Search Documents

By George S. Rice

"INTRODUCTION During the past 4 or 5 years the frequent occurrence of bumps in coal mines of the Cumberland field, in Harlan County, Ky., and Wise County, Va., has caused much apprehension among miners and mining officials of that region.These bumps have caused many deaths and injuries, and have been increasing in frequency. Eight men were killed and a number injured by bumps in the first 4 months of 1934. Their unpredictable occurrence and the usual absence of any preliminary warning tremors or sounds, such as ordinarily precede a large fall of roof, cause fear of other bumps and impair the morale of mine workers.Acknowledgments This report on bumps in coal mines of the Cumberland coal field of Kentucky and Virginia is based on an investigation made at the urgent request of .the Harlan County Coal Operators Association, through James F. Bryson, director of safety of the association, to the Director of the United States Bureau of Mines, following a series of disastrous bumps in. Harlan County, Ky., and Wise County, Va. The request was granted and the writer detailed to undertake the investigation, which was made in June 1934.The officials of certain operating companies in the Cumberland field gave every facility for examining the conditions accompanying bumps in their mines. The writer is most grateful to them for the courtesies shown; to J. F. Bryson, to J. F. Davies, district engineer, Safety Division, U. S. Bureau of Mines, who accompanied the writer throughout his trip to the vari¬ous mines and gave him much assistance and detailed information regarding the occurrence of bumps; and to Dr. David White for reviewing the geological descriptions,Definition of Bumps ""Bumps"" are phenomena comparatively rare in the coal fields of the United States and, for that matter, in the coal fields of the world, because for their occurrence certain exceptional natural conditions are required strong, massive strata of sandstone or conglomerate above the coal and a fairly strong floor, as will be described in detail later."

Jan 1, 1935

By Rudolph P. Frizzi

Quality control is essential for augered cast-in-place (ACIP) piles (also known as continuous flight auger (CFA) piles outside the United States) and augered displacement (AD) piles since the pile is constructed below the ground surface out of the direct sight of the personnel constructing and inspecting the pile. ACIP piles are being successfully constructed to support high-rise structures, arenas and stadiums, mass transit systems, and power and industrial facilities. The use of AD pile technology is also gaining ground in the United States, typically utilizing proprietary systems such as Omega (currently utilzed by Richard Goettle Inc., and LG Barcus and Sons, Inc.), Berkel, and DeWal (currently utilized by Morris-Shea). Different types of ACIP/AD pile installation equipment are shown in Figures 1 and 2. ACIP piles are installed into granular and cohesive soils, and soft rock to lengths currently approaching 130 ft (39.5 m), with diameters up to 24 to 36 inches (610 to 915 mm), and sustaining design loads approaching 900 kips (4000 kN). Current AD pile installation equipment in the United States is capable of installing up to 79-ft-long (24 m) piles with diameters ranging from 12 to 18 inches (305 mm to 460 mm).

Jan 1, 2002

By Bryan A. Bartley

"Jim Macdonald was promoted from Waterworks Engineer to Streetworks Engineer for the Wellington City Council. He thus took over the City quarry and responsibility for its performance. The crushing plant needed upgrading and he thought it would not be difficult to make a crusher to overcome a problem. If he had a longer association with the quarry industry he would have used conventional methods and equipment, so his invention arose from a fresh view of crushing.He invented the Barmac Rotopactor after observing a wear resistant chute with a lining of dead stone trapped above a piece of angle. This idea led to a rotor lined with trapped stone, rotating on a vertical spindle. In trying - a model rotor he observed the impact against a circular rill of stone in half an oil drum and thus was started a very fertile new area of developement in comminution. The writer helped in the developement and shares in the patents. Jim died in January 1982, just as the machine was becoming known and some 200 were in use in various countries. Most were working in hard rock quarries et that time but recent uses have carried the machine into the mining and mineral processing field. This paper is directed at that industry."

