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By Boris CARO VARGAS, Bernard Theron

"In early 2014, Nicholson Construction Company was awarded, together with its tunneling sister company Bessac, the Norris Cut Miami Tunnel Project. The 2.5-meters diameter segmental lined tunnel, 1600-meters long, is aimed to replace the existing 54” force main connecting the Waste Water Treatment Plant (WTP) on Virginia Key to Fisher Island. To overcome project challenges such as the highly permeable limestone of the Fort Thomson Karstic Formation (one of the most permeable formation in the World), the project team has developed State of the Art solutions: The TBM was launched with pipe-jacking technique for the first 70-meters and then converted to segment erection mode. It allows substantial schedule savings and drastically reduces the size of the circular launching shaft. The TBM, jointly designed and manufactured by Bessac and Herrenknecht, can convert from slurry to EPB mode within a few minutes. The cutters can be replaced by wet divers thanks to an innovative application in the TBM industry. PRESENTATION OF THE PROJECT The aim of this project is to replace the existing 54-inch force main pipeline which transmitted all sewage collected from Miami Beach, Surfside, Bal Harbour, Bay Harbor, North Bay Village and Fisher Island to the Central District Wastewater Treatment Plant (CDWWTP) to Fisher Island. The existing pipeline consisted of pre-stressed concrete cylinder pipe which is in poor condition in a number of locations and could be subject to sudden failure. An adjacent portion of this existing force main under the Government Cut (North Fisher Island) has already been replaced as part of a previous design-build contract and involved the installation of a 60-inch diameter fiberglass-reinforced mortar pipe installed inside a micro-tunneled casing."

Jan 1, 2016

By J. M. Mutmansky

This paper outlines patterns of methane emission in both longwall and room-and-pillar operations and the effects that these patterns have on the decision as to whether the methane is most economically handled by ventilation alone or by means of a methane drainage system in addition to ventilation. The costs of handling the methane in the ventilation system and the costs of implementing the methane drainage system will be discussed as well as the costs related to the production of coal. The important issue of production slowdowns and gas outs will also be discussed as well as the proper response of mine management to such a situation. Suggestions concerning the keeping of production records related to methane problems will be made as well as justification for more intensive economic analysis of coalbed methane extraction and utilization.

Jan 1, 1998

By R. L. Loofbourow

Most wet mines face unquantified water costs as well as the obvious wing costs. Both kinds of cost are multiplied by work at greater depth and by higher unit prices. This intensified challenge merits renewed or perhaps altogether new response. Any practicable way to reduce inflow tackles both obvious and unquantified costs. Ten groups of possible ways to do it are cited. Most have been demonstrated. Two are known from work other than mining. Surely new means can be found. Here are opportunities for operators of wet mines!

Jan 1, 1980

By N. Nemeth

The filter is an apparatus designed to hold the filter medium. At such a medium takes place the entire liquid-solid or gas-solid separation process. Hence, the medium is really the essence of filtration. Yet, the medium, an originally clean porous substance with trapped solids in it, is perhaps the most neglected part of filtration research. Basically three problems prevail at the medium: 1) Penetration of solids and their blinding of the medium and the influence of such blinding on the resistance to flow. ii) The behavior of the medium in long term repetitive filtration. iii) The filter effect phenomenon whereby the flow rate on filtering an apparently clear liquid through a medium decreases with time. This study undertakes to investigate these fundamental processes.

Jan 1, 1968

By C. C. Harvey

As we move towards the 21st Century there are several factors that will influence the markets and processing requirements for industrial minerals. Traditional markets for many industrial minerals in the developed world are frequently stagnant or decreasing because of their maturity or due to environmental factors such as reclamation, recovery of byproducts, and recycling. Some industrial minerals are greatly affected by these factors, while others are either immune to or have adapted successfully to meet these challenges. In the developing countries of the world, there is rapid market growth and resource exploitation. The future of specific mineral commodities in several markets will be discussed.

