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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 D. Gatzemeier

The Jewett mine is a surface mine in central Texas, producing about 8,000,000 tons/year of lignite. The mine covers 46,000 acres of land. Approximately 430 people are employed by Northwestern Resources Company and through their efforts, the Jewett Mine is one of the most productive mining operations in the country. The Jewett Mine utilizes a unique structure of staff to convert Operations Research into plans which can be implemented at the "front line" level of the Operations Team. This planning not only makes the mine cost effective and efficient, but promotes creativity in mining, which promotes ongoing research to lower the cost of mining.

Jan 1, 1993

By Igor Gonzales G.

Southern Peru Copper Corporation (SPCC) has recently completed the construction of copper leaching, solvent extraction, and electrowinning facilities at their Toquepala and Cuajone plants in Southern Peru. Much of the ore for these new operations is the result of the existing mining operations that have been in existence as early as 1959. At Toquepala, pre-conditioning and bacterial dump leaching of the sulfide ore that was too low in copper content to be processed through the copper concentrator began in 1987. The Cuajone heap leach operation is treating copper oxide ore that has been stockpiled since the Cuajone concentrator began operation in 1976. The pregnant leach solutions from the dump leaching at Toquepala and the permanent pad heap at Cuajone are combined into one plant feed solution. Adjacent to the large dumps at Toquepala, a solvent extraction and electrowinning facility has been constructed. The electrowinning facility has a planned annual production rate of35,000 metric tons per year Grade A cathode copper. Initial production of the cathode copper began in November 1995.

Jan 1, 1996

By M. P. Oommen

This paper provides a brief look at a proposed short-longwall for coal, development. The proposed method is an attempt to realize the advantages of longwall mining in deposits that, historically, would only be minable by continuous mining methods. An overview of the proposed layout, development requirements, production rate, ventilation scheme and other associated features is provided. This mining method could help operators in above-drainage seams where minable areas are smaller. It may also have application in areas that are peppered with gas wells and in environmentally sensitive areas which preclude the use of conventional longwalls.

Jan 1, 1993

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 D. J. DeLeo

In recent years the hue and cry of American industry concerning the pressure of foreign competition on the domestic marketplace has become all too familiar to most of us, as we are all well aware, the steel industry has not been exempted from this pressure, reduced production levels, work force cutbacks, and in some extreme cases, plant closings and company liquidations have resulted, new regulations governing imports and quotas have been enacted, foreign trade agreements reached, and more strict regulation enforcement practices undertaken, despite these, and other measures, the impact of aggressive foreign competition has not lessened, the concensus of numerous management consultants is that in order to successfully cope with these problems we must draw on all available technology to provide the tools which will enable us to enhance our management effectiveness, one area requiring particularly close attention in any mining operation is that of managing critical resources - namely time, energy and equipment in a fast and efficient manner, In mining, with critical resources deployed over a large geographical area, any degree of success involved with resource management is dependent upon knowing the current status of all work related activities, if we, as mine operators, are to be more successful in this area, additional tools are a necessity and modern technology has provided a multitude of new options from which to choose.

Jan 1, 1985

By J. Bacho

The modern drilling fluids industry is a dynamic, evolutionary environment. It is continuously striving to satisfy and anticipate the ever-changing needs of the oil and gas industry. The predominant driving forces in the industry over the past decade have changed dramatically. Health and environmental issues, coupled with economic and performance requirements, demand innovation and change from the drilling fluids industry. Emerging drilling fluid technologies will demand environmental considerations from mined components with additional emphasis on cost and performance criteria. Drilling fluids providers continue to search for and identify environmentally sensitive components which meet or exceed the performance of their more toxic predecessors. These changes have and will impact the components of drilling fluids that are mined.

