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By T. A. Lang

For permanent structure underground, where rock is not competent, support usually consists of concrete or reinforced concrete. However, temporary supports in the form of timber or steel are often needed during construc-tion. Although the history of rock bolting is relatively short—50 years— their use has become widespread in general engineering construction as well as mining. This profusely illustrated and detailed study covers a broad range in the field of rock belting: from the behavior of rock and bolts including rock properties, masses, and structure; mathematical formulae for rock bolt applications; through analysis of various operations and descriptions of the bolts themselves. Rock construction is one of the oldest of the engineering arts and its origin is lost in antiquity. From the days when early man decided that he wanted to improve the natural caves which he was using for shelter and protection or made a river crossing by placing rocks to form a ford or causeway, we have had structures made of rock. It is not too much to say that rock in situ as a structural material forms part of every major engineering undertaking. Rock bolting is one means whereby the inherently good characteristics of rock in situ are preserved and used to the best advantage and the bad characteristics ameliorated. In many cases the latter are accentuated by construction processes used. Rock bolting, as with other rock construction techniques, is only just beginning to emerge from being an art. Consequently, its theory and practice is still more descriptive than mathematical. ROCK BOLTING In underground excavations, where the rock is not competent, support is provided. For the permanent structure, this generally consists of concrete or reinforced concrete. However, support may be needed during construction before the concrete can be placed, and conventionally this consists of timber or steel support in the form of ribs, struts, and lagging. Alternatively, rock bolts may be used. Although their use dates back over 50 years, it is only in recent years that rock bolts have become widely used, not only in mining but in general engineering construction. A rock bolt is a steel bar which is inserted in a hole drilled in rock. The end away from the rock face has a device which permits it to be firmly an- chored in the hole and the projecting end is fitted with a plate which bears against the rock surface. The bolt is placed in tension between the anchor and the plate, thereby exerting a compressive force on the rock. The essential feature of a rock bolt is that it is placed in tension. This distinguishes it from anchor bars which are grouted into holes in rock, but which are not prestressed. The difference between an anchor bar and a rock bolt when the rock bolt is grouted in is analogous to the difference between the reinforcement in ordinary reinforced concrete and in prestressed reinforced concrete. The view that rock bolts only pin or nail blocks or slabs of rock which are loose to the sounder rock behind them is erroneous. Rock bolts are useful for this purpose and have been so used for a long time. However, the term rock bolting, as used here, means the designed use of rock bolts to reinforce and develop the rock around an excavation into a structural entity which can competently play its part in a structure such as a powerhouse or a mine installation. Rock bolts behave quite differently than steel ribs. They can be installed at the working face directly after blasting and within a short space of time can be exerting a stabilizing pressure on the loosened rock surface. This early installation not only partially restores loosened blocks of rock to their original unloosened positions, but also it prevents the gradual relaxation or loosening of the decompression zone behind the new rock face. In contrast, steel ribs generally use timber blocks, wedges, and lagging between the ribs and the irregular rock surface. The timber is relatively compressible, and loosened blocks of rock must move outwards an appreciable distance before any load builds up on the steel ribs. Also, the ribs may settle as the foot blocks and foundation become compressed. Hence, it may take several days or weeks before the rock has moved sufficiently to make the steel ribs carry an effective load.

Jan 1, 1961

By AIME AIME

THOUGH born in England-on Nov. 23, 1372 William Wraith was brought to this country at the age of ten. Eight years later he entered the University of Illinois, transferring to the Michigan College of Mines where he got his E.M. in 1894. For the next three years he was a mine surveyor for the fuel department of the Santa Fe Railroad. Then he got into the copper-mining industry, which has occupied his attention for the last forty years. First he was engineer, at Butte, for the Boston & Montana company, and then helped to build the Washoe smelter at Anaconda, of which he was assistant superintendent from 1906 to 1913. The Anaconda company then sent him to Salt Lake City as manager of its subsidiary.

Jan 1, 1938

By E. C. Weichel

THERE have been many attempts at permanent roof support in anthracite mines, in some cases brick arches, in others concrete, and also combinations of brick or concrete walls with steel beams. These supposedly permanent roof supports have frequently failed when heavy pressure is brought to bear upon the structure, because they are so rigid that failure occurs because the structure is unable to adjust itself to the increased load. Roof pressure exerts a tremendous weight, and it is at times difficult to find any means of support which is strong enough to bear the entire pressure, unless this supporting structure has in itself the element of some flexibility which will enable the structure to hold the moving mass until it "arches" itself. If the supporting medium has flexibility enough so that it can adjust itself to the heavy initial loads, and so give the overlying material an opportunity to form a self-supporting arch, then such a roof support will be more useful than any rigid roof support. There has recently been introduced into the anthracite region a new form of gangway lining that is flexible enough to slightly adjust itself under heavy pressures, and so give the loosened material which is being supported a chance to form into an "arched" mass. This lining, manufactured under patents granted to Hans Schaefer of Essen, Germany, was introduced in the United States in the summer of 1928, at which time the Amercan licensee, Richard Howells of

