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By P. Kim Carroll, D. Nick Tiffany, Doyl M. Fritz

Thunder Basin Coal Company received the 1987 Wyoming Excellence in Surface Mining Award for construction of the State's first major sediment control reservoir to be designed using the new settleable sol ids standard. Use of this standard resulted in construction cost savings of more than $250,000; reduced water quality monitoring; enhanced downstream channel stability because of more natural sediment loading; allowed simultaneous establishment of permanent waterfowl and fisheries habitat; and provided a quality recreational site. This article will address factors associated with the design and construction of that sediment reservoir and the benefits that were realized. (Note: This paper was originally published in the proceedings for the 1988 National Symposium on Mining, Hydro1ogy, Sedimentology and Reclamation held in Reno, Nevada, December 5-9, 1988.)

Jan 1, 1989

By T. D. Maki

FMC Gold's Paradise Peak Mine, located 13 km (8 miles) south of Gabbs, Nevada, became operational in April of 1986. Shortly thereafter heap leach testwork began on sub mill grade ore. Presently, testwork continues in combination with production size heaps that account for approximately 6% of total gold production at Paradise Peak.

Jan 1, 1989

By Larry L. Snyder

A compact 4.87 m (16 ft) diameter tunnel boring machine (TBM) is capable of boring a 12.2 m (40 ft) radius curve while gripping horizontally, or vertically, as may be required for the excavation of turnouts. The machine's 5.0 m (16.5 ft) length and a patented machine structure allows steering while boring without causing harmful eccentric loads. An extremely stiff thrust system, rigid front and rear grippers, and the torsional stiffness of a front end electric cutterhead drive combine to create superior machine stability and boring efficiency. A 2.2 m (7.2 ft) diameter prototype, complete with a soft ground shield attachment, was used successfully on a tunnel project in Scotland.

Jan 1, 1989

By D. B. deur Mostert

This paper was presented at the Coloquium on Management Techniques in the Mining and Metallurgical Industry, which was organized by The South African Institute of Mining and Metallurgy and held in Pretoria during June 1988. The author asks whether technical audits are of any use to management. Technical auditing he defines as an evaluation undertaken by an outsider of whether a technical activity is being carried out correctly. After examining the types of technical auditing, and its prerequisites and procedures, he describes its application in regard to quality, and to production processes and their adequacy. He then answers his question by saying that, not only are technical audits very useful, but they form an essential element in the provision of quality products. In addition, they give management the opportunity of testing whether the activities of the organization are being conducted correctly. This is their most important function in that they alert management to areas of potential growth, modernization, and innovation. However, the use to which technical auditing is put remains the key to its value; that is, its value depends on the positive action that each manager takes as the result of a technical audit.

Jan 1, 1989

By Tom L. Enos

Increased production through the plant was limited due to thickener circuit constraints. To overcome these constraints and maximize plant throughput to match grinding circuit capability, two options were considered: A. Adding 2000 TPD CIL circuit to operate in parallel with the existing CCD circuit. B. Adding a CIL circuit to treat the entire 4600 TPD while retaining some thickeners for tailings thickening. Option B was selected based on simplified plant operations, reduced operating costs, minimal capital requirements, reduced solution losses, and bullion grade improvement.

Jan 1, 1989

By R. R. Graham

Echo Bay Minerals operates a 650 tpd gravity float gold circuit at their Manhattan facility. The objective of this paper was to document the gold recovery by size distribution. This was accomplished by studying the material balance of each size fraction as it progressed through each gravity Circuit separator. It proved to be an impossible task. Figure I depicts the gravity circuit. The gravity cyclone underflow goes to two duplex Pan American type jigs. The jig overflow reports to the OK Flash Float Cell. The cyclone hutch product is reground and goes to a full size wilfly table. The rougher table concentrate reports to a pilot size Wi1fly cleaner table. The cleaner and rougher table tails circulate back to the jig feed. The gravity circuit was composite sampled for two to four hours per day for four days. Each sample was taken every 20 minutes. Each composite sample was filtered, dried, repu1ped, and screened through a wet/dry screening procedure. Each size fraction was checked for gold value by fire assay fussion technique. A material balance was run on each size fraction. The tables listing the results are enclosed.

