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By P. Somasundaran, J. T. Kunjappu

Spectroscopic techniques are becoming increasingly popular for characterizing the interior of adsorbed layers of surfactants and polymers at solid- liquid interface as well as in the identification of com- pounds on mineral surfaces. This review encompasses the application of fluorescence and ESR spectroscopic techniques to reveal the microscopic environment of the adsorbed layers of surfactants and polymers on minerals with a special reference to the adsorption of anionic surfactants (e.g., sodium dodecyl sulfate) and polyelectrolytes (e.g., polyacrylic acid) at positively charged mineral (e.g., alumina) - water interfaces. Finally, the utility of XPS and auger techniques to identify the surface elemental composition of different mineral species has been related to their flotation efficiency.

Jan 1, 1987

By Ing. E. h. Martin Herrenknecht

The paper will describe a number of developments and innovations now in use in microtunnelling machines. These include the use of fuzzy logic steering systems, the proven ability to successfully undertake complex curved microtunnel drives, the ability to complete ultra long drives using microtunnelling techniques, and machines with access to the face of the machine from inside the machine. The ability to tunnel in relatively hard rock utilizing a rock head with back loaded cutters changeable from inside the microtunnel machine and the ability to utilize microtunnel machines in multi modes, such as hard rock mode, “open” mode, EPB mode, and slurry mode with the same base machine again with access to the face of the machine will be described. In addition, the latest computer technology gives the operator “full visualization” of machine functions together with the ability to data log machine operating parameters. Reference will be made to a number of projects worldwide recently completed or under way where these innovations have successfully been utilized.

Jan 1, 1999

By James S. Scott

Effluents discharged from gold mills, and more recently from heap leaching operations, pose significant hazards to the environment if not properly managed prior to discharge. This paper describes the nature of wastewaters which must be treated, the treatment processes being applied in Canada and the capabilities of these methods in removing cyanide and metals. As a result of past practice the most common method of reducing cyanide in gold mill effluents remains that of natural degradation in tailings ponds. This method has proven capable of producing high quality effluents where large ponds and sufficiently long water retention times can be provided, but at many mines this has not been the case. Since 1981, as a result of these limitations there has been a strong move in Canada to chemically-based effluent treatment plants, particularly as additional processes became available. Canadian gold mills have become leaders in the use of chemical processes to remove cyanide, in terms of the variety of such processes in operation (five in total), the number of plant installations and the number of processes developed in this country. The hydrogen peroxide and Inco SO2-air processes, in that order, are being applied most widely. Alkaline chlorination, the initial process to be used fairly extensively has been almost totally replaced by the two methods mentioned above. Since a number of effective methods are now available for the treatment of gold mill effluents, the selection of a process for application at a specific mill requires careful consideration of:

Jan 1, 1987

Unless otherwise indicated, pounds are US avoirdupois, feet are US, and gallons are US.

Jan 1, 1985

By Alfred C. Maevis

On October 27, 1972, ground was broken for the first section of the Second Avenue Subway, a two track underground rail system that was to extend from the south end of Manhattan at Broad Street, north to the Harlem River at 126th Street, a distance of eight miles. This ground breaking was the culmination of 67 years of planning for an east side subway in Manhattan. Following the successful opening of New York City's first subway on October 1904 there was a mass planning for additional subways throughout the City. In 1905 approval was requested of the Board of Estimate for a First Avenue route and Third Avenue route. The Third Avenue route was approved but when action was not taken to start construction, the approval in accordance with the conditions under which it was given was withdrawn. Further reports and plans for an east side subway, usually to be constructed on Third Avenue, were issued in 1920, in 1922, in 1924, etc. Those of us who had worked on the Sixth and Eighth Avenue subways in the thirites and early forties left to join the armed services of World War II in the expectation that we would return and start work on designing and constructing that east side subway. The reason that much of the thrust in those years was to construct on Third Avenue was that there was a Third Avenue "EL" and business interests of the City were in favor of its demolition. This demolition was accomplished in 1955 so one of the incentives to construct on Third Avenue was removed; but an east side subway was always part of the master plan of the City.

