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Provide an unobstructive means of measuring small changes in distance from roof to floor or from rib to rib of a mine opening and the rate of closure in order to help operators of under-ground mines detect hazardous ground conditions. Approach A small ultrasonic measurement system was developed to detect g round movement and define closure rates. How the System Works The system contains two parts: a transducer and a readout device. The small ultrasonic transducer, similar to an audio speaker diaphram, is plucked with an ultrasonic frequency every six seconds. This frequency wave is sent through the air and reflected back to the transducer off any surface at which the transducer is pointed. The amount of time needed by the ultrasonic wave to make this round trip is accurately measured using a precise oscillator / timer and is converted into a measure of distance. The accurate 6-second time interval is used to convert any subsequent changes in the reading to a rate of change in feet per minute. Two readings are then displayed alternately on the readout instrument.

Jan 1, 1984

By Steve Kral

A near-record crowd of mining history enthusiasts made the trip to Leadville, CO in September to attend the National Mining Hall of Fame and Museum’s 19th induction banquet. Dressed in Victorian garb, black tie tuxedos and formal gowns, the 268 people honored four distinguished men who made a lasting impact on the U.S. mining industry. They joined 188 other inductees. The first induction banquet took place in 1988, with about 500 people attending.

Jan 1, 2007

By J. L. Page, A. C. Marlowe

The Research and Development Services of South Africa has begun underground trials with a Robbins 52RE blindhole borer using a cutterhead fitted with high pressure water jets to assist mechanical cutting. The objectives of the work are to reduce cutter costs by increasing cutter life and to increase overall penetration rates. The paper reviews blindhole boring in South Africa and laboratory experiments in rock cutting assisted with high pressure water jets. The borer and its ancillary equipment are described. Initial results of underground boring experiments are presented. The paper concludes with the test programme for the future.

Jan 1, 1985

By M. B. Balachandra

A three-dimensional finite element analysis was performed of an instrumented section of a double-entry coal mine in order to provide a comparison between field measurements and existing analytic techniques. The BMINES computer code was used to perform the analysis. The sequence of excavation of the entries was considered, as well as the installation of rock bolts and cribbing during the mining cycle. The materials In the region under investigation were idealized into four rock types and coal. The rocks were assumed to be isotropically elastic, perfectly plastic. Coal was represented by an elastically anisotropic (transverse isotropy) and plastically isotropic model. A fracture yield criterion of the Coulomb form was used for all materials. The strength and stiffness of all materials were substantially reduced from available laboratory data to account for in-situ properties. Qualitative trends and stress distributions obtained from the calculation were found to be reasonable. However, computed displacements and closures were greatly exaggerated and an excessive degree of inelastic deformation was indicated in the coal, especially adjacent to the excavated faces. It was established that both these effects were the result of an excessive reduction in the strength and stiffness of the materials. The analysis underscores the need for three-dimensional calculations by identifying a number of important structural response parameters that would be either outside the scope of, or misrepresented by, two-dimensional analyses. The analysis also emphasizes the need for comprehensive and accurate measurement of material properties in order fully to exploit the power of the analytical techniques to generate reliable predictions.

Jan 1, 1976

By G. W. Jones

During the course of an investigation by the Bureau of Mines into the causes, behavior, and control of anthracite-mine fires, it was observed that the carbon monoxide disappeared from a sealed fire area much more rapidly than could be explained on the basis of leakage of gases. Two suggestions were offered for this high rate of disappearance: (1) That the carbon monoxide, was oxidized at temperatures below 150° C. by either the anthracite or its ash (tests on many anthracites have shown that at temperatures above 150° C. carbon monoxide is liberated in the oxidation products when air is passed through it); (2) that the carbon monoxide was oxidized by micro-organisms present in the sealed area.

