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By R. K. Singhal

Optimization of a load-haul system for a surface mine involves two processes. The first is proper selection of mining equipment compatible with the minesite job specifications and the second is an efficient utilization of this equipment. All things being equal optimal productivity and cost is achieved when the capacity of the hauling equipment is matched at all times with that of the loading equipment.

Jan 1, 1986

By Gunjan R. Bhattarai, Kumar Bhattarai

Recently, there has been an enormous increase of interest in artificial intelligence (AI), machine learning (ML), and their applications by researchers, government agencies, and the underground construction industry. Ultimately, these tools have the potential to automate the design and construction processes and boost productivity, safety, quality, and operational stability. This paper presents ongoing research and applications of artificial neural networks (ANNs), robotics, and 3D technologies in ground characterization, tunnel ground support prediction, risk projection and reduction, and productivity enhancement in TBM operations. The paper further investigates potential uses of AI, robotics, and 3D technologies in the underground construction industry

Dec 1, 2022

By William C. McBee

A sulfur concrete technology has been developed by the U.S. Department of the Interior, Bureau of Mines, in which chemically modified sulfur is utilized with suitable mineral aggregates to produce construction materials which are resistant to corrosion by acids and salts. This report presents a summary of the basic technology and results of testing the materials under actual operating conditions in 50 corrosive environments in 40 commercial plants. After 4 years of testing, there was essentially no evidence of material degradation or loss of strength. Regular concrete materials were attacked and in some cases completely destroyed under the same conditions. Testing is continuing to establish ultimate longevity and durability of the sulfur concretes. The materials are finding widespread applications in metallurgical, chemical, and fertilizer processing plants.

Jan 1, 1983

By G. Potts, K. Raiber, T. BoBo

Effective control of balling line circuits is a problem taconite companies have been dealing with for over thirty years. The sensitivity of balling circuits to changes in moisture, bentonite, concentrate particle size, and other operating parameters are the main reasons for control problems. This paper presents test results and describes the integration of existing instrumentation with a digital image analysis system on a balling circuit. This work has the goal of developing control strategies to automatically adjust water spray and bentonite addition, to optimize the size distribution on the roll screen and reduce the variability in control between balling attendants, resulting in more consistent greenball product quality.

Jan 1, 2003

By M. L. Harris, I. Zlochower, M. J. Sapko, I. E. Perera

Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effective, rock dust must be able to disperse as individual particles to inert. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anti-caking additives after being exposed to moisture and then dried. The dusts were exposed to moisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anticaking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Laboratory (LLL), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for one day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for six months. This report details the analysis and characterization of anti-caking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber. INTRODUCTION In order for a coal dust explosion to propagate, five elements are required. In addition to the fire triangle in which three elements are necessary to sustain a fire—fuel (coal dust), heat (ignition source), and an oxidizer (oxygen in air)—a combustible dust explosion requires dispersion of a dust cloud (pressure wave) and confinement of a dust cloud (underground mine entry) (1). Coal dust explosions can originate anywhere in a mine. For example, when a small volume of a flammable methane and air mixture is ignited in a closed end, the high-temperature gases rapidly expand to create a pressure wave, sometimes referred to as a “pioneer wave,” that may steepen into a shock wave as it propagates away from the ignition source. The shock wave produces a wind that disperses the dust preferentially from any elevated and exposed surfaces (roof, ribs, belt structure, cribbing, etc.). Factors that are known to affect the intensity of an explosion are the dust particle size, the location of the dust within the entry, the dust dispersibility, and the volatility of the coal dust (1). Particles less than 75 μm (< 200 mesh) in size are most reactive (2). Dusts that are located on the roof, ribs, and elevated surfaces are more readily dispersed than dusts on the floor. Therefore, application of quality rock dust in sufficient quantities is essential to inert coal dust and to prevent continued flame propagation. 30 CFR 75.402 and 75.403 require 80% total incombustible content be maintained within 40 ft of the face, and 30 CFR 75.2 defines rock dust acceptable for use in underground coal mines. It also defined that “when rock dust is wetted and dried, will not form a cake”.

