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A viable flow sheet of the sorption-flotation technology for gold recovery from low-grade ores and concentrates using powdered activated carbon modified by organic compounds as the sorbent-bearer has been developed. The powdered activated carbon, with high kinetic ability and sufficient specific area, was selected as the all-purpose gold cyanide complex-bearing sorbent which is active during flotation. To improve carbon adsorption capacity and to provide the required floatability its porous structure was filled with a quaternary ammonium compound which can extract gold cyanide complexes and render additional flotation properties to the carbon. To optimise the process and to simplify the layout, adsorption and flotation processes were carried out simultaneously in a mechanical flotation cell. The proposed technology was used for extended and pilot-plant tests of sorption-flotation gold recovery from 0.6 g/t Au final tailings and 2.0 g/t Au gravity tailings. The extended tests were carried out on Taseevskaya (Chita Region) flotation tailings, whereas pilot-plant tests were conducted on Kommunarovskaya (Krasnoyarsk Region) gravity tailings passing to cyanidation, followed by processing with filtration technology. Additional gold recovery from Taseevskaya final flotation tailings was 50.8 per cent. Gold recovery from Kommunarovskaya final gravity tailings was 92.5 per cent. Compared to the complete sludge process conventionally used at the plant, gold recovery was increased by 7.5 per cent due to lower gold losses in the liquid phase and conversion of the refractory non-cyanided metal into a carbon concentrate. This paper presents the experimental results of gold adsorption onto powdered activated carbon modified with quaternary ammonium compounds (sorbent-bearer) as well as sorbent-bearer flotation with various collectors from cyanide solutions and pulps.

Jan 1, 2005

By Nick Rose, Mathieu Veillette, Matthew King

"The Teck Highland Valley copper (THVC) mine is located approximately 55 km (34 miles) southwest of Kamloops and approximately 20 km (12 miles) west of Logan Lake, BC, Canada (Fig. 1). Mining at THVC is conducted at three openpit operations comprised of Valley, Lornex and Highmont with a total annual output on the order of 300 kt (330,000 st) copper concentrate and 5 kt (5,500 st) of molybdenum concentrate. The Phase 8 pushback in the Valley Pit (Fig. 2) was mined from 2011 to 2016. Successful slope steepening occurred in the later stage of the pushback with the implementation of presplit blasting in 2015 and 2016.This article summarizes the investigation and design approach including: structural analysis, kinematic assessments of bench breakback potential, development of discrete fracture networks (DFNs) to characterize discontinuity fabric, rockfall modelling, 2D anisotropic limit equilibrium and 2D distinct element modelling, assessment of potential kinematic failure modes affecting double benches with 3D distinct element modelling and improved blasting techniques using e-dets. THVC is currently undertaking a mine life expansion involving the pushback of the west wall of the Valley Pit above Phase 8 to extend the mine life to 2029. Engineering geologyThe east wall slope in the Valley Pit is comprised of a 350-m (1,148-ft) thick sequence of glacial valley sediments that occur along the Highland Valley (Fig. 2), exposing an overburden slope up to about 225-m (740-ft) high below the crest of the ultimate east wall. The glacial overburden units consist of pro-glacial outwash and glaciofluvial deposits, glacial outwash sands and gravels interbedded with till and alluvial fans consisting of cross-bedded sands and sandy-gravels. Lacustrine sediments occur within the mid to lower portion of the glacial sequence and contain intervals of low-shear-strength clays and silts. Two large (1.3 and 7 Mt or 1.4 and 7.7 million st) waste rock buttresses were required to maintain slope stability using slot-cut and fill mining methods, as described in Fortin et al. (2011).The Valley porphyry deposit occurs in the central portion of the late Upper Triassic Guichon Creek Batholith, which intrudes assemblages of the Permian Cache Creek and Upper Triassic Nicola groups. The Valley deposit occurs in an area of intense fracturing near the intersection of the northerly trending Lornex Fault and the northwest to westerly trending Highland Valley Fault."

