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By James Barr

The process of manufacturing ferrophosphorus lies not alone in smelting a mixture of phosphates, silica, iron ore, with coke as fuel, but upon smelting this mixture with coke and air as chemical agents as well as heat producers and in conjunction with extraordinary procedures and manipulations making the process continuous and profitable. For best results there must be cool top, limited fusion zone, hot bottom, good mechanical condition of stock and perfect distribution of gases; also minimum air supply, high heats and excess of coke or carbon. FERROPHOSPHORUS, an alloy of phosphorus and iron or perhaps a physical mixture of definite compounds of iron and phosphorus, has become of increasing importance as the use of the basic open hearth has extended. Commercial ferrophosphorus is a porous, brittle metal of crystalline structure and often with a bluish metallic luster. A typical analysis is as follows: PER CENT. Phosphorus 18.0 to 22.0 Iron 80.0 76.0 Oxygen 0.2 Sulfur : 0.3 Silicon 0.1 Carbon : 0.1 Manganese 0.2 This alloy was first made in an electric furnace, as it was thought that the high heat of the electric arc together with the reductive effect of carbon was necessary. About 1898, J. J. Gray, Jr., was producing a high-phosphorus pig iron in his furnace at Rockdale, Tenn., by using high-phosphorus, local iron ores. As these high-phosphorus ores were difficult to obtain, he conceived the idea of increasing the phosphorus content of the pig iron by the addition of phosphate rock to the furnace burden. When the phosphorus content of the pig was kept low and only small amounts of phosphate rock were added to the burden, no particular troubles were encountered, but when he increased the amount of phosphate rock to produce an 18 per cent. alloy, his furnace troubles rapidly multiplied.

Jan 10, 1924

RISKGATE is an interactive online risk management system developed by the Minerals Industry Safety and Health Centre (MISHC; University of Queensland) to assist the mining industry in implementing continual improvement in management of major unwanted events, and so maximising health and safety performance. A comprehensive body of knowledge has been compiled from diverse mining industry experts for risk management of tyres, collisions, fires, isolation, strata underground, ground control open cut, explosions, explosives, manual tasks and slips/trips/falls. This paper presents an overview of the body of knowledge captured from diverse mining industry experts for the management of unwanted strata incidents, and explosions in the underground environment. This knowledge is divided into a series of initiating events within both topics (as listed) with further degrees of classification based on design, operation, and management concerns. Strata Underground Initiating Events: Explosions Initiating Events Loss of strata control at longwall face Fire or ignition in a sealed area Loss of strata control in outbye roadways Fire or ignition in an unsealed goaf area Loss of strata control in roadways under development Fire or ignition in an extraction face Loss of control of overburden and caving behavior Fire or ignition in outbye Loss of pillar system stability Loss of control of goaf edge in pillar extraction Fire or ignition in a development panel or first working Loss of strata control in shafts The system guides the user in generating substantive and leading edge controls to assist industry stakeholders in the design, management and reporting of organisational and regulatory compliance requirements. From a broader industry perspective, RISKGATE provides an environment for knowledge capture and knowledge exchange to drive innovation and best practice in the identification, assessment and management of risk. By capturing operational knowledge from industry experts, RISKGATE provides a cumulative corporate memory at a time of high personnel turnover in the coal industry.

Aug 1, 2013

The desire for minimising impacts of mining activities on the environment, and in particular, water resources; is usually tempered by the costs and practicalities of implementing æbest practiceÆ measures. This paper briefly discusses the theoretical and practical options for water management for typical mines and quarries in a range of environments to assess if adverse impacts can be completely eliminated or at least be perceived as doing so. The regulatory requirements for water resources management are usually an essential part of mine planning and operations that can be a primary focus for all stakeholders. As such they can distract attention from implementing best practice in water management for the benefit of the environment and the community for altruistic reasons that have a long-term benefit for the mining industry as a whole. Cost-effective options for supply, demand and quality management of water that comply with basic regulatory requirements are readily available. Making a mine æinvisibleÆ in a practical sense, in terms of impacts on water resources would require eliminating potentially contaminated discharges, minimising demand, maximising reuse and recycling and putting back a healthy proportion of the clean water that is taken out of the natural environment for use in mine operations. This may sound simple enough and there are many well-known standard approaches that are usually applied. But which are the most effective, and who benefits? New approaches to water management are becoming more affordable and can benefit the bottom line as well as the environment, but can they make a mine ædisappearÆ? The perception of whether a mine is æinvisibleÆ in terms of its impacts on water resources is as important as the actions taken to try to achieve such an objective. The viewpoints and thresholds of perceptions of the different stakeholders are therefore relevant to how ævisibleÆ mining activities become.

