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By T. Burchett, F. Stanley, K. McGough, G. Luttrell

The vast majority of U.S. coal preparation plants utilize screen-bowl centrifuges to dewater their fine clean coal products. In light of this popularity, researchers at Virginia Tech have engaged in a variety of laboratory and industrial field test programs to develop technological enhancements that have the potential to further improve the performance of this important solid-liquid separation process. These enhancements, which include simple design modifications and new reagent packages, have been shown to significantly improve solids recovery and reduce product moisture in several experimental trials.

Jan 1, 2006

By C. P. Proctor, E. D. Hummer, J. A. Younkins

COMPARATIVELY little has been published relating practical experience with the control of the solid content of washery water systems that must be "closed." A "closed" system is one that for some reason may not be cleaned by the emission of any effluent of high solid content to be replaced by clean water in order to hold the solid content of the waste water within reasonable bounds for efficient washing. It is the purpose of this paper to describe practical experience with such a water system and to present data that it is hoped may be of some use to those who are faced with a similar problem. The washery clarification system described comprises three thickeners and three filters, and although it is admitted that each of the fields of water settling and thickening and filtration offers a wide scope for investigation, the authors are not attempting to present the answers to these problems but to set down the results of some experience along these lines, making no claims as to the ultimate solution of the problems in hand. The subject of water clarification has vast ramifications; for example, the science of flocculation as applied to water settling and filtering opens up fields of wide possibilities of which as yet little is known. A comparatively recent entry into the field of water treatment, which may offer possibilities of practical application, is the use of "wetting" agents such as "Aerosol." GENERAL ARRANGEMENT OF WATER SYSTEM So that the reader may obtain a comprehensive picture of the factors concerned in the control of a closed water system, it is necessary to give a brief description of the washing plant that is serviced by the water system to be described in the following pages. As we are not primarily concerned with the washing plant in detail, only a brief description of the flow of coal as it relates to the water system will be given here. For a more detailed account of this type of washer, the reader is referred to earlier papers.1.2 The washer, which handles 0 to 4-in. raw coal (750 tons per hour) is an American Rheolaveur plant of two complements; the coarse coal or sealed discharge plant and the fine coal or free discharge plant. The sealed discharge plant (Fig. r) consists of twin 48-in. primary launders, each having two washing boxes, supplemented by one 32-in. rewash launder, which also has two washing boxes. "Push" water for washing and conveying coal in these launders is supplied from a constant-head tank under pressure head of 10 ½ ft. at the point of introduction at the feed end of the launder. This tank also supplies water for upward or vertical currents used in the Rheolaveur or washing boxes. Each box discharges into a sealed boot elevator (Fig. I).

Jan 1, 1942

By Eugene Guccione

Evidence that the United States is gradually converting to the metric system of measurement can be perceived today even by housewives in a supermarket. The question is no longer whether but when the country will have completed the conversion. To the extent that any bickering about metrication still exists, the debate now centers on such issues as finding agreement on details of implementation, and whether federal legislation should speed up the metric-conversion process or allow it to proceed along its present evolutionary and voluntary course. Apparently, the voluntary or "make-haste-slowly" approach is gaining widespread support. According to The Research Institute of America, Inc., if and when federal legislation is enacted it will likely include the following national ground rules: (1) A National Metric Conversion Board will develop and submit to the President and Congress a comprehensive plan to achieve a coordinated, minimum-cost changeover. (2) The change- over will be completed 8 to 10 years after the board's plan goes into effect, and by that time the US will be predominantly, though not exclusively, metric. (3) Costs will "lie where they fall"; subsidies, special tax concessions, and antitrust exemptions will not be authorized by the legislation. (4) The changeover will be voluntary because of the recognition that while some firms can "go metric" in a matter of weeks, others may require 15 years or more, and a few might never convert. (5) In determining whether or not to convert, on an individual company basis, adherence will be to the "rule of reason-that is, ". . . do not convert unless the engineering, economic, or other benefits outweigh any metric-related disadvantages. No one is talking about rip- ping up our railroad tracks or rewiring our homes just to conform to the practice of metric nations in Europe." (6) Government is to be part of the solution, not part of the problem; in effect, says The Research Institute of America, the leverage of federal procurement will not be exerted to force-feed the metric changeover but will be coordinated with the sector-by-sector conversion of the economy.*

