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By D. V. Bush

The economic application of real time computer control can be broken down into 2 broad areas of concern. The first would be in gaining the most efficient utilization of energy. The second would be in improved product quality. This paper will be primarly concerned with the first area of efficient energy utilization as that area has the greatest effect on costs and thus net profits. Most process control strategy attempt to achieve the greatest comminution with the least amount of energy thus maximizing efficiency. A more direct approach to energy control involves a total mine and mill energy management system. In most cases these systems have an ability to achieve a very short payback period with the greatest return on investment.

Jan 1, 1986

By Patricia Pride, Kurt Bettger, Jack Raymer

"INTRODUCTION The Jefferson Barracks Tunnel is in the final stages of design and is expected to go out to bid in the summer of 2016. The project is located in south St. Louis County along the west bank of the Mississippi River, about 13 km downstream of the St. Louis Gateway Arch. The project consists of a deep sanitary sewer tunnel, a deep pump station and several intakes. The intakes will divert sanitary flows into the tunnel and the tunnel will convey the flows by gravity to the Lemay No. 3 Pump Station, which will pump them up into the Lemay Waste Water Treatment Plant. The tunnel is about 5.4 km long and will be lined with 84-inch (2.1 m) fiberglass pipe. It drops at a gradient of 0.1 percent from south to north and will be bored through strong limestone using a hard-rock tunnel boring machine (TBM). The diameter of the TBM is anticipated to be about 3.4 m. The Owner’s original concept was for a relatively shallow tunnel so as to minimize construction and pumping costs. The preferred alignment ran close to the river, next to the existing force main, which was to be abandoned. Keeping the tunnel close to the force main would reduce the amount of shallow sewer work needed to connect the existing feeder sewers to the new tunnel. Several geotechnical investigations were performed, with shallowly focused geophysics and the borings all going exactly down the conceptual tunnel depth. Limestone bluffs run along the Missouri side of the river. These bluffs are pockmarked by sinkholes and riddled with karst. Large, well-known caves occur both north and south of the alignment. Karst features, including deep crevices and possible caves, were found in those early geotechnical investigations. Many of these features extended well below the level of the Mississippi River and would have been encountered by the tunnel. If a large crevice or cave were encountered, then the inflow of mud and water into the tunnel could have been large and possibly uncontrollable. Something had to be done to mitigate this situation. Pre-excavation grouting was considered, but the program would have been huge and extremely expensive. Using a closed-face TBM with bolted and gasketed lining was also considered, but that too was both risky and extremely expensive. The Owner could have abandoned the tunnel altogether and built a new force main, but that would have brought a whole new set of problems and was undesirable to the Owner. The last option was to move the tunnel away from the karst."

Jan 1, 2016

By Christoph Schulte-Schrepping, Bou-Young Youn, Rolf Breitenbücher

"The main requirements of two-component grouts are a high workability and sufficient stability against sedimentation with a retention time of more than 72 hours, as well as a rapid strength development im-mediately after grouting. Component A usually consists of OPC, water, bentonite, and retarding agent. Component B, a liquid accelerator, is added to Component A during grouting at the end of the shield tail. Current investigations on different compositions of Component A showed a high workability lasting for at least 72 hours. The workability could be extended with increasing amount of the retarding agent to a certain degree. An increase of the bentonite content improved the stability of the mix, but had a negative impact on the flowability respectively the workability of Component A. High compressive strengths could be rather achieved by an adapted mixing ratio of Component A and B than by increasing the amount of the accelerator. Thereby, the interactions and compatibility of the selected constituents play an essential role. INTRODUCTION In mechanized tunneling with segment linings, the annular gap between segment ring and soil must be filled instantaneously with an adequate grouting mortar. The main functions of the annular gap grouting are to stabilize the tunnel lining and to minimize settlements of the ground surface at the same time. Thereby, two contradictory requirements are demanded on annular gap grouts: On the one hand a high workability and sufficient stability against sedimentation, on the other hand a rapid strength develop-ment immediately after grouting. Besides single-component grouts, which achieve the necessary stiffen-ing by dewatering into the surrounding soil, two-component grouts are used, especially in cohesive soils with a very low permeability. Basically, annular gap grouts are almost exclusively defined on empirical basis. Fundamental studies about the constituents and composition of the grout as well as the related achievable properties are still missing so far. Therefore, it is necessary to investigate the material-specific correlations regarding the relevant parameters of annular gap grouts – workability and flowability, stability of the mix as well as strength development – in comprehensive experiments. Based on the knowledge gained from the investigations, it should also be possible, to perform the grouting material according to a real design concept and thus, to ensure an adequate grouting in prac-tice considering the geological and hydro-geological conditions."