Jan 1, 2006

By Gregg Wilkerson

The Blind Springs Hill pumice beds are located 5 miles southwest of Benton, California in the foothills between the Benton Mountain Range and Blind Springs Valley. The best exposures of the pumice are in an area 0.75 miles west of Blind Springs Hill. The pumice is Quaternary ejecta material which came from the rhyolitic volcanoes in the Glass Mountain-Volcanic Tablelands area of Mono County. The pumice beds occur in two distinct layers separated by an unconformity. The upper layer is 0 to 11 feet thick and consists of coarse subangular pumice fragments, some of which are over 1.75 inches in diameter. The lower bed is medium to coarse grained with subangular fragments up to 1.0 inch. The lower bed is 0 to 9 feet thick. Overburden at the Blind Springs Hill deposit varies from 0 to 15 feet. There are approximately 1 million cubic yards of material in the deposit that can be mined. The size distribution in the deposit is mostly fine with only 10.6% of the pumice fragments being over 0.5 inch in diameter, the minimum size needed for stone-wash or acid-wash applications. Suitability of pumice for the textile industry is quantified by standard 15-minute abrasion and absorption tests. In the Blind Springs Hill deposit, the plus 0.5 inch fraction has an abrasion loss of 33% which is too high for stone-wash application but it has an absorption capacity of 36% which makes it suitable for acid-wash applications in the textile industry. The abrasion and absorption properties of this deposit are within the range of those which have been measured for other pumice deposits within the United States.

Jan 1, 1995

INSTITUTE MEDALS AND PRIZES ASIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has four awards it may make annually, as fol¬lows. the Robert W. Hunt Medal and Prize, the J. E. Johnson, Jr., Award, the James Douglas Medal, and the William Lawrence Saun¬ders Medal. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting ceremony-on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules 1 The award shall consist of two prizes first of a gold medal, second of a sum of money, a certificate to accompany each prize The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal 2 The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel The scope of the term "iron and steel" shall be determined by the sub-committee considering the awards In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main contributions to the industry have been in the improvement of production and quality of material

Jan 1, 1923

By M. Wu, A. Kharicha, J. Bohacek, A. Ludwig

"During the horizontal spin casting of rolls, vibrations and mould deformations seems to have a significant effect on the final quality of the product. Sources for vibrations can be found in the poor roundness and a static imbalance of the chill itself. The bending of the mould axis is also considered. Both, vibrations and axis bending, are used as an input for CFD simulations of the flow dynamics of the liquid metal inside the rotating cylinder. The aim is to study the feedback of the free surface behavior in terms of wave propagation and various wave shapes. Introduction The horizontal spin casting process (HSC) is a casting process that has several advantages over the traditional gravity casting processes. Centrifugally cast products have a high degree of metallurgical purity and homogeneous microstructure. A significant gain is observed for the rupture strength, the rupture strain, and the Young modulus. These properties naturally depend on the centrifugal force and thus, the best mechanical properties can be found at the largest distance from axis of rotation. However proper selection of the angular frequency has to be done in order to prevent the so-called ""metal rain"" i.e. metal droplets can fall down from the upper part of the cylinder due to a too weak centrifugal acceleration. In the same time excessive speeds can lead to the appearance of longitudinal cracks caused by the hoop stress in the initially solidified layer. From empirical knowledge other parameters have important influence on the casting products, it includes the pouring temperature, the pouring rate, the mould coating etc. Recently the presence of natural or forced vibrations have been identified as possible additional factors to be taken into account [1-2]."

Jan 1, 2012

By Charles Larkey

NUMEROUS papers have been published on the use of graphic methods to determine the best curve to be used in estimating the production decline of oil wells but, as far as the writer has been able to ascertain, nothing has been published dealing directly with the subject as to how curves may be worked out mathematically, which will conform most closely to the production data under consideration in any given instance; hence the writer has endeavored to show by means of a few concrete examples just how such appli-cation can be made. Among valuation engineers, two types of curves are in current use for the representation of the decline in production of oil wells. One may be represented by the equation, y = krx, sometimes known as a percentage curve, for the reason that the production for any period is multiplied by a constant rate or percentage to obtain the production for the succeeding period. This curve appears as a straight line on semi-logarithmic cross-section paper. The other curve may be represented by the equation, y = kxn, and is shown as a straight line on logarithmic cross-section paper. In each of these equations, y represents the number of barrels produced over a given period of time, and x the successive periods of time. The other letters are constants to be determined for each well or group of wells considered in arriving at the most probable curve to represent the rate of production for a given property; from which the underground reserves may be estimated by extrapolation, or the extending of the curve beyond the last known period of production to show the most probable production values for the future.

