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By Peter Cain

Longwall extraction in the Phalen Scam in the Sydney Coalfield of Nova Scotia is carried out under flooded abandoned workings in the Harbour Seam 140 m above, and at depth of up to 700 m beneath the Atlantic Ocean. Careful planning of panel and pillar dimensions is necessary to prevent inflows from the overlying workings and to prevent the development of excessive subsidence strains at the seabed. This paper briefly summarises the research undertaken over the past five years by CBDC and CBCRL into the problems associated with mining under water, and then describes the development and application of a design/planning code of practice developed jointly by CBDC, CBCRL and mine regulatory agencies. The design method employed in the Code of Practise is based on empirical data from the coalfield and parameters developed from subsidence modelling and previous water inflow experience. It includes precautionary measures to be adopted during development and mining, and monitoring procedures to be followed. It is flexible enough to allow future developments in the understanding of inflow mechanisms to be incoporated without major modifications, and represents a major step forward in reducing the potential hazards associated with coal extraction in the coalfield.

Jan 1, 1996

By K. L. Paciorek

The primary objective of this program was to determine the toxic fume and fire hazard of elastomeric noise abatement materials with a limited effort expended on the evaluation of specific treatments applied to mine timbers. Under the conditions employed, for a dimethyl silicone rubber, formaldehyde presented the major toxic threat; acrolein was the main toxic species for both polyester and polyether urethanes and an acrylonitrile-butadiene-styrene resin; in the case of flame-retardant styrene-butadiene rubber compositions, hydrogen chloride, and in the case of PFA-treated timber, furfural, were the major toxic compounds. Of the materials studied, the flame-retardant styrene-butadiene rubbers presented the greatest toxic hazard. The generated data have been reduced to toxic load tabulations amenable to employment for potential hazard assessment.

Jan 1, 1982

By R. J. Sweigard, R. V. Ramani

G.F. Learning The paper by R.V. Ramani and R.J. Sweigard is a wonderful description of the labyrinthine web that has been spun about the mining industry by energetic bureaucrats and politicians over the past 50 years. The remedy for the problem, however, is not more of the same, but less. That may be difficult for the industry to achieve, for it is not a technical solution but a political one. And the current fervor for more detailed planning at all levels of government and private enterprise has become deeply ingrained. The authors recommend the provision of more information about mining and mineral resources to "macro" (i.e., government) land use planners. They apparently overlook, however, the already strong tendency on the part of most government land use planners to consider themselves omniscient. Thus, giving them more information about the technical problems of mining will only make them want to get more and more involved in the "micro" (private, site specific) mine development and production plans of the individual mining firm. In fact, this has already happened at all levels of jurisdiction from municipal to federal government. Examples are legion. The most effective way to ameliorate the adverse impacts of government land use planning on existing and potential mining operations is to: (1) introduce greater flexibility in the definition of land use zones by local and state governments; (2) adopt realistic and relevant ambient environmental performance standards in governing relationships between mineral land uses and concurrent or subsequent nonmining land uses; (3) allow greater leeway for economic considerations in land use decisions in contrast to the explicit legalistic approach now in vogue; (4) recognize that all minerals are not the same and that sand and gravel mining should not be treated the same as underground metal mining, coal stripping, oil field production, or in situ leaching; and (5) eliminate the notion that mining operators should be responsible for determining in detail the use of land by subsequent owners of mined land. This last bit of conventional ethic really makes no more sense than requiring the builders of every shopping center or government office complex to provide detailed plans for the use of that land when its use for shopping or government is ended. Did the builder of Ebbetts Field plan for Brooklyn after the Dodgers went to Los Angeles? Should the developer of the Bingham Pit plan for suburban Salt Lake City after the copper mining goes to Chile? The nation's mining industry must address these questions before further bankrupting itself to provide more data to planners and spending thousands of dollars per acre to create land that when reclaimed is worth only a few hundred dollars per acre. Reply by R.V. Ramani and R.J. Sweigard We thank Mr. Leaming for his valuable contribution. His views on the problems of land use planning and mineral resources are most welcome additions to our paper. As the title indicates, our paper was more concerned with the impacts of land use planning on mineral resource conservation than with the details of the planning process. On the whole, his five recommendations would be helpful for mineral resource conservation. However, we would suggest that the argument he presents for his final recommendation does not address the differences between mining as a land use and commercial or institutional uses. We believe that this difference is the crux of the issue. We share Mr. Leaming's desire to ameliorate the adverse impacts of land use planning. Possibly the most detrimental impact is the loss of mineral resources. Any development, whether mineral or community, that does not give proper consideration to other resources can result in permanent loss or sterilization of resources. With proper planning, some of these losses can be avoided. As our paper indicated, one factor that limits the consideration of mineral resources, and ultimately leads to their sterilization, is the generally inadequate levels of resource characterization and understanding of the unique nature of mineral resources and mining operations. The last point raised by Mr. Leaming is also important. In terms of reclamation and land use planning in mining districts, we certainly do not advocate spending more than what the results are worth. The main thrust of the paper was to explore the avenues for conserving the mineral resources so that, at some appropriate time, the issue of mining and reclamation can still be addressed.

