Search Documents

By D. M. Walters

To achieve safe and healthy working conditions in shaft sinking operations, ventilation, and where necessary cooling, must be provided. These requirements are considered for sinking vertical, sub-vertical and decline shafts. Regulatory requirements, determining air volumes and amount of cooling required, the various ventilation methods used such as force, exhaust, twin columns, air reversal using four gate systems and the equipment required to achieve this, are discussed. Consideration is also given to the sinking of single and twin declines using diesel equipment, calculating the air volumes required to dilute pollutants and the various methods for achieving this. Also discussed is the importance of having early ventilation design input to the overall design of the mine. In many cases ventilation can be the prime determinant for the size and configuration of the shafts or declines that have to be sunk.

Jan 1, 2009

By J Cahill, D Holden, R Stuart, G Cryan, W Power, W Stratford, S Garwin

The combination of Stage 1 Geoinformatics legacy data intervention processes with the Stage 2 ultra-detailed airborne geophysical prospecting demonstrates a new approach to converting data to information to knowledge, and converting that knowledge into exploration results.   The Coromandel region of the North Island of New Zealand has long been know to host gold deposits of economic viability (Hauraki Gold Fields). To the SE of this area lies the Taupo Volcanic Region (TVR) where the geology and structural setting mirror the Hauraki Gold Fields, however mineral exploration in the past has been hindered by the blanketing volcanic ash deposits. Glass Earth Limited recognised that this whole potential epithermal gold province could be effectively explored utilising rapid, risk orientated processing to review legacy geoscience data: The Geoinformatics Data Intervention Process; which in turn directed ultra detailed airborne geophysical surveys over the TVR. Results have outlined 21 new drillable potential epithermal gold targets; and a plethora of other targets with high prospectivity.

Jan 1, 2005

By Dwight L. Sawyer

To provide technology that can help decrease the dependence of the U.S. aluminum industry on imported bauxite, the main ore of aluminum, the Bureau of Mines is investigating the extraction of aluminum from abundant domestic reserves of kaolinitic clay. Miniplant studies of the continuous leaching of calcined kaolin with boiling 25-pct HC1 acid resulted in a 93- to 99-pct extraction of the acid-soluble alumina in the calcined kaolin feed. Data are presented for an acid leaching study carried out in three or four continuously stirred tank reactors (CSTR) in series, feed rates of 100 to 250 lb/hr of calcined kaolin, and total nominal residence times of 0.7 to 2.3 hr. A material balance for a 176-lb/hr calcined kaolin feed rate in a circuit consisting of three reactors, four classifiers, and five thickeners is given. Data provide detailed compositional and physical information for calcined kaolin, process liquors, and acid-leached residue solids.

Jan 1, 1983

By L. Mabiza

Keywords: Pyrometallurgy, furnace, sulphur, SO2, off-gas, Zimplats Zimplats embarked on an off-gas sampling campaign in December 2009 to characterise the concentration of SO2 in the off-gas from their 13 MW furnace. In excess of forty isokinetic samples (US EPA Method 8) were taken over seven days. The aim of the sampling campaign was to increase the understanding of factors that influence sulphur release from sulphide concentrates in an electric furnace. Specifically, detailed monitoring was conducted over various operating conditions to evaluate: ? The relationship between SO2 and feed rate (i.e. furnace power) ? The relationship between SO2 and ingress (i.e. furnace freeboard pressure) ? The impact of concentrate bed thickness on SO2 (i.e. blacktop) ? The effect of events such as tapping and converter slag return on SO2 ? The desulphurization reactions that take place in the blacktop A model was developed to predict the SO2 content in furnace off-gas for a particular set of operating conditions. In order to evaluate the impact of random, uncorrelated changes in concentrate composition, ingress and power (feed rate) on the SO2 content of the off-gas, a Monte Carlo approach was adopted whereby concentrate composition, power, and ingress were allowed to vary randomly around selected set-points. The model is primarily based on the release of ?labile? sulphur from the partial thermal dissociation of sulphide minerals with an over-stoichiometric sulphur content (e.g., Fe7S8 decomposition to FeS and S). The main findings of this work suggest that labile sulphur does not fully account for the measured SO2 content of the off-gas, and that limited oxidation of sulphides during melting also contributes to the SO2 content. Details of sulphide oxidation reactions in the furnace remain unclear, and it is currently not possible to provide a theoretical framework for the relationship between the extent of oxidation and variables such as temperature, gas composition, particle size, and residence time in the furnace black top. Through the use of the Monte Carlo model it was, however, possible to constrain the extent of sulphide oxidation to about 1%. This work has shown in practice what was expected in concept, that SO2 in off-gas is proportional to furnace power and ingress rate. The model that was developed consistently slightly under-predicts the quantity of SO2 generated. It also highlights that more work is required to better understand the analytical methods used to analyse for SO2 in off-gas.

