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By L. W. Swent

Dr. Emrick, honored guests, distinguished speakers, ladies and gentlemen, I am Langan Swent, Vice President for Environmental Affairs and Occupational Safety and Health, of Homestake Mining Company. Today, I appear on behalf of the American Mining Congress, as chairman of its uranium mine health subcommittee. The American Mining Congress is a trade association of several hundred members, which include the producers of a large proportion of the nation's uranium. I've been asked to make a statement of principles for the uranium industry. There are two types of principles that apply to industry in general, and specifically to the uranium industry. Some have external origins and apply regardless of what industry does or thinks. Others are generated by industry itself and serve as goals for the industry. I'll discuss some of each type. I'll limit my statement to those principles related to the subject of this conference--radiation hazards in mining. I won't take your time trying to explain some of the unrelated principles that we must all contend with, such as Parkinson's Laws, Murphy's Law, and the Peter Principle. First and foremost, industry has a sincere interest in the well-being and health of its employees. There are two basic reasons for this. One is a basic respect for human lives, especially those of people we see and work with every day. No one in management wants to carry the lifelong burden of blame for a life lost due to poor working conditions. Most uranium and other mining is done in small communities. Production workers, maintenance workers, service workers, shift bosses, foremen, superintendents and managers all live in the same community. They attend the same churches. They serve together in civic activities. Their children go to the same schools. If one employee in such a community loses his life due to poor working conditions, those remaining know in a daily and intimate way the resulting personal tragedy, usually of a bereaved widow and fatherless children. This sad experience makes the community, including industry management, intensely sensitive to the need for maintaining good working conditions in the mines. But what about the segment of industry that does not live in the mining communities? Corporate and owner's offices are frequently hundreds of miles from the communities where the mining takes place. Many of these people are not personally acquainted with the workers, and there are few close personal ties between the two communities. The distant staff are, however, still human beings and motivated by the same basic human respect for life. Mr. Manuel Gomez of MSHA and a member of the planning committee for this conference summed this point up expressively when he told me: "No one group has a corner on compassion." In addition to compassion, there is another factor. In both communities the basic assignment to everyone is to produce profits. In carrying out this assignment, supervisory and management people are acutely aware of the high cost of illnesses and accidents. Their objective of maximizing profits is advanced significantly by minimizing illnesses and accidents at the mines. A business that has illnesses and accidents generally suffers from poor employee morale and high employee turnover, both of which detract from profits. Next, I would like to talk about what industry has done in the field that is the subject of this conference. We have worked at all sorts of methods to reduce exposure of employees since the exposure standards were first introduced and then lowered. Other speakers will go into details of technology, and I'll simply comment on exposure results. These are best shown in Table 1. The table shows the average WL to which miners in U.S. underground uranium mines have been exposed since 1937 through 1980. The trend of decreasing radon daughter concentrations throughout the period is obvious. Figure 1 presents this data graphically and shows the trend at a glance. This record begins in 1937 when uranium, as such, really wasn't being mined or sought. The concentrations given by the U.S. Public Health Service were for a few small vanadium mines which carried uranium as a by-product. A few years later, when the Manhattan project to develop the atomic bomb was begun, these mines became the first U.S. uranium mines and the vanadium became the by-product! The radiation hazard then also received attention and the average concentrations began to decline. As knowledge of the reality of the hazard spread, conditions improved. The search for uranium in the U.S. turned up new and larger ore bodies that had to be mined by large underground mines. These mines involved ventilation planning from the beginning, and when they came into production in the late 1950's they lowered the average concentrations greatly. Then in 1960 the American Standards Association adopted a standard setting 1 working level as a satisfactory condition, and several action levels up to 10WL, at which point removal of people from exposure was called for. As a result of the uranium producing states governors' conference in December 1960, state mine inspection agencies, in the early 1960's, began to adopt and enforce the ASA standards. As a result, average concentrations again declined. In 1967, the Federal Radiation Council recommended an annual limitation of 12 WLM per individual. This represented a great change in the methods of

