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By K. Kovári, G. Anagnostou

Slurry and EPB-shield tunnelling have been successfully applied worldwide in recent years. Under extremely unfavourable geological conditions, however, face instabilities may occur. The present paper aims at a better understanding of the mechanics of face failure. For the case of slurry shield, attention will be paid to the time-dependent effects associated with the infiltration of slurry into the ground ahead of the face. Related topics, such as the stand-up time and the effect of the excavation advance rate, will be discussed. In the case of an EPB-shield, a distinction will be drawn between fluid-pressure and effective pressure in the chamber. The effective pressure can be visualized as a “grain to grain” contact pressure between the muck and the ground at the face. The water pressure in the chamber reduces the hydraulic head gradient in the ground and, consequently, the seepage forces acting in front of the face. The face is thus stabilized both by the direct support of the pressurized muck and by the reduction of the seepage forces in the ground. The paper includes normalized diagrams which allow the assessment of tunnel face stability.

Jan 1, 1997

By David D. DiPonio, John DiPonio, Roger Van Omen

The greatest opportunity to attain the most favorable prices for underground construction projects occurs during the competitive bidding period. The Owner, Engineer, and Contractor need to have a thorough understanding of the project’s design concept, how it is going to be built, and what it is going to cost. This paper presents the opinions of three engineering professionals who are well established in their sectors of heavy civil underground public works construction. This paper will outline and summarize the considerations that the three principal contracting parties of Owner, Engineer, and Contractor need to make to obtain good price quotes at the time of bids.

Jan 1, 2005

By R. D. Williams

"In a very real sense, Butte, MT is where the copper came from that won two world wars. The price for that unrestricted mining and smelting of copper came due in 1983 when Butte was declared a Superfund site.One of the most complex remnants of this mining history is the Parrot Tailings site. The Parrot smelter operated from 1881 to 1910, moving Upper Silver Bow Creek to the south and depositing approximately 283,000 m3 (370,000 cu yd) of waste material adjacent to Upper Silver Bow Creek. Additional mixed waste from other processing sites deposited below the Parrot tailings at the Northside Tailings, Diggings East and Blacktail Creek Berm total approximately 171,000 m3 (224,000 cu yd) of contaminated material. As part of the Superfund remedy, the U.S. Environmental Protection Agency (EPA) proposed leaving all these wastes in place. This proposal prompted a detailed criticism by several geoscientists familiar with the site. The EPA’s 2006 Record of Decision (ROD) did in fact leave these wastes in place, which set the stage for a series of studies that continue to refine how best to protect extensive completed Superfund Remediation downstream of Upper Silver Bow Creek. History of the Parrott Mine and tailingsPlacer gold was discovered in Silver Bow Creek, the headwaters of the Clark Fork River only a few miles from the Continental Divide in 1864. This discovery led to a stampede of placer and lode claims. One of the first lode claims located was the Parrot lode, located in the fall of 1864. Progress for developing a mine at the Parrott was slow, and it was not until 1876 that one of the original locators encountered a rich vein of chalcocite. Butte had its first copper mine.The Parrott Mine was patented in 1879 and by 1881 the Parrot, having lost a “t”, concentrator and smelter were built. The smelter and concentrator were an immediate success with a considerable market for processing the district’s rich copper ore. In 1885, the employees of the Parrot smelter bought the Butte Reduction Works, another smelter. In 1885, dams were built on Silver Bow Creek to contain various tailings and related processing byproducts (Fig. 1).By 1890, the various smelters in Butte rendered Butte’s air quality as suffocating (Fig. 2). An 1889 funeral procession was rumored to have gotten lost in the thick smelter smoke and somehow ended up at the Centennial Brewery. A city ordinance was passed late in 1890 in an attempt to control smoke. The Parrot smelter employed approximately 500 men by 1890. Through the 1890s, the tailings produced grew from approximately 91 t/d (100 stpd) to more than 181 t/d (200 stpd). Copper values in the tailings were initially as high as 4 percent, but as the processing improved that was reduced to 1.5 percent."

Apr 1, 2019

By S. H. Brown

In our work as health physicists*, we do a lot of public speaking and interaction with the public on issues related to development of uranium mining and milling (?uranium recovery?) in the US. Understandingly, the public has important concerns about this. Accordingly, this paper is presented in a ?question and answer? format in which we have tried to capture what are some of the most common concerns we hear from citizens and address them. We have attempted to do so based on the best scientific information we have, representing information well documented in peer-reviewed scientific literature and consensus positions from both national and international scientific standard setting bodies and related committees. We have included some of the more important of these scientifically-based references to support the information provided. Practical space limitations prevent completeness in this regard in some cases. Visit the Health Physics Society?s web site or feel free to contact me directly for additional references, information or detail ? Steve Brown. The health physicist?s primary objective is to manage the beneficial uses of ionizing radiation while protecting workers and the public from potential hazards. For more information on what a health physicist is and on the Health Physics Society, visit the Society?s web site at www.hps.org.

