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By D. C. Dahlin, W. K. O’Connor, G. E. Rush, C. A. Summers, S. J. Gerdemann

The Albany Research Center (ARC) conducted studies of mechanical activation by conventional and ultra-fine grinding techniques to enhance olivine reactivity in mineral carbonation reactions. Activated olivine is one of several solid feed materials used at ARC in reactions with carbon dioxide to form carbonate minerals. This paper compares grinding techniques via energy demand data and product characteristics, including particle size distributions, surface areas, full width at half maximum (FWHM) XRD analyses, and particle morphology by SEM analyses. Reactivity was gauged by percent conversion to carbonate in subsequent carbonation tests.

Jan 1, 2004

By Christopher J. Bise

INTRODUCTION A mine's power system represents the driving force behind all of the extraction and auxiliary operations, because the production and transportation of mined material and the operation of equipment, such as fans and pumps, are all dependent upon a power source. Once, compressed air was the primary power source in mining; today, however, electrical power dominates. This chapter reviews the basic theories of com- pressed-air and electrical power and provides several examples of applications in mine power systems. COMPRESSED-AIR POWER General Compressed air has been, and should continue to be, an important source of power in mining operations. It has been used as a means of blasting coal in conventional mining and is widely used to operate stopers, mucking machines, and other air tools in both coal and hard-rock mines. Such applications demonstrate the suitability of compressed air for applications requiring linear motion, but it is also utilized for its reliability and safety. A compressed-air system is composed of a compressor, a receiver, a distribution network, and the air-operated machines. A compressor takes in air at normal atmospheric pressure (free air) and compresses it to a higher discharge pressure. The discharge pressure must be high enough to overcome the friction in the distribution system of pipes and hoses and deliver the compressed air to the machines at the pressure recommended by the manufacturer. The most common type of compressor used in mines is the reciprocating compressor in which the air is compressed by a piston in a cylinder. An air receiver is a container or storage tank that is located in the distribution system between the compressor and the machines. It stores compressed air, when the full capacity of the compressor is not being used, and gives a more steady flow of air to the machines. The distribution network consists of pipes, Oalves, elbows, tees, and hoses that transmit the compressed air from the receiver to the machines in the mine. It is essential that the distribution system be designed with the proper sizes and lengths of pipe, hose, and other components to keep pressure losses well within allowable limits. The air-operated machines consist primarily of drifters, stopers, pluggers (sinkers), slushers, and several other pieces of equipment. Compressor Operation Every compressor is made up of one or more basic elements; a single element, or a group of elements in parallel, comprises a single-stage compressor. Many compression problems involve conditions beyond the practical capability of a single compression stage. Too great a compression ratio (absolute discharge pressure divided by absolute intake pressure) may cause excessive discharge temperatures or other design problems. It, therefore, may become necessary to combine elements or groups of elements in series to form a multi- stage unit, in which there will be two or more steps of compression. The number of stages commonly used in reciprocating compressors is as follows: Pressure Number of stages 0- 150 pig 1 80- 500 psig 2 500-2500 psig 3 2500-5000 psig 4 When pressure is referred to as pounds per square inch gage (psig), it means the pressure (in pounds per square inch) above barometric pressure as measured by a gage. The sum of barometric pressure and gage pressure is the absolute pressure (in pounds per square inch). The gas is frequently cooled between stages to reduce the temperature and volume entering the subsequent stages, thereby reducing the work required for compression. The basic reciprocating compression element is a single cylinder compressing on only one side of the piston (single-acting). A unit compressing on both sides of the piston (double-acting) consists of two basic single-acting elements operating in parallel in one casing. The reciprocating compressor uses automatic spring-loaded valves that open only when the proper differential pressure exists across the valves. Intake valves open when the pressure in the cylinder is slightly below the intake pressure. Discharge valves open when the pressure in the cylinder is slightly above the discharge pressure. In Fig. 1, Diagram A shows the basic element with the cylinder filled with air at atmospheric pressure. On the corresponding theoretical pressure-volume

Jan 1, 1986

By Robin B. Dill, Mark Pelletier, Daniel J. Dobbels, Subodh Bhaumik, Daniel J. VanRoosendaal