Jan 1, 1981

By Harold B. Goldman

On the basis of tonnage, the sand and gravel industry is the second largest nonfuel mineral industry in the United States. In 1990, the production of sand and gravel was 927 Mt valued at $3.4 billion. California, which leads the nation with more than 126 Mt, together with Texas, Washington, Michigan, and Ohio, account for 36% of the total production in the nation (Table 1). In commercial usage, sand applies to rock or mineral fragments ranging in size from particles retained on a No. 200 Sieve (0.074 mm openings) to those passing a No. 4 Sieve (4.76 mm openings). Gravel consists of rock or mineral fragments larger than 4.76 mm, ranging up to 88.9 mm maximum size. The construction industry consumes 97% of the sand and gravel produced; the remainder is sand used for specialized products such as glass (see chapter on Industrial Sand and Sandstone and Glass Raw Materials). Utilization The building industry uses sand and gravel chiefly as aggregate in portland cement concrete, mortar, and plaster; the paving industry uses sand and gravel in both asphaltic mixtures and portland cement concrete. Aggregate is commonly designated as the inert fragmental material that is bound into a conglomerate mass by a cementing material such as portland cement, asphalt, or gypsum plaster. Sand and gravel is also used as construction fill, road base and subbase, and decorative material. Portland Cement Concrete Aggregates: Portland cement concrete consists of sand and gravel surrounded and held together by hardened portland cement paste. Concrete mixes commonly contain 15 to 20% water, 7 to 14% cement, and66 to 78% aggregate. Sand and gravel used as concrete aggregate have to meet many requirements (Goldman and Reining, 1983). Premature deterioration of concrete has been traced in many instances to the use of unsuitable aggregates. Asphaltic Aggregate: Asphaltic mixtures used predominantly for paving consist of combinations of sand, gravel, and mineral filler (material finer than 0.076 mm), uniformly coated and mixed with asphalt produced in the refining of petroleum. Sand and gravel used as asphaltic aggregate must meet the same general physical requirements as materials used for portland cement aggregate. GEOLOGY General Requirements of Aggregates Construction aggregate has many requirements that are difficult to meet if only unprocessed material from natural deposits is used. Suitable material is composed of clean, uncoated, properly shaped particles that are sound and durable. Soundness and durability are terms used to denote the ability of aggregates to retain a uniform physical and chemical state over a long period of time so as not to disintegrate when exposed to weathering and other destructive processes. Individual particles must be tough and firm, possessing the strength to resist physical stresses and chemical and physical changes, that may cause swelling, cracking, softening, and leaching. The aggregate should not be contaminated by excessive clayey material, silt, mica, organic matter, chemical salts, and surface coatings. Physical Properties: The quality of aggregate depends upon its physical and chemical properties. These, in turn, may be inherent mineralogical and textural features of the rock or may be the effects of later changes such as tectonics, mechanical or chemical weathering, or incrustations. The physical properties most significant for concrete use are: 1) abundance and nature of fractures and pores, 2) particle shape and surface texture, and 3) volume changes which may occur because of freezing and thawing or wetting and drying. An aggregate is considered to be physically sound if it is adequately strong and capable of resisting the agencies of weathering without disruption or decomposition. Minerals or rock particles that are physically weak, extremely water absorptive, and easily cleavable are susceptible to breakdown. The use of such materials in concrete reduces strength or leads to early deterioration by promoting weak bond between cement and aggregate, or by inducing cracking, spalling, or popouts. Severely weathered, soft, micaceous, or porous materials may cause localized stresses to develop in concrete by swelling and shrinking during wetting and drying or freezing and thawing cycles. Physical Suitability of the Various Rock Types. Sedimentary rocks have a wide range in physical and chemical qualities. Sand- stones and limestones, if hard and dense, are ordinarily satisfactory, but many sandstones are friable and excessively porous and commonly are clay-bearing. Shales generally make poor aggregate material, being soft, weak, and absorptive. Most igneous rocks are satisfactory, being normally hard, tough, and dense. Tuffs and certain flow rocks may be extremely porous and have high water absorption and low strength. Metamorphic rocks differ in character. Most quartzites are massive, tough, and dense. Fine-grained marbles are usually durable, but coarse-grained marbles have low abrasion resistance. Gneisses are ordinarily very tough and durable. Some schists contain micaceous minerals that are undesirable because they are soft, laminated, and absorptive. Micaceous minerals are susceptible to splitting along cleavage planes and thereby impair particle strength and durability. Some schists and slates in particular are thinly laminated and tend to assume flat slabby shapes that lack strength-and do not pack well. Any or all of these rock types may be rendered undesirable because of harmful exterior coatings. Weathering processes, particularly the action of ground waters, deposit these coatings. The most common coatings are calcium carbonate, clay, silt, opal, chalcedony, iron oxide, manganese oxide, and gypsum. Particles with these coatings are undesirable as aggregates because the bond between particle and coating may be weak, and decreasing the strength of the aggregate-cement bond.

Jan 1, 1994

By O. J. R. Baena, D. E. Chaverra, C. D. L. Ramirez

Cyanide is one of the most used reagents in the precious metal extraction process; as well as the most efficient from the point of view of the dissolution process; but it is also a toxic product that requires a lot of care in handling. Likewise, the residual solutions of the process must be followed because they can be a risk of contamination of water, animals and human health. In the artisanal processes of obtaining gold and silver, neutralization of the residual solutions is used to passivate the present cyanide. During this process ammonium cyanate is formed which decomposes rapidly in the presence of air and sunlight in carbon dioxide and ammonia gas, contributing to the greenhouse effect. In this work the use of the ammonium cyanate obtained in the process of neutralization of the cyanide solutions as a reagent to obtain urea is proposed. Urea was obtained indirectly through the use of the reagent kit UREA/BUN-COLOR. The process is effective at pH ≤ 4.5 with a rapid increase in solution temperature, and addition of hydrogen peroxide. The urea crystals begin to form at 50°C. The cyanide / urea ratio obtained was 1 / 7.5 INTRODUCTION In the processes of extractive gold metallurgy, the use of cyanide leaching is perhaps the most widely used method worldwide; by the ease of operation, its low cost and high levels of precious metal recovery. However, neutralization, in most processing plants, is not done properly, and leftovers of solution with free cyanide are dumped in concentrations harmful to the environment, in particular animals and humans. Cyanide can enter surface water through releases from industries using cyanides. Due to its high toxicity, the presence of cyanide in water is a matter of great concern (Jawale et al., 2017). The pollution generated by the effluents from the leaching of gold ores is one of the main obstacles of social opposition presented by mining activity due to the impact of both surface and groundwater. During the cyanide decomposition process, a compound known as ammonium cyanate OCN(NH4), which is a raw material for the manufacture of urea, CO(NH2)2 is generated. In the case of good neutralization, cyanide is no longer a toxic compound through oxidizing reagents, but as a result, there is the generation and emission of ammonia and carbon dioxide into the atmosphere, generating both a greenhouse effect (Gómez, 2012). This is evidenced by the strong effervescence of the reaction, and a penetrating smell of ammonia, which can irritate respiratory mucous membranes and eyes; however because they are greenhouse gases they are considered pollutants.

