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By Joshua Hoffman, Braden Lusk, John Rathbun

A Flyrock Prevention Taskforce was established in Kentucky with the support of Kentucky's Department of Natural Resources, Kentucky's Explosives Industry, and the University of Kentucky. This paper presents the initial work of the Flyrock Prevention Taskforce towards its missions of identifying the root causes of flyrock incidents based on the analysis of previous events, and tracking the progress of flyrock elimination in the future. Work identifying root causes of flyrock events is presented through the development of a database which manages information about the blasts which caused flyrock. This data includes: blasting and seismograph records, drill logs, videos of the event when available, company notes/incident reports, and any additional information regarding probable cause. Work tracking the progression of flyrock elimination efforts is presented in this paper through the introduction of a flyrock index. Several metrics are proposed for this index, and are discussed for their appropriateness and shortcomings. In order for these indexes to be valid forms of tracking flyrock incident rates additional records must be kept and reported, such as the annual consumption of explosives by surface coal blasting. Suggestions for record keeping, flyrock investigation practices, and means of tracking flyrock incident rates are proposed in this paper.

Jan 1, 2013

By Gordon Bath

During the summer of 1946, the Division of Geophysical Exploration of the U.S. Bureau of Mines established several primary magnetic base stations near important iron-producing districts in Minnesota, Michigan, and Wisconsin. Stations were located in groups of four to six in six separate base-station areas, and each position was marked with a concrete monument. Differences in magnetic intensity between stations in these areas, as well as the difference between each area and a magnetic datum at the magnetic observatory of the Coast and Geologic Survey at Cheltenham, Md., were measured with a modified Askania magnetometer. Measurements also were made with a Hotchkiss superdip to study the usefulness of the stations for the calibration of instruments of this type. The work was planned and supervised by F. W. Lee, chief of the Division of Geophysical Exploration, and Edward F. Fitzhugh, Jr., chief of the Minneapolis Division of the Bureau of Mines. Special mention is due Harold B. Ewoldt, Bureau of Mines engineer, for his assistance in the field work, especially in locating and establishing monuments. Special mention also is due Clyde L. Holmberg, of the Bureau of Mines, for the magnetic measurements made with the Hotchkiss superdip. Helpful suggestions were received in the field from H. L. James, of the U. S. Geological Survey. Acknowledgment is made of the cooperation of Stephen Royce, Irving E. Beckwith, Arthur Johnson, and Josiah Royce of Pickands, Mather & Co., and A. E. Matson, of Butler Bros. The U. S. Coast and Geodetic Survey furnished daily magnetograms from the Cheltenham Magnetic Observatory as well as calibration equipment and values of absolute magnetic intensity. Short-term forecasts of ionospheric conditions were obtained from the National Bureau of Standards.

Jan 1, 1951

By Jerry Ran

Stope back caving in a mine using open stope mining interrupts the planned mining sequence and causes oversize muck and dilution with adverse economic implications. As many underground mines are mining or have plans to mine at depth, stope back caving could have significant impact on the mine sustainability. Therefore understanding the caving mechanism is important in preventing future occurrence and improving the mine economic performance. Falconbridge Ltd Kidd Mine is an underground mine using open stope method producing more than 2 million tonnes per year. Its current lowest mining level is approximately 2070m below surface and the lower portion of the orebody is being developed. In years of 2002 and 2003 the back of three stopes of approximately 1900m and 2040m below surface caved and caused substantial mining difficulties at the mine. As these caved stopes are subject to stress concentration, seismic activities and near major geological structures, the caving mechanism is much more complex than that of stopes near surface. In addition to the recorded caving history by site observations, the mine carried out cavity surveys and test drilling to define the caved profiles. The mine seismic monitoring database provided information at these stopes. Stress modeling work conducted by an external consultant provided the stress patterns at the caved stopes. Based on the field collected data and stress and seismic information, this paper presents details of the stope caving process and cavity surveyed profiles, reviews the predictability of the stability graph approach for these cases, discusses the caving mechanism and proposes preventive measures to stabilize the stope back.

