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By Günter Strappler, Max John

When tunneling through karstic terrain, diverse and complex karst structures are to be expected. By means of drilling ahead of the face using drill jumbos, these structures can be detected to such a degree that by applying proper support measures both open karst cavities and karst holes surrounded by boulders embedded in soft rock can be mastered without causing any break-outs. Support measures such as spiles ahead of excavation, sealing off cavities, back?lling with sand, etc. have to be planned schematically and adapted to the dimensions and formations of the karst structures on site. An essential requirement for a smooth excavation procedure is the availablility of all necessary tunneling equipment for excavation by drill and blast as well as for excavation of soil, with experienced tunnel engineers being in charge of any adaptions on site.

Jan 1, 2003

By E. P. Barrett

THE high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,1 in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. SHAPE AND SIZE OF CENTRIFUGAL LIQUID CRUCIBLES When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape f a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and its speed of rotation. Melted Wood's metal was poured into cylinders 2 ½ in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections f the cylinders, shows the effect f speed f rotation of the containers upon the shape f the inner surface f the rotating liquid crucibles.

Jan 1, 1938

This paper describes the application of a three-dimensional finite element modelling tool to help assess the stability of a highwall at a Central Queensland mine following the weakening of its base due to highwall mining. With traditional stability assessment techniques, likely failure modes are identified on the basis of previous experience and structural, sedimentological and geomechanical data and a mechanistic analysis of these individual modes is performed. The value of the full three-dimensional model over these traditional techniques is that it provides a coherent approach to assessing highwall stability without the necessity of initially deciding upon the dominant failure mechanism and gives a useful adjunct to the traditional tools. The three-dimensional model assumes the rock mass is made of elasto-plastic blocks, incorporating possible planes of weakness, separated by near horizontal joints. The model includes the relaxation of stresses due to the excavation of the highwall and incorporates estimates of blast damage near the highwall surface

Jan 1, 1995

By N. L. Wimmler

"INRODUCTIONSedimentary deposits of titaniferrous magnetite occur at various localities in the eastern foothills of the Teton Ranse in Deer Lodge County, Mont. The Choteau deposit was examined by a Bureau of Mines engineer in August 1942. An exploration project was recommended.Core drilling exploration was begun in June 1945; it was concluded in August 1945, Seventy-six holes were drilled. This report presents the data obtained by the Bureau of Mines exploration.ACKNOWLEDGMENTIn its program of exploration of mineral, deposits, the Bureau of Mines has as its primary objective, the more effective utilization of our mineral resources to the end that they make the greatest possible contri¬bution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, Chief, conducts preliminary examination, performs the actual exploratory work, and prepares the final, report. The. Metallurgical Branch, R. G. Knickerbocker, Chief, analyzes samples and performs beneficiation tests. Both of these branches are under the supervision of Dr. R. S. Dean, Assistant-Director. The field work was supervised by Earshel W. Newman, engineer in charge of the Helena Field Office. D. B. Hoiekvam was the project engineer; he provided most of the data used in the preparation of this report."

Dec 1, 1946

By Jurgens J. Louw, Vincent C. Smith, Gareth C. Smith, Agit Singh, Dave G. Hulbert

"During 2000 Mintek Developed the PlantStar plant wide control platform for the minerals processing industry. The flexibility of the PlantStar control platform has enabled Mintek to investigate and easily develop new control strategies for both milling and flotation. This includes a Solids Feed Controller, a Safety Limit Controller, Mill Power Optimiser and Flotation Optimiser, amongst others.Processes with long dead times, like a feed belt to a mill, are difficult to control. The solids feed controller was developed for minerals processing plants using a specialised time delay compensator. Using conventional time delay compensators that are purely model based, results in robustness problems due to model uncertainties. The Mintek Solid Feeds Controller makes use of a plant model, but compensates for model inaccuracies, giving more controller stability and a more robust delay compensation algorithm.Often there are more variables on a plant that need to be controlled (process variables) than there are variables to control them with (manipulated variables). Process constraints are often reached and violated. Safety control loops are necessary to prevent constraints being reached. The safety limit controller has been developed to switch smoothly between normal and safety control loops without bumping the process. The safety loop output is chosen in accordance with a predefined list of priorities and whether the respective constraint boundaries are exceeded.The Mill Power Optimiser helps to find the power peak on the mill power curve. It continuously perturb the solids feed rate to learn ‘where’ on the curve the mill ‘was’ and then to drive it continuously toward the middle, maximum power drawn. This insures maximum grind with maximum throughput. It also prevents power dips due to mill overloads by cutting the solids feed to a minimum if the power drop below a specified threshold. Once the power rises above the threshold the solids feed is increased again to an intermediate value from where it start the perturbations again to find the maximum. This makes the milling circuit easier to operate."

