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By Thirumalai, K.

Although the term "spalling" has long been known, Norton l first referred to its usage for the fracture or disintegration of materials subjected to rapid temperature changes. Spalling of ceramic materials at high temperatures has received attention in the past. Removal of the char formed during ablation in re-entry of space vehicles has been referred to as mechanical spalling. The first experiments to evaluate the process of rock fragmentation by thermal spalling were conducted by Stoces using a series of gasoline burners on the quartz veins of the Zinnwald deep mines in Germany. After the development of rocket-jet burners, the principles of 'thermal spalling combined with high fluid momentum found wide practical application in rocks. The well-known jet piercing process for drilling blastholes in taconite and for jet channeling in the quarrying of granite are among the more notable of these application^.

Jan 1, 1970

By S. J. CRAIGHEAD

IN 1912 the United States Smelting Refining and Mining Company made a large investment in a number of coal properties in Utah and in 1915 a subsidiary, the United States Fuel Co., was organized to take over these properties. Operations started in 1916 and the Company soon became, and remains, one of the major coal producers of the State. It now produces approximately one million tons of coal annually, which is about 22 per cent of Utah's output. The U. S. Fuel Co. owns large reserves of good coal and is in a position to expand operations with the industrial growth now taking place in the West. Traveling through the Western States, one is struck by numerous advertising signs portraying the picture of jovial Old King Cole of nursery rhyme fame. His rotund figure and beaming countenance are the symbols of Utah King Coal, the product of the King mine of U. S. Fuel Co. King Coal is a by-word of quality coal throughout all the Western States.

Jan 1, 1948

By A. Blake Caldwell

Tyrone-a complete mining and concentrating facility built by Phelps Dodge Corp.-straddles the Continental Divide where surface water on either side flows in opposite directions although all water is taken from and returned on the northwest side of the Divide. At the outset, Tyrone was saddled with a problem of an adequate water supply, and the Gila River some 23 miles distant appeared to be the logical source. This in itself presented a major obstacle to Phelps Dodge because of the distance water had to be pumped and because of an adverse head which had to be overcome between the Gila River and the two 4-million-gal-capacity terminal water supply tanks at the mill. Having acquired water rights on the Gila River and in order to control the seasonal fluctuations in water volume, the company built the Bill Evans, off stream, earth-filled dam. This reservoir will contain 2100 acre-ft of water when full and it was constructed by the Hamilton Construction Co. for Phelps Dodge. The dam impounds fresh water for the Tyrone plant's use and four vertical turbine pumps (4500 gpm each) lift the water 275 ft from the Gila River into the reservoir. Since construction, Phelps Dodge has optioned the lake to the New Mexico State Game Commission for recreational purposes. In addition to the lake, land around the reservoir has been optioned to the State Game Commission for public use. The lake has already been stocked with trout and by next summer some keepers should be available for the taking.

Jan 12, 1969

By J. E. Hilliard

Isobaric sections of the eutectoid region of the iron-carbon phase diagram have been exgerimentally determined at 35, 50, and 65 kb. The phase boundaries were located by metallographic analysis of specimens quenched after equilibriatwn at known temperatures and pressures. With increasing pres -sure a pronounced decrease in the solubility of FesC in austenite was observed together with a depression of the eutectoid temperature. These two effects resulted in a shift of the eutectoid composition toward a lower carbon content; at 65 kb the eutectoid was at less than 0.2 wt pct C. These results are in qualitative agreement with thermodynamic calculations. It has also been shown by calculations that Fe3C in contact with saturated austenite will be stable with respect to both graphite and diamond formation at all pressures above -3.5 kb. 1 HE investigation described in this article was part of a more general study of the effect of high pressure on transformations in Fe-C alloys. Thermodynamic calculations and exploratory runs made in 1959 at the start of the program indicated an appreciable change with pressure in the phase equilibria of Fe-C alloys. However, the calculations were not considered reliable enought to provide the quantitative information required for the interpretation of the effect of pressure on the kinetics of transformations. An experimental investigation was therefore made to determine a series of isobaric sections of the eutectoid region of the phase diagram at pressures up to 65 kb. EXPERIMENTAL PROCEDURE Materials. Seven alloys with analyzed carbon contents of 0.10, 0.20, 0.38, 0.60, 0.77, 0.93, and 1.20 wt pct C were prepared from Ferrovac" iron and high-purity graphite induction melted in magnesia crucibles under argon. The ingots were hot worked and swaged down to 0.19-in.-diam rod which was then centerless ground to a final diameter of 0.125 in. Samples for chemical and spectrographic analyses were taken from each end of the rods. The prin- cipal impurities were found to be Ni, Al, Co, and Si which were present in amounts up to 0.03, 0.02, 0.01, and 0.01 wt pct, respectively. Specimens were prepared by slicing the ground rods into pills 0.06-in. thick which were silver plated to reduce decarburization during the equilibration. Silver was chosen for this purpose because of its very low solubility for carbon and its mutual immisicibility with iron. High-Pressure Apparatus. The high-pressure runs were carried out in the "Belt" apparatus.' As shown in Fig. 1, this consisted of a cylindrical cell compressed between two Carboloy punches loaded by a uniaxle press. Radial support to the cell was given by the "belt" which was a Carboloy die heavily prestressed by a series of steel binding rings. Laminated gaskets of lava and metal separated the punches from the inner surface of the "belt". A cross-section of the high-pressure cell is shown in Fig. 2. Two specimen pills were located inside a resistance heater of 0.20-in.-diam Nichrome tubing. The ends of the tube were sealed with alumina and lava pills tamped in place after the