Jan 1, 1989

By Axel J. Pollak

Since the late 1960's the Interstate Division for Baltimore City (IDBC) has been planning and developing the Interstate Highway System for the city to meet regional planning goals. The principal goals are to provide convenient access to the central business district and the port while diverting through traffic away from these congested areas. Interstate Route 95, an eight-lane highway carrying north-south traffic, has headed the city's priority list; during the 1970's its construction proceeded steadily from both east and west towards the harbor. Closing the final 8800-ft (2670-m) gap under the harbor will complete Interstate 95's construction. This final portion, known as the Ft. McHenry Tunnel project, will be built in nine construction contracts. Construction costs of the complete project are expected to exceed $700 million, making it the costliest single project in the Interstate Highway System. Full funding is being provided initially by the Federal Highway Administration (FHWA), and the Maryland Department of Transportation will re-pay the 10 percent local share from toll receipts within the first three years of operation.

Jan 1, 1989

By Mehmet F. Tauer, Pierre Trudel

"The metamorphosed mineralized Archean Bourlamaque batholith, dated at 2710 +-54 Ma, is a homogeneous body, composed mainly of quartz diorite; it is cut by late dioritic, mafic and aplitic dykes, and contains metasomatized ultramafic xenoliths. A geochemical investigation confirms the calc-alkaline affinity of the batholith, and the REE profiles are similar (Lal Yb = 3.9 to 8.1) to those of the intermediate to felsic metavolcanic rocks at Val d'Or into which the batholith was intruded and to those of the calc-alkaline members of the Blake River Group at Rouyn.Gold distribution within the batholith is heterogeneous and anomalous. Although the background Au content of the batholith is estimated to be 3.2 ppb Au by RNAA , the estimated median gold content of the batholith is 10 pp b (with P84 =32 and PI 6=3.1 ppb), much higher than that of ""normal"" granites (I to 5 ppb A u). The gold mineralization exhibits a close relationship with shear zones (e.g. Belmoral Mine) or with diorite dykes (e.g. Sullivan, Perron and Courvan mines).The following sequence of geological events is proposed: (I) pretectonic emplacement of the batholith, which is cogenetic with its volcanic host rocks; (2) regional metam orphism and deformation with localized shearing; and (3) hydrothermal alteration and quartz veining. We conclude that: (1) the Bourlamaque batholith is a gold-enriched intrusion, and (2) the determination of average gold content may be an effective method f or distinguishing ""sterile"" intrusions from those with potentials for gold mineralization.RESUMELe batholite archéen minéralise de Bourlamaque, daté de 2710+-54 Ma, est une intrusion homogène, constituée principalement de diorite quartzique, qui a été recoupée par des dykes tardifs de diorite, d'aplite et de composition mafique. Il contient aussi des enclaves de roches ultramafiques metasomatisees. L 'étude géochimique confirme le caractère calco-alcalin du bath olite et les profits des ETR sont semblables (La/ Yb=3.9 a8.1) a ceux des volcanites intermédiaires afe tsiques de la région de Val d'Or dans lesquelles le batholite fait intrusion et à ceux des unites calco-alcalines du Groupe de Blake Ri ver a Rouyn. La distribution de Au dans le batholite est à la fois anomale et hétérogène. Bien que le bruit de fond du batholite ait été estime à 3.2 ppb A u par AANR, sa médiane a été estimée a10 ppb Au (avec P84=32 et PI6= 3.1 ppb) , ce qui est nettement plus élevé que la valeur des roches granitoides ""normales"" donnée dans la littérature (1 a 5 ppb A u). Dans la batholite, la minéralisation aurifère est intimement associée aux zones de cisaillement (e.g. mine Belmoral) au aux dykes de diorite (e.g. mines Sullivan, Perron et Courvan).La séquence des évènements géologiques suivante est proposée: (1) emplacement pre-tectonique du batholite, lequel est cogenetique avec les roches volcaniques encaissantes; (2) deformation et metamorphisme regional avec des cisaillements tectoniques locaux; et (3) altération hydrothermale et développement des veines de quartz. Nous concluons que: (1) le batho lite de Bourlamaque est une intrusion enrichie en Au; (2) la determination de la teneur en Au peu être une méthode efficace pour distinguer les intrusions stériles de celles qui possèderaient un pot entiel pour des minéralisation s aurifères."

