Search Documents

By Nicolae Dobritoiu

The literature in this field and the practical activity record that a method, respectively the technology used for an underground mining work have many components which, in order to be applied, demand that for each of the parameters that describe the environment of the mining work and that influence the chosing of that method and that technology of execution, must have values in an interval well determined. There are situations when one or many parameters of the set of parameters that describe the environment of the mining work, can modify its values, and, as a result, one or more components of the methods or technology cannot be applied anymore, making necessary a replacement of their values. The information offered by this graphical-analytical model allow the determination of optimum solutions for the process of digging of the underground mining work and thus it will result the incresing of the technical-economical efficiency of the digging process and, also the increasing of the quality of the underground mining work.

Oct 1, 2009

By E Ah Mu and C R Lilley, A D. Campbell

Cave propagation is a complex process due to interacting variables such as mine geometry, rock mass heterogeneity and complex structural networks and stress fields. The Ernest Henry sublevel cave (SLC) is directly below an open pit, which provided an opportunity to observe and measure rock mass failure as the cave initiated and propagated through the pit wall. This paper describes interaction between the open pit and SLC as well as rock mass failure mechanisms observed from the start of the SLC to surface breakthrough.Cave propagation and slope failure mechanisms were found to be governed by intermediate structures, while the cave shape was largely controlled by cave-scale faults. The open pit, production-level geometry and production draw strategy were also important factors for cave and subsidence growth. Cave propagation was episodic and asymmetric in shape due to the orientation and relative position of geological structures, combined with the effects of the increasing SLC geometry and drawdown from the underlying production levels. The precursors and failure mechanism of a 2.5 Mt wall collapse are also reviewed in detail.Cave growth was simulated using a 3D, non-linear, discontinuum finite element model coupled with Newtonian Cellular Automata. Model results are compared to field observations and monitoring data to determine the accuracy of forecasts and compared models versus actual rock mass response during cave propagation.CITATION:Campbell, A D, Ah Mu, E and Lilley, C R, 2016. Cave propagation and open pit interaction at the Ernest Henry Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 311–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Jiulong Cheng

Underground coal mining causes overburden deformation and failure, one major form of which is bed separation in the overburden. Surface subsidence can be controlled by injecting grout into the bed separations. For a long time, the grouting results of bed separation can not be validated. This is the problem in the application of this technique. This paper analyzes the conditions leading to bed separation, develops mathematical models for seismic wave fields generated before and after bed separation, and bed separations grouted with different materials, and computes the seismic wave field characteristics using the finite difference method. The results show that the existence of bed separation causes changes in the characteristics of seismic wave field, and that different grouting materials generate different seismic wave field characteristics. Intact strata, bed separation, and bed separation filled with air or water all display distinctive seismic wave field in amplitude and frequency spectra. After mining, the original location that provides strong seismic reflection wave no long exists. It is replaced by a weak and syncline-shaped reflection wave. The area, where the seam wave disappears, is larger than that of the mined area. The location, where a bed separation occurs, generates a set of reflection waves stronger than the normal one. The energy of the reflection waves varies with the materials filling the separations. Bed separations filled with air generate stronger reflection waves than those filled with water. The major frequencies for those filled with air are lower than those filled with water. Therefore, it is possible to determine the property of filling materials by analyzing and comparing the amplitude and frequency spectra of the reflection waves. Case studies of application of seismic method for exploring bed separations and grouting were analyzed. The results show that it is feasible to use seismic technique for exploring bed separations and grouting.

Jan 1, 2006

By T. A. Sullivan

The processing of sweated aluminum electronic scrap was investigated to develop methods for recovering the aluminum and concentrating the other metals, including copper, lead, gold, and silver, into a product that can be separated by known methods. Two molten-salt electrorefining processes were developed and tested. The first process utilized a three-layer refining cell with a BaCI2-NaF-AIF3 electrolyte, which operated at 750° to 850° C. The second process used an all-chloride electrolyte of NaCI-KCI-AICI3 at 750° to 800° C, with separate anode and cathode compartments. High-quality aluminum was recovered that averaged 99.8-percent pure in the three-layer cell and 99.6-percent pure in the compartment cell. Over 94 percent of the aluminum was recovered with cathode current efficiencies of approximately 90 percent in both methods. The copper, lead, tin, silver, gold, and other metals were concentrated threefold in an anode product. Separation of lead and part of the tin by liquation from this product seemed feasible. The anode product was smelted to prepare a 96-percent copper bullion that contained 690 ounces of silver and 65 ounces of gold per ton, with 98 percent recovery of these values.

