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. E. P. MATHEWSON, New York, N. Y.-I would like to call attention to the excellent plan for protecting the lining of the tanks from rough handling by the excavator. Many engineers, when considering mechanical excavators for lead-lined tanks, have been afraid that the machinery might get out' of order and rip out the lining. This difficulty seems to have been entirely overcome in this installation, and those who have been responsible for its success deserve a great deal of credit. A. F. CASE,* Cleveland, Ohio. (written discussion t).-The application of the automatic unloader to the copper leaching process at Ajo was a very radical departure from the common use of this machine, inasmuch as the only previous use of this device has been in connection with the unloading of coal and ore from vessels on the Great Lakes. There are many phases in connection with the unloading of ore from lake vessels that are not presented in the extraction of ore tailings from leaching vats. For instance, in unloading from boats, it is necessary to provide means to reach under the hatches to parts of the cargo hold which do not lie directly under the hatches, and to work in inaccessible places that do not exist in a leaching vat. These necessities require complications that could be very easily dispensed with in this new application. On this account the unloader, is applied to the New Cornelia, plant, represents what is probably the simplest development of the machine that has ever been produced, and, manifestly, in its simplest form it could he expected to show results corresponding to its performances when installed with all of its complications. One of the requirements of vessel unloading is extreme vertical travel, when the bucket is required to reach the bottom of the, cargo hold, often 12 or 13 ft. below water-level, and discharge into a receptacle 30 ft. above-the water. This was materially simplified at Ajo for the reason that the vertical travel was never more than 20 ft. This condition immediately resulted in the possibility of shortening the walking beam which carries the bucket leg, and, in fact, in entirely reducing the size of all the working, parts of the trolley, walking beam, and bucket leg, as far as reaches were concerned.

Jan 11, 1918

By Fred Bond

THE process of comminution by grinding is properly classified as an art, rather than as a science. Like most other operations concerned in ore dressing, or in the treat-ment of nonmetallic minerals, the mathe-matical relationships of rock breaking are still obscure, and much disputed. If some basic formula exists, comparable for in-stance to E = RI in electricity, it has not yet been placed in common use. The absence of such a comprehensive mathe-matical background undoubtedly is the cause of many inefficient designs and installations, as well as of much poorly oriented experimental work. On the other hand, the mathematical immaturity of the process constitutes an opportunity for a real contribution on the part of those who enjoy mental pioneering. Some of the statements made in any such exploratory work may be little more than opinions, and it is to be expected that some will later be proved untrue; but such an evolutionary development is necessary if we are ever to arrive at the fundamental laws, the discovery of which can change the empirical art into a mathematically exact science. The most significant principle of com-minution that we possess is probably Rittinger's law, which states that the work done in crushing or grinding is proportional to the area of the new surface produced. There is an alternative theory, known as Kick's law, which formerly was preferred to Rittinger's but which now is rather dis-credited. According to Kick, the work done in comminution is proportional to the volume, or weight, of the pieces broken, or to the cube of their diameters, while accord-ing to Rittinger it is proportional to the square of the diameters.

Jan 1, 1940

By Alfred H. Bell

IN 1945, Illinois produced 75,210,000 bid. of oil, or 4.4 percent of the total for the United States, and ranked sixth in the nation in oil production for the third consecutive year. Production decreased about 3 per cent from that of 1944, when the total Illinois production was 77,413,000 bbl. This is the smallest percentage of decrease in production in the state for any year since a peak was reached in 1940. Daily average production for 1945 was approximately 206,000 bbl. Daily averages by months were as follows:

Jan 1, 1946

By Kim Appleby

Epithermal gold-silver (lead-zinc-copper-manganese) mineralization on Misima Island is confined to steep and reactivated flat-lying normal faults in the upper plate of a major, shallowly dipping detachment fault. The hangingwall comprises an Eocene metavolcano-sedimentary sequence that has been extensively intruded byMiocene calc-alkaline granodiorite. It is unconformably overlain by Pliocene sedimentary and volcanic rocks. High-pressure amphibolite facies rocks dominate the footwall and have many characteristics of a metamorphic core complex. Mafic-alkalic lamprophyre dike swarms intrude the hangingwall and footwall sequences. Previous workers attributed the gold-silver mineralization on Misima to the intrusion of the porphyritic granodiorite (Williamson, 1984). This has been proposed for many tertiary gold deposits of the southwest Pacific(Sillitoe, 1989; Leach and Corbett, 1994).

