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By Fredy A. Elorrieta Agramonte, Gabriel von Rickenbach, Roberto Luis Fonseca, David Córdova Rojas, Rolando Romero, Rico Brändle

The mine’s economic life is dynamic by nature. Some factors that create this scenario are the need to recognize new exploitation areas, the evolution of the mineral prices and the development of new technologies to access them. The dynamics of mining development, especially in the underground environment, changes significantly as the stages unfold. In many cases the final solution differs greatly with the initial. The frequent presence of new conditions and factors often cause the mine to develop in a quasi-permanent transition stage, which could be characterized by the generation of dynamic micro-seismic events that could cause rockburst damage in some specific areas. Although they may be infrequent, these dynamic events can have an important adverse impact on mine safety and causes serious losses. Also, changes in the production schedule during exploitation could be a big issue if the problem is not effectively addressed. When the transition of the mine to an active micro-seismic environment begins as an unforeseen scenario, it is frequent to use static ground support systems as they are readily available. Traditionally, the support systems used are reinforced shotcrete with a middle layer of Welded Standard Wire Mesh (WSWM) and Chain Link Standard Wire Mesh (CSWM) of reduced gauges, i.e. wires less or equal than 4 mm in diameter. Although, this support system is used to control static instability problems, there is no good reference of its energy absorption capacity under dynamic load conditions, creating uncertainty in the effectiveness of controlling rockburst events. These support systems are analyzed at the present paper, testing the reinforced shotcrete layer with 4 mm diameter of WSWM and CSWN under dynamic load. Additionally, the influence of the use of high tensile strength steel wire in the meshes (HSWM) compared to the previous ones, is analyzed to assess the scope in controlling rockburst events and keeping the safety of underground environment.

Apr 26, 2022

To generate a most profitable ultimate pit limit is generally the first step in mine design. This paper presents a new graph theory oriented, optimum ultimate pit limit design algorithm which will maximize the total undiscounted net profit. This algorithm performs much better than the well known Lerchs-Grossmann algorithm, in terms of the reduction in computation time and computer memory requirements. This algorithm operates on many directed trees in a graph, where each vertex in a tree represents a block in the mine model. The formation of each directed tree is based more on the ore-waste support concept than the geometry constraints alone. The general procedures of the algorithm, programming considerations and two case study results are discussed in the paper.

Jan 1, 1990

By Nicholas Tabor, Norbert Fuegenschuh, Richard Taylor, Jean-Marc Wehrli

The Plymouth Tunnel forms part of the 16-mile long route of the Purple Line Light Rail Project promoted by the Maryland Transit Administration. The tunnel is approximately 1,220 feet in length with a shallow vertical alignment located beneath a residential area. Challenging mixed ground conditions included surficial soils, decomposed Saprolite, and highly weathered to fresh rock requiring the use of the Sequential Excavation Method (SEM) for construction. This paper discusses innovative approaches implemented during construction as well as challenges faced during planning and installation of a spray-applied permanent concrete liner.

Jun 13, 2021

By Francisco A. Fonseca

The Carajás Hills are in Brazil's Eastern Amazon, between the Araguaia and Xingu rivers, and parallels 5° and 7° Latitude South. A location map is given in Fig. 1. It is an area of low mountains (maximum altitude 900 meters), covered by the Amazon rain forest. Annual average temperature is 25°C, ranging from 31°C (maximum) to 19°C (minimum). Annual rainfall averages 2,000mm. Although it rains throughout the whole year, heavy rains occur from December through March. At the beginning of the 20's, Brazilian explorationists made brief geological descriptions of the area. Due to the thick soil, scarce fresh rock outcrops and the tropical forest covering a completely unpopulated area, detailed geological studies were difficult and reconnaissance expeditions were limited to the river margins.

Jan 1, 1982

By B. W. Cavender

The operating lifetime, or production rate, selected for a mining project is among the most important factors influencing the design and ultimate economic success of the project. An incorrectly-determined lifetime can lead to the erroneous rejection of projects as uneconomic as well as the suboptimal exploitation of producing properties. This paper examines the calculation of the optimal lifetime using both traditional discounted cash flow and recently-proposed option pricing techniques. Using each method, the production rate is determined as that rate at which the net present value of the project is maximized.