Jan 1, 1976

By K. E. Hjelmstad

Solution mining operations often encounter difficulty maintaining adequate leach solution flow into the ore formation because of loss of formation permeability near the injection well. Permeability loss caused by swelling and breakup of clays and fine particle migration can often be the cause of the problem. Combined permeability and leaching tests were done in the laboratory on samples of clay bearing ores to evaluate a clay-stabilizing polymer's effectiveness in preventing the problem. Test results indicate that treating the ores with cationic polymers could maintain permeabilities two to five times greater than the long-term permeabilities present in untreated ores. Both alkaline (pH 8.5) and acidic (pH 2.0) leaches were used in the permeability leaching tests. To determine the reasons for the success of the clay stabilizing polymer, clay swelling tests and zeta potential measurements were made on untreated ore samples and on ore samples treated with the cationic polymer. Test results indicate the cationic polymer could reduce the degree of negative charge on fine particles and their tendency to disperse, as well as reduce clay swelling. Test results indicate a potentially beneficial effect on operating parameters such as capacity and injection pressure during leaching, if clays and fines are kept stabilized. This may be done by treating the zone of high fluid velocity near injection wells with cationic polymers.

Jan 1, 1991

By Andreas G. Mueller

Gold-silver and copper-gold deposits with high-temperature wallrock alteration of Ca-Mg-Fe-Al silicates occur in ca. 3.0 Ga old greenstone belts of the Yilgarn Block, Western Australia. The deposits are hosted by amphibolite-facies komatiites, basalts and BIF, controlled by ductile shear zones and located within the contact-metamorphic aureoles of composite granodiorite-granite batholiths. Disseminated sulfides and free gold form foliation-parallel ore zones in a gangue of anhydrous silicates (garnet, clinopyroxene, olivine), hydrous silicates (amphibole, biotite) and calcite. The deposits may be classified on the basis of their dominant economic metals as: 1(1) Gold skarns with substantial silver as by-product, represented by the Marvel Loch mine (production: 2,200,000 t at 3.5 g/t Au), and characterized by the mineral association pyrrhotite, loellingite, arsenopyrite, galena, gold and magnetite. (2) Gold skarns with low silver contents, represented by the Nevoria mine (production:1,850,000 t at 3.4 g/t Au), and characterized by the mineral association pyrrhotite, chalcopyrite, arsenopyrite, gold, Bi-tellurides and magnetite. (3) Copper-gold skarns, represented by the Elverdton mine (production: 850,000 t at .7 5 Cu, 0.81 g/t Au), and characterized by the mineral association magnetite, chalcopyrite, pyrrhotite, pyrite, gold and Ag-Bi tellurides.

Jan 1, 1990

By W. G. Pariseau

Regression analysis of calculated on measured displacements were used to assess the influence of fill and fold plunge on shaft pillar mining at the Homestake Mine. These effects were neglected in the original three-dimensional finite element analysis undertaken in 1991. An average fold plunge of 15? and a 24K fill (Young’ modulus of 24,000 psi or 165 Mpa) were used in the reanalysis. Measured displacements were obtained from an array of 36 m (120 ft) multiple-position borehole extensometers installed in June 1994 and read to March 2003. Results indicate the effects of both on calculated displacements and thus on regression parameters are noticeable. However, these neglected effects would not have changed the original inference of Ross Shaft stability during pillar mining.

Jan 1, 2004

By Mike O’Brien, Rob Croll

The Evolution of AngloGold -Incorporated in 1944 under the name of Vaal Reefs Exploration and Mining Company Limited -Name changed to AngloGold Limited in 1998 as the vehicle consolidating the gold interests of Anglo American Corporation -Diversification (geographic and orebody) through the sale of low-margin, deep level, short-life assets and the acquisition of higher margin, open-pit and shallow underground operations

Jan 1, 2003

By Fathi Habashi

METALS COMMONLY leached may come from one of the following sources: 1) Occurring in nature in the native state, e.g., gold, silver, platinum metals, copper. 2) Produced as by-product of a metallurgical process, e.g., gold, silver, platinum metals, selenium. 3) Produced by reduction of an oxide ore, e.g., copper, nickel. GOLD AND SILVER Cyanidation According to Mellor (1923) the alchemists of the eighteenth century knew that gold was soluble in aqueous solution of potassium cyanide, and the early jewelers probably utilized this fact in gilding. He also mentions that Scheele in 1783 and later Bagration in 1843 noted the solvent action of aqueous solutions of alkali cyanides on gold. Yet it was not until 1887 that the value of this observation was recognized, when MacArthur and Forrest (1887) made use of it in leaching gold from its ores. Since then, the process has spread to every gold and silver mining district in the world.