Jan 1, 1994

By R. D. Cook, J. L. Johnson

"Measuring mud bed level in a sedimentation device is an important control variable. Methods used to date for this purpose have had limited success providing continuous, consistent measurements at a reasonable price. This paper describes a new instrument for detecting the mud bed / liquor interface as well as bed density profiles. The state of the bed is measured directly with sensors located in the thickener. Data from bench-scale and full-scale tests show that the bed level is well defined and easily detected. In addition, full-scale testing revealed unprecedented information about thickener beds. Variation in bed density gave new insight into thickener bed dynamics, providing design and control opportunities never before possible. This novel instrument can significantly improve thickener control by providing reliable and consistent bed level measurements. It is also capable of measuring bed density profiles that can potentially identify significant operating problems early enough to take corrective action before experiencing costly shut downs. INTRODUCTION Numerous studies and papers have been devoted to the subject of thickener design and operation to achieve specified throughput and discharge densities. Mathematical models have been developed that present methods for sizing thickeners and predicting performance under varying process conditions. The compression effect of deeper beds on dewatering performance is a recognized phenomenon (Wilhelm and Naide 1981). This is one variable of many that are inter-related and influence thickener performance. For example in the steady-state, continuous operation of a thickener, if the solids feed rate increases and the bed level remains the same, the underflow discharge rate must increase with the result of solids concentration being lower. The interactions of these parameters are at the heart of thickener models. One such model (Burger and Narvaez 2007), predicts solids concentration profiles increasing downward and discontinuities between settling zones. This model uses sediment height (bed level) as a parameter that influences capacity calculations to achieve the specified solids concentration of the underflow. Knowing the bed depth is critical to maintaining stable thickener operation. Implicit in these modeling strategies are some basic assumptions such as homogeneous distribution of solids in the different settling zones, plug flow of solids through the settling zones and steady state operation of the thickener. The accuracy of these assumptions has not been verified because there has been little visibility inside the bed of full size operating thickeners. Testing of the instrument presented in this paper demonstrates that it provides a degree of visibility of the dynamics in a thickener not previously possible and indicates that the basic assumptions of the modeling strategies may not be completely accurate."

Jan 1, 2015

By Robert Stefanko

The importance of underground stress instrumentation cannot be minimized. It was Lord Kelvin who said that unless you can assign a number to a quantity,, you know very little about it. Most engineers will agree although this kind of statement is resented by our friends in non-technical fields. Mining is undergoing a revolution from art to science. But how can mining methods be optimized if there is no way of measuring the effectiveness of a given mining method? Do we know how effective a' support is unless we can determine its reaction to the mine structure? How do we assess the need for modifications to existing systems and supports, and how do we measure the effectiveness of such changes? Cut and try techniques are too wasteful of time and energy, and rarely provide solutions to a given problem. The purpose of underground stress instrumentation is to provide answers to some of the above questions -- answers that cannot be obtained otherwise This does not mean that laboratory studies are not valuable -on the contrary. Laboratory and underground studies supplement one another. Rock mechanics had its conception with the study of stresses in homogeneous, isotropic, and elastic models subjected to various force systems. These analyses were valuable inasmuch as they pinpointed possible sources of trouble due to stress concentrations. If the results observed underground did not always agree with the experimental analysis, it was not an indictment of the latter. More probably, the discrepancy could be attributed to the lack of similitude between model and prototype. The more nearly one can simulate underground conditions in a model, the more apt one is to produce results which correlate well-with underground observations. It is impossible to completely simulate underground conditions because all of the significant design parameters have not been recognized and evaluated. What better way can one evaluate these parameters than by underground stress instrumentation?

