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By D. Rutledge

Discrete (digital) signal processing techniques are proving to be very valuable tools for miners using the block cave method. Waveform analysis of different measured signals associated with active mining provides valuable information on production dynamics and safe operation of the mine. For example, correlation of the 3D surface displacement velocity waveform and the production output waveform reveals a remarkably predictable time-varying physical process. Studying the geometrical and temporal relationship between these two signals opens a broad window through which new management techniques become apparent. In this paper we discuss the signal processing techniques used to study these relationships, as well as the related implications for mining. This research was carried out in association with the Chevron Mining underground molybdenum mine in Questa, New Mexico. Some of these new techniques will be integrated into the decision management process at the mine and will provide insight on ore production, draw control, and safe reclamation. The science of signal processing involves the analysis and interpretation of physical processes that vary with time. Two general categories of signals1 are recognized. A continuous signal is a waveform of varying amplitude that is continuous in time (such as a sine wave). A discrete signal is a sequence of quantized values. The independent time variable and amplitude are sampled periodically such that we only know the value and shape of the waveform at the sampling frequency. Displacements measured by a Global Positioning System (GPS) receiver are an example of this. Discrete signals may be studied in the time, frequency, autocorrelation, or wavelet domains. In this paper the amount of ore extracted from the mine and the measured surface displacements are analyzed in the time domain.

Jan 1, 2008

Remote sensing, in general, is the recording of light and heat from a planet's surface within a certain range of the electromagnetic spectrum. For the Earth, systems capable of this recording are the MultiSpectral Scanner (MSS) and SLAR. The former is the recording system used in satellite and will be discussed in the next section. SLAR stands for Side Looking Airborne Radar. This device sends invisible radar waves which illuminate the Earth's surface. The reflected waves are subsequently recorded as images. The system can operate through darkness and dense cloud cover, and is particularly suited for the study of geological structures at both large and small scale (Wayland 1976). Remote sensing techniques are now widely being made use of in mineral exploration, especially for those last remote 'sanctuaries' where geological data are meagre or non-existent. For places like Borneo, West Irian, the Amazon Basin etc. remote sensing, in the form of both satellite imagery and SLAR, is of considerable help, in fact more often than not the only help, to delineate geological provinces, geotectonic domains and meaningful lineaments. In the case of New Zealand, well made geological maps at scale 1:250 000 by the Geological Survey are available to the public and these provide useful preliminary grounds for the selection of target areas. However, even in this case LANDSAT imagery can be of aid as will be shown later.

Jan 1, 1977

By M. A. Barclay, D. Samson, A. M. Esteves

Several companies have adopted policies and standards aimed explicitly at increasing ‘local procurement’, recognising that local economic participation has benefits for companies and communities alike. From a corporate perspective, local economic participation is seen as one means of maintaining a social license to operate, as well as ensuring reliability of supply by having a supplier located nearby. From a community perspective, the participation of local businesses in the resource project is a means by which the benefits of resource development can flow into their communities. This paper is based on the research undertaken to produce a good practice guide for the mining, oil and gas sector. Our research revealed that the extent to which the local community will actually benefit from local procurement initiatives is dependent on the capacity of the community to supply goods and services to the project and, even more importantly, on its ability to adapt to the inevitable changes that accompany large-scale resource development. We provide guidance on adapting impact assessment tools to guide planning of procurement interventions.

Jan 1, 2011

By F. Hassan, M. A. Arafa

At El-Gedida iron ore deposits there is a block of about 30million tons neglected due to its higher sulfur content due to the presence of barite gangue minerals. From this bluk by magnetic separation dual concentrates of high grade iron concentrate (~65%Fe and total Sulfur of 0.26%) and the second concentrate is barite of (60.87% BaO and total impurities of less than 3%).

