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By D. N. Madge

A description will be given of an approach to plant process automation based on the strategy of first developing an information system followed by later development of process models. The advantages of this approach over the unit process control will be outlined. Some insight will be given into the risks associated with this method. These risks can be shown to be primarily economic.' Some reference will be made to two Cominco installations in the interests of illustrating the generality of the information systems approach.

Jan 1, 1972

By Daniel McNamee, Wern-ping N. Chen

The Amtrak East River Tunnels include four tunnels, Line 1 to Line 4, which extend from New York Penn Station in Manhattan, under the East River to Sunnyside Yard in Long Island City. Since fall 2015, Amtrak has initiated a program to repair and reconstruct the century-old tunnels, including structural repairs of all the tunnels and reconstruction of the Line 1 and Line 2 tunnels. The reconstruction includes bench wall demolition and replacing and installing the following elements in the tunnels: direct fixation track, traction power, signal, communication, and tunnel fire/life/safety components. This paper provides design and site investigation challenges and knowledge gained from this program.

Dec 1, 2022

By Trenton Cohen, Joseph McDivitt, Shimi Tzobery, Joseph Sinacori, Scott Zylstra

The 2-mile Beach Interceptor Sewer Tunnel was constructed in 1954 to then-current mining and construction standards. Due to its lifespan and deteriorating condition it is now being stabilized and rehabilitated using conventional excavation and ground support. At its southern end, below the prestigious Three Arch Bay community, the original tunnel alignment passes under a historic landslide where the tunnel was sand-backfilled and capped by bulkheads in 1957 due to severe and caving ground conditions. Video footage of the existing 21- inch clay pipe showed that the pipe is severely damaged, which could potentially cause a catastrophic pipeline failure and sewage spill into the Pacific Ocean. This paper summarizes the thorough investigation and design process, tunnel realignment construction and monitoring, and the notable cooperation between all parties to overcome the project risks.

Dec 1, 2022

By M. Ghiani

Biohydrometallurgy originated, some forty years ago, from an environmental problem, namely the serious pollution of the Ohio river by acid drainage water coming from neighboring subbituminous coal mines. Studies aimed at elucidating the cause of the intensive oxidation of the iron sulfide (pyrite) inclusions of those coals, led to the discovery of a bacterium, Thiobacillus ferrooxidans (Temple and Colmer, 1951), capable of acting as a catalyzer, accelerating the otherwise very slow chemical oxidation of iron sulfide to rates many orders of magnitude higher. However, it is now recognized that the biotechnology of microbial mining dates back to 1963, when the ability of this bacterium to solubilize copper from sulfide ores was ascertained (Razzell and Trussell, 1963). Much research has been carried out on biohydrometallurgy over these last 25 years and is still being actively conducted all over the world. The interdisciplinary nature of this young branch of science and technology is reflected by the variety of experts involved: microbiologists, mining engineers, hydrometallurgists, physico-chemists, mineralogists, solid-state physicists and biochemists. This intensive research effort has provided a solid background on the fundamentals of this technology, although many important issues have still to be solved, amongst which the enzymatic mechanisms controlling biocatalysis of mineral sulfides dissolution, the influence of bulk- and surface solid-state physics of metal sulfides on dissolution mechanisms, the interaction of the various strains composing natural microbial floras. Their elucidation should permit the rationalization of biohydrometallurgical techniques and the optimization of commercial processes. Biohydrometallurgy has already achieved satisfactory results: copper recovery from submarginal copper sulfide run-of-mine ores (i.e. assaying less than 0.3% Cu) by in-situ, dump and/or heap leaching is successfully practised in many countries and uranium recovery through bioleaching is competitive with other leaching processes.

