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By A. N. Pritchard

The development of vibrating screens over the last century has seen many variations to suit the exacting requirements of industry. Indeed, as each year passes, industry has presented the challenge to screen manufacturers of supplying larger machines than those used in the past and the question is often posed - what is the maximum limit? Not only must size or screen area be considered but excellence of performance in terms of screening efficiency must be maintained or maximized.

Jan 1, 1983

By M. Polat

A combined heavy medium-flotation process which incorporates the advantages of two widely employed cleaning methods, namely, heavy medium separation and flotation was used to achieve improved separation of coal from ash at fine sizes and to recover the heavy medium as a substantially recyclable product. The investigation was carried out in two successive phases. In the first phase, tests were performed to deter-mine the effect of different variables such as the medium density, flotation time, magnetite type, etc. on the efficiency of the process using in-plant samples from Homer City Coal Preparation Plant. In the second phase, the optimum conditions determined in the first phase were employed to determine the applicability of the process to a few Central Pennsylvania coals. It was observed that the process was very effective in recovering the magnetite. In most of the cases investigated, the magnetite was separated from the non-magnetic material at approximate-1 to 99 % recovery with a grade ranging from 95 to 99 %. The grade of magnetite decreased with increase in ash content of coal and with decrease in size of magnetite.

Jan 1, 1992

By Roger M. Buckeridge, Charles D. Reese, Silvio M. Martino, William T. Carey, Ansel H. Graham

FUNCTIONS OF RAIL HAULAGE SYSTEMS The principal application of rail haulage in under¬ground mining is in the movement of ore or coal pro¬duction from near the mining areas out to a processing plant. In some cases, such production haulage may end at a shaft pocket or slope belt conveyor transfer station, depending on the type of mine and the geo¬logical placement of the mineral being mined. Main-Line Haulage The basic reasons for choosing main-line rail haul¬age are high-tonnage production per shift and long haulage distances. The choice between rail and other systems, such as belt conveyors, is not easy and requires an integrated study of many factors: tonnage, distance, grade, product size, number of producing areas, ore reserve, safety, capital cost, operational and maintenance cost, and the mining system. Projecting a main-line rail haulage system for com¬parison with other systems requires a choice of many variables which are interrelated. The project must start with consideration of the mining system, tonnages per day, distances and grades, and loading and dumping conditions. Rail mine cars of different sizes and types are studied. High tonnage demands consideration of wider track gages. A suggested minimum for metal mines is 914.4 mm (36 in.); for coal mines, 1066.8 mm (42 in.). The choice of the train size should be governed by tonnage per shift, physical factors of loading and dumping, cycle time, and the number of trains that can be operated and safely controlled. After the size of the train is determined, the type, size, and specifi¬cations of the locomotive can be selected. The loco¬motive may be trolley, battery, or diesel; selection guides are discussed elsewhere in this chapter. The advantages of rail main-line haulage are high tonnage capacity, flexibility, reliability, safety, low operational and maintenance cost, and dual usage of the system (supply haulage, for example). The dis¬advantages are high capital investment, high installation cost, the requirement for more maintenance facilities, and restriction to certain ore reserves and mine pro¬jections. Supply Haulage Supply haulage is a basic requirement of any mine, but the type and volume of supplies vary with the type of mineral being mined, the mining methods, and the size of the mine. A mine developed for rail main¬line haulage gains supply haulage through the addition of a secondary track system to extend the main line closer to the producing areas. Additional haulage equipment, generally smaller, is also added. It is neces¬sary to design into the rail system more switch bypass points and train control systems. The track system standards demanded by rail main-line haulage con¬tribute to the reliability and efficiency of the supply haulage function, whereas a supply track system to supplement other haulage systems often suffers from poorer track and installation standards. When belt conveyors are chosen for production haulage, a rail supply haulage system is often installed rather than using rubber-tired vehicles for supply haul¬age. The conditions of the seam or ore body create these items for consideration: haulage grade of more than 6% favors rubber-tired vehicles; longer haulage distances favor rail; difficulty in maintaining a smooth roadway favors rail; and movement beyond the end of a rail system generally requires rubber-tired vehicles, making a single system rather than a dual system attractive. Although operation of a supply haulage system may be concentrated on a single shift of a multiple-shift mining operation, proper planning and supervision are required if the haulage is to be efficient. Often the newer personnel at a mine are assigned to supply haul¬age which may add to the difficulty of obtaining maxi¬mum efficiency. Supply haulage by rail offers the advantages of high reliability, lower maintenance, and high efficiency over long distances. The disadvantages are less flexibility, high installation costs, and rubber-tired vehicles for use beyond the inby end of track often required. Personnel Movement The efficient and comfortable movement of the miner to and from his work area has a significant effect on his daily output. Minimizing man-trip time also becomes more and more important as hourly wages increase. Personnel are generally moved over a rail system by one of three methods: a specialized personnel carrier to which a certain number of men who work in a certain area are assigned; a combination vehicle, used to carry personnel but also capable of being used as a light supply/utility locomotive during a working shift; and man-trip cars towed by a supply locomotive. The first and second methods are used in coal mines where long distances make speed and comfort important. The third method is more common in metal mines. Equipment Movement As mining equipment technology has advanced, many mining machines and their subcomponents have grown in size. This trend requires careful planning for adding specialized carriers to handle the movement of larger equipment. Continuous miners, longwall equipment, raise borers, and ventilation equipment are examples of machines which may be difficult to move and which require special handling. The selection of the weight, speed, and operating characteristics of supply locomotives used to move equipment is important. Larger mines may often justify a special group of loco¬motives for this application.

