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By R. L. Loofbourow

Reasons for reexamining underground mining include: 1. The assurance that more deep deposits of useful minerals will be found. 2. The existence of deeply covered deposits of industrial minerals near large markets where quarries are becoming depleted or are lacking. 3. Surface property values, zoning and other limitations on open pit mining. 4. Expectation that underground space will be increasingly used for transportation, power plants, storage and similar purposes. 5. The improvements which have been made in underground mining. During the last three or four decades many changes and improvements have been made underground. All underground construction and mining has benefitted to some extent but the effect on the productivity of labor employed with some methods- has changed little and the use of these methods has declined. Productivity of labor in other methods has increased substantially. The relative usefulness of mining methods has changed and a vital industry, bituminous coal, has been returned to health. In this paper, consideration is limited to nine methods used with high productivity during the period under review. These methods are not necessarily better than others but they may be considered the prime methods in the sense that, in our economy, many, low grade ores, coal and the principal industrial minerals could hardly be produced by less productive means.2 Although most of the examples cited are from mining as such., the first four methods discussed can be used for the construction of stable excavations of various' shapes in sound rock.

Jan 1, 1967

By T. Qiu

"The purpose of this study is to investigate the effect of the dosage of sodium hypochlorite as activator on the flotations of depressed marmatite and depressed chalcopyrite, with a focus on activation-flotation kinetics. Four flotation kinetic models were applied to test data using 1stOpt statistical analysis software to estimate the relationships between the maximum flotation recovery rates for the depressed marmatite and depressed chalcopyrite, the flotation rate constants and the sodium hypochlorite dosages. Within the range investigated, the highest flotation performances of depressed marmatite and depressed chalcopyrite were obtained at 2.5 mL/L sodium hypochlorite with zinc recovery rate of 93.8 percent and 3 mL/L sodium hypochlorite with copper recovery rate of 94.6 percent, respectively, after four minutes of flotation. A second-order model with rectangular distribution of flotabilities gave the best fit to test data collected at various sodium hypochlorite dosages. For the highest flotation performances of depressed marmatite and depressed chalcopyrite, the respective equations of their flotation models were derived and presented.IntroductionCyanidation tailings are the solid residues generated by gold plants that use cyanide to extract gold (Lv, Ding and Qian, 2015; Zhang, Li and Yu, 2013). Because of increasing demand for gold, the Chinese gold industry has developed rapidly, with production amounting to 451.799 tons in 2014, an increase of 5.5 percent from 2013. Chinese gold production has been the highest in the world for eight consecutive years. As a result, more than 2.45 million tons of cyanidation tailings are estimated to be discharged into tailings ponds every year (Li et al., 2010; Lv, Ding and Qian et al., 2015; Wang et al., 2015; Zhang, Li and Yu, 2013; Zhang, Li and Yu, 2012), and approximately 300 million tons of cyanide tailings are stockpiled in China, with the potential to cause serious environmental pollution as well as death to wildlife (Adams and Lloyd, 2008; Donato et al., 2007; Hewitt, Breuer and Jeffery, 2012; Velasquez-Lopez et al., 2011; Stephen et al., 2009; Zagury, Oudjehani and Deschenes, 2004). Concerns over cyanidation tailings are not exclusively environmental but also economic, as tailings occupy considerable land area, and tailings storage facilities increase the production costs of gold enterprises (Donato et al., 2007). Tailings often contain other valuable metals such as zinc, lead and copper. For example, the cyanidation tailings of Gaoyao Hetai Gold Plant in Guangdong Province contain 2.5 percent copper (Cu), 0.31 percent lead (Pb), 0.23 percent zinc (Zn) and 15.36 percent iron (Fe) (Shi, 2008), and the tailings of Tianshui Gold Plant in Gansu Province contain 1.94 percent Cu, 5.96 percent Pb, 0.27 percent Zn and 24.62 percent Fe. Cyanidation tailings have therefore been increasingly viewed as a secondary resource rather than waste."

Jan 1, 2016

By Philip Lindstrom

Retreat mining, using yielding steel friction props, over a seven-year period has been successful at a uranium mine operated by Hecla Mining Company in southeast Utah. The support system allow good roof control, maximum profit, complete extraction, and good ventilation. Unusual subsidence observations were made in that some of the surface was raised rather than lowered, Longwall mining, commonly practiced in European coal mines, has a potential of broader application because of mechanization possibilities and better roof control and ventilation at greater depths.

