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By T. M. Barczak

Longwall tailgates in coal mines are often subject to severe mining induced loading and deformation. Innovative tailgate supports have been developed over the years to provide safe and economical access and a ventilation pathway at the tailgate. The support capacity and yield capabilities of the supports need to be matched to the loading imposed by the surrounding rock mass. The ground response curve can be used to represent the rock mass response to mining and its effect on support systems. The FLAC finite difference code was used to supplement field results by simulating a longwall tailgate and the associated ground response. The ground response curve is developed by modeling tailgate excavations with different internal support pressures and recording the resulting convergence. Ground response curves are developed for two typical longwalls operating in the Pittsburgh seam with weak and strong immediate roof. An additional model is presented in which the effect of weak overburden strata is simulated. The ground response is shown to be significantly affected by the strength of the immediate roof as well as the main roof. The importance of yield capacity of standing support is demonstrated. Gob height and compaction are found to affect the amount of convergence in the tailgate. The potential exists to develop site specific tailgate design curves by combining model results with field observations.

By Roger "Dean" Skaggs

Mechanical rock drilling is about 150 years old, and the fundamental principles of augering, penetration and dragging, pressure and rotation, and percussion have not appreciably changed. Surface mining blasthole drilling employs relatively shallow blastholes (to about 100 to 130 feet or 30 to 40 meters) with respect to the blasthole diameter and hole alignment while problematical is not a major universal problem. Modem underground mining methods are spacing development levels up to 400 feet (130 meters) apart, to take advantage of high powered mechanical drilling methods, requiring very long blastholes compared with surface mining. Blasthole alignment is a major problem in underground mining and this paper will address the aspects of percussion bit design which impact on hole alignment and drilling and blasting costs, i.e. bit geometry, cuttings removal, penetration-retraction.

Jan 1, 1997

By C. Dixon

The Abandoned Mine by C.C. Woollacott A heap of rocks marks the abandoned mine. The veld's unpitying silence lies around. Those broken stone?a mute and mournful sign Of human enterprise with failure crowned. Time with the slow hands, shall form the scene anew, Repair the gashes in the wounded soil, And cover up the last remaining clue To a poor useless record of men's toil. And this, the mound they built when hopes were high Shall be a grave, where those hopes buried lie. Outline This paper will consider the implications of the mine closure provisions set out in the new Mineral and Petroleum Resources Development Act and draft regulations. A comparison will be made with the existing provisions in the Minerals Act and the mine closure policy of the Department of Minerals and Energy (DME). The paper will consider whether the new provisions have the potential for improving performance as regards mine closure. It will investigate the financial provisions requirements and the implications of these provisions for mines. It will consider the requirements for a social and labour plan and consider the implications of this for mine closure and its funding. It will analyse the provisions relating to the transfer of environmental liabilities to third parties and consider the implications of this in the case of closing mines and non-closing mines. Finally it will consider the issue of residual legal liability of a mining company once a closure certificate has been issued.

Jan 1, 2003

By B. Tiryaki

Longwall shearers usually suffer from excessive pick and pickholder consumptions and severe wear of the back plate of the clearance ring section of shearer drums. In practice, most of the drums were seen to be withdrawn from the face due to the abovementioned problems, while vane picks and their holders were intact due to the improper lacing design of the clearance ring picks. However, few underground investigations and their results on the effect of lacing arrangement of clearance picks on the service life of shearer drums have been published. Nevertheless, the pick consumption characteristics of shearer drums were not investigated in detail, since these are fewer pick consumptions with shearers when compared to roadheaders. This paper is concerned with the comprehensive in situ trials on the effect of lacing of clearance ring picks on the lifespan of shearer drums, and the pick consumption characteristics of longwall shearers at Cayirhan Coal Mine in Turkey. The lifespan of shearer drums employed with shearers in this mine increased 70 per cent, while the consumption rate of clearance ring picks decreased threefold through using an alternative lacing for clearance picks, indicating the significance of utilizing proper design techniques for clearance ring picks for the service life of shearer drums. Statistical analyses carried out, using the raw pick consumption data, implied that the clearance ring picks experienced much higher loads than vane picks, revealing that special attention must be paid to designing clearance ring picks. An average maximum consumption value of 41 was determined for clearance ring picks, with corner-cutting picks having the most replacements, while it was 35 for vane picks, on three-day based pick replacements.

Jan 1, 2004

By D. J. Burger

This paper will highlight the system components of a successful underground mining automation project recently launched at DeBeers Finsch Mine. It will also show that integration of short-term mine planning with other upstream and downstream mining processes in the extraction of kimberlite ore from a block cave is not just critical to the future sustainability of this underground mining operation but also for profitability and cost-effectiveness. This paper will discuss the information data flow required from the mine-planning process through to production for underground block cave mining. The benefits associated with this type of integrated mine planning and automation system will be highlighted.