Jan 1, 2019

By Thomas E. Howard

Engineers today face a tremendous challenge. Growing population and rising standards of living all over the world are creating unprecedented and accelerating demands on and for all kinds of technology. At the same time, the public is becoming more and more conscious of--and concerned with--the impact of technology on human welfare. The growing controversy over the Supersonic Transport is a case in point, It is clear that the modern engineer must expect to spend a growing share of his time considering this dilemma and evaluating the tools that are available to him, not only with respect to their adequacy for the job at hand but also their capability for meeting the increasingly demanding--and, in many cases, conflicting--requirements of the future. This meeting seems a particularly appropriate place to speculate about the future of mining technology. The summary of the state-of-the-art in surface mining contained in the papers scheduled for the International Conference, together with the recently published Surface Mining volume, constitute not only a major contribution to the technical literature but also form an impressive record of technologic progress. That record, and the advanced technology displayed in the exhibits, and to be discussed in the SME technical sessions demonstrate engineering achievement in which the mining community can justly take pride.

Jan 1, 1968

By George S. Austin

Adobe, dried mud bricks, have been used since before historic time in the construction of dwellings. Building materials are normally evaluated for thermal performance based on measurements known as R- and U-values. The R-value is an indicator of the ability of a wall to insulate effectively and the higher the R-value, the better it is as an insulating material. The U-value, or value of conductance, is the reciprocal of the R-value and reflects the rate at which heat is conducted through a material. But the "heat capacity of the wall" must also be considered. This measures the length of time that passes before a steady state of heat flow is achieved. The effective U-value measures both the resistance to the transfer of heat and the capacity to hold heat. These latter value make adobe a far more interesting as a modern building material that was formerly recognized.

Jan 1, 1983

By C. W. Hoffman

A fairly recent development in the field of particle separation is now under investigation to determine its value to the mining industry. The method employed is probability sizing through a vibrating network of decreasing screen openings. While probability sizing as such is not new, the possibility of using it for coarse, highly abrasive ores at high tonnage rates has only recently appeared to merit practical consideration. The advantages to be gained by the use of probability sizing vs. conventional screening methods are: reduced space requirements for a high capacity unit, fewer moving parts, more versatile product sizing selection, reduced maintenance requirements and lower power consumption.

Jan 1, 1968

By J. E. Murphy, Y. Topkaya, R. E. Johnson, B. R. Palmer, D. K. Dysinger, R. B. Bhappu, A. E. Clark

The U.S. Bureau of Mines utilized a central composite experimental design to investigate leaching kinetics of pure chalcopyrite in the sulfuric acid-oxygen system. The six factors studied were oxygen pressures of 150, 300 and 450 PSI, leach temperatures of 35O, 65O, and 95O C, oxygen-to-chalcopyrite mass ratios of 0.5, 1.0 and 1.5, leach times of 8, 16 and 24 hours, initial acid strengths of 0.6, 1.2 and 1.8 g H,SO,/g chalcopyrite and pyrite to chalcopyrite mass ratios of 0, 1, and 2. Chemical analysis and oxygen consumption measurements indicatedthat leaching occurs through three consecutive reactions. Temperature was the primary determinant of leach rate and solution acidity was the primary determinant of oxygen consumption, sulfur oxidation, and activation energy.

Jan 1, 1993

By Keith S. Liddell

he selection of mill design parameters to suit the applica­tion requirements can result in quite different operating parame­ters for each generic type of application, even though the basic mechanical layout of the mills may remain similar. The selection of the type and size of grinding media is very important to efficient and cost-effective operation, and to ensuring that the milled product achieves the required properties. Accordingly, the grinding media selection is seen as an integral part of the mill design. Consideration of the requirement for classification is important in order to achieve the optimum mill and circuit performance. This can lead to the circuit feed not being classified for a steady feed with minimal slimes and a low size reduction ratio. Feed containing on-size particles would be deslimed by open circuit classification. Closed circuit classification is performed where the feed fluctuates. The rheological characteris­tics of the circuit feed slurry can have an influence on mill performance, and needs to be allowed for. A common misconception frequently encountered is the belief that "a mill is just a mill". This is not the case with stirred types of mills, since the operating parameters selected for the mill can have a large effect on the product characteristics. For example, horizontal shaft high speed stirred mills have a com­pletely different grinding action to vertical shaft low to medium speed stirred mills, which results in large differences between the surface area produced at a given product size (Liddell, 1986). Hence, it can be misleading to apply test results or design procedures obtained from one type of mill to other types for scale-up. The Metprotech stirred mill, as applied in the mining and minerals industries, is a low to medium speed vertical shaft mill. The basic design has been discussed previously (Liddell, 1989). Currently, the largest mills that have been manufactured have an installed power of 400 kW. The largest chamber volume at this power is 6000 litres, containing IO t of grinding media. It is intended that the installed power will increase up to lMW as applications requiring larger sizes arise.

