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By H. Akbari

The ordinary Portland cement (OPC) is the key pozzalonic component of the concrete mix, widely used as the construction material world-wide. Billions of tons of OPC are used in the construction industry each year. However, calcinations of limestone and silica that produce OPC also produce almost an equal amount of CO2 during the cement manufacturing process. Thus, OPC production accounts for nearly 7% of all anthropogenic CO2 emission each year. The main objective of this study was to develop a geopolymer-based composite to be used as a substitute for OPC in concrete application to significantly lower the carbon foot print of the construction industry. A waste material produced during the coal combustion process was used as the main raw material for the geopolymer-based composite. It was mostly the non-metallic content of the F-type fly ash produced from the combustion of bituminous coal. The authors envisioned to extract some of the valuable metal oxides from fly ash prior to using the major non-metallic portion of the fly ash for geopolymer concrete application. The results obtained from this study exhibited that the compressive strength of the geopolymer concrete compares favorably with that of the conventional concrete prepared using the OPC.

Feb 27, 2013

By Matteo Montesi

Deep foundation elements are often used as discrete elements in externally supported earth retaining structures such as soldier piles and lagging walls, secant/tangent pile walls, anchored walls, etc. These structures can be designed using different approaches such as conventional limit equilibrium methods, finite element/difference analyses, and soil spring (p-y) analyses which are contained in various commercially available computer programs used by engineers worldwide. Although these programs usually undergo various degree of verification and validation, users must be aware of each program’s limitations and conditions in which each design approach should or should not be used. These programs may incur difficulties when non-continuous deep foundation elements are used as part of the retaining system and in cases of non-uniform geometry where closed-form solutions are not available. Design input parameters such as passive arching width, wall-to-soil friction, and p-multipliers (pm) are not always given enough attention which may result in potential design deficiencies. This paper presents the main features of various earth retaining structure design approaches and discusses their advantages/disadvantages. The paper addresses some of the limitations and difficulties that may be faced with when utilizing non-continuous discrete deep foundation elements and identifies key elements that are sources of potential deficiencies and errors. An example comparing the design outcomes using different design approaches is presented. INTRODUCTION Earth retaining structures are used to retain soil and create or maintain a difference in ground elevation between grades in front and behind the retaining structure. Deep foundation elements have been used for decades to support earth retaining structures. Earth retaining structures that are supported by deep foundation elements are typically referred to as externally stabilized system (O’Rourke and Jones, 1990). An externally stabilized system uses an external structural element, in contrast to internally stabilized systems which rely on reinforcements installed within and extending beyond the potential failure mass. The design of externally supported retaining structures can be accomplished using different approaches, which can be challenging under certain conditions. Each approach has been discussed extensively in available literature, and is well summarized in the and Federal Highway Administration (FHWA) guidelines. The objective of this paper is to present the most widely used design approaches and discuss their limitations and difficulties in one concise and brief document, giving the reader a good source for comprehensive understanding of the various design approaches, supported by a technical example. This paper is not intended to be a comprehensive review of all available design methods and formulations available in the literature.

Jan 1, 2018

By James A. Robertson

"In the Blind River area Proterozoic clastic and sedimentary rocks and minor volcanic rocks (The Huronian Supergroup) uncomformably overlie and trangress northwards over dominantly granitic Archean terrane (2500 + Ma) and are intruded by Nipissing Diabase (2ll5 Ma). Later deformation and metamorphic events are recognized. The developing depositional basin was controlled by the incipient Great Lakes Tectonic Zone marginal to the Algoman Craton.The Matinenda Formation (basal Huronian) comprises northwards-derived fluvial arkose, quartzite, and pyritic, uraniferous oligomictic conglomerate which contained in 1981 some two-thirds of Canada's uranium resources. Production to December 1981 from Elliot Lake totalled 98.3 thousand tonnes U for an average recovered grade of 0.1% U with an additional 671 tonnes U recovered by leaching at Agnew Lake. The remaining resources are at lower grades. Some thorium and yttrium have been produced. Minor amounts of gold reflect the paucity in the source area. Gold is better-developed in the Huronian north of Sudbury reflecting the local source area.The conglomerate beds lie in southeasterly-striking zones controlled by basement topography down sedimentation from uraniferous Archean granite. Uraninite textures, the distribution of monazite, and local enrichment by reworking indicate a syngenetic, probably placer, origin of the mineralization. ""Brannerite"" has formed by solution of uranium from the margins of the uraninite grains and redeposition on the original titaniferous minerals. Penecontemporaneous volcanics may have been a source for sulphur in some of the pyrite and of trace amounts of Co, Ni and Au. Some pyrite may be detrital, some may be authigenic and some introduced.Drab coloured rocks, uranium and sulphide mineralization, the presence of hydrocarbon (thucholite) and a post-Archean regolith formed under reducing conditions have been cited as evidence of an early Precambrian reducing environment extended to the atmosphere. Sedimentary features indicating fast-flowing water and possibly a cold climate imply that the uraninite would be exposed to whatever oxygen was present in the atmosphere under conditions which would inhibit complete solution. In the upper Huronian, red beds and in the Lorrain Formation a monazite - iron oxide assemblage and copper mineralization indicate more oxidizing conditions. . Similar uranium deposits occur at Agnew Lake and in the basal Huronian north of Sudbury there are minor uranium and gold values.Provenance, lack of complete oxidation, transportation and depositional processes, redistribution during diagenesis and possibly low grade metamorphism, and the lack of post-depositional destructive processes are the dominant factors in the formation and preservation of the ores. The modified placer theory of genesis is well entrenched and an exploration model for such deposits throughout the world is well-documented.Research continues on mineralogy and textures of the ores, detailed sedimentology of the ores and their host rocks, with particular emphasis on: provenance area, the influence of early Precambrian mineralization patterns on the mineralization present in the Huronian both in space and in time, fluvial sedimentation and diagenesis. Expansion and reopening of the mines of the Elliot Lake camp should facilitate further studies."

