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By Michael J. Howes

The nature of business in a free enterprise system is to maximise the return on an investment i.e. to maximise the wealth of the shareholders. This is normally achieved within constraints dictated by many agencies, one of which is the health and welfare of the employees. In the mining industry considerable effort has been expended in improvements in this field, however, the major problem still confronting the practicing ventilation or environmental engineer is the determination of what standards he should design for, which satisfy both the economic and health requirement s. Normally the basic health requirements are satisfied by the minimum standards defined in regulations and codes of practice. These are, however, based on an acceptance of a certain risk or lower production potential. A prime function of the ventilation engineer is therefore to financially justify and implement improvements to both standards and systems. The main purpose of this paper is to examine the basis and techniques of providing this financial justification. Changes in existing methods to achieve the same standards but at lower costs are also covered.

Jan 1, 1980

By J. F. T. Agapito, C. E. Brechtel, C. J. Gilbert, T. R. Kelly, R. C. Karlson

A multi-lift benching cut-and-fill mining method was adopted at Asamera Minerals (U. S.), Inc.'s Cannon Mine to balance the goals of high productivity and near 100 percent recovery with the need to minimize subsidence. High strength backfill was required to provide effective long-term overburden support and safe working conditions during the pillar recovery operations. Operational designs were evaluated using numerical modeling to predict global mine stability and backfill strength requirements. These models incorporated sequential mining of primary stopes, backfilling of primary stopes and recovery of pillars, and have been transferred to the mine operations group for use in evaluating different production sequences. The modeling has provided a better understanding of the structural response of the mine to excavation of the primary stopes and removal of the pillars. Predictions about the transfer of overburden weight to the abutments, pillars and cemented fill pillars have provided a criterion to evaluate mining plans and production sequence. Comparison of these predictions with actual mine structural performance has developed confidence in the design of the mining method and in the geomechanical design methods being employed. Primary mining of the B-North zone is nearly complete, and the stopes have been generally stable, as projected in the original design. Some exceptions have occurred where locally stope pillars have failed due to the presence of adversely oriented sheared beds. Recovery of the pillars between the

Jan 1, 1987

By Y. J. Wang

Editor's Note: Y.J. Wang's paper appeared in the September Technical Papers section. There were some inadvertent editorial errors in it. So we are reprinting it here. Abstract - This paper examines the ventilation network problem from a view point of solving a system of B equations in B unknowns, where B is the number o f branches in the network. Based on Kirchhoff s current and voltage laws, the solution to the general ventilation network problem must satisfy B network equations. In this paper, the air quantities and control-device pressures are chosen as variables and are grouped into B dependent variables (unknowns) and B independent variables, resulting in a system of B equations in B unknowns. Based on whether their variables are dependent or independent, the network branches are classified into f our types: five d, non-fixed, p-fixed, and q fixed. The ventilation network problem may include all four types of branches. There are .some conditions under which the problem as defined in this manner does not have a unique solution. To have a unique solution, the Jocabian matrix of the equations m us! he nonsingular. It then follows that: • the number of branches with independent air quantities must be less than or equal to the number of chords with respect to a spanning tree; •the subnetwork of branches with independent air quantities must not contain any cutset; and •the suhnetwork of branches with dependent control-device pressures must not contain any cutset. These three conditions must be met regardless of the values for the variables. In addition to the problem formulation, a solution procedure applying the Newton (or Newton-Raphson) method is outlined and illustrated with an example problem.