Jan 1, 1970

By T. Ruff, J. Steele

The lack of visibility near earthmoving equipment results in an average of five fatalities in U.S. surface mines each year. These accidents occur when a piece of equipment either strikes another vehicle or worker, or travels over the edge of an embankment. Researchers at the National Institute for Occupational Safety and Health have evaluated off-the-shelf proximity warning systems that sense obstacles near the equipment and provide an alarm to the operator. Limitations of existing systems have necessitated the development of new systems designed specifically for mining equipment, including a GPS-based proximity warning system and a computer-assisted stereovision system.

Jan 1, 2004

By Phillip O. Tyree, R. A. Metz, Joseph W. Mussey

Bio-epigenetic sulphur deposits occur in Pecos, Reeves and Culberson counties of far West Texas. Sulfate reducing bacteria, utilizing hydrocarbons as energy, transformed gypsum into replacement limestone and hydrogen sulfide. Hydrogen sulfide, retained in the pores of the replacement limestone, was subsequently oxidized by highly oxygenated groundwaters, and native sulphur precipitated. West Texas sulphur was first recognized at surface exposures by William P. Blake, a geologist attached to the Captain Pope Military/ Scientific Expedition of 1854. Attempts were made in the early 1900's to mine these sulphur vent exposures by a retort method, but the ventures met with little success. In 1967, Duval discovered a large sulphur deposit near some of the old sulphur works in Culberson County. Duval also expanded reserves in a small sulphur deposit in Pecos County. The Frasch process, developed for producing sulphur from Gulf Coast salt domes, proved successful in West Texas type sulphur deposits also. However, modifications of the process were necessary to provide economical and efficient sulphur recovery from the varied ore occurrences. West Texas conditions and logistics require the ultimate in productivity to be competitive in the domestic and foreign sulphur markets. Several companies, in addition to Duval, are producing or have produced sulphur in West Texas. As of June 1, 1984, a total of 29.87 million mt (29.4 million long tons) of sulphur had been produced west of the Pecos River. Duval corporation has produced more than 88 percent of that total.

Jan 1, 1992

By Guido Venturini, Giorgio Martinotti, Luca Delle Piane, Paolo Perello

This paper presents a critical review of geo-structural mapping methodologies applied to deep tunneling projects in complex mountain chains such as the Alps. Geological forecastings are often a crucial part of tunneling projects, which should allow contractees or contractors to assume their own risks. Despite this, often adequate methodological criteria are not applied in the realization of these studies, with consequent increase of costs and delays. A discussion should hopefully start in the world of tunneling in order to define a correct approach.

Jan 1, 2003

By Nikhil Dhawan, Veeranjaneyulu Rayapudi, Singh Rahulkumar Sunil

The ever-increasing demand for steel and the subsequent depletion of high-grade ores requires the massive utilization of low-grade iron ores. In the present study, an iron ore slime sample containing 56.1% Fe was investigated using physical beneficiation, carbothermal reduction, and a microwave-assisted process; however, physical beneficiation and microwave exposure were found to be inefficient as they yielded lower iron recovery. Using coconut shell as an alternative reductant was found to be promising and does not lead to the formation of higher iron oxides, such as fayalite and wustite phases. The microwave-assisted carbothermal reduction was found at par with conventional reduction, saving time and heating. The optimum magnetic concentrate obtained in both carbothermal reduction routes (microwave and muffle furnace: Fe grade, Fe recovery, and yield of 64.3, 97, and 84%, and 67, 99, and 83%, respectively) are suitable for alternative iron-making or blast furnace units.

By Stanley J. LeFond

After two disappointing years where most industrial minerals posted decreasing production, 1981 saw an increase in production over 1980, or at least in status quo. Several commodities did, however, post significant gains. For example, bromine posted a 14% increase; fluorspar production dropped 21% in 1980, but gained 24% in 1981; and sulfur production increased. However, perlite was off 13% and manufactured sodium sulfate off 18% in 1981, while natural sodium sulfate production remained almost even with 1980. In fact, many industrial minerals production either remained constant, increased, or decreased only slightly over 1980. Increasing energy costs had their impact on industrial minerals in 1981. Hopefully, the recent downward trend in energy costs, at least gasoline, will financially help some of the more marginal plants. The 1979 shortage of rail cars that did not carry through 1980 also did not carry through in 1981. Rail rates increased 12.8% over-all last year, while average freight rates for industrial minerals increased 15.5%, according to Neil Johnson, consultant. Also, the trucking industry posted a 5-6% decrease in rates due to deregulation. All in all, we in the industrial minerals section seem to be holding our own at least. Stanley J. Lefond Contributing Editor