Jan 1, 1999

This report describes the redesign, development and field demonstration of a remote shotcrete lining system, capable of operating in shafts and mines from 8 to 16 feet in diameter at depths up to 1000 feet. The original contractural scope of work outlining problems and remedial measures associated with a previous unit proved inadequate. Significant additional effort was necessary in order to fulfill the project objectives of producing a functionally reliable remote shotcrete lining system. Included with the engineering and technical description of the system, is a comprehensive technology package. Included with this material is ancillary equipment, materials selection procedures, mix-design data, quality control and assurance program, selection and training of personnel and the organizational aspects required to operate the entire system. The report concludes with details of a successfully completed borehole lining operation at the Nevada Test Site. An irregular 104 inch diameter borehole was lined at a rate of 4.8 feet per hour and 20 feet per hour respectively for 8-9 inch and a 2 to 3 inch shotcrete thickness.

Jan 1, 1983

By R. Strandahl

As one of the largest private utilities globally, E.ON currently operates hard coal fired power stations in with a total installed capacity of some 20.000 MW: These thermal power plants consume domestic coals but are increasingly dependent on imported seaborne traded coal (in 2009 approx. 17 million t). Knowing that the company’s reputation and credibility depends in part on how E.ON lives up to the responsibilities along the entire energy value chain, E.ON takes a collaborative approach with the various suppliers. Hence, E.ON’s responsible policy also applies to the procurement of coal; the utility launched in 2009 a comprehensive Corporate Responsibility program with special focus on supply-chain audits. One of the first coal audits focussed on the Cerrejón coal mine in North Eastern Colombia. The authors will share the key learning’s and experience from the Colombian audit jointly conducted with an independent auditor and E.ON experts from the Corporate CR and E.ON Energy Trading.

Jan 1, 2011

By Y. P. Chugh

This is the final report of a study done by IIT Research Institute for the Bureau of Mines to identify the problem areas and technological inadequacies in noncoal (metal, nonmetal, stone, and sand and gravel) mining and processing systems that are the primary causes of death, injury and occupational disease, and to make recommendations to improve safety and health in these operations. The findings and recommendations presented in the report are based on: (1) analyses of MESA injury and employment data for the period 1961-70, MESA fatality reports for underground noncoal mines (1968-72) and lost time accident data for 1970-72 obtained from mining and processing operation: (2) visits to a variety of noncoa1 mines and mills throughout the country to observe the operations and to study the safety organization and practices used in the industry and (3) interviews with industry and government representatives knowledgeable in the field of noncoa1 mining and processing safety and health. The report provides a comprehensive overview of safety and health problems.

Jan 1, 1974

By S. E. Olsen, M. Tangstad

The main source of Mn in raw materials for SiMn production is Mn-ore and Mn-rich slag from the high carbon FeMn production. The amount of slag per tonne of SiMn metal is mainly determined by the ore/slag ratio. Increasing share of FeMn slag at expense of Mn-ore will lead to larger slag/metal ratio in the SiMn process. High volume of slag leads to an increased consumption of energy and probably to higher losses of metal inclusions in the final slag. Excavation of a SiMn furnace has shown that only modest pre-reduction of Mn-ore with CO gas seems to be obtained. Nearly all reduction of MnO was finished at the top of the cokebed. Dissolution and reduction of quartz obviously takes place in the cokebed zone after the main reduction of manganese oxide is finished. Probably the ?pick up? of Si in the metal is quite fast and takes place as the metal trickles down through the cokebed towards the metal bath. The distribution of Si between SiMn alloys and multicomponent MnO-SiO2-CaO-Al2O3-MgO slags is mainly determined by the process temperature, the silica content of the slag and its R-ratio = (CaO+MgO)/Al2O3. As an example, the equilibrium content of Si in the alloy will increase by about 6 % if the R-ratio is reduced from 2 to 1, provided constant temperature and silica content. The effect of temperature is also considerable. The equilibrium content of silicon will increase by approximately 6 % per 50°C in the temperature range 1550°C to 1700°C. The equilibrium content of MnO in SiMn slags depends first of all on the temperature and secondly on the silica content of the slag. At 1600°C the MnO content decreases from about 9 % at silica saturation to a minimum of about 3-4% when the silica content is reduced to about 40-45%.