Jan 1, 2006

By Kwang ‘Min’ Kim, Paul T. Behum

The Old Bevier Aerobic Wetland in Macon County, Missouri, was constructed between 1990 and 1991 by the Missouri Department of Natural Resources’ Land Reclamation Program for the purpose of treating acid mine drainage (AMD). The principal source of the AMD is from an underground mine that operated during the 1920's through 1950's, which was partially exposed during surface mining in the 1960’s. Limestone bedding of an AMD collection system provided alkalinity similar to an anoxic limestone drain (ALD). Because the original aerobic wetland failed when a critical dilution water supply became unavailable, the total acidity of the AMD overwhelmed the limited neutralization ability of the aerobic wetland. The aquatic vegetation deteriorated and treatment became ineffective. The Missouri Land Reclamation Program with the assistance of the Office of Surface Mining, Mid-Continent Regional Coordinating Center rehabilitated the Old Bevier Aerobic Wetland in 2001, incorporating newer technologies to improve the performance. The new system, Old Bevier II treatment facility, consists of a 2-stage vertical flow pond (VFP) with associated oxidation cells and aerobic wetlands. This paper discusses the performance of this passive AMD treatment system, updating an earlier report. The new treatment system has operated with nearly continuous net alkaline discharge and a high iron removal rate. Treatment improves during warm months when emergent vegetation is fully established and biologic activity is greater. Reduction in system efficiency is evident during winter months.

Jan 1, 2005

By K. Awuah-Offei

An aggregate plant may have difficulty balancing product stockpile inventories if hot mix asphalt (HMA) design engineers do not account for aggregate inventory during mix design. Yet HMA design engineers do not, often, take this into consideration during asphalt mix design. This is due to the lack of tools that enable the lab technician or engineer to optimize the mix for good performance while helping the aggregate plant manage its stockpile inventory levels and reducing the aggregate cost. This work presents a linear programming model of the asphalt mix design problem that helps aggregate plants manage their inventory levels while meeting HMA customer demands. The algorithm is implemented in MATLAB as an Asphalt Mix Design Optimization (AMIDO) program. The program is successfully validated with real-life data. The results show that AMIDO can be used to successfully produce any mix design while reducing the cost of aggregates by using the cheapest stockpile materials. The application of AMIDO will increase aggregate plant profitability when serving HMA customers and could potentially be modified for concrete aggregate customers too.

Jan 1, 2009

By J. Chilton

The fact that methane ignitions continue to occur at the mining face indicates that monitoring with machine-mounted methanometers does not always indicate the presence of high methane concentrations. Methane concentrations at the face change quickly due to changes in airflow. By measuring these changes in airflow, it may be possible to predict changes in face methane levels more quickly. Currently there are no techniques or instruments to accurately measure airflow in by the mouth of the ventilation curtain or tubing. Tests conducted in the NIOSH ventilation test gallery compare the data provided by one-, two-, and three-axis ultrasonic anemometers. The effects of changes in airflow direction and turbulence on instrument readings are discussed, and guidelines are given for selecting the type of instruments to be used for monitoring airflow near the mining face.

By Clarence Karr

THE BUREAU OF MINES is investigating methods for upgrading tar produced by the low-temperature carbonization of bituminous coal. This survey was undertaken to compile information needed for identifying the ether constituents of low-temperature tar. Physical properties are listed for 1,024 aromatic ethers. The compounds include cyclic and noncyclic, polyfunctional and monofunctional ethers with oxygen joined directly to either one or two aromatic rings. Alkyl groups up through butyl are included. The compounds are divided into 37 groups ranging in complexity from alkoxybenzenes to dibenzopyrans. Compounds containing aromatic ether groups are important constituents of the neutral oxygen components of low-temperature tar. For example, at Morgantown, W. Va., the Bureau of Mines has identified and determined the amounts of benzofuran, 2-, 3-, 5-, 6-, and 7 -methylbenzofuran, diphenyl ether, dibenzofuran, 2,3-dimethyldibenzofuran, and two other dimethyl-dibenzofurans in the neutral oil from a low-temperature bituminous coal tar (103, 104).3

Jan 1, 1962

By R. Gunda

Due to the rapidly increasing production rates and deepening of mine working areas, there is a drastic rise in the number of thermal issues to be addressed for maintaining a safe mine environment. As high temperatures and humidity in underground mines could affect the health and performance of workers, and ultimately the production rate, it is necessary to provide a properly controlled safe environment. The backfilling of stopes in metal, non-metal mines results in different thermo-physical properties for the hanging, side and foot walls, modeling of which is not provided by any existing mine climate simulation software. This paper presents the modeling of such a single stope using the MULTIFLUX (MF) software, developed at the University of Nevada, Reno. A special case is presented in this paper, where a case study from the Homestake mine in the US with a drift and ramp connected to a stope with high Virgin Rock Temperature (VRT) and various spot heat sources is modeled in MULTIFLUX and CLIMSIM, and the results are compared against each other. Another case is presented in which the stope of the previous case is modeled with walls, each having a different set of thermo-physical properties. These results are compared with the former results to analyze the effect of anisotropic properties.