Jan 1, 2003

By Gungor Tuncer, Ali Kahriman, Abdulkadir Karadogan, Umit Ozer, Ertugrul Kaya, Kagan Ozdemir

The results of bench blasting on quarries, have important influences on the performance of subsequent mining activities such as loading, hauling, crushing, grinding etc., and the total costs of that mine. Drilling and blasting is an important step in mine producing chain and its results such as fragmentation, muckpile shape and looseness, dilution, damage and rock softening effect the efficiency of downstream processes. Within the scope of this study, the three different hydraulic excavators’ working performances have been studied considering the particle size distribution after bench lasting at a quarry in Istanbul Turkey. Five shots have been realized on the quarry and average particle size of muckpile after each shot were assessed by digital image analysis method. Bucket loading times have been measured by stopwatch study after five shots. Excavator bucket loading times were also estimated by bucket loading time estimation formula which was published in ISEE 2007 Conference, Ozdemir et al. 2007. Estimated and measured times have been statistically analyzed and the accuracy rate of formula has been determined for five events.

Jan 1, 2008

Manganese ore from the Black Rock, Kramer, and Black Jack mines in Tooele and Jaub Counties, Utah, are of acceptable grade, the U. S. Bureau of Mines has announced. Payment of a premium price of 252¢ per lb to the Copper Range Co., of Michigan for the output of its White Pine mine, has been agreed to by the DMPA. The contract will be limited to $28.6 million worth of copper. The agreement follows an RFC loan grant of $57 million to bring the White Pine property into production within three years. Increases of 5 to 6 cents over the Lake copper ceilings have been granted to the Calumet & Helca Consolidated Copper Co., for operation of "high cost" deposits, according to Jess Larson, DMPA administrator. Mr. Larson expects the move to add about one million lb of copper per month to the supply. The agreement can be cancelled on 60 days notice and is terminated automatically in the event copper ceilings are removed.

Jan 1, 1952

By Y. M. Jiang, D. W. Park, S. M. Lee

A vast majority of longwall operations in the US use shield-type hydraulic supports to provide ground control along the longwall face. The three-dimensional, finite-element technique combined with a progressive failure approach was utilized to simulate interaction between shields and surrounding strata and determine various loading conditions. In addition, a separate finite-element model of the shield structure was made to study responses of each longwall shield to the different loading conditions. Shield responses under various loading conditions and the shield characteristics, such as shield stiffness, the ability of resisting horizontal forces, and the effect of shield height, were studied based on the results from finite-element analyses. The results can provide the basis of effective shield design and be used for evaluation of the shield performance. It is suggested that a technique incorporating the finite-element method be developed to evaluate real-time shield performance for the purpose of effective ground control.

Jan 1, 1993

By Roberto Parra

The selective reduction smelting of Cu2O in Cu2O-FeOx-SiO2 melts has been studied at laboratory level, using as a feed a dead roasted calcine from a copper concentrate. The purpose of the study was to evaluate the kinetic and mechanisms of the indirect reduction with CO and the direct reduction with graphite from 1260°C to 1350°C. The reduction rate by CO was found to be 10-2 to 10-1 mole Cu2O m-2s-1. The graphite reduction macrokinetics for FeO and. Fe2O3 containing melts, was found to be a first order reaction with respect to the Cu2O concentration, with a kinetic constant of 104 to 10-3 s-1. The reduction rate was not sensitive to temperature nor to stirring, in the range studied. The measured reduction rate is almost one order of magnitude larger than the observed rate for the direct reduction of FeO.