Jan 12, 1975

By Ralph J. Holmes

"An accurate knowledge of the chemical, mineralogical and physical characteristics of ores and mineral products that are mined, processed and sold commercially is crucial to resource definition, effective resource utilisation, plant design, process control, metallurgical accounting and finally quality control to ensure that contract specifications are met and equitable payment is received for product sales. However, the responsibility for sampling is often entrusted to personnel who do not fully appreciate the significance and importance of collecting fully representative samples for analysis, and they seem satisfied as long as some material is collected and returned to the laboratory for analysis. Furthermore, sample stations incorporated into the design of new plants are often the first casualties when cost cutting exercises commence. There is really little point in accurately analysing samples if they are not representative in the first place, because the resultant analyses can be seriously biased and the effort taken to carefully analyse such samples is largely a waste of time and resources.Ultimately, a poor knowledge of the characteristics of ores and mineral products limits the ability of mining companies to optimise the life of ore resources and plant performance, and failure to meet final product specifications can have disastrous consequences, including price penalties and more seriously loss of sales contracts and significant revenue losses due to poor sampling practices at the point of sale. Consequently, it is critical that sampling is given the attention it deserves as the first important step in the quality measurement chain. The golden rule for correct sampling is that all parts of the ore, concentrate, slurry or other material being sampled must have an equal opportunity of being collected and becoming part of the final sample for analysis."

Jan 1, 2016

By John Smith

"The RTZ Corporation PLCFrom a company's point-of-view, a good investment decision is one which results in the purchase of an asset that is worth more than it costs. Thus, in order to judge the merit of an investment opportunity, it is necessary to estimate the value of the assets to be acquired.Discounted cash flow (DCF) analysis has become widely adopted by companies in assessing potential new investments. The principle is a simple one: invest in projects which have a positive net present value, and reject those which do not. However, perhaps because of its apparent simplicity, DCF analysis is frequently misused. Good practice in the use of the technique is discussed, together with several common misconceptions.Sound analysis requires sound data; thus, the valuation process relies heavily upon a wide range of specialists to provide the basic input from which cash flow forecasts can be built up. The analyst must maintain close liaison with these specialists from the outset in order to ensure that the data provided is indeed relevant and complete.IntroductionBefore turning to the main subject of this paper ""How Companies Value Properties"", it is of interest to consider first a slightly different question ""Why do Companies value Properties""? In other words, for what purposes are such valuations prepared? Certainly the commonest, and probably the most important circumstance in which a valuation is required is when the company is considering an investment opportunity. This may be the direct purchase of a property or group of properties from a third party, but could also be the opportunity to develop a new operation or expand an existing one.A very simple objective in making any kind of investment is to make our shareholders richer than they would otherwise have been. That is, to make investments whose value to shareholders exceeds the consideration required to acquire them. Thus the investment decision focusses on the difference between an asset's value and its cost.This distinction between ""value"" and ""cost"" is an important one. Study of a company's balance sheet may tell a lot about the cost of this company's assets, but very little about their value. Then again, it is sometimes argued that a business should be bought because this will result in assets being acquired for less than their replacement cost. This merely compares one cost with another, it says nothing about value."

Jan 1, 1991

By R. J. Miller

The current National commitment to expanding the human presence into the solar system will clearly require major facilities in Earth orbit or possibly on the moon. Such facilities will need large amounts of materials for structural modules, life support, propulsion, and shielding. The heavy transportation costs in fuel required to lift materials from the Earth's surface make a terrestrial-based space system inherently inefficient. A more cost-effective approach would be to provide as much of the required materials as possible from other bodies in space not having the high cost of Earth launch. This paper identifies potential targets for space-based resource utilization, constraints on exploitation, and relative benefits of various sources.

Jan 1, 1992

By Jean-Luc Collins

"This new tool can be used as a quick guide f or the assessment of the potential economic wealth of any risky capital project. It does provide an unambiguous recommendation of the type ""go or no go"" to the decision-maker simply by comparing two different ratios profit/investment. One ratio determines the minimum value required to at least break even while the other measures a probable value based on the asymptotic theory of statistical extremes.Its application is briefly illustrated by means of an underground gold mine extension project, an oil sands mine project and a polymetallic open pit project.Once a favourable recommendation has been obtained then a detailed ""cash flow after taxes"" analysis can be carried out for the project.IntroductionMany tools are used in financial decision-making such as the payback period, the discounted cash flow, the internal rate of return and the wealth growth rate (Berry , 1971).These tools are useful and meaningful in evaluating normal projects closely related to regular business where the number of assumptions made is usually very small and where the cost of capita! is usually selected as a discount rate or a hurdle value. In situations where a significant number of assumptions have to be made,two problems can emerge, namely:I. the risk involved is underestimated leading to a potential financial disaster; or2. a good opportunity is lost because the approach used in evaluating the project is too conservative.Each assumption has its own degree of uncertainty and it is well known that combining uncertainties together can lead to a total uncertainty of critical proportion. The easiest way to account for risk is to increase the discount rate or the hurdle value, but this approach alone is quite subjective and can easily lead to the problems described above."

