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By Gunter Zimmermeyer, Hartmut Eicker

Radon in the Environment Radon, as a natural nobel gas, can be detected nearly everywhere in the environment as a decay product of ubiquitous uranium. As it is emanated from soil and rocks measurable concentrations have been found at the surface of soils and in even higher concentrations in enclosed spaces like, for example, mines and buildings. While above soil surface activities caused by radon have been found in an order of magnitude of up to 1 pCi/l (Weigel, F. 1978), concentrations in enclosed spaces and mines are higher because of the lack of atmospheric circulation. Beside air circulation the relevant figure depends on the Ra226-concentration in the surrounding rocks or building material, as well as on emanation coefficient and the diffusion coefficient. While representative Rn222concentrations in well ventilated buildings are reported to be in an order of magnitude of 1 pCi/l maximum values up to one order of magnitude higher have been found in badly ventilated brick buildings (Ettenhuber, E., Lehmann, R., Clajus, P., 1978) (Aitken, J.H., et al., 1977). Just now it was stated that the reduced air circulation due to German legal regulations on energy conservation will increase radon exposure of the public considerably (Jacobi, W., 1979). Radon in Mines Radon exposure of workers is, of course, a matter of concern in uranium ore mines where relatively high concentrations of the uranium to be mined are present. Measures to protect workers' health have been implemented, based on experience on dose-effect relationship. They serve to meet exposure standards by limiting inhalation of radioactive particles, in reducing radon concentrations or in limiting working hours. Both improved measuring devices and capacity as well as the lower discrimination threshold enable to measure radon concentrations in other mines, e.g. in coal mines. It is known that radioactivity in coal is small compared with that in other minerals and even soil, rocks. Nevertheless, radioactive elements were identified in coal and so the question was whether the concentrations of radon in coal mines might be a subject of concern. The problems encountered when measuring radon in coal mines are described below, as the measuring device has to be flame proofed which is an important additional requirement. Measured radon concentrations in British coal mines have already been published (Duggan, M.J., Howell, D.M., Soilleux, P.J., 1968 (Dungey, C.J., Hore, J., Walter, M.D., 1978). The authors found concentrations of up to 14 pCi/l in Cornish mines. In most cases the values were in the order of 2 pCi/l. These results were consistent with measurements reported from U.S.-coal mines (Lucas, H.F., Gabrush, A.F., 1966). Such concentrations of radon were not considered to represent a hazard for British miners (Ogden, T.L., 1974). In Germany, too, first measurements have been carried out in five coal mines in the Saarland in the 60's. Air samples were taken at different places in the coal mines, dried, fed to an ionisation cell and measured by a device including reference cells. Samples taken at ventilated places showed radon concentrations consistent with the lower British results. They all kept within the standards of the first German regulation on protection against radiation. Measuring the radon daughters was renounced because of the relatively low radon concentrations and the requirements for flame proofness in coal mines. Moreover, it can be ascertained that because of the effective ventilation the disequilibrium factor between the decay products and the radon concentration remains far below the value of one (Muth, H., 1978) (Keller, G.). In 1979 the committee on mine safety and health protection in coal and other mines of the EEC proposed to have measured and evaluated radon concentrations in European coal mines to find out whether they complied with international standards. Great Britain and Germany agreed to this proposal and by commissioning such measurements to scientific institutes complied with the request to harmonize the methods used. In the Federal Republic of Germany, e.g. Westfälische Berggewerkschaftskasse (WBK) and Staatliches Materialprüfungsamt; Dortmund (MPA) were requested to carry out the measurements in coal mines of the Ruhr coalfield whereas Saarberg Interplan was responsible for the Saar coalfield. The WBK measurements are reported in later paragraphs.

Jan 1, 1981

By Jeffrey L. Zelms

There is no known, practical substitute for lead in the automobiles, communications systems, medical equipment and computers that Americans use every day. However, there are many who say lead should be stopped at its source -- banned. As America's largest lead producer, The Doe Run Company has ralized that it must do more than mine and reclaim lead efficiently and safely. It must also earn the public's consent to operate if it is to continue to be a viable business. LEAD - THE BRILLIANT PERFORMER: REFURBISHING AN IMAGE It's been an embarrassingly long time since I was a college student. However, I remember there was no course at the University of Missouri's School of Mines and Metallurgy that had anything to do with the public relations aspects of mining or, put another way, the politicization of mining. It's been an embarrassingly long time since I was a college student. However, I remember there was no course at the University of Missouri's School of Mines and Metallurgy that had anything to do with the public relations aspects of mining or, put another way, the politicization of mining. I haven’t perused the course catalog for Penn State’s College of Earth and Minerals Sciences. But I strongly suspect I wouldn’t find such a course there today, either. A statement by the chairman of one of the country’s largest chemical companies leads to the point I want to make. He described his business this way. He said, “We’re a public affairs company that just happens to produce and market chemicals.” Like chemicals, minerals and mining are politicized today. To the extent that we don’t understand that reality, we don’t understand that reality – and act on it – we’re less likely to survive in this business. Some of you may well be saying to yourselves, “This guy Zelms is an alarmist.” That’s fair enough. Because it is absolutely true that there’s n o known, practical substitute for lead today. And it’s also absolutely true that, knowingly or not, Americans use lead everyday. It’s in our automobile batteries. It’s an integral part of communications systems. High tech (and low tech) medical equipment contains lead. And lead is an essential component of computer and TV screens. But even with all these uses, lead has a negative image today. An image so negative that its very existence is threatened. If you doubt that, consider these two statements made in 1989. Statement one. “It is probably reasonable to argue that exposure is the single most important and critical environmental health problem in the U.S., and possibly also the world…” Statement number two. “Many of the uses of lead should be terminated. We need to go back to the ultimate source: that is, taking lead out of the ground and putting it into the product stream and we need to turn it off at the ultimate source. Not the approximate lead in gasoline, or lead in air, or lead in food. Go right back to the source and start cranking it down." (End quote.) Those are what I call strong statements. And they weren’t made by some celebrity spokesperson for the environment like Meryl Streep. Both these statements were made by Dr. Ellen Silbergeld, whose long list of professional and academic credentials includes: o Adjunct professor and research scientist at the University of Maryland Medical School and Johns Hopkins: o Chief toxic scientist and director of the Toxic Chemicals Program of the Environmental Defense fund; o and President of the Society for Occupational and Environmental Health. If Dr. Silbergeld were the only person making these kinds of statements, it would be one thing. But she’s not a voice in the wilderness, by any means. Also for those of you who say, well since there’s no known substitute for lead, how on earth could it be banned. I refer you to a number of bills before Congress that would permit the EPA to ban any product if it is determined that its