Jan 1, 1999

By G. Bucelluni

An essential element of truss bolt installation requires machines to angle a hole in the top of approximately 39° to 45° from its vertical axis. Parameter which inherently effect the drill position are: height, width of truss, physical size of mast, and whether single or dual mast bolting is utilized. The combination of these facets govern the installation procedures required for the bolting cycle. The following illustration with written explanation will demonstrate this concept. See Figure #1. [ ] This model assumes certain fixed criteria which corresponds to a dual mast drill design and a set 41° drill angle. Using the derived formula, the maximum possible seam height for both masts to touch the bottom can be calculated for any given condition by substituting by the appropriate bolt spread distance. [ ] In a high seam application where the mast touching the bottom was considered a requirement, the proposed model demonstrates the advantage of single mast drilling. See Figure #2. [ ]

Jan 1, 1982

By G. A. Gross

DURING the past 5 years a large amount of money and effort has been expended in exploration of iron-formations and in testing their suitability for beneficiation. Beds of ferruginous material are numerous and widely distributed in the Precambrian rocks of Canada and practically all of the known iron ranges or belts have been examined to a limited degree at least in an effort to evaluate their potential as sources of iron ore. A number of favorable beds have been selected for mining on completion of surface sampling, diamond drilling, extensive metallurgical testing and economic studies, and many other ranges are being studied. There are still a great many iron-formations that have not been evaluated by modern concentration methods and their regional extent is not fully known. The iron-formations are easily located by airborne or ground magnetic surveys but the main task in finding a mineable ore-body of this type amounts to locating a bed sufficiently large for mining which consists of material that can be concentrated economically by modern beneficiating methods. The ease with which an iron-formation can be concentrated to give a marketable ore depends primarily

Jan 1, 1961

By AIME AIME

A separate room in the suite occupied by the American Institute of Mining Engineers on the ninth floor of the United Engineering Society Building, has been equipped with furniture and telephone extension for the temporary use of members of the Institute or of sister societies, or visitors suitably accredited. .In addition to this general accommodation, another room has been similarly furnished as a business headquarters for a single person, and for a limited period. For the conditions of this privilege, inquiry should be made at the office of the Institute. . In order that the benefit of this arrangement shall not be restricted to a few members only, the period of continued occupancy will be limited, and applications will be considered in the order of their receipt. A small. fee will be required for the use of the facilities furnished. ANNOUNCEMENT. THE BIRMINGHAM MEETING. - The XCIVth Meeting of the Institute for the reading and discussion of professional papers will be held at Birmingham, Ala., beginning about October 1. After the Birmingham sessions and excursions, it is proposed to return by special train via Chattanooga, Ducktown, etc., to Washington, D. C., where additional sessions will be held. Further particulars will be given in a special circular, to be issued at an early day.

Jan 5, 1908

And it takes more than good organisation. You may read or heard this poignant reflection: We tried hard, but it seemed that every time we were beginning to form up in teams we would be reorganised. I was to learn later in life that we tend to meet any new situation by re-organising, and a wonderful method this is for creating the illusion of progress while producing confusion, inefficiency, and demoralisation This was written by the Roman Gaius Petronius in AD65. How much have things changed in nearly 2,000 years? What then does it take besides the fundamentals and good organisation to build a successful career in a successful organisation? I'm prepared to venture a list of what I'll'call Tips for Young Professionals. If you've got what it takes, and apply these, I think that you'll gain a great deal of satisfaction from your career, even if you don't reach the distant target each of you should have in mind now. So settle back in an advice-receiving mode, and please forgive me if I come across as a master of the bleedin' obvious, as Basil once accused his wife Sybil of being in the unforgettable Fawlty Towers.

Jan 1, 1990

The National Mining Association’s (NMA)MINExpo International ’96 is shaping up to be the organization’s largest. About 30,000 mining industry business and technical professionals are expected to descend on Las Vegas, NV Sept. 9-12 to take part in the 25 technical sessions and visit the more than 900 exhibitors who will be showing off their products and services. MINExpo will be the largest mining equipment and services exposition in the United States this year. Exhibits at MINExpo will fill the Las Vegas Convention Center, parking lots and part of the Hilton Center, located next door to the convention center. NMA estimates that this year’s show will cover more than 46,450m2 (500,000 sq ft) of exhibit space. Some of the exhibits on display will include haultrucks, hydraulic shovels and excavators, conveyors, continuous miners and tunneling machines. In addition, an array of computer equipment and software will be demonstrated. A new feature this year will be a helicopter pavilion, located in the Hilton Center. Helicopters and fixed-wing aircraft have become indispensable to many remote mining operations. NMA said that at least one full-size helicopter will be on display.

Jan 1, 1996

By William E. Little, William R. Sharp, Edward R. Kennedy

Cost o f mechanical tunneling requires the knowledge of many machine/rock parameters such as rock types, machine power, penetration rate, cutter life, maintenance schedule, etc. Capital investment, labor requirements, and project scheduling will all play an important role in defining the economics of the overall project. Knowledge of the cost sensitivity of different project parameters will improve the overall success of any particular tunneling project if this information is incorporated into an effective management plan. Through the use of an interactive graphic computer program written for a microcomputer, one has the ability to quickly evaluate relative costs for a variety of parameters for either an existing project or for a proposed site.