Jan 1, 1930

By A. H. Hand

When considering the question of future demand for crude petroleum in California, one must first decide whether it is to be approached in the light of the definition of "demand" when used in economics; i.e., "The quantity of any commodity required or sought in the market," or in the light of markets developed to dispose of total supply. Therefore, is the California demand of future years to be predicated on a continuation of supplying markets developed following the surplus production commencing in 1922, or predicated on supplying what would be termed economic markets ? If the latter, what are economic markets ? Obviously, the Pacific Coast States and Canada, Alaska, Hawaii and probably the Pacific side of Central and South America, can be considered as normal markets for California petroleum products. While there have been small quantities of gasoline shipped into the PacSc Coast from East Texas, transportation costs, plus import taxes in the case of foreign oil, are a sufficient barrier to justify considering that these markets will be retained. But how about our participation in Atlantic and Pacific foreign and intercoastal markets? During the five years preceding 1931 California shipped substantial quantities of gasoline to the United Kingdom and to France, Germany and Italy. During recent years our business in European markets has been restricted to occasional shipments of gasoline and Kettleman crude. This loss of business is occasioned by the development of production in the Mid-Continent, principally East Texas, and in Iraq, Rumania, Venezuela and other closer producing areas, which makes it impossible at the prevailing crude-oil prices for California to be competitive in supplying any substantial portion of these markets. It is therefore apparent that under a stabilized price structure that will return the California producer a reasonable price for his oil, future Atlantic foreign -business will be restricted to occasional spot cargo sales. As to Pacific foreign shipments which, in addition to Central and South America, consist principally of shipments to Japan, China, Australia and New Zealand: A considerable portion of the business we had with Australia and New Zealand until four or five years ago is now being

Jan 1, 1937

By Nathaniel Arbiter, Norman L. Weiss

Factors now accelerating the trend to larger concentrators and larger equipment units are reviewed. After almost 40 years of stability with unit sizes less than 100 cu ft, 200 and 300-cu-ft flotation-cell units are now operating and a 500-cu-ft machine is being built. The design of these cells is considered, as is the design and operation of flotation circuits against the background of the need to achieve greater process efficiency while holding down operating and investment costs. Particular attention is paid to the scale-up problem. With the newer cells having five to ten times higher unit capacities, the advantages resulting from this in sampling, mill operation nnd control, testing and plant layout are indicated, as well as the broad direction for changes in the overall design of 50,000 to 100,000-tpd concentrators. A comparison is given of the available larger cells of U.S. manufacture with analysis of differences and similarities. After almost 60 years of application in this country, froth flotation is still by far the most important process for concentrating metallic ores as well as a number of nonmetallic ores including fluorspar, phosphate rock, and potash. Its use on iron ores and coal is increasing. In the metals groups, the largest plants and the greatest progress are found in copper and molybdenum mills, and the section of this paper that deals with applications will be found most pertinent to that field. During its long reign, the flotation process has passed through several phases of evolution and has achieved progress in economy, efficiency. and simplicity of operation. Much of today's success in the flotation of low-grade ores can be attributed to that progress. Even more important to us than our ability to cope with today's conditions are tomorrow's problems, which we can contemplate with some prescience and confidence. Our annual production of copper, lead, zinc, and molybdenum—to mention only the most important metals occurring in the U.S. as sulfides- must be held at a high level in the face of a declining grade of ore. It is probable that the tonnage of such ores mined and processed will double in this country before the turn of the century. Not only will many of the existing flotation mills be enlarged again and again, but larger mills will be built here and abroad to meet our needs. At this moment, in fact, there are at least three proposed new foreign mills or expansions that envision 100,000-tpd milling rate on copper ores. Table 1' shows the trend in copper ore grades in U.S. in recent years. Table 2' shows the projected annual growth rate of consumption 1966-1985. A study by one of the authors 25 years ago showed that of 32 copper mills in North America with more than 100-tpd capacity, only eight had capacities exceeding 10,000 tpd. The average for these eight was 25,000 tpd. These included the three giants of that day, Magna, Arthur, and Morenci; the other five averaged a little over 10,000 tpd. Today instead of the eight mills with capacities exceeding 10,000-tpd capacity we have 25, and the mill with less than 1000-tpd capacity is fast becoming extinct. Much less range is found in lead and zinc mills, which are still generally small except for the few with over 1000-tpd capacity in Missouri, Utah, and Idaho, and a few zinc ore mills in the same size category. Molybdenum and potash operations are the fastest growers in North America today, but when one considers the projected increase in consumption of copper together with the projected decrease in grade of ore (3% annually), he can foresee that copper ore milling will soon lead the list. Technological improvements to meet the challenge of lower-grade ores have taken the wholly predictable path toward bigger equipment. In mining, shovels, draglines, scrapers, and trucks have led the way; in ore processing, we have seen a rapid increase in size of grinding mills, flotation cells, and pumps. Twenty-five years ago, for example, the 10-ft-diam ball mills treating 2000 tpd at Morenci were considered the giants, but today some grinding mills in similar service have five times that capacity. The specific matters to be dealt with in this paper are 1) the underlying principles that affect flotation-machine design, and the conditions required to produce

