Search Documents

By John E. Udd

Introduction During the very long period in which man has mined minerals from the crust of the earth, falls of ground and collapes of under- ground workings have been the causes of a significant part of those accidents which have resulted in either death or in injury. At present, because of improvements in the approaches to the design of underground structures, in equipment, and in attitudes towards accident prevention, the proportion of accidents due to instability of rock is probably far less than it was historically. Nonetheless, in spite of the many advances which have been made, instabilities still account for about one-quarter of all fatalities, and one-tenth of all of the injuries, in the minerals industry. The means must be found whereby both the numbers of accidents and the accident rates due to falls of ground can be reduced to the lowest levels possible. At the outset it should be stated that, short of suspension of all mining activity, it will probably never be possible for us to eliminate accidents completely. Most human enterprise involves unknowns and risks, and mining is no exception. A certain number of accidents, then, must be viewed as the inevitable consequence of our attempting to work with unknowns and to make decisions that involve uncertainties. However, in retrospect, many instabilities can be attributed to factors which could have been within our control. The preventable accident must be eliminated. It should be our goal that we make every effort to direct our skills and technology to the creation of a safer working environment and should be constantly striving to

Jan 1, 1983

By John Fulton

The following table shows the shipments from the four Lake Superior iron-ore districts during the year 1887, and their total outputs from their beginning until the close of 1887.* It will be noted that the Menominee district is second in importance in its total output tonnage to the close of the year 1887. These ore deposits are found in jasper-slates and in the horizon between these and their associated clay-slates; in the latter they are true contact-deposits. They are found in this jasper- and clay-slate formation under varied conditions, yet, in all, certain characteristic laws are preserved. The angle of dip varies from 15° to 20°, and up to 85° and even 90°, with the horizon. The ore is rather soft, bluish-black in color, and is a hematite. It varies in thickness from a few inches to one hundred feet, or more. It is mainly "Bessemer" ore, containing 57 to 63 per cent, of metallic iron, and .03 to .07 per cent, of phosphorus. In the mining nomenclature of this range two conditions of the ore-lens are described by the terms "dip" and "pitch." The former is in common use in defining the relation of the ore-plane to the horizon ; the latter indicates the posture of the ore-body as it inclines east or west from its position at the opening of the mine. In the

Jan 1, 1888

By Brigitta Hassler

INTRODUCTION In the early 1960's research was begun in Sweden to improve the agglomeration of our domestic iron ore concentrates (5). Different agglomeration methods that were used in the building material industry were studied under the economic support from the Swedish Technical Council, the Swedish Board of Technical Development and by the Swedish industry. The research work was performed at the Division of Mineral Processing at the Royal Institute of Technology in Stockholm. All known agglomeration methods were reviewed and the methods were developed to produce superior quality agglomerates (6). The term cold bonding (in contrast to sintering) was introduced to describe the induration operation in these processes and this has been accepted internationally. Even though we used it mostly for steam autoclaving methods, it has come to describe a class of processes that use binding methods by pore filling. Schumacher in Germany discovered around 1907 that a strong material can be produced by mixing slaked lime with fine ground quartz and subjecting to a steam atmosphere under pressure at about 185ºC. This started development of lime-sandstone building materials and later on, in Sweden, the light-weight concrete. Schumacher also used the same reaction for briquetting iron ore concentrates by adding silica and lime, and autoclaving. The product seems to have been accepted for blast furnace burden and the process was used on an industrial scale until the 1920's. The sintering method has a small melting phase as diffusion medium and in the steam-autoclaving method a small quantity of water condensate at about 200°C serves the same purpose. Thus the induration process by the hydrothermal hardening methods is similar to that of sintering or heat treatment.

Jan 1, 1977

By Felicia F. Peng

The computer graphic routines and digital simulation program of coal cleaning circuits have been developed in the Mineral Processing Engineering Department, West Virginia University. The functions of the program include computing, tabulation and graphing of 1) washability characteristics of raw coals, 2) blending, 3) Tromp distribution curves for two washer types-- water only and dense medium, 4) predicting the functional relationship of yield and qualities of clean coal product in individual and overall coal cleaning circuits in coal preparation plant, and 5) determining the optimal clean coal yield based on the market and environmental specifications. Amdahl 470 V/7A digital computer, Tektronic 4025 graphic terminal and Tektronix 4663 digital plotter with Fortran IV are used to achieve the goals. The simulation with the aid of graphic routine program of coal cleaning circuits is a useful tool for coal preparation engineers in evaluating the feasibility of proposed flowsheets, in investigating the effect of a modification in a unit operation of an existing plant, in analyzing the off-line optimization, and in comparing the alternative circuit control strategies. The coal cleaning process simulation with graphic routine can contribute greatly to the decision making processes of preparation plant design.