Jan 1, 2019

By Sadatoshi Ohmori, Karen Shinoda, Nobuharu Isago

Method of tunnel excavation is generally classified such as full-face excavation, bench-cut excavation, diaphragm with center pillar excavation, center drift advancing excavation and so on. These excavation methods should be selected properly in terms of ground condition, the area of tunnel section, the arrangement of construction. Center drift advancing excavation method in mountain tunnel construction, is often applied under quite weak ground condition, prior to the main tunnel widening excavation. Recently, the advancing drift is for the excavation of extreme larger section in main tunnel to confirm the stability of face. In addition, we make advancing deformation occur in drift when the construction was done in poor ground like squeezing and swelling ground, and the force occurred in main tunnel was expected to reduce by the effect of ‘dodging’ for support structure. Mechanical relation between drift and main tunnel has been mainly grasped on past experiences in Japan. However, the characteristic of tunnel enlargement was partially discussed by using the three dimensional analysis and the result was grasped by past experiences on the basis of each tunnel construction. It is considered that the natural ground stress is normally released as the advance displacement, but it was released after the main tunnel widening, causing a displacement and deformation increase. Up to now, the construction practice has shown the reduced displacement during the main tunnel widening excavation by the drift, and the numerical analysis agreed with above observation. However, there is no report found that the displacement and deformation at the time of widening excavation of the main tunnel become larger in case of a drift application. In Kyusyu area, western part of Japan, the northern part of Yoshinomoto tunnel was applied an advancing bench-cutting method for a center drift for the purpose of obtaining the geological information for support selection of the main tunnel in widening excavation. The shape of center drift was a perfect circle with a diameter of 4.0 m or 6.0 m and the same temporary support regardless of the geological situation. As a result, the displacement and deformation of the main tunnel after widening excavation were larger than the section where the center drift was not applied. Furthermore, the displacement and deformation of the main tunnel after its widening excavation was considered larger in the section where the cross-section of the center drift with 4.0 m diameter was applied than one with 6.0 m. Therefore, the center drift with a high rigidity support structure had the effect of suppressing the advancing deformation prior to the main tunnel widening excavation.

Jun 13, 2021

By A. Cecala, J. Noll, J. Hummer

"NIOSH has observed that many control rooms and operator compartments in the US mining industry do not have filtration systems capable of maintaining low dust concentrations in these areas. In this study at a mineral processing plant, to reduce respirable dust concentrations in a control room which had no cleaning system for intake air, a filtration/pressurization system originally designed for enclosed cabs was modified and installed. Eighty-seven percent of submicron particles were reduced by the system at static conditions, meaning that greater than eighty-seven percent of respirable dust particles should be reduced. The particle size distribution for respirable dust particles are greater than for submicron particles, and filtration systems usually are more efficient in capturing the larger particles. A positive pressure near 0.02 inches of water gauge was produced which is an important component for an effective system and minimizes particles (e.g. dust) from entering into the room. The intake airflow was around 118 cfm, which is greater than the airflow suggested by ASHRAE for acceptable indoor air quality. INTRODUCTION Chronic overexposure to respirable silica dust (particle diameter < 10 microns) leads to a progressive lung disease known as silicosis. Workers who develop silicosis have an increased incidence of lung cancer and pulmonary disorders. In June 1997, the International Agency for Research on Cancer (1) found sufficient evidence to declare that inhaled crystalline silica in the form of quartz and cristobalite is carcinogenic. Mining is one of the leading industries for occupational exposure to silica dust (2-7). Control rooms located in dusty areas in some mines are of particular concern (8). Many mineral processing operations utilize operator’s compartments and/or control rooms to house workers who are performing particular job functions. Most industrial processing mills have rooms where a worker looks out over the facility and has direct control over the product flow throughout the entire building. In addition, primary crusher operators are often located in a compartment from which they are able to view the primary crushing function. Their job is to control when trucks dump into the primary jaw crusher and the rate of feed of the ore from the hopper into the crusher. Many of these control rooms and operator booths do not have filtration systems capable of cleaning air entering the control room or booth, which can result in elevated concentrations of dust in the room or booth. To reduce the dust concentrations in these rooms, it would make sense to clean the entering air with filtration/pressurization units similar to those proven to provide a clean environment in enclosed cabs."

Jan 1, 2016

By Patricia Pride, Kurt Bettger, Jack Raymer

"INTRODUCTION The Jefferson Barracks Tunnel is in the final stages of design and is expected to go out to bid in the summer of 2016. The project is located in south St. Louis County along the west bank of the Mississippi River, about 13 km downstream of the St. Louis Gateway Arch. The project consists of a deep sanitary sewer tunnel, a deep pump station and several intakes. The intakes will divert sanitary flows into the tunnel and the tunnel will convey the flows by gravity to the Lemay No. 3 Pump Station, which will pump them up into the Lemay Waste Water Treatment Plant. The tunnel is about 5.4 km long and will be lined with 84-inch (2.1 m) fiberglass pipe. It drops at a gradient of 0.1 percent from south to north and will be bored through strong limestone using a hard-rock tunnel boring machine (TBM). The diameter of the TBM is anticipated to be about 3.4 m. The Owner’s original concept was for a relatively shallow tunnel so as to minimize construction and pumping costs. The preferred alignment ran close to the river, next to the existing force main, which was to be abandoned. Keeping the tunnel close to the force main would reduce the amount of shallow sewer work needed to connect the existing feeder sewers to the new tunnel. Several geotechnical investigations were performed, with shallowly focused geophysics and the borings all going exactly down the conceptual tunnel depth. Limestone bluffs run along the Missouri side of the river. These bluffs are pockmarked by sinkholes and riddled with karst. Large, well-known caves occur both north and south of the alignment. Karst features, including deep crevices and possible caves, were found in those early geotechnical investigations. Many of these features extended well below the level of the Mississippi River and would have been encountered by the tunnel. If a large crevice or cave were encountered, then the inflow of mud and water into the tunnel could have been large and possibly uncontrollable. Something had to be done to mitigate this situation. Pre-excavation grouting was considered, but the program would have been huge and extremely expensive. Using a closed-face TBM with bolted and gasketed lining was also considered, but that too was both risky and extremely expensive. The Owner could have abandoned the tunnel altogether and built a new force main, but that would have brought a whole new set of problems and was undesirable to the Owner. The last option was to move the tunnel away from the karst."

