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By Z. Zborovszky

The feasibility of using the nucleation properties of combustion generated particulates for the identification of their sources was investigated, using the Cloud Condensation Nuclei (CCN) Spectrometer. The Investigated materials included coal, wood, belt materials, electrical insulation, brattice cloth, and diesel exhaust. The materials were heated In an oven using filtered air flow, and their time, temperature, and the critical supersaturation spectrum of condensation nuclei (also referred to as the CCN spectrum) produced by the combusting material were recorded. Some data was obtained on a typical metal-mine background containing blasting products. The data was processed and analyzed In an attempt to specify parameters and limits that would allow the identification of the combustion sources. It appears that under controlled test conditions It Is possible to Identify the source on the basis of data derived from the CCN spectrum. More general use of the Idea for fire detection under uncontrolled practical circumstances in an actual mining environment does have potential but would require further research.

Jan 1, 1978

By Sheryl D. Gallagher

The project consisted of filling an abandoned underground limestone mine to facilitate construction of a new entrance ramp to I-470 in Lee?s Summit, Missouri. Due to collapse of mined areas near the project site, design included determination of the limits of remediation for the project and minimum construction requirements for mine infilling. The Judy Company, contractor selected for the mine infilling, experimented in the laboratory with several grout mixes to determine the appropriate mix for the project. Infilling was accomplished from the ground surface, and camera observation was used to monitor the barrier wall construction and infilling process. It was discovered that some of the mapped rooms were larger and some were smaller than indicated on the construction plan.

Jan 1, 2009

By Jochen Belz, Allan Henneker, Nod Clarke-Hackston

For the construction of tunnels and other underground structures, extraction of the exact amount of material is of paramount importance both economically and for engineering purposes. In the Sequential Support Method (NATM) immediate (sequential)and smooth support by means of shotcrete, steel arches, lattice girders and rockbolts, either singly or in combination are used; cutting of the precise (albeit sometimes of complex geometry) profile is an integral part of the method. In order to save unnecessary excavation and provide better information to the machine operator, VMT GmbH has developed a system to support precise excavation of the tunnel profile when using road headers or other partial face cutting machines. This paper outlines the principles of this system with examples from Australia, Ger-many, Sweden and Spain and will cite examples of typical savings achieved.

Jan 1, 2007

By F. A. Penning

An experimental and analytical investigation was conducted on a recoverable pit bottom buffer. Work was conducted at the Colorado School of Mines using the U.S. Bureau of Mine-s free fall test tower. The four-sided butter, one of several designs by Cable Belt Ltd., was constructed of reinforced rubber slabs. The kinetic energy of falling weights, 1670 to 6000 lb, was absorbed by the flexure of rubber slabs loaded along their edge. A series of constant energy, 3000 ft-lb and maximum design velocity, 600 fpm tests were conducted. Static testing of the buffer established the load-deformation behavior. A large hysteresis loop plotted above and below the data published by the manufacturer. Creep was evident during; the loading Lend unloading cycle. Electronic instrumentation measured deceleration using your accelerometers; overall and intermediate movement was found from four displacement transducers; bending strains were recorded at four locations; and base reactions were measured by using four load cells. Data were recorded on tape and played back on a recording oscillograph. High speed movies were taken of all the tests. Symmetry of response and rebounds, when they occurred, were noted. From the displacement-time and load-time data, maximum decelerations were calculated by four methods and different assumptions. Good agreement was found from these approaches. Impact loads ranged from a low of 0.7 to a high of 6.1 gs. A dynamic computer model was written for the response of the buffer. Displacement-time, and acceleration-time plots show close correspondence with experimental data for the ten experiments. Data from accelerometers, displacement transducers, strain gages, and load cells are included. The computer program listing, and displacement-time acceleration-time plots are also presented.

