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By R. W. O. Kersten

The shrinkage method of stoping with pillar support has been used at Agnes Gold Mine since mining commenced. Until recently, rock instability did not have any detrimental effect on safety or production. Presently sill pillars are failing not only on the current production levels, but also in shallower old worked-out areas. The incidence of failure raises the question as to whether the pillar dimensions are adequate at the current working depths and what their size should be at greater depths. The effect of pillar dimensions on the economics of the mining operation is of paramount importance because of the amount of ore that can be left unmined.

Jan 1, 1982

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through the use of more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the air bubbles, water, and ore, rapidly attaching the hydrophobic mineral to the bubble surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. A rougher concentrate containing 4.5 pct copper was obtained from a western porphyry copper ore containing 0.67 pct copper. Over 99 pct copper was recovered from the ore at a rate 7 times faster than conventional flotation.

Jan 1, 1991

By B. L. Bessinger

Because of a, work stoppage at the Carlsbad plant, IMC faced the challenge of operating a 24-hour-a-day mine and plant with inexperienced maintenance and production crews. This is an underground mining operation, using the room-and-pillar mining- method. The mine was entirely, mechanized with conventional equipment, was hoisting an average of 13,539 tons off ore per 24 hours, and employed a, mine maintenance group of 100 men. The 100-man, mine maintenance group was equally divided between mechanics and electricians. In re-forming this maintenance group, two main objectives were to be achieved (1) a general upgrading off the intelligence level; and (2) the elimination of craft lines for greater flexibility.

Jan 1, 1966

By A. F. Symonds

The effects of harmonic resonance between the supply impedance and power factor correction capacitors on systems with large harmonic sources, such as mine winders, are well known. The similar effects of resonance with cable capacitance are not commonly encountered and, hence, are not always considered in the design of medium-voltage networks. This article considers some of the aspects of resonance between the supply impedance and the cable capacitance and presents one successful approach to solving the problem.

Jan 1, 1998

By G. Davis

It is well known that anticipated mineral prices can have an overwhelming effect on a property's expected value. However, price movements throughout the life of a project also affect value. Thus, it is necessary to not only estimate the expected commodity price at the start of a project but also the manner in which that price is likely to fluctuate throughout the project's life. This paper provides a simple method of incorporating mineral price movements into mineral project valuations.

Jan 1, 1997

By Heinrich Schubert

In many unit operations, there are more or less developed turbulent flow conditions. Then, macroturbulence influences the transport phenomena of the particles and microturbulence controls the stresses acting on fluid and solid particles or agglomerates as well as the collisions between particles. Consequently, these conditions have to betaken into consideration for modeling and optimization. The results of corresponding approaches are demonstrated taking classification and flotation as examples. But, at present, extensive simplifying assumptions have to be made.

Jan 1, 1989

By W. J. Garmoe

The Carr Fork mine is located approximately 50 kilometers southwest of Salt Lake City, Utah, in the Bingham or West Mountain District, adjacent to the Bingham open pit copper mine. Applied geology at Carr Fork, by Anaconda Minerals Company personnel, includes detailed geologic mapping and sampling of underground workings, logging and sampling of drill core and cuttings, and the preparation and posting of geologic maps and cross sections for geologic interpretation, ore reserve calculation, mine operations, and long range planning. Accurate and easily understood graphic recording of Carr Fork geology is essential for optimum use by operating and engineering personnel. The design and implementation of exploration, development and definition drilling programs, research into geological spatial relationships, and analysis of structural complexities of the Carr Fork deposit are also integral parts of the applied geology program.