Jan 1, 1971

By R. E. Tate, L. J. Herman

We have had occasion to produce wire of Np-237 in small diameters for use in some chemical experiments. Since the mechanical metallurgy of neptunium has not been investigated extensively, it seems desirable to report our successful extrusion technique. Because of the neptunium activity and its attendant health hazard the experimental work was done in glove boxes and related equipment also used for Pu-239. At room temperature a phase neptunium' is a hard (Dph -355) orthorhombic metal of high density (p = 20.45 g per cu cm). a neptunium transforms2 to tetragonal ß neptunium at about 280°C and this in turn transforms to bcc y neptunium at about 577°C. The y phase melts at about 637°C. A temperature of 340° to 345°C was selected for the extrusion, this temperature being a compromise be- tween a possible advantage of working with the presumably more plastic cubic y phase above 577°C and the risk of having the neptunium react with the alloy steel die to form the low-melting Fe-Np eutectic. A 0.75-in.-long, 0.26-in.-diameter ingot of good-purity* Np-237 was extruded by the direct *C = 230 ppm, Pu = 200 ppm, thirty-five metallic elements below limit of detection by spectrographic methods. process through flat-face orifices to form several sizes of wire ranging from 0.010 to 0.030 in. in diameter. Molybdenum disulfide was used as the die lubricant. The extrusion was done in a vacuum of about 10-4 torr to reduce reaction of the neptunium with atmospheric gases. British workers3 at Harwell have extruded neptunium under similar conditions. The force required to extrude 0.010-in.-diameter wire at the rate of 4 in. per min was 6000 lb, as measured with an electrical load cell. Wire 0.020 in. in diameter was extruded with a force of 4700 lb at a rate of 2 in. per min, and wire 0.030 in. in diameter was extruded with a force of 4000 lb at a rate of 1.3 in. per min. An extrusion constant, c, can be computed from the measured forces, P, for the equation4 P = c log-A/a where A/a is the extrusion ratio or the ratio of the cross-sectional areas of the container and the

Jan 1, 1965

Some years ago the open Hearth Committee of the Institute reached the conclusion that the reading of "set" papers tended to preclude the specific and detailed discussion of specialized problems of current interest to those operating steel plants. As an innovation the Committee distributed in advance of the meeting in May, 1927, a questionnaire containing a list of 27 topics involving operating problems. The subsequent discussion of the questions, participated in by 37 members, was a conspicuous success. Semiannual meetings have been held since; and at the conference of November, 1929, at Chicago, 131 men were present and the minutes comprised a book of 133 printed pages, thereby, indicating the growing value of the conference in the eyes of both the metallurgists themselves and the companies that employed them. With this example in mind, the Directors felt that definite advantages would accrue to a similar conference to be participated in by smelter officials and metallurgists engaged in the operation of copper reverberatory furnaces. The settlement of the Carson litigation, which for several years had virtually stopped public discussion of reverberatory practice, offered an opportune time for launching the scheme. Although the Conference may become largely self-financing in the future, some funds were regarded as necessary to conduct the first meeting. The members of the Rocky Mountain Income Committee, in view of the fact that copper smelting was essentially an activity of the Rocky Mountain area, recommended the project be, in effect, underwritten by the Fund, and the directors approved an appropriation for this purpose. Invitations were extended to high executives of the various-companies interested to send representatives to an initial meeting to be held at Salt Lake City, May 26-27. The response was enthusiastic. Twenty-three metallurgists representing 12 different plants were present to discuss the comprehensive-program relating to construction and operating phases of reverberatory smelting. It was understood that the record was not to be included in the regular publications of the Institute but that it would be prepared for private distribution among the participants and the officials of their companies. That the exchange of views and experience was no less instructive and stimulating than it was frank, full and informal is indicated by the following transcript of the minutes of the meeting.

