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By Hugh E. Cronin, Lok Home

THE PENETRATION RATE BASELINE DILEMMA The penetration rate is the instantaneous advance rate of a TBM in a rock tunnel. Normally expressed in feet per hour. The production rate is the penetration rate multiplied by the number of hours worked and then factored by the actual utilization of the TBM. In a given rock formation, the actual production rate is a result of many factors some of which are within the control of the contractor and some of which are based on the route selected. Factors that are within the contractors control are cutter profile, frequency of cutter changes, thrust, rotation speed, cutter spacing and the efficiency of the operation. Factors that are site (route) specific are compressive strength, fracture orientation, fracture frequency, micro- fracturing, quartz content, Moh’s hardness, Cerchar Abrasivity Brazilian Tensile Strength and Youngs Modulus of the rock. In addition the following route speci?c conditions are beyond the contractors control; rockjointing, rock stress fault zones, water in?ow and rock decomposition; all of which effect production rate. Any one of the above defined rock properties, equipment specifications and actual operating usage will change the penetration rate. Furthermore, since the rock formation changes both in content and orientation as the tunnel advances, the penetration rate is constantly varying. The current industry practice in bidding tunnels is for each contractor to individually evaluate the rock hardness and other properties and from this information develop a penetration rate. All other factors being equal, the contractor using the most optimistic penetration rate will be the low bidder and be awarded the project. As this view is by definition optimistic, invariably the rock will be harder than the low bid assessment and the contractor will request additional compensation for the changed condition. The contractor will attempt to justify his optimistic assessment as reasonable by using expert supporting analysis. The above described example which is quite common at present in the industry tends to make the most optimistic contractor (at time of bidding) the contractor selected for the project whereas it is in the owners interest to contract with the most efficient contractor not the most optimistic. This situation is similar to the Geotechnical analysis that was prevalent in the industry over twenty years ago. Many projects have experienced a significant reduction of penetration rate from that which was originally estimated. In these cases the contractor often makes a claim for extra compensation based on the difference between the actual rock encountered

Jan 1, 2003

By Gordon V. lewis

The Penjom gold mine treats highly preg-robbing carbonaceous ore by using relatively inexpensive gravity and hydrometallurgical methods. The mine is a joint venture between Avocet Gold Limited, a subsidiary of Avocet Mining PLC, a U.K listed mining company with interests in gold and tungsten, and the Pahang State Development Corporation (PKNP) who receive a 2% royalty. The operating team at Penjom embarked on a programme of innovation during 1998 following a realisation that almost all of the primary ore in the gold deposit was highly carbonaceous in nature. Earlier attempts at desliming and leaching the deslimed product through a normal CIL circuit had failed, and through shear necessity, the team turned to new technologies which were considered most suited to the ore characteristics indicated from pre­feasibility testwork. Between April and September, 1998, the mine introduced three key processes, which combined represent the elements of "The Penjom Process". The gravity circuit was boosted to maximise the capture of leachable sulphide and free gold from the relatively carbon free cyclone underflow stream, kerosene and diesel blanking was introduced to treat the cyclone overflow and RIL (resin-in­leach) technology utilised to replace the existing CIL (carbon-in-leach) circuit. Further experimentation with selective resin in partnership with Mintek of South Africa yielded a significant improvement to the process during 1999. Minix­Dowex resin was introduced mid year to replace a non-gold selective resin, which had been used in a flotation/batch leaching circuit for about nine months. Lower carbon levels in the feed at that stage led to the abandonment of flotation and the introduction of continuous RIL, which has been adopted as the major chemical process at the Penjom gold mine since September, 1999. Given the proven performance of the circuit to date, this process may be considered as a low cost option for the treatment of highly carbonaceous ores, particularly those which are not refractory and contain a reasonable percentage of free gold.

Jan 1, 2000

By W. T. Walter

High-G centrifuges from five preparation plants were sampled to determine and quantify the various operating factors affecting performance. The operating factors that were considered include feed rate and percent solids, size of feed material, screen-basket type, hardness of coal and age of the flights. The performance parameters that were measured include product surface moisture, recovery and degradation of the coal. Regression equations with good significance levels were developed.