Jan 1, 2016

By Jiang Su, Michal Uhrin

"The use of composite linings, consisting of permanent sprayed primary and secondary linings with a sandwiched spray applied waterproofing membrane is expected to improve efficiency and reduce lining thickness, but it also brings complex primary-secondary lining interaction. This issue is further complicated by the uncertainty regarding the long-term behavior and parameters of the sprayed concrete–sprayed membrane interface.This paper aims to address this issue by presentation of a series of numerical analyses of a typical shallow SCL tunnel in soft ground with a range of design assumptions on the interface behavior: (1) compression only; (2) compression and tension; and (3) compression, tension, and shear.The results demonstrate that the assumed interface behavior has a significant impact on the primary-secondary lining interactions. A design approach of ignoring the tension and shear bond at the interface may not be conservative particularly for serviceability. This paper explains the rationale behind these conclusions and discusses the implications for design.INTRODUCTIONSprayed Concrete Tunnel Lining SystemsSprayed concrete linings (SCL) have been used in conventional tunneling for decades. However, details of SCL systems may differ to a large extent depending on ground conditions and specific tunneling methodologies.In hard rock conditions, for example, drill and blast excavation is typically supported by rock bolts and sprayed concrete (NGI 2014). Such tunnels are usually designed fully drained and the above-mentioned support elements considered permanent without the need for a further inner liner. Therefore, there is no structural interaction between separate lining shells to consider.In conventional tunneling in the European Alps, a double shell lining is typically utilized, consisting of an outer (primary) sprayed concrete lining and an inner (secondary) cast-in-place concrete lining, separated by a waterproofing system. The primary lining normally includes rock bolts and may include other support elements. The waterproofing system is usually based on a plastic membrane and a geotextile fleece. The tunnel may be designed fully or partially drained or fully undrained. Although there are two structural lining shells interacting, investigation of such interaction is generally irrelevant to designers because the primary lining is considered only temporary (fully sacrificial in the long term). An overview of reasons for this assumption is given, for example, by Lemke (2014). The secondary lining is designed to resist all foreseeable loads on the tunnel. The primary lining may, in reality, interact structurally with the secondary lining during the life span of the tunnel. However, since the secondary lining design must cover all possible (extreme) scenarios, investigation of such interaction does not bring any value to the design."

Jan 1, 2016

By W. R. Reed, G. J. Joy, B. Kendall, A. Bailey

"Testing of the NIOSH-designed roof bolter canopy air curtain (CAC) has gone through many iterations demonstrating successful dust control performance under controlled conditions. J.H. Fletcher & Co. (Fletcher), an original equipment manufacturer of mining equipment, has further developed the CAC concept by incorporating it into the design of its roof bolting machines. A new CAC design has been developed incorporating the results of testing of the NIOSH design and the recent Fletcher design. Observations from smoke testing conducted on this new CAC design in a laboratory setting show promise for improved performance. INTRODUCTION Exposure to respirable coal mine dust can cause coal workers’ pneumoconiosis (CWP) otherwise known as black lung. If silica is present in the dust, the miner may develop silicosis in addition to CWP. CWP and silicosis are occupational respiratory diseases that are ultimately fatal and have no cure. The only method of prevention is through elimination of exposure to respirable coal mine dust and crystalline silica (quartz). The current occupational exposure limit (on an MRE basis) for respirable coal mine dust is 2.0 mg/m3 during each shift that a miner is exposed in the active workings of the mine or in mine facilities [30 CFR 70.100 2015]. Recently enacted legislation changes this standard beginning in August 2016 to 1.5 mg/m3 for a full working shift [Federal Register, 2014]. If the respirable coal mine dust contains more than 5% silica, the applicable respirable dust standard is reduced; calculated as 10 divided by the percent quartz present [30 CFR 70.101] so that the effective exposure limit for respirable quartz is 0.1 mg/m3 for a full working shift. Sources of exposure to respirable coal mine dust for the roof bolting occupations include infrequent maintenance and cleaning of the vacuum dust collection system and operating the bolter downwind (in the return air) of the continuous miner [Goodman and Organiscak, 2003]. Recent studies have demonstrated that vacuum dust collection systems are effective in capturing bolter-generated dust, if maintained and operated correctly and if proper face ventilation techniques are used. However, most exposure to respirable coal mine dust for the roof bolter occurs when the roof bolter machine is operated downwind of the continuous miner [Potts et al., 2011; Colinet et al., 2013]. Because of this higher exposure downwind of the continuous miner, the roof bolter is generally limited to working downwind of the miner only once during a production shift"

Jan 1, 2016

By A. D. Hammond

"INTRODUCTION Vanadium deposits in Arizona are distributed all across the state, from the rim of the Grand Canyon to the Tombstone mining district in the southeast corner of the state (Figure 1). The combined past production of vanadium from Arizona and New Mexico ranks second nationwide, after deposits in the Colorado Plateau In the northeast corner of the state, in the Carrizo Mountains and Monument Valley of Apache and Navajo Counties, vanadium was produced as a by-product of uranium in deposits of the Salt Wash and Shinarump members of the Morrison and Chinle formations, respectively. The production took place between 1943 and 1970. Another source of vanadium in Arizona occurs in vanadate deposits associated with supergene enrichment of base-metal vein and replacement deposits. The most important vanadate mineral is vanadinite, a chloro-vanadate of lead. Presently, there are no primary mines of vanadium in the United States. In 2012, a small production of vanadium pentaoxide (V2O5) was reported as a by-product of uranium at the White Mesa uranium mine in Utah1. This paper describes vanadate deposits in Arizona with emphasis in three districts, namely, the Mammoth, Globe-Miami and Banner districts.VANADIUM EPIGENETIC DEPOSITS: VANADATES Almost all vanadium epigenetic deposits occur as vanadates in oxidized zones of lead, zinc and copper veins and replacement deposits. Vanadinite, descloizite and mottramite are the most common minerals in vanadate deposits. Descloizite is a vanadate of lead, zinc and copper. Wulfenite, a molybdate of lead is also present. These minerals replace supergene base-metal minerals, form crusts on faces of open cavities, or are inter-grown with residual clays in pockets. The vanadium content in vanadate deposits is believed to have been leached from the country rock by ground-water and transported through porous rocks until precipitating as a relatively insoluble vanadium compound or until the solution evaporated. Precipitation was brought about by local concentrations of cations of divalent lead, zinc or copper. Lead is a constituent part of almost all of vanadate deposits and the vanadium pentaoxide (V2O5) content in vanadate minerals seems to have a direct correlation with the content of lead in the hypogene mineral. Vanadate deposits are restricted almost entirely to the oxidized parts of vein or replacement deposits. It is rare that oxidized zones extend past 100 ft from the surface. Vanadate deposits are largely restricted to tropical and temperate zones and regions of dry climate. Arizona and New Mexico have the largest concentration of vanadate deposits in North America."