Jan 1, 1963

By K. D. Luxbacher, J. T. Davis

"A wind tunnel was designed to examine air flow, heat transfer and layering near an active fire at a working face. This tunnel simulates an active entry in an underground coal mine including an attached cross-cut of similar dimensions. A steel rectangular duct 1 ft. (0.305 m) tall, 3 ft. (0.914 m) wide and 10 ft. (3.05 m) long composes the main body of the tunnel and represents a mine entry. Air flow is generated by an exhausting centrifugal fan attached to one end of the crosscut. This fan was sized to supply air velocities based on Froude scaling. A 6 in. (15.25 cm) propane burner is used to simulate fires of various heat release rates at the working face. Thermocouples are used to map heat layering in the tunnel. Ports are installed for the introduction of tracer gases into and from sampling the system. Barometric, differential pressure, and temperature sensors are also included to monitor environmental conditions. Details about the design and testing of the system are presented including an overview of how the tunnel was scaled to accurately represent fire and flow phenomena. Finally, the proposed use of the tunnel for better understanding of mine fire phenomena and prevention is given. INTRODUCTION Fires in underground mines have been a concern since the dawn of mining. While technological advancements, regulations and best practices have improved both fire detection and firefighting techniques, mine fires continue to represent high risk events. From 2006 through 2015, fires accounted for 1.06% of fatalities in underground coal mines and 0.85 percent of fatalities in all underground mines in the United States (U.S. Department of Labor, 2006 to 2015). In addition to the risk of loss of life, mine fires can cause millions of dollars in equipment damages and lost production revenue. Extensive research has been conducted on how fires occur and spread in underground mines. In addition to testing conducted by government agencies such as the Mine Safety and Health Administration (MSHA) and the National Institute for Safety and Health (NIOSH) (e.g.(Liming, 2006), researchers like Verakis and Dalzell (Verakis, 1988) and Lowndes, et. al. (Lowndes, 2004) have furthered this field by studying ignitions and propagation of conveyor belt fires. While the studies of belt fires in mines are extensive, studies focused on fires at the working face are few in number. The particularly confined space and limited access to a working face, coupled with less robust, temporary ventilation controls create a unique environment that warrants special attention. Separate from studies on mine fires, the use of tracer gases to characterize flow patterns in normal mining ventilation is well established. In 1982, Timko and Thimons (Timko, 1982) outlined current and future applications of sulfur hexafluoride (SF6). However, little experimentation has been conducted to study specifically how tracer gases might be used to evaluate active mine fires and the fires’ effect on the surrounding mine environment (e.g.(Lindsay, 2014). In order to better understand the dynamics of smoke layering from a fire in an enclosed space, a small-scale apparatus was designed to map smoke layering and to examine other aspects of fire behavior at a working face. In addition to studying smoke flow around an active fire, experiments will be conducted using tracer gases in order to determine how they might be used to evaluate an underground fire."

Jan 1, 2017

By G. T. Homce

Most electric motor predictive maintenance methods have drawbacks that limit their effectiveness in the mining environment. The U.S. Bureau of Mines is developing an alternative approach to detect winding insulation breakdown in advance of complete motor failure. In order to evaluate the analysis algorithms necessary for this approach, the USBM has designed and installed a system to monitor 120 electric motors in a coal preparation plant. The computer-based experimental system continuously gathers, stores, and analyzes electrical parameters for each motor. The results are then correlated to data from conventional motor-maintenance methods and in-service failures to determine if the analysis algorithms can detect signs of insulation deterioration and impending failure. This paper describes system design and implementation. At this writing, however, installation is still underway, and field data analysis results are not yet available.

Jan 1, 1994

By C. R. Stephan

Explosion-resistant seals in underground coal mines isolate the environment within the sealed area from the active workings of the mine. The current United States Title 30 Code of Federal Regulations (CFR) requires these seals to be constructed of solid concrete blocks. The CFR also allows for alternative methods or materials to be used to create a seal if they can withstand a static horizontal pressure of 138 kpa (20 psi), provided the method of installation and the material used is approved in the ventilation plan. The purpose of this report is to identify those explosion-resistant seals that have been tested and meet or exceed all the requirements of the CFR.

