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By Paul E. Epstein

Despite the controversies that have surrounded asbestos over the past 20 to 30 years, no knowledgeable authority has doubted the usefulness of this material. Were it not for the health risks associated with the manufacture and use of asbestos products, its physical and chemical characteristics would continue to be hailed as an undeniable boon to mankind. However, it has become clear over the past 30 years that like other major contributors to our modern industrialized society, asbestos must be handled responsibly and with the full understanding that lack of care can lead to injury, suffering and death. In this sense, asbestos shares characteristics with nuclear power, pesticides and even motor vehicle usage. It is unlikely that modern society would be willing to walk away from the benefits bestowed by any of these valuable resources. Rather, the appropriate response to the identification of danger is to define the type of risk, quantify its incidence, search for methods of decreasing the risk and implement programs to achieve the goal of minimization of risk. We should recognize at the outset that the risk cannot be diminished to zero without elimination of the material entirely from our midst. The concept of acceptable risk is a complex issue involving medical, legal, financial, moral and even psychological factors that defy precise quantification. In essence, the major danger produced by exposure to asbestos is its potential effects on the respiratory system. Despite the fact that asbestos workers have constant skin contact with the material and porbably swallow it in the course of their activities, inhalation of the fibers is recognized as the major health risk associated with its use. Aerosols of asbestos are inhaled not only by miners, millers and fabricators but also by urban dwellers who have no direct occupational contact with the material. This occurs because asbestos has been applied to our buildings and has been used in a wide variety of products that touch our daily lives. While it is estimated that three to four million people in the United States have been occupationally exposed to asbestos, the number who have been non-occupationally exposed is many times that number.

Jan 1, 1984

By Kim A. Lapakko, David A. Antonson, Jon R. Wagner

This study examined the potential of mixing rotary kiln fines (RK fines), a waste product generated when limestone is converted to lime (CaO), with acid producing mine waste to provide 1) short-term mitigation by neutralizing acid produced by iron sulfide oxidation and 2) long-term mitigation by facilitating the passivation of iron sulfide mineral surfaces. Five loadings of RK fines were mixed with 75 g of Duluth Complex rock to produce neutralization potential (NP) added: acid potential (AP) quotients of 0,0.11,0.22,0.66 and 1.1. The mixtures were subjected to wet-dry cycling laboratory testing for 585 weeks. The rock alone produced acidic drainage, with pH decreasing below 4 after about 20 weeks of reaction and ultimately reaching the approximate range of 3.3 to 3.5; sulfate release did not decrease over time. The RK fines elevated pH and inhibited sulfate release for time periods which increased with the mass of RK fines present. The pH of drainage from the 0.11 quotient (NP added1AP) loading decreased below 6.0 after 75 weeks of dissolution and decreased to 3.6 after 117 weeks, at which time the reactor was terminated. The duplicate 0.22 quotient loadings of RK fines decreased below 6.0 after 95 and 170 weeks. The former was terminated after 117 weeks, and the latter reached a minimum pH of 2.8 after 512 weeks. Drainage pH from the 0.66 quotient decreased below 6 after 581 weeks. For the drainages which acidified, the cumulative calcium release prior to pH decreasing below 6.0 was 92 to 103 percent of that initially present as calcium carbonateloxide in the RK fines. The pH of drainage from the 1.1 quotient typically remained above 8.0 throughout the period of record. Sulfate concentrations in the drainages decreased while the neutralizing fraction of the RK fines was present, but increased after this fraction was depleted.