Jan 1, 2015

By Thomas Camus

"STATE OF THE ART The current situation of ground prediction in TBM is of great concern for tunnelling contractors, and the subject has been quite widely addressed over recent years, for instance by the French Eupalinos 2000 programme, which tested a variety of technological approaches. A number of interesting projects were executed, such as the SOUND and OnSITE projects, part of the German Geotechnologien programme: these projects are focused on seismics, while other techniques such as radar are not considered. Little information and even less industrial applications have been released apart from lab simulations and numerical modelling. A number of field tests in different configurations have been carried out for compression waves, but the results were often not reliable or convincing, and therefore little has been reported in open literature. The advances seem somewhat promising as far as hard rock tunnels are concerned, but ignore the problem raised by concrete lined tunnels such as those bored by a TBM in soft ground. In such tunnels, sending and receiving seismic waves reliably through the lining (and the grouting behind) is quite illusory. A careful analysis of the seismic prediction research results show that the main problem is the source which is poorly controlled and poorly coupled (for instance in concrete lined tunnels, or in approaches that use the TBM cutter head vibrations as a source). Generating waves perpendicular to the tunnel axis is also a problem: aligning with the tunnel axis makes more sense. Radar (Ground Penetrating Radar - GPR) has been used in geotechnical surveys for decades, and also for tunnel inspection. Attempts have been made at using it on a TBM (for example in Japan by Taisei) but mainly using off-the-shelf GPRs, which are not adapted to work in the specific environment of a TBM (because of its huge mass of metal, to start with). Very few results have been published, probably due to the somewhat disappointing performance of such implementations. At present, no TBM has a GPR incorporated in its cutter head that is able to predict ground characteristics while drilling. Another characteristic and drawback of most current methods is that they require dedicated periods of time during which other tunnel construction activities must be stopped. Due to the duration of such operations this leads to performing ground prediction on a weekly basis only, and therefore to a requirement for an investigation range of 100 metres approximately (in order to cover the TBM advance over the coming week). This is not achievable with boreholes made from the TBM, even less if a reasonable accuracy is required, as is usually the case."

Jan 1, 2016

By Art Hamid, Manfred Wong, Carlos Jaramillo, Greg Raines, John Caulfield

"The Central Bayside System Improvement Project (CBSIP) is a critical element of the Sewer System Im-provement Program (SSIP), a 20-year, $6.9-billion investment by the San Francisco Public Utilities Commis-sion (SFPUC) to upgrade San Francisco’s 100+ years old seismically vulnerable combined sewer system. The CBSIP’s centerpiece, a proposed 10,000-foot-long (3,048-meter-long) Channel Tunnel, will provide reliable and redundant gravity conveyance and storage of combined wastewater flows from the northern and central parts of San Francisco to the Southeast Water Pollution Control Plant (SEP) while ensuring compliance with regulatory requirements for combined sewer discharges to the Bay. A tunnel with a diameter of 23 to 30 feet (7 to 9 meter) is being planned using pressurized-face tunnel boring machine technology. Project challenges include tunneling through Franciscan Bedrock, mixed ground conditions in close proximity to the Bay, connector tunnels and shafts, construction in congested urban environment, and challenging real estate issues for shaft access. BACKGROUND AND NEED FOR TUNNEL The City of San Francisco is one of the most beautiful cities in the world. About 850,000 people live in the city and many more come to work, for tourism, and for attending conferences. The SFPUC is a department of the City and County of San Francisco that provides energy, drinking water and wastewater services to San Francisco, wholesale water to three Bay Area counties, and green hydro-electrical and solar power to San Francisco municipal departments. The SFPUC wastewater system includes tunnels, large storage/transport boxes, 1000 miles of collection sewers, 28 pump stations, and three wastewater treatment plants. San Francisco’s combined sewer system collects both wastewater and stormwater in the same sewers, which is then pumped, treated to stringent state standards and discharged into the San Francisco Bay and Pacific Ocean. After decades of service, much of the sewer system is nearing end of its working life. During the 1989 Loma Prieta earthquake, damage to SFPUC water and wastewater infrastructure was extensive. The 11,200-foot-long (3,400-meter-long), 66-inch-diameter (1,676-mm-diameter) Channel Force Main, built in 1976, and a critical component of the SF wastewater system was also damaged. This force main carries 70 percent of the bayside dry weather sewage flow from the northern and central part of the city to the SEP. The force main is at the end of its life and was not constructed to the current seismic code; in addition it has no redundancy. Figure 1 shows the project background and the force main that will be provided redundancy by the new gravity tunnel."

Jan 1, 2016

By Peter Zhang, Daniel Su, Heather Dougherty, Jack Trackemas

"Longwall mining has a significant influence on gas wells located within longwall chain pillars. Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well casings. If the gas well casings are compromised or ruptured, natural gas could migrate into the mine workings, potentially causing a fire or explosion. By the current safety regulations, the gas wells in the chain pillars have to be either plugged or protected by adequate coal pillars. The current regulations for the gas well pillar design are based on the 1957 Pennsylvania gas well pillar study. The study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the pillars. As the guidelines were developed for room-and-pillar mining under shallow cover, they are no longer applicable to modern longwall mining, particularly under deep cover. Gas well casing failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 study.This study presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh coal seam. The study indicates that overburden depth and pillar size are not the only determining factors for gas well stability. The other important factors also include subsurface ground movement, overburden geology, and weak floor, as well as the construction of gas wells. Numerical modeling was used to model abutment pressure, subsurface deformations, and the response of gas well casings. The study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above, within, and below the chain pillars, and the potential location and modes of gas well failures, therefore providing a more quantifiable approach to assess the stability of the gas wells in longwall chain pillars.INTRODUCTIONIn the eastern United States, abundant gas wells have been drilled through coal seams that are being actively mined by longwall mining. The existence of gas wells in the U.S. coal fields, whether active or abandoned, have caused many issues for longwall mining. First of all, any gas well in the mining area has to be located by all possible means. Secondly, the gas wells within longwall panels have to be plugged, as cutting through gas wells will allow natural gas to flow into the active longwall mines. On the other hand, the gas wells within longwall chain pillars or barrier pillars can be left in place if the wells are protected by properly designed pillars."

