Search Documents

By H. M. Breza

Recovery of phosphate concentrate at Texasgulf’s Aurora Mine has received increased attention as existing mine and plant production capacity limits are reached. Improved mining techniques and mineral processing of waste streams offer the potential to increase phosphate production without major expansion. Innovative processes are being identified to maximize pit mining recovery and to minimize waste stream losses. This results in more effective use of the phosphate. Texasgulf Inc., is a wholly owned subsidiary of Elf Aquitaine. The Aurora phosphate rock mine and refining facilities are located in North Carolina on the south shore of the Pamlico Sound. Phosphate ore is recovered by open- cast mining techniques. Draglines and other earthmoving equipment are used to uncover and mine the phosphate ore. The mined ore then is slurried and pumped about 8 km (5 miles) to the processing plant.

Jan 1, 1994

By Robert D. Gibson, E. Donald McKay, Paul B. DuMontelle

Subsidence of the land surface in some parts of Illinois is caused by underground coal mining. The U.S. Bureau of Mines is backfilling abandoned mines at selected sites in southwestern Illinois in an attempt to support failing mine openings. The Illinois State Geological Survey assists the Bureau by developing geologic and engineering information. As part of this investigation, television probes of fifteen injection borings in Belleville augmented conventional methods of study. The television probes of uncased sections of borings revealed several phenomena. Water erosion caused shale beds to slough, which partially filled some borings. Fractures caused by subsidence were identified, and excellent views of underground mine workings provided documentation of the mining method. The condition of mine timber was evaluated. Pack walls supported some openings. Both floor heave and roof fall were observed to be causes of failure in the mines.

Jan 1, 1982

By Don Minard

Management support systems are extremely important to mining management to enable them to operate their company as a business. Management must give attention to the financial, maintenance, materials, and other reporting and control systems that are necessary to successfully operate a mining company. This subsection describes the management support systems that are critical to most mining companies. In this introductory review, the major objectives and functions of these management support systems will be introduced. The following topics will expand on the functions and key concepts as well as other considerations in each of these systems areas. Additionally, this introductory review will touch upon the unique environment that mining companies find themselves in from a management and personnel standpoint and the effect of this environment on management systems. Additionally, specific keys to successful systems installations and acceptance in the mining industry are discussed.

Jan 1, 1979

By Denis M. Riley, Neville C. Lockhart, Bruce A. Firth

The potential use of the Kelsey Centrifugal Jig to clean fine coal has been studied. It was found capable of cleaning coal at very fine sizes, at least to 0.038 mm at relative densities as low as 1.6. This effect was however very dependent upon the solids feed rate and the absence of significant amounts of clay slimes. Comparisons with a spiral and a laboratory scale Jameson Flotation Cell were made. The concept of recleaning spiral product was investigated. Use of a spiral to reclean the coarse fraction, and a centrifugal jig or flotation to treat the fine fraction, gave significant improvements in final ash values over spiral recleaning of the full size. Future R&D needs include improving feed rate capacity, and application to problems like pyrite removal that are difficult to solve via flotation.

Jan 1, 1995

By L. Piga, G. Belardi, V. Alesse, N. Shehu, J. Freund

The physico-chemical interactions among minerals such as olivine, chromite and serpentine; the most commonly present ions in solution such as Ca and Mg; and flotation reagents such as EDTA and oleic acid were investigated. The study was conducted via release tests, electrophoretic measurements and microflotation of selected minerals coming from the Kukes deposit in Albania. The results were confirmed in beneficiation tests on two ores, one from the Kukes (Kalimash) deposit and the other from the Rizo deposit in Greece. It was demonstrated that, when Na-oleate is used as collector, chromite, olivine and serpentine can be separated at pH 2.5 and/or pH 5.5 when employing ethylenediamine tetraacetate (EDTA) on previously deslimed material. This approach ensures flotation concentrates with a Cr203 content better than 50% with a recovery of more than 75%.

Jan 1, 1998

By R. L. Guerguerian

Critical fasteners are described as they apply to the specification, manufacture and assembly on large grinding mill bolted joints. The importance of adequate design methods, related joint diagrams and pivot analyses, with special emphasis on the quality of manufacturing and the tightening of procedures in the field, are discussed in an effort to ensure high availability plant operation.

Jan 1, 2003

By J. Changsheng, Z. Youdi

Based on the criteria of maximum net present value per ton of reserves and on the optimum matching of some other essential parameters, a comprehensive optimization model of surface-mine production rate is developed using system- engineering approaches and using the theory of economy of scale. A mine is then selected to demonstrate the application of the model.

Jan 1, 2000

By David E. Thompson, Edward S. Plotkin

The Massachusetts Bay Transportation Authority (MBTA) Red Line Extension Northwest is nearing the final stages of construction. The 3. 1 mile extension of the Red Line from the existing Harvard Square Station in Cambridge, Massachusetts to Alewife Brook Parkway in Cambridge, includes a large, near surface, hard rock, rapid transit chamber at Porter Square in Cambridge (Figure 1).

Jan 1, 1983

By Jerry C. Tien

This paper investigated the airflow pattern in the working face area during a cross-cut development. The study used a 10:l scale face model and a mock continuous miner. Results showed that keeping up the line curtain is essential in order to avoid recirculation and to control respirable dust and methane, in the face area.

Jan 1, 1989

By P. D. Tomlingson

Senior mining mangers that do not get directly involved in the quality of maintenance performance risk the profitability of their operations. Maintenance is not a stand-alone activity. It requires a production strategy that addresses the total life cycle of equipment from procurement to replacement and assures the fully cooperative, mutually supporting interaction of all mine departments. Only senior managers can assure this happens. This paper examines the strategies, policies and actions required to establish and sustain effective maintenance and the profitability that derives from it.

