Search Documents

By Sherwin F. Kelly

The Geophysics Education Committee was organized in 1938 and presented its first report at the A.I.M.E. annual meeting in February, 1939, at a session held jointly with the Committee on Geophysical Methods of Exploration. REPORT OF 1939 The first task the Committee set itself was to find out in which universities the subject of geophysics was being taught, and the manner in which such instruction was given. A questionnaire was drawn up and sent out to 147 universities in the United States, Canada, and abroad. Of these 100 replied. Their answers were then tabulated and analyzed, yielding the information summarized in the following pages. Two universities, Colorado School of Mines and St. Louis University, actually maintain departments of geophysics, while 3 Canadian and 31 American universities give courses on the subject. In other institutions, 45 in the United States and 5 in Canada, more or less extended reference is made to geophysics in lectures on other subjects. Altogether, there are at least 86 universities in the United States and Canada at which students may obtain instruction of some kind in geophysics. To enter the courses in geophysics given by 33 American universities, certain prerequisites are demanded, varying with the level at which the subject matter is treated. In analyzing the prerequisites, some assumptions had to be made: one year of college mathematics was taken to mean up to, but not including, calculus, while three years was presumed to embrace a course in differential equations. On this basis, 16 per cent require only elementary college mathematics, 40 per cent require differential and integral calculus, and 31 per cent require differential equations. A few demand even more advanced mathematics, while some list no prerequisite mathematics beyond high school. Evidently a student contemplating the study of geophysics should ground himself in calculus and differential equations. In physics, similar assumptions have been made as to time required in the subject. All of the universities giving geophysics require their students to take physics first, and 34 per cent require a standing in

Jan 1, 1940

By Sherwin F. Kelly

The Geophysics Education Committee was organized in 1938 and presented its first report at the A.I.M.E. annual meeting in February, 1939, at a session held jointly with the Committee on Geophysical Methods of Exploration. REPORT OF 1939 The first task the Committee set itself was to find out in which universities the subject of geophysics was being taught, and the manner in which such instruction was given. A questionnaire was drawn up and sent out to 147 universities in the United States, Canada, and abroad. Of these 100 replied. Their answers were then tabulated and analyzed, yielding the information summarized in the following pages. Two universities, Colorado School of Mines and St. Louis University, actually maintain departments of geophysics, while 3 Canadian and 31 American universities give courses on the subject. In other institutions, 45 in the United States and 5 in Canada, more or less extended reference is made to geophysics in lectures on other subjects. Altogether, there are at least 86 universities in the United States and Canada at which students may obtain instruction of some kind in geophysics. To enter the courses in geophysics given by 33 American universities, certain prerequisites are demanded, varying with the level at which the subject matter is treated. In analyzing the prerequisites, some assumptions had to be made: one year of college mathematics was taken to mean up to, but not including, calculus, while three years was presumed to embrace a course in differential equations. On this basis, 16 per cent require only elementary college mathematics, 40 per cent require differential and integral calculus, and 31 per cent require differential equations. A few demand even more advanced mathematics, while some list no prerequisite mathematics beyond high school. Evidently a student contemplating the study of geophysics should ground himself in calculus and differential equations. In physics, similar assumptions have been made as to time required in the subject. All of the universities giving geophysics require their students to take physics first, and 34 per cent require a standing in

Jan 1, 1940

By Werner Ostertag

A series of rare earth cobalt compounds of the composition RCoa (r = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Ev, Tm, Lu) has been prepared. The compounds crystallize in space gvoup R3m and are isomorphous with PuNi3. Except for CeCo3 and PrCo, the series shows decreasing- values of a. and co. The relalively small parameters of CeCo, and PrCo, are explained by valencies of cerium or praseodymium which exceed the usual rare earth valency of three. The structure of the compounds is discussed as in-fillings of kagome nets in direct and staggered superposition. In the course of a systematic investigation of rare earth cobalt compounds"2 and their magnetic properties,, a series of alloys corresponding to the formula Rco3 has been prepared. The investigation of the Rco3 series was stimulated by our investigation of the yttrium cobalt system2 as well as by reports in the literature: Smith and Hansen4 reported the structure of YcO3 and Van vucht5 that of GdCo3; ceco3,6 Gdco3,7 and DyCo3 7 have been found to be single-phase during phase diagram studies. It was the purpose of this work to report crystallographic data on the entire Rco3 series and to interpret the structure of these compounds on the basis of general principles as discussed by Frank and Kasper.8 At the time this work was terminated, it was learned that a similar investigation has been carried out independently by Bertaut, Lemaire, and schweizer.9 Except for CeCo3 (ao = 4.952, co = 24.73') and NdCo3 (a0 = 5.067, co = 24.76') data of this work are in satisfactory agreement with their investigation. EXPERIMENTAL TECHNIQUES A series of samples having the composition Rc03 was prepared from stoichiometric amounts of the rare