Jan 4, 1985

By S. Erçayhan, B. Derin, O. Yücel

In the present study, the production of low carbon ferrochromium (LC-FeCr) from chromite concentrates containing 55.09% Cr2O3 and 13.06% Fe via metallothermic process was investigated. For this aim, in the experiments, the aluminothermic reduction method was applied in an open crucible. 10% CrO3 + 10% NaClO3, 15% CrO3 + 5% NaClO3 and 20% CrO3 by weight of concentrate were added to the charge, respectively and the charge was reduced with aluminium. The experiments were done with the additions of 90, 100, 110, 120 and 130% of stoichiometric requirement of aluminium. The highest Cr content in alloys was found as 71.7% at 120% of stoichiometric Al whereas the highest Cr recovery in alloys was found as 71.8% at 130% of stoichiometric Al when the both charge contained 15% CrO3 + 5% NaClO3 by weight of chromite concentrate.

Jan 1, 2004

By W. H. Oppelt

A lignite from west-central North Dakota (Mercer County) was dried by the Bureau of Mines by the Fleissner process at saturated steam pressures to 1,500 pounds per square inch absolute (p.s.i.a.). Normally, the process is operated at pressures of 200 to 370 p.s.i.a. At the highest pressure the temperature of the saturated stearn is 596° F. The purpose of the investigation was to evaluate the influence of very high stearn pressure and temperature on moisture removal, steam consumption, and physical and chemical characteristics of the dried lignite. Two drying cycles were used: A normal cycle, corresponding to previously established standard time requirements, and an accelerated cycle, wherein time requirements were determined by boiler capacity and handling speed. Blank tests to determine stearn requirements for heating the empty autoclave were performed for each cycle and each test condition. Moisture removal, final moisture content, net steam consumption, and size stability of the dried lignite were determined.

Jan 1, 1959

By H. H. Murray

Clay minerals are one of the more important industrial minerals. They are used in many products and because of different specifications may require special processing which can be either wet or dry. The clays discussed are bentonites, kaolins including ball clays, and palygorskite (attapulgite). In order to design a process flow sheet for these clay minerals, the physical, chemical, mineralogical, and optical properties need to be evaluated. Each species of clay minerals require a group of special tests which are described in this paper.

Jan 1, 2009

By Pengfu Tan

The control of converter slag chemistry and slag viscosity has played an important role in optimizing converter operations. A thermodynamic model of copper P-S converter and a viscosity model of converter slag have been used to predict the chemistry and viscosity of converter slag. The effect of oxygen potential, SiO2/Fe in slag, detection of slag blow endpoint, and temperature on slag viscosity, liquidus temperature of converter slag and skimming operation has been discussed. Some applications of the industrial operations have been presented.