Jan 1, 1992

By Guillermo P. Salas

The Consejo de Recursos Naturales No Renovables of the Mexican government entered into an agreement with the United Nations in 1964 for the mineral exploration of a large area in Estado de Sonora, Mexico. The agreement called for a systematic exploration for copper in northern Sonora based on photogeologic mapping, aerial reconnaissance, and geochemical stream sediment sampling. The UN-CRNNR investigations resulted in the detection of anomalous copper values in sediment from the Arroyo Cruz de Cafiada. The anomaly was followed upstream to its source, which ultimately proved to be the La Caridad ore body (see Fig. 1). Soil copper and molybdenum values were found over a large area, and further detailed geologic and geophysical investigations were instituted of the anomalous area. David Coolbaugh was largely responsible for the follow-up work. An induced polarization (IP) survey found a roughly circular region of "highs" that coincided with a high soil copper anomaly. The circular anomalies ringed the topographic feature that ultimately was found to contain the Caridad ore body. Soil geochemical copper response over the ore body was subdued, because the soils were derived from a leached capping, whereas leaching in fringe areas that contained less veining was less intense. The ore body was also ringed by the typical high pyrite zone, and this was the anomaly detected by the IP survey. The UN began drilling in the fall of 1966. Eleven holes tested the IP-Cu geochemical high, but none were of commercial interest. The project was returned to the Consejo and was reviewed in the field by G.P. Salas and V.F. Hollister. It was found that the leached capping had not been tested by the past activities, and the Consejo elected to explore that area in 1967. The capping was evaluated by Salas and Hollister and drilling by the Consejo began in 1967. Commercial grade ore intercepts were found in the first hole. The Consejo drilled nine holes, of which eight were commercial. At least 90.7 Mt (100 million tons) of 0.8% copper were indicated by the Consejo in eight holes. The lesson learned in this discovery is that evaluation of leached capping is an important guide to exploration. The general-

Jan 1, 1991

By F. W. Mueller

It seems to be a matter of general understnading that title extraction or use of ground water may not be used as the basis of a depletion deduction under the United States Revenue Code And indeed, I have been unable to find any precedent upon which to base such a deduction. It is for this reason that the Shurbet case, which is the subject of my discussion and is now before the Court, may well become a precedent as authority for the allowance or disallowance of a depletion deduction for income purposes. It is well known that the law recognized that capital is consumed in the process of extracting minerals, oil and has, other natural deposits, and timber (underscoring supplied). This exhaustion, or depletion, is likened to the using up of raw materials in manufacturing. The law, therefore, provides a deduction for depletion which is intended as compensation for the exhaustion of assets consumed in the production of income through severance of minerals, oil and gas, other natural deposits, and timber.

Jan 1, 1962

By Atta Ur Rehman, Kwame Awuah‑Offei

This paper examines the effect of bucket geometry (cutting blade profile, floor profile, and blade thickness), speed, motor power output, and muckpile particle sizes on bucket penetration and draft for rubber tire loaders. The work uses a 1:16 scaled model of a load-haul-dump in full factorial experiments to examine the effect of the variables on penetration and maximum draft. The results show that speed and motor output are positively correlated to penetration and draft; muckpile particle size is positively correlated to penetration and negatively correlated to draft (p < 0.0014). The results show that buckets with a semi-spade cutting nose profile yield the highest penetration (mean 118.30 mm) followed by those with the spade (mean 108.88 mm), which also yield higher penetration than those straight blades (mean 95.19 mm). Bucket floor profile and blade thickness had no significant effect on penetration or draft. Also, we determined that increasing the speed and motor power output, simultaneously, can reduce bucket penetration. Thus, operators should not waste energy for no additional gain or even loss in bucket penetration. Also, the work finds speed and motor power output each combine with muckpile particle sizes to affect bucket penetration. This research furthers our understanding of the effectiveness of different bucket geometries in improving penetration and reducing draft for rubber tire loaders.

Oct 29, 2021

By James A. Bloom

To operate the Morris Fork Preparation Plant with a closed water circuit has been an elusive goal for Union Carbide. The benefits of a closed circuit have never been questioned. The removal of fine solids from washery water makes possible the recirculation and reuse of the water. Heavy media drag tanks and other separating machines perform better and more consistently with washery essentially free of fine solids. Finally, the production of a clarified effluent makes unnecessary the sludge ponds usually associated with a coal preparation plant. Why then do I say elusive? Because, since plant design was completed in 1970 we have been in hot pursuit of an ever-growing fine solids problem. In four years the minus 28 mesh material in the plant feed has nearly doubled. The replacement of conventional sections with continuous mining machines has led to a lowering in size and quality of product from the mine. In addition, increasing emphasis underground on roadway clean-up has contributed to the fines problem.