Jan 1, 1983

By W. A. Wissler, B. E. Field

COBALT is a silvery white metal with a slight bluish cast. It strongly resembles nickel in its appearance and properties, notably its resistance to corrosion, although its alloys with other metals differ decidedly in their properties from those of nickel. The name "cobalt" was derived from the German Kobold, meaning goblin, and this came to be applied to the cobalt minerals which, although they resembled ores, did not readily yield metal when smelted by the primitive processes available in the Middle Ages. Cobalt minerals were used as pigments by potters and glass- workers before the Christian era. Cobalt blue glass was found in the tombs of the Egyptians and in the ruins of Troy, and many colors used by the ancient Greeks and Romans contained cobalt. The ancients were entirely unaware that the colors they used were caused by cobalt and the metal itself was not isolated until about the middle of the eighteenth century, by Brandt, although the preparation of cobalt compounds had been carried on in a small way ever since the opening of the silver-cobalt deposits at Schneeberg, Germany, in 1470. By the middle of the nineteenth century, several firms in England were engaged in the refining of cobalt products and the consumption of cobalt oxide in the British ceramic industry in the year 1866 had reached 67,000 lb. COBALT METAL AS A NEW RAW MATERIAL IN ALLOY TECHNOLOGY Nickel and cobalt are usually found together and, although the relative amounts of the two have varied greatly in different ores, those

Jan 1, 1953

By C. C. RAE

The Texas Panhandle produced 18,677,000 bbl. of oil in 1932 as against 25,064,000 in 1931. The decline was caused by smaller market demand, since the Railroad Commission potential increased from 105,528 to 149,260 bbl. during the year. Well Completions, 1932 The development during 1932 compares with 1931' as follows: Year Wells Drilled Dry Holes Gas Wells Oil Wells Initial Pro- duction, Bbl. 1931 200 6 77 117 347 1932 136 18 28 90 603 Crude oil prices, small market demand, and lower allowable rate of production caused less drilling. Expiration of leases was one reason for a greater number of dry holes through forced drilling of questionable areas. The small number of gas wells reflected the influence of the business depression upon industrial and domestic gas demand, together with difficulties of franchise negotiations or pipe line extensions under present conditions. Probably much of the gas-well drilling was done on expiration leases, or to protect against drainage, and equalize withdrawals as between the various units held by each gas pipe line company. The increase in average initial daily production was due chiefly to excellent granite wash wells in the LeFors district developed by the Texas Co. and Skelly Oil Company. In the Panhandle district, comprising a major anticline with almost a million productive gas acres, the pools tend to merge in time, the development being confined to more productive areas. Hence separation into pools becomes a matter of time of development with some effort to keep dolomite, archosic and granite wash production separate. Many pools, like the Finley and Bowers, have mainly one type, but many leases and even individual wells produce from two zones. The oil production is usually closely associated with sea level, where proper porous formations

Jan 1, 1933

By F. Keeler, C. M. Craighead

Aluminum alloys containing magnesium and silicon are susceptible to strengthening and hardening by suitable heat-treatments, and they constitute a class of alloys of considerable commercial importance. Generally, they contain these two elements in the proportions required for the formation of the intermetallic compound Mg2Si, or an excess of silicon; no commercial wrought alloys are made with an appreciable excess of magnesium. The reason for not having excess magnesium is obvious from the results given in this paper, since it is shown that excess magnesium results in a proportional decrease in the solubility of Mg2Si. This is the eighteenthl of a series of papers from the Aluminum Research Laboratories dealing with the equilibrium relations in aluminum-alloy systems; most of the previous publications concerned binary aluminum-alloy systems; this is the fourth of a group pertaining to ternary aluminum-alloy systems. The work on this system was completed in 1930, but the results were not published because of the pressure of other work. Hanson and Gaylor2, in 1921, presented the results of an extensive investigation of the aluminum-magnesium-silicon system. Their results indicated that an excess of magnesium over the amount required to form the compound MgzSi caused a noticeable decrease in the solid solubility of MgzSi in aluminum. A more recent investigation3 in these laboratories showed that the solid solubility of MgzSi in aluminum was 1.85 per cent at 595' C. and decreased to 0.30 per cent at 300' C. The results of the latter investigation were used as the basis for the present work. The Present Investigation In the present investigation, a study was made of the effect of various amounts of excess magnesium upon the solid solubility of MgzSi in