Jan 1, 1992

By Greg Barfoot, Alex Harrison

Conveyors with multiple drive pulleys of the same diameter and wrap, driven by identical motors through gearboxes of the same ratio, consume different powers. The fundamental issues related to this problem hinge around the drive pulley co- efficient of friction and the intermediate tension. Some basic design concepts will be presented with reference to validity and applicability. The paper will describe some experimental results obtained from multiple drive conveyors in which the drives are spatially separated. The dynamics of tripper drive and linear booster drive systems are overviewed with reference t

Jan 1, 1993

By A. Unal, R. L. Grayson

The use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments are reviewed, and the specifications of some of the past and currently available systems are presented. The advantages and disadvantages of using various frequencies, system configurations and specific components, including their construction standards and capability, are also discussed. The remaining challenges to the more widespread use of RFID systems for personnel and vehicle tracking are identified, and recommendations concerning the operating environment capabilities are detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency are discussed.

Jan 1, 1999

By Robert W. Burns

Gentlemen, my subject today is glass reinforced plastics. By definition, this encompasses a wide variety of materials: at least a half dozen basic varieties of polyester, epoxy, and phenolic; virtually infinite compounding variations within the basic groups: literally limitless variations in the amount and the nature of the glass reinforcing. Complicating all of this is the fact that different modes of application of the same material fall appreciably alter' the product's general strength and suitability. These many, many differing materials are what we conveniently call "glass reinforced plastics" or, more simply, fiberglass". This common name is actually a large part of the problem when dealing with fiberglass materials. Far too often a specification is written calling for simply "fiberglass reinforced polyester', based on successful prior use of a polyester laminate. Such a specification is very nearly worthless since such tremendous variation is possible under it. Success of a laminate furnished under such a specification is entirely dependent on good fortune

Jan 1, 1962

By J. Andersen

The very large quantities of energy used for size reduction in the minerals processing industry necessitate the accurate prediction of comminution machine power draw for optimum plant design. The JKMRC has developed effective models for predicting ball mill, autogenous mill, semi- autogenous mill and crusher power draw. When combined with comminution models they provide a powerful tool for evaluating not only the size reduction performance of a plant design, but its power utilization efficiency as well. This paper describes the structure of the mill and crusher power models. Data from a wide range of equipment types are presented which illustrate the accuracy of these models.

Jan 1, 1992

By Jorge A. Benitez Muro

Within the exploration programs carried on by the Consejo de Recursos Naturales No Renovables, the one with the largest coverage (more than 75, 000 square kilometers) is the northern Coahuila Exploration Project. Due to its nature, geochemical exploration methods were selected to obtain quick results. The program included essentially, three main stages : 1. - A regional geochemical stream sediment survey. 2. - Semi-detailed studies of the anomalous areas selected in the previous stage, and 3. - Detailed exploration of the promising areas. To the date, the first two stages have been completed, and the third one is being carried on. The work was started on september 1972, and it will probably take one more year before drilling can be started, but at the end of stage three it is expected that at least 5 important targets will have been detected. The regional work was conducted by 3 field crews, but the detailed program is being done by only one.

Jan 1, 1974

By Donald Lau, Adrian Crawford

In the field of grouting, practitioners fre¬quently advocate procedures that are often unique and contradictory. As a result there has been considerable debate as to what constitutes optimum grouting practice. A knowledge of both the rheological properties and the flow characteristics of grouts is essential to the development of a rational understanding of the grouting process. Flow models and viscosity experiments have been conducted using cement grouts comprising High Early Strength Portland and Microfine cements. The addition of superplasticizers was found to enhance the flowability of the grouts as well as to reduce the effective groutability ratio. Steady state flow equations and design charts for predicting the radial penetration of cement grouts have been developed.

Jan 1, 1986

By S. K. Kawatra

For efficient control of particle size in a wet grinding circuit, three alternative methods for monitoring pro- duct particle size are available. These methods are based on: 1. Ultrasonic wave absorption. 2. Low-angle forward scattering of a laser beam. 3. Inferential sizing techniques. The relative advantages and disadvantages of each technique are discussed. A particle size monitor can be used on a single grinding line to control the product particle size. To minimize the number of particle size monitors at an operation consisting of many similar grinding lines, a portable multi-stream on-line analyzer can be used. The paper outlines the design and the operational characteristics of the portable multi-stream online analyzer.