Jan 1, 1968

By Leonard Obert

Before 1957 a number of investigators reported stress determinations made on or near the surface of underground excavations. The usual procedure was to measure surface strains and to calculate the stresses using laboratory-determined values of the elastic constants of the rock. In some instances strain gages were stress-relieved so that the measured stress was absolute. Also, several investigators reported near-surface absolute stress determinations made by the flat-jack procedure. In 1958, Hast1 described a procedure for making absolute stress determinations within a body of rock. In this procedure a diametral deformation gage was placed in a borehole and then the borehole was overcored to produce stress relief. The secondary principal stresses in the plane normal to the axis of the borehole were calculated from measured deformations and the elastic constants of the rock. During the past nine years a number of investigations have been reported1-20 in which this technique, or modifications of it, have been reported. Both the stress distribution in the walls of underground openings and the stress field at points as great as 200 ft from these openings have been determined. Considered collectively, these reports shed some light on the nature of the stress distributions in the proximity of underground openings and on the stress field, that is, the state of stress outside of the zone of influence created by openings. To summarize these findings first consider the stress distribution in the wall and structural components of openings. Fig. 1 (a) shows a typical theoretical stress distribution curve in a linear-elastic, isotropic, homogeneous material. Fig. 1 (b) is an idealized measured stress distribution curve for the same opening in a relatively unfractured uniform, but brittle,

Jan 1, 1967

By Robert Anderson

The diffraction of x-rays by cold-worked and heavily polished surfaces of metals gives, no evidence of an amorphous state and typically perfect crystallographic diffraction' patterns are obtained. Severely cold-worked metals, reduced as much as 98 per cent. in area, give true crystallographic diffraction patterns, and polished surfaces of large single crystals of metal give typical crystallographic patterns. The conclusion is drawn, on basis of x-ray evidence, that metals are fragmented on cold work and polishing and not amorphized. THE purpose of this paper is to report evidence, regarding, metal: structures, that is contradictory to the amorphous-metal, hypothesis of Beilby, and particularly evidence that is opposed to the proposition that a vitreous amorphous layer is produced by polishing a piece of metal. According to the theory of Beilby, which has been developed, by Rosenhain and others, polishing a piece of metal greatly affects the condition of the metal at or near the surface polished, making that surface entirely different in character from the metal beneath. A vitreous amorphous surface film is said to be formed. The polishing process, on the basis of Beilby's explanation, is well known-and does not' require discussion here, but it is advisable to seek the precise meaning of,., the term "amorphous." According to Beilby, "amorphous means. Non-crystalline in the most intimate sense of the word'; the molecules are not marshalled in crystalline order and orientation." According to Rosenhain, the amorphous condition is that assumed by a metal when, the .crystalline arrangement is completely broken up so that the atoms exist in a state of disorderly arrangement similar to that ;which exists in the liquid state. Thus, from the point of view of the phase rule, the "amorphous phase" is regarded as being identical with the liquid phase. Amorphous metal is often likened to an undercooled liquid. A crystalline substance is one in which the atoms are arranged in space according to some definite repeating geometrical pattern. The existence of amorphous metal has not been definitely proved.