Jan 1, 1980

In some parts of the world explosions in mines are more commonplace events. Even in the more developed nations explosions have occurred in recent times. In some cases these mines have significantly lowered their lost time injury frequency rates and as such considered themselves to be ?safe? operations. The consequence of these explosions has been devastating. It is not just the loss of those underground, but also to the families that have lost people in them and the broader community that has lost friends, income, business opportunities, and in many cases support and sponsorships. It begs so many questions, ?What went wrong??; ?Why were the circumstances not foreseen??; ?What could have been done to prevent it??; ?How is it that no one stopped it, reported it, fixed it etc.??. Being held accountable for negligence, should not be overlooked, however this may not aid the processes required to find all the answers. If the nature of explosions is understood, the circumstances and tools to prevent them are readily available then the occurrence and reoccurrence are due to weaknesses or inadequacies of the systems of work or in the implementation of them. This paper restates the fundamentals of gas explosions, examines the options to control the underground environment through ventilation, gas management and monitoring, education and training. Case studies have been used to examine systematic failures in ventilation management. In some of these cases it is not so much, the system that had been developed, but the interpretation and implementation of the system that resulted in the failure and subsequent loss.

Aug 1, 2013

By Thomas J. Peters

A mineral survey of the Sill Hill RARE II area (No. 5304), covering 5,200 acres (2,100 ha) of the Cleveland National Forest, San Diego County, California, was conducted by the U.S. Bureau of Mines and the U.S. Geological Survey. This survey was in conformance with the Resource Planning Act (RPA) of 1974, as amended by the National Forest Management Act of 1976, to provide mineral resource information for study area classification. Bureau of Mines personnel made an economic appraisal of mineral deposits by searching pertinent geological and mining publications as well as U.S. Bureau of Land Management, U.S. Forest Service, and U.S. Bureau of Mines files and records. Known mines, prospects, and mineralized localities were examined during 1981, and sampling and mapping were done where warranted. The Geological Survey 'did geologic mapping, geochemical sampling, and geophysical surveys to aid this study.

Jan 1, 1983

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

A discrete element computer program named DMC-BLAST (Distinct Motion code) has been under development since. 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions (2-D). DMC-BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993).

Jan 1, 1998

By K. Wongaew, R. F. Cook, J. E. Carlson, T. Cleys, C. R. Smith

Steel fiber reinforced concrete segmental rings are the final tunnel lining for approximately 85% of the alignment for a 6.706-meter (22-foot) internal diameter tunnel being built as part of the East Side Combined Sewer Overflow Tunnel Project. This paper describes the approach adopted for the design of the steel fiber reinforced concrete segments, the development of the performance criteria for the segments, and the testing program used to confirm the performance of the materials and segments in the laboratory and in the field.

Jan 1, 2007

Gangue-cemented paste backfill (GCPB), is a well-established green mining technology and significantly improves the recovery rate of mineral resources, prevents mine dynamic disasters, reduces surface subsidence, and consumes a considerable amount of solid waste. The addition of an early strength agent as an additive in cement-based materials provides several security, technical, and economic advantages. In this study, the early strength agent on the early age (3, 7 and 28 days) strength of GCPB is evaluated experimentally. The GCPB specimens have an initial sodium sulfate early strength agent concentration of 0%, 1%, 2%, 3%, and 4%, and the obtained samples were analyzed by testing for uniaxial compressive strength (UCS) and scanning electron microscopy (SEM). The test results show that the UCS of the GCPB specimens with sodium sulfate is much higher than that of the blank specimens. When cured for 3 days and 7 days, the strength of GCPB with 2% sodium sulfate increased the most, by 131% and 116% respectively. When cured for 28 days, the strength of GCPB with 1% sodium sulfate increased by 135%. Scanning electron microscopy (SEM) results showed that the GCPB with 1% and 2% sodium sulfate had better internal structure compactness, thicker acicular crystals, and more flocs. As a kind of early strength agent, sodium sulfate can react with calcium hydroxide to generate calcium dihydrate sulfate and then react with calcium aluminate; the hydration product (C3A) quickly generates calcium sulfoaluminate hydrate (AFt) needle-shaped crystals, forming an early skeleton and improving the early strength.