Jan 1, 1992

By G. J. Simandl

Jade is a commercial term encompassing green, white, black or yellow-brown jadeitite and nephrite. Jadeitite consists of Na-rich pyroxene, whereas nephrite consists of prismatic to acicular amphiboles of the tremolite-actinolite series forming bundles that are randomly oriented and interlocked. Nephrite is tougher (harder to break) than jadeitite. Its fracture strength is about 200 MN/m2 whereas that of jadeitite is about 100 MN/m2. On the other hand, jadeitite has a higher hardness (7 compared to 6.5 on the Mohs scale). There are over fifty known nephrite occurrences in British Columbia (B.C.). These occurrences consist of individual blocks, boulder fields, talus blocks and in situ occurrences. Most of the in situ occurrences are lens or cigar shaped. They occur at, or near the contact of ultramafic/mafic rocks (mainly serpentinites) with cherts, and other metasedimentary or igneous felsic rocks of Mississippian to Jurassic oceanic terranes such as Cache Creek and Slide Mountain. These contacts are commonly interpreted as shear/fault related. In general, it is believed that the B.C. nephrite formed by metasomatic exchange between ultramafic and silica-bearing rocks. Impurities in B.C. nephrite are spinel group minerals (chromite, magnetite, picolite), diopside, uvarovite, titanite, chlorite, and talc. Jadeitite is slightly denser than nephrite and good quality material sinks in methyl iodine. There are no known jadeitite occurrences of economic interest in B.C., but there are at least four geographic areas where favorable lithologies, and metamorphic conditions (Pn) required for the formation of jadeitite coincide. These are Bridge River, Pinchi Lake, Dease Lake, and Jennings River. These areas are known to contain small concentrations of jadeite, or are characterized by blueschist or eclogite-grade metamorphic conditions. Rhodonite and pyroxmangite are MnSi03 polymorphs. These minerals are pyroxenoids and are macroscopically and microscopically very similar. For brevity, both are grouped together under the term "rhodonite". Most of the B.C. occurrences are hosted by late Paleozoic chert sequences and are lens shaped and concordant. The common association of rhodonite with iron formations, jasperoids, and/or volcanogenic sulphide deposits in southwestern B.C. permits the delineation of favorable horizons using magnetic or electro-magnetic geophysical methods. Geographic associations between manganese showings and sulphide deposits, and the hydrothermal chemical signature of the rhodonite occurrences from this area, suggest a genetic link between rhodonite and volcanogenic sulphide deposits. The typical rhodonite rocks consist of rhodonite, pyroxmangite, neotocite, black amorphous Mn-oxides, Mn-bearing garnet, ± epidote, ±chlorite, ±rhodochrosite, ± parakutnah-orite, ± Mn-bearing calcite, ± iron oxides and hydroxides. Garnet ± epidote forms yellow patches and layers within the rhodonite. Within some of the rhodonite occurrences, the garnet is altered to chlorite. Rhodonite-bearing rock is commonly cross cut by secondary manganese oxide veins, creating a characteristic web-like texture. In several localities, the contorted bedding planes are readily recognized. Mn-calcite and quartz also crosscut rhodonite. Rhodonite deposits hosted by high grade metamorphic rocks may contain pyroxmangite. Rhodonite is an important gemstone and ornamental stone in B.C., second only to nephrite in dollar value. B.C. nephrite and rhodonite have been used for the past 100 years in local jewelry and ornamental applications. More recently they have been used in table tops, and they have potential as upscale materials in tile-making. There may be a market for tiles made from lower grade materials that were previously extracted and stockpiled. The prices of nephrite, jadeitite, and rhodonite vary widely with quality, but gem and ornamental grade stones are relatively highly priced materials and they trade world-wide.

Jan 1, 2001

By Richard H. T. Garnett

In 1900, placer gold was discovered on the beach of Nome, AK on the southern coastline of Alaska's Seward Peninsula (Garnett, 1991). The site is about 800 km (500 miles) from Anchorage. Nome is connected to Anchorage only by air (daily) and by sea (summer). Total onshore placer gold production from Nome's immediate vicinity was more than 155.5 t (5 million oz). Alaska Gold Co, has continued to produce gold onshore with, until recently, two bucketladder dredges, each of 255-L (9-cu ft) bucket capacity. Small-scale marine dredging for gold has been at- tempted several times this century (Garnett, 1991). Western Gold Exploration and Mining Co. Ltd. Partnership (WestGold) is the only company to have been successful in achieving a significant offshore production. The Nome bucketladder-dredging operation from 1986 to 1990 constituted a unique marine-mining experience in the United States. \Inspiration Gold Inc., WestGold's predecessor, acquired six offshore leases in 1985. The total lease area of 87 km2 (21,551 acres) extended from the coastline to the 4.8-km (3-mile) offshore limit (Fig. 1). Those leases al- ready had been partially explored. Drilling was conducted off the shorefast winter sea ice. Therefore, it was rarely more than 1.6 km (1 mile) from the shore or in water deeper than about 9 m (30 ft). In 1985, estimated reserves comprised of a 5-m (17-ft) vertical thickness of sediments below 6.3 m (20 ft) of water. This meant a mean digging depth below the mean sea level (msl) of 11.3 m (37 ft). It was thought that the offshore Nome deposit possessed a feature that is common with many terrestrial gold placers - the secret of profitable exploitation of the marine deposit lay in maximizing the dredge throughput to minimize the unit costs. The inability of the project to withstand the prohibitively high cost of a new dredge was recognized. So Inspiration Gold purchased a used unit. This was the world's largest ocean- going bucketladder dredge (Fig. 2). Binzn was an 850-L (30 cu ft) bucket capacity dredge that was lying idle in Singapore. Originally constructed in the Jurong shipyard of Singapore in 1979, Bima was designed by Mining and Transport Engineering, a subsidiary of IHC Holland. Billiton Marine used the dredge for tin production at Pulau Tujuh in Indonesia (Dieperink, 1978) before it was laid up in mid-1985. Bima underwent a nine-week refit before departing Singapore on June 4,1986, with 800-t (880-st ) of deck cargo. It was dry-towed for 32 days to Alaska. A slower, less expensive, wet-tow at the authorized 5.5 kmthr (3 knots/hour) would have delayed the dredge's arrival in Alaska untl almost the onset of winter. The 13,000-km (8,100-mile) voyage was made on the deck of Smit Lloyd's "Giant-4" submersible barge towed by its 7.8- MW (10,500-hp) tugboat. The first season's dredging revealed several major shortcomings in Bima. Further repairs and modifications were undertaken at Tacoma, WA. The dredge returned to Nome for the June start of the 1987 summer dredging season. The refitted Bima worked offshore at Nome from 1987 to 1990. It produced 3.67 t (118,078 oz) of gold at an average recovered grade of 824 mg/m3 (0.0204 oz/cu yd). In 1991, the dredge was dismantled and sold.

