Search Documents

By Larry R. Powell

The Bureau of Mines, in cooperation with the Illinois Mine Subsidence Insurance Fund, is monitoring the response of two foundations to ground movements induced by subsidence from high extraction mining in southern Illinois. The objectives of the monitoring program are to study the inter- action between the ground surface and a foundation during a subsidence event and to determine the capability of the tiltmeter to detect and monitor subsidence movements. Tiltmeter data were obtained on two foundations constructed near Sesser, IL. One of the 30-by 40- ft foundations was constructed with a typical poured concrete footing, the other with a rein- forced-concrete footing poured on top of pol yethylene sheeting placed over a compacted layer of sand. Soil-filled bins were placed on the perimeters of both foundations to simulate superstructure loads. Monitoring pins and tiltplates were installed on the corners and midpoints of the footing. Additional survey points were established on the five-acre site to track the mining advance. This paper describes the monitoring instrumentation and techniques as they relate to the mining and site conditions. The capability of a tilt- meter to detect and follow the tilt of the foundations is demonstrated.

Jan 1, 1986

By William R. Yernberg

A conference on coalbed and coal mine methane was held March 27 and 28, 2000, in Denver, CO. The conference, organized by the Strategic Resource Institute, was attended by leaders in the coal mining and gas energy industry. The conference focused on the recovery of methane from coal beds as an energy resource and the removal and utilization of coal-mine methane (CMM) related to underground coal mining. The two-day conference discussed methane resources around the world, methods of recovery, methane markets, underground coal mining, health and safety issues and environmental issues related to methane. The consensus among the presenters is that the future looks promising for coal bed methane (CBM) and CMM.

Jan 1, 2000

By M. Pérez-Tello

A mathematical model to represent the expansion and fragmentation of copper matte particles oxidized under flash converting conditions is presented. The model assumes that the particles are initially nonporous, have a constant mass prior to fragmentation and travel at a constant velocity throughout the reaction chamber. The model requires the specification of the following five parameters: the particle expansion rate, a fragmentation diameter factor, a fragmentation size distribution parameter and the fractions of the finest and the coarsest particles in the feed that undergo fragmentation. The model predictions show good agreement with the experimental data collected in a laboratory furnace over a wide range of experimental conditions. The evolution of the size distribution of the particles along the reactor length was computed, and the model parameters were correlated with the experimental operating variables. Model predictions indicate that particle residence time is an important factor in the generation of dust. The presence of two maxima in the particle density function may be attributed to turbulent conditions prevailing in the furnace, which cause particles to follow different trajectories within the furnace even if they are injected at the same location.

Jan 1, 2008

By Q. J. Browne, M. A. Miller

Silver Bell produces about 22,000T of fine copper annually from low-grade chalcocite and oxidized copper ore that is recovered by sulfuric acid leaching and SX-EW processing. The current mineable reserves are 146 million short tons averaging 0.39% Cu, at a 0.15% cutoff. Silver Bell utilizes two types of mining methods to develop the low-grade reserves: (1) a conventional blast, load and haul method for run-of-mine leach ore, and (2) rubblization of material on the margins of existing pits. Rubble leach ore is blasted, terraced with a bulldozer, and leached in place. Mining and/or rubble leaching is currently active in four separate pits. Laramide-age intrusive rocks host porphyry copper mineralization at Silver Bell. Quartz monzonite porphyry dikes and stocks, mafic-poor equigranular granite (alaskite), and sub-volcanic dacite porphyry are the predominant host rocks. Most of the ore currently mined comes from near-horizontal enrichment zones containing veinlets and disseminated grains of pyrite and chalcopyrite rimmed by chalcocite. Conversion from a milling operation to a leach only operation allowed for a much lower cutoff grade than was historically used at Silver Bell. Mine geologists were able to increase copper resources by drilling exploration targets that were previously interpreted to provide lower-grade mineralization below cutoff-grade for milling. Geologic parameters that effect the distribution of rubble and mineable leach ore include: ore grade and thickness, variable alteration styles in intrusive host rocks that affect fragmentation during blasting, acid consuming carbonate wallrocks (reactive skarn) which influence leach solution pH, solution flow paths and drainage, presence of leachable oxide mineralization in non-reactive skarn, and depth to hypogene mineralization which is currently uneconomic. Geologic parameters are used to predict rubble bench limits, vary blast hole spacing for consistent fragmentation, and correct errors in mineral zone classification based solely on blast hole assays. An expansion-drilling program has identified approximately 150 million tons of new leachable copper resources with an average grade of 0.35% Cu.