Jan 1, 1986

By Christoph Müller

Information exchange for mine process optimization is essential. Today, modern mining equipment uses the IREDES standard to exchange production plans and reports for easy management and storage. To gain further benefits from process optimization, a mine wide access to real-time information is needed as e.g.: The current status of a machine, operational details etc. Presently, real-time data exchange systems are developed by machine producers. Each machine producer uses its own way of gathering, managing, and storing production data. These proprietary mining processes increase the complexity of cross platform data exchange and management for mines which involves machines produced by different vendors. Casting and unifying the data requires much effort. For this purpose, ?IREDES On-line? currently is being introduced. The standard defines an open, web based method for the exchange of volatile real time machine information. Two different principles are used: Web Services for cross platform information exchange within the IT world and the optional OPC UA for use with automation and process control systems. With such a standard information from machines of different vendors may be managed by using one common platform without spending the effort for dedicated interface development. Additionally, information management and storage will become straight forward since all the data are of the same format. The IREDES On-line standard utilizes the latest IT technologies as well as the knowledge and experiences gained from the previous IREDES standard. The paper explains the benefits, the use, as well as the technical design of the standard and gives application examples from the practice.

Oct 1, 2009

By J R. Lang, J K. Mortensen

The Canadian Cordillera contains numerous classic porphyry deposits and several unusual subtypes, including the alkaline suite of porphyry Cu-Au deposits and the Tombstone magmatic suite and associated Au¦W deposits. The alkaline suite formed in collisional settings in island arcs whereas the Tombstone suite was emplaced in an active fold and thrust belt in a continental arc. In addition to different regional settings, these suites differ in the type of underlying basement, metallogeny, and the styles of mineralization. Both magmatic suites were emplaced over short intervals, probably in response to specific tectonic events. In the case of the alkaline suite, the tectonic event promoted magmatic processes suitable for the formation of porphyry Cu-Au deposits. The tectonic environment is less well constrained for the Tombstone suite, but the result was the formation of distinctive porphyry and intrusion-related Au¦W deposits.

Jan 1, 1995

By William N. Patterson

Drive systems for mining machines are usually sized to accommodate anticipated peak loads. Usually, the average power requirements are considerably less. Energy storage and power averaging are attractive concepts for mining machinery and could have far-reaching implications. The purpose of this program was to: ? Identify truly feasible concepts, ? Identify advantages/disadvantages, limitations, and constraints, ? Evaluate feasibility based on today?s technology, ? Identify anticipated safety problems, and ? Provide the designer with a comprehensive literature base. Concepts evaluated include flywheels, high energy batteries, gas charged accumulators, inductive storage, capacitive storage, springs and counterweights, thermal, closed cycles, internal combustion engines, trolley systems, and hybrid systems. A comprehensive reference index is provided. Included is an appendix containing abstracts of the pertinent literature.