Jan 1, 2004

By Milne J. Schmid

A program has been conducted to determine the feasibility of providing a borehole liner for Kelly Bar drilled boreholes in Southern Florida. The concept was to drill the borehole with the Kelly Bar and with it still in the borehole insert a tube which would remain in the unstable ground after withdrawl of the bar. The tube then will provide an unobstructed borehole for the charging of explosives upon completion of the drilling the shot pattern.

Jan 1, 1977

By D Craw, K A. Hunter

Deposits of the metalloids arsenic and antimony occur in quartz veins of mesothermal hydrothermalsystems in the South Island as arsenopyrite (AsFeS) and stibnite (Sb2S3). Arsenopyrite and stibnite occur in natural exposures in gold-mining areas, and additional arsenopyrite and stibnite have been exposed to the atmosphere by mining activity. At present the drinking water limits for dissolved As and Sb are 10 ppb and 3 ppb respectively. Sampling and analysis techniques are critical to determination of metalloid concentrations at these low levels. Endeavour Inlet in the Marlborough Sounds is an historic mining area (late 19th Century) with elevated As and Sb in waters emanating from mineralised rocks. Waters running out of abandoned adits have concentrations of As and/or Sb up to ppm levels. Natural waters have high Sb and low As, and the As levels increase markedly where anthropogenic activity has exposed rock. Changes in Sb/As ratio could potentially be used to quantify the anthropogenic component of metalloid mobility on mine sites on the 100-year time scale.

Jan 1, 2002

Preface The intention of this paper is to provide the reader with knowledge gained here at Memorial University regarding the practical use of the Bruker SDD x-ray detector for applications in image analysis. Included below are descriptions of the detector’s characteristics and observations regarding precautionary use. What is described below is relevant to the XFlash® model 3001 detector only, whereas the model 4010 is the new and currently available detector. The manufacturer has provided up-to-date information and a figure that presents very different behaviour relative to the characteristics described in this paper. That information and figure is also included here as an addendum (see figure 9). Introduction It has been more than two decades since an image analyzer has been proposed based on the unique imaging characteristics and spatial resolution provided by the scanning electron microscope (SEM) together with energy discriminating x-ray (EDX) acquisition (Reid et al, 1984). From the inception of technique, technology of the day has played the major role for making applications increasingly more practical. Computers, digital imaging, and softwares together with computer automation of modern digital SEMs have all played their part in advancing the technique to where it is today.

Jan 1, 2007

By Shi Hongchao, Zou Zou Xinkuan, Zhang Jichun

As drilling and blasting is carried out in an urban tunnel, which is adjacent to an existing building or structure, the balance between blasting-induced vibration reduction and drivage efficiency is a most important issue that must be resolved properly. Therefore, a new cut blast method named Stepped V-cut millisecond blasting (SV-cut) was developed by optimizing the most common used Vertical V-cut blasting method (V-cut). The most significant features of SV-cut lie in the utilization of sublevel interval charging structure and millisecond delay blasting technology in cut hole and the cut-cavity formed from outside to inside sequentially. SV-cut provides advantages of high borehole using ratio, low vibration level, and satisfied advance per attack. Based on the principal of millisecond blasting, the rock fragmentation process and the vibration reduction mechanism of SV-cut are analyzed. Determining methods of blasting parameters, which do have significant effect on vibration intensity and cut-cavity formed quality, are proposed according to the forming requirement of both outer and inner cut-cavity and vibration reduction. In order to compare the performance between SV-cut and V-cut, field blasting experiments were performed in the blasting engineering of Yamalike twin-arc tunnel, which closely passes over aged parallel tunnels. Blasting results show that SV-cut blasting is proven as an effective tunnel blasting method for both increasing blasting effects and decreasing blasting vibration. Comparing SV-cut with V-cut, the SV-cut can increase blasting drivage about 8.5% and reduce the vibration intensity induced by cut hole blasting 30% at least.

