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By Michael G. Nelson, Hanguang Wu, V. Izaxon, Sukumar Bandopadhyay

The method of mine ventilation involving heated air, which is frequently used in mines in cold regions, does not correspond to the natural conditions prevailing in permafrost regions; it is not economical and leads to a series of complications which can be prevented or greatly reduced by lowering the temperature of the air stream entering the mine until it is equal to or very close to the temperature of the frozen ground This paper presents ventilation design approaches which can be engineered to provide the required micro-climate and thus en- sure the stability bf the ground for placer mines in permafrost. Specifically three ventilation design approaches are presented: 1) design based on minimum thermal impact; 2) design based on positive/negative heat accumulation in the existing mine airways; and 3) design based on heat exchanging devices such as thermosyphons placed above ground.

Jan 1, 1997

By A. Covelli, A. B. Cecala

Two recent US Bureau of Mines studies evaluated workers' dust exposures in automated pallet loading processes. The first study involved a Bureau designed dust control system using a push-pull ventilation technique. The unit was shown to reduce workers' dust exposures by 76% during pallet loading at a ground silica operation. A hydraulic lift table was used to automate the bag stacking process. This kept the loading height constant throughout the entire pallet loading cycle. The second study evaluated different commercial, automated-pallet loading systems. These systems automatically stack the bags onto pallets, shrink wrap the pallets, and deliver the pallets to a fork lift pickup location. Results from a ground silica evaluation site indicated respirable dust samples taken were below the Threshold Limit Value (TLV) as established by the Mine Safety and Health Administration (MSHA).

Jan 1, 1992

By Alan Weakly

The Powder River Basin (PRB) of northeastern Wyoming and south-central Montana is the largest strippable reserve of compliant coal (0.6 or less lb of sulfur per million Btu) in the United States. In mining parlance, it is the Mother Lode! Wyoming’s portion of the Basin provides one fifth of the coal produced in the United States annually, and the state has been the nation’s top coal producer for the past six years. Based on 1993 production statistics and estimated strippable compliance coal reserves, Wyoming may remain the nation’s top producer for the next 76 plus years. Past articles on the PRB have focused mainly on production. After living and working in the Basin for the past five years, I have developed an appreciation for the area and its major industry that transcends size and production data. In the fall of 1993, MINING ENGINEERING’s publisher and I decided to present a series of articles that would cover many other aspects of the Basin. Ten topics were outlined, and specific individuals, selected for their knowledge and experience, were asked to contribute articles about their specialties. Although Montana has four large mines producing coal from the PRB, this series of articles will concentrate on the Wyoming portion of the Basin.

Jan 1, 1994

By Edward J. Cording, William H. Hansmire

INTRODUCTION The Washington Metro, a rapid transit system that will serve the District of Columbia, Virginia, and Maryland, has been under construction for about two years. Construction of the Metro by the Washington Metropolitan Area Transit Authority involves a large amount of cut and cover, soil tunnel, and rock tunnel construction. To aid initial construction and improve future designs, performance observations were undertaken on tunnels in the initial construction phase. The University of Illinois Department of Civil Engineering was engaged to carry out a comprehensive program of field observations and measurements for this purpose. One part of the program was on the first soft ground tunnel constructed in the system. The tunnel is a 2200-ft (670 m) twin-bore section, designated Contract A-2, in downtown Washington. Two objectives of this program were to determine the relationship of construction procedure to settlements and to observe the pattern of soil movement around the tunnel as an aid in evaluating underpinning criteria for nearby structures. A test section, consisting t three instrument lines located across the tunnel path, was established prior to mining in Lafayette Park to measure in detail both vertical and lateral soil displacements as the tunnel was mined through the section. The site was selected because it is free from surface structures and access for installation and reading of the instruments was convenient. Load and distortion measurements on the lining were also made within the test section; observations of construction procedure were maintained throughout construction.

Jan 1, 1997

By Walter H. Schwedes

Ore grinding mills are really just slowly rotating barrels, but barrels that are growing in size so fast that the application of electric drives for them is rapidly approaching a technology like that for wind tunnels or pumped storage drives. This application is particularly worthy of care because some 40% of the 75 megawatts of power used by a large copper ore concentrator, or some 60% of the 200 megawatts supplied to a large iron ore concentrator, are for grinding. These ore plants are located where the ore is, not where a utility happens to be. So, the challenge is not only to choose a drive and .power transmission for reasonable cost, high performance, reliability and minimum maintenance, but to afford the interface between mill drive and power distribution and source systems to minimize the whole ore plant's monthly power bill, or costs of self generation. Conclusions can be reached in optimizing a drive selection only for each particular ore plant's set of parameters, but by identifying the criteria for selection and then weighting each type of drive per criteria, yardsticks for final choice become apparent. This is the purpose of this paper. Grinding action takes place inside the barrel, where the ore charge is ground with the aid of balls, or mill length rods, or large chunks of ore as in autogenous grinding.