Jan 1, 1997

By Barbara J. Arnold

The Electric Power Research Institute (EPRI) and six EPRI-member utilities are sponsoring research to define relationships between coal properties and coal handling behavior. Deratings and outages caused by plugged chutes or bunkers or frozen coal can cost utilities millions of dollars annually in lost energy production as well as in manpower to restore coal flow. There is also the added expense of maintaining redundant equipment to assure a continuous coal feed to the boiler, a common practice for utilities. Over the past two years, researchers at CQ Inc. and Iowa state university have collected and analyzed coal samples to develop a coal handleability index for utilities to use when specifying coals for their power plants. These coal samples cover ranges in ash content, rank, grindability, size distribution, and moisture content--properties that affect the handling behavior of coals. Other properties, such as the washability and ash composition, are measured as well. Over the remaining two years of the project, all of these analyses will be correlated to handling behavior, measured using a triaxial shear tester that determines the strength of a coal under compression. An index will be developed and validated at host utility power plants.

Jan 1, 1991

By R. F. Hüttl

The restoration of surface mining landscapes requires the (re)creation of ecosystems. In Lusatia (eastern Germany), large-scale open-cast lignite mining operations generated spoil dumps widely consisting of acidified, phytotoxic substrates. Amelioration and rehabilitation measures have been developed and applied to these substrates since the 1950s. However, it is still not clear whether these approaches are sustainable. This paper reports on collaborative research work into the ecological potential of forest ecosystem development on typical minesites in the Lusatian lignite district. At first sight, pine stands on minesites along a chronosequence comprising about 35 years did not show differences when compared with stands on non-mined sites of the general region. Furthermore, with some modification, conceptual models for flora and fauna succession in forest stands on non-mined sites seem to be applicable, at least for the early stages of forest ecosystem development. For example, soil organism abundance and activity at minesites had already reached levels typical of non-mined sites after about 20-30 years. In contrast, mine soils are very different from non-mined soils of the test region. Chemically, mine soil development is dominated by processes originating from pyrite oxidation. Geogenic, i.e. lignitic, soil organic carbon was shown to substitute for some functions of pedogenic soil organic matter. Rooting was hampered but not completely impeded in strongly acidified soil compartments. Roots and mycorrhizae are apparently able to make use of the characteristic heterogeneity of young mine soils. Considering these recent results and the knowledge accumulated during more than 30 years of research on minesite rehabilitation internationally, it can be stated that minesite restoration might be used as an ideal case study for forest ecosystem development starting at "point zero" on "terra nova".

Jan 1, 2002

By David Sainsbury, Bevan Thompson, Yuejun Cai

The practice of placing loose rockfill as passive support in open stoping voids, of narrow vein mineral deposits, lends itself to the sterilisation of substantial mining reserves in the requirement for regional crown/sill pillars. Significant benefits are to be gained by the Australian mining industry via the development of improved guidelines for the extraction of such sterilised mine pillars. The application of selectively injecting specifically developed ettringite (calcium sulphoaluminate hydrate) type cement grout into loose rockfill, enables an artificial pillar to stabilise the surrounding rockmass and prevent the caving of loose rockfill from the previously backfilled void during extraction of remnant crowdsill pillars. This paper presents the results of laboratory testing used to reduce the technical risks associated with the design of cemented rockfill pillars. A laboratory testing program was devised to investigate the critical parameters influencing the performance of a stabilised rockfill matrix, along with the critical parameters influencing the interpretation of laboratory test samples. The factors investigated include; sample size and shape, particle size distribution, curing time, water quality, cement : water ratio and the confinement effect.

Jan 1, 2001

By Richard L. Coleman

El trabajo de ensayo metalúrgico para desarrollar un flujograma es el que ahora describimos, comenzando con una información experimentada requerida en todo momento hasta llegar a un esquema final de flujo de un proceso. Tanto las pruebas de laboratorio como de planta piloto son revisadas adecuadamente sobre las experiencias anteriores.

