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By Dani Delaloye, Kas Zurek

Evaluating and selecting the appropriate excavation method is a key to the success of any tunnelling project. The benefits and risks of different methods should be well understood by the designer and communicated to the project owner to enable selection of a preferred method from a technical, social and environmental impact, cost and constructability perspective. For tunnels that have an internal diameter around 3 m, depending on the tunnel purpose and ground conditions, both microtunnelling with pipe jacking and tunnel boring machine excavation with a one- or two-pass lining may be feasible construction methods. Using the Ferry Road and Riverbend Combined Sewer Relief Project located in Winnipeg, MB as a case study, this paper will discuss the benefits and drawbacks of each method, including technical design, social, environmental, cost, schedule, and risk considerations.

Jun 13, 2023

By Fred T. Towne

Recent developments in fine grinding by the means of mechanical impaction are the result of continuing improvements in modern machine construction. This is especially true when related to the bearings and mechanically operated parts of impact mills. These improvements allow manufacturers to increase the speeds of the impacting members Most of the more common forms of size reductions, such as percussion, pressure, friction and sectioning, or cutting were at one time accomplished by human hands. These actions were transferred to machinery. Originally of limited application, their use widened as industrial materials and construction became more sophisticated.

Jan 1, 1965

By D. R. Forshey

Although the United States has the world's largest coal reserves, most of those reserves will require underground mining. Unless underground injury and fatality rates are reduced, the number of disabling injuries and accidental deaths will grow as coal production increases. The Bureau's Mining Research Program, designed to reduce the exposure of workers to hazards while improving productivity, is described. Major program thrusts are 1) re- moving the hazards or removing miners from the areas in which hazards exist, 2) developing ways to improve management decisions and mining skills so as to reduce the incidence of situations requiring human involvement in hazardous, emergency, or corrective tasks, and 3) improving, or at least maintaining, productivity so that both the tangible (dollar) and intangible (human) costs are reduced. In these ways, projected demands for coal can be met using resources without an increase in human suffering.

Jan 1, 1987

By R. L. Hills

America's industry uses about 44% of the total energy consumed by the nation directly as fuel burned in industrial plants or indirectly as fuel burned by utilities to provide electric power. In addition, industry requires raw materials or feed stocks derived from fuel sources or having fuel value. This represents about 11% of total U. S. energy consumption, bringing industry's portion to about 55%. Adding that portion of energy consumption required by the transportation sector to move raw materials, intermediates, and finished products, the total energy impact of industry approaches 213 of total U. S. consumption. It is obvious that American industry has the largest share in the task of balancing energy demand and supply. What are we going to do? -- We must increase the supply of energy and increase the beneficial results obtained from each unit expended. Both avenues, unfortunately, are limited in extent and speed. Increases in supply cannot occur without drastic and permanent increases in cost. These increases in cost are un- desirable and inflationary but do provide incentive for the rational businessman to expend the effort and money required to improve the effectiveness of energy in industry.

Jan 1, 1975

Engineering programs usually do not provide sufficient opportunities for students to develop written communication skills. The responsibility for developing those skills is frequently delegated to the humanities faculty, who in a single technical writing course are supposed to transform engineering students into proficient communicators. A general template which was developed for report writing in our senior level capstone design courses is discussed. Students have improved their writing skills by using the template. The writing assignments have provided the students the opportunity to write and revise more technical reports that communicate their design.

Jan 1, 1995

By Edwin S. Smith

One of the many responsibilities of mining engineers and mill superintendents is to provide for the safe and economic disposal of wastes (or tailings) remaining after a mineral has been extracted from an ore. The cost of disposal of these tailings exerts a considerable influence on the minimum grade of ore extracted from the mine. It varies to a great extent with each project and is dependent on many diverse factors, such as the local topographical, meteorolgical, geological and seismological conditions together with the applicable water pollution laws of the area. The process used to extract a mineral from an ore determines the physical characteristics of the tailings and thus is one of the more important factors to be considered when planning disposal facilities. Today's trends .in ore-processing operations complicate the problems of waste disposal: recently developed extraction methods result in the production of finer tailings, the use of lower grade ores produces greater volumes of wastes, while the enhanced land values in the vicinity of industrial plants preclude the former practice of spreading wastes laterally and force the expansion of waste desposits upwards to greater heights. The frequent occurrence of stability problems in waste deposits indicates that many mining organizations may not be employing current soil mechanics concepts and practices. One of the most spectacular, and often most disastrous, types of tailings dike failure is that resulting from liquefaction of the fine particles combined with a breach of the main retaining dike.