Jan 1, 2002

By S. Kim Juniper

"This presentation aims to serve as a primer on conservation, research and regulatory organizations interested in the environmental impact of deep-sea mining. It will also consider a recent, early-stage proposal for an experimental SMS mining operation aimed at increasing our understanding of mining impacts and ecosystem recovery.Over the past 5 years, as deep-sea mining has been moving closer to reality, it has attracted growing attention from deep-sea biologists, conservation groups and operators of deep-sea research vehicles and observing systems. Several new international research organizations have emerged that have a direct interest in deep-sea biodiversity conservation, and the environmental impact of ocean mining. These include INDEEP, which evolved from the 10-year Census of Marine Life program, the Deep Ocean Stewardship Initiative that has recently hosted several high profile international meetings, and the VentBase forum of academics, industry and regulators that aims to develop environmental best practices and informational documents for all stakeholders involved in Seafloor Massive Sulphide (SMS) mining. InterRidge, currently hosted by China, represents a decades old partnership of deep-sea biologists and economic geologists who discovered the more than 100 known hydrothermal vent fields and SMS deposits on midocean ridges and in other settings of seafloor volcanism. In 2012 InterRidge formed an industry liaison group to examine how the mid-ocean ridge researcher community could contribute to the development of environmentally responsible practices for the exploration and exploitation of SMS deposits. While initial meetings with industry were promising, InterRidge members are currently debating the relative merits of sharing exploration know-how and understanding of vent ecosystems with industry, against the need to maintain their independence as stewards of deep-sea ecosystems."

Sep 1, 2014

By J. Hunter, E. Jackson

This paper describes work done by Placer Dome Technical Services Limited, a subsidiary of Barrick Gold, and Nautilus Minerals Inc. in support of the conceptual design of a subsea mining system. It describes an overall concept design plus specific studies into mechanical excavation at depth. The concept design includes one or more subsea excavators connected to a suction riser, which transports the cut material to a shipboard dewatering and offloading system. A multi-phase investigation was performed into the mechanical excavation of seafloor massive sulphides at depths of around 1600m. Rock samples were recovered and tested for rock properties and cutting behaviour. A small pick drum cutter was procured and tested on a representative concrete slab in a lab and tested again while submerged in a test tank. Finally the cutter was tested on a massive sulphide ore body at 1600m depth. The cutting performance results, e.g. pick forces and specific energies, should provide valuable input to the design of future full scale subsea mining systems.

Jan 1, 2007

By S. Johnson

Introduction The mining of aggregates underground has grown steadily over the last 25 years. Growth has come in both production volume and in the importance this segment of the industry is playing in the continuing supply of construction aggregate. Underground aggregate mines will continue to grow in both number of operations and complexity, as the replacement of zoned reserves in metropolitan areas becomes crucial. This growth will result in a shortage of qualified mine managers, possibly limiting the success of these facilities. The aggregate industry will have to modify current practices in order to meet the growing demand for this specialized skill. Segment Growth Underground mining for aggregates is not a new idea. Martin Marietta has been operating underground mines since 1969, and currently operates 16 underground mines ranging in size from 250,000 tpy to 2,500,000 tpy. These mines represent less than 4% of the total number of operating locations, but contributed 9% of the annual production in 2004. Though they range in size and production capacity, the importance is evident. The 2000 United States Census revealed several trends that are of interest to the aggregate mining industry. For the period 1990-2000 the U.S. population grew by 33 million or 13%. There were nine major metropolitan areas with a population of five million or more. These nine areas accounted for 30% of the total U.S. population. More significant was the fact that the population growth in these nine metro areas was 25% of the growth for the entire country. These statistics tell us that the population is expanding in these major metropolitan areas at a staggering rate. The same thing is happening to some degree in every population center. Population growth increases the demand for local aggregate while reducing the available area to mine that aggregate. The need for an economical supply of aggregate to support community expansion is a problem that will grow as older quarries are mined out and closed. This will be an issue that communities of all sizes will have to deal with. A reliable and cost effective supply of quality aggregate is crucial to support community expansion.

Jan 1, 2006

By Tim O’Neil

If you build a big truck, build a big tire to match it. Let that haulage synergy aid the economics, productivity and lessened maintenance for the unit. Now, Cater-pillar and Michelin have done just that. Discussions began in 1996. Caterpillar was making plans for its 797 ultra-class haul truck. The development team realized the need for a tire that could withstand extreme loads. The 797 would weigh 558 t (615 st) and be capable of 64 km/h (40 mph) speeds. So Caterpillar approached Michelin. The two companies realized the benefits of jointly developing a tire for the 797.