Jan 1, 1980

By Masayuki Ishikawa

In a radio frequency and optoelectoronic device packaging, Gold-Tin (Au-20 wt% Sn eutectic) solder is used widely due to the excellent electrical and thermal conductivity, high strength, and negligible creep characteristic under repetitive thermal cycling. With the recent lead-free movement, Gold-Tin solder is recognized as an alternative material for high temperature Lead-Tin solder. Generally, Gold-Tin solder is supplied in the forms such as ribbons, pellets, and ring frames. However, these forms must be set-up accurately on the joint area to press chips in bonding, therefore, it is difficult for these forms to satisfy the recent requirements for the down sizing in the connection areas. On the other hand, Au-20 wt% Sn solder paste can be applied flexibly to various supplying methods, such as printing, dispensing system and pin transcript. These methods also make it possible to reduce the production cost. However, in the case of using the solder paste, the void issue is one of the most undesirable problems. The void causes the degradation of the characteristics such as the bond strength, electrical characteristic and thermal conductivity. We have been intensifying the development of the void free paste, and have achieved void reduction by optimizing the powder size, the flux composition and the reflow condition.

Oct 1, 2003

By D. Pohl

The past decade has seen rapid expansion in the West African mineral exploration environment. This expansion has been largely driven by changes in ?Political climate ?Fiscal and legal regimes ?Exploration approaches ?West African geology. Major regional mapping and geochemical surveys by the UNDP, and the BRGM in the late 1970s and early 1980s laid the foundation for the rapid development of mineral exploration and resources during the past decade. An additional driving impetus was the discovery by native artisanal miners of many significant new gold occurrences at Libiri, Essakan, Bouda and Tirahori, during the great droughts of the late seventies and early eighties.

Jan 1, 1998

Plant-Based Trials of Monitoring of Coal Flotation Systems Using Electrical Impedance Spectrum Technique

Sep 13, 2010

By J. -F. Lagueux

Goldex Mine is an underground mine located near the town of Val-d?Or. Multiple innovations were required to work the mine. Due to its low grade, it was important to develop a bulk mining method to economically extract the ore. The method used is a combination between shrinkage stope and long hole stope methods. This modified method is more than adequate; however, all of the ore body must be liberated in a very short period of time. Therefore, to bring down 23 Mt of ore, large blasts up to 1.8 Mt are required. The situation is also complicated by the fact that the mine is located in a residential area. No less that 40 homes are built within a 1 km radius of the mine site. In addition to managing mass blasts, means must also be found to mitigate the vibrations produced by the blast to diminish the disturbance to the neighbourhood. Therefore, the mine used numerous tools to properly plan the blasts and reduce the impacts. A program to control vibrations was one of the first tools put in place. The program?s aim was to draw up an action plan to ensure a follow-up of the homes by inspecting them. The second tool was to develop a methodology to plot a reliable attenuation curve and to adequately determine the maximum charge weight for each blast. Finally, effective communication tools were developed to inform the neighbourhood. There was a huge amount of work to be done in relation to the bench. Reliable and fast loading techniques had to be found to load large blasts in a very short period of time. Adequate logistics had to be developed to send underground more than 20,000 kg of emulsion per day while performing the daily underground operations. Technology had to be developed to adapt the i-kon electronic blasting system to large blasts. Since the control of the charges was the major factor to reduce surface vibrations, it was important to employ loading techniques that would permit decking of the long holes to reduce the charge weight per delays without adversely affecting the loading. All of this work requires an enormous amount of energy but also close collaboration between the different stakeholders (various departments, suppliers and consultants).

Jan 1, 2011

By Michael J. Bertoldi

The purpose of this Bureau of Mines report is to describe the methods and establish the basic economics for dragline, shovel-truck, and scraper mining systems. An overall view of the techniques of preliminary design and the cost involved is presented. Considerations of equipment selection, emphasizing short-range evaluation of required equipment, and a long-range evaluation are considered at a constant production rate over the life of a hypothetical mine. Separate cost analyses for each system were based on 1977 equipment prices, prevailing wage rates, and associated mining costs. Specific engineering and cost breakdown for such items as access roads, transmission line installation, rail spurs, etc., are beyond the scope of this report.

Jan 1, 1977

By S. J. Gasior

A method for destroying the caking properties of bituminous coal was developed by the Bureau of Mines. Coal is treated in a fixed bed by heating through its plastic range under controlled temperatures in mildly oxidative atmospheres composed of inert gas and/or steam containing about 1 volume-percent oxygen. High-volatile A (hvab) and high-volatile B (hvbb) and low-volatile bituminous (lvb) coals in the size range 1/8 to 1-1/2 inches were successfully treated at 0 (atmospheric pressure) to 300 psig in static beds 6 to 18 inches deep. Conditions of treatment depended on the coal and ranged from 80 to 200 minutes at 350° to 510° C. Char produced in this manner from hvab coal was gasified with steam at 800° C and 100 psig in a fixed bed in one series of tests and in other tests was exposed to hydrogen in a dilute co current free-falling-bed system at 750° C and 3,000 psig without agglomerating.