Jan 1, 2004

By S. Behl

In the selective flocculation process, polymers with specific functional groups can yield highly selective adsorption and, therefore, high separation efficiency. Selectivity in polymer adsorption may also be attained by specific additives that inhibit the adsorption of the flocculant on some solid surfaces but not on others. Generally, these additives have a different chemical nature than the flocculant. In this study, the lower molecular weight fraction of the flocculant was successfully evaluated as a site blocking agent, leading to higher separation efficiency than obtained otherwise.

Jan 1, 1993

By R. J. McGregor, Deepak Malhotra

Engineers frequently encounter situations where decisions that are counterintuitive to the logically trained engineering mind are made because of other influences, whether they be financial, social, cultural, or environmental. Such influences can overrule the "logical" decision-making process. The aim of this book is to explore some of the nontechnical issues, which most engineers don't learn about in school, that can have a major impact in the mining industry. This chapter gives a brief overview of this volume and introduces the topics that will be addressed.

Jan 1, 2001

By L. D. Bowerman

The topic of the presentation will be the excavation of 25,000 IF, 11-foot 0-inch diameter, hard rock tunnel using a Robbins boring machine on the Terror Lake Hydroelectric Project on Kodiak Island, Alaska. This tunnel was completed on a tight construction schedule under some unusual conditions. The tunnel was mined through hard massive granite with faults and high water flows up to 7,000 GPM encountered at the heading in some areas. New innovations in equipment and cutter design were used.

Jan 1, 1985

By Jon Y. Kaneshiro, Blake D. Rothfuss, Gregory E. Korbin

A critical aspect of the planning, investigation, design, and construction of an underground excavation project is the portal. The portal is the primary access through which most if not all tunnel construction is carried out and it is the lifeline of the tunnel. Planning considerations include depth of cover, slope stability, economics of open cut versus shaft access, environmental impact, and contractor staging area. Critical aspects of planning, investigation, design, and construction of portals are considered by discussing portal design and portal failure case histories.

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 D. I. Phillips, P. J. Bethell

This paper focuses on the -1/2 mm cleaning at Elk Run Coal. The original circuitry incorporated desliming cyclones. Problems with slimes entrainment in the cyclone underflow (froth cell feed) resulted in poor froth cell selectivity. Laboratory test work led to the installation of high frequency desliming screens. Consequently, great improvement in cell performance was brought about by enhanced desliming with the ability to use split flotation. The modifications resulted in significant improvement in total plant performance and overall yield while maintaining clean coal quality.

Jan 1, 1987

By Kadri Dagdelen

The definition and shortcomings of traditional cutoff grades are discussed. . The concept of optimum cutoff grade policy which maximizes the Net Present Value (NPV) of annual cash flows coming from a mining project is introduced within the basic framework outlined by K. F. Lane. Several examples are used to demonstrate the shortfalls of cutoff grade policies obtained by various heuristic optimization techniques. An algorithm to obtain an optimum cutoff grade policy which maximizes the NPV of a project is given and described in detail.

Jan 1, 1992

By J. C. Stankus, J. J. McCaffrey, S. Guo, S. S. Peng

An innovative concept in longwall tailgate support is discussed. This new concept utilizes a high-capacity roof-truss system to replace conventional wooden cribs. The first field test was conducted at the Bailey Mine and was very successful. Similar tests were installed in other mines and seams. An extensive instrumentation plan was designed and implemented in the truss test area. The test data demonstrated that the dynamic roof-truss system effectively controls the various abutment pressures caused by longwall mining. Thus, a stable tailgate entry is maintained

Jan 1, 1997

By Jon T. Langstaff

The microseismic method of detecting instability and high-stress zones in underground mines was first developed in this country by the US Bureau of Mines in the early 1940's (Obert and Duvall, 1957). Early laboratory experiments showed that when competent rocks are stressed in a testing machine, the rock noise rate (number of rock noises per unit time) increases with increasing applied stress. This increase is more pronounced as the ultimate strength of the rock is approached. Subsequent testing of rock noises in underground mines confirmed this laboratory experience and much effort has been directed in recent years to make use of this property to develop a practical method of predicting rock failure. Investigations conducted in the Coeur d'Alene district mines have pointed out a definite relationship between the stress buildup in a rock mass caused by mining activity and the emission of audible and subaudible seismic activity (microseisms). In 1968, a concentrated joint effort by USBM Denver Mining Research Center and American Smelting and Refining Co. at Asarco's Galena mine was undertaken to verify several theories regarding the generation of microseisms (Blake, 1971; Blake, Leighton, and Duvall, 1974; and Kovacs, 1973). Findings indicate that (1) rocks under stress emit detectable seismic energy; (2) the energy source can be located using a triangulation method involving travel time differences to various receiving stations; (3) the rate of release of seismic energy increases with increasing stress; and (4) this increase in noise generally precedes a major rock failure (rock burst).

Jan 1, 1979

By Terence H. Fisher

The use of more productive mining equipment, the tendency to longer development and the advent of new mining methods have introduced new challenges to the ventilation practitioner in Western Australia. These new and more productive mining methods have presented specific ventilation problems, that if not properly addressed, present additional hazards to miners. Factors influencing the increased hazards are larger diesel units, the use of series ventilation systems and an increasing incidences of long (single entry) development and production headings where miners could be trapped in a fire emergency. This paper discusses these new ventilation safety challenges, how they have been and are being addressed, and the legislation changes that take cognisance of technological developments.

Jan 1, 1995