Jan 1, 1993

The Department of Interior, U.S. Bureau of Mines performs the task of estimating the quantity of coal reserves existing in each state on a county by county basis. As a part of Information Circular 8655, the Bureau of Mines established the criteria for the uniform estimations of coal reserves and listed the most recent estimates of coal reserves by county and by seam. At the same time however, the Bureau recognized that these figures represented the upper bound with regard to the estimated actually usable or obtainable reserves. Recovery of these reserves are subject to the mining methods used and to the resolution of such problems as the use of poor quality coal and competition provided by conflicting land use. These problems, in practice restrict the recovery of the estimated quantities of coal reserves listed in IC 8655. Another impact, the subject of this manual, is the impact resulting from previous mining activities. In particular, many of the reserve seams included in the reserve estimates overlie or underlie mined-out coal beds. Portions of these reserve seams may therefore be unmineable or at best may have a reduced quantity of extractable coal. In order to improve the accuracy of the coal reserve base estimates, the Bureau of Mines funded an effort1 to develop a systematic methodology for estimating the coal loss associated with the impact of previous mining activity. The coal loss calculation model (CLCM) described in this manual is a result of that effort and addresses the percentage of coal loss in reserve seams due to previous overmining or undermining.

Jan 1, 1976

By NORMAN D. FitzGkrald

IN 1942 the outstanding characteristic of the petroleum industry was the multiplicity of war-induced distortions in virtually every segment of the business. So devastating was the success of the Nazi submarine campaign along the shores of the western Atlantic and on transoceanic routes that within six months after our entry into the war petroleum rationing was necessary in the East Coast area. The conquest of the Netherlands Indies by the Japanese three months after the opening of the war in the Pacific cut off our normal sources of rubber, and in our first year of war nationwide rationing of gasoline had to be invoked to conserve rubber-borne transportation facilities. Meanwhile the oil industry faced the imperative necessity for rapid expansion in the output of aviation gasoline and later accepted the vast responsibility for developing a new industry. synthetic rubber manufacture. Probably no other essentially peacetime industry has been forced to make so many complicated adjustments, yet its response to its wartime obligations has been nothing short of dramatic.

Jan 1, 1943

By H. W. Davis, Richard J. Lund

"In presenting the results of this survey on consumption of ferrous scrap and pig iron for the year 1935 the Bureau of Mines, responding to requests from industry, seeks to fill a major gap that has long existed in the field of metalliferous raw-material statistics. This type of information is designed to meet the needs of: (1) Consumers of ferrous scrap. including operators of blast furnaces, steel mills, ferrous foundries, and rolling mills; (2) marketers of scrap iron and steel, including large brokers who sell, and dealers who collect, prepare, and sell the material; (3) large scrap producers; (4) producers of iron ore, with which scrap competes indirectly; and (5) other individuals and agencies interested in more general economic analysis, since the scrap market has repeatedly been cited as one of the most sensitive of all industrial barometers, If the survey prover as useful as now seems probable, it will be continued annually with possibly an enlarged scope of treatment.The Bureau appreciates that its first efforts in this field may not meet all expectations: but it hopes to develop gradually, through suggestions, advice, and criticism from the industrial groups most interested, a type of analysis that will accord closely with technical processes and best meet the needs of all groups vitally interested in supplies and use of ferrous scrap. Constructive criticism and suggestions from industry regarding improvements to be desired in the conduct of future surveys on this subject will therefore be warmly received by the Bureau."

Nov 1, 1936

By James J. Scott

To the safety engineer, mine planning engineer, and mine inspector associated with an underground operation, stability of the underground structure is of the utmost importance. In the United States in 1961 rock falls killed 167 miners, crippled many more, and cost the industry a fortune in lost equipment and production. Much research has been carried on to try to find ways to eliminate this loss of life and property. Within the past few years the interest in rock mechanics as a science has been at its highest point, Private industry, government agencies, universities and foundations have launched studies to gain a better basic understanding of the stability of underground openings.

