Search Documents

By D. D. Misra

Though computer simulation of coal beneficiation has been in use for nearly two decades the models used in the programs for the simulation of the crushing processes concentrate mainly on the size distribution. This paper suggests the use of an empirical equation approximating to the cumulative probability or error function for the simulation of the liberation process in coal crushing. The algorithm outlined here can be incorporated in a computer program already having a size distribution model.

Jan 1, 1989

By J. L. Weaver

The spiraling rate in phosphate rock demand during the period 1957 to 1967 led producers to expect a continuation of a high growth rate. Consequently they expanded production capacity to meet the expected demand. Both the domestic and the world demand has shown little growth over the past three years. Florida producers operating at less than 75% of installed mining capacity, produce all that their markets will absorb. We expect that the nest few years will bring only a slight improvement in this condition. An increased demand in the domestic agricultural market will be partially offset by a continuing erosion in the export market.

Jan 1, 1972

By J. F. T. Agapito

The load carrying capacity of oil shale pillars excavated by conventional blasting, presplit blasting, and mechanical mining is evaluated. The study was based on a comparison of in-situ vertical stresses and fractures obtained from overcoring horizontal holes in the Colony Mine, Piceance Creek Basin, Colorado. Results indicate that conventional blasting causes a zone of damage approximately 3 m (10 ft) thick with low stress distributions. Presplit blasting reduces damage significantly, and increases the load carrying capacity in the 3 m (10 ft) thick zone by 5.93 MPa (860 psi). Mechanical mining causes little or no rock damage, and an increase of 9.83 MPa (1425 psi) in strength in the same 3 m (10 ft) thick zone. An example of pillar design is given showing that the use of presplit blasting and mechanical mining techniques can increase the extraction ratio by at least three and five percent, respectively, as compared to conventional blasting. It is speculated that comparable increases in extraction should also occur due to increases in span dimensions.

Jan 1, 1984

By Mary-Lee Athorn, David A. Barratt

An opportunity to compare the performance of different tunnel boring machines (TBMs) operating in similar rock conditions occurred during the construction of a major water scheme in the UK. The principal objectives of this study were: (i) To collate, analyse and present the data available for the four TBM drives of the Kielder Aquaduct Scheme in terms of the tunnelling system performance and the downtime experienced, particularly where these were influenced or controlled by geotechnical parameters. (ii) To isolate the major sources of machine downtime and highlight those aspects of the tunnelling system that critically affect tunnelling progress rates (iii) To determine, by statistical techniques, relations between TBM performance and rock properties.

Jan 1, 1986

By R. Larry Grayson

A survey of 1250 surface and underground coal mines across the United States was made according to a stratified sampling technique based on national coal districts. A total of 171 responses (13.7% response rate) have been returned and summarized, giving a picture of computer usage in the coal industry. Overall, 63.5% of the respondents use computers, but the percent varied from 100% for large mines to only 44.1% for small mines. As expected, a proliferation of microcomputers has pervaded the industry. Importantly, in spite of the high usage of computers in the industry, sophisticated engineering applications have not yet burgeoned.

Jan 1, 1989

By Frank R. Cappuccitti

This paper will deal with current market trends for sulfide mineral collectors in three distinct parts; the global market for sulfide collectors, collectors as tools to solve mineral processing problems and new collector Research in the 1990's. The global market and manufacturing of sulfide collectors will be detailed as well as the trend towards using increasing amounts of specialty products. The use of Total Quality Concepts for laboratory and plant evaluations of new products will also be discussed. Research in the 1990's for sulfide collectors will need to focus not on the development of new chemical species but on the application of the new technologies that have already been developed.

Jan 1, 1994

By J. A. Burger

Research in the eastern U.S. has shown that productive mine soils and forests can be restored using the following guidelines: (1) cooperation among the mine operator, landowner, and regulatory authority in developing the mining permit; (2) replacing topsoil or creating a desirable medium in which trees are planted; (3) loosely grading non-compacted topsoil; (4) using native and non-competitive domestic ground covers that quickly protect the site; and (5) planting a proper silvicultural mix of crop trees for their commercial value along with nurse trees for wildlife and soil improvement.

Jan 1, 2002

By A. G. Mayton

Bureau of Mines research has addressed improved operator protection for thin-seam shuttle cars. Because of working height restrictions in thin-seam mines (1.22 m or 48 in), MSHA regulations require that-canopy protection on shuttle cars be provided only in mines 1.07 m (42 in) and greater; however, variances are given to mines 1.22 m (48 in) and below. This paper reviews past Bureau efforts to develop protective structures for thin-seam shuttle car operators. The paper also discusses recent research leading to a novel method of protecting shuttle car operators, in mines as low as 1.02 m (40 in), through the use of a cross-car, end-mounted operator compartment.