Jan 1, 2019

By Edward I. Erlich

1984 saw the 30th anniversary of a momentous event in Soviet geology-the discovery of kimberlites in Siberia, an event that vaulted the Soviet Union to second rank among the world&apos;s producers of both gem and industrial diamonds. There are many legends associated with this story, legends about those who predicted the discovery and those who achieved it in the field. The story told here unfolded during the field campaigns of the 1940s through 1960s, as witnessed by the authors and their companies of an earlier generation. This story illustrates science, chance, and human emotions at work, resulting in a blend of conviction, courage, bureaucratic sniping, and competition for glory. At the same time, it is an illustration of the workings of the Soviet exploration system. In a broader sense, it is the realization of the Russian image-boundless natural wealth, indomitable ingenuity, and the rigid political economic system that permeates the Russian landscape as well as the people. Most accounts of the Siberian diamond saga begin with statements such as, "This discovery confirmed the predictions of...", or "It was a result of predictions of one of the greatest Soviet geologists, Academician V.S. Sobelov...". These are only part of the truth. It had become apparent even in the 1930s that the Siberian Platform contained one of the Earth&apos;s greatest Basaltic provinces, described in a monograph by Sobolev...; and at the end of the thirties, G.G. Moor of the Institute of Arctic Geology found alnoites, similar in many ways to kimberlites. At the same time, the famous polar geologist, N.N. Urvantsev found other kimberlite like rocks in the southern Taymir Peninsula, adjacent to the Siberian Platform. In publications describing these rocks, Moor and Urvantsev mentioned for the first time the possibility of finding diamondiferous kimberlites similar to those in South Africa. Unfortunately, Urvantsev spent little time in the field between terms in concentration camps. Moor was considered by his superiors to be no more than a good descriptive petrographer; they suggested to him that his conclusions should be backed up by more highly regarded specialists. Thereupon, Moor asked Sobolev to coauthor a paper with him and this became the widely quoted prediction about diamonds in Siberia. Another early paper should also be mentioned, an unpublished paper found by M.I. Rabkin in the geological archives of the Norilsk Metallurgical Plant, written by Yu. M. Sheinmann when he worked in the concentration camp there in the late forties. This report placed the probable location of yet-to-be-discovered kimberlites within less than 100 km of their correct location.

Jan 1, 1990

By J. Sidhom, W. Fourie

"As the mining industry continues to face difficult challenges the need to persistently focus on productivity and utilization of labor and equipment costs will intensify. With these challenges in mind, Joy Global is helping to bring mining performance and analytics to the next level. By evaluating underground haulage, a significant component of the Room and Pillar mining value stream, variables have been identified and sensitivities have been performed to show opportunities to balance and streamline throughput. As a result of applying operational excellence tools to the mining environment, Joy Global is seeking to optimize mining performances by limiting waste, simplifying the process, increasing productivity and machine utilization, as well as removing workers from harm’s way. These days it’s not enough to work harder; mines have to work smarter. Improving efficiency, reducing costs, increasing safety: these are no longer ‘nice to haves’, they are ‘must haves’. Starting with the best products and the right people is a first step, but then what? How do mines take their operations from just OK to being a top performer? By using operational excellence principles aimed at eliminating waste, simplifying processes, automating where possible and removing people from harm’s way. The fundamentals of operational excellence (OpEx) are based upon the DMAIC process, which stands for define, measure, analyze, improve and control. DMAIC is an improvement cycle that helps with, for example, haulage optimization by: defining the issues and problems in the process as well as the areas of improvement; measuring and collecting mining operational data by time study and equipment monitoring system; analyzing through sensitivities and production modelling to determine root causes; then improving the performance and controlling the operation. Joy Global uses Joy OpEx or ‘lean’ principles inside its organization to drive efficiency, but it also helps its customers employ them to achieve new levels of productivity and safety. These same principles can be applied in most situations to streamline processes, improve operations and deliver value. As applied to mining, OpEx is seen as moving the needle on value creation by first identifying the value stream, then analyzing the areas that are not optimized. Once defined, these areas are ‘designed out’ of operational processes to create an automated operational flow. At a US coal mine, Joy Global was brought in to apply Joy OpEx principles to optimize mining and haulage to improve productivity and reduce costs. This multi-phase process started by defining the existing systems challenges to start finding areas for improvement."