Jan 1, 2006

By Karl E. Burgher

Since World War II, the need for the use of explosives with testing, construction, demolition, mining and quarrying near urban areas has increased dramatically. Once remote, testing areas have been encroached upon by commercial and residential areas. Evidence has been found that overpressure levels near these areas can be estimated using meteorological conditions. This paper reviews a study where 205 test shots were fired, meteorological conditions recorded, and over-pressure levels estimated using multiple regression techniques.

Jan 1, 1988

By M. J. Gilbey

Cross passageways between adjacent tunnels in passenger rail or transit systems may be used during train fire emergencies to evacuate passengers to points of safety in the non-incident tunnel. Rescue trains can be brought into the non-incident tunnel to remove passengers to expedite evacuation times as compared to walking along bench walls to the nearest egress stairs. In cases of multiple train emergencies, the required ventilation capacities can result in high pressure differences between the incident and non-incident tunnels. These pressure differences can make it difficult or impossible for a normal person to open doors of a cross passageway between adjacent tunnels. If opened, the velocity of the airflow through an open cross passageway can reach levels high enough to impede passenger evacuation. This paper describes the analysis of this problem for a sample rail tunnel. A ventilation concept that mitigates the problems of high cross passageway door opening forces and high velocities through open cross passageways is presented.

Jan 1, 2009

By Lane White

Refractory gold ores are those from which a significant percentage of the gold cannot be recovered by conventional cyanidation. Historically, roasting has been the primary method for rendering such ores amenable to gold extraction; however, roasting creates environmental problems that are not acceptable in many locations. During the 1980s, consistently strong gold prices drew increasing attention to refractory gold ores, and new processing schemes were commercialized, most prominently aqueous pressure oxidation and more recently bacterial oxidation. Since 1985, pressure oxidation has been incorporated into four plants processing refractory gold ores. A fifth plant is scheduled for start-up in early 1990, and three additional plants are scheduled for production before late 1992. A technical session on treatment of refractory ores was included in the program of `World Gold '89, a Gold Forum on Technology and Practices' held by SME and the AusIMM in Reno, NV, Nov. 5-8, 1989. This article summarizes material from five of the papers presented during the refractory gold session and published in the proceedings of `World Gold '89,' edited by Roshan Bhappu and Rod Harden. The complete proceedings are available from SME Publications Sales, P.O. Box 625002, Littleton, CO 80162-5002 $53.50 for members, $38.50 for student members, and $73.50 list price.

Jan 1, 1990

By Robert J. Hundhausen

This report describes Bureau of Mines investigations of a low-grade scheelite-bearing granodiorite intrusive situated on Henderson Creek, Granite County, Mont. The intrusive is in a narrow, V-shaped valley at the head of extensive placer workings. Since May 1943 the H. & R. Mines Co. of Portland, Oreg., has recovered scheelite sand and gold from the placer workings. A modified Yuba, 4?cubic foot bucket dredge was used in the operation. By February 1947 this operation had recovered and marketed over 215,000 pounds of scheelite concentrates containing 63 percent WO3. The scheelite in the placer was found to be derived principally from erosion of the granodiorite intrusive. The intrusive is one of a series of four similar, dikelike masses of granodiorite whose outcrops are aligned along a 10-mile zone of weakness trending N. 60° E. The intrusive has a triangular outcrop exposed over an area of 57 acres. Trenching and sampling by the Bureau of Mines demonstrated that scheelite is sparsely distributed throughout the granodiorite. This work delimited the outcrop of the intrusive and indicated a large submarginal reserve of low-grade tungsten mineralization. The deposit is ideally suited for exploitation by large-scale, open-pit mining operations; it would be easily available in a national emergency. Additional exploration would be necessary, however, before large-scale production plans could be made efficiently or accurately.

Jan 1, 1949

By E. Bakhtavar

All parameters influencing the decision for selection of a suitable extraction method were first selected as the base of this study. Then these parameters were categorized in two main groups. The first group of the parameters includes ?geomechanical and inherent characteristics of the dimension stones? such as hardness, RQD, compressive strength, joints plane orientation and spacing, and water content. The second group was named ?technical and economical parameters associated with the investor?s objectives? like for example extraction capacity (production rate), blocks recovery, mechanization, capital investment and operational costs. Finally, the influences of all mentioned parameters on the selection of the most applicable extraction methods have been assessed and discussed.