Jan 1, 1989

By Robert W. Elayer

For the design of a coal mine and process plant, a comprehensive foundation of geologic information is essential. Historically, the development, collation, and use of this information for design have been costly and time consuming. With the application of a digital computer, however, the effort expended can be reduced and maximum effective use of the geologic information realized. The purpose of this paper is to demonstrate the feasibility and convenience of using a computer to Store and manipulate geologic data for use in mine and process plant design.

Jan 1, 1975

By Kenneth R. Miller

Surface mine equipment operators in the Campbell County region of Wyoming's Powder River Basin have found new ways of solving old problems. Technology, experience, competitive pressures and an increasing grasp of economies of scale have driven mine operators, equipment manufacturers and suppliers to specialization of applications. In economic terms, today's coal price of $4.95/t ($4.50/st) equates to $2.53/t ($2.30/st) in 1980 terms - an incomprehensible value at that time. This article describes some examples of change and adaptation made by Powder River Basin coal operators in overburden stripping equipment and techniques. It focuses on the evolution of the design and use draglines, shovels, trucks, scrapers and dozers.

Jan 1, 1998

By Marvin A. Ph. D. Friedman

The following paper describes an overview of evaluations for assessing the potential hazards associated with handling newly developed reagents used in the mining industry. Important factors in determining the risk and hazard associated with handling a particular chemical include hazard identification, dose-response assessment, exposure assessment, and risk characterization. The hazard evaluation step involves collecting and evaluating appropriate toxicology information on a chemical. This can include a comparison of the structure of a developmental chemical with that of a material with known toxicology information. Acute toxicology data, including oral, inhalation, and dermal LD50 values, eye and skin irritation data and sensitization or allergic potential information are typically generated for new chemicals. Environmental and in-vitro genetic toxicology data (e.g. Ames test) are also used to evaluate new mining reagents.

Jan 1, 1994

By Steven W. Hunt, Ronald E. Heuer, Safdar A. Gill

A 3.3 m (11 feet) diameter, 51 m (168 feet) deep temporary steel casing which had been sunk within glacial soils buckled and collapsed on July 29, 1985. The collapse occurred at the CT-8 Dropshaft site in Milwaukee while two workmen were contact grouting outside the casing in an attempt to stop groundwater inflows through a bottom plug. This paper describes the soil and groundwater conditions at the site, the casing design, the method of shaft construction, and probable causes of the buckling failure. Specific aspects of the paper include: slurry method of shaft excavation and casing installation, soil creep, earth pressure due to three dimensional arching, and buckling strength of a casing surrounded by slurry rather than grout and firm soil. The paper should be of interest to designers and constructors of temporary ground support systems for deep shafts.

Jan 1, 1995

By V Leus, J. Kallioinen

The large size of the modern flotation cells and the high product flow rate from them has increased the importance of optimal flotation of all the particle sizes and of process control. By treating all the subprocesses of flotation separately a new family of flotation cells and a new concept of optimizing the flotation of coarse and fine particles in separate units but in the same row of flotation cells has been developed. The paper discusses the possibility to enhance coarse particle flotation by varying the froth residence time. A function has been developed between the residence time of the froth, air rate and the froth removal rate of coarse apatite particles. The response of apatite flotation to different control variables has been studied and modelled. The results show that the BPL assay response depends not only on the control variable used but also on the feed assay to the cell. There exists an feed assay dependent region within which the froth assay can be controlled by using the froth residence time as the control variable. These regions can be used to tune a rougher-multistep cleaner circuit to optimal.

Jan 1, 1993

By C. O. Brawner

A recent advance in slope dewatering-depressurization and stabilization is the use of vacuum assist horizontal drainage. (Brawner and Pakalnis) Horizontal drains have been used for several decades to reduce water pressures in slopes to improve stability. The benefit from vacuum assist arises from an increased hydraulic gradient caused by an induced negative atmospheric pressure. A research program included a laboratory model whereby the effects of vacuum drainage were evaluated. Three case studies are described where the technique has been successful. The first is in a rock slope where flows increased from 0.1 1/min. under gravity drainage up to 1.2 1/min, upon vacuum. The second study involves installation of 17 drains placed at a slightly downward gradient to intercept and de- pressurize aquifers under a major tar sand deposit in Canada. The third study was on a large open pit copper mine in British Columbia where flow increased about 30 per cent.

Jan 1, 1984

By Pamela J. Nebgen

Surface mine planning and watershed management requires the manipulation of a massive volume of data. The processes of collecting, examining, selecting, and generalizing information for the production of maps and sediment structure designs are a major part of mine planning and evaluation. Computer aided design graphics systems are becoming increasingly more important to the surface mining industry. This paper illustrates the applications of a digitizer and plotter interfaced to an IBM PC-XT microcomputer, which form the hardware elements in the new University of Kentucky hydrology, sedimentology, and structure design package called SEDCAD.