May 1, 2004

By E. P. Dowding, J. Schlocker, C. H. Fuchsman, R. R. Lloyd, Mahan. W. M., O. C. Garst, W. T. Rawles

"INTRODUCTION The United States, although the leading consumer of chromite, depends almost entirely on imports for its supply. For instance, the consumption during. 1941 amounted to 714,645 long tons, whereas the domestic chromite production, although the highest since 1918, was 12,731 long tons or only 1.78 percent of the domestic consumption. 9/ Domestic production was tremendously, accelerated,after 1941 by war demands; however, only a small proportion of this domestic product was of sufficient quality to be substituted for the high-grade imported chromite demanded for metallurgical purpose. Chromite is used largely for making ferrochromium, an alloy containing 60 to 70 percent chromium which is used in making alloy steels. Peacetime specification for ferrochromium required that it should contain 68 to 69 percent chromium. These specification were lowered to between 60 and 63 percent, chromium in 1941 to permit the use of lower-grade ores. The specifications for metallurgical chromite, used for making ferrochromium, were established first by the Metals Reserve Company at 48 percent Cr203 and a Cr. Fe. ratio of 3 : 1 but later were lowered to 45 percent Cr203 and a Cr : Fe ratio of 2.5 : 1. The ratio of chromium to iron in chromite is important, because the contained iron enters the alloy in making ferrochromium and, although an ore may contain the required 45 percent Cr203, it may contain too much to be suitable for ferrochromium production. The principal sources of domestic chromite are California, Oregon, Montana, and Alaska minor, small, and widely scattered deposits in another dozen States. Without exception, these deposits are low-grade, require beneficiation to produce a commercial product, and are not competitive with imported high-grade ore in normal times. Nevertheless, these deposits form strategic reserve, which must be utilized in periods of national emergency. Recognizing this fact; the Bureau of Mines for many years has undertaken investigations to develop methods of utilizing domestic chromite ores. The problem has been approached from three angles: (1) Mechanical methods of concentration; (2) beneficiation by chemical or metal¬lurgical methods; and (3) production of metallic chromium by electrolysis of solutions prepared from ore or concentrate."

Feb 1, 1946

The optimum cut-off grade policy maximizes the net present value (NPV) of an open pit mining operation subject to the mining, processing, and refining capacity constraints. The traditional approaches to cut-off grade determination ignore the escalation of the economic parameters such as metal price and operating costs during life of an operation, and consequently lead to unrealistically higher values of the objective function. Further, the NPV of a mining operation declines due to the depletion of the available reserves, causing a decline in the optimum cut-off grade, i.e. higher cut-off grades in the early years of an operation and lower cut-off grades during the later years. Hence, low grade material mined in the earlier years may be stockpiled for processing during later years to offset the effect of escalating economic parameters on NPV. This paper demonstrates the combined impact of introducing economic parameters, escalation and stockpiling options into the cut-off grade optimization model. The model promises an enhancement in NPV as illustrated in a case study incorporating practical aspects of an open pit mining operation.

Jan 1, 2011

By J Aydin Bilgin, Sedat Esen

This paper describes the ideality of some commercial explosives with the help of the detonation theory and detonation velocity measurement. Ideality of an explosive can be determined by comparing experimentally measured and ideal detonation velocities. A measured detonation velocity at a certain charge diameter markedly lower than the ideal value indicates incomplete reaction and thus non-ideal detonation. Since it is shown that commercial explosives exhibit non-ideal behavior, two-dimensional detonation theory should be used to evaluate the performance of explosives. This theory enables to compute the detonation properties of explosives (detonation velocity, detonation pressure, etc.) as a function of charge diameter and confinement. The use of the one-dimensional detonation theory to compute the detonation properties for commercial explosives has an error associated with it as these calculated properties are independent of charge diameter and confinement. It assumes that shock front is planar. Hence, it is incapable of assessing the ideality of the explosives due to its assumptions. Shock front in real situation is curved in shape but not planar as in one-dimensional detonation theory. In this paper, the non-ideal behavior of some commercial explosives is modeled using EXRINT code based on the steady-state two-dimensional detonation theory firstly. Then the degree of ideality of each explosive found from the code is checked using detonation velocity test results conducted at a quarry. It has been shown that idealities of the tested explosives determined by the code agree well with the field detonation velocity test results.

Jan 1, 1999

The beach sand industry is the only Australian mineral industry which, so far, has used electrostatic separation on a full commercial scale. The main application of the process is for the separation of rutile from zircon. Laboratory work has demonstrated that electrostatic methods are effective for ilmenite-monazite and cassiterite-zircon separations, thus facilitating the production of high grade monazite and cassiterite products from top-strip table concentrates, but the commercial application of these processeshas been rather limited so far. Overseas, electrostatic methods are becoming more widely used for the treatment of granular material which is not amenable to flotation. The use of electrostatic separation for the treatment of ores other than beach sands has been investigated in this laboratory 1, 2, 3, and two pilot separators were built during i953 to carry out field tests. Of these, the first was an inclined feed plate separator for the removal of silica from granular lime-sand in Western Australia, the second a conductance roll separator for the removal of diamonds from alluvial gravel in New South Wales. In both cases the whole of the ore passed through the separator, not a gravity concentrate only as in beach sand practice. The two types of separator mentioned are shown diagramatically in Figs. 1 and 2.