Jan 1, 1996

By Paul M. Tyler

Graphite is chemically identical with diamond, both being crystallized allotropic forms of carbon. Graphite obviously differs greatly from diamond in physical properties and is easily recognized by its blackness, its softness (1 to 2 on Mohs' scale), and its slick feel when rubbed between the fingers. Strictly speaking, all graphite is crystalline, but grades in which the individual grains cannot be distinguished with the naked eye are commercially classed as amorphous. Natural mixtures of the two varieties occur in all proportions, and the classification of a given sample as "amorphous" or "crystalline" graphite is based largely upon trade practice. Until recently different varieties of vegetable or animal charcoal, lamp black, soot, gas carbon, and coal ware considered strictly amorphous, but modern examination by X-ray methods indicates that even these materials possess the same internal crystalline structure as graphite, differences in physical properties being perhaps explained by porosity or presence of combined hydrogen or other impurities.

Jan 1, 1941

Computerized financial models can be used in all phases of the mineral industry from setting exploration targets to projecting profit plans for producing mines. In this presentation, I will use the example of an exploration company entering a new district to trace the application of financial models through the following intermediate phases. 1. Hypothetical analysis and strategy 2. First encounter of mineralization 3. Preliminary drill results - decision process 4. Feasibility studies 5. Post-feasibility negotiations 6. Producing mine 7. Acquisition of producing mines or mineral properties. I will conclude with a brief discussion of the mechanics of the financial models that we use at Wright Engineers Limited. As we progress through the seven phases, the availability and accuracy of the data will parallel the complexity and application of the financial models. However, the same basic financial models are utilized throughout the seven phases. I will begin by suggesting that the exploration group is somewhat autonomous and has the mandate to explore in Western Canada.

Jan 1, 1979

By Grant D. Nicholas

This paper compares an integrated evaluation approach to decision-making with more traditional sensitivity analysis and Monte Carlo simulation. The primary objective is to highlight the differences in NPV that can arise from using these evaluation methods in a top down and bottom-up approach. Results from three resource scenarios, derived from sampling a "virtual" ore body (reality) on grid spacings of 75m, 50m and 25m, are analyzed and compared.

May 1, 2007

By J. B. Zadra

Tungsten, a comparatively new metal, is one of the important strategic war materials. In peacetime, tungsten is widely used as a filament in elec¬tric lamps and electronic tubes and is a vital constituent of some of the most important industrial alloys. High-speed tool steel containing tungsten and stellite alloys containing cobalt, chromium, and tungsten are extremely hard and resistant to corrosion. These alloys and the tungsten carbides are unequaled as cutting tools and in other wear-resistant applications. They play a prominent role in the present era of mass production. Alloys containing tungsten resist oxidation at high temperatures and have been key alloys in the development of modern aircraft. The adaptability of tungsten to new uses is expanding, particularly in the high-temperature range. Domestic production of tungsten has come from a large number of deposits in 17 of the 49 States; but, of the total domestic output from 1900 to 1956, more than 80 percent was produced from mines in North Carolina, California, Colorado, and Nevada. The average tenor of the mined ore was less than 1 percent tungsten trioxide (W03).

Jan 1, 1959

By W. H. Young

THE DOMEST[C bituminous coal and lignite industry remained fairly steady in 1959 compared with 1958. Although mechanization continued to expand and production increased slightly, consumption, average value, exports, and employment decreased. The percentage of underground production mechanically loaded, the percentage of total production mined by stripping, and tonnage per man per day were at their highest levels. Production.-The output of bituminous coal and lignite in 1959-412 million tons-was 0.4 percent greater than the 410.4 million tons produced in 1958. Production was retarded in 1959, largely owing to the steel strike and reduced exports.