Jan 1, 1987

By J. C. Johnson

The problem of estimating pillar capacity in coal mines has motivated development of a variety of empirical equations. Most of these equations have arisen from experience and a very limited set of measurements that have, necessarily, been focused on particular regions or coal fields. Their applicability is often limited to a specific range of pillar sizes. This is of particular concern in the design of large gateroad pillars and small barrier pillars between panels. The result has been a variety of equations and equation coefficients that can calculate load estimates to size pillars. Inclusion of these equations in more sophisticated loading models, such as boundary element methods (e.g. LaModel and MULSIM) has been hampered by absence of a function that describes specific variation of coal strength within the pillar. A singular exception, to our knowledge, is a function corresponding to the Bieniawski pillar strength equation. Because of this, it is the only coal strength criteria inherently available in most boundary element models. This paper presents a general method for deriving local coal strength, as a function of distance from the pillar rib, for an arbitrary pillar strength equation. Integration of this function provides the strength of pillar regions, or cells, needed for boundary element models. The method is demonstrated for the Bieniawski, Maleki and Holland-Gaddy equations. The Maleki and Holland-Gaddy equations contrast strongly with Bieniawski as strengths are extrapolated to large pillars and barriers. This development provides a tool for incorporating any of the proposed empirical equations into a boundary element model, thereby allowing the analyst to choose the most appropriate equation for a particular region, coal seam and/or pillar size.

Feb 23, 2014

By C. Patrick

Longwall face-to-face transfers can cost over $100 per minute in lost production potential and $100,000 for personnel and supplies. Such high cost makes extensive planning and control of the transfer process a critical necessity for the economic feasibility of longwall operations. This paper reports operations research techniques used for the analysis and modeling of longwall face-to-face transfers. Transfer data has been collected from companies who operate over 30% of the total U.S. longwall faces. Comprehensive sequence networks of existing longwall transfers were developed; simulation models of transfers under varying conditions were generated; and, the economics of general transfers and time-cost tradeoffs in the transfer procedure were investigated.

Jan 1, 1993

By Frederick McNeill, Mahmood Khwaja, Benjamin Lundsted, David Polcari, Michael S. Schultz, Timothy Clougherty

The City of Manchester, New Hampshire, is embarking on one of its largest public works projects in history to construct a 12,000 foot long, large-diameter, conveyance tunnel through downtown Manchester. This area has challenging geology with undulating bedrock (granite, schist, and gneiss) profile overlain by fluvial deposits. Understanding the subsurface conditions is key to mitigating project risks, establishing plan and profile for the tunnel, and selecting the most cost-sensitive and technically appropriate tunneling method. This paper presents the project team’s approach for conducting the ground investigation, developing preliminary subsurface profile, and the considerations for selecting the tunneling method.

Jun 13, 2023

By James R. Jones

The tempo of air pollution control regulations has increased dramatically in the past few years. Because coal mining operations are frequently located in remote areas away from urban developments, specific regulations applying to coal mines have received lower priority and are thus only now being promulgated and/or enforced. Therefore, many mine operators are not yet familiar with the regulations and the impact upon their method of operations. Few have been faced with an inspector on the property sighting them for specific violations. Several of the Mid-western states are just now requiring permit applications to be submitted.

Jan 1, 1973

By E. L. Smith

The development of larger size flotation machines, which started in the 1950's and 19601s, is still proceeding. The largest mechanical flotation machines available today have unit volumes in the range of 38 to 42 m3 (1,350 to 1,500 cft). In fact, the motivating forces of increasing capital and energy costs and decreasing ore grades, which created the need for large flotation cells, not only still exist, but are becoming more critical. This paper reports the development of an improved mechanism for these large flotation machines. The starting point in the development of a new mechanism was the identification of design and performance features of existing machines where improvements were desirable. The result of this work was a mechanism which is an improvement over existing designs. This new design is characterized by an efficient overhung stator and a vortex profile rotor. The overhung design of the stator removes unnecessary and undesirable baffling in the lowest parts of the tank, while maintaining a quiescent froth layer. This results in lower power consumption and better pulp circulation and solids suspension. The vortex profile rotor acts as an efficient pump, with higher pulp recirculation rates as evidenced by the increased air dispersion capabilities, good solids suspension, and low power consumption.