Jan 1, 1967

By R. Fernando

"The Office of Mine Safety and Health Research (NIOSH-OMSHR) currently is leading an effort in the development of the next-generation self-escape apparatus as part of the research imperative directed by the MINER Act of 2006. A multifaceted contract program over the past 3 years delivered key components and base breathing modules to form the basis for developing backpack and vest-style versions of dockable self-contained (closed-circuit) self-escape respirators with hoods (CCMERs). This paper outlines the current status in developing the CCMER that incorporates a docking and switch-over valve (DSOV) for seamless transfer from one breathing device to another, and a hood with an inner mask and speech diaphragm (HMC) for ease of donning, ease of use, and communication ability. Three versions of the CCMER are being pursued, namely: the CCMER-B, which can be worn as a backpack and incorporates the features of a miner’s belt; the CCMER-V, which is worn similar to a miner’s vest and attaches to a miner’s belt; and the CCMER-C, a breathing module cached along the escape route that can be docked to the -B and -V versions. Human factors considerations are a key element in the CCMER design, as it is to be continually worn by the miner while underground, and must be readily accessible for deployment when needed. The CCMERs are designed to be capable of being certified to 42 CFR part 84 standards, including sub-part O for mine use, and to meet MSHA permissibility regulations for use in underground mines. They are sized for sufficient oxygen capacities (Cap 2 and Cap 3 as defined in sub-part O) to yield a duration that is of practical use in a mine escape scenario. INTRODUCTION The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) is leading the development of self-escape apparatuses to provide breathing gas to mining personnel operating in the event of an emergency in various capacities underground in environments containing hazardous gas components. The Mine Improvement and New Emergency Response Act of 2006 (also known as the MINER Act) and input from the mining community called for the need to move Self-Contained Self-Rescuer (SCSR) technology to a next-generation status. In response to this need, NIOSH’s Office of Mine Safety and Health Research (OMSHR) established a strategic plan to develop key components and devices with help from external experts knowledgeable in breathing apparatus designs. The US Navy was identified as a key expert in this field through its extensive experience in diving apparatus and life support systems, and development work commenced through Inter-Agency Agreements with OMSHR. A contracts program was also launched with industry experts specializing in this field. This paper outlines the current status in developing the Next-Generation Closed-Circuit Mine Escape Respirators (CCMERs) that could be used for surviving and escaping from a mine following an emergency that renders the mine atmosphere irrespirable."

Jan 1, 2016

By Kan Aketa

The Japanese iron and steel industry has been developed remarkably, supported by the increase of steel demand. In particular, progress in various technical aspects of the ironmaking process, including burden materials, equipment, and operation has greatly contributed to the increase in productivity and the reduction of the fuel rate in blast furnaces. With the recent rise in the price of petroleum, the conversion of the energy source from oil to coke has resulted in a temporary increase in the fuel rate of blast furnaces.

Jan 1, 1982

By T. B. Szwilski

The paper gives an account of the development of a mine health and safety program in China from 1987 to 1996. The project was funded by the United Nations Development Program and managed by the International Labor Office (ILO). The objective was to strengthen the capability of the National Safety Training Center (NSTC), located near Beijing to train more than 2,000 engineers per year, and provide consulting and informational services to 39 safety training centers and coal mines. Presently China has the highest mortality rate in the world for coal mine operations, the greater incidence occurring at the many thousands of small, unlicensed underground mines.

Jan 1, 1998

By D. Gove

Several coal mines in Southeastern United State face the problem of multiple, very thin coal seams or seams adhering to interburden, and because of the strip ratio economics, these seams must be recovered. Over the past few years several mines have discovered a common method to solving these problems...use of a Caterpillar RR-250 Road Reclaimer.

Jan 1, 1995

By William G. Wilson

In the U.S. today a number of tentative synthetic fuel plants have been sited by a number of major corporations. Each of these for a number of reasons have deferred construction. The only synthetic fuel plants under active development are those being built with the Energy Research and Development Administration (ERDA) under the authority of the Non-nuclear Energy Research and Development Act of 1974 (Public Law 93-577). Under this Act in joint sponsorship with industry, a series of coal conversion pilot and demonstration plants are being built to produce environmentally acceptable fuels from high sulfur coals. Before entering into a discussion of the factors associated with the siting of the ERDA coal conversion program, the difference between a pilot plant and a demonstration plant should be explained. The terms pilot plant and demonstration plant iridicate a size of plant rahter than technology. A pilot plant will vary from an "add-on" to an existing facility to an independent unit. Demonstration plants are a wholly independent, self contained plants, capable of independent operation to demonstrate the environmenta1, economic, and technica1 feasibility of a technology. These plants are from one-third to one-tenth the scale of a commercial operation and often described as plus 1000 tons per day of coal consumption. Their purpose is stated in the Act (Section 6, (3)(E),) "to accelerate the commercial demonstration of technologies for producing syncrude and liquid petroleum products from coal: Provided. That the Administrator shall invite and consider proposals from potential participants based upon Federal assistants and participation through guaranteed prices or purchase of the products .... " In site selection and plant design it has been suggested that special interest groups should be allowed to dictate the site and specify the design. Under the present program the industrial partner who is contributing 50 percent