Jan 1, 1982

By Harald F. Solberg

A preliminary study of the performance of a 4-inch Krebs cyclone at near rope conditions and different feed slurry temperatures was completed. Results suggest that temperature influences the x50c size which, in turn, did not depend upon spigot diameter. The bypass correction to a reduced efficiency equation incorporating the concept of a critical size xo was a function of fractional water recovery to underflow and may depend on feed size and feed percent solids. Further experimentation is required to develop an accurate model at near rope conditions.

Jan 1, 1981

This paper presents the results of an investigation of the stability of the mass flow rates and average pellet size in the different streams of an industrial-scale balling circuit. The variables in this study include water content, drum speed and fresh feed rate. It was found that both the mass flow rates and pellet diameter are greatly disturbed when a change, positive or negative, in any of the variables takes place. For most of these disturbances to be damped don, a period of one hour or so is required. When a disturbance in the feed rate was made, the transient period extended to more than one and half hours (the duration of the experiment). It was observed that there is an interaction between the drum speed and moisture needed for producing an acceptable green ball product. The moisture content of the product pellets was found to be a function of the pellet size, with the larger pellets retaining a higher moisture content.

Jan 1, 1980

By C. P. Lazzara, R. W. Pro, A. C. Smith

The U.S. Bureau of Mines conducted a study to evaluate the effectiveness of automatic water sprinkler systems in the extinguishment of incipient conveyor belt fires under ventilated conditions. Large-scale experiments were conducted using a double strand conveyor belt configuration. Standard response, pendent-type sprinklers, with activation temperatures of 100°C, were installed above and between the two strands of belting, in accordance with Federal standards for sprinkler system installations in belt drive areas. Experiments at airflows of 1.1 and 4.6 m/s showed that the sprinklers activated later, the peak heat release rate was larger, and more betting was consumed at the higher airflow. In experiments with 74°C, fast response, directional sprinklers, the sprinklers activated at the same heat release rate for both high and low airflows, but the peak heat release rate and amount of bett consumed was slightly higher at the lower airflow. Experiments were also conducted with 100 °C, standard pendent sprinklers installed above the top belt, in accordance with the National Fire Protection Association (NFPA) Standard 123 for sprinkler system installations in conveyor belt drive areas in underground coal mines. In these experiments, the heat release rate and amount of betting consumed was larger at the higher airflow.

Jan 1, 1995

By T. R. Kostecki, A. J. S. Spearing, A. Hyett, M. Gadde

Ground control research for underground coal mining has progressed significantly over the past several decades. With this progression, and the ability to analyze and model underground conditions, underground working conditions have significantly improved. In order to progress further, the behavior of roof support must be known and be adequately modeled, such that models can be used for support design under different geological and mining conditions. This paper discusses the results from a research project funded by the U.S. National Institute for Occupational Safety and Health (NIOSH) and undertaken by Southern Illinois University Carbondale and Peabody Energy. The research involved installation of active and passive instrumented bolts in mines, recording relevant in situ data and then attempting to model the behavior of the bolts as mining progressed. Such calibrated models could aid in design of roof supports under different geological and mining layouts and thus, hopefully, further improve rock related safety.

Jan 1, 2012

By Raymond E. Zimmerman

The cleaning of coal by the use of jigs is one of the oldest methods of separating coal from its impurities. Although in many situations jigs have been replaced by other methods, by far the largest percentage of coal today is still being cleaned by some form of jigs. Some piston- or plunger-type jigs are still in use throughout the world; however, the greater number are air pulsated, generally called the Baum jig, named after the original inventor, Fritz Baum of Germany. This standard jig, with slight modifications, has been in use for over 75 years. Up until recently, however, it has had certain limitations in obtaining the high performance and efficiencies required in modern coal preparation practice. TO improve its performance, some radical modifications have been made in its design and operation SO that there is now a Baum-type jig giving much higher performance in terms of capacity, efficiency and sharpness of separation- This new jig is called the Batac, and the purpose of this paper is to describe its characteristics and present data giving its performance in treating coarse and fine sizes of coal.