Although primarily cut-and-cover excavations are required for replacement of the existing elevated I-93 interstate highway through the heart of Boston for the Central Artery/Tunnel (CA/T) project, some mined tunnel construction was also undertaken. The mined tunneling conducted was the 22-m-wide northbound roadway structure which passed below a 20-m-deep operating underground subway station that was built in 1913. The innovative underpinning scheme used to support the subway station during construction resulted in the successful mining beneath the subway station with negligible vertical settlement. Two grouting galleries were carefully mined below the subway structure, and pre-grouting of the granulary, pervious glacial soils and weathered bedrock was carried out from these galleries. The reinforced concrete walls of the underpinning structure were constructed within three stacked drifts that were sequentially mined below each grouting gallery. After 11 cross adits were mined between the grouting galleries, cast-in-place post-tensioned girders that spanned between the stacked-drift walls were constructed to support the subway station. The stacked-drift walls also provided lateral support for the 22-m wide by 29-m long by13-m high opening beneath the girders.

Jan 1, 2001

By S. Devasahayam

Acid production or acid drainage is a major environmental issue that also has negative implications on the aquifer system surrounding the mine tailings area. The approach to controlling acid mine drainage involves physical and geochemical characterization that affect acid production. The material permeability determines the availability of oxygen, which is paramount in acid production in coal rejects, and varies with depth. In this paper the author presents the variation in oxidized pyrite/acid production with depth in black coal mine washery wastes. Chemical kinetic parameters and the diffusive parameters have been used to obtain the variation in oxygen content and the oxidized pyrite content with respect to the depth and time. Its dependence on porosity and moisture content is illustrated.

Jan 1, 2007

By A. L. Crandell

History The Cortez Mining District has a long history of mining activity dating back to 1862. More recently, Cortez Gold Mines had operated a cyanide leach, counter current decantation (CCD) recovery gold mill from January 1969 to February 1976. This type of plant has been standard in the US for treating higher grade, finely disseminated gold in Carlin type ores. The mill was initially operated from 1969 to 1973 at 1.5 kt/d (1650 stpd) on oxidized ore from the Cortez ore body. In 1973, the mill was operated at 2 kt/d (2200 stpd) on softer, less oxidized, high clay ore from Gold Acres, located 13 km (8 miles) west of Cortez, NV. In February 1976, the oxidized portion of the ore body at Gold Acres was depleted and the mill ceased operations. Successful heap leaching of the lower grade portion of the ores was practiced at both Cortez and Gold Acres to supplement the milling operations. Valuable experience was gained in the operation of these two heap leaching programs (Duncan and Smolik, 1977). The ore heaps at Gold Acres and Cortez were releached with a limited crew from 1976 to 1979. The surge in the price of gold in late 1979 sparked an interest to incorporate new techniques into treating lower grade and less oxidized carbonaceous ores at Cortez. In early 1980, heap leaching was started on low grade oxidized dump material left from the earlier Cortez mining operation. By June of 1980, testwork was completed on the London Extension Dump, a low grade, mildly carbonaceous dump at Gold Acres. It was decided to convert the mill at Cortez from the conventional cyanide leach CCD recovery plant to a carbon-in-leach (CIL) recovery system. In May 1983, ore processing from the Horse Canyon deposit began. The Horse Canyon ore body contains both oxide and carbonaceous ores and is located 22.5 km (14 miles) from the Cortez mill. The Cortez CIL circuit was expanded to handle a blend of oxide and carbonaceous ores from Horse Canyon. Ore selection In the last quarter 1979, gold prices were increasing to a point where restarting the Cortez mill, idled since 1976, appeared imminent. Several previously explored geologic reserves at various stages of development were available as possible sources of feed for the mill. Initial metallurgical testing of dumps and tailings from earlier operations was completed, and previously uneconomic deposits were explored. It was decided to pursue sources of ore with the least lead time to production and those with the least capital cost requirements. A master plan was developed to bring the four profitable ore resources into production. The plan called for: • Heap leaching of waste dumps from the Cortez mining operation; • Restarting the mill to handle the waste dumps from the London

Jan 9, 1986

By David C. Girard, Larry Williamson, Leonard R. Benson, Ronald E. Bizzarri

On the east side of Washington DC, the DC Water & Sewer Authority is developing a Facility Plan for the Anacostia River CSO Control Projects, including 8 to 12 miles of CSO storage/conveyance and flood relief tunnels and associated facilities. The project includes major technical and non-technical challenges, including: completion under a Federal Consent Decree schedule; large diameter (estimated 25 to 35 ft) soft ground tunnels and shafts up to 200 ft depth; operations without use of active flow control systems; and close coordination with several major public and private construction and development projects that are being advanced in the project area.

