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In 2007, a total of 7,199 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 ? Sand and gravel mines were the largest mining sector, comprising 48.4% of all mining operations. ? Sand and gravel mines were found throughout all 50 states and Puerto Rico.

Aug 1, 2009

By François Robert, Steve Green, Tyson Birkett, Dan Richardson

Abstract -Detailed sampling using a portable diamond drill, and interlaboratory comparison of selected samples have been combined with statistical studies of truncated populations to establish the gold content of several outcrops in the Val d'Or area. The outcrops chosen are non-mineralized. The background gold concentration in the rocks of the region is 5 ppb or Jess. Gold is distributed relatively homogeneously within the outcrops studied except for slightly increased concentrations within quartz-tourmaline veinlets. Three samples, of which 20 grams of powder are analyzed for each, can adequately determine the gold concentration of a structurally simple outcrop in the Val d'Or area.

Jan 1, 1992

By Madgwick J. C

The monosaccharides glucose, galactose and arabinose, and the polyols glycerol and mannitol (0.1 Ufo WIV) supported pure and mixed culture heterotrophic bacterial manganese leaching of solid pyrolusite (MnO2, 2% W/V) to yield 14-38 mg/litre manganous ion in 3 days from a simple mineral salts media at 30°C. Supplementation of pure bacterial isolates growing on glucose with soluble intracellular photosynthate from freshwater algae (0.07 g/l carbohydrate) and marine algae (0.11 g/l) led to an improvement in Mn++ yields of 24 and 100 per cent respectively. Extracellular products of the freshwater algae (0.3 g/l carbohydrate) boosted recoveries by 57 per cent.

Jan 1, 1982

Domestic production of pyrite cinder reached 15.95 million tons in 2006. The pyrite cinder used in cement industry accounts for about 30% production. The remaining 70%, 11.17 million tons, was thrown away as waste, which brought serious environmental and resource problems. A new technology of composite pellet reduction-roasting and magnetic-separation (CPRM) has been developed to utilize pyrite cinder. Pyrite cinder sample, containing 45.56% Fe, 0.19% Cu and 1.45% S, was pelletized with addition of 5% composite agent in balling disc. Green balls after drying were reduced at 700~800 ? for 20min with 300kg/t pulverized coal injection in rotary kiln. After two stages of ball-grinding and four stages of magnetic separation, high grade magnetite concentrate with 66.23% Fe was produced, meanwhile impurities Cu and S was decreased to 0.048% and 0.053%, respectively. And iron recovery of 73.32%, desulphurization of 96.34% and decoppering degree of 74.73% were achieved. Key technique is that composite agent can accelerate reduction of Fe2O3 and transfer copper and sulphur into water-soluble inorganic salts, which can be removed during wet magnetic concentration. This new technology can be used to fully utilize pyrite cinder and produce high quality magnetite concentrates as feed for steel industry, which will help tackle the pollution problem of pyrite cinder and extend iron-bearing raw material sourcing for Chinese steel industry.

Jan 1, 2014

By Tatiana Kotrikova, Steven Kolarz, Alan Kolodne, James Parkes, Matthew Goff

The WMATA Yellow Line is the section of steel segmentally lined tunnels that have experienced leakage and significant corrosion in isolated areas. A three part rehabilitation design has been developed for curtain grouting, structural repairs, and corrosion protection to provide continued performance. As WMATA’s first Construction-Manager-at-Risk (CMAR) project, the design development benefitted from collaboration with the Contractor through the final design development process. Rehabilitation work started in Fall 2022 and will be completed by late Spring 2023. Details of the project, the remediation design, and the process and benefits of the CMAR approach in the design development are presented.