Jan 1, 2016

By Verya Nasri, Kevin Akbarpour, Hiva Mahdavi

"The Sheppard East Light Rail Transit (SELRT) project comprises approximately 13 km of new light rail, which will be constructed along Sheppard Avenue East in Toronto. There is a 380 metre long section of the route that will be constructed as tunnel below Highway 404, which is owned by the Ministry of Transportation Ontario (MTO). MTO has published guidelines for tunneling under its highways. An impact analysis was undertaken to predict the surface settlement and angular distortion of Highway 404 resulting from the construction of the twin tunnels. The results were then compared to the performance criteria defined in MTO’s guidelines. As a result of this analysis, it was necessary to request an adjustment to MTO’s current performance criteria. This paper presents details and results of the impact assessment, approaches taken to satisfy the requirements defined by MTO, and provides details of the adjustment permitted by MTO. INTRODUCTION Several major rapid transit projects are planned for the Greater Toronto and Hamilton Area (GTHA) located in southern Ontario, Canada. These projects are part of The Big Move (Metrolinx 2008) initiative, a 25-year, and $50 billion plan aimed at improving regional transportation. Metrolinx, an agency of the Government of Ontario, is now working collaboratively across the region to deliver major Toronto rapid transit projects to the GTHA. One such project is the SELRT. The line will largely run along Sheppard Avenue East on the surface, except for a crossing of Highway 404 where it will be constructed using a combination of open cut and bored tunneling methods. AECOM has been retained by Metrolinx as the Technical Advisor (TA) to develop the Reference Conceptual Design (RCD) and Project Specific Output Specifications (PSOS) for the project. Also, Infrastructure Ontario (IO) is the Co-Sponsor and CH2M HILL is Metrolinx’s Owner’s Engineer (OE) & Project Management Support (PMS) for the new LRT lines. This paper presents information on the tunneling settlement analysis and further work undertaken to satisfy the MTO’s requirements."

Jan 1, 2016

By T. J. Fenner

Surface and underground mining operations are often hindered by unknown tunnels and stopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or non-existent. The results of several Ground Penetrating Radar (GPR) studies for the detection of known mine tunnels in underground coal; salt, and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 meters.

Jan 1, 1992

By R. J. McLaughlin

Acid mine drainage (AMD) can occur as a natural phenomenon through oxidation of sulfide minerals. Oxidation by air and water can be exacerbated by mining. Because AMD can exhibit low pH, it is capable of extracting heavy metals from mineral deposits. The result is highly acidic drainage with elevated heavy metal concentrations -the combination of which can cause extensive environmental damage. Because of the importance of these factors, this paper is focused on sulfate based AMD. Due to widespread mining, the occurrence of AMD is ubiquitous. As a result, several approaches to treatment have been developed. Chemical treatment using alkali is most commonly employed to treat AMD. There are alternative methods of treatment, as well as alternative ways of handling treatment sludges or concentrates. Dewatering of sludge or concentrates is beyond the scope of this paper.

Jan 1, 1996

By M. A. Cornachione

The west central upper Peninsula of Michigan contains a large resource of graphitic slate. The slate has potential industrial use as a substitute for shale currently used in the production of portland cement. Some of the unweathered slate, however, has a high concentration of pyritic sulfur which can create emission problems when processed in a kiln. A low cost method to reduce the sulfur content of the slate through the optimization of pyrite oxidation in a bio-heap leaching operation was investigated.

