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By J. M. Pugliese

The U.S. Bureau of Mines is developing designs and estimating costs for vertical in situ copper mining wells as part of its in situ mining research program. Conceptual designs and estimated costs for "deep" 1100 m (3600 ft) recovery and injection wells in an undisturbed copper ore zone are presented. Within a single in situ copper mining well, multiple perforated well completions and associated costs are discussed for two ore zones between depths of 370 m (1200 ft) and 550 m (1800 ft). The order of well specifications for designing these wells is explained.

Jan 1, 1995

By John C. Balla

The Troy deposit is located in northwestern Montana, approximately 17 mi south of Troy. The deposit is a stratiform, strata- bound, copper-silver deposit which occurs in the Revett formation of the Proterozoic Belt Supergroup. The Revett formation is approximately 1730 ft thick in the vicinity of the Troy deposit, and is divisible into three units. The upper Revett, approximately 250 ft thick, is the host for the orebody. The Revett represents a deltaic environment. The Troy deposit was discovered by Bear Creek Mining Company in 1 963 during the course of a reconnaissance stream sediment sampling program that was designed to discover strata-bound copper deposits. The deposit is approximately 7500 ft long, 1800 ft wide, and averages 60 ft thick. It is bounded on the north by outcrop, on the east by a post-mineral fault, on the south by diminishing grade and post-mineral faults, and on the west by diminishing grade. Ore reserves are 64 million tons with a grade of 0.76% Cu and 1.58 oz Ag per ton. The mine is presently operating at a production rate of 4.2 million oz of silver and 20,000 tons of copper per year.

Jan 1, 2013

By R. E. Miller

Hoisting coal using water and air is a technology which has potential to improve the economics and safety of transporting coal. The Coal Air-Lift Hydrohoist is a prototype coal hoisting system developed by the U.S. Bureau of Mines (USBM). This paper discusses the method used to regulate the supply of water to the 50-m-high hydrohoist U-tube such that the pressure difference at the bottom of the U-tube is held constant. Maintaining a constant pressure difference results in a steady flow of slurry out of the hydrohoist.

Jan 1, 1995

By E. J. Beckman, R. M. Enick, C. Powell

Liquid carbon dioxide can be used as a replacement for organic solvents in the extraction of anionic platinum group metal complexes from an aqueous phase. However, because conventional extractant-metal complexes are not soluble in liquid carbon dioxide, this can be achieved only if highly carbon dioxide-soluble extractants are developed. For example, trioctylamine-gold chloride is not soluble in liquid carbon dioxide, although trioctylamine is CO2 soluble. The novel CO2-soluble extractants presented in this paper have a CO2-philic fluorinated tail to enhance solubility and a conventional amine head group for extraction of metals. Both the extractant and the extractant-metal complex are soluble at ambient temperature at pressures from 7 to 35 MPa. Efficiency factors as high as 2.23 have been measured using 1,1,2-trichlorotrifluoroethane (TCTFE), a low pressure screening liquid for carbon dioxide, indicating that these compounds will strongly bind the metal chloride. For example, 84% of Pt-chloride was extracted into TCTFE using a 3.5:1 ratio of a double¬tailed fluoroalkyl amine extractant: metal chloride. An 88% recovery of Pt-chloride into high-pressure liquid carbon dioxide was achieved using the same extractant at a 3.5:1 ratio. Therefore, it appears possible to replace organic solvents with liquid carbon dioxide during the extraction of platinum chlorides if highly carbon dioxide-soluble extractants agents are employed.

Jan 1, 2002

By N. Edmonson

Frasch sulfur production/pricing decisions are based on market demand, less nondiscretionary sulfur supply. Price covers the cost of Frasch production and byproduct sellers accept the Frasch price structure. Large stocks have led Canadian byproduct producers to price aggressively at times, but their near-term drawdown suggests more passive price policies in the 1990s. Expanding continental nondiscretionary supply is combining with sizable Frasch supply increments to weaken prices. Simulations using a market model embodying these structural characteristics indicate that expanding demand may not result in substantial recovery from 1992 price lows before 1996.

Jan 1, 1995

By A. L. Mular

Se revisan brevemente varios procedimientos para el cálculo de coste de capital; no obstante, se discute en preferencia el método del factor estimado. Se proporciona una tabla de costes frente a los datos de parámetros de equipo, de donde los costes pueden ser adaptados a partir de los valores actuales de los índices de costes M&S para minería y molienda. Las ecuaciones de costes son utiles para preparar los programas de computador que realizan cálculos de coste de capital. Se ilustra la utilización del metodo del factor estimado.