Jun 13, 2023

"Decreasing gold-in-ore grades is one of the main drivers of poorer productivity and rapidly escalating unit costs. Grinding costs, water use and reagent consumption are all intimately related to the ore grade processed. Various pre-concentration technologies have been developed that can be applied at various stages of crushing prior to ore grinding. This paper will review the amenability of ores to coarse particle barren gangue rejection for fine crush sizes in the pumpable particle size range (i.e., particles between 5 mm and 0.3 mm in size). The liberation of oxide gangue achieved during crushing is evaluated by proxy using sink-float analysis and the deportments of gold, sulfur, and arsenic into sinks and floats are monitored. Amenability of gangue rejection by continuous gravity separation is evaluated after various crushing modes (vertical shaft impact crushing, cone crushing, and HPGR crushing). The potential to identify coarse particle mineral association and liberation using three-dimensional x-ray computed tomography will be discussed.INTRODUCTIONThe aim of research in this area is to explore some of the attributes which make some ores amenable to preconcentration, or rejection of a significant component of the feed mass to tailings at a coarse liberation size. Characteristics such as ore type, mineralogy, breakage pattern, particle shape, and liberation characteristics may need to be examined to identify amenability to pre-concentration amenability.It is intended to focus on continuous gangue rejection in the pumpable size range (0.3–5.0 mm) as this remains one of the key opportunities to reduce processing costs through a combination of techniques including screening (for mineral differentiation rather than size classification only) and gravity separation (using jigs). This is to be contrasted to conventional preconcentration as performed with automatic ore sorters."

Jan 1, 2016

By Peter Riccio

Oxiana Sepon?s mineral processing facility in south central Laos produces copper cathode using leach-autoclave-SX/EW flotation technology. Pyrite recovery in the flotation circuit is critical to the operation, as it is used to generate acid for the leach circuit. However, low pyrite recovery has been an ongoing challenge in the flotation circuit. Tailings characterization work done by Ian Wark Research Institute showed that the pyrite losses to the tail are made up of a combination of coarse liberated particles and finer particles that have been coated by clay fines. In December of 2005, a joint Cytec-Oxiana technical program was initiated to address the pyrite recovery issue. A series of diagnostic tests were performed in the Cytec Stamford Research Facility using synthetic plant water showing that the collector was precipitating as a metal salt, and was un-available for mineral attachment. The tests also identified several collector chemistries that would likely be robust in the Sepon low pH, high dissolved metal ion environment, and will not complex with ferric, ferrous, or copper in solution. With the support of the Sepon on-site engineers, an extensive, successful laboratory program was completed, which then was followed by on plant testing that showed a step wise improvement in pyrite recovery.

Jan 1, 2014

By Manuel Gomez

This report presents low-temperature tar data from studies by the Bureau of Mines of tars produced in an externally heated (entrained state) pilot-plant-scale retort. Analytical data covering 20 low-temperature tars, derived from the. carbonization of various ranks of foreign and domestic coals, are tabulated. The character of the tar is discussed in relationship to carbonizing conditions and the rank of coal. It is seen that in carbonization techniques that employ entrainment or fluidization of the coal particle, carbonization conditions are secondary to coal rank with respect to tar-oil yields and composition. The influence of distillation conditions on recoverable yields of tar products is presented. The probable yield of commercially important chemical products, based on a ton of pure (moisture- and ash-free) coal, are predicted. INTRODUCTION Low-temperature tars produced by entrainment or fluidized carbonization techniques that employ internally heated reactors represent the most nearly primary tart produced by industrial processes. In brief, such a process involves the application of a heat gradient to the coal particle "boiling" or suspended in a turbulent state in the reactor chamber. Conditions are observed so that the coal particle remains suspended within the reaction zone by a gas stream for a time interval commensurate with maximum tar-oil yield. The heat necessary for the carbonization reaction may be obtained entirely from the hot (preheated) gas stream, or it may be derived partly from the combustion of the volatile products and char by the transport gases, usually air. The volatile material moves out of the carbonizing zone at a rate that approaches the velocity of the transport gas. Carbonizing conditions are ideal when a minimum particle residence time is obtained within the reactor at a given temperature and a maximum yield of condensable volatile matter is released. In industrial practice this objective is a compromise.

Jan 1, 1957

THE object that the writer has mainly in view in presenting this paper is to draw the attention of those connected with the technical side of the industry to the unsatisfactory and by no means up-to-date methods employed in estimating the tin contents of an ore. At the same time, what is regarded, from the writer's personal experience, as a satisfactory and reliable method is explained in detail. It is a curious fact that for the last 25 years tin·assay methods have made little or no advance, while those now in general use ill connection with copper and lead ores can scarcely be compared with those then obtaining, so greatly have they been improved upon. Though it. is not altogether expected that the method herein advocated will at once meet with general approval, the writer hopes the resultant discussion may bring out points that have hitherto escaped detection.FIRE METHODSThe old Cornish method of smelting with anthracite is now obsolete. The cyanide assay, although unreliable, is still much used because of its simplicity. In the Malaya many buyers of tin ores use the cyanide assay, the smelting being carried out generally in a benzine furnace. It is essential that the smelting with cyanide be performed at a low temperature. Even then, impurities, such as Sb2S3 and...

