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By Nancy J. Wheatley

I. INTRODUCTION The Massachusetts Water Resources Authority (MWRA) is a regional water and sewerage authority which provides wholesale water and sewer services to the Metropolitan Boston area. The MWRA was created by the Massachusetts Legislature as an independent authority in 1985 following the filing of a lawsuit in federal court to correct the pollution of Boston Harbor resulting from inadequate and inadequately maintained sewerage facilities. Immediately upon its creation, the MWRA began to tackle treatment plant issues, including addressing the need for a secondary treatment plant, planning for ceasing ocean discharging of sludge, and making interim repairs to the existing, antiquated treatment plants. The MWRA's initial activities led to a court-ordered schedule for construction of a single new primary and secondary treatment facility, for development of sludge management plan focussed principally on reuse, and for completion of a short term program of repairs to existing facilities. Once a schedule for completing these activities had been negotiated, the U.S. Environmental Protection Agency (EPA), a plaintiff in the federal court case, asked that the MWRA take "responsibility" for controlling discharges from combined sewer overflows (CSOs) within its service area. Combined sewers (sewers in which both sanitary sewage and storm water runoff are carried in a single pipe) presently discharge over 10 billion gallons of untreated wastewater into Boston Harbor and its [ ]

Jan 1, 1991

By William Petruk

Lithium bearing lepidolites from three deposits in the province of Goias in Brazil were investigated to determine whether there is a correlation between the lithium content of the mineral and the colour of lepidolite and associated tourmaline. Such a correlation can be a useful guide to field geologists for outlining high grade ore zones. It was found that mauve-pink lepidolite associated with pink tourmaline, and brownish lepidolite associated with black tourmaline have high lithium contents, but the colour of lepidolite is not due to lithium. The pink colour of lepidolite and tourmaline is likely to Mn3+, and the brownish tint of lepidolite and black colour of tourmaline to Fe3+. Lepido lites appear to be lithium-rich when the lepidolite and associated tourmaline contain relatively high amounts of Mn3+ and/or-Fe3+.

Jan 1, 1985

By Richard Minnitt, Philippe Renard, Christina Dohm, Winfred Assibey-Bonsu, Matthew Aboagye, Julien Straubhaar, Mahlomola I. Mabala

The application of multiple point statistics (MPS) in oil studies has gained traction over the years; however, the use of MPS in mineral resource estimation and classification is still limited. This is despite MPS’ ability to deal with complex and heterogeneous geology better than the commonly applied two-point based methods. The availability and choice of a representative training image (TI) are often cited as the main challenge holding back MPS’ application in mining geostatistical studies. On the other hand, the general approach used in mining whereby early focus is on higher grade areas and lower grades are planned to be mined later presents a massive opportunity for the development of representative TIs. Mined-out areas provide large amounts of historical data that can be used to develop training images or training datasets that can be used to estimate in mining extension areas (often lower in grade), provided low grade areas are underpinned by similar geology analogue. This approach will enable more robust estimates in mine/pit extension areas for both high- and low-grade extensions than with traditional two-point geostatistical methods.

Jun 25, 2023

By K. V. Raj, A. T. Weakley, A. L. Miller, D. A. Parks

Diesel particulate matter (DPM) is a common and well-known health hazard in the mining environment. The current approved method for monitoring both the organic and elemental carbon (OC, EC) portions of DPM is a laboratory method with a turnaround time of approximately one week. In order to evaluate exposure levels and take corrective action before overexposures occur, a portable real-time device capable of quantifying both OC and EC is needed. To that end, researchers from the National Institute for Occupational Safety and Health (NIOSH) designed and tested a device based on narrow bandpass optical filters that is capable of targeting infrared absorbance bands associated with DPM. Five optical bandpass filters were chosen based on previous work quantifying DPM using Fourier-transform infrared (FT-IR) spectrometry. The resulting device, referred to as a filtometer, is optimized to exclusively determine DPM and could serve as a cost-effective, field-portable alternative to laboratory-grade FT-IR analysis and instrumentation. The performance of the filtometer was investigated by calibrating FT-IR data from DPM (dependent variable) to the filtometer spectra (predictor variables) using a partial leastsquares (PLS) and ordinary least squares (OLS) approach. The square of the correlation coefficient and root-mean-square error of cross validation m