Jan 1, 1936

By S. P. Ray, B. D. Sharma

THE activation energy values for self-diffusion in pure metals have been correlated with a number of physical properties such as melting points,1 valences,' Debye temperatures,3 and cohesive energy densities.4 Extending the melting point correlation, the self-diffusion activation energy values for the alloys can be similarly correlated with the solidus temperatures. For metals and alloys which exhibit phase transformations, such a correlation is not feasible because of the uncertainty of various physical properties of the corresponding phases. Using thermodynamical approach, Ardell5 calculated the hypothetical melting points of the low melting phases of the polymorphic metals. However, these calculated melting points do not show reasonable correspondence with the activation energy of self-diffusion. Recently, a new approach treating metals and alloys as electron concentration phases has been developed by Engel6 and Brewer.7 These workers have attempted to correlate the crystal structures with the electron configurations of the atoms existing either in ground state or in an excited state of low promotion energy. The basic postulate of this theory is that whereas the contribution to the bonding of the metal comes from the interaction of both d and (s-p) electrons existing either independently or in hybridized states, the existing crystal structure is controlled by the (s-p) electrons alone. Specifically, a metal is supposed to crystallize in bcc, hcp, or fcc phase provided the metal has one, two, or three valence electrons per atom in the (s-p) configurations. The diamond, or ZnO and ZnS structures, occur with four (s-p) electrons per atom. Secondly, the contribution of d electrons to bonding is supposed to increase with atomic number

Jan 1, 1970

By C. L. Dake

Iron is much more soluble in the ferrous than in the ferric form. Where, as in the case of the ferrous silicates and. the sulphides, the iron is already in the ferrous form, it may go at once into solution and be removed, upon the breaking down of the parent rock. If in the ferric form, it must first be reduced; usually by the decay of organic matter, the demand of the decaying carbonaceous matter for oxygen being so great that the latter is abstracted from the ferric compounds and the iron is thereby reduced and rendered soluble. The iron may go into solution as the sulphate, or in the presence of excess CO2 as ferrous carbonate. It is probably soluble as salts of the organic acids.' Recent work indicates that these are important in the formation of bog ores.2 There is considerable variety of opinion concerning the behavior of these organic compounds.3 The secretions about the roots of plants and trees also cause the solution and removal of iron and a consequent bleaching of the soil,4 While the matter is not yet well understood, we can probably say definitely that the so-called organic acids are a group of colloids which possess slightly acid properties, and the salts of which are partly soluble and partly insoluble.5 Their iron salts readily change from the ferrous to the ferric form, and their solubility is greatly modified by the presence of ammonia.

Jan 1, 1916

By Fred Bond

WHEN some materials are ground dry in a ball mill, a stage of comminution is reached at which the finely divided particles begin to adhere to the balls and to the mill lining. As grinding progresses, a coating accumulates upon the grinding media, which tends to cushion the impacts and thus retard reduction of the material, and finally becomes so thick that all grinding ceases. At this stage, the characteristic noise produced by the grinding media dur-ing normal mill operation changes to a dull, muffled sound. In most instances, the formation of the coating marks the practical limit of size reduction. Industrial requirements for fine grinding frequently meet with this obstacle, and the tendency in many com-mercial operations to grind materials to a higher degree of fineness than formerly makes the solution of this problem an im-portant one. The phenomenon is of far greater importance, therefore, than the limited amount of research and technical discussion devoted to it implies. In order to learn more about the coating of different materials when ground dry to a high degree of fineness, certain labora-tory tests were made from which it was found that different materials form coat-ings at widely different size distributions. It is probable that most materials will coat if they are ground fine enough; the exceptions have inherent lubricating qual-ities, like coal and graphite.