Jan 1, 1982

By Kevin Schraden, Andrea Pezzi

environmental and social/political changes the world is currently experiencing. Three of major challenges facing the mining industry today are: water scarcity, unpredictable weather conditions that generate a risk of tailings dam failures as well as the correlating social pressure and government regulations that prevent the development of new or expanded tailings dam projects. It is estimated the total number of active, inactive and closed storage facilities globally is over 8,500 containing over 217 km3 of tailings (46% are from copper mining)1 which at some point will need to be addressed. Technologically, there are several solutions for tailings management, including conventional ponds, thickened tails, paste backfill and filtered dry stack tailings. The use of pressure filters, for tailings dewatering is currently being evaluated and often selected as the preferred technology where dry stacking is the chosen solution for residue disposal. This is mainly due to the pressure filters ability and flexibility to address and achieve the current challenging aspects of tailings processing including: • Extremely high capacities of >80,000 dry tons/day • Lower ore grades which require finer grinding and result in a higher amount fine fractions and clay content • Residual moisture targets required for the geotechnical specifications for dry stacking

Feb 1, 2024

By Marc Lonoff

Byproducts are more important to the copper mining companies than to the copper market. Copper ores frequently contain gold, silver, molbydenum and cobalt. With the increase in the prices of these metals copper mining has become more profitable. If byproduct prices remain high, additional firms will be attracted to the copper industry; the increased supply of copper will reduce the long-run copper price. However, this is unlikely to happen because the markets for the copper byproducts, especially molybdenum and cobalt, are small. Increased recovery from copper and other sources will depress the prices of these byproducts before the copper price is significantly affected. Should byproduct prices remain high the copper market will both settle at a lower long-run price and be more unstable in the short run. Since changes in the copper price do not affect the entire earnings of a multi-metal mine, the copper price must fall further before such mines reduce output in the short run. Higher byproduct revenues will make copper supply less responsive to copper price; shifts in copper demand will result in greater copper price fluctuations in the short run than they did before.

Jan 1, 1980

By K. J. Shoop

An analysis of an iron ore processing plant showed that its performance was affected by seasonal temperature variations, resulting in reduced grinding efficiency in the winter months. Laboratory and pilot plant studies were conducted to determine the cause of the observed loss of efficiency at lower temperatures. Experiments were divided into two groups: 1) Drop testing, which was performed to determine the effect of brittleness and frozen pore water on the breakage characteristics of the ore. 2) Wet grinding, which was further divided into laboratory tumble tests and pilot plant scale tests. Laboratory tumble tests were performed to determine the effect of temperature on the grinding of iron ore. This was done by varying the percentage of fines and percentage of metamorphic clay material added to the iron ore grinding charge. The pilot plant scale tests were conducted as a scale-up of the laboratory tumble tests and to determine the effect of temperature on slurry rheology, and how this changing rheology affected the grinding of iron ore. The combined results of drop testing and wet grinding were used to make some predictions of the performance of plant scale autogenous grinding. In drop tests the breakage characteristics of the iron ore had no noticeable change in size stabilities for dry and water saturated samples over the temperature range studied (-25°C to 25°C). The effect of frozen pore water was not observed due to the low apparent porosity of the iron ore. The addition of fines to the test charge caused a decrease in the amount of new fines produced for both the laboratory tumble tests and pilot plant scale tests. The production of fines further decreased when tests were performed at the colder temperature. The increased energy consumption at lower temperatures was dominated by rheology phenomena. The addition of metamorphic clay material to the iron ore test charge resulted in more fines being produced in the laboratory tumble tests. This was due to the metamorphic clay material grinding easier than the iron ore. This caused an increase in the amount of fines in the mill, which in turn, would prematurely slow down the grinding of iron ore because of an increase in the viscosity of the slurry.

