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By D. D. Bush

Based on the results of this study, the underhand cut and fill stoping method, with mass destressing, is an effective method for controlling rock bursts and falls of ground for deep mining in the Coeur d'Alene Mining District. The procedure can be utilized to pull highly stressed pillars by converting from conventional overhand stoping methods or used as a primary recovery system. During the demonstration, only one minor rock burst occurred, with no injuries. The system facilitates accurate placement of vertical boreholes for effective mass destressing. Each mining cut is filled with cemented sandfill overlying a timbered mat that forms the back for the succeeding cut. For this demonstration, a cemented fill was mixed on the surface and piped to the stone. Costs for pillar recovery by this method are comparable and are considered cost effective over conventionally timbered overhand mining as a pillar recovery method.

Jan 1, 1982

By G. M. J. van Heerden

Paper written on project work carried out in partial fulfilment of B. Eng (Mining Engineering) degree The Union Section of Anglo Platinum is situated ±18 km west of the town of Northam on the north-western rim of the Bushveld Igneous Complex. Both the Merensky and UG2 reefs are mined. Support of the Merensky stoping areas with rock bolts is specifically problematic due to the stoping width restrictions varying around 90 cm. The installation equipment of in-stope rock bolts and the effectiveness thereof in the Merensky stoping areas was critically evaluated. In order to do this a background research on the need for better on-the-face support had to be conducted. The need for improving the rock bolt drilling and the equipment had to be investigated and the financial implications and justifications for the improved equipment examined. To conduct the search an overall study was done on the rockfalls and safety aspects throughout the platinum industry in South Africa and specifically Union Section. It was found that most of the rock falls in the Merensky stoping areas of which ± 70% are less than 1.2 m in thickness generally occurs within 4 m from the face and causes ± 60% of the in-stope injuries. Serious shortcomings had been identified with respect to the airleg, rock drill machine and the drill steels used in the drilling of the rock bolt holes. Through experimentation, using a testing frame built for this purpose on surface and with the co-operation of mine staff and suppliers, a number of possible modifications were identified and tested. This resulted in the final product with which it was possible to drill a 1.2 m hole in the hangingwall of the stopes ranging with an angle to the hanging from 90° for a 90 cm stoping width and 67° for a 80 cm stoping width. It is confidently concluded that this system will effectively improve the total face support and result in a substantial reduction of rock falls and consequently the occurrence of injuries and fatalities in the Merensky stoping areas. The installation of rock bolts on the face with the modified drilling equipment will increase the direct support, but the system has a potential of a substantial reduction in the profile stick support density and an increase in productivity in the stoping areas due to fewer occurrences of rock falls. It was finally concluded that effective modifications to the drilling equipment for rock bolt in-hole drilling could be made and the installation thereof in the stope face is adequately justified.

Jan 1, 2002

By Louis Schaffer

The objectives of the research were to determine whether a model health and safety program could be defined in terms which would enable its application to mines of all types, and, if such a model program could be defined to determine through evaluations in two mining companies whether it would achieve measurable improvements. This volume describes the model, how it was applied in the field, and how it was evaluated. Anecdotal data to illustrate common kinds of safety problems and their solutions are included. The literature and field research that preceded the model definition is discussed in Vol. 2, which covers the period of September, 1980 to September, 1981.

Jan 1, 1983

By D. G. Krige

For the purpose of determining confidence limits for ore grade estimates, an extensive simulated database was used, which included 1728 ore blocks with ?actual? grades and the corresponding estimates based on ordinary and simple kriging. The practical results show that conditional unbiasedness is essential and that acceptable confidence limits can then be set using Normal theory for the simulated error distribution based on the logarithms of the ratios of ?actuals?/estimates with a variance related to the kriging variance. The mean of the data used to prepare the variogram and the estimated block grade are to be used properly in this approach. A practical analysis was also done of the actual point and block data from a very large mined out Carbon Leader area. The distributions of the actual grades for two levels of block sizes with different levels of variability were fitted using three models, ie. two three and compound lognormal. The trends of tonnages, grades and relative profits for a range of pay limits, as well as the usual tonnage-grade curves, show a practical insensitivity for the choice between the three lognormal models considered.