Jan 1, 1982

By K. V. Raj, C. A. Berry, A. T. Weakley, A. L. Miller, P. R. Griffiths, D. A. Parks

Diesel particulate matter (DPM) has been classified as a carcinogen to humans by the International Agency for Research on Cancer. As a result of its potential carcinogenic nature, DPM exposure is regulated by the Mine Safety and Health Administration. Currently, diesel emissions in the workplace are monitored by collecting the aerosol onto filters, which are then sent to a laboratory for thermal-optical analysis using the NIOSH method 5040. This process can take days or even weeks, and workers can potentially be exposed to excessive levels of DPM before the problem is identified. Moreover, the delay involved in getting the loaded filter to the lab inevitably means the loss of some of the more volatile organic carbon. To remedy this delay, researchers from the National Institute for Occupational Safety and Health are seeking to develop a field-portable, real-time method for measuring elemental and organic carbons in DPM aerosols. In the current study, the use of mid-infrared spectrometry was investigated. It is believed that mid-infrared spectroscopy is more suitable for use in a real-time field-portable device than thermo-optical analysis methods. This article presents a method for measuring organic carbon (OC) and elemental carbon (EC) in DPM for a broad range of OC/EC ratios. The method has been successfully applied to laboratory-generated and mine samples.

By Lon Santis, Gregory M. Rumbaugh, Christopher Mark

This paper examines the relevant theory, experience, and past practices relating to development mining near gas or oil wells. It addresses setback distance for both coal and stone room-and-pillar mining. This study also involved a review of accident reports involving well interceptions and downhole well surveys. It provides technical considerations for decisions regarding safe setback distances for development mining throughout the United States. The study’s scope is limited to mining near active or inactive (i.e., non-producing, abandoned or inadequately plugged) wells with known surface locations.

Jun 25, 2024

By Duane L. Abata

This paper discusses recent technology dealing with the use of computer graphics in the mining industry and presents a newly developed computer software package specifically designed for use in underground mining operations. This software package, developed under a United States Bureau of Mines contract, 1) displays mine ventilation schematics and other representative illustrations for a real time data acquisition system and 2) utilizes the Bureau-owned Minefire and Ventilation Code for display of ventilation and contamination predictions on the microprocessor system. The package utilizes a unique system of display indexing that provides a simple yet efficient method of recalling a series of mine schematics detailing an underground operation and an alarm acknowledgement scheme that provides an effective method of identifying problem areas which may exist in the mine network. The package was written in Fortran for a 64 kilobyte, Z80-based microprocessor-computer.

