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By C. K. Skokan

Various geophysical tools have been tested over the last eight years to evaluate their usefulness in defining damaged rock zones in an underground facility at the WIPP site in New Mexico. These tools include direct current and frequency domain electrical methods and seismic tomography. The electrical measurements show a "drying rind" to exist around older excavations. Seismic tomography confirms that a rind of lower velocity has developed along walls. In combining these tools, a monitoring program has been proposed to observe long-term changes in bedded salt. Results from the monitoring of electrical data over a 2-year time period illustrate the applicability of the technique in an underground environment.

Jan 1, 1993

By Randal J. Barnes

The January 1988 issue of Engineering and Mining Journal includes two short articles on blasting practices in surface gold mines (Anon., 1988 ; Carr , 1988). A reader of these articles learns, among other things, that a "12 x 13 ft" blasting pattern is used at the Carson Hill Mine, and a "17-ft burden and 18-ft spacing" is used at Echo Bay Mineral's Borealis operation, while at Mascot's Nickel Plate Gold Mine "ore shots are on a 10 x 10 ft" pattern. Like a new edition of the World Book Almanac, these articles are overflowing with useful tidbits of technical data; but, they never mention why the particular blasting patterns were selected. A survey carried out during the Winter of 1988 at six surface gold mines in the western United States also failed to produce a satisfactory answer. The responses from mine planning engineers to the question "why is your blasting pattern X by Y", reduced to "we use X by Y here because we used X by Y at our last operation, and it worked ok." Certainly, with the available decades of experience and professional practice in blast holes design, rock fragmentation in surface mines has been thoroughly investigated. However, and this is the central issue, fragmentation of the rock is not the primary purpose of most rotary drill holes in surface gold mines. Quoting senior mine engineers from companies operating, three of the richest surface gold mines in the world (AMAX Gold, Homestake Mining, and Gold Fields Mining)

Jan 1, 1989

By M. A. Pipke, C. M. Brown

The semiautogemus grinding circuit at the Utah Mines Ltd., Island Copper operation, located on Vancouver Island, British Columbia, is described. Since startup of the operation in 1971, grinding circuit throughput has been progressively increased from the initial design rate of 90 000 (99,000) to the current average 45 000 t/d (49,600 stpd) of porphyry copper ore. Key developments ad modifications in operating and maintenance practice that have contributed to this increase are reviewed.

Jan 1, 1987

By T. R. Ley

"RELIABILITY & SAFETY – TOGETHER. REALLY? I was starkly reminded of the challenges facing by the coal industry while talking with a number of senior mining executives. One said to me: “Safety is the #1 priority in our organization but of course, dollars are very, very important!!!” A coal mine worker at the Bluefield Coal Show claimed: “We know our equipment is bleeding hydraulic fluid all over the place but all that matters is getting the coal out”. We all understand. We want our people to go home safely at the end of the day but the coal industry is bleeding – fluids, dollars and real blood. An issue getting plenty of buzz these days is equipment reliability – in mining too! Achieving an optimal return from the massive investments in equipment is a critical requirement for success within a capital intensive industry like coal mining. You can cut costs by scrimping on maintenance, scavenging used parts and downsizing. Or, you can save money by being smarter with your asset management processes. Can we afford to spend money on both safety and reliability? Is one more important than the other? Many leading edge companies from a variety of industries will tell you that you can’t just cost-cut your way to profitability - or even survival. You need to systematically improve the effectiveness of your business. Do reliability and safety both have a place in improving the performance of the coal industry? According to Ron Moore, of The RM Group, the answer is emphatically YES! Ron says: “If you believe in safety, then you MUST believe in reliability and, more importantly, have the appropriate policies, systems, practices and measures in place. If you want lower costs, you must get your processes right. Simple cost cutting will remove resources from your system without changing the underlying system design, and performance will likely deteriorate.” Figure 1 shows the 5+ year results of a large manufacturing company. When plants are running well (high Asset Utilization), then injuries are less likely. Figure 2 plots data from a number of manufacturing plants. If you want sustainably lower costs get your reliability processes right. But these are manufacturing companies, not coal mining operations! It doesn’t matter. The fundamentals still apply. Mining industry thought leaders tell us that manufacturing is 20-30 years ahead of us and we need to learn from them – and do so quickly. Leading companies, no matter the industry, think in terms of operational excellence. They see this as the meshing of people, process and technology to achieve optimal results. Safety and reliability go hand-in-hand. People and equipment are different – but only to the extent that each requires its own relevant, but related, policies, practices, systems and metrics to achieve effective performance."