Apr 1, 2019

By A. H. Sharbaugh

It is believed that considerable economic benefit would arise if run of mine (ROM) coal from the underground mines in the Winifrede seam could he enriched before shipment to the preparation plant by partial removal of the shale. Shale could comprise up to 50% of the ROM product. Complete mine-mouth separation is not necessary, but any process must be dry and have high Btu recovery. We have conducted a preliminary analysis of coal/shale mixtures from the Winifrede seam and we find that it is quite possible that a 50-50 ROM mixture of coal and shale could be converted to a 60-40 coal-shale mixture by inspection of individual lumps coming from the mine. The device would consist of a feeder/siever section to deliver the ROM coal > 5 cm (2 in) to an inspection station via a conveyor belt. This inspection station decides if a piece is coal or shale, and if it is shale, activates an air jet to blow shale off of the belt. We have evaluated a dielectric loss technique for the inspection device. The potential advantages of the dielectric loss method are high throughput, low capital cost, and no special handling or licenses would be required. Such a single lump inspection technique is made possible because of advances in high speed electronics and servo systems. This paper provides a summary of our analyses on the Winifrede coal sample, a description of a proposed apparatus to separate coal from shale, some of the experiments needed to demonstrate our ideas.

Jan 1, 1984

By S. H. Lorain

This paper is one of a series on mining methods and costs being published by the U. S. Bureau of Mines. The operations of the Quartz Hill Mining Co., near Dewey, Mont., afford an interesting example of the cost of mining small bodies of direct shipping ore; they also illustrate the effect of the unavoidable periods of unusually high exploration and development costs in this type of mining upon the cost per ton of producing ore. The importance of skilled geological guidance and the necessity of avoiding unnecessary overhead and capital expense at small mines are shown. Operating conditions at Quartz Hill are typical of those in many other mining districts of southwestern Montana. It is believed that the costs presented here may be of value in the preliminary estimation of costs to be expected by conservative operators under similar conditions elsewhere. The information contained in this paper was obtained during a visit to the Quartz Hill mine in August 1936.

Jan 1, 1937

By Walter K. Utt

The vibration levels of the heavy machines used in surface mining are much greater than for vehicles used on highways. In order to assure the proper functioning of electronic equipment placed on the surface mining vehicles, the U.S. Bureau of Mines has conducted a program of field measurements to define their vibration environment. The information in this report is for a class of vehicle that has a blade for scraping and wheels with rubber tires. The statistical information derived from these measurements can be used as a basis for laboratory testing to qualify equipment for a surface mining vehicle of this class. The envelope that would encompass 99 pct of the vibrations encountered in normal operations is presented for each location on the vehicle. The five locations for which data were recorded are the floor of the cab, the engine, the frame, the drive train (gear, differential, and torque converter), and the axle. Tabulated data are provided for those who wish to use a different probability level. The appropriate test profile for the laboratory testing can be determined from the information presented in this report.

Jan 1, 1993

By Silas C. Nichols, Jennifer E. Nicks

"Limit states design (LSD), or load and resistance factor design (LRFD), is a method to account for the uncertainty in loads and resistance through a reliability calibration that requires all applicable limit states (strength, service and extreme) to be checked during foundation design. LRFD has been in use internationally for several decades; however it wasn’t until recently that engineers working on highway projects were required to use the method for the design of highway bridges and other appurtenances. Although the bridge community has been using a form of limit states design for structural components since the early 1970s, the design of foundations for bridges, walls and other geotechnical features had long been performed using allowable stress design (ASD), whereby all uncertainty in loads and material resistance is combined in a single factor of safety. While the move to LRFD was viewed as a more rational approach for the design of bridges and structures, the transition to its use for geotechnical engineering has been met by many with confusion and difficulties in application. This article will revisit the history of transition from ASD to LRFD for geotechnical engineering, summarize the status of the transition and issues with its use, and briefly discuss some emerging research opportunities for improving and advancing the design platform.Background and HistoryUntil about a decade ago, foundations and substructures for bridges were traditionally designed using ASD, while the superstructure was designed using load factor design (LFD), a precursor to LRFD that incorporated factored design loads but no risk assessment. This combination led to uncertain and incompatible safety margins in design for the various bridge components. In 1986, the American Association of State Highway Transportation Officials (AASHTO) Subcommittee on Bridges and Structures (SCOBS) concluded that the standard bridge specifications in use at the time for U.S. transportation projects had significant inconsistencies and gaps, wasn’t up to date with emerging technology and that the development of new specifications was warranted. The proposed solution by the subcommittee was to transition to a more coherent method of design where applicable failure and serviceability conditions could be evaluated considering the uncertainties associated with loads and resistance."

