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By Jan K. Wolski

The PC computer program PCVENT, version 3.3, for the ventilation network analysis now incorporates a real-time fire simulator. Position of the fire or a source of contamination and the character of the event are input from the keyboard. There are several options of type of fire: heat only, contaminant only, or both with a constant burning rate or with oxygen as the only limiting factor. Airway resistances or fan characteristics can be modified during a fire simulation. This allows testing of various fire suppression strategies. Program application in the analysis of a real mine fire is presented.

Jan 1, 1991

By K. N. Han, Y. Guan

The dissolution behavior of silver and copper from silver/copper alloys in ammoniacal solutions was investigated using a rotating disc. Oxygen was used as an oxidant. The effects of the alloy composition, concentration of lixiviants, stirring speed and temperature on the overall dissolution kinetics were studied. Three silver/copper alloys (containing 76.7, 46.9 and 24.1% silver) were used in this study. The rates of dissolution for these alloys were compared to that of pure silver and copper under the same testing conditions. Emphasis was given to the galvanic effect on the overall dissolution rates.

Jan 1, 1995

By C. E. Jordan, B. J. Scheiner

The Bureau of Mines has developed a continuous ultrasonic flotation cell for the recovery of Florida phosphate ore. Within a small mixing chamber near the bottom of the flotation cell, an ultrasonic probe agitates an injected mixture of air, water, and phosphate ore and breaks the air into fine bubbles. Phosphate particles are preferentially attached to these fine bubbles and floated in the main chamber of the flotation cell. Over 94 pct of the phosphate was recovered, resulting in a 30 pct P205 concentrate. The ultrasonic energy consumption was less than 7 kW.h/mt of phosphate ore.

Jan 1, 1989

By D. R. Schmitt, B. L. Jensen, T. J. Ahrens, C. L. Smither

The in situ elastic moduli of rock are measured holographically by a borehole instrument in marble and oil shale. A point force induced displacement field is recorded with double expo- sure holography. Data consists of a fringe pat- tern on the viewed hologram. The elastic moduli are determined by modelling of the fringe pattern. Only Young's inodulus is fairly constrained by the present data reduction. For an applied force of 520 [ ] 50 Newtons, a marble was found to have a Young's modulus of 56 [ ] 8 GPa, near an ultrasonically determined value of 48 [ ] 6 GPa. In an oil shale, an applied force of [ ]

Jan 1, 1986

By Tim Wolf, Barry Fink

Mine site managers reported occurrences of locking assembly bolt failures on the Enlow Fork Coal Mine's slope belt conveyor. The observations were made after a number of years of operation and raised questions as to the status of the assemblies in operation. These questions prompted a detailed review of the situation by independent consultants. Using operational history of the conveyor and confirmation of belt loads by static and dynamic methods, a locking assembly fatigue curve was created to suggest expected service life. From this work, suggestions were made to modify the pulley assemblies for extended service life.

Jan 1, 2002

By F. F. Aplan, D. D. Xu

A novel system for the depression of pyrite and the ash-forming minerals has been developed. A metal ion, including but not restricted to Fe+2, is added to form a hydroxide coating on the pyrite or ash-forming minerals. A polymeric depressant is then added to attach to these re- surfaced minerals. Nearly 200flotation tests with I1 different coals indicate the effectiveness of this system. Many of the important process variables such as the coal source, frother- collector system. grind size and procedure, pH, metal ion, and depressant type and concentration have been studied.

Jan 1, 1995

By F. L. Pirkle, D. A. Podmeyer

The mineral zircon is mined for use as specialty foundry sands, abrasives, ores of Zr02 and zirco¬nium metal, refractories and zirconium chemicals. It is produced as one of several products from heavy-mineral sand deposits associated with ancient shorelines. Because of its low coefficient of thermal expansion, its high melting point, its high refractive index and its chemical inertness, it is an attractive refractory material. Zircon varies from deposit to deposit in terms of grain size, grain shape and chemical purity. Thus, there is a wide range of commercial zircon products that differ in impurity levels, particle shapes and grain sizes.

Jan 1, 1993

By James Lonergan

This paper describes the application of the Graphics Assisted Under Ground Engineering (GAUGE) software to a 2-layered room and pillar hard rock mine. The graphics- assisted mine modeling and mine planning capabilities of GAUGE are demonstrated. The system uses polygons to model the room and pillar mine design and displays the model in plan view on the graphics screen,. The planning engineer interactively specifies areas to be mined in the medium or long term. The system calculates and accumulates tonnages and grades for the user-specified areas based on the layer being mined and the particular unit operation (drifting, widening or benching).

Jan 1, 1989

By Dave Willis

In ME'S 1994 Powder River Basin (PRB) coal transportation article, the lead author described some destinations pursued by the railroads. As with many destinations, though, they turned out to be merely stops on the way to places that have yet to be reached. Along the way, the railroads discovered that making it better is a continuous process, not just something done in several phases. This was always known but not at the awareness level that exists in 1998 railroad environments. This update of the 1994 article includes railroad companies' plans for the future of rail transportation in the PRB.

Jan 1, 1998

By Dwayne K. Rowlett

A lysimeter designed to measure suction and collect a pore water sample from unsaturated waste rock has been developed and its performance has been verified in two large scale column tests. The test columns were constructed to bracket the envelope of grainsize curves for waste rock from Northern Saskatchewan. The suction profile within the columns was measured under a series of infiltration rates using tensiometers and these were compared to the lysimeter readings. The rate at which pore water samples could be collected was also measured under each infiltration rate. Lysimeter measurements of suction were found to be slightly lower than the tensiometers.