Jan 1, 2017

By John H. N. Yen, James M. Marquardt, Larry H. Heflin

INTRODUCTION On February 17, 1995, WMATA Contractor J.F. Shea holed through the last segment of rock tunnels of the planned 103-Mile Rapid Transit System for the Washington Metropolitan Area Transit Authority. Through the joined efforts and cooperation between the owner and the contractor, the project was completed on time and within budget. The Glenmont extension is on schedule to open in Mid-1998. The complete 103-mile system is scheduled to open in 2001. WMATA’s earlier 19 miles of rock tunnels had been done since 1976 ? By drill and blast with heavy horseshoe steel sets, sets with shotcreting over wire-fabric by TBM and NATM. All rock tunnels were primarily in metamorphic gneiss and schist, part of an east coast lithology that outcrops in a band running from below Richmond, Va. To above New York City. The 5,400 ft. long twin six meter tunnels of the Glenmont line had been earlier de-signed in 1979 by URS of NYC using Jenny Engineering of Pittsburgh, Pa., as a tunnel design specialist sub consultant. Jenny had provided two alternative designs, one conventional drill and blast horseshoe and one for Tunnel Boring Machine. Funding considerations had put the design on the shelf and it was clear that the state of the art had led to improved design methods in the intervening years. Before URS was tasked to update their design in1992, the Authority reviewed its earlier hard-rock experiences in light of the funding mandate to complete each segment on a limited budget and an expedited schedule. Many factors considered and many opinions were in leading to a final decision to drop the earlier designs and redesign for a single designated means of tunneling. That method was the New Austrian Tunneling Method. The NATM had been used earlier on WMATA for both soft-ground and rock tunnels. In the public’s eyes the NATM had become inextricably linked with the use of PVC’s and filter material enveloping or partially enveloping the underground structures to give the holy grail of tunnels, a water-tight structure. Although this link of waterproofing methods with excavation and support methods was essentially severed, a general feeling of their interdependence no doubt helped lead to acceptance of the NATM decision because of the waterproofing design that accompanied it. The Authority decided to drop the TBM and conventional options and provide bid documents for NATM only. URS asked LAW Engineering of Atlanta to provide the NATM design of the tunnels and associated shafts.

Jan 1, 1997

By Sharon Thomson

Since 1977, Amax Coal Co.&apos;s Belle Ayr mine near Gillette, WY, has been the largest producing coal mine in the US. In its 10 years of operation more than 90 Mt (100 million st) of coal have been shipped from the mine&apos;s facilities to electric generating plants across the country. It is thought to be the largest amount ever produced in US history from a single coal mine. The railroad is Belle Ayr&apos;s lifeline for moving this massive volume from a relatively isolated corner of northeastern Wyoming. There are no waterways for barge traffic, and highway truck hauling would be impractical considering the quantity and distance of coal to be moved. Transportation in the Powder River Basin-at least for the present-is strictly unit trains. An average of four unit trains daily load at Belle Ayr. These trains average 108 cars long, with a capacity of 91 t (100 st) per car. Burlington Northern Railroad serves the Powder River Basin, but locomotives supplied by Union Pacific, Milwaukee Road, and Kansas City Southern are a common site as well, since coal will often travel these lines too on its way to utility plants in Colorado, Kansas, Iowa, Texas, Arkansas, Louisiana, Wisconsin, and Oregon. When Belle Ayr opened transportation in the Powder River Basin was in an early development stage. As the first large-scale coal shipper in the area, Belle Ayr was the only user of a 27-km (17-mile) railroad spur south of Gillette. Other mines, however, were to open soon on the abundant, low-sulfur reserves. Today, less than a decade after Belle Ayr&apos;s debut, 13 large-capacity mines operate near Gillette. The 27-km (17-mile) spur that once served only Belle Ayr has been extended 177 km (110 miles) south to service other mines as well, and to tie into a major rail line in central Wyoming. The Powder River Basin is now served by a wishbone-shaped track configuration that allows train movement north into Montana, south into Colorado, and east into Nebraska for connections across the country. Operations at Belle Ayr are closely tied to train arrivals and departures, with coordination essential between mine operations and rail personnel. "Train movement in the Powder River Basin has evolved to the point where we are fine-tuning mining operations to coordinate them with a more dependable transportation system," according to Joe Jefferson, transportation supervisor with Amax Coal&apos;s western division. That, however, hasn&apos;t always

Jan 10, 1982

By K. N. Santini

The evaporite deposit at Searles Lake consists of alternating brine-saturated saline beds and saline-bearing mud beds. Three major subsurface brine-saturated saline horizons have been identified by private companies and the U.S. Geological Survey. They have been termed, from bottom to top, the Mixed Layer, Lower Salt, and Upper Salt. The important water-soluble components (Na, K, Mg, CO3, HCO3 , SO4, Cl, and B407) are either in brines or have combined to form the following minerals: halite, hanksite, trona, nahcolite, burkeite, borax, thenardite, northupite, sulfohalite, glaserite, etc. Kerr-McGee Chemical Corp., the current operator at the lake, selectively pumps interstitial brines from each of the major horizons to feed its three chemical plants. As the pumping continues, brines are continuously replenished within the deposit by dissolution of the minerals through natural recharge or artificial fluid injection (solution mining). The brines are processed to produce a variety of chemical products, which include sodium carbonate and sulfate, potassium chloride and sulfate, sodium borate, and boric acid. The Anaconda Minerals Co. has been evalua¬ting potential domestic trona acquisition since 1981. We have evaluated various properties in the Green River, Wyoming trona district, and Owens Lake and Searles Lake in southern California. In 1983, we purchased with our joint-venture partner, Leslie Salt Co., the southern portion of Searles Lake from Occidental Petroleum Corp. Since mid-1983, Anaconda has been conduct¬ing a small exploration-drilling program at the property. The initial core holes were drilled along and adjacent to the existing access road. In 1984 we used an all-terrain drill rig to gain access to drill sites on the playa where no roads exist. The use of this equipment proved to be highly successful. The drill program consists of coring to an average depth of 450 feet and collecting brine samples from potentially commercial horizons. The brine samples are collected by setting a packer and swabbing the hole. The core is logged and split lengthwise; one-half is submitted to our Tucson Geoanalytical Laboratory for semi-quantitative mineralogy by X-ray diffraction and the following suite of chemical analyses: Na, K, Mg, C03, HCO3, SO4, Cl, B407, Li, H20 insolubles, and acid insolubles. Additional test work for selected core samples will include effective porosity and horizontal permeability determinations. The brine samples are subjected to the same suite of chemical analyses (minus insolubles) as the core samples. In addition, specific gravity is also determined. Both cross sections and isopach maps are being constructed. The hydrological characteristics of the potentially commercial horizons are also being investigated.