Jan 1, 2004

By D. Diering

Having agreed to perform this task, I naturally started to wonder what on earth I was going to talk about, and on reviewing the literature I was surprised at how little I knew and how much I?d forgotten about the origins of this industry. For example: ?I?d forgotten that the Chinese invented black powder at least 1 000 years ago, back in the 10th century (although some say this invention occurred 2 000years ago). ?I didn?t know that Roger Bacon was the first person in the Western World to give exact directions for the making of gunpowder in 1242 and to understand its potential. Pepper?s Playbook of Metals quotes:?...above all, he is named as the discoverer of gun-powder, a material which has brought more wonderful changes in the great family of man than the most potent elixir that could have been devised to prolong life?.

Jan 1, 2000

By R. G. McLusky

This paper analyzes the opinion in Bragg v. Robertson, 72 F.Supp. 2d 642 (S.D. W.Va. 1999), a case which threatens the future of surface mining in West Virginia and which will almost certainly result in new policies or rules that will affect surface mining everywhere. This paper addresses: (1) the jurisdictional bases of the action which relies on the federal surface mining laws to enforce a state mining program; (2) settlement agreements reached in the case that threaten to alter federal policies beyond West Virginia borders; (3) a programmatic environmental impact statement on mountaintop mining being undertaken by the federal government; and (4) an opinion by the Court outlawing excess spoil disposal in intermittent and perennial streams.

Jan 1, 2001

By W. G. Willson, D. E. Walsh, B. Irwin

Low-rank coal (LRC) drying processes are generally categorized by operating temperature, drying environment and type of feed (either sized or ground coal). Within these broad categories, drying processes differ according to the type of drying equipment and methods of quenching and stabilizing the dried products. This paper focuses on the produce quality of various LRC drying processes including conventional low and high temperature evaporative drying and non-evaporative, hydrothermal drying. The former may be preferred if the dried product can be utilized immediately, but moisture reabsorption, spontaneous heating and fines production during handling are problems associated with longer term storage, transportation and utilization. Methods for reducing these problems are discussed. Hydrothermal processing is an advanced technology featuring high pressure, non-evaporative drying, which solves stability problems by producing a liquid feel.

Feb 24, 1997

By J. J. Lukasko

The U.S. Bureau of Mines developed an alternative electrochemical process for the production of calcium metal. The current industrial practice is costly, complex, and inefficient. The Bureau method involved electrowinning of a calcium-tin alloy followed by electrorefining to produce calcium metal. In the electrowinning cell, CaCI2 was fed to a KCI2-CaCI2 electrolyte. The calcium was electrowon at 6500 C into the pure molten tin cathode until the cathode contained 7.5 wt pct Ca. Current efficiency for electrowinning averaged over 90 pct. The resulting calcium-tin alloy served as the anode for the electrorefming cell, which employed a [CaC~-CaF2] fused salt as the electrolyte. Calcium metal was electrorefmed at 8500 C with a current efficiency of 85 pct based on calcium metal recovered. The calcium metal analyzed 99.2 pct, which is purer than commercially produced calcium.

Jan 1, 1990

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60 percent and 40 percent, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert, and a rigid insert for cleaning the roof bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the coveralls when using either of the inserts.

By K. R. Gardner, P. B. Altringer, R. H. Lien, B. E. Dinsdale

The Bureau of Mines, U.S. Department of the Interior, is investigating chemical and biological decontamination of complex wastewaters such as tailings pond water containing 280 ppm CN and 5 ppm Se as well as significant concentrations of arsenic, copper, iron, silver, and zinc. The most effective chemical procedure involves cyanide oxidation using hydrogen peroxide or sodium hypochlorite followed by selenium reduction using ferrous hydroxide. The effluent contains ?1 ppm CN and 20 ppb Se; concentrations of other - major contaminants meet National Drinking Water Standards. Preliminary research indicates that biological cyanide oxidation is possible even in highly alkaline solutions (pH 10.5) containing high cyanide concentrations; indigenous bacteria destroyed 85% of the cyanide. Exploratory research shows that other bacteria removed up to 79% of the selenium from chemically oxidized, low- cyanide water. These promising results may lead to a final processing scheme that involves a combination of chemical and biological techniques.