Jan 1, 1912

By Osamu Taki

The innovative Soil-Cement Mixed Wall Technique emerged in Japan and obtained recognition in the engineering and construction communities in the 1980's. This technique was introduced to the United States in 1986. It was accepted as the most credible construction technique by the U.S. Bureau of Reclamation for ground stabilization and cutoff wall work in the Jackson Lake Dam Project, Wyoming in 1987 and 1988. It was also accepted as a remediation technique by U.S. EPA for a Superfund Innovative Technology Evaluation (SITE) demonstration on in-situ solidification/ stabilization. The Soil-Cement Mixed Wall Technique consists of mixing in-place soils with cement grout or other reagent slurries using multiple axis augers and mixing paddles to construct overlapped soil-cement columns. The overlapped column panel is then extended to form an underground continuous soil-cement wall for use as a cutoff wall or a structural diaphragm wall for groundwater control and excavation support. By arranging the column panels in various configurations, the technique becomes a versatile tool for stabilization of soft or liquefiable soils.

Jan 1, 1990

By Maria I. De Rosa

The U.S. Bureau of Mines performed experiments to determine the hydrogen cyanide (HCN) concentrations and smoke particle characteristics during the combustion of flexible polyurethane foams and other nitrogen-containing materials, for the development of a test parameter. The experiments were conducted in an approximately 2O-L furnace at set furnace temperatures of 250° and 1,000° C for a 14-min duration, with an airflow through the furnace of 10 L/min. The variables studied as a function of time were the gaseous and aerosol HCN concentrations, the smoke particles average diameter (dg) and particle concentration (no), and the product of the smoke particle diameter and concentration (dgno). Carbon monoxide, carbon dioxide, and oxygen concentrations, sample mass weight loss, and furnace temperatures were also studied; analyses of nitrogen and cyanate content of the material were carried out. Results show that dgno correlates directly with the HCN concentrations, which depend on the nitrogen and cyanate contents of the material.

Jan 1, 2010

By G. L. Neumann

"INTRODUCTION Mining in this area is inactive. The entire region is now comprised of small farms. Because approximately 1,500,000 tons of magnetite ore had been shipped from this area between 1855 and 1915, it was deemed probable that geophysical surveying and core drilling might indicate other ore bodies or sizable extensions of the previously mined ore bodies.ACKNOWLEDGEMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has, as its primary objective, the most effective utilization of our mineral resources, thus fortifying our national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual investigative work and prepares the final report. The Metallurgical Branch, Oliver C. Ralston, chief, analyzes samples and performs beneficiatien tests.The chemical analyses and beneficiation tests included in this report were performed at the Eastern Experiment Station of the Bureau of Mines at College Park, Md., under the general supervision of J. B. Zadra, chief, College Park Division, Metallurgical Branch, and the immediate direction of Dr. Alton Gabriel, head of the laboratory service unit.The Mineral exploration Was under the general supervision successively of G. D. Jermain, district engineer, C. B. White, district engineer, and McHenry Mosier, chief, College Park Division, Mining Branch.The geophysical section of the exploration was performed by G. B. Botsford, engineer of the Bureau of Mines. Assistance was given by the Division of Geophysical Exploration of the Bureau of Mines, Dr. F. W. Leo, chief."

Dec 1, 1947

By F. G. ROCKWELL

ALTHOUGH the diamond as a gem stone dates back many hundreds of years its use industrially, at least to any extend is recent. The old adage: "Use a diamond to cut a diamond" indicates that some industrial use was made of this material in cutting and polishing many years ago. It also put to various other industrial by the Romans. General industrial use however was never developed to any considerable extent until about the time of the first World War. It is definiely known however, that a Swiss watchmaker, M. Leschot by name, invented a diamond drill in or about the year 1862, Today, some 75 or 80 per cent of the total didamods produced are used in industry. There are two main classifications of diamonds : (1) carbonados or "black diamonmds," and (2) diamonds proper.