Jan 1, 1972

By Malcolm J. McPherson, Daniel J. Brunner

This paper describes an experiment conducted to investigate the law of airflow on a mechanized longwall coal face. Background to the Square Law relating frictional pressure drop and airflow is presented and deviations from this Law are discussed. The procedures used to investigate the Law of Airflow for the longwall are described and the results are presented. The results verify the Square Law relationship for airflow along a mechanized longwall face.

Jan 1, 1987

By D. Spitty

Mining companies often have many disparate systems and repositories of data in their organization for planning and scheduling outbound mining supply chains. To optimize ore quality, throughput, transport logistics scheduling and delivery to contract, planning teams need to model and manage the value chain accurately and achieve a consolidated, enterprise view of operational performance. Planning teams coordinate a complex series of activities to ensure production forecast accuracy. They also negotiate and execute complex contracts often with disconnected and limited visibility of production forecasts, quality, and variability with little ability to accurately market potential product specifications over longer time horizons. This market is becoming increasingly dynamic, with increasing variability and the time for planning teams to react is decreasing. This is driving the need towards using science to generate the necessary scenarios required to support the decisions made by planners on a frequent basis. Resource-to-Market is a highly flexible, user-configurable supply chain management system for the mining and metal processing industries. This provides an integrated view of the supply chain that supports the dynamic nature of planning in a mining company, embraces variability of elements across the supply chain with the ability to optimize across all the functional areas of the operation to enable optimal decision making for often competing objectives such as throughput, quality, cost, revenue and profit.

Feb 23, 2014

By Rosario Lunar, Jesús Martínez-Frías, Egidio Marino, Trinidad Torres, Jose E. Ortiz, Juan A. Martín-Rubí, Luis Somoza, Ricardo León, Teresa Medialdea, Javier González

Seamounts, submarine banks, volcanoes and undercurrent channels are prominent geomorphic features that have become an important target for minerals research and exploration with the goal of future exploitation. Polymetallic ferromanganese deposits are common types of mineralization on these settings. Co-rich ferromanganese crusts are important as potential resources of Mn and Co, but also Ti, Ni, Tl, REEs, PGEs, and other metals. Many seamounts and channels along the Atlantic Spanish continental margin are known to hold mineral deposits but are poorly studied. This work presents and briefly describes the most recent activities of the Spanish Geological Survey (IGME) on exploration and investigation of ferromanganese deposits along the Atlantic Spanish continental margin. Different submarine areas from the northwestern margin of the Iberian Peninsula to the west off Canary Islands have been surveyed by geophysical, sampling and underwater observations from 89 to 4000 m water depth. The mineral deposits cover a large diversity of submarine geological and geomorphical features: mud volcanoes and diapirs related to hydrocarbon seeps, seamounts associated with hot spot volcanism, hydrothermal vents in active magmatic volcanoes, structural basement highs and banks or contourite channels. Considering the collected dataset, we present the preliminary results of the study of these mineral deposits, including ferromanganese nodules and crusts and phosphate pavements and nodules, which can be considered as potential sources of raw materials.

Sep 1, 2014

By M. S. Klima

This paper will detail the work that has been done in 1990 and 1991 at the Pittsburgh Energy Technology Center (PETC) on the development of the U.S. Department of Energy's (DOE) patented Micro-Mag Process. This process entails the use of a micronized-magnetite (minus-10 microns) and water mixture for cleaning fine coal (minus-600 microns) in a cyclone, along with the production and recovery of the magnetite. Emphasis will be on the results from micronized-magnetite recovery testing using both conventional wet-drum and high-gradient magnetic separators in which several key operating conditions were varied including feed percent solids, magnetite-to-coal ratio, magnetite grade, and feed rate. Also presented will be selected results from testing done on a 76-mm diameter cyclone at a relative density of 1.50 showing the effects of operating pressure, magnetite grade, and medium-to-coal ratio on separation efficiency. In addition, two methods for producing micronized magnetite, along with the corresponding size distributions, will also be discussed.

Jan 1, 1992

By Lisa A. Banick, Robert A. Rubin

The lawyer's role in underground construction, certainly for the past 20 years, has been principally that of the advocate in disputes resolution. Disputes in underground construction have been steadily increasing, making the lawyer a more prominent participant in the underground construction process. It is widely believed, however, that this is not a salutory state of affairs. It is our thesis that lawyers ought not be eliminated from the process, but rather that their role should be changed. They should function as prophylactics rather than as swords, i.e., they should be used to prevent or reduce disputes rather than, after the fact, to champion their clients' causes. a. Mr. Rubin is a partner in the New York law firm of Postner & Rubin. He has litigated and arbitrated numerous complex construction disputes. He has also participated in efforts to improve contracting practices on committees of ASCE and the National Academy of Engineering. b. Ms. Banick holds a BS in Civil Engineering from the University of Virginia and is a law student at New York Law School. She is a law clerk at Postner & Rubin.

