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At Black Lake, Quebec, Lake Asbestos of Quebec Ltd., a wholly-owned subsidiary of American Smelting and Refining Co., has opened a $36-million mining and milling operation which will produce about 100,000 tons of asbestos fiber a year and add 7 pct to the Free World's supply. The orebody once lay beneath Black Lake, and readying the ore deposit for open pit mining meant removing about 37 million cu yd of overburden- 30 million cu yd by dredging and pumping, and 7 million by power shovels and trucks. The enormous amount of material to be dredged, control of drainage during dredging, the need to cope with drainage problems in the area and to provide for flood control to replace the regulating effect of the lake, posed unusual engineering challenges and required tremendous capital investment.

Jan 1, 1959

By N. G. W. Cook

At present, tunnels can be driven in rock by either of two essentially different techniques, in one of which rock-breaking is accomplished by drilling and blasting and in the other by mechanical loading. The methods based on these techniques are comparable in terms of the rates at which tunnels may be advanced, although they differ widely in their range of applicability to different types of rock and lengths of tunnel. The method based on drilling and blasting has reached a high degree of development. It is applicable to even the hardest rocks and rates of advance in excess of 50 ft per day (fpd) are attainable. The main disadvantages of this method are that it involves a sequence of operations punctuated by blasting and that it is relatively uncontrolled, resulting in overbreaking the tunnel profile and damage to the surrounding rock. However, its flexibility, mobility, and low capital cost constitute real advantages in many situations, such as those involving short lengths of tunnel or low rates of advance. Tunneling machines based on mechanical breaking of the rock are a more recent development. They offer a continuous and controlled means of tunneling capable of rates of advance in excess of 100 fpd under favorable conditions. However, these machines weigh many tens of tons and consume several hundred horsepower, so that they are costly and lack mobility. At present, their applicability is limited to long tunnels in relatively soft rock where the high rates of advance and tunnel quality can offset their onerous capital cost. Many situations exist in which the superior quality of a machined tunnel and freedom from blasting would be real advantages, but where the rock is either too hard for existing machines or the length of the tunnel does not justify their capital cost: What are the possibilities of developing cheaper, more flexible, and mobile tunneling machines? Most existing tunneling machines fragment all the rock at the tunnel face to facilitate its disposal. If a machine were used to cut only the profile of a tunnel as one of a sequence of operations, it would be required to break

Jan 1, 1970

By C. W. Hall

Owin to its isolation and comparatively small tonnage, the Yoquivo district is not widely known; though financially important andgeologically, quite interesting. San Francisco de Yoquivo, the center of the mining district, is in the western part of the state of Chihuahua, Mexico; about 35 miles west of San Juanito, on the Kansas City, Mexico & Orient R. R. The town can be reached from the railroad by a good trail over a rugged country. The elevation of Yoquivo is 6500 ft., and peaks surrounding the town are 2000 ft. higher. The mining towns of Concheño and Ocampo are 25 miles northwest, and Uruachic is 20 miles southwest. The climate, temperate and healthful, is almost ideal. The rainy season begins in July and ends the latter part of September. There is usually, though not always, some precipitation in all months except April, May, and June. The mountains are covered with pine and scrub oak. Water, wood and lumber are plentiful for all ordinary purposes, and hydroelectric power is available for about six months of the year, when wood for steam power is utilized as an expedient. The district has been worked recurrently for over 60 years. The Yoquivo province lies on the steep western slope of the Tara-humara division of the Sierra Madre range of mountains. The province is traversed by many deep canyons, most of which flow west. The town is situated on the San Francisco arroyo, which makes a confluence with the Huevachic stream 236 m. southwest; the Huevachic in turn joins the Candemeña river farther down and these two drain the western flank of the Tarahumara mountains and form the headwaters of the Mayo river. The claims of the Yocluivo Development Co., which is the only organization in the district with a record of any considerable production, lie within an area roughly l½ m. square. Thc area extends from the San Francisco arroyo north, and from the Dolores arroyo west, and is confined to the andesite formation. General Geology The terrane about Yoquivo is composed of a series of Tertiary eruptives that consist of numerous phases of andesite and rhyolite, and