Jan 1, 1954

By Eric Dussell

Commercial or industrial explosives are mechanically-mixed, fuel-oxidizer composites which exhibit varying degrees of non-ideal behavior. Non-ideality results from a relatively slow and state-insensitive reaction rate (Lee, 1990) and is characterized by C-J pressures, velocities or expansion isentropes significantly lower than those expected from equilibrium, steady-state calculations such as Tiger or BKW (Mader, 1979). This departure results from significant amounts of explosive material which remain unreacted at the sonic point. Energy released by continued combustion within the emergent supersonic region downstream of the sonic point, constrained by local sound speed, cannot flow to the shock front and do work on it. The significant amount of this ‘late energy” and its slow time rate of release must be considered in any blast performance model.

Jan 1, 1997

By D. C. Lynch

While a sizable amount of data exist as to the activity and distribution of minor elements between matte and metal, there has been no unifying theory presented delineating the form of dissolution of these elements in molten sulfides. In order to alleviate that deficiency the literature concerning the behavior of As, Sb, Bi and Pb in mattes is reviewed. Models present in the literature, regarding the thermochemical behavior of minor elements, are tested, and new models are presented and evaluated using thermodynamic theory. The results of those analyses are used to predict optimum conditions for the volatilization of minor elements. The dearth of data on the behavior of minor elements in nickel mattes requires that this review focus on copper- iron mattes. An effort is made, however, to utilize basic knowledge regarding nickel sulfides and the interaction of nickel with the minor elements to predict the behavior of those elements in nickel-copper and nickel-iron mattes.

Jan 1, 1993

By R. H. Fernald, C. D. Smith

When the United States Geological Survey began operations at the coal-testing plant erected at the Louisiana Purchase Exposition at St. Louis, Mo., in 1904, it had already outlined a comprehensive plan for the systematic study of coals, lignites, and other mineral fuels with reference to their suitability for particular purposes and the methods by which they could be utilized most efficiently. Recognizing the need of information on the relative economy of producer gas as compared with steam for power purposes and the lack of comparable tests of American coals in the gas producer, the Geological Survey undertook investigations of the merits of different coals as producer fuel for the purpose of promoting efficiency in the utilization of the nation's fuel supplies. These investigations were carried on at St. Louis, Mo., and, later, at Norfolk, Va., and Pittsburg, Pa. The aet of Congress approved May 16, 1910, transferred the fueltesting work being carried on by the Geological Survey to the Bureau of Mines. This bureau is conducting producer-gas tests at P~ttsburg, Pa., and is publishing and distributing reports relating to all the fuel tests made by the Survey. These investigations into the possibility of generating producer gas in a commercial way for power purposes from the various fuels of the country have been associated with steaming, briquetting, coking, and other tests, all of which supplemented an examination into the nature, extent, and distribution of the fuels. The tests have all been made with carefully selected representative samples and carload lots of materials procured specially for the purpose by experienced collectors.

Jan 1, 1911

By S. Kawatra, K. Lewandowski

Heap leaching efficiency is reduced by poor solution flow characteristics (channeling and ponding), which result from fines migration. Agglomeration of the ore can immobilize fines, but copper leaching requires an acid-resistant binder to stabilize the agglomerates. Until now, there has not been a satisfactory way to evaluate whether a binder was effective, other than squeezing a handful to see if it “feels right”. We have developed procedures to quantitatively determine whether a binder gives good performance in an acidic solution, and have identified several binders that will be suitable for copper heap leaching.

Jan 1, 2007

By Roberto Folchi, Hans Wallin

Having so many norms and technical content of legislation to deal with is a problem that an explo-sives engineer has to face, especially when working at an international level. Each country has its own norms and legislation, sometimes even each other region or state, as if the physics of explo-sions, rock, concrete, and masonry characteristics would change across the borders. Both norms and laws are frequently out of date, being mainly developed at the beginning of the previous century and adjusted, piece by piece, to a technical and political context that is constantly changing, with adjustment being frequently adopted in a hurry, due to a problem arising such as that of internation-al terrorism. Sometime also, norms are not harmonized with those they intend to amend, so required explanations and new adjustments lead to a vicious circle that increases confusion, complexity and depresses the explosive industry.