Jan 1, 2011

By James C. Barker

A uniquely mineralized area extends from northwestern Canada through Alaska into eastern Siberia. Some of the metals found there are relatively rare in the conterminous United Stales. Among these are cobalt, the platinum-group metals, and chromite. Geologic evidence suggests that cobalt and the platinum-group metals may be present in deposits that could constitute nationally important reserves. Chromite in potentially minable deposits is known, but it may be relatively less abundant. Limited reserves of these metals have been delineated, but most of the favorable terranes and reported occurrences throughout the vast expanse of Alaska remain unexplored. As part of the mineral studies mandated under the Alaska National Interest Lands Conservation Act, the Bureau of Mines' Alaska Field Operations Center and the Bureau's research centers at Albany, Oreg., and Reno, Nev., are cooperating in a long- range program to investigate occurrences and delineate reserves of cobalt, the platinum-group metals, and chromite in Alaska. Studies of other critical and strategic minerals will be phased in during succeeding years, as ongoing projects are completed. This first in a series of annual reports summarizes available information about deposits and past production of cobalt, the platinum-group metals, and chromite, and describes current and planned Bureau investigations of these minerals.

Jan 1, 1981

Thermal method of diagnostic as a nondestructive monitoring is based on data logging of infrared radiation from heated surface or from the associated thermal field. Monitoring of gearcases and motors hidden faults, such as, bearing degradation (deep-seated wears and tears, fretting wear, spalling and jamming solids of revolution) is closely related to high variations in temperature. The use of portable thermal imaging devices provides considerable advantages due to: easy remote access to the unit under test even when it is operating; minimum time required to obtain information and an opportunity for a real-time diagnosis of the tested subject's condition.

Dec 6, 2010

By J. Brian Anderson

Jointed micropiles were investigated to support bridge foundations where shallow rock was present. In this application, micropiles would have some amount of unsupported length, and would be subject to nominal lateral loads. Five lateral load tests were conducted on micropiles to demonstrate the impact of casing joints and rock socket embedment on lateral behavior. Load tests were simulated with FB-Multipier, a hybrid-finite element program for analysis of deep foundations, for proper design of the loading apparatus and instrumentation. The micropile sections were 2 m (6.56 ft) long, 273 mm (10.75 in) in diameter, 13 mm (0.5 in) thick walled, with a 50-mm (2-in) long threaded joint. Micropiles were made of one to three casing sections and were embedded 0.3, 0.6, 1.5, or 3.0 m (1, 2, 5, or 10 ft) into rock. In each test, two identical micropiles were pulled together using a simple frame until the weaker pile failed. All micropiles were instrumented with inclinometer casings while two contained strain gages at 0.76 m (2.5 ft) intervals. Load and displacement were measured at the pile heads. Tests showed the embedment of 0.6 m, 1.5 m, and 3.0 m (2 ft, 5 ft and 10 ft) sufficiently carried lateral loads over 180 kN (20 tons). The piles embedded 0.3 m (1 ft) were not able to maintain lateral load. In general, all micropiles tested to failure exhibited a brittle failure mode where there is small lateral deflection followed by a sudden failure at the casing joint. This was demonstrated in three of the load tests. In most cases, the micropiles were stiffer and stronger in the load tests than originally predicted numerically. The final test, where piles were not loaded to failure, verified that embedding vibrating wire rebar strain meters in the grout captured the bending moment profile of the micropile. The results showed the maximum moment in this case being carried directly across the threaded joint as predicted by the preliminary models. The results of these tests were used to calibrate the FB-Multipier numerical model. Using a load test that included bending strain measurements for a match, the soil properties were adjusted to produce reasonable matches for all of the load tests.

