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By Kraig W. Grubaugh

Rapid growth in the rate of surface mining for coal has caused many states to increase the rigor and complexity of their surface mining codes. The promulgation of Federal surface mining standards may cause those states containing Federal land to amend their codes also. Presented is an up-to-date review of these codes with tabular summaries that divide the codes into operative functions. These summaries will be of use to new operators, multiple-state operators, and state officials. Suggestions are made for industrial efforts to present workable and acceptable amendments to these codes.

Jan 1, 1977

By S. Hardcastle

Kidd Creek mine has recently completed upgrades of its primary ventilation systems enabling it to maintain a delivery of 1200 m3/s to continue mining ore zones extending to over 3000 m below surface. Following these upgrades the mine initiated a multi-stage review of their ventilation usage. The focus of these reviews, ranged from a brainstorming session of invited experts, through an evaluation of production plans to a detailed analysis of production data to determine if the ventilation system could be run more efficiently, thereby reducing the mine?s power consumption and associated operating costs. The initial review identified 1500 kW of installed fan power that could be eliminated from the primary ventilation system. The benefits of the subsequent analyses, so far, are not as measurable. The second and third analyses, respectively using long range production plan data and historic production data to determine ventilation requirements based upon diesel equipment, did not agree. Both were shown to have limitations, the future based analysis underestimating, and the historical analysis overestimating the requirements. Regardless of the failings of each method, important outcomes were achieved from the detailed analyses, namely, the ability for a mine to meet a forward analysis prediction of airflow depends on its ability to adjust the ventilation to meet the dynamic nature of the mining process. Also, to minimize total ventilation requirements, a mine must regularly redistribute its airflow; this not only reduces the total volume requirement but also increases the variability of the delivered flows which can provide further operational savings. Since the detailed analyses, the Kidd Creek mine has implemented a more frequent ventilation review and redistribution procedure; consequently, it now operates with an average delivery of 930 m3/s, which is 23% lower than in 2005 at the start of the review process.

Jan 1, 2009

By K. L. Woodruff

Shredding is the usual first step in processing municipal solid waste (MSW) for resource recovery. This unit process requires high capital cost and, usually, considerable maintenance cost. In addition, some shredders at times will render certain components of the MSW in a form difficult to recover. This is particularly true in the way metal cans are distorted and the way glass is pulverized. A trommel screen was proposed (1) to pre-process packer truck refuse prior to shredding. Part of the logic for this step is that the portion of raw refuse already within the specified shredder output particle size range would bypass the primary shredder and proceed directly to further processing, such as to an air classifier or secondary shredder. This would reduce the throughput of the primary shredder and allow certain recoverable materials, such as glass, to remain in larger piece sizes, important for recovery. In this way, operating costs for the shredder would be reduced and the recoverability of materials, and hence the revenue, increased.

Jan 1, 1975

By David G. Van Hersett

The single most unique design feature of the Centralia Coal Mine is the public information program. Just what the heck does public information have to do with the development of a coal mine? The utilities of today have had to build larger and larger plants to keep down the costs of power to the consumer. The large plants require huge amounts of capital, take up large areas of real estate, consume unprecedented amounts of coal, and generate large quantities of waste products which have to be reckoned with. Coal mines supplying these plants have also increased in size and production to meet the power plants' unending appetite for coal. This means the disturbance of great areas of land and significant alterations to the landscape. Today's public is greatly concerned about the environment in which he is living. The great size of a power plant with its large stacks, coal piles, and the coal mine with its large earth movers, disturbed acreages and the resulting waste products of both operations appears to present a threat to his environment. Because of this,' many power plants and coal mines are having public acceptance problems. This has resulted in the passage of stringent legislation and in some cases brought upon construction delays for major power plants.

Jan 1, 1970

By Myles E. Altimus

One responsibility of a manager is to improve his human organization. Some executives believe a manager should be measured and compensated accordingly on the basis of his ability to improve the quality of his human organization. Officials in the coal mining industry have had a tough road to travel in this regard due to fluctuating coal production demands, contractual obligations, and improved mining equipment and methods. The time may have finally arrived when we are able to recruit, select, and develop men from the labor market to fill vacancies, This is particularly true of our maintenance organizations. Because of the importance of this responsible function and the types of skills required, we must develop an extensive improvement pro- gram. Anyone in the industry who fails to undertake a manpower audit and who accepts a philosophy which will not permit collective planning, organizing and con- trolling the improvement of the human element throughout his maintenance organization may certainly cause deterioration within his company.