Jan 1, 1984

By R. J. Sweigard

Deep tillage is used widely as a Means of alleviating excessive soil compaction. There has been some concern that the voids created by deep tillage may collapse before a more natural soil structure develops, resulting in recompaction subsequent to deep tillage. A laboratory investigation was conducted to determine the feasibility of pneumatically injecting organic material into the voids during deep tillage to prevent any significant recompaction from occurring. Various amendments were injected into the soil in the laboratory using a small-scale ripping and injection system. Measurements were made of selected soil properties to evaluate the feasibility of this method.

Jan 1, 1993

By Josh Swank

Albert Einstein once said, ?the important thing is not to stop questioning.? In the mining industry, a lack of inquisitiveness may lead to a blissful ignorance but it certainly will not increase efficiencies. While one may claim necessity is the mother of invention, questioning and analyzing how methods and systems can be improved is the catalyst to discovering necessities. Understandably, when working in the middle of Canada?s oil sands, where trucks operate around the clock every day of the year, it is nearly impossible to pull the nose from the grindstone long enough to provide thorough analysis. But, fortunately, some manufacturers/inventors have assisted by examining the process and the ensuing headaches within this application.

Jan 1, 2013

By Sakshi Hazuria Anderson, Angela Binder, Oscar Jaime Restrepo Baena, Simit Raval, Sandra Nowosad

As the mining industry faces times of change, new challenges arise to ensure raw material supply for the younger and future generations. Different scenarios are currently shaping the way we mine and teach mining engineering. Led by an increasing demand for raw materials, net zero requirements for improving long-term operation performance, technological advancements such as automation and digitalization, safety improvements, environmental considerations and a need for social acceptance, mining is pursuing to change and adapt to these requirements at a faster pace. Such changing times raise new concerns, one of the most relevant is the lower number of students interested or enrolling in mining engineering and related fields leaving mining engineering as one of the less preferred career options between the younger generations. Nonetheless, it is essential to continue addressing and supplying the skill sets that are suited to the contemporary and future mining industry. To this end, globally, academia is currently undergoing several initiatives such as curricula updates and adaptation, up skilling, improving teaching practices and techniques, including e-learning techniques, enhancing industry-academia and inter-university collaboration, and much more. In countries like Australia, where mining plays a crucial role in the economy, the need for curriculum updates is more pressing than ever. As the mining industry evolves with new technologies and sustainable practices, there is a growing demand for a workforce skilled in these modern approaches. Recognizing this necessity, universities such as the University of New South Wales and Curtin University have taken significant steps to revamp their educational programs. By updating their academic offerings, both universities aim to equip graduates with the necessary skills to drive innovation and sustainability in mining, supporting Australia’s development as a leader in this critical sector. Moreover, the selection of topics that drive curricula update and the focus of the research institutions in mining engineering must extend beyond mere technological and technical aspects to include social and ethical dimensions. In this context, the Universidad Nacional de Colombia, in association with the Colorado School of Mines, has introduced the topic of Humanitarian Engineering (HE) in 2020. HE is a socio-technical approach that focuses on developing engineering solutions that promote the sustainable development of communities addressing their basic needs and aiming to improve their quality of life (10, 18). By focusing on sustainable development, community engagement, and equitable resource distribution, HE helps the industry build positive relationships with stakeholders, reduce conflicts, and foster social license to operate. As the mining industry seeks sustainable and socially responsible practices, future engineers require training in this area to understand the broader impacts of their work, fostering a mindset that prioritizes community well-being and environmental stewardship alongside technical proficiency.