Jan 1, 1990

By Jeff Kravitz, John Kovac, Wayne Duerr

Since 198 1, Federal mining law has required every miner working in underground coal mines to have a self-contained, self-rescuer (SCSR) available for use in emergencies. Some miners that have escaped from fires using SCSR's have reported that they had to remove their mouthpiece to talk during escape, thus compromising the protection afforded by the SCSR. If miners are in thick smoke during an escape, they may have trouble if they become separated from their group. The visibility can be so poor that separation can occur at very short distances. To address this problem, two-way, FM radios were built into the SCSR to improve the ability to communicate should the miners be separated over relatively short distances. The SCSR prototypes built and used in testing included both two-way radios and improved mouthpieces. Comparison studies were conducted using combinations of the new and old mouthpieces, and trials using the radio or not using the radio. Subjective judgments indicate that communication ability was significantly improved using the prototype devices. Communication problems have been encountered with teams using standard voice- powered communications systems. Mine rescue teams perform rescue and recovery work under extremely hazardous conditions, life lines are a standard part of mine rescue team equipment. Leaky feeder and quasi-leaky feeder life line communications systems provide significant improvements over standard systems. These improved systems allow all members of the team to communicate with each other and their base of operations. These innovations will significantly enhance the safety of mine rescue operations.

By W. V. Long, D. H. Reynolds, R. B. Bhappu

Equilibrium distribution coefficients were determined for some monovalent and polyvalent ions for several absorbing and exchanging media as functions of pH and initial ion concentration. Among ions studied were NH4 (I), K(I), Ni(II), Ce(III), Th(IV), and Mo(VI). Absorbents used were: ion exchange resins; a tertiary, and a quaternary amine in an inert solvent; and some activated carbons. The ions studied were in aqueous HCI, HNO3, H2SO4, or HC104 solutions. The classical mass action expression proved of little value in describing the variations observed. The data indicate that the determining factors in absorption and ion exchange may be the ionic species in the aqueous solution, which in turn depend upon pH, dilution, and perhaps other conditions. Three sorption processes have become prominent in recovering values from leach solutions. These are: 1) ion exchange, 2) solvent extraction (liquid ion exchange), and 3) physical adsorption by materials of high specific surface. In the first two of these processes the exchange reaction is considered chemical in nature, and is discussed in terms of the mass action principle. The third is considered a surface phenomenon and is discussed in terms of surface areas and various forms (Gouy, Stern, Grahame, etc.) of the Helmholtz double-layer theory. Generally speaking, we have found in chemical analysis and hydrometallurgical studies that there are close similarities between the three sorption processes, and also differences which are difficult to reconcile with any of the usual theoretical treatments. That others have experienced the same troubles is shown by the fact that usable processes, in chemical analysis as well as in hydrometallurgy, generally are discovered by empirical procedures. EXPERIMENTAL CONSlDERATlONS The gaps between theory and practice have allowed many conflicting statements to appear in the litera- ture. To learn, in particular, the behavior of some metallic ions on a cation exchange resin at a constant pH, equilibration studies were made over a wide range of concentrations.' Results are shown in Fig. 1 for four metals in hydrochloric acid solution on a strongly acidic cation exchange resin, AG 50W-X8 (Bio-Rad). The distribution coefficient, defined as D = amount of metal extracted per g of resin/amount of metal unextracted per ml of solution is seen to vary in a way to support all manner of reports about its behavior with changes in solution concentration. The metals used were chosen from those least likely to form stable chloro-complexes. The changes of slope in the various isotherms may reflect formation of unsuspected chloro-complexes of low stability (ion-pairing for example) whose concen-

Jan 1, 1967

By F. M. Goodwin, John Campbell, G. W. Jones

"INTRODUCTION In cooperation with the Boston Edison Co. and the Boston Consolidated Gas Co. of Boston, Mass., a survey has been conducted continuously since 1929 by the Bureau of Mines to determine the general hazards of combustible gases and vapors in manholes of the Boston Edison Co. The New England Telephone & Telegraph Co. also has cooperated in the investigation, and tests have been made in its manholes from May 1, 1933, to October 15, 1937. Yearly reports. 6/ on the results obtained since the beginning of the survey have been published.The methods and procedure of conducting the survey in 1937 were the same as heretofore."

