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By B. Bag

Saturated and unsaturated fatty acids are used in the flotation of iron values present in iron ore. Among the several fatty acids, oleic acid and its sodium salt are widely used. To substantiate the flotation results, the quantum chemical calculations of a few such acids have been carried out by adopting the semi-empirical AM1 method. These acids have been further optimized in the presence of an iron atom. The electronic interaction of the polar carboxylic head group of oleic acid with the iron atom is higher compared to the other acids. The numerical results support the flotation behavior of iron ore with oleic acid. Key words: Iron ore, Flotation, Fatty acids, Quantum chemical calculations, Semi-empirical AM1 method

Jan 1, 2009

By W. Jacobi

INTRODUCTION The radon problem concerns the radiation exposure from inhaled short-lived radon daughters and the associated risk for the induction or promotion of lung cancer. In several groups of miners which were exposed in the past to relative high radon levels during their underground work, an excess lung cancer frequency has been observed. On the basis of these findings it has to be stated that the inhalation of radon daughters is the most important radiation hazard in mining. Involved in this radon problem in mines are the difficulties to measure the individual radon daughter exposure of miners and to estimate the dose to critical cells and target tissues in the lung from inhaled radon daughters. And finally the reduction of radon levels in mines confronts us with special technical problems which are difficult to solve. Thus the setting of annual limits for the radon daughter exposure of miners alone is not sufficient to guarantee an appropriate standard of radiation safety. Of same importance are the improvement of air monitoring and the optimization of technical protection measures in mines. This has to be kept in mind for the following considerations on exposure limits. The ICRP has recommended in 1959 for the first time a maximum permissible concentration (MPC) for the occupational exposure to radon and its short-lived daughters (ICRP, 1959). This MPC in air was derived from a maximum permissible dose equivalent of 0.15 Sv (15 rem) per year to the epithelium of the large bronchi which was regarded as the "critical tissue". This old MPC-value was derived using a simplified lung model which paid main attention to the dose contribution from the inhalation of unattached 218Po(RaA) atoms. Since this time more realistic dosimetric models for radon daughters have been developed; some of these models will be presented in special papers on this conference. Furthermore in the last 10 - 20 years substantial epidemiological information on the lung cancer risk among several groups of Rn-exposed miners has become available. Taking into account these epidemiological and new dosimetric findings the ICRP has adopted in March this year new recommendations on occupational limits for inhalation of 222Rn, 22ORn and theirshort-lived daughters. This report will be published this year as ICRP Publication 32 (ICRP 1981). The recommended limits for radon daughters were derived from the basic dose and risk limits as they were proposed by ICRP in its new basic recommendations (ICRP Publ. 26, 1977). In the following this basic system of dose limitation is shortly outlined before the special recommendations for radon daughters are described. [BASIC CONCEPTS AND LIMITS] The new basic recommendation of ICRP (Publ. 26, 1977) proceed from the assumption that in the dose range which is relevant for radiation protection, the risk RT of so-called stochastic radiation effects (carcinogenic and genetic effects) in a target tissue T increases proportionally with the mean dose equivalent HT in this tissue: RT = aT HT. If several target tissues are irradiated the total individual (stochastic) risk is given by the sum of risks in these tissues: [R = ?TRT = ? T aT HT]. Thus this concept of individual health detriment takes into account the risk contribution from each relevant tissue. It replaces the old concept of the critical tissue, which neglected the exposure of other tissues. Applying this new concept a dose quantity can be defined which is proportional to the total individual radiation risk from stochastic effects. This so-called "effective dose equivalent (HE)" is given by the sum of the weighted dose equivalents in the relevant tissues: [HE = E wT HT with E wT = 1 T '1] The weighting factor wT of each tissues follows to wT = aT/awB, where awB is the total stochastic risk coefficient for a uniform irradiation of the whole body. For the lung as a single organ comprising several target tissues, the ICRP recommends a total weighting factor w = 0.12 (ICRP 1977/79). This concept of risk or detriment, respectively, has important consequences. To meet the objectives of radiation protection the new ICRP-system of dose limitation is based on the following three principles: 1) The justification of practices involving radiation exposures; no pratice shall be adopted unless it produces a net benefit. 2) The ALARA-principle that all exposures shall be kept as low as reasonably achievable; this requires the optimization of the level of protection. 3) The limitation of individual exposure (annual dose limits). It is important to note that the dose limits for individuals are only one part of this system of dose limitation. Furthermore, these limits cannot be regarded as a boundary between safe and unsafe. They have to be interpreted as the lower boundary of an unacceptable exposure region. This means that in addition to the observance of these basic dose limits it is demanded to optimize the level of protection. Consequently the optimized exposure levels or the corresponding operational limits will be normally lower than

Jan 1, 1981

By P. Grotjohann

In processing heavy mineral sands, the low feed concentration and respective high value of the desired minerals require high capacity production and sharp classification/separation techniques to reduce the specific production costs. The allflux® separator, a new process system introduced to the heavy mineral industry, meets these criteria in an economical way. Its two-stage process, a combination of rising current and fluidized bed technology, allows the treatment of extremely high massflows in a single unit. Using concepts that have proven successful in processing concrete sands for many years, testwork in coal, iron ore, and heavy minerals looks very promising.