Mar 2, 2022

By Jorgen Elbrond

Before and in the early stages of industrialization, mining was the undisputed leader in technology. It represented the high-tech of the time. Early mechanization bears witness to that. Hoisting and rock breaking driven by waterpower are such examples. The mines' use of the steam engine was a major incentive to its development. By these means new mines could be opened and more metal supplied. Understanding of systems was essential for miners when shaping the infrastructure of the mines for the transportation of ore, material and men and for the evacuation of water and for ventilation. The irrigation systems of ancient mines are such examples. However, with the industrial revolution other more specialized branches of industry advanced further, and the mines became users of other industrial branches technologies. The mining industry had, however, always been quick to recognize a good thing and use it, when time was right. But, compared with other branches of industry, the mining industry has the disadvantage of working in a rugged environment with (and actually inside) a raw material which is abrasive and highly variable with respect to mechanical properties. This determines the rather high unpredictability of mining machines' performances and their low availabilities and explains a part of the delays in introducing technological advances.

Jan 1, 1989

By John E. Litz

Since the 1974 introduction of catalytic converters to automobiles in the United States, more than 150,000 kg (5,000,000 oz) of platinum, palladium, and rhodium have been used in the converters. An estimated 8 to 10 million converters are being used annually in the United States, each containing from $5 to $15 of PGM metals. In addition, use of converters is beginning in Europe which will significantly increase the quantity of PGM used. Two basic types of catalysts for converters are being used: pellet and monolithic. The pellets are small, discrete spheres or cylinders of gamma-alumina coated with platinum group metals, Figure 1. The monolithic are honeycombs of a cordierite, A13(Mg,Fe)2Si5AlO18, base coated with gamma-alumina and subsequently with platinum group metals, Figure 2. Pellet catalysts are being used by General Motors and American Motors; whereas Ford and Chrysler are using monolithic catalysts. The table below compares the PGM content and value of the catalysts.

Jan 1, 1986

By Ralph W. Barbaro

In many parts of the country, electric utilities use spot market coal to make up the difference between the amount of contract coal and the total amount burned. The utilities involved will normally have a structured contract for those companies supplying that spot coal. These contracts will often involve a pricing schedule with bonuses or penalties for coal above or below the specified coal quality goals. Normally, penalties will be assessed on the sulfur, ash, and other coal quality variables. This paper deals with some aspects of the pricing schedule of one of the eastern utilities that buys coal on the spot market. This utility has a number of plants that a supplier can attempt to supply through bidding procedures. The existence of the pricing schedule gives the supplier a number of different options. To the single-mine producer, options are available to send the coal to any demand site and to clean all, part, or none of the coal. In other words, he can ship to a number of different sites and can send different coal qualities to each site depending upon the level of preparation. In addition, the options to deliver blended coal to any given site will provide an additional level of complexity to the problem.

Jan 1, 1983

By John F. Parmeter

On August 29, 1989, the Department of Labor, Mine Safety and Health Administration (MSHA), published a Federal Register concerning a new proposed rule on air quality, chemical substances and respiratory protection standards. As of this writing, their proposed rule has not become a standard. However, with little revision it could be expected to become a standard, and we in the mining industry will be expected to adhere to and enforce it.

