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By Bill Cain, R. John Caulfield, D. Scott Kieffer

The East Bay Municipal Utility District is undertaking seismic upgrades of the Claremont Tunnel in the San Francisco Bay area. The tunnel carries treated water across the active Hayward Fault to supply a major metropolitan area. Studies indicate the tunnel could be severed by fault offset during a major seismic event. A design approach to achieve limited operation of the tunnel following fault displacement has been established and design details are currently being evaluated. This paper describes the project, the design approach, and summarizes significant construction constraints.

Jan 1, 2001

Amid some of the worst economic conditions that the mining industry has been faced with in more than a decade, the mood among the large crowd at the 114th Annual Northwest Mining Association?s annual meeting was surprisingly upbeat. More than 2,200 attendees showed up at John Asuaga?s Golden Nugget Casino in Reno, NV for the conference held Dec. 1-5. And more than 200 companies exhibited in 240 spaces, including SME and the Minerals Information Institute. The number of attendees and exhibitors were the most for the conference in more than 10 years. The conference was held in Reno/Sparks for just the second time in its illustrious history but began under the cloud of global financial turmoil. Prior to, and during the conference, the industry news headlines were grim, to say the least. An alarming number of mine plans and expansions had been put on hold; hundreds of miners across the United States had been or were in the process of being laid off; commodity prices were falling and some of the biggest mergers in the industry fell through while miners around the world put the brakes on to take a wait-and-see approach. It was a painful time for many, but the downsizing actions taken by many mining companies was exactly what needed to happen, according to Industry Outlook Luncheon featured speaker Frederick Sturm. He is the executive vice president and chief investment strategist and member of Mackenzie?s Investment team. He has earned a reputation as one of Canada?s leading investors in natural-based companies and he also manages the Ivy Global Natural Resource Fund in the United States Sturm said that the mining industry has fallen hard and that he expects it to bounce back quickly, before falling hard again. In these tough times, he said, the companies that have pulled back on production early are doing the right thing in the long run.

Jan 1, 2009

By Michael Day, Paul Kos, Scott Brinton

A hydrogeologic characterization and impact analysis was performed for a proposed quarry at the Hitch Rack Ranch located in the Little Turkey Creek watershed southwest of Colorado Springs, Colorado. Continuous multiple channel tubing, nested piezometers, stream flow measurements, and mapping of known seeps were used to define the three-dimensional potentiometric distribution and areas of groundwater recharge and discharge. Water balance considerations, mass balance calculations, and potentiometric response to earth tides and barometric fluctuations confirmed that the granite fracture system in the ridge area of the proposed quarry has an extremely low bulk hydraulic conductivity resulting in minimal groundwater discharge to sustain the baseflow of Little Turkey Creek. The Little Turkey Creek valley forms the major conduit for groundwater flow exiting from the upper part of watershed underlain by granite. This conclusion has significant implications with respect to mine planning to minimize projected impacts to the hydrologic system and preserve this recharge component to downgradient Denver Basin sedimentary deposits.

By Corby G. Anderson

Since 1985, the Sunshine Mining Company has used a patented nitric-sulfuric acid pressure leaching system for production of silver and copper from a refractory sulfide ore body. To better understand this novel process, a program of lab scale testing was undertaken to quantify the effect of system variables on silver recovery. Some of the factors studied include temperature, agitation, acidity, vessel pressure, particle size, percent solids and oxidizer amount. In turn, this knowledge will be applied in actual plant practice to upgrade reaction time, increase concentrate throughput, raise silver recovery and lower reagent costs. A discussion of plant process changes resulting from lab scale testing is included.

Jan 1, 1991

By Ray Brainard

The Jollyville Transmission Main will be a 10.5-km- (6.5-mile)-long, 213-cm (84-in.) diameter rock tunnel. The tunnel will pass beneath the Balcones Canyonlands Preserve, which was established to protect two endangered bird species, six endangered cave invertebrates and a threatened salamander. To address the sensitive habitat that the transmission main is to pass through, the city of Austin developed an environmental commissioning (EC) process that brought together environmental engineers and scientists, the city?s project management team and the designer team to work collaboratively to meet the city?s goals of producing a cost-effective design while also protecting the environment. This paper describes the environmental commissioning process and the benefits it brought to the project and environment through some unique environmental mitigation measures to protect this sensitive area.