Jan 1, 1966

By A. R. MacPherson

The procedure to arrive at an energy efficient autogenous grinding plant is carried out in the following steps: First Step - Determine power requirements to grind a particular ore. This work carried out on small samples ground in a 450 mm diameter Aerofall Hill and the results are checked against a standard Bond Index test. Second Step - A bulk sample from the ore zone is ground in a 1.8 m diameter pilot mill. This work is carried on until the power objectives as indicated from the first step have been realized. Third Step - Correlate the pilot mill data, with the data from the numerous samples ground in the small 450 mm mill and arrive at design criteria for the commercial plant. Ensure commercial mill design will be suitable to obtain similar results as those obtained in the pilot mill.

Jan 1, 1981

By Daniel Threlfall

The disposal of hazardous chemical wastes will be one of the major environmental issues of the 1980's. Approximately 50 million tons of hazardous wastes are produced yearly. One of the major aspects of the problem is the siting, design and construction of environmentally acceptable disposal facilities to accommodate this huge volume of material. Surface mines have been considered attractive for development as disposal sires for several reasons: 1. Surface mines represent an open pit that can conveniently serve as a repository for wastes. This could represent a significant economic savings when compared with sites on undisturbed lands chat might require extensive excavation or embankment construction.

Jan 1, 1981

By Garry G. Lowder

The regional geologic setting is essentially a volcanic island arc built upon an oceanic basement, consisting of basalt and minor pelagic sediments (the Tinombo Formation of Eocene - lower Miocene age. Trail et. al. 1974). -- An east-west chain of intermediate and acid calc-alkaline volcanoes (the Bilungala Volcanics) was built on the oceanic basement during the Miocene. The Bilungala Volcanics are flanked to the north largely by contemporaneous andesites and volcanoclastic sediments of the Dolokapa Formation. During middle to upper Miocene time the Bilungala Volcanics were invaded by large masses of predominantly dioritic intrusive rock and it is within one of these dioritic intrusive complexes, the Bone Diorite, that the cluster of porphyry copper systems occurs. Renewed volcanic activity in the Plio-Pleistocene produced acid pyroclastic rocks (the Pinogu Volcanicsi whose distribution is controlled by present-day topography. Structural trends, largely interpreted from SLR imagery, are pre- dominantly NW or NIWJ. The right-lateral Gorontalo Fault, which trends hW through the town of Gorontalo (Katili, 19691 is the most prominent structural feature. Many of the major structures in the Tapadaa district have similar orientations and may be sympathetically related to the Gorontalo Fault.

Jan 1, 1976

By Margaret Armstrong

The increasing cost of developing new mines and the need to mine more marginal deposits have led mining companies to use more sophisticated estimation methods such as kriging. But until recently, coal mining companies have shown little or no interest in these techniques. However, the stringent quality controls which are now placed on coal have led to a surge in interest in improved estimation methods. This can be seen from the -, number of research projects by private companies and governmental agencies on the application of geostatistics to coal reserve estimation. At present, most of these programs are centered on the problem of estimating the tonnage and the average grade (i.e. ash percent, sulphur content, calorific value, etc.) of the coal in-situ. See, for example, Sabourin (1975), Woods (1976, 1979), Pauncz and Nixon (1979) and Armstrong (1980). These studies show that the established techniques of linear geostatistics can be applied successfully to coal deposits. The study by Woods is particularly interesting because he had access to the actual production figures as well as the initial sample data from the no 2 seam in the Greenside Colliery owned by the Anglo-American Corporation. He showed that the estimates obtained by kriging were consistently closer to the actual production figures than those given by three other estimation methods. This confirms the superiority of kriging as a method of estimating block values for coal. Another advantage of geostatistics is that it can be used to determine the optimal spacing between drill holes. An example of this is given by Armstrong for the coking coal deposit in the Bowen Basin, Australia.