Jan 1, 1960

By Lawrence A. Soltis

Senior engineering or executive management positions are filled by engineers who are evaluated on their performance, knowledge, skill, and maturity. Not only is technical expertise required but a knowledge of sales and marketing, finance, law, industrial relations, and public affairs is necessary. The University of Wisconsin-Extension offers an innovative post-baccalaureate degree program blending technical and professional subjects the Professional Development Degree in engineering (PDD)-designed to bring various opportunities for learn-

Jan 4, 1978

By V. Rajaram

Rock reinforcement systems are used in open pit and underground mines to stabilize the rock mass in-situ and provide safe working conditions. Significant progress has been made to date in the design and implementation of rock reinforcement systems to accommodate bad rock conditions and larger excavations. However, the rationale for the design of rock reinforcement systems remains essentially the same and can be categorized into three groups, namely 1. to create a beam of competent rock in stratified formations, 2. to resist sliding motion in jointed rock, 3. to passively support the superincumbent loads in highly stressed ground. Case histories of the rock reinforcement sys¬tems that illustrate these design approaches will be presented in this paper.

Jan 1, 1983

By Earl Oliver

Page A.I.M.E. Stabilization Committee Activity................. 133 Definition of Capture Rule: Robert E. Hardwicke.......................... 134 Westmoreland Natural Gas Co. vs. DeWitt................ 135 Kelly vs. Ohio Oil Co......................... 135 Bernard vs. Monongahela Gas Co.................... 136 Definition of Ownership in Place..................... 137 Prospective Stabilization Remedies.................... 137 Dean Roscoe Pound's Four Teats of Practicability.............. 137 I. Mechanically Feasible....................... 138 Capture Rule.......................... 138 Ownership in Place....................... 140 Mechanical Separatio.7 Method................. 140 Engineering Appraisal Method................. 141 II. Economically Advisable...................... 143 Capture Rule.......................... 144 Ownership in Place....................... 144 III. Politically Wise.......................... 144 Capture Rule..........................144 Ownership in Place.......................147 IV. Legally Sound..........................148 Capture Rule..........................148 Ownership in Place.......................149 Dean Henry M. Bates' Analysis......................149 Raumé................................152 The A.I.M.E. Stabilization Committee was named in 1932 to ascertain whether some practical substitute could be devised for the Rule of Capture, which was generally credited with being the major cause of instability in the Petroleum Industry. After considerable intercommittee correspondence a letter was received from E. DeGolyer under date of Jan. 25. 1935. in which he discussed the possibility of modifying rather than discarding the Rule of Capture. He summarized his proposal as follows:

Jan 1, 1937

By AIME AIME

QUALITY and size do not ordinarily go hand in hand, but there is good evidence that both these attributes reached a new peak at the Annual Meeting of the Institute in New York just concluded. Certainly, the total attendance of 2500 was far above any yet attained, as might be expected with the recent rapid growth of Institute member- ship. General comment indicates that the quality of the papers also was notable, though not measurable by so definite a yardstick as attendance. During the meeting 49 technical sessions were held, at which more than 250 formal papers were presented. In addition, there were some thirty special meetings of committees, Divisions, and other Institute groups. In reporting the Annual Meeting eleven years ago the statement was made that "unless the Engineering Societies should build for themselves a new building it is probable that no meeting can be larger," and "the fifth floor, where a buffet lunch is served each day, has reached its full capacity and it seems quite evident that any future development of Institute meetings must be along the lines of quality, not size." Unfortunately the angel to succeed Andrew Carnegie, who financed the building of the present home of the Institute 35 years ago, has not yet ' appeared. Even if some one would merely build another elevator or two in the present building it would help. Fortunately, the modern auditorium of the American Radiator & Standard