Jan 5, 1982

By C. P. Shen, H. C. Tsai, Bennie Chu, Y. S. Hsieh

The Pinglin tunnels are situated within the fold-and-thrust belt structural region in Taiwan, due to continent-arc collision and plate tectonic setting. The pilot tunnel TBM (§=4.8m) became stuck ten times with the standstills to date. The westbound main tunnel TBM (§=11.74m) was buried in a collapsing calamity. The main tunnel TBM shall identify and overcome the adverse geology with high volume of ground water ingress itself. This paper presents our experience and methodology through the adverse geology with Pinglin large TBM.

Jan 1, 1999

By Jerome C. Motz

Los tipos, tamaños y número de trituradores empleados en un sistema completo de reducción varían con factores tales como: el volumen de mineral que debe ser procesado, tamaño de la mina, tamaño máximo del todo-uno, dureza del mineral y de su roca soporte y tamano requerido para el producto final. Básicamente, sólo existen tres tipos distintos de equipos de trituración para la etapa primaria. Estos son: machacadoras de mandíbulas, trituradores giratorios y molinos de impactos, y cada uno tiene unas características operativas propias. Las trituradoras de mandíbulas operan por aplastamiento de las rocas entre dos paredes, una fija y otra móvil, en una cavidad determinada. Han sido ensayadas variaciones en la caída y movimiento, pero la mayoría de las máquinas del tipo Blake tienen un ángulo de trituración de aproximadamente 27° entre las mandíbulas fijas y móviles. El principio de trabajo del triturador giratorio es muy simple. Si un cono es montado en un eje vertical y la parte superior del eje se sitúa estacionaria mientras que la parte inferior gira excéntricamente, el cono tendrá también un movimiento excéntrico. Si el cono se coloca en una carcasa conveniente se movers aproximándose y retrocediendo de las paredes que lo contienen a la vez que gira. Si el cono y las paredes de la carcasa son suficientemente robustas y pesadas, cualquier cosa apresada entre ellas será triturada. Al lado de los incrementos de la eficacia desarrollados por las continuas acciones de trituración y el curvado de las caras de trituración, los trituradores del tipo giratorio tienen las siguientes ventajas: 1. La gran abertura de alimentación disponibles en comparación con trituradores de otro tipo. 2. El alto rango de tamaños y capacidades, que se encuentran entre 600 y 6.000 toneladas por hora. 3. Generalmente no es necesario control en la alimentación. Dumpers de 150 a 200 toneladas descargan directamente en las actuales instalaciones.

Jan 1, 1982

By Richard M. Bennett

Twelve linear test foundations were constructed over an advancing longwall panel in southern Illinois, six were located along the centerline, and six in the maximum tension zone. One footing in each set was a control foundation constructed according to conventional practice. It suffered severe damage. Footings with reinforcing bare and post-tensioning had much smaller elongations, with the post-tensioning preventing cracking of the footing. Footing-soil interface treatments of plastic-on-sand and plastic-on-soil served to reduce damage. The addition of steel fibers to the footing had about the same effect as an interface treatment. Sill plate construction (butt-jointed versus lap-jointed) appeared to significantly affect the behavior.

Jan 1, 1986

By F. Romero, L. Yacher, M. Orchard

Specific software tools for Statistical Multivariate Analysis combined with real time process data were applied to Concentrator Plant at Compañía Minera Doña Inés de Collahuasi SCM in Chile, basically to two Mill Lines, each one with one SAG mill (32’x15’8MW)and one Ball mill (22’x36’9.7MW). The main objective was to empower the operator actions using process patterns references instead of process variable set-points. Pattern clustering and the analysis of pattern deviations regarding normal or desired pattern, allows for improvements in process control and the further implementation of soft sensors for those variables not included in the initial model.

Jan 1, 2003

By D. S. Choi

The paper contains a subsidence measurement taken over a room and pillar panel of a mine located in northern West Virginia. A total of 72 monuments were used to determine a three dimensional view of mine subsidence. In addition, the results of measurements were used to compute ground strains with the use of a numerical model.

Jan 1, 1982