Jan 1, 1983

By D. L. Romero

The Line Creek Mine is operated by Crows Nest Resources Limited, a wholly owned subsidiary of Shell Canada Resources Limited. It is located approximately 25 km north of Sparwood in southeast British Columbia (refer to figure 1). The Line Creek coal deposit is part of the Upper Elk Coalfield in the East Kootenays. The coal is a medium volatile, low sulfur, bituminous coal and is used as a coking coal. Coal close to the outcrop is typically of low F.S.I. and is processed for thermal use. The present pits have a total coal reserve of 30 million clean tonnes and is a multi-bench, open-pit operation. The coal is recovered by front shovel and backhoe combination, and hauled to the plant with a fleet of 120-tonne and 40-tonne capacity trucks. Line Creek is unique in that it can simultaneously treat both metallurgical and thermal coal in separate processing facilities (refer to figure 2). Run-of-mine coal is delivered to the truck dump. The plus 50 mm material is scalped off and reduced to minus 50 mm in two rotary breakers. The raw coal is then conveyed to one of five, 5000-tonne capacity, silos. Typically one silo is used for thermal coal and four for metallurgical coal (refer to figure 3).

Jan 1, 1991

By Michael Gay, W. H. Hansmire, G. Rippentrop, V. S. Romero

The new Tren Urbano heavy rail transit project in San Juan, Puerto Rico has one very significant part, the Río Piedras Contract, being constructed underground. This paper will give an overview of the tunneling work that started construction in1997. Design-Build procurement for tunneling is addressed. The new and modern transit system in San Juan will be 17.2 km (10.7 mi)long and have 16 stations in its first segment of construction, which is due to open in 2001. The line connects the city center district of Santurce to the outlying suburban municipality of Bayamón. All construction is being done under design-build contracts as a demonstration project funded by the Commonwealth of Puerto Rico and the Federal Transit Administration (FTA). The Río Piedras Contract is completely underground and involves practically all types of construction in soft ground. One station is built as cut-and-cover at the University of Puerto Rico. One portion has twin tunnels to be driven with an Earth Pressure Balance Machine (EPBM) and lined with one-pass precast concrete segments. Another has four short tunnel drives at a turnout that will be constructed with an initial support of shotcrete and lattice girders (i.e., the New Austrian Tunneling Method of construction). The most complex construction is the Río Piedras Station, which is being built as a stacked drift with a total of 15 individual tunnel drifts. After being sequentially excavated and concreted, they will form the arch of the 19 m (62 ft.) wide by 16 m (53 ft.) high cavern station. This structure is excavated in soil with less than 5 m (16 ft.) of cover to overlying historic buildings.

Jan 1, 1999

By J. H. Dietz

The electric assist option for diesel-electric trucks can improve truck productivity while maintaining the inherent flexibility of a truck and shovel operation. In addition, the resulting cost reductions offer a rapid investment payback for many mine situations. A review of the present technology and performance experiences verify the projected benefits in productivity and operating cost. New technologies can further improve the productivity/cost scenario.

Jan 1, 1984

By Ralph P. Hackl

Biooxidation processes for treating arsenical and other types of refractory gold ores are touted by many as being simple, inexpensive and environmentally friendly. One of the advantages claimed by proponents of biooxidation is that arsenic is disposed of as insoluble ferric arsenate which is suitable for long term disposal in tailings ponds. However, there is considerable controversy as to the stability of ferric arsenate with respect to re-dissolution of arsenic. In particular, there is concern that the amorphous ferric arsenate produced at low temperature is not stable, especially at the alkaline pH's required for cyanidation. There is a general lack of published information on the stability of arsenical bioleach tailings. Past work on ferric arsenate stability has usually involved purely chemical systems and the use of synthetically prepared precipitates. Upon completing the Salmita bioleach pilot plant campaign (Hackl and Wright, 1989) the author had the opportunity to test the stability of the arsenical bioleach/cyanide tailings which were produced. This paper summarizes the results of that work.