Jan 1, 2015

By J. M. Singer

In this Bureau of Mines study coal and rock dust beds were entrained by airblasts generated by gas explosions at the closed end of a 0.61-m-diameter explosion tunnel, 49.7 m long. The system was designed to simulate entrainment of mine dust deposits by accidental gas explosion at the coal face of nonintersecting mine passageways. Full-scale mine explosion trials confirmed many of the results of the explosion tunnel experiments and indicated several new features of dust entrainment. Dispersal of 20.3-cm-long stepped dust beds located 35 m from the closed end always began during the early portion of the ascending gradient of the first transient airflow (and pressure) wave, and was usually completed before the end of the first quarter-wave period. Bulk quantities of dust were entrained simultaneously by longitudinal regression from the leading edge of the dust bed and by surface lifting of the top layer. Instantaneous threshold air velocities for bulk quantities of coal and rock dust beds in separate, mixed, and layered configurations were in the same range (5 to 30 m/sec) as previously found under steady-state velocity conditions. Selective lifting of coal dust layers from rock dust occurred when the threshold dispersal velocity of coal dust but not of the underlying rock dust was exceeded.

Jan 1, 1976

By Lex L. Udy

Properties of an explosive which itiuence its performance on rock breakage are analyzed in relation to the rock: hardness and a discussion on the interaction of an explosive with the rock during the blasting process is given. Theoretical concepts regarding ideal and non-ideal detonation are reviewed to explain how the physical and chemical factors of an explosive influence the rate of energy release and its consequence on blasting performance. While a lower velocity of detonation indicates a slowed chemical reaction it does not necessarily mean a loss in energy from the explosive. High density ammonium nitrate (HDAN) can be used effectively in the formulation of modern industrial explosives to slow the energy release rate with its attendant decrease in detonation velocity. Examples of blasting performance using custom formulated explosives with HDAN are presented.

Jan 1, 1995

By James C. Patterson

Sintered fly ash was shown to have promise as a modifier for poorly drained soils. Turf grown in mixtures of sintered fly ash and soil benefited from increased water-infiltration rates, greater total pore space, and higher moisture availability, The result was an improved turf stand with increased grass yield and root density.

Jan 1, 1970

By William C. Cooley

A technical and economic study was made of the feasibility of establishing an underground hydraulic coal mine in the Wilkeson-Carbonado coal field approximately 25 miles southeast of Tacoma, Washington. The deposit contains reserves of more than 200 million tons of generally high quality metallurgical coal. It is located in nine seams of minable thickness in a complex, folded and tectonically disturbed set of anticlines and synclines. Typical dip angles are up to 60°, with minable seam thicknesses of 6 to 17 feet. A mine plan was made for a 2 million TPY mine (clean) using two shafts to access the deposit to a depth of 2500 ft. The mining method uses monitor jets to break coal by sublevel retreat mining, fluming to a sump and pumping the minus 0.25 inch coal to the surface and to a preparation plant. The plus 0.25 inch coal is hoisted by skip. Cleaned met coal would be shipped by rail for export. A middlings product would be sold as thermal coal. Assuming a coal price of $48 per short ton (FOB the mine) for the met coal and $35 for the middlings, the return on investment is estimated at 20% after taxes. The many uncertainties about the geological conditions and the specific mine design parameters make the economic analysis and conclusions somewhat tentative. A second mine could also be developed in the eastern section of the reserves to produce 1 million TPY of clean coal and is expected to have similar economics. Recommendations are made for a Test Mine and a Pilot Mine leading to a production mine.

Jan 1, 1983

By R. Q. Honaker

Dense medium processes are used to clean over 50% of the coal that is fed into preparation plant facilities worldwide. The dense medium is formed using ultrafine magnetite which is recovered after the cleaning step using drain-and-rinse screens and magnetic separators. Despite the high efficiency of the recovery system, magnetite losses of around 0.5 to 1.0 kg/ton are common. Considering the recent escalation of magnetite to around $300/ton, an alternative source of magnetic material from coal combustion bottom ash has been investigated. A relatively low cost recovery system has been developed. Dense-medium tests using the bottom ash magnetics revealed a high level of efficiency as indicated by probable error values around 0.03 over the range of medium densities investigated. The results from both the recovery and coal cleaning efforts will be discussed in detail.

