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By Harry R. Nicholls

The objectives of this investigation were to determine the strain propagation laws for a strain pulse in salt and to compare the seismic effects from the detonation of different explosives in salt. The investigation showed that a strain propagation law of the type, e = K(R/W 1/3 ) n, and a strain energy propagation law of the type, Ea/W 1/3 = K(R/WI/3)b , are valid in salt. A change in the regression law coefficient, n , was noted with strain level. A similar change in b was inferred because strain energy is proportional to the square of strain amplitude. Particle velocity data may be used interchangeably with strain data under the test conditions.

Jan 1, 1962

By Yin Zongze

The pile foundation of Sutong bridge pylons is an extra large pile foundation. The length of piles is 115m, and the diameter of the piles is 2.5-2.8m. Since the traditional design method may not determine the settlement and capacity reasonably for such a large pile foundation, the finite element method is used to study stress and deformation of the foundation. The interface element is set to simulate the possible slide between piles and soil layers. The hyperbolic model is taken for soils. Parameters are determined from triaxial test first, and then modified by back analysis on basis of in-situ loading test. The computation results show that the axial force of piles changes with the location of the pile. Outer piles support greater axial force and also friction. The settlement will not be greater than 26cm. The stress and deformation of the pile cap, the abutment, are obtained too. The whole foundation is safe.

Jan 1, 2006

By John B. Hastings

THE reconnaissance of the Goldfield mining-district, described in this paper, was made in May and June, 1905, and, though this time was too short for a complete report, the work accomplished may serve as a basis for more thorough future research. Dr. Berkey has examined the rocks collected by myself, and I am using his classifications. As a result of further field-work, and Dr. Berkey's examination of the rocks, this paper is an elaboration and correction of my views expressed in the Gold-field Sun, May 12, 1905. The sketch-map, Fig. 1, illustrates the geology of the Goldfield mining-district. Goldfield is an eruptive complex, consisting of alaskite (binary granite), hornblende-andesite, hornblende-dacite, rhyolite, pyroxene-andesite, pyroxene-dacite (sometimes containing, a small quantity of olivine), quartz-felsite, olivine-pyroxene-ande¬site, and basalt. Considering this list to be arranged in the order of eruption, the age-sequence of the rocks conforms to Richthofen's law, formulated in 1868. From his observations in Europe and America, propylite, andesite, trachyte, rhyolite and basalt, occurring together, succeed one another. In a general way, the medium and more acidic rocks precede the most asic-a result supposed by some to have arisen from their relative position beneath the surface, and due to a rude stratification by gravity in the original cooling magma during the older history of the earth, or to the same differentiation occurring during a quiescent (molten ?) period preceding eruption, being aided by the ease with which acidic rocks, mixed with water vapors, become fusible. In effect, the more basic and less re-

Mar 1, 1906

By Larry G. Stolarczyk

[STATES REPORT Mining Research Mine Health and Safety Research for Period Ending 30 September 1980 PROGRAM Wireless MF Communication System DATE STARTED January 1980 TPO (USBM) Robert I. Chufo (PSRC) CO ( USBM) Alan G Bolton, Jr, (Mr. Patrick Neary RESEARCH AREA Industrial Type Hazards SCHEDULED COMPLETED Phase I 29 September 1980 Phase II 29 June 1981 Phase III 29 April 1982 Subject OBJECTIVE Development of demonstration Hardware. for medium frequency mine tireless communication system.]

By P. A. Hagerty

Biological treatment of metals-impacted water using sulfate reduction is a viable means of treatment that has been applied in pilot and full scale at numerous projects. One of the fundamental challenges with this type of treatment is the selection of an appropriate substrate to support the sulfate reduction process long-term. The substrate degradation products provide a carbon source and an electron donor for metabolism by sulfate-reducing bacteria and consequently organic characteristics are critical; however, the physical attributes of the substrate are equally critical to an efficient and optimized substrate mix. This paper explores the affect of particle size (a.k.a. grain size) of several substrate mixes on the treatment efficiency of sulfate reducing treatment systems. Substrate selection can be separated into two phases of evaluation, the primary selection phase and the secondary optimization phase. The primary selection phase considers such fundamental attributes as source availability, economics, bioavailability and longevity. These fundamental activities are conducted in order to identify potential candidate ingredients of the substrate mix which are regionally available, economically viable and consistent with the biogeochemical aspects of the project. Recent work has been conducted in the development of testing protocol for organic substrates to quantify bioavailability (Martinez Hernandez et al. 2010, Place et al. 2006) as part of the primary selection phase. Once the substrate ingredients have been selected based on the primary criteria, the mixture of these ingredients is then developed based on an optimization process, including consideration of the substrate ingredient?s particle size distribution.