Jan 1, 2011

By J. Böhlke, B. Friedrich, E. Hecker

The legislation for the disposal of heavy metals contaminated substances is still going to be tightened up in the future. The main criteria for the utilization or deposition of these residues are the content and the water solubility of these metals. Through this, the use of slags from the lead-and zinc-industry in road building may become limited or even not possible at all. From an economic point of view this would lead to Pb/Zn losses and costs for safe dumping. This paper investigates the feeding of the reducing agent via hollow electrode DC smelting and the yield of metal reduction. After carrying out thermodynamic calculations, the process window conditions for electric-arc furnace tests were determined. Doing this, the zinc could be reduced, evaporated and recovered as an oxidic intermediate product flue dust, while the lead was present either in flue dust or in metallic form. The zinc content in the final slag could be reduced by up to 90%. The slag product has undergone an eluation test which allows it to be used as building materials. Keywords: zinc reduction, lead reduction, hollow electrode, slag treatment, electric arc furnace

By Verne E. Hooker

This Bureau of Mines report summarizes the results of modifications in the borehole deformation gage design and subsequent changes in the overcoring techniques. Modifications in the borehole deformation gage have greatly improved the creep characteristics and enhanced the versatility of the gage. In situ field tests in competent rock near St. Cloud, Minn., provided sufficient data to compare the reliability between gages and new techniques in obtaining good engineering estimates of stresses. Near-surface horizontal stresses at the test sites are compressive and biaxial in nature.

Jan 1, 1974

By Bill Linville

During fiscal years 1967-68, the Bureau of Mines produced 185 technical papers and reports about petroleum and oil-shale research, which were published either by the Bureau or by others as referable scientific literature. Numerous other reports were prepared for Government agencies, State agencies, and organizations of the petroleum and natural gas industry engaged in cooperative research programs with the Bureau. Research performed during the reporting period by the Bureau on petroleum, natural gas, and oil shale was classified by 71 active projects. A basic appropriation of $3,575,000 was supplemented by $1,300,000 in fiscal year 1967, and that of $4,043,000 by $1,402,000 in fiscal year 1968, making the appropriated-to-supplemental fund ratios about 2.8 to 1 for fiscal year 1967 and 2.9 to 1 for fiscal year 1968. In fulfillment of the mission of the Bureau, through planned research programs, methods for producing and utilizing petroleum were improved. The continued conservation of this natural resource of petroleum, including crude oil, natural gas, and oil shale, was pursued through research performed by some 350 personnel at two petroleum research centers and two petroleum research laboratories supervised and supported by administrative personnel of the Bureau and the Department of the Interior.

Jan 1, 1970

Application of Gy?s formula is appropriate for calculation of the Fundamental Error (FE) prior to samples being collected at any stage of the minerals process, provided that sampling parameters K and a (alpha) have been determined by calibration of the ores. Two types of calibration procedure are well established in the industry, the Hetrogeneity test and the 32-piece sampling tree experiment. The sampling tree experiment uses the variance and average grade of metal analyses from four series of samples at different nominal fragment size, as the basic input data. Pierre Gy suggested the cube as an appropriate exponent of the nominal fragment size for use in his equation. More recent work suggests that this exponent is variable and characteristic of specific ores and therefore requires calibration. The method described here explains the experimental procedure of the calibration. It is then possible to calculate a sampling nomogram using the sampling parameters K and a. This allows the sampler to determine a suitable protocol for the sampling event that will ensure that the FE does not exceed a predetermined precision at any point in the sampling procedure.

Jan 1, 2007

By A. C. Fieldner

All technical facilities of the Bureau of Mines have been geared for more efficient use and conservation of mining equipment, developing plans for safety, improving the quality of coal through better methods of preparation, studying the problems of coal storage and utilization, and extending the uses of coal5/ for the war and postwar economy. The Bureau is now analyzing all of the coal purchased by the Army and much of that required by the Navy. Work on boiler feed water was doubled over last year to meet the increased demand made by the War Department for protecting vital boiler plants in many new camps and defense plants. Progress has been made in safely storing coal to reduce dangers of spontaneous ignition to a minimum and to preserve coking power. Mixtures of oil and coal to be used as a substitute fuel have been investigated. Technical service on the conversion of plants to other fuels has been given to government agencies and private consumers. The possibilities of making motor fuel,

Jan 1, 1944

By D. A. Bruce

The use of small diameter cast-in-place bored piles is becoming increasingly popular in the United States. Such inserts are used as conventional load bearing piles, and are generally referred to as pin piles. The other major application is for the in situ reinforcement of soil slopes or excavations. The paper reviews the applications, construction, design and performance of inserts of each type.