Jan 1, 2016

Production reporting is a natural computer application and is often one of the first applications implemented by new computer users. Automation of a manual reporting system is a good place for new computer users to gain computing experience because generation of basic reports - is fairly straightforward, and automation can often be justified easily on the basis of clerical cost savings. Computers are particularly well-suited for reporting applications which generally satisfy the criteria for effective computerization. Three characteristics must be present to effectively utilize a computerized system: 1) The potential application must be precisely definable. If an algorithm for data processing cannot be developed, data cannot be processed. 2) The operation to be performed must be repetitive. If a particular function is only going to be performed once, computerized systems development is probably not justified. 3) The volume of the data to be processed must be relatively large. If only a few items of data must be manipulated, manual methods are probably adequate. Although a computer can perform only a few functions (it can compute; it can make comparisons; it can rearrange data), it can perform these functions much faster and more accurately than a human being can. The ability to classify and reclassify data in a variety of ways and the ability to summarize data make the computer an ideal tool for production reporting. Production reports can be classified into three major categories, depending on their purpose. Reports can be used for (1) informative, (2) analytical, and (3) control purposes.

Jan 1, 1979

By C. Treworgy

Geologic and technical factors such as coal seam thickness, stripping ratios, roof conditions, partings, faults, and size and geometry of the reserve block greatly impact the availability of Illinois coal for mining. Residential and commercial developments also restrict access to coal reserves in some areas. Despite the collective effects of these factors, large blocks of bituminous coal reserves suitable for efficient, low-cost underground mining remain available in Illinois.

Jan 1, 1997

By William F. Riggs

The name of this symposium speaks for itself in the connotation normally assigned to the term 'political. "In this paper, various donors have contributed their stories of metallurgical bloopers, blunders, and scams. The paper covers areas from human error stories, through technical blunders, to outright scams. Included are some stories that involve geology as it relates to metallurgy, warehouses of precious metal concentrates, reagent selection, solutions that treat the symptoms instead of the problems, improper technological transfers, humorous design mistakes in the interest of being exacting, and many more. The stories are all true with the names and dates withheld and the cases presented in the true sense of the "John Doe Stories."

Jan 1, 2001

By Dae S. Young

The Disjunctive Kriging (DK) procedure was developed to estimate ore recovery figures within a deposit/ domain from limited diamond drill hole (DDH) core assay data taken at the exploration stage. Local recovery figures include minable ore tonnage and ore grades within relatively small areas such as stopes or small panels on a pit bench, for a given cut-off grade. The grade and tonnage should be computed based on the true selective mining units, that is, the average grade distribution of selective mining units within a panel. Local recovery figures are critical information for economic and engineering feasibility studies before mine development, as well as for short-term mine planning for operating mines. This kind of information can be provided only by non-linear geostatistical methods including DK and the Multivariate Gaussian Approach (MG) (Journel, 2, Parker, et al, 5).

Jan 1, 1982

By Paolo M. Brion, Z. Bade Sozer

"The Bypass Tunnel has high head conditions ranging from a minimum of 600 feet (183 m) under the Hudson River to a maximum of 875 feet (267 m) on the west side. The ground cover ranges from 425 feet to 900 feet (130 to 274 m). A two-pass lining is designed for the Bypass Tunnel. The bolted, gasketed precast segments carry the temporary hydrostatic and permanent ground loads. After the tunnel is put into service, the design assumes that the final lining, which varies from reinforced concrete to reinforced concrete with steel interliner, will carry the permanent hydrostatic loads. The design head for the segments is assumed at 775 feet (236 m), and the internal operating pressure head is around 1,200 feet (366 m). This paper discusses the design hydrostatic head and different load conditions considered for the segments, the load sharing between the segments and final lining, and the means employed to control water and hydrostatic pressure. PROJECT BACKGROUND The Rondout-West Branch Tunnel (RWBT), a segment of the Delaware Aqueduct, was built from 1937 to 1944 and provides about 50% of New York City’s total water supply. Monitoring and tunnel operations have shown that the RWBT is leaking up to 35 million gallons per day (MGD) (132.5 million L/day). In particular, two locations have been identified as areas of concern: Roseton and Wawarsing, as shown in Figure 1. The Wawarsing reach of the aqueduct will be repaired with an extensive grouting program when the RWBT is unwatered. However, because of the extensive nature of the leakage in the Roseton area, a Bypass Tunnel will be constructed to divert the flow around this area."