Jan 1, 1925

By Marcel Schlumberger

The electrical methods for surface-prospecting have been well developed in the last 20 years. The method involves, in the classic form, the sending of an electrical current into the soil, by means of two electrodes A and B, and studying the potential distribution at the surface, by measuring the difference of potential between pairs of points such as M and N. The points M and N are usually placed on a line between, and equidistant from, A and B. By increasing the distance AB, the current sent into the Earth, and likewise the distribution of surface-potentials, become influenced by regions of greater and greater depth below the surface. By varying the form and dimensions of the electrode-arrangements AMNB, called a "quadripole," one may make valuable deductions concerning the nature or thickness of beds, if one knows the electrical properties of these beds. On the other hand, if the form and dimensions of the electrodes AMNB remain fixed, the depth of penetration of currents in the Earth remains, so to speak, almost constant, although it tends to increase where the subsoil is more conductive, and conversely. Therefore, if one moves the constant-dimension quadripole over all the terrain to be Investigated, one achieves approximately a horizontal exploration. This permits a study of tilted beds or faulted horizon-tal beds. When the particular problem becomes deep, of the order of 2000 meters, or more, it is ne-cessary to Increase the distance between the current-sources AB to a length such that the work 'comes very troublesome, especially if the region is wooded. At the same time, the separation the points M and N must be likewise great (for example, one km) in order to obtain differences potential which are not too small; the measurement of potential differences across MN is then difficult because of the presence of parasitic potentials, due to a flow of telluric currents in fourth, and the order of greatness of these currents may exceed the quantities to be measured.

Jan 1, 1940

By M. L. Fuller

OWING to the nature of the die-casting process, freshly cast alloys are undoubtedly not at equilibrium from the standpoint of alloy phase relationships. After casting, therefore, they tend to undergo phase changes, with the ultimate effect of reaching a state of equilibrium at the aging temperature, beyond which no further change takes place. This phase alteration undoubtedly is one of the primary causes of the changes in dimensions and physical properties that zinc-alloy die castings undergo during aging. It is planned to report on this problem in a series of papers of which this is the first. The writers have made a study of commercial zinc die-casting alloys over a period of several years, utilizing the X-ray diffraction technic of determining the phase composition changes in the alloys. Up to the present, two principal phase changes have been observed which are capable of causing dimensional changes: (1) the segregation of secondary constituents from the zinc-base solid solution and (2) the beta aluminum-zinc decomposition. The latter is the subject of the present paper and studies on the former will be reported upon at a future time.

Jan 1, 1934

By David L. Riley

Organization The Foundling Years - 1901-1921 Two events that occurred in the decade of the 1870's have had far- reaching effects upon the petroleum industry in the U. S. and formed a basis for the birth and growth of the petroleum engineering profession. In 187 1 a group of mining engineers banded together to form the American Institute of Mining Engineers "to promote the arts and sciences connected with the economic production of the useful minerals and metals and the welfare of those employed in these industries by all lawful means". Although it was to be 30 years before an event in Jefferson County, Tex., would cause petroleum to come into prominence as the world's principal source of energy, the founding of AIME provided an organization through which the application of engineering to the recovery of petroleum and natural gas could be developed. In 1875, a Pennsylvania judge who was called upon to make a decision for which there was no precedent reasoned that oil and gas were like wild game - they belong to the man who can reduce them to possession. His decision sired the "rule of capture", which stated that a landowner possesses the oil produced from his well, even though it might have come from beneath his neighbor's land. This interpretation prevailed for more than half a century, during which time gold-rush tactics were employed in the drilling and production of many oil fields in the U. S. The resulting overproduction and tremendous waste led to a virtual economic collapse of the U. S. petroleum industry by the early 1930's. To bring these malpractices under orderly control, proration and conservation policies were developed, and petroleum engineering became the medium through which they were devised and implemented. At the turn of the 20th Century, more than 90 percent of this country's oil production came from the East, but the picture changed with dramatic suddenness on Jan. 10, 1901. Captain Anthony F. Lucas, an Austrian mining engineer, had noticed concentrations of oil and gas near salt domes during mining operations on the Louisiana Gulf Coast. In 1899 he leased a low mound near Beaumont, Tex., began drilling, and after almost 2 years of intermittent operations, brought in the famous "Lucas Gusher"

Jan 1, 1971

By Francis S. Kendorski

Caving offers the lowest cost per ton of ally large-scale mining method, but its successful application demands an ore body that conforms to several rigid requirements. The deposit must be of wide areal extent, massive and not spotty in ore values, and insensitive to ore dilution. It must also be a rock mass that breaks up readily. There are only three active caving operations in the US-Climax, Henderson, and San Manuel-but caving methods have recently-taken on new importance as deeper, lower grade mineral occurrences and ore bodies are found. These deposits are too deep for surface mining methods, and too low grade to support any type of underground mining except a bulk method such as caving.