Jan 1, 1964

By A. Andreas

The transportation of mine products incurs a cost which can have a significant bearing on the competitive position of the product. This statement not only holds true for the transportation of the finished product but certainly as much for the in- plant haulage of the raw materials. Extensive literature is available both in North America and Europe on all aspects 02 these questions and to cite only a few of them: Pipelining of slurries, oil and gas, shipping of minerals and oil from the Arctic by icebreaking tankers, airlifting of metals or concentrates, etc. This paper is concerned with movable crushing plants as opposed to stationary and their influence on the in-plant transportation, that is trucks vs. belts.

Jan 1, 1973

By Kadri Dagdelen

New underground coal mines have become increasingly expensive to open. A simple drift mine producing a raw coal product can cost as much as $50 million while a new shaft mine producing a washed coal product can cost up to $200 million. As a result, few if any speculative new mines are constructed. Normally, a long term coal supply agreement is needed to justify new mine projects. Negotiating a supply agreement prior to production start is difficult. Pricing must be based on estimated rather than historic costs and coal quality must be estimated from core hole samples versus actual shipments. Further in todays competitive coal markets, there is little margin for error in either price or quality.

Jan 1, 1983

By S. B. Hildebrand

One of the highest costs associated with insitu leaching of copper is electric power. The ReGeneration Project addressed this cost issue with a research and development project for BHP Copper. The project involved the installation of a reverse pump/turbine for the removal of excessive fluid pressure and the production of useful electric power. The motivation for the project was that a reverse pump/turbine unit could not only remove the excess hydraulic pressure, but when connected to an induction .generator, would produce electric power, which could be easily connected to the local power gird, thus reducing operating costs. The project was successful in removing excess fluid pressure and producing electricity. The unit is operating today, producing useful 2,300 volt power at a rate of approximately 128 kilowatts.

Jan 1, 1998

By Mark E. Gershon

The development of long term plans and schedules for strip mines now faces many companies, especially those developing large properties in the West. The rule of mining the lowest strip ratios first, while delaying equipment acquisitions and recouping investment the fastest, creates the situation where stripping ratios are too high in the latter years of mining operations. A program concept taking life of mine return on investment into account is developed in this paper to optimize mine scheduling and equipment acquisition. In addition, quality considerations (heat content, ash, sulfur, washability) can be considered by including the appropriate blending constraints to meet contract requirements.

Jan 1, 1983

By Thomas Camus

"STATE OF THE ART The current situation of ground prediction in TBM is of great concern for tunnelling contractors, and the subject has been quite widely addressed over recent years, for instance by the French Eupalinos 2000 programme, which tested a variety of technological approaches. A number of interesting projects were executed, such as the SOUND and OnSITE projects, part of the German Geotechnologien programme: these projects are focused on seismics, while other techniques such as radar are not considered. Little information and even less industrial applications have been released apart from lab simulations and numerical modelling. A number of field tests in different configurations have been carried out for compression waves, but the results were often not reliable or convincing, and therefore little has been reported in open literature. The advances seem somewhat promising as far as hard rock tunnels are concerned, but ignore the problem raised by concrete lined tunnels such as those bored by a TBM in soft ground. In such tunnels, sending and receiving seismic waves reliably through the lining (and the grouting behind) is quite illusory. A careful analysis of the seismic prediction research results show that the main problem is the source which is poorly controlled and poorly coupled (for instance in concrete lined tunnels, or in approaches that use the TBM cutter head vibrations as a source). Generating waves perpendicular to the tunnel axis is also a problem: aligning with the tunnel axis makes more sense. Radar (Ground Penetrating Radar - GPR) has been used in geotechnical surveys for decades, and also for tunnel inspection. Attempts have been made at using it on a TBM (for example in Japan by Taisei) but mainly using off-the-shelf GPRs, which are not adapted to work in the specific environment of a TBM (because of its huge mass of metal, to start with). Very few results have been published, probably due to the somewhat disappointing performance of such implementations. At present, no TBM has a GPR incorporated in its cutter head that is able to predict ground characteristics while drilling. Another characteristic and drawback of most current methods is that they require dedicated periods of time during which other tunnel construction activities must be stopped. Due to the duration of such operations this leads to performing ground prediction on a weekly basis only, and therefore to a requirement for an investigation range of 100 metres approximately (in order to cover the TBM advance over the coming week). This is not achievable with boreholes made from the TBM, even less if a reasonable accuracy is required, as is usually the case."