Jan 1, 2011

By Doug Anderson

Blast vibration seismograms are generally collected strictly for compliance with regulations. The peak levels (including dominant frequency) are typically all that are looked at. However, these records contain a lot more information about how a blast has performed. The seismogram is actually a record of explosive energy that was not used in fragmenting rock. The trick is to determine how to extract information that would be useful in analyzing blast performance.

Jan 1, 2013

By R. B. Alke

Request to Mine Beneath Bridge The Jabs Run Bridge is a reinforced portland concrete arch filled bridge located on WV Bouts 7 near Pentress, WV. The bridge has a span of 22.9 m (meters) and a height of 4 m above normal pool elevation to the underside of the center of the arch (See Pig 1). The bridge is a two lane structure with a width of 6.86 m. The structure is over 50 years old Wing been built in 1929 and is owned by the Department (WV Department of Highways).

Jan 1, 1984

By Robert L. Virta

This U.S. Bureau of Mines paper discusses the structure of the talc industry, talc production, processing of talc ore, applications and demand for talc, and the outlook for the talc industry.

Jan 1, 1989

The major copper orebody at Mount Isa is being extracted at a rate of four million tonnes per year. The method used requires an equivalent rate of back filling with (mainly) cemented fill. There were three major incentives for developing this mining system. The first was the prospect of high ultimate recovery of the orebody. The target is 100 per cent recovery. Also the proposed stoping layout appeared to offer significant advantages in development and production costs. Finally, extensive subsidence above the northern end of the orebody could have disturbed permanent surface installations and jeopardised a possible future open cut. The full implications of this ambitious strategy were not apparent in the early years. Now, after 12 years of production the benefits are being realised and they can be weighed against the costs. Probably the most interesting result which comes from this analysis is the significance of cutoff grades and dilution factors in balancing mining and filling rates.

Jan 1, 1980

By N. N. Malila, N. R. Shoko

The ever-increasing pressure on the profit margins of ferro-chrome producers and the gradual depletion of deposits of rich hard lumpy chrome ores calls for the ferrochrome industry to maximise the use of fine fractions of concentrates and friable chromite ores. Zimbabwe is endowed with huge deposits of refractory and friable ores that occur on and off the Great Dyke complex. The conventional metallurgical process of smelting of chromite ores in submerged arc furnaces is favoured by the use of refractory hard lumpy ores. The requirement to use all lumpy ore has been circumvented to a large extent at Zimbabwe Alloys. The use of briquetted chrome ore fines in the production of Ferrosilicon Chrome and High Carbon Ferrochrome has yielded positive results over a period in excess of twenty-five years. Of the three industrially used methods of agglomeration of chromite ores; sintering, pelletisation and briquetting, briquetting is preferred because the other two are associated with higher capital and operational cost. Zimbabwe Alloys has developed operational and technical expertise on the briquetting and utilisation of chromite ore fines and concentrates. Variations in the quality of available chromite ore fines imply that their amenability to briquetting is a dynamic problem. Appropriate briquetting parameters to guarantee quality briquettes are essential to the successful use of briquetted chromite ore fines. In developing a technology for briquetting of chromite ores, it is important not only to study the mineralogical and grain-size characteristics of the chromite ore fines but also to make an informed choice of the type and quantity of the binder and the conditions for producing a physically and chemically competent green and cured briquette. This paper discusses Zimbabwe Alloys' experience on the briquetting process and the advantages derived in the smelting of the briquetted chromite ore fines in comparison to the use of conventional lumpy chromite ore with respect to improvements in chromium recovery and as a consequence related efficiencies and unit cost of production.

Jan 1, 2004

By A. Lashagri

This paper presents research results on assessment of environmental impact of digging and loading equipment in surface coal mining. Environmental impact is accessed through the equipment exhaust and dust emissions, and sound level. Exhaust emission is related to carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), and volatile organic compounds (VOCs). Dust generation is expressed through the particulate matter PM10 and total suspended particulate matter (TSP), while sound is presented through the sound pressure level. Modeling of environmental impact of digging and loading equipment is conducted in Microsoft Visual Studio.NET software package. This research is a part of a boarder project on development of software system for the selection of productive, cost-efficient and eco-friendly mining systems, which is sponsored by the Appalachian Research Initiatives for Environmental Sciences (ARIES). The research work presented here may be used by mining professionals to aid in quantifying environmental impact of digging and loading equipment and determinate strategies for reducing its overall impact.