Jan 1, 1966

By R. S. Tahautdinov, A. N. Posazhennikov, V. V. Bastrygin

"The Bakal (South Ural, Russia) deposit of iron ore bearing iron carbonate (siderite) with the capacity of more than 1 billion tones belongs to the MMK. This ore cannot be fully processed via blast furnace technology because of high content of MgO. According to the investigations carried out in the USA and Japan in 1999-2004 the ITmk3 (Ironmaking Technology mark three) RHF technology is a breakthrough in Ironmaking. Four iron ore types (hematite, magnetite, high and low Al2O3/SiO2) were tested. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from iron carbonate bearing ore via the ITmk3 by means of the lab scale testing. Samples of iron ore and carbon reductant were chemically and physically analyzed. Green pellets were processed via a lab tube furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities in 1996 [1]. After pilot testing at Kobe Steel’s Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics has committed to building the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota). Only 4 iron ore types (hematite, magnetite, high Al2O3/SiO2 and low Al2O3/SiO2), as well as 4 coal types with range of volatility, ash and fixed carbon were tested. Results were consistent with nugget characteristics confirming ITmk3’s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from iron carbonate bearing ore with high content of MgO has been done. Such kind of iron ore is restricted for charging into the blast furnace due to contamination of MgO. The reason for restriction is the limitation of load of MgO in the blast furnace. If a lot of MgO enters the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace."

Jan 1, 2011

By Kendall E. Born

Production of crude oil in Tennessee during 1940 was slightly more than 15,000 bbl., a decrease from 1939 of about 36,000 bbl. This sharp decline has been caused largely by curtailed activities in the shallow pools in Clay County, where approximately 3000 bbl. was marketed off the lease during the year as against more than 37,000 bbl. in 1939. The flashy production found in 1938 in the Celina area has been short-lived and the area is essentially abandoned. Failure to find steady production has been the major factor retarding developments in the northeastern Highland Rim area. The Mississippi lime production in Scott and Morgan Counties continued to show a steady decline. The Tennessee production by counties is shown in Table I. Table i.—Oil Production in Tennessee it1 1940 Production. Bbl. Number of County Wells Pumped 1939 1940 Scott............ 4 4,332 3.596 Morgan.......... I: 6,479 5,751 Fentress.......... 3 I,2XX 1,5xz Pickett........... 1 1.2XX Clay............. 8 37.200 3,XXX Developments There were 32 wells spudded in during 1940, four of which were drilling or only temporarily suspended on Dec. 31, 1940. Twenty-eight wells were completed during the year, four of which were commercial producers. The total footage drilled was 3I,214 ft. The more important wildcats are listed in Table 2; the distribution of 1940 oil and gas tests according to physiographic divisions is given in Table 3. Cumberland Platenu.—Thcre was one completion in the coal area of the state, a test that attempted to extend the Mississippi lime production in the Coon Hollow pool to the southeast in Morgan County. This test encountered only slight shows of oil in the producing horizons of the near-by Coon Hollow and Boone Camp pools. Some surface work was carried on by private interests during the year in Scott and Morgan Counties and two wells were spudded in early in 1941 The revival of interest in the Kentucky portion of the plateau will probably result in increased activity in this part of Tennessee during 1941. Several sizable blocks of acreage, some by major oil companies, are held in Scott, Morgan, and Cumberland Counties. Middle Tennessee.—The northeastern Highland Rim continued to be the most active area in the state with 20 completions, although this figure is about one third of the number drilled in 1939. Four oil wells, none with initial productions of more than I00 bbl., were completed in Clay, Fentress, and Pickett Counties. The producing horizons discovered in Pickett and Fentress Counties were in the "Sunny-brookJ' pays of Trenton age. The Clay County producer was an old test drilled deeper in which oil was found at 671 ft. in the upper part of the Stones River group of limestones, a common pay in this area. All four wells were drilled in or close to old shallow production. Deeper testing into the Knox dolomite group in this area was not particularly encouraging, although one well in Fentress County encountered some saturation at 1860 to 1869 ft. in the upper