Jan 1, 2016

By C. Bateman, F. Calizaya

"This study presents the results of three laboratory experiments on pressure balancing carried out at the University of Utah’s coal mine ventilation model. The model includes simulations of two working areas, one longwall mine gob, and a set of stoppings and seals. It also includes a pressure chamber between the longwall face and the gob. The model is ventilated by one main fan and one bleeder fan. A carbon dioxide injection system, equipped with flow control valves operated by a microprocessor, is used to pressurize the chamber and to maintain the pressure in the chamber slightly higher than that of the gob. During each experiment, fan pressures and stopping resistances were changed, the carbon dioxide injection rate was regulated, and the differential pressures across the stoppings were monitored so that the chamber pressure is always kept slightly higher than that the gob pressure. Result of these experiments are reported in this paper. INTRODUCTION Spontaneous combustion (Sponcom) is a safety hazard in underground coal mines. The history of coal mining in the US is replete with mine fires and explosions. Sponcpm accounts for approximately 17% of the total number of fires recorded in the U.S. since 1990. In the U.S., by law, worked out areas in coal mines must be either ventilated by a bleeder system or isolated by explosion proof seals. Experience has shown that seals are not airtight structures and that they allow some leakage of air into or out of the gob. In fact, seals “breathe in and breathe out” with changes in barometric pressure (Francart 1997, and Chalmers 2010). These changes in pressure affect not only the methane emission rate but also the ingress of oxygen to the gob, the lower the pressure behind seals is, the higher the ingress of oxygen. In mines ventilated by a U-tube exhaust system, the gob is often kept under negative pressure. Under these circumstances, an increase in barometric pressure may cause an influx of fresh air into the gob. This quantity may be sufficient to start self-heating of the coal, which can lead to spontaneous combustion. Depending on the coal characteristics and the ventilation conditions, self-heating of coal can start at temperatures as low as 35 ºC. If the heat is not removed it will increase the coal temperature leading to ignition and fire. The risk of Sponcom fires can be reduced by isolating the mine gob using rated seals, and implementing a suitable ventilation system. However, isolation seals are not airtight structures, thus some leakage of air is expected unless the pressure in the gob is neutralized. The alternative is to use a pressure balancing system. This requires a thorough knowledge of the ventilation system, the seal/stopping construction techniques, the airflow behavior in the gob area, and the gas build-up behind the seal line."

Jan 1, 2016

By M. J. Carlson

With the goal of improving the strength characteristics of pneumatically emplaced material used for localized subsidence control, the binding additives: fly ash, bentonite, and Portland Cement, were examined for their effect on the support capabilities of coal refuse. It was found that, within certain concentration ranges, all three of them offered some increase in the ultimate strength of the backfilling mixture; however, Portland Cement gave the greatest percentage increases. Selection of the appropriate backfilling mixture will allow for the most economical and efficient subsidence control when pneumatic stowing is employed.

Jan 1, 1987

By N. D. Cristescu

The aim of the present paper is to show how a mathematical modeling of a creeping rock and that of an yieldable lining can allow us to obtain an optimization of the lining design and generally of the whole procedure and sequence of excavation-lining application. We follow the procedure presented by Cristescu (1989) Chap. 13, and Cristescu et al.(1987); for some other approaches see the literature mentioned, for instance, by Ladanyi and Gill (1988). We have in mind to describe the creep of the rock, i.e. the tendency of the tunnel to close in time, and to take into account that the lining itself may be deforming, i.e. possesses some rheological behavior. We start from the well known fact that "intelligent" lining, which are yielding to the pressure of the rock, may be much more successful in supporting creeping rocks than excessively strong, badly designed supports which are unable to resist to pressure of the rock, though these are oversized supports (too strong, too stiff, installed too early, etc.). In order to optimize the lining to be used for a certain rock, it is absolutely necessary to study in the laboratory the main mechanical properties of that specific rock and to formulate for it a reasonably simple mathematical model. Standard triaxial test results are quite enough to determine the model for the rock, combined with some creep tests which have to reveal the long-term behavior of rock (the so-called rheological model). What concerns the lining, we consider several kinds of linings existing today, for which a mathematical model was also formulated. One shows which is the interaction between the creeping rock? and the yielding lining and how can it be formulated in mathematical terms. Once written in mathematical terms, an optimization of the lining design and that of the excavation layout and support application sequence is possible. We will try to make the exposure as simple as possible, avoiding details and having in mind to give only a sketch of the problem, while the mathematical details could be worked out quite easy.