Jan 1, 1940

By F. E. Marcy

IT is not my purpose to write a lengthy article or to attempt the solotion of the problem I am presenting, but to call attention to what I believe an important issue, hoping that it may arouse in some one, or in some company, a sense of responsibility. I am referring particularly to modern up-to-date milling plants discharging tailings which under existing conditions cannot be further treated or from which a recovery cannot be made at a profit, but where a quantitative and qualitative analysis shows that a portion of these tailings might profitably bee treated, at some future time when our metallurgical knowledge has advanced, when we have cheaper power, chemicals, labor or other advantageous conditions. Early Methods In our early milling methods very little attention was given to the care of tailings. It was thought that if the mill could be located by a stream or a river where the final disposal of the tailings could be forever lost sight of, it was highly desirable. We can now see acid estimate what was lost in these rich tailings, not recoverable from the streams and the great rivers. Fortunately for many, the depositing of tailings in these streams and rivers was objected to by the farmers and finally prohibited by the State Legislatures. In looking back over our past milling methods, it seems that, the first endeavor was to make the maximum amount of money for a particular period, or year, regardless of the future, the depletion of the mine, or the conservation of the total mineral content. The dumping and sluicing of 3,000 tons per day, for a period of many years, of a copper tailing carrying

Jan 8, 1917

By R. J. Jackson, D. E. Williams, W. L. Larsen

The phase diagram of the Ta-Zr system is presented with a discussion of the methods used in its determination. The solidus contains a minimum at 1820°C near 25 wt pet Ta. A complete solid solution exists at elevated temperatures between tantalum and ß zirconium. This solid solution decomposes monotectoidally at 800°C and 12 wt pet Ta. The maximum solubility of tantalum in a zirconium is slightly less than 2 wt pet, and decreases with decreasing temperature. The solubility of zirconium in tantalum is 5 wt pet at the monotectoid temperature and about 2 wt pet at room temperature. THIS investigation was part of a program of research on refractory metal alloy systems having potential application in nuclear reactor technology. Preliminary prop-ess has been reported in the Ames Laboratory annual research reports.l Most of the previously reported work on the Ta-Zr alloy system consisted of partial phase diagram investigations and the determination of the mechanical properties of the zirconium-rich alloys. Anderson eta1.2 studied alloys containing up to 30 wt pet Ta as part of an investigation of several zirconium alloy systems. These investigators also determined some of the mechanical properties of the alloys at room temperature and 650°C. In a discussion of Anderson's work, Pfei13 suggested that the bright phase in the microstructures of the intermediate alloys is a tantalum-rich solid solution or an intermediate phase in a matrix of ß zirconium solid solution. Litton,4 Keeler,5 and Chubb6 determined the mechanical properties of zirconium-rich alloys at ambient and elevated temperatures. Van Thyne and McPherson7 reported the tensile properties

Jan 1, 1962

By J. J. K. Daemen, C. Fairhurst

Introduction The stress field around a supported tunnel can be considered as being composed of: i) the virgin (pre-mining) stress in the rock ii) the (elastic) change in this stress field caused by creating the opening iii) the (time-dependent ) change in the stress field produced by (i) and (ii) as a section of the rock breaks up iv) the (time-dependent) influence of the stress build-up in the support. Several authors have examined the conditions necessary to produce static equilibrium between the support, the rock, and the regional (in-situ) stress field. The analysis used by Labasse (1) is typical. Consider a circular tunnel radius R in a hydrostatic stress field (P), and a radial pressure pi exerted by the support. According to Labasse, the radius ‘b’ to which the rock will break* for a given support pressure, pi, can be calculated from: - the equilibrium equation: [ ] As a zone of broken rock develops around the opening, the stress circle for a point on the elastic-broken rock boundary moves to the right in the Mohr diagram until the radial stress in the broken zone s equal to the radial stress in the elastic zone.