Feb 1, 2025

By R. Brown, A. J. S. Spearing, M. Treinen, M. Theisinger

The mining and use of coal creates a significant amount of waste material that needs to be safely disposed of. It is likely that in the medium term, the Environmental Protection Agency (EPA) in the U.S. will categorize all such products as a new category – special waste. This would make the materials subject to many of the requirements for handling toxic waste, which will complicate the disposal of such products and significantly increase the disposal costs. Underground disposal would, therefore, seem to be the obvious solution, especially if the placed material can have low or no permeability, so that water table pollution does not present a serious long-term issue after placement. Significant additional advantages could be derived from this backfilling, including the reduction or elimination of surface subsidence, increased extraction, reduced surface waste disposal footprint and the elimination of explosion-proof seals in worked out areas. The research using a specific coal waste product as a typical example proved that the method of placing the backfill at a high density with low permeability is technically viable, but it must be made more cost effective and the other potential benefits quantified and costed in order to present a true comparison.

Jan 1, 2010

By D. Berberick

Hecla?s Lucky Friday Mine is a deep, underground producer of silver, lead and zinc in the Coeur d?Alene mining district of northern Idaho. Main access into, and production from, the mine is via the Silver Shaft, a 5.5-m (18-ft) diameter, concrete lined shaft sunk by J.S. Redpath to an original depth of 1,890 m (6,200 ft) in the early 1980s. The shaft is divided into four compartments (Fig. 1), with sets made of 225 mm x 175 mm (9 in. x 7 in.) hollow structural section (HSS) steel buntons and 150-mm x 150-mm (6-in. x 6-in.) HSS dividers spaced every 4.5 m (15 ft) down the length of the shaft. Two skip compartments on the east side of the shaft are equipped with 125-mm x 150-mm (5-in. x 6-in.) HSS steel guides and 9-t (10-st) skips with three deck trailer cages for men and materials. The west side of the shaft is divided into a manway, and a fourth compartment that was originally designed for a service cage. Shaft services consist of a 250-mm (10-in.) a compressed air line and 150-mm (6-in.) sandfill line along the south side of the shaft, and 250-mm (10-in.) discharge (gray) water and 150 mm (6 in.) fresh water lines on the north wall. The mine?s primary 13.8 kV power lines, as well as communication lines are located on the west wall of the shaft. The production hoist is a 3.7-m (12-ft) diameter, double drum, double clutch, 2,238 kW (3,000 hp), direct current unit equipped, at the time, with thyristor drives. The 30-year-old drives would prove to be problematic during the rehabilitation project, leading to an upgrade to modern ABB drives later in the project, after the shaft rehabilitation was complete. The shaft had been subjected to the typical wear and tear of 30 years of operation, including intermittent sandfill and muck spills, and, in the lower areas, some corrosion. During those 30 years, the west compartment, originally designed for the service cage, could only be accessed from a work deck on top of the skips or from the manway.

By Myles E. Robinson

During the last decade there were pronounced changes in the competitive pattern of the fossill fuels It is proposed to trace these trends and describe inter-fuel competition, first as it relates to the economy as a whole and then more specifically to examine competition of the fossil fuels as these share the electric utility market. Table 1, Competitive Fuels and Water Power Used in the United States, 1950-1959, shows the growth in the consumption of coal, oil, gas and water power 'during the past decade. Uses which are not directly competitive among the fuels, such as tractor fuel, carbon black, and consumption of petroleum products in the making of synthetic rubber, have been excluded from these statistics. The experience of the three fossil fuels in competition since 1950 shows natural gas expanding more rapidly, than oil by roughly twice as much, 219.0 percent' compared to 124.1 percent growth in B.t.u.s of oil consumed in the ten-year period. Percentagewise, water power little more than held its own, and coal, including anthracite, actually decreased more than one-fifth.