Jan 1, 2012

By Jai Ghosh, Aprad E. Torma, Roger Guay

The catalytic effect of ferrous ion in the industrial biohydrometallurgical heap and dump leaching processes is explained. During the bacterial leaching of metal sulfides, ferric ion will partly be hydrolyzed and a variety of sols, gels, amorphous and/ or crystalline mono- and polynuc- lear hydroxo- and sulfato complex species formed, especially by olation and aggregation reactions. There are many problems associated with these iron precipitates especially in the purification of leach solutions. The present study will discuss the iron precipitation reactions; gives kinetic and thermodynamic evaluations of the effect of temperature on pyrite and ferrous iron oxidation; and reports on the tolerance of heavy metal ion concentrations by Thiobacillus ferrooxidans.

Jan 1, 1989

In 1950, about a third of the world?s population lived in cities. That figure has steadily risen throughout the following decades. Now it is believed that about 60 percent of the estimated 8.1 billion people in 2030 will be living in urban areas. The strain on infrastructure in cities in the developed world is already showing. And the rapid growth in developing nations today is adding to the shortage of materials, equipment and labor needed to keep up with this growth. So, while materials and labor may be in short supply, there is no shortage of work for the underground tunneling and space industry. In June, 718 of those professionals from around the world were in San Francisco, CA for the North American Tunneling (NAT) conference, put on by the Underground Construction Association (UCA) of SME. The attendees spent the three days of technical sessions listening to international authors discuss the state of the industry, new technologies that have become available and updates on major tunneling projects throughout the world. The accompanying exhibit attracted 79 vendors, who displayed the latest in tunneling and underground space equipment and services. In addition to the technical sessions and the exhibit, the NAT featured three short courses ? ?DRB Process Update Workshop,? ?Soft Ground Tunneling Technologies? and ?Underground Blasting Technology and Risk Management.? And the post-meeting field trip to the Devils Slide tunneling project near San Francisco was sold out.

Jan 1, 2008

By Clayr Alexander

Stillwater Mining Co. (SMC) is engaged in developing, extracting, processing and refining palladium, platinum and associated metals (PGM)from the J-M Reef. This geological formation is located in Stillwater, Sweet Grass and Park counties in southern Montana. Associated byproduct metals include rhodium, gold, silver, nickel and copper. SMC’s current mining operations are near Nye, MT. The company is currently developing a second underground palladium and platinum mine, the East Boulder project, about 21 km (13 miles) west of the Nye operations. A 5,650-m (18,550-ft) tunnel is required to gain access to the ore-bearing horizon (J-M Reef).