Jan 1, 1974

By Jack M. Campbell

The regulatory process by which governmental authorities acknowledge and, in turn, permit the location, construction, and operation of large scale energy-related facilities has become extremely detailed in recent years. One example of the detail that is entailed in the regulatory process is the number of permits that must be acquired by operators prior to the construction and operation of energy-related facilities. It has been estimated, for example, that 75 permits are required prior to the opening of a new coal mine in Pennsylvania while 50 are required in Kentucky. From the perspective of facility owners and operators the regulatory process often appears overly complex and may be perceived as a constraint to the corporate decision making process. From the perspective of those responsible for administering regulations, the process is perceived as a mans by which public desires - pursuant to social objectives such as environmental protection and occupational safety - can be achieved. As a result of conflicting organizational interests, the clash between energy facility owners and operators and their regulators appears to be inevitable. Furthermore, the resolution of this conflict lies in the tradeoff between objectives and the costs of regulation. The balance of objectives and costs is a subject of the political process and not a topic of consideration in this paper. This paper is concerned with the actual administration of regulations, that is, the implementation of that which arises from the interplay of organizational interests. The paper assumes that environmental control laws will not likely be repealed, that regulations to implement the intent of these laws are here to stay and thus the paper seeks to assess how regulations are administered at various levels of government pursuant to objectives. The paper hypothesizes that the administration of objectives (or policy) has an impact on decision making which affects energy facility decision; making while recognizing the fact that regulatory policy cannot be totally divorced from administration, this paper proceeds

Jan 1, 1977

By C. Okrusch, C. Roos, M. Akers, S. Rosenthal

Modern mining consistently faces controversy. Public sentiment impacts the permitting and development of mines, so a quality public relations (PR) program for mining companies may improve society’s impression of the mining industry. Developing mines face more permitting challenges than operating mines, which stems from a lack of societal trust given the history of mining and its impact on the environment. Two case studies were selected based on the type of public controversy they face to demonstrate how pervasive permitting issues are in industry. Both Pebble Mine, owned by Northern Dynasty Minerals (NDM), and Black Butte, owned by Sandfire Resources America Inc (SRA), experienced difficulties with their water permitting due to potential risks their mine developments posed to local fish populations. Pebble has, to date, failed in all of their attempts to become permitted due to concern for the water and the fish. Black Butte dealt with the same problems, on a smaller scale, but was able to become permitted. These two mines will be discussed in detail including local history, mine setting, mining history in America, prevalent culture groups, technology development, and intercultural communication competence (ICC). The mining industry needs to evaluate its ICC skills since ICC directly determines the effectiveness of PR. Based on Barna’s Stumbling Blocks for intercultural communication, methods for improving the mining industry’s PR will be suggested in the hope of easing the permitting process for future mines by developing ICC.

Mar 2, 2022

By H. P. van Ormer

The objective of this paper and the developed personal computer program is not to identify or try to identify the actual total drilling cost in any Rotary Drilled Blast Bole Program. The ideas put forth here and in the computer program developed are a very accurate way to measure what is often very hard to identify and interpret -The actual direct operating cost of various drilling package combinations including comparing with available blast hole sizes and patterns

Jan 1, 1988

By L. P. Meade

The particular impact of imported industrial minerals varies within the Industry and is dependent upon many diverse factors. In a similar way, the impact on individuals has been varied and the degree of impact will depend partially on the individual's ability to handle change. Just as many corporations are adjusting their marketing strategy and production methods to compensate for imported mineral products; individual managers, mining engineers and geologists are making adjustments to their own personal job marketing techniques and on-the-job operating procedures. Modifying the degree of impact for both industry and individuals depends upon the ability to adapt.

Jan 1, 1988

By Bekta? Uz

Istanbul is the bigest metropolitan city of Turkey with more than 15 millions of population and construction activities are steadly increasing with respect to that increase in population. In this papaer petrographical, physico-mechanical properties of natural aggregate mines from west, (Tekirdag) to East, Izmit (Gebze) 'will be summarized in connection with the concrete production. However the locations suitable for aggregate production in these area as; Paleozoic aged sandstones (Ayazaga, Cendere, Mahmutbey areas), Permb-Carboniferous aged limestones (Cebeciköy area), Triassic limes tones (Ömerli-Gebze areas) and Eosen limestones (Çatalca area), Plio-Quaternary aged volcanic basalts (Tekirdag, Çorlu, Beykoz areas). Plio-quaternary aged, fine grained aggregates within sandy formations are mined in Silivri-Sinekli area, Catalca-Ormanali area, Agacli-Akpinar (Kemerburgaz area) and Sile-Karakiraz-Sahilköy areas. Sandstones mineralogically contain mainly of Quartz+Feldspar and less amount of Mica (biotite+muscovite) rich with slica content and sedimentary origined. Especially limestones are cryptocrystaline textured, unique mineral composed of calcite and secondary have Dolomite ± (Quartz+Albite). Basalts are microlitic textured and contain Olivine+Pyroxene+Plagioclase. Chemically basalts rich with Fe and Mg and also volcanic origined. Sands are fine grained natural aggregates mainly contain semiangled, rounded minerals and rock fragments. Mineralogically have Quartz + Feldspar ± pyroxene+ ambhibole ±garnet and less amount of epidote ± magnetite ± hematite. Different rocks, used in aggregates such as limestones, sandstones-sands and basalts, supply varied concrete strength because of their mineralogical composition and characteristics of textures. Moreover, Basalts (Karatepe area) are good example for the higgest concrete strength (1017-1895 sc; kg/cm2) in our study area because of their clambed mineralogical apperance such as intersertal texture. As the result of extensive field and comparative laboratuary studies, the effect of petrographic, physical, mechanical properties of the aggregates on concrete srtength is extensivelly discussed in this paper.