Jan 1, 1939

By J. B. Clark

In 1933, R. paris1 published a phase diagram for the entire Mg-Ca-Zn system. He reported the existence of a ternary intermetallic phase, Mg5Zn5Ca2, which formed a quasi-binary with the magnesium solid solution. Since then, no extensive work has been reported on the system. Recently however, indications of the existence of a second ternary in-termetallic phase in equilibrium with the magnesium solid solution led to a reinvestigation of the solid phase equilibria involving the magnesium solid solution. The 335°C (635°F) isothermal section was chosen for study. Metallography and powder X-ray diffraction were selected as the best mutually corroborating methods for determining the solid phase constitution. Seventy-six alloys were prepared from singly sublimed (99.95 pct) magnesium, electrolytic (99.95 pct) zinc and USP calcium. The analyses of some of the alloys are shown in Fig. 1. The alloys were melted in a graphite crucible under a chloride flu and chill cast in a split graphite mold. Dif-fusion couples (see Fig. 2) were prepared by casting molten Mg-20 wt pct Zn alloy around a cylinder of Mg-30 wt pct Ca alloy. The alloy samples and the diffusion couples were sealed under argon in Pyrex vials and annealed in a furnace capable of controlling within 1/2°C of 335°C. At the conclusion of the anneal, the alloy samples were quenched in ice water and the diffusion couples were air cooled. Procedures standard for magnesium alloys were used for metallographic examination. Powder X-ray diffraction patterns were taken on a G. E. camera with a 14.32 cm dim using nickel-filtered copper radiation. The redetermined 335°C (635°) section of the Mg-Ca-Zn phase diagram is shown in Fig. 1. TWO ternary intermetallic phases, designated w and

Jan 1, 1962

Grouting is mainly used to improve mechanical properties or decrease the permeability of rock mass around civil and mining projects. The purpose of this paper is to present the most effective factors on grout penetration depth in rock mass. Such factors are essential for reliable estimation of the grout penetration depth and the expense for cement take of any grouting project. In this paper, about 50 different types of the relations presented so far by various researchers to estimate the depth of penetration in fractured rock were studied. The effective factors are classified to rock mass properties, grout properties, and operational factors. Results show that firstly, the discontinuities aperture and Lugeon value are respectively the most investigated factors of rock mass properties influencing on penetration depth. Secondly, the yielding stress, viscosity, and density of grout are the most effective factors of grout properties. Finally, grouting pressure has an intense effect among other operational factors. The investigations were also verified in Siah Bishe dam case study. Keyword: grout penetration depth, rock mass properties, grout properties, operational factors.

Feb 27, 2013

By K. Drescher

Excavations in deep level hard rock mines show rheological or time-dependent deformation responses to mining-induced stresses. These are generally not as dramatic as those seen in soft rock environments, such as potash and salt mines, but these deformations can nevertheless become substantial in time. It is usual to see total excavation closure at a much earlier stage than predicted by numerical models, and real-time measurements underground have confirmed that closure takes place on a more-or-less continuous basis, with highest closure rates observed after a blast and then slowly diminishing with passing time. This paper describes laboratory tests to determine the time-dependent response of hard rocks to loading, the results of the tests, and then quantifies these effects to explain the time-dependent phenomena observed underground. The primary intention of this work is to help explain the various time-dependent deformation processes around typical deep level hard rock tabular excavations. Three mechanisms were investigated in two typical hard rock types present in the deep level gold mines in South Africa, namely Ventersdorp Lava and Elsburg Quartzite. Uniaxial compression creep studies were done as the first part of the study followed by shear creep studies on discontinuities where crushed lava and crushed quartzite as well as a natural gouge were used as infilling. The last part of the study consisted of triaxial post-failure relaxation tests. The compression creep tests and the triaxial post-failure relaxation tests showed that the amount of energy dissipated by the lava is significantly less than for quartzite. For mines operating at depths greater than 2000 m the implication is that the lava must show a greater rockburst-proneness than the quartzite. Since the lava shows a lower post-failure stress relaxation, it can store sufficient energy for multiple rockbursts, which is seen in the clustering of multiple seismic events in the deep level mines. This study provides the first data available for energy change calculations in fractured rock masses, and provides the first general indications for rockburst intensities ahead of active mining faces.