Jan 1, 1971

This study of engineering education arose out of the action of a joint committee on engineering education, representing the principal engineering societies. The committee had gathered so much material that it decided the work could best be carried out by some one trained in applied' science, who would devote his entire attention to the study.. The Carnegie Foundation therefore asked Prof. Charles R. Mann, of the University of Chicago, to undertake the work. After making a thorough study Prof. Mann has made a most comprehensive report. In it he says: The engineering schools of the United States began their work upon a definite teaching plan and one that had at least pedagogic consistency. But during the past half century the course of study has been overlaid with many special studies intended to enable the student to deal with the constantly growing applications of science to the industries. As a result, the load upon the student has become so heavy that there is a feeling that the students fail to gain a satisfactory grounding in the fundamental sciences and do not fulfil the expectations of engineers in d manufacturers in dealing with the practical problems with which they are confronted on leaving school. At present 60 per cent. of those who enter the schools fail to graduate, still many of them persist in engineering and make a success of it. It is evident, therefore, that the present systems of admission are not satisfactory. If a group of schools will take up the careful study of their entrance systems and experiment with objective tests and records of the students' youthful interests and achievements, the percentage of elimination can be reduced to at least a fourth of its present size, with an enormous saving of time, energy, and money for both student and school. The number of required credit hours per week should be less than eighteen, preferably sixteen. The few experiments that have been made indicate that college students do their best work when not more than five subjects are studied at a given time.

Jan 1, 1919

By W. Rostoker, H. Nichols

The embrittlement by mercury of aluminum alloys in various states of anneal, cold work, and aging has been studied. It is shown that single phase and non-precipitation hardened structures irrespective of de,pee of prior cold work demonstrate some small measure of yielding before fracture occurs. Sub-yield-stress failure is confined to the aged state, and embrittlement is accentuated by small plastic prestrains. With large plastic pyestrains, embrittle~nent is progressively reduced. In previous work' it was shown that the propensity of commercial aluminum alloys for embrittlement when wetted with mercury seems to be related primarily to the intrinsic strength in the normal un-wetted condition. The data from a large number of commercial alloys in various states of anneal, cold work, and/or aging gave a generalized relationship. At low strength levels, the wetted fracture strength increases proportionately to the increase in tensile strength; but above 65,000 psi normal ultimate strength, the trend is abruptly reversed, and the wetted fracture stress decreases proportionately to the increase in tensile strength. This paper will demonstrate that the simple character of this relationship between normal tensile strength and wetted fracture strength is fortuitous. It will be shown that structure and thermal-mechanical history are clearly relevant factors. The term brittle fracture has been used to connote the geometry of the fracture surface (transverse vs shear plane) or the negligible extent of preceding plastic strain. At its maximum effectiveness, liquid metal embrittlement can satisfy both criteria—fracture transverse to the axis of tension and without observable plastic strain. In this paper, brittle fracture will signify failure at stresses below the engi-

Jan 1, 1962

By Fred T. Williams

The Park City mining-district is distinctively a camp of few properties, 5,000 acres, or one-third of the entire district, being under the management of but three companies. As a rule, the ore-bodies lie deep, with no outcrop, except where erosion has formed the deeper canyons and gulches. Ontario canyon exposed the famous Ontario ledge, and Woodside gulch showed the first ore of the Silver King Coalition mine. The Quincy ore-bodies were first brought to light in upper Empire canyon, and Thaynes canyon was instrumental in aiding the prospector during the early days of the camp. There are 22 shafts which have reached a depth of at least 500 ft., ten a depth of 1,000 ft., five a depth of 1,300 ft., and two a depth of 2,000 ft. The amount of lateral development has been proportiorlally extensive, including six long tunnels, four of which are in 3 miles, with a fifth now being driven. The Ontario lower drain-tunnel is now more than 4 miles long. The formations are sedimentary, dipping about 30° NW. and N., and traversed by many fissures, dikes, and faults. The principal ore-bodies are found. associated either with the contact of the basal Ontario quartzite and the overlying limes, or on a quartzite stratum within the limes, or in the fissures, or along some of the porphyry dikes. The district covers the intersection of the Uintah and Wasatch ranges, which explains the existence of large folds and faults, and fissures of great length, width, and depth. In a general way, the geology of the district consists of a basal quartzite dome, which has been exposed by erosion at the Ontario property. The Ontario fissure lies entirely within this formation. Flanking this dome on the west, north, and east lie