Jan 1, 1985

The analysis of in-mine grounding systems began with an extensive literature search which is still in progress. About a dozen articles have been found which deal directly with grounding problems on low voltage power systems or mine power systems. These systems have special grounding problems because normal load currents can be nearly as large as many types of fault currents. Information has been collected on the influence of cable spacing) conduit geometry, location of nearby conducting structures, etc., on the magnitude and path of fault current. Many other articles have been found which are less directly related to mine ground system analysis. The in-mine ground system analysis team has also inspected portions of two mine power systems to become familiar with the practices used in grounding. One electrical engineer and several other mine personnel have been interviewed concerning mine power system grounding practice. Already several aspects of the mine grounding system have been marked as requiring special attention.

Jan 1, 1975

By John C. Edwards

A computer program, developed for the Bureau of Mines under contract, predicts in a quasi-steady-state approximation the ventilation and contaminant concentrations and temperatures when a fire occurs in a multi-level mine. For periods of time in which there is no significant change in the ventilation, yet a fire is producing fumes, a real-time fume concentration throughout the mine is calculated. Multiple and time-variable contaminant sources can be simulated. Recirculation paths that can develop provide a mechanism for increasing the fume concentration in the mine network and are identified by the computer program. This report contains a listing of the Fortran computer program as well as the required format of the input data. Two examples are provided of the real-time spread of smoke from a fuel-rich fire throughout a multilevel mine. The first example considers an operational exhaust fan as well as a booster fan. The second example evaluates the real-time smoke spread following a failure in the exhaust fan; recirculation occurs in this latter case.

Jan 1, 1982

By T Wambeke, J Benndorf

A risk-robust development of a heavy mineral resource requires an assessment of the geological uncertainty and spatial variability of the key factors impacting the mining and processing operation. Attributes of interest are the total heavy mineral grade, the slime content and the amount of oversized particles. The modelling of a mineral sand deposit presents two main challenges. Firstly, the exact location of the geological boundaries are obscure due to the complex interaction of the deposit formation processes. Secondly, the properties of interest exhibit a rather complex transitional behaviour across the so-called soft boundaries. Traditionally, the modelling exercise is restricted to a consecutive stochastic simulation of distinct geological facies and orebody properties. This results in different zones separated by hard boundaries, ignoring the typical transitional behaviour.This contribution presents an alternative approach which models the entire sand body as a single domain while accounting for the complex trends present. Error curves are used to infer covariance model parameters without the need of a prior removal of the trend. The principle is based on minimising the differences between empirical and theoretical errors resulting from two methods of prediction calculated for different rings of influence. The added value results from the unambiguous decomposition of the spatial variation into a deterministic trend and a stochastic residual. The trend model neither overfits nor underfits the data. The calculated residuals are thus unbiased and the uncertainty can be correctly assessed.The effort results in a characterisation of the resource uncertainty which provides a more realistic image of the spatial variability of the key properties in and across the geological domains of an existing heavy mineral sand deposit.CITATION:Wambeke, T and Benndorf, J, 2014. Optimal inference of modelling parameters to simulate complex trends across soft boundaries – a case study in heavy mineral sands, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 73–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By A. Baldwin

Reports technical progress in designing four machines to be used in mining coal underground, applying innovative concepts at the design stage (instead of add-ons). A study phase was followed by design activity, including calculations supporting the designs. Scale models of three machines were built, and a full-scale mock-up of the conventional loader was used to measure human factors parameters.