Jan 1, 1939

By Paul L. Campbell

Investigations by the Federal Bureau of Mines of methods of upgrading tar obtained by low-temperature carbonization of lignite showed that ß,ß?-oxydipropionitrile, ß,ß?-iminodipropionitrile, and ß,ß'-thiodipropionitrile were effective solvents for extracting aromatics (aromatic hydrocarbons plus polar compounds) from coal-tar neutral distillate fractions. Batch extraction showed that these solvents extracted approximately the same percentage of aromatics from various neutral oil fractions boiling between approximately 170° and 350° C. In continuous countercurrent extractions using oxydipropionitrile and iminodipropionitrile, approximately 30 to 35 vol.-pct, and 65 to 70 vol.-pct, of the aromatics in 170° to 350° C. neutral distillate oil were extracted at room temperature when solvent-to-oil ratios were 2:1 and 12:1, respectively. As the concentration of aromatics in the neutral distillate oil fraction decreased, the capacities and, to some extent, the selectivities of these solvents for the remaining aromatics decreased. Aromatics were isolated from the extracts and the solvents recovered by washing the extract fractions with a low-boiling paraffinic hydrocarbon such as heptane, using hydrocarbon-to-extract ratios of at least 2:1. The heptane wash removed most of the aromatics but only part of the polar compounds (compounds containing oxygen, sulfur, and nitrogen) from the extracts. The recovered oxydipropionitrile and iminodipropionitrile, containing polar compounds, were effective in extracting aromatics from neutral distillate oils. The contaminated solvents showed essentially the same capacities and selectivities as the pure solvents.

Jan 1, 1961

The refractory nature of residual gold in Kalgoorlie calcines is caused by occlusion in dense pyrrhotite formed by fusion within pyrite grains during decomposition. Fusion of pyrite increases as the rate of heating exceeds the rate of sulphur expulsion. By controlling these rates in relation to each other in a fluidised system fusion is limited and an expanded structure is formed. The increased area presented to cyanide solution, and the decreased diffusion distance, makes gold more accessible for extraction. Gold extraction from expanded pyrrhotite, before oxidation for porosity, is comparable with extraction from fully oxidised calcines from Edwards roasters. A method is suggested for standardised comparison of cyanidation residues.

Jan 1, 1957

By R Fury, I Skepper, D White, G Miller

Although the Pressure Acid Leaching (PAL) of nickel laterites has been conducted at Moa Bay, Cuba, since the early 1960s, the commissioning delays generally encountered by the æsecond generationÆ of PAL lateritic nickel producers in the late 1990s have demonstrated the potential complexity of the PAL process and the importance of technical risk management in maximising the realised project value. This paper describes some of the strategies used by the Ravensthorpe Nickel Project (RNP) to manage the technical aspects of the Ravensthorpe project risk. Central to these strategies is the use of Front End Loading (FEL) to deal with issues early in the development phase, when changes to the project structure can be made most effectively and cheaply. Such an approach requires a management philosophy that recognises risk as a potential cost, which accepts responsibility for dealing with risk, and which is prepared to provide adequate resources for risk management.

Jan 1, 2004

By E. Marcoux, F. Lotfi, A. Belkabir, L. Maacha, A. C. Brown, S. Brunet

"Koudiat Aïcha is a small Zn-Pb-Cu deposit, enclosed in the Visean Sarhlef volcano-sedimentary series of the Moroccan Hercynian Jebilet massif. Base metal mineralization is located between a basal unit consisting of black argillite with arenite intercalations, and an upper unit composed of black argillite with locally fossiliferous calcareous units towards the top. Paraconcordant gabbro sills are present in both the upper and basal units, and the enclosing strata. Three successive phases of deformation linked to regional deformation overprint the volcano-sedimentary rocks and gabbros, as well as the sulfide mineralization.The mineral deposit includes several lenses of massive to semimassive pyrrhotite, 1 to 20 m thick, with a large halo of disseminated sulfide veinlets and sulfide nodules within a zone of intense chlorite alteration in the footwall. The ore mineralogy consists of massive to semimassive pyrrhotite with lesser amounts of sphalerite, chalcopyrite, arsenopyrite, galena, pyrite, and stannite.Lead isotope results (206Pb/204Pb averaging 18.27) suggest that the metals of the Koudiat Aïcha deposit are derived from the volcano-sedimentary host rocks. Sulfur isotopes also indicate a volcano-sedimentary origin, with bacterial reduction of sulfate (d34SCDT = -7.5‰ to -10.5‰). The conditions for sulfide meta-morphic equilibration range from 250° to 330°C (sphalerite and chlorite geothermometers). The gabbroic sills could have been a local heat source for hydrothermal circulation. Based on these geological and mineralogical features, a Besshi-type model seems appropriate for the genesis of the Koudiat Aïcha mineralization.Koudiat Aïcha est un petit dépôt de Zn-Pb-Cu, encaissé dans la série volcano-sédimentaire Viséenne de Sarhlef dans le massif Hercynien de Jebilet au Maroc. La minéralisation en métaux usuels se situe entre une unité basale d’argilite noire interlitée d’arénite et une unité supérieure composée d’argilite noire comprenant localement des calcaires fossilifères près de son sommet. Des sills de gabbro paraconcordants sont présent à la fois dans les unités basale et supérieure, ainsi que dans les strates environnantes. Trois phases de déformation successives associées a la déformation régionale superposent leurs effets sur les roches volcano-sédimentaires, les gabbros, ainsi que la minéralisation sulfurée. Ce gîte comprend plusieurs lentilles de pyrrhotite massive a semimassive de 1 a 20 m d’épaisseur au sein d’un large halo de veinules de sulfures disséminés et en nodules au sein d’une zone intensément chloritisée dans le mur du gisement. Le minerai consiste en pyrrhotite massive à semimassive avec des quantités subordonnées de sphalérite, de chalcopyrite, d’arsénopyrite, de galène, de pyrite, et de stannite. Les résultats de l’analyse des isotopes du plomb (206Pb/204Pb moyen de 18.27) suggèrent que les métaux du gîte Koudiat Aïcha proviennent des roches volcano-sédimentaires encaissantes. Les isotopes du souf¬fre indiquent eux-aussi une origine volcano-sédimentaire, impliquant la réduction bactérienne des sulfates (d34SCDT = -7.5‰ et -10.5‰). L’équilibration métamorphique des sulfures s’est produite entre 250° et 330°C (géothermomètres à sphalérite et chlorite). Les sills de gabbro pourraient avoir été la source de chaleur locale responsable de la circulation hydrothermale. Sur la base de ces caractéristiques géologiques et minéralogiques, il semble approprié d’invoquer un modèle de type pour Besshi pour expliquer la genèse de la minéralisation de Koudiat Aïcha."