Jan 1, 2007

By G. Aggistalis, N. Kazilis, C. Rawlings, N. Rachaniotis, S. Raptopoulos, M. Knights, R. Game

The Egnatia Odos (Odos meaning road) is one of Greece’s largest ever highway construction projects and one of Europe’s most important. The Highway will assist in the connection of the Greek Ionian/Adriatic Coast with Turkey and the Black Sea reviving an historic Roman alignment “Via Egnatia” connecting Rome to Constantinople (now Istanbul). There are 74 twin tunnels (60 bored and 14 cut-and-cover) with lengths ranging from 160 m (175 yd) to 4,600 m (5,031 yd) and 100 m (109 yd) to 270 m (295 yd),respectively. The complex geology and resulting physical geography have had a major influence on both the design and construction of these tunnels. This paper describes the management, design and construction challenges of these numerous tunnels.

Jan 1, 2005

By Robert Rautenberg, Paul McDermott

This paper will discuss the construction of 15.9 km (9.88 mi) of tunnels on a project in Chicago, Illinois. The tunnels were driven utilizing two rock and four soft ground TBMs ranging in sizes from 7.39 m (24.25 ft) in rock down to 1.95 m (77 in) in soft ground. In addition to the mining, there are 63 upper level structures and 16 dropshafts averaging 61.5 m (202 ft) deep included on this project. Many diverse mining, excavation, support and lining techniques were employed on this project.

Jan 1, 1997

A large lab apparatus was designed using a scale-down methodology based on the design legacy of the current FLSmidth commercial forced air flotation machines. This new apparatus, along with a new test methodology, was used to evaluate new rapid prototype concepts. The apparatus was designed to monitor bubble size, power, pumping capacity, Jg, velocity profiles, froth character, and tip speed. The methodology developed follows a sequence that goes from hydrodynamic tests and solids suspension tests to a flotation kinetic test. This methodology has been demonstrated to be a good tool to determine the effect of machine design changes on flotation.

Jan 1, 2012

By None None

Life as a mining/mineral professional doesn’t leave much time for perusing 20-page technical papers. Yet, being technologically savvy is part and parcel of a successful career in this industry. What’s an intelligent, well-informed person to do?

By G. S. Takenaka

When Bridger Coal Company transformed their operations from surface mining to an underground longwall operation their plans included not only the addition of new mining equipment but also surface fans for a blowing (supply) air ventilation system. The original system concept included a propane gas fired air heater to preheat the intake air during cold weather and a dual parallel fan and duct system. One fan operated to ventilate the mine while the other fan was for stand-by emergency operation. Equipment proposals were submitted in March, 2005 based on the dual parallel fan system. Discussions conducted during the equipment selection process revealed that several alternative system design concepts were available. The alternative concepts included innovation features that not only saved space and cost but also reduced operating expense as well. Many of the features were incorporated into the final design of the system. A comparison of the original system concept and final installation design are presented in the paper in addition to details of the features and the derived benefits.

Jan 1, 2009

By O. N. Sikazwe

The Nchanga Cu-Co ore deposit of the Zambian Copperbelt, is hosted in Neoproterozoic siliciclastic-carbonate sedimentary rocks, and it consists of two orebodies: the Lower Orebody (shale) and the Upper Orebody (arkose). Refractory Cu ores present in the Upper Orebody comprise 150 Mt with average 0.87% Cu, and are characterized by inadequate recovery of copper by leaching. This materials characterization study, conducted on refractory ore samples from the Upper Orebody using optical microscopy, QEMSCAN®, and microprobe, has shown that copper occurs mainly in biotite, phlogopite, malachite, pseudomalachite and goethite. QEMSCAN® has quantified the abundance of each phase and total Cu deportment in each phase.

Jan 1, 2008

By E. F. Schnitzer, S. R. Mamoyac, P. J. Wampler

During 1996 and 1997, Oregon experienced flooding on a scale not seen in many years. Some gravel pits located near rivers experienced erosion and, in several cases, breaches between the gravel pit and the river. Initial evaluation of several sites that experienced breaches indicates that impacts to the river system are complex and vary significantly from site to site. The impacts to the adjacent river system may be viewed as both positive and negative. Several floodplain-mining sites in Oregon located in areas of historic river flow have reverted to active riverbed. In many cases, state and federal fisheries biologists and university researchers see the resulting increase in channel complexity and habitat as favorable. The Oregon Department of Geology and Mineral Industries – Mined Land Reclamation Program (DOGAMI-MLR) is performing additional studies of the impacts to the off-channel areas that resulted from the 1996 floods. More data is needed to make sound floodplain decisions regarding mining.