Jan 1, 1927

By Harold L. Hinds

The Homestake Ledge or Lead was discovered by Fred and Moses Manuel on April 9, 1876. They recovered a small amount of gold from the quartz outcrop, but, unfortunately, they were prospectors not hardrock miners. Their claim was sold to a group of experienced California mining men in 1877. These mining men incorporated their holdings as the Homestake Mining Company. This was the beginning of one of the greater gold mining enterprises of the Western World. Metallurgical operations progressed over the years from an eighty- stamp grinding circuit using amalgamation for recovery to the more complex circuit of today. The Homestake Mine, today, is an underground mine with the deepest winze reaching the 8,000-foot level. The ore is hoisted to the surface by two primary shafts, the Ross Shaft and the Yates Shaft. See Figures 1 and 2. It is crushed in three-stage crushing plants located in the headframes. From here, it is trammed to the mill fine- ore bins by electric locomotives. The Lead grinding plant milling circuit, known as the South Mill, receives ore from the crushing plant at minus 112 inch (Figure 3). This material is dumped into overhead fine-ore bins from five- ton rail cars. The fine-ore bins have a live capacity of about 3,700 tons. The South Mill bins can also be fed by a conveyor system which reclaims ore from an 80,000-ton capacity stockpile. This stockpile is built up from peak mining production periods and available surface low grade material. It is then reclaimed during low mine production periods. The grinding circuit at the South Mill consists of four rod mills in open circuit followed by four ball mills in closed circuit. Three of the rod mills are 6-foot by 12-foot Marcy's. The other is

Jan 1, 1983

By A. Rakshit, W. E. Kolb, Y. C. Kim

An IBM/XT microcomputer with 10 MB hard disk storage, together with automatic sensing capability of truck movements at several key locations in the pit, formed the core of this automatic truck dispatching system. System software is written primarily in MICROSOFT FORTRAN with supporting subroutines in MACRO assembly language. The software is designed to automatically monitor truck movement throughout the pit, to make heuristic assignments based on expected shovel availability and truck travel times, and to record production statistics. It is currently dimensioned to handle 50 trucks, 10 shovels, 10 dump sites, and three material types. Due to the lack of funds to purchase the necessary communications hardware, the work related to the automatic sensing of truck movements has not been performed to date. Otherwise, the system is fully operational on a realtime mode.

Jan 1, 1986

By S. W. Parr, F. B. Hobart

Studies relating to the behavior of coal toward oxygen may have for their purpose the determination of the fundamental factors that underlie spontaneous combustion, weathering and deterioration, and the general topic of storage, as well as those properties that have to do with the underlying principles of carbonization. There is also involved the possibility of developing information relating to the constitution of coal, or at least the chemical properties inherent in the type substances of which the coal is composed. It is the purpose here to record certain results bearing on this latter idea of the chemical properties that characterize the main constituents of bituminous coal. The avidity of freshly mined coal for oxygen has long been known. What happens to the coal or to the oxygen is not so clear. Is the oxygen absorbed or chemically combined, and what are the conditions as to time, temperature, texture, or components that are most involved in the phenomenon? If we subject a weighed quantity of coal maintained at a constant temperature to a current of oxygen, we may obtain three factors of interest—the weight increase of the coal, the weight of the water, and the weight of the carbon dioxide formed in the reactions involved at that

Jan 1, 1925

By Thomas P. Meloy, Duane T. Eppler

The science of particle shape analysis has expanded rapidly in the decade since precise numerical-statistical techniques were developed for use in characterizing the shape of closed forms. Use of Fourier descriptors permits shape to be quantified to whatever degree of precision is required. With this technique, particles and particle systems can be compared either on the basis of shape characteristics displayed by individual particles, or on the basis of aggregate shape characteristics representative of large samples of particles. Shape characterization work completed to date has shown that the physical characteristics of particle systems (porosity, permeability, strength, mechanical stability, chemical reactivity, and flow characteristics (viscosity)) are related directly to particle shape. Furthermore, it has been shown that particle shape is a function of chemical composition, process of formation, and post-formational history of the particle. In this light, particle shape analysis has potential applicability to a host of engineering and industrial problems encountered in processing particulate material. It can be used to optimize the efficiency of separation processes and particle feed systems, to trace particle pathways through processing systems, and to monitor the operation of specific processes, the wear of critical machine parts, and the quality of end products in processing systems. In this paper we discuss these specific applications of shape characterization to particle processing.