Jan 1, 1997

By M. R. Shahan, C. E. Seaman, S. E. Mischler, T. W. Beck

"Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof, and ribs of mine airways. If deposited float dust is re-entrained during a methane explosion, without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting—adding inert material to airway surfaces—is the main control technique currently utilized by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, NIOSH’s Pittsburgh Mining Research Division (PMRD) initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture, and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types, and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section, and a coal handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer, and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8. INTRODUCTION During the extraction of coal, various dusts are produced that can be classified into two categories of interest: respirable and float coal dust. Respirable dust (diameter 10.0 = µm) has the capability to penetrate beyond the terminal bronchioles and become deeply embedded into the human lungs, leading towards respiratory disease complications (Potts et al., 1990). Float coal dust is defined as coal dust having a diameter less than 74 µm (Harris et al., 2009). During the mining process, float coal dust can be deposited on the floor, roof, and ribs of mine airways. With the proper mixture of methane gas (between 5% and 15%) and an ignition source, a methane gas explosion can occur (Barker and Humphreys, 1996). The resulting explosion can develop a pressure wave which lifts the deposited float coal dust material into the air, propagating a disastrous coal mine explosion (Harris et al., 2010). The current technique to safeguard against the propagation of a coal mine explosion is to treat the mine airways with incombustible rock dust (typically limestone), maintaining an 80% total incombustible content of the deposited material. NIOSH initiated a project to investigate control technologies that could be aimed at reducing the amount of float coal dust allowed to deposit in the mine airways using three approaches: prevention, capture, and suppression prior to deposition. Reducing the float coal dust being generated during the mining processes and capturing or suppressing airborne float coal dust prior to deposition would in turn increase the efficiency of the applied rock dust used to prevent mine explosions."

Jan 1, 2017

The Sandvik Group (Sandvik AB), headquartered in Sandviken, Sweden, continues to expand its worldwide operations growth. After recent acquisitions, including Tamrock, headquartered in Tampere, Finland, the company now has annual sales of more than US$5 billion (SEK 40 billion). With the acquisition of Tamrock, Sandvik has further increased its interests in the mining industry. Sandvik Rock Tools, a familiar name in the mining industry, is one of the world's leading suppliers of rock-drilling tools. And Tamrock is one of the world's leading suppliers of drilling machinery, loaders and equipment for rock-excavation operations. Sandvik believes that the two companies combined offer customers "maximum productivity through total system solutions, including machinery, service and tools." In 1997, Tamrock posted sales of US$940 million (SEK 7.5 billion). In addition to its expertise in drilling tools and equipment, Sandvik is supported by its collective resources in specialty steel and cemented carbide. These resources include extensive research and development capabilities, with annual investments in R&D now at about US$150 million. As a result of the R&D programs, internal expansion and acquisitions, the company has nearly doubled in size during the past four years. From 1994 to 1997, nearly US$1 billion was invested in internal growth and another US$825 million has gone towards acquisitions. Return on net assets is now 22% annually. In addition to Tamrock, acquisitions of interest to the mining community include Drillmaster Inc., Houston, TX. The acquisition of Drillmaster (by Sandvik Rock Tools) has further strengthened Sandvik's position in down-the-hole drilling tools. Other major recent acquisitions by Sandvik include Kanthal, a Swedish manu¬facturer of metal and ceramic-resistant materials for electric heating furnaces, household appliances and elec¬tronics, and Precision Twist Drill, Crystal Lake, IL, one of the leading producers of high-speed cutting tools. With more than 38,000 employees worldwide, the Sandvik Group is divided into six separate business areas. Each area is responsible for its own R&D, production and sales: ? Sandvik Mining and Construction. Including Tamrock and Sandvik Rock Tools, this business area boasts of offering the most comprehensive range of "rock-working" products. These include drilling rigs, loaders, rock-excavation equipment and rock drilling tools. ? Sandvik Specialty Steel. This area includes Sandvik Steel and Kanthal, manufacturers of stainless steel tube, strip wire and bar, as well as high-alloy steel and specialty metals. ? Sandvik Tooling. This business area consists of tools and tooling for metalworking applications. Sandvik Coromant is a market leader in the development, manufacture and marketing of tools using cemented carbide, ceramics and extremely hard materials, such as diamond and cubic nitrite. CTT Tools is the world's largest manufacturer of high-speed steel tools and is now expanding operations into solid cemented-carbide tools. ? Sandvik Hard Materials. This segment produces a full range of "hard materials," ranging from cemented carbide to diamond. This area manufactures and markets a full range of cemented carbide blanks for tool manufacturers, as well as components and rolls. ? Sandvik Saws and Tools. This business area manufactures high-quality handsaws and metal saw blades, as well as hand tools ranging from wrenches to chains for logging machines. ? Sandvik Process Systems. This segment manufactures steel belts, process systems and automatic sorting systems for the chemical