Jan 1, 1994

By Ke Yang, Kai Zhang, Xiaolou Chi, Xiangyang Zhang, Yingming Li

Based on the research background of 1303 working face return air roadway in Jinyuan Zhaoxian Mine, Shaanxi Province, a method of determining the reasonable spacing of boreholes is proposed based on the stress transfer degree of coal above and between boreholes, combined with the law of plastic zone and energy evolution by theoretical analysis and numerical simulation. After drilling pressure relief, the average daily energy of microseismic events decreased by 70%, and those with microseismic energy greater than 104 J decreased by 99.2%. The research has a strong guiding significance and research value for determining the reasonable distance of borehole pressure relief.

Jun 25, 2024

By Scott O’Brien, Richard Williams, Camilo I. Mejias, Elias Godoy, Javier Sierra

High-rate thickeners play a critical role in tailings management by enhancing water recovery and increasing solids concentration. However, these units face operational instability due to fluctuations in feed solids, flow rate, and flocculant response typically managed in manual mode with delayed corrective actions. This work presents an adaptive automatic control algorithm designed for dynamic thickening environments. The algorithm integrates real-time measurements of feed density, rake torque, bed level, and turbidity (overflow), optimizing the underflow slurry density while minimizing suspended solids in the overflow. The proposed control strategy is modular, simple, scalable, and applicable to both existing and new thickening systems, offering a robust alternative to manual operation in increasingly demanding metallurgical environments.

Feb 22, 2026

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the bubbles, water, and ore, selectively attaching these bubbles to the hydrophobic mineral's surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. The rapid flotation system was evaluated for beneficiation with a western porphyry copper ore containing 0.67 pct copper, and a phosphate-bearing amine flotation tailings sample containing 9.5 pct P2O5 in a quartz matrix. Over 88 pct of the copper was recovered from the ore in a rougher concentrate containing 5.9 pct copper at a rate 7 times faster than conventional flotation. Sixty percent of the quartz in the phosphate-bearing sample was floated at a rate 4 times faster than conventional flotation. The unfloated product retained 80 pct of the phosphate in a l6.9-pct P2O5 concentrate.

Jan 1, 1993

By R. Asmatulu

According to Darcy?s law, the rate of filtration should increase with increasing pressure drop across a filter cake. In centrifugal filtration, the driving pressure is created by the centrifugal forces applied in the free water on the surface of a filter cake. However, the pressure drop can become negative when the free water surface disappears, which makes it difficult to achieve low cake moistures. In hyperbaric centrifugal filtration, this problem is overcome using air pressure to restore the pressure differential. In the present work, various mineral and coal fines have been subjected to hyperbaric centrifugal filtration tests. The laboratory tests show that the moistures of various mineral fines, such as copper and zinc concentrates, phosphate, talc, kaolin clay, and precipitated calcium carbonate, can be reduced substantially below that achieved by conventional centrifuges. Similar promising results have also been obtained with various coal fines in laboratory and pilot-scale test programs and in full-scale plant demonstrations.

Jan 1, 2012

By Jake Beale, Joe Wickline, M. Van Dyke, Ted M. Klemetti

A longwall coal mine in southwestern Virginia mining the Pocahontas #3 Coal Seam experienced a history of mining-related seismic events. The events were never large enough to cause concern until three major events occurred recording 3.4, 4.3, and 3.4 ML in 2005, 2006, and 2007 respectively. Two of the seismic events generated an air blast which damaged stoppings which fueled a mine fire in 2005 and 2007. The mine responded to the events by narrowing the longwall widths, changing ventilation controls, installing a 7-sensor seismic system around the active panel, and creating a mining hazard map to avoid similar geology in the future. All of the actions taken have prevented seismic activity from impacting mining operations, but it did not prevent other large seismic events from occurring (Van Dyke et al., 2018). In 2016, another large seismic event, measured at 3.7 ML, occurred in the gob that was reported by the local media and recorded by the United States Geological Survey (USGS). While the event did not directly impact mining operations, mine management wanted to know where and under what conditions could large seismic events occur in the future. The National Institute for Occupational Safety and Health (NIOSH) became involved to help understand what conditions precipitated these events so that future mine design could more accurately assess seismic hazards and reduce the risk to mine worker safety. Researchers at NIOSH and mine management created a seismic forecasting map that combined three factors: (1) overburden thickness, (2) sandstone thickness, and (3) the expected caving height of the gob. The criteria were developed based on the geologic data the mine collected from core drilling, e-log analysis, and fiberscope observations. The forecast map was able to provide an accuracy of 72%–85% of events 1.5 ML or greater and 100% accuracy of events that were 3.0 ML or greater based on historical data. The seismic forecasting map was applied to the entire future mining area to show areas where seismic potential could be the greatest based on current mine design planning, ultimately improving the ability of the mine operator to assess the seismic hazards surrounding active and future mining areas (Van Dyke et al. 2018). Following this research, the seismic forecasting map was implemented into the mine’s hazard recognition program and is continuously updated and evaluated prior to mining each longwall panel. This paper will cover in more detail how the seismic and lithologic data was processed and how the mine implemented a new seismic mitigation program based on the forecasting results.