Jan 7, 2020

By Terry R. Neumann

During 1983, U.S. Bureau of Mines personnel examined mines, prospects, and mineralized zones to evaluate the mineral resources and potential of the Funeral Mountains Wilderness Study Area (WSA), Inyo County, California. Eleven mineral properties and two mineralized zones were examined during this study. Of these, six are within the study area and seven adjacent. There are no active mines, in the WSA, nor is there evidence of past production from any claim within the study area. The WSA contains no identified mineral resources. However, occurrences of bentonite, zeolites, and strontium were found in the area. There is little likelihood for resource development of any occurrence in the WSA. The area, in the Basin and Range Physiographic Province, is dominated by a Paleozoic marine sequence. Segments of Tertiary continental fluviolacustrine sediments, including volcaniclastic rocks, abut and overlie the Paleozoic rocks in fault controlled basin areas. Significant concentrations of bentonitic clay and zeolites occur as alteration products in Tertiary tuffaceous sedimentary rocks. However, they are generally low-grade, thin, and discontinuous, precluding commercial development. Limestone, quartzite, and sand and gravel in the area are suitable for many types of construction uses, but similar deposits outside the WSA are closer to markets. No energy resources have been identified in the WSA.

Jan 1, 1984

By C. M. F. Vieira

This work has as its objective to characterize ceramic bodies for vitrified tiles elaborated with the mixture of nepheline-syenite flux and kaolinitic clay. Formulations were prepared with 0, 30 and 50 wt.% of nepheline-syenite incorporated in a kaolinitic clay. To determine the physical and mechanical properties such as dry bulk density, linear shrinkage, water absorption and flexural rupture strength, specimens were prepared by 30 MPa uniaxial pressure-molding and then fired in a laboratory furnace at 1150oC. The microstructure of the fired ceramics was evaluated by scanning electron microscopy. The results indicated that the nepheline-syenite improved the evaluated properties of the clay and attended the specifications of vitrified ceramic tiles.

Jan 1, 2010

Variations in product distribution in the carbon-sulphur dioxide system due to variations in reaction temperature, sulphur dioxide concentration in the feed gas, and gassolid contact time were studied in detail for a brown coal char. The results were compared with those for two wood chars, a coke prepared from Liddell coal and two cokes prepared from Ac1and coal. Conditions were chosen such that gas-solid diffusion rates did not hinder chemical attack of the carbon.With brown coal char under suitable conditions, the selectivity of sulphur in the sulphur dioxide fed, to either elemental sulphur or carbon disulphide, was in excess of 90 per cent. The wood chars gave very similar product distributions Ito brown coal char. However, the cokes from Ac1and and Liddell coals were respectively approximately three and seven times less reactive than the brown coal char.The approximate carbon holdup required to just achieve total conversion of sulphur dioxide, and thereby achieve high selectivity to elemental sulphur, is given as a function of reaction temperature.

Jan 1, 1974

By Robert Lee, Jeff Corace, Rob Cyr

Blasting in the heart of the historic Byward Market District of Canada’s capital, Ottawa, presents a unique set of challenges. The obvious difficulties arising on projects requiring blasting within 3 m (10 ft) of 125 year old buildings in various states of disrepair have been encountered and successfully dealt with countless times before. The complexities increase exponentially when tenuous property boundaries, unknown structural details, litigious histories and the need for encroachment agreements lead to individuals with competing interests all able to impact the same operation. Blasting on three projects in the Market was started in early 2005 after months of negotiation. Ultimately, the potential for the projects to proceed hinged on the ability to successfully disseminate blast data to the various stakeholders. As part of the agreements drawn up, property owners demanded immediate notification of the measured vibration levels with contract provisions including clauses such that any exceedance of the USBM criteria immediately triggered project shut down and complete blasting program redesign, and approval by all parties. With stakeholders located in various cities and, in some instances, on various continents, a conventional attended monitoring strategy would not satisfy the requirements. In response to the critical reporting need, Explotech Engineering Ltd. installed unattended monitoring stations around the sites, all incorporating wireless telemetry. After each blast, data was automatically transferred from the monitoring stations to a web-linked server via the wireless network, where it was immediately available to project stakeholders through a password protected website. The solution required a unique blend of data acquisition, telemetry, database, and security technologies, all married to produce a reliable system that was easy to maintain and use. While these types of systems were originally developed for use as permanent monitoring networks in operating mines and quarries, monitoring professionals are increasingly benefiting from the technology on temporary building projects that have typically been the realm of attended monitoring strategies. Globally, this has emerged as a solution to provide more timely access to data for stakeholders, and to minimize the legal exposure from multiple violations of vibration limits. As this trend is likely to continue, the regulated vibration control industry is likely to see a continued shift in technology development to leverage wireless networks and the Internet to continue to improve data transfer, archiving and distribution.