Jan 1, 1963

By Paul E. Rosten

Introduction This papers describes some of the latest improvements that have been incorporated or planned by the Cleveland-Cliffs Iron Co. to reduce operating costs and improve pellet quality. The Cleveland-Cliffs Iron Co. operates and manages mining, beneficiation, and pelletizing operations in Michigan, Canada, and western Australia. This paper deals with the grate-kiln pelletizing operations at Republic, Humboldt, Tilden, Empire, and Pioneer in Michigan, and the Adams and Sherman in Ontario, Canada. Table I characterizes each operation in regard to location, ore type, pellet capacity and date that pellets were first produced. All of the operations with the exception of Pioneer and Tilden, utilize downdraft-two-pass grate cycles of drying followed by preheating. Pioneer utilizes an all-downdraft, three-pass grate cycle which consists of three drying zones followed by the preheat zone. The Pioneer and Tilden cycles have been described previously (Lindroos and Koski, 1966; Villar and Dawe, 1975; Koski, 1977). Tilden utilizes a three-pass grate cycle with a stage of updraft drying, followed by two downdraft drying stages. Recuperation systems which supply hot gases to a drying zone from second stage cooling were designed and fur¬nished for Tilden I. Tilden II will be identical. Empire IV will also be furnished with a recuperation system. The Adams grate¬kiln system was retrofitted with a recuperation system. This paper will summarize some of the efforts that are in effect or planned for grate-kiln pelletizing systems to: (1) reduce operating and maintenance costs, (2) reduce energy requirements, (3) improve product quality, and (4) meet environmental standards.

Jan 1, 1981

By A. W. Fahrenwald

Flotation practice in Idaho is now about 13 years old. The advance has been steady during these 113 years. The operators have been alert to take advantage of the newest developments and they have themselves made a constant effort to improve their work. The metallurgical improvements are due to the development of (1) better equipment, (2) better reagents, and (3) better understanding and control of the process. During the eight years the writer has been in this district, there has been continuous experimentation by several companies to improve the ore dressing by flotation methods. Gravity concentration has fought hard to hold its place, and although it is true that gravity processes have been improved during this period, nevertheless, in several of the important mills of the district the few tables that managed to hang on have finally given way. On the straight-lead ores, tables and jigs are still used; and, due to better classification, their hold on this job has been strengthened. Ores of the District The ores of the district are of two general classes: (1) clean lead ores, such as those from the Bunker Hill and Hecla mines, and (2) complex lead-zinc ores. The general impression prevails that the clean lead ores, class 1, are simple and that it is easy to obtain high recoveries and good grade products. This, in a way, is a false impression; there is quite a high percentage of locked middling in these ores at 100 and' 150-mesh sizes. Improved classification preparatory to table treatment of this type of ore has made it possible to segregate effectively a high-grade middling which is further comminuted and floated. The complex lead-zinc ores of the district, of which the ore from the Morning mine of the Federal Mining & Smelting Co. is a typical example, always have presented a difficult problem. It always has been comparatively easy to make a clean lead concentrate, but it never has been possible to concentrate sphalerite with a specific gravity of 4.10 from siderite of gravity 3.88. Also, a large percentage of the galena and sphalerite of this class of ore refuses to separate out until the crushing has been carried