Jan 1, 1999

By Douglas R. Cook

Exploration record In preparing this paper, a list of world class discoveries prepared in 1983 has been updated. In both surveys, the following criteria were used in the definition of world class discoveries: • deposits that are continuously operated and consistently return a profit even in periods of low metal prices; • deposits large enough to significantly affect a medium sized corporation's profits; and • these deposits should be in the lower one-third cost per unit of metal produced for all similar deposits. Only 70 discoveries in the last 40 years qualified as world class deposits using these criteria. Unfortunately, this restricted population was too low to develop meaningful trends. The numbers were therefore enlarged to include all significant discoveries. The principal feature of a significant discovery is that its size and grade would yield more than $500 million in revenue using average metal prices for the last five years. A significant deposit should also meet some of the standards for a world class deposit. A tabulation of these deposits are shown in Table 1. The number of discoveries increased to 166 from 70 using the revised classification. The relationship between the number of discoveries per year and their location by continents was prepared from these data. Figure 1 shows the number of discoveries per year for the nonCommunist world. It also shows estimated and actual nonCommunist world exploration expenditures per year and the commodity price index. These data show that modern exploration started in the late 1940s, with the tempo picking up rapidly in the 1950s. The maximum discovery rate occurred in 1962. Thereafter, the discovery rate gradually declined to the present. This occurred despite a real increase in expenditures from about $200 million/a in 1955 (1982 constant dollars) to more than $900 million/a in 1980. Thus, these data suggest a significant decrease in the exploration success ratio (total exploration expenditures a year divided by the number of significant discoveries) in the last 20 years. As an example, $70 million was spent for each significant discovery in the early 1960s as compared with $225 million in the late 1970s (expressed in 1982 constant dollars). However, with the general declining trend of discoveries, one can perceive a more pronounced drop in 1973 and then a sudden increase in 1974, 1975, and 1976. This increase is probably related to the inflation of the 1970s that in turn created an environment for the explosion of commodity prices, as shown by the commodity price index on Fig. 1. Thereafter, the decline in discoveries resumed in 1975 until the present. Exploration performance by regions North American discoveries are shown in Fig. 2. The graph shows three pronounced high discovery peaks in 1962, 1975, and 1980-81.

Jan 2, 1986

By David Kress

Mill crushing drive systems are essential to cement producers. With the increased emphasis on operating efficiency, it is vital that these systems be dependable and reliable. No one needs the costs or headaches associated with unscheduled downtime or inefficient machinery operation. A reliable drive system starts with the proper selection of the ring, or girth, gear and continues through proper maintenance. Ideally, selecting the right girth gear brings together the gear manufacturer, the system designer and the end user. The gear manufacturer must know the details of the application, the demands that will be placed on the gear and the nature of the equipment to be driven. Similarly, the user and the system designer must be familiar with the variables that affect gear drive performance and service. For example, an application that places a torque load on the drive in excess of its rated capacity will result in gear tooth distress and, in severe cases, breakage.

Jan 1, 2000

By John B. Sabey, Vernon R. Degner

The industrial coal processing trend toward greater fines production, due to mining techniques and customer requirements for reduced ash and sulphur content in the fine coal product, is the basis for ongoing efforts to improve the performance of the flotation machine. WCO has successfully adapted the principles of the beds Column to a full size machine prototype. Recent plant evaluation tests confirmed the initial promise of this concept by achieving a considerably lower ash product while maintaining the combustible recovery level of conventional flotation machinery. The paper will include a review of the fundamental principles of the beds Column concept, together with a summary of the WEMCO R&D Program from concept evaluation and laboratory testing, through pilot, to full size machine tests. The performance of the WEMCO/Leeds flotation column will be compared to conventional flotation concepts using a flotation "kinetics" approach, which quantifies the floatable and non-floatable specie recovery performance using the Klimpel model as the basis for analysis. The variety of distinct features unique to this concept include a series of barrier rods which are used to advantage, often together with countercurrent reflux water flow, to achieve a significant improvement in product grade. The hydrodynamics associated with the mechanics of "gangue stripping" from the rising "air bubble-floatable specie" matrix will be briefly reviewed.

Jan 1, 1988

In Alaska?s southwest corner, in the Bristol Bay region, 476 holes have been drilled to help define the size of the Pebble Project. The results indicate that the deposit holds close to 32 Mt (72 billion lbs) of copper and 2.9 Gt (94 million oz) of gold. The Pebble Partnership, an Alaskan limited partnership of Anglo American and Northern Dynasty Minerals, owns the project that consists of two world-class mineral deposits. Currently in the prefeasibility and prepermitting stage of development, the Pebble Project is one of the largest and highest profile exploration projects in North America. History The Pebble West Project was originally discovered in 1988 by Cominco (now Teck Cominco). Drilling programs in 1997 defined a near-surface mineral deposit of 1 Gt (1.01 billion st). Minerals found included copper, gold and molybdenum. Northern Dynasty Minerals acquired the property in 2001 and, by 2005, it had confirmed a measured and indicated resource of 4.1 Gt (4.5 billion st) containing 1.2 kt (42.1 million oz) of gold, 11.2 Mt (24.7 billion lbs) of copper and 612 kt (1.35 billion lbs) of molybdenum and additional silver. By September 2005, Pebble East, a deeper, but richer deposit had been found. Drill data by the end of 2005 confirmed a 3.4-Gt (3.7-billion st) inferred resource containing 19 Mt (42.6 billion lbs) of copper, 1.2 Mt (39.6 million oz) of gold and 1.2 Mt (2.7 billion lbs) of molybdenum.

