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By Mark L. Matthews

In 1978, Congress enacted Public Law 95-604, the "Uranium Mill Tailings Radiation Control Act of 1978." The Act authorizes the Department of Energy to stabilize and control the tailings from designated inactive uranium mill tailings sites in a safe and environmentally acceptable manner. DOE has established the Uranium Mill Tailings Remedial Actions (UMTRA) Project Office to implement, in cooperation with the affected States, Indian tribes and owners of the sites, remedial actions at the sites. The UMTRA Project Office has initiated efforts to perform remedial actions in accordance with EPA cleanup standards.

Jan 1, 1981

By P. Marcheselli, Jean-Yves Peron

A twin tube tunnel of 2 000 meters long and an internal diameter of 6.90 m has been excavated through alluvial ground, with low overburden, using a 8.0 m diameter Earth Pressure Balanced tunneling machine with foam injection and extruded concrete behind segment.

Jan 1, 1995

By Michael C. Montoya, Craig Hopper

It has been well established that the ability to soft start a conveyor will give many benefits to the conveyor user. The effects of deceleration on belt tension have not been as extensively studied. This paper presents the findings of field measurements on the belt tension of a conveyor undergoing various rates of deceleration. The control of conveyor drive motors by Variable Frequency Drives (VFDs) allows the conveyor to be controlled during both acceleration and deceleration. The conveyor is allowed to ramp to a stop without putting unnecessary stress on the belt or conveyor structure.

Jan 1, 2000

By Mark J. Schultz, William J. Francart, Michael P. Snyder

The Pittsburgh Safety and Health Technology Center surveyed MSHA Coal Mine Safety and Health Districts to monitor the implementation of computer based atmospheric monitoring systems (AMS) in underground coal mines. This survey was first completed in 1984, and has been periodically updated with the latest update completed in 1995. The utilization of computer based monitoring systems has steadily increased over the past 12 years, with over 16 percent of all producing underground coal mines using this technology in 1995. This paper discusses the results of the MSHA 1995 AMS Survey.

Jan 1, 1997

By T. Altman

Using theory of network planning together with graph theory, an algorithm is presented that creates canonical diagrams for mine ventilation networks (M VN). The data generated by the algorithm is used in the construction and plotting phases of a program that automatically plots the canonical diagrams, which can then be used for further studies of a given MVN.

Jan 1, 1988

By Dennis A. Beiter, William J. Francart

Barometric pressure changes have been an important consideration in the sealing of mines, especially in the case of mine fires. These changes are caused by storm fronts and regularly, on a daily basis, by atmospheric heating and cooling. In many cases, anticipation of these fluctuations in a mine sealing operation or recovery can be an important consideration when scheduling activities. The barometric pressure changes create pressure differentials across sealed areas, inducing airflows which may create explosive mixtures of mine gasses, cause intensification of fires, and create irrespirable atmospheres outby seals. These effects of barometric pressure fluctuations on mine fire sealing and recovery operations are discussed. Data available from the National Weather Service is also discussed as a tool for predicting barometric pressure changes.

Jan 1, 1997

By D. J. Barratt

The specification of the prime mover of an autogenous-semiautogenous mill involves an analysis of the likely operating conditions within the mill and the choice of a nominal operating speed. For variable speed mills, the operating range for mill speed has to be defined so that mils power-torque requirement can be matched by the motor power-torque capability. This paper describes how thin relationship can be influenced by ore grindability.

Jan 1, 1995

By J. M. Keane, C. K. Chase

Critical to successful dump and heap leaching of copper is an adequate evaluation of applicable parameters. This paper deals with methods to establish optimum conditions for dump and heap leaching copper so that commercial operations can proceed. Discussion is also offered of ore occurrences and preparations for dump or heap leaching.

Jan 1, 1988

By G. J. Koons, J. L. Uhrie

Field density studies carried out at the Phelps Dodge Chino Mine have found that truck-induced compaction is limited to the upper 2.4 m (8 ft) of an individual lift. Hydraulic properties of material compacted to field densities were determined in a laboratory setting. Saturated flow models were then run, simulating the effect of compacted zones within a stockpile. Modeling shows that compaction can prevent solution flow through large portions of the stockpile. This implies that care must be taken to ensure that ripping is carried out to a depth of at least 2.4 m (8 ft) across the entire stockpile to achieve uniform solution flow. Uniform solution flow will result in maximum leach recovery.

Jan 1, 2002

By S. O. Moshier, L. S. Barron, J. C. Hower

The Hardgrove grindability test, commonly used in coal characterization, was conducted on 13 Mississippian carbonates from Kentucky, Tennessee and Illinois. The results demonstrated that the grindability increases with a decrease in the Si02/(MgCO3+CaCO3) ratio, with fine-grained and petrographically-complex stones having lower grindabilities. Also, the relationship between the Bond work index and Hardgrove grindability is significant.

Jan 1, 1993

By R. K. Davey

Subsequent to the determination of an ultimate pit and ore reserves for metallic and nonmetallic deposits, it is necessary to develop the most profitable long-range mining sequence for the deposit. Long-range planning is a dynamic process because product prices and costs change, additional assay and metallurgical data become available, mining technology and operating prices and requirements change. The three case studies included in this subsection present different techniques for dealing with the objectives of long-range planning. To be able to forecast production, profitability, and capital requirements, it is essential to have a long-range mining plan.