Jan 1, 1961

By Sadegh Elyasi

TBMand roadheader are two dominating excavation machines in underground tunnelling projects. The performance of these two tunnelling machines has been reviewed and analysed individually by many researchers from multiple points of view. However, there are almost no studies that have made an extensive comparison between these two machines, mostly from financial points of view. The current study is intended to characterize both financial and technical status of these two mechanical tunnelling machines in one of the biggest coal mines in Iran. The main objective of this study is to define the best method and equipment that meets a predefined economic goal, which is mainly to maximize the net present value. To this end, a technical and financial model based on the geomechanical and financial parameters involved in the project has been prepared and the financial part of the project has been carried out by applying COMFAR III financial analysis software. Subsequently, a sensitivity analysis of the model was conducted in order to evaluate the effect of involved parameters on the project. According to the results, a roadheader has better economic justification than a TBM, while the TBM has a better advance rate than the roadheader.

Feb 12, 2021

By Jay F. Colinet

Coal workers’ pneumoconiosis (CWP), commonly known as black lung, is caused by the inhalation of respirable coal mine dust and is a disabling and potentially fatal lung disease with no cure. Historically, CWP has taken a tremendous human and financial toll in the US coal mining industry. Recent health surveillance data indicates that CWP continues to occur at elevated levels. Respirable coal dust exposure must be controlled to prevent the development of CWP. The Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH) conducts laboratory and mine-site research to identify control technologies that can be used to successfully reduce respirable dust levels. Various technologies, using multiple methods of control, can be applied in order to reduce dust levels. An overview ofCWP’s impact and a general methodology for controlling respirable dust in underground coal mines are discussed in this paper.

Jul 30, 2020

By James W. Estep

The sulphur shortage that has occurred in the past two years has directed attention more and more toward sour natural gas reserves, Wellhead values of sour gas vary widely depending upon the acid gas composition, location, market conditions, and necessary processing charges. Preparation of a saleable residue gas is considerably more involved and expensive than that normally encountered in treating a sweet gas. Recent revisions in sales gas specifications have increased capital costs and processing charges. The presence of hydrogen sulphide and carbon dioxide in a natural gas contributes to shrinkage factors that may approach 50%. Fuel required by the gas sweetening process and sulphur slant tail gas incineration also contributes to a further reduction in the volume of residue gas available for sale. The additional processing facilities involving gas sweetening, mercaptan removal, expanded utilities, sulphur recovery and sulphur handling, all demand additional operating and maintenance staff. A favorable sulphur market under certain conditions may justify the processing of sour gas whereby sulphur is either a by-product or a co-product, Five typical cases involving different compositions of sour gas are presented for evaluation. Capital costs, operating problems, and operating costs are presented in detail for full economic evaluation

Jan 1, 1967

By S. R. Titley

Carbonate-hosted massive sulfide (60%) ores of the western Cordillera compose a distinct class of deposits although they vary widely in detail and perhaps genesis. They have been important sources of lead, zinc, copper, silver, gold, and more rarely, molybdenum, tin, and tungsten in complex mineral assemblages usually dominated by pyrite. They occur as concordant stratiform bodies, as discordant mantos, and as chimneys crossing tens of meters of section; many are associated with faults and breccia bodies. Environments of formation of carbonate hosts range from craton basin to shelf with ages from Proterozoic to Cretaceous; in many instances, dating has shown mineralization to be significantly younger than hosts. Temperatures of formation determined for many deposits are high (200°-400°) and many districts are centers of igneous activity manifested by dikes, sills, and stocks. However, direct cause and effect relationships have been difficult to establish. Many important problems attend the renewed interest and study of these deposits and include questions of metal-sulfur sources, metallization processes and histories, geological controls at all scales, and relationships to broader patterns of metallogeny.

