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By Siegmund Babendererde, Jan O. Babendererde

Extruded Concrete Lining combines technological and financial advantages. The tunnel lining is reliably embedded in the surrounding ground as the fluid concrete is extruded at constant pressure directly behind the TBM supporting the exposed surface. Ground deformation from the TBM passage can be compensated and the ground will be pre-stressed by the extrusion process. Developments in concrete technology permit high speed tunneling by use of a slip formwork attached to the TBM. Realised projects in Milano (Italy), Lyon (France), Frankfurt (Germany) and Akima (Japan) will be demonstrated.

Jan 1, 2001

By Dale Matthews

The Getchell Mine, near Winnemucca, NR, was discovered in the 1930s and was initially mined to recover gold from oxide ores. During the 1940s and 1950s, gold was recovered from the highly refractory arsenic sulfide ores using horizontal kilns to roast the ores. During the 1960s, fluid bed roasters were used to oxidize the ore and recover the gold. The mine was shut down from 1968 through 1985. In 1985, heap leaching was started on the low-grade oxide ores that were available. In 1989, a pressure oxidation circuit was started to recover gold from the higher grade sulfide ores. Flowsheet The basic plant flowsheet of the Getchell Mine are shown in Figs. 1 and 2. The plant was designed to process a nominal 2.7 kt/d (3000 stpd) of ore with about an 85% onstream availability and a gold production of 15.5 kg/d (500 oz/ day). Run-of-mine (ROM) ore is fed directly to a wet semiautogenuous grinding (SAG) mill after the +457-µm (+18in.) rock is removed on a stationary grizzly. From the SAG mill, the ore goes to a ball mill where it is ground to 80% -75 µm (-200 mesh) and is then sent to a thickener. The SAG and ball mill operate in closed circuit using cyclones.

Jan 1, 1994

In 2005, CANMET-MMSL used its pool of expertise in ground control, open pit and underground mine engineering, mineral processing, information technology and applied mineralogy to launch a mine-to-mill research project. The objective of the project was to optimize the distribution of rock breakage energy among blasting, crushing and grinding activities, thereby maximizing the efficiency of energy utilization within comminution processes. Tests were designed to demonstrate that this approach could reduce energy consumption, thus contributing to the reduction of green house gas (GHG) production in the Canadian mining industry. The project was accomplished in collaboration with DynoConsult and Dyno Nobel Canada Inc., a world leader in commercial explosives. Data analysis from 12 blasts (six with electronic and six with pyrotechnic detonators) in three different geological formations of a quarry (soft, medium and hard rock) shows that electronic blasting technology increases rock fragmentation by 15% (in hard rock) to 20% (in soft rock). A more uniform rock fragment size distribution is also obtained. The impact of the improved quality blast product on downstream processes of the quarry is a productivity increase of 5% in rock excavation and transportation, an energy reduction of 10% at the primary crusher and an increase of 15% of the primary crusher throughput. Extended to the Canadian mining industry, such results would represent a GHG emission reduction of about 0.05 Mt/y. A soft-sensor prototype, based on primary crusher data (i.e., energy consumption, throughput, feed and product size distribution) and a simplified computerized process model, was developed for on-line measurement of the rock operating work index. Additionally, 385 rock samples and specimens were collected and prepared to determine the tensile and compressive strength of the rock material, to evaluate the aggregate crushing work index and to examine the development of micro- and macro-fractures by means of binocular and SEM microscopy. Blast-induced rock damage was evaluated at the end of the laboratory-testing program. Even though a reduction of rock hardness of around 30% was observed after blasting, the impact of the blasting method (i.e., use of electronic or pyrotechnic detonators) on the induced rock damage could not be observed. It is either absent or not perceptible with the accuracy of the measuring techniques and the number of samples analyzed.

