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By J. Wagner, P. Eger

Although lifetime estimates for sulfate reduction based on total substrate carbon typically range from 20 to 30 years, field and laboratory experiments showed that rates of sulfate reduction decreased over time as readily available organic material was consumed. When the rate of acid input exceeded the rate of sulfate reduction, alkalinity was removed from the substrate, the pH decreased and metals increased. Output pH increased from 4 to more than 6 after the system was shut down for several weeks and the rate of acid input was reduced. Successful long-term treatment requires a design based on the input pH and the long-term organic decomposition rate.

Jan 1, 2002

By S. Zendejas-Mendivil, E. Pérez-Segura

The Cananea porphyry copper-deposit is the site of the second largest mining operation in Mexico. Mineralization is related to quartz-monzonite Laramide stocks that intrude volcanic and volcaniclastic Mesozoic rocks. The ore deposit is a stockwork and breccia-pipes system with Cu-Mo sulfides and pervasive quartz-sericite hydrothermal alteration. A study was made of the arsenic distribution in the mine and the ore-dressing plants. The arsenic (As) in the mine is related to a feldspathic quartz-porphyry type rock associated mainly with the breccia pipe structures (100-700 ppm As in the Veta 7 Breccia). There is vertical zoning, with As decreasing in the deepest part of the breccias. This As mineralization corresponds to a later sulfide hydrothermal stage. The concentrates are made of Cu, Fe and Mo sulfides and some minor quantities of As minerals. The most important copper minerals are chalcocite-covellite, bornite and chalcopyrite. Some of these minerals have 390-880 ppm As. The main As mineral is enargite[ [Cu2.97Fe0.06(As0.90 Sb0.01Pb0 01 )0.92 S4 051 and there are traces of stibioluzonite-luzonite I Cu, .95(Aso.4vSbu.49)0.9rfS4.07-Cu2 93(Aso.H4Sba.10)0.94S4.13] and of another stibioluzonite mineral type with substitution of As by Bi[Cu,96(Ascr,,'Sb0ccrB'OJ3jI~6S] These minerals contribute 80% of the As in the concentrates.

Jan 1, 1992

By Jenna Wundrack, Evan Thibaud

The advanced cryogenic treatment is a post-manufacturing metallurgical process that involves subjecting off-theshelf materials to extremely low temperatures, significantly improving wear resistance and reliability. These case studies explore whether the claims of Enrich Bits & Tools benefit metals and their specific in-field application to drill bits in the blasting industry. This paper reviews the application of the treatment to button drill bits for enhanced wear resistance in two operations. The first is a civil construction project with highly abrasive rock. To confirm the remarkable benefits of the treatment, a second case study was performed. This case study utilized measure-while-drilling technology in consistent rock characteristics to reduce variables in the field study.

Feb 1, 2024

By J. Driscoll

After 30 years of success, Newmont Gold Company has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East Decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East underground at the rate of 700 t/d (770 stpd) for an annual production of over 100,000 ounces. Over 70 underground miners enjoy the estimated 6-year mine life at Carlin East. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By Peter J. Conroy

Introduction Most subsidence monitoring to date has been surface monitoring to develop empirical relationships of the magnitude and extent of subsidence effects. Federal regulations are forcing a better understanding of subsidence. Empirical methods of subsidence prediction may not be adequate, since the empirical relationships may not be valid between or even within coal fields. A better understanding of the mechanics of subsidence is required in order to develop and verify analytical models. This paper presents some of the results of surface and underground monitoring in longwall faces of a coal mine. The seam thickness in these mines ranges from 5 feet to 6 feet at depths of 600 to 1100 feet.

Jan 1, 1982

By J. A. Lombardi

Innovative hard rock narrow-vein, longwall, and stope leach mining systems concepts are described and evaluated economically. The principal tool proposed for use in these systems for both mine development and production is the U.S. Bureau of Mines radial-axial splitter. The mining systems concepts are prefeasibility level costed and projected to be cost competitive for steeply dipping veins, 0.6-1.2 m wide, for horizontal tabular ores 2 m -5 m thick, and for leachable ores with greater than a 1.7:1 stripping ratio. In all of the systems the orebody, less swell, is retained underground for use as backfill.

Jan 1, 1994

By B. Pregerson, M. Gaft, J. Rabinowitz

The main phosphate minerals, apatite and francolite, are characterized by intensive selective photoluminescence, connected with impurities of Eu2+, Ce3+, V4+, Mn2+ and (UO22+ ). The non-uniform distribution of phosphate minerals in lumps makes photoluminescence sorting possible. As result, an intermediate product is recovered which is enriched by P205 and has relatively small amounts of chert, dolomite, calcite, fluorite, etc. In the case of Zin Phosphate Plant coarse rejects, for example, it is possible to separate a product enriched by francolite, practically free of chert and with a lowered calcite content. This material is suitable for flotation, with a potential 6-7 % increase yield of concentrate.