Jan 1, 2016

By G. T. Adel, W. Z. Choi

In previous work at Virginia Tech, a population balance-model describing the simultaneous processes of size reduction and mineral liberation has been developed. Experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple-composite- class model has been developed. Emphasis is placed on direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

By Bill Kendall

"In coal mines, handheld air, electric and hydraulic powered drills are used along belt conveyors, in single entry development, in entries where there are obstructions, and in longwall recovering bolting. In hard rock mines, pneumatically powered jackleg drills are typically used in narrow vein mining. Drilling and bolting in narrow confines has traditionally been performed with pneumatically or hydraulically powered hand-held drills or newer electrically powered hand- held hammer drills due to their low cost, simplicity of operation, and extreme flexibility due to their small size. Mechanized equipment has typically been too large, too expensive, inefficient due to the confined space, and too restrictive due to lack of flexibility for use in narrow confines.Although the handheld equipment is effective, it requires operator exposure to certain inherent hazardous conditions in use. These include falling rock from the roof, rib and face; tripping hazards; bending twisting lifting hazards; high noise levels and chemical fumes from the pneumatic exhaust. The operation of the hand held equipment can adversely affect the long-term health of the operator - continual jackleg operation frequently results in longterm damage to hearing, shoulders, arms and wrist joints and back injuries. This results in a reduction in life style for the operator and higher personnel turnover rates for the mining company.Hand-held drills also typically have limited thrust and torque capability that limits their ability to push long resin bolts, inadequate torque to properly install resin bolts or to properly torque mechanical or tensioned rebar bolts. Hand-held drills do not offer any type of protection for the operator from roof or rib falls. They do not offer any means for handling roof or rib mesh. Since the operator stands on the ground the maximum safe drilling height without use of a ladder or "riding the drill" is limited to 2.44 m (8 ft)."

Jan 1, 2014

By Hang Yang, Linneas W. Laage

Mine fire emergency planning requires simulation of the interaction of the fire and ventilation system and the subsequent distribution of products of combustion (POC). Several computer models were developed by the Bureau of Mines to perform this simulation. The most recent and advanced program, MFIRE performs normal ventilation network planning calculations, and dynamic transient state simulation of ventilation networks under a variety of conditions. MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influences such as varying outside temperatures, and internal influences such as fires. A major concern of mine fires is the heat- generated ventilation disturbances which can move POC through unexpected passageways. This Bureau paper describes recent in-mine experiments conducted at the Waldo Mine near Magdalena, NM to validate the temperature distribution and heat exchange with rock functions of MFIRE.

Jan 1, 1991

By Terry D. Vandell

The purposes of this presentation are: (1) to discuss the actual as well as potential incidents that have caused and that could cause groundwater contamination at uranium in situ leach mining sites and (2) to discuss remedial actions and solutions that have been or that could be implemented in the future to stop or prevent serious groundwater contamination from in situ leach mining in Wyoming?s Powder River Basin. Open pit, underground, and existing and proposed in situ leach uranium mine sites in the Powder River Basin are shown in Figure 1. In situ leach mining or solution mining for extracting minerals in liquid form is a relatively new addition to the list of conventional mining methods currently used to extract uranium in Wyoming's Powder River Basin. Basically, the in situ leach mining method involves: (1) the injection of a leach solution lixiviant (an acidic or basic oxidizing solution) into a uranium-bearing ore body, via injection wells, to complex the contained uranium, (2) mobilization of the uranium complex from the host material via creation of a soluble complex salt, and (3) surface recovery of the solution bearing the uranium complex via production wells. Uranium is then separated from the leach solution by conventional milling unit operations (ion exchange).

Jan 1, 1981

By Jean E. Tilden

An investigation of several trace elements distributed among sulfide minerals from deposits located in the southeastern United States was conducted. The deposits investigated are distributed within both the Blue Ridge Province and the Piedmont Province, which are contiguous geographic provinces. Twenty five deposits were examined;' eleven in the Blue Ridge Province and fourteen in the Piedmont Province. Figure 1 shows the locations of deposits investigated. In the deposits investigated, the mineral phases examined were pyrite, pyrrhotite, chalcopyrite, and sphalerite. These phases were chosen because of their relatively widespread occurrence, although no pyrrhotite was seen in the Piedmont Province. A total of 116 polished surfaces of ores were prepared, and mineral phases were collected from these surfaces for analysis. Samples were analyzed for cobalt, nickel, manganese, lead, tin, chromium, molybdenum, and gold. A total of 372 analyses were made. Trace elements were determined by atomic absorption spectrophotometry following standard procedures. In this study, trace elements are defined as those elements which are present in the mineral but which do not affect the chemical formula for that mineral. Lead is considered as a trace element only in ores where little or no lead sulfide could be identified as a distinct mineral phase.

