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By John M. Moore

Within the Pofadder district of Namaqualand, South Africa, economically exploited deposits of bedded barite and zinc-lead-silver-copper sulfides occur in close proximity within highly metamorphosed mid-Proterozoic pre-tectonic para¬gneisses of the Namaqualand Metamorphic Complex (NMC) (figure i). The paragneisses belong to the Bushmanland Group (SACS, 1980) that comprises a relatively straight-forward regional sequence of basal leucogneisses, intermediate mica-sillimanite schists and glassy quartzites, and a mixed upper zone of banded iron formations (BIF), minor marbles, quartz muscovite schists and localised uppermost quartz-pebble conglomerates and amygdaloidal mafic gneisses (Joubert, 1974) (figure ii). The base metal and barite mineralisation occurs in close association with BIFs, generally above the glassy quartzites, although in some cases possibly below them. In the regional context, the Bushmanland Group paragneisses are, to the north, intercalated with and ultimately replaced by meta-volcanic sequences of talc-alkaline affinity (Reid, 1977) belonging to the Orange River Group (SACS, 1980). The metavolcanics are generally of acidic to intermediate composition and show evidence of subaerial formation from 'high altitude shield volcanism' with many acidic ashflow and welded tuff bands, mesocratic and lesser melanocratic lavas and some fanglomerates (Ritter, 1980). To the south and east, the schist/quartzite associations are initially intercalated with and eventually replaced by cordierite gneiss/metacarbonate/biotite gneiss associations of shallow marine affinity (Moore, 1980a). The Bushmanland Group paragneisses appear to represent sedimentary material in the extreme distal portions of a talc-alkaline volcanic environment adjacent to a shallow platform sea.

Jan 1, 1983

By E. R. Bauer

A primary goal of Ground Control Research, Bureau of Mines, U.S. Department of the Interior, is to develop information that can be used by the mining industry to reduce accidents and fatalities due to failure of mine roof. A specific research objective is to determine methods to detect hazardous coal mine roof. This paper reviews the existing and experimental techniques, and describes a recent Bureau of Mines contract research project that resulted in a simple technique and prototype instrument for evaluating mine roof competence.

Jan 1, 1986

The 30th annual American Mining Hall of Fame Awards Banquet and Fundraiser sponsored by the Mining Foundation of the Southwest (MFSW) will be held at the JW Marriott Star Pass Resort, Tucson, AZ on Saturday, Dec. 1, 2012. Each year, one living inductee, two recipients of Medals of Merit and up to five honorees from mining history are chosen by the MFSW for their outstanding contributions to the mining industry. Gregory H. Boyce will be the guest of honor, featured speaker and inductee into the American Mining Hall of Fame. Boyce, chairman and chief executive office of Peabody Energy, is being honored for his leadership in the coal industry.

Jan 1, 2012

By Matt Bilson, Ritesh Mahajan, Antoni Kuras, Wataru Okada

The Waterview Tunnel comprises twin 2.4 km long 13.1 m internal diameter three lane road tunnels in Auckland, New Zealand. The City Rail Link (CRL) is a 3.45 km long, 6.24 m internal diameter twin rail tunnel underneath Auckland’s city center. This paper presents an overview of the tunnel geometry, segmental lining congurations, geometric constraints, performance criteria and functional reuirements for the large diameter Waterview Tunnels and smaller diameter CRL tunnels. Other key aspects, which include sustainability, innovations, construction performance and practical aspects are discussed and compared. Lessons learnt from these mega tunnelling projects are also presented.

Jun 23, 2024

By George S. Barnett

The Equis and El Roble projects are located in the Cordillera Occidental of Colombia. The Equis vein deposits have sulfide ore reserves of 95.9.5.5 mt (105.770 st) grading 8.51 g/mt (0.248 oz/st) gold and 12.4 g/ml (0.36 oz/st) silver with 0.94 % copper. 1.10 a lead and 11.06% zinc. Ore reserves at El Roble are estimated as 1.1% Mmt (1.21 million st) grading 4.89% copper and 3.39 g/mt (0.099 oz/st) ,old. Geologically possible reserves at Equis may total 1.6.Mmt (1.76 million it). El Roble has the potential to contain several tens of millions of metric tons. Exploration included diamond drilling, trenching, channel sampling, rock and soil geochemistry, geophysics and tunneling. Erratic high grade samples affect the weighting of channel and drill core samples. Secondary reconcentration of gold is also a factor. Sample maps and graphs show the distribution of values to be highly variable. Geostatistical treatment of some of these data gave important guidelines for parameters such as sampling densities, drill hole spacing and confidence limits.