Jan 1, 2015

By M. Z. Emad, M. U. Khan, A. ur Rehman

Stemming plugs are used as an accessory in drilling and blasting industry. They supplement conventional stemming material (i.e. drill cutting) with retention of gases in the drill hole that result in better fragmentation of rock and improved explosive utilization. Better fragmentation and explosive utilization along with economic benefits enhance efficacy of the project. Incorporation of stemming plugs in drilling and blasting industry is in exercise for about thirty years. The efficiency of stemming plugs is a key factor in their rising induction in mining industry. Different studies have been conducted on the economic viability of these plugs. The focus of this paper is the selection of stemming plugs for a bench blasting operation and the examination of blasting operation efficiency based on ergonomics and human factors. Three types of stemming plugs were evaluated during multiple blasts at a limestone quarry. Their performance was evaluated using split desktop software. Based on the human factors plastic molded stemming plug (stemming plug-1) was found to be the best among all selected plugs. INTRODUCTION Surface mines and quarrying operations heavily depend on bench blasting to achieve high volumetric targets and production demands. Use of explosives is the most economic method adopted for rock breakage and movement. Extensive research had been performed to enhance explosives energy utilization. This include changing the drilling pattern, application of air decks, stemming plugs, and use of other supportive devices. Optimization of explosive energy has been a major concern in those mines that rely on drilling and blasting operation to carry out main production. Due to continually increasing cost, efficient mining demands, and associated hazards of using explosives, it is necessary to utilize explosives at their best. Efficiency of a blasting operation is generally evaluated by the fragmentation size. From post blast conditions at blasting site to efficiency of processing plant, anything can be affected due to improper blast resulting in bad fragmentation. Better fragmentation is necessity for better operation of the system along with consideration of the safety of operation, environmental issues and related costs. For developing a blast design, an engineer should always attempt to minimize the cost of operation without compromising with acceptable technical and safety necessities [1]. Blast performance is dependent on many different factors associated with the process. These factors have been gauged as blast geometry, explosive specification, and rock mass properties [2]. Similarly, in 2013 Mohammad et al. concluded that fragmentation dynamics depends on blast hole diameter, primer, spacing, stemming, burden, and delay timing for blasting operation [1]. At the work site where this study was performed, blast holes were filled by drill cuttings and muds to help in confining gases. In a blast hole, gas confinement helps in better rock fragmentation along with reduced flyrocks. This practice is most common in many countries including Pakistan. Due to lack of homogenized particle size, the effectiveness of confinement is variable and majorly based on the size of stemming. Extremely small sized drill cuttings often result in hole blow out along with flyrocks from the collar. This improper blast energy will result in poor blast, bad impacts on environment, and reduced operational efficiency. In addition to the stemming material, the length of stemming is also a prime consideration. The decrease in stemming length will increase the quantity of explosive in the blast hole and an increase in stemming material generally improves stemming performance.

Jan 1, 2019

By O. Lashkari

Manipulation of pouring temperature is an efficient way to produce different microstructural features. In order to characterize the microstructure of rheocast billets due to different superheats of 615-695 °C, the parallel plate compression method was employed. Foundry 356 Al-Si alloy with different morphologies of primary a-Al particles were tested at different initial pressures of 4,8, 11,2 KPa, The resulted strain-time graphs were further treated mathematically to calculate viscosity of SSM billets. The interrelationships of viscosity, the microstructure and primary phase flow during compression are discussed, It is shown that the dendritic primary a-Al structure has the highest viscosity number which is almost three orders of magnitude greater than those for globular morphology, The current research have, for the first time, shown the validity and reliability of "parallel plate compression viscometry" method in characterizing microstructural evolution of Rheocast SSM billets.