Jan 1, 1998

By Andrzej Frycz

The development of the theory of reliability creates more and more possibilities of its application in different domains of technics. The methods evolved to date, both theoretical analysis of the engineering systems and investigations techniques in practice can be put in use a d translated from one science to another one [1,3,7J . It needs to consider the specific of the different sciences. But it is necessary to take account of the specific characteristic of each line of science. The reliability investigations needs, justified in technical and economical viewpoint appear too in mine ventilation technics and systems. The mine ventilation system is a complex of workings and ventilation plants, which serve to supply the networks with a sufficient quantity of fresh air from the atmosphere and then carry off the vitiated air. The condition necessary for a ventilation system to perform definite task is the correctness of all its elements, that is a capability to preserve in a expected range of tolerance, the values of basic parameters. The element of a system which ceases to work correctly is called failed. The basic parameter of all elements of a ventilation system is the characteristic curve, pressure loss - air quantity relation ?p = f(Q) (1) This curve concerning the workings and ventilation stoppings is given by the formula: ?p = R Q2 (2) thus the resistance R (of the workings or stoppings) may be taken as a characteristic parameter. The course of this characteristic f(Q) will be given in a complex form in concern with fans, ejectors, air curtains. The failure of a ventilation plant or working is therefore an event, relying on a change of its characteristic, thus for a definite time the losses of the plant's or working's capability set in for the fulfilment of its function in the ventilation system. The failures are divided in viewpoint of their nature on sudden and progressive. We are in concern with the sudden failures which are characterised by a violent change of the ventilation element parameter for example a fall of roof, or silt up of the working, opening or failure of the ventilation stopping, the stand-off of the fan or ejector etc. We distinguish two kinds of failures on the viewpoint of their action on the air flow: the "opening" failure and "closure" failure. The prevalence of factors, which causes the failures is in connection with the intersection in the mine of roads of haulage, roads of underground transport of materials and lining elements, roads of people motion with airways, as also depends on the rock pressure reaction on the workings lining and plants placed there. Other factors will yet be decisive upon supply decay of fans, ejectors and curtains. The appearance of failure of the ventilation element is therefore of random nature and determines the change of the element, when it is passing from operating state to unoperate. Qualifying the ventilation system element to one of these states is easy, when the characteristic change is clear and occurs suddenly, that was assumed. The investigations conducted by Patrushev and Karnaukh [91 in concern with the ventilation stoppings resistance change in the case of their opening, had shown the possibility of resistance value change in the range of several hundreds higher.

Jan 1, 1980

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

It is imperative that the hydrogeologic frame- work and the ground water flow systems of a Potential mine area be investigated prior to initiation of mining. Such investigations are necessary so that potential mine water inflow problems can be anticipated and controlled. Obvious difficulties can arise if large inflows of ground water occur in underground workings. Costs of water removal and disposal, if not foreseen and included in economic planning, can severely limit or eliminate profit from a mining operation. Safety problems associated with large inflows are an additional potential problem. The inflow of water into a mine necessarily alters the associated ground water system. The inflow also may impact nearby surface water regimes, depending upon the interaction of the surface water and ground water systems. The inflow of water into a mine inevitably causes a decline in the ground water levels in the vicinity of the mine. This decline may be restricted to a small area or it may extend a considerable distance, depending upon the hydrogeologic properties of the associated hydrostratigraphic units. A decrease in surface flow will result if the area of ground water level decline intersects a stream or spring that is hydraulically connected to the ground water system. Mine inflow problems historically have been evaluated after-the-fact. Premining hydrologic investigations only recently have been initiated. Brown's (1977)* report on anticipated hydrologic impacts of oil shale mining in the Piceance Basin of Colorado is an example of premining hydrologic planning. Observed difficulties inherent in designing a data collection network and then utilizing the data to predict mine inflow have led us to the preparation of this manuscript. This manuscript reflects a two-phase effort. The first phase describes and develops analytical and numerical techniques for mine inflow prediction. Emphasis in this section is placed on the selection and application of data collection techniques and data analysis procedures. The second phase applies the prediction technique(s) developed during phase 1 to two existing mines. The objective of phase 1 efforts is to evaluate the hydrologic variables associated with surface water systems and ground water systems that can affect the inflow of water into an underground mine. Subsequently these variables are incorporated into predictive techniques for estimating underground mine water inflow and its effect on associated ground water and surface water systems. The specific objectives of phases 1 and 2 are to: 1) Determine the hydrologic parameters required for predicting underground mine water in- flow and the potential effects of the inflow on surface and ground water systems. The hydrologic parameters represent both premining and past initiation conditions. 2) Outline methods for obtaining the necessary input data for the predictive techniques in pre- mining and post initiation periods. 3) Present existing numerical techniques for predicting underground mine water inflow including assumptions Ad required input. 4) Evaluate existing numerical techniques previously tabulated based on their applicability to mine water inflow prediction. 5) Attempt to develop analytical techniques for predicting underground mine water inflow. 6) Develop, through modification of existing models, a general mathematical model as a numerical technique for predicting underground mine water inflow and the resultant effects on surface and ground water systems. 7) Apply the predictive techniques to two existing mines selected for this purpose. 8) Compare the predicted inflow rates to measured inflow rates at both mines. 9) Compare predicted impact on district hydrology to observed impacts where possible. 10) Evaluate the predictive technique.