Jan 1, 1981

By Dennis Asmussen

The peatlands of the U.S. and Canadian parts of the Upper Great Lakes region have a long history of modest utilization in agriculture, forestry, horticulture, and as natural undisturbed areas. Only recently have they been assessed as potential sources of non-renewable or renewable energy. This new interest in peatlands, should current proposals be realized, might mean the commitment of millions of acres to energy production purposes. The magnitude alone of this potential utilization of peatland signals the possibility of substantial environmental disturbance, local resource shortages, resource use conflicts, and social and economic change. Peat- land resource managers in the region are just beginning to weigh the advantages and disadvantages of large-scale peatland utilization. The Minnesota Department of Natural Resources has made a considerable effort to study peat resource management issues and will shortly make recommendations to the state legislature regarding utilization alternatives. What follows is a general discussion of peatland utilization and management trends in the region with a focus on Minnesota and its peatland management efforts.

Jan 1, 1980

By Burton H. Boyum

The paper generally reviews the iron ore occurrences and regional geology of Western Australia, but features in particular the mesa deposits of PJasic Materials - Cliffs International. Initial production is planned from a aeries of mesa deposits of Eocene-Oligocene age. The ore is oölitic to pisolitic goethite and hematite. Source of the iron in the mesa deposits is thought to be from the Precambrian iron-formations. The geology and occurrences of the mesa iron ore deposits are summarized and illustrated.

Jan 1, 1964

By F. C. Nicolli, J. P. Barbosa, P. S. M. Soares, A. V. Estevez

INTRODUCTION Spent household dry cell batteries are frequently disposed of with metropolitan wastestream (MSW) in landfills where they can leak due to handling or aging. Frequent rain and sun cycles, especially in tropical environments, coupled to the action of leachate, dissolve their metal constituents which will eventually reach rivers, lakes and underground water. It is well known that some of these metals are fundamental to sustain life and that is why living organisms concentrate them through their metabolism, but it has been also recognized that beyond specific limits they can definitely be deleterious to the environment. In other words, high concentration of heavy metals are proven to cause chronic or acute diseases and toxic reactions, by acting on mammals' kidneys, liver and nervous system. In addition, some metals frequently used in household batteries, as mercury and cadmium, are said to be carcinogenic (Landis et al. 1995, Silva et al. 1988). Occasionally, plants to treat MSW are coupled to compost production. Household batteries present in MSW can be dragged into these plants, contaminating their products and eventually reaching vegetables making them not proper to consume by people and animals. Alternatively, batteries are also conveyed to incinerators and burned, throwing into the atmosphere volatile species. These can either act as contaminants as toxic vapor species or be delivered by winds and scavenged by rains contaminating soils and water far away from their source. In conclusion, despite the treatment applied to MSW, one can say that battery residues are potentially environmentally hazardous. The careful assessment of the environmental impact caused by residues of household batteries it is not an easy task and it can be referred as a multivariable problem. First, many different household batteries are produced by industry and the potential environmental hazard associated to their disposal depends primarily on the type of battery and manufacturer's technology. These characteristics will dictate how resistant the battery case is to handling and the

Jan 1, 1998

By Jim Salley, Mohammad Saleem, Indra Banerjee, Kevin Sapp

"On underground construction projects, effective Quality Management is essential for ensuring facility durability, life cycle performance and low maintainability. Furthermore, follow on contracts also rely on an effective quality management system for interface congruency. An effective Quality Management System (QMS) is also essential in mitigating risks and meeting schedule and budget performance objectives. For the past 15 years Central Puget Sound Regional Transit Authority’s Link Light Rail extension has successfully completed over 10 miles of twin bore tunneling and associated underground features including cross passages, deep sump structures and shafts. After the completion of each segment, lessons learned have successfully been implemented to improve the quality of delivered projects. This paper presents the Sound Transit QMS with regard to a number of project elements of tunnel construction projects, with specific focus on quality performance of slurry wall construction, TBM tunnel excavation assessment, segment production and segmental lining installation, and other associated construction features. A collaborated total QMS will be presented in this paper that will serve as a guide for successful implementation of Quality Assurance and Quality Control processes. INTRODUCTION Implementation of a robust Quality Management System reduces defects, errors and omissions, identifies and addresses nonconformance in a timely manner and increases stakeholder confidence in the project. In fact and effective QMS helps ensure that optimal project outcomes are realized both in terms of project delivery and life cycle performance. The two key components of QMS are quality control and quality assurance. Quality Control (QC) is the procedure implemented to achieve a certain level of quality and ensure that products, processes and services meet specific requirements. Quality Assurance (QA) activities are carried out to evaluate the effectiveness of the quality control measures and ensure that the QC process is working. A team obligation that recognizes that quality is built into every aspect of a project is the basic concept of a successful QMS."