Jan 1, 1989

By Alizeibek Saleimen Nader

The intensive use of computers for mineral application at Serrana's phosphate mine in Jacupiranga, State of Sao Paulo, Brazil, began in the late seventies. The early hardware and software available are described in sufficient detail to allow comparisons between that solution and the new one, based on a personal computer and a new software package - PC MINE SYSTEM from GEMCOM SERVICES INC - that provides full color graphics capabilities plus mine design and planning tools. The process needed for adaptation to the new technology' and its impact on SERRANA S.A. DE MINERACAO are described. Finally, future enhancements to the System and mine control and planning are focused.

Jan 1, 1989

By Harold Kennedy

Take a good look at this issue of Minerals and Materials. This is the last issue of M&M, as it has been known within the U.S. Bureau of Mines, that you will receive. Fifteen years after it was created to help cope with a growing worldwide mineral shortage, M&M is ceasing publication. In its place will be a bright, new publication called Minerals Today. Like its venerable predecessor, Minerals Today will be a bimonthly magazine that reports on recent trends and issues in the minerals and materials industries. It will be the Bureau of Mines' most frequent periodical presenting an overview of the entire field of minerals and materials.

Jan 1, 1989

"The dust/lung research of the Center has several long-range objectives:* better methods for the early diagnosis of coal workers' pneumoconiosis (CWP);* methods to modify the disease process;* tests to identify toxic products; and* tests to identify individuals with heightened susceptibility to pneumoconiosis.A major immediate objective is to define the mechanism of dust-induced lung disease. This means determining:* dust characteristics that are important in causing lung diseases;* important interactions between dust and lungs; and* earliest detectable stages of the disease.Several of the Center's projects involve exposing lung cells in culture (in vitro) or animal lungs (in vivo) to samples of the suite of characterized mineral dusts described earlier. The responses of the lung cells or tissues to the dusts are being studied in order to better understand how inhaled dusts cause lung disease.One project is studying the effect of dust exposure on the production of mucus by rat tracheal explants in vitro. Mucus is a major factor in clearing inorganic dusts from the lung. Results thus far have shown that exposure of tracheal cultures to coal dust caused a decrease in micin production in comparison to parallel cultures without dust. To examine the effect of in vivo coal dust exposure, rats were maintained in an inhalation chamber for two weeks, and control rats were in an identical, but dust-free chamber. Tracheal explants results indicate that the effect of in vivo dust exposure is similar to that noted in the in vitro experiments.Pulmonary alveolar macrophages (PAMs) are a key component of the lung's response to inhaled particulates, and they play several important roles in pulmonary inflammatory and repair processes. PAMs are the cells that actually ingest dust particles. Other studies have shown that they play a critical role in the development of silicosis and asbestosis. The Center is studying the effect of dust exposure on the release of oxygen free radicals (superoxide) by PAMs. Intercellular production of superoxide occurs when PAMs phagocytize particles, such as inhaled bacteria, and is an essential mechanism by which PAMs kill ingested, bacteria. A number of complex physiological events occur during this process which are not clearly understood. It is thought that PAMs containing indigestible materials, such as mineral dusts, overproduce superoxide, or inappropriately release it into the surrounding tissues. If true, this would cause toxicity to surrounding lung cells by peroxidation of the lipids in the cell membranes. In vitro exposure of PAMs to low or high doses of kaolin is inert. Preliminary studies indicate that coating the quartz particles with a surfactant reduces toxicity."