Jan 1, 1972

By Peter Radziszewski

"Comminition process costs, which typically represent an important contribution to mining operating costs, can themselves be divided roughly between energy and liner /charge wear. As such, developing the ability of predicting mill wear will allow a more accurate estimation of wear costs and therefore their control. In this paper and based on the possibility of estimating energy dissipated in impact and abrasion by using a discrete element charge motion model for mill charge motion simulation, media wear will be investigated principally as a function of three wear mechanisms : impact, abrasion and corrosion. Experimental results will be used to identify a total media wear model. Model results will be compared with real mill data from three operating Australian mines. These preliminary results show for the cases tested that the overall average error, as compared with the observed cases, is 0 % with a standard deviation of 66.1 %. Results from the Bond abrasion index tests, for the same cases investigated, give an overall error of 73 % and a standard deviation of 192.5 %. Further work is in progress to improve test procedure, validity and confidence.INTRODUCTIONComminition process costs, which typically represent an important contribution to mining operating costs, can themselves be divided roughly between energy and line / charge wear. In Greenfield situations where the estimation of operating costs is critical in determining project feasibility, the level of confidence in such estimates becomes quite important. With regards to media wear, the Bond abrasion test currently serves as the standard media wear prediction device. However, as shown [l, 21 test results once compared with actual wear rates can vary greatly. Figure 1 shows test results as compared with 15 cases. Average error over this data is 73 % with a standard deviation of 192.5 %. As such, developing the ability of more accurately predicting mill wear will allow greater confidence in wear cost estimation and therefore their control."

Jan 1, 2001

By David B. George

Kennecott Utah Copper adopted Outokumpu Flash Smelting and Kennecott-Outokumpu Flash Converting in 1995, a process based on granulating high grade copper matte. While nickel mattes and very small quantities of copper matte had been commercially granulated for years, no large scale copper matte granulation system had been built. This paper summarizes the history and benefits of copper matte granulation, the Kennecott design basis, the successful operation for over 10 years and potential problems inherent in some matte granulation approaches.

Jan 1, 2006

By Brown H. R, Wright E. A

The authors identify the workable coal seams, their distribution in relation to quality and economic occurrence and relate their analytical characteristics to industrial use. The development of established collieries is also discussed with regard to increased production demand.The authors also indicate the potential of the coal resources of the Southern District and postulate their ultimate development.INTRODUCTIONThe Southern Coalfield yields 30 per cent of the total production of bituminous coal in New South Wales. The economic potential of the coalfield was examined last by Harper (1915). Since that time additional knowledge has been gained by prospectors, mining companies and public authorities. Expansion in the steel industry and the building of power stations on the coalfields together with improvements in fuel technology, mining methops and road transport have resulted in production of coal from seams mice thoughtto have no economic value.DESCRIPTION OF THE COALFIELDFor the purpose of this paper the term Southern Coalfield includes also the South-Western Coalfield which together comprise the following Coal Districts:IllawarraDouglas ParkWollondilly-NattaiMoss Vale-Berrima (Hanlon, 1953).Geographically the coalfield is contained by the Illawarra Range in the east, the Shoalhaven River to the south, the Wollondilly River to the west, and in the north by a line...

Jan 1, 1958

By D. R. Brox, J. Levell

The Montana Tunnels Mine was mined out to a depth of 900 feet at the end of 1999. The first signs of instability were recognized in 1996 along the upper slope area of the northwest sector when the pit was mined out to a depth of approximately 500 feet. To extend the life of mining operations, it has been proposed to extend and steepen the northwest highwall to a depth of 1000 feet. Slope stability analyses were carried out using the UDEC software program to assess the stability and deformation of the proposed highwall design. Back analysis of an instability in 1997 along the upper slope section and highwall deformation to date has indicated reasonable agreement with the observed mode of failure and displacement monitoring results. The results of detailed analyses of the proposed highwall design have indicated very limited additional deformation, further development of tension cracks is unlikely and large-scale instability is not expected to occur. A total of 40% of additional mining has been completed and ongoing displacement monitoring to date has confirmed very limited additional movement and no further tension crack development.

Jan 1, 2001

By M. E. Poad, M. M. McDonald, J. C. Johnson, W. G. Pariseau

A U.S. Bureau of Mines case study of pillar recovery in high-grade ore near the Ross shaft at the Homestake Mine, Lead, SD, has demonstrated the usefulness of the finite-element method for evaluating shaft pillar mining plans and shaft stability. This report focuses on mine measurements and calibration of the two-dimensional computer model and is the second in a series of three Reports of Investigations describing the Ross shaft study. In this study, borehole extensometers and other instruments were installed to provide data for model verification and to monitor the shaft. Results of the recalibrated two-dimensional model (UTAH2) confirmed the premining stability evaluation. However, after mining began, concern was expressed because cracks and other signs of ground motion appeared at considerable distances from the area of active pillar mining. In part 3 of the study, an intense three-dimensional modeling effort using UTAH3 was initiated. The results again showed that the observed effects were within expectations and that the shaft would remain safe. Three-dimensional analyses of alternative pillar mining scenarios indicated that more of the shaft pillar ore reserve could be recovered than previously thought.