Jan 1, 2016

23.1-SOURCE, POWER-SYSTEM ELEMENTS A. J. T HUM Basic considerations in providing power for mine production and collateral operations are: 1. Mining operations of any size normally use electric motors for driving all equipment except mobile service units. 2. The electricity for power may be purchased or self-generated, depending on the location, size and specific operating circumstances of the individual property. 3. The major elements of the power system will be the source, either an incoming transmission line from a utility in the case of purchased power or the power plant if self-generated. Energy for the power plant may be water, hydrocarbon fuels, waste heat or nuclear, which will govern the type of prime mover selected. 4. The electricity normally is generated in the form of alternating current and must be distributed to the points of usage. This usually requires a primary substation for transformation to suitable voltages and secondary substations at points of usage throughout the operations, The power is delivered from the primary to the secondary substations over transmission lines or cables, depending on distances, voltages and local conditions. 5. At the points of use, there will be starting and protective devices for each motor. In some instances, direct current will be needed and rectifiers of various types can be used to provide it. 6. The entire electrical system requires suitable switching and protective devices to prevent damage to the equipment in case of power failues or faults; also, in most cases, sufficient metering to establish the demand and amount of electrical energy consumed. 23.2-PURCHASED POWER A. J. THULI 1. Where public-utility or government-generated power is available, it usually is advantageous for the mine owner to purchase rather than generate. Purchased power generally will be cheaper and more reliable than operating a small generating plant except in some cases where waste heat is available as the source of energy and can be used to supply all or a portion of the power requirements. 2. If it is decided to purchase power, the owner usually must participate in the cost of constructing the connecting line from the closest existing utility line to his point of usage. If the connected load is less than 1,000 lip, it probably is best to let the utility provide the primary substation. For larger connected loads the owner can obtain a more favorable "primary voltage" rate if he provides the primary substation to receive the incoming power and transform it to the distributing and usage voltages. 3. The cost of purchased power usually is made up of a demand charge, deter¬mined by the maximum amount of power the customer takes during any 15-min period throughout a month, and a graduated energy charge for the kilowatt-hours consumed-that is, so much for the first block of energy based on the demand,

Jan 1, 1973

By Sean Dessureault

The ubiquity of big data, internet of things (IoT), and smart devices is radically changing society; our personal lives are being tracked, digitally motivated through gamification, where information has become an addiction at all income levels, genders, and generations. These forces should not be held at bay in mining; rather, we should embrace and take advantage of this phenomenon to improve safety and productivity. It is time to rethink long-held conventions behind Fleet Management Systems, such as permanently mounted hardware, connecting through cables and Bblack boxes^, equipment centric rather than operator-centric, wireless requirements, minimal to no feedback to the operator, and high costs. We should also reconsider how we are collecting much of our safety, training, and preoperational forms on paper that then, must be entered into computer systems for compliance, and rarely if ever used in analytics, rather than entering the data directly into a digital device. Collecting safety and location data directly digitally also unlocks the information contained in safety forms and audits enabling new data mining and analytical approaches. Managing then gaining value from this new, greatly expanded mountain of largely unstructured data, requires the use of modern tools and approaches, such as gamification and big data, as well as skill sets, not traditionally available in mines. Furthermore, tablets can now provide a better user experience as well as new sensors when compared with traditional fleet management systems (Mining Magazine 2019, 2016, 2015), at a fraction of the cost, employing the extremely esthetic and engaging visuals derived from the video game industry. Real case studies of these applications of both technology and approach, such as gamification, show that these tracking technologies can bring high visibility and large amounts of data to even the smallest operations and the challenge of making use of the data can be facilitated through the application of gamification. As with our personal smart devices, these technologies are poised to deliver huge improvements in operator feedback, tracking, and performance management, at a much lower cost per unit.