Jan 1, 1975

By John Sasadi

Several years ago I wrote a comprehensive paper &apos;entitled, "Future Trend of Bulk Carriers" dealing with the principle dimensions of vessels and how they can be predicted; then with loading and unloading of large carriers, especially considering various designs of "Self Unloaders". Since writing the paper, many large bulk carriers were basically built along the, predictions made. Maximum size today is in the 150,000 DWT class, with few exceptions, which are combination carriers (ore-oil) or OBO&apos;s (oil-bulk-ore) in the 200-250,000 DWT class in the same paper, many references were made cautioning engineers not to design ports which could be "obsolete tomorrow", however, these were not always followed. Nevertheless, during the past few years many modern ports were built signaling the beginning of a new area of "Super Ports". Super Ports can be built for various reasons, most important to provide transfer stations where bulk material is received from large carriers then transferred to smaller vessels or barges for distribution. Obviously, opposite movement of bulk commodities can justify the building of "Super Ports", however, these are not as difficult to build for many reasons. The Material Handling Industry has developed efficient means of unloading smaller vessels or barges with continuous-type unloaders and has mastered the art of storing, reclaiming, and moving large quantities of bulk material to high-capacity shiploaders. Nevertheless, the industry has failed to design and market efficient ship unloaders which in any way could match the presently attainable shiploading rates. For these reasons, it is considerably more difficult to build "Super Ports" for incoming rather than outgoing bulk materials with large bulk carriers. The purpose of this paper is to elaborate on problems affecting high-capacity, continuous ship unloaders, especially involving large bulk carriers. For better understanding, some references will be made to the smaller, continuous barge or ship unloaders, but only as the principles affect the larger units. Additional references will also be made to exploit the present "State-of-Art" of the grab

Jan 1, 1972

By R. L. Hudak, R. F. Randolph, A. S. Azman

The mining workforce experiences high rates of hazardous noise exposure and hearing loss. However, previous studies have identified specific behavioral and attitudinal barriers that keep miners from effectively acting to prevent their own hearing loss. The National Institute of Occupational Safety and Health (NIOSH) has developed several new hearing loss prevention tools and interventions that specifically target these barriers to prevention. The NIOSH Hearing Loss Simulator addresses motivation to take action and knowledge about the consequences of noise exposure. The QuickFit earplug test device and QuickFitWeb online hearing protection tester address barriers to effective earplug and earmuff use by verifying at least 15 decibels of protection. The NIOSH Roll-Pull-Hold technique helps miners obtain better protection through an easy-to-remember set of steps that improves attenuation by nine decibels. The “Inquiring Ears Want to Know” fact sheet helps miners to understand audiograms and to use them to maintain their hearing health. Each of these interventions can be used within the context of a comprehensive hearing loss prevention program.

Jan 1, 2010

By Siyu Song, Yanhong Wang, Guohua Gu, Linbo Huang

In this study, the effect of cations, Na+ and Mg2+, in saline water on copper flotation in the presence of calcium bentonite was investigated. It was found that as the concentration of NaCl was increased, the copper recovery initially decreased and then increased to above 99%, while the copper grade initially increased and then decreased. In contrast, as the concentration ofMgCl2 was increased, the copper recovery continuously increased, while the copper grade continuously decreased. The variation of copper recovery and grade was mainly attributed to the synergistic effect of pulp rheology and flotation solution chemistry. The underpinning mechanisms are the compressing electrical double layer and ion-exchange interaction between saline water and bentonite, which occur at the same time. Using salinewater slightly affected the pulp rheologywith a decrease in copper recovery at low NaCl concentration. Increasing the concentration of cations in saline water might even facilitate the flowing out of exchangeable cations, especially divalent cations, from the interlayer space of bentonite to the solution, resulting in the decrease of copper grade at high salt concentration.

Sep 10, 2020

By Dieter Loh, Mathias Knoll, Florian Werres

When a new tunnelling project starts, it has been a vital tradition for decades to cast and erect master rings horizontally on a flat surface to demonstrate the compliance with dimensional tolerances. Some tenders ask for the erection of two or even three rings upon each other or repeated master ring erections at intervals throughout the project. Especially for large diameters, this is a challenging and risky task for the workforce in the segment factory. A truck-mounted crane is often necessary, and in some cases it can take up to a week to complete a master ring. The concept of virtual rings has the potential to replace this tradition by assembling master rings digitally instead of physically. This is based on a best-fit approach, considering the 3D coordinates from laser tracker measurements of segments or segment moulds. Building a virtual ring, a sub-millimeter accuracy can be achieved, the alignment of neighboring circumferential and ring joints observed, and the fit of bolt holes checked. The traditional method, on the other hand, is discussed controversially despite the significant amount of work and risks—particularly as the horizontal position of the ring and absence of gaskets do not simulate the reality in the excavated tunnel. This paper will highlight the technical aspects of virtual rings, as well as their pros and cons, illustrated by a case study from London Thames Tideway where a total of 30 physical master rings could be replaced by virtual rings.