Jan 1, 1998

By Michael E. Lively

DOUG HALBE: We've talked about copper operations and gold operations. For our third section on the topic "Operating Ideas That Have Saved Me Some Bucks," we'll turn to the coal fields. Our featured speaker is, I'm almost embarrassed to say, a mining engineer, Mike Lively. Mike has 25 years' experience in the coal industry. He is currently superintendent of surface operations for Southern Ohio Coal Company, Meigs Division (AEP Company). I've read his paper, and there's some really great information here. Mike.

Jan 1, 1998

By Jack G. Pippenger

This report focuses on the procedures required to review, prepare specifications, bid, and purchase a fully integrated computer system for utilization by engineering personnel in all phases of mine engineering. The presentation is based on the experiences encountered in 1984 in procuring an engineering computer system at The North American Coal Corporation's Western Divi- sion. A two-phase report detailing the purchasing process and subsequent utilization of the engineering computer system will be given. Special detail is also provided on the final system hardware and software setup.

Jan 1, 1989

By B. Govindarajan, T. C. Rao, J. P. Barnwal

A simple modelling methodology has been proposed to predict the performance of industrial coal flotation circuit based on the observations made on the actual performance. The solid content in the tailings of the coal flotation circuit has been identified as a lode-star to predict the performance in terms of yield and ash content of the concentrate. The modelling parameters are directly measurable.

Jan 1, 1995

By W. A. Cincilla, S. C. Tadolini

INTRODUCTION Resin bolting systems continue to gain popularity in underground coal mines in the United States, and their general success under a wide range of geological and operational conditions is well documented. In 1984, 36% of all bolts used were resin-grouted systems. However, many questions dealing with basic support mechanisms and the influence of various factors on bolt effectiveness in situ remain only partially answered. The Bureau of Mines' Denver Research Center conducted a major research project to investigate the influence of installation procedures on the effectiveness of resin-grouted roof bolts. The project consisted of two main studies: the first dealing with the contribution of bearing plates to the load-carrying capability of the bolt; the second examining the relationship between installed grout column and the anchorage capacity as measured by the standard pull-out test. Additionally, a finite-element computer model and other analytical and empirical techniques were applied to aid in the basic understanding of the test procedures and to examine the load transfer mechanism in resin-grouted bolts, which to date has not been comprehensively assessed. The plate study includes field test results from two mines (Fig. 1). At these test sites two behavioral parameters were measured: the actual loads that bearing plates were subjected to when installed in conjunction with full-column resin grouted bolts, and the roof movements generated by the applied loads. Results indicate that bearing plates are subjected to varying degrees of loading, which range from conventional installation pressures of 2.2 kN (500 lb), up to a measured load of 142.4 kN (32,000 lb) when the immediate roof is shifting and deforming. These measured loads indicate that the bearing plate is an integral part of the support system. Differential sag stations, installed to monitor roof displacements in the test sites, show the highest degrees of loading occur in conjunction with the largest amounts of movement. The column-length study addresses possible reductions in anchorage capacity of "full column" bolts. These reductions could result from such factors as the loss of grout to surrounding strata, or improper mixing of catalyst and resin. Field test sites were established at eleven mines located in major coal mining districts throughout the United States (Fig. 1). Four major roof-rock types were represented in the study: shale,

Jan 1, 1986

By Misra M., P. Grimes, Chen. S.

The combustion of petroleum products produces emissions which contain oxides of nitrogen (NOx), hydrocarbons (HC), and particulate matter (PM) which have adverse health and environmental effects. In recent years there has been increasing interest in the use of water-fie1 emulsions as a substitute for conventional fuels. Emulsified fuels are emulsions of water in fuel, which are typically made of 10 to 20 percent of water mired with certain additives and fuel. Studies have shown that the emulsified diesel can significantly reduce the emissions of NO, PM and car- bon monoxide and increase the fuel efficiency. In order to produce a stable diesel emulsion, the development of an effective surfactant additive is critical. The stability of diesel emulsions is influenced by many factors, including size distribution of the droplets, the viscosity of the continuous phase, the physical properties of the interfacial film, and temperature. This paper describes a method to produce emulsified diesel and combustion results obtained from various tests. It has been found that the diesel emulsion made with this additive package was stable during the test, and the emissions were lower in NO, CO, and PM compared to the baseline diesel.