Jan 1, 1993

By Robert J. Ramsey, N. Finkelstein, Robert D. Jeppson

Introduction The Utah Copper Division of Kennecott Copper Corporation will present its contribution to the A. M. Gaudin Flotation Symposium in four parts. The first two segments will discuss briefly the historical development of the Utah Copper Division and describe the ore body. The third segment will review the facilities and operating procedures for the Utah Copper Division's newest plant, the Bonneville Concentrator. The fourth segment describes flotation process circuitry, including molybdenite recovery procedures, at the Arthur and Magna concentrators. (The Bonneville concentrator is a crushing and grinding unit and does not have its own flotation plant). 1. Historical Development Progress through change has been the key to the successful operation of the Utah Copper Division for more than 70 years. As the original low-grade copper operation, the pressures to remain competitive and profitable have dictated the timing and extent of each change. Much of the change has occurred through technological and economic advancements in the area of ore concentration. The Utah Copper Division of Kennecott Copper Corporation had its origin June 4, 1903, when the Utah Copper Company was organized. The initial mill of 300 tpd (tons per day) capacity was built at Copperton a few miles below the present Bingham Canyon mine site. From 1904 to 1910, the Copperton mill was expanded to a capacity of 1,000 tpd, and all of the known apparatus for gravity concentration were evaluated.

Jan 1, 1976

By Shulin Xu, Moreno Pescara, Nicola Avagnina, Piergiorgio Grasso

The Roreto Tunnel is a shallow, twin-bore, road tunnel on the connection between the A6 and the A21 motorway in NW Italy. The challenges faced the design and construction of this tunnel derive from 1) the presence of groundwater, both phreatic and artesian; 2) excavation in loose and/or little cohesive materials; 3) excavation in cohesive materials containing water-saturated, sand lenses; and 4) surface constraints due to the urban environment. In this paper, these problems are examined and the rationale led to the optimum design choices and construction solutions explained. The experience should be useful to others when tunneling in similar situations.

Jan 1, 2003

By S. Chatterjee, S. Bandopadhyay

A spatial modeling technique based on the Bayesian neural network (BNN) is proposed. Incorporation of the Bayesian method for posterior probability of the output parameter helps calculate the uncertainty associated with the estimate. Parameters of the BNN model were selected using a grid search algorithm. The expected value and the variance of block support were calculated by Markov chain Monte Carlo sampling of the posterior distribution at discretized points within the block. The BNN model was validated by applying it to the Walker Lake data set and comparing the results with ordinary kriging results. The comparison revealed that the proposed BNN method performs marginally better than ordinary kriging. The variance map is less smooth than with ordinary kriging, and the proportional effect is less in the BNN-based model than in the ordinary kriging model. The developed BNN model was applied to the Coho block of a placer gold deposit in Nome, AK. Results reveal that the BNN model is globally biased for the Coho block and underestimates the sample mean. The grade volume curve was developed by calculating the block mean and block variance after discretizing the block into a number of points and applying the BNN model to each discretized point.

Jan 1, 2011

By J. G. Jenkins

Magma Copper Co.'s San Manuel solvent extraction/electrowinning (SX-EW) facility has operated since May 1986. The original facility had a design capacity of 22.6 kt/a (25,000 stpy) of electrowon copper cathode produced by processing pregnant leach solution from an open pit-heap leach operation. In 1988, the plant was expanded to 45.3 kt/ a (50,000 stpy) to incorporate processing in-situ leach solutions. This pager focuses primarily on the heap leaching area with regard to exploration, testing, feasibility, permitting, design and construction, and operating practices. Research using surfactant leaching aids to enhance copper recovery is also discussed.

Jan 1, 1995

By R. G. Reddy

Viscosities of Feo-SiO2 slags were calculated using the previously developed structural based model. An expression was derived using hole theory and the atomic pair model to relate the NO0 and temperature to the viscosity. The deduced equation n=4.9x10-9 T1/2 NO0 exp (E/RT) poise was successfully applied to predict the viscosity of FeO-SiO2 slags in the composition range of 0.1 < XSiO2 < 1 for several temperatures. The calculated data agrees well with the experimental viscosity data.

Jan 1, 1991

By Ehsan Alavi, Eren Kusdogan

The City of Toronto’s Coxwell Bypass Tunnel is currently being constructed by North Tunnel Constructors ULC, a joint venture of Jay Dee Canada, C&M McNally Tunnel Constructors and Michels Canada. This project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five 20 meter diameter storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. This paper describes progress on the project to date and reviews the risk mitigation measures utilized on the project to move the project forward through tough geological conditions during shaft excavation and tunneling phase of the project.

Jun 13, 2023

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

The Mount Royal Tunnel (MRT) is a 100-year-old railway tunnel located in Montreal, Canada. The tunnel is approximately 5 km long, 8.7 m wide and 5.5 m high, with a constant 0.6% grade. This existing tunnel will be used by the new Montreal light rail transit network, Réseau Express Métropolitain (REM). This requires the tunnel to be inspected, rehabilitated and made compliant to the recent safety standards. This paper presents the details of the structural inspection and rehabilitation of the tunnel along with the repair methods, addition of a center wall as well as the enlargement of the tunnel section.