Jan 1, 1940

By R. S. Hearon

The image of the open-pit miner in the eyes or the Environmentalist has never been very outstanding. The phosphate industry, whose history in Florida reaches back to the late 1800's, can-not be credited until recently with a large number or accomplishments in terms of protection or the environment to change this image. This lack of action was not deliberate or in opposition with the desires of the public. In the formative years, there was little or no public and the companies found it necessary to build towns to house their employees and their families, towns which remained in existence until the late 50's and early 60's or formed the core of present large communities. Neither these pioneers nor most subsequent resource developers considered themselves un-thinking spoilers, nor were they so regarded by their contemporaries. Instead, they acted in a manner consistent with their environmental circumstances and intellectual heritage. Early Americans did make mistakes in using the land but the mistakes became apparent only in the opinion of later generations. Over the past five to ten years, there has been a new self-awareness in the industry with regard to environmental responsibilities brought about, in part by a continuing onslaught of new regulations with jurisdiction over our activities. Part of the new regulations are aimed at industries as a whole while many, particularly state regulations, pertain specifically to the phosphate mining industry. Why all the new regulations? The reasons are encased in a complex web of activity but stem primarily from a new public awareness of its environment. More and more of our youth have become interested in the environmental science areas such as biology and ecology. The tremendous growth rate in both the population and industry has made personal issues out of subjects such as atmospheric inversions and water shortages which previously were abstract concepts. The State has grown from a population of 1,500,000 in 1930 to approximately 9,000,000 people today. This personal impact and general lack of knowledge on the part of the public concerning economics has resulted in big business no longer being held in awe, often in contempt and generally in suspicion where environmental concerns are encountered.

Jan 1, 1978

"When a metal-mining company takes out a workmen's compensation insurance policy, it does so to relieve itself of its uncertain and variable financial liability under laps requiring payment to employees for lost-time accidents, there-by passing the liability or to the insuring agency. For this service, or rather for the assumption of the risk, the insuring agency charges the mining company a price, or in insurance parlance, ""a premium"".The insuring agency depends upon a volume and variety of business to average the losses incurred by its individual policy holders, and determines its price to cover losses that are suffered and its cost of doing business.It is generally known that all types of insurance are founded on the theory of probability applied to large groups of risks, Workmen's compensation insurance is no exception, and the average price paid therefor must be based on the frequency and severity of accidents in the particular industry or branch of industry under consideration. The frequency and severity rates are determined by statistics, which, of course, unless standardized, kept carefully and consistently, and analyzed properly, are liable to be inaccurate and misleadingThe importance of large groups in arriving at an average price for insurance service can not be overestimated, For example the writer knows of one small group of some twenty metal-mining companies whose losses during the past two years exceeded their premium charge by 54%. Not a single individual company during the two years kept its losses below the premium rate. For several years the group as a whole has persistently exceeded its premium rate, Such risks are not profitable to the insuring agencies and can only be carried where a large volume of good risks will balance the poor risks, but in order to conform to good insurance ethics the premium rate must be based on averages for the industry as a whole, and kept sufficiently low to induce operators to sell their risks."

May 1, 1924

By Paul M. Tyler

According to Lindgren , the economic importance of pegmatites stems from the fact that they represent the principal natural storehouse of two classes of mineral products : (1 ) common minerals in exceptional size and purity and ( 2 ) several of the rarest minerals , which are not commercially available from other types of deposits . Most pegmatites can be described simply as coarse- to very coarsegrained granites . Pegmatite includes coarse -textured igneous rocks of any composition , such as syenitic , alkali syenitic , dioritic , or gabbroitic ; but basic pegmatites are far less common than those that are associated with acid rocks and correspond approximately to the mineral composition of ordinary granite . Moreover , only a very few basic pegmatites can be considered as economic sources of useful minerals . Whereas , in ordinary granitic rocks the individual minerals usually measure 1/8 to 1/4 inch across , in pegmatites they are characteristically over 1 inch and often more than 12 inches in diameter . Although some of the constituents of the pegmatite may be only a fraction of an inch in length , single crystals more than 10 feet long are by no means unusual , and some crystals are enormous . A whole quarry was operated in the Urals within a single crystal of feldspar . Huge quartz crystals are quite common although usually imperfect . Muscovite plates 10 feet in diameter have been mined in India , and the Purdy mica mine in Canada contained a mica crystal measuring 6.5 by 9.5 feet and weighing nearly 7 tons , which supplied more than $20,000 worth of trimmed mica sheet . A loglike crystal of spodumene in the Etta mine in the Black Hills of South Dakota was 42 feet long . Giant crystals of beryl weighing several tons apiece have been mined from several properties . Because so many rare minerals are found in substantial concentration only in pegmatites , it is a common fallacy to suppose that pegmatites are always enriched in rare elements . Traces of most of these elements , of course , are found in almost all igneous rocks , and they reappear in the sediments derived from igneous rocks . It does not follow , however , that all or even most pegmatites contain higher percentages of rare elements than other granitic rocks . Geological evidence points to the probability that notable concentrations of rarer minerals or elements in pegmatites are more or less fortuituous , such additions often being ascribed to events subsequent to the original emplacement of the main body of the pegmatite . Most pegmatites consist principally of potash , feldspar , and quartz . Even mica , although commonly present , is not an essential constituent . Probably