Jan 6, 1978

By Ta M. Li

A change in priorities is perhaps the underlying motivation reflective of governments and people in the Far East nations of the Philippines, Indonesia, and Thailand. While in the past, local governments have focused on feeding their large populations, the transfer of modern technology to the agricultural sector has produced record crop years in many of these countries. As a result, agricultural objectives have become more manageable, prompting governments to shift priorities to the accelerated development of their industrial sectors. The basis of any sustained industrialization program, the governments concede, is the development of a vibrant minerals sector.

Jan 8, 1979

By AIME AIME

FOR many years it has been the invariable custom of the Institute, in addition to its annual meeting in February, to hold a technical meeting in the fall in some mining or metallurgical center in the West. As the activities of the Institute have increased, and especially since the absorption 'of the American Institute of Metals, there have for a number of years been two fall meetings. Never before in the history of the Institute have there been three meetings in addition to the annual meeting in February; in 1920, however, three important fall meetings are to be held. The general Institute trip will be made this fall to the Lake Superior iron and copper country. Members will leave Buffalo on August 20 by steamer, visit the copper mines in and about Houghton, the iron mines of the Marquette and Iron Ranges of Michigan and the iron mines of the Mesabi Range in Minnesota, and' return to Buffalo by steamer on September 3. Technical sessions will be held at Houghton, Minneapolis and Duluth. For a long period it was customary for the Institute to visit the Lake Superior country about every seven years. This trip, however, will be the first visit since 1904. The unprecedented development in both copper and iron mining in this section during this period will make this trip of unusual importance. In addition, a notable series of papers will be presented.

Jan 1, 1920

By Adolf Gurlt

It has long been known that minute quantities of foreign substances, when alloyed with steel, are capable of materially altering its physical properties. Thus, half a century ago, Faraday and Stodart, in England, discovered in the famous Indian steel, known as " wootz," small quantities of aluminum, from 0.0728 to 0.693 per cent., and attributed its extraordinarily good quality to the presence of such minute quantities of that metal. Since aluminum is now produced by electrolytic means on a large scale and at low cost, its addition to cast-steel has been frequently recommended of late. Chromium was alloyed with steel fifty years ago by the celebrated French metallurgist, Berthier, of Paris, and has recently been successfully applied to the same purpose by Holtzer, of Terre-Noire. In 1860 titanium was alloyed with crucible steel by Robert Mushet, of Coleford, the alloy containing up to 0.50 per cent. of titanium, which was extracted from Norwegian ilmenite. The titanium-steel was much vaunted by him for its excellent qualities. Rhodium, a very rare metal of the platinum series, was maintained by Berthier to improve steel materially in strength and hardness. Manganese has always been held by Sheffield steel-melters to provide steel with excellent qualities, and this influence was quite recently investigated by H. M. Howe and L. Campredon. Nickel was tried as an addition by Berthier, not to speak of gold, silver and platinum ; and nickel-steel has recently been brought into prominence by J. Riley and others, who recommend it for its great strength and toughness, particularly as material for armor-plates.

Jan 1, 1894

By Robert Mehl

THE precipitation of the nitride Fe4N from the solid solution of nitrogen in a Fe and of the phosphide Fe3P from the solid solution of phosphorus in a Fe both lead to the formation of structures that may be easily identified as Widmanstätten figures, within the meaning of the term as used in this series of papers. A complete solution has been obtained for the figure formed by Fe4N. The structure of Fe,P, however, is not fully known and a complete solution of this figure thus cannot be obtained; nevertheless, a study of this figure has furnished some new information. PRECIPITATION OF FE4N FROM ALPHA SOLID SOLUTION OF N IN ALPHA FE Constitution of System Iron-nitrogen A knowledge of the constitution of the whole of the Fe-N system is unnecessary for this work, though the recent studies by Eisenhut and Kaupp1 and by Lehrer2 have clarified most of the moot points; it is sufficient for our purpose to state that a Fe of high purity dissolves 0.42 per cent of nitrogen in solid solution at the eutectoid temperature, 591° C., and that this solubility decreases at first rapidly and then more slowly until at room temperature the solid solubility amounts to approximately 0.1 per cent nitrogen.3