Jan 1, 1930

By O.W. Ellis

Recently there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2 alone gave reliable information in this regard. Even today his determinations of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time—their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systernatic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington, 16 Smalley33 and Thiband 45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper. The situation in regard to these alloys in 1926 was very clearly stated by an anonymous writer,47 in The Metallurgist of February of that year, whose remarks were so to the point that they are well worth quoting: It will he seen that there are still large fields remaining to be studied in each of these systems (those of the aluminum, iron, nickel and manganese brasses) before our knowledge is adequate. When we come to the more complicated systems the position is even less satisfactory, and on account of the very incomplete nature of the work which has been

Jan 1, 1929

By O. W. Ellis

Recently there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2 alone gave reliable information in this regard. Even today his determinations of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time—their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systernatic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington, 16 Smalley33 and Thiband 45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper. The situation in regard to these alloys in 1926 was very clearly stated by an anonymous writer,47 in The Metallurgist of February of that year, whose remarks were so to the point that they are well worth quoting: It will he seen that there are still large fields remaining to be studied in each of these systems (those of the aluminum, iron, nickel and manganese brasses) before our knowledge is adequate. When we come to the more complicated systems the position is even less satisfactory, and on account of the very incomplete nature of the work which has been

Jan 1, 1929

By E. M. Wise

THOUGH known as the platinum-group metal- the sextuplet, platinum, palladium, iridium. rhodium, osmium, ruthenium, might well be called the American metals or perhaps Pan-American metals, as the ore containing them eras first discovered in South America, and in recent years the largest production has come from North America. The South American alluvial deposits, which also, contain gold, are in active production, as are the alluvial platinum deposits of Alaska, but the main production is from the copper-nickel ores of Sudbury, Ontario. The Russian deposits in the Urals were the source of most of the worlds platinum for about 100 years, but since 1934 have assumed second place. For a time considerable amounts of platinum came from several rather rich deposits in South Africa but these were exhausted quickly. However, a tremendous reserve of lower-grade ore exists there, which could be worked profitably if the price of platinum were considerably higher.

Jan 1, 1942

By Frank R. Van Horn

It is customary to ascribe two general modes of occurrence to natural gas, namely, shale gas which, as the name indicates, is found in shale, and reservoir gas, which occurs in sandstone, conglomerate and dolomitic limestone. Both of these types are found in the Cleveland district. The shale gas has been produced on a small scale for a long period of years, probably dating back as far as 1883. Shale gas is a low-pressure gas, small in volume with variable pressure, and is limited to no definite horizon. It is generally independent of oil, may last for a long time, and is not dependent to any great extent on the structure of the rocks. There are many such wells in the district which range from 400 to 1,840 ft. in depth, although most have been completed at about 800 ft. This indicates that the wells pass through the Cleveland and Chagrin shales into the Huron or Portage shale of the Upper Devonian. During the last 2 years great interest has developed in a deeper-seated reservoir gas. What is commonly called reservoir gas is generally a high-pressure gas occurring in large volume at a definite horizon. Oil may, or may not, be associated with the gas, and in most regions in which reservoir gas is found, the geological structure is of great importance. This type of gas occurs in all large fields such as those of West Virginia which have been supplying Cleveland until the recent discovery of local gas at great depths in commercial amounts. Historical Outline The oldest well producing reservoir gas in the district was drilled in 1886 in Newburg for what was then known as the Cleveland Rolling Mill Co. This well was 3,000 ft. deep, and was thought to have reached the "Clinton" formation. Two "sands" showing small amounts of oil were recorded in the Niagara limestone at depths of 2,658 and 2,686 ft. This is about the horizon of the so-called Newburg sand which has proved to be of some importance as a source of gas and oil by recent drilling operations. The rock pressure was reported to be 400 to 500 lb. per square inch, but since the volume was only 14,000 to 16,000 cu. ft. daily, the well was not only considered unsuccessful but was thought to prove the absence of high-pressure gas in commercial quantities in the Cleveland district.