Jan 1, 1965

The Century zinc-lead-silver deposit has a geological resource of 118 million tonnes averaging 10.2% zinc, 1.5% lead and 36 g/t silver. It lies approximately 250 krn NNW of Mt Isa in NW Queensland, Australia, and is hosted by middle Proterozoic age siltstones and shales of the Lawn Hill Formation. Within the orebody, most mineralisation occurs selectively within black shale units as fine grained sphalerite and galena lamellae with minor pyrite and siderite. The black shale units are separated by weakly mineralised sideritic siltstone horizons. The deposit is unmetamorphosed and only weakly deformed, displaying excellent lateral stratigraphic and grade continuity. The deposit is mostly overlain by younger Proterozoic sediments and later Cambrian age limestone cover and only a small proportion of the mineralisation crops out. Mineralisation has a subtle surface expression without a classic gossan profile, probably due to the low iron sulphide content of the ore. These factors contributed materially to the length of time between the first recognition of lead-zinc-silver mineralisation in the area by prospectors in the 1880s, to the discovery of the orebody by CRA Exploration Pty Ltd (CRAE) in April 1990.   Small scale prospecting and mining continued in the area from the date of the first mining lease in 1887. Post 1950, the deposit area was also included within nine separate regional exploration titles prior to CRAE's title acquisition in 1987. CRAE's original exploration strategy was partly pragmatically and partly conceptually inspired, but the eventual discovery only partly conformed to the original conceptual model. The deposit was found higher in the stratigraphy than the original target position, with unexpectedly low total sulphide content relative to other known deposits.   The discovery soil anomaly was located by the CRAE's first regional orientation traverse line in the area, but was not drill tested for three years. The discovery sequence at Century has strong elements of persistence, technical competence and some luck. It demonstrates that even in well explored terrains (by conventional standards) the exploration story can never be said to be over. The foreshadowed development of an economic resource at Century will hopefully inspire continued commitment to 'brownfields' exploration by mining companies, and demonstrate to external regulators the importance of genuine multiple land use strategies and the need for continued access to land for exploration and mining purposes.

Jan 1, 1995

By William F. Hahn

The Bureau Of Mines recognized the desireability of illuminating working places in trona mines. This report describes two illumination system designs, their demonstration and evaluation on a Jeffrey 120HR continuous mining machine in an active working trona mine in Wyoming.

Jan 1, 1980

By Roy T. Sorensen

As part of its mission to maintain an adequate supply of minerals to meet national needs and maximize mineral production from domestic sources, the Bureau of Mines is investigating the recovery of alumina by hydrochloric acid leaching of kaolinitic clay. Most iron impurities are leached from the clay along with the alumina and must be removed before or during crystallization to aluminum chloride hexahydrate. The thermal decomposition step then provides an alumina product of acceptable iron analysis. Miniplant studies of a Bureau-developed solvent extraction technique, using a tertiary amine in kerosene diluent, have demonstrated that the iron content in aluminum chloride leach liquors can be reduced to levels of less than 0.007 wt-pct (7 ppm), expressed as Fe203. Entrained and dissolved organic matter in the purified pregnant leach liquor from the solvent extraction circuit can be reduced to less than 2 ppm by using a fabric-packed coalescer and subsequent activated carbon treatment. Investigators discovered that a steady buildup of zinc accumulated in the solvent phase within the extraction circuit, proportional to the amount of leach liquor treated. The solvent phase zinc analysis increased by 0.01 wt-pct ZnO for each 1,000 gal of pregnant leach liquor purified.