Jan 1, 1985

By P. H. S. W. Kulatilake

The presence of discontinuities strongly affects the mechanical and hydraulic behavior of rock masses. Joint geometry networks play a vital role in civil, mining, and petroleum engineering projects associated with jointed rock. The need for a realistic representation of joint geometry in rock masses has been recognized. The first part of the paper shows how to build three-dimensional stochastic joint network schemes and also shows how to perform validation studies for these schemes using joint data from the Stripa mine, Sweden. Due to the existence of complex joint patterns, mechanical behavior of jointed rock masses usually exhibit scale effects and an-isotropic properties. A correct understanding of the mechanical properties (strength and deformability) of jointed rock masses is important for designing and performance estimation of structures build in and on rock masses. Beyond a certain volume, the mass proper-ties of the rock may remain essentially constant with respect to the effect of joints. This minimum volume may be used as the element size to represent the equivalent properties of a statistically homogeneous rock mass volume which contains a significant number of joints. This volume may be termed as a "Representative Elementary Volume" (REV) and may be of great importance for engineering purposes. Investigations are underway at both the 2D and 3D levels to look into the possibility of establishing relationships between REV mechanical properties and joint geometry parameters. Recently developed joint geometry modeling schemes are linked with existing distinct element codes (both 2D and 3D) to create a stochastic/deterministic stress analysis approach in achieving the goal. Results obtained so far in this direction are presented in the second part of the paper.

Jan 1, 1992

By J. E. Jennings

The problems of slope stability in open-cast mines are examined. A criterion, the instantaneous stripping ratio, is suggested for use in the design of pit slopes and as an index of control at all stages of the exploitation of the ore body, This criterion may also be related to safety and to the maximizing of profits. Two approaches to safe design of slopes, one from the point of view of soil mechanics and the other from the point of view of rock mechanics, are described and critically compared. The effect on slope stability of the regional tectonic stress field is discussed. Explanation is given of the application of the Terzaghi effective stress concept to problems in both soil and rock environments, including possible effects when borehole deformation techniques are used to measure stresses in rock in situ.

Jan 1, 1963

By P. J. Cook

Comminution is one of the fundamentals of mineral processing, requiring large expenditures to be made on capital equipment, installation, power and maintenance. The trend toward lower grades and higher operating costs, mean mining operations are becoming increasingly marginal. The challenge is to improve and more importantly, utilize crushing and milling technologies that provide for reduced capital and operating costs whilst providing increased unit efficiencies. The Svedala Barmac Autogenous Crushing Mill presents such an opportunity by providing many of the cost savings and production increases required by its ability to produce a finer mill feed size and realize reduced energy consumption. This paper briefly describes the operation of the Svedala Barmac Autogenous Crushing Mill and reviews its benefits towards improving the efficiency of crushing and milling operations.

Jan 1, 1999

By David T. Kao

The energy situation the world faced during the decade of the Seventies resulted in actions throughout the free world to reduce its dependence on OPEC oil. Many nations heeded the indicators early in that decade and commenced efforts to reduce their oil requirements. Those nations which did not heed these warnings had the message brought to them more emphatically in the last portion of the decade with the further rapid and continuing rise in prices of OPEC oil. Furthermore, the demonstrated unstable nature of large oil-producing countries has made it clear to all free world nations that their energy demands of the future must be provided for by some more stable and assured supply. Now, early in the decade of the Eighties, we see the need for expanded use of coal as an energy supply to be essential. The result in 1980 and 1981 has been a great increase in demand for steam coal worldwide. In essence, a new business for the United States has developed in steam coal export. In the United States, the large growth in foreign demand for our steam coal is now well recognized and documented. A major impediment in meeting this growing demand became abundantly clear in 1980. This impediment is the congestion existing at U.S. coal export ports. With the recognition of this constraint, a plethora of activity has been observed in announcements for alleviating the problem by improving and expanding current export port facilities. In addition to improvement and expansion, an abundance of totally new facilities has been announced in an effort to find ways to meet this large demand in the new business of steam coal export. This is needed; and hopefully, many of these plans will be translated into action. While total implementation of all stated plans is not expected, much of the implementation depends upon large- scale dredging, large waterside ground storage sites, and improved handling equipments in the conventional type of export ports. The time and capital required for implementation is great, and environmental problems associated with dredging are substantial. Host significantly, and unfortunately, implementation that does include dredging our ports will still not permit use of the truly large colliers of 140,000 DWT and greater, which are evolving as the "state of the art" in long-distance sea transport.

Jan 1, 1981