By Eric Leung, Stephen G. Hardcastle, Andrew Dasys

In today's economic environment, Canadian mines can ill afford to neglect their ventilation systems as they can consume 30- 40% of the electricity used in underground mines. In addition, Canadian mines can incur significant heating costs. For mines to be their most cost efficient they must embrace existing and emerging technology to optimize the use of their air; namely, maximizing its work in diluting and removing pollutants, limiting leakage, and avoiding the unnecessary consumption of costly fan pressure all the while ensuring the health of their workforce. Furthermore, in Canadian mines which are heavily dieselized there is great interest within the industry to convert from a rigid quantitative approach to ventilation, based upon engine size, towards a more flexible qualitative approach that provides credit for Clean engine technology" and permits ventilation supply to be driven and based upon pollutant demands. In the future, there is even the possibility that ventilation will only be required to supply oxygen to diesel equipment as the underground hands-on workforce is replaced by surface workers and tele-operation. Such changes will allow mine operators to minimize their electrical usage and operating costs, for in its simplest form the cost of running a fan is proportional to the quantity3; therefore, reducing current ventilation demands or limiting increases brought on by more stringent legislation, can produce very significant cost savings. CANMET, through ventilation surveys and use of its modern 3D-CANVENT ventilation simulator, have been demonstrating to the mining industry how ventilation can be optimally delivered at reduced costs. El-Equip with their leaky-feeder communications and MultiVENT monitoring and control system have facilitated mines to control fans and hence costs, and also monitor such ventilation parameters as pollutant concentrations. These two parties are now combining their efforts to develop an integrated air management system which will be demonstrated at CANMET's Experimental Mine Val D'Or, Quebec. With such an air management system, the ventilation engineer will have: 1) a simple to use simulator to design and test ventilation scenarios; 2) remote controls of fans, doors and regulators to implement changes; and 3) real-time monitoring of airflow, pollutant concentrations, and both vehicle identity and location to show whether changes are necessary. It is only when all three are available, that a mine's ventilation system can be operated at minimum cost.