Jan 7, 1923

By Gail F. Moulton

The production of petroleum in Illinois in 1928 was approximately 6,500,000 bbl., a decline of about 500,000 bbl. from the previous year and of about 1,500,000 bbl. from 1924. Production increased about 200,000 bbl. in Indiana to slightly less than 1,000,000 bbl. Production for 1929 is estimated at approximately 6,000,000 bbl. for Illinois and 1,000,000 bbl. for Indiana. Illinois Because production from most of the wells in the state has declined to a small daily average and the low prices for crude oil discouraged wildcatting, the number of wells drilled fell below that for any previous year since the development of commercially important production in the state. The Ohio Oil Co. discovered a pool of apparent commercial importance in southwestern Illinois near Dupo, in St. Clair County, and favorable showings of oil were encountered in a well in southeastern Illinois, near Harrisburg in Saline County. New production from the Dupo area is expected to check the rate of decline for the state. Thc following tablel summarizes field developments for 1927 and 1928 (for important detail by counties see notes at foot of table): 1027 1928 Completions........................................... 162 145a Initial production, bbl.................................. 2244 1840b Dry holes........................................,.... 66 58" Gas well completions................................... 13 8d 0111 wells abandoned.................................... 45" a Crawford, 44; Lawrence, 28; Wabash, 40. b Crawford, 501; Lawrence, 403; St. Clair, 165 (4 completions); Wahash, 668. o Crawford, 12; Wabash, 19. d Crawford, 6. b Lawrence, 21; Wabash, 15. The discovery well in the Dupo field in St. Clair County, produced about 150 bbl. per day from the Trenton lime at 660 ft. It is located in a northern extension of the Columbia-Waterloo anticline on which the Waterloo pool was developed in 1921. The best information on the.

Jan 1, 1929

By Ashbel Welch

Gentlemen of the American Institude of Mining Engineers.—As you well know an application is about to be made to Congress, by the American Society of Civil Engineers, for the appointment of a cornmission composed of persons skilled in the production and use of iron, steel, and other structural materials, whose duty it shall be to test the strength, elasticity, and other quatities of such materials ; not simply the substances used as such, but the members of large structures composed of such materials, of the forms and sizes in which they are actually used. As I understand, the papers that will be read here to- night will have for their object to show the necessity for such tests, and therefore the necessity for the commission asked for. As the representative of the Society of Civil Engineers, I have to thank you, gentlemen of the Mining Engineers, for the great zeal with which yon have taken up this subject, and seconded the efforts of the Civil Engineers; or, perhaps I ought rather to say, initiated the efforts to get a suitable commission appointed to obtain most vitally important information which it is admitted on all hands we do not now posses. In drawing up the memorial to Congress, in connection with some of the ablest and best informed of our Society, and in all the discossions on the subject, I have been struck with the emphasis with which the confession is made, that so little is known of the strength of the larger-sized members constantly used in building structures of the magnitude which the present requirements of the country now demand. I presume the remarks made to-night will bring this out very prominently. This is no disgrace, for with the means here-