Jan 1, 1995

By Michel G. Grenier

Compliance with Diesel Particulate Matter (DPM) exposure regulation is currently performed using timeweighted average (TWA) sampling on underground mine workers. These samples are collected in the span of an entire shift and the resulting concentrations are compared to a legislated exposure limit. While this is very useful to determine the exposure level of an individual to DPM, it fails to clearly identify causes of exposure and highlight opportunities that could help reduce the exposure of workers in the course of the work shift. Real-time DPM monitoring measures the worker?s exposure as a function of time and helps identify circumstances where corrective actions can be taken or design changes can be made by the individual or the employer to reduce the overall exposure of the worker and peers. This work focused on obtaining DPM concentrations using a real-time polycyclic aromatic hydrocarbon (PAH) monitor. The aim was to demonstrate that this instrument, while not a direct DPM analyzer, was able to provide a concentration profile that could easily be linearly correlated to standard TWA elemental carbon measurements. In addition, several instances of improvements that could be implemented to reduce the exposure of underground employees were demonstrated.

May 1, 2010

By F. D. Fox

The Flambeau and Ridgeway Mines, both owned and operated by wholly owned subsidiaries of Kennecott Minerals Company, were located very close to populated areas having initial concerns about health, safety and the environment. The success of both operations depended upon developing a framework of community support and enhancing sustainable development opportunities throughout the entire life cycle of the mining operations to address these concerns. The protection of the Flambeau River was the cornerstone of the Flambeau Mine’s success. The highest priority for the Ridgeway Mine was to ensure long-term physical, chemical and ecological stability of the reclaimed mine site. Both of these goals have been achieved and are discussed in this paper, which highlights Kennecott Minerals Company’s integration of sustainable development principles into its business decision-making and management processes.

Jan 1, 2003

By Patrick J. Coleman, John C. Kerkering

Problem: Mining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injury rates over the last century. Coal mine fatality rates, for example, have dropped almost a thousand fold since their peak in 1908. While incidence rates are very important indicators, lost worktime measures offer an alternative metric for evaluating job safety and health performance. The first objective of this study examined the distributions and summary statistics of all injuries reported to the Mine Safety and Health Administration from 1983 through 2004. Over the period studied (1983 2004), there were 31,515,368 lost workdays associated with mining injuries, for an equivalent of 5,700 person years lost annually. The second objective addressed the problem of comparing safety program performance in mines for situations where denominator data were lacking. By examining the consequences of injuries, comparisons can be made between disparate operations without the need for denominators. Total risk in the form of lost workday sums can help to distinguish between lower and higher risk operations or time periods. Method: Our method was to use a beta distribution to model the losses and to compare underground coal mining to underground metal/nonmetal mining from 2000 to 2004. Results: Our results showed the probability of an injury having 10 or more lost workdays was 0.52 for coal mine cases versus 0.35 for metal/nonmetal mine cases. In addition, a comparison of injuries involving continuous mining machines over 2001 2002 versus 2003 2004 showed that the ratio of average losses in the later period to those in the earlier period was approximately 1.08, suggesting increasing risks for such operations. Discussion: This denominator free safety measure will help the mining industry more effectively identify higher risk operations and more realistically evaluate their safety improvement programs. Impact on Industry: Attention to a variety of metrics concerning the performance of a job safety and health program will enhance industry's ability to manage these programs and reduce risk.

By Eleanor Abshire

THIS PUBLICATION is the third to be prepared as a result of a cooperative project by the Bureau of Ships and the Bureau of Mines for accumulating literature published on zirconium and hafnium. The undertaking also resulted in the establishment of an information center on zirconium and hafnium at the Bureau of Mines station at Albany, Oreg., for the use of research organizations and others. The present bibliography consists of references (with abstracts) to pertinent literature on zirconium. The first publication in this series was Information Circular 7771, Bibliography of Zirconium, published in April 1957. It consists of 969 abstracted reports and 645 U.S. and foreign patents. The second publication, called a supplement to Information Circular 7771, is numbered Information Circular 7830 and consists of 844 abstracted reports and 62 U.S. and foreign patents. It was published in October 1958.