Jun 13, 2023

By Santhanam Sundaram

The potential for the utilization solar energy for the production of industrial process steer in mineral processing industries is discussed briefly. To advance the technical and economic feasibility of solar-thermal systems applications, U.S. Department of Energy has funded several projects. NL industries of Newberry Springs, California is one among them and has been chosen as a case study. The NL Industries solar system consists of 950 square meters of Del, single-axis, tracking, parabolic-trough, concentrating collectors. It was designee to produce a portion of the 420°. 530°k. steam utilized in a trying operation reduce the moisture content of hectorite ore from 10 percent to 4 percent. (Hectorite is an hydrous magnesium silicate which, when refined, is of significant commercial interest because of its applications in various chemical and food processes.) is estimated that implementation or this solar system could result an annual savings of 3.545 billion KJ ,3.360 billion BTUs), or the equivalent of 90 cubic meters (600 barrels) of oil and a net reduction of 1,860 kilograms (4100 pounds) of air pollutants annually. The technical, economic and institutional issues encountered in the course of this project are also discussed. Finally, the impact of the commercialization of solar energy applications in mineral processing industries is evaluated.

Jan 1, 1981

By James J. Komadina

INTRODUCTION Newmont Gold Company&apos;s Rain operations are located in Elko County, Nevada, approximately 9 miles southeast of the Town of Carlin.The property was submitted to Newmont Exploration Limited in 1979 and underwent development drilling over the course of the next four years, culminating in the completion of a project feasibility study in October 1986. Initial project scope included development of an open pit mine, an 815,000 DSTPY heap leach, a 572,000 DSTPY mill (Mill No. 3), and associated support facilities. Approval to proceed was given by Newmont Gold Company management in June 1987. Detailed engineering began in early July, followed immediately thereafter by procurement of major equipment components through various second hand sources. PROJECT DESIGN Keep It Simple In early August, Newmont Mining Corporation, parent company of Newmont Gold Company, became the takeover target of an "investor" group headed by T. Boone Pickens. Details of the ensuing events have been well documented by the press; suffice to say their impact on this project was material and required immediate flowsheet changes. Project design throughputs were increased to 1,000,000 DSTPY and 760,000 DSTPY for the heap leach and mill, respectively, in mid- September. These changes caused major project headaches as all general arrangement drawings had been approved and structural steel as well as concrete contracts were in place. Additionally, ground breaking was to commence in two weeks time! Rain project management assembled shortly after the announced changes, to devise an engineering and construction strategy capable of handling these new business conditions. The project had been justified using a gold price of $325 per ounce with a forecasted overall cash cost per ounce of $230. Hence, strict control of capital expenditures was necessary to maintain development economics. Mill start-up had also been moved forward one month, to August 1, 1988. To meet an already ambitious schedule, construction techniques needed to be simple and proven as most of the facilities were planned for erection during winter at a site with design criteria of -40F and 90 mile per hour winds. Perhaps the most critical factor requiring consideration was that of personnel. Newmont Gold&apos;s revised business plan called for corporate-wide production increases from 587,000 ounces per year in 1987, to 1,400,000 ounces by mid- 1989. Labor requirements were forecasted to grow from 900 employees to over 2,100. This fact, in combination with the rapid growth of Nevada&apos;s gold industry, led to the expectation that turnover of operating personnel would be extremely high. It was concluded that, to meet cost, time, and operational goals, the necessary strategy could be succinctly put - "Keep It Simple." Mining/Metallurgical Factors The Rain deposit consists of three interconnecting mineable shapes with host rocks ranging from 90%+ barite to a highly silicified jasperoid. Due to a limited number of mining faces in the first two years, in-pit blending

Jan 1, 1990

By Ihsan Berk Tulu, Mustafa Can Suner

The synthetic rock mass (SRM) approach and discrete fracture network (DFN) model, generated from the field surveys, are novel methodologies to study fracture rock mass behavior. In this paper, SRM and DFN methodologies were used to understand the influence of natural fractures on the mechanical response and failure mechanisms of stone mine pillars. First, a multi-stage up-scaling procedure with the homogenization process is established. Later, a stochastic sampling process on the SRM model to have further insight on the stone mine pillar mechanics is performed. Two-dimensional Universal Distinct Element Code (UDEC) is utilized to represent intact rock with the Voronoi-Trigon discretized blocks and to capture fractured rock mass behavior. The laboratory-size limestone mine rock specimens are systematically up-scaled to the average width of the field-size stone mine pillars. Then, the DFN model, generated from field data, is sampled to construct the SRM of the field-size pillars. By doing so, the effect of discrete discontinuities on pillar stability is studied by assessing the pillar strengths and failure mechanisms in various width-to-height ratios.