Jan 1, 1882

By Dinabandhu Ghosh

The stability diagram of the ternary system Ti-C-O is drawn in the present work for four temperatures, 1473 K, 1573 K, 1673 K and 1873 K, showing the stability fields of TiC, Ti, TiO, Ti2O3 and TiO2. An analysis of the system reveals that it is not possible to produce Ti in a carbon-saturated system; instead, the stable product is TiC. However, Ti can be an equilibrium product in a carbon-unsaturated system at prohibitively low values of pCO and pCO2; for example, at 1873 K, these limiting values are: pCO = 10-6.76 atm and pCO2 = 10-13.36 atm, which, when exceeded, produce TiC and TiO respectively. The magnesiothermic reduction is examined through the stability diagram (log pO2 vs. 1/T) of the system Ti-Mg-O, drawn for a number of pMg values, presenting the pairwise stability fields such as Mg(l) + Ti(s), Mg(v) + Ti(s), MgO(s) + Ti(s), etc. The diagram shows that magnesium reduction of TiO to Ti is possible only at T < 1641 K with pMg = 1 atm and only at T < 1569 K with pMg = 0.5 atm. An experimental scheme for Mg vapor reduction of TiO2 is proposed in which an argon stream is passed over a Mg(liquid) evaporator at temperature T1 (say, 1234 K); the resulting Ar-Mg mixture at 1 atm is subsequently flown over a bed of TiO2 at temperature T2. A thermodynamic analysis establishes that complete reduction to Ti is possible and that the best results are obtained when T1 = T2.

Jan 1, 2006

By Remmerswaal, U. Boin, M. B. G. Castro

"To design sustainable products that can be recycled with high resource efficiency, low environmental impact and economic feasibility, the choice of materials and materials combinations, made in the design stage, is fundamental. The products we design, manufacture and use now will be the resources of the future. Designers are able to select materials for a product according to the many functional requirements they must fulfil. But they have a limited knowledge of the recycling processes and its requirements regarding quality of the secondary material streams. Resource Engineers have to manage the processing of these streams, that are becoming more complex with the increasing variety of materials and decreasing size of components. After mechanical separation of the materials streams resulting from shredding of EOL (endof- life) products, there is always a degree of contamination, from two possible causes:Incomplete liberation: the bonds between different materials combined in a component are not completely destroyed by shredding, resulting in some particles containing two or more materials attached;Separation efficiency: the mechanical separation processes are not able to separate perfectly the many material particles; there are always a number of foreign particles in the recovered streams.Sometimes, those contaminants cannot be removed by the industrial metallurgic recycling processes, and a more serious problem occurs when the contamination levels compromise the recycling of the material stream by lowering its quality (i.e. the properties of the recycled material will be lower due to the contamination). As a consequence, the material must be diluted in virgin raw material and/or used in a less demanding application (downgrading), causing resource depletion and increased energy use, waste production and recycling costs. In order to make the best choice of materials combinations for a product, a systematic approach is necessary, that can close the gap between the knowledge areas of Product Design and Recycling Technology."

Jan 1, 2003

ASIDE from the John Fritz Medal, in which the Institute partici¬pates through its representation on the John Fritz Medal Board, the Institute itself has four awards it may make annually, as fol¬ lows the Robert W Hunt Medal and Prize, the J E. Johnson, Jr , Award, the James Douglas Medal, and the William Lawrence Saun¬ders Medal ROBERT W HUNT MEDAL AND PRIZE The partners of Robert W Hunt established a fund which was, presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded tinder the following rules¬ 1 The award shall consist of two prizes first of a gold medal, second of a sum of money, a certificate to accompany each prize The money prize shall not be awarded to a member&apos; over 40 years of age, but under unusual circumstances, both prizes may be allotted to one per son provided that he is not over 40 years of age In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal 2 The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on non and steel The scope of the term "iron and steel" shall be determined by the sub-committee consideing the awards In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt&apos;s main con¬ti ibutions to the industry have been in the improvement of production and quality of material

Jan 1, 1923

NOW continuing with the preparation of the moulds I say that it is necessary to give the greatest attention to the differences of the clays as well as to the differences of those things that you wish to mould; and to know that every concavity in the mould produces a convexity and every convexity a hollow following the shape of the original pattern that you have. The pattern should be a body of a harder mated than the thing [78] you wish to mould with and of a substance that is not swollen or disintegrated by moisture. Its archetype may be of marble, bronze, lead, or any other metal, or also of wood, wax, tallow, gypsum, sulphur, or other plaster compositions-in short, of whatever you may have or whatever succeeds best for you, depending on whether the works are large or small and easy or &cult to mould. If you wish to cast them in bronze, you must mould them with loam, covering them with it and then drying it. There are some things in which it is enough to form only one part, such as half- or bas-reliefs. These are easy if they have no undercuts. Some other patterns that are easily handled are formed in two halves, or in three or four pieces, if they are of a hard material. There are also moulds for large statues, which, if one desires to make them of bronze, are first made of wax according to the ordinary procedure. I have in mind to describe every one of these processes in their own place. There are like- wise some moulds that are difficult to make, like scenes on a plane to which figures in full relief are attached, or twisted ornaments or other detached things that cannot be withdrawn from the mould without break-