Feb 1, 1950

By J. Réal Cloutier

[Options are a natural extension of the forward and futures markets as they offer fexible method of hedging exposure. -An organized options market is preferable to the "over the counter forward markets since EGCC (EOE, ME, VSE) assumes responsibility for contract fulfillment minimizing credit risks by guaranteeing transactions. -Options ante considerably more "fexible" than the futures and forward markets, permitting prompt, precise and respected adjustment of one's exposure risk position. -The risk to the buyer of the options market is limited to the initial premium paid.]

Jan 1, 1983

By A. S. Usrnani

Due to both turbulence and the highly variable geometry of castings, a realistic numerical simulation of the metal flow is prohibitvely expensive with current technology. However, when the chief purpose is to achieve realistic thermal fields a precise How simulation is not necessarily required. In this paper we assume a laminar flow regime and obtain the flow field by solving the incompressible Navier-Stokes Equations using a velocity-pressure segregated semi-implicit finite element method. The free metal surface is predicted by advecting a pseudo-concentration function via the computed How field. This involves an explicit finite element solution of a pure advection equation. The thermal field is calculated by solving the convective-diffusive energy equation by an explicit finite element method using the computed flow field and the location of the free surface. All the advection terms are discretized using a Taylor-Galerkin method. The interface between the metal and mould is modelled using special interface elements. The model is demonstrated by solving practical example problems. The results show that a sharp thermal front is maintained during the course of filling without excessive diffusion. The heat diffusion in the mould can be controlled by varying the metal mould heat transfer coefficient.

Jan 1, 1994

By Alexander Burns, David Dreisinger

The kinetics of the oxidation of uranium(IV) by oxygen gas in aqueous systems is dependent on acid concentration, oxygen partial pressure, and temperature. In order to better understand the relationship between these variables and the speed of oxidation, a series of experiments have been conducted where each parameter has been varied in turn. Data were collected continuously using UVVis spectroscopy, allowing for a detailed examination of the reaction rate over the course of each experiment. The data fit an overall apparent rate law that is 1.5order in uranium(IV), -2order in H+, first order in oxygen, and unaffected by uranium(VI). This relationship does not appear to hold for solutions with <0.2 mol/L initial acid, where a different kinetic mechanism appears to be dominant.

Jan 1, 2014

By W. L. Chen

In the United States hydraulic cyclones have been used for thickening, classification and cleaning in coal preparation plants for many years. The cleaning cyclones presently in use are based on using a "heavy medium", such as a fine magnetite and water pulp. The latest addition to cleaning cyclones is the one which uses ?water only?, or simply called "Hydrocyclone". Just as was the heavy medium cyclone, the hydrocyclones were originated in the Netherlands (1, 2). Plants using hydrocyclones were built in Europe (3) and test plants were erected in Canada (4, 5, 6) and India (7). Roberts and Schaefer Company has built four plants using hydrocyclone circuits. One additional plant is in the process of construction.

Jan 1, 1965