Jan 1, 1944

By Syd S. Peng

In the past few years, the numbers of underground coal mines in this country using longwa11 mining method have been dramatically increased. In the latest count there are approximately 90 10ngwa11 faces amounting roughly 8% of the total underground production. Meanwhile, shortwall mining adapting longwa11 powered supports to 'coal mining and handling systems in room and pillar mining is also gaining importance in the Appalachian coal field. Although there are only 7 operating shortwall faces so far, indications are that it will be increasing steadily. Modern longwall faces are highly mechanized and productive. One of these key elements that contribute to the success of modern longwall mining is self-advanced powered supports. There are several types of powered supports. Frame type is two sets of one to four hydraulic legs supporting beam-type roof canopy and floor base. However, chock type is more popular and connected to broad roof and base structure. Shield supports were introduced recently but proved to be highly successful (1). A shield support consists of two hydraulic jacks mounted between a base plate and a gob shield. The base plate is hinged to gob shield which is in turn hinged to roof canopy.

Jan 1, 1977

Longwall mining operations have been in place in Australia since the early 1960s. This mining method is currently used to extract the bulk of coal obtained from underground mines in Australia (CSIRO, 2010). Despite the high tonnages extracted the expected utilisation of much equipment remains relatively low. To some extent this level of utilisation is influenced by the variability in conditions inherent in the mining process. This variability in production rates presents challenges to those attempting to design a coal clearance system. The difficulty is to design a system that has sufficient capacity to support production, without over capitalising or incurring high operating costs. The need to allow for a series of largely unplanned events in the design of a coal clearance system makes simulation modelling an ideal technology to employ. Simulation modelling is a methodology that allows a system with interacting components to be modelled over time, while explicitly taking into account unplanned events that may disrupt operations.This paper discusses how dynamic simulation models have been used to assist in the design of coal clearance systems. Typically this type of modelling has been used to look at the likely profile of production rates from the Longwall shearer and to determine how well various proposed combinations of belts, bins and stockpiles would support production.

Sep 26, 2011

By Paul M. Tyler

[This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the mining laws of specified French possessions in Africa has been prepared from the best information available in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers, to whom it is being referred through the courtesy of the Department of State. France controls large areas on the African continent, but the various Colonies and Dependencies are administered more or less independently. Algeria is under the direct jurisdiction of the Ministry of the Interior, and its mining laws are essentially the same as those of the mother country. Tunis and Morocco are attached to the Ministry of Foreign Affairs; separate digests of the mining laws' of these respective colonies have already been prepared by the United States Bureau of Mines. The present paper covers all other French territory on the continent of Africa except Somaliland, a rather small Colony including the port of Djibouti near the point where the Red Sea joins the Gulf of Aden. Available information indicates that the prospects of mineral production in this Colony, apart from salt and gypsum, are not at all encouraging.3]

Jan 1, 1933

By R Austerberry, S Green

The discovery of the Cuffley Lode at Mandalay Resources Costerfield Operations provided an opportunity to extend mine life via mining the offset depth extension of the previously worked Alison Mine. Access from the existing Augusta Mine placed the initial Cuffley underground workings at approximately 250 metres depth from surface. As the new orebody transitioned towards production, a secondary means of egress needed to be established. The depth of the initial capital development presented a challenge in establishing a secondary means of egress that could be confidently relied on. The availability of land to locate a surface shaft collar further reduced available options and geotechnical drilling further limited suitable shaft locations. Time limiting factors such as permitting and having a secondary means of egress in as soon as possible, further highlighted that an innovative secondary means of egress was needed. A consideration of using an emergency gig lowered by a suitable sized crane supplied by an external crane contractor was investigated and found to be a suitable outcome. This Emergency Gig was deployed via the Cuffley Return Air Raise. When trialled, the emergency gig was found to provide a reliable, repeatable extraction method with an acceptable level of risk. Issues discovered during such trials further improved the process to a point where this extraction method became the adopted secondary means of egress for additional lodes that existed at depth. When assessing possible methods of secondary means of egress, the use of a third-party crane and custom designed and fabricated emergency gig should not be discounted. Where a crane can be sourced within an acceptable timeframe, the emergency gig extraction method provides a reliable safe and cost-effective means of secondary means of egress, especially when multiple shafts are to be developed. Local laws may negate the ability to employ such a system, although it is believed with good communication and well-constructed risk assessments, this system can be safely deployed.