Jan 1, 1982

By Kent C. Condie

Precambrian terranes in the Rocky Mountain region decrease progressively in age from the Archean Wyoming Province (> 2.5 b.y.) to the late Proterozoic in West Texas (figs. 1,2). Within the Wyoming Province, most dates fall near 2.7 b.y. although some are recorded at 2 3.8, 2.9, and 2.6 b.y. Although Penokean (- 1.8 b.y.) deformation and plutonism are recorded in southeastern Wyoming, most Precambrian rocks south of the Wyoming shear zone, which separates the Archean and Proterozoic provinces, are < 1.76 b. years in age. Supracrustal rocks in Colorado, western Arizona, and northern New Mexico fall in the range of 1.72-1.76 b.y., those in central New Mexico about 1.65 b.y., those in southeastern Arizona and southwestern New Mexico about 1.70 b.y., and those in West Texas 1.1-1.2 b.y. The Wyoming Province is comprised chiefly of 2.7 or 2.9 b.y. tonalitic gneiss terranes intruded by 2.6 b.y. granites in the central and southern parts of the province. Supracrustal rocks are minor and include greenstone belts comprised chiefly of pillow- ed tholeiites and graywackes and remnants of quartzite-shale successions. Metamorphic grade in greenstone-gneiss terranes ranges from upper greenschist to amphibolite facies and in quartzite-gneiss terranes from upper amphibolite to granulite facies.

Jan 1, 2013

By John C. Draper

The principal object of an underground coal mine transportation sys- tem is to move coal from the face where it is produced to the outside of the mine where it is prepared for market. In addition to the movement of coal, a transportation system must also move supply materials to the inside; it must move men in and out of the mine; and it must move rock and other debris out of the mine for disposal. Usually, mine haulage is divided into three categories named for the various areas of the mine served : 1) Pace Haulage. This is used at face from the mining machine to the intermediate transport system. 2) Intermediate or Secondary Haulage. Generally this is used between face haulage and main haulage. Sometimes this is merely an extension of the main haulage. 3) Main Haulage. This extends from the secondary haulage to the outside and is usually either a track or conveyor system, sometimes a combination of both. Transportation modes of coal in the various areas pose different problems, but the whole system must be synchronized. For instance, at the face the coal should be removed quickly from the various places to facilitate the movement of machines, whereas the intermediate system just passes the same coal on to the main transportation system. Selection of the transportation system must be based on the seam height, mining methods used to extract the coal, capacity required, ease of coal handling, and haulage efficiency. When driving rooms, mine cars can be used. They often simplify supply haulage and rock handling because they can also handle these items. Conveyors could be used and would have a greater haulage capacity but they cannot handle supplies easily or segregate the rock. When using a different mining method, such as longwall, mine cars cannot be used because there is not sufficient space to move the cars at the face nor can the cars haul the coal without delays which would cause excessive losses in production. As for ease of handling at a longwall face, conveyors are convenient because of their low height, ruggedness, and ability to operate while being advanced. Similarly, in low seam heights, conveyor systems are easier and more economic to operate than the regular track haulage because roof has to be taken down for handling mine cars of adequate size.

Jan 1, 1981

By Mark Colwell

As per most other earth science engineering problems, the underground coal geotechnical environment and the way in which roof and rib support interacts with the rock mass are complex issues. While the problem should not be oversimplified (i.e., the dominant failure mechanisms or critical data input parameters should not be ignored), without question judicious simplification is at the heart of all good engineering design. Engineers play a vital role in supplying the world with solutions and products; however it is crucial that engineers make practical and readily useable contributions. One way to ensure this is to employ simplification in the engineering process.

