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By C. P. Mangelsdorf

Introduction During the 13 years since C. C. White introduced the Birmingham roof truss there has been a revolution in permanent roof support technology. While not all of the emerging concepts have their origins in the truss-resin bolting is a prime example - the combinations and permutations of devices presently available to the underground mining industry reflect a well-spring of creative activity. The purpose of this report is to chronicle a number of roof support system that have same physical similarity to the Birmingham truss, and to report on their application. Definitions The application of the tern "truss" to the device developed by White of the Birmingham Bolt Company in 1967 may be derived from the classical technique of stifwood, by the attachment of an underslung, sometimes pretensioned metal strap, rod or cable. If the beam is separated from the reinforcement by a single block or vertical post it is called a "King's Post Truss". If two equally spaced blocks or posts are used it is referred to as "Queen's Post". When the immediate roof of a mine is visualized as a beam, the Birmingham device completes a structure resembling this latter form.

Jan 1, 1982

By F. M. Swain

High-calcium limestones occur in the upper part of the New Market Formation, of Lower Middle Ordovician age, in Franklin and Cumberland Counties, Pennsylvania. The high-calcium facies of the New Market Formation is represented by sublithographic limestone or vaughanite, which probably formed in quiet water; low-energy environments such as intershoal lagoons, or in protected bays similar to the present-day Florida Bay environment. Rapid facies changes are characteristic of the strata. The better grade of stone lies in the upper 100 to 125 feet of the New Market Formation and averages 95-97% calcium carbonate. Silica and magnesia are about equal in amount as impurities. One high-calcium belt extends from the Maryland state line through Chambersburg and Newville to beyond Carlisle. The strata in this belt are structurally complex, which requires careful field study' and core-drilling prior to exploitation. Stone suitable for blast-furnace flux is present in relatively large amounts, but stone for open-hearth use or portland cement requires more selective quarrying.

Jan 1, 1966

By Ralf Vergeiner

The most famous landmark of the city of Graz (Austria) is the clock tower on the castle hill. An underground chamber was built as a multifunctional structure beneath this landmark. The required structure was designed as cavern. The overburden to the clock tower in the north side of the cavern was only 30 m. To allow access from the city to the chamber and the clock tower, a vertical shaft was built near the cavern. Rock excavation was by drill and blast method. The pilot shaft was made by the raise-boring method. Because the location of the building site was in the center of Graz, special care was taken to minimize deformations and vibrations so as to protect surrounding buildings.

Jan 1, 2001

By E. M. Frizzell

In an effort to economically and efficiently enhance the erosion control aspects of present surface coal mine reclamation practices, the US Bureau of Mines has recently completed a two-phase research program wherein irrigation strategies and equipment developed under the first phase were field tested on three surface coal mine sites. The fundamental basis for the use of irrigation as a reclamation tool is to provide the plant moisture requirements as a supplement to prevailing natural precipitation, and thereby support the natural growth of drought-hardy native vegetation. Portable solid-set irrigation equipment and several irrigation strategies were tested on large 6-ha (15-acre) sites in Montana, Wyoming, and New Mexico. Results of these tests will be presented which include daily irrigations, precipitation levels, soil moistures, climatic data, and density cover and biomass of the native plants.

Jan 1, 1987

By Cynthia S. A. Wallace, Joseph E. Crawford

The Culberson ore body is a bioepigenetic sulfur deposit located in the Delaware basin. Sulfur occurs in the Upper Permian Castile, Salado and Rustler Formations. Most of the ore body forms a subhorizontal layer within the Salado Formation. Abundant cave fill deposits of Rustler and younger lithologies occur within the Salado Formation and predate mineralization. The cave fill deposits provided porosity zones within the otherwise impermeable sulfate host rock and controlled sites of mineralization. A northeast trending fracture zone near the west edge of the ore body localized some deep mineralization and may have allowed migration of hydrocarbons from depth.

Jan 1, 1992

By John T. Bartlett

With more stringent environmental and economic constraints being placed on mining operations, it has become necessary to optimize each process to minimize energy and raw material consumption and reduce waste discharge. In most cases, detailed process analysis is required to detect inefficiencies and provide alternative solutions for process improvement. HETSIM, a microcomputer process modeling and simulation system, is routinely used to analyze communition, hydrometallurgical, pyrometallurgical, and coal preparation processes. The process modeling techniques used in METSIM, including process control simulation, will be presented and illustrated using actual plant processes.

Jan 1, 1987

By Pierre Mousset-Jones, Felipe Calizaya, Malcolm J. McPherson

The algorithm presented in this study determines the combination of fans that provide all working districts of a mine with predefined airflows at the minimum operating cost. It is based on an existing ventilation simulator, VNETPC, and a set of linear equations associating fan pressures and the added resistance of regulators. Two assumptions are undertaken: (1) fan locations are predetermined and (2) the number of working districts is equal to or greater than the number of fans. By means of this algorithm, the optimal solution to an n fan ventilation system may be found after n + 1 simulation runs.