Jan 1, 2000

By David L. Daniels

The U.S. Geological Survey has for many years been flying and compiling aeromagnetic surveys. The aim is complete coverage of the United States, about half of which is presently done. Colored aeromagnetic maps at a scale of 1:1,000,000 are published as the states are completed; Minnesota and Colorado have been published. Michigan, Iowa, Nevada, Utah, Maryland and Virginia are presently being processed. Some of the most spectacular data collected to date is from the Piedmont of the Eastern United States. I am going to discuss a preliminary aeromagnetic map of the Piedmont region between New York and North Carolina, where coverage is nearly complete. This map has been compiled from many surveys. Flight spacing over Piedmont rocks is 1/4 to 1 mile with flight elevation of 500 feet above ground. The spacing over the Virginia Coastal Plain and Valley and Ridge regions is wider at 2 - 3 miles. Much of the data in Virginia has been produced by the Virginia Division of Mineral Resources. The map is colored on a spectral color scheme with red for the higher intensities and violet the low intensities. Each color represents a 100 gamma interval. Some of the highest intensities are beyond the range of the 13 colors - these are left white. It is necessary, of course, to remove first, the Earth's main magnetic field. The Geological Survey uses the International Geomagnetic Reference Field or IGRF (Fabiano and Peddie, 1969). The use of color in aeromagnetic maps is not new, but then not common. We have found that colored aeromagnetic contour maps are more useful by far than the uncolored versions because they allow the user to instantly compare intensities in widely separated areas and visualize long wavelength anomalies even when numerous short wavelength anomalies' are superimposed. One tends to see only steep gradients on uncolored aeromagnetic maps, the broad anomalies being quite invisible. We feel that colored maps take the place of various mathematically derived maps such as second derivative or averaged maps.

Jan 1, 1973

By Jaime Lomelin

The brines from the sub-surface of the Laguna del Rey dry lake are pumped to Química del Rey, S. A. plant, where they are cooled in adiabatic crystallizers precipitating sodium sulphate decahydrate. This salt is dehydrated in multiple effect evaporators and dried in rotary kilns producing high purity anhydrous sodium sulphate. The spent brines from the sodium sulphate operation are concentrated in solar ponds, precipitating astrakanite and leaving a brine with a higher concentration of magnesium ions. This brine is treated with calcium chloride solution to eliminate the remainder of sulphates, leaving a solution of magnesium chloride ready for the manufacture of refractory grade magnesium oxide or periclase. The magnesium chloride is reacted with dolime to produce magnesium hidroxide which is washed, filtered, and calcined to produce soft burned magnesium oxide, which is briquetted and dead burned to produce the periclase.

Jan 1, 1984

By K. G. Black

When one's attention moves from the control of a process unit or from the control of a department of similar units, to the control of an entire plant, two things must change. One is the techniques of control, and the other, the goal or purpose of control. The goal is no longer maintaining a certain quality of product or maintaining a particular flow rate through a process unit. The goal becomes economic - how to make the most money out of the plant. The principal control techniques become those of optimizing, rather than regulating. It is quite common to discuss the control of an entire plant in terms of three levels of control l; regulation, supervision, and optimization. Regulation is the control of inputs to a process unit at desired values. This is accomplished by two or three mode analog controllers or DDC loops. The second level of control is the selection of these desired values, e.g., set-points of the regulation controllers. The third level is to make such adjustments or corrections to the supervisory calculations so as to optimize the plant profit. It is immediately evident that supervisory control and optimizing control are intimately related, and a distinct dividing line cannot always be drawn between the two. Some authors prefer to add even more levels such as adaptive control and management information systems, but we believe our point is well made without further division of the functions which are necessary for complete plant control. To accomplish the economic goal, that is, the optimizing (maximizing) of the profit of a mineral processing plant, the plant should ideally be operated as if it were a separate company, buying its raw materials on the open market and selling its products on the open market. While petrochemical plants endeavor to operate in that manner, unfortunately this is not true of a mineral processing plant. The plant manager has to accept the amount and quality of ore the mining department delivers to him, and the products (concentrates) are delivered to another department of the company for further refining. In some cases he may sell

Jan 1, 1972

By Rolland L. Blake

The Bureau of Mines is investigating the potential for in situ leach mining "(ISM) of gold and silver mineralization. This preliminary study examined samples from several types of deposits using light optical microscopy and the electron microprobe to characterize the ore and gangue minerals and their microscopic characteristics, including the spacial relations between the target minerals and likely natural fluid channelways. Low grade disseminated deposit types from the western U.S. were found to contain fracture-hosted or matrix-hosted gold and silver minerals, some of which are encapsulated by quartz or pyrite. Geologic features readily observed microscopically include ore and gangue mineral identity, size, and their association with each other and with fractures. Successful ISM application to gold and silver deposits needs this data to: (1) select the proper lixiviant based on chemical reactivity of the host rock, ore, and gangue minerals, (2) determine potential permeability characteristics when designing lixiviant flow patterns, and (3) understand potential problems of the lixiviant reaching encapsulated ore minerals. Careful examination of the geologic characteristics of each ore body is required because of the observed diversity of characteristics in deposits from the same "class" and even within the deposit itself.