Jan 1, 2008

By James S. Browning

[The objective of this project wan to determine the technical feasibility of recovering the associated copper, lead, and zinc from the pyrrhotite axe, of the Great Gossan lead, which has bon pined only for it:, sulfur and iron contents so far. The report constituted a description and discussion of small-scale Preliminary studies. This great pyrrhotite or body has strategic value, inasmuch it contains considerable quantities of zinc, copper, and lead, as well as the iron rend sulfur. The recovery of the: copper, lead, and zinc, associated with certain of the pyrrhotite ore bodies, could augment our domestic supply of these metals.]

Jan 1, 1953

By John C. Machisak

This publication, for the calendar year 1959, contains statistical data on injuries and employment pertinent to metal mines, ore-dressing plants, and primary nonferrous smelters, refineries, and reduction plants. The Bureau of ,Mines is authorized to request data on injuries and employment in the metal-mining industry, and the information, voluntarily submitted by the operators, contributes immeasurably to the promotion of safety in the metal- mining industry. Every effort has been made to make the annual canvass as complete as possible. The data presented are classified according to the hind of ore mined and includes information on copper, iron, lead-zinc, gold-silver lode, placer, uranium- vanadium, and miscellaneous metals. A breakdown of miscellaneous metals by commodity is shown in tables 17 and 18.

Jan 1, 1963

By Kenneth Eltschlager, Jim Ratcliff, Michael Mann, Edward Sheehan

The Appalachian Blaster Certification Delegation initiated a study to compare the consistency of measurements from blasting seismographs. Six blasts were monitored at surface coal mines in West Virginia, Maryland, and Ohio. A total of seven different makes were deployed during the tests, with as many as seven models from five different manufacturers compared during any one blast. Great care was taken to bury the geophones in identical fashion. The variations in seismograph readings were compared to the International Society of Explosives Engineers’ Performance Specifications for Blasting Seismographs. Between 4 and 125 Hertz, the ground vibration amplitudes should be within ±5% and airblast amplitudes should be ±1 decibel. For each of the three mutually perpendicular ground vibration channels and the acoustic channel, the median value of all the units was used as a baseline for comparison. The six blasts monitored had median peak particle velocities ranging from 0.42 to 3.47 inches per second (in/s) (10.7 – 88.1 mm/s) and median airblasts ranging from 124 to 135 decibels (dB). There were 46 seismograph recordings for the six blasts. Eighteen (39%) of the 46 maximum peak particle velocities varied more than ±5% from the median. A total of 138 (3 × 46) component particle velocities were recorded, with 50 (36%) of the readings varying more than ±5% from the median. For airblast comparison, 43 recordings were obtained, with seven (16%) varying more than ±1 dB of the median. Variances may be attributable to blasting seismograph differences, variations in field deployment, and relative locations of the geophones. Full waveform seismic and acoustic overlays for individual blasts showed encouraging conformity with some slight anomalies

