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By B. Moudgil, M. Bogan

A bench-top centrifuge was used to study the consolidation behavior of phosphatic clays. A mathematical model (based on, first-order kinetics) was developed to describe the relationship between the void ratio (at any time) and the effective stress. The permeability of the sediment as a function of the void ratio is also described. The results of this analysis are then compared to data obtained by other consolidation testing methods. The centrifuge results indicate that consolidation data may be developed in a short period of time (hours) as compared to days or weeks when other techniques are used.

Jan 1, 1997

By Leonard A. Eros

In many mining applications it is not practical to use gravity takeups. In these situations hydraulic takeups are often utilized. Performance specifications are often compromised by designs which have inherently high internal friction and inefficient hydraulic designs. This results in performance which does not match the requirements of the conveyor system. A computer model has been built to check unit efficiencies and field measurements have been taken which verify the results.

Jan 1, 1993

By J. Kelleher, R. Saulters, K. H. McDaniel, L. Griswold

To improve underground safety and visibility during mining applications, the Waste Isolation Pilot Plant designed and built a dry-dust filtration unit. The unit works in conjunction with a Spendrup 1120-70 fan with ventilation tubing to filter the face exhaust air during mining operations. The closed- loop system is designed to filter 17 m3/s (36,000 cfm) and is intended to screen 10- µm (1,250 mesh) and larger particles at 90% efficiency. To accomplish this, the unit uses a combination of Dollinger Staynew Inertial Spin filters, cyclones and traditional mesh filter media.

Jan 1, 2002

By K. J. Shoop, S. J. Ripke, T. C. Rao, T. C. Eisele

This study investigated the use of a 7.6-cm inside diameter, 344.2-cm-tall horizontally baffled column to reduce the ash content of a low-sulfur bituminous coal. Tests were carried out to determine how the baffled column responded to changes in feed rate, reagent dosage and feed quality. The tests were also carried out to compare the columns performance to a conventional column installation in an operating plant. In this paper, the results of this investigation are reviewed and discussed.

Jan 1, 1999

By W. K. Tolley, D. G. Kotlyar

Silver is an economically important component of many complex, massive sulfide ores. The beneficiation of this type of ore is now almost entirely accomplished by flotation. Silver recovery is often low, and little is known about the flotation behavior of the silver-bearing minerals. Floatability studies were conducted using silver-bearing tetrahedrite and lead-zinc ore. The effects of xanthate-collector concentration, conditioning time, potentiostatic control of the mineral potential and control of the pH on mineral floatability were evaluated. The floatability of the silver-bearing minerals was shown to depend on collector concentration and mineral potential. The effect of controlling the mineral potential during the flotation process is discussed.

Jan 1, 1996

By Donald W. Gentry

This article introduces mine planning as a complex process based on the quantitative and qualitative assessment of a myriad of independent and inter-or co- dependent variables. The interdependent variables of particular interest in this paper are those associated with mine planning activities that impact metallurgical processing plant performance and costs. These variables are identified and examples are provided to substantiate the argument that the magnitude and sensitivity of these variables must be formally assessed and analyzed to determine their potential impact on overall economics.

Jan 1, 1991

By Mark W. Springett

The sampling of precious metal deposits entails inherent problems due to the low mineral abundances, high mineral specific gravities, skewed grade distributions and wide ranges of mineral particle sizes. Sampling practices and precautions are discussed with particular attention to each of the tripartite stages of sampling - sample acquisition, sample preparation and sample assaying. Practical examples of approaches to the sampling problem are given and some examples of significant sources of error are provided from gold and silver deposits in North America.

Jan 1, 1992

By G. V. Basham

"Environmental audit" is a phrase that can raise the blood pressure of otherwise cool and calm corporate personnel. There is widespread concern that any organized effort to find environmental problems will do so and may result in the imposition of substantial liability against the business that engages in such activities. However, such audits can reduce rather than enhance possible liability. Relevant issues include: the role of the attorney in the process, liability risks associated with environmental audits, steps to maximize confidentiality of audit results, reporting requirements and use of audit results in a proactive manner.

Jan 1, 1995

By E. G. Kelly, D. E. Walsh

The behavior of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effects of particle size, particle shape, pulp density, feed rate and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that, with suitable precautions, the technique is capable of providing valuable information, unobtainable from conventional studies, that could be used to better optimize spiral performance.

Jan 1, 1993

By D. R. McGregor, B. V. Clingan

A practical application of recent design concepts makes it possible to design a column cell to fit a specific set of conditions. The design and operating parameters of a column cell installation that replaced a conventional two-stage copper flotation cleaning circuit at Magma Copper Co., San Manuel, AZ, using these design concepts is described. A survey of other mineral processors using column cell technology was conducted. The results of this survey are also discussed.

Jan 1, 1988

By G. D. Hood, B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the US Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1995

By L. D. Gehi, A. W. Khair, M. Ahmad

This paper presents an analysis of the effect of the dynamics of bit wear on dust generation. Two surveys have been conducted in order to assess the mechanism and type of bit wear and to evaluate the impact of bit wear on the productivity of the continuous miners. Used bits were collected from the underground coal mines and these used bits were utilized in laboratory coal cutting. The effect of bit wear on dust generation has been quantified and its impacted on dust generation and ventilation system has been exemplified.