Jan 1, 1941

By Kendall E. Born

Production of crude oil in Tennessee during 1940 was slightly more than 15,000 bbl., a decrease from 1939 of about 36,000 bbl. This sharp decline has been caused largely by curtailed activities in the shallow pools in Clay County, where approximately 3000 bbl. was marketed off the lease during the year as against more than 37,000 bbl. in 1939. The flashy production found in 1938 in the Celina area has been short-lived and the area is essentially abandoned. Failure to find steady production has been the major factor retarding developments in the northeastern Highland Rim area. The Mississippi lime production in Scott and Morgan Counties continued to show a steady decline. The Tennessee production by counties is shown in Table I. Table i.—Oil Production in Tennessee it1 1940 Production. Bbl. Number of County Wells Pumped 1939 1940 Scott............ 4 4,332 3.596 Morgan.......... I: 6,479 5,751 Fentress.......... 3 I,2XX 1,5xz Pickett........... 1 1.2XX Clay............. 8 37.200 3,XXX Developments There were 32 wells spudded in during 1940, four of which were drilling or only temporarily suspended on Dec. 31, 1940. Twenty-eight wells were completed during the year, four of which were commercial producers. The total footage drilled was 3I,214 ft. The more important wildcats are listed in Table 2; the distribution of 1940 oil and gas tests according to physiographic divisions is given in Table 3. Cumberland Platenu.—Thcre was one completion in the coal area of the state, a test that attempted to extend the Mississippi lime production in the Coon Hollow pool to the southeast in Morgan County. This test encountered only slight shows of oil in the producing horizons of the near-by Coon Hollow and Boone Camp pools. Some surface work was carried on by private interests during the year in Scott and Morgan Counties and two wells were spudded in early in 1941 The revival of interest in the Kentucky portion of the plateau will probably result in increased activity in this part of Tennessee during 1941. Several sizable blocks of acreage, some by major oil companies, are held in Scott, Morgan, and Cumberland Counties. Middle Tennessee.—The northeastern Highland Rim continued to be the most active area in the state with 20 completions, although this figure is about one third of the number drilled in 1939. Four oil wells, none with initial productions of more than I00 bbl., were completed in Clay, Fentress, and Pickett Counties. The producing horizons discovered in Pickett and Fentress Counties were in the "Sunny-brookJ' pays of Trenton age. The Clay County producer was an old test drilled deeper in which oil was found at 671 ft. in the upper part of the Stones River group of limestones, a common pay in this area. All four wells were drilled in or close to old shallow production. Deeper testing into the Knox dolomite group in this area was not particularly encouraging, although one well in Fentress County encountered some saturation at 1860 to 1869 ft. in the upper

Jan 1, 1941

By D. L. Schweyer, W. A. Munson, R. H. Hanewald

Discussed is the INMETCO processing of electric arc furnace (EAF) baghouse dusts from the specialty-steel and low-alloy industries. In addition, the INMETCO process has been modified to recover nickel, chromium and iron from many other waste materials including: •pickling solutions or filter cakes, •spent nickel and chromium plating baths, •carbon refractories from pickling tanks, and •superalloy wastes including baghouse bags. INMETCO is the only North American company presently capable of recycling nickel-cadmium batteries by high-temperature metals recovery. This process and the details of INMETCO's best demonstrated available technology (BDAT) test program are discussed.

Jan 1, 1993

By A. H. Grobe, F. N. Rhines

THE constitution of the indium-zinc alloy series has been investigated by Wilson and Peretti,1 who determined the liquidus and eutectic temperatures by the conventional method of cooling curves and the eutectic composition by analyzing eutectic exudations. Recent developments affecting the availability of indium and consequent increased interest in its applications make a more complete knowledge of the constitution of its alloys desirable. As a part of a program for the reexamination of the constitution of indium alloys by precision methods, the indium-zinc phase diagram [ ] (Figs. I and 2) has been redetermined in its entirety. The eutectic temperature (143.5°C.) reported by Wilson and Peretti has been confirmed exactly, but their value of the zinc concentration at the eutectic, 4 per cent, was found to be high; the new value is 2.8 per cent of zinc. There is also a rather large difference between the forms of the liquidus curves of Wilson and Peretti and those found in the present studies. The solidus curves herein have been located for the first time and the limits of solid solubility have been tenta-

Jan 1, 1944

R. S. MACPHERRAN,* Milwaukee, Wis. (written discussion?);-Mr. Stork's paper is very interesting, but I am unable to agree with some of his conclusions. He argues very strongly for the beneficial effect of oxygen, but gives no actual determinations of this element to support -his views. He states that the oxygen resulting from a high bed, heavy charges, low coke ratio, etc. must not be confused with the oxygen under normal conditions. I will be glad to know in what respect these oxygens differ or in what state they occur. Is it his opinion that the beneficial type is present as a dissolved gas and the other as metallic oxide? I will not discuss the first five of his six points, as I have not seen enough trustworthy determinations of oxygen in cast iron to form any conclusions as to its effect. I have never known the addition of manga-nese, however, to reduce the strength of cast iron. Under the sixth point, I would say that the addition of steel lowers the total carbon content, and by this action will increase the strength independently of oxygen. This reduction of carbon operates also to raise the melting point. It is interesting to note here that the author, in order to get proper fluidity for his cylinders, was obliged to reduce his oxygen by raising the manganese in the charge.