Jan 1, 1987

By S. Subbarayan, S. Chander, M. S. Klima

A laboratory study was conducted to investigate the potential for recovering anthracite from coal preparation-plant tailings. The study included washability analyses, cyclone simulations and froth flotation testing Samples were collected from either the tailings streams or the slurry ponds of five anthracite-cleaning plants. From each sample, a washability analysis was conducted on the 28x100 and 100x200-mesh fractions. Using the above data, along with published partition data, simulations were performed with various cyclone-staging arrangements for both water-only and dense-medium cyclones treating the 28x200-mesh fractions. Separate froth -flotation tests were conducted on the 28x100- and 100x200-mesh fractions from three of the plant samples. The washability, simulation and flotation results are presented as grade-yield curves.

Jan 1, 1996

By W. R. Dearman, N. Turk

A seismic fissuration index (K) is defined as the ratio of the difference in the P and S wave velocities obtained when a dry rock specimen is tested both under a load equal to half the uniaxial compressive strength of the rock (Vo) and without an applied load (Vd) to the velocity obtained without an applied load (Vd), as K = (Vo - Vd)/Vd. A similar seismic fissuration index is also proposed for classifying the dry rock mass in terms of field seismic velocities. The field equation is extended by including the intact rock seismic velocities. K is found to be related to the porosity of rocks. The proposed equation can equally be used for characterizing saturated rocks, using S-wave velocities. However, the time average equation should be used for characterizing saturated rocks, using P-wave velocities, even though this equation gives upperbound estimates of the rock material and fracture porosities.

Jan 1, 1986

By D. W. Fuerstenau, J. Vazquez-Favela

This paper shows how the efficiencies of size-reduction processes depend on the mode of particle constraint and energy transfer within the comminution device: namely, whether the process consists of single-particle loading, confined-particle-bed comminution or loose- (unconstrained-) particle grinding. The relative efficiency of single-particle comminution, ball-mill grinding and particle-bed comminution in the recently invented high-pressure roll mill is evaluated by making use of the self-preserving nature of the size distributions of comminuted products. The highest energy efficiency can be achieved by utilizing a hybrid two-stage system in which the material is first ground in the high-pressure roll mill and then the ball mill.

Jan 1, 1998

By Steven A. Whittle, Robert E. Cook

Years ago, personal computers (PC) were pricey devices destined for who knows where in the process industry. Now their use runs the gamut from low end data acquisition systems to high performance windows into the process area. Their applications range from CAD, CAM, CIM, and CAE to factory floor scheduling, process planning QC, facility management, cell control, and publishing. This discussion traces the evolution of a zinc plant's control automation program beginning with a PC as an operator interface and migrating to higher level work stations. Included in this paper will be a discussion of an Open Industrial System and the role PCs have played in this facility.

Jan 1, 1993

By Chi M. Phan, Anh V. Nguyen, Geoffrey M. Evans, Graeme J. Jameson

Surfactants are used to control the interfacial properties of the gas-liquid and liquid-solid inter- faces inflotation. This paper investigates the dynamic adsorption of surfactants at the gas-liquid intelface. The dynamic adsorption process was modeled by considering the surfactant mass transfer to the gas-liquid interface by dimion and the Langmuir and Frumkin adsorption isotherms. The numerical computation was applied to solve the non-linear governing equations. The dynamic adsorption was measured in tenns of the dynamic surface tension using the pen- dant drop method. The theoretical modek were compared against the experimental data obtained with non-ionic (Dowfroth 250) and ionic (sodium dodecylbenzene sulfate, SDBS) surfactants. The theoretical results agreed well with the erperimental data for SDBS, but not for Dowfrother 250, especially for the initial stage. Reasons for the variation in results are given in the paper.

Jan 1, 2005

By B. Jensen, B. K. Abraham, G. J. Tuck, A. D. S. Gillies

A dust concentration meter has been developed with Australian coal industry support for the measurement of total airborne dust concentrations capable of causing explosions in underground coal mines. The instrument, The University of Queensland Dust Meter (UQDM), measures the effective dielectric constant of a mixture of coal dust and air that is drawn between the plates of a capacitor, the capacitance of which is measured by a ratio-transformer bridge and synchronous detector system. This technique measures small changes in capacitance to approximately 1 part in 106. The unique design of the capacitor sensor permits a precise volume of coal dust and air mixture to be sampled. This arrangement overcomes difficulties inherent in optical dust measurement. The meter is portable, battery powered, incorporates data logging and has intrinsic safety approval. The operation of the meter is discussed. The system is designed to monitor dust concentrations along a coal mining face and provide concentration profiles leading to the development of suppression strategies. If data from underground tests are available, the meter's potential to contribute to establishing safe working conditions underground will be discussed. Other areas of potential application of the measurement technique are also examined.