Jan 1, 1997

By Luisa Alfieri, Giorgio Fantauzzi, Sergio Notarianni, Spencer Cavagnet, Alessandro Damiani

"The new tunnels of the Copenhagen ""Cityringen"" will be excavated, at Kongens Nytorv square, crossing over the existing M1 and M2 metro lines. After the crossing, the tunnels will underpass the historical building of the Magasin du Nord and adjacent masonry buildings, with a minimum tunnel cover of about 4.5 m. The tunnels have an internal diameter of 4.9m and are being excavated through earth pressure balanced Tunnel Boring Machines in mixed face.The Magasin du Nord estate is characterized by a very complex structure, with different blocks built in different times. An assessment of the condition of the building and its sensitivity to tunnellinginduced ground movements has been conducted through a fully coupled soil-structure interaction analysis; based on the results of this analysis, mitigation measures have been designed.INTRODUCTIONThe Copenhagen Metro Cityringen is expected to be running in July 2019 and will consist of two single tracks in a twin tunnels, each approximately 16 km in length, for transporting up to 243,000 passengers on an average work day. The Cityringen includes 17 underground stations with island platforms, 4 crossover facilities and 3 construction and ventilation shafts. The tunnels is being excavated using earth pressure balanced Tunnel Boring Machines and have an internal diameter of 4.90 m.The intersection with the existing M1 and M2 metro-line will take place at Kongens Nytorv and at Frederiksberg. According to the design alignment, in Kongens Nytorv the new tunnels will pass over the existing M1 and M2 ones; as a result of this, the tunnels will underpass the historical building of the Magasin du Nord and the adjacent masonry building hosting a Mc Donald’s with a minimum cover of about 4.5m.In the framework of Risk Assessment for sensitive buildings, the effects of tunneling-induced ground movements on the Estates ØS0437 (McDonald’s building), ØS0428 (Magasin du Nord) and ØS0004 (Hviids Vinstue) were evaluated. To achieve this goal a fully coupled soil-structure interaction has been considered and the entire excavation process has been reproduced in a 3D model where the abovementioned buildings have been modeled. In this way, a risk assessment analysis was performed evaluating directly the effects of the excavation in terms of settlements and variations of the internal forces as far as the excavation process proceeds. In figure 1, a picture of the construction of Kongens Nytorv station, with Magasin du Nord and Mc Donald’s building on the background, is presented."

Jan 1, 2016

By C. J. Hunter

Prior to the commissioning of the Sansu Sulphide Treatment Plant (STP), Ashanti Goldfields' treatment facilities were capable of producing some 700 000 ounces of gold per annum. Ore sources were underground refractory sulphides, surface oxides and old tailings dams. In order to increase the mines production to 1 million ounces per annum and to accommodate the change in ore sources as surface mining moved into fresh sulphides, a part of the strategy adopted was -the construction of a new sulphide treatment plant with a capacity to mill 2.2 million tonnes per annum and produce 400 000 ounces of gold. The STP has been designed, built and commissioned. and has been in operation since February 1994. The Plant boasts the world's largest Bio-oxidation facility which is capable of treating 790 tonnes of sulphide concentrate per day at a grade of 11.4% sulphur and is currently undergoing an expansion to increase its capacity to 1050 tonnes per day. The following sections describe the reasons for selecting the BioX® Process, the plant design, the commissioning experience and the plant performance to date.

Jan 1, 1996

By Frank E. Chase

Preventing pillar squeezes, massive pillar collapses, and bumps is critical to the safe and efficient recovery of coal during room-and-pillar retreat mining. To help prevent these problems, the U.S. Bureau of Mines (USBM) has developed the Analysis of Retreat Mining Pillar Stability (ARMPS) computer program. ARMPS calculates stability factors (SF) based on estimates of the loads applied to and the load-bearing capacities of, pillars during retreat mining operations. The program can model the significant features of most retreat mining layouts, including angled crosscuts, varied spacings between entries, barrier pillars between the active section and old (side) gobs, and slab cuts in the barriers on retreat. It also features a pillar strength formula that considers the greater strength of rectangular pillars. The program may be used to evaluate bleeder designs as well as active workings. A data base of 110 pillar retreat mining case histories has been collected across the United States to verify the program. It was found that satisfactory conditions were very rare when the ARMPS SF was less than 0.75. Conversely, very few unsatisfactory designs were found where the ARMPS SF was greater than 1. 5.