Feb 23, 2014

By D. Bernabe

The mine scheduling process defines a mining sequence across the life of the mine and stipulates the amount of ore, waste, and specific blocks to be mined each year so that the highest economic return can be obtained under a number of constraints. There are a number of mine scheduling software packages available. Each claims to be the best scheduler by maximizing Net Present Value (NPV) or by minimizing overall mining costs. These mine scheduling programs follow different procedures and scheduling philosophies based on either mathematical or heuristic principles. There was no study in which the mine production scheduling procedures applied by these packages were discussed and compared. This paper evaluates four open pit mine scheduling programs recently developed and compares them in order to determine if significant differences exist among them. The same input data, which consist of a 3-D block model, an economic set of parameters, and the initial surface topography for a operating copper mine in Southern Peru, was used to test each technique. The following programs were investigated with respect to their ability to optimize the NPV for the case study. 1) M821V1 Scheduler by Mintec; 2) NPV Scheduler by Earthworks; 3) Milawa Scheduler by Whittle Programming; and, 4) Fundamental Tree Scheduling Method (FTSM) developed at the Colorado School of Mines. The results from this case study demonstrate that the scheduling software packages, Mintec, Earthworks, and Whittle obtained similar NPV’s, while FTSM scheduler gave a six percent higher NPV than the other schedulers.

Jan 1, 2002

By Wern-ping (Nick) Chen

In concrete lined tunnels, formwork removal timing may be controversial. Contractors seek to strip the form as soon as possible, and designers seek to keep the formwork in place as long as practical to protect the fresh concrete. Formwork removal timing is normally specified as a function to its insitu concrete strength. This approach may work for smaller diameter tunnels, but fallacy occurs when applying this approach to larger diameter tunnels, since a larger diameter would experience more displacement than a smaller diameter tunnel from its own weight. Excessive deformation may fail a tunnel to meet its roundness criterion and overstress the lining causing cracking or falling from the crown. This paper presents a contractual mechanism to mitigate this issue.

Jan 1, 2008

By Xingang Wang

Spontaneous combustion is one of the most important safety issues in the global coal industry. It is considered to be a trigger for explosions in underground mines, especially for gassy mines. This thermal event is not easily detectable in the gob and sealed area. It is also a tough job to find the most likely hot point accurately. Admittedly, determination of the propensity for spontaneous combustion before mining activity should be a necessary step in the design of a mine and ventilation plan. However, due to the complexity of the chemical and physical properties of coal, spontaneous combustion has not been fully understood. According to a proximate analysis of coal, it is believed that sulfur and volatile matter in coal are the main intrinsic factors that cause the self-heating of coal. Their oxidation at lower temperatures than that of fixed carbon to initiate coal?s self-heating should be quantified. This study aims to improve the previous mathematical model developed by the authors for studying a coal?s propensity for spontaneous combustion. It enhances the model?s ability to consider the effects of sulfur, volatile matter and moisture content in the coal ? three important factors affecting a coal?s self-heating process. Based on the law of energy conservation, heat release rates for pyrite oxidation and moisture condensation are built into the model. Finally, the simulation results in terms of time versus temperature are calibrated with adiabatic testing data extracted from the literature for pyrite oxidation and moisture condensation, respectively. From the modeling results, it is found that the higher the pyrite content the coal contains and the more moisture that condenses in an environment with high relative humidity and initial temperature, the higher the potential for spontaneous combustion.

Jan 1, 2014

By T. J. Loyd

The capabilities of the analog computer, the Mine Ventilation Simulator, installed at WHA's Safety and Health Technology Center in Denver, Colorado, are discussed. General opera- ting procedures are described showing how a mine model is produced, and how the model can subsequently be modified to produce a solution to a mine ventilation problem. A sample problem is included to illustrate the technique. The important role the Mine Ventilation Simulator plays in ventilation training is discussed, including experiences with the education of students at the Colorado School of Mines. This paper includes a summary of some of the advantages and disadvantages of the analog technique and suggests some design criteria for application to future development of analog computers, based on experience gained with the Mine Ventilation Simulator.

Jan 1, 1984

It had been more than a decade since this many booths were occupied at an SME Annual Meeting, but at the 2010 meeting in Phoenix, AZ 630 booths were sold to 470 vendors from the entire spectrum of the mining and minerals industry. Exhibitors such as Metso, FLSmidth, West-Tech, ABB, NIOSH, Eriez and Resource West took their usual prominent places on the exhibit floor and were joined by newcomers such as tunnel boring machine manufacturer Herrenknecht AG, Frontier Kemper, the International Society of Explosive Engineers and more than 100 other first-time exhibitors. On the floor, one could find everything from a new pair of boots to a new career in the recruitment pavilion where some of the biggest companies in mining (Barrick Gold, Freeport-McMoRan, Newmont Mining, etc..) set up shop. The following is a look at some of the companies and products that were on display at the 2010 meeting. For information about displaying at the 2011 annual meeting in Denver, CO, Feb. 27 to March 2, contact exhibits@smenet.org.