Jan 1, 1912

By D. C. McLean

This report summarizes the work that has been done during the past several years in adapting resins for use as auxiliaries in mine roof support. The resins were applied in two ways: 1) by injection into the strata, and 2) as a bonding agent for roof bolts and reinforcing bar. The Explosives and Mining Chemicals Department of the American Cyanamid Co. has worked during this period in cooperation with the Roof Control Research Group of the U.S. Bureau of Mines, the Pattin Manufacturing Co., the J. H. Fletcher Co., the Homestake Mining Co., the U.S. Steel Corp., the National Mines Corp. and the Pocahontas Land Corp. in an effort to create resin formulations and methods for applying them as a practical and sate type of roof support for mining areas particularly where conventional support is inadequate, yet expensive. This, work has involved much pioneering in a field where theory, speculation, and pure mythology predominates, and little basic engineering data is available. It is strange butt true that, despite the importance of roof control both from an operational and safely standpoint, there is scarcely a mining' company in this country that has an engineer, or anyone, assigned to the study of roof support problem, except temporarily--after a bad roof fall. The responsibility for improving roof control methods seems to have been placed entirely upon the shoulder, of the USBM, various State departments of mines, and individual roof bolt manufacturing; companies. It was in cooperation with the USBM that Cyanamid first developed resins for mining use.

Jan 1, 1964

Key elements of open-pit design fixing the ultimate pit limits are stripping ratio, pit slope angle, and grade cutoff. Results of exploratory and development drilling should be reduced to horizontal sections corresponding to level spacing. It is advisable to interpolate the actual drillhole values to a uniformly spaced 50-ft grid system. Vertical sections can be and are used to approximate the fixing of pit limits, but horizontal sections must be used to optimize a pit design. To develop a pit design requires the establishment of the break-even stripping ratio. This ratio is applied only at the surface of the final pit and must not be confused with the over-all ratio, which is always less; otherwise there would be no profit in the operation. The break-even stripping ratio is determined by the formula: [ ]

Jan 10, 1967

By Frederic E. Carter

THE history of all the civilizations of the Eastern Hemisphere is underlaid and interwoven with the story of gold. Great nations rose, welded by the hand of the conqueror, flourished gloriously because of the wealth of gold inevitably attracted to them, only to fall, either through the sapping of their original virility by the softer living their material prosperity made possible, or by wars made upon them by enemies who craved possession of what was theirs. Imposing fleets sailed the seas, seeking gold or tangible wealth that might be converted into gold. Men suffered untold tortures in its quest. It sent Columbus out into unknown oceans, caused the migration of hordes of people from our Atlantic to our Pacific seaboard in '49 and accelerated the final subjection of our last frontier, probably by as much as a century. The mystic may see both something sinister and something beneficent in this metal that has played such a tremendous part in the shaping of the destinies of men. It has showered blessings and taken them away. It "hath deposed the mighty from their seats and hath exalted men of low degree" and, sardonically, reversed the order yet again. Its peculiar color, its incorruptibility, and its rarity all have contributed to excite the imagination of all races of men. In the Eastern Hemisphere and now in the entire modern world, the predominant emotion excited by gold is avarice. But in the social and economic organization of the civilizations native to the western half of the world, gold has a far different history. Before the advent of the white man, these sun-worshipping peoples saw in the permanently

Jan 1, 1953

By W. A. LaVenue, W. M. Houston

Pebble phosphate mines of Florida have been established from south of Hardee County to north of the Georgia state line, a distance of over 200 miles. Mining has been carried out on an ever-increasing scale since 1885, but phosphate deposits that can be mined on the economical standards of today, are confined in a roughly circular area about 30 miles in diameter, generally within Polk and Hillsborough Counties, in the central part of the State. The phosphate deposit, which is in the Bone Valley formation of Pliocene age, is covered by Pleistocene terrace deposits of unconsolidated quartz sand. The matrix is composed of approximately 1/3 clay slimes, 1/3 silica sand and 1/3 phosphate pebbles. The phosphate usually occurs as rounded pebbles, ranging in size from about 1 in. down to approximately 400 mesh. The phosphate may vary from well-defined hard pebbles to soft weathered rock. The color and character of the phosphate will range from smooth buff pebbles to black and white "salt-and- pepper rock." The screen size distribution varies considerably between locations; the recoverable phosphate may extend down to the 400-mesh size in some areas, while in others the phosphate may cut off sharply at about 35 mesh.

Jan 11, 1962