Jan 1, 1976

This modern plant consists of a battery of 72 Otto Wilputte Compound Under-jet Ovens with extensive plant for the recovery by-products. The ovens produce 9000 tons of furnace coke per week together with some 17,000,000 cub. ft. of coke oven gas, which is used for heating purposes throughout the works and for heating the ovens.Coal is supplied from the, company's colliel'ies and is stored under a Coal Handling Bridge of 264 ft. span and 365 ft. overall, capable of handling 250 tons per hour. The coal storage space of 1600 ft. can. be extended to a maximum of 2800 ft.Preparation of the coal for coking involves fine grinding which is carried out as follows:-Coal is dumped from rail waggons on to a conveyer belt which delivers it to a 12 ft. x 22 ft. Bradford Breaker, with a capacity of 400 tons per hour. The coal, then approximately 4 in. in size, passes, to the mixing bins; and after careful blending is reduced in the,hammer mills to a fineness suitable for the ovens.The fire coal is elevated to the main storage bin over the battery for subsequent charging by electric larry car. The average cokingtime is 15 hrs. 36 mins. At the end of ,this period the doors, are removed and the coke pushed from the oven by a mm. The coke, is, then quenched with fresh, water and sent to the Blast Furnace in 50-ton Copper Waggons.The gas is exhausted from the ovens by Brown Boveri turbine, exhausters of 23,000. cub, ft, per min. capacity. Exhaust steam from these is used for various. purposes in the By-Product plant. After removing the last traces of tar by Electrostatic Precipitators', the gas is bubbled through sulphuric acid, the ammonia forming ammonium sulphate, which is subsequently washed, dried and bagged for sa,le as a fertilizer. The gas then goes to the Benzol Scrubber Towers, where benzol and other derivatives are recovered and later redistilled and purified. The cleaned gas is then piped to the main works for heating purposes, being used with tar to fire the steel furnaces, and also the soaking pits and reheating furnaces.BLAST FURNACES.The company is at present operating two Blast Furnaces of 800, and 1000 tons nominal daily capacity respectively. The latter was...

Jan 1, 1938

By A. W. Fahrenwald

As an aid to studies of grinding, a batch laboratory classifier and elutriator has been developed at the U. S. Bureau of Mines Metallurgical Field Office at Moscow, Idaho, in cooperation with the University of Idaho. It is designed for use in conjunction with other batch laboratory apparatus, such as ball mills and flotation machines. It is shown in Figure 1. Description and Operation of Batch Laboratory Classifier The classifying column is a cylinder 4 feet 2 inches long, of 5 3/4-inch inside diameter, and terminates at its top in a cone or funnel 18 inches in diameter at the overflow elevation. The pressure chamber is of the same diameter as the classifying column, and has a conical bottom; it is provided with two openings, one in the cylindrical portion through which water is admitted, and the other, a small drain hole, in the apex of the conical bottom. The two compartments are bolted together and communicate with each other through the medium of a constriction plate provided with 3/16-inch holes spaced 1/2 inch apart. Constriction plates having any other percentage of opening may be substituted as the needs demand water is admitted to the compartment below the constriction plate at constant pressure. The volume of eater admitted is controlled with a valve. It should be mentioned that the classifying column at the bottom, just above the constriction plate, is glass.

Jan 1, 1929

By M. Maleki

Variogram analysis and kriging lack robustness in the presence of outliers and data with long-tailed distributions, which often arises when estimating grades in precious metal deposits. The capping technique, consisting of truncating the data to some top-cut grade, is widely used in order to mitigate the influence of the values in the upper tail of the distribution. However, this procedure omits part of the grade variability and is likely to provoke a bias in the estimates. To avoid these issues, a recently proposed approach is to decompose the grade of interest into three components (the truncated grade, a weighted indicator above the top-cut grade, and a zero-mean residual) and jointly estimate the truncated grade and the indicator by cokriging. This approach is attractive as it provides unbiased grade estimates, allows choosing the ?optimal? top-cut value, and essentially works with truncated and indicator data, thus avoiding the use of outlying values for calculating sample variograms and performing spatial interpolation. This work presents an application of this approach to a disseminated gold deposit that has been identified through exploration drilling. The effect of using an indicator covariate is assessed through leave-one-out cross-validation, by comparing the grade estimates with the true grades and with the grade estimates obtained with the conventional capping approach, which considers only the truncated grade as the variable of interest. As a result, cokriging the truncated grade and the indicator above top-cut grade outperforms the conventional capping approach, yielding significantly more accurate estimates. A few complementary guidelines are provided for validating the model hypotheses and for the implementation of cokriging.