May 1, 2010

By Dick T. Atkinson

Due to improvements in the safety of other aspects of mining (primarily in roof control), haulage related accidents, particularly rail haulage accidents, are about to become the most common category of hazards causing death and injuries to underground coal miners. The major causes of these accidents are collisions between vehicles, men caught between rib and trip or between cars, derailments, and runaway cars. Such hazards can be greatly reduced if the motorman has the capability to selectively couple and uncouple cars from the cab of the locomotive, to transmit braking intelligence to the coupled cars, to determine if the trip is intact, and if brakes are automatically applied in any uncoupled car. These capabilities can be provided through an improved coupler system, designed and built by Foster-Miller Associates under a Bureau of Mines contract. Early in the program, a survey of rail haulage patents and literature was conducted. Manufacturers of couplers, mine cars and braking systems were contacted and information relevant to the remote control mine haulage application was collected. From this information evolved a working specification and a design concept. The key elements of the specification, shown in Table I, are the result of a detailed tradeoff study and considerable thought given to the specific problems encountered in the mining environment. A brief explanation of each element is as follows: Automatic Coupling - The couplers operate similarly with most already in underground use - they latch together when a trip is backed into a car intended for coupling. Remote Uncoupling - From the locomotive, the motorman can decide how many cars are to be uncoupled, operate the appropriate controls, and the desired coupler is opened.

Jan 1, 1977

By Timothy D. Arnold

Barrick Gold’s Bullfrog underground mine, near Beatty, NV, was established as an after-thought to the main open pit. As open pit ore dwindles, the underground mining became increasingly more important as an ore source, and to the overall economics of the project. This situation is similar to many other mines. Today, there is a move towards underground mining in the United States. There are inherent problems in starting and operating underground mines in the shadow of any open-pit operation. Several attempts were made at the Bullfrog Mine for productive increases. Some were successful, while others were not.

Jan 1, 1996

By Allan M. Hale

Taconite tailings reclamation, especially the stabilization of tailings ponds, .dams, and slopes, can be effectively accomplished through the use of appropriate vegetation. Utilizing vegetation provides both aesthetic and ecological enhancement of a site while at the same time protecting tailings structures against wind and water erosion. Generally, the methods and techniques for establishing vegetation are well known; however, there are many site-specific factors that can alter a particular reclamation approach. Those factors include slope gradient, tailings material size, solar exposure, and physical and chemical properties of tailings. In addition to the site-specific factors, variations in climate, geography, and physiography of a region can have a pervasive influence on the success or failure of a revegetation program. Both the site-specific and regional factors control reclamation planning in such areas as plant variety selection, methods and times of plants establishment, maintenance techniques, and subsequent monitoring methods. As a result of this multifactor relationship, it is important to establish a data base that identifies both the site-specific and location conditions in order to tailor the reclamation plan to the specific area. When an appropriate data base has been collected, detailing the various site-specific and regional factors that will influence a revegetation program (in the absence of previous testing), it is very beneficial to apply experimental techniques to develop the reclamation plan for a specific site. The reclamation plan for a specific site may include several techniques adapted for the differences found within the specific site as the result of topographic or other influences. Considering this, the Reserve Mining Company and Dames & Moore undertook to develop a successful reclamation plan based on a detailed test plot program conducted at the Mile Post 7 location.

Jan 1, 1980

By L. Lacerda, C. Rose, E. Zellers

Approximately six hundred air sample measurements were taken at several U.S. underground metal/nonmetal mines in 1998 and 1999. This air sampling effort was organized by the Nevada Mining Association to evaluate mining conditions and to evaluate the Mine Safety and Health Administration’s (MSHA) Proposed Rule on Diesel Particulate Matter Exposure of Underground Metal and Non-metal Miners. MSHA’s proposed air sampling method, NIOSH Method 5040, was tested under controlled conditions and under normal mining conditions. Unfortunately, NvMA sampling results have indicated that carbonaceous rock dust, oil mists and even cigarette smoking create severe sampling interference problems for NIOSH 5040.The main conclusion was that NIOSH 5040 did not distinguish between DPM and other airborne carbon particulate. Thus, it is not a reliable method of accurately and unequivocally measuring DPM in underground metal/nonmetal mines.