Jan 1, 1986

By H. E. Goetzman

A cooperative research project supported by the taconite industry and the Minnesota DNR was undertaken to establish quality standards for carboxymethyl cellulose (CMC) based organic binders. The objective of this study was to identify the effect of CMC quality parameters such as degree of substitution, molecular weight, and purity as well as the effect of inorganic extenders such as sodium carbonate on performance. These factors have been evaluated by green-ball testing with two taconite concentrates followed by pot-grate tests. Balling tests with bentonite and Peridur were conducted to provide baseline data. At a constant DS the molecular weight as measured by viscosity had the greatest effect on green-ball drop strength. Dry-ball compression strength was most dependent on CMC addition rate and sodium carbonate content. DS was not found to have a major effect on green-ball quality for medium molecular weight CMC.

Jan 1, 1988

By F. L. Pierson

Since the discovery of 'potash in the Carlsbad area in 1926 and the start of mining operations in 1931, "first mining," operations have been carried on. This is a room and pillar system in which approximately 62% of the total ore is removed. Or the basis of ore reserves and rates of extraction, the life of the mine in the early; days was estimated to be well over 50 years, however, even with an increase by additional ore reserves, it became increasingly apparent that the life of the mine was being shortened considerably by increased production. Further cause for the shortening of mine life was due to the exceptionally weak back over the northeast quadrant of the main orebody which had .caved in on first mining up to a height of 8 feet. Thus, in 1953 the decision was' made to begin pillar pulling, also called, second mining or final mining, and in December of 1953 this program was started after much discussion.

Jan 1, 1965

By Joe Hachey, Jerry Dorn, Jeff Schutt, Derek Penrice

"Sound Transit’s East Link Project, a $3.7 billion (2015 $), 14-mile light rail extension, will connect downtown Seattle with the rapidly developing east side cities of Bellevue and Redmond. Among the most technically challenging aspects of the Project is the 2,435 foot long Downtown Bellevue Tunnel (DBT), which will be constructed through the central core of Bellevue underneath 110th Avenue NE using a combination of Sequential Excavation Methods (SEM) and cut and cover tunneling. The 1,980 foot long central SEM component of the DBT will be mined at shallow depth through challenging and complex geology, comprised of glacially overconsolidated soils, containing both regional and perched groundwater conditions and in close proximity to existing high rise buildings. The paper shares lessons learned from the planning decisions and risk based approach to the investigation, design and procurement processes which shaped the DBT configuration and enabled a successful transition to the project’s construction stage. INTRODUCTION The East Link Project is a voter-approved $3.7 billion (2015 $), 14-mile extension of the existing Sound Transit (ST) light rail transit (LRT) system from downtown Seattle, across Lake Washington via I-90, to the cities of Bellevue and Redmond on the east side of Lake Washington. With targeted completion in 2023, East Link will provide riders with an efficient and reliable connection between the largest population and employment centers on the east side and downtown Seattle. The project alignment is indicated in Figure 1 below.ST completed the Preliminary Engineering (PE) phase of the East Link project in late 2011. Subsequently the final design contract for the easternmost seven miles of the project was awarded to the H-J-H Team, a joint venture comprised of HNTB, Jacobs Engineering and Hatch Mott MacDonald in February 2012. H-J-H’s final design scope includes approximately 7 miles of double-track LRT between the east end of the I-90 East Channel Bridge and the Overlake Transit Center Station. While the project scope is extensive and diverse, the focus of this paper is the DBT. The DBT is located immediately north of the East Main Station, and travels approximately one half mile through downtown Bellevue under 110th Avenue NE between Main Street and NE 6th Street; terminating at the Downtown Bellevue Transit Center (BTC) Station. The location and extent of the DBT is indicated in Figure 2."

Jan 1, 2016

By Mark E. Smith

Oxide ores can consume enormous amounts of expensive sulfuric acid. The problem is amplified with increasing heap heights. One solution is to provide a thin liner and drainage system between each lift of ore, thereby intercepting the pregnant leach leach solution (PLS) after it exits the active lift. However, these liner systems require special attention to hydraulics, slope stability and geomembrane design criteria. Inadequate attention to the first two can result in reduced recoveries, increased acid consumption andsystem failures. The geomembrane selection criteria are different from the base liner, and optimizing its selection can have significant effects on the operation’s bottom line.

Jan 1, 1996

By Liu Hanzhao, Jin Yongduo

Many gold ores which are not only submicroscopic but also rich in arsenic and organic carbon, for example Dongbeizhai Mine, have been found in china. These ores belong to the most refractory ores The key to the recovery of gold from these ores is preoxidation. Dongbeizhai ores have been tested with biooxidation, chlorination, double oxidation, acidic and alkaline pressure oxidation, catalytic oxidation, NITROX and roasting. To date it appears that either roasting or pressure oxidation is optimal. It is suggested that the flotation-roasting (or pressure oxidation)-CIL process should be used to treat this type of ore.

Jan 1, 1995