Jan 1, 1995

By P. D. Rao

Chemical and physical properties of typical low-rank coal (LRC) ash are significantly different than bituminous coal ash. With the exception of extraneous ash, which is incorporated during mining or is due to ash partings within or between coal seams, LRC ash consists primarily of inherent ash that is bonded into the coal's organic matrix or finely disseminated mineral matter. This paper reviews the nature of LRC ash, both inherent and extraneous, and how this impacts the prospects of washing and utilizing LRCs. A literature review, as well as washability data, proximate and ultimate analyses and ash analysis of 25 Alaskan LRC seams are used as a basis for this discussion. The authors' recent research into the nature and distribution of phosphorous in an Alaskan LRC is also discussed

Jan 1, 1997

By Georges Cote, Ehsan Alavi, Eren Kusdogan

The City of Toronto's Coxwell Bypass Tunnel is currently being constructed by North Tunnel Constructors (NTC) ULC, a joint venture of Jay Dee Canada, C&M McNally Tunnel Constructors and Michels Canada. This project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five 20 meter diameter storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. 120 m of Starter tunnel and 70 m of Tail tunnel were excavated with roadheaders to help with the launch of the TBM and as part of the contract base scope work. JayDee Canada in Collaboration with Everest Equipment Co. developed an innovative approach to design and build a stand-alone Ring Machine Erector nicknamed Enterprise to erect precast segmental lining in Starter and Tail tunnels in lieu of Cast-In- Place concrete. This paper describes the design and provides feedback on the innovative procedure used to install the rings.

Jun 23, 2024

By D. J. Crawford

The Lucerne Valley Operations of the Minerals, Pigments and Metals Division of Chas. Pfizer & Co., Inca, are located about 5 miles south of the town of Lucerne Valley, California. These operations consist of several limestone quarries, a whiting plant which produces finely pulverized limestone products, a-kiln which produces granular quicklime and lime products, and maintenance shops, warehousing, shipping, and office facilities. Construction of the Lucerne Valley plant began in 1961 as the result of a decision to utilize large undeveloped reserves of limestone in that area. Quarry development was started in the following year; and by 1965, Lucerne Valley had become the principle limestone and lime facility of the Western Operations of the Minerals, Pigments and Metals Division.

Jan 1, 1967

By Dominique Francois-Bongarcon

The rational and optimal determination of the design of a mining exploitation is a very intricate and difficult problem : the parameters are numerous, some technical, some economic or technico-economic which cannot be fully controlled; beside, deposits are estimated from very limited information and the choice criteria are not always quantitative, the economic context has to be anticipated by several years, and even the technological limits can change tomorrow. So, although very clever and performing numerical algorithms have been developed in recent years for open-pit design, we consider that this problem has not really been solved satisfactorily until now. The reasons are that people have concentrated their efforts on informatical algorithmical problems, and have assumed that the technical and economical data are well defined at the time of the study, which is generally not true. In particular, the mere fact of assigning dollar- values to blocks in order to maximize the total cash-flow is generally unrealistic because of the uncertainty of the data used. Consequently, the significance of the unique pit obtained as a result of these algorithms is questionable.

Jan 1, 1981

By Kurt Wiener

A major process control system is in some ways like a complex organism. The extremities, (that is, field instruments) are exposed to many hazards and suffer malfunctions of relatively minor and repetitive nature. Here I equate a stuck valve or dead transmitter with a skin abrasion or cut. The maintenance and repair of the extremities can be done by technicians with basic but thorough knowledge of relatively few problems and their solutions. Here I equate with administering Band-Aids and aspirin. On the other extreme, when the master control device (such as a computer) fails, one does not attempt home remedies. A "brain" specialist is called in. It is, however, crucial that the patient be able to clearly describe his symptoms. Getting down to the case at hand, a complex system consisting of field instruments, instrument racks, interface equipment, and perhaps a computer, may require maintenance at all levels. At the field equipment end where physical damage, corrosive atmospheres, reconfiguration, and routine calibration checks are common, the customer has the opportunity to develop a competent staff of maintenance people. The relatively high maintenance activity assures competence through repetition.