Jan 1, 1989

By E. Niehuis, J. Y. Kim, H. G. Cramer, S. L. Chryssoulis, K. G. Stowe, C. Bendel

TOF-SIMS was used to detect, identify from parent molecular ions and determine the relative concentrations of collectors sorbed on the surface of mineral particles in concentrate and tailings samples from three Canadian concentrators. In the Kidd Creek Zn circuit, sphalerite lost to tailings carried on average a quarter of the amount of isobutyl xanthate present on that recovered to Zn concentrate; amyl xanthate, which is not reported as added to the circuit, was also detected on floated sphalerite and pyrite. At Brunswick, sphalerite particles lost to the scavenger tailings had ten times less amyl xanthate and isobutyl xanthate than those recovered to the Zn final concentrate, while both xanthates were detected on sphalerite floated to the Cu-Pb cleaner circuit. At Matagami, significantly more isopropyl xanthate and isopropyl dithiophosphate were detected on sphalerite recovered to the final Zn concentrate than on that lost to the Zn rougher tailings

Dec 1, 1995

By K. P. Davey

In 1998 an initial objective was given to the author, to process valuable off grade High Carbon Ferro Manganese (FeMn) metal fines profitably. The previous attempts that had been made to re-melt these metal fines through the furnaces had resulted in poor furnace operation, mainly to do with lack of electrode penetration and furnace bed permeability. It was decided that the method to resolve these problems was to agglomerate the metal fines. During the study on the agglomeration of the metal fines, a decision was made to use furnace baghouse dust and stockpiled furnace baghouse dust and sludge (DSF) as a ?filler? in the metal fines. The primary reason for using baghouse dust was to eliminate an environmental hazard, whereas the secondary reason for using the DSF was to utilize manganese units contained in the dust. The off-grade metal fines and dust were compacted using a brick press, with cement and aluminum rich plastic clay as a binder, to obtain agglomerate that was cost effective. Through the re-melting of the agglomerated off-grade metal fines, it was realized that this agglomerate concept could have other uses, that of replacing ores on the furnace, at a lower cost. The agglomerate recipe was changed to create an agglomerate that had a high manganese to iron ratio, this replaced Comilog ore on the furnaces, thereby reducing overall furnace unit costs. Future work concerning agglomeration, is to reduce furnace costs further through agglomerating .0.5mm ultra ore fines and .0.3mm Gloria and Nchwaning sludge. Using this agglomerate replaces a portion of the Gloria and Nchwaning lumpy ore on the furnaces at a lower cost. This would eliminate problematic material that exists at the ASSMANG Manganese mines.

Jan 1, 2004

By J. A. Vallejos

Re-entry protocols are a tactical approach for controlling risk after blasts or large events in seismically active mines. Based on the results of a survey on 18 seismically active mines, mostly in Ontario, current re-entry practices are summarized. Over half of the mines in Ontario use event decay rate analysis as their primary re-entry decision making parameter. We study in detail the applicability of the Omori?s law as an equation for describing the event decay rate for more than 250 mining-induced aftershock sequences in seven different environments. Practical guidelines for the use of the Omori equation as a re-entry criterion are proposed.

May 1, 2009

By Leon Lorenzen, Victor E. Ross, Anton W. Kleingeld

"Key to successful innovation, whether at organization, industry or national level, is the alignment and utilization of resources in the most appropriate and efficient way. Innovation needs to be directed strategically, and it needs to be auditable in a systematic and integrated fashion. In the light of these considerations, this paper describes the construction and use of a topographical map of the innovation landscape of an organization. The purpose of the map is to provide a holistic view of the key factors that enable innovation (the so-called 'landmarks'), how well they are aligned to support a particular type/nature of innovation in the organization (e.g. radical vs. incremental innovation), and to identify possible gaps between actual and sought performance.The landscape covers four domains that influence innovation - the attributes of the individual, the organizational context in which he/she functions, the business environment (the market / industry in which the organization is operating) and the external environment. The significance (importance) and height (performance) of the landmarks in supporting and enabling innovation within the organization is determined by means of a self-appraisal audit. The topography of the landscape derived thus is subsequently interpreted in terms of the organization's particular innovation strategy and environmental context."

Jan 1, 2003