By Daniel A. Wasson

A review of the history of boosters is given with examples of the prominent types that have been made commercially. The performance and design features of protected core boosters are discussed in detail. A new gel booster is discussed with its advantages to the mining industry. Booster size, hole configuration, performance and safety aspects are reviewed. Important features of boostering in above ground and underground blasting are related to an economic analysis. This presentation will cover different types of boosters commonly used in mining. However, for the purpose of this paper a few terms need to be defined to clarify the action of different parts of a priming system. Booster* - "Any unit of explosive or blasting agent to be used in a charged hole for the purpose of perpetuating or intensifying the initial detonation". Primer* - "A unit, package or cartridge&apos; of explosives containing a detonator or detonating cord which is used to transmit detonation to other explosives or blasting agents". Detonator - A device for initiating a detonation from a flame or a small electric current, the former being represented by a fuse cap and the latter an electric blasting cap.

Jan 1, 1981

By Edwin B. Wilson

Electric power generation remains the greatest market for coal in the United States. In 1967, about 272 million tons of coal, amounting to over 51 percent of total coal consumption, were burned to satisfy this nation&apos;s hugh demand for power. The size of the utility market is currently five times that of 1941 and continues to grow with the demand for more and more energy. A major reason for this strong market has been the ability of the coal industry to supply a superior product for combustion while maintaining competitive prices. Now that the coal industry is engaged in intensive competition with nuclear power for future energy demand, it becomes ever more imperative that superior coal products are produced. One important problem when burning some coals is a liquid phase corrosive attack on boiler tube metal in the superheater and reheater areas of the furnace where steam temperatures may exceed 1050°F.

Jan 1, 1969

By S. S. Nadgauda, A. J. Hathaway

Typically, as long as the coal quality is within the specified range, electric utilities have used delivered cost of fuel per million Btu as the primary criteria for qualified coals when making coal-procurement decisions. Such an approach may not fully address the total cost of using different quality coals at a given plant. A practical and easy-to-build model is described for estimating plant-specific utilization costs for coals of different qualities. Examples are included to illustrate the modeling results for plants operated by two utilities. While the model has certain limitations, it does represent an improved method for evaluating coal bids, and, consequently, reducing generation costs.

Jan 1, 1990

By Malcolm J. A. Swallow

In June 1997, Mount Polley Mining Corp., a division of Imperial Metals Corp., completed an 18-kt/d (20,000 stpd) gold-copper mine in central British Columbia. Fast-track construction and extensive off-site construction were combined with an aggressive project schedule to build the mine in one year. This was three months ahead of schedule and 7% below the original budgeted cost of C$123.5 million (US$86 million). The Mount Polley Mine was the first of a crop of new open-pit mines in British Columbia. The Mount Polley deposit has been explored since the mid-1960s when it was known as the Cariboo Bell property. From 1988, Imperial Metals completed drilling and metallurgical testing on the deposit. This led to a positive feasibility study and the issuing of a Mine Development Certificate in 1991. The project was later shelved due to falling metals prices and the strength of the Canadian dollar. In late 1994, Imperial merged with Bethlehem Resources Corp., bringing a strong project team to the company. The deposit was then re-evaluated, ore reserves revised and additional metallurgical testing was performed. The result was a revised project plan. It indi¬cated that a financially feasible gold-copper mining op¬eration could be constructed at Mount Polley operat¬ing at 18 kt/d (20,000 stpd). In May 1996, an agreement was reached with Sumitomo to jointly fund and develop the project. By early 1996, final plans and permits were being prepared for construction, scheduled to begin in June 1.996. On-site work commenced on May 28th, 1996 following lifting of the road restrictions. Mount Polley Mining acted as its own project manager. Construction was completed in June 1997. Plant runup took place in July and full production began in August. Through the use of off-site construction and the careful selection of contractors who cooperated to complete some 12 major contracts, it was possible to reduce the mine and mill construction time from 16 to 13 months. Off-site construction for all possible aspects of the work and the use of used milling equipment allowed significant savings in overall capital costs of construction. Total costs for the mine, mill and tailings dam equated to C$6,100/t/d of throughput. The mill design incorporates several innovative features that will aid maintenance and allow flexibility of operation. The operation is designed as a closed system and meets the latest environmental standards. Concentrate is shipped by truck to the port of Vancouver. Revenues for the mine come from the mine&apos;s production of about 3.1 t/a (100,000 oz/year) of gold and 10.8 kt/a (24 million lbs/year) of copper during the first four years of the 12-year mine life.