Jan 1, 1992

By C. Fuellenbach, J. Brune

"INTRODUCTION Mining activities must be safe and profitable. These two requirements influence each other. The purchase and implementation of safety improvements costs money. Injuries and illnesses at mines stop or delay production and may result in additional costs or a loss of profit. Other effects of injuries and illnesses include the negative influence on employee morale, corporate reputation and conflicts with contract partners. Based on this researchers asked the question: are mines with lower rates of injuries and illnesses more profitable than mines with a higher frequencies? One aspect of this research is the evaluation of the safety situation and the measurement of benefits of safety improvements in the German mining industry. In the following paper, this part of the research will be examined. The main aim is the evaluation of injury rates in different German mining sectors and regions in Germany. SELECTION OF GERMAN MINING OPERATIONS The research team decided to focus the study on the salt and potash and the aggregate and industrial minerals mining industries in Germany. These two mining industries are different in the number and size of operators, structure of the industry, pricing and markets. The selection of two different industries adds to the clarity of the evaluation. Salt and potash mining industry The German salt and potash industry is primarily located central Germany. All salt and potash mines in Germany are underground operations. In 2015, the German potash industry employed 8,100 employees and generated a total revenue of 2 billion Euros. German potash reserves include magnesium compounds like kieserite (MgSO4·H2O), in addition to sylvite (KCl) and carnallite (KMgCl3·6(H2O)). The German salt industry employed 2,300 people in 2015 and generated revenue of 800 million Euros (Krueger, 2015) There are seven mining companies with salt and potash operations: esco-european salt company GmbH & Co. KG, K + S Kali GmbH, Saline Luisenhall GmbH, GSES Glückauf Sondershausen Entwicklungs- und Sicherungs-gesellschaft GmbH, Südwestdeutsche Salzwerke AG, Wacker Chemie AG and Südsalz GmbH. In this way, esco – european salt company GmbH & Co. KG is an affiliated company. Esco was founded as a joint venture of K + S and Solvay in 2002, since 2004 K + S is the sole holder (esco - european salt company GmbH & Co. KG, 2016). Likewise, the Südwestdeutsche Salzwerke AG has a controlling interest in Südsalz GmbH (Südsalz GmbH, 2016). Aggregate and industrial minerals mining industry The aggregate mining industry in Germany is comprised of many small mining operations and relevant companies. According to the German Department of Economics (BMWi, 2015), the following industrial materials are classified as aggregates: fluorite, barite, kaolin, quartz and quartz sand, quartzite, silica, loamy and foundry sand, pegmatite sand, shale, clay, bentonite, schistose, limestone and dolomite, gypsum and anhydrite, basaltic lava and lava sand, gravel and split, pebble and silicic sand and peat."

Jan 1, 2017

By R. Hogg

Sedimentation in highly flocculated suspensions of fine particles such as clays occurs through individual settling units (flocs) which have very open structures and correspondingly low density -typically less than 5% solids by volume. It follows that such settling processes rapidly lead to the build-up of a bed of flocs which are essentially close-packed, with inter-floc porosity of perhaps 50%, but with an overall solids content of no more than about 2-3 percent by volume. An important consequence is that the thickening process is dominated by the consolidation of this bed rather than by simple settling of the individual flocs. Experimental measurements of sediment consolidation in flocculated clay suspensions indicate that for a given system, consolidation rates are essentially determined by solids concentration and can be evaluated using the classical Kynch treatment. However, these rates are strongly dependent on the physical as well as chemical conditions of the flocculation process. Furthermore the extent to which gravity consolidation proceeds depends on the total weight of sediment (i.e. on both height and solids concentration). The implications with respect to thickener operation and the requirements for laboratory testing for thickener design are discussed.

Jan 1, 1992

By J. W. Shield

Refractory sulfide flotation or gravity gold concentrates are coated onto a sized support matrix and placed in a heap configuration for biooxidation. The surface coating is typically less than 0.05 in. thick and the support matrix is preferably composed of 0.375 to 0.75 in. diameter material. The exposed thin coating of sulfides reduces biooxidation rate limitations due to oxygen mass transfer. The large spaces between matrix particles reduce resistance to fluid percolation and aeration in the heap. The capital and operating costs for this biooxidation configuration are significantly less than for concentrate biooxidation in stirred tanks. After 30 to 90 days of biooxidation, sub- sequent gold recoveries exceed those seen in whole ore heap biooxidation and are comparable to recoveries obtained from stirred tank biooxidation processes. Results from laboratory and pilot testing indicate that this technology is a viable alternative for pretreating sulfide refractory gold ores.