Feb 27, 2013

By J. H. Swisher

An experimental study has been made of the possible mechanisms for foam stability in the system CaO-SiO2-Cr2O3, where Cr2O3is the foaming agent. The degree of lowering of surface tension by Cr2O3 was determined at 1600 "C for high -silica melts. Measurements were also made of foam stability under standardized conditions. The results of the two sets of measurements then were correlated by applying the Gibbs and Marangoni theories of film elasticity. It was demonstrated that the Marangoni elasticity effect is probably the largest single contributor to foam stability, although the high uiscosity of' silicate melts makes some contribution in controlling the rate of drainage of liquid from bubble lamellae. ThE tendency of metallurgical slags to foam has frequently been observed during steel-refining operations. In the open-hearth furnace,this tendency is considered undesirable because it slows down the rate of heat transfer from the burners to the molten-metal bath. On the other hand, it is sometimes desirable to have a "foamy" slag in the basic oxygen converter.' A more effective blanket over the steel bath is made by a "foamy" slag, and loss in yield of metal due to splashing is minimized. In addition, a flush slag can be removed more easily in this condition. Since slag-foaming problems in the field have been attacked largely on an empirical basis, it appeared desirable to obtain a better basic understanding of the mechanism of foam stability. The experimental work was directed almost entirely toward the behavior of Cr2O3 as the foaming agent in CaO-SiO,-Cr2O3 melts. In the first stage of the investigation, the degree of lowering of surface tension by Cr2O3 was determined at 1600°C. The second stage consisted of measuring foam stabilities under standardized conditions. The two sets of experimental results then were correlated by applying various theories of foam stability. For convenience in interpreting the surface-tension and foam-stability results reported here, a portion of the CaO-SiO2-Cr2O3 phase diagram2 is reproduced in Fig. 1. EXPERIMENTAL 1) Surface-Tension Measurements. Very little information is available in the literature on the lowering of surface tension of slags by foaming agents. Kozakevitch 3 mentioned that the addition of 1.5 pct Cr2O3 lowered the surface tension of FeO slightly. In another system, some data on the lowering of surface tension of foaming slags by P2O5 were reported by Cooper and Kitchener.4 The technique used for the surface-tension measurements was the maximum bubble-pressure method,' using a single tube immersed to various depths in the melt. This method has been used extensively in high-temperature systems, such as in liquid metals, slags, and glasses.6,7 It has the advantage that the contact angle between the liquid and the tube material need not be known. The equation used for calculating surface-tension values from maximum bubble-pressure measurements is the Schroedinger equatioq5 which can be written as follows:

Jan 1, 1964

By Kenneth Maas

The Bureau of Mines devoted portions of the 1987-1988 field seasons to investigate the mineral aggregate industry in Juneau, Skagway, Haines, and Gustavus, Alaska, as part of the Juneau Mining District study. Statistics compiled for current suppliers include location, activity, reserve estimates, expected mine life, and types of commodities available. Each population center, except for Gustavus, is well endowed with suitable mineral aggregate to last at least 20 years. The Bureau of Mines quantified the mineral aggregate resource in many large potential sites within each area. Sampling, engineering and soil-index testing, site descriptions, deposit dimensions, and gold recovery information is described. Refraction seismic studies performed at three localities revealed gravel thicknesses in excess of 40 to 80 feet. In the Juneau area the Herbert/Eagle Rivers outwash area, East Fork Lace River. Antler/Gilkey Rivers, and Grizzly Bar (Taku Inlet) individually contain in excess of 60 million yd3 of excellent-quality aggregate with minor accessory gold credits. Haines is also well endowed with aggregate resources; large, quality deposits occur along and at the confluences of the Chilkat, Katzehin, Klehini, Tsirku, and Kicking Horse Rivers. Large deposits of granitic aggregate exist in the Skagway River and East Fork Skagway River.

Jan 1, 2012

By André Desbiens, Jocelyn Bouchard, René del Villar

"The metallurgical performance of the column flotation process is determined by the concentrate grade and recovery. Although the former can be continuously measured using an on-stream analyzer, the latter must be estimated by a material balance calculation based on seldom verified steady-state assumptions. Consequently, the automatic control and optimization of flotation columns should be performed using secondary variables having a strong influence on the metallurgical performance, such as froth depth, gas hold-up or bubble surface area flux and bias. The aim of this paper is to present a model-based automatic control strategy using froth depth and bias measurements obtained from virtual sensors developed at Laval University. Preliminary pilot plant results on two-phase (water– air) and three-phase system (water – minerals – air) will be presented and eventual industrial implementation of such a strategy as well as the possibility of achieving effective real-time optimization from bias and froth depth measurements will also be discussed.INTRODUCTIONFlotation columns have been widely studied and used in mineral processing for about twenty years. Although a great deal of work has been accomplished to understand the influence of different variables such as froth depth (H), bubble surface area flux (Sb) and bias (Jb) on the metallurgical performance, the measurement of some of these variables is still difficult to be performed – except at the laboratory level – because in most cases, no commercial device yet exists.As a result of this, it is almost impossible to achieve neither efficient control nor optimization of the process at the industrial level, even in open-loop operation. This paper aims at presenting a simple control strategy of froth depth and bias. Description of the sensors used to achieved measurements, preliminary pilot plant results for froth depth control, eventual industrial applications and possibilities for process optimization are also treated."