Jan 1, 1984

By K. Dagdelen

The definition and shortcomings of traditional cutoff grades are discussed. The concept of optimum cutoff grade policy which maximizes the Net Present Value (NPV) of annual cash flows coming from a mining project is introduced within the basic framework outlined by K. F. Lane. Several examples are used to demonstrate the shortfalls of cutoff grade policies obtained by various heuristic optimization techniques. An algorithm to obtain an optimum cutoff grade policy which maximizes the NPV of a project is given and described in detail.

Jan 1, 1993

By J. J. Scott

As a Rock Mechanics investigator, the author has, Over his career, attempted to use his best knowledge in developing better rock control fixtures. Based on the experience of nine years of development of friction rock stabilizers, in 1980 he decided to launch a new investigation to develop a unique roof support fixture which would fit the coal mining market. The largest single user of roof bolts in the world is the American coal mining industry, historically using up to 100 million fixtures per year. In 1989 they used approximately 82 million fixtures.

Jan 1, 1990

By VASU GANGRADE, Marcia Harris, Kumar Vaibhav Raj, Jim Addis, Khaled Mohamed, Snigdha Sarkar

The National Institute for Occupational Safety and Health (NIOSH) conducted a ventilation assessment for a recently established underground room-and-pillar stone mine implementing split-mine ventilation. The primary objective was to examine the impact of the length of the in-place stone stoppings on face ventilation efficiency. These stone stoppings serve to separate the intake and exhaust entries and align with the mining direction. To achieve this, computational fluid dynamics (CFD) modeling was utilized. The appropriate turbulence model was selected, and a mesh convergence analysis was conducted for the CFD model. Following that, the CFD model was validated using the conducted ventilation surveys. Two configurations of in-place stone stoppings, designated as Layout-I and Layout-II, were simulated using the validated CFD models. Layout-I featured a shorter in-place stone stopping, while Layout-II had a longer one. The results obtained from the CFD models demonstrated that the increased length of the in-place stone stopping in Layout-II resulted in a notable enhancement in ventilation efficiency at the advanced faces (last stopping), elevating it from 4% in Layout-I to 8.4% in Layout-II. However, no significant impact of the in-place stopping layouts was observed at other faces. In general, Layout-II exhibited a greater circulation of air at the outby stoppings.

Feb 1, 2024

By E. J. Karges

[For reasons well known to Mining Engineers, fine grinding in the wet form is quite universal inn plants engaged in the traction of metallic values from crude ore In the processing, of non-metallic and industrial minerals, however, fine grinding in dry form is the more common method. The crude materials generally contain less moisture than required for wet grinding, and the products are usually marketed or used in the dry form, most of them as powders. To grind wet would therefore entail the addition of water and the expense for drying the product, which is not justified. This paper will concentrate on the particle size reduction or fine grinding of materials to produce a dry powder]

Jan 1, 1963

By T. Tamagawa

A gaseous chlorination process for hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low temperature chlorination-selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper elemental sulfur and ferric oxide. In this article, the chlorination phase of the processes is described. Initially, the chlorination behavior of chalcopyrite-concentrate micro-pellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established was used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 1999

By L. J. Habegger

This paper considers the potential water quality impacts of future energy scenarios which project an approximate doubling of coal utilization from 1975 to 1985. The major impacts estimated for coal extraction are related to effluents from unregulated activities (reclaimed areas prior to stable vegetation) and pollutants (e.g., metals and ammonia). Where applicable, the EPA effluent guidelines to be in effect by 1983 reduce the impact of individual sources to low levels. For example, total suspended solids and acidic discharges are to be regulated to levels generally below recommended water quality standards for receiving streams. However, implementation of these guidelines, particularly for coal extraction, has not been demonstrated on a wide scale. Water quality is not expected to be a major constraining factor for increasing capacity of coal fired utility and industrial boilers. Water quality control has not been demonstrated on a commercial scale for coal conversion to synfuels, but adequate control technologies appear to be feasible.

Jan 1, 1978

By Michael F. Gleason

In 1986, Gold Fields began negotiations with a large Nevada electrical power utility to supply power for its Chimney Creek Mine In northern Nevada. After the long negotiations reached an impass over various costs associated with the power line, a decision was made by Gold Fields to generate its own power. Self-generation is not uncommon overseas, but it is rare for any but very large or very small operations in the United States. Surprisingly, under certain conditions a mine can generate its own power profitably and Gold Fields has found that the associated operating and maintenance problems are minimal. The following report details what factors went into this decision and how it works. Hopefully, it can serve as a guideline for those who may find themselves in a similar position.