Jan 1, 1991

By Michael L. Cramer, Kunsoo Kim

INTRODUCTION The Columbia River Basalt beneath the Hanford Site is one of several rock types being considered by the U.S. Department of Energy for the first commercial high-level nuclear waste repository. The Basalt Waste Isolation Project (BWIP) has been carrying out a comprehensive investigation to assess the feasibility of constructing a repository in basalt and to develop technology required for repository engineering and site characterization. Development of a nuclear waste repository requires a number of design considerations not usually necessary in the planning of conventional underground structures. Principal among these is the thermally induced stress field resulting from waste emplacement. This thermal stress, super- imposed on the preexisting in situ- and excavation- induced stress fields, needs to be evaluated in the design process due to the sensitivity of waste emplacement density to this factor. The nature of this thermally induced stress field is dependent on several factors, including the temperature distribution around the repository openings, the thermal properties of the rock mass, and the deformability of the rock mass. Re1iable performance of the repository structure is largely determined by the ability to under- stand the above rock mass characteristics and predict the underground opening response to waste emplacement based on this understanding. To gain an understanding of this rock mass behavior in a repository condition, the BWIP has conducted a large-scale heated block test in basalt at the Near-Surf ace Test Facility (NSTF) on the Hanford Site. This paper presents the results from the elevated temperature phase of the block test in which the thermal, mechanical, and thermo- mechanical response of the closely jointed basalt rock mass was evaluated as a function of stress and loading orientation at varying temperatures up to 200 oC. SITE GEOLOGY The NSTF test areas, including the block test site, are located in the entablature zone of the Pomona basalt f low. The Pomona flow entablature is structurally typical of most flows in the Columbia River Basalt Group in that it is characterized by long, undulating, polygonal columns up to 2.4 m in length. Columns vary from 15 to 30 cm in diameter, averaging about 20 cm. Over their length, columns can vary in dip by 150 to 200. The column structures are dissected by subhorizontal cross joints that are generally discontinuous and seldom cross columnar joint boundaries. Spacing of the cross joints also averages about 20 cm. A representative joint pattern taken from mapping of the tunnel wall near the block test site is shown in figure 1. Application of the Rock Mass Rating System (Bieniawski, l979) to the block test site yielded an overall value of 62. The corresponding value from application of the Q-system (Barton et al., 1974) is 8.7 (Cramer and Kim,1985). The NSTF is approximately 50 m below the surf ace. However, this depth is sti1l above the water table and conditions are generally dry. Interstitial water exists as the result of percolation of meteoric water from the surface.

Jan 1, 1986

By P. M. Jones

Introduction The success of in situ leaching depends upon: • maintaining adequate injection and recovery flow capacities in wells, and • distributing leach solution effectively to contact and leach ore minerals within the target zone. Solution balance is an important indicator of the capability of a particular in situ hydrologic design to efficiently and effectively control and distribute leach solution within the target ore zone. As part of ongoing hydrological investigations into in situ leaching, the US Bureau of Mines (USBM) is studying factors affecting solution balance in an unsaturated copper ore deposit at the Cyprus Casa Grande Mine. The purpose of this study is to assess the effect of hydrogeologic features and in situ operating conditions on changes, during leaching, in: • solution storage within the deposit, and • solution balance. At the Casa Grande Mine, In-Situ-Leaching Test Facility, solution balance estimates are obtained for 10 selected intervals during 17 months of leaching under a variety of well configurations, pressures and flow conditions. Operational and geological description The Casa Grande Mine is located 32 miles south of Casa Grande, AZ. The mining area is within the Casa Grande Deposit, a porphyry copper stock consisting primarily of an intensely-fractured, granodiorite cap overlying a copper sulfide base. As a result of mine dewatering activity, unsaturated conditions existed in the deposit prior to leaching (Schmidt et al., 1990; Friedel and Schmidt, 1991). No groundwater was present in any of the in-situ-leaching, test-facility wells after drilling and prior to leach solution injection. Also, no ground water seepage occurs in the test-facility drift. The Casa Grande, In-Situ-Leaching Test Facility consists of 58 injection and recovery wells collared in an underground drift. The wells were drilled at various angles into the granodiorite deposit in a series of 15 divergent fans (Fig. 1). The fans are 12.5 ft apart and lie parallel to one another between the 900- and 1100-level drifts. Each fan contains three to five wells drilled at angles ranging from 6° to 89° from the horizontal. The wells can operate in an injection or a recovery mode. Currently, 36 flow sensors and 28 pressure transducers (part of a hydrologic, data acquisition system) are used to continuously monitor injection-well flow rates and pressures.