Jan 1, 2011

By G. K. Jorgenson, S. H. Chung

"IntroductionThe SABREX Blast Modelling Program was developed jointly by the companies of the ICI Explosives Group, of which C-I-L Inc. is a member. SABREX (Scientific Approach to Breaking Rock with Explosives) is a modular computer program which incorporates new technology with a number of tested programs that have been in use world wide.SABREX predicts the performance of blasts in terms of (I) fragment size and distribution; (2) muckpile profile and face velocity; (3) grade fracture; (4) collar breakage; (5) a rupture envelope which depicts crack penetration behind and beneath blastholes; and (6) a complete cost analysis including explosives, drilling and accessory costs. The predicted blast results are displayed as dynamic colour graphics and in tabular form.SABREX uses data on the detailed geometry of the drilled and loaded pattern, detonation characteristics of the explosives and the dynamic properties of the rock to generate blast predictions. SABREX blasting calculations take into account the effects that shock and quasi-static pressures exert on the rock around the blastholes. While physical effects occur very rapidly in rock blasting, it is possible to view and model the sequence of events as discrete sections.The program can be run on a microcomputer and is currently operated by C-I-L technical service staff in Canada for the use of drilling and blasting operators.Figure I is a diagram representing the modules of the program and associated technology that is used to complement the program.Any, or all, of the modules may be used in a particular study or blast optimization. Because the BOBCAT module of the SABREX program has been described in previous papers(7.8.9), this discussion will concentrate on the newer modules: CRACK, HEAVE, RUPTURE ENVELOPE and to a limited extent, KUZ-RAM, which present a more detailed picture of the blasting process.Each of these modules is discussed in terms of the information they offer the operator in analyzing the blast. Specific examples of recent usage in Canadian mining situations are included to illustrate the ability of the model to produce practical results that can assist in optimizing actual blasting operations or solving problems that do exist."

Jan 1, 1987

By Giannini M

Of the optimization techniques proposed in determining the optimum open pit limits, dynamic programming and graph theory have proved most successful. However, publications on these two methods lack a certain amount of rigour and clarity in exposition. Certain ideas in the methods have been clarified and additional features introduced in order to make them more sensitive to practical applications. A case study in the form of an application of these ideas on data from a producing mine is presented and discussed.

Jan 1, 1986

By Marcial Medina

El presente texto describe la reología de la Pulpa a nivel de química de superficie y así sugerir las alternativas a los problemas que impiden poder operar en forma continua y su capacidad de diseño la Planta de Flotación Diferencial de Cobre – Molibdeno. Asimismo, es necesario definir una solución a escala de laboratorio, la cual debe ser validada con pruebas industriales e implementarla en planta. La estrategia debe garantizar la continuidad de la operación de la Planta de flotación de Molibdeno con cualquier tipo de mineral y que no presente compactación la pulpa. Finalmente, se devbe agarantizar el procesamiento de toda la producción de la planta de cobre en la planta de flotación diferencial de cobre molibdeno.