Jan 1, 2008

By Neel Gupta, Dustin M. Crandall, Brijes Mishra

X-ray computed tomography (CT) images of rock specimens often contain artifacts which must be corrected before scientific analyses are performed. This paper presents a new workflow of automated image processing to utilize poor-quality X-ray CT scan images. The workflow runs on the open-source image analysis software and efficiently separates desired features from low-contrast scanned images. The new workflow is a two-step technique using contrast enhancement and automated feature segmentation to generate noise-free binary images. The results of binary images using the proposed workflow and using a conventional thresholding technique are analyzed to show the quality of the proposed method. The paper also presents a workflow of estimating the structural geometries of features in two and three dimensions. The results of the structural feature analyses and computational time were compared between the open-source (ImageJ) and commercial image analysis software (Bruker Computed Tomography Analyzer). The commercial software was more computationally efficient, but the task-specific macros in open-source software enabled the user-desired automation in image processing and data extraction of desired structural features of comparable quality.

Sep 8, 2022

Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the loads that will be carried by them, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses to be used in pillar design. The empirical methods are based on equations derived from large databases of various case studies. They are implemented in government-approved design tools and are widely used. There are also analytical and numerical techniques used for more detailed analysis of the induced loads. In this study, two different longwall mines with different panel width-to-depth ratios are analyzed using different methods. The empirical method used in the analysis is the square decay stress function that uses the abutment angle concept, implemented in pillar design software developed by the National Institute for Occupational Safety and Health (NIOSH). The first numerical method used in the analysis is a displacement-discontinuity (DD) variation of the boundaryelement method, LaModel, which utilizes the laminated overburden model (Heasley, 1998).

Jan 7, 2020

By Brianna M. Eiter, Jennica L. Bellanca

Mineworkers face a challenging and dynamic work environment every workday. To maintain a safe workplace, mineworkers must be able to recognize worksite hazards while they perform their jobs. Though hazard recognition is a critical skill, recent research from the National Institute for Occupational Safety and Health (NIOSH) indicates that mineworkers fail to identify a significant number of hazards. To further the understanding of mineworkers’ hazard recognition ability and to begin to address hazard recognition performance, NIOSH researchers analyzed data collected during a laboratory research study to determine the effect of individual mineworker factors including risk attitude, work experience, and safety training on hazard recognition accuracy. The results of this study show that mineworker risk attitude and safety-specific work experience affect hazard recognition performance while hazard-specific safety training does not. These results suggest that some of these individual factors can be overcome through experience and training. Potential strategies that can be used to address these factors are also discussed.

Aug 31, 2020

By M. Z. A. Bakar

A series of full scale laboratory linear rock cutting tests was carried out with a long bladed single disc cutter (292 mm diameter, 11mm wide constant cross-section blade) on dry and water saturated sandstone blocks using a linear rock cutting machine (LRCM). The muck collected from the cutting tests has been analyzed to establish a link with the specific energy (SE) of the operation. Coarseness index (CI), a non dimensional parameter, has been found to be a useful indicator of the relative efficiency of the cutting operation. An inverse relationship of the form SE = k CI-n is observed between SE and CI with very high CI usually corresponding with the lowest values of SE. The power n of the relationship for both dry and saturated rock tests is much less than the values found in the previous studies using constant cross section disc cutters and is believed to be dependent on the strength of the rock and the cutter type used. Although the average CI is found to be lower for saturated rock than for dry rock, at the same time saturated rock cutting is found to be less energy intensive (in terms of SE) than dry rock cutting. Moderate correlation exists between the production rate or yield and the SE of the cutting operation for both dry and saturated rock, which can provide some useful information about the field production rate discounting the effect of discontinuities in the rock mass.