Jan 1, 1995

By Scott G. Britton

Today&apos;s coal mines are turning more and more to belt haulage as the key system to transport coal out of the mine. The advantages of using belt for both intermediate and main haulage are numerous. Belts are reliable high capacity haulage mediums that can be utilized at low operating costs. They are adaptable to rolls in the coal seam and can handle relatively steep grades. They are not noisy, operate with a minimum amount of labor, and are easily extended and retracted. Belts require the least power of any haulage medium, are easily controlled by push- buttons and interlocks, and present low fire and safety hazards. Belt haulage can also be the largest source of operational problems for mine management when not installed correctly. This chapter and Chap. 6 concentrate on proper installation of both the static and dynamic components of efficient belt haulage. This chapter looks at the static system component, composed of the belt drive, its installation and operation, as well as belt takeup and transfer point construction. These components do not change readily over the life of the installation, hence the term static system. Chap. 6 discusses the dynamic system of belt line construction, which includes belt splicing, breaking down and reanchoring the tailpiece, and extending the belt line, plus operational and maintenance items for belt operation. This chapter is divided into three major topics. The first is a general discussion covering the points necessary for designing an efficient haulage system; the second looks at installing belt drives, head rollers, and takeups, and the third discussion centers on installing efficient and effective transfer points along the haulage system. Each will address the design and construction issues facing the engineer or construction supervisor in charge of installing the system. Before looking at the static system, it may be useful to review some of the basic design factors and considerations of all belt haulage systems. The material usually carried on an underground belt is a mixture of raw coal and rock, commonly known as run-of-mine (ROM) coal. This mixture has certain material characteristics that guide the mining engineer to the final and proper belt selection. The characteristics looked at most frequently are: 1) Angle of Repose is the angle at which the material will freely make a pile. Most ROM coal averages a 35"-39" angle of repose. 2) Angle of Surcharge is the angle a pile will assume on a moving conveyor. This ranges from 5" to 15" less than the angle of repose in most materials. For ROM coals, 25" is the average angle of surcharge. 3) Flowability, which determines the maxi- mum cross-sectional area needed to carry any given material on a belt. It is measured by the angles of repose and surcharge of a material and also serves as an index of the safe incline angle for the belt line. These characteristics, plus practical engineering research and development work are defined by an organization called the Conveyor Equipment Manufacturers Association (CEMA) for most bulk materials. CEMA also provides a code for each classified material depending on the characteristics above and the subjective considerations of the average size to be encountered, the abrasiveness of the material, and any miscellaneous characteristics (oil resistive, corrosive, etc.) which may be important. For coal, CEMA (composed of member companies in-

Jan 1, 1983

By Nader Shahcheraghi, Verya Nasri, Mehdi Bakhshi, Ali Haghighat

An accidental fire load is one of the major loads considered in design of segmental linings in transit tunnel. Typically, a two-dimensional coupled thermo-mechanical finite element analysis (FEA) is conducted. The conventional approach involves using standard fire curves (temperature-time curves) which can lead to a significant overestimation of fire load and tunnel lining thickness in metro tunnels. The focus of this paper is on the cutting-edge approach, using 3D computational fluid dynamics (CFD) analysis of real train fires in metro tunnels and coupled thermo-mechanical finite element analysis (FEA) to accurately and cost-effectively design fiber-reinforced concrete (FRC) segmental tunnel linings for large-scale metro projects.