Sep 12, 2011

Helium has probably aroused more varied scientific curiosity than any other single element. Discovered by spectroscopic examination of the sun during an eclipse in 1868, helium is now known to exist not only in the sun and other stars but on earth occluded in minerals, accumulated with natural gases in pockets in the earth's crust, and in the atmosphere surrounding the earth. Astronomers study its presence in the various stars of the universe for clues to their origin and history. Geochemists and geologists study its occurrences in rocks, minerals, and meteorites to determine the age of the earth and the manner of its formation. Pathologists study its effect on living tissues in search for the ideal combination with oxygen for artificial breathing mixtures in medicine, diving operations, and space vehicles. Chemists study its physical properties and use it to trace the sequence of events in reactions in which it does not participate. Geneticists and bacteriologists use it for special studies. Physicists study its behavior when liquefied and the behavior of materials cooled to nearly absolute zero by its use. Nuclear physicists learn more about the universe through study of the nuclear reactions that produce it. Through study of helium and greater knowledge of its origin and properties, science continues to unlock some of nature's more closely guarded secrets. Unknown on earth before 1895, and not discovered as a minor constituent of natural gas until 1905, helium with its simple atomic structure--a nucleus with two electrons orbiting in a closed shell--is a unique element. It is next to the lightest gas, only hydrogen is lighter. It occupies position number 2 in the Periodic Table of the Elements and heads the list of so-called "rare" or ?noble? gases. Most of the naturally occurring helium has an atomic mass of 4.003874 (oxygen = 16). A trace (1.7 x 10-5 mol percent) is the light isotope helium-3 whose atomic mass is 3.0169800 Unstable isotopes of mass numbers 5 and 6 have been authenticated. Isotopes of mass numbers 7 and 8 have been reported, but their existence is less well established. All the heavier isotopes are radioactive and are the product of nuclear reactions.

Jan 1, 1968

By J. B. Clemmer

This report summarizes the results of u laboratory study of the beneficiation of Arkansas bauxite by flotation. Although the investigation is not yet completed, a preliminary retort of the results on several typical bauxites is presented to show the merits rind. limitations of flotation for the production of concentrates acceptable to the aluminum industry. It is

Jan 1, 1941

By Stephen C. Tadolini, Dennis R. Dolinar

The risk of injury caused by minor roof falls continues to increase in underground mining. Most ground control injuries result from small rock falls that occur in a supported area, but do not involve the failure of the support system. In the roof, these are the "skin failures" that occur between previously installed primary or secondary bolting systems. To minimize skin failures and the associated accidents, several devices were designed and tested in the laboratory to maximize stiffness, minimize material thickness and weight, and ease material storage and handling on roof bolting machines. The goal of this project was to design and evaluate devices that can be installed with traditional primary or secondary roof supports, and that are easy to handle/install under temporary or previously supported roof.

By J. B. Clemmer

This report summarizes the results of u laboratory study of the beneficiation of Arkansas bauxite by flotation. Although the investigation is not yet completed, a preliminary retort of the results on several typical bauxites is presented to show the merits rind limitations of flotation for the production of concentrates acceptable to the aluminum industry. It is

Jan 1, 1941

By J. W. Thompson

That the governor is hereby authorized to appoint a commission of seven persons, to be known as the industrial accidents commission-two of whom shall be employers of labor, two of whom shall be employees in either mines or industrial establishments of this Commonwealth, or duly accredited representatives thereof, two of whom shall be learned in the law, and one of whom shall be a person skilled and experienced in making investigations-to inquire into the causes and results of industrial accidents in the mines, mills, factories, stores, and upon the railroads, street railways, ships, wharves, and in all industrial establishments, and in all other places where men, women, and children are employed in manual labor in this Commonwealth; to study the most advanced methods for safe-guarding against these accidents; to inquire into the subject of fair compensation for those who are injured in these accidents, and for the families of those who shall be killed as a result thereof; and to study the operation and effect of the Workmen's Compensation Law of 1913. SEC. 2. The chairman of said co~mission shall be designated by the governor, and the person named on said commission as a skilled and experienced investigator shall be the secretary of the commission, The commission shall have power to employ such legal counsel and other officers and employees as it may deem necessary to properly perform its duties. SEC. 3. The secretary of said commission shall receive an annual salary of $2,400 and his actual necessary expenses; and the other members of the commission shall receive no compensation for their services, but shall be allowed their actual traveling and other necessary expenses. The salaries of any other persons employed by the commission shall be fixed by it.