Jan 1, 1980

By J. W. Leonard, B. A. Donahue

A method is described for incorporating coal petrography into mining and preparation plant quality control based on conventional analyses. Complete analyses are made of each of the uniform and relatively distinct petrographic bands in a coal face. With this information it is possible to develop petrographic standardization curves. These curves permit diverse coal characteristics to be rapidly monitored by application of a few standard coal tests. Single seam quality control is discussed in this paper. Inquiries continue to be made about coal petrography, and specifically, about whether coal petrography should be applied more extensively in the coal industry. Coal petrography is the study of the distinct physical, optical, and chemical increments which make up the organic rock mixture which we know as coal. Petrography can be applied by any coal company or at any coal mine where conventional coal analytical facilities are available and where additional resources can be allocated for an increased number of determinations. This first paper of a two part series includes (1) a proposed conventional approach to single seam petrography based on the development of petrographic standardization graphs and (2) some informative and supplemental interrelationships involving coal characteristics developed as a result of this research. In the second part of this series, to be published at a later date, those petrographic characteristics of bands taken from many different coal seams located over wide geographic areas which can be closely related to each other will be considered. These findings will be examined looking toward the development of a comprehensive, conventional approach to coal petrography which can be used as a common basis for multi-rank petrographic standardization graphs. Implicit to the understanding of coal petrography is the well established fact1,2 that the individual analyses of distinct petrographic bands often differ widely from the average analysis which is used to characterize a whole coal seam. In fact, a distinct and minor banded increment of coal in a high volatile seam may actually be a medium or low volatile coal with an analysis similar to the average analyses of seams located in distant coal fields. During the mining of coal, much degradation is caused which tends to randomly scatter coal bands. The degraded, scattered, and physically separated constituents of distinct petrographic bands are processed side by side in the coal preparation plant as distinct petrographic fractions with particles grouped according to a narrow size range (which derives in part from common hardness), specific gravity, and-or surface chemistry. Tile data obtained from numerous analyses made on each of the bands of any given coal seam, although diverse, can be readily interrelated. Indeed, these interrelationships can be developed into a series of nomographs or petrographic standardization graphs to serve as a basis for developing a conventional petrographic* program. Thus, by analyzing one property (for example, ash) of a selected petrographic fraction collected or separated from the flow of coal in a preparation plant, it should be possible to estimate the other physical, chemical, and thermal properties of this fraction by referring to the petrographic standardization graphs. It follows that any or all petrographic fractions in the total coal flow originating from a single coal seam can be rapidly monitored for many properties on the basis of a single analysis run on each fraction. In recent years coal petrographic research has concentrated heavily on that phase of this work which involves microscopic reflectance measurements made at many minute and selected points on a coal briquette surface.3,4 Thus, the percentage of the total number of reflectance measurements that fall into each of a consecutive series of arbitrarily chosen reflectance classes are used to characterize coal. This procedure is analagous to using the face of a coal briquette to represent the reflectance characteristics present at the face of a coal seam. Moreover, by analyzing petrographic fractions of known and uniform optical properties it is possible to closely relate reflectance to other coal characteristics. For example, reflectance has long been known to be related to such