Jan 1, 2015

By John C. Machisak

This publication, for the calendar year 1959, contains statistical data on injuries and employment pertinent to metal mines, ore-dressing plants, and primary nonferrous smelters, refineries, and reduction plants. The Bureau of Mines is authorized to request data on injuries and employment in the metal-mining industry, and the information, voluntarily submitted by the operators, contributes immeasurably to the promotion of safety in the metal-mining industry. Every effort has been made to make the annual canvass as complete as possible. The data presented are classified according to the hind of ore mined and includes information on copper, iron, lead-zinc, gold-silver lode, placer, uranium- vanadium, and miscellaneous metals. A breakdown of miscellaneous metals by commodity is shown in tables 17 and 18.

Jan 1, 1963

By K. M. Stone, N. J. G. Masson, A. C. Woollett

The Jabali zinc deposit, in Yemen, contains at least 9.4 Mt at a grade of 10.7% zinc, 2.2% lead and 77g/t silver. The zinc occurs as smithsonite with minor hydrozincite. The Jabali ore does not produce a zinc concentrate of sufficient grade to be acceptable to conventional smelter/refineries, and it has been necessary to formulate a less conventional development plan. This involves the construction of a mine and concentrator at Jabali and a metal production facility using a new flowsheet designed specifically for the treatment of oxide material, at Yanbu, in Saudi Arabia. In order to give the facility the necessary economies of scale, the Jabali concentrate will be supplemented by feed from other deposits, this may be either oxide or sulphide material. The paper outlines the geology and proposed mining and treatment operations at Jabali, the flowsheet for Yanbu and presents preliminary costs for both operations

Jan 1, 2002

By Jay L. Hodkinson

Replacement of an aging twin span river crossing in Vermont required a temporary bridge to accommodate traffic during construction. Soils beneath the temporary approach embankment consisted of very soft organic clayey silt underlain by interbedded, loose alluvial fine sand and silt/clayey silt. Reinforcement was required for the southern temporary approach embankment to limit settlement and to increase global stability factors of safety. A ground improvement design was developed using Rammed Aggregate Pier® reinforcement and was included in the contract documents as an FHWA Category II Experimental Feature. Instrumentation intended to document the performance of the supported embankment was installed. Piers were then constructed and monitoring commenced as embankment and bridge construction occurred. Weekly instrumentation data reports indicated continuing excess pore water pressure, settlement, and lateral deformation of the subgrade soils as the embankment and temporary bridge abutment was constructed. In response to the unanticipated monitoring results, further investigation indicated that significant deviations from the conditions and basis upon which the ground support design was developed were made during construction. This paper discusses these deviations and their specific impacts to embankment support performance, how these deviations occurred, the role that the ground support system played in maintaining global stability, measures taken to limit further detrimental impacts to the embankment, and provides recommendations for contract document preparation and construction oversight to prevent similar situations from occurring on future projects.

Jan 1, 2011

By G. D. Schena, C Chiaruttini

The feasibility is demonstrated of reconstructing the volumetric distribution of liberated particles and middlings by use of a damped, weighted least-square regularisation method. This allows a precise mass balance to be obtained around a separation/concentration unit, permitting evaluation of the partition curve (Tromp curve) of the separator. Areal grade measurements are made on polished sections of feed, concentrate and tailings and a kernel-based inversion technique is then used to obtain the volumetric grade distribution of the three assemblages. A plain kernel (number of occurrences) and a weighted kernel (each occurrence counted with its area) are used for the solution. Testing of the method on computer-generated synthetic areal grade measurements indicates that it offers a valid alternative to the tedious conventional procedure of conducting experiments with heavy liquids