Jan 1, 1999

By N. L. Hayward, V. H. Ness

In the past decade Australia has seen the development, construction and commissioning of three complex processing plants for the treatment of lateritic nickel ores. These have all been based on high pressure acid leaching (HPAL) for extraction of nickel and cobalt into solution, followed by solid liquid separation in a CCD circuit. However, flowsheets for separation and purification of the nickel and cobalt diverge markedly. The existing plants have been commissioned with varying degrees of success, with a variety of problems ranging from materials of construction to inadequate design. While the process problems are not insurmountable, there is much room for improvement. Currently there are several new HPAL plants at the feasibility or financing stage. All of these have adopted one of the existing flowsheets. Most of the enhancements have focused on increasing autoclave size. It is now time to assess the success and failures of the three existing plants and incorporate this experience in a design for productivity, efficiency and reliability. Towards this end, this paper discusses aspects of flowsheet optimization, materials of construction and engineering design.

Jan 1, 2001

By E. F. Schnitzer, P. J. Wampler

During 1996 and 1997, Oregon experienced flooding on a scale not seen in many years. Some gravel pits located near rivers experienced erosion and, in several cases, breaches between the gravel pit and the river. Initial evaluation of several sites that experienced breaches indicates that impacts to the river system are complex and vary significantly from site to site. The impacts to the adjacent river system may be viewed as both positive and negative. Several floodplain-mining sites in Oregon located in areas of historic river flow have reverted to active riverbed. In many cases, state and federal fisheries biologists and university researchers see the resulting increase in channel complexity and habitat as favorable. The Oregon Department of Geology and Mineral Industries – Mined Land Reclamation Program (DOGAMI-MLR) is performing additional studies of the impacts to the off-channel areas that resulted from the 1996 floods. More data is needed to make sound floodplain decisions regarding mining.

Jan 1, 1999

By Luke Erickson

San Francisco Public Utilities Commission is planning to replace 5 miles of pipeline under San Francisco Bay. The tunnel will be constructed using an Earth Pressure Balance (EPB) TBM and will be the first TBM-driven tunnel under the Bay. The alignment passes under environmentally sensitive habitats, through interbedded layers of sands and clays, and through a buried bedrock ridge. This paper discusses the geotechnical characterization and anticipated tunneling conditions and presents the analysis of various construction methods that resulted in the selection of an EPB TBM. Considerations related to tunneling with an EPB TBM are described in detail, including ground conditioners, TBM cutterhead wear, muck control, and squeezing ground.

Jan 1, 2008

From Sept. 22-24, the Las Vegas Convention Center will be home to MinExpo 2008, the world?s largest mining equipment show that comes along once every four years. Sponsored by the National Mining Association (NMA), this year?s show is on pace to be the largest ever. Nearly 1,300 exhibitors have purchased nearly 55,700 hm2 (600,000 sq ft) of booth space. At the center of it all will be some of the most impressive mining equipment that the industry has to offer. And in the shadows of the massive haul trucks, drill rigs and bulldozers, attendees will be able to see the latest and greatest products including hand tools; the latest in automation and robotics; safety and communications equipment; longwall mining equipment; engines and parts; materials handling and processing equipment and services; pollution control equipment; reclamation equipment and services; computer applications; consulting and financial services and more. While many companies will be on hand to display the tried and true, there will also be plenty of new things to see. ?We anticipate that a whole range of new products will be introduced at the show,? the NMA said of the show that has been called the world?s richest deposit of mining technology, services and products. In addition to the show that will take place in Center Hall and North Hall of the Las Vegas Convention Center, MinExpo 2008 includes a conference program with 20 educational sessions that will tackle the most timely and pressing issues affecting the mining industry. Many of the industry?s top professionals will lead the discussions.