Jan 1, 1917

By Fulton B. Flick

The micrography and macrography of aluminum and its alloys present certain difficulties. Many of the difficulties attendant on the micrography have been removed by methods developed during the past few years, notably those of E. H. Dix, Jr.1 The development of grain size in aluminum and its alloys may be equally troublesome, yet comparatively little detailed attention appears to have been given to it. Satisfactory reagents are available for the development of such structurcs in ferrous and most non-ferrous metals, but those applied to aluminum and its alloys, i. e., alcoholic or aqueous solutions of sodium hydroxide or hydrofluoric acid are not entirely satisfactory. Hanson and Arch-butt,2 in speaking of these two reagents, state that "These two reagents give fairly satisfactory results, but they sometimes produce badly tarnished surfaces from which the surface deposit is difficult to remove." It has been our experience that neither of these reagents is to be entirely relied on for developing structures suitable for study or photography. This means that when the etch fails to produce satisfactory results the specimen must be repolished, through the 000-paper at least, and then etched with another reagent. This procedure entails a considerable loss of time, and the final results may not be all that might be desired. However, the reagent to be described, although not a panacea for all etching troubles, has improved results so markedly that it is felt that it & worth offering as a grain-size etch generally applicable to aluminum and aluminum alloys. Czochralski3 in 1915 mentioned the application of a solution of 10 to 20 c. c. concentrated hydrofluoric acid in 100 c. c. absolute alcohol, etching in this reagent being followed by dipping in concentrated hydrochloric acid soliltion.

Jan 1, 1925

By H. J. Rahilly

MINE FIRES, in the Butte District, have been a source of trouble and expense for the past thirty years, for while the actual fire area in most of the mines has been comparatively small, the handling of the gas has generally been a much larger problem than the actual putting out of the fire. The chief causes of these fires have been: Defective electrical equipment, incendiarism or carelessness, and spontaneous combustion. While fires from the first two causes have been numerous, they have generally been discovered and extinguished before they became very serious. Spontaneous combustion has been the cause of most of the large fires. Sufficient heat has been generated by ground movement, high rock temperatures, and decomposition to set fire to inflammable materials (tarred ropes, canvas, dry timber, manure, and hay) left in the gobs some years ago. Also, the heat resulting from the oxidation of the fine broken sulfide ore is sometimes sufficient to set fire to the timbers. In 1906, a fire was discovered on the 1100-ft. level of the Minnie Healy mine about 400 ft. (122 m.) west of the Minnie Healy shaft, which presumably originated, in one of the upper levels, from spontaneous combustion. The fire was walled off by concrete bulkheads and a pillar of ground 100 ft. (30 m.) thick was left below and mining resumed underneath. During subsequent operations, this pillar became cracked and broken and the fire passed into the new workings. It travelled downward and spread rapidly until, in 1917, it had become necessary to wall off portions of the Tramway, Leonard, and West Colusa mines on the 1300, 1400, 1500, 1600, 1800, 1900, and 2000-ft. levels, and the top of the 2200-ft. raises were sealed. The fire area now consists roughly of a block 1000 by 1200 ft. and from the 600-ft. to the 2200-ft. level. This block is composed largely of a series of parallel northwest-southeast nearly vertical veins and stringers that form a large orebody, with no well-defined walls but badly fractured and faulted, and known locally as "Horsetail Ore." These veins, or orebodies, are mined by the square-set or the rill method.

Jan 2, 1922

This discussion of the paper of Chester W. Washburne should have been printed following the remarks of H. A. Wheeler, in Bulletin No. 100, April, 1915, pp. 835 and 836, but was inadvertently omitted. ROSWELL H. JOHNSON:-There is one reason why the hydrostatic interpretation of gas pressure is not wholly acceptable. As we go clown in the sands we seem to get excesses of gas. Particularly in this field it becomes excessive in quantity relative to the amount of water in the sand. If this holds in other fields as well it must mean that there has been an ascension of water, because these sedimentaries when laid down, were filled with connate water. If we do get an ascension of connate water, produced by some such phenomena as its expansion by heat or by the formation of new gas by pressure upon organic materials at great depth, we can hardly expect the pressure to be controlled merely hydrostatically. * In reply to Mr. Wheeler's inquiry as to gas wells with pressure higher than hydrostatic pressure, I would cite the original wells given by Orton on which he based the hydrostatic theory. He used in his calculation a head of 600 ft. above tide, assuming the outcrop of the Manitoulin Islands to be in Lake Superior, whereas the Trenton does not outcrop at Lake Superior. The Manitoulin Islands are in Lake Huron, the level of which is 580 ft. above tide. No allowance is made for the lower density of the fresher water near the outcrop, the weight taken for the whole column being the water of high density found at the wells.

Jan 5, 1915

By W. N. Poundstone, G. R. Spindler

A comprehensive report on extensive experimentation in degasification of the Pittsburgh Coal seam is presented. Detailed accounts of the procedures and results are given for permeability tests, vertical bore hole tests, measurement of gas flow from sealed drainage areas, horizontal rib hole tests