Jan 1, 1989

By Song Jiang, Xianzhi Tan, Minjie Lian

"The ground water heat pump system lades underground hot water which can be heated or cooled by heat exchanger in water source heat pump air conditioner. This system replaces the model of heating of air-conditioning by refrigerator and boiler. In this paper, the formation conditions of hot water energy in Shan Dong are analyzed in order to achieve the purpose of energy conservation and emissions reduction by taking full advantage of water resources such as water pouring and return water of beatification during the productive process of underground metal mine. In order to analyze the issue better, the paper points out some ways and methods for geothermal water often used in underground metal mine. This paper also presents the advantages of the technology of water source heat pump that is applied into underground metal mine. Here is a case study of comprehensive utilization of water source in a certain underground metal mine in Ji Ning. This mine, according to its own actual situation, designs heat pump heat exchange system which is used for indoor heating of buildings and bath for staff. It turns out that the system can save 23% water per year, cut down 3.303 million KW electric energy, and reduce 4160t emission of carbon dioxide. It is concluded that the technology of water source heat pump has broad application prospects in underground metal mine. Therefore, the results show that it is an ideal way to change the present structure of cooling and heating source in metal mine.Introduction In recent years, overuse of fossil fuels has posed a grave threat onto the environment, which makes renewable energy a more important status in energy structure. Development and utilization of renewable energy has become an important direction. Water source heat pump technology is to use solar energy stored in water as cold/heat source to convert energy. Currently, this technology has been widely used in some advanced countries. However, due to facers of implementation technology and component costs, there is still a gap in water source heat pump technology between China and these advanced countries. According to (Blum et al 2011) that after in-depth study, water source heat pump technology has developed rapidly in China recently, and the gap is gradually reduced. Groundwater source heat pump system as a kind of high efficiency, energy-saving and environmentally friendly technology in recent years, more and more get the people's attention. At the same time, its practical application has also been rapid development. Based on (Ni et al 2015) that According to the relevant departments of the prediction, the technology will become the 21st century the most efficient heating and cooling technology."

Jan 1, 2017

By David M. Parkes

The hydraulic movement of coal is here defined as the movement of all sizes of coal in pipes and open flumes, by gravity and against gravity. It is not restricted to coal which is in slurry form. In other words, it is not crushed to a size in the 8 to 20 mesh size range. The top size could be as high as 12 inches. The dewatering of coal which is transported hydraulically is carried out to restore the coal to a suitable form for further cleaning, or for transportation by other methods. The process involves complete separation of all the coal, wood and rock from the water so that the water can be recycled without undue damage to pumps, pipes and monitors.

