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By Ing. E. h. Martin Herrenknecht, Werner Burger

In recent years, there has been a dramatic increase in the number of machine driven soft ground tunnelling projects. This increase is largely due to the technological development of slurry and EPB Shield systems. A new generation of soft ground tunnelling machines, markedly different from those of five years ago, now overcomes ground conditions that until now were too costly and impractical to undertake. The paper reviews the latest soft ground tunnelling machine developments in material transport, guidance and control, seismic surveying, soil conditioning, settlement control, cutting tool applications and variable mode operating systems. Specific projects where this technology has been applied will be highlighted.

Jan 1, 1999

By Geoff C. Knight

Longwall mining using the shearer is acknowledged internationally as the most economically successful method of high volume production from underground coal mines. Since its introduction in the 1950s, a great deal has been achieved in developing the capability and reliability of the shearer - and the associated face conveyors and powered roof supports - to produce the competent systems now widely deployed. Equipment will continue to improve as knowledge and experience are gained and through the influence of market forces on the international equipment suppliers. However, current systems are so successful that further improvements are likely to be incremental rather than radical unless a high level of system automation is introduced. The automation concept is not new to the shearer-based longwall system. The opportunity and the need were recognized soon after the shearer and powered support were introduced in the 1950s. In the early 1960s, the British Coal Corp. (BCC; then the National Coal Board) attempted remotely operate longwall systems. Those imaginative early schemes were seen as failures at the time. But, with hindsight, a great deal was learned from the experience that stimulated automation research in several European countries. One of the most fundamental lessons learned was that coalface system automation is not possible until there is a high level of competence in automatically controlling the operation of the production machine itself within the coal seam. Once that is achieved, the rest of the system will follow with comparative ease.

Jan 1, 1991

By Thomas E. Ban

During recent years fuel consuming industries of the United States have been caught between environmental restrictions and the uncertainty of obtaining an inexpensive fuel. With the advent of the National Energy Act of 1978 there has been added impetus to switch from gas and oil to coal. For industrial furnaces and boilers that were designed to bum coal, returning to an available compliance coal might be feasible. However, furnaces and boilers designed for gas or oil cannot reasonably be converted to coal unless the coal is initially gasified. All cases, nevertheless, depend upon the availability of an adequate structured coal of a compliance composition, a challenge to the coal mining industry. The foregoing problems have contributed to the current energy-coal crisis of today's economies. It therefore would be worthwhile to capitalize on previous experiences of the mineral processing industry.

Jan 1, 1979

By E. J. Hammer

In the crushing and grinding of metallics for beneficiation, the sizing is normally done to liberate the metals or sulphides for further processing to improve recoveries of the basic metals or minerals. The objective is to reduce the ore in size through various closely controlled stages to that degree of fineness which gives an economic liberation of valuable mineral, but which avoids as much as possible the production of sliming fractions. A different philosophy applies to the crushing and grinding of Gypsum. Our requirements normally demand controlled grinding and/or crushing of the material not only to a fineness suitable for further processing of the mineral into end products, but to produce various sizes of material which are them- selves saleable products. The majority of our tonnage ultimately ends up in stucco for Wallboard. Therefore, our mineral reduction is normally designed toward this end, but it is done in a manner that permits drawing off inter- mediate products to meet various Customer requirements. This forces us into compromises at times in our equipment installations, and our equipment must sometimes be more versatile and complex than we would like it to be. We try to process our basic rock, Gypsum, for the most efficient size reduction. We market 5 to 6 different sizes intermediate to the end product, which generally is the fineness of material to be used for stucco for Wallboard, and we do this with controlled crushing, grinding and sizing cycles of the material. To summarize, we use a different philosophy of crushing and grinding than the metallic field which uses comminution or crushing and grinding to improve recovery, whereas we choose our equipment to crush and grind primarily for product performance.

Jan 1, 1969

By G. Davey

High speed stirred milling is a relatively new method of grinding in the metalliferous process industries. However it has been it has been in wide spread use in the industrial mineral field for over 30 years for various minerals. Many existing metallurgical operations are looking to maximize economic return from existing deposits, requiring new thinking and technologies. The operating experience of two existing copper operations will be covered to show the effect of the introduction of the Metso Stirred Media Detritor (SMD) a new type of high speed stirred mill. Both operations have derived significant metallurgical benefits from the introduction of this new technology. The benefits and process difficulties are covered and explained.