Jan 1, 1979

By Gary S. Brierley, John W. Critchfield

This paper is a case history of a subsurface exploration program conducted for a system of sewer tunnels in upstate New York. The focus of the discussion is a non-technical outline of how the exploration process was organized to efficiently produce a large body of geological and geotechnical data. A brief description of the project and geological setting is provided, the scope of the exploration program is summarized, the logistics of collecting, processing and reporting subsurface data is outlined, and recommendations for management of explorations applicable to any rock tunnel are provided.

Jan 1, 1983

By D. Zaharaki

In the present experimental study the geochemical stability of inorganic polymers was studied by immersing them in various solutions (distilled water, seawater and 0.5N HCl) for a period of 7 months. Inorganic polymers were synthesised by mixing ferronickel slag with kaolinite, potassium hydroxide and sodium silicate solution. The cement like paste was heated at 80 °C for 48 hours and left for curing at room temperature. Their structural integrity was assessed by compressive strength testing after subjection to freeze-thaw cycles as well as high temperature heating. XRD studies were carried out in order to identify new formed phases and provide useful information regarding the progress of the mechanisms involved.

Jan 1, 2008

By A. F. Raschenko, V. V. Elschin, Y. E. Golodnov

Kinetics and mechanism of gold and silver sorption from thiocarbamide solutions by activated carbon were studies using tne method of equilibrium-kinetic analysis. The intradiffusonal character of the process was determined and the kinetic and thermodynamic constants were calculated. The electrostatic component of the adsorption interaction was estimated by the electro - chemical investigations. The optimal parameters of the desorption of noble metals thiocarbamide complexes were determined. The intensification of gold and silver desorption process is reached through the use of activating additions to the eluent and electro - chemical polarization of activated carbon. Methods for complex and selective extractions of gold and silver from thiocarbamide solutions and pulps by activated carbons were developed.

Jan 1, 1995

By D. H. Y. Tang, S. S. Peng

Three-dimensional finite element modeling (3-D FEM) was performed to analyze the safety factors of stump pillars, 5.5 m x 5.5 m, under a cover of 63 m using the Modified Drucker-Prager Theory. The results showed that they were safe. This was substantiated by underground observations. But the safety factors predicted by three commonly used pillar design formulae showed otherwise. This paper discusses the modeling details and analyzes the difference between 3-D FEM method and traditional pillar design formulae.

Jan 1, 1987

By M. Gaft, G. Panczer

Sedimentary francolite and magmatic apatite are characterized by specific laser-induced time- resolved luminescence, which allows phosphate to be distinguished from accompanying dolomite. The "selective window" parameters are: he, = 337 nm, delay time after laser pulse is 0.5-5 ps, and detection spectral range is 400-525 nm. In the case of nonuniform distribution of phosphate minerals, it makes it possible to accomplish lasero- luminescent sorting and to receive intermediate product with a lowered dolomite contents.

Jan 1, 1999

The first of this two part series takes a look at some of the history and types of flotation as well as agents and mechanisms involved in it. Part two, next month, will examine flotation processes as applied to various sulfide and nonsulfide mineral ores. Flotation-"froth" flotation-is a physicochemical method of concentrating finely ground ores. The process involves chemical treatment of an ore pulp to create conditions favorable for the attachment of predetermined mineral particles to air bubbles. The air bubbles carry the selected minerals to the surface of the pulp, there forming a stabilized froth that is skimmed off and from which the predetermined mineral particles are recovered. Other minerals remain submerged in the pulp.

Jan 3, 1982

By Patrick R. Taylor

The hydrometallurgical fundamentals review did not arrive in time for publication in the May issue. Papers presented at the SME Annual Meeting, in Phoenix, AZ were available as preprints. The EPD Congress 1992 from The Metallurgical Society had several papers related to hydrometallurgy. Minerals Engineering 1992 was published in Minerals Engineering and contains several papers related to hydrometallurgy. In addition, a conference was held to honor Ernie Peters. The proceedings contains a large number of hydrometallurgy papers. Precious metals Gold extraction in the potassium cyanide-primene JMT sulfate-Xylene system was studied by Caravaca and Alguacil (Hydrometallurgy). Adams, Friedl and Wagner presented results on the mechanism of gold cyanide adsorption onto activated carbon (Hydrometallurgy). Adams also studied the adsorption of silver cyanide and used an IR method to evaluate adsorbed aurocyanide species on activated carbon (Hydrometallurgy).

Jan 1, 1993

By Dirk Timmerman, Klaus Schönert

This paper reports on the results of research on counter flow classification of - 10 µm particles. Two classifiers were designed and constructed, the first semicontinuous and the second fully continuous. The latest version operates continuously with recoveries of fines up to 90% at feed loads of 30 vol.%, separation sharpness X25/x75 up to 0.83, without bypass and cut sizes down to 1.4 µm (x50 from separation efficiency curve).

Jan 1, 1995

By Richard Gertsch

In the operation of this mobile-modular system, inexpensive fiberglass charcoal columns are loaded with gold at strategically-located adsorption stations. The loaded columns are then shipped to a centralized stripping facility. After stripping, the columns are returned to the adsorption station. The advantages of this system are as follows: •Easy scale up from pilot plant to full production. •Low capital and operational costs. •Gold production quickly reacts to changes in ore production. •The solution circuits are simple and easy to maintain. •Charcoal damage is greatly reduced.

Jan 1, 1996