Jan 1, 1995

By M. Fig, A. Juganda, M. Zurhorst, J. Brune, C. Strebinger, G. Bogin

"Understanding the airflow patterns in and around the longwall panel can help to identify poorly ventilated areas that may be prone to methane accumulation. Ventilation network modeling provides quick simulation time, and flexibility in adjusting airway parameters and ventilation controls. Such modeling is effective for analyzing linear ventilation networks in underground mines, but cannot compute flows in caved areas of hard rock mines or longwall gobs. The use of Computational Fluid Dynamics (CFD) enables a more detailed investigation of the interaction between the airflows in these caved areas but requires much longer computational times, designing complex meshes and determination of a variety of modeling parameters. Airway friction factors and ventilation controls are simple to implement in a network model but can be difficult to model and adjust in CFD. This paper will focus on using mine ventilation network simulation to identify and analyze key parameters that are affecting airflow distribution in and around the longwall panels, prior to more detailed analysis with CFD modeling, using the example of a longwall coal mine. INTRODUCTION In longwall coal mine ventilation systems common in the U.S., the main purpose of bleeder ventilation is to dilute methane gas and prevent the formation of explosive gas mixtures in the caved, poorly ventilated gob areas and adjacent mine workings. In longwall operation, these critical areas include the development headings inby the longwall face, and the gob. Methane-air explosions in these areas may be ignited by spontaneous combustion, rock-on-rock friction and other sources. Although rare, ignitions due to rock-on-rock friction caused by roof falls caving into the longwall gob are possible and were suspected in the Willow Creek mine explosions in 1998 and 2000 (Elkins et al., 2001; McKinney et al., 2001). Rock-on-rock frictional ignitions are difficult to prevent, as they occur in inaccessible areas. Therefore, rendering the gob area inert is essential to prevent the formation of explosive mixtures. Research by Gilmore et al. (2015) and Brune et al. (2015) has shown that gob inertization can be a difficult or impossible when using bleeder systems, since the flow of gases through the gob depends on the gob permeability and the amount of fresh air leaking from the face and the immediate roof caving conditions cannot be controlled by the mine operator. Having the ability to predict the location where explosive gas zones (EGZs) form inside the gob will be helpful for designing the best ventilation setup to minimize explosion and fire risks."

Jan 1, 2018

By Loic Galisson

"Urban tunneling projects are usually extensively monitored. Most of the instruments used rely on benchmarks providing a sustainable datum throughout the life of the project. The monitoring program also is based on a predicted model of deformation induced by specific construction methods. Events can interfere with those assumptions and eventually alter the stability of these datum. In addition, the anticipated ground conditions and hence the theoretical deformation model often differ from reality. Satellite Radar Interferometry provides useful information to overcome the weakness of the hypothesis made before construction. It is also a powerful tool to ensure the continuity of the monitoring program throughout the life of the project, accurately describing the true effect of the project on the surrounding environment. This paper emphasizes the benefits and limitations of this technique for urban tunneling applications, illustrated by examples of major tunneling projects around the world. MONITORING URBAN TUNNEL PROJECTS Why Monitoring? Retrofitting existing tunnels or constructing new tunnels – including access and retrieval shafts, portals and cross passages – implies an alteration of the neighboring soil structure. Excavating, dewatering, grouting, loading tie backs, etc. artificially modifies the natural equilibrium of the pore-water pressure, of the water table level and of soil stability. In many cases, the effects are immediate: ground loss, deformation of utilities, settlements of buildings, and distortion of infrastructure are a few examples resulting from construction activity.Instrumentation and Monitoring Scope To control and mitigate the risks of damage associated with the above effects, tunnel projects usually include an instrumentation and monitoring program. Depending on the level of geotechnical, structural and environmental risk, the magnitude of this program varies. Projects with a low exposure to risk may restrain the program to conventional methods such as limited topographical surveys and intermittent manual readings of geotechnical instruments. On the other hand, iconic projects with high risk or with controversial history may implement complex and extensive instrumentation plans, involving highly technical solutions such as Automated Motorized Total Stations (AMTS – see opposite Picture 1), Multi-Point Borehole Extensometers (MPBX), In-Place Inclinometers (IPI) and a wide series of fully automated geotechnical, structural and environmental sensors. In this case, all the devices are usually connected to field data loggers collecting raw data around the clock at frequencies ranging from days to seconds, depending on the sensors."