Jan 1, 1976

By J. L. Carr, A. K. Smith, C. C. Jobes, G. T. Homce

"Underground continuous mining machines pose a difficult safety challenge since their operators generally work in close proximity to these machines in very restricted spaces. Intelligent software for use with magnetic proximity detection systems has been shown to accurately locate workers around mining machinery in real time. Calibrating these systems requires the manipulation of a lot of data to determine the calibration constants. Researchers have developed software to analyze, convert, and visualize data acquired during this calibration process to more accurately model magnetic fields and their interaction with the environment. This paper details the background, development, and operation of the resulting application software focusing on the utility of the graphical user interface to visualize the magnetic field calibration data. The refined data developed by this process can then be utilized by the proximity detection system to more accurately identify the location of miners working in an underground mining environment. INTRODUCTION Roughly half of the electricity consumed in the United States is produced with coal, and roughly one-third of all US coal production comes from underground mines [1]. Over the last century underground mining health and safety has seen a continuous and dramatic improvement. However, machine-related injuries and fatalities continue to be a major safety concern [2]. Every year, hundreds of miners are severely injured while operating underground mining equipment, and 39 miners have been killed in striking/pinning accidents involving continuous mining machines (CMMs) since 1984. CMMs, such as the one shown in Figure 1, are large mobile machines that are used to mechanically cut coal in an underground mine. These machines weigh approximately 40 to 50 tons, have hydraulically articulated appendages, and are capable of moving at speeds up to six feet per second [3]. Modern CMMs are remote-controlled, yet the operator and other miners are often in close proximity to the machine. Recent research by the National Institute for Occupational Safety and Health (NIOSH) reveals that the locations workers take relative to the CMM are usually influenced by visibility requirements and safety concerns [4]. The Mine Safety and Health Administration (MSHA) estimates that at least 28 fatalities involving CMMs since October of 1984 may have been prevented with proximity detection technology [5]. MSHA further estimates that proximity detection could prevent 20% of all deaths throughout the industry [6]."

Jan 1, 2016

By J. P. Ducarme, J. L. Carr, C. C. Jobes

"An average of 1.2 fatalities occur per year in underground coal mines in the United States when a miner is struck or pinned by a remote-controlled continuous mining machine. Proximity detection technology provides a means to prevent these types of accidents by disabling all machine motion when a miner is in close proximity. Researchers at the National Institute for Occupational Safety and Health (NIOSH) have developed the intelligent Proximity Detection (iPD) system, which continuously tracks the position of miners near the machine and disables only those machine motions that could cause a pinning accident. This system, previously demonstrated using non-permissible proximity detection hardware, has now been shown to be effective when implemented using an MSHA-approved system as a platform. Performance tests have shown accuracy, repeatability, and stop zone identification to be comparable to or better than the system demonstrated with non-permissible hardware. INTRODUCTION Underground coal mining room-and-pillar operations typically use Continuous Mining Machines (CMMs), such as the one shown in Figure 1. When CMMs first became available, they were operated from an on-board operator’s compartment that protected operators from roof falls and other hazards but severely restricted visibility and subjected them to machine vibration and high levels of dust and noise. To solve these problems, remote controls were developed to operate CMMs. Now CMM operators are free to position themselves for best visibility of each mining task and are no longer subjected to the rough motion of the CMM during mining operations or the dust and noise generated by the machine. However, this technological advance removed operators from the protection afforded by the operator’s compartment and exposed them to the hazard of being struck or pinned by the CMM or other large moving machines."

Jan 1, 2015

By Robert L. Grayson

In small coal mining operations, little is done in controlling supply and material inventories and optimizing total inventory costs. Material Requirements Planning (MRP) is an efficient material control system which time-phases net material requirements based upon production plans, bills of material data, and inventory status records. Inventory levels and total inventory costs are optimized using a lot sizing technique in placing time-phased purchase orders. The MRP system has been applied in large manufacturing firms utilizing mainframe computers, but it can be adapted to micro-computers for inventory control. This paper presents an application designed to assist the coal mine manager in optimizing inventory costs.

Jan 1, 1985

By David J. Dunn

Mill liner design is an important factor in grinding. Testing and selection of the optimum liner profile for a given set of mill operating conditions can improve mill capacity, liner life, and liner wear rate At a time when mill avilability is at a premium, production costs are going up, and lead time for mill liner castings is a year or more, the mill liner that grinds best, lasts longest, and costs least is a necessity for economic mill operation. In testing four mill liner profiles for 13' x 12' overflow ball mills, Climax found that an improved design increased mill tonnage by 3 tons per hour while reducing finish grind by 1.7% + 100 mesh, reduced liner wear rate, and almost doubled liner life.