Jan 1, 1990

By C. L. Coldren

Recently there has been much discussion of the use of pipelines for the long-distance transportation of solids. Many have come to recognize the economies inherent in pipeline transportation. The widespread movement of oil and gas at astonishingly low costs - a gallon of oil moves from Montana to New York for less than that for the delivery of a postcard - has spurred others to sturdy this mode of transportation. Most interested people are aware of the inherent advantages of pipelines - continuity and reliability of operations - low manpower requirements per ton mile - moderate capital costs per ton mile - low maintenance costs per ton mile - low operating costs per ton mile.

Jan 1, 1963

By D. L. McCain

In considering slurry transportation for Consolidation Coal Company's Loveridge Mine in Northern West Virginia, many things were taken into account. The advantages of slurry transportation in comparison to shuttle car, belt and rail transport have been given in previous publications." These include increased safety and the potential for increased productivity. In addition to these considerations, the slurry transport system installed in an existing mine provides an alternate or additional transportation mode to the one already existing. In the Loveridge Mine, this is rail haulage. Since the rail system is a single track system and the distances involved are several kilometers, it is not always possible to provide for haulage of loaded cars, return of empties, supplies and maintenance in an efficient manner. Slurry transport of the coal from the production faces to the preparation plant allows the rail system to fulfill the remaining transportation needs in an efficient manner. Consol initiated development work in slurry transportation in the early fifties leading to the construction and operation of the 174-km (108-mile) Cadiz-to-Cleveland pipeline which carried 1,200,000 metric t/y (1,300,000 t/y) from 1957 to 1963. Development work on coarse coal slurry transportation for underground mines started in 1970 with feasibility tests on coarse coal at Conoco's Ponca City, Oklahoma, slurry test facility. A series of tests were conducted in several locations as development work proceeded on the various subsystems, mechanical equipment and controls required to produce a working system to follow a continuous miner in a room-and-pillar type mine, then to combine the coal production from several mine faces for mainline transportation to the preparation plant. The face system, including the crusher-pump vehicle, hose hauler vehicle, slurry booster pump units, return water unit and 900 to 1,200 m (3,000 to 4,000 feet) of pipeline was brought together for the first time and tested as a system at Consol's Robinson Run Mine in northern West Virginia in 1975. A pipeline wear test at the Loveridge Mine where 300,000 tonnes (330,000 tons) of minus 127-mm (5-inch) run-of-mine coal were pumped from the raw coal bin into the preparation plant and a large scale test in Ponca City on a multiple feed sump where several slurry flows could be combined to provide surge capacity and a constant reclaim rate for mainline transportation completed the preliminary testing for a complete system. A decision was made to commit the system to a mine, and the south half of the Loveridge Mine was chosen. This site required the transporting of coal from one longwall and two continuous miner development faces. To prevent startup and unexpected problems in the slurry system from shutting down production of coal from the longwall face, the rail car loading point from the main section belt was chosen as the feed point for the slurry system and the design would allow for rapidly switching from one transport mode to the other. Scheduling of required development entry work and the developmental nature of the system led to a decision to install only one continuous miner face slurry transport system rather than two for this first system. The type of continuous miner in use at the mine for the foreseeable future was the Joy 2BT6 twin boring machine. This machine cuts a stable, arch-shaped entry and was therefore allowed to mine about 26 m (85 feet) of entry before roof bolting was re¬quired. Since peak production from this type of machine was not high, a smaller transport system could be used with it.

Jan 1, 1981

By F. W. Petersen

Slurry reactors are being used extensively throughout the chemical, biochemical and mineral processing industries. This paper describes the interaction between fine ore particles and granular porous adsorbents such as activated carbon and ion-exchange resins in a stirred tank reactor. Gold and silver cyanides were used as adsorbates to detect changes in the mass transfer characteristics of the adsorbents, which were ashed to determine the loading of ore particles. A simple kinetic model incorporating film diffusion, intrapanicle diffusion ~d the adsorption equilibrium, was used to interpret kinetic data and to estimate the effect of slurry conditions on the diffusion parameters. It was observed that the equilibrium loading of fines in the adsorbents was independent of their concentration in the slurry. Furthermore, the presence of these panicles inside an adsorbent decreases the effective diffusion of gold or silver cyanides into the adsorbent matrix. When fine suspended solids are present in the reactor, a decrease in the effective availability of the superficial surface of the pre-saturated adsorbent panicles for mass transfer from the liquid phase was observed. This newly defined surface availability factor was dependent on the concentration, panicle size, and the zeta potential of the fine particles in suspension.