Jan 1, 2012

By R. S. Dean

[During the past fiscal year the Metallurgical Division has made important contributions along the lines dictated by the Bureau policy of conservation of domestic mineral resources through Its investigations include determining of fundamental data of metallurgically important materials improvement of standard ore-treatment method to eliminate waste and improve the grade or recovery of the products; and development o new metallurgical processes.]

Jan 1, 1940

By R. S. Dean

[During t!~c past f isc.~l y~:-.r the Xetzllvz-gicd 3ivi oion has made im- portant contribution-, don,- tlie lines rlictnteil by the Bureau policy of con- servation of domestic rnker~l rcsoul-ces throui;h use. During t!~c past f isc.~l y~:-.r the Xetzllvz-gicd 3ivi oion has made im- portant contribution-, don,- tlie lines rlictnteil by the Bureau policy of con- servation of domestic rnker~l rcsoul-ces throui;h use.]

Jan 1, 1940

By Jack Wasserman, Don Wasserman, Logan Mullinix, Shekhar Khanal, Kelly Neal

This paper presents current finding on truck driver average exposure to acceleration for several different manufacturer’s cab-over trucks on a variety of roads in different countries. The predominant time, for this aspect of the study has been spent in the area around London, England and Warsaw, Poland. The ECE directive 2002/44/EC has provided specific guidelines for vehicle operators 8 hour average acceleration exposure. The primary considerations have been on truck design including the air-ride driver’s seat. The truck manufacturers have produced truck cabs that have some separate suspension from the truck frame. The truck seat manufacturers have been producing air-ride suspension seats for the cab. Both of these designs have had the objective of meeting the ECE directive and providing the vehicle drivers with some degrees of comfort. This paper will provide some information on the ability of the vehicles to operate on a variety of roads and meet the objectives. Method The primary method for evaluation of the driver’s exposure has been the use of a seat pad attached to the driver’s seat. Although this sensor system provides the critical information for the driver, an understanding of the reasons for the values requires additional measurements. The initial study in England used both driver and passenger seat pads, as shown in Figure 1, as well as triaxial accelerometers mounted on the base of the seat. The latest studies used significantly more transducers to better understand the relative rotations and translations on the truck frame, the cab, and the driver. [ ]

Jan 6, 2006

By M. Li, J. D. Miller

Many technology problems must be solved if we are to continue to produce phosphate at our current rate of consumption. The U.S. produces at least 25% of the world's phosphate, 40 million tons of phosphate rock per annum with most of the production coming from Florida. Of particular concern are improved separation efficiency and the ability to treat new dolomitic resources. Phosphate flotation technology needs include: 1. Simplification of the standard flowsheet 2. Improved recovery of coarse phosphate 3. Selective flotation for phosphate recovery from dolomitic resources Preliminary results, including tests on plant feed from Florida show that these objectives may be achieved with a new collector chemistry depending on the specific circumstances. The effectiveness of the new collector chemistry has been demonstrated by the preliminary results from single stage flotation experiments both at the University of Utah laboratories and at Florida Institute of Phosphate Research (FIPR) laboratories. In the best case, from these experiments with low grade (5% P2O5) coarse feed (16x35 mesh), a single stage phosphate recovery of 95 % was achieved with a concentrate grade of 31 % P2O5. Such a separation efficiency could not be achieved using the traditional fatty acid/fuel oil collector. Based on these results it seems that a one step process may be possible for phosphate flotation and a research program is justified for the development of this new flotation strategy.

Jan 1, 2001

By Lee Browne

The transformation of Peru’s Tintaya copper project from a state-owned company to a private company is under way and the results have been successful. Since Magma Copper Co. assumed operating management in December 1994, production and costs have improved dramatically. To understand the transformation of Tintaya, the transformation of Magma Copper must also be understood.