Jan 1, 1934

By A. F. Lucas

The discovery of oil in 1901 on the Spindletop dome, Texas, inaugurated a new industry on the Gulf Coast, an industry which has gran with the discovery of successive fields, until today it engages the services of thousands of workers and employs enormous capital. New fields are being discovered from time to time and doubtless some still remain to be found, though of late years discoveries have become more infrequent. Nowadays several hundred dry holes are drilled each year in a fruitless and blind effort to discover new fields, for as yet geologic science has developed no effectual method of locating the coastal oil deposits in advance of drilling. Moreover despite the occasional discovery of new fields, the total production of the Gulf Coast is today no greater than it was in 1906, for the added production of the new fields has been offset by the rapid decline and more or less complete exhaustion of some of the older ones. Careful geologic work within the fields has in some cases increased the production temporarily, but has developed no really new supplies. The Gulf Coast oil industry seems to have passed its period of greatest expansion and to be declining at a fairly steady rate, and this condition is naturally viewed with alarm by the more farsighted operators. In my opinion, the time has come for the adoption of radical and aggressive methods of prospecting; and a fraction of the money wasted yearly in drilling shallow wells in hopeless locations might well be devoted to this purpose. Many facts lead me to believe that all the salt-dome oil has had a common origin; that it has migrated up from considerable depth along lines of structural weakness; and that a deep well, properly located, stands an excellent chance of discovering the parent reservoir and thus of developing new and probably great supplies. This paper is presented as a discussion—necessarily hypothetical and based largely on personal opinion—of the possibility of encountering deep-seated oil deposits beneath the salt domes. Salt-dome Structure All of the oil produced in the coastal region of Texas and Louisiana is probably associated with salt domes, though in Goose Creek, Edgerly, and one or two other fields no salt has yet been actually penetrated. As

Jan 1, 1920

By C. H. Aldrich

For many years the City of Prescot, about 8 miles northeast of Liverpool, has been the home of British Insulated Cables, Ltd., one of the largest wire mills and manufacturers of electrical equipment in England. Since this location is close to the industrial center of the country and the seaboard, with good railroad transportation facilities, it was a logical site for the new refinery. Early in April, 1932, the writer was called upon to prepare a preliminary layout and estimate of cost of the proposed plant, and shortly afterward, following a discussion of these figures with officials of British Insulated Cables, in England, the decision was reached to proceed immediately with construction of the plant. The refinery was built by British Insulated Cables, Ltd. Designing of the plant was started early in May, 1932, orders for equipment being placed as rapidly as possible. On July 18 the first steel was erected and the first charge was cast on Jan. 5, 1933. No difficulties of any consequence were experienced in starting the plant and the grade of copper produced was quite satisfactory after the first charge. The initial capacity desired was 2500 tons of refined copper per month. Since only one furnace was to be built, it was necessary that it should have sufficient reserve capacity to catch up after unavoidable shutdowns. It was also necessary to lay out the plant so that it would operate efficiently at this tonnage and at the same time permit expansion in the future, if necessary, to several times its original capacity. In order to meet these conditions and also to take full advantage of the space available, the layout shown in Fig. 1 was adopted. The principal plant structures are a blister storage aisle, casting building, wire-bar storage building and a coal-pulverizing building. Additional smaller structures include a brick and charcoal shed, pumphouse, drill room, water-cooling tower, clay-preparation shed, substation and plant office. Incoming blister is received in either broad-gage railway cars or steam motor lorries in the blister storage aisle, unloaded by overhead electric crane to narrow-gage cars, weighed and sampled, then either sent directly to the furnace or placed in storage. After refining, the copper is cast on the wheel, passes through the cooling bosh and is