Jan 1, 2012

By W. D. Monaghan

One of the major ignition sources of fires and explosions in underground U.S. coal mines is flame cutting and welding. On May 20, 2006, a flame-cutting operation at the Darby Mine No. 1 led to an explosion that resulted in five fatalities. On Jan. 22, 2003, another explosion caused by flame cutting at the McElroy Mine resulted in three fatalities and three serious injuries. On June 22, 1999, a flame-cutting and welding operation at the Loveridge Mine caused a fire that required sealing the mine for an extended period. On March 19, 1992, an explosion initiated by welding at the Blacksville No. 1 Mine resulted in four fatalities. These examples of mine incidents demonstrate the need to conduct research to develop best practices for safely conducting flame cutting and welding in underground coal mines. The National Institute for Occupational Safety and Health (NIOSH) conducted a study on fires and explosions in underground U.S. coal mines that were caused by flame-cutting and welding operations to determine the root causes of these types of incidents. The methodology included interviewing mining personnel who perform flame-cutting or welding operations in underground U.S. coal mines and visiting mines to observe these operations. In addition, MSHA reports of investigations and accidents statistics were analyzed. The findings were used to identify and compare differences between flame-cutting and welding practices and techniques in small and large mines, eastern and western mines, low-seam and high-seam mines, room-and-pillar and longwall mines, and between experienced miners and new miners. As a result of this study, best practices were developed to reduce the number of ?res and explosions caused by flame cutting and welding. This paper provides a summary of this research.

Jun 1, 2010

By A. Bascetin

Materials produced in quarries have been used for different intentions such as concrete and cement raw material, asphalt and embankment aggregates, railway ballast. Especially in cement manufacturing, the chemical composition and the uniformity of the raw materials play a strategic role in the economy and quality of the cement process. Therefore, it is necessary to achieve uniformity and desired chemical composition and maintain these at all production stages according to the type of cement produced. To achieve this goal the production planning and pit design play an essential role. This paper briefly outlines the production optimization of cement raw materials in a quarry in Istanbul western part of Turkey. For the purpose it was used the 3D ore body modeling and the geostatistical techniques. The variation of chemical components (%CaO, %Al2O3, %Fe2O3 etc.) and quality control parametres (LSF, SR, AR and etc.) obtained from the quarry were determined. Then the values of unknown chemical components and quality control parameters in the ore body were estimated using Kriging which is one of the geostatistical interpolation methods. The open pit design was also created by specifying wall slopes and taking into consideration of the grade distributions of the benches. The most important revolution in the paper is investigating the effects of the block dimensions in block modelling which is important for reserve estimation. The other important point in the study is using the different range values in variogram analysis for determination optimal reserve estimation. n this study, the effects of two parametres on reserve and waste amount estimation were determined according to CaO% distribution. The study was pointed out that the changing of the two parameters are very important for the optimal mine planning and environmental considerations.

Jan 1, 2010

By Christopher J. Bise

INTRODUCTION The control of nuisance water in a mine is extremely important; left uncontrolled, nuisance water can have a severe effect on haulage, ventilation, production, and the health and safety of miners. To control water in mines, a four-step process is followed: (1) prevention, (2) collection, (3) transportation, and (4) treatment. This chapter will be devoted to the collection and transportation of mine water because prevention is usually dictated by pre-mining conditions and initial planning, while treatment is variable and highly site specific. A mine drainage system is nothing more than a collection of gathering points (sumps), machines that impart energy to the fluid (pumps), transportation ducts (pipes), and control devices (fittings, valves, etc.). A pump does not pull the fluid up the suction pipe; atmospheric or external pressure pushes the liquid up the suction pipe to the pump. All references in this chapter will be to centrifugal pumps, due to their popularity for mine drainage. PUMP CHARACTERISTIC CURVES The performance of a pump is plotted on a graph as an indication of its characteristic. To develop the data points, a test facility similar to that shown in Fig. 1 is established. The calibrated Venturi meter is used to measure quantity, the Bourdon gage measures pressure, and the wattmeter measures power input. Various discharge pressures are obtained by throttling with a gate valve in the discharge pipe. Quantity and power are measured at each of these pressure levels, giving the necessary data for plotting the characteristic curves. Fig. 2 shows a typical characteristic curve for a centrifugal pump. Notice that pressure is measured as so many feet of vertical water column above the outlet level, or head. Knowing the quantity (in gallons per minute), head (in feet), and power input (brake horsepower), the pump's efficiency can be plotted based upon the following relationship:

Jan 1, 1986

By Erica Frederickson

"Millennials. Doesn’t the word just make your blood boil? You’ve probably encountered one of those kids who think they know best despite a lack of any real experience.Hi, my name is Erica, and I am a Millennial. We often get a bad rap, sometimes for good reason. But we do have qualities that are often overlooked. For example, I am happy to share with my generation a real desire to make a difference in the world and a commitment to innovation. Does this mean I think we always have good ideas? No – especially not right away. After all, few of us came anywhere near a piece of construction equipment until arriving for our first job, as was the case for me. We may have fancy degrees, but not many of us learned to run a jackleg drill in school.Two weeks after graduating college in 2011, I packed up my bags and moved to New York City to work as a field engineer for Traylor Bros. Inc. on the Queens Bored Tunnels project (Granite/Traylor /Frontier Kemper, JV), part of NYC MTA’s multi-billion dollar Long Island Railroad East Side Access project. It was here I became acquainted with the notorious New York City union workers. Perhaps the greatest challenge of my career thus far was earning the respect of the field supervision and craft workers on this first project.The first time I asked a maintenance mechanic to clean a piece of equipment in accordance with our maintenance protocol I got a flat-out “No.” It was the most powerless I had ever felt. But why should these experienced workers trust a 21-year-old girl with her civil engineering degree and no prior experience? I realized no employee on the job had any reason to listen to me — not until I proved my worth. Fortunately, I arrived on the job site just as we were commissioning the slurry plant for the first tunnel drive. I dove into learning as much about the slurry tunneling process as possible and was able to quickly pick up the ins and outs of running the slurry separation plant. As none of the other engineers or management had first-hand experience on a slurry tunneling job, I soon became the go-to engineer in the slurry plant. No one questioned me if I asked to have something done around the plant after that, or if they did, they quickly learned that I had a convincing answer as to the need for the task. I was even able to play a large role in shaping our slurry monitoring and control methodology."

Jan 1, 2015

By F. Taylor Ostrander

Some countries are infinitely poorer than others in mineral resources-despite the perfect equality of their political leaders ambitions. Compare the mineral poverty of Kenya and Tanganyika with the riches of Katanga Province and Northern Rhodesia. Compare Paraguay with Chile, There never has been any equality in the distribution of nature's wealth. Minerals cannot play any role at all in economic development where they don't exist, and there are bound to be differential rates of economic development where there are basic differences in the wealth of mineral resources available. Africa is my principal area of interest and I know that there is an unfortunate but widespread misconception about Africa's "vast mineral resources, "its "untapped mineral wealth." Why is it untapped? Why is it undeveloped?

Jan 1, 1963

By Y. Akin

The floatability of a typical boron mineral, colemanite (Ca2B6O11.5H2O), is shown to be hindered by the presence of montmorillonite type clay minerals. The clay is found to act in the form of slime coating. The mechanism of slime coating is investigated using pure colemanite and clay and their mixtures with an anionic reagent in a microflotation cell. Adsorption, flotation, solubility, zeta potential and scanning electron microscope studies reveal that slime coating occurs through electrostatic attraction. It is possible to minimize the effect of slime coating either at high surfactant concentration or at high pH values.

Jan 1, 1997

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jason Navoyski, Jennica L. Bellanca

Haul truck fatal accidents and injuries continue to be a significant concern for the mining industry. However, the availability of high-quality training materials continues to be limited. Near-miss incident accounts, if packaged well, could help fill this gap, because for every fatality, there are hundreds of reportable accidents and thousands of undocumented near misses. Researchers from the National Institute for Occupational Safety and Health (NIOSH) collected detailed accounts of 21 near-miss incidents in virtual interviews with mineworkers at surface mining operations across the country. From these interviews, researchers created four simulation videos using the Unity game engine. The simulation videos bring these events to life through first-person retelling and various visual perspectives of actual events. Each video exemplifies a critical safety message and a common haul truck hazard. This paper describes the process of taking narratives and turning them into impactful visual stories using graphic simulation. NIOSH plans to co-release these simulation videos with the Mine Safety and Health Administration (MSHA) to the mining industry to raise awareness and ultimately help reduce haul truck-related accidents and fatalities in mining.