Jan 1, 2006

By Raymond J. Castelli

The paper provides a general overview of the numerous types of earth retaining systems currently available, and organizes these various systems by several classification methods. These classifications can be used as a guide in identifying the appropriate type wall or walls for any specific project application. As a further aid in sorting through the numerous wall alternatives for a specific design or construction project application, the paper suggests a systematic approach for wall selection, and presents helpful charts summarizing the general advantages and disadvantages, and typical limitations for the currently available wall systems.

Jan 1, 2003

By S. Montes

Mineral floatability is strongly connected with mineral structure and composition. The complexity of mineral surfaces has meant that few attempts have been made to understand the effect of impurities (trace elements) on the flotation process. Zeta potential technique has been extensively used to evaluate the surface charge of mineral particles. Nevertheless, those measurements consider only an average of mineral particles surface charge. The presence of fine particles and inclusions covering a mineral may influence the local reagent adsorption process, which will ultimately be reflected in the subsequent global response of the mineral froth flotation efficiency. The current work assesses the iron oxide mineral, haematite (Fe2O3). Zeta potential and streaming potential techniques were used to determine the surface charge of fine and coarser particles of haematite. Further analysis was performed to determine the point of zero charge (PZC) of the mineral. In addition, adsorption isotherms of alkyl ammonium chloride reagents with different lengths of carbon chains were carried out. It was found haematite floatability depends strongly on the isoelectric point (IEP) value, which is affected by other mineral species present at the mineral surface. Haematite floatability became significant only at relatively high tetradecyl ammonium chloride collector concentrations (concentration greater than 4 10-4M), which does not happen with other oxides such as quartz. Unlike quartz, haematite develops a low surface charge over a wide range of pH, disabling all long-range attractive interactions between the mineral and the collector. Therefore, hydrophobic chain interaction is probably the most likely mechanism acting to promote collector adsorption and enhance further floatability. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to suggest a possible mechanism to understand the sequence of collector adsorption and the effect of trace species on it. Keywords: floatability, haematite, adsorption, electrochemistry, zeta potential.

Jan 1, 2007

By T. M. Barczak, S. C. Tadolini

Reduction in the recovery time required and improvements in safety during a longwall face move have compelled coal mine operators to examine and use pre-driven longwall recovery rooms. The recovery entry is developed at the longwall stop position and supported ahead of time so that the required combinations of standing and internal supports can be installed before the longwall face approaches. A calibrated three-dimensional finite element model, developed in conjunction with an underground test area, provided the critical components and design principals for a comprehensive parametric study. The study indicates that vertical, horizontal, and shear stresses concentrated on the outby abutment pillar corner of the recovery room resulting in deformations in the immediate roof above the primary roof support anchorage level. The results of the numerical model and field site observations indicated that the combination of the internal bolting system and the standing concrete supports are critical for the successful and safe extraction of the longwall equipment. Cable supports installed at and angle over the pillars can help stabilize the disturbed zone above the adjacent fender and outby pillars, however; standing supports are required in most sedimentary roof conditions to increase stability and assure a safe longwall extraction.

By AIME AIME

WTHIN the next month all members of the Institute will be given an opportunity to vote for a new President, two Vice-Presidents, and five Directors. All of the candidates nominated by the official committee are well known to certain groups of the Institute membership but a brief record of their professional lives will be given here for the information of those that will vote. Not since 1927, when Everette DeGolyer guided the destinies of the Institute, has a member of the Petroleum Division been a candidate for President. John Meston Lovejoy has been a Director since 1930, and a Vice-President as well for the last year: In the three years 1932-4 lie was also chairman of the Admissions Committee. Dir. Lovejoy graduated from the Columbia School of Mines in 1911, just before lie was 22 years old, and began his professional career as a copper miner at Chuquicamata. Chile. Silver and gold mining later claimed his % attention, and it was not until 1914 that lie gut into the oil business, as geologist for the Standard Oil Co. of N. Y. This took hint to China and he later worked for the company in Wyoming. In 1917 lie joined the Army where lie rose to be captain of Field Artillery. Upon his return to the United States he went to work for the Amerada Petroleum Co., of which he later became vice-president and general manager, with headquarters in Tulsa. Since coining to New York he has been president of the Petroleum Bond & Share Cu.. and is currently president of the Seaboard Oil Co.