Jan 1, 2015

By P. Brad Marchant

"To properly evaluate bioleaching as a commercial alternative for sulphide concentrate oxidation, to enhance cyanidation response, it was necessary to define and optimize critical operating variables outside of the laboratory under less than ideal conditions. A complete bioleach testing laboratory was installed at Equity Silver Mines to aid in pilot plant flowsheet development.A continuous pilot scale bioleach circuit was constructed to provide data for meaningful valuation of biotechnology on a plant scale. The important operating and design parameters for pilot plant testing are described. Plant scale feasibility and design considerations, to treat a refractory pyrite/arsenopyrite concentrate produced from flotation tailing, are discussed. 1.0 BACKGROUNDEquity Silver Mines Limited is located 37 km southeast of Houston in central British Columbia. A 70% owned subsidiary of Placer Development Limited, Equity is Canada's largest open pit silver producer. Ore reserves were estimated at 28 million tonnes grading 106 g Ag/t, 0.96 g Au/t, and 0.38% Cu from two pits, the Southern Tail and the Main Zone. Detailed geology and mineralogy has been described previously(1,2).The concentrator flowsheet consists of conventional crushing, grinding, flotation, and dewatering circuits processing 5 300 tonnes per day of new mill feed. The resultant Cu/Ag/Au concentrate is trucked to Prince Rupert for shipment to market. Mill tailing reports to a closed circuit pond from which mill process water is recycled. Details of the concentrator process have been reported( 2,3).Production in the Southern Tail pit, from July 1980 to March 1984, resulted in mill tailing averaging 0.9 g Au/t and slightly more than 20 g Ag/t. Historic data indicate that unrecovered gold is associated with arsenopyrite and silver losses with unliberated tetrahedrite or minor silve,, bearing sulphosalts. Main Zone mill tailing, which commenced production in March 1984, contains approximately 0.5 g Au/t which is probably associated by majority with silver bearing minerals and pyrite while silver losses, 30-40 g Ag/t, are associated with unliberated silver and antimony bearing minerals."

Jan 1, 1985

By Edward Keller

The work covered by this report was undertaken at the request of Dr. J. A. Holmes, late Director of the Bureau of Mines, to whom the writer had been recommended by C. W. Goodale and E. P. Mathewson, of Butte and Anaconda, Mont. The director's offer was accepted for the honor it conferred and for the useful results that might be promulgated by the work in the technical field covered. The investigation was facilitated by permission to visit various works and sometimes by contributions of important definite information on a given subject. It is therefore with pleasure that acknowledgment of courtesies is made to the following corporations and gentlemen: Anaconda Copper Mining Co., Raritan Copper Works, Baltimore Copper Smelting & Rolling Co., United States Refining Co., American Smelting &, Refining Co., B. B. Thayer, A. C. Clark, A. L. Walker, William H. Peirce, E. A. Cappelen Smith, H. H. Alexander, F. C. Newton, S. Rolle, R. W. Deacon, N. W. Pierce, O. C. Martin, C. N. Sappington, James K. Thomson, W. G. Derby, and the assistants of the writer, K. W. McComas and W. L. Raup. In this report considerable space has been devoted to general and theoretical principles on the ground that under modern conditions the best results in any field of activity can be attained only with the a. id of an adequate knowledge of the best theories underlying the practice. The diffusion of such knowledge in the field of sampling metallic metallurgical materials appears to have been quite insufficient, and it is felt that when the principles involved are once thoroughly comprehended their universal application will be appreciated, so that it will make no difference whether pig iron or gold bullion is offered for test. It may further be noted that a discussion of the theories underlying practical methods is placed under the caption "Practical Sampling," with the idea that no one can be a practical sampler unless he is capable of analyzing his methods. No attempt has been made to advocate any one method, but it is hoped that the analyses of all of the methods in use will show where each may be correctly and safely applied. The fact that it is possible to demonstrate the theoretical correctness of several methods indicates the invalidity of the claim that any single one of them is the standard.

Jan 1, 1916

By W. L. Cooley

The report provides a detailed analysis of 23 electrical accident countermeasures contemplated for use in the metal/non-metal mining industry. The costs and potential benefits of implementing groups of these countermeasures are estimated, and methods arc outlined by which the operator ran choose countermeasures in an effective manner. The analysis is based largely on an extensive electrical accident event tree which is developed in detail. For those countermeasures which are not currently technically feasible, several prototype devices were developed to help speed development. These included a trolley arc eliminator and a safer mine electricians multimeter.