Jan 1, 1997

By Frank G. Horino, V. E. Hooker

INTRODUCTION The determination and use of mechanical properties of rock in engineering and rock mechanics are rapidly developing. Many of these properties are determined on intact rock specimens; thus, their application and repre¬sentation of rock mass properties may be limited. How¬ever, relative information often provides useful guidance in the solution to mine design and stability problems. Summarized in this chapter are some of the stan¬dardized techniques and procedures currently used to obtain these mechanical properties. Typical applications of the use of these properties are also presented. Stan¬dardized techniques include those advanced by the American Society of Testing and Materials (ASTM), International Society of Rock Mechanics (ISRM), US Bureau of Mines (USBM), Canadian Dept. of Mines and Technical Surveys, South African Institute of Min¬ing and Metallurgy, and other individual investigators. Information on the mechanical properties of rock and the behavior of the rock under a given system of stresses represents a necessary part of the information for rational engineering design for any given mining op¬eration. The mining method, the type and extent of sup¬port, the extraction ratio, the overall dimensions of the mine, and the orientation of the rooms and pillars are all decisions that are influenced by the mechanical prop¬erties of the ore, roof, and floor material under various stress systems and the magnitude and direction of the in situ stresses (Hooker, Bickel, and Aggson, 1972). Initial mechanical property information regarding a structure or mine property is generally obtained by two basic techniques: (1) static and dynamic property tests are conducted on intact and fractured rock specimens of exploratory drill core, and (2) dynamic properties are obtained by borehole logging techniques. When mining access becomes available, and as the mining horizon is expanded, additional information can be ob¬tained to verify preliminary mine design values. This chapter presents some of the standardized tech¬niques and equipment currently used in obtaining me¬chanical property data in the laboratory. The properties considered are: (1) uniaxial compressive strength of intact rock core specimens, (2) uniaxial compressive strength of rock cores containing planes of weakness, (3) triaxial compressive strength of intact rock core specimens, (4) triaxial compressive strength of cores with a plane of weakness, (5) Young's modulus, (6) Poisson's ratio, (7) density or apparent specific gravity, (8) modulus of rupture, (9) indirect tensile strength, and (10) creep characteristics. Where possible, an at¬tempt will be made to evaluate each property measure¬ment in relation to the problems of rock mechanics and application of results. TEST SPECIMENS The selection and care of drill core for laboratory testing require some consideration. It is recognized that laboratory-determined properties are not necessarily rep¬resentative of an in situ rock mass property. However, relative information between beds or zones of interest is still valuable information in selecting mining horizons and preliminary design criteria. To provide statistical data the number of drill core samples selected to repre¬sent each of the areas of interest should be from a mini¬mum of three to a maximum of ten test specimens. A judgment must also be made on site as to whether the recovered drill core should be wrapped and sealed in plastic to preserve moisture. On the one hand investiga¬tions of air-dried and saturated specimens have shown that moisture significantly affects the elastic properties and strengths of many rock materials (Obert, Windes, and Duvall, 1946; Colback and Wiid, 1965); on the other hand it is apparent that most core drilling is done with water which may saturate the specimen to a greater extent than in the in-situ condition. Whether or not the decision is made to retain the moisture, the core should be delivered to the laboratory as soon as possible after recovery for subsequent specimen preparation and testing. Specifications Shape: The shape of the specimens influences lab¬oratory testing in two ways: (1) time and cost of sam¬ple preparation and (2) strength of the material. Cy¬lindrical specimens of drill core are by far the least time-consuming to prepare for static or dynamic labora¬tory testing. In addition, the cylindrical shape lends it¬self to a more uniform stress distribution throughout the sample than other shapes, such as rectangles and hexa¬gons. The compressive strengths of various shapes have been studied (Grosvenor, 1963, and Price, 1960), and results indicate that the cylindrical specimens usually provide the highest strength for a given height-diameter ratio. However, reduction in strength from a cylindrical shape to a rectangular in situ pillar is not regarded as significant in relation to other considerations such as planes of weakness in a pillar or safety factors in the design process. Length-Diameter Ratio: The length-to-diameter ra¬tio, LID, has a significant effect on the compressive strength. Various recommendations have been made to use standard LID ratios ranging from 2 to 2.5 to 3 (ASTM, 1975c; ISRM, 1972). However, past work by others such as Obert, Windes, and Duvall (1946) has shown that excellent results can be obtained using LID ratios from 2 > (LID) > >/s. In selecting an LID ratio for testing, one should keep in mind the amount of material available for testing. In many instances, this may be limited. Thus, a shorter specimen such as 1: 1 LID may be necessary to provide enough test data for statistical analysis of results. Sec¬ond, it may be desirable to obtain elastic constants dur¬ing the test. This generally requires instrumentation such as linear variable differential transformers (LVDTs) or strain gages near the center of the specimen. In this case, an LID of 2.5 or 3 is desirable so that the instru

