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By Andrew L. Mular, Richard R. Klimpel

Optimization strategies of possible interest to mineral processing are reviewed and typical strategies initiated in processing plants to date are discussed. Both On-Line and Off-Line optimization procedures have been employed by industry, assisted either by operators or by digital computers. In every case, dollar benefits have accrued.

Jan 1, 1991

By C. P. Mangelsdorf, Richard A. Allwes

At the request of the U.S. Department of Labor, Mine Safety and Health Administration (MSHA), the U.S. Bureau of Mines evaluated the suitability of using tri-sets for protecting mine personnel in roof-fall prone areas. A steel-set arch provided by MSHA served as a basis for evaluating the performance of the tri- set. All tests and analyses were conducted according to the arch canopy test and design procedures developed by the Bureau. Theoretical resistance functions were established for the steel-set arch and tri-set and were representative of their experimental behavior. The resistance functions were used to determine the energy absorption capacity of the structures and to predict their dynamic response to impact loading. The dynamic tests demonstrated that the arch canopy design procedure is appropriate for tri -sets and yields conservative designs for both steel-set arches and tri-sets. As a result of this work, it is recommended that tri-sets may be considered for protection against roof falls, provided that the arch canopy design procedure is utilized for each application and that the principles underlying the design procedure are understood.

Jan 1, 1992

By J. D. Miller, C. L. Lin

"The use of 3D X-ray tomography analysis for plant-site characterization of coarse particles at a sampling rate of about 3 kg/min for particles ranging in size from 150 mm to 1 mm at a voxel resolution of about 150 µm is now possible. This is quite a significant advance in X-ray tomography technology and promises to be useful for plant-site coarse particle characterization—size, shape, composition, density, texture, grain exposure and mineral liberation—with a response time of minutes after receiving the sample. This paper discusses applications in the mineral industries, including the coal industry, aggregates industry, metal mining and the processing of industrial minerals.IntroductionPlant-site characterization of coarse particles at coal preparation plants, crushed stone/aggregate plants and mineral processing plants is needed to improve plant capacity, product quality and/or process efficiency. Not much online coarse particle characterization is being done at these plants. Only some limited information regarding particle size is obtained online from reflected light images using analyzers such as the OPSA, Split and WipFrag™ analyzers. Even the laboratory analysis of coarse particles has been difficult because of the large amount of sample required to ensure statistical significance of the results. During the past several decades, laboratory 3D characterization of particles from energy and mineral resources by X-ray tomography has been demonstrated and used to good advantage (Miller and Lin, 2004, 2009).Three-dimensional X-ray tomographic analysis has its origins in the medical services industry, where it is used to provide internal images of the human body. It has since been developed for nonmedical applications as well (Banholzer et al., 1987). Figure 1 shows a schematic diagram of the cone-beam geometry micro-CT system. In our case, X-rays from a microfocus X-ray generator are partially attenuated by the sample (a packed bed of particles) that is made to rotate in equal steps in a full circle about a single axis of the particle sample. At each rotational position, the surviving X-ray photons are detected by a planar two-dimensional array (image intensifier) large enough to contain the shadow of the specimen. These two-dimensional projection images are collected using conventional video technology. The video signal for each projection is then converted to a two-dimensional digital array by an image processing system. Finally, a threedimensional image is reconstructed from the collected set of projection images."

Jan 1, 2016

By Bo Hyun Kim, Mark K. Larson

Fault-slip bursts induced by mining activities can result in severe damage to nearby mine development. In general, engineers designing rock support in burst-prone mines not only need to consider stress redistribution resulting from excavation, but also dynamic loading that results from seismic waves generated by large mininginduced fault-slip events. In this study, we simulated dynamic waves in sedimentary rock from a blasting source and from a mining-induced-seismicity source using a Universal Distinct Element Code (UDEC) model with discrete fracture networks (DFNs). Our purpose was to investigate the stability of openings and the adequacy of existing support systems at an underground limestone mine in South Korea. A baseline model with only static loading was also simulated, which verified observed stability under such conditions. The results indicate that the current support system of shotcrete lining is likely to work well under dynamic loading caused by blasting. However, when the dynamic source was a far-field fault-slip event, the dynamic loading exceeded the support capacity of the shotcrete lining. Thus, if a mine is operating in ground with an elevated risk of mininginduced fault slip, mine engineers should consider seismic wave propagation and ground motion distribution from a remote, mining-induced fault-slip event to determine a suitable support design.