Jan 1, 2003

By Richard L. Fowler

An automatic steering control system was designed, installed and tested on a coal mine shuttle car. The system utilizes sensors and associated signal processing electronics developed under a previous phase of this contract. The automatic steering system performs the routine guidance functions of turning corners and straight-through tramming. The shuttle car driver retains full authority of speed, braking, load and unload functions and at any time may exercise his option with manual override or steering. Steering information is generated from signals derived from the existing Lateral Guidance sensor subsystem, and all operational features of the previously developed open-loop system are retained. Above ground system tests were conducted in a simulated mine constructed of wood panel ribs. Results were in good agreement with prior hybrid computer simulations undertaken to validate the basic control system over a broad range of conditions and to select system parameter values. The automatic steering system was successfully demonstrated in the above ground simulated mine to USBM technical representatives. Designed to meet USBM permissibility requirements, the system is ready for a Phase II underground testing program. Testing in actual underground mine environment is expected to provide additional data regarding recommended performance improvements and implementation techniques.

Jan 1, 1975

By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations wi.thin a multiple-seam configuration. At two mine sites where such ground interactions were present, the Bureau performed a complete geological analysis and installed and monitored instrumentation to gather pertinent data on rock mechanics. Overburden depth varied dramatically in the vicinity of the study area and reached a maximum at the study site; innerburden thick-ness was less than a pillar width (40 to 4S ft); heaving was experienced in both mines where sandstone and/or shale floor units were observed; overlays of the mine layouts show pillars were not totally superpositioned; a maximum of S in of roof to floor convergence was measured; and pressure readings indicated pillar core loading only and increased to a maximum of 7,000 psig over instrument setting pressure.

Jan 1, 1987

By S. C. Tennant, G. M. Steed

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. Immobile-element lithogeochemistry is providing a detailed chemostratigraphy of the submarine Ordo-Silurian volcano-sedimentary sequence. Primary lithologies and magmatic affinities of the sericitised and silicified volcanics are determined from binary plots of Nb, Zr, Y, TiO2 and Al2O3, while mass-change calculations using immobile-element anchors can identify and quantify zones of significant hydrothermal alteration. Stratiform polymetallic mineralisation at the western margin of Parys Mountain, around the Penymynydd fault zone, has been shown to have a distinct hanging-wall and footwall stratigraphy. These ore zones are probably part of a homoclinal, north-younging volcano-sedimentary sequence. The apparent stratigraphic complexity results from primary lithofacies variations and pervasive alteration, with the modifying role of the Caledonian orogeny much less than previously suggested

Jun 19, 1905

By D. G. Klaren

Self-cleaning fluidized bed heat exchangers are conquering the world for reason that they are able to solve any severe fouling problem in indirect heat transfer due to the circulation of cleaning particles through the tubes of vertical shell and tube exchangers. In most cases, these particles consist of chopped metal wire. Moreover, self-cleaning fluidized bed heat exchangers perform with excellent heat transfer at very low liquid velocities, which makes completely new designs of shell and tube configurations possible. Further, self-cleaning fluidized bed heat exchangers show a strong shear thinning effect in non-Newtonian liquids. All the above characteristics make the self-cleaning fluidized bed heat exchanger an ideal tool for the indirect heating of laterite nickel slurry in High-Pressure-Acid-Leach (HPAL) plants. Preliminary tests and evaluations of these heat exchangers have shown that the performance and price of these heat exchangers used for the production of nickel and cobalt from a laterite slurry, cannot be matched by existing conventional heat exchange systems. This article explains the principle, design, lay-out and enormous advantages of the self-cleaning fluidized bed heat exchange technology in a plant suitable for an annual production of approx. 45,000 ton nickel and 4,500 ton cobalt from laterite slurry through high pressure'acid leaching.

Jan 1, 2002