Jan 1, 2003

By C. P. Mangelsdorf

Introduction During the 13 years since C. C. White introduced the Birmingham roof truss there has been a revolution in permanent roof support technology. While not all of the emerging concepts have their origins in the truss-resin bolting is a prime example - the combinations and permutations of devices presently available to the underground mining industry reflect a well-spring of creative activity. The purpose of this report is to chronicle a number of roof support system that have same physical similarity to the Birmingham truss, and to report on their application. Definitions The application of the tern "truss" to the device developed by White of the Birmingham Bolt Company in 1967 may be derived from the classical technique of stifwood, by the attachment of an underslung, sometimes pretensioned metal strap, rod or cable. If the beam is separated from the reinforcement by a single block or vertical post it is called a "King's Post Truss". If two equally spaced blocks or posts are used it is referred to as "Queen's Post". When the immediate roof of a mine is visualized as a beam, the Birmingham device completes a structure resembling this latter form.

Jan 1, 1982

By E. M. Frizzell

It is unlikely that improvement in truck efficiency and capacity can fully offset the effects of inflation, fuel cost/shortages, and increasing haul distances as in the past. Therefore, investigations of haulage systems less sensitive to these problems are warranted. Thus, this Bureau of Mines contract research study on alternative continuous haulage systems was prepared. This study identifies the physical, economic, and technological parameters in the application of continuous haulage systems with special attention to under pit slope conveyors and skip hoisting systems. The evaluation data were gathered from extensive literature searches, European/North American mine visits, and industry comments. The study concludes that continuous underground haulage is a viable method within the proper geometric configurations.

Jan 1, 1979

By Gail B. Knight

INTRODUCTION In May 1984, The Canadian Pacific Railway awarded to the Joint Venture of Foundation of Canada, Ltd. of Toronto, Atlas Construction Co. of Montreal, and S. A. Healy Co. of Chicago the contract for the construction of 27,000 ft of tunnel starting from the east portal. Selkirk contractors, the Joint Venture of Foundation, Atlas and Healy, which had successfully completed for CPR in 1983 the construction of both portal structures for this tunnel, studied several different alternative proposals before presenting its bid pooling each individual company's technical resources and experiences. (Foundation had just completed in association with other companies a similar tunnel project in British Columbia, and the S. A. Healy Co. could provide its experience of more than 40 miles of tunnels excavated by full face boring machines.) Among the alternatives investigated there was a fully circular tunnel to be excavated by a 30 ft diameter TBM, a full section drill and shoot proposal, and a mixed alternative, the "key hole" proposal, consisting of a TBM driven circular top heading followed by benching to design size. Technical, geological and economical considerations determined the alternative that was eventually proposed to CPR. HISTORICAL NOTES The tunnel construction parallels an existing tunnel through the Selkirk mountains that was excavated in 1885. In order to reduce the grade to 1% on the heavily loaded west bound trains, the new tunnel was at a lower elevation and lengthened to almost 9 miles. GEOTECHNICAL INFORMATION CP Rail site investigations began in 1978. The surface rocks in the tunnel construction area are metamorphosed Cambrian and Pre-Cambrian sediments; the underlying formation contains fine and coarse grained rocks presenting different degrees of metamorphism. The

Jan 1, 1987

By Roger L. Hulette

Mt. Newman Mining Co. is now completing an expansion program, begun even before initial construction was complete, which will result in facilities with the ability to ship over 30 million tons of iron ore per year by early 1973. Confidence in such rapid future growth was evidenced by careful planning for the future expansion of those facilities provided for initial operation of the project which first shipped ore on 1 April 1969. Ore sales contracts totaling more than 300 million tons have been negotiated, thus justifying the optimism which led the joint venturers to provide over $200 million in initial investment and a like amount in capital required to finance the continuing expansion program. Members of the Mt. Newman Joint Venture are: Amax Iron Ore Corporation - 25% (a subsidiary of American Metals Climax) Pilbara Iron Ltd. - 30% (a subsidiary of Colonial Sugar Refining) Dampier Mining Ltd. - 30% (a subsidiary of Broken Hill Proprietary) Seltrust Iron Ore Ltd. - 5% (a subsidiary of Selection Trust Ltd. of London) ? Mitsui C. Itoh Iron Ore Pty. Ltd. - 10% Mt. Newman Mining Co. Pty. Ltd. manages the project on behalf of the five companies which make up the joint venture.