Jul 1, 2023

By W. Reed

During the 20th century, the increased emphasis on worker health and safety and the advent of new mining equipment and methods led to many changes in mine face ventilation practices. Efforts by government and private industry to improve and modify ventilation practices resulted in better health and safety conditions for workers. This paper examines factors that had a significant influence on mine face ventilation design during the past century. Several “milestone” events are discussed along with the impact they had on worker health and safety. Significant ventilation research efforts by government and private industry are presented. This brief ventilation history highlights innovative ventilation designs and a consistent commitment to mining health and safety.

Jan 1, 2007

By W. R. Reed

NIOSH continues to conduct respirable dust control research for surface mine blasthole drilling operations. Research areas have included testing variables (shroud leakage area, drill deck cross-sectional area, shroud height, collector-to-bailing airflow ratio, etc.) that have the most impact on respirable dust control, development of a dust collector inlet hood, development of a dust collector dump point shroud, and testing of a small diameter water separating sub. This paper summarizes the results of the aforementioned research that has been completed. Additionally, past dust control research for drilling operations of both underground and surface mines completed by the U.S. Bureau of Mines, created in 1910 and incorporated into NIOSH in 1997, is reviewed.

Jan 1, 2008

By F. L. Wilke

The prototype of an expert system, designed to assist layout planning of face operations, is presented. By specific combination of knowledge-based and conventional EDP techniques it has been possible to extend the known Kepner-Tregoe method up to the determination of mature layout solutions in difficult planning cases. It has been proven that the presented strategy - which can be applied to any kind of problem with similar structure - is apt to provide efficient EDP support for handling complex mining problems. Such support goes far beyond the purely numeric evaluation of envisaged alternatives.

Jan 1, 1989

By Z. Abdel-Khalek, Hassan El-Shall, S. Farrah, C. Boice

Selective adsorption and surface modification of minerals by surfactants is the primary step in the process of separating certain minerals with similar physical and chemical characteristics in the flotation process. In this study, microorgan- isms are used as surface modifiers for francolite and dolomite. Results of adsorption experiments with francolite and dolomite show that the microbes selectively adsorb to one of the minerals under specific operating conditions. In preliminary flotation experiments, it is found that the microorganisms enhance or depress flotation of the minerals leading to an increase in the efficiency of separation between the francolite and dolomite. The conditions leading to selective adsorption (surface modification) and subsequently to possible efficient separation of these two minerals are discussed in this paper.

Jan 1, 2002

By Joseph E. Worthington

The Haile Gold Mine is one of the earliest gold discoveries in the eastern United States as well as one of the largest gold producers from that region. Gold was first discovered in the gravels of what is now known as Haile Gold Mine Branch in 1828 on lands then owned by Colonel Benjamin Hale (spelling not the same). Small placer workings were immediately started and it was not long before the surrounding residual soils and saprolites were also found to contain gold. Following the presence of gold in the residuum eventually lead to the discovery of the underlying gold-bearing lodes that actually outcropped in saprolite form where not masked by heavy vegetation or a thin veneer of Coastal Plain sand. The earliest attempts at production, immediately after discovery, utilized slave labor, washing gravel and residuum from leased tracts that were 15m (50 ft) square. Several at- tempts at small milling operations were made during the en- suing decades, but there was really no substantial or successful production until the 1880s.

Jan 1, 1990

By Gunnar Nord

Shifting ground conditions when tunnelling often call for different methods of attacking the tunnel face. In order to overcome problems with local unstable soft ground in a hard rock tunnelling project the Boodex method offers a cost effective alternative. Boodex and variants of it is a combination of two well-known techniques, drilling with Boomer rig using Odex gear. It will give a steel lined hole ready for grouting and the steel pipe has a load bearing capacity that means that a spiling effect is achieved. In this paper the method and some applications will be described with possibilities and limitations.