Jan 1, 2016

By Howard G. Coopersmith

A resource of low grade good quality diamonds has been discovered through the Diamond Company NL-Moonstone Diamond Corp. Joint Venture. A limited bulk sample diamond test of two large kimberlite pipes on the Kelsey Lake Property, Colorado, has been completed. These kimberlite pipes have petrological and mineralogical indications of the presence of diamond. Small diamonds were recovered from surface samples. Drilling and trenching revealed both pipes were complexes of diatreme facies kimberlite. One pipe contains crater facies kimberlite as well. This is the first reported occurrence of crater facies kimberlite in the Province. Approximately 1000 tonnes of kimberlite rock was excavated and processed through a scrubber -HMS -Sortex -Grease Plant. Significant diamonds were recovered. The diamonds were generally of good color and clarity, with many being in the gem and near gem categories. Grades are considered low however. Additionally, a small potential resource of alluvial diamonds is present.

Jan 1, 1991

By J. D. Miller

On the basis of nonequilibrium zeta potential measurements by laser-Doppler electrophoresis, the sign of the surface charge of alkali halides in their saturated brines has been established. The results are generally as expected from simplified lattice ion hydration theory. This recent electrokinetic information coupled with the stability and prevalence of collector colloids in such soluble-salt flotation systems suggests that the selective flotation of alkali halides is due to the adsorption of oppositely charged collector colloids by heterocoagulation. Experimental flotation results confirm this surface-charge/collector-colloid adsorption model and are presented herein.

Jan 1, 1992

By John E. Dreier

The Pachuca-Real Del Monte district, Hidalgo, Mexico (Figure 1) has produced roughly 1,500,000,000 oz Ag., 6,000,000 oz Au. and minor Pb., Zn, and Cu from about 100,000,000 tons of ore since discovery early in the 16th century. Production has come from epithermal vein deposits that have been up to 8 km in length, 650 m in vertical extent and 45 m in width but which averaged 200-400 m in length and vertical extent and 2-4 m in width. Ore deposits occur through-out an area about 12 km E-W by 10 km N-S (Figure 2) and between the elevations of 2000 and 2800 m above sea level. The deposits occur as shoots in the veins and terminate laterally where the veins narrow, upward where the veins pinch out and downward where the veins decrease in silver con-tent to below the cut-off grade; the veins are known to extend 500 m below the bottoms of the ore bodies and probably extend to much greater depths. The district lies wholly within a mid-to-late Tertiary volcanic rock sequence that is made up principally of andesite and dacite lava flows and flow-breccias. Although the bottom of the sequence is not exposed in the district, stratigraphic constructions indicate the volcanic rocks to have an aggregate thickness of 2000 to 2500 m. Structurally, the area is characterized by gentil warping and normal faulting of the volcanic rocks. Pre-ore modifications to the volcanic rock sequence consisted mainly of faulting along west-trending, south-dipping normal faults and north-trending high-angle faults.

Jan 1, 1978