Jan 1, 1935

By S. J. Page, R. A. Jankowski, J. A. Organiscak

The U.S. Bureau of Mines investigated the relationship of bituminous coal seam parameters and the amount of airborne respirable dust generated at longwalls. Dust and coal samples were obtained from 20 longwalls operating in geographically representative coalfields throughout the United States. Statistical analyses of coal seam parameters and airborne respirable dust measurements indicate a likely causal relationship between seam type and respirable dust. Low-ash, high-volatile coal seams were associated with higher airborne respirable dust levels. A negative linear correlation (significant at the 95-pct confidence level) was observed between the seam's ash content and airborne respirable dust, explaining up to 18 pct (R2 = 0.18) of headgate dust level variation and up to 15 pct of tailgate dust level variation. Volatile matter was found to have a positive linear correlation with tailgate dust level, explaining 16 pct of the variation. Further data examination indicates that these relationships with dust are most likely nonlinear, because of improved R2 values over the linear correlations. However, a notable portion of longwall dust production is influenced by other operational parameters, so additional research under more controlled conditions is needed to determine the seam's causative functions.

Jan 1, 1992

By Paul D. Tomlingson

During the next several months, SME’s E-Newsletter will feature 15 articles on maintenance management. The articles may be read online or downloaded and distributed within your organization. They will address maintenance management topics, offer guidelines to mining managers and provide techniques that the maintenance manager can use. The articles will stress equipment management, a strategy that the mining industry has accepted as a modern replacement for outdated maintenance practices. Equipment management is the mutually supportive interaction of all mine departments as they establish equipment needs, procure equipment, test, commission, operate, maintain, modify and eventually replace equipment. The successful application of equipment management principles can quickly and reliably produce cost reduction and performance improvement results while providing a dependable way of sustaining them. Equipment management embraces modern management techniques. These include reliability-centered maintenance, life-cycle costing, capital performance, the effective use of information and productive organizational models.

Jan 1, 2003

By R. D. Hull

Paper written on project work carried out in partial fulfilment of B.Sc. (Eng.) (Mining) degree As a partial fulfilment for the degree of B.Sc. (Eng) (mining) at the University of the Witwatersrand, a dissertation was to be completed in the mining industry. This was done at Finsch mine, with the purpose of determining the best solution to the required secondary breaking problem. In order to complete the study of the secondary blasting method available for use in the new block 4, cave mining method at Finsch mine the following problem statement was identified and solved ?The methods currently in use, for the secondary breaking of oversize rocks at their source in the current production levels, are to be investigated, and their applicability to the new block 4mining project determined?. To effectively achieve this problem statement above; time was spent researching and investigating, in depth, the methods that are currently in use at both Finsch and Koffiefontein mines; so as to gain practical knowledge of these. The methods were identified and independently evaluated, taking into consideration factors such as costs of the equipment, time to break oversize rocks, advantages, disadvantages, safety and labour requirements, etc. This in turn then allowed for a direct comparison between the methods and the decision as to the best to apply to the new block 4 production level. The methods that were investigated included: ?Concussion blasting, where concussion bombs and lay-on charges are used to break hang-ups and boulders. ?Drill and blast methods, where holes are drilled in large rocks and charged manually with explosives. ?Emulsion secondary blasting, which is a new project in use at Koffiefontein mine from African Explosives Limited. ?The Ro-BustTM breaking system, a hydro-fracturing breaking system. Once all the methods had been evaluated and compared it was found that the Ro-BustTM Breaking system was the most applicable for the breaking of boulders, with, the Emulsion Blasting System being used for hang-ups. Further information and the more in-depth version of this report, is stored in the resource centre at De Beers?Finsch Mineand the School of Mining Engineering WITS University.`

Jan 1, 2002