Jan 1, 1993

By B. A. Wills

With the increasing need to mine lower grade ores, high energy-related costs in comminution are of major concern. Very fine grinding is needed to liberate the very fine mineral particles in these ores. Not only is this expensive but it leads to greater losses in 'slimes'. In the early 1970's, 50% of the tin mined in Bolivia, 30% of the phosphate mined in Florida and 20% of the world's tungsten were lost in this way (Somasundaran, 1979). Gravity concentration techniques become unacceptably inefficient for particle treatment below 25-50µm, and even flotation fails in the ultra-fine range. Two approaches can be adopted to try to overcome this problem. The first involves increasing the efficiency of existing equipment or developing new slimes treatment processes. Gravity devices such as the Bartles-Mozley concentrator have been developed for this purpose and good recovery has been reported from 100µm down to 5µm. Such machines, however, have relatively low throughputs, so that large areas of plant space are generally required. Flotation is rapidly growing in importance for the treatment of ultra-fine minerals traditionally treated by gravity concentration.

Jan 1, 1986

By Egons R. Podnieks, Wallace W. Roepke

Mining technology to utilize vital lunar resources will be required for any commitment to permanent lunar basing. Lunar mining must be viewed both as a major supporting element for space resource commercialization and for creation of human settlements on lunar and planetary surfaces to support long-range space exploration. The Apollo missions to the lunar surface and results from fundamental research on analogue lunar rocks by the Bureau of Mines, and others, have provided the initial data for developing lunar mining technology. The multi-disciplinary research projected in this paper outlines the scientific and engineering needs to realize the lunar mining goals.

Jan 1, 1990

By Steve Karl

"The global underground construction and tunneling industry is in pretty good shape. Billions are being spent in shoring up aging infrastructure in the United States and other places, and new underground projects are being put out for bid.With each new project, comes new equipment, technology and tunneling methods. So it is incumbent on tunneling professionals to constantly improve their knowledge of the profession. This is where spending a few days with other underground construction professionals can assist the tunneler in keeping up.Every two years, tunnelers and underground construction engineers, contractors, suppliers, designers and owners from around the world gather for the Rapid Excavation Tunneling Congress (RETC). The 2017 conference was held in June in San Diego, CA. The UCA of SME puts on the conference.This years’ RETC attracted 1,400 attendees. The accompanying sold-out exhibit totaled 188 service and equipment suppliers. In addition, the conference had the UCA of SME bookstore, where the new History of Tunneling in the United States book was introduced. And a short course on tunnel rehabilitation was featured.Technical programmingRETC 2017 featured nearly 100 technical presentations. Topics covered the breadth of the global underground construction industry. Here is a sampling of a few. The proceedings from the conference is available from SME, 303-948-4200, www.smenet.org.Accomplishing extraordinary tasks as a machine supplier for Metro Doha: The construction of the Metro Doha in the State of Qatar established a modern, safe, efficient and integrated public transportation network. Upon final completion of multiple phases, the network will comprise four metro lines with a length of 216 km (83 miles) and 100 stations. Phase one comprises 112 km (43 miles of underground tunnels (56 km or 22 miles of twin-tube tunnels). Twenty-one earth pressure balance tunnel boring machines (TBM) were deployed by the four different joint ventures. The project was initiated, managed and supervised by the owner, Transport Authority Qatar Rail.Phase two of the Doha Metro will start upon the completion of Phase One in 2019 (Qatar Vision 2030). The owner placed full faith in the manufacturer’s abilities to deliver equipment of high quality, state of the art standards within the given time frame. This paper focused on the manufacturer’s scope of delivery and on the supplier’s high standards of quality in production, logistics and services."

Jan 9, 2017

By Franziska Günther, Helmut Mischo

The calculation of costs for an underground mine, as well as the planning of the equipment and materials to be used, is a complex and time-consuming process. The estimation depends on a multitude of parameters, and all mining processes are interconnected. A novel tool has been developed that enables automated calculation of underground mines and allows for the comparison of the effects of changing individual parameters. Previously, changing individual planning parameters often necessitated a complete recalculation of the mine. The newly developed calculation tool provides an innovative planning aid that allows for more efficient and accurate mine planning and cost estimation. The tool enables the user to implement continuously up-to-data costs and prices. This allows for more accurate planning data and results. The underlying concept of the calculation tool, its implementation at a planned quartz porphyry mine in Germany, and the verification of the tool at an existing underground mine will be presented.

Feb 1, 2025

By Del Brock, Dan Wooton

The design/build of two adjacent vertical mine shafts in difficult ground conditions at a mining complex in the midwestern United States required innovative construction techniques. Construction of the 267-m-deep Service Shaft required full depth dewatering wells and ground freezing. Blind drilling was utilized to excavate the 257-m-deep Production Shaft and it was finished with a steel/concrete composite liner that was floated into place. An equally unique component of the installation included supplying a high capacity vertical conveyor system, featuring a 273-m-lift. Other components of the project include the mine level development, as well as the design and installation of three hoisting systems, including a 45-ton capacity men/materials hoisting system.

Jan 1, 2003