Jan 1, 1928

By David W. Brunton

I. INTRODUCTION. THE list of our past-Presidents comprises the names of runny who, in their official addresses, have sketched the current progress of the arts and professions with which they were familiar. Such addresses are, in my judgment., highly useful, setting forth the results of our own work as a. society, and recalling to our minds the particular lines in which discussion would prove most fruitful. . Following this course with some hesitation, I venture to offer an outline of the recent improvements and the present situation in minim and metallurgy in the Western United States. The wonderful advances in mechanics, chemistry, and electricity have all combined to aid these arts to such an extent that. progress during the last decade has undeniably been more rapid than ever before in the history of the profession.. In all mining countries improved transportation-facilities, in many instances called into existence by the traffic created by the mines themselves, have done much- to enlarge the. field of operations by the reduction of freight-, operating- and living-expenses, thereby bringing lower-grade properties into the producing class. Under normal' conditions, as the age of a district in¬creases, all these differentt factors should combine to off-set. the augmented costs attendant on deep mining, and greatly tend to prolong the profitable life of the mines. The more recent and important improvements in our Western mining-practice which have contributed most toward the advancement of the art may be briefly summarized as follows; but, before beginning this portion of ray address, I wish to thank most heartily the many engineering friends who have so

Sep 1, 1909

By S. F. Radtke

The properties and characteristics of lead and zinc have made these metals useful to man in many ways since the days of antiquity. Despite their long history of use, however, these metals have proved to be extremely resilient and responsive to modern needs. New alloys and compounds continue to be developed, adding to the growth of these metals. Consumption data is given for 1969 and compared with one and two decades ago. Trends in major markets also are cited and explained. Uses for lead and zinc which have come into prominence within the past few years are described and explained, with emphasis on the role played by the industry's cooperative research program. Current efforts in the research phase are discussed, with details given on major efforts for both metals, including new alloys, process developments, applications research, finishes, coating, paints and pigments, batteries and fundamental research. A forecast is given of promising new areas and a projection made on a longer term of new applications that may emerge from current research.

Jan 1, 1970

By H. M. Woodroffe, H. K. Conn, S. J. Rice

World production of asbestos is estimated to be at a current level of almost 3.5 million tons, having more than doubled in the past ten years. A substantial part of the increase has been due to a rapid expansion in the Soviet Union. Production from that country during 1964 is estimated at 1.5 million tons and, as a consequence, Russia has displaced Canada as the leading world producer. Although traditionally the asbestos mining industry has been centered near Sverdlovsk in the Urals, two new producing areas have been under development for some time. It is expected that a new mine will be in operation in 1965 near Kiembi, Kazakhstan, some 300 miles south of Sverdlovsk, and an- other mine at Aktrovak in Tannu-Tuva, west of Lake Baikal. These developments will provide a significant increase in the production capability of Russia. Although internal consumption is expected to increase with the addition of new asbestos- cement producing facilities now under construction in Russia, there is some speculation that exports will also increase.

Jan 2, 1965

By CLAYTON C. BALL

In the year 1948, more than ever before, the coal industry established itself on the threshold of a new and exciting future expansion. While production did not equal the wartime and peacetime peaks of 1944 and 1947, it was, in review, a good coal year. During the latter part of the year a combination of mild weather, record stock piling, and general business slackening reduced coal demand to the extent that marginal mines suspended operations, while mines remaining active found it necessary to renew their attention to producing better products at lower operating costs.

Jan 1, 1949

By AIME AIME

CERTAINLY in point of attendance, and doubtless in several other ways as well, the 147th meeting of the A.I.M.E. was the best ever held. In times of depression, mining engineers and metallurgists have plenty of time to come to the Annual Meeting but money is scarce; at the height of industrial activity they have plenty of money but no time. "The current period of transition seemed to provide ideal conditions for' both the preparation of papers and attendance at their presentation. The weather made even the Californians present envious though the weather man gets no credit, for rain and snow was what he willed. Among the elevator men, the miners have the reputation of being the toughest crowd to handle, though the best natured, withal, of all the engineering groups that meet in the Engineering Societies Building. This year Your inquiring reporter was told, "it was the damnedest meeting I ever saw; they

Jan 1, 1937

By Clarence P. Linville

(Pittsburg Meeting, March, 1910.) IT is recognized that, in all metallurgical operations, the greatest possible uniformity in all conditions is essential to the best results. It is the constant aim of metallurgists to secure this uniformity, and their success in this respect has been in many cases the cause of great advances in the metallurgical processes themselves. Of all such processes, the production of pig-iron in the modern blast-furnace is perhaps the most complex and the most difficult of control. Notwithstanding the great progress of recent years, there is still great difficulty in obtaining anything like uniform conditions and results in the manufacture of pig-iron. The reason is not far to seek. The ores vary in composition and physical properties, often carrying a varying amount of gangue material, unevenly distributed The coke may vary in composition, cell-structure, moisture, hardness, and other properties. The blast, the weight of which far exceeds that of any other constituent, varies in its moisture-content and consequently in its chemical composition ; and its temperature, by reason of the method of heating, is not uniform, but, besides varying from time to time with atmospheric and other outside conditions, has a maximum and minimum for every changing of stoves. Now, with regard to these variations, the modern demand for uniformity has been greatly aided. Chemical analysis has made it possible to select ores so that the composition of the charge can be kept fairly constant; coal may be obtained from a given field, and coked in the same kind of ovens under conditions which . make the fuel practically uniform ; the Gayley

