Search Documents

By Terry McNulty

There are many potential pitfalls in the commercialization of innovative technology, and the failures often are remembered longer than the successes, thereby serving as deterrents to subsequent attempts. Given the dependence of the mineral industry's future on effective innovation, it is essential that we understand the causes of failure. Case histories are presented and the out- comes are analyzed in terms of the driving forces for innovation and the steps taken during development. Industry's current attitude toward and capacity for technological innovation are discussed, and a methodology is suggested for predicting successful innovation.

Jan 1, 1998

By F. Gray

The industrial diamond review arrived too late for the June issue. Since the economy is showing a resurgence of strength, diamond tool consumption is similarly on the rise. Tool makers indicate that sales are picking up. They expect that 1994 will see about an 8% increase. Fabricators expect this positive trend to continue through 1995. In the industrial sector, sales of grinding wheels, honing stones, cutting tools and the like are expected to grow 5% and 8% during the next year. Users still are buying only those products necessary for "just-in-time" production cycles.

Jan 1, 1994

By Frederick W. DeVries

EPA announced, when they proposed to set a potable-water limit on cyanide, in August, 1990, that they had never encountered cyanide in a :sample of potable water, but they felt this was a sufficiently toxic and common material that it should be covered with a specification. The writer worked with both the American Mining Congress and the Aluminum Association in responding to their proposed spec. of 0.2 ppm max. of "cyanide" in· potable water. Although there are many subcategories of "cyanide", they failed to specify which type they meant.

Jan 1, 1993

By P. J. Suardini, T. E. Seppanen, M. J. Hanninen

In order to reduce the heat loading in the Tilden Mine kilns caused by burning coal, which in turn resulted in rapid and significant build-upon the kiln lining, internal carbon was added to the green ball prior to balling. Intensive laboratory testing led to three short-term full-scale plant tests that were successfully conducted. Appropriate environmental permits were obtained to allow Tilden to use internal carbon on a continuous basis. Findings concerning carbon addition rates, reductions in coal use, build-up reductions, fired pellet quality, and environmental issues will be discussed.

Jan 1, 2003

By D. A. Harman

The U.S. Environmental Protection Agency recently recognized Newmont and other mining companies, along with the Nevada Division of Environmental Protection for their voluntary work in reducing mercury air emissions. One example of this voluntary effort is the installation of a reactive scrubber to capture mercury vapor from the exhaust of a carbon regeneration kiln at Newmont’s Twin Creeks Mine. After considering the available technologies, a proprietary reactive scrubber, developed by ADA Technologies, Inc., was selected and is currently being commissioned. Mercury removal rates greater than 90% have been documented.

Jan 1, 2004

By C. J. Barbee, P. J. Bethell, C. J. Wood

Heavy medium cyclones (HMCs) are commonly used to clean run-of-mine coal in the 50 x 0.5 mm size range. Unfortunately, field studies suggest that industrial HMC circuits are often poorly designed or improperly operated, resulting in significant losses of recoverable clean coal. To assist plant engineers in overcoming these problems, a spreadsheet-based simulation package has been developed to predict HMC performance based on mathematical expressions originally developed by Wood (1990). A case study is provided to illustrate the predictive capabilities of this simulation package for an industrial HMC.

Jan 1, 2004

By Jerry L. Purswell

INTRODUCTION The principal OSHA standards dealing with tunneling activities are found in 29 CFR Part 1926. A reference for the applicable subparts which apply to tunneling is included as Appendix A. In addition, some standards from 29 CFR Part 1910 have been identified as applicable to construction and are included in the recent printing of an interim vertical standard for construction (1910/1926 Project). The remainder of this presentation will be focused on past OSHA activities to revise Subpart S of 1926, the principal subpart dealing with tunnel construction.

Jan 1, 1979

By Priscilla P. Nelson, Yousof Abd Al-Jalil, Christopher Laughton

Prediction of excavation rates is a critical element in the pre-planning of a tunnel boring machine (TBM) project. A realistic evaluation of performance expectations is needed that reflects both the knowns and unknowns of the excavation process and geologic conditions. Current planning procedures are often based on deterministic “best guess” estimations. In this paper, a probabilistic approach to performance simulation is presented that will permit rational consideration of general and project-specific uncertainties in establishing realistic performance estimates. Companion to the simulation software is a database of over 600 public-domain case histories.

Jan 1, 1999

By Romeo Jurani, Ralph Dresel, Fred Kissell, Charles Parker

This report describes actions taken to control silica dust at the Yucca Mountain Exploratory Studies Facility (ESF), a tunnel located in Southern Nevada that is part of a scientific program to determine site suitability for a potential nuclear waste repository. The rock is a volcanic tuff containing significant percentages of both quartz and cristobalite. Water use for dust control was limited because of scientific test requirements. A major dust reduction was achieved with an intermediate air cleaning station located on a rear deck of the TBM trailing gear.

Jan 1, 1999

By Frederico J. Price

This paper describes the production of a specific iron oxide pellet that has given very good and consistent results as feedstock for HYL-Process Direct Reduction Plants. The sponge iron originated from these pellets has been used for the economic making of almost 15 million tons of low carbon steel via electric arc furnace meltshops. An overview of mining, benefication, pelletizing direct reduction and steelmaking for this case is given with emphasis on the characteristics of the self-fluxing oxide pellets. HYL Operator and management training is described.