Jan 1, 1968

By Robert E. Ennis

This somewhat misnomered "continuous" face section is, in most mines today, still far from perfect continuity. Achieving uninterrupted flow of coal from the mining machine to the outside has been a long sought for goal. Clearly, the largest problem to be solved in continuous mining today is one of increasing the cutting time of the miner. Full machine utilization can never be achieved with the new high capacity miners as long as their performance is tied to that of the shuttle car. A recent development has proven, however, that truly continuous mining and haulage is possible. The Bell & Zoller Coal Co. working with the Research and Development Department of Hewitt-Robins Inc. developed and perfected a new mining system which offers advantages in terms of increased productivity at reduced mining costs and enhances the safety of personnel at the face. This new system involves the use of two pieces of equipment that form an unbroken link between the mining machine and the mine belt haulage system. These pieces are a Mobile Bridge Conveyor and an Extensible Panel Conveyor.

Jan 4, 1965

By H. H. Uhlig

IN our study of the mechanism of and the prevention of corrosion in stainless steels, it was considered of fundamental importance to obtain knowledge of the surface structure of such alloys. If corrosion resistance is due to a self-healing oxide layer, which like a paint film protects the underlying metal, it would be obviously relevant were the effort made to make the film less permeable and more adherent; for example, the surface might be expected to respond to an anodizing process, which is found successful in increasing the film thickness and corrosion resistance of aluminum. However, if passivity and corrosion resistance of stainless steels are due to another cause, the attack of the problem would follow another path. One of the most effective techniques for studying passivity and corrosion tendency is the measurement of the electrochemical potential. Not only can one determine by potential measurements whether a metal is active or passive, but also one can determine the degree of passivity and rate of transformation of passivity with time. Chemical media that build up or destroy passivity when in contact with the steel can also be classified by potential measurements. Something can be learned, too, of the effect of alloy additions such as molybdenum to 18-8, known to decrease corrosion of the alloy in chloride solutions. A study of alloys in previous investigations has sometimes included data on the electrochemical potentials. Tammann and Sotter1 measured the electrochemical potentials of alloys of iron-molybdenum and iron-chromium and reported the critical concentration of molybdenum or chromium at which passivity initiates. Strauss2 made similar measure-ments for the iron-chromium system. The electrochemical potential' has also been used to indicate carbide precipitated 18-8. In 18-8, heat-treated to precipitate carbide, active metal exists at the region of the grain boundaries, contrasted with passive metal within the grains, the active metal accounting for a resultant active potential. Several

Jan 1, 1939

By G. S. Rice, J. A. Davis

The Péchelbronn oil field is located in the province of Alsace, in the Rhine Valley, about 30 miles north of Strasbourg. It is approximately 4 miles wide and 12 miles long, extending from the villages of Lobsann on the north to Wintershausen and Ohlungen near Haguenau on the south. (See Fig. 1.) The productive area includes about 44,000 hectares (107,680 acres). The name Péchelbronn signifies "pitch-spring" or "pitch-fountain." The first exploratory galleries were driven in from the hillside in 1735; and in 1745 the first official concession was granted by the French government and the first pit sunk to a depth of about 30 ft. Extraction by drilled wells was begun in 1879, supplementing the mining operations, and during the next 10 years 200 wells were drilled to an average depth of 172 m. (568 ft.). The bringing in of two "gusher" wells, in 1882 and 1888, respectively, was followed by the abandonment of all underground work. Underground mining, with a view to increasing the production of petroleum by recovering the oil left in the sands after drilling wells, was resumed in 1916. This mining operation started by sinking shaft No. 1 to a depth of 150 m. (495 ft.). The underground developments were pushed during 1917 and 1918 and the annual production of the Péchel-bronn field was increased to about 50,000 metric tons or 350,000 bbl. On the signing of the Versailles Treaty the province of Alsace, which had been taken by Germany as the result of the war of 1870, was returned to France, and the proprietary rights were taken over by the French Government. Concessions or leases, which embraced all the known oil-bearing territory of the field, were granted to the present operating company, Mines de Péchelbronn. This company followed both the drilling and the mining methods of the previous company.