Jan 1, 1942

By Dale S. Preece

INTRODUCTION In 1975 Congress passed the Energy Conservation Act to establish a U. S. Strategic Petroleum Reserve (SPR) with a capacity of 750 million barrels of crude oil. The most economic storage medium was determined to be salt caverns leached in salt domes in Louisiana and Texas. Salt caverns existed at several sites when the reserve was created. These were obtained by the U. S. Department of Energy (DOE) and used to initiate SPR oil storage. In order to meet the storage capacity approved by Congress, new caverns also had to be leached. To support the resulting design effort, finite element computer programs have been used to determine the creep closure and structural stability of salt caverns Using site specific material properties including creep models, elastic moduli and fracture data, the finite element analyses have replaced earlier empirical approaches to cavern design. This report presents results of such finite element analyses to determine the best cavern roof shape and the minimum pillar to diameter ratio, P/D. These numerical predictions indicate that the current cavern design is safe. FINITE ELEMENT AND MATERIAL MODELING The finite element program used in this study has existed for approximately four years. Its theoritical basis (Key, et al, 1980) and application are well documented It was originally developed to predict the creep around mined openings In bedded rock salt for the Waste Isolation Pilot Plant (WIPP) The program was tested by modeling the creep of salt around a drift and by comparing the results with the predictions of eight other structural computer codes (Morgan, et al, 1981) Since then the program has had continual use for calculations to support the WIPP (Miller, et al, 1982) For about two years the

Jan 1, 1984

By John M. Marek

INTRODUCTION This paper is for the mining manager, generally meaning mine superintendent, chief engineer, and others who have control over the mine operation responsible for feeding the insatiable beast called the mill or processing plant. The author is not from mine management but from the field of technical mine engineering consulting. This fact illustrates the authors gross inadequacy to comment on this subject. On the other hand, the consulting profession allows visits to many mine operations, worldwide, supplying many different commodities. The common complaints and misunderstandings that have been heard worldwide will be shared within the following few paragraphs. In order to discuss optimization, one must first define it. There certainly will be many papers in the following sessions that claim to optimize something, or other, based on a technical definition of cost, efficiency, throughput or some other quantifiable basis. DEFINE OPTIMIZATION Actual optimization of an operation is not as easily achieved as most of us in the technical world would like. Borrowing terminology from the technical world, the boundary conditions and the optimization function are usually not well defined. The problems in many cases do not lend themselves to quantification. Typical management procedures are to establish goals or strategies that set the approach or general boundary conditions to the overall plant. Three simple cases are listed below as possible corporate strategies to optimization of a mine-process plant complex. 1) Maximized discounted cash flow 2) Minimized long term cost of product 3) Maximized resource utilization This list seems simple when presented in the above context, uncluttered by constraints such as market position, capital availability, or environmental limitations. Sometimes the best approach is a prioritized combination of the above items. Typically, the Board or CEO has established these strategic priorities. They may

Jan 1, 1991

The primary purpose of the Institute is to advance those sciences embraced by it through interchange of knowledge This can best be done by the presentation and discussion of technical papers by its mem¬bers Short practical papers are especially welcome In any case the author should satisfy himself that his material is of a quality that will be a credit to him and to the Institute The preparation of a good paper frequently leads to a reorientation of the author&apos;s thoughts, which is extremely valuable, and pertinent dis¬cussion thereof contributes in no small way to the professional standing of the author Members are urged to submit papers presenting the results of their work Attention to the following suggestions will greatly further the prompt and efficient handling of manuscripts 1 Subjects: The subject must be within the field of the Institute Original work, the results of field, plant, laboratory or theoretical investigations, new views on old but important problems and occasion¬ally reviews of timely and important subjects of wide interest to our members may constitute the basis of a paper The mere fact that the work is original does not necessarily justify publication it must be of a substantial nature, of value to a reasonable number of our members and worthy of permanent record It is rarely desirable to subdivide the results of a single research for publication in a variety of journals Pre¬vious publication is a bar to acceptance 2 Construction : Papers should be clearly and concisely written in good English Care in this regard insures wider reading and the saving in space permits the Institute to publish more papers The terminology and units employed should be those current in the particular field An examination of Institute publications will afford useful guidance in such