Jan 1, 1962

By E. P. Youngman

Zirconium, formerly distinctly a rare element, is rapidly becom- ing of rather extensive commercial importance. Economic features of the zirconium industry, together with general information regarding the metal and its compounds, are discussed in a separate paper, to which this paper is a supplement. In addition to giving a brief discussion of the four or five de- posits that so far have proved to be commercial sources of the element, this circular summarizes available data (including some hitherto unpub lished material from the files of the Bureau of Mines) upon other occur- rences, including many of scientific interest only, of the two commercial. minerals, zircon and baddeleyite, and also data upon some of the minor minerals, such as eudyalite and cyrtolite, which have attracted addition- al interest in recent years because they are frequently richer in hafnium than the more common zirconium minerals.

Jun 1, 1931

By Rowan A' Murry Karstel

One way to ensure dragline productivity is by Increasing the size of the dragline bucket. In August 1994, Optimum Colliery in conjunction with Van Reenen Steel, Northwest Applied Technology, SSAB of Sweden and Barlows Equipment launched the new lightweight dragline buckets. Optimum built the first prototype bucket that was used for the deslgn for future buckets. After knowledge had been gained from measuring the input force of the bucket Northwest Technologies designed the new bucket with finite element analysis. Together with the knowledge of quenched and tempered steel from SSAB of Sweden and Barlow Equipment, the new Wrightech bucket was born.

Jan 1, 1998

By A. D. Davis

Limestone-based material is effective for reducing arsenic concentrations below the current limit of 10 parts per billion for drinking water, typically resulting in final concentrations of about 4 to 6 ppb. However, in laboratory and field testing, further reductions to the 1 ppb range are difficult to achieve with limestone unless other material such as iron is added. The removal mechanism with untreated limestone appears to be the formation of a low-solubility precipitate of hydrated calcium arsenate, in the form of arsenate-apatite. Likely reactions and thermodynamic data indicate a theoretical removal limit of about 2 to 4 ppb for arsenic using raw limestone. Limestone also can reduce concentrations of cadmium and lead below 1 ppb in water, resulting in >99% removal efficiency. Thermodynamic constraints appear to be favorable for reactions involving the formation of otavite during cadmium removal and the formation of hydrocerussite during lead removal.

Feb 27, 2013

By Patrick E. Durnal

A joint venture of Ben C. Gerwick Inc., Sverdrup (now Jacobs) and DMJM (now DMJM Harris) designed the $779 mill seismic upgrade of the Richmond - San Rafael Bridge over the San Pablo Bay in the San Francisco Bay Area and provided construction support to Caltrans. Construction of the marine foundation retrofit was completed by a joint venture of Tudor Saliba/Tidewater/Koch-Skanska and their subcontractors: Pomeroy Precast Construction, AGRA Foundations, Dutra Construction and Vortex Divers. Construction management and inspection was performed by Caltrans with support of various consultants.

Jan 1, 2013

The presence of gold or tin in a particular place in payable quantities may be suspected from geological and prospE;cting reports. It behoves the engineer by judiciously spaced boreholes or pits to establish whether the place is exploitable with profit, and it is the purpose of this paper to set out the ways in which this is done. The various types of deposit to be considered occur in Malaya, Thafland and Borneo, in which countries the writer spent four years in estimating alluvials.The methods described were used in actual practice both by the writer and previous engineers for the same company. The subsequent exploitation of the alluvials evaluated by the methods given below shows that the recovery was as good as, and sometimes higher than, expected. No claims are made to the originality of the methods, but it is 'felt that they may be new to some engineers and< interesting to others contemplating alluvial testing.

Jan 1, 1942

By S. C. Langvik

The presentation named 'Dewatering of fines by Rotary Vacuum Disc Filters' has an opening why the filtration process is important to the Iron Ore Industry. It goes on to describe the various types of dewatering machines which have been used in this industry in the last 30-40 years, and where the vacuum disc filters now dominates. It presents also the most important design changes which have been made during this period to enhance performance. Further are discussed the principles of filtration and the factors and parameters which influence performance and operating costs. As a closing is presented today's ideas and thoughts about what can be foreseen of design modifications and improvements in disc filter design in the coming ten years.

Jan 1, 2001

By Roger Scarr, Richard A. Walker

Interactive video is the combination of computer and laser disc -technologies that allows for the storing of 54,000 single images or 30 minutes of video with the ability to access any segment or single image within a half a second. This capability combined with the use of a graphics overlay on the video and accessed through a keyboard or touchscreen creates a very powerful and versatile marketing or training tool.

Jan 1, 1990