Jan 1, 1927

By Joseph A. Gill, Ernest A. Curth

The Government and Leeco concluded a cost-sharing agreement in 1976 to demonstrate longwall mining of a thin coalbed, 1 m or less, in a mine near Hyden, Ky. A premining investigation laid the groundwork for mine design and equipment specifications. Four- legged shields, a face conveyor, a stage loader and an in-web shearer were selected to operate on a 183 m face. Lengwall mining began in 1979 and initially was slowed by low mining height and equipment problems. A rock mechanics program provides early warning capability and criteria for future mine design. Monitoring of surface effects is included.

Jan 1, 1981

By D. W. Brunton

The maps of our large mines are usually prepared with the greatest care; and it is somewhat singular that, in compari~on with the great amount of time and money spent in surveying and platting, 80 little actual use is made of them. Almost the only purpose for which a completed survey-map is afterwards consulted, is the determination of the relative position of the different workings to each other, and to the boundary-lines of the property. After the completion of such a map, it should be made the beginning of another, and in most cases a far more important undertaking, namely, its utilization as a starting-point for a complete inventory of the company's underground possessions. The ordinary mine-survey map, being nothing but a record of what has been done, is, in one sense, only ancient history. To increase its value, such additions should be made as will render it a complete statement of the amount and value of ore in sight at any particular time, and a guide for future development. Comparatively little extra labor is involved in this undertaking, since the larger and most expensive part of the work has already been completed when the mine has been surveyed and mapped. The necessary additions consist in working out and platting on the maps, the geology of the mine as exposed in the workings, in such a manner that the geological survey may be of daily use in the development and operation of the mine. The first step towards the production of a geological map consists in tracing individual level-sheets from the general or composite map. The area to be included, outside of the property in question, will depend very much on local conditions; but, for geological, legal and commercial reasons, it should be extended as far as reasonably practicable. The scale to be

Jan 1, 1906

By T. A. Rickard

A knowledge of the principles of punctuation is essential to effective and intelligible writing, for the ease and pleasure of the reader, and even his understanding, may depend upon the choice and the placing of punctuation marks. To 'punctuate' is to mark with stops or points; the word comes from the medieval Latin punctuare (punctuatus), which in turn is derived from the Latin punctum, a point. The purpose of punctuation is to show the manner in which the writing is to be understood; to indicate the relations between parts of a sentence and between successive sentences. To some extent "it does for the eye what vocal stress does for the ear", but especially it marks logical relations. Some punctuation marks, such as those indicating admiration, exclamation, and interrogation, are rhetorical as well as grammatical, but most of the common ones are logical, or grammatical. My discussion will be confined to grammatical punctuation in ordinary writing. .'The problem of punctuation in text matter", as George Summey * says, "is to employ words, points, and paragraph breaks in such a way as to achieve at the same time clearness; proper distribution of emphasis, and the desired kind of movement." The criticism of the punctuation of a sentence or of a group of sentences is not final until the context, within the paragraph, is read. A paragraph is a sentence or a group of sentences forming an independent unit of the composition; it represents a unit of thought. A multiplicity of paragraphs produces a choppy effect; 'on the other hand, paragraphs of. excessive length are tiresome, because the belaboring of one unit of thought wearies the reader. The aim should be to

Jan 1, 1931

By Owen S. Roberts

During the design phases of a conveyor system, the question arises regarding the type of drive required for each application. The paper shows that the correct drive for any particular application is the one that satisfies the criteria established for that application in the most economical manner consistent with such considerations as site location, availability of spare parts, area environmental conditions, power supplies available, etc. Following discussions of various mechanical arrangements for the drives, motor types and their characteristics are considered along with the control means of modifying these characteristics to satisfy individual requirements. These characteristics are all illustrated graphically. After selecting the motor and its starter, control accessories and interlocking arrangements as applied to material handling systems are discussed.