Jun 23, 2024

By Frank Sames

A recently developed model is used as a tool to optimize blast designs based on the continuing combination of full scale blast assessment and performance prediction. The use of this tool has allowed to evaluate present blasting practices and proposed designs through a better under-standing of the influence of the various blast parameters. The empirical model has a modular structure covering all aspects of blast performance including 30 fragmentation, potential rock damage and 30 muckpile profile prediction. The modules are assisted by a terrain model which is compatible to most mine mapping systems, and a blast design editor. The evaluation is summarized in a blast management module. Various studies have recently been undertaken using the model to qualify and improve blast designs with respect to wall stability, optimized fragmentation and muckpile distribution, as well as to the control of the environmental effects such as blast vibration and airblast overpressure. To verify the predictions of the modeling, full scale blast assessment techniques were used to qualify blast geometry, explosives and initiation performance, rock movement, muckpile distribution, near- and far-field vibration levels and airblast ovepressures. The model provides a tool to gain an improved understanding of blasting and blast control. The modeling results are presented in a visual form which allows simple comparisons of proposed blast designs. Additionally, the model can be used for detailed analysis and blast management.

Jan 1, 1996

By I. K. Kapageridis

Environmental management and planning requires the integration of large volumes of disparate information from many sources and the analysis of this information with efficient tools for assessment and evaluation. Effective methods of communication that allow interactive participation in the planning, assessment and decision-making processes are also very important. The VULCAN software package from Maptek (Pty) Ltd comprises a large number of 3D graphical tools within an interactive 3D interface called ENVISAGE. These tools are designed and developed to help engineers and scientists to identify and solve environmental problems. The combination of VULCAN 3D Software and the I-SiTE 3D Laser Imaging system leads to powerful solutions for environmental management. This paper presents the capabilities of this integrated system and its applications for environmental management.

Jan 1, 2002

By Aurel Goodwin

I chose the title "Let&apos;s Clear the Air" for this afternoon&apos;s presentation because it has two meanings, the literal and the figurative. Most of you know what MSHA is. Most of you know what MSHA does. And, for the most part, most of you know why. What I hope to accomplish today is to "clear the air" around our health standards, to clarify for you how MSHA views its congressional mandate under Title I Section 101(a)(6), (7), and (9) of the Mine Safety and Health Act. Asbestos, silica, radiation, noise, welding fumes, carbon monoxide, lead, hydrogen sulfide, nitrogen dioxide - the list of physical and chemical hazards encountered in the metal and nonmetal mining industry is as diversified as the industry itself, possibly even more so. In addition, miners are often exposed to several of these health hazards simultaneously.

Jan 1, 1980

By Charles T. Ford

Limestone neutralization of acid mine drainage has been proposed and examined as a method of treatment. However, limestones differ greatly in composition and structure. The reactivity of 14 selected limestones was studied, both by chemical and physical properties and by relative effectiveness in neutralizing synthetic and actual mine waters, and several guidelines for the choice of limestones are given. The particle size should be at least as small as 74 microns and preferably smaller. The most effective limestones are most nearly pure calcium carbonate. Stones which have a relatively low calcium con- tent but which contain calcite and have a large surface area are also effective neutralizers. Magnesite and dolomitic limestones are much less reactive. Disadvantages in using even the most reactive lime- stones for neutralization are indicated.

Jan 1, 1974

By Mogens Henriksen

In the past decade, numerous urge scale drilling projects have made use of reverse circulation air lift methods. Reverse air lift pumping can be established by injecting gas into a column of liquid; the subsequently decreased density of the gas-liquid mixture allows atmospheric pressure outside the lift conduit to establish flow. The rate of flow can be controlled by varying the gas to liquid ratio. A typical reverse circulation air lift system is depicted in Figure 1. Allen1 has described a number of reverse air lift drilling projects. Although cited examples are generally related to large diameter holes, the method has seen use in other applications such as sand dredging, chemical pumping, water well pumping and continuous coring. One particular benefit obtained with enclosed reverse circulation drilling is elimination of lost circulation. The required air/water ratio for pumping at a given submergence and lift has been established experimentally by Gibbs2. His data, however, do not reflect sensitivity of flowrate to air/water ratio. Further, in Gibbs&apos; work, air apparently is injected continuously along the column of water. This configuration differs from that used in reverse air lift drilling where air is injected at discrete points only. Gas lift theory has received considerable attention over the past decades. Orldszewski3 defined flow regimes in two phase flow. Griffith and Wallis4 determined relative velocities of gas to liquid. Two-phase flow has been studied extensively for oil transport in inclined and vertical pipes by Chierici et a15, Beggs and Brill6, and Gould, Tek and Katz.7