Jan 1, 1986

By S. P. Chong, Peter V. Avotins

The iron and steel industry continues to operate at depressed production levels due to the low level of demand for steel and foundry products. Crude steel production in the Western world dropped by 13.7% from 459.3 Gt (506 billion st) in 1981 to 396.4 Gt (437 billion st). The reduction was particularly severe in North America where the industry suffered a loss of 37.3% from 123.6 to 77.5 Gt (136 to 85 billion st). This reduced level of production severely affected iron ore and agglomerates output. Substantial curtailment was made in both sintering and pelletizing plants to meet reduced demand. The pressure on these plant operators shifted from quantity to quality. With energy cost becoming an ever increasing part of production costs, conservation was a major area of emphasis. Iron Making Sinter has continued to be the favored burden for blast furnaces overseas. As hot metal production declined and excess sintering capacity developed, many of the overseas operators that have been using pellets found it advantageous on hot metal production cost to increase the ratio of sinter at the expense of pellets. This was the case despite the depressed price level of pellets in the world market. In North America where pellets have been the predominant burden material-mainly because it is necessary to pelletize the fine grain iron ores available domestically-there was also increased interest in sinter usage. Bethlehem Steel Corporation's 13.6-m (44.5-ft) furnace at Sparrows Point experimented with a burden with more than 70% of sinter during the second half of the year and indicated some favorable results as compared to its previous 50% super flux sinter and 50% acid pellet burden. The blast furnace operators continued to press for improved burden quality. In addition to the emphasis on the importance of burden chemistry and quality, uniformity, much emphasis was placed on improving reducibilitiy and high temperature metallurgical qualities. These burden properties were recognized to hold further promise in reducing fuels rates. Sintering With reduced consumption caused by the cutback in hot metal production, many sinter plants sat idle while others operated at greatly reduced rates. The deemphasis on production in many plants allowed them to experiment with various means to reduce operating costs. The most notable action was the introduction of low cost South American pellet feed fines into the sinter ore mix. These feed fines, which are finer than 150 µm (100 mesh) ore, were previously thought to be too fine for sintering. However, when the full production rate is not required the use of up to 40% in the ore mix was reported to be successful with the aid of burnt lime and adequate premixing and granulation of the sinter mix before sintering. The emphasis on quality and tighter cost control also has resulted in a further breakthrough in sintering technology. It was recognized that good feed preparation-including selection of compatible ores, good blending, good pseudo-particle formation, additive size control increased bed depth, and closed control of the sintering bed heat pattern-could allow the production of high quality sinters with much lower heat input and FeO level. Bed depth of more than 600 mm (23.6 in.) was practiced in a number of operations. Total heat input of better than 1.3 GJ/t (290,300 kcal per st) has been achieved. Kawasaki Steel's Chiba Works has also achieved a 5.3% SiO2 in the sinter with good quality. The low heat input approach allowed production

Jan 5, 1983

By R. E. MacDougall

Very few mineral properties spend their entire lifespans from discovery to depletion in the hands of one owner. More likely, properties will have several owners, and partial interests may change quite often. Similarly, mineral companies are bought and sold with frequency, in recent years at what appears to be an accelerating rate. The reasons for selling a property can be manifold -need for additional capital in other parts of the business, need for development capital, realization of a large gain at a perceived high point in the market, pessimistic commodity outlook, retirement of principals, or resolution of estate problems. Regardless of the reasons for a sale, there are specific steps that logically follow. Spruce up the business, package the information, market the property, negotiate the terms, close the sale, and make sure it stays sold. Adherence to certain very basic ground rules in property sales can maximize the profits and minimize the effort.

Jan 1, 1990

By D. Randall Crooke, Ron R. Jorgenson

Many coal combustion products (CCPs) have historically been unsuitable for placement as mine backfill because of their physical and geochemical properties and/or regulatory status. However, innovations in paste production and transport of CCPs utilizing the high, fine particle contents of these fine-grained waste materials and their water retention colloidal properties produce a non-segregating, self-cementing material that may be environmentally suitable for placement as mine backfill. Both industry and the regulatory agencies are enthused by the possible cost reductions, both in design and construction of disposal sites, and the reduced environmental impacts of CCP realized by implementation of this new use/disposal technology.

Jan 1, 2001

By Ava Walker

The first form of a surety bond was an honest handshake between two or more parties agreeing to a decision, and their personal guarantee of following through to completion. This has all changed. In 1895, the United States Treasury Department disclosed that $35 million worth of personal surety guarantees on file had become worthless. A law was then passed requiring all surety bonds, in favor of the United States, must be corporate surety bonds. Today, a surety bond is one of the nation's leading fi¬nancial instruments used to guarantee the completion of an obligation. One hundred-fifty years before cor¬porate surety bonds, outcrops near Richmond, VA, were being mined. These surface mines became under¬ground mines. Today, both are still being used to obtain a leading energy source, coal. Since that time, more than 5956 km2 (1.47 million acres) of coal mined lands have been reclaimed in the US (Coal News, August, 1987). More than 25,000 state and Federal mining permits cover¬ing 14,164 km2 (3.5 million acres) have been issued during the last 10 years. Coal production has exceeded 7.2 Gt (8 billion st). More than 5665 km2 (1.4 million acres) of mined land has been reclaimed by active coal mining opera¬tions and 267 km2 (66,000 acres) of abandoned mined lands have been re¬claimed by others. Reclamation bonds were freely writ¬ten in the 1970s. So why are they almost extinct today? Contract bond losses have been severe in the past several years, sureties reporting losses exceed¬ing 110%. But the same proof is not provided on coal reclamation bonds. A surety bond is generally required when one party has an agreement with another party, and that party wants a guarantee from a third party that a job will be completed according to the terms and conditions of a written contract. In the case of a reclamation bond, the surety company (surety) is the financial party. It extends the credit and a guarantee to the obligee (the State, Commonwealth, or Office of Surface Mining) that the principal (the coal operator/company) will complete the terms and conditions of the contract (the rules and regulations governing mining and reclamation). The Surety Association of America defines a surety bond as an agreement providing for monetary compensation should there be a failure to perform specified acts within a stated period. Webster's Dictionary defines surety in the following ways: "l: the state of being sure; 2a: a pledge or other formal engagement given for the fulfillment of an undertaking and; 3b: one who has become legally liable for the debt, de¬fault, or failure in duty of another." Banks never make accommodation loans. Either the loan is good or no loan is made. Surety companies feel the same way about surety bonds. In fact, the average person does not realize the dangers of becoming surety for another. How does a surety determine if a company is worthy of receiving surety credit? How is a coal account under¬written today for an obligation that may not be released for many years? When a surety company executes a reclama¬tion bond, it financially puts its name behind the coal company and its guaran¬tee that should the coal miner default on the obligation, the surety will fulfill the contract. How is the surety to determine if a coal company may still be in business five, 10, 20, or 40 years from today?