Jan 1, 1982

By Joseph Peterson, Alexander May

The Bureau of Mines used geochemical modelling computer programs to characterize a site containing lead slag generated by a lead processing facility. Tests for toxic elements by the U. S. Environmental Protection Agency (EPA) extraction procedure showed that all elements except lead were in compliance. Concentrations for lead ranged from 28 to 30 ppm. However, analysis of water samples from monitoring wells resulted in no lead concentrations that exceeded the National Drinking Water Standard. A discussion of a computational program to calculate concentrations of lead species and several other ions is presented.

Jan 1, 1991

By Paul Grisley

Air-supported belt conveyors-conveying systems that replace troughing idlers with a film of air-were a revolutionary concept when introduced in the 1970s. But high installation and operating costs limited their application. Now, system refinements have led to successful applications, even under the challenging conditions of mines and process plants. In this presentation the author will discuss the latest developments in the engineering of these systems, including the ability to retrofit existing transfer points with modular air conveyor components. Air conveyor applications and limitations in mineral-handling operations will also be examined.

Jan 1, 2002

By Milton E. Wadsworth, M. Ken Han

The kinetics of leaching of galena in hydrochloric acid solutions with sulfur dioxide gas have been investigated experimentally. The leaching method is then applied to complex sulfide concentrates to evaluate its selective leaching capability and to develop a new hydrometallurgical lead extraction process based upon the method. The leaching reaction follows a linear rate with an activation energy of 61.9,KJ/mole. The rate Is of first order with respect to the product [H+] [Cl-] . Excel lent selective leaching capability f s demonstrated and an attractive hydrometallurgical process flow sheet is proposed.

Jan 1, 1989

By Thomas W. Camm

The U.S. Bureau of Mines has extensive experience estimating the cost of mining and mineral processing operations as an ongoing part of its information and analysis studies. With the increased interest in remediation of mine wastes, the USBM is developing a methodology to expand its cost estimating expertise to include costs of various remediation techniques applicable to mineral processing and mining wastes. By integrating waste remediation costs with existing USBM cost estimating systems for mine and mill operations, a comprehensive system for cost engineering studies will be developed.

Jan 1, 1995

By J. Andrew Leach, Robert T. Tape, Thomas G. Harper

A practical approach to elope stability design of heap leaches up to 90 m (300 ft) high is presented based on recent experiences with heaps throughout the Western U.S. Shear strength parameters for foundations, ore and liner systems are considered, with particular attention given to frictional contacts between geomembranes and clay or geotextiles. Stability of both ore and containment dikes is discussed including the effects of seismicity, staged dike construction, progressive heap development and in-heap solution levels. Design criteria and methods of analyses are presented along with techniques for improving stability.

Jan 1, 1987

By B. Dabrowski, J. D. Miller, D. Halbe, J. Hupka

An air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was removed from the gas phase in a single one second pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than 10 ppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry’s Law constant, exceeded 40% in one pass.

Jan 1, 2004

By Sangwhui Cho

In comminution processes including crushing, grinding and pulverizing, the efficiency of the comminution system is very low. Since the early 1980s, research has been conducted to increase the efficiency of pulverizing mills. Additionally, the application of microprocessors and Personal Computers to process control have come into general use. Given appropriate models of the process and control algorithms, these systems can economically control comminution processes. The ring-roller type mineral pulverizer is known as an energy saving mill. In this study, a control strategy to increase the efficiency of this type mill is explained.

Jan 1, 1992

By J. S. Lindsey, E. E. Jones

Dow Chemical Co.'s research in lignite gasification has required that the fuel be upgraded in terms of ash loading and the slagging character of the residual ash. Lignite beneficiation has been shown to substantially reduce the total ash loading and, in some cases, causes very significant reductions in slag viscosity. In support of this work, a slag viscometer was constructed and the viscous flow properties of lignite ash were run as a function of temperature and composition. The flow as a function of temperature was shown to be predictable from the chemical composition.

Jan 1, 1988

By E. W. Hawk

he power generation industry may be required to reduce carbon dioxide (C02) emissions if regulations related to global climate change are enacted. Coal-fired generation emits more than 80% of the power sector CO2 and would be a likely target for CO2 reductions. Compliance with the Kyoto Protocol will require a 33% reduction from the projected year 2012 emission level, even with moderate load growth. This article describes an analysis of power industry CO2 reduction options and their costs. It assesses how a generator would make compliance decisions under a mandatory CO2 emissions reduction program. Carbon sequestration, fuel switching and new plant construction are considered. The Global Climate Change Treaty signed at the Rio de Janiero Earth Summit in June 1992 set the long-term goal of stabilizing CO2 concentration in the atmosphere. The December 1997 Kyoto Protocol established short-term mandatory targets for the United States and 37 other developed countries. The United States' target is a 7% decrease by 2012 from the 1990 "greenhouse gas" level. Developing countries are exempted from reductions, according to the Kyoto Protocol, despite projections that indicate a significant increase in their emission levels. The Kyoto Protocol must be ratified by the US Senate. US power industry carbon emissions were 490 Mt (540 million st) in 1990 and are projected to be 680 Mt (749 million st) in 2012, according to the US Energy Information Administration. Coal-fired generation emits more than 80% of the power sector CO2. Assuming that the power industry is only required to reduce emissions by a proportional share, a 33% emission reduction, or 225 Mt (248 million st) of carbon, would be required to comply with