Jan 1, 1996

By E. V. Manlapig

This review paper describes recent advances that have been made at the Julius Kruttschnitt Mineral Research Centre (JKMRC) in Brisbane in developing a framework for simulating the flotation process. The work has been carried out collaboratively with the Mineral Processing Research Unit of the University of Cape Town in South Africa (UCT), as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. The framework consists of four components, namely – the mathematical model of the flotation process, suitable measurement tools for characterising the flotation cell, a computer program for modelling and simulating the process and the plantas for testing and validating the flotation models. A brief description of the model is first presented, then a number of applications of the model are described. The paper shows how the model can be used to optimise the performance of flotation cells, and then two case studies on the modelling methodologies are described. Finally the current and future plans of the project are outlined.

Jan 1, 2001

By D. E. Walsh

With the exception of the development of large scale mining equipment (haul trucks, draglines, shovels, etc.), there are likely few other candidates responsible for the ability to exploit large tonnage, low grade deposits, than the development of large capacity comminution equipment and circuits; crushers and grinding mills. Ball mills are often the final step in the comminution process and are responsible for providing what should be the optimum particle size distribution of ore to subsequent mineral concentration steps in the flowsheet. Because comminution processes are such high cost centers for milling operations, both capital and operating costs, an enormous amount of research has been conducted to study and model their performance, in order to improve efficiencies (Kelsall, et al., 1969; Austin et al., 1984; Napier-Munn, et al., 1999; Powell and Smit, 2001). With respect to modeling ball mills, estimates of the breakage rates for individual size classes of ore particles are fundamental, as are the particle size class breakage functions (the progeny of particle sizes produced from breaking a coarser particle size class), also termed appearance functions. Fundamental research into particle breakage in tumbling mills focuses on how much energy is input into single particles versus how they break and what size distribution of particles results. Several test methods, including JKMRC?s well known dual pendulum test and drop weight test, have been developed for the breakage of coarse particles down to 6 mm in size (Napier-Munn, et al., 1999). Work on the breakage of finer particles is still an area of intense research and single particle breakage is being investigated as are multiple particle, fixed bed methods (Hoffler and Herbst, 1990; Bourgeois et al., 1992; Whiten, 2007).

Jan 1, 2011

By J. H. East, D. Harrington

"INTRODUCTION Mining at its best is not a clean occupation for either surface or underground employees; and this applies alike to coal, metal, and non-metallic mines. The employees are handling minerals that have been blasted, or broken by some means and are subjected to mineral dust, whether it is coal, quartz, or talc. The employees usually wear clothes specifically adapted to the work in which they are engaged, and frequently these clothes are not suitable for use away from the mine. Many mines are wet, and employees must wear rubber boots to remain at least partly dry, and even on relatively dry mines, some parts of the mines usually have water falling from overhead, there are accumulations of water, or the floor or other surfaces are wet or muddy, Some mines are dusty, and the air-borne dust quickly settles on the clothes and body of the miner, especially, when he is working in confined areas, or in places that are hot, humid, or poorly ventilated. Most occupations around a coal tipple, anthracite breaker, or a mill at a metal or nonmetallic mine have their own problems of cleanliness as to skin or clothes or both. Mining in any of its phases is inherently dirty work, and the employees dress accordingly while at work.In the early stages of mining it was the custom or workers to wear their dirty clothes home and change there. This necessitated their going home after work in dirty clothes which were usually damp from perspiration or from contact with wet or muddy matelials or surfaces, and, in addition to being inconvenient this was a frequent cause of colds, pneumonia, other pulmonary diseases or, possible skin ailments. Men working in very wet mines found that it was more satisfactory to change into dry clothes in the boiler room at the mine after work and allow their wet clothes to dry overnight. The mining companies later provided the first of the so-called ""dry-houses"" which were heated but had, few, if any, conveniences, such as showers, lockers, or latrines. The miners changed into dry clothes after work, but would not bathe or ""clean up"" until they reached their homes. Later, progressive mining companies provided bathing facilities for the employees, and eventually the present modern wash and change houses were evolved. Unfortunately, many mines, still have no bathing accommodations, and many have only makeshift accommodations."

Dec 1, 1947