Jan 1, 2005

By Douglas E. Rawling

The successful genetic manipulation of T. ferrooxidans is partly dependent on an understanding of the molecular biology of the organism. For optimum controlled expression of foreign DNA in T. ferrooxidans it is important that donor DNA is derived from bacteria that are genetically similar to T. ferrooxidans or placed under the control of T. ferrooxidans transcriptional promoters. Several structural genes and their controlling regions from T. ferrooxidans have been isolated and their DNA sequenced. These include the genes that encode the nitrogenase enzyme (nifHDK genes), glutamine synthetase (glnA gene) and the recA gene. These genes and the identical genes from a wide variety of other bacteria have been compared at levels of DNA sequence, protein sequence. Where possible, gene expression as well as transcriptional control and protein function of the cloned genes were tested in the enteric bacterium Escherichia coli. The two genes involved in nitrogen metabolism were either expressed or possessed the necessary elements for expression in other bacteria. In contrast the recA gene was not expressed in E. coli from its own promoter. The two gene products that would be tested (glnA and recA) were fully functional in E. coli. The relevance of these findings to the genetic manipulation of T. ferrooxidans is discussed

Jan 1, 1989

By S. Hoerger

Newmont has a large integrated operation in Northern Nevada with numerous mines, stockpiles, and processing facilities. There are over ninety defined metallurgical ore types and over sixty defined gold recovery process options. To take better advantage of the available synergies, a complete Nevada wide mine plan and process model along with a mixed Integer and Linear Programming optimization tool has been developed and implemented. This system is maintained and operated by a Nevada Planning Group. Standard in-house planning software tools and methods have been implemented at all mine sites. While increasing the effectiveness of planning in Nevada, these changes have allowed a significant reduction in overall Mine Engineering staff.

Jan 1, 1999

In the last four years, 2007~2010, 9 out of 24 metal/nonmetal underground mine fatalities were caused by ground fall across United States of America (Mine Safety & Health Administration, MSHA). To reduce or eliminate incidents/accidents caused by ground fall, this paper clarified how to design and select ground support based on different ground conditions, how to use mine ground support standards, what geotechnical engineers and underground operators should do to keep mine production free of ground failures.

Jan 1, 2012

By C. S. Boland

The Copper Range Company's mining properties are located in the Upper Penisula of Michigan. (Fig.). Early work indicated the presence of copper ore in a bedded deposit, confined to the base of the Upper Keweenawan Nonesuch shale, and exploitation of this deposit on a portion of the Company's property was undertaken by White Pine Copper Company. Diamond drilling of the White Pine orebody indicated that a major fault pattern terminated the values to the South-west. Further drilling Southwest of the fault zone proved a downward displacement of the ore bearing horizon some 1,500 feet and a lateral displacement of approximately 4,000 feet; and in this area an ore deposit was outlined in a large asymmetrical syncline locally plunging to the South-west. (Figs. 2 and 3)

Jan 1, 1962

By H. L. Ehrlich

Processes involving biological solubilization of metal values from ores, or removal of mineral constituents that interfere with metal value recovery from ores by abiological means, published mostly in the last 10 years, are reviewed. Many of them, though promising, have yet to be tested on a pilot scale or applied industrially.

Jan 1, 1987

By A. Bruce Waugh, W. W. Wen, Kevin N. Clark, Neville C. Lockhart, Bruce A. Firth

Australia is the world's largest coal exporter, and technological advancement is a key element of the coal industry strategy. The issues include: increased recovery of saleable coal; enhanced quality, i.e. lower ash, moisture, fines, phosphorus (sulphur is a relatively minor problem for Australian coals); better quality control; higher throughputs/lower costs; improved handling and transport; and reduced environmental impacts. In process terms, many coal preparation operations, particularly fine coal circuits, are relatively inefficient, and all circuits must also be matched and integrated for optimum overall operation. A holistic approach to technological improvement is desirable. This paper summarises research and development efforts, within CSIRO and its collaborators, across the unit operations as outlined in the title.

Jan 1, 1995

By Michael J. Martinson, John R. Larsen, J. Warren Andrews

Measurements reported in the paper were recorded in an active Green River, Wyoming, trona mine, partly as a teaching exercise and partly to provide the mine in question with additional input data for its ventilation network program. Measurements were made: - in representative three-entry intake airways in room and pillar sub-mains; - between the lower portion of a vertical down-cast hoisting shaft and the start of an intake airway system established in a room and pillar main; - in a representative downcast section of a divided vertical shaft, and of the collar entrance loss at the top of the same compartment. Pressure differences were measured with manometers and trailing hoses, air flowrates with calibrated anemometers, and barometric pressures and wet-and dry-bulb temperatures were recorded for density determinations. Where possible, results are quoted as Atkinson friction factors, and relevant measurements are recorded in some detail to show the magnitude of fluctuations in observed pressure differences.