Jan 1, 1972

The day after I reached New York, on January 30th, John Ryan of Anaconda told me where they wanted me to go. Late in 1916 the Russian Czar, desperate for money and supplies with which to carry on his unhappy share In the first World War, sent emissaries to the United States to see if our great mining companies might be interested in trying to find mines and to bring them to production in the millions of acres of the Imperial Estates in Russia and Siberia. It looked like a long chance as no one knew whether or where there might be important ore bodies. Even if they found them it might be a hopeless task to equip them under wartime conditions But the American copper companies had plenty of money and they were used to taking risks. They made a supersecret agreement with the Czar's deputies to send an exploring expedition to Russia at once I never learned the names of the other companies but Anaconda was to man- age the venture. Horace Winchell, then the leading mine geologist In the United States, was to be in charge of operations. Charles Janin, an eminent placer and dredge expert, was to study chances for producing gold and platinum. Though at 33 years of age I was much younger than the others, I was chosen to hunt for copper and other valuable metals. Charles Boynton, a business man who had lived in Russia and had married an attractive Russian woman, was to join the party and carry on any necessary financial or diplomatic affairs. He had gone on ahead to arrange for our reception Finally a graduate student from Ann Arbor named Steinberg was to go along as Interpreter. We soon found out that if his Russian was no better than his English his interpretlng couldn't be trusted too much I knew nothing about the millions of square miles In Russia and Siberia, and even less about what mineral deposits might be found, but I was delighted at the prospect. I was treading on air for the few

Jan 1, 1976

By S. Watkins, D. Apel, B. Gray, R. Moss

Currently, there are several techniques and technologies available which are used by mining industry in its attempts to remotely monitor the ground movements both at surface and underground mines. The currently available remote distance meters and distance change monitors mainly use phase change and time-of-flight techniques. The described monitor uses triangulation technique to track position of an optical spot projection and then image processing to measure mine wall movements. The system can be easily automated and poses no obstruction to mine traffic. The position of an off-normal laser spot will shift as the target wall moves. The described ground movement monitoring system has potential for superior accuracy and target monitoring can be made through air (gaseous) or other transparent media. The theoretical accuracy and range of this system depends solely on the resolution and focal length of the camera being used. The remote capabilities of the system make it uniquely suited to applications where monitoring is required in high-traffic, inaccessible, or unstable and dangerous areas of a mine.

Jan 1, 2007

By T. H. Koenning

Spontaneous combustion in western U.S. coal mines has been recognized as a serious problem which requires unique solutions. Methods have been developed for longwall mining which rely on the existence of an oxygen-deficient atmosphere in the gob for control of the spontaneous combustion hazard rather than the use of bleeder systems. Monitoring of the gob atmosphere is required to protect against the possibility of an explosion and to detect spontaneous heatings. Data from an example mine employing such a system is included to illustrate normal gob gas trends and is compared to abnormal trends which resulted from and were indicative of a fire. Under normal circumstances the oxygen (O2) and carbon monoxide (CO) concentrations decline rapidly as the longwall face retreats. Samples taken from a leaking seal in the example mine prior to a spontaneous heating showed virtually no oxygen depletion, contained erratic CO concentrations, and indicated the existence of hydrogen, a fire indicator. The appearance of an abnormal trend in the gob atmosphere can be used as an early warning of spontaneous heatings.

Jan 1, 1992

By L. M. Gochioco

The U.S. coal industry is under-going dramatic changes to meet the challenges of the keenly competitive fuels market. The application of innovative technologies is needed to improve safety and to increase productivity in order to make coal more competitive as a fuel. As more coal companies shift into capital intensive longwall mining, there is a clear need to invest more in exploration before mine plans are made. Coal seam anomalies may create adverse mining conditions. The early detection of these anomalies could make the longwall mining safer and more productive through improved planning. A standard exploratory drilling program can provide only limited geologic information. The seismic reflection technique can be used to detect coal seam anomalies and is effective in reconnaissance surveying. Recent advances in the quality of coal seismic data have increased the success rate of seismic surveying. Therefore, surface seismic surveys, coupled with selective drilling, will come to play an integral role in coal exploration in the 1990s.