Jan 1, 1989

By Shan Mafi

he Broken Aro coal mine is located at the Woodbury Wildlife Preserve 11 km (7 miles) west of Coshocton, OH on State Route 541. Underground min¬ing at the 16-hm2 (40-acre) site took place during the 1910s. During the past five years, surface mining has occurred along the western and northern perimeters of the underground region. The Ohio Department of Natural Resources (ODNR), R&F Coal and American Electric Power (AEP) are involved in a project to remine the abandoned underground complex. The program also includes installing a mine seal made of fixated flue gas desulfurization (FGD) material. Previous mining activity in this area has resulted in an acid mine drainage (AMD) problem on portions of the reserve. In particular, a prominent AMD source is present in the Simmons Run drainage. The project goal is to eliminate or reduce the AMD that is discharging into the watershed. It was initially hoped that the Simmons Run drainage area could be economically mined. Accordingly, this area was included in the mine permit. However, experience with other previously mined areas on this reserve showed that the old mine workings were more extensive than originally thought. Old mine workings present several problems. The most significant are reduced coal recovery, poor coal quality and AMD liability. All of these problems increase mining costs. And the more extensive the old workings, the more significant the increase in cost. Based on R&F's experience with old mine workings in this area, it was decided that economic recovery of the Simmons Run drainage reserve was not possible. As a result, R&F excluded the Simmons Run drainage area from its early mine plans. Some time after it was decided not to affect the Simmons Run drainage area, R&F and ODNR's Division of Mining and Reclamation discussed the possibility of removing this area from the permit and attempting to correct the AMD problem as an Abandoned Mine Lands (AML) project. Specifically, the discussion centered around mining through a portion of the old mine workings to expose the mine openings in the highwall. Once exposed, the mine openings would be sealed using FGD material from the nearby Conesville power plant operated by AEP. In addition, there was interest in reclaiming the old tipple and associated gob pile located adjacent to Coshocton County Road 17 on the opposite side of Simmons Run. R&F attempted to eliminate the AMD problem by sealing the mine openings with FGD material. Once the seals were installed, they were covered with overburden. Monitoring wells were installed to determine the effectiveness of the seal and the inundation progress in the old mine workings as well as monitoring the quality of ground water. The project was jointly funded by revenue from the sale of the coal recovered during the project and AML funds. The FGD seal is expected to cause well water levels to increase above preseal elevations. However, the additional head pressure due to increased water depths in the underground mine may cause seepage through the bottom of the mine or out through the perimeter. The in¬creased water depth in the underground mine is expected to cause lower oxygen concentrations in the underground mine water. Since acidity is produced by oxidation of iron pyrites, less oxygen should result in better quality water. Monitoring wells will be installed before seal installation so that pre- and postseal water levels and well water quality can be determined. Surface sampling locations will be identified. These will be monitored before and after seal placement.

Jan 1, 1998

By Z. Henderson, J. Saylor, L. R. Mendoza

"Diesel particulate Matter (DPM) is a byproduct of fuel combustion in diesel engines. It is classified as a carcinogen, with associated respiratory and cardiovascular health effects. The composition, size, and concentration of DPM is dependent on factors such as engine type, loading and fuel composition. Though a number of DPM abatement and control strategies currently exist, particularly in underground mining environments, occupational exposures remain a serious health concern. As a novel abatement approach, DPM scavenging by fine water or “fog” droplets has been proposed and a laboratory set-up has been built to test the efficacy on engine exhaust. Here, we describe a series of tests that varied engine load, system flow rate and fog drop number density. While none of these factors had overwhelming effects on the results within the ranges tested, the improvement in DPM mass removal attributed to the fog treatment was about 45% on average in comparison to no treatment. INTRODUCTION Diesel engines have seen widespread use for well over a century due to their relatively high thermal efficiency and fuel economy1. More recently, however, adverse health risks of diesel exhaust have become increasingly clear. Many of these risks are associated with the physical and chemical properties of exhaust components1–3. The term diesel particulate matter (DPM) is used to refer to the solid components of diesel exhaust, which are a mixture of elemental and organic carbon (EC and OC) and minor constituents including sulfates and metal ash3. The OC fraction of DPM results from unburned fuel and lube oil, whereas EC or soot is formed during the combustion of locally rich regions within the fuel. DPM is classified as a carcinogen6,7 and epidemiological studies have demonstrated a positive correlation between long-term exposure to DPM and other combustion-related fine particulate and increased cardiovascular and pulmonary diseases8,9. Diesel engines operate in relative fuel rich/oxygen lean conditions and are characterized by relatively high emissions of particulate as compared to spark-ignition engines2,3,10. Typically, these emissions range from 107 – 109 particles/cc and cover two primary size ranges: the nuclei mode where particles have diameters less than about <50 nm, and the accumulation mode where diameters are from about 50-10,000 nm. Most OC resides in the nuclei mode as semi-volatile compounds, while most EC is in the accumulation mode3. The physical and chemical properties of DPM vary with the type of engine, fuel (e.g., petro- vs. bio-diesel) and operating conditions such as loading (i.e., a function of torque and rotational speed)2,3,9,11,12. Loading is a particularly important factor with respect to DPM toxicity9,13,14, and on the effectiveness of after-treatment technologies2,3,15. Engine load alone can affect the EC/OC ratio, and the size distribution and number density of DPM. For diesel engines, the load is roughly proportional to the equivalence ratio3, defined as the actual fuel/air ratio over the stoichiometric fuel/air ratio for complete combustion. Light loads generally favor the formation of OC and small particles. As load is increased the volatiles are oxidized leading to larger soot particles (i.e., EC), but lower total number density of DPM. With further loading, the formation of soot offsets the decrease in volatiles, resulting in increased DPM mean size and number density3."