Jan 1, 2009

By Judy B. Jones, Bradley A. Crenshaw, Theodore DePooter

This paper reviews groundwater issues leading to a secondary grouting program at the Chattahoochee Tunnel that was implemented subsequent to the contact grouting program. The secondary grouting program was developed based on infiltration data, geology, and testing programs. This paper includes a brief description of the geological features encountered, as well as describing the grouting program. The success of this grouting operation has been quantified by several methods, and is presented to help others project the costs and benefits of this type of program. Review of initial results and refinements of techniques are also discussed.

Jan 1, 2005

By Larry S. Diaz

The paper considers the selection of control instrumentation for a modern flotation plant, as well as the best interpretation and most effective use of the process data obtained. Process control computer availability is considered from the outset. A general philosophy of control is proposed which leads toward a system that is its own reliability monitor. The bulk of the problems are in grinding and classification. Alternative control methods are described that use particle size measuring devices. Flotation controls, based to a large extent upon on-stream X-ray analysis, are reviewed in detail. Reagent control methods are also examined. Methods to analyze the data obtained from the various measurement devices are introduced. These methods would enable an estimate of the validity of the data and require some redundant information. Another objective of these methods is the protection of operating equipment from possible control malfunctions. Although the discussion generally considers some degree of computer usage, this paper attempts to describe instrumentation and data analysis methods that enable control with or without the process control computer.

Jan 1, 1972

By Pat C. Hautala, J. R. Hoskins

This is a new era for the minerals industry. Never before has there been more need for effective communication. So said Robert Anderson, chairman and chief executive officer of Hanna Mining Co. He was speaking to the American Mining Congress's Communication Workshop. The question is whether there is enough industry concern to meet the challenge. Anderson observed that increased workshop attendance, in continuing tough times, reflects the industry's concern for communication. But, why were students, faculty, engineers, supervisors, and managers not at the conference? Communication applies to every manager, Anderson said. But he was the only operating manager present. And only one company sent operating supervisors. The remaining conference participants were public relations personnel, generally with nonmining backgrounds. And the program dealt mostly with public relations issues. Role of Communication in the Minerals Industry. It is well known that the minerals industry faces economic, political, and social problems. Economic shifts and foreign competition have created an international minerals industry and an international marketplace. This, in turn, calls for worldwide communication. Other factors effecting communication are: • Governmental protectionism as well as regulatory reforms call for increased interaction with governing officials. • Changing social values have created environmental issues and anti-industry attitudes. This intensifies the need for improved public relations. • Traditional work values are shifting towards self-actualization and humanistic movements. The work force is better educated and more informed. Employees demand more satisfaction, equality, and job autonomy. • The mining industry's task of managing its human resources is complicated by layoffs, job uncertainties, and bleak outlooks concerning employee morale and motivation. Technology and Information for a New Era As noted, this is a new communications era, one propelled by technology and information. Technology has led to reduced demand for raw materials by developing substitutes. Copper demand, for example, will never fully recover. Copper cables are replaced by fiberoptics; copper transmission lines, with aluminum. Technology has shifted the US from traditional to high tech and service industries. The speed, frequency, and scope of information transmission have greatly increased. But the most significant characteristic of this information is not the pace of advancing technology. It is the dramatic increase in the importance and frequency of our personal transactions. Knowledge has replaced raw materials and capital as the strategic resource. Information has replaced energy as the transforming resource. And the game against nature has become an interpersonal game (D. Bell, Post-industrial society, Physics Today, '76). In Megatrends, John Naisbitt says that information will soon double every 20 months. So, professionals will become "information workers." And communication will be the life channel of the information age. Thomas Wolfe said you can't go home again. Hanna Anderson said we are, indeed, facing a new day. It will never again be "business as usual." We must move into the information age with the rest of society. We cannot trust that the world will continue to rely on our products. Nor can we place the responsibility and control for problems and solutions outside the minerals industry. Improved communication is not a panacea. But, Anderson said, it is critical to the minerals industry. What is Communication? The word communication is overused. It is applied to every aspect of our lives. Satirist Tom Lehrer got sick of hearing about the need to communicate. He said, "It seems to me that if someone is having all that trouble communicating, the very least he can do is shut up!" Obviously, we cannot follow that advice (though we might wish that some others would do so). Communication is always going on. It is inevitable. Yet we have many misconceptions about com-