Jan 1, 1977

By Sam H. Patterson

Australia has led the world in bauxite production since 1976, and only the Republic of Guinea has larger bauxite resources. India has a small integrated aluminum industry, and deposits containing more than 1 Gt (billion metric tons) of bauxite were discovered in the 1970's. The Peoples Republic of China has large bauxite resources scattered in several regions, but it is a monohydrate type that is difficult to process for aluminum. Indonesia and Malaysia both have long histories of bauxite mining, and both have limited resources of high-grade bauxite. Districts containing bauxite resources in the 10 Mt to 150 Mt (million metric tons) range are scattered in countries along the eastern rim of the Pacific Ocean, on islands in this ocean, and on the western and northern rims of the Indian Ocean.

Jan 1, 1982

By Joseph D. Martinez

Salt, because of its plasticity, exerts a major influence in deformation. Resulting salt structures are common world-wide. A special type, salt domes, are associated with thick sequences of sediments deposited over salt. Their upward intrusion is generally thought to be in response to buoyancy. Mines in salt domes reveal an internal pattern compatible with large amounts of vertical flowage. Caprock, the end product of accumulation of anhydrite from salt dissolution, attests to long continued upward growth and concomitant truncation by moving underground waters. Concepts of modes of growth are evaluated and related to problems in utilization.

Jan 1, 1979

By L. S. Harris

The application of briquetting in various chemical, mineral, mining and metallurgical processes has been rapidly increasing in the past two decades. This is, in part, due to the development of new, more economical and higher performance briquetting equipment. Some of these developments, which have reduced the operating and maintenance costs,, include anti-friction bearings, hydraulically applied pressure enclosed and sealed gearing and bearings, tapered predensification feed screws, water cooling and materials of construction capable of operating at temperatures up to 18000F, and control systems capable of maintaining optimum briquette quality control. The briquets can be formed into almost any desired size and shape, To date, with present rotary briquetting presses in the 25 to 500 ton force range, briquets from 1/4" to 6" length are presently being used, some of which are illustrated in Figure No. 1. In force fed rotary briquet machines, these shapes are produced by feeding the material in between a pair of counter rotating rolls, as illustrated in Figure No. 2. The rolls have forming dies indented into their circumferential surface, as illustrated in Figure No. 3.

Jan 1, 1973

By Robert M. Cox

Systematic roof bolting has proven to be a very effective method of mine roof control; however, major roof failures still occur and roof falls still remain the number one occupational hazard of underground miners. Why do some bolted mine roofs fail, while the vast majority of bolted mine roof remains stable and safe to work under? Observations of numerous roof failures indicate that most of the major roof failures* are associated with either: 1) Jointing, faulting or other structural fracture zones; 2) massive shale beds of lenticular structure, or 3) thinly laminated sand-shales. The jointing and faulting present an obvious weakness in the roof rock structure; whereas, the massive shales and laminated sandy-shales create a roof structure with low shear strength and/or modulus of deformation. An observation of major significance is that most bolted mine roofs fail as a unit, and that the thickness of the fall is roughly equivalent to the roof bolt length (See Figure 1). In fact, several operators have experienced the phenomenon of an increase in roof fall thickness with an increase in roof bolt length.

Jan 1, 1973

By Laurence E. Snow

The conversion to the use of commercial grade ammonium nitrate (CGAN) for use in blasting at the Utah Copper Pit of the Kennecott Copper Corporation has presented unique problems for the Drilling and Blasting Department, In order to better understand these problems, a' picture of the Bingham Pit might be helpful. Some quarter of a million tons of ore and waste must be blasted daily in order to keep thirty-eight electric shovels operating. All material is blasted by "toe holes" of 24 to 28 feet in depth, drilled from prepared drill grades and sloped so as to bottom approximately 5 feet below the bench level. Horizontal spacing of these holes averages 22 feet, with exceptions being made where faults occur in the bank. These "toe holes" are drilled by 4-inch drifter machines, mounted on self-contained mobile drill units using .3-inch starter bits and bottoming at a minimum of 2 1/2 inches in diameter, "Toe-hole" drilling amounts to about two-thirds of the total drilling. In the higher bank sections of the Mine and wherever necessary, single rows of "down holes" are drilled to 28 feet in depth and spaced, on the average 23 feet apart. These holes are also drilled by a mobile drill. "Down hole" drilling amounts to about one-third of the total drilling.