Jan 1, 1993

By M. C. Rockwell, G. F. T. Lay

Promising placer gold exploration sites offshore Lunenburg County are drowned pre- and post-glacial river channels and auriferous glacial tills. Gold values up to 5.67 9/m3 have been encountered in the vicinity of the Ovens Peninsula offshore Lunenburg County. Moderate gold values associated with notable amounts of heavy minerals were reported from various other exploration sites in this area. This paper highlights the major geological and gemorphological features for placer gold depositions in southern Nova Scotia. The past to present gold exploration activities nearshore and offshore Lunenburg County are summarized and potential areas for placer gold identified.

Jan 1, 1988

By Wen L. Cai

This paper examines the effects of different block dimensions and cone bases on the economic open pit limit design based on case studies on a coal deposit consisted of two west- east elongated, near vertical thin seams starting with a base model dimension of 200x170x50 (NX*NY*NZ) with a block dimension of 10mx5mx4m (DX*DY*DZ), the blocks were combined along easting, northing and elevation directions. Two cone bases were used, one with a base radius of 10 meters, the other with a base radius of 0. Two pit design algorithms, one is the floating cone algorithm, the other is an optimum algorithm, were used to see which one of the two pit design algorithms is more sensitive to block dimension and cone base variations. The results are presented and analyzed.

Jan 1, 1992

By Walker Ian W., John D. Gow

The paper describes the exploration and development activity associated with a series of open pit gold deposits in the Laverton region of Western Australia with an aggregate resource base of 4 million tonnes at a grade of about 3 grammes per tonne. In September 1988, Hill Minerals N.L., now a wholly owned subsidiary of Ashton Mining Limited, completed the purchase of the Cork Tree Well treatment plant from Austwhim. This CIP plant had a rated capacity of 235,000 tonnes per annum, and is located within the Hill Minerals Laverton Project area. Ore is trucked by haulage contractors from each open pit mine to the central treatment plant at Cork Tree Well. Studies were completed and a plant expansion undertaken lifting throughput to 500,000 tonnes per annum. A contract was let for this expansion in November 1988, and construction completed in April 1989. Concurrent with the above project development work, heap leach metallurgical studies are being undertaken on low grade mineralisation associated with higher grade ore zones at several of the open pit mines, notably King of Creation and Craiggiemore. It is anticipated that heap leaching will provide a useful adjunct to gold production from milling higher grade ores.

Jan 1, 1989

By P. Chauvet

From a computational point of view calculating a variogram is a perfectly simple operation. For any particular study, we know which variable is to be studied. We also have a good idea of structural parameters which are likely to be important (the scale of the phenomenon, the probable direction of the anisotropy, etc.). Finally, we know the structure of the data file. So we can specify the parameters to be used to calculate the variogram (the distance classes, the angular classes, etc.). This allows us to decide which variogram program is most appropriate (1, 2 or 3 dimensional data, regularly or irregularly spaced, etc. ) . In general, the basic statistics (mean, variance, correlation? etc.) have been calculated beforehand, and so the distribution of the data is already known. Consequently, the choice of the parameter values fed into the variogram is by no means arbitrary. But it must nevertheless be made before the' variogram is calculated. If the resulting variogram is not satisfactory, the whole sequence of operations has to be repeated. Before going on to see how this can be avoided, it is worthwhile having a brief look at the common causes of "unsatisfactory" variograms.

Jan 1, 1982

By Kevin D. Lofftus

This paper presents a dynamic model for column flotation. The model equations are normalized and the dimensionless groups that are directly responsible in determining the column flotation behavior are identified. The resulting model equations are incorporated for computer simulation. Numerical results from computer simulations are analyzed to gather information about design and operation of column flotation devices.

Jan 1, 1988

By Arpad E. Torma

The introduction of biotechnological principles in hydrometallurgy has created new opportunities and challenges for the industry of mineral processing. During the 1950's and 608s, the mining wastes and unused complex mineral resources have been successfully treated in bacterial assisted heap and dump leaching processes, especially for the production of copper and uranium. The economic viability of bio- leaching technology lead to its world-wide acceptance by the mining industries. During the 1970's this technology grew into a more structured discipline which is called "biohydrometallurgy". Currently, bioleaching techniques are ready to be used, in addition to copper and uranium, for the extraction of cobalt, nickel, zinc, gold and silver from diverse mineral resources and for the desulfurization of certain coals. However, in a foreseeable future the biohydrometallurgical processes may be applied also for the treatment of high- grade ores and mineral concentrates using native and/or genetically engineered microorganisms.

Jan 1, 1989

By Yannis Faitakis, Brenda M. Wright, Gail Powley, Mark Hamblin, Randy B. Paine

A major problem in the ore extraction process is the high degree of variation in the mix of materials that make up the mined ore. The mix of materials makes it extremely difficult to characterize and predict the behavior of the ore when it is processed. The Quality Production Database (QPD) tool was successfully used in order to predict and transfer information regarding the quality characteristics of the ore being delivered to the extraction and hydrotransport unit operators. This paper describes the use of QPD in the prediction of various ore characteristics at the Syncrude Canada Ltd. processing facility.

Jan 1, 2000