Jan 1, 1991

By Pinar Eksert, Hakan Akcin

Investigations show that injuries and fatalities in mining workplaces in developing countries are increasing. In Turkey, the number of workers killed in occupational accidents in the Zonguldak Hard Coal production region per 100,000 tons of coal production is 2.83 in the private sector and 2.03 in the public sector. For this reason, it is important to conduct risk analyses in terms of occupational health and safety and to implement measures quickly. Risks are evaluated with reactive and proactive approaches. Because hazards and events are often unpredictable in high-risk areas such as coal mining, it is not practical or meaningful to plan proactively in advance for every possible situation underground, especially psychosocial risks. However, it is important to develop protective strategies and measures for unexpected events or to take a reactive approach to prevent future incidents or accidents and to identify psychosocial risks. Therefore, reactive risk assessments based on the tactics and strategies of criminology can be conducted and spatiotemporal geographic information system (GIS) techniques can be utilized, enabling managers in mining workplaces to correct assessments.

Oct 1, 2024

By Eric R. Braun

Ore reserves in the Republic mining district were nearly exhausted in 1984 when hole D-54 intersected a vein twenty- eight feet in drill width averaging 1.57 opt gold and 11.95 opt silver below post-mineral lake beds. The discovery area, termed "Golden Promise", has announced proven and probable ore reserves of approximately 372,000 tons averaging 1.0 opt gold and 4.5 opt silver, and drilling indicates another 756,000 tons of mineralized material containing 0.37 opt gold and 1.4 opt silver (Hecla fourth quarter 1986 report). This paper describes new geological interpretations made as part of a district research study sponsored by Hecla Mining Co., which led to the D-54 discovery. Important new geological concepts include: 1) re-interpretation of the volcanic stratigraphy of the district and recognition of a suite of pyroclastic rocks that are unique to the Republic graben, 2) identification of disseminated subaerial mineralization at a paleosurface that corresponds to the newly described upper contact of the Sanpoil Volcanics, 3) recognition that epithermal veins have a maximum productive vertical range of 0-500 meters, measured from the paleosurface, and 4) veins exhibit visual and geochemical vertical zoning within the productive zone with highest gold occurring at an optimal depth, which is interpreted as the average depth of hydrothermal boiling.

Jan 1, 1987

By L. Alan Weakly

The purpose of this paper is to present a viable method of reinforcing rock pillars by utilizing fully grouted reinforcing steel and a cement - fly ash mortar. Although the fully bonded bolt concept is not new, as exemplified by the present widespread use of resin bolts within United States mines and by the use of cement grouted reinforcing used as back pins in the Kiruna Iron Ore Mine in northern Sweden, (1) (2) the method of stabilizing mine pillars with fully bonded reinforcing is new. This method, called the "grout-rebar system", was first incorporated at St. Joe Minerals Corporation’s Fletcher Mine in December of 1972. The system was used on an emergency basis before extensive research on the mechanics of the system could be completed. Since December of 1972, however, approximately 206 pillars have been reinforced at Fletcher and the system is currently being used on a regular basis at two other St. Joe mines and at two competitor mines in the area. Basically, this paper is a case study of the efforts, research and results of utilizing the grout-rebar system, on a selective basis, at the Fletcher Mine. In addition to information about the system, this paper will explain in detail the three rock mechanics instruments developed by St. Joe and used to measure and monitor rock movement to validate the grout- rebar system.

Jan 1, 1977

By W. C. Yates

Lack of visibility from cabs of the large haulage trucks used in open-pit mines has become a serious safety problem. This Anaconda research program was conducted to develop a low-cost system for alerting haulage truck operators of the presence of small vehicles in their blind areas. Several systems, developed and tested to help solve this problem, are summarized and evaluated in this paper. As the size of the haulage trucks used in large open-pit mines has increased, so have the blind areas. Mine utility vehicles, pickup tucks and cars become concealed within these blind areas and, thus, become a serious safety hazard. Figure 1 shows the typical blind areas of a 150-ton haulage truck. The areas of greatest concern are those at the rear center and front right corner of the truck. It is within these areas of "no visibility" that numerous small vehicles over the years have been crushed by the large haulage trucks at various mine sites. Although the occupants in most instances, have escaped the vehicle before it was destroyed, injuries and deaths have occurred. The accidents, in most cases, were attributed to negligence or carelessness on the part of the driver of the smaller vehicle, but the problem of limited visibility still exists, and a solution is needed.