Jan 1, 2000

By William C. Beebe, Russell E. Martin

An account of driving and concreting two 900 m railroad tunnels for the Denver and Rio Grande Western Railroad under emergency conditions. Details the importance of on-site decision making by the Owner in completing the project successfully in record time. A general description of the geology and construction methods. The Thistle Drainage Tunnel drained water impounded behind the Thistle slide and serves as permanent diversion of the Spanish Fork River and Thistle Creek around the slide area. The project involved 684 meters of 5 m horseshoe tunnel, a 5 m diameter raised shaft and 23,000 cm of cut excavation.

Jan 1, 1985

By J. E. Hoffman, Corby G. Anderson, T. J. Keefe, O&apos, Suzzann M. Nordwick

Antimony removal has become necessary as it is commonly found in precious metal refractory ore bodies. The Sunshine Mine in Kellogg, Idaho has recovered metallic electrowon antimony from its argentiferous tetrahedrite (Cu2S'Sb2S3) deposits for over fifty years. Recently, Sunshine conducted an intense research effort to improve and modernize its antimony facility. This paper presents information which was learned about the antimony electrowinning processes and the development of a single¬-electrolyte antimony electrowinning technology. The relevant effects of process variables were investigated. The research results and the relevant chemistries involved in metallic antimony electrowinning will be discussed.

Jan 1, 1993

By Sharad Mathur

The purpose of this paper is to present the benefits of high reactivity meta kaolin (HRM) in high performance cement-based systems. HRM, unlike other pozzolans, is manufactured from selected naturally occurring kaolin ore and carefully processed under stringent conditions to result in a consistent product with highly pozzolanic properties. HRM is an ultrafine pozzolan that enhances the mechanical properties (workability and strength) and chemical stability (durability) of Portland cement concrete and cement-based products. HRM is unique with respect to its white color which makes it an ideal choice for architectural applications where visual and aesthetic concerns are critical.

Jan 1, 2003

By Jiro Yamatomi, Susumu Takemura, Osam Sakai, Hiroshi Shimotori, Yoshio Otsuka

The Toyoha Mine is operated under extremely high rock temperature. The geothermal heat is 10 to 20 times more active than the average of the Japanese Islands. The highest temperature ever observed in exploration drill holes is 242°C that must be equivalent to those of the geothermal fluids utilized for power generation in Japan. In order to improve the underground climate, the mine has a plan to introduce paste backfilling and to effectively reduce the heat flows from the mined out stopes. The surface flow test was carried and the second test is being arranged in underground.

Jan 1, 2001

By Scott Stebbins

Cost estimating and economic evaluation software provide evaluators with the ability to predict the profit potentials associated with mine design alternatives even during project exploration and prefeasibility. Examining a multitude of development alternatives early on serves to identify aspects critical to profitability and to increase the reliability of economic projections. A case history illustrates how Sherpa Cost Estimating Software, when used in conjunction with Apex Software for Economic Evaluation, significantly enhances an evaluator's ability to examine design alternatives in a timely and reliable manner. The costs and economic impacts associated with various access routes, production rates, equipment mixes, and stoping methods are projected.

Jan 1, 2002

Conventional logging tools such as density, neutron, and acoustic have ranges of investigation of tens of centimeters. The borehole gravimeter, however, has a range up to hundreds of meters. For example, from the center of a cylindrical ore body 0.20 g/cm3 denser than its surroundings, one can detect the boundary of the ore body at a radius as large as five times its height. More complex structures can be investigated with computer programs. We can predict the usefulness of proposed gravity surveys, or decide which suggested structure is most likely to have caused the results of existing surveys.

Jan 1, 1988

By Richard H. Sailors

Data from full scale marked ball tests are used to demonstrate the effects of abrasion, corrosion, and impact on overall wear rate. The predominate wear mechanism need be identified before the optimum alloy can be chosen for the grinding media. Use of high chromium grinding media often results in increased mill efficiency due to shape retention. Thus, a benefit from energy savings can result as well as a reduction in wear rate. Converting from steel to east high chromium grinding media requires close association and cooperation between producer and consumer in order to properly conduct these studies.

Jan 1, 1990

By Terry Ritzel

Predictive maintenance technologies include vibration analysis, tribology, infrared thermography, ultrasonic detection and electrical measurements. These technologies have been applied to large electric mining shovels at the Cyprus Sierrita Mine outside of Tucson, AZ. The predictive maintenance program was initiated on the P&H models 2300 and 4100 electric shovels during August 1996. Results of these technologies have shown the potential for improving electric min- ing shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition-based planning of component replacement. Maintenance costs are minimized by focusing resources through condition-based prioritization.

Jan 1, 1997

By J. Michael Howard

Holes cored through the Prairie Creek lamproite volcanic complex at the Crater of Diamonds State Park by companies interested in the site's commercial diamond potential give an opportunity to redefine the size and shape of the Prairie Creek pipe. Relationships of cored rock sequences and the discovery of a previously unrecognized major rock type allow a reinterpretation of the sequence and type of intrusive activity. Trench sampling of diamondiferous rock units yielded a diamond content far below what was anticipated based on an estimate from historical records. Inadequacies of shallow bulk-testing methods for a diamondiferous pipe are examined.

Jan 1, 1999

By E. Sehner, G. Van Weert

Metal chloride pyrohydrolysis is a fifty year old technology, operating satisfactory in many plants around the world, mainly on ferrous chloride, The capabilities and costs of its two equipment options (spray roaster and fluid bed pyrohydrolysis) are well known. Why is the technology not more widely used in mineral processing, beyond the production of MgO and upgraded TiO2slag? After briefly reviewing chloride vs. sulphate process characteristics and existing plant operations, this paper will discuss pyrohydrolysis options for the mine developer using the processing of ilmenite, siliceous zinc oxides and oxidic nickel / cobalt ores as examples.

Jan 1, 2003