Jan 1, 1990

By Jerzy Iskra, Wlodzimierz Sikora

INTRODUCTION The effect of stress concentration in coal seams leads to a sudden release in the form of rock bursts. This effect is controlled along many lines, but the most efficient methods consist in preventing the accumulation of energy in the seam or in the roof. The over- burden weight resulting from mining is the main cause of excessive stresses in a seam. An additional weighting of roof takes place due to formation of abutment loads. The accumulation of energy in the roof takes place where thick sandstone beds occur in overburden strata. An essential problem is to watch, with appropriate measurements, the stress of coal and roof rocks, and to conclude, on this basis, the degree of rock burst hazard. The methods for determining the stresses in a coal seam are quite well developed at present. Let me mention here the seismoacoustic methods, or borehole overcoring measurement methods. On the other hand, an examination of the state of stress in the roof rocks is almost impossible at the actual stage of development of the measuring technique. Hence, the model of stresses in roof was analyzed and determined theoretically. Based on this model, a technology for roof fracturing was developed which aims at destressing rock masses in a planned way. The essentials of the fracturing method consist of a controlled breaking of sandstone roof beds in order to: - prevent the excessive weight on the pillar - prevent a spontaneous breaking of roof beds at a limiting state followed by sudden energy release. High pressure fluid infusion is used to release buildup of stresses. THEORETICAL AND RESEARCH BASES According to the tests carried out by A. Kidybinski by the method of finite elements, isobars of stresses occurring in the roof over the working face are shown in [Fig. 1]. The results indicate: - the highest values of compressive stresses occur in the roof directly over the seam, at a distance of about 5 m ahead of the working face - at a distance of about 22 m above the seam there is a line of transition of compressive stresses into tensile - within the tested roof area, the highest tensile stresses occur at a vertical distance of 35 m, and at a horizontal distance of 20 m from the line of the working face. H. Gil (1) determined the pres- sure initiating the fracture of roof rocks by the formula: [ ] On the basis of results of analysis of isobars, and of the initiation of failure stress formula (1), isobars may be designed for a given roof class. Assuming for sandstones the Poisson ratio equal 0.3, a field of failure stresses presented in [Fig. 2] is obtained. In this figure it can be seen in which areas the effects of sandstone breakage may be obtained with the operation of a determined hydraulic pressure. To use formula (I), the knowledge of Rr is still necessary. This value may be determined in two ways: - taking a sample and testing it in the laboratory, if there is access to roof rocks in the existing openings, - drilling boreholes in the roof from surface and examination of the rock mass by using hydraulic breaking, if there is no access to roof rocks.

Jan 1, 1982

By Fulian He, Jianhang Chen, Shoubao Zhang

"Fully grouted rock bolts have been used in mining industry for many years. Significant research has been conducted to evaluate the load transfer behavior of fully grouted rock bolts with experimental programs. However, compared with that, less work has been conducted with analytical modelling. Therefore, in this paper, the authors used an analytical model to study the load transfer behavior of fully grouted rock bolts. To confirm the credibility of this analytical model, an in-situ pull-out test was used to validate this model. There was a close match between the experimental result and the analytical result. Following this, a parametric study was conducted with this analytical model. The influence of coefficients, Young’s modulus of the rock bolt and the diameter of the rock bolt on the load transfer performance of rock bolts were studied. Furthermore, the load distribution along the fully grouted rock bolt was analytically studied. The results show that the axial load in the rock bolt decayed from the loaded end to the free end independent of the pull-out load. However, the trend of the load distribution curve was influenced by the pull-out load. This paper was beneficial to better understand the load transfer mechanism of fully grouted rock bolts.INTRODUCTIONRock bolts have been used in the mining industry for a long time. They are used as the reinforcement tendons to keep the stability of openings in underground mining and the slope in open-pit mining. Furthermore, rock bolts are commonly used not only in the mining engineering, but also in civil engineering (Thompson, Villaescusa, and Windsor, 2012).The rock bolt is a tendon which can be a rod or a cable inserted into a borehole drilled in rock masses or soils. Traditionally, the material of rock bolts was steel. However, engineering practices showed that the steel rock bolts can be easily corroded by the moist environment in underground mines. Next, Fiber Reinforced Polymer (FRP) was used to manufacture rock bolts, which are termed as FRP rock bolts. Experimental results proved that the FRP rock bolts can effectively reinforce the surrounding rock masses without being corroded (Wang et al., 2018)."

Jan 1, 2019