Jan 1, 1972

By Gary Brierley, Lok Home

"The majority of tunnels for civil engineering applications are now being constructed using some form of mechanical excavation. Beginning in the 1960s with rock tunnel boring machines (TBM), the tunneling industry has introduced both earth pressure balance (EPB) and slurry pressure balance (SPB) soil machines; mixed soil and rock machines and a variety of different mechanical devices for the construction of small diameter tunnels. Over time, these machines have become more powerful and more adaptable to a wider variety of ground conditions; so much so that tunnels are now being constructed in ground conditions and in the vicinity of third-party impacts that would have been considered beyond the state of the art just 10 years ago. Figure 1 is an example of a mixed ground crossover TBM used successfully at Mexico City’s Túnel Emisor Poniente II.All of the above is highly advantageous for the tunneling industry, but it has also placed a much higher level of risk on the performance characteristics of the tunneling machines, on the contractors operating those TBMs and on the manufacturers of those machines. Most of the risks for a tunneling project are associated with creating the space inside of which the finished facility will be constructed. In order to create that space, the tunnel contractor must make many decisions about the best way to excavate the ground, the best way to control the ground at the face of excavation and the preferred method for supporting the ground around the tunnel in a manner that is safe for the workers and stable with respect to all of the overlying and adjacent existing structures. If it is proposed to use some form of TBM in order to build the tunnel, then the TBM becomes central to all three of these activities and becomes an integral part of managing the risks associated with these activities."

Jan 9, 2018

By P. I. Prescott

Ground calcium carbonate (GCC) is used in the paper, plastics, paint, rubber, caulks, and sealants industries. The favorable properties of GCC include high whiteness and brightness, low hardness, and outstanding rheology in water systems. The quality of calcitic GCC ores, which include chalk, limestone, and marble, is dependent on calcite purity and the nature and quantity of ancillary minerals. Wet and dry grinding is used in the manufacture of GCC. Ore processed by optical sorting, flotation, and/or particle size classification has higher brightness and lower abrasion. GCC markets are a function of the product's properties, purity, and cost.

Jan 1, 1995

By C. J. Hall

An investigation of multi-shaft airflow problems by the author in 1976 (1) was presented in the hope of arousing considerable written comment, but in fact-. only one contribution (2) was forthcoming. The investigation in this paper is taken several stages fur¬ther, because the matter is of major importance in many American hard rock mines with complex networks extending over thousands of meters vertically. The examples used have all been generated thermodynamical¬ly and checked by motive column (denisty) calculations. Dry air has been used to reduce the amount of time spent on the rather complex calculations, but it has been shown (3) that the principals developed apply equally well to air/vapor/water mixtures. Initially the subject is investigated using both thermodynamic and motive column analyses. The latter part of the paper concentrates on a motive column presentation. Both methods are, of course, equally valid and give identical answers to any situation when correctly applied, as is shown in the worked examples.

Jan 1, 1980

By N. Dashbold, E. Rudnik

"Waste electric and electronic equipment currently comprises the fastest-growing waste stream in the world, but at the same time it is seen as an important source of metals for the recycling industry. E-waste is usually treated pyrometallurgically, with hydrometallurgical methods used to a lesser extent. This paper reports the results of research on the selective recovery of copper from smelted low-value electronic waste. Pyrometallurgical pretreatment of the scrap allowed the removal of plastics and the increase of metal content in the material. The obtained alloy of copper, zinc, tin and silver was a multiphase solid consisting of two brass phases and inclusions rich in iron, lead and silver. Copper alloy was further anodically dissolved in ammoniacal chloride solution. It resulted in high degradation of the material and accumulation of the metals mainly in the slime. The slime was then leached in acid or ammoniacal chloride and sulfate solutions followed by selective copper electrowinning. Hydrochloric acid was the most efficient solvent for the slime, but ammoniacal solutions were more selective for copper. Copper could be leached with 96 to 100 percent and 87 percent efficiency from the slime by the chloride and sulfate solutions, respectively. Copper with 90 to 99 percent purity at current efficiency of 42 to 76 percent was obtained from the acid solutions, while copper with 98 to 99 percent purity at current efficiency of 60 to 86 percent was deposited from the ammoniacal baths. IntroductionObsolete electrical and electronic equipment makes up the fastest-growing waste stream in the world (Baldé et al., 2015), due not only to the introduction of wider ranges of new types and models of a variety of electronic products but also to the shortening of their life-spans, sometimes referred to as planned obsolescence by producers (Keeble, 2013). About 42 million tons of electronic waste, or e-waste, are estimated to have been generated globally in 2014 (Baldé et al., 2015), and it is expected that in the European Union alone the waste electrical and electronic equipment (WEEE) stream will reach more than 12 million tons by 2020 (European Commission, 2015). Accurate evaluation of e-waste generation (Wang et al., 2013) and its global transport (Breivik et al., 2014) is difficult, mainly due to a lack of high-quality data related to its market and socio-economic dynamics.Many countries introduced legislation to control e-waste flow, collection and recycling. For example, Directive 2012/19/EU on waste electrical and electronic equipment (European Parliament and the Council of the European Union, 2012) obliges all E.U. members from 2016 to maintain a minimum collection rate of 45 percent of the total weight of WEEE collected. From 2019, the minimum collection rate to be achieved annually shall be 65 percent of the average weight of electronics placed on the domestic market in the three preceding years, or alternatively 85 percent of WEEE generated in the territory of the particular member."