Jan 1, 2014

By David R. Beadman

This paper discusses how modern techniques of design and construction were used to create the deep stations for the Copenhagen Metro. The deep stations are located in small squares within the city adjacent to many old and sensitive buildings. The architectural design provides a large open atrium to allow natural light to reach the column free platforms to give the citizens of Copenhagen a feeling of safety and security and encourage them to use the Metro. The design and construction contract was undertaken using the relatively new and untried Eurocodes. The resulting stations set new standards of design for underground metros and have pushed forward the frontiers of what is appropriate construction practice to protect the existing and enhance the future environment.

Jan 1, 2000

Jan 1, 1970

By John R. Zelonka

Models made by encasing strain-gage networks in epoxy are described and evaluated. With this technique relatively complex models can be constructed in which any number of gages can be located and alined precisely. Although the gages are an integral part of the model matrix, they create no important mechanical or thermal stresses. Model construction techniques and experimental data proved reproducible and reliable. In addition, the sGlution obtained with these models to the problem of the state of stress around a circular hole in a plate subject to a plane stress condition was in agreement with theoretical, photoelastic, and finite-element solutions.

Jan 1, 1970

By E. P. Youngman

The Siamese mining lew, which is cited as "The Sian Mining Act, 2461 (1919)," was enacted February 14, B. E. 2461 (A. D. 1919), corresponding to the ninth year of His Majesty's reign. This act replaces the Sian Mining Act of 1901 and repeals all edicts, decrees, laws, rules, and local customs relating to mining the terms of which are inconsistent with the new law. It shall in- clude all subsequent alterations or additions, as well as all rules issued by the Minister (of Land and Agriculture) already in force or to be brought into force publication in the Government Gazette to be deemed sufficient notice of any modifications or alterations. (Art. 1, 2, 5, 83, and 85.) Legislation passed recently amending certain provisions of the mining law for the purpose of controlling the sale of minerals is the mining amendment act, B. E. 2474, given August 21, 1931 (7th year of the present reign), which repeals provisions of the mining act, B. 3. 2461, and also all rules and regula- tions relating to mining that are inconsistent with the amending ect. Under article 25 of the mining amendment act, B. E. 2474, ministeriel regulations (of the Minister of Agriculture) were issued August 21, 1931. Further recent legislation, brought about by the agreement of the Siamese Government to become a party to the international tin restriction scheme (inter- national tin pool), is the tin and tin ore restriction act (Siam), B. E. 2474, which came into force on September 1, 1921, its purpose being to suspend the

Mar 1, 1933

By R. J. Snoby, M. A. Short, A. Jungmann

In processing coal, the low concentrate value requires high capacity production and sharp classification/separation techniques to reduce specific production costs. The allflux separator meets these criteria with a unique two-stage design. Through a combination of rising current and fluidized bed technologies, the allflux has extended the state of the art by expanding the particle size range that can be efficiently processed. Using concepts that have proven successful in processing concrete sands, small-scale industrial testing with coal feed stocks looks very promising. Attractive applications for the allflux are projected in fine coal recovery from old settling ponds or as a retrofit in existing fines circuits.

Jan 1, 2001

By Yunnen Chen

In the present study, waste materials like pine sawdust and spent grains were investigated to assess their potential for removal of cobalt ion from water by the process of biosorption. The effects of solution pH, reaction time and initial concentration were studied in batch experiments. The removal efficiency of Co(? ) by spent grains was higher than that of pine sawdust. The initial removal was rapid and equilibrium was established in less than 90 min. Equilibrium data all agreed well with both Langmuir and Freundlich isotherm models for the two metal-biomass sorption processes. Good correlation coefficients were obtained for the pseudo second-order kinetic model. Pine sawdust and spent grains were shown to be promising biosorbents for Co(? ) removal from aqueous solutions.