Jan 1, 2005

By Sarah Beutner Mavrogenes

The mineralogy of three slags from a domestic secondary copper refinery were studied by applied mineralogical techniques to determine the: 1) phases present, 2) phase chemistry, 3) phase abundance, 4) associations, 5) crystalline habit, 6) grain size, 7)microtextures, and 8) causes for certain metallurgical problems, such as metal losses to the slags. The slags were produced by skimming the bath prior to melt-down to allow heat from the flame to reach the bath. The first slag is highly viscous and all three slags contain a large amount of copper. The "first slag", which is skimmed prior to treatment of the bath with fluxes, contains metallic copper, cuprite, delafossite, magnetite, Mg-hercynite, common spinel-chromite solid solution, picrochromite-chromite solid solution, common spinel-picrochromite solid soiution, gahnite, cassiterite, silica-rich glass, and corundum. Its abundant solid refractory phases make the slag difficult to skim. The "soda-rich slag", skimmed after the treatment of the bath with sodium carbonate flux, contains cuprite, delafossite, magnetite, cassiterite, Na-Al-silicate, and Na-Al-Ca-silicate. It contains less metallic copper than the first slag and lacks the refractory minerals. The "phosphorus-rich slag", skimmed after treatment of the bath with a copper phosphide flUX, contains metallic copper, cuprite, delafossite, berlinite, cassiterite, silica, apatite, Cu-Fe-rich apatite, copper phosphate, Cu-Fe-phosphate, and a Pb-phosphate. In contrast to the above three copper-rich slags, recent charges have produced a silver-copper-rich slag. The "silver-rich slag", skimmed after the treatment of the bath with a copper phosphor ide-borax flux, contains, cassiterite, delafossite, cuprite, a Na-Al-silicate, magnetite, metallic copper, MgO, common spinel-chromite solid solution, and wollastonite. Silver ranging from 0.05 to 2.02% was found by atomic absorption and inductively coupled plasma spectrometry analyses in the metallic copper phase.

Jan 1, 1989

By Douglas A. Elkins

The unique characteristics of plasmas, their current applications, and ongoing research into new applications are described. Major technical and economic problems in application of plasma technology are discussed. Examples of potential applications of plasma in extractive metallurgy are described and evaluated. The report includes a selected bibliography of articles on plasma and related high-temperature technology.

Jan 1, 1969

By Gordon Jackson

"There are two accomplishments of air and gas drilling: a new series of economic and mechanical challenges; and, acceptance as a standard drilling and completion tool.The new challenges are related to the concept of using a gaseous circulating medium in drilling for oil or gas. For purposes of discussion, a two part division has been made: the challenge of fluid invasion control and that of equipment and tools. Great strides have been made in the development of materials and techniques to combat formation fluid invasion. Chemicals and the ""mist drilling"" technique, now in use, have the versatility to cope with a wide range of downhole fluid entry conditions.Equipment and tools have been developed to meet the challenges of better, more economic drilling and completion possible with a gaseous circulating fluid. Economic and operational challenges remain.Acceptance of air and gas drilling as a normal operating tool was reached with difficulty. It is now established as a means of reducing costs in exploratory and develop-mental well drilling, exemplified in a recent study of 226 wells covering 419,407 feet of hole in the United States. Air reached the projected depth in 85 per cent of the operations, although formation water was encountered in 48.7 per cent of the holes. Slim hole bit performance and cost all compared for overall bit averages as part of analysis."

Jan 1, 1961

By William J. Schloemer

INTRODUCTION The history of coal mining the Ostrava Region of the Czech Republic goes back nearly 250 years. Both coking coal for steelmaking and thermal coal for the production of energy are mined here; however, it was the coking capabilities that subsequently turned the region into a major steel-producing area in the early 1800?s, something that continues to this day. Ostrava lies in the northeast corner of the Czech Republic, near the southern border of Poland, and falls within the Upper Silesian Coal Basin. The region contains over 400 seams of coal of which about 150 have been mined over its history and continue to be mined. Eighty percent of the Upper Silesian coalfieldlies in Poland and is presently mined by about 35 coal mines; the remaining 20% falls in the Czech Republic, which presently has four mines operated by OKD, a.s., a subsidiary of Amsterdam-based New World Resources. Traditionally, all the mines in this region have employed the longwall method of mining, of which subsidence is an unavoidable consequence. In fact, due to the long history of longwall mining here, there are areas where the overall subsidence has exceeded 37 meters (121 feet). The region is fairly densely populated with residences and industry, and a considerable amount of coal lies under some of these areas where subsidence is not allowed or has to be minimized. It is this reason that has driven OKD to consider alternate methods of mining that will not create subsidence. The decision was made to consider the room and pillar method of mining in order to leave stable pillars of coal to support the surface. After considering several locations, OKD chose the shaft safety pillar at the CSM mine as a test mining location. To say the least, this is a very challenging location in which to conduct a test. As with the entire region, there are many faults from tectonic activity, the seams are pitching at 12 to 20 degrees, the area is affected by high horizontal stress, and the depth of 750 to 900 meters is perhaps the deepest room and pillar coal mining ever attempted.