Jan 1, 1993

By Nina I. Fedunec, Olga E. Fomicheva

Results of researches on creation of the intelligent adviser system for mining dispatcher are represented. A method of the analysis of subject domain is considered and results as the generalized expert questionnaire and diagrams are represented. The system-adviser REALTREE, functioning in real time, is represented, results of an estimation of a system effectiveness during decision making by the dispatcher are submitted.

Jan 1, 1996

By Ahmed I. A. Salama

This paper describes the development of computer density control for heavy media cyclone circuit at the Coal Research Laboratories of CANMET. The control objective is to reach and maintain the medium density set point in minimum time. A description of the mechanical components and instrumentation are presented. The control strategy and computer software are discussed. Testing and evaluation of the installed system are presented.

Jan 1, 1989

By K. N. Hebbar, R. G. Reddy

Spent potliners (SPL) were declared hazardous waste under RCRA (K088) in July, 1990. The glass formation characteristics of the SPL was studied. The SPL glassy matrix were analyzed using X-ray diffraction and optical microscopy. Results showed that SPL can be fixed in a glassy matrix with the addition of sand and limestone. The optimum amounts of additives were determined for obtaining the best glass formation characteristics.

Jan 1, 1995

By D. A. Kramer

Seawater and natural brines accounted for about 51percent of U.S. magnesium compounds production during 2004. Dead-burned magnesia was produced by Martin Marietta Magnesia Specialties from well brines in Michigan. Caustic-calcined magnesia was recovered from sea-water by Premier Chemicals in Florida; from well brines in Michigan by Martin Marietta and Rohm and Haas; and from magnesite in Nevada by Premier Chemicals. Intrepid Mining and Great Salt Lake Minerals recovered magnesium chloride brines from the Great Salt Lake in Utah.

Jan 1, 2005

By Richard R. Klimpel

This paper summarizes the author's laboratory and industrial experiences in designing and evaluating frothers for optimal coal flotation circuit performance. The key variables discussed are particle size distribution hydrocarbon addition rate, frother chemical structure, and frother dosage. A number of detailed examples will be used to illustrate the important rare/recovery/selectivity interactions that can occur.

Jan 1, 1995

By Richard J. Frechette

Final reclamation of mine tailings impoundments typically involves addressing the broad issues of surface stabilization and water management. Surface stabilization includes immobilizing the tailings particles and providing long-term protection of the containment facility. Water management typically includes provisions for handling both the external water (rainfall and runoff) and the internal water (pore fluids). Wet tailings disposal facilities, and sites with limited access and steep topography, present challenges to implementing effective surface stabilization and water management plans. This paper presents a generalized discussion of the approach to tailings impoundment reclamation based on project experience.

Jan 1, 1995

By M. J. Hrebar

Surface coal mine design has traditionally relied on graphic and analytic approaches for pit layout and equipment selection. A number of interactive graphic microcomputer programs have been written that aid in the design process in the academic arena and should also have industrial applications. The programs described include a drag-line cut diagram and production index calculation program, a downslope load scraper cut diagram and volume program, and an overburden volume and coal tonnage sequencing program.

Jan 1, 1988

By Joseph A. Zupanick

Methane drainage is a mature technology, now commonly practiced in many highly productive underground coal mines throughout the world. Universally, the practice of pre-draining methane will continue to grow as near-surface coal seams become depleted and mining operations are forced to exploit deeper reserves. These deeper coal reserves inherently have higher gas contents. In addition, increases in productivity and extraction rates have caused higher methane liberations per unit of time. As the cost of providing ventilation air increases, the economic justification for implementing a methane drainage program becomes apparent.