Jan 1, 1934

By Yang Tsang Woo

The method of making coke that has been adopted at the Kaiping and other collieries in northern China resembles, to some extent, the familiar bee-hive oven process of the United States, except that a kiln with permanent sides is used instead of a closed oven, and the products of combustion are drawn off at the bottom. In building coke-kilns in China, two circular holes, 8 ft. 6 in. in diameter at the bottom and 13 ft. in diameter at the top, are excavated in the ground, and connected at the bottom by a flue, as shown in Figs. 1 and 2. The sides and bottom of the kiln are lined with fire-bricks, and covered with a lager of fireclay, and a rectangular opening, 6 in. by 8 in., connects the bottom of each kiln with the main flue. Around the edge of the hole, and overlapping the lining, is a wall of fire-brick extending 2 ft. 6 in. above the level of the ground. An open space 5 ft. wide is left in this wall, through which the coal is carried into the kiln and the resultant coke removed. This space, of course, is bricked up during the time that the coking-operation is being carried on. The wall is pierced with nine flue-openings uniformly placed around the circumference, each interverliilg space in the wall being strengthened with a brick buttress, as is shown in Figs. 2 and 4. The floor of the kiln, as well as the main flue, is lined with fire-brick. Before charging the coal, it is first placed in shallow bamboo sieves, 2 ft. in diameter, and immersed in a trough 10 ft. long, and 3 ft. wide, fed with pit-water, in which it is washed by hand. Fig. 3 shows the manner in which the washing is done. From 25 tons of good "dust" coal, 22.5 tons of washed coal are obtained. When ready to charge the coal into the kiln, a temporary cone-shaped flue of fire-wood and lump coal is first built to a

Jan 1, 1906

By Walter Harvey Weed

The Republic of Mexico is traversed by many mountain ranges, and presents a great diversity of climates, soils and geographical features, yet its grander geographic provinces are few and peculiarly well defined. The Gulf plain, the Cen tral plateau, the Sierra Madre, and the lowland or Tierra Cali ente of the western coast are the main features of the geogra phy of the Republic, and in the northern half these provinces are particularly well defined. The Sierra Madre separates the Republic into eastern and western parts, and from the City of Mexico north to the Texas line presents an almost impassable barrier to east and west travel. On the north, the first wagon road pass from east to west is at El Paso del Norte, the site of the Texan city of El Paso. Southward for many hundreds of miles the Sierra Madre, traversed by well-worn trails, over which all travel from the west coast to the interior must pass, is a stupendous barrier to social and commercial intercourse. The Sierra Madre is commonly described as a range or con geries of mountain ranges. In fact, it is, in Chihuahua at least, a great plateau, fringed by mountains on the east, trenched by deep canons in its center, and bordered by a wild and rugged complex of mountains carved out of the plateau on the west. Professional duties took me across this region from Parral westward to the Gulf of California via Guadalupe y Calvo. As it includes some of the great ore-deposits of Mexico, and its geological features have never, so far as I am aware, been described, I have prepared a diagrammatic section made from my observations on a horseback trip across the Sierra, and added such notes as seem to be of general interest.