Jan 12, 1919

By O .. G. Sharrer

Loading mechanically has of late become the most widely discussed subject in connection with coal mining and has even equalled. the discussion of safety measures as a topic of interest. The subject has been discussed in the various mining journals and by well. informed persons at the Mining Institutes, so it would appear; that all has been said that can be said until further experiments bring out new lines of discussion. It is, therefore, not the intention to present this article as a technical discussion of the subject of mechanical loading as a whole, but rather as a plain talk on machines with which the writer has had personal contact. In 1919, during the first period of post-war depression, a Pennsylvania coal company employing union labor became interested in the possibilities of mechanical loading with the hope of reducing their mining costs, which were and are yet too high to meet competition from the non-union fields of Somerset and Westmoreland counties. Of several loaders presented for their consideration the model of the Joy loader shown by Mr. Joseph F. Joy, seemed to hold the greatest possibilities, and after extended study, the management decided to invest in a machine of this type. A machine was built, which as far as the writer knows was the only one of its type ever put on the market. This machine arrived at one of the mines early in 1920 and was put to work immediately. It was a forerunner of the present 4-BU and 5-BU types, but differed from them very radically as to design. In general the machine consisted of the familiar Joy gathering arms and a short conveyor which discharged into a steel tank which held about four and one-half tons of coal. This tank was emptied by a second conveyor which placed the coal in the mine car. The object of this conveyor tank was to provide storage room while changing cars and to allow the machine to load on the entry while the room was short. This plan was very efficient and from our experience was worth retaining, but has been abandoned by the Joy Company on account of its making the machine unwieldy. The whole machine was mounted on caterpillar tractors which were driven by two 10-H.P. Westinghouse series wound motors, each having its own controller, the controllers being arranged in tandem so as to be operated by the same handle. This very ingenious scheme which is shown in Figure 4, was supposed to make it possible to steer the loader by the controllers. By swinging the handle one way both motors moved forward, by swinging the handle the other way both motors moved backwards and by twisting the handle as shown by arrows, one motor moved ahead and the other back, thus causing the machine to turn. This scheme proved a failure as the loader was too temperamental and erratic in its operation. After Mr. Joy, himself, narrowly escaped serious injury, this device was taken off and the controllers manipulated separately. This system never proved satisfactory and was abandoned' for

Jan 1, 1925

By Lawrence Devon Smith

"The Management and Economics Society has undertaken a survey of industry practice in the evaluation of mineral projects. The survey addresses a number of issues relating to evaluation techniques, discounted cash flow methodology, and risk. Completed during the spring and summer of2005, the results provide a record of opinion at an active and vital time in our industry.The 2005 survey questionnaire was distributed by e-mail to groups and organizations around the world. There were 22 respondents out of several hundred questionnaires distributed (we gather this small proportion of respondents is typical for such surveys). The responses, although a small number, show a consistency that suggests that the survey has captured the views of the industry. The results of the survey are summarized below in series of tables and graphs.The reader is cautioned that the results are a snapshot of industry practice at a point in time as represented by a small sampling of the industry's practitioners. These results should be viewed as indicative values."

Jan 1, 2003

By Daniel Gustavo Perucca

Los proyectos Veladero, Jagüelito, el proyecto binacional Pascua-Lama y otros ubicados en la zona Valle del Cura, provincia de San Juan, Argentina necesitan una vía acceso que permita el tránsito de camiones capaces de transportar los insumos necesarios en sus etapas de construcción y explotación. En este sentido, el objetivo del trabajo estriba en seleccionar la alternativa más conveniente y así cuantificar los costos y beneficios derivados de la construcción de un camino de vinculación entre los proyectos mencionados y las localidades de Rodeo o Las Flores. La metodología aplicada es la comparación entre costos y beneficios entre las situaciones “con proyecto” (obra ejecutada) y “sin proyecto” (situación actual), de forma que en un futuro, la construcción del camino estudiado posibilitará el abastecimiento de insumos a los yacimientos ubicados en el Valle del Cura, provincia de San Juan.

Sep 13, 2001