field (E-field) sensing to send text based communications using two separate antenna arrays connected in parallel. Each antenna array is composed of interconnected, grounded metallic rods or other such structures. Two-way communication between subsurface locations was investigated in this study using various antenna configurations. This field study was conducted as a part of a larger multi-site evaluation of available TTE systems in an effort to determine their operational sensitivity. INTRODUCTION Wireless, Through-the-Earth (TTE) communication technology is designed to achieve point to point communication through solid strata using very low frequency (VLF) and ultra-low frequency (ULF) electromagnetic waves. This ability allows TTE communication to function without the need for intermediary communications infrastructure, such as repeaters. As a result, such communication systems have the potential to provide reliable, robust communications between surface and underground personnel. Exploration into the use of TTE technology for this purpose dates back to the 1920s (Jakosky and Zellers 1924; Pittman, Church and McLendon 1985), but U.S. permissibility requirements slowed the development of TTE equipment for widespread implementation (Durkin 1980; Pittman, Church and McLendon 1985). One of the primary challenges in producing wireless TTE communications is the counteraction of signal attenuation when propagating through solid strata (Barkand, Damiano and Shumaker 2006; Wadley 1949). The long wavelengths of TTE transmissions make them well-suited for reducing the rate of attenuation. However, even when operating within the VLF to ULF range, the performance of TTE systems is still affected by geologic and anthropogenic factors (Geyer 1973; Geyer and Keller 1976; Geyer, Keller and Ohya 1974; Jakosky and Zellers 1924; Large, Ball and Farstad 1973). Although commercially developed TTE systems have demonstrated the ability to communicate through a variety of conditions, their range and performance have been highly varied (Barkand, Damiano and Shumaker 2006; Geyer and Keller 1976; Geyer, Keller and Ohya 1974; Ilsley, Freeman and Zellers 1928; Jakosky and Zellers 1924; Yenchek et al. 2012)."

Jan 1, 2016

By Clayton J. Parr, Northcutt Ely

Mining law is essentially a branch of the law of real property. It concerns acquisition of property for extracting contained minerals, and the rights, privileges and duties that fall upon the holder thereof once the rights are acquired Accordingly, this section focuses on the procedures to be followed in acquiring state. federal and private lands, and defines briefly the nature of the rights obtained. The mining laws of Canada and Mexico are summarized, and the related subjects of minerals taxation and governmental regulation are discussed briefly. This section is not intended to be the basis for legal decisions. Rather, its purpose is to provide the engineer with an understanding of basic principles and procedures. For a detailed treatise of mining law, reference can be made to The American Law o] Mining, a five-volume set edited by the Rocky Mountain Mineral Law Foundation. The law changes constantly, especially that based on federal and state statutes, and the reader is cautioned to be alert for subsequent modifications of statutes, regulations and case law. 2.1-PRELIMINARY LAND-STATUS CHECK Often, after completion of area reconnaissance, or perhaps after receipt of a submittal, a specific more localized target area will become of interest. Usually, an intensive exploration program comprising detailed surface mapping, sampling, geophysical prospecting and drilling will be required before the mineral potential of the ground can be properly evaluated. Before an investment of this magnitude is made, however, it is advisable to obtain rights to mine ore from the property. Otherwise, knowledge of the exploration activity might greatly inflate land values, or speculators or competing mining concerns might step in. Hence, as a general rule, a land-acquisition program should be undertaken before an intensive exploration project is begun. The first step in such a program is to make a land-status check to determine whether the subject lands are available and, if so, from whom they can be obtained and by what means. 2.1.1-BUREAU OF LAND MANAGEMENT RECORDS In those states which contain large areas of federal land, basically (he western states, the primary informational source is the records of the Bureau of Land Management. These may t)e examined at the land office having jurisdiction over federal lands in the area of interest. The records for Montana and North and South Dakota are kept at the Billings (Mont ) land office; Wyoming, Nebraska and Kansas, Cliejenne, Wyo.; New Mexico, Oklahoma and Texas, Santa Fe, N M ; northern Alaska, Fairbanks, and southern, Anchorage; Utah, Salt Lake City; Nevada, Reno; Arizona, Phoenix; Colorado, Denver. There are two land offices in California, at Sacramento and Los Angeles Records for other states are kept in Washington, D C. at the office of the Director, Bureau of Land Management.

Jan 1, 1973

By J. R. Henke

Dewatering wells producing iron-rich water experience rapid declines in yield and drawdown due to the formation of ferric (Fe +) hydroxide deposits in well screen, pump intake and riser pipe. Precipitation is caused by a combination of dewatering-promoted iron oxidation and iron-oxidizing bacteria. Physical and chemical well rehabilitation techniques, as well as alternative well construction and well development techniques designed to minimize well clogging, were evaluated in this study. The addition of acid downhole feed systems to dewatering wells prone to iron encrustation can, in some cases, prolong their operational lives up to 500 percent that of unacidified wells.