Jan 1, 2005

By Robert J. Ramsey, N. Finkelstein, Foster J. Witthauer

First mining operations in the Tyrone District, located just north of the Burro Mountains in Grant County, New Mexico, commenced in the 1870's. A major operation was undertaken by Phelps Dodge Corporation in the early 1900's when a 2,000 ton per day underground mine was developed and a gravity concentrator was built east of the mine and across the Continental Divide. It was during this time that the picturesque Tyrone townsite was built and occupied. In 1921, however, the underground operation was closed because of high operating costs and low demand for copper. The area was drilled extensively during the 1950's and in October 1966 Phelps Dodge announced the pending development of the new Tyrone with a large open-pit mine, a modern concentrator, suitable support facilities, and a new townsite to be located between the mine and Silver City. Stripping for the pit and construction of shop and milling facilities began in 1967. By the spring of 1969, ore was being stockpiled near the primary crusher. Operation of the concentrator on a 3-shift per day basis commenced on July 17, 1969. The concentrator as initially built had one primary, two secondary, and five tertiary cone crushers, two grinding sections of six ball mills each, two flotation sections, four filters, and four tailing thickeners. 'he capacity was about 30,000 tons per day. In 1971 and 1972, the capacity was increased to 48,000 tons per day by the addition of one secondary and two tertiary crushers, one section of eight ball mills, one flotation section, two filters, and four more tailing thickeners. Centralized automatic control was built into the original and expanded facilities to the greatest extent possible, considering the state of the art at that time. Installation of additional control

Jan 1, 1976

By William F. Stowasser

The organization and operations of the information gathering system, and examples of the products prepared for the commodity phosphate rock by the Division of Nonmetallic Minerals, U.S. Bureau of Mines, are used to describe the Bureau's commodity program. Selected examples from publications about phosphate rock are used to illustrate the program. The Commodity Divisions reporting to the Office of the Assistant Director-¬Metals, Minerals and Materials, have the responsibility in the Bureau of Mines to maintain commodity records, understand the present supply and demand status of the commodity, and forecast future supply, demand, and problems. Within the Divisions, commodity specialists have the broad charter of acquiring as much information about a commodity as is necessary to characterize its history, current status, and future. This information and understanding are the base for the development of mineral policies. To accomplish these objectives, the commodity specialists acquire data and information about each commodity and produce a number of standard publications each year. In addition, as circumstances dictate, each specialist will prepare or participate in the preparation of special documents for specific purposes or problems associated with his commodity. In the preparation of reports and publi¬cations, he may communicate with industrial organizations and other Government agencies.

Jan 1, 1975

By John W. Antalovich

Normally I would like to begin a talk on photogrammetry by defining the word. However modern technology has changed the science so radically that it bears little resemblance to its original definition. Photogrammetry as defined is a science of taking accurate measurements from photography. Today's photogrammetrist, in addition to working with photography, finds himself working with magnetometers, infrared scanners, radiometers, holo¬graphy, lasers, side-looking radar, digital interfaces, computers and countless other modern space age concepts. The modern photogrammetrist is a pilot, photographer, lab technician, mathematician, geologist, programmer, engineer, physicist, and cartographer. His modern instrumentation and many spheres of activity all have a role in the environmental sciences. For example, the magne¬tometer which measures the earth's magnetic fields is used to locate the earth's ore deposits. The infrared scanner captures the heat emitted from the earth to detect ground waters and thermal pollutions. To elaborate on each of his many endeavors would take volumes rather than this short paper. I have elected therefore to discuss what I feel is his most important role in the environmental sciences - that of cartographer.