Jan 1, 1981

By J. B. Gwiazda

Introduction Thick seams constitute a considerable portion of Polish coal reserves. In producing mines and those under construction, the reserves where the height is more than 4.5 m (15 ft) total about 24% of all the hard coal reserves. The reserves that are under urban and industrial areas can be extracted using stowing methods for surface protection. About 50% of thick seam reserves can be extracted by caving methods. Thick seam mining methods Thick seams are usually extracted by multilift methods. There are some methods of thick seam mining that generally can be divided into caving and stowing methods. The stowing method is more expensive, but must be used when mining to protect surface features. The more known methods of thick seam mining include • extraction of thick seam in ascending order with stowing ; • thick seam mining in descending order with consolidated stowing; • thick seam mining with gob consolidation; • thick seam mining in descending order with roof caving ; • sublevel caving thick seam mining system; and • thick seam mining system using an artificial roof. Thick seam mining with introduction of an artificial roof The most advantageous method of thick seam mining is the method using an artificial roof. The artificial roof usually consists of wire mesh. Such wire mesh must be durable and must prevent small rock fragments from passing through. The mesh is usually made of steel properly protected against corrosion. The artificial roof is placed on the coal floor of the top slice (Fig. 1). Caving rock falls on the artificial roof and is thus separated from the coal. The next slice is extracted under the artificial roof. The producing face of the next slice must progress within 10 m (33 ft) behind the front of the first slice. As the second producing face progresses, the wire mesh moves down on the coal floor and may be used as an artificial roof for the next slice. Thus, one artificial roof allows the extraction of several consecutive slices. Application of the artificial roof allows for clean extraction and reduces coal losses. It also eliminates the hazard of spontaneous combustion. Introduction of the artificial roof has been limited due to a lack of artificial roof laying equipment. Manual laying of wire mesh is a labor-intensive operation, and it delays face progress, resulting in poor productivity. To eliminate these problems, artificial roof laying equipment was designed at the Polish Central Mining Institute. The support and the method of laying operation is covered by a patent. Artificial roof laying powered support To extract thick seams using an artificial roof, four-leg shield supports with lemniscate linkage were developed (Fig. 2). This shield is used in the first top

Jan 3, 1987

By Stefan Mutz

In Germany the automobile recycling is regulated by law. Current legislation requires that by the year 2015, eighty five w.-t. % of the components from used cars ill be materially recycled. Whilst for 10 w.-t. % of the materials a thermal utilization is certified, there are still some concrete questions that remain unanswered regarding the usability of single fractions. The recent innovative approaches to the concepts of used cars dismantling do not alter the fact that the majority of the materials of used cars still have to pass over the shredder and the connected processing aggregates. The status of the so called SLF (Shredder light fraction) which is about 25 w.-t. % w.-t. in used cars, has not been satisfactorily clarified. Furthermore questions still remain regarding the separation of the NMSF (nonmagnetic metal shredder fraction) which has to be separated in the single metallic fractions like stainless tell, copper, brass, zinc, etc. Attempts of optimization can be found. This paper analyses some of the difficulties being encountered by the automobile recycling industry in Germany, before reviewing some of the innovative approaches that the industry has introduced. Finally the paper goes on to describe the potential of automatic picking. Examples of a series of tests, utilizing this technology, in which a variety of products from a range of shredders were isolated are described in detail. This new technology provides a range of applications to the automobile recycling industry.

Jan 1, 2002

By A. Vien

Over the past several years, Svedala has developed a continuous charge monitor (CCM) for tumbling mills. It consists of a strain gauge embedded into a rubber lifter and associated electronics. This paper describes the results of a research program to evaluate the technical and economical merits of such a device on a SAG mill. The evaluation includes validation through discrete element modelling and comparison to measured static volumetric load. Inclusion of the measurement into a control strategy and its potential for condition monitoring is discussed.

Jan 1, 2001

By J. Nielen van der Merwe

This investigation was done to develop a method to predict the lie of coal pillars. It has long since been known that coal pillars deteriorate over time, but there was no method to quantify the deterioration. It was found that the rate of pillar deterioration was essentially a function of two parameters, namely mining height and time. The higher the mining height, the more rapidly the pillars deteriorated. The rate of deterioration is not constant, but decreases exponentially with time. The pillar life should be viewed in conjunction with the safety factor. While the relationship between safety factor and pillar life is ambiguous, the trend is nonetheless for higher safety factor pillars to have longer lives. The safety factor can be used to quantify a failure probability. The pillar life prediction indicates when the pillars which are predicted to fail, can be expected to do so.

Jan 1, 1998

By George G. Goble

The use of augercast piles has been limited by the engineer's concern for the structural quality of the installed pile. The nature of the pile is such that its final structural continuity is very dependent on the skill of the personnel that do the installation. Thus, NDT methods have been used to verify integrity and when problems are indicated the available solutions are usually quite costly. If information were available during the pile installation so that immediate steps could be taken to correct perceived problems, the concerns of the engineer could be addressed and the system would gain increased reliability. Pile Dynamics, Inc. has developed a quality control system, the Pile Installation Recorder for Augered Cast-in-Place piles (PIR CFA). This system consists of the following devices as shown in Figure 1. 1) The Control Unit powers the sensors, conditions the signals from the sensors, records all measurements, takes input information from the operator, displays the results, and stores the recorded data on a flash card for later permanent storage and processing. During the use of the system all of the results obtained during a test are seen during recording and can be reviewed on the screen again after completion of the installation. The ability to review the measured information makes it unnecessary to print a copy in the field. Since printers often give difficulty in the construction site environment the ability to review the results quickly after completion of the installation is an important capability.

Jan 1, 1997