Jan 1, 2017

By D. Carr, C. Anderson, M. Deal, C. Larson

"Construction of the OceanaGold Haile operation’s process plant in Kershaw, South Carolina is currently under way, with ore through the mill expected in late 2016 and commercial production expected in early 2017. The process is designed to treat 6,350 tonnes per day with minor upgrades required to achieve 8,270 tonnes per day. Plant optimization during detailed engineering, combined with a focus on de-risking the process, has resulted in numerous process changes since the initial design. This paper describes the plant optimization and de-risking, it also presents a proven commissioning strategy modelled after OceanaGold’s Didipio operation, whilst identifying potential expansion opportunities. INTRODUCTION Haile Gold Mine is located in Kershaw, South Carolina, approximately 50 miles south of Charlotte, North Carolina. Gold was first discovered at the site in 1827, and the property has been through several operating periods since. The last operation employed heap leaching from 1985 through 1992. Since then, the property has been closed and fully reclaimed. Romarco Minerals acquired the property in 2007, and began an exploration program that delineated 2.02Moz. of gold in reserve at an overall grade of 2.06 g/t. OceanaGold acquired Romarco Minerals and the Haile Operation in October of 2015. OceanaGold operates under a risk management philosophy in all aspects of operation, both corporately and at each individual business unit, and has implemented numerous process changes to eliminate or mitigate risks identified in the initial design of the processing circuit, and provided increased opportunity for optimization and expansion. This paper describes the plant optimization and de-risking, it also presents a proven commissioning strategy modelled after OceanaGold’s Didipio Operation, and identifies potential expansion opportunities. INITIAL PROCESSING CIRCUIT DESIGN An extensive metallurgical test work program was undertaken by Romarco Minerals and third party laboratories during the initial design phase of the Haile project [1]. This preliminary test work provided the technical information as a basis of plant design. The initial flow sheet for the Haile processing circuit is shown in Figure 1 (see APPENDIX). The plant is designed to process 6,350 tpd (7,000 stpd) on an annualized basis. The process begins with a jaw crusher followed by a SAG and ball mill grinding circuit to reduce particle size to P80 74 µm. A flash flotation cell treats 50% of the cyclone underflow in the ball mill circuit. Grinding circuit product is sent to a rougher flotation circuit to recover gold-bearing pyrite. The flotation concentrates from flash and rougher flotation are reground to P80 13 µm using stirred media detritors (SMD’s). The rougher flotation tail is pumped to the carbon-in-leach (CIL) circuit for gold recovery. The reground concentrate is pre-aerated prior to being pumped to the CIL circuit. The CIL circuit is a hybrid circuit with eight tanks. Tank 1 leaches the pre-aerated concentrate only, and tanks 2 through 8 leach the combined flotation tailing and tank 1 discharge. The carbon strip circuit is a standard pressure Zadra system, followed by electrowinning, and refining using an induction furnace. CIL tailing passes through a cyanide recovery thickener prior cyanide destruction and then pumped to the tailing storage facility (TSF)."

Jan 1, 2017

By R. J. Roman

Introduction This paper attempts to describe the characteristics of the industrial minerals segment of the minerals industry that make it different from the other segments. Also described are the trends, strengths, and shortcomings in the industrial minerals segment. This may help professionals in the minerals industry determine if there is a place for them in industrial minerals. Industry Overview It is difficult to generalize when describing the industrial minerals industry. Some products, such as cement and potash, are produced exclusively by large, well capitalized and technically sophisticated companies. Others, such as sand and gravel, are generally produced by small, family-owned companies operating on a shoestring budget. Still other products, such as feldspar, are produced by both types of companies. Not only are the companies vastly different, the products and marketing of their products are also different. Industrial mineral products are sold based on their physical characteristics (abrasives), or their chemical characteristics (trona), or both (glass sand). Marketing can be direct by the producing plant, a corporate office handling products form several plants, or through distributors. The geologic, mining, and processing skills needed can be minimal or sophisticated. There can even be large differences in the technical skills needed in two plants producing the same product. One feldspar producer may only need to mine and grind his ore, while another may use a delicate flotation process. One easy generalization is that there are industrial mineral operations in all geographic locations. A second is that industrial minerals offers more opportunities to entrepreneurs than the metals field because of the variety in the sizes and types of operations. Industry Growth Industrial minerals must be considered a mature industry. Consequently, little exciting growth can be expected. Over the past 30 years, industry sales have grown at a rate of 6.2%, compared to a 6.7% growth rate of the GNP (Kliff, 1978). A 3.8% growth rate has been forecast for the remainder of this century. The fortunes of those plants producing a product for local consumption will depend on the prosperity of the local economy. The fortunes of those plants that sell into the national market will depend on their competitiveness in their industry. Major industrial mineral products are shown in Table 1. The first three commodities account for 66% of the industrial minerals market. Typically, deposits of stone, sand and gravel, and the limestone, silica, and clay needed for cement are easy to find and mine. Role of Mining Engineers and Geologists Because a sophisticated techcical knowledge of geology or mining is not required, very few geologists and mining engineers are employed in industrial minerals. Geologists working for these companies function less as geologists than managers and executives dealing with permitting and land acquisition. Likewise, mining is done mostly by open-pit methods. It is generally supervised by an individual experienced in the operation and maintenance of heavy equipment, not a mining engineer trained in rock mechanics or computer methods of mine planning. What of the geologists and mining engineers employed by the industrial minerals industry? Many gained their positions as a result of their experience dealing with the regulatory agencies that control the operations of all mines and mills. Their technical expertise in geology or mining becomes only a side benefit. Finding and mining industrial minerals does not generally require the concentrated efforts of geologists and mining engineers. But the processing of the ores does