Jan 1, 1970

By N. M. Levine

This work defines and systematizes the physical factors of the problem of leaching and demonstrates for the first time the utility of macropore volume, micropore volume, specific surface, pore size distribution and permeability as parameters of leaching based on a study of the recovery of uranium from the Top Black member of Chattanooga Shale.

Jan 1, 1962

By John Frostiak, Igor Gonzales, Kenneth G. Thomas, Ken Manning

The Pierina deposit was acquired in August 1996 when Barrick Gold Corporation purchased Arequipa Resources, a junior mining company with extensive land positions in Peru. At the time of acquisition, Arequipa ha.d developed two exploration tunnels and drilled 9 exploration holes on the property. Metallurgical tests, conducted on samples taken from the tunnels and the exploration holes indicated that the ore was amenable to heap leaching. Barrick's exploration team recognised from the outset, the potential of the mineralisation and convinced Barrick's senior management that this was indeed a world class deposit that should be pursued. On November 25, 1998, the fi was poured at Pierina, 27 months from the time of acquisition. During that period BmTick completed its exploration programme, prepared a development plan including capital and operating costs, production profiles and cash flow forecasts, and a schedule to develop a mine and construct a leach pad and gold recovery plant, including all supporting infrastructure. All permits and environmental approvals were obtained and all necessary land was acquired. The project was completed on schedule and under budget. This was the first greenfield mine development for Barrick outside of North America. This paper details, mainly, the research and development, engineering, construction and commissioning of the metallurgical process facilities.

Jan 1, 2000

By Larry Whittle

Gold milling activities generate waste streams containing dissolved metals and cyanide, among other contaminants, that require some form of treatment prior to discharging to the environment. To date, this treatment has involved the destruction of cyanide through natural degradation, chemical oxidation, or a combination of both followed by the precipitation of metal hydroxides. Although these processes have been proven to be capable of achieving. regulatory levels for metals and cyanide, they often generate significant levels of cyanate and, at times, ammonia, that may be toxic to rainbow trout and thus undesirable for regulatory compliance. Tallon Metal Technologies Inc. (Tallon) has developed Vitrokele™, a chelating resin that has the ability to capture metals (including gold), both total and weak acid dissociable cyanide, as well as thiocyanate from both slurries and solutions. The loaded resin is eluted and returned to the recovery circuit while metals and cyanide are recovered from the eluent stream. This process was demonstrated at pilot scale at B.P. Resources' Hope Brook Gold Mine in Newfoundland, and more recently at Canamax's Bell Creek Mine near Timmins, Ontario. The results from these pilot programs showed metal and cyanide recoveries of 99% or more with the concentration of cyanide and metals in the effluent reduced to levels with minimal or no toxicity to rainbow trout. Furthermore, neither cyanate nor ammonia were generated from the process. The loaded resin was effectively stripped and re-introduced to the recovery circuit; cyanide was captured in the eluent stream and made available for recycling to the mill leaching circuit; and metals were captured for re-use, sale or disposal. This paper summarizes the results obtained from the pilot tests at the Bell Creek and Hope Brook Gold mine sites.

Jan 1, 1992

By J. W. Motter

Currently, virtually all new electric power generation systems under construction are designed with natural gas as the primary fuel. Factors driving these construction decisions involve sustained low prices for natural gas, environ-mental (and consequent regulatory) risks associated with the use of coal for power generation, and relatively high costs of construction for conventional coal-fired power plants. Despite the unarguable abundance of coal in the US. and worldwide, a fundamental question arises: What will be the role of coal in electric power generation in the 21st century? Congress, recognizing the vital and strategic importance of preserving the coal option for electric power generation, authorized the Clean Coal Technology Program. This pro-gram, with original funding in excess of $2,500 million, is intended to promote the demonstration and commercialization of a new generation of clean, efficient coal-based energy technologies through collaboration and partnering with private industry. The two technologies being demonstrated under this program which are the key to the continued use of this nation's huge coal reserves are coal gasification and the pressurized fluid bed. Either or both of these technologies, coupled with a combined cycle will pro-vide the continuing future coal option, while responding to increasingly more restrictive environmental standards. Recent Congressional budget-cutting efforts, however, could threaten the effectiveness of that model program, and ultimately other subsequent government-industry collaboration.

Jan 1, 1996