Jan 1, 1976

By P. L. Stavenger

Principles of Operation and Mechanical Features General Mechanical Description Sieve-bend screens are high-capacity screening devices which utilize stationary, concave, wedge-bar screening surfaces. A complete sieve bend is comprised of a feed distribution chamber, a structure for holding the screen surface, and collection chambers or chutes for oversize and undersize materials. In devices used for metallurgical practice, provision is usually made for reversal of the direction of flow over the surface, either by rotating the surface or by changing the feed nozzle position. The size of the unit varies in height from 5 to 8 ft, and in width from 2 to 8 ft. The orientation of the wedge-bar surface is such that the slots between the wedge bars are perpendicular to the flow of feed material over the surface. The feed distribution means is arranged such that the flow of liquid suspension is distributed evenly and tangentially over the width of the screen surface. A variety of means are used including simple gravity weir feeds, long slotted nozzles, and a multiplicity of round nozzles. A typical gravity-fed weir type nozzle is shown in Fig. 18. Most sieve bends are fed with gravity feed in such

Jan 1, 1985

By M. U. Khan, A. D. S. Gillies

"Diesel exhaust is a major cause of large number of occupational diseases. Acute and continuous exposure to Diesel Particulate Matter (DPM) can cause numerous health issues including respiratory disease, reduced lung capacity, heart disease etc. The National Institute of Occupational Safety and Health (NIOSH) and the International Agency for Research on Cancer (IARC) consider diesel engine exhaust as carcinogenic. In large underground metal and nonmetal mining operations, regulatory compliance regarding miner’s exposure to airborne particles especially DPM is a big challenge. Complex mine networks add more difficulties in controlling DPM. MSHA relies on the NIOSH 5040 method for DPM compliance. The NIOSH 5040 method is a shift average based method which inherits some limitations. Due to these inherent limitations of the NIOSH 5040 method the concept of real-time DPM monitoring is promoted in the mining industry. Several real-time DPM monitors have been used by the researchers and efforts still continues to improve their measuring techniques and understanding. Real-time monitoring of DPM is vital to gain understanding of rapid changes in the mine atmosphere. The current study highlights the advancement in real-time DPM monitoring and mainly covers a review of several studies in which DPM concentrations were measured by utilizing real-time DPM monitors. INTRODUCTION Ventilation of underground mines is an important aspect of mining operations. Mining is a continuous activity and the ventilation networks in modern mines change with extended developments. Proper understanding of the ventilation network is a key design factor of an optimum mine ventilation plan. An important task of underground mine ventilation engineers is to provide clean air with sufficient quantity to the underground miners (Khan M. U. and Gillies A.D.S. 2015). The amount of fresh air supplied to the mine should be adequate to dilute the concentrations of contaminants present in the mine atmosphere. In the United States it is estimated that diesel powered equipment is used in thousands of mining operations (Stephenson D. J. et al. 2006). Use of diesel powered equipment is an attractive option in underground mines due to its several advantages over other available alternates. Diesel engines are rugged, dependable and fuel efficient (McKinnon 1999). It is common for diesel engines in heavy duty trucks to have a life of 1.6 million kilometers (McKinnon 1999). Looking at the developments in other energy alternatives, it can be assumed that the underground mining industry will maintain its reliance on diesel powered equipment (Anon 2001). DPM is an important source of mine air contamination in many non-gassy underground mines (Khan M. U. and Gillies A.D.S. 2015). Diesel exhaust is harmful for humans. Acute and continuous exposure to diesel exhaust concentrations can cause several health issues. Some of the health diseases caused by DPM exposure are respiratory diseases, reduced lung capacity, heart disease, and lung cancer (National Research Council. 1981, Mine Safety. 2005). In addition, NIOSH regards diesel exhaust as “potential carcinogen” (Centers for Disease Control 1988) and IARC has declared that “diesel engine exhaust is carcinogenic to humans” (IARC 2012). NIOSH has also declared that the reductions in DPM exposure would reduce cancer risks (Centers for Disease Control 1988)."