Mar 15, 2021

You have been involved with research activities in froth flotation and size reduction. What do you think the future holds for these technologies? Froth flotation and size reduction are essential processing steps common to almost all current mineral-processing operations. The most significant recent advances in both of these technologies have been in the increased size of equipment and in some alternative machine designs, such as the column cells and the high-pressure roller mills. I believe that the next major area of improvement in size reduction will be at least partially driven by an improved awareness of controlling the conditions that influence the efficiency of particle breakage. This would include factors such as water-chemistry influences, the influence of fines from classification, chemical grinding additives and better rheology control. In froth flotation, significant changes are currently taking place in the plant use of frothers. Also, there will be an increasing number of new collector chemistries for certain types of flotation, such as with oxide minerals, oxidized mineral recovery in sulfide systems and improved selectivity with certain sulfide mineral systems. You have been active in implementing new engineering technology in industry. What do you think will be the technological future of mineral processing? Being involved in the invention and industrial implementation of new technology has been one of the most positive experiences of my career. I also have had the unique experience of working in the chemical and petroleum industries as well as in mineral processing. In my opinion, the future of mineral processing will be an exciting, wonderful work area in which to be involved. The development of new technology in minerals processing offers a special challenge compared, for example, to that of chemistry or chemical engineering. In successful industrial innovation involving minerals, having a sound theory is not enough. Instead, what is required is a valid blend of a good idea, meaningful laboratory characterization and, most key, the experience necessary to adjust the plant in such a way to incorporate the idea. The complexity of engineering systems that contain solids, liquids and gases, as well as highly variable natural mineral properties, means that nothing new comes easily. In some cases, it has been difficult to explain how processes practiced in industry for decades actually work, in terms of physical and chemical fundamentals. On the other hand, when a new idea is successfully implemented, the economic and professional returns can be very rewarding. I know of no more challenging field of engineering than minerals processing. What is your view of the future of the minerals industry in general? The need for minerals, metals and coal will be with us for decades to come. In many aspects, the minerals industry became global much earlier than some of the other industrial sectors that are currently experiencing globalization. I believe that fair international competition is beneficial to the users of minerals, metals and coals and to those involved in producing such materials. The key word here for a global economy to work is "fair." So the various playing fields involved such as finance, profit return, regulation and labor should be relatively level for all the players involved. Competition is an amazing driving force for innovation. This has been true in the minerals industry during the last few decades. The mining industry is producing more at less cost per unit than ever before in our history. I anticipate that this trend will continue as long as the global political situation remains relatively stable.

Jan 1, 1997

By W. F. Watts

The U.S. Bureau of Mines has conducted research on methods to reduce and to measure diesel particulate matter (DPM) aerosols in underground coal mines. One objective of this report is to present findings from an investigation of the DPM reductions obtained by an engine-mounted integrated control system consisting of a dry system (DS) and a diesel particulate filter (DPF). Another objective is to present results from the usc of a size selective personal sampler to measure DPM concentrations in an underground coal mine. Bureau laboratory tests of the integrated dry system and diesel particulate filter (DS-DPF) have shown that DPM emissions can be reduced up to 97 pet with little change in gaseous emission concentrations. The DS-DPF is undergoing certification tests conducted by the Mine Safety and Health Administration (MSHA). Subsequent to passing all safety requirements, it will be tested in an underground coal mine. A baseline survey of DPM concentrations and aerosol size distributions in a cooperating mine was completed in August 1988. A prototype DPM personal sampler was tested during this survey. Based on results from this test, an improved unit has been developed. This unit is scheduled for extensive field testing by MSHA in 1989.

Jan 1, 1989

By Bruce R. Leland, Steven H. Smith, John D. Paulson

The USDA - Wildlife Services has been removing beaver dams with explosives for over 30 years. This paper will discuss the history of the explosives program, summarize how we've evolved, and highlight our work removing beaver dams in unique locations.

Feb 1, 2020