Jan 1, 2014

This paper reviews recent advances in geophysical tools for mineral exploration. It does not restrict comments to methods which are usually applied in the tectonically active belt surrounding the Pacific Ocean, where geophysics has often been secondary to geological prospecting (eg visual recognition of surface alteration) and drainage geochemistry; but considers geophysical tools applied to a broader range of both deposits and terrains. For example, the subdued topography of much of Australia and Canada has lent itself to the development and extensive application of airborne methods. In Australia, deep weathering and transported cover have necessitated the use of geophysical methods to not only detect anomalies but also to map and understand basement geology. This same weathering has caused specific problems, particularly for electrical methods, but recent improvements in instrumentation, processing and visualisation have largely overcome them. A great deal of geophysical data is now being collected by government agencies, often from the air, and made readily available to explorers. In several Australian states it is free, often on line, and in almost all cases it is relatively cheap. These regional data sets are often augmented by more detailed local surveys in areas of interest. Although æanomaliesÆ are still important much more is being done with the high quality data which is now available The results are used for geological mapping, to test geological hypotheses, to construct detailed 3D geological models and, together with fluid flow modeling, to predict optimum locations for mineralisation.

Jan 1, 2004

By J. W. Ahlrichs

In gold exploration and metallurgical testing, the role of the mineralogist is to assist in solving problems with regard to (a) sampling, (b) gold occurrences, and (c) petrologic classifications of host rocks. The presence of "coarse" gold as a sampling problem can be overcome by various methods, including "screen fire assays," screened analyses and special gravity techniques which may be used to determine distributions of "coarse" versus fine gold. Determinations of mineralogic associations of gold usually require special separation techniques, accompanied by fire-AA-mineralogic assays of the products. After accurate mineralogic analyses are obtained for various products, quantitative distributions of refractory gold associations can be calculated by the use of simultaneous equations. Petrologic classifications are required by the geologist for mapping and interpretation of the various rocks. After the petrology and mineralogic differences of the rock units are determined, x-ray diffraction analyses of analytical pulps can be used for lithologic logging of drill cores. XRD logging is an efficient method for correlating lithologic units and alteration trends throughout a gold prospect.

Jan 1, 1981

By Rodney R. Krause

In attempting to tell the general public about the coal industry's land reclamation efforts, we have often said, "We're not doing things by the book, because we're still writing it." Like any good catchphrase, the statement is not only striking but true. It is particularly true in the mountains of Appalachia, where the problems of mining; and of reclamation are made more intense by the nature of the terrain. Mining and reclaiming the land "by the book' --which is to say by the methods of contour mining traditionally used in hill country--hasn't worked too well. So a lot of conscientious coal operators and associations are trying new methods--new ways of mining, new machines for seeding and planting, and new species to seed. Not all their experience can be transplanted to other areas, and of course I don't believe that Appalachia is the only place where new methods are being developed. Nevertheless, there's enough action in Appalachia to make a detailed examination rewarding, so let's focus on the hills to see what's new.

Jan 1, 1970

By Thomas R. Wildeman

Experimental methods for studying vapors over solid minerals are reviewed and an especially developed method using atomic absorption is described. The method is used to study vapor pressures over Te. Ag, Au, Ag2Te, and AuTe2 from 250°C through 10S0oe. Vapor pressures observed and, concurrently. sintering properties are significantly altered by the form of the solid. The vapor pressures of the tellurium compounds reveal complex processes occurring on the surfaces of the solids. The data given also point out a method of recovering precious metals from their telluride minerals w

Jan 1, 1987

By Bawden WF, Paynter JT

This investigation involves laboratory testing and stability analysis of paste fill at the Golden Giant Mine. Site-cast samples are tested in unconfined, confined, and consolidated-undrained triaxial compression. Pore pressures during shear and consolidation characteristics are measured to determine both drained and undrained shear strength parameters and assess the potential for undrained loading. Liquefaction potential is also considered. A limit equilibrium solution is used to obtain factors of safety against failure of the fill during mining of adjacent stopcs