Jan 2, 1985

BP Minerals America (BPMA) has completed its $400 million modernization of Kennecott Utah Copper&apos;s Bingham Canyon mine. Modernized facilities include the in-pit crusher, conveyor, ore storage area, concentrator, ore pipe-line, and tailings pipeline. With modernization, Kennecott will achieve substantial cost reductions. Bingham Canyon is now one of the lowest cost copper producers in the world. And the mine will continue to provide jobs and income in Utah for another 30 years or more. The Modernization Project began in February 1986. The work took 33 months. In late 1987, the construction force peaked at 1100 workers. Kennecott Utah Copper now employs a permanent work force of 2100 employees. Less equipment and more efficiency The modernization work has increased the scale of the facilities that transport and process copper ore. A large, continuous transport system has replaced multiple haulage units. Fewer but larger pieces of equipment have replaced many crushing, grinding, and flotation units. The result is less maintenance, fewer employees, and improved metal recoveries. About one-third of the $400 million modernization project is directed at improving ore movement by eliminating rail transport. The new concentrator accounts for the remaining two-thirds of the modernization investment. The modernized plant was started up in stages. In February, ore was fed to the crusher. By the end of March, the three grinding lines were operating and the flotation circuit was producing copper concentrate. In July, the design through-put rate of 70 kt/d (77,000 stpd) was reached. October saw the achievement of targeted metal recoveries that corresponded to the fully modernized operation. It is estimated that Bingham Canyon will annually produce 181 kt (200,000 st) of refined copper, 9.3 t (300,000 oz) of gold, 71 t (2.3 million oz) of silver, and 5.4 kt (12 million lb) of molybdenite. Current Bingham Canyon production is about 97 kt/d (107,000 stpd) and a similar amount of overburden. Some 70 kt/d (77,000 stpd) of ore are processed through the in-pit crusher and 27 kt/d (30,000 stpd) of ore are transported by rail. The Bingham Canyon mine has yielded more than 11 Mt (12 million st) of refined copper. In 1863, precious metals - silver-bearing lead - were first discovered in Bingham Canyon. What was once a mountain is now a huge open pit. In fact, the mine is the world&apos;s largest man made excavation. The pit is some 4 km (2.5 miles) wide and 0.8 km (0.5 miles) deep. Since the pit began operating in 1906, more than 4.5 Gt (5 billion st) of material have been removed. Modernized facilities Electric 21 m3 (27 cu yd) or 23 m3 (30 cu yd) shovels are used to load the haulage trucks. Both 154 t (170 st) and 181 t (200 st) trucks are used to haul the ore to a mobile, in-pit crusher. The crusher replaces three crushers located at the old concentrators. There are two dumping locations at the new crusher, which can handle two trucks a minute. The 1.5 x 2.7 m (60 x 109 in.), 745 kW (1000 hp) Allis-Chalmers gyratory crusher reduces the ore to 254 mm (10 in.) size or less and delivers it to the conveyor. The crusher and conveyor systems are capable of handling 9 kt/h (10,000 stph) of ore.

Jan 11, 1988

By J. J. Gusek

An 81 hectare (200 acre) tailings impoundment at a taconite operation in Wyoming that ceased operations in 1983 has been a source of blowing dust. The site qualified for reclamation under Wyoming&apos;s Abandoned Mine Land (AML) reclamation program. The ultimate reclamation construction included: incorporating commercially available organic amendments and fertilizers into a 300 mm (12 in) thick "cap" of a sterile clay loam cover material, lowering the water level in an adjacent flooded mine pit that was feeding uncontrolled seeps into the tailings basin, constructing a wide tailings pond spillway that allows flood control while minimizing seasonal water level fluctuations in the pond, and building rock berms and rock snow fences for wind erosion control and soil moisture preservation. Tree planting in the protective wind/snow shadows of rock berms and rock snow fences, and the plugging of a decant pipe are planned for future work.

Jan 1, 1998

By Verya Nasri

This paper will present the design and construction of a deep underground station of the Réseau Express Métropolitain (REM) project; the Édouard Montpetit station. The Édouard-Monpetit station is an interchange station that will connect the deeply sitting REM tracks to the existing metro station of the same name located closer to the surface. Édouard-Montpetit station is expected to be the deepest in North America, surpassing the famous Forest Glen Station. The various challenges and solutions put forth for the successful completion of this underground work are presented to serve as a valuable example for future deep excavation performed in urban area, in the close vicinity of highly sensitive structures.

Jun 13, 2021

By A. Pezzuto

"Pipes are used on mine sites in a variety of applications including transport of slurry, conveying clean and processing water, and in mine dewatering. Mine waters and slurries can cause pipe wear and failures via several mechanisms (or combinations thereof) such as abrasion, scaling, and corrosion. Polyethylene (PE) pipe materials have grown in popularity over the past several decades due to their chemical and mechanical properties (e.g., inertness, flexibility, relatively low density) and low cost. While PE is generally resistant to corrosion, it is subject to abrasion. To combat this, a novel, rubber-like liner is in development. In addition to comprehensive abrasion testing, however, the liner must be evaluated to see how it performs under other conditions. Here, a brief field study is described that tested PE pipes with the new liner against traditional PE pipes to specifically assess mineral scale buildup. The study was conducted in the Reiche Zeche study mine in Freiberg, Germany in six different locations with varying water qualities and flow conditions. INTRODUCTION Water and slurry conveyance are major operations on and around mine and mill sites, from mine dewatering, to tailings transport, to water treatment processes. Conveyance systems in such applications can include great lengths of pipe materials along with pumps and monitoring instruments, and thus represent significant capital investments. Due to the variability of the physical and chemical properties of water and slurries, pipe materials are subject to a wide range of conditions. These can cause pipe wear and eventually failure leading to serious economic, environmental and social, consequences. While pressure-induced pipe failures (e.g., ruptures or ""bursts”) can be immediate, most failure mechanisms involve gradual processes. Scaling and sedimentation can present major problems for pipe systems conveying highly mineralized waters. Sedimentation generally refers to the deposition of suspended solids, such as sand, clay, silt, or organic matter onto pipe surfaces. This phenomenon can occur due to a decrease in water velocity or particle collisions with the pipe wall. Scaling, on the other hand, commonly refers to the deposition of precipitated mineral salts (including oxides and hydroxides) onto pipe surfaces. Mine waters often have extremely high ion concentrations (i.e., high dissolved solids content) due to their interaction with enormous surface areas of minerals, which are exposed during mining and processing operations (Brown and Barley, 2002). As these waters are transported, slight changes in temperature, pressure or chemistry (e.g., pH or ORP) can cause instability with respect to ion solubility such that salt precipitation begins to occur. “Seed” crystals can rapidly grow and attach to pipes, either due to local surface phenomenon near the pipe wall (e.g., which can promote coagulation) or sedimentation of the precipitated solid. Whether due to suspended or precipitated solids, as the solids begin to stick to pipe walls, “aging” or hardening processes can commence; and the build-up of scale can become self-perpetuating as the scale itself provides an attractive “nucleus” for further attachment of particles or crystal growth (Muryanto et al., 2014). Over time, scale-buildup reduces the effective pipe diameter, which can ultimately result in decreased flow velocity, clogging and, in some instances, bursting (Dirany et al., 2016)."

Jan 1, 2017