Jan 1, 1902

By Jun-Yan Chen, Stefan H. Boshkov

Metal mining in the People's Republic of China has shown great growth during the last three decades. Over 150 new iron ore mines and nonferrous base metal mines have been opened since 1949, althouc.11 most of them of medium and small size. Concurrently, many old mines were enlarged and reconstructed. The production of iron ore has grown from less than 1.5 million tons per year in 1949 to almost 76 million tons in 1978. A corresponding increase in the total annual output in the nonferrous metal mineral industry has also been noted. It is well known that the PRC is very rich in metal mineral resources. The reserves of tungsten, tin, antimony, molybdenum and iron ore are ranked in the top three in the world. Recently, some copper porphyry ore deposits were discovered in Jianxi and Anhui provinces. Some large nickel-copper sulfide deposits were discovered and have been developed in North- West China. Huge iron ore deposits have been found in Liaoning, Hebei and Szechwan provinces. However, the bulk of the iron ores are low grade. The growing metal mineral production has met basic domestic needs since 1949; it has also proven China's big resource potential. Mining methods have also undergone development in the past 30 years. About 80% of the annual output of iron ore comes from open pits, whereas about 58% of nonferrous metal ores come from underground mines. Blasthole open stoping, sublevel caving and induced block caving are widely used in Chinese underground metal mines (table 1). This paper summarizes in detail the planning for and application of these three bulk mining methods in the nonferrous and iron ore mines in China. CLASSIFICATION OF UNDERGROUND MINING METHODS The main principle of the classification of underground mining methods in PRC is ground support in the stoping cycles of the mining blocks or stopes. Table 2 lists this classification. It is essentially the same as that given in the SME Mining Engineering Handbook. Be- cause pillar removal is a secondary mining operation, using a variety of methods, they are not included in this classification. As is the case with most classifications in science and technology, there is no precise division between the classes of mining methods. Because of the rapid development of consolidated filling techniques in the past twenty years, some types of open stoping methods use fill in order to improve the ground conditions for the secondary recovery stage. Thus, these mining methods have features of both methods using no artificial support and those using artificial support. In this classification, this type of mining method is placed in the latter category. The shrinkage stoping method has been employed extensively to mine steeply dipping narrow veins of tungsten and tin in the Jiangxi, Hunan, Guangdong and Guangxi provinces. Shrink- age stoping is placed under the class of mining methods without artificial support be- cause this reflects the nature of the Chinese experience. The function of the broken ore serving to support the footwall and/or hanging wall is limited, because the expectation is for the host rocks to remain unsupported until the stope is drawn empty. APPLICATION OF BULK MINING METHODS Bulk mining methods consist of blasthole open stoping, sublevel caving and block caving. These stoping methods have much in common, such as: bulk ore materials blasted by long holes; higher production rates of stopes or blocks and higher production efficiencies of the whole mining systems.

Jan 1, 1981

By John Hillman

Reconstruction of the British mining industry began shortly after nationalization in 1947 and continued until well into the 1950s with the support of the government. This support diminished as plentiful supplies of cheap oil from the Middle East made many coal mines uneconomic. The planned rundown which followed was foreshadowed in the 1965 White Paper which outlined financial measures to speed the closure of uneconomic collieries. The decline appeared likely to continue into the 21st century as the role of coal in UK energy requirements became less and less significant. This policy was well on course in 1973 when the oil crisis led to a complete reappraisal of the position. A government examination in 1974 of the coal industry then supported the National Coal Board's general strategy of major capital investment as set out in its ' Plan for Coal ' .1

Jan 11, 1979

By A. G. McGregor

During the past 5 years, five new copper-smelting plants have been built and put into operation in the State of Arizona. The monthly copper output from these plants averages from 5,000,000 to 18,000,000 lb. Previously, there never was as much activity in copper-smelting plant construction in the same length of time in all the rest of the world. Naturally, in this amount of work, some new problems were met and new features in plant design and equipment developed. Some of these features are described in this paper. Concentrate Hauling, Unloading and Sampling System (a) Concentrate Car The International Smelting Co. has provided at its plant at Miami specially designed cars for hauling the concentrates from the mills of the Inspiration Copper Co. and the Miami Copper Co. The car has a bottom that is readily made tight to hold flotation concentrates and is quickly and cheaply unloaded. Figs. 1, 2 and 3 show views and details of the car. The main feature of this car is the slot in the bottom throughout its length, which is closed by means of short planks that overlap like ship-lap as shown by Fig. 1. At one end of the car an iron gate operated by a screw and hand wheel is provided, which clamps or presses the planks together, making the bottom tight. A removable tapered plug rests vertically over this gate when the loading of the concentrates at the mill commences. A concentrate unloading pocket (Fig. 4), 180 ft.long, is provided at the smelting plant, which has a conveyor belt running throughout its length underneath the track. To unload a car, the vertical plug at the end of the car is lifted by means of a chain hoist which is supported by a trolley overhead. The gate at the end of the car is opened approximately 18 in. The removal of the plug leaves a hole down through the concentrates. The concentrates are poked through the hole from the top of the car until it is convenient for a man to stand on the bottom and draw one of the slats in the bottom toward the gate end of the car. The concentrates are then raked down with hoes on their natural angle of repose,

Jan 1, 1917