Jan 1, 1959

By C. Cho

One problem with the application of neural networks to the multivariable control of mineral and extractive processing is deciding whether and how best to use them. The objective was to compare neural network control to more conventional strategies and find any advantages in terms of set point tracking, rise time, settling time, disturbance rejection, and other criteria. The procedure was to develop neural network controllers using both historic plant data and simulation models. We tried various neural network control patterns including both inverse and direct neural network plant models. These were compared to state space controllers that were, by nature, linear. For grinding and leaching circuits, a nonlinear neural network-based model predictive control strategy was superior to a state space-based linear quadratic Gaussian controller. We also learned the importance of incorporating state space into neural networks by making them recurrent--feeding certain output state variables into input nodes in the neural network. We concluded that neural network controllers can have better disturbance rejection, set point tracking, rise time, settling time, lower set point overshoot, and can be more foolproof and easy to implement in complex, multivariable plants.

Jan 1, 1996

By T. C. Rao

The quantum of coal fines below 6 mm in run-of-mine (ROM) coal has been increasing due to progressive mechanization of mining methods which has created a substantial incentive, worldwide, to develop suitable fine coal beneficiation techniques. The majority of the efforts have been directed toward reduction in ash/sulfur contents in clean coal. The beneficiation techniques may be broadly grouped as those based on specific gravity and surface property. The processes, which use heavy medium cyclone, water-only cyclone, concentrating tables, and spirals, belong to the former group while the latter group encompasses froth flotation, column flotation, oleo- flotation, and oil agglomeration. In almost all the gravity based techniques, it has been noted that a classification step prior to beneficiation is essential for effective treatment. In general, the effect of design and process variables on the performance of these units and also the quantification of the processes have been the main areas of research and development. In froth flotation, efforts throughout the world have been mainly to understand the effect of variables and to optimize the process. Quantification of the process has been attempted through kinetic studies and mathematical modeling. The efforts have led to the development of new reagents, machine designs, and flowsheets for a specified objective. The attempts so far with the column flotation and oleoflotation processes have indicated a great potential. Extensive R&D efforts are in progress to understand as well as to commercialize the processes. The efforts in the oil agglomeration process have been toward substantiating the inherent merits of the process by developing cheaper bridging liquids and technology to recover and reuse the oil to make the process commercially viable. Modeling of the process has also been attempted to predict the yield and size distribution of the agglomerates. This paper reviews and summarizes the recent developments in the science and technology of fine coal beneficiation processes. The current trends in R%D efforts for these processes are also highlighted.

Jan 1, 1987

By George H. Tousley

As a member of the vast fraternity of those that supply and service the mining industry, I can assure you that we are amused, amazed, and horrified at the poor drilling and blasting practices of a great number of operations. Yes, ?horrified?. After all, that is our product you are using and abusing. We all know that drilling and blasting is expensive. In some operations D & B costs may exceed excavating or hauling costs, or both. At any rate, it is the only portion of the whole operation that could be said to directly affect other costs. There is no argument that it affects excavating costs. If the overburden and/or product is drilled and hauled, it affects haulage costs. It can easily affect milling costs, if more or less fines is important. And poor fragmentation affects crushing costs. If scalping is done ahead of the primary crusher it can affect production. As has been pointed out, the D & B operation itself is costly, and therefore should lend itself to close scrutiny. Anyone that could immediately decrease haulage costs by 10% would be a hero with any mining company.

Jan 1, 1976

By Garrett R. Hyde, Aleksandar Stojsic

Introduction Economic pressures in the international marketplace have spurred advances in almost every facet of flotation. New developments have occurred in flotation chemicals, flotation machines, and in the application of automated process control technology to grinding and flotation. Many of these advances are the results of concerted efforts to apply the knowledge obtained from basic flotation research over the past 15 to 20 years, to develop industrial technology for the more efficient separation of sulfide minerals in real ores. Mining company executives and equipment manufacturers are being called on to make decisions for incorporating some of this technology into present operations. This discussion is limited to two developments now at the stage of being engineered into industrial scale operations. They are control of the electrochemical environment or redox potential of the slurry, and control of bubble size in column flotation. Potential economic impacts are noted. Froth flotation Froth flotation makes use of differences in the surface properties of finely ground minerals to obtain separation. If the mineral surface is water repellent, the mineral particle will stick at the air-water interface of a bubble and float. If a mineral surface is not naturally water repellent, a chemical collector is added to the slurry to make it so. The collector must adsorb on, and make water repellent only the mineral to be recovered, not the gangue minerals. To achieve this degree of selective adsorption, chemical modifiers may have to be added to the slurry. Modifiers include pH regulators, activators, and depressants. Electrochemical control One of the most significant developments in recent years in the area of mineral processing technology is the recognition that collector adsorption of sulfide minerals is an electrochemical process. Consequently, flotation of these minerals depends on the electrochemical or redox potential of the system. Many of the modifiers used to control various flotation processes are actually potential controlling reagents. For example, the role of well known depressants, such as cyanide, sodium hydrosulfide, and sulfur dioxide, is essentially to

Jan 7, 1987