Jan 1, 1980

By John D. Smith

This paper describes how a knowledge of inherent rock characteristics can aid the mining engineer in his design of a mining method for a massive domelike structure. The paper shows how the pertinent rock characteristics were measured and analyzed and how the data obtained was used for design purposes. This analysis was conducted in 1964 in a producing salt dome, since that time, mine management has tried certain of the recommendations for mine design changes. The results of such changes are presented.

Jan 1, 1968

By Anna Eleria, Joseph Welna, Jim Herber, Nathan Campeau

Constructed by stonemasons over 120 years ago, a portion of the Trout Brook Storm Sewer Interceptor (TBI) owned and operated by the Capitol Region Watershed District in Saint Paul, Minnesota, needed rehabilitation. A routine inspection of the 10-foot limestone block tunnel revealed degraded and missing mortar between the blocks, allowing significant infiltration and soil migration through the tunnel joints. Conditions, including damaged and missing blocks, were considerably worse in a 250-foot-long segment beneath a busy mainline railroad corridor. Barr’s solution included tuck-pointing to repair the mortar joints, shotcrete overlay, and construction of a hybrid cast-in-place/shotcrete “tunnel within a tunnel” to support the mainline railroad loads.

Jun 13, 2021

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

INTRODUCTION The majority of ground water flow models have been developed for large computer systems. Most of these operate under a batch mode of operation, that is, the data are input with a deck of punched cards. The advent of micro- and minicomputers over the last few years opens the possibility of adapting many of these large flow programs to the smaller computers. In general, this adaptation will require more computer time to run the program, but in many cases if the small computer is in-house, the overall cost may be less than that required for a large computer. There are also a number of peripheral devices that can be used to make the data input much easier. As an example, the use of a digitizer with a finite element or finite difference mesh reduces the data input time considerably; the use of a graphics terminal for display of the mesh immediately after it is developed shows immediately whether there are errors in the location of node points. DEVELOPMENT OF AN INTERACTIVE SYSTEM The finite element program, UNSAT2, has been used over the past several years by the authors for several ground water flow problems (Bloomsburg, 1977; Bloomsburg and Wells, 1978; Zahl and Bloomsburg, 1980). In the past these programs have been run on an IBM 370/ 145 computer under the batch mode of operation. One difficulty that has been encountered has been in determining the length of time step that must be specified for operation of the program. The problem is that if the time steps are too large, the program becomes un- stable and operation ceases. If this happens in the middle of the problem, the only alternative is to reduce the length of time step and repeat the entire run. This problem has been alleviated in other pro- grams by using a subroutine that determines the time step automatically. If the solution becomes unstable, the time step is reduced automatically and that portion of the solution is repeated. With an interactive system this can be done by storing the output pressures and restarting the program with the new output pressures. Under the batch mode of operation, there is an option in UNSAT2 that allows restarting of the program from the last point of solution, but this must be specified when originally starting the program. The interactive computer system that we use currently consists of a PDP 1 1 /23 with hard disk drive, CRT terminal, plotter, graphics terminal, digitizer, and printer. The computer has 256 K bytes of core storage and the hard disk drive will accept a 5.2 M byte disk. To run a large program on a computer such as this, some overlaying must occur; that is, subroutines are stored on disk and put into core storage only when they are actually needed for running the program. UNSAT2 required very few changes to run on this computer but some changes were necessary to take advantage of the interactive capabilities of the system. One of these changes consists of the development of a program called DBUILD to build the data file for running the program. This program calls for each piece of data by prompt statement and gives instructions for using the digitizer. The data are then entered in completely unformated form. The node points must be entered in order and the coordinates are determined automatically by the digitizer. The pressure readings or initial conditions on each node point are entered through the terminal. All element information also is entered through the terminal. After DBUILD is run the mesh may be displayed immediately on the graphics scope whereupon any error in node point

Jan 1, 1986