Jan 1, 1998

By R. V. Ramani, R. Bhaskar

"The results .of an experimental and theoretical research study into the spatial and .temporal behavior of dust in mine airways is summarized in the paper. Experiments were performed in mine airways under both controlled and .normal operating conditions. The controlled experiments included the documentation of the concentration and deposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using Real-time Aerosol Monitors (RAM-1) to determine the dispersion coefficient in a mine airway. 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.In this paper, comparative analyses of results of the controlled experiments with the predictions of the mathematical model are presented. 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 are examined in light of the experimental observations.The experimental data from controlled experiments compared more favorably with model predicted results for similar conditions as opposed to the ·comparative analysis results for in-mine experiments. Specifically, the model· predictions for an 800-meter stretch of a mine airway reveal some significant differences from the behavior noticed in the mine. The deposition was lower than that predicted by the model. Consequently, concentrations were higher than those predicted by the model. The implications of these and other findings for further investigations are discussed in the paper."

Aug 31, 1989

By G. G. Krishna Murthy

Interactions of wustite and hematite pellets with Fe-C melts were investigated experimentally by examining the effect of pellet size and bath temperature on the reduction rates of the pellets. Experiments were carried out in the temperature range 1473-1923 K. A flash X-ray equipment was used to obtain images of the melt surface during its reaction with an oxide pellet. The reduction rates were calculated using experimentally estimated time for complete reaction of a pellet, tR. The value of tR was determined employing gas mass flow rate, or pressure rise in the sealed furnace, versus time traces. The value of tR was the same for both wustite and hematite pellets of equal weight at or above 1723 K and it decreased with increasing melt temperature. But the reduction rate was substantially lower at temperatures below 1651 K, the melting point of wustite. The rates were defined as the rate of moles of oxygen removed from the pellet per unit area of bath free surface and it was found that the bath surface area affects the reduction rates. It was established that the overall reaction followed nth-order rate kinetics with the values of n falling between 0.3 and 0.4 for temperatures above the melting point of wustite. The apparent activation energy determined using the apparent rate constants obtained from the experimental data was 76.2 + 27.7 kJ/mol-O.

Jan 1, 1992

By J. F. Burr, D. P. Snyder, G. W. Luxbacher

"The Mine Improvement and New Emergency Response Act (MINER Act) of 2006 established the Office of Mine Safety and Health (OMSH) within NIOSH and provided authority for awarding contracts related to the development and implementation of new mine technology and equipment. Subsequently, Congress provided additional funding to NIOSH to initiate and continue the program. OMSHR has fulfilled this Congressional mandate through annual Broad Agency Announcement (BAA) solicitations, directed Requests for Proposals (RFP) and Inter-Agency Agreements (IAA), and has further expanded the program through capacity building BAA contracts with U.S. university mining departments in the areas of mine ventilation and ground control. This paper describes the extramural funding program and broadly examines the results of the 150+ contracts issued to date, grouped into key focus areas. INTRODUCTION The Mine Improvement and New Emergency Response Act (MINER Act) of 20061 established the Office of Mine Safety and Health Research (functioning as the Office of Mine Safety and Health Research or OMSHR) within the National Institute for Occupational Safety and Health (NIOSH), and provided authority for awarding contracts related to the development and implementation of new mine technology and equipment. The OMSHR external contracts program was formed in accordance with the MINER Act and has since issued over 150 contracts focused on worker health and safety. Initial funding for this program was provided by Congress through two Emergency Supplemental Appropriations (ESA) and was focused on emergency oxygen supply, communications and tracking, and refuge chambers (also referred to as refuge alternatives). Since the MINER Act, Congress has continued to fund the program through the annual NIOSH mining appropriation. The program was supplemented starting in 2009 with an academic capacity building program directed toward developing university tenure-track faculty and facilities and supporting graduate students in the area of mine ventilation; ground control was added as an additional focus area in 2011. A short synopsis of each contract is published on the NIOSH Mining website2 and final reports are available in digital form on request. A summary of the progress OMSHR has made over the 10-year period since the Act was published previously.3"

Jan 1, 2018