Jan 1, 2005

By Fernando Concha, Arturo Barrientos, María Cristina Bustos

Manufacturers referred to high capacity thickening as a filtration operation rather than thickening in spite of the fact that it is performed in thickeners and that conventional thickeners can be operated as high capacity thickeners by changing the feeding level and operate it in a different manner. In this work we derive a phenomenological model for high capacity thickening based on mass and momentum balances. The difference with a conventional thickening is the presence of a surface source within the variable domain. The model can be used to design, simulate and to develop control strategies.

Jan 1, 1995

By A. Raviprasad, B. Das

Copper ore from the Rakha Copper Concentrator (India) was successfully floated using LIX-65 NS as the collector. The beneficial role of this reagent was clearly demonstrated in hatch-flotation tests. From a feed containing around 1% Cu, it was possible in a single-stage flotation to obtain a 23.7% Cu concentrate with a recovery of more than 90%. The plant now uses rougher, scavenger and a two-stage cleaning process. The tests demonstrated that LIX-65 NS is superior to conventional xanthate for the recovery of copper from the Rakha ore.

Jan 1, 1997

By Anthony Busigin, Charlett Busigin, Colin R. Phillips

For the purposes of measurement and dosimetry of airborne radon daughters in uranium mines and elsewhere, it is important to understand their physicochemical state. This work deals with the chemical fate of 218Po in air. Extensive experiments were performed to determine the rate of neutralization, diffusion coefficient and fraction born charged of 218Po in air. The experiments were performed in a specially constructed apparatus of well-defined geometry. Careful control of experimental conditions made it possible to obtain more precise and detailed quantitative data than previously possible.

Jan 1, 1981

By Charles H. Arnold, Timothy Fallara, David A. Day, Paul H. Marshall

The Upper Scioto West Interceptor Sewer (USWIS), Parts 1 and 2, consists of approximately 7,128 meters (23,385 ft) of 328 cm (129 in.) diameter tunnel. The project ex-tends from the City of Dublin to Griggs Dam in the City of Columbus. The majority of the tunnel was designed for excavation in rock by TBM. The remaining portions span pre-glaciation formed valleys in-filled with glacially-derived sediments. Tunnel construction in one of the glacial till filled sections includes excavation by drilling and controlled blasting. The other section will be constructed by ground consolidation followed by excavation by TBM. This paper describes the methods employed to mine the glacial till filled valleys.

Jan 1, 1997

By Raul Z. L. Cançado, Virginia S. T. Ciminelli, Roberto Galery, Armando C. de Araujo

Brazil is presently among the seven largest gold producing countries in the world. This paper discusses the evolution of gold mining through the history of Brazil. It also gives a general account of the present practices for mining, processing and extraction of gold. Flowsheets of some selected plants are presented. The environmental aspects involved with gold production are also considered.

Jan 1, 1987

By S. Chunhui, W. Anbin, R. B. Cook

The Xicheng is one of China's largest lead-zinc (Pb-Zn) districts with known minable reserves in excess of 10 Mt (11 million st). The centrally located Changba-Lijiagou and nearby deposits are representative of the district. They consist of stratiform and stratabound zones of pyrite-sphalerite-galena mineralization within deformed, moderately metamorphosed Middle Devonian clastic and carbonate units. When considered with other similar districts that extend for several hundred kilometers to the east, a major episode of Devonian sedimentary exhalative mineralization is indicated.

Jan 1, 1992

By William J. Gregg

Mechanical testing results on oriented Devonian gas shale core throughout the Appalachian basin show a preferred fracture direction perpendicular to bedding. The preferred direction is generally parallel to the Allegheny Front, but is only coincidentally parallel with in-situ stresses in some areas of the basin. The strength of the preferred orientation of induced fractures decreases with distance from the Front. It is suggested that strain related to Paleozoic deformation is responsible for this mechanical fabric and thus the direction of induced fractures in laboratory tests may not be of use as indicators of in-situ stress orientations as previously suggested.

Jan 1, 1986