Jan 1, 1982

By James R. Arnold

Gold Fields Mining Corporation started processing ore from it's Chimney Creek operation in northern Nevada in November, 1987. Since that time production has averaged about 200,000 ounces per year from the milling and dump leaching circuits combined. The events that led up to commissioning of the plant started in January of 1985 when the Gold Fields exploration team drilled their first hole in an area now known as Discovery Hill. The major orebody was located later in the year in what is currently the major focus of activity, the North Pit. Subsequent drilling since plant startup has found another 14 million tons of ore two miles south of the original orebody. This South Pit orebody is currently being stripped and metallurgical testing is underway. Engineering Engineering on the Chimney Creek plant started in earnest in May, 1986. Davy McKee Corporation from San Ramon, California, did both the engineering and the construction management. Before engineering began the entire senior staff of the Plant Department was hired and assigned to the project. Senior staff included the Plant Superintendent, Plant General Foreman, Maintenance General Foreman and Chief Metallurgist. Gold Fields does not employ an internal central engineering staff to design their plants. We feel that the people who design the plant should be the ones who will be required to run it once it has been commissioned. This philosophy affords a continuous accountability from start of design through commissioning and operations. All four of the senior staff spent the most critical phase of the engineering stage at Davy McKee, so the plant is truly a reflection of all four disciplines. In bringing on the Maintenance General Foreman from the start, there was a focus placed on ease of maintaining the plant. Another philosophy that was adopted from the start was that the plant be easy to work in and maintain for both operators and maintenance personnel. Numerous design criteria were given to Davy McKee to ensure this. For example, we required that every piece of equipment could be reached easily with a crane or fork lift. All conveyors were required to have walkways on both sides for ease of maintenance and a minimum of 30 inches of clearance under them for ease of cleanup. Visibility for operators was considered very important and the control rooms and general plant layout were designed with this in mind. A list of about 100 general rules were given to Davy McKee during the early layout meetings and these were held as the general design criteria throughout engineering and construction. While engineering was progressing in San Ramon, California, dump leach test work was being done at the site. Three 6 foot diameter fiberglass columns were constructed and filled to a 20 foot height with low grade ore. Leaching characteristics were determined and the dump leach design was based on information collected from these columns. Construction The major contractors on the project were The Industrial Company for the bulk of the piping and structural, EMKO on the electrical/ instrumentation and Hunewill for most of the earth work and leach pad construction. All plant operating and maintenance personnel were employed eight weeks before startup for intensive training. Instructors were Gold Fields personnel, including foremen, and Davy McKee engineers. On occasion, selected suppliers representatives were brought in to discuss major pieces of equipment. Project completion was targeted for January, 1988 at a projected cost of 78.9 million dollars. Actual startup was about 1 1/2 months ahead of schedule and slightly under budget. Full design capacity was achieved the first full month of operation. Crushing Run of mine ore is delivered to the crusher and dumped into a 90 ton hopper which is topped with a 30" X 30" opening stationary grizzly. Ore is fed to a 50" X 60" Telsmith jaw crusher with a 5' wide apron feeder. The closed size setting of the