Jan 1, 1982

By Prakash M. . P. E. Donde

1. INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has often taken a leading role in introducing innovative construction technologies to build its transit system. Most recently, Contract Section E-5a, which included Fort Totten Station and Tunnels was constructed utilizing the New Austrian Tunneling Method (NATM) in soft ground. Along with the station and tunnels, two permanent shafts were also constructed in soft ground employing the NATM technique. This project is located within the District of Columbia on the Greenbelt Route. The subject of this paper is to discuss the unique method of construction of these two shafts, and explore the benefits of applying the NATM technique to the construction of deep shafts. The design of the shafts was performed jointly by Jenny Engineering Corporation of Springfield, New Jersey, and Mayreder Consult of Linz, Austria. The designers also provided construction support services and a resident NATM expert at the site during construction. The construction of the project started in April 1988 by a joint venture of Mergentime Corporation and H. T. Construction, a subsidiary of Hochtief Company from Germany. This $48.7 million construction project has been completed. 2. SUBSURFACE CONDITIONS The two NATM shafts are located primarily in Cretaceous-age deposits that are over 100 million years old. These deposits are intermixed and lenticular in nature

Jan 1, 1993

By C. E. McFarland, N. W. Kirshenbaum

Cortez Gold Mines is located about 75 miles southwest of Elko, NV. Activity in the mining district dates from 1862. The current operation developed from a 1963 joint venture of Webb Resources, The Bunker Hill Company, Vernon F. Taylor, Jr., and American Exploration & Mining Co. Three years later, the USGS discovered gold on the property following a regional geochemical survey. Drilling in 1966 and 1967 identified 3.4 million st of oxide ore grading 0.28 oz Au/st, and a 1700 st/day countercurrent decantation mill was commissioned in 1969. Heap leaching started in 1971 on low grade ore and continues to the present. The mill was shut down in 1976 following exhaustion of known oxide reserves. Mobile equipment was sold and the proceeds committed to local exploration. In 1980, a new plan of operations was developed starting with existing low grade and newly discovered mill ore. The mill resumed operations in 1981 and has been operating to date. A series of metallurgical innovations, culminating in the commissioning of a new fluid bed roaster in the summer of 1990, has enabled treatment of a series of increasingly refractory ores. Current partners in the venture are Kennecott Corporation, Vernon F. Taylor, Jr., and Placer Dome U.S. Inc., manager of the operation. Idaho Mining Corp. holds a 7.5% carried interest.

Jan 1, 1992

By Ted T. Biddle

The world energy crisis has created a greatly expanded exploration program for energy fuels. The demand for materials required for drilling operations such as barite, which is the primary component of drilling fluids, has increased proportionally. As in the case of many other minerals, existing high grade barite mines are no longer capable of producing the required tonnage. Consequently, exploration and development of lower grade ore bodies has been increased. The need to produce a high quality product at maximum recovery rates, along with the ever changing economics affecting both selling price and production costs has triggered accelerated research programs toward more sophisticated and efficient beneficiation methods. Taking into account the specific gravity differential between barite (4.5) and the normal gangue minerals such as silica and calcite (2.7), gravity concentration methods are the prime consideration with flotation as a scavenging process. Greater emphasis on particle size liberation, size reduction and concentration is also indicated. In order to accomplish these objectives, it has been necessary to revert back to the old adage, "Recover your minerals as soon as they are free."