Jan 1, 2016

By Thomas J. Regan

The first stage of the Massachusetts Bay Transportation Authority's Red Line Extension Northwest, is a two-track rapid transit extension from Harvard Square in Cambridge, through three stations, to the Alewife Station/Garage complex in North Cambridge. The extension, about 5.0 km. (3.1 miles) in length, is entirely in tunnel, with the Alewife Station/Garage complex and adjacent line sections of tunnel constructed by cut-and-cover methods. The Station/Garage complex, just west of Alewife Brook Parkway, is in an area underlain by deep deposits of very soft highly sensitive clays. It is proposed to construct the station and adjacent tunnel sections by the slurry trench method, using the slurry wall as the permanent structural wall of the station and tunnel. The unusual nature of the underlying clay and its very high sensitivity raised questions concerning the feasibility of the proposed construction. Since research failed to reveal any construction precedent for the specific conditions encountered, a test section was undertaken to determine construction problems, resolve uncertainties, and to establish acceptable parameters for the construction of the slurry walls. PROJECT ORGANIZATION Sverdrup & Parcel as tunnel and transit systems consultant for the Red Line Extension-Davis Square to Alewife had overall responsibility for determining program objectives, project management and test implementation.

Jan 1, 1979

By Betty L. Gibbs

What does the information age mean to mining companies? The perception of greatly increased access to information is based on modern communications through ‘smart’ fax machines and computer networks. Computer media allow us to `talk' to the President or to a sister in Australia. If we need data to help put together a mining permit, we can find that data somewhere on computer media. The vast amount of easily accessible information quickly overwhelms us. To avoid `information burnout,' we must learn to target searches and be able to discriminate between dross and information that is useful to our goals. If you watch commercial TV, you have learned to screen out most product commercials. A similar screening process must be applied to computerized information sources. You may need to sort through a lot of irrelevant information before finding the pearls you are looking for. ‘Smart’ fax machines can send information with no direct human intervention. MINES FaxBac, for example, from the US Bureau of Mines instructs you to enter four-digit numbers to have particular reports sent directly to your fax machine. Software vendors use a similar system to supply information about their products. You select an item by number, and the related brochure is faxed to your machine. To compete, the industry must maintain access to as many information sources as possible. The availability of computers and software for almost every conceivable application allows us to accomplish work faster than we ever thought possible, even as recently as 10 years ago. Most mining companies have become aware that doing geology, reserves, mine planning and other technical tasks completely by hand is much too slow. The world moves faster, drilling happens faster, mining happens faster, all related activities happen faster. We no longer have the manpower or time to keep all maps. calculations and records up to date.

Jan 1, 1994

By R. A. Young

Effective October 1, 1958, President Eisenhower imposed, by Presidential Order, fixed import quotas on lead metal and lead concentrates and also on zinc metal and zinc concentrates. He did this in response to an escape clause case under the Trade Agreements Act filed by many of the large and small lead and zinc mining companies in September 1957. It is the purpose of this paper to give the experience of the lead-zinc industry under this order during its first two years and some observations on what might have come about under different conditions of U.S.A. consumption. Before considering these various experiences and observations, it seems wise to first outline briefly the basic problem which prompted such an order. Under the Tariff Act of 1930, the duty on pig lead was fixed at 2-l/8¢ per pound and slab zinc at 1-3/4e; per pound. The ores, concentrates and closely related products of these metals carried closely related duty rates. The Trade Agreements Act of 1934 and succeeding similar acts had given the, President the power to lower these and other duties. As a result-of various negotiations with foreign nations, by 1951 these duties had been lowered to their present day rates of 1-1/16 per pound on' pig lead and 7/10o, per pound on slab zinc. Related ores, concentrates and semi-fabricated forms of the metals received commensurate treatment. Under these acts, the Tariff Commission has the right to recommend to the President duty increases, specific quotas or both if find that imports have injured the affected industry. He has the right to accept or reject such recommendations, in whole or in part, in the light of the national interest,

Jan 1, 1961

By E. W. Hawk

The power generation industry may be required to reduce CO, emissions if regulations related to global climate change are enacted. Coal-fired generation, which emits 82% of the power sector CO2, would be a likely target for CO2 reduction. Compliance with the Kyoto protocol will require a 30% reduction from the projected year 2012 emission level even with moderate load growth. This paper describes an analysis of power industry CO2 reduction options and their costs to assess how a generator would make compliance decisions under a mandatory CO2 emissions reduction program. Carbon sequestration, fuel switching and new plant construction are considered.