Jul 8, 2022

The properties of interfacial water at hydrophilic surfaces are of great importance in many technological areas including flotation, solid-liquid separation, dispersion and emulsions, flocculation, adsorption, corrosion, and soil contamination. This paper examines the use of FTIR/internal reflection spectroscopy (FTIR/IRS) to study the spectral characteristics of interfacial water at silica surfaces. FTIR spectra were characterized by consideration of the OH stretching region (3000-3800 cm-1) associated with the vibrational spectra of interfacial water. The broad peak in this region was deconvoluted in order to isolate overlapping spectral features that describe the nature of hydrogen bonding in interfacial water. Three distinct bands were found; -3600 cm-1 (free OH), -3400 cm-1 (incomplete tetrahedral coordination), and -3240 cm-1 (complete tetrahedral coordination) and the variation of their intensities with pH was found to be significant. This spectral information helps to explain orientation and bond ordering of interfacial water molecules at hydrophilic surfaces.

Jan 1, 1998

By Hesam Dehghani, Farid Alimohammadnia, Nima Babanouri, Mokhtar Kalhori

In open-pit mining, blasting pattern design is performed to achieve a desired degree of fragmentation for loading, hauling, and crushing operations. Inappropriate fragmentation of rock will result in numerous problems such as incurring extra costs for secondary blasting, production interruption, etc. Wetness of the blast holes is one of the most important factors, which can cause the inappropriate rock fragmentation. Lowering ambient temperature in the vicinity of the explosion, the presence of water in the hole adversely affects the quality of the explosive while dissipating part of the explosion energy, ending up with inappropriate fragmentation problems. In the present research, in order to study blast-induced fragmentation conditions in Baba-Ali Iron Ore Mine, three scenarios were considered: explosion of ammonium nitrate with fuel oil (ANFO) in dry hole, explosion of ANFO in wet hole, and explosion of the emulsion in wet hole. For this purpose LS-DYNA, a numerical simulation code was used. Results of the present research showed that, compared to the explosion of ANFO in wet hole, the explosion of the emulsion produced more uniform distribution of fragment size, while the explosion of ANFO in dry hole resulted in fewer large fragments.

By Timothy O’Rourke, Karrie Buxton, Chris Lynagh, Daniel Dobbels, Frederick Vincent

The Doan Valley Storage Tunnel Project in Cleveland Ohio was constructed to control Combined Sewer Overflows (CSOs). It is a complex system of three tunnels ranging from 8.5 to 18 feet in diameter with a total length of about 2.3 miles that was put into operation in mid-2021. The project lies within and below the cultural, educational, and medical hub of Cleveland, which presented unique design and construction challenges. This paper provides a case history of the design and construction, with particular attention given to lessons learned in devising a large tunnel system that can carry both dry and wet weather flows constructed in rock with limited cover, within a flood plain area and vibrant urban center

Dec 1, 2022

By W. Robert Power

Dimension stone includes a wide variety of natural materials that are put to an equally wide variety of uses. It is possible to classify dimension stone according to the end use to which the stone is put or according to the lithology of the stone. Both schemes are used by the United States Bureau of Mines in the annual Minerals Yearbook. The 1969 Yearbook lists 15 specific uses and has additional miscellaneous catagories. The same Yearbook lists five specific rock types or lithologies, and also includes a miscellaneous category. In a short presentation it would hardly be possible to list and define all these categories, much less discuss the evaluation of deposits with regard to all possible combinations. Besides, I am only slightly familiar with some of the uses and their requirements. I have therefore chosen to limit my remarks to some special problems in evaluating dimension stone that is to be cut and finished to specific sizes, tolerances, and finishes for use in buildings and some monuments. This use class is called cut stone in the Minerals Yearbook. In terms of dollar value it is the largest single use category. In 1969 the dollar value of cut stone was $29,122,000 which is more than twice the value of the next largest category. For those of you who are interested in other use applications of dimension stone I suggest that you start with recent articles by Bowles (1960), Currier (1960), and Barton (1968).

Jan 1, 1972