Jan 1, 1987

By J. F. T. Agapito

Stability in Exxon's Colony Pilot Mine in the Piceance Creek Basin, Colorado has been monitored by periodic pillar stress-determinations End roof-to-floor convergence measurements since 1971. Pillar failure has caused marginal stability in some areas of the mine. Measurements taken during the process of failure provided valuable information on the in-situ pillar strength and long-term behavior of the mine structure. Four pillars were reinforced by 32 mm (1-1/4 in) diameter tensioned grouted bolts to increase long-term stability in the northern area of the mine. Stability of this area is necessary because future plans envision its use as an exit/access and ventilation exhaust. Computer analyses were performed to help evaluate the effect of pillar reinforcement on long-term stability. Results indicate that bolting is particularly useful in stabilizing failed pillars, but its effects are significant only in the immediate area of the pillar. The projected significant decrease in deformation of two extensively failed pillars near a main entry indicates that bolting reinforcement will assist the long-term stability of the opening.

Jan 1, 1985

By William C. Cassun

The important role of pit slope design in the overall economics of open-pit mining ventures has long been recognized and well documented.1 2 Any economic analysis of a pit slope design must reflect the trade-off between the benefits and the increased risk of slope failure inherent in steeper slope angles. The conventional practice in pit slope design is based on the factor of safety analysis.' The approach uses average values to arrive at a deterministic solution to slope stability. Past analyses based on this approach generally have had several drawbacks: 1. The risk from slope failure could not be quantified. 2. Only relatively simple pit wall geometries were considered. 3. The analyses were performed solely for the benefits of steeper slopes, seldom discussing the potential costs of slope failures. 4. Analyses were seldom considered in a year-by-year mine planning context. Recognizing that average values do not reflect the uncertainty in geomechanical parameters, a probabilistic philosophy to slope design has evolved. 4,5 However, this approach had not been fully developed to include complex slope geometries and mine planning consideration. In order to develop an integrated, pit slope design procedure, a research project was initiated at the University of Arizona during 1973 in conjunction with the Canada Center for Mineral and Energy Teleology. This research resulted in the development of a probabilistic design procedure. The remainder of this paper gives an overview of the probabilistic design procedure and a discussion of the requirements for the benefit-cost analysis of a pit slope design. Finally, the results of a case study undertaken at an operating mine are given.

Jan 1, 1977

By N. R. Sainath

This paper discusses the results of a laboratory investigation carried out to study the microscale flow characteristics of copper ores and the variation in flow behavior resulting from flow of leach solution. Fractures in 1.5 and 4 inch diameter cores were mapped by visual inspection. The cores were stressed in a triaxial stress field representative of in situ conditions. The permeability of the samples to water was then estimated. The samples were exposed to 20 g/l sulfuric acid and the experiment repeated. The Permeability of unleached samples ranges from 10-1 to 10-19 m2 and it increases as leaching progresses. The porosity variation and the rate of recovery of copper from the specimen during leaching were also studied.

Jan 1, 1991

The most important event affecting the United States coal industry in 1993 was the strike by the United Mine Workers of America (UMWA). This was a series of selective strikes, beginning with a strike against four Peabody Holding affiliates on Feb. 2, following unsuccessful contract negotiations between the UMWA and the Bituminous Coal Operators' Association (BCOA). Although that strike ended on March 3, the failure to reach a new contract agreement led to walkouts at several Midwestern mines on May 10. During the summer, the strike expanded to include mines of 13 companies in seven states including Ohio, Pennsylvania, Illinois, Indiana, Kentucky, Virginia and West Virginia. About 17,000 miners were idled during the strike. As the prospects for a settlement diminished, the Secretary of Labor appointed a federal mediator. The mediation resulted in a five-year contract. In addition to increases in wages and pensions, it was agreed that 60% of new job openings would be filled by laid off and active UMWA miners. In return, companies won the right to establish more flexible work rules and scheduling of miners. While some health care benefits were expanded, the agreement established a new health care system that was designed to reduce costs. Preliminary Energy Information Administration (EIA) data indicate that US coal production fell by 5% in 1993, to 859 Mt (947 million st) (Table 1). The strike was one of the primary causes of the decline in production. Another significant cause was a 27% decline in coal exports. Also, a very small displacement of domestic coal production resulted from a rise in coal imports.

Jan 1, 1994

By S. P. Lucido, I. Iwasaki

The potential of controlling heavy metal ions in effluents from discontinued mining operations and waste rock piles has been investigated. A fresh water green alga, Cyanidium caldarium, was found to have the potential to remove Cut' from solutions while exhibiting high tolerance to acid conditions which are commonly encountered in copper-nickel mine drainage. The process has the potential for application as a low maintenance metal decontamination system. The growth requirements and copper removal characteristics of this microorganism are described.

Jan 1, 1991