Jan 1, 1989

By Gerard P. Hand

The use of graphite in industrial applications is one of the oldest in the world. Yet, it is one of the fastest-changing technologies today. Graphite was first used centuries ago in developing writing instruments and as a raw material in crucibles used in melting metal. Today, graphite is used in some of our most demanding industries. These include aerospace, electronics and automotive applications. Graphite usage has historically been split between the natural and synthetic forms. Figure 1 shows the breakdown of natural graphites and synthetic graphites used. The usage of natural graphites and synthetic graphites is split fairly evenly, although the applications are quite different. Figure 2 shows the breakdown of applications using natural graphite. The largest application is the refractory industry. This includes refractory brick and plastics, crucibles, shrouds and other refractory parts. This main application uses roughly 50% of all natural graphite. The refractory industry is an important application for natural graphite. However, the refractory markets have been struggling for several years. As demonstrated in Fig. 3 (Semler, 1996), the production of refractories in tons per year has declined by more than 32% during the last 25 years. Refractory prices have actually risen on a dollar per ton basis during that same period as the product mix has shifted to the value-added side. Raw material and production cost increases, inflation and other related costs have kept profitability at low levels for the industry. Furnace linings that once lasted 1,000-2,000 heats now last 8,000-12,000 heats. This means that tonnage requirements have gone down and quality requirements have gone up for graphite suppliers. Therefore, new opportunities and applications must be developed if the graphite industry is to grow. Synthetics are the other major forms of graphite. There are two forms of synthetic material currently used. One is the traditional type. It is made from the turnings of graphite electrode production. The second was developed in the mid-1970s in response to a shortage of conventional synthetic graphite. This occurred by a breakthrough in thermal technology. This new technology purifies, desulfurizes and graphitizes petroleum coke on a continuous basis at temperatures of more than 2,500° C (4,532° F). This product is called desulfurized petroleum coke (Desulco). It now accounts for about half of the synthetic type material used in the United States. Figure 4 shows the breakdown in the use of synthetic types of material by application. The largest requirement is for use as a carbon addition in iron and steel. This is followed by alkaline batteries and friction materials. Current technological opportunities New opportunities for graphite products are now being developed. These new areas are made possible due to the advances in graphite thermal technology. The ability to purify and modify graphite and carbon products is the key to future growth in the graphite industry. New, higher-purity, more consistent graphite products are leading to enhanced performance in current applications. They are also opening the door to new applications.

Jan 1, 1997

By Ian J. Corrans, Gary Johnson, John E. Angove

Activox® is a hydrometallurgical process used to oxidise sulphide concentrates. The process is based on two relatively simple, established unit operations; i.e. fine or ultra-fine milling (UFM) and pressure oxidation under mild conditions. An under-standing of, and ability to control the pulp chemistry during oxidation has resulted in the successful Activox® treatment ( on a batch scale) of a wide variety of sulphide flotation concentrates; • pyrite/arsenopyrite + gold • pyrite/chalcopyrite + gold • pyrite/chalcocite + gold • pyrite/enargite/tetrahedrite + gold Oxidation rates are rapid (1-2 hours retention time) and gold

Jan 1, 1995

By Aditya Rana, A. K. Mishra, M. M. Singh, N. K. Bhagat

Many cases of derailments, train accidents and traffic interruptions due to the slope failure and rockfall have been reported in the past on Konkan Railway trackline because of unstable rock slopes. The authorities installed stability enhancement measures such as wire netting, rock bolting and shotcreting which were found insufficient. The failed geotechnical measures prompted authorities to excavate the unstable slopes. Rock blasting is generally not preferred for the excavation of slopes along the transportation route. Stabilisation and widening of slopes by blasting need closure of the route for a considerable time. Discontinuing traffic on Konkan Railway route was undesirable as it connects two important port cities Mumbai and Mangalore. The paper presents an innovative directional controlled blasting (DCB) technique for excavating three unstable slopes (i.e. cuttings) in hilly terrain without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw have been developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3 irrespective of the actual free face was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle has been changed from 80 to 82° to 45–47° and probability of wedge, planar and toppling failures was eliminated. About 100 such accident-prone slopes (52 km cumulative length, 7% of total route) situated at discrete locations along Konkan Railway route were stabilised using the technique. No incident of rockfall and slope failures along these slopes has been observed after the stabilisation.

By G. Orhan, C. Arslan

The possibility of producing metallic chromium from Cr2O3 via the aluminothermic route, with no external energy supply, was the subject of this laboratory-scale research. The experimental study focused on investigating the individual effects and quantitative optimization of the charge contents, i.e., the additions of CrO3, Al powder and CaO (or BaO). The highest chromium recovery of 98% was attained with the additions of 12% CrO3 and 1.2 times the stoichiometrically required amount of Al powder. The optimum CaO addition giving the highest chromium recovery was found when the CaO/Al weight ratio in the charge was equal to 0.3. When BaO was used, however, 95% Cr extraction efficiency was obtained at a BaO/Al weight ratio of 0.15.

Jan 1, 2000

By Tom L. Enos

Increased production through the plant was limited due to thickener circuit constraints. To overcome these constraints and maximize plant throughput to match grinding circuit capability, two options were considered: A. Adding 2000 TPD CIL circuit to operate in parallel with the existing CCD circuit. B. Adding a CIL circuit to treat the entire 4600 TPD while retaining some thickeners for tailings thickening. Option B was selected based on simplified plant operations, reduced operating costs, minimal capital requirements, reduced solution losses, and bullion grade improvement.

Jan 1, 1989

By J. Ke

Traditional geostatistical methods have been used in ore reserve estimation for decades. Neural Networks (NNs) have provided an alternative approach to data analysis and ore reserve estimation. Unlike the traditional geostatistical methods, neural network uses a highly non-linear complex algorithm to do the estimation. Although Neural Networks have been demonstrated to be attractive alternatives as with every new techniques, there are questions which remain unanswered. This paper presents a comparative analysis with different types of metamodeling approaches -- Triangular, Kriging, Spline, and Neural Network. The neural-network is organized in a multiple-layers and Back-propagation model is used to handle the non-linearity and hidden slabs for smoothing the predicted results. With multiple dimensional and very noisy drill hole sample data, the ore grade is predicted and the overall performance is validated by the analysis of R-squared (R2), Root-Mean-Squared (RMS), and contours of ore grade spatial variability. The ore grade and tonnage of estimated outputs are also compared with various cut-off grades.

Jan 1, 2003