Mar 1, 1910

By M. R. Geer

Coal washing assumed an important role in the mining industry of the Pacific Northwest long before washing practice became firmly established in the Appalachian field. A Scaife washer was operated in the state of Washington in 1887; and by 1927, the fist year for which complete statistics were compiled, nearly a third of the state's coal production was washed, in comparison with only about 5 pct for the country as a whole. Mechanical preparation was adopted in Alaska in 1922 in a plant constructed by the United States Navy at Chickaloon to provide bunker coal for naval forces operating in northern waters. Many of the coal beds mined in Washington and Alaska contained more impurities than those mined elsewhere, and this circumstance contributed to the early interest in mechanical cleaning. A much more important factor, however, was the inclination of the coal beds. With steeply pitching beds, hand sorting by the miner at the face is impossible; consequently, all material must be loaded and dealt with on the surface, just as is now proving the case with mechanical mining of flat beds. Thus "full-seam" mining afforded the same stimulus to the early development of coal washing in the Northwest that - it is providing under mechanization in the rest of the country today.

Jan 1, 1949

By Howard H. Fields

Any mining engineer with a desire to operate independently, with some financial backing, and with no fear of heavy responsibility and long hours, should be able to make a comfortable living in Mexico. Barring a few inconveniences such as a lack of satisfactory liability or accident insurance, the difficulty of obtaining repair parts or vehicles, and the length of time required to receive returns from shipments, the operation of small mine is not at all difficult. It is, in fact, a little easier to find a good prospect in Mexico than in the U.S.

Jan 1, 1950

By George H. K. Schenck

Diminishing returns in management's fight to lower manufacturing expenses have added luster to savings that can be achieved in delivered costs through creative management of the distribution function. This is especially true for companies engaged in the production of bulk commodities, for which transport costs may represent 25 to 50% or more of total delivered price, A. E. Cascino, vice president of International Minerals and Chemical Corporation, recently gave an example of why top management in his firm is concerned with distribution: "The price of a ton of phosphate rock, f.o.b. mine, is about $7. The cost of warehousing, freight, and handling frequently totals an additional $11 . . . . If one of our competitors . . . discovers a way in which he can cut his distribution costs by $3, we're dead! Even if we wanted to offset our competitor's more efficient means of shipping with reduced f.o.b. price for our product-we don't have that much profit margin . . . ." In a special report on the revolution now occurring in transportation of goods, Business Week stated in its September 24 issue: "Moving and storing goods on their way from mine and mill through various sub-assemblies to their final markets costs anywhere from $50 billion to $75 billion a year- $100 billion if paperwork costs are included.

Jan 1, 1967

By Colin G. ink

OUTSTANDI'NG in progress among the less familiar 'metals during 1936 is the electrolytic production of 99.9 per cent manganese meta1 readily and many quantity. Strictly speaking, manganese should not' be classed as 'a rare metal, since there is 800 times as much manganese in the earth's crust as there is zinc or lead. But manganese' as a metal is rare, just as titanium metal is rare though titanium is five times as abundant in the earth's crust as manganese.

Jan 1, 1937

By Andrews Allen

WE all remember when, a few years ago the preparation of coal was nothing but a matter of having somebody at the face or somebody in the railroad car pick out the impurities; also the sizes were generally' made" over a bar screen. Anything that was black was coal; and the only matecia1 picked out was the slate or rock-impurities that could be distinguished by eye or by hefting. This was all right as long. & coal could be sold at. a good price. After all, we are all in business to -make the most money honestly out of a certain acreage of coal and a certain plant. For this purpose what is required is the greatest possible recovery of marketable coal and the highest market price.