Nov 1, 1988

By Timothy Green

El presente texto explica la historia, características complejas que intervienen en el desarrollo, producción, comercialización del oro. De otro lado, como consecuencia de la abundancia de este metal, se produjeron las "fiebres del oro", originando migraciones de muchedumbres a territorios vírgenes que estimulaban el rápido crecimiento de ciudades y comunicaciones.

Nov 1, 1988

"There is considerable evidence that all mine dusts do not present the same health hazard. Rank of coal and composition, especially silica content of the mine dust, shape, and surface charge are risk factors that affect the incidence and severity of CWP. Current efforts of Center researchers involve characterization of:•,size/shape/composition•,surface and functional groups•,particle interactions.Work is underway to prepare and characterize respirable coal dust samples, and to develop and evaluate techniques and procedures for the characterization of respirable dust. A suite of standard samples including anthracite, medium volatile and high volatile bituminous coals, quartz, clay, and rock dust have been prepared and thoroughly characterized with respect to the distributions of particle size and compositions. A comparison of the morphology of the standard dust particles with similar particles collected in an underground coal mine is given in Figure 43. Samples of these characterized (Standard) dusts have been distributed among various research groups associated with the Center.The aerodynamic diameter of a particle is a particularly important characteristic since this parameter determines the point of deposition in the human respiratory tract. A 3-dimensional numerical model for theoretically determining the equivalent aerodynamic diameter of irregular shaped particles has been developed and used to analyze coal dust particles and a particle shadowing technique has been developed for .experimental 3-dimensional shape analysis (Figure 44). In the theoretical technique, the equivalent aerodynamic diameter of the particle is numerically determined from computation of the fluid drag on the particle. This allows the aerodynamic diameter of any regular or irregular shaped particle to be determined as a function of the particle's orientation or as an average over all particle orientations. The technique is quite accurate in that the aerodynamic diameter of several coal dust particles have been numerically determined to be within 5% of experimentally measured values."

Nov 1, 1988

"The major thrust of this research is directed towards a better undstanding of the behavior of airborne dust particles in underground mine airways. Figure 61 shows a schematic of dust flow in mine airway. The work included development of a mathematical model of dust behavior in mine airways, experimental study of the behavior of dust clouds and comparison of computer model output and experimental results. Re-entraiment is a secondary source of dust in mine airways and factors affecting re-entrainment are being identified.Investigations have encompassed both experimental and theoretical research into the behavior of dust in mine airways. Experiments were performed in mine airways under both controlled and normal operating conditions (Figure 62). The controlled experiments included the documentation of the concentration and desposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using real-time aerosol monitors (RAM-1) (Figure 63).On the theoretical front, a convection-diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion. Comparative analyses of results of the controlled experiments with the predictions of the mathematical model were carried out. In addition to the overall validity, the adequacy of the individual components of the model, such as deposition in the total and respirable range, and dispersion were examined in light of the experimental observations."