Jan 1, 1977

By H. I. Meyer

The mine is a large open-pit copper mine located near Tucson, AZ. Mining operations involve shovels digging at relatively fixed locations and haul trucks moving the muck to a primary ore crusher, a primary waste crusher, and directly to waste dumps. The total investment in shovels and trucks is some $100 million. Fig. l is a schematic drawing of the operation. A static method of truck assignment is used; i.e., each driver is given one particular shovel to serve until reassigned by the dispatcher. A dynamic system is one where trucks are reassigned after each trip. The problem is to compute a near optimum assignment of trucks for efficient operation.

Jan 1, 1979

By Michael J. Fiannaca

Disseminated epithermal gold metallization occurs within a breccia unit interpreted to be a submarine debris flow. Cold is associated with oxidized pyrite, fluorite, and jasperoidal silica. A minimum of 9 million tons of open-pittable mining reserves will be cyanide heap leached as run-of-mine ore at a rate of 1.0 million tons per year. Careful evaluation of the combined results of successive sampling projects has established the pit plan, mineable reserves, and process metallurgy of the operation. The sampling procedure utilized for a given test depended upon geological interpretation as well as the procedures, successes, and failures of previous tests. This paper summarizes the sampling and testing procedures of the development effort in light of the project goals and attendant problems in achieving them.

Jan 1, 1984

By E. McCarthy

"INTRODUCTION Talc is a hydrous magnesium silicate with the approximate elemental composition 4MgO.3SiO2.H2O. It is one of the layered phyllosilicates (like kaolin and mica) but it differs from these in that it is relatively hydrophobic. This is due to its unique crystalline structure whereby a brucite inner layer is sandwiched between silica layers and the adjacent silica layers have no interlayer bonding other than van der Waals forces. This allows talc to be sheared easily along this basal plane, and the surface is covalent not ionic. Talc occurs both as a relatively pure material (>90% talc content) and in conjunction with many other minerals in proportions all the way from 1% to 90%. At lower concentrations, it is often considered a nuisance mineral when it occurs with base metals like copper, molybdenum or nickel or with precious metals like platinum or palladium. It floats readily with these materials and often is suppressed using guar gum or carboxy methyl cellulose which will absorb along the basal surface and make it hydrophilic. Alternately if the reduced ore is hydrophobic, like MoS2, then a partial oxidation of the sulfide will convert the surface to a hydrophilic oxide and the talc can be floated away in a separate step. Talc in grades from 20 to 90% has been commercially exploited in a wide range of pigment (paint and paper), material (ceramic, construction and cosmetic), reinforcing (polymers and composites) and functional (pitch adsorbent, lubricating agent) applications. Initially these tended to be local or regional markets, but eventually with certain higher purity grades, cosmetic, polymer and ceramic applications became valuable enough to be national and trans ocean markets. TALC FLOATATION PLANTS This drove the need for higher purity grades of talc and initially this need was met primarily by ore sorting. This works well for certain deposits with well crystallized talc lenses, but for ores, such as those from widely available ultramafic deposits, where the liberation size is closer to 100 microns, sorting is not effective. That drove the need for floatation and the first investigations were published by Clemmer and Cooke of the US Bureau of Mines in 19362. The first commercial floatation plant was installed in Johnson, VT by the Eastern Magnesia Talc Co in 1937. The circuit is shown in the schematic (Figure 1). The ore was an ultramafic, serpentine derived talc; mineralogy was about 55% talc, 40% ferroan magnesite and 5% oxides, sulfides and other silicates. The oxides include hematite and chromite, sulfides pyrite and gerstorffite and silicates chlorite, serpentine and mica. After crushing, the ore was dry ball milled and then air classified to remove minus 325 mesh fines. The coarse fraction was further classified to cut at about 100 mesh and the fines from this were the feed to floatation. The -325 mesh (about 15% of the ore) was sold as a paint grade and the plus 100 mesh (about 25% of the ore) was screened to make an asphalt backsurfacing grade."

Jan 1, 2018