Jun 21, 1905

By T. R. A. Davey

The fundamental principles by which bismuth may be removed from lead by pyrometallurgical processes are enumerated. Qualitative discussion of the phase diagrams concerned is followed by presentation of quantitative diagrams. Brief mention is made of the practical aspects. Data presented show how chemical lead (<0.005 pct Bi) may be produced by the Jollivet, Dittmer, and Kroll-Betterton processes. BISMUTH is an element whose properties are very similar to those of lead, and its minerals are associated to a greater or lesser extent with nearly all the major lead ore deposits of the world. In consequence, the lead produced contains bismuth unless a special debismuthizing process is practiced. There does not appear to be any published comprehensive review of the effect of bismuth as an impurity on the properties of lead, and there is some uncertainty as to the beneficial or detrimental effects of small amounts of bismuth in lead used for particular applications. Standard specifications of most countries stipulate a maximum bismuth content of 0.005 pct for chemical lead. With one exception, this specification is met only by lead producers whose ores are relatively bismuth-free, or whose refineries are electrolytic. In lead for certain applications a higher bismuth content is preferred by some fabricators.&apos; In contrast to the refining for silver, copper, and antimony, the refining for bismuth does not usually result in a large overalil economic gain from the sale of byproduct. Thus, debismuthizing is customarily practiced only if market conditions demand a lead with a bismuth content lower than that produced by classical refining; i.e., softening, desilverizing, and zinc refining. Until this century, debismuthizing was carried out only a:; an incidental result of desilverizing, as later described. This century has seen the development of the Betts electrolytic process—the only successful one of many electrolytic processes proposed and patented —and a number of precipitation processes based on the pioneering work of Kroll,&apos; although only one of these, the Kroll-Better ton process,&apos; is in wide commercial use today. It is proposed in this paper to deal only with the pyrometallurgical processes, excluding those based on aqueous electrolysis. Historical Background Prior to 1833 silver (and incidentally bismuth) could not be removed from lead. To recover silver from rich bullion, the only course available to lead refineries was to cupel the bullion, forming a slag of litharge. The first slag tappings or skimmings, on reduction, yielded soft lead of very low silver and bismuth contents. Intermediate skimmings yielded a lead of somewhat higher silver and bismuth contents, which could if desired be recupelled. The last skimmings yielded a litharge very high in bismuth, which could by successive oxidation and reduction cycles be separated into high purity bismuth, and lead returns. This oxidation reduction process, with modern operating techniques, can still be used today to produce a portion of a lead refinery&apos;s output of very low bismuth content, as discussed later. In 1833 Pattinsone discovered that lead bullion could be purified of silver and bismuth by fractional crystallization, the primary lead crystals formed by partial freezing being purer than the melt. Repeated processing in pans produced a lead containing as little as 0.02 pct Bi. The simple explanation of this

Jan 1, 1957

By F. G. Scott

This document is a proposed program plan for mining environmental research to be conducted by the U.S. Bureau of Mines in support of industrial oil shale mining and processing. This program plan is one of three research alternatives being considered by the Bureau, each based on a different level of anticipated funding. This report documents the mid funding level program plan.

Jan 1, 1980

By J. Burgess Winter

It is an honor to present the lecture in honor of Daniel C. Jackling, the developer of the technology of copper mining that we continue to use 100 years later. He made a dramatic breakthrough in the early part of this century in the development of bulk-mining methods for large, low-grade porphyry copper-sulfide ore bodies. At Magma Copper, we are particularly proud that the Jackling Award states we have "made significant contributions to technical progress." Before Jackling&apos;s time, copper mining had exploited with primitive equipment very high-grade underground ore bodies and high-grade open pits. During the 20th century, the situation changed. Three significant innovations occurred within about 10 years around the turn of the century. In 1903, Jackling&apos;s concept of large-scale mining with steam shovels and rail haulage was implemented at the Bingham Canyon mine in Utah. Eighty years after the introduction of rail haulage, the mine converted to truck haulage with large-capacity high-efficiency haul trucks and reduced the stripping ratio from 3.5:1 to less than 1:1.

Jan 1, 1995

By Doris M. Hyde

Mineral output and trade in the Central American countries were directly or indirectly affected by the sometimes violent civil unrest and recessionary economic developments that have pervaded the region for several years. Central American countries found their foreign exchange export earnings and traditional market areas shrinking while essential import costs were rising. Restricted spending measures were adopted by governments and private industries. Domestic investment funds for mineral development and exploration projects were among the first casualties of these austere budgetary measures, especially since weak demand and depressed mineral prices diminished the probability of a favorable cost-benefit ratio. The lack of physical security and political stability also discouraged private foreign investment. The United States Congress enacted the Caribbean Basin Economic Recovery Act of 1983 (19 U.S.C. 2702), more popularly known as the Caribbean Basin Initiative (CBI). This legislation was designed to stimulate economic recovery and promote economic development by increasing private investment and trade in the Caribbean Basin countries. The act provided for the elimination of U.S. duties on most trade items imported directly from eligible Caribbean countries, provided at least 35% of the product value originated in the region. The financial assistance components of the CBI were to be supportive of the basin&apos;s private sector as well as assist general economic stabilization programs.

Jan 1, 1985