Nov 1, 1988

"The Generic Mineral Technology Center on Respirable Dust was established in August 1983, at the request of the Bureau of Mines, to conduct research that affords ""...each miner the opportunity to work underground during the period of (his/her) adult working life without incurring any disability from pneumoconiosis or any other occupational disease"". The Center consists of the Mining and Mineral Resources Research Institutes (MRI) of The Pennsylvania State University (PSU) and West Virginia University (WVU) in association with the MRIs of the Massachusetts Institute of Technology (MIT) and the University of Minnesota (UMN). (FIGURE 34) Michigan Technological University (MTU) is also affiliated with the Center in the area of diesel particulates.The Center brings together experts concerned with particles causing potentially disabling or fatal diseases including pneumoconiosis (""black-lung""), silicosis, and asbestosis. The latter is of deep concern not just to workers in the mineral sector of the economy but also to the general populace. The primary goal of the Center is to reduce the incidence and severity of respirable dust disease through advancing fundamental understanding of all aspects of respirable dust associated with mining and milling, and the interaction of dust and lungs. The research program of the Generic Mineral Technology Center explores these scientific, engineering or medical concerns with the objective of refining existing strategies and developing new respirable dust control techniquesand technology that are consistent with the fundamental dust-lung interaction processes that lead to mine worker disability. The work concentrates on five areas (FIGURE 35):"

Nov 1, 1988

"Health standards in the U.S. are among the highest in the world. Achieving these standards have often had an impact on productivity, slowing output, and raising prices to levels that make it difficult to compete with many foreign industries. The answer to many of these problems lies in the development of new and advanced control techniques. This overview has identified some of the major respirable dust technological hurdles that have been overcome, and provided some insight into current and future approaches underway to remove these obstacles and to provide the United States with the most advanced state-of-the-art mining industry in the world from a respirable dust standpoint. The necessary developmental research is costly and time-consuming. The long-term, high-risk aspects of this effort are being addressed by the Bureau and the Generic Center on Respirable Dust, with support by industry. This should be recognized as one of the principal agents through which the great mineral potential of this Nation can be realized, and our international status as a mining power be assured without compromising the health and welfare of those who ensure it.The problem of more stringent dust standards will continue to grow. To date, approximately 40 pct of the coal mining industry has been placed on more stringent dust standards due to quartz. Control techniques must be improved if mandated levels are to be met. As longwall production increases, dust levels will also increase. In light of the industry trend toward longwall mining, if no new control technology is available, the Federal dust standard will act as a constraint on future output per hour. The Bureau has recently completed a survey of 18 coal preparation plants; 50 pct of these operate at dust levels which exceed 2.0 mg/m3; future work will be directed toward solutions in this area. The 2.0 mg standard for respirable dust is for dust particles which are below 10 pm in diameter. Recent studies have shown that dust in the range between 10 and 25 pm can cause obstructive airway disease. The Bureau is currently determining the extent of exposure to dust in this size range from various mining operations."

Nov 1, 1988

"The main objective of this research is to identify the mechanisms of control of respirable dust generation in coal mines. Full understanding of the mechanics of crack propagation in coal is of fundamental importance in studies of the generation and control of respirable dust.The main objectives of this fracture investigation are: 1) to determine reliable data on the fracture toughness of coal as a parameter controlling unstable crack propagation; 2) to determine fracture propagation velocity in coal providing data on the terminal velocity at which crack bifurcation occurs and fine fragments of coal material are generated; and 3) to apply the critical strain energy density criterion to model mixed mode crack propagation in coal.The development of the protocol, laboratory procedure and equipment necessary to conduct an extensive mixed mode fracture toughness testing program has been completed. About 80 mixed mode fracture toughness tests, 10 good fracture velocity records and over 50 fracture surface examination with the SME are available. The details of the mixed mode fracture toughness testing are available in a paper titled, ""Development of Mixed Mode Testing System for Geologic Materials"" which is available from the center. The average fracture toughness and critical strain energy density values for the three seams investigated to date are included in the attached Figures 71, 72, 73."