Jan 1, 2010

By J. A. Bakken, M. Tangstad, P. A. Eidem

In the submerged arc production of ferromanganese, sillicomanganese and ferrochromium, the coke bed characteristics play an important role. The basic mechanisms of electric current conduction in the coke be dare not yet fully understood, but important parameters are the material resistivity of coke and the contact resistance between the coke particles. Preliminary tests indicate that the contact resistance is of great importance to the bulk resistance of the coke bed. An apparatus measuring the material resistivity and contact resistance of carbon materials has been developed. Both graphite and industrial coke have been tested. The material resistivity tests were performed on single particles to ensure that the effects of pores and cracks were included and the contact resistances were excluded. Two geometries were tested to obtain the contribution of the contact resistance to the total resistance of two connecting particles. The tests were performed in an inert atmosphere at temperatures and current levels found in industrial submerged arc furnaces. The results show that the method has a satisfactory reproducibility. It was found that the contact resistance is about 10 times higher than the resistance of the material when two particles are in perfect contact and that the resistivity of SSAB coke is more than 10 times higher than that of the graphite at room temperature, but with increasing temperature the difference decreases. For SSAB coke the general trend is that both the resistivity and the contact resistance decrease with increasing temperature.

Jan 1, 2007

By H. Sato, B. Thornton, K. Nishi, A. Usui

"Northwestern Pacific submarine seamounts are believed to be future marine mining areas of ferromanganese crusts, which contain hi-tech industrial metals, such as Co, Ni, Te, Ti, Pt, and REEs. The Takuyo No. 5 seamount is a member of the Cretaceous super-plume seamounts in the north Pacific, located within a Japanese EEZ (100 nm from the Minami- Torishima Is. or Marcus Is.), and only 300 nm away from the Japan’s Licensed area for exploration of Co-rich ferromanganese crusts under the ISA. This is an on-going program supported by independent academic communities but not a state-run program or managed by private funding.We have observed, sampled, measured, and analyzed the occurrences, distribution, physical properties, and microbiological environments at a selected flat topped seamount named Takuyo No.5 as a model area for scientific study of ferromanganese crusts within the Japanese EEZ. We then characterized crust structures, composition, age, and growth history, resulting in an understanding of the overall nature and distribution of these deposits from wide range of areas, water depths and geological environments. The study started with a ROV (Hyper-Dolphin 3K of JAMSTEC) exploration jointly with universities and national institutions (Japan Agency for Marine-Earth Science and Technology, Japan Oil, Gas, and Metal Exploration Corporation, and Geological Survey of Japan) in 2009 using marine geology vessels, remotely-operated vehicle, an oceanbottom drill machine, deep-tow TV camera, as well as conventional dredges and corers. We have been studying the topography, geology, nature of the bottom material of the seamounts using delicate sampling devices and measurement tools, and characterized the distribution patterns of the metal-rich ferromanganese deposits from chemical, mineralogical, and microbiological points of view."

Sep 1, 2014

By Amanda Elioff

Success of the Gold Line Eastside Ex-tension rail tunnels in Los Angeles, CA has prompted the Los Angeles County Metropolitan Transportation Authority?s (Metro) planning new rail lines to include underground alternatives. The Westside Extension Transit Corridor alternatives include up to 27 km (17 miles) of subway to be constructed in soft ground. The routes will require construction in Los Angeles? ?potential methane zone,? which was not considered for subway construction until recently. Slurry face tunnel boring machines (TBM) will likely be specified.

Jan 1, 2009

By Andrew G. Martin

In 1991, Modular Mining Systems began marketing a Slope Monitoring System (SMS) now installed at twelve mines. The SMS uses automated wire line extensometers to monitor field conditions frequently. Every few minutes, the slope displacement values and current temperature are transmitted to a central computer via a packet radio telemetry system. The desktop workstation receiving the data continuously provides updated displays of active slope monitors and generates audible and visual alarms if movement exceeds user specified thresholds. The computer system also generates numerous graphs and reports for quick analysis of slope stability. This work describes the functionality of the SMS, details improvements to the SMS hardware and software developed for several clients, outlines different installation techniques needed for wall rock and spoil monitoring, and interprets slope movement data using illustrations of stable and unstable conditions.

Jan 1, 1996