Jan 1, 1985

The largest investment in mining equipment in Caterpillar?s history ? The F series mechanical and electrical drive trucks ? is rapidly advancing. Caterpillar showcased the 793F and 797F mechanical drive trucks and the 795F ac electric drive truck at MinExpo in 2008 and have continued testing since then. The 793F and the 797F have accumulated more than 75,000 hours of field testing and have proven their performance capabilities and their durability. The new Cat C175 engine that powers them has racked up 130,000 hours of field testing in mining trucks and more than 120,000 hours in power systems. Because of the success of these field-follow programs, the 793F is targeted to go into full production within a few months and the 797F late this year. Caterpillar engineers have been testing two 795F ac prototypes at the Tucson Proving Grounds in Arizona. The development program has provided input for the construction of a new 795F ac in Decatur, IL. The new truck recently shipped to a copper mine in North America where it will serve as the first field-follow 795F ac as it works at the mine. The 313-t- (345-st-) capacity 795F ac will enter a new size class for Caterpillar, and, as a result, the primary focus of the Caterpillar ac electric program has been on the 795F ac. The commercial launch date will be defined as the field-follow program progresses. ?It?s fitting that soon after producing the 50,000th Cat off-highway truck, we are now shipping our first ultra-class ac electric drive truck to a mine,? said Chris Curfman, president of Caterpillar Global Mining. ?Our new trucks further solidify our position as the one manufacturer to provide unparalleled options and unmatched customer support.?

Jan 1, 2009

By Dennis Molvik, Omar Fulton, Chris D. Breeds, Don Gonzales

This paper presents and describes the South Interceptor Parallel Phase III Contract C93012C, which involved construction of a nominal 2.7 m (9-ft) finished diameter sewer conveyance using both pipe jacking and conventional tunneling methods. Earth Pressure Balance (EPB) excavation was required to minimize the potential for settlement beneath a main rail line, overpass, sensitive wetland, areas of contaminated soils, and nearby structures. Ground conditions predicted in the Geotechnical Baseline Report included low plasticity, clayey silt (40 to 10%) and silty sand (60–90%) with pieces of wood such as logs, stumps, branches and other tree fragments. Soil cover ranged from 2.7 m (9-ft) to 5.4 m (18-ft) over the tunnel crown with a groundwater table between 1.5 m (5-ft) and 3.7 m (12-ft) deep.

Jan 1, 2003

By Jennifer L. Bell, PATRICK L. YORIO, Emily J. Haas, Susan M. Moore, Lee A. Greenawald

Although researchers have struggled to replicate Heinrich’s safety triangle findings (Heinrich 1931) for various reasons (e.g., no access to his original database and it is unclear if the database was of a single establishment/operation or for an entire industry), the occupational safety community has continued to adopt and expand the applications of this theory (e.g., McSween 2003). Within the mining industry, the potential exists for operations and companies to use concepts from the safety triangle as a way to inform or challenge the practices employed within their health and safety management systems (HSMS) to prevent incidents (Backlund 2016). This paper considers data obtained from the Mine Safety and Health Administration’s databases and demonstrates the validity of applying the safety triangle theory at the mine level. The results support the use of this theory and demonstrate that lower severity incidents can predict fatalities in a subsequent year where significant nuances and caveats to applying the theory are identified and discussed.