Jan 1, 2000

By M. Prud’Homme

Potash is an important natural mineral used largely as a fertilizer in the production of food and fiber. About 93 percent of all potash consumed globally is used in agriculture as fertilizer. The balance is used to manufacture potassium chemicals. Most potash is extracted by conventional underground mining methods. Solution mining is used when underground deposits are irregular and very deep. The other main production method involves the evaporation of brines in shallow salt lakes, followed by the harvesting of potassium minerals.

Jan 1, 2005

By R. Mensah-Biney

The aqueous biphase separation process (ABS) has been used to separate ultrafine industrial minerals. The partition behavior ofTiO2, Al2O3, Fe2O3 and kaolin was not pH dependent. The partition behavior of SiO2 was, however, pH dependent. The partition coefficient of kaolin in PEG 3400/ Na2CO3 biphase system was 150 and that of the silica in the same system was 0.02, resulting in a separation factor of 8500 between kaolin and silica. The aqueous biphase separation system was used to separate free silica from kaolin in a raw clay sample from Mexico. The partition behavior of mica, feldspar and clay from North Carolina was also evaluated.

Jan 1, 1999

By K. M. Kim

An analysis was conducted to determine the effects of blasting on slope stability and downstream comminution processes. To investigate these effects, the extent of blast-induced rock damage and the magnitude of induced stress were examined. This analysis showed that damage may extend up to 500 m (1 MPa, tensile strength) into the rock mass, a distance that is sufficient to have an impact on the pitscale slope over the long term. In addition, the damage zone was calculated using the assumption that compressive waves are the primary agent in microfracturing during blast fragmentation. The calculated damage zone — up to 2.2 m (43 MPa, rock mass compressive strength) — indicates that microfracturing can occur throughout 20-50% of the entire rock mass in the blasting area, depending on the blast geometry, burden and spacing. Finally, an economic analysis was conducted by comparing two assumed blasts in a copper mine. The change in energy required for crushing and grinding was demonstrated using Bond’s law after increasing the blast energy from 180 kcal/t to 350 kcal/t. A total cost saving of 13.3% ($9.4M) was achieved with the increase. However, the benefits of blast-induced microfracturing must be balanced against the potential impacts to slope stability to ensure safe conditions, a top priority in mining operations.

Jan 1, 2014

By T. Yegulalp, R. Farrauto, A. Belova, M. Castaldi

Calcium oxide, with its ability to capture and store carbon dioxide, is emerging to become an important tool in carbon management. Calcium oxide can be used reversibly to capture carbon dioxide in situ and then be regenerated to produce a pure stream of carbon dioxide ready for sequestration; the Zero Emission Coal Alliance technology utilizes this property of calcium oxide to generate emissions-free electric power from coal. The reaction of calcium oxide with carbon dioxide resulting in thermodynamically stable carbonate is well understood; however, the efficiency of this reaction is limited by the diffusion of gases through bulk calcium oxide and through a layer of carbonate formed on the surface. In addition, the regeneration of calcium oxide is an endothermic reaction and is favored at high temperatures. The purpose of this paper is twofold: first, to address the diffusion limitation, a thin layer of calcium oxide, supported on a high surface area material, is studied thermogravimetrically to demonstrate the physical adsorption of carbon dioxide on calcium oxide. The adsorption is to take place at temperatures lower than required to form calcium carbonate.

Jan 1, 2007

By Kraig W. Grubaugh

Rapid growth in the rate of surface mining for coal has caused many states to increase the rigor and complexity of their surface mining codes. The promulgation of Federal surface mining standards may cause those states containing Federal land to amend their codes also. Presented is an up-to-date review of these codes with tabular summaries that divide the codes into operative functions. These summaries will be of use to new operators, multiple-state operators, and state officials. Suggestions are made for industrial efforts to present workable and acceptable amendments to these codes.

Jan 1, 1977

By Michael E. Stickney

"Soft technology" computers and computer programs-brings to mind a room full of machines, tape drives, disks, plotters, and printers spitting out financial reports. Computers now have a much broader scope of applications because of reductions in equipment size and cost. For example, people now interact directly with computers to control events. Such computers and associated equipment-called interactive control systems-are often small, relatively inexpensive, and can be designed to increase productivity at mining operations. This is accomplished by improving communications between individuals; giving employees the information needed to make decisions in real time, as events are happening; and giving individuals the background needed to perform more effectively. This paper will describe a procedure for determining the return on investment for interactive control systems, and describe four such systems. The analysis process is general in nature and can be applied to any type of mining operation or production process.

Jan 4, 1981

By M. N. Semenoff

On July 8, 1999, EPA announced the RCRA Cleanup Reforms, a set of administrative reforms designed to achieve faster, more efficient cleanups. This paper will discuss the Reforms, the status of their implementation and assess these potential impacts on the mining industry.

Jan 1, 2001