Jan 1, 1990

By L. Bernoth, I. Firth, S. Rhodes, P. McAllister

As biotechnologies emerge from laboratories into main-stream application, the benefits they offer are judged against competing technologies and business criteria. Bioremediation technologies have passed this test and are now widely used for the remediation of contaminated soils and groundwaters. Bioremediation includes several distinct techniques that are used for the treatment of excavated soil and includes other techniques that are used for in situ applications. They play an important and growing role in the mining industry, for cost-effective waste management and site remediation. Most applications have been for petroleum contaminants, but advances continue to be made in the treatment of more difficult organic and inorganic species. This paper discusses the role of biotechnologies in remediation and pollution control from a mining-industry perspective. Several case studies are presented, including the land application of oily wastewater from maintenance workshops, the composting of hydrocarbon-contaminated soils and sludges, the bioventing of hydrocarbon solvents, the intrinsic bioremediation of diesel hydrocarbons, the biotreatment of cyanide in water from a gold mine, and the removal of manganese from acidic mine drainage.

Jan 1, 2000

By Gerald H. Luttrell, Jaisen N. Kohmuench, Michael J. Mankosa

A new separator, known as the Hydrofloat cell, has been developed to overcome limitations of traditional flotation cells in recovering coarse particles. In this process, small air bubbles are introduced into a hindered "teeter" bed of fluidized solids to create light bubble-particle aggregates that can be separated based on differences in density. Laboratory tests conducted with coarse phosphate feeds indicate that the Hydrofloat cell is capable of increasing BPL recoveries by nearly 20% over conventional flotation methods. Based on these encouraging results, a pilot-scale Hydrofloat cell was fabricated and installed at a central Florida phosphate plant. Test data collected using the pilot-scale unit suggest that the BPL recovery of the plus 35 mesh plant feed can be increased by more than 40% through the application of this new technology. This improvement is particularly beneficial due to the very high grade (-73% BPL) of the plus 16 mesh particles in the Hydrofloat concentrate. This article describes the theoretical basis for the development of the Hydrofloat cell and provides an overview of recent laboratory and pilot-scale test results.

Jan 1, 1999

By G. A. Parkison

The sequential copper analysis method is a particularly useful technique to semi-quantitatively define the geologic, mineralogic, and metallurgical types and zonations commonly associated with porphyry-type copper deposits. The method is based on the partial dissolution behavior displayed by the prevalent copper minerals malachite, chrysocolla, chalcocite, and chalcopyrite to solutions containing sulfuric acid and sodium cyanide. Results from sequential analyses of the sample and analytical residue using sulfuric acid followed by sodium cyanide and then aqua regia solutions when compared with conventional total copper analyses can determine the amounts of leachable oxide minerals, leachable secondary sulfide minerals, and primary copper minerals, respectively. Sequential assay analytical results and interpretation are presented for copper deposits in Chile, Mexico, and the United States.

Jan 1, 1995

By B. Cavender

Investments in new technology are often intended to improve the production or cost performance of existing operations. The economics used to justify these projects can be flawed, however, if they do not adequately consider the potential benefits of the alternative: the fully optimized use of the facility's present equipment and personnel. While new technology can be effective, dramatic improvements in production performance can also be achieved through the rigorous application of standard industrial engineering and operations management practices. An intermediate approach may also be effective: many basic improvements in the mine or plant necessary to support new technology will be equally effective when implemented for the facility's present operators. Firms that optimize their present operations are able to save the capital and avoid the risk associated with new technology. These firms will also be able to capitalize more quickly on new technology when it is implemented.

Jan 1, 2000

By Frank X. Bellini, Marc Saidman, Allen J. Hulshizer, Anthony J. Stewart

The cooling water system for the Seabrook Nuclear Station involves 10.25 Km (33,623 ft.) of 6.7 m (22 ft.) OD hard rock tunnels, over one third of which is under and terminating over 1.6 Km (a mile) out in the Atlantic Ocean. The major excavation is accomplished by two TBM's concurrently driving the intake and discharge tunnels which by mid-January, 1981, completed 92% of the excavation. This paper presents the case history of the excavation work and describes a computer program developed to evaluate major activities of TBM excavation on a shift-by-shift basis. Details and summaries of the production efforts are computer plotted in different forms to facilitate the evaluation of production performance, trouble spots and trends.

Jan 1, 1981

By F. M. Doyle, Robert G. Robins, E. Peters

Stability diagrams for the Cu-S-H2O system have been widely applied over many years. Stability diagrams for aqueous systems generally, have been generated by computer, but with the programs for Potential-pH diagrams in particular, a common routine leads to error in multi-element systems. In this paper these errors, and some misinterpretation of diagrams are considered. In most of the published diagrams for the Cu-S-H2O system there has been no account of the sulfide complexes of copper. Here, the free energies of formation for the various species in the system have been re-evaluated for consistency, and some diagrams for the Cu-S-H2O system ( generated with the program DIASTAB Vers.5 ) are presented.

Jan 1, 1993