Jan 1, 1989

By William H. Mount

INTRODUCTION Effective mine ventilation is required to maintain a healthy underground environment for humans. Without effective ventilation, the environment can become unhealthy or hazardous as a result of the depletion of oxygen, contamination with toxic gases, or the buildup of an excessive amount of particulate matter (dust). Each contaminant has an upper limit of concentration that should not be exceeded within an 8-hr period. This is known as the threshold limit value (TLV). The TLV represents an acceptable level of exposure that should produce no ill effects. Unfortunately, more than one contaminant may be present at any one time and the effects of the individual contaminants may be additive, i.e., the effects of each contaminant must be considered simultaneously to determine the potential danger to miners. Possibly the greatest threat to mine-air quality is the uncontrolled underground use of the diesel engine. The diesel engine was invented in 1892 by Rudolf Diesel. His intention was to develop a power source that could burn coal dust as a fuel, but he was unsuccessful in that attempt and had to resort to liquid petroleum fuels (Johnson, 1975). In 1898, the diesel engine was intro¬duced into the United States by Adolphus Busch, who anticipated using it as a prime mover in factories and generating plants. At that time, the diesel engine was a very large and very heavy engine, designed for fixed installations. By 1919, lighter engines were being developed, and by 1931, Caterpillar was marketing a diesel-powered, track-type tractor (Henderson, 1975). Since 1931, the diesel engine has evolved into an extremely popular prime mover in medium and heavy-duty applications. Efficiencies now are on the order of 40% and improvements such as turbocharging and aftercooling have produced engines capable of generating power at a ratio of 0.3 kW/kg (1.0 hp per 5.0 lb) of engine weight. Although the diesel engine is relatively efficient as a mobile power plant, it is far from efficient in terms of the energy produced from the energy potential of the fuel. About 60% of the heat value of the fuel leaves the engine as wasted heat, with about 50% of that heat being emitted through the exhaust pipe and the other 50% being emitted through the radiator or cooling fins. Perfect combustion in an engine would produce only water vapor (H_0), carbon dioxide (CO_), and nitro¬gen (N2) as the byproducts. Since the diesel is not a perfect engine, each pound of fuel burned generates 5.6 m° (200 cu ft) of exhaust gas, containing about 0.009 m3 (0.33 cu ft) of carbon monoxide (CO), 0.009 m' (0.33 cu ft) of nitrogen oxides (NO, NO2, and NOD), and 0.57 m3 (20 cu ft) of carbon dioxide. The balance of the exhaust emission consists of free nitrogen and water vapor (Hurn, 1975). Contrary to popular belief, the diesel is not inherently dirty. Under normal operating conditions, a well-maintained engine neither smokes nor smells. However, the same well-maintained engine can and does produce toxic emissions. A diesel engine is not inherently safe and constitutes a distinct hazard to personnel. This chapter is devoted to a description of the various toxic substances that may be generated by a diesel engine. Although some of these substances may also be produced by blasting or natural causes, the focus of this chapter is on the relationship between the internal- combustion compression-ignition engine (the diesel) and the quality of the mine air. CARBON MONOXIDE Combustion Process During the combustion process (burning) of organic fuels, each atom of carbon combines with two atoms of oxygen, provided that a surplus of oxygen atoms is available. Thus, the carbon is oxidized to carbon dioxide. Most open flames, such as trash fires, camp fires, gas ranges, etc., produce carbon dioxide. However, with insufficient oxygen, incomplete combustion results as the carbon atoms each combine with one atom of oxygen to produce toxic carbon monoxide. Burning charcoal briquettes produce carbon monoxide because the combustion takes place inside the briquettes where sufficient oxygen is not available to the combustion process. Internal-combustion engines, whether burning gasoline or diesel fuel, also produce carbon monoxide. The only oxygen available to the combustion process is that trapped within the cylinder. If the amount of fuel delivered to the cylinder is excessive, there is insufficient oxygen for complete combustion and carbon monoxide production results. In a normally aspirated (nonturbocharged) diesel engine, the amount of air "sucked" into a cylinder is the same on every intake stroke, resulting in complete combustion only at low levels of engine loading, when small amounts of fuel are injected. Higher levels of engine loading cause larger amounts of fuel to be injected into the same volume of air in the cylinder. Unless the volume of air is increased, the combustion process becomes progressively less complete as the amount of fuel increases. Turbocharged engines are able to compensate some¬what for increased loading and increased fuel consumption. The turbocharger acts as a compressor for the intake air, forcing a larger volume of air into the cylinders as the engine speed increases. Hence the turbocharged engine burns cleaner than a naturally aspirated engine and produces slightly less carbon monoxide (Marshall and Fleming, 1971). Much of the underground equipment used today is powered by turbocharged indirect-injection diesel engines. Although these engines emit fewer toxic contaminants than naturally aspirated engines, they do not eliminate the problem. Since the turbocharger is driven by the exhaust gases, rapid accelerations can cause temporary overfueling of the engine until the turbocharger attains a speed sufficient to restore the correct air-to-fuel ratio. During this "turbocharger lag," the combustion cylinders contain insufficient oxygen, causing severe smoking and an increased output of carbon monoxide.

Jan 1, 1982

By John Newby, Ulf Gwildis, Fred Marquis

From the Brightwater Conveyance System in Seattle to the Second Narrows Water Supply Tunnel in Vancouver, BC, the design and construction of deep-lying tunnels in the Pacific Northwest often require the incorporation of deep portal shafts. Alluvium overlying marine and glacial deposits combined with the high regional seismicity is the common geologic setting. The latest example illustrating the development of shaft design for this scenario is the 40-m-deep shafts of the Annacis Island Wastewater Treatment Plant New Outfall System. The main components of the shafts include the initial lining, providing the excavation support system to be used for launching and receiving a 5-m-diameter TBM; and the final lining, designed to withstand all static and seismic loads and to remain viable for the intended design life. This paper presents design and construction considerations for these shafts against the background of and lessons learned from past project experiences.

Jun 13, 2021