Jan 1, 2009

By Osvaldo A. Bascur, J. Pat Kennedy

"The profitability of mining and metallurgical operations continues to lag behind that of other industries despite the technical advances that have occurred in recent years. A primary reason for poor performing in this economic sector is the lack of integration of mining and metallurgical information. The mine cut-off grade can be optimized if mining and metallurgical engineers have the data to optimize milling for the type of ore in hand.Integration of mine transactions, stockpile inventories, process flows and assays is the key to determining the economics for each blast strategy in a mining site. Real-time information from manufacturing assets greatly affects the profitability and flexibility of a company, but gross errors from faulty sensors, inaccurate instrument calibration, or incorrect process models may corrupt actionable information. New software tools can model the process, sift through available data to identify and eliminate gross errors, and use statistical data reconciliation to create materially balanced and consistent readings. The reconciled data is unified for use by both monitoring and decision making processes.Creating a real-time information environment where upgrade and change are allowed is becoming an accepted methodology to accelerate and simplify the integration of applications such as production monitoring, equipment performance management and yield and inventory management."

Jan 1, 2003

By Toshiharu Teranishi

When we apply the Au nanoparticle superlattices to the future nanooptical and nanoelectronic devices, the control of not only the particle size but also the interparticle spacing and symmetry of superlattice are the essential problems to be overcome. First, we developed a novel synthetic procedure to precisely control the particle size of alkanethiol-protected Au nanoparticles in the range from 1.5 to 9.7 nm by the heat-treatment of the small Au nanoparticles in the solid state. Absorption and nonlinear optical properties of alkanethiol-protected Au nanoparticle superlattices were then elucidated. On the other hand, the hexagonal close-packed (hcp) 2D superlattices of small Au nanoparticles with the interparticle spacings from 1.9 to 3.6 nm were successfully prepared by using newly-synthesized ligand for single electron tunneling devices. Finally, various symmetric superlattices, such as chain (2-fold), quasi-honeycomb (3-fold), square (4-fold), etc., of Au nanoparticles could be produced by making use of interligand interactions or some templates.

Oct 1, 2003

This publication summarizes the in-house and contract research and development projects programed for fiscal year 1981 by the Bureau of Mines under its Minerals Environmental Technology activity. The document provides a mechanism for interested parties, including potential contractors, to gain insight into ongoing and projected work of the Bureau?s environmental research efforts. Research to identify and correct environmental problems associated with mining and metallurgical operations has long been an integral part of the Bureau's mission. The environmental research and demonstration activities of the Bureau were consolidate in 1979 with the formation of the Minerals Environmental Technology program, which is directed toward the elimination or reduction of environmental problems associated with the extraction and processing of minerals. Among the efforts underway are development of data and technology for assessing the potential environmental impact of minerals development, for monitoring minerals extraction operations, and for establishing viable reclamation requirements on abandoned mine lands; development and demonstration of technology 'or control of environmental disturbances during minerals extraction operations; development and demonstration of land reclamation and mine closure techniques to restore or enhance the productive use of mined lands; development of engineering techniques that incorporate state-of-the-art mining environmental technology in the design and planning of minerals extraction operations; development and demonstration of new mining systems that greatly reduce or eliminate the adverse environmental impacts of minerals extraction; and providing the technologic base for Federal, State, and local establishment of environmental standards for mining operations. Included in the minerals-processing-related work are projects to clean mineral-processing waters: demonstrate a Bureau process for scrubbing SO from powerplant stack :;as; recover dissolved minerals from process streams; stabilize discarded dusts, slags, and tailings: remove hazardous contaminates from byproduct wastes; reduce generation of waste solids; and improve metallurgical process engineering to eliminate pollution. Approximately $21 million was appropriated for this work in fiscal year 1981.

Jan 1, 1981