Jan 1, 1997

By Theodore H. Eyde

In 1971, the Minerals Division of The Superior Oil Company acquired exploration rights to an unpatented claim group in the Superior (Pioneer), Arizona mining district, lying west of the Concentrator fault. This major post-mineral fault displaces the Magma vein-fault, which is mined in the Magma Mine at Superior, Arizona. The Magma vein-fault and the enclosing section of pre-mineral rocks consisting of Paleozoic and younger Precambrian sediments and diabase, is overlain by a thick section of post-mineral rocks, consisting of the Gila conglomerate, the Apache Leap dacite, and the Whitetail conglomerate. Geologic information on the thickness and attitudes of the rocks obtained from previous diamond drilling indicated that the section of post-mineral rocks might be from 3,000 to over 4,010 feet thick in the target area. (Figure 1) The Magma vein-fault is a steeply dipping vein which has produced nearly a billion dollars of copper, zinc, silver, and gold. It has been mined continuously for nearly 10,000 feet along the strike and nearly 5,000, feet vertically down the dip. It ranges from less than a foot to over 50 feet wide and contains sulfide mineralization con¬sisting of pyrite, chalcopyrite, bornite, and chalcocite.

Jan 1, 1973

By Nicholas C. Lias

Quartz crystals are the raw material from which are made the crystal units utilized in filters and oscillators so vital to the performance of all long distance communications systems. These devices act as the heart of equipment that permits a single telephone cable to carry hundreds of conversations simultaneously. Quartz crystals are of value in communications because of this piezoelectric nature, that is when an electric signal is applied to the quartz, there is a resulting mechanical motion and conversely, a mechanical stress results in an electrical output signal. A plate cut from a quartz crystal will oscillate at some specific frequency, which is determined by the physical dimension of the plate. During the early stages of telephony, all quartz plates were cut from natural quartz, which was imported mainly from Brazil. Since the source of this important raw material was based upon a foreign supply which is located at a great distance from the user and could be vulnerable in time of a national emergent, it became necessary to maintain a large inventory of this strategic material. Also due to the considerable cost of natural crystals of a size and quality suitable for Bell System use, an investigation was made by Bell Laboratories into the possibility of developing a substitute material. The effort was successful and led to a joint development program between Bell Laboratories and Western Electric. This program brought about the design of manufacturing facilities capable of producing large quantities of cultured quartz at Western's Merrimack Valley Works, No. Andover, Massachusetts.

Jan 1, 1973

By B. Morris

This presentation will describe the process by which the Quebrada Blanca (QB) copper project in northern Chile was financed. It will also show how a relatively junior mining company addressed the problems created by its inability to provide its share of the equity funding and the guarantees required by the project lenders. QB is located in the semi-arid Andean highlands of northern Chile, 170 kilometres southeast of the port of Iquique and 30 kilometres west of the border with Bolivia, at an altitude of about 4,300 metres (14,000 feet). Figure 1 depicts the project's location. The QB orebody is a secondarily enriched porphyry copper deposit containing reserves of 85 million metric tons grading 1.3 percent copper. Underlying the enriched zone is a significant primary ore zone containing several hundred million metric tons grading about 0.5 percent copper. In the late seventies and early eighties Falconbridge and its affiliates spent $20-30 million dollars exploring the deposit and conducting feasibility studies. For a variety of reasons they decided not to develop the property which was returned to its owners, Empresa Nacional de Mineria (ENAMI), which is a Chilean state mining corporation. In 1988 ENAMI announced its intention to privatize the property through a public bidding procedure.

Jan 1, 1993

By William Gleason

While a fleet of 100 t (110 st) haul trucks were busy removing overburden from the open pit mine in the distance, a host of dignitaries, including congressmen and California state representatives, gathered for Molycorp?s official groundbreaking ceremony at the Mountain Pass Mine on April 20. The mine, recognized as arguably one of the richest rare earths deposits in the world, is at the center of Molycorps? strategic ?Mine to Magnets? plan. It aims to secure America?s future supply of rare-earth-dependent technologies by developing a strong domestic rare earth industry. Molycorp identifies rare-earth-dependent technologies as those that cannot be produced without rare earth materials. The list of these technologies is long and growing. It encompasses everything from personal electronics and batteries for hybrid cars to permanent magnet generator wind turbines and national defense applications.

Jan 1, 2011

By Donald T. Mylar

It is axiomatic that in designing a bulk material handling system the primary consideration is the functioning of the machines. The structure is secondary -its reasons for being are to support, enclose and provide access to the machine, for servicing. This results in a wide variety of supporting structures. Other considerations are: plant layout, local soil conditions, climate, local laws and codes, and last, but by no means least, the Customer's wishes.