Jan 1, 1987

The Mine Safety and Health Administration (MSHA) academy in Beckley, WV, received enquiries from various segments of the mining industry concerning alcohol and substance abuse in the mining industry. The MSHA Director formed a committee, the Mining Industry Committee on Substance Abuse (MICSA), to deal with these enquiries. The committee met in April 1985 at the mining academy in Beckley. The MICSA committee expanded its membership to represent labor, management, and government agencies affiliated with the mining industry as well as government agencies dealing with alcohol and drug abuse. This expanded 18-member committee met for the first time in July 1985. At that time, two cochairmen were elected, one from labor and one from management. MICSA has spent time on education by sharing information on the issues and by calling in outside experts for advice and consultation. The committee also initiated several projects. These include a resource manual on substance abuse and employee assistance programs. Mine operators and labor unions can use these programs as guides. MICSA is also assembling statistics on substance abuse, particularly as applied to mining. And the committee commissioned an Education film, Substance Abuse, Is It Our Problem? (The results of a survey on drug use, given in Table 1, suggest that substance abuse may indeed be a problem.) The educational film, produced by MSHA, is an introduction to the problem of substance abuse in the mining environment. The film encourages mine operators, labor unions, and miners to analyze their individual circumstances to determine whether a problem exists. The film also offers ways to deal with the problem. And the film invites the mining industry to request additional information from MICSA. There is no single approach to substance abuse that will fit the need of every mining operation. As with any health, safety, or production problem, remedies must be site specific. MICSA&apos;s aim is to channel ideas to those who seek to help employees in a mining environment who seek to rid themselves of alcohol and substance abuse. As stated more formally: The Mining Industry Committee on Substance Abuse represents the efforts of labor, management, and government. The mission of the committee is to make the mining industry aware of the problems resulting from alcohol and other drug abuse and to recommend possible methods to remedy the problem. The function of the committee is to assist the industry in developing programs and resources to recognize and provide help for troubled employees, and thus reduce the risk of accidents, while lower absenteeism and increasing productivity.

Jan 11, 1987

By E. M. - Technical Papers Spokes

A.B. Rushton The work and resulting publications of the Committee on Underground Coal Mine Safety and The President&apos;s Commission on Coal were appropriate at the time of publication. The statistics cited in the publications appeared to be valid, and the actions proposed by the committee had merit. Although the actions proposed to achieve further improvements in safety may have been worthy of repeating, to associate statistics (Table 1) that are seven to eight years old with company names is bad. Statistics are readily available from the Mine Safety and Health Administration (MSHA) and are usually within three months of being up to date. A review of the most recent Coal Controlling Co. Report will reveal significant changes in the rankings. The more recent statistics should have been cited, or at least compared with those used in the article. Westmoreland Coal Co. is listed as having a 21.1 disabling injury rate for the period (1/78-12/80). The disabling injury rate for the Company for the year ending 1985 was 7.4 for the underground mines and 6.25 for the total facilities. Through March 1986, the dis- abling rate for the underground mines was 2.86. The management and employees of Westmoreland Coal Co. are committed to safety. The improvements achieved over the past five years attest to that commitment. We are justifiably proud of the achievement and dislike being misrepresented as in the April 1986 article Reply by E.M. Spokes I regret that the lapse of time since the original work gives a picture of safety practice that is no longer true today. That Westmoreland has reduced its disabling injury rate by 65% to 7.4 in 1985 is most commendable, and I congratulate you for this accomplishment. It is typical of the progress sought by the National Academy of Science and National Research Council when they funded the original study and published "Toward Safer Underground Coal Mines" in 1982. If a significant number of companies do as well as Westmoreland, the report will have served its purpose. Since the paper was primarily a condensation of the original report, it would not have been appropriate to seek access to later statistics. The purpose in seeking its publication at the time of presentation was to reach those who might have missed the original report. The fact that publication was delayed has not voided that purpose and may have reminded some who were aware of the original that its recommendations still apply to improvement of underground coal mine safety

Jan 1, 1987

INTRODUCTION The role of comminution and related unit operations in mineral processing applications is of major importance. This is especially true in terms of operating costs, since these unit operations represent the major fraction of the overall processing costs. Due to the broad scope and the large number of unit processes and machines involved, Section 3 is divided into five subsections. In Section 3A, General Aspects of Comminution, topics covered include history, terminology, particle¬size distributions, classes of comminution machines, testing and calcu¬lation procedures, and simulation and modeling. In Section 3B, Crush¬ing. the subjects include jaw crushers, gyratory crushers, cone crushers, hammermills, and impactors. The chapters of Section 3C, Grinding, cover aspects common to tumbling mills, ball mills, rod mills, autogenous mills, pebble mills, roller mills, fluid energy mills, other types of grinding machines, and grinding costs. Section 3D, Classification, coverage includes classification theory, hydrocyclones, and mechanical classifiers, and in Section 3E, Screening, the topics presented are classes of screens, selection of vibrating screens, sieve bend screens, and screening media. About five years after the Handbook was begun, Section 3 was unfortunately without an editor or contributors for over half of the chapters. A committee was then organized to expedite completion of the section. When this committee contacted the persons who had agreed to contribute to the section, it was found that many of them wished to resign from their earlier voluntary obligation to AIME. Therefore the committee had to find new contributors for these chap¬ters in addition to other chapters in Section 3. Since there had been no previous effort to locate contributors for Air Classification, Dust Collection, and Washing and Scrubbing, it was agreed to delete these subsections. In Section 3, equipment availability, capacity, and performance data from various manufacturers and users are provided for engineer¬ing use. Selected data from existing installations are also included. The machines that are being used in comminution, classification, and screening are described in detail, and drawings, photographs, and diagrams are presented to supplement the descriptive material. The editors thank and acknowledge the generous effort of the many contributors, some of whom were called upon five or more years after the Handbook was started. It is regretted that Fred C. Bond, who was a member of the committee formed to complete this section, was deceased before the section was finished. During the time that he worked with the committee, he contributed a great deal as an author and councilor.

Jan 1, 1985