Jan 1, 2003

By R. R. Fernández

Newmont Mining Corporation has been processing refractory gold ores by roasting since January 1995. The ores are refractory due to the association of the gold with iron sulfides, namely pyrite and marcasite, and the presence of carbonaceous components and is oxidized in an oxygen-enriched gaseous atmosphere. The structural characteristics of the calcine have a strong influence on the eventual recovery of gold by cyanidation. These characteristics are strongly dependent upon the roasting conditions, mainly the roasting temperature. Originally, the sulfides and carbonaceous matter were oxidized at a temperature that typically ranged between 535 and 560 °C. Controlling the roasting temperature within the lower and narrower range of 510 to 515 °C produced a calcine with a larger surface area(e.g. higher porosity), which resulted in a gold recovery increase of3.3 percent in 2001 equivalent to 5.1 million dollars of additional gross revenue. The new strategies of operating at temperatures never tested before are discussed. It constituted a great challenge to the control room operators for the lower operating temperature falls much closer to the ignition temperature of the sulfide ore and smaller and more frequent adjustments in operating parameters were needed to improve and maintain high gold recoveries. Based on the encouraging results that were achieved in 2001, a decision was made to install a “smart” process control system because the roaster temperature control was performed by manual inputs from the control room operators. The development and implementation of the control system to reduce or eliminate the temperature variability between the different control room operators commenced in June of 2002 and was fully operational by the end of October. Lower roaster temperatures were achieved (500 to 505 °C), which resulted in further increase of gold recovery by about two percent. The overall recovery increase equated to 8.0 million dollars of additional revenue for the first 10 months of 2002.

Jan 1, 2003

By I. Melik-Gaykazov, N. N. Melnikov, V. A. Fokin, S. P. Reshetnyak

Kola Mining Institute has been carrying out investigations of the possibility to steepen the walls of the Kovdor open pit with the design depth of 600 m. Steeping (up to 60°) wall angles is done by double height (24 and 30 m) benches with vertical slopes. One of the safety factors of mining with such walls is choosing the width of the safety berms preventing against rock falling from the slopes into the pit working area. The test on rock falling from 24 m benches has shown that vertical slopes are not more dangerous compared to the inclined(60-75°) ones.

Jan 1, 2003

By Barry A. Hillman

Respirable (PM-10) crystalline silica is regulated by the State of California as a carcinogen. The risk-management of this material by the State exemplifies the inherent problems in the development of regulations based on current risk-assessment practices. The influence of extremely conservative risk-assessment and risk-management can be expressed in economic impacts including the increased cost of production, reduced competition, increased prices, reduced employment and redistribution of income. This paper attempts to contrast theoretical risk- assessment and risk-management with current application using crystalline silica as an example. Based on health information pertaining to silica, the paper examines federal and State of California regulatory and public policy positions. Using current risk factors and empirical data for the Central Valley of California, the projected incidence of lung cancer in humans is examined. While such an analysis would project an extremely high incidence of lung cancer as well as silicosis, not a single case of either lung impairment has been recorded within the study area or throughout the world in the general population. This suggests that sound guidelines for the analysis of scientific information have given way to the assumption that virtually any information representing a substance as a carcinogen is to be considered valid with little or no qualification.

Jan 1, 1992

By L. H. E. Weyher

A mine is essentially a vast materials-handling system. All other systems found in the mine exist to one degree or another to support the materials-handling functions, from the cutting at the face to the hoisting in the shaft. In this chapter computerized planning of underground materials-handling systems will be examined by dividing this function into: (1) the planning of the production section, and (2) the planning of underground rail or belt haulage from the production section to the shaft, slope, or surface. While alternative divisions might focus on the different materials- handling functions, i.e., production, supply, and manpower transportation, historical computer analysis has focused on the various systems rather than functions. The emphasis in this chapter is directed toward coal mine applications; however, most of the programs and methods are equally applicable to other underground mines. Markedly different methods are encountered in each system, and moreover, marked differences exist in the nature and the degree to which the materials-handling subsystems in each interact with the environmental or support systems. The most intimate interaction exists at the faces where geologic, human, and machine performance factors are closely related and constantly varying. In view of this, the planning of the materials-handling systems for the face will usually stress flexibility, while the outby materials-handling systems will generally place decreasing emphasis on flexibility and more on system reliability, capacity, and cost effectiveness. Thus, hoisting and main haulage systems are generally designed and constructed as permanent installations and cannot be readily changed, whereas secondary haulage systems and face operations are relatively mobile. These differences may have considerable significance for the mine planner in making technical and financial comparisons of alternatives to provide the scheduled mine production.

Jan 1, 1979

By Bern Klein, Richard W. Lawrence, Scott Frostad

Laboratory and field scale kinetic testing was conducted to evaluate scaling up of laboratory data. Two 20- tonne (field) cells were monitored for internal temperature, pH, conductivity, volume and rate of flow, and water quality. On a surface are. basis, results showed sulfide oxidation rates obtained using 50-kg cells are more sensitive to changes in aeration than those from 1-kg cells. Correcting the laboratory oxidation rates for field temperatures with a pH 7 activation energy, which is in the field drainage pH range, returned oxidation rates an order of magnitude lower than the field cell rates.