Jan 1, 2002

By R. Owen, T. Canty, C. Marks

The industrial vision system provides on-line 2D particle size analysis for aggregate slurries in both the overflow and underflow of hydrocyclones. This paper covers required vision system features allowing CCD cameras to function in the harsh environment of a mine milling area. The study conducted demonstrates the system’s capacity to obtain particle size distributions for controlling hydrocyclonic separators. The particle size distribution is obtained within seconds and immediately updated to allow for process adjustments. Results are then provided as a graphical computer generated display or output as a 4-20mA current loop for process control. The primary use of the vision system is in classifying particles in cyclone overflows which are often a few microns in size. Typical size information for actual mine slurry samples are presented and possible control schemes discussed.

Jan 1, 2002

By R. Abel, T. Wildeman, N. Heflin

A study was conducted to assess environmental effects of waste rock piles on water in the Russell Gulch area. Each pile was rated on physical characteristics of proximity to an ephemeral gulch, extensiveness of erosion features, size, presence of vegetation, and presence of a kill zone. Chemical assessments focused on three leachate tests performed on waste rock samples. Ratings were based on pH, conductivity, acidity, and analysis for 31 metals using inductively coupled plasma emission spectroscopy. The chemical and physical assessment of each site is used to make a rating of each pile on its overall potential to deliver contaminants.

Jan 1, 2004

By Pratoomkhuan N. Lertsgoon

A large underground cavern with dimensions of 25m × 175m × 49m (W×L×H) was excavated in sandstone and siltstone to house 4 units of hydropower generator and was completed in 2000. In feasibility study stage, the property of the siltstone which governs the ceiling of the cavern was questionable due to slaking phenomenon. Parameters on rock properties for design were back calculated from actual ground response measured from a trial excavation. For safety of construction, comparison between prediction and actual ground responses during excavation had proceeded. The prediction was provided by means of PHASES and PHASE2 software and the actual rock response was detected by the provided monitoring system.

Jan 1, 2003

GE Industrial Systems has received a multimillion dollar contract from Bucyrus International to supply complete electrical systems for three new draglines. These machines will be installed at Coal India’s Northern Coalfields’ Dudhichua and Nigahi open cast mines. The Dudhichua and Nigahi mines are located south of Varanasi. They produce Type C and Type E coal for use in the region’s super-thermal power stations. The GE systems will power and control the drag, hoist and swing motions of one Bucyrus W2000 walking dragline at Dudhichua and two a Nigahi.

Jan 1, 2000

By William H. Dresher

Introduction A subject long debated but rarely resolved involves the interaction between the academic community and industry in the sponsorship and conduct of research. The subject is, unfortunately, too often treated as a controversy involving ethics and the profit motive. But, in fact, the two branches of society - industry and academia - are necessarily part of the same system. In the last 25 years, the realization has developed that research alone is not sufficient to bring about use of those results to benefit society through productivity gains and economic growth. The flow of events shown in Fig. 1 was generally believed to be the steps required for reaping the benefits of research. Today, research still has the very important role of creating new information or new ideas. However, it is recognized to be but one of many steps in a process that we now refer to as technological innovation. Charpie (1967) said, "Technological innovation is the driving force behind economic growth in the US. In this context, innovation means the process by which a new idea is successfully translated into economic impact within our own society, by providing better products, and simultaneously creating new jobs in the manufacturing of those products. Only after an investigation is put into sufficient use to have an economic effect, is it termed an innovation." One of the best depictions of the technological innovation process is shown in Figs. 2 and 3. These are adapted from Haeffner (1975), and modified by the Committee on Mineral Technology of the National Research Council (1981). Figure 2 identifies the many steps involved in the process. It designates a generalized form for interaction between the academic community and industry. Figure 3 identifies the steps in the "innovation activity" box of Fig. 2. Academia is generally responsible for developing of new knowledge and ideas, as well as maintaining and enlarging the collected body of scientific knowledge. Industry is responsible for developing new products, methods, and processes. Both institutions operate for the benefit of society, but under different driving forces. In academia, the driving force is the achievement of academic excellence. In industry, the driving

Jan 10, 1984

By Miles T. Stephens, Felipe Calizaya, Jacob O. Kingston

Currently, the Bear Canyon Mine is facing the challenge of excessively high coal and rock temperatures in one of its headings. In Mine No.3, the air temperature at the 6th Right panel reached 36.4ºC and the coal 83.9 ºC. Due to these severe work conditions, the mining plan has been altered by changing the mine direction to avoid the high temperatures. To investigate the problem, drill holes were developed from the entries and the rock temperatures monitored using K-type thermocouples. The measurements confirmed the existence of localized “hot spots” in the mine. This paper presents a summary of ventilation surveys that were conducted in this mine. It includes the results of coal and rock temperature measurements from drill holes, interpretation of results using a heat flow simulator and the identification of hot spot areas. It also includes a summary of methods that were developed to reduce the hazard and control the problem.