Jan 1, 2017

By John R. Marks

In April 1990, the Homestake Gold Mine embarked on a five year, $US 23 million underground drifting and drilling program to explore promising ore targets north of the current mine. This paper describes the ventilation and air-conditioning system that was installed for the 4m x 4m x 5.2 km (ultimately) drift, which is being driven at about 8m per day in 48OC (118.5 F) crystalline rock. Design parameters are described first. Differences in South African, Canadian and U.S. drift ventilation and civil tunneling techniques proved interesting. Details are then given on equipment selection, installation and performance. Costs are included. Special note is made of safety considerations for a long, dead-end drift.

Jan 1, 1991

By C. L. Kosmoski, B. M. Eiter, B. P. Connor

"In the recent past, the mining industry has witnessed a substantial increase in the numbers of fatalities occurring at metal and nonmetal mine sites, but it is unclear why this is occurring. One possible explanation is that workers struggle with identifying worksite hazards and accurately assessing the associated risk. The purpose of this research was to explore this possibility within the mining industry and to more fully understand stone, sand and gravel (SSG) mine workers’ thoughts, understandings and perceptions of worksite hazards and risks. Eight mine workers were interviewed and asked to identify common hazards they come across when doing their jobs and to then discuss their perceptions of the risks associated with those identified hazards. The results of this exploratory study indicate the importance of workers’ jobrelated experience as it applies to hazard identification and risk perception, particularly their knowledge of or familiarity with a task, whether or not they had personal control over that task, and the frequency with which they perform that task. IntroductionAccording to the U.S. Mine Safety and Health Administration (MSHA, 2015a), 37 mine workers were fatally injured in accidents at metal and nonmetal mine sites between October 2013 and January 2015, following a record low of 16 in 2012 and in 2011. In 2014 alone, 29 mine workers were fatally injured at a metal or nonmetal mine site, and 52 percent of these fatalities occurred at a surface stone, sand or gravel (SSG) mine. In January 2015, Joseph A. Main, Assistant Secretary of Labor for Mine Safety and Health wrote to stakeholders in the metal and nonmetal mining community and identified several areas where improvement was necessary to promote the health and safety of mine workers. One area identified was an increased focus on “daily and effective workplace exams to find and fix hazards” (MSHA, 2015b).Hazard detection is challenging in the mining industry, despite the existence of regulation. Mining is a major undertaking involving the use of complex heavy machinery, equipment and processes as well as numerous and diverse worker activities that take place in a dynamic, challenging environment (Scharf et al., 2001). In other industries that are similarly dynamic and unpredictable, such as the construction industry, a large proportion of hazards go undetected (Carter and Smith, 2006). It is critical that miners are able to both recognize worksite hazards and accurately assess the risk associated with the hazards, because their health and safety depend on their deciding whether and how to remove hazards and mitigate risks."

Nov 1, 2016

By Kadri Dagdelen, Steven Hoerger

For gold mines, orebody uncertainty is one of the leading causes of differences between planned and actual production. Geostatistical conditional simulations create multiple equally probable orebody block model realizations which are conditional to the current drilling information and demonstrate the sampled grade distributions and spatial statistics. These simulated block models are key inputs for a stochastic evaluation to show the likely range of grades and cash flows to be delivered by a mine plan. The stochastic evaluation outputs can be used to compare different mine plans in terms of expected values and risks to planned grades, production, costs, Net Present Value (NPV) and other plan metrics. For the McLaughlin gold mine, risk profiles are demonstrated to show how different mine, cut-off and stockpile strategies can reduce risk and improve expected value. The strategies considered were effective in improving expected NPV and reducing or eliminating tonnage uncertainty, but the strategies had little impact on reducing the uncertainty of NPV’s or mill grades. The stochastic evaluation process is also used to compare the risk impact of orebody uncertainty against the risk of not achieving planned mining tonnages or vertical advance rates. Risks for plans created with and without stochastic mine plan optimization are also compared.