Jan 1, 1999

By David M. Sullivan

Jim Walter Resources, Inc., (JWR) a division of Jim Walter Corporation, has 5 underground coal mines in Central Alabama varying in depths from 400-2500 feet. Gas Chromatography plays a vital role in safety and production at each mine. Chromatographic data is used to monitor working areas for safety and proper ventilation and to control the quality of extracted methane for sales purposes. Instruments have a1 so been employed during mine rescue operations. JWR's first Gas Chromatograph (GC) was installed in April 1984 to monitor gob gas taken from longwall gob areas and sold based upon BTU value. The GC allows maximum extraction rate of the gas within the quality guidelines. By late 1985, another system was purchased and both units were upgraded to perform an analysis of indicator gases which may appear during mine emergencies. Each unit has the ability to detect and measure the following gases at almost any level ; Oxygen (021, Nitrogen (N2), Methane (CH4), Carbon Dioxide (C02), Hydrogen (HZ), Carbon Monoxide (CO) , Ethylene (C2H4), Ethane (C2H61, Acetylene (C2H2) and a composite of hydrocarbon threes and above (C3+). The analytical run is accomplished in less than ten minutes and is completely automated. This report will introduce Gas Chromatography as applied by Jim Walter Resources for the analysis of underground mine air.

Jan 1, 1987

By M. Quamrul Ahsan, Andrew Griffiths, Edward P. Jucevic

Heap leaching of precious metal ores using the cyanide process is extensively used in the Western U.S.A. for extracting gold. Consequently, the impact of cyanide in the spent heap is closely examined by environmental agencies and permitting authorities. Currently, many states require that all decomnissioned heaps be detoxified before abandonment. This paper describes a case study for detoxification of spent heaps at the ACH-Dayton Project using hydrogen peroxide. The chemistry of cyanide detoxification by hydrogen peroxide, together with simplicity of a detoxification operation, is discussed.

Jan 1, 1989

By O. Ozcan, J. D. Miller, Z. S. Nickolov

The production of soda ash from trona (sodium sesquicarbonate, Na2CO3•NaHCO3•2H2O) resources has completely displaced the production of synthetic soda ash in the USA. Further, the utilization of other trona resources is under consideration in China, Turkey, etc. Recent research has been concerned with the development of flotation technology for the trona industry. In this regard studies on the flotation behavior of sodium carbonate salts: trona, sodium carbonate monohydrate and decahydrate, as well as the flotation behavior of sodium bicarbonate, are reported for both cationic (dodecyl ammonium hydrochloride) and anionic (sodium dodecyl sulfate) collectors. It has been found that strong flotation of sodium bicarbonate (NaHCO3) can be achieved with 100% recovery, while the other sodium carbonate salts do not float well. These results have been explained by FTIR analysis of aqueous solutions of Na2CO3and NaHCO3in a range of concentrations from very dilute to saturated conditions. The changes in the shape of the O-H stretching band of water are correlated with the flotation behavior of Na2CO3salts and NaHCO3. In addition, the absorption band of the carbonate ion at ca. 1385 cm-1is used to monitor its interactions with water and/or other ions in solution. The infrared results demonstrate thatNa2CO3acts as a water structure maker, leading to an extensively hydrated surface that accounts for the poor flotation of most sodium carbonate salts. In contrast, NaHCO3does not have this characteristic and consequently complete flotation is possible with both cationic and anionic collectors. These results support the previous water structure analysis for soluble salt flotation of alkali halides and other oxyanion salts.

Jan 1, 2003

By K. Nagata, T. Kawashima, S. Tejima

The expanding volume of maritime coal transportation is intensifying the problems concerning large vessel service, port construction, trans-shipment, and environmental control. The major problem is the shipment of coal. Customary methods for bulk transfer must be improved and new systems developed. Slurry unloading has a key role in the new systems. This report reviews progress in slurry transportation research that has been done in Japan since the 1960s, when large-scale experiments for domestic transportation were done. Experiments on the effects of vibration on the slurry cargo and on reslurrying are focused on.

Jan 1, 1987

By Iwao Iwasaki

Since the oil crises in the 1970s, the mining industry in the developed countries has faced strong competition from developing countries. In order for the North American iron ore industry to remain competitive with high-grade overseas sources, research on low-cost beneficiation methods that ensure high-quality and uniform-quality products must be maintained in order to prepare for ever-tightening specifications on iron making raw materials for blast furnaces and also for the future iron- and steelmaking processes that can directly utilize finely ground concentrates.

Jan 1, 1999