Jan 1, 2005

By R. D. Peterson

As underground mine operations expand, the ventilation systems supporting them become complex. Complexity increases with periodic ventilation changes. New diagonal connections require a rebalance of resistance to maintain airflow in affected splits in the system. Incidents of mine fires and explosions have occurred in U.S. coal mines when diagonal connections resulting from ventilation changes have resulted in changing airflow directions. MSHA regulations prohibit the reversal of airflow and poor ventilation practice in general, but regulations cannot stipulate or recommend proactive preventative measures because every situation is different. This paper discusses the phenomenon of diagonal branches and recommends practical precautionary measures that can be taken to prevent airflow reversal in planned ventilation changes.

Jan 1, 2012

By Leon Maday, Dan L. Pecha, Jeremy Johnson, Daniel N. Adams

The Brightwater conveyance system includes 26 km of tunnels, a 130 mgd pump station, 2 km of micro tunnels, and a 2.4 km outfall. The tunnels extend from Woodinville to Puget Sound through varying soils in 1 to 7 bars of hydrostatic pressure and depths to 185 m. The tunnel diameters range from 4 to 6 m and include numerous lining systems. This paper highlights major shaft and tunnel design, including dual cellshafts, multiple pipe configuration tunnels, polymer concrete segments, and the use of a one pass lining designed to convey high pressure effluent.

Jan 1, 2005

Nuclear power currently produces about 20% of the electricity in the US, with 104 nuclear power plants located in 31 states. The commercial US nuclear industry contributes over $4 billion annually to US workers in salaries and wages. 25,000 new jobs need to be filled in the next 5 years. There are over 30 new power plants under consideration by US utilities. The operating reactors use uranium oxide fuel enriched to about 4% U235 and fission is the process used to generate heat to form steam to drive the turbine generators. Nuclear energy is an important element in the US generation portfolio and represents the largest producer of nearly emission-free electricity. Most, if not all, of the operating plants will secure an extended 20 years of operation or more. The last plant constructed was ordered in 1978. New smaller, modular reactors are under design to provide less expensive, expandable generation options.

Jan 1, 2011

By D. Nutakor

The ability of computers to create synthetic representations of the real world in virtual reality offers a number of opportunities to enhance training methods used in the mining industry. Unfortunately, the training effectiveness of virtual reality systems currently used in the mining industry has received only limited testing. Miner Simulation (MinerSIM), an augmented reality system with integrated hypermedia suitable for training underground miners in the basics of using a jackleg drill to install rock bolts in a virtual mine environment is in its evaluation process at the University of Missouri-Rolla Experimental Mine. This paper discusses evaluation methodologies of the MinerSIM system, which consists of experimental and control groups with control students learning via traditional lecture and text formats. Preliminary results from usability tests of the first part of MinerSim, which is an online tutorial on underground rock bolting, are presented.

Jan 1, 2008

By S. Yerel

In a mineral processing plant, the determination of a preventive maintenance schedule is one of the most important maintenance policies. In this study, to determine the preventive maintenance schedule for the Emet Colemanite Mineral Processing Plant in Turkey, a mean quality control chart was constructed using the historical concentrate B2O3 grade data. The effect of preventive maintenance scheduling on B2O3 grades was monitored using the mean quality control chart. It was determined that recovery increased after each preventive maintenance scheduling. Close examination of the mean quality control charts indicated that there were three periods that showed different grade characteristics. These were identified as the period ?prior to preventive maintenance,? the period ?after preventive maintenance? and the period ?requiring preventive maintenance.? These periods were compared as two independent samples by using the Kolmogorov-Smirnov test. Application of this test for interpretation of the mean quality control chart enabled the authors to analyze the system effectively, and it showed that the preventive maintenance for this plant should be scheduled at four-month intervals.

Jan 1, 2007

By R. J. Snoby, M. A. Short, A. Jungmann

In processing coal, the low concentrate value requires high capacity production and sharp classification/separation techniques to reduce specific production costs. The allflux separator meets these criteria with a unique two-stage design. Through a combination of rising current and fluidized bed technologies, the allflux has extended the state of the art by expanding the particle size range that can be efficiently processed. Using concepts that have proven successful in processing concrete sands, small-scale industrial testing with coal feed stocks looks very promising. Attractive applications for the allflux are projected in fine coal recovery from old settling ponds or as a retrofit in existing fines circuits.

Jan 1, 2001