Jan 1, 2003

By Thomas J. Albin

U.S. Bureau of Mines research has found that maintenance of surface mining equipment is involved in slightly more than one-third (34.1 pct) of all surface mining accidents. Two groups of machines, haulage trucks and power shovels, accounted for over one-half of all surface mining mobile equipment maintenance accidents in 1978-84. Maintenance work-time histories for these machines were compared with accident records to identify the most hazardous-to-maintain systems within the machines. Recommendations to reduce the accident risk associated with maintenance of these hazardous systems are presented.

Jan 1, 1990

By R. A. Welsh

The Bureau of Mines has developed a photoelectric concentrator apparatus which is capable of collecting incremental products from the discharge of wet concentrating tables. The instrument uses photoelectric cells as sensors to differentiate between two products which have differences in color or reflectivity. The photocells provide a signal that controls a mobile splitting device that separates the products. Tests conducted on a wet table demonstrated the ability of the apparatus to separate a product containing 81.5 percent pyrite from a lower-grade product containing only 68.8 percent pyrite. The photoelectric concentrator should have a broad application for collecting concentrates with visible color or reflectivity differences from wet concentrating tables.

Jan 1, 1972

By J. G. Kirby

The total number of petroleum refineries in the United States continued to decline during 1950, and according to the Bureau of Mines annual refinery capacity survey there were 357 refineries January 1, 1951, compared with 367 a year ago. The total throughput capacity increased 267,344 barrels daily during the year to 6,963,644 barrels daily as of January 1, 1951, continuing the trend of the past several years to increase the throughput capacity of the refineries and decrease the number of plants. The capacity of the average refinery to process crude oil increased during 1950 from 18,246 barrels daily to 19,506. The Indiana-Illinois refinery district accounted for 110,175 barrels, or 41 percent of the total crude-oil capacity increase, the Oklahoma-Kansas district, 17 percent, the California district, 14 percent, the East Coast district, 13 percent, and the Louisiana Gulf Coast district, 12 percent. Slight declines ill crude-oil capacity were reported in the Texas Inland, Texas Gulf Coast, New Mexico, And Appalachian refinery districts. The 160,100 barrels of additional crude-oil capacity that was building January 1, 1951, represents an increase of 10 percent over the year earlier figure. The only completely new refinery listed as under construct ion at the beginning of 1951 is located at Superior, Wisconsin. Other new construction involves enlargement of existing refineries. Plans for at least five additional new refineries are under consideration, and construction is expected to begin during the current year.

Jan 1, 1951

By R. C. Courtney, D. J. Forrester

Modern advances have led to sweep and multibeam bathymetric surveying techniques that yield three-dimensional images of the sea floor and have also produced high-powered personal computers with which to control the data and analyse the results. At Sydney, in Nova Scotia, the topography of the sea floor over the longwall workings was observed before and after mining with a precision echo-sounder in 1987-89, with sweep bathymetry in 1993 and with multibeam bathymetry in 1994-95. The results of the latter programme produced what was probably the first observation of a complete three-dimensional subsidence trough over a longwall panel 2 500 m x 168 m. The subsidence has been quantified to a sufficient degree of accuracy to allow simple trend analysis, which has shown that the pattern and shape of movements are similar to those found elsewhere but with significantly smaller maximum subsidence. A prediction model has been calibrated

Jun 19, 1905

By Will H. Coghill

This paper on milling methods and costs at a flat river (Mo.), mill is one of a series of information circulars on milling methods and costs which is being prepared by the United States Bureau of Mines, The mill under consideration treats 5,000 tons of load ore daily by table concentration and flotation. It is 25 years old, and yet it is a new mill. Research has been in continual progress at the plant since its beginning, and accordingly a day never passes without a record of change for advancement. The changes have been so orderly that no evidence of obsolete equipment remains.

Jan 1, 1932

By Yijun Caoa, Xiuxiang Taoc, Zhongbo Hub, Yinfei Liaoa

A new preparation scheme for a difficult-to-float coking coal from the Kailuan Mine, Tangshan, China was investigated. The results showed that grinding followed by column flotation was beneficial for obtaining products with low ash content. The positive effect of grinding on the coal floatability is attributed to the liberation of intergrowths and coal surface improvement. Tests indicated that 10 minutes was the optimum grinding time, and over grinding resulted in a deterioration in flotation performance. With a grinding time of 10 minutes, conventional flotation had potential to yield a product with around 12.42% ash content and 69.15% combustible recovery. Column flotation can reduce the product ash content to 11.15%and increase combustible recovery to 74.47%. Consistently better flotation results reveal that column flotation is more efficient than conventional flotation for such fines.

Jan 1, 2015