Jan 1, 1998

Jan 1, 1999

By Joel Nonnweiler, David Young, John Hawley

The Sacramento Regional County Sanitation District has implemented a billion-dollar interceptor system master plan, including the 31 km (19 mile) long Lower Northwest Interceptor (LNWI). For the two LNWI Sacramento River crossings, pipe-jack/micro tunnel drives in excess of 300 meters (1,000 ft) from 30 meter (100 ft) deep shafts in mixed soil conditions below the water table were considered, as were600 meter (2,000 ft) tunnel drives utilizing pressurized-face tunnel boring machines. Operation and maintenance concerns, predicted flood scour, and levee concerns are discussed. A risk assessment process was used to select both profile and construction method. Construction will begin in mid 2004.

Jan 1, 2003

By James K. Gowans

The Red Dog Operation is located in northwestern Alaska at Latitude 68°, 100 miles north of the Arctic Circle and 50 miles inland from the Chukchi Sea. The orebody was acquired by the NANA Regional Corporation, (an Alaska Native Corporation established by the Alaska Native Claims Settlement Act of 1971), in 1980 in their land selection. In 1982 Cominco American and the NANA Corporation signed a development agreement and Cominco Alaska Inc., a wholly owned subsidiary of Cominco American, was formed to manage the Red Dog Project. An extensive exploration program in 1980 -1982 outlined a mineral inventory of 85 million tons, at a grade of 5.2% Pb, 17.1 % Zn, and 2.4 oz/ton Ag, which makes the Red Dog the second largest deposit ever discovered. Broken Hill, in Australia, is the only zinc orebody which was originally larger than Red Dog. The design of the facilities is to process 2.1 million tons of ore annually, which will produce 560,000 tons of zinc concentrate, 100,000 tons of lead concentrate and 50,000 tons of bulk lead/zinc concentrate.

Jan 1, 1991

By Hung-Kei H. Lam

Rubidium and cesium were discovered by Bunsen and Kirchhoff about 100 years ago. These two elements are by no means as abundant as sodium or potassium. Their occurrence in minerals is widespread, but usually as minor constituents. There is no known specific ore containing rubidium, but rubidium is found replacing the. other alkali metals in .some minerals.. Perhaps the highest concentration of rubidium found in one mineral is in lepidolite, KLi(OH,F)2A12Si3010, which contains from 0 to 3.5%*Rb20. 0n the average, lepidolite contains about 0.5% Rb20. Other sources of rubidium are carnallite, KMgCl3?6H20; pollucite, H20.2Cs20.2AI203.9SiO2; rhodizite, R20.2A1203-3B203; biotite, H2K(Mg,Fe)3A1(Si04)3; sea water, rivers, marine and fresh water organisms, soils, and plants. Cesium, even though it is the least abundant. of the stable alkalies, has a specific ore. Pollucites a hydrous cesium aluminum silicate, may con¬tain as high as 42.5% Cs20, although again, the average Cs20 content is about 25% among the handful of known deposits. Other cesium-containing minerals are lepidolite and carnallite. Rubidium and cesium are very much like potassium in chemical properties, consequently, they are hard to separate. Because of the difficulty in obtaining pure cesium and rubidium compounds coupled with the scarcity-of supply, prices were high and the two elements enjoyed little industrial use. Just before the Second World War, the world. supply of rubidium and cesium, from Germany, was a matter of tens of kilograms per year and prices were about

Jan 1, 1959