Jan 1, 1982

By A. J. Monhemius

This paper reviews the history of modern iron-control processes in hydrometallurgy. Attention is paid to processes developed in the electrolytic zinc industry for removal of iron from zinc sulfate leach liquors and the problems faced by the industry in the safe disposal of the iron residues produced by these processes. Past lessons learned are projected onto current efforts to develop hydrometallurgical processes for treatment of copper sulfide concentrates. It is argued that any attempt to create a \u201chydrometallurgical copper smelter\u201d will fail, unless methods are developed that can recover iron in a form that can be directly used by the steel or pigment industries.

Jan 1, 2017

The material presented in this paper describes experimental work to determine the effect of variations in suction nozzle design upon inlet flow conditions. Four entrance profile shapes were examined under controlled conditions of slurry flow and it was found that the straight ended nozzles had consistently higher entrance losses than the straight taper or the ellipse, and that the circular arc profile nozzles were the most efficient. Subordinate considerations were the measurement of the quantities and the forces involved.As the work progressed, three distinct phases in the pattern of flow were apparent and the static pressures in each were carefully examined. An inlet zone was found to be unstable in changing boundary conditions, a transition zone was largely independent of slurry density and in a zone of stability the pressures were found to be directly related to the characteristics of the flowing pulp. In this zone pressure measurements were reproducible within ± 2 per cent regardless of changing boundary conditions.The effect of varying the "1" parameter of nozzles with a part circular entrance profile was examined and it was found that flow conditions approaching the ideal were obtained when the radius of curvature was between 0·40 and 0·550.

Jan 1, 1966

By Kot F. Unrug

In the premining stage of engineering design, the only available data are obtained from core drilling. It is often not sufficient for a realistic design of strata control. During the development, an access to the geological formation is created, enabling in situ testing. Obtained data can be utilized accordingly to improve preliminary design. The available methods for testing are described with emphasis on their application for a longwall system. The optimum design ensuring continuous operation of the high output longwalls is critical because their downtime is very expensive. Optimization of ground control measures also has the potential for substantial savings by elimination of unnecessary support.

Jan 1, 1994

By Donald F. Reed

Deposits of gray hematite occur in two districts in Talladega County, Ala., the Emauhee-Tallasechatch and Weewoka, both in the; vicinity of Wintorboro, 50 miles east of Birmingham. The deposits were investigated by the Bureau of Mines in 1945 and 1944. Approximately 15,000 feet of diamond drilling was done and 6,000 linear feet of trenches excavated and sampled.

Jan 1, 1949

By H. B. Hill

Virtually from the date of its discovery in December 1928 the Oklahoma City oil and gas field, Oklahoma County, Okla., has attracted national and international attention. The history of the field has been associated closely with rules and regulations pertaining to production control and proration practices. Early development was rapid, and Oklahoma City soon attained the distinction of being the first major field in which the producing wells were over a mile in depth. Before the structural features of the reservoir had been disclosed every outpost well was considered a "wildcat", so complex appeared the underground geology, The wells not only were deep and the reservoir pressures high, but the production from the early wells was a high A.P.I. gravity oil, accompanied by large volumes of gas. Several "blow-outs" and fired occurred during the early development, and the close proximity of these now unusual events to a large city gave the field much publicity, both local and national. Later, when its production threatened to demoralize the market for oil and its products, the Oklahoma City field again attracted wide publicity. The then little understood geology of the underground reservoir and the diversity of ownership of the land overlying the producing structure made orderly development and production difficult to enforce. Proration was enforced with difficulty., and the, rate of production from the field continued to increase until, on August 4, 1931, martial law was declared in all prorated fields of the State, and most of the wells in the Oklahoma City field wore shut n. On October 9, 1931, permission was granted t o reopen and prod e the wells in the Oklahoma City field. The order permitting production of the wells provided that during the period beginning October 10 and extending to October 20, 1931, all wells in the field that hid not produced more oil than specified under the earlier proration orders and that had been shut in for the required 55-day period were permitted to produce 5 percent of their last potential during that 10-day period. On November 7, 1931, the Corporation Commission of Oklahoma issued an order which divided the Oklahoma City field into the Wilcox, Arbuckle, and Lower Simpson zones for proration purposes. Wells producing from the Wilcox zone were allowed to produce 4 1/2 percent of their potential5/ from November 1, 1931, to January 1, 1932; Arbuckle limestone wells were allowed to produce 250 barrels of oil daily; and Simpson sandstone wells which had a potential of over 2,000 barrels per day or which made 3 percent or more water were allowed to produce 200 barrels of oil per day.

Jan 1, 1937