Jan 1, 1979

By M. W. Harmer, J. M. Quist

Laboratory test work, pilot plant testing and plant experience with wet, fine-mesh screens are discussed. High-frequency, low-amplitude, fine-mesh, wet screens were installed on the 6th cleaner concentrate stream. These screens produce a 60% oversize recovery split of the molybdenite concentrate that is of leached equivalent quality. The undersize stream is leached with hot ferric chloride to remove lead and copper contaminants before roasting or shipment to sulfide customers. This plant modification is a good example of using existing technology in an unconventional flow sheet to yield significant cost savings.

Jan 1, 1991

By Angelus S. C. Owili-Eger

The protection of groundwater resources is a growing issue on both the legislative front and within the private sector. At present, the legislative push is to establish within the Environmental Protection Agency a comprehensive research, development, and demonstration program relating to groundwater contamination and resources. It is evident that certain aspects of such legislation will be directed at the mining industry. Consequently, the mining industry must position itself to address the issues and concerns from a backdrop of facts and knowledge by developing an integrated hydrogeochemical model of the mining environment.

Jan 1, 1989

By Charles A. Edwards, Kenneth D. Merrill

The Construction of the Northeast Extension of the Baltimore Metro involved soft ground, compressed air tunneling. During the tunneling, gasoline and dry cleaning fluid contamination were encountered. Innovative approaches and solutions were developed to address these problems. Special emphasis was on the problem of compressed air pushing gasoline vapors into surrounding communities, resulting in an extremely dangerous situation and a public relations nightmare. Guidelines and standards were established for working in this contaminated environment. Also, through a proactive approach by all parties, all claims and disputes have been resolved.

Jan 1, 1995

By J. G. Wargo

In situ leaching of disseminate gold deposits has been studied from a theoretical perspective to outline the operating environment for the process. Rock permeability and the relationship of permeability to the site of gold particle deposition are key factors in predicting the efficiency of in situ leaching. Permeability measurements, however, have rarely been made during gold exploration, so that secondary geologic features of the deposit must be used. This paper examines some of the geologic characteristics of disseminated gold deposits and comments on the problems and possibilities of in situ leaching of gold.

Jan 1, 1987

By Fernando Concha, Arturo Barrientos, María Cristina Bustos

Manufacturers referred to high capacity thickening as a filtration operation rather than thickening in spite of the fact that it is performed in thickeners and that conventional thickeners can be operated as high capacity thickeners by changing the feeding level and operate it in a different manner. In this work we derive a phenomenological model for high capacity thickening based on mass and momentum balances. The difference with a conventional thickening is the presence of a surface source within the variable domain. The model can be used to design, simulate and to develop control strategies.

Jan 1, 1995

By Sheldon Shepherd

Fifty years ago, belt scales were mechanical devices based on a complex weight balancing design. Today's systems use load cells to assess material weight, belt speed sensors and microprocessor-based integrators to continuously compute the rate of material transferred along a conveyor. Belt scales have become important assets to a plant. They help maximize the use of raw materials, control inventories and aid in the manufacture of a consistent product. Choosing and installing a belt scale system may seem complicated but it can be simplified by following a few guidelines.

Jan 1, 1999

By N. M. Grant, W. G. Prast

Jamaica has extensive deposits of marble, gypsum, and limestone, offering prospects for commercial sales to nearby US markets, notably the Gulf Coast and Southeast. Stare-owned and private Jamaican industrial minerals producers have made limited sales to date but expect to increase exports during the balance of the 1980s. Restraints include Jamaican government controls on access to essential foreign exchange for new capital investments and distribution of profits. Jamaican efforts to identify market opportunities in the US are reviewed, and the outlook for further exports of carbonates is discussed.

Jan 1, 1987

By L. W. Saperstein, MJ. Carlson

With the goal of improving the strength characteristics of pneumatically emplaced material used for localized subsidence control, the binding additives fly ash, bentonite, and portland cement were examined for their effect on the support capabilities of coal refuse. It was found that, within certain concentration ranges, all three offered some increase in the ultimate strength of the backfilling mixture. However, portland cement gave the greatest percentage increases. Selection of the appropriate backfilling mixture will allow for the most economical and efficient subsidence control when pneumatic stowing is employed.

Jan 1, 1990

By P. W. Hunter

The construction of a major sewerage scheme requiring 15.3 km of 5.5m excavated diameter tunnel in basalt, mixed and soft ground has been undertaken by the Melbourne and Metropolitan Board of Works. A double shielded Tunnel Boring Machine was selected to excavate 13.7 km of basalt and mixed ground. Advanced methods for recording operational data on the TBM were introduced. Progress to date has shown that the TBM can excavate rock very effectively with a best weekly production of 178.8m; soft ground has been encountered and successfully handled.

Jan 1, 1987

By Antoon W. van der Vooren, Colin R. Phillips

A comparison of analytical models used to describe deposition in the first generation of lung bifurcations is presented. In order to allow testing of the mathematical models, experimental data were obtained from radon daughter deposition in simplified lung bifurcations. The experimental data for particles deposited by diffusional mechanisms is best described by the assumption of a thin concentration boundary layer at the entrance of a right circular tube. Other more complex models do not accurately describe the deposition of submicron particles. The angle of bifurcation was found to have a minor effect on deposition.

Jan 1, 1981