Jul 25, 2020

By Bruno Bussière, Guosheng Zhan, Michel Aubertin, Vincent Martin, Robert P. Chapuis

The study evaluates the hydrological behaviour of exposed and covered waste rock dumps. The objectives were to determine the major factors influencing unsaturated flow in waste rock dumps and covers, and to improve the in-situ, laboratory and numerical modeling characterization methods. Using material properties obtained from in-situ and laboratory tests, waste rock dumps of different configurations, with and without covers, were modeled. It was found that a properly designed “Store, divert and release” (SDR) cover allows most of the water to be diverted downslope and discharged outside of the waste rock dumps. The SDR cover seems to work efficiently even in extreme storm events. The numerical modeling results show that the unsaturated hydraulic properties (e.g. air entry value and water entry value) of the materials largely control the infiltration of water into waste rock dumps.

Jan 1, 2005

By P. Rosten

US mine production of iron ore in 1984 showed some improvements compared to 1983. But reduced demand from the iron and steel industry caused temporary shutdowns of many iron ore mines and pelletizing plants. US raw steel production in 1984 was slightly above 1983, but still at a depressed level. Production was 83 Mt (92 million st), compared with 77 Mt (85 million st) in 1983 and 68 Mt (75 million st) in 1982. Two major production trends continued in 1984. They were the increased production from electric furnaces and the growing use of continuous casters. Electric furnace production included 33.2% of the steel poured in 1984, compared with 31.5% in 1983. Continuous casting was used for 39% of 1984 steel production, compared with 32.1% in 1983. Statistical Process Control Statistical Process Control (SPC) has taken on new proportions in the iron ore and steelmaking industries within the last year. This mathematical technique is used to monitor, control, evaluate, and analyze a manufacturing process. The technique charts variability of important quality parameters. Training and adaptation of SPC techniaues for process control have been initiated at Inland, Steel's Minorca, Pickands-Mather's Hibtac, Cleveland-Cliff's Empire and Sherman operations, and at Reserve Mining. One of these operations has requested its bentonite supplier provide SPC charts on quality specifications. Some of the steelmaking operations (Inland Steel, Bethlehem Steel, Dofasco, LTV Steel, National Steel, Stelco, Weirton Steel, and Wheeling-Pittsburgh) have set up SPC programs within their operations. And they also have insisted that some of their suppliers use SPC. Plant Shutdowns The permanent closure of Stelco's Griffith mine at Red Lake, Ontario, has been delayed by one year. This gives employees more time to adjust. The mine is now set to close in April 1986, instead of April 1985. Sidbec (Canadian government) and its other partners (including British Steel Corp., Quebec Cartier Mining, and US Steel) closed its iron mining operations at Gagnon, Quebec. The pellet plant has been leased to Quebec Cartier. New Iron Ore Operations The massive Carajas iron ore project in Brazil is scheduled to come onstream in Jan. 1986. It is to achieve full-scale commercial shipments by July of that year. The 66% iron crude ore requires only crushing and screening before shipment. The product consists of 83% sinter feed and 17% coarse ore. Annual production capacity will be 32 Mt (35 million st) when the project is completed. Principal customer for the ore is Nippon Carajas Iron Ore Co., a consortium of Japanese steel mills. The Arab Iron & Steel Co. (AISCO) has started up a $US300 million, 3.6 Mt/a (4 million stpy) iron ore pelletizing plant built by Kobe Steel Ltd., at Al Hidd-hide in Bahrain. By 1986, this grate-kiln-cooler plant will supply high quality iron ore pellets to feed direct reduction plants in the immediate Gulf area and Far East markets. Iron ore supplied from Brazil, Peru, India, and Mauritania provides the feed to the pellet plant. Hydrated lime (2%) is used as a burden.

Jan 5, 1985