Jan 1, 2008

By V. L. Franzen, Z. J. Hladysz, C. A. Kliche

The Wharf Resources mine, located in the Bald Mountain Mining District approximately 6.4 km (4miles) west of Lead, South Dakota, has operated a surface gold and silver mine and heap leaching processing facility since 1983. Wharf Resources intends to mine and process gold and silver ore from the Wharf Expansion area which is located on the eastern flank of the currently permitted Foley Ridge Mine. The Trojan Pit for the Wharf Expansion area was initially designed with an overall highwall slope angle of 45o. During mine permit presubmission meetings with personnel from the SD Department of Environment and Natural Resources (SD DENR), the question arose as to whether a detailed slope stability analysis of the proposed Trojan Pit highwalls was completed to justify the 45o slope. Wharf’s response was that the highwall design was based, in part, upon studies completed in1987 on the Annie Creek and Foley Ridge Mines; and, in part, upon subsequent slope stability analyses conducted by Wharf mine personnel through 1996. It was suggested by the SD DENR that the stability study be updated to reflect structural geological conditions in the Wharf Expansion area.

Jan 1, 2000

By Verya Nasri

This paper presents analysis of damages and rehabilitation design for three major French rail-way tunnels built in mid-19th century. The La Nerthe tunnel underwent ovalization deformation with excessive displacement at the springline, and pinching and bursting of the liner bricks at the crown due to tectonic residual stresses with very high lateral earth pressure. The Saint-Louis les Aygalades tunnel invert was subjected to undulatory deformation resulting in tracks misalignment, which was caused by non-homogeneity of mechanical and hydraulic properties of the ground. The Roches de Condrieu tunnel required widening to comply with the increase in dynamic envelope of trains due to their larger cross section and higher speed. The applied rehabilitation methods and constraints of work in these busy mainline railway tunnels have been discussed in detail.

Jan 1, 2008

By Samuel A. Reipas

Introduction The ore mining industry has been successful because of technological progress and huge sums of capital investment. But new technology and plants have not come cheap. The problem now is companies will run out of money before they run out of ideas. Survival Strategies Industry survival strategies demand restructuring and new plans. Inland's prescription for the future includes: • Continued emphasis on technological improvements to upgrade pellet quality and lower costs; • Effective use of human resources resulting in employee satisfaction and improved planning and productivity; • Deliberate, well planned, and documented cost-control programs for the short- and long-term; and • Capital investments to support the first three initiatives. Technology Technological changes are not only required by the need for operational improvements, but by product quality improvement dictated by the user - usually the blast furnace operator. Established ambient measurements of pellet quality, such as tumble index, compression strength, porosity, size distribution, and chemical composition, are no longer considered meaningful in predicting pellet performance in a blast furnace. New specifications, called low temperature and intermediate temperature properties, have been recently introduced. Low temperature specifications are characterized by disintegration of pellets in the 500°C (930°F) range in the upper portion of the granular zone during the hematite-to-magnetite transformation in blast furnace stack. Intermediate temperature properties (measured by 1000°C or 1800°F) are characterized by swelling, reducibility, and compression strength after reduction, reflecting conditions in the lower portion of the granular zone of the furnace. These new parameters are being used for pellet quality evaluation at Inland, and will be introduced at its Minorca mine for more routine analysis and correlation with the pellet furnace operation. With increased emphasis on quality, effective communication between the blast furnace operator, research, and the pellet plant operator is critical. At Inland, this is accomplished through technical meetings where the opportunity is provided to solve problems, establish a common understanding on the value of quality, and develop future quality standards and programs. With the degree of sophistication in determining pellet quality as it affects blast furnace operation, the future pellet plant operator will actually be producing a custom pellet. Human Resources Technological change has been a strong point at Inland, and will continue to be. However, human resource management is equally important. Is management giving sufficient attention to employee motivation and involvement? It is a way to improve productivity, reduce costs, and enhance employee job satisfaction. The industry is beginning to understand the principles and the potential for tapping employee brainpower. The payoff can be handsome. Management has to be willing to share both information and power if participative management is to live up to its potential. It has to become more flexible and be willing to adapt to change on the human side. Management should embrace rather than fear employee involvement. Given time, joint problem solving will replace adversarial attitudes and pay dividends for both sides. Productivity and product quality will improve and new dimensions of employee job satisfaction will be achieved. But, it will not happen overnight. Attitudinal change must permeate the organization from top to bottom. This change is needed to support the working relationships and give everyone a sense of direct and meaningful involvement.

Jan 11, 1983