Apr 26, 2022

By Larry A. Enloe

The 16-to-1 milling operation is Sunshine Mining Company's first new silver and gold producing facility. The 16-to-1 underground mine and mill are located approximately 64 km (40 miles) southwest of Tonopah, Nevada. Ore re- serves in the epithermal vein deposit are estimated at 0.91 Mt (one million st) of ore, at an average silver grade of 206 to 240 g/t (6 to 7 oz/st) and an average gold grade of 1.2 g/t (0.035 oz/st). The underground mine uses a large diameter blasthole stoping system of mining using highly mechanized rubber-tired equipment. The mill uses conventional cyanide leaching with countercurrent decantation and Merrill-Crowe precipitation. The mill start-up was in February 1982 resulting in the first pour of dore' in March 1982. The mill's present annual production is approximately 31.1 t (1.0 million oz) of silver and 264 kg (8500 oz) of gold.

Jan 1, 1984

By H. Walqui

The Empire concentrator currently processes magnetite ore from the Empire pit which is approaching the end of its mine life. Over the past two years plant wide tests have been run to access the plant capability of processing ore from the neighboring sister Magnetite pit. The neighboring pit presents challenges to the Empire plant due to its higher feed grade, finer liberation size and higher percent silica which require additional secondary grinding and concentrating capacity to achieve concentrate grade. The following paper summarizes the results from the second full scale test, run during 2009 under a challenging market environment

Jan 1, 2010

By Tsunenori Shibata, Kazunori Jimbo, Kaoru Toya, Masafumi Matsumoto, Jinya Mitsui, Toshinori Tsuji

"The Toyama Line is under construction as a natural gas pipeline with a length of 102 km from Itoigawa City to Toyama City. A 2 km-long tunnel section of the pipeline that we are reporting here is being excavated in a mountain area away from an urban area. The geology under which the tunnel is constructed is collapsible fractured breccia slate and Holocene sandy soil. Other tunnels of the Hokuriku Expressway and Hokuriku Shinkansen are in service above the tunnel route. From the starting shaft on Toyama side, conventional tunneling was adopted to facilitate excavating the base rock layer and maintain enough distance from the Hokuriku Expressway tunnel. From the starting shaft on the Itoigawa side, TBM tunneling was adopted to cope with the unconsolidated soft ground for a 200 m-long section from the shaft. We will discuss the issues and countermeasures concerning the selection of a tunnel route and excavation methods, performance of both conventional and TBM tunneling, and underground connecting of these tunnels excavated by conventional (NATM) and TBM methods under a high groundwater pressure up to 1.2 MPa. INTRODUCTION AND BACKGROUND The International Petroleum Exploration Teiseki Co., Ltd. (INPEX) is constructing a high-pressure main pipeline network in the Toyama Prefecture area to promote the use and reliable supply of natural gas as shown in Figure 1. As part of the Toyama line project that has a total length of 102 km, A-1 construction, the nearest section to the tunneling starting point in Itoigawa City, where various tunnel excavation methods have been adopted to install the high-pressure pipeline 20 inches in diameter, a 2 km tunnel in the A-1 construction section discussed here is to be excavated by conventional and TBM methods in a mountain area. Based on environmental studies such as traffic jams due to frequent traffic of heavy vehicles disposing of soil, and the effects of dust, noise and vibration during construction, we selected the route to install the gas pipeline in a mountain area as shown in Figure 2, where the impact on the surrounding environment could be minimized."

Jan 1, 2016

By Y. C. Guan

In an attempt to replace the traditional cyanide process of extracting gold, a new technology using ammoniacal solutions has been developed. In this study, the electrochemical behavior of gold in ammoniacal solutions at temperatures above 100°C has been investigated. An electrochemical cell in an autoclave has been introduced to carry out this study. The system consists of a gold working electrode, a platinum counter electrode, and an external saturated calomel electrode (SCE) which is connected to the autoclave system through a Birch wood plug. Techniques used in this study included potentiodynamic polarization, galvanostatic polarization, cyclic voltammetry, and Tafel polarization. The electrochemical reaction mechanisms governing the dissolution process are presented.

Jan 1, 1996