Jun 13, 2021

By Kugan Kuganathan

Pastefill is being increasingly considered as a viable fill by underground mine operators. Mount Isa Mines (MIM) chose pastefill to fill their deep copper mine (>1200m deep) after considering various other types of fill in the feasibility studies. During the development of pastefill at Mount Isa (1996 - to date) the Mining research of MIM developed two cost effective, reliable and simple testing methods and used. With the help of these tests the behaviour of MIM pastefill was studied thoroughly and the most optimum mix design for pastefill was achieved. The MIM&apos;s pastefill plant, the largest in the world with a capacity of 450rph continuous pastefill production and unique in the process used, has been built (1998-1999) to produce pastefill to the specification developed through extensive testing program using the Flow Cone and Mini Slump cone Tests. As a consequence, it is now possible to select the optimum pastefill mix designs and predict their flow behaviour in bore holes or pipe lines using only these tests. MIM Blended Tailings Pastefill (BTPF) uses 3-3.55 Portland cement and the cost of pastefill is much lower than the total tailings pastefill, that could be produced from the same tailings.

Jan 1, 2001

By Ann M. Hagni

One of the most costly factors in the production of aluminum is the consumption of energy in the form of electricity. Energy consumption is increased as refractories in the Hall-Heroult reduction cells are corroded by penetration of the fluxes cryolite (Na3AlF6) and villiaumite (NaF). To decrease thermal conductivity and refractory waste, protective barrier linings are installed. Dry powder barrier linings form stable reaction products at cell operating temperatures. Four dry powders composed of vermiculite, corundum, wollastonite, and anorthite are characterized mineralogically by X-ray diffraction, reflected light microscopy, scanning electron microscopy, and cathodoluminescence microscopy in this research project.

Jan 1, 1998

By L. Barry Phelps

Coal mine drainage, which occurs predominantly as acid mine drainage in the East, is a serious contaminant of surface and groundwater systems (Appalachian Regional Commission, 1969). Treatment of this pollutant can be very costly and is often difficult to achieve (Appalachian Regional Commission, 1969). A major source of coal mine drainage in surface waters is polluted ground- water discharge, therefore treatment of surface water does little to combat groundwater contamination. Prevention of the formation of coal mine drainage and restricting its entrance into the groundwater protects both surface and groundwater systems. The formation of acid mine drainage may be inhibited by preventing contact between toxic spoil, air, and water (Grim and Hill, 1974). This may be accomplished by surrounding toxic spoil with a relatively impermeable barrier, thus restricting groundwater and oxygen flow through the toxic zone. Toxic spoil packages constructed in this manner would minimize the entrance of acid mine drainage into the groundwater system, allowing dilution by uncontaminated water to occur. If successful, concentrations of coal mine drainage would be reduced below toxic levels.

Jan 1, 1981

By Janusz S. Laskowski

The most important type of potash ores, sylvinite, contains sylvite, halite and a small percentage of insoluble gangue [sulfates (anhydrite), carbonates (dolomite), and clay minerals]. Primary normal long-chain amines are exlusively utilized to float sylvite from halite, but since mines are also adsorbed by insoluble slimes, the process requires prior desliming. This is carried out either by mechanical means, or by flotation of slimes and blocking off the adsorption centers on clays with the use of polyelectrolytes. Fractional crystallization is employed to produce fertilizer grade KC1 from disseminated ores with a high content of slimes. An extender oil is needed in addition to mine to float coarse sylvite fractions. The process is carried out in a saturated brine at mine concentrations exceeding the solubility limit and is strongly affected by temperature fluctuations. All these important features, which make this process differ from a conventional flotation, result from a high electrolyte concentration.

Jan 1, 1994

By Jozef F. Zurawski

The paper discusses design and construction of a 1.8 meter (6 ft.) diameter tunnel installed under complex geology of Staten Island, New York. Contract T-13 is a section of the Oakwood Beach Water Pollution Control Project constructed for New York City Department of Environmental Protection. A knowledge of the subsurface conditions and difficulties experienced on the adjacent contracts called for an innovative approach to handle tunneling under 12 to 17 meters (40-55 ft.) of water in the variable subsurface conditions. This paper describes tunnel design and construction utilizing continuous grouting during advancement of tunnel boring machine and installation of liner plates.

Jan 1, 1993

By Victor Phillips

The Humphrey Preparation Plant of Christopher Coal Company, located in Monongalia County, West Virginia, was built to process the combined production of the Pursglove No. 15 and the Humphrey No. 7 Mines. Both Mines operate in the Pittsburgh Seam, primarily producing Metallurgical Fuel destined for by-product ovens in the Pittsburgh District. The results of an extensive core-drilling program have established sufficient reserves of low-sulfur coal to justify a 20,000 ton-per-day preparation plant, This is the story of the preparation phase of this combined operation. Christopher Coal Company operated the Pursglove No. 15 Mine to produce steam coal, which was prepared in a conven-

Jan 1, 1958