Feb 1, 2025

By R. H. Sergent

The interest in using halogens for extracting precious metals from ores has increased due to changes In ore characteristics, environmental concerns and regulations. The rediscovery of halogen leaching capability has been the topic of these and other writers1-30. Much work has been done on the performance of bromine, chlorine and iodine5-29. Of these, bromine and chlorine look most promising. Iodine is quite expensive and sometimes forms an Insoluble film on a precious metal surface22,23. Little experimental work has been published on the relative performance of bromine versus chlorine. The Pourbaix diagrams for the halide leach system (see Fig. 1-4) Indicates a significant stability advantage for bromine In forming complex ions with gold. This should result In greater extraction of gold under similar leach conditions and Is evaluated In this work. The regeneration of halogen from a spent leech solution is a critical requirement for an environmentally acceptable halogen leach process. Bromide can be oxidized In-situ to bromine ~ adding chlorine or ozone2,31. Bromide like chloride can be oxidized In an electrochemical cell to produce halogen on demand 13,15,17. Bromine clearly offers a number of possible regeneration pathways. This work strives to compare the relative ability of chlorine and bromine to extract gold from partially and fully oxidized ores. A commercially pressure oxidized sample was evaluated under a number of experimental conditions. The autoclave feed ore from the same mill was also evaluated after complete oxidation In a laboratory autoclave.

Jan 1, 1993

By Wolfgang Pietsch

DR iron') is a generic term for metallized product that results from the direct or solid state reduction of iron ore. In direct reduction, iron oxides are reduced to metallic iron in the solid state without an intermediate melting step. MIDREX ® Iron is the DR iron material produced in the MIDREX ® Direct Reduction Process. Except for some thermal and mechanical degradation, the external physical form of as-reduced DR iron is the same as the feed material. Chemically, oxygen associated with iron is removed leaving a very porous structure. Figure 1 is the scanning electron micrograph (SEM) of the internal surface of a MIDREX Iron pellet obtained from a Swedish oxide pellet during reduction at 760 °C. Figure 2 is the SEM of a polished and etched cross-section through the same pellet showing the amount of intraparticle porosity. As a result of this high porosity, apparent density of DR iron is relatively low, typically a¬round 2 g/cm3, and specific surface is extremely high, typically around 1.0 m2/g or more. Both density and specific surface depend on the raw materi¬al and the operating conditions of the direct reduction plant. Normally, more than 97% of the available iron is reduced into metallic iron with the rest mainly in the form of wustite (FeO). During direct reduction, the gangue in the iron remains essentially unchanged. Removal of oxygen and the corre¬sponding reduction in weight result in a slightly higher percentage gangue in the product than in the raw material.

Jan 1, 1976

By Y. C. Kim

This paper describes the implementation aspect of a blast hole kriging system which has been developed for the purpose of daily ore-waste control in an open pit mine. The primary goal of blast hole kriging is to improve the ore-waste delineation procedure. A complete computer program package called Blast Hole Kriging (BHK) System was developed for IBM/PC AT or XT computer, using Fortran language and supplemented by a few Assembly language routines for bit-map manipulation. The emphasis of this paper is on the implementation aspect of the developed system. For this reason, the requirements for practical implementation and the system design considerations are discussed in the paper, as well as the main features of the University of Arizona's BHK System.

Jan 1, 1990

By J. Y. Hwang

Sands are utilized to make molds for metal castings in the foundry industry. Approximately a half ton of sand is disposed of for each ton of metal cast in this country. In Michigan, annual sand disposal amounts to about one million tons. A process has been developed in this study to reclaim sands from a steel foundry. Physical separations are utilized in conjunction with other operations (such as the removal of binder, metal, spruce, washes, etc.) to yield silica and chromite sands with desirable molding properties. Several different separation methods, including electrostatic, magnetic, and various gravitational approaches have been examined. Experimental results are presented. The applicabilities of these separation methods are discussed.

Jan 1, 1992