Jan 1, 1929

By N. V. Hansell

l. INTRODUCTION. THE last few years have shown an increasing interest in the subject of beneficiating iron-ores -in all iron-producing countries. In the United States, this movement has been slower than in certain parts of Europe, for the obvious reason that the abundance and relative cheapness of the Lake Superior iron ores has hindered the development of enterprises for the preparation of low-grade ores. Gradually, however, conditions have changed. The world's consumption of iron is increasing enormously. Being in 1900 about 40,000,000 tons, in 1910 ii was already 60,000000; and there is no reason to doubt that for the near future the increase in iron-consumption will continue at the same rapid rate, especially with, the development of China, certain parts of Africa, and other regions which have hardly been touched as yet by modern industrialism. It is. therefore, not surprising that apprehension is felt that the known available iron-ore resources of the world are gradually being depleted. Signs of this feeling are the recent investigation, under the direction of the U. S. Geological Survey, of the iron-ore resources of the United States, and the estimate presented to the last International Geological Congress, at Stockholm, Sweden, of the iron-ore resources of the world. These investigations have emphasized the fact that the known high-grade ore-deposits are limited in extent, and will, at a not distant future, be exhausted, compelling the iron industry to depend for raw material on the enormous deposits of low-grade ores which are distributed over almost all the world. The discovery of new deposits of high-grade ore, in countries not yet thoroughly explored, will not materially change this prospect. Of course, the part which such new deposits will play in the future cannot be forecast. The difficulty and cost of transportation will probably exclude many of them from use at the present centers of the iron industry.

May 1, 1912

By B. M. Larsen, K. Heindlhofer

Jan 1, 1945

By R. D. Begley, A. W. Khair

Introduction The technique being investigated here uses a physical mine model which consists of a plexiglass room-and-pillar model 11.4 x 11.4 cm (4.5 x 4.5 in.). It is placed at the bottom of a larger plexiglass box 25.4 x 30.5cm (10 x 12 in.). The box is then filled with a model material representing geologic overburden. Sand has been selected because of its deformability under gravitational forces. The mine model is capable of creating a cavity and induces movement on the surface of the model material. This surface disturbance can be measured using a photographic technique called holographic interferometry. This paper discusses results of an investigation of the possibility of generating subsidence criteria using physical mine models and laser holographic interferometry. Problem Statement Subsidence appears to be widespread in two states - Pennsylvania and Illinois - although serious subsidence is found in localized areas of numerous other states (HRB Singer Inc., 1977). The US Bureau of Mines estimates that more than 1618 km2 (400,000 acres) of urban areas are threatened by subsidence. Pennsylvania and West Virginia contain 57% of these threatened areas, with the remainder being spread out over 16 states (Johnson and Miller, 1979). Events of subsidence have been reported in urban areas, including Pennsylvania (Gray et al., 1977) and Illinois (Mahar and Marino, 1981). One location has observed three episodes of subsidence beginning in 1950 (Bruhn et al., 1981). These subsidence events all occurred over abandoned room-and-pillar mines. Some mines have been abandoned more than 50 years (Bauer and Hunt,1981) . Available research does not offer much on the problem related to time dependent subsidence, especially those associated with the failure of remnant coal pillars. The physical modeling technique developed at West Virginia University is capable of measuring both instantaneous and time delayed subsidence. Laser Holographic Interferometry Laser holographic interferometry, or holometry, uses the interference properties of laser light to measure small movements of objects. The object requires only optical access and no surface instrumentation. This technique is closely related to photoelasticity. Both techniques rely on the uniqueness of the light reflected off or through an object in any given state of stress. The entire measurement process is done remotely without any surface instrumentation and without using a camera. The interferogram is constructed and visual observation will yield fringes on all areas that yielded or moved. The displacement represented by one fringe was determined by Wilson et al. (1977) and is given by the relationship: [d ='1(1) 2 cos 8 where d = displacement of one fringe 6 = incident angle of laser light A = wavelength of light (632.8 x 10-9 meters for Helium-Neon lasers)] In summary, holometry is capable of detecting very small movements of objects under study. It is a very sensitive process that requires laser light and vibration free experiments. Experimental Program Lab Facilities The primary components of the facilities were the laser and the optical table. The light source was 50 milli-watt, Helium-Neon laser. The optical table was a granite slab weighing nearly one ton. All experiments were performed on the optical table. It consists of a large table sitting on air cells similar to car innertubes. Six air cells were placed on top of two layers of wood and Styrofoam. Figure 1 is a schematic diagram of the vibration free table. Even with these precautions, the experiments still had to be performed at night to reduce potential traffic related vibrations. Room-and-pillar mine models consisting of three different pillar sizes were constructed out of plexiglass. The models were designed to represent three different extraction ratios. Figure 2 shows the models. The extraction ratios were determined by the tributary loading concept (Peng, 1978). These models were the primary component of a seam extraction simulator. A schematic of this simulation device is shown in Fig. 3.

Jan 1, 1986