Jan 1, 1937

By Paul Delottinville, Maynard Hall, Henry Hillier

"An expert system application for supervisory control and optimization of the indurating process at the Iron Ore Company of Canada (IOCC) has been developed and installed in closed-loop. Prior to the installation of the expert system, the indurating machine was rebuilt and the instrumentation revamped. A Foxboro I/A Distributed Control System (DCS) was installed for regulatory control, and a new control strategy configured. The modernization of the regulatory control has resulted in significant improvement in both production rate and product quality. Expert system control was implemented in September 1996. Preliminary indications are that the expert system has further improved the consistency of product quality, enhanced fuel efficiency and increased productivity. The expert system considers both wet and dry sections of the circuit, and its optimization scheme is driven by pellet tumble index and compression strength. Statistical Process Control (SPC) rules were implemented in the expert system as part of the quality analysis and control scheme. The expert system application was developed and delivered using the Comdale Expert Optimizer (CEO), and has been in continuous closed-loop control since its installation. The system development and implementation is described, and preliminary benefits are presented..... IntroductionIn early 1996 the Iron Ore Company of Canada (IOCC) contracted Comdale Technologies of Toronto to develop and implement a real-time expert system for optimizing the indurating pelletizing furnace at our plant location in Labrador City, Newfoundland.The decision to install the expert system has been timely. Like many other resource-based industries in increasingly competitive markets, IOCC recognizes the need to find ways to improve the efficiency of our production process and ensure that product quality is maintained at the highest levels. With the Labrador City plant producing 11 million tons of iron ore pellets annually, implementing the best technology solutions to meet these objectives is critical."

Jan 1, 1998

By Roberto Fernandez

Want of knowledge on the part of experts from abroad respecting the amalgamation-system, known as the Mexican or patio process, has been the cause in this country of trouble to many foreign mining companies. This process has not been looked upon by their managers as a satisfactory method of treating silver-ores, and they prefer to employ others, which, although more modern, and often more profitable in other countries, have not proved to be so under the exceptional conditions of this country, where labor is cheap and paid in silver, while fuel is very dear. The cause of this error of judgment is probably the inexact information which has been furnished by several authors respecting the economical results of the patio process. This treatment is not suitable for silver-ores of every kind. Simple sulphides of silver are best adapted to it, and, next to these, the combinations of complex sulphides, viz., pyrargyrite, polybasite, stephanite, proustite, etc. Chlorides, bromides and iodides of silver are considered rebellious ; argentiferous galena, blende, bournonite, as also argentiferous arsenical pyrites of iron and copper, are absolutelg unsuited to this treatment. Experience has proved that high-grade ores do not give as satisfactory results as those of mediurn grades, as, for instance, carrying from 1 to 2 kilos of silver per metrical ton. The patio process, as actually practiced in this district, comprises the following operations: 1. The ore is crushed in a dry state in a roller-mill, reducing it to pea-size, from which uniform samples, and, in consequence, correct assays, can be obtained. 2. It is then thrown into the arrastra, and pulverized with water, so fine that it will pass through an 80-mesh screen.

Jan 1, 1900

W. L. Saunders, New York, N. Y. (communication to the Secretary*):—The Laramie tunnel, though a small one, compares very favorably in the speed of driving with the great Alpine tunnels which have the record so far. I think it safe to say that, taking all things into consideration, the record made at Laramie is the best American record, though it still falls short of the long-tunnel records abroad. In discussing tunnel-records it must always be borne in mind that there are conditions peculiar to each individual tunnel job, so that no comparisons are complete, fair and conclusive. At Laramie there is one point which stands out prominently, and which distinguishes this from any of the recently-built Alpine tunnels, and that is that here we have great progress in an American driven tunnel without the use of a carriage for mounting the drills. At the Arlberg and Loetschberg tunnels, the carriage was an essential condition for progress. All the heading-drills were mounted upon a bar which rested upon a small carriage. This carriage was withdrawn after the drilling and run into the heading after the blast without much disturbance of the drills, and with very little adjustment except that required in jacking the horizontal bar across the tunnel. The carriage was so small in its track-area that it required little mucking to run it in to the face; and as the rock-drills used were heavy machines 38 in. in diameter, progress in setting up and drilling was very much accelerated by the use of the carriage. At the Laramie tunnel hammer-drills were used instead of piston-drills, and here we have an important distinction which

Jan 1, 1913

By Gerhard Derge

A SERIES of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.1 There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. EXPERIMENTAL PROCEDURE The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938