Jan 1, 1980

By L. G. Stolarczyk

In-mine Continuous Wave (CH) Radio Imaging method (RIM) instrumentation has the capability of measuring EM wave propagation constants in layered formations. The RIM method is based upon the fact that seams of coal, trona, potash, quartzite, gilsonite and oil bearing sands form natural waveguides for low loss transmission of electromagnetic (EM) waves. The waveguide forms whenever the seam is bounded by more conducting claystone, mudstone, shale or in the case of oil/gas traps, by a floor of saline water. Disturbances caused by faults, shear zones, paleochannels, sills and dikes significantly alter the propagation constant. The analytical values of the EM wave propagation constants depend on the physical and electrical parameters of the seam. The values are presented in this paper in a graphical form to assist in the interpretation of RIM tomographic images. This paper compares in-mine geologic mapping obtained during mining to tomographic images of the geologic disturbance zones in a Central Utah coal mine.

Jan 1, 1989

By S. Liu

A general account of nitrogen-generating systems, including the surface fixed, surface-mobile and underground-mobile types is presented. These systems have recently been adopted in coal mines in China to prevent and extinguish fires. The paper stresses nitrogen -injection technology and relevant systems of monitoring and stopping air leakage.

Jan 1, 1998

By M. A. Cristovici

The use of surfactants as wetting agents to suppress sulfide ore dust has been investigated. Numerous surfactants were examined to determine their characteristics and to investigate their ability to improve the wetting of the sulfide ore dust. However, the surfactants selected as suitable dust suppressors proved to have a negative effect on the flotation of ore contaminated with such reagents. A method was developed to eliminate the detrimental influence of dust-suppressing surfactants. It consisted of surfactant adsorption on activated carbon and separation of loaded carbon prior to flotation. The technique is simple and requires minimal changes in the plant flowsheet.

Jan 1, 1992

By Hans von Michaelis

Metallurgists are trained to seek synergisms and to optimize trade-offs in the selection of processes and flowsheets. The subject of my paper and the focus of this entire conference is on synergisms involving more than just metallurgical recovery, but encompassing mining and environmental management too. Operators have always known that by recycling tailings water they could recover some cyanide and lime values or reduce the amount of new flotation reagent additions. The trade-offs have changed at many US mines today where concern about avian mortality necessitates that water in the tailings pond be detoxified. This is just one example of how selection of processes and technology today requires integration of environmental management. MUDDER & GOLDSTONE (1989) showed how cyanide can be recovered from tailings slurries by an acidification­volatilization-reabsorption (A VR) process which was installed in New Zealand, and which in 1992 is being commissioned also at Nerco DeLamar Silver Mine as described by OMOFOMA & HAMPDEN (1992). FRICKER (1990) and FRICKER & OWERS (1992) show how using A VR to recover cyanide from pregnant pulps ahead of gold recovery improves the yield of recoverable cyanide while improving the performance of the gold recovery step and detoxifying the tailings. This is an excellent example of the synergisms that can be achieved ,y applying a "systems approach."

Jan 1, 1992

By S. Ash

Murray mine was one of the first Mechanized cut and fill underground gold operations in Northern Nevada. At the end of 2002 mine production began to decline and Murray entered a phase of remnant mining and began preparations to close down. The remaining mining took place along the ore waste boundary, in previously condemned areas, and in highly challenging ground conditions. To remain economically viable new techniques were implemented in operations, geology, engineering, and rock mechanics. These improvements pushed the edge of known and accepted mining practices and have allowed Murray to remain in operation today. History The Murray mine is located on the Jerritt Canyon property, which is located 45 miles north of Elko, NV in the Independence mountain range. Mining operations started at Jerritt Canyon in 1980 out of several open pits. In 1993 underground mining began in conjunction with a decline of surface mining operations. The transition from surface mining to underground mining moved the property into a new era. At the time there were limited examples of successful underground operations in the area from which to draw experience. Several mining methods were attempted with varying degrees of success and underhand cut and fill proved to be the most effective method. To date Murray has mined 1.2 million ounces at an average grade of .335 OPT utilizing this mining method.

Jan 1, 2006