Nov 1, 1988

"In sum, significant benefits to mine worker health have resulted and should continue to result from the synergistic scientific, engineering, and medical research in respirable dust. As always, an important objective is the rapid dissemination of the results of this research to industry. Video tapes and the Technology News series published by the United States Bureau of Mines (USBM) have been a very effective means of technology transfer. Individual no-cost subscriptions to the Technological News series are available from the Bureau of Mines, Branch of Technology Transfer, 2401 E St., N.W. Washington, DC, 20241.Two respirable dust conferences have been jointly sponsored by the Center, USBM, NIOSH, and MSHA. The proceedings from these conferences are titled:1. Coal Mine Dust Conference held in Morgantown, West Virginia on October 8-10, 1984 and2. Respirable Dust in the Mineral Industries: Health Effects, Characterization and Control held in University Park, Pa. on October 14-16, 1986.Copies of the proceedings from the first conference are available from the National Technical Information Service (NTIS):National Technical Information Service5285 Port Royal RoadSpringfield, VA 22161NTIS # PB86-169380Telephone Number: (703)487-4650Copies of the second conference proceedings, ISBN: 0-936712-76-7 (publication #3010), are available from ACGIH by writing toWilliam D. KelleyExecutive Director, A.C.G.I.H.6500 Glenway Avenue, Building D-FCincinnati, Ohio 45211Telephone Number: (513)661-7881During the period 1984-1987 more than sixty-four (64) papers and publications have been produced by the Center researchers. These publications have appeared in scientific journals and have been presented at national and international symposiums and meetings. A list of these papers, organized by topical headings, has been included in this publication.The generic center maintains a reference center that serves as a clearinghouse for technical information for the generic area and supplies reports on generic center accomplishments."

Nov 1, 1988

By Robert A. Jankowski

"Following passage of the Coal Mine Health and Safety Act of 1969 (Public Law 911173), the Bureau of Mines initiated a research program aimed at controlling respirable dust exposures of coal mine workers. Respirable dust is the dust that gets into, and interacts with, the lungs of those who inhale it. It has long been recognized as a severe health hazard to mine workers. This program has been implemented by a team effort consisting of the Bureau's in-house capabilities, the Generic Center for Respirable Dust, and contractors, as necessary. Over the years, Bureau research has addressed principally three areas:o Compliance with the Federal 2.0 mg/m3 dust standard (1970-76).o Dust control for longwall mining (1976-1983).o More stringent respirable dust standards due to quartz dust (1983-1987).In addition, fundamental studies have been conducted by the Generic Center for Respirable Dust, with emphasis on penetration of dust into the lung. Accomplishments have been significant, but problems remain, as noted later.The Coal Mine Health and Safety Act of 1969, established a 2.0 mg/m3 dust standard for all coal mining operations, underground as well as surface. At the time of enactment of this legislation, the industry was averaging approximately 4.0 mg/m3. The Bureau of Mines respirable dust research program played a significant role in identifying and developing effective technology to allow better compliance with this new standard, thanks to industry implementation and Federal enforcement."

Nov 1, 1988

"It is evident that the incidence of coal worker's pneumoconiosis (CWP) or black lung disease varies in different coal producing regions of the United States. Many people have hypothesized about the reasons for the differing occurrences. Because underground coal mining involves many mining methods under changing geological conditions, several factors may be involved in contracting CWP such as: the amount of quartz in the respirable dust, the trace elements in the respirable dust, the rank of the coal that produced the respirable dust (bituminous, anthracite), the amount and size of respirable dust, etc.Recognizing the uniqueness of underground coal mining and CWP, research investigations involving seam characteristics, mining system and worker position are being conducted in the center to establish standard procedures for characterizing some coal properties that may be involved in workers contracting CWP. This has been accomplished by the in-mine sampling of airborne dust at various worker locations and mining system configuration and by performing laboratory analyses of mined material (coal and rock) taken from the mines. (FIGURE 49 and 50)The investigations includes a method of classifying coal seams according to their potential to generate respirable dust. It includes statistical analyses of the size and locational variations of the elemental compositions of respirable coal mine dust in operating underground mines from seams located in the eastern, midwestern, and western United States, and is currently completing research which is investigating the relationship between the elemental compositions of respirable dust sampled near a continuous-mining machine and a laboratory-produced respirable dust."

Nov 1, 1988