Jun 1, 2023

By F. W. DeVries, O. B. Mathre

Addition of Kastone® peroxygen compound and formaldehyde to cyanide gold extraction process effluents, containing at least 5 mg soluble copper per liter, will oxidize acid-dissociable cyanide to levels less than 0.2 mg per liter, without appreciable oxidation of thiocyanate. Most of the copper precipitates and is removed by filtration of the treated solutions. The treatment can be completed in less than 2 hours when the excess of hydrogen peroxide over the cyanide is about 75-100 mg per liter. The excess hydrogen peroxide destroys residual formaldehyde and then is catalytically decomposed by the copper-containing solids that separate, so it will not interfere with subsequent operation. A pilot plant using this technology has been operated for more than four months at rates from 1-2 gpm. Clear, filtered effluent containing less than 0.2 mg acid-dissociable cyanide per liter has been produced.

Jan 1, 1981

By M. E. Lewellyn

A new class of thionocarbamates, O-alkyl-N-allyl thionocarbamate (III), has been found to give better metallurgy than 0-isopropyl-N-ethyl thionocarbamate (I) for a number of sulfide ores containing copper, lead, and zinc. Data on the results of flotation tests with several such ores are presented. The improved metallurgy is believed to be due to the participation of the allyl double bond in the complex formation of the thionocarbamate on the surface of the mineral.

Jan 1, 1985

By Richard B. Stein

Section 25 has been assembled to give the geological, mining, or metallurgical engineer an overview of some of the important downstream operations that typically follow mining activities. This subject is obviously too broad and complex to be covered in detail within this Handbook. However, the engineer will be interested to learn about the basic fundamentals, and especially how they might affect the economics of the total project from prospecting and mining through to metals recovery and marketing. In this way, it is hoped that the engineer will have a better overall appreciation for the technical and commercial prospects of a mining and metal-producing project.

Jan 1, 2008

By Bradshaw, Y. S. Cho

The size of bubbles plays an important role in flotation. Equations used to calculate the size of bubbles all show the effect of liquid/gas surface tension. However, the surface tension does not change much with frother concentration and experiments conducted using single capillaries (or single-hole spargers) do not reveal any clear effect of the frother concentration on bubble size. The size of bubbles does, however, strongly depend on frother concentration when multi-hole spargers are utilized (or when measured in a flotation cell); at low frother concentrations the bubble size is much larger indicating coalescence as a main mechanism determining the size. Coalescence can be prevented at frother concentrations exceeding the critical coalescence concentration (CCC), which in turn was found to be interrelated with the dynamic foamibility index (DFI).

Jan 1, 2001

By R. W. Smith, R. K. Mehta, X. P. Zheng, A. M. Raichur, M. Misra

Experimentation was per formed on the flotation of apatite and dolomite separately using anionic collectors in the presence of Mycobacterium phlei. Also, the flotation of mixtures of dolomite and apatite in the presence of anionic collectors and in the absence and presence of the bacterium were studied. It was found that M.phlei functions as a depressant for both minerals. However, it functions as a better depressant for dolomite than for apatite. Experimentation was extended to two different Florida dolomitic phosphate rocks. In this investigation a concentrate grade of less than 1.0% MgO was achieved with a 75% P2O5 recovery.

Jan 1, 1999

By H. Sevim

In this paper, the research effort in simulating the operation of underground coarse-coal hydrotransport systems (UCCHS) is summarized. The equipment of the system to be simulated is already optimally selected by using an analytical optimization model. The purpose of the simulation model is to test the performance of the system and to obtain the distribution of the operating parameters such as water and power consumption, amount of slurry delivered to the preparation plant, etc. Knowledge of the distribution of these parameters is essential for the efficiency of the design and the operation of the system.

Jan 1, 1985