Jan 1, 1973

By Rodolfo V. de la Cruz, Richard E. Goodman

Knowledge of the initial state of stress in rocks provides a key to the solution of many problems in rock mechanics. The initial state of stress is part of the basic data required for rational design of structures in rock, since its redistribution when engineering activities are conducted is a primary load on the rock portion of the engineering system. Knowledge of initial and subsequent changes in the state of stress is also relevant in the study of active faults and crustal strain. The purposes of stress measurements are not generally well served by methods which disclose only one of the stress components at a point. Recently, interest has centered on overcoring methods which though ex- pensive and difficult have the important advantage of yielding data on three or more stress components. In a previous paper, the authors introduced a new method-termed borehole deepening-based on measurement of the deformations that occur close to the bottom of a borehole when it is deepened by further drilling without overcoring.l The proposed method is at a disadvantage when compared with over- coring procedures in that the quantities to be measured are somewhat smaller and the measuring environment is more hostile. However, the borehole deepening method presents three distinct advantages in comparison with overcoring procedures: (1) Using the same borehole, both the initial and the subsequent changes in the state of stress can be obtained by borehole deepening. Stress changes with time are

Jan 1, 1970

FRIENDS of the late Charles F. Rand presented in 1930 a sum of money from which the income is available to support various phases of the work of the Institute in which Mr. Rand was so deeply interested. At present the fund amounts to $10,000. The specific terms of the deed of gift are as follows: "The fund collected to establish a memorial to the late Charles F. Rand shall be placed in the custody of the Board of Directors of the American Institute of Mining and Metallurgical Engineers, to be set up as a trust to be known as the `Charles F. Rand Foundation,' the income of which shall each year be applied to a distinct purpose to be decided upon in that year by vote of the Board of Directors. This purpose shall be such as to promote the general welfare of the Institute and to constitute a permanent memorial of the usefulness of Mr. Rand, who for many years gave unstintingly of his time and talents in its service.

Jan 1, 1946

By AIME AIME

In taking account of stock, on the occasion of the recent removal of the office of the Institute, it was found that pamphlet copies of the papers named in the list given below were on hand, in excess of the average number deemed adequate for future casual demand. Special reduced rates will be made for these surplus copies to members applying promptly. "First come; first Served." Author. Title. Ref. No. ASHBURNER, C. A. " Petroleum and Natural Gas in New York State." 273 MARTENS, A. "The Microstructure of Ingot¬ Iron and Cast Ingots." 626

Jan 1, 1907

By R. C. Nelson, T. L. Weaver, A. I. Michals

This paper describes the design and performance of an apparatus for making continuous nondestructive resistance measurements throughout a spool of fine wire. Highly reproducible results on clean and graphite coated tungsten and rnolybdenum wires from 1 to 9.5 mil are presented. A linear relation between resistance and wire weight (per standard length) was obtained on clean wires, but only on those coated wires with very uniform coatings. Results indicating a correlation between tensile strength, hardness, and resistivity are reported. THE increasing demand for greater uniformity in fine tungsten and molybdenum wires destined for use as mandrels, grids, and coils in radio tubes and as filaments in light bulbs has rendered inadequate the standard (sampling) approach to the control of wire diameter and other physical properties. This ap-

Jan 1, 1961

By M. Stuart, R. F. Down

The Copper flotation concentrate produced at Gortdrum mines contains about 1% Hg. This article deals with the treatment used to produce a substantially mercury-free copper concentrate. Metallic mercury is a byproduct. Nearly all the mercury in the Gortdrum concentrate is present in the copper mineral tennantite-tetrahedrite. This mineral is variably distributed throughout the ore body so that by selective mining it was possible to produce salable concentrate relatively low in mercury while the treatment plant was being built. Roasting was the only feasible method found for removing the mercury from the concentrate, and it was decided that this should be done in an atmosphere with limited oxygen. A multiple hearth furnace is used. Mercury soot is condensed from the gas stream and treated to produce prime virgin mercury. Problems were experienced at first with materials handling, oxygen control, cooling of the calcined concentrate, treatment of the mercury soot, and in the metallurgical accounting. Precautions were necessary to avoid health problems. The plant is now operating reasonably well. The value of the mercury produced does not warrant the cost of the plant but without it, the copper concentrate could not be sold.

Jan 1, 1975