Jan 1, 1983

By Peter J. Alderson, M. P. Evans

The application of conveyor belting in bulk materials handling is crucial to the success of most mining enterprise selection of the cover rubber grade and thickness has a direct bearing on the cost per ton conveyed. Current and future demands placed on belt covers by higher speeds, increase capacities and greater lifts means today's cover will not be adequate for tomorrow's applications. The simple selections of RMA Grade I and I1 and MSHA above and below ground need to be expanded upon. This paper describes various new approaches for selecting conveyor belt covers for specific applications. It also presents examples of material and compounding techniques available to the belt manufacturer to improve the performance of their covers.

Jan 1, 1996

By V. I. Lakshmanan, R. Roy

Base metals and PGMs are currently recovered from sulfide concentrates using pyrometallurgical processes. These processes suffer from several limitations such as being capital intensive, scaling problems, S02 emissions and long delay in value recognition. Alternative hydrometallurgical technologies have so far not been successful and currently total pressure oxidation and partial pressure oxidation hydrometallurgical technologies are being evaluated. Process Research ORTECH has developed a unique hydrometallurgical process to recover base metals and precious metals using mixed chloride technology. In a first stage leach, base metals are recovered and elemental sulfur is liberated from hydrogen sulfide formed during this leaching stage. During second stage leach, precious metals are recovered using proven separation technologies. Some of the advantages of the process are the recovery of elemental sulfur from sulfide sulfur, recycle of the chloride lixiviant thereby eliminating effluent treatment steps and use of excess energy from the Claus reactor for the pyrohydrolysis step.

Jan 1, 2011

By Corrans I. J

A wide variety of copper-bearing gold ores exist throughout the world which have yet to be processed economically for gold recovery. The copper minerals present in these ores can be many and varied and usually result in high cyanide consumptions and problematical levels of copper in leach solutions. The copper content is often assessed as being of nuisance value as the ores are generally of the grade or type which can support neither a copper project nor a straight gold project, due to the interference of copper. Many of these problematical gold-copper ores could possibly be processed economically for gold recovery using a novel ammoniacal cyanide leaching system which utilises a copper-ammonia-cyanide complex as an effective lixiviant for gold, yet limits copper dissolution and conserves cyanide. Results from recent testing have promoted a re-evaluation of the economics of treating some gold-copper ores. This paper describes the novel leaching process and discusses the conditions employed to treat a variety of gold-copper ores.

Jan 1, 1992

By Koginmo V. I

The concentrator at Bougainville Copper Limited has an annual throughput of 48.2 million tonnes/year producing approximately 175,000 tonnes copper, 16.1 tonnes gold, and 50 tonnes silver. Conventional three stage crushing and screening are used to reduce run of mine ore to an average product d80 size of 6.7mm. The primary objective of the crush- ing plant is to provide a continuous supply of ore to the 12 primary grind- ing mills via an intermediate 300,000 tonnes capacity stockpile. Since ball mill performance improves with decreasing mill feed size, the crushing plant continually strives to produce the finest possible product for mill- ing. This has been achieved by increasing plant availability and total installed power, and improving crusher manganese liner life, screen cloth life, and plant operating practices. A recent innovation was the installa- tion of a 35 million tonnes/year preconcentration screening plant in Janu- ary 1987 to recover high grade fines from low grade run of mine ore types in which the mineralisation occurs preferentially along fracture planes in the parent rock.

Jan 1, 1988

By James D. McClung, H. J. Gluskoter, M. R. Geer

INTRODUCTION The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1 ) cleaning to remove inorganic impurities; (2) sizing-crushing or screening, or both; or (3) special treatment, such as dedusting. The properties and quantities of impurities in coal are of major importance in the design and operation of steam generating equipment. Al- though boilers are often designed and equipped to use a wide range of coals, no boiler will perform equally well with all types of coals. All coals have certain properties that place limitations on their most advantageous use. These limitations are especially stringent for many of the older installations. Because of a general lowering of quality of raw coal in recent years, the need for coal cleaning has significantly increased. Among the factors contributing to the need for increased coal preparation are (1) increased demand for quality brought on by market and environmental requirements; (2) increased extraneous dilution caused by mine, health, and safety laws; and (3) depletion of the higher-quality coal seams.

Jan 1, 1979