Jan 1, 1920

By Cem Şensöğüt, Özer Ören, Yaşar Kasap

The mining sector, which has an important place in terms of raw material and energy supply, is referred as a sector with one of the highest fatal accidents in comparison with other sectors. In this century, where occupational health and safety awareness has increased, it is important to review the past accident statistics and to determine the current deficiencies by using the information in the inventory. In this study, the Malmquist total factor productivity index (MPI) has been utilized to investigate the changes in the work accidents occurring in the Western Lignite Corporation (Turkey), where underground and surface production methods are applied, and to determine the measures to be taken. According to the results obtained, both the decrease in production amount and the increase in the number of accidents caused inefficiencies during the period in concern due to the expected 10-year economic life of the mechanized system operating in the underground production panel that came to an end in 2007 and the flooding took place in early 2017. Compared with the underground operations, it has been determined that production can be carried out at the appropriate scale despite the heavy working conditions encountered due to the changing climatic conditions and the progress of production in the surface operations.

By Ram Avtar

High tensile thick plates (>80mm, weight ~3000 Kg) of medium carbon low alloy steel, when heat treated, manifested higher percentage of crystalline area (>20%) in fractured surface. Such problem was not encountered in thinner plates. The genesis of higher crystallinity in fracture was examined. It was observed that the thicker plate undergone slower rate (Average 0.9oC/Sec.) from soaking temperature to Ms temperature) of cooling after austenising during oil quenching and thereby quenched microstructure had upper bainites. During tempering of as quenched bainite, additional precipitation took place at the lath boundaries of bainite. This led to weakening of grain boundaries and aided easy crack propagation during fracture and resulted in formation of higher percentage of crystalline area in fractured surface. Enhancement in cooling rate (Average 1.8oC/Sec. from soaking temperature to Ms temperature) of austenised plate by switching over from oil quenching to water quenching practice resulted in complete transformation of austenite into martensite and produced ductile fracture (zero Crystallinity). Plates conformed improvement in mechanical properties between 2-5%.

Jan 1, 2009

By John C. Nigro

This Bureau of Mines report summarizes the performance characteristics of a 30-day around-the-clock gasification-pelletizing test conducted in October and November of 1980 with North Dakota Indianhead lignite. Gasification was conducted in a commercial-size, 6.5-it-diam, Single-stage, fixed-bed, atmospheric pressure producer with a rated capacity of about 30 million Btu/hr. Iron oxide pellets made from a commercial hematite concentrate were fired with the low-Btu gas in a 2.8-ft-diam by 35-ft-long pilot plant rotary kiln at a rate of 900 lb of pellets per hour. Gasifier operations at fuel feed rates up to 3 tons of lignite per hour and hematite pellet induration with raw 160-Btu/std ft3 lignite gas are described.

Jan 1, 1982

By D. M. A. Flight, P. M. Green, J. A. Plant, P. R. Simpson

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The British Geological Survey's regional geochemical database is used to identify the patterns associated with the various mineral deposit types and to examine the extent to which their distribution reflects the presence of long-lived metallogenic provinces in the crust. Image analysis provides new insights into the setting of the mineralisation, geochemical constraints on tectonic models of Caledonide evolution and evidence for terrane amalgamation and large-scale processes. There is evidence that much of the mineralisation reflects the presence of long-lived provinces with a distinctive geochemistry reflecting their origins as zones of crustal extension. In the case of the Middle-Upper Dalradiam sedex deposits, the relationship between geochemistry and tectonic setting is direct. In other cases, rocks deposited in extensional zones appear to have acted as reservoirs of ore-forming elements which were further concentrated during later events

Jun 19, 1905

By A. B. Parsons

Jan 1, 1971