Jan 1, 1999

By J. R. Gump

The term "rare earths" is used to designate a group of elements, Numbers 57-71 which are closely related chemically. They were called "earths" because their oxides resemble those of the alkaline earths, and the designation "rare" was originally applied because of their scarcity. Now many of these elements are known to exist in considerable quantities, and the term "Lanthanide" is applied to this group of elements, because of their similarities to lanthanum, the first element in the group. Many authorities insist on including yttrium, element Number 39, because of its extremely close association with the members of the group in nature and because of its similarity in chemical properties. It has been estimated that the combined rare earth group makes up about five-thousandth. of one percent of the Earth's crust, a higher percent than the common elements, lead, tin, zinc, arsenic, mercury, silver and gold. Cerium is by far the most abundant member comprising about half of the total amount. Yttrium, neodymium, and lanthanum are next in order; samarium, gadolinium, praseodymium, dysprosium, erbium, holmium, and ytterbium are increasingly scarce; while the elements lutetium, thulium, terbium, and europium are extremely rare. The rare earths as a group are metals, usually trivalent, forming basic oxides, and insoluble oxalates in dilute mineral acids. Their fluorides are also difficultly soluble; hence the rare earths or lanthanides may be separated, in general, from other elements by adding oxalic or hydrofluoric acid to a dilute mineral acid solution containing them. The most striking fact which characterizes these elements is the remarkable .similarity in both the physical and chemical properties of their compounds. Their main differences are in the solubilities of their salts and the basicity of their oxides, which vary between that of the alkaline earths and that of aluminum.

Jan 1, 1960

By D. J. A. Chambers, J. M. Wempen, K. D. Koper, M. K. McCarter, K. L. Pankow

"The EarthScope Transportable Array (TA) of broadband seismometers (www.usarray.org) was deployed across southwest Wyoming from November 2007 through May 2009. During this time period the Array Network Facility (ANF, anf.ucsd.edu) detected and located a total of six seismic events near the trona-mining district. This lack of seismicity is atypical compared to coal mines employing similar mining methods. In this study, eighteen months of continuous seismic data from several nearby TA stations are reexamined using conventional and correlation-based methods to detect seismic events. Waveform cluster analysis and epicentral locations are used to discriminate between mining induced seismicity (MIS) and seismic energy generated from surface blasts at nearby coal mines. The locations and magnitudes of the 143 newly detected MIS events are compared to regional subsidence as measured by Differential Interferometric Synthetic Aperture Radar (DInSAR). INTRODUCTION An abundance of natural resources and a favorable political climate have made southwest Wyoming home to multiple large mining operations. Among these operations are five underground trona mines located approximately 50 km west of Rock Springs, Wyoming. The trona mines employ room and pillar, longwall, and solution mining methods over an area roughly 900 km2, and produce a sizable portion of the world’s soda ash (Brown 1995). Historically, in the Rock Springs mining district, several relatively large magnitude seismic events have occurred. These events are thought to have been related to mining activity and have caused notable subsidence (Case 1997). The largest event in the region recorded by seismometers, ML 5.1, has been confirmed as the 1995 Solvay Trona Mine collapse (Pechmann et al. 1995). In addition, blasting at surface coal mines near Rock Springs produces significant amounts of seismicity; approximately 50% of all daytime seismic events in the Mountain time zone from 2007 to 2009 locate near an active surface mine in this region (Astiz et al. 2014). Much of the current research related to surface subsidence and induced seismicity focuses on wastewater impoundment (Ellsworth 2013) and hydraulic fracturing. The observable seismicity in geological injection environments is widely variable and McGarr (2014) has argued that, in such environments, the maximum amount of seismic energy that can be released is proportional to the injected volumes. Like injection environments, in extraction (mining) environments seismicity is highly variable depending on many geological and operational variables (Boltz et al. 2012; Carnec and Delacourt 2000; Fritschen 2010; Iannacchione et al. 2005; Sen 2013) and does not always correlate well spatially with subsidence, a surface expression of extraction at depth."

Jan 1, 2015