Jan 1, 1979

By Dave Willis

Two hundred and thirty million tons of coal! That is what the Burlington Northern (BN) railroad anticipates that it and the Chicago North Western railroad (CNW) will haul out of the southern Powder River Basin l (see map on page 966) in 1994. Put that 209 Mt (230 million st) into railroad perspective. Current average train size is 113 cars. With each car transporting 94 t (103.5 st) of coal, each train averages 10.6 kt (11,700 st) of coal. Simple division shows that 209 Mt (230 million st) of coal equals 19,658 trains a year. So BN and the CNW must move 54 loads a day out of the Basin. Every load, of course, has an empty side of its cycle. This means that 54 loads a day translates into 108 total trains a day, or 39,420 trains a year through the southern PRB.

Jan 1, 1994

By M. T. Holroyd

Digital computer applications to minerals exploration remained largely an experimental alternative to manual techniques until well into the 1960's. Due to the high cost of computer time, and the lack of digital data and appropriate software, the most favoured applications in the early days were computationally intense tasks - those which produced the most results with the least demands for programing and data input, e.g. forward modeling. When large digitisers and plotters became affordable, the computer took over simple labour intensive tasks such as data transcription, and when software caught up, more complex tasks such as contouring. Digital data acquisition systems and superminicomputers made total computerisation of geophysical compilation and cartography possible and affordable. Applications continued to develop into areas of much greater logical complexity. Software, the new labour intensive process, still lagged behind. The microcomputer made computer applications potentially available everywhere to everyone. Desk-top micros as powerful as the minis of ten years ago can take on any geophysical exploration task currently done by computer - when the software becomes available.

Jan 1, 1989

By John W. Graham

To start my talk, I thought it might be helpful for us to define the term "aggregate", so I went to the dictionary. Webster has several listings under "aggregate", and I found the following: "1. A mass or body of units or parts somewhat loosely associated with one another." Well, I didn't like that term "loosely" so I read on. "2. Crystals of one or more kinds of mineral or rock fragments." That sounded better, but I still read on. "3. Any of several hard inert materials used for mixing with a cementing material to form concrete or mortar." That sounded even better, but it should be a little broader. So I would like to define "aggregates" for you as follows: "Hard, inert fragments of rock or minerals used alone or with cementing agents to form products essential to nearly all types of construction." Usually aggregates are sand, gravel, or crushed stone, but other minerals such as clay or shale can be heated and become aggregates. What are some of the construction uses? Well, we've already mentioned concrete, as used in streets and highways, sidewalks and parking lots, airports and all kinds of building construction, not to mention bridges and swimming pools, and docks and breakwaters, just to list some of the uses. Our way of life couldn't exist without concrete. And you can't have concrete without aggregates,

Jan 1, 1977

Little knowledge is available that considers the effects of continuous miner position on the possible respirable dust exposure of the remote mining machine operator. Such information could be very useful for increasing the awareness of the remote operator as to those parts of an extended cut that generate higher levels of respirable dust. This data could be used to develop guidelines for positioning the remote operator to reduce his potential exposure. This work details the effects of continuous miner position on dust levels measured on the machine and at the remote continuous miner operator location.

Jan 1, 1998

By Ernest M. Spokes

Maximum fan efficiency can only be obtained when the fan has the correct combination of size, speed, and blade setting to provide the required flow of air against the mine resistance. As the mine grows older, resistance decreases unless old workings flow is restricted, and new combinations of speed and blade setting or different fan sizes may provide greater economy.

Jan 1, 1977

By Madan M. Singh

Although roof bolting has been a major means of strata support for nearly two decades, little attention has been directed towards the design of bolt Installations. The variables involved are interdependent and their study complex. However, some simple tests may be employed to serve as guides to the efficient design of roof bolt systems. Local conditions are continually varying and are important to pattern design. This paper discusses such considerations and suggests techniques which may be employed to effect improved roof control with bolts.

Jan 1, 1967