Jan 1, 1971

By J. D. Miller, C. L. Lin

"The use of 3D X-ray tomography analysis for plant-site characterization of coarse particles at a sampling rate of about 3 kg/min for particles ranging in size from 150 mm to 1 mm at a voxel resolution of about 150 µm is now possible. This is quite a significant advance in X-ray tomography technology and promises to be useful for plant-site coarse particle characterization—size, shape, composition, density, texture, grain exposure and mineral liberation—with a response time of minutes after receiving the sample. This paper discusses applications in the mineral industries, including the coal industry, aggregates industry, metal mining and the processing of industrial minerals.IntroductionPlant-site characterization of coarse particles at coal preparation plants, crushed stone/aggregate plants and mineral processing plants is needed to improve plant capacity, product quality and/or process efficiency. Not much online coarse particle characterization is being done at these plants. Only some limited information regarding particle size is obtained online from reflected light images using analyzers such as the OPSA, Split and WipFrag™ analyzers. Even the laboratory analysis of coarse particles has been difficult because of the large amount of sample required to ensure statistical significance of the results. During the past several decades, laboratory 3D characterization of particles from energy and mineral resources by X-ray tomography has been demonstrated and used to good advantage (Miller and Lin, 2004, 2009).Three-dimensional X-ray tomographic analysis has its origins in the medical services industry, where it is used to provide internal images of the human body. It has since been developed for nonmedical applications as well (Banholzer et al., 1987). Figure 1 shows a schematic diagram of the cone-beam geometry micro-CT system. In our case, X-rays from a microfocus X-ray generator are partially attenuated by the sample (a packed bed of particles) that is made to rotate in equal steps in a full circle about a single axis of the particle sample. At each rotational position, the surviving X-ray photons are detected by a planar two-dimensional array (image intensifier) large enough to contain the shadow of the specimen. These two-dimensional projection images are collected using conventional video technology. The video signal for each projection is then converted to a two-dimensional digital array by an image processing system. Finally, a threedimensional image is reconstructed from the collected set of projection images."

Jan 1, 2016

By Q. Xu

Adsorption of nonionic/anionic surfactant mixtures on kaolinite has been studied with sodium dodecylsulfate as the anionic surfactant and octaethyleneglycol mono-n-dodecylether as the nonionic surfactant. Synergistic interaction between these surfactant was found to cause adsorption of the nonionic surfactant with its hydrophilic chains protruding into the bulk, leading to substantial changes in wettability and dispersion characteristics of kaolinite. Similarly, hydrophobicity changes are observed also for silica particles upon adsorption of nonionic ethoxylated alcohols owing to possible changes in the orientation of the adsorbed surfactant molecules at the interface.

Jan 1, 1991

By P. R. Hervey

Quartz is the second most widely used electronic material, with approximately 3,000 tons of single crystals used each year. Virtually all of this material is synthetic; grown with a technique called hydrothermal growth. We will review the basics of hydrothermal growth, the feedstocks for these crystals, and the challenges to improving the growth process. We will also review the processing of these crystals, the markets and applications where they are used, and the global outlook for these markets.

Jan 1, 1999

By Anthony Harding

In a world of technology and electronic communication, it is easy to forget what engineers do best with a problem: sitting around a table, exchanging views and ideas with sketches and respecting everyone?s view. This was the approach adopted in the project to arrive at a solution for the cross passage opening sup-port for the Seattle University Link Extension. Schedule and space constraints usually impede concurrent cross passage excavation and tunnel boring machine (TBM) operation. And where the space is constrained, opening support solutions that maximize available cross sections are of great benefit. While there are a number of solutions that minimize space, some of these solutions can require expensive steelwork and extensive drilling and fixing. However, following a detailed round-the-table discussion of the options and constraints, it was identified that a shotcrete shell would not only limit obstruction of the space during installation, but also permit easy installation, particularly around services, and avoid costly steelwork and drilling and fixing.

By S. Lu

The particle-bubble attachment and the rupture of formed aggregates in flotation cell were investigated in terms of turbulent regime. It was found that the particle-bubble collision rate is closely correlated to the energy barrier between particles and bubbles, and no adhesion takes place for the hydrophilic particle-bubble system due to the introduced ?capture efficiency? f(a) being zero. The values of an especially defined Weber number, i.e. the ratios of turbulent stress to aggregate strength in the inertial subrange of turbulence were estimated, the results showed that the detachment of a particle from a bubble involved in an aggregate is mainly caused by the turbulent stress only in the impeller zone, no bubble splitting occurs both in the impeller zone and in the bulk zone.

Jan 1, 1993