Jan 1, 1993

By Douglas W. Fuerstenau

Technological innovation is needed to meet the challenges that face the mineral industry because ores steadily become lower in grade, more complex in mineralogy, and must be processed in the face of ever- increasing environmental constraints and increased costs. How periodic innovation in mineral processing helped overcome the challenges that faced the mineral industry is briefly traced from antiquity up to the present time.

Jan 1, 1989

By B. K. Mishra, Partha Chakroborty

Jigs are the most important equipment used in the separation process that exploits the stratification of particulate matter under the influence of hydrodynamic and gravitational forces. Very little is known about the determined mechanisms by which particles of varying density, size, and shape stratify in a moving bed. A model is developed by using the discrete element method to understand the behavior of jig bed. This model is utilized here to study the stratification behavior of the bed and its control. The control action is based on the understanding of the physics of the stratification process within the framework of fuzzy logic. The actions suggested by the fuzzy logic controller (FLC) depend on the current degree of stratification and the existing frequency of the jig cycle. The results show that the FLC achieves efficiency in stratification with minor variations to the jig cycle.

Jan 1, 1995

By John Reynolds, Robert Sloan

The Escondida copper mine is located in the northern Atacama Desert of Chile at an elevation of 3,050 m. approximately 160 km southeast of the port of Antofagasta. The mine is a joint venture between BHP-Billiton, Rio Tinto, a Japanese consortium and the International Finance Corporation. The most recent expansion, Laguna Seca, has increased the total capacity to the level of 220,000t/d ore throughput. The ore body, a typical porphyry deposit, is situated on the major Chilean west fissure fault system and contains primary sulphide ore grades between 0.6% and 2.0% copper. Primary sulphide mineralization consists of chalcocite pyrite, chalocopyrite, bornite and covellite. Significant copper oxides overly the sulphides in many areas.

Jan 1, 2005

By J. R. England, W. J. Taylor

The Sudbury Basin is the scene of the mining operations of the Ontario Division of the International Nickel Company of Canada, Limited. Around the rim of the geological formation and within thirty miles of the City of Sudbury are located twelve operating mines and one open pit operated by the Company. The City, with a metropolitan population of some 100,000 lies 240 miles Northwest of Toronto. In addition, there is one mine in Northwestern Ontario, at Shebandowan, 700 miles Northwest of Sudbury. In 1973 these mines produced 16.5 million short tons of ore of which 14.9 million tons were from underground and the balance from open pit operations. Mining methods include blasthole, sublevel caving, induced caving, shrinkage, cut-and-fill and undercut-and-fill. Raise boring commenced at Inco in 1964 and is now applied at all mines in the Sudbury District (Figure 1). [ ]

Jan 1, 1974

By P. K. Chatterjee

Before coal can be extracted from surface or underground mines, approval must be obtained from state and federal authorities. Permitting is the application process through which such approval is sought. The application includes en environmental impact statement Which focuses on Such topics as subsidence, toxicity of acid mine drainage, pollution levels of rivers and streams, post mining reclamation, and the effect on the hydrological balance of the area. The permitting procedure is extremely time and labor intensive, and requires extensive interdisciplinary knowledge. This paper examines a LISP based permitting procedure which will help to reduce the time taken to prepare and review a permit application.

Jan 1, 1986

The importance of factoring mining dilution into the estimation of ore reserves in an open pit mine is discussed. An example that relates the issue of mining dilution to the size of the smallest volumes that can be mined selectively is given. The relationship between the size of the selective mining units (SMUs) and the variance of their average grade is presented. The concept of variance reduction and its use in factoring mining dilution into geostatistical ore reserve estimation is described. An approach to estimate a variance reduction factor by way of conditional simulation is introduced.

Jan 1, 1998

By D. Doepker

The dissolution of metals from various metal/ non-metal mine tailings has been studied through column leach tests at US Bureau of Mines laboratories. Metal mobilization in unsaturated columns was consistently greater than metal dissolution in water-saturated columns. Leachate pH was also frequently lower when a leachant was passed through columns but showed a mixed residence-time dependence. On the other hand, metal and sulfate ion concentrations in the leachate increased with dry-cycle residence time. Results suggest that acid formation through atmospheric oxidation of pyrite may compete with non-acid-forming oxidation of other metal sulfides. The two processes lead to decreased pH and increased metal mobilization, respectively. Leach tests using sodium lauryl sulfate indicated that microbial activity was not a factor in these studies.

Jan 1, 1991

By R. D. Hagni, R. T. Brandom

An ore microscopic study of the Boss-Bixby, Missouri, copper-iron deposit has shown that the mineralization formed as a simple sequence of oxides followed by cobaltian sulfides, copper-iron sulfides, and then oxides. The hypogene ore minerals found by this study are magnetite, hematite, ilmenite, rutile, chalcopyrite, bornite, covellite, cobaltian pyrite, carrollite, sphalerite, clausthalite, galena, electrum, scheelite, wolframite, and a Pb-Bi-Se-Te mineral. Textural evidence indicates that some of the early oxides were original constituents of the host syenites and oxidized during cooling. The remainder of the mineralization formed as breccia fillings and replacements. Subsequent partial oxidation has formed martite, covellite, rutile, and anatase.

Jan 1, 1987