Jan 1, 2000

By J. A. Finch, B. J. Huls

Accurate level detection is required to make full use of level in optimizing control strategies for flotation columns. Techniques based on pressure and electrical conductivity are compared. Pressure and conductivity profiles give good agreement on level. Level calculated from single and multiple pressure values became more accurate using, in order, one, two and three sensor locations. The level estimate remained in error, however, because, unlike the collection zone, froth zone bulk density varies with height. A conductivity probe continually updating the conductance profile is a practical method of obtaining an accurate level.

Jan 1, 1990

By Don Phelps, Christopher Tattersall, David McAllister

Located south of downtown Seattle, the Beacon Hill Station & Tunnels is the key section of the southern segment of Sound Transit’s proposed new LINK light rail system. This paper presents an overview of the design, which includes 4,300 ft of segmentally-lined bore twin tunnels and a deep mined station. With platforms located156 feet below grade, the station itself is only the second large-scale mined station in soil the US. Its complex geometry combined with variable soil conditions—sands, silt sand clays with slickensides—challenged the designer’s to come up with a SEM-based design that addresses the owner’s risk, cost and schedule concerns.

Jan 1, 2003

By A. D. S. Gillies, A. Haghighat

"A study has been undertaken at the Missouri University of Science and Technology (MS&T) limestone Experimental Mine to determine new fans set up and wiring options.to install additional mine ventilation capacity. Selection for main fans has been undertaken according to the mine’s required performance specifications and fan characteristics. Available fans for ventilating the mine are Joy and Alphair axial fans each of 24 kW each and two Spendrup booster fans of 12 kW each. The installation of main mine fans on the surface and underground entails numerous considerations. Design of a ventilation network for the Experimental Mine incorporating surface and booster fans has been accomplished using Ventsim Visual program software. The ventilation network has been separated into two segregated parts. A main surface fan and a booster fan have been used in each segregated part of the network. The mine has had a vane axial Joy fan in place for many years. The Alphair 4800 VAX 1800 full blade adjustable pitch vane axial fan was selected and installed as the other surface fan and eventual replacement for the Joy fan. Main surface fans have been connected individually to booster fans in series. The Alphair main surface fan has been installed vertically. Four different wiring options and related cost estimations for addition of the new main fans to the ventilation network have been considered. The analysis resulted in an innovative steel frame design used to allow the fans, when necessary, to be moved to the side of the shaft so that blast pressures do not damage the blades. INTRODUCTION Main fans are the heart of a mine’s ventilation network and play a key role in supplying required airflow (Haghighat, 2014). The Missouri S&T Experimental Mine has been developed in uniform limestone with few stratigraphic features. The mine floor is approximately horizontal and water drains well. A study has been carried out on MS&T Experimental Mine. Selection of main fans has been undertaken according to the mine’s required performance specifications and fan characteristics. Ventsim Visual computer simulation has been used to assist in design of the ventilation network. Wiring circuits, fan foundations and flexibility have been considered as the three main parameters for surface fan installation at the Experimental Mine. Two surface and two underground wiring options and three surface set up options and related cost estimates for the new surface fan system were investigated. Frequent use of explosives in the mine occurs throughout each year. Flexibility in changing the position of a surface fan is important. A number of options have been considered for the location of a vertical main fan positioned on the upcasting shaft. The mine is used for a variety of purposes and flexibility has a high priority amongst design considerations."

Jan 1, 2015

By D. S. Choi

The paper contains a subsidence measurement taken over a room and pillar panel of a mine located in northern West Virginia. A total of 72 monuments were used to determine a three dimensional view of mine subsidence. In addition, the results of measurements were used to compute ground strains with the use of a numerical model.

Jan 1, 1982

By H. Akgun, J. J. K. Daemen

Design of plugs for abandonment of boreholes and shafts may be governed by the bond strength between the plug and host rock. Presented in this paper are the results of push-out tests on two types of expansive cement grout plugs emplaced in rock salt. The average interface shear strengths range from 2 to 12 MPa. Peak shear stresses (assuming an elastic stress distribution along the interface) are up to eight times higher. Dissolution along the interface may be enhanced by clay inclusions in the salt and appears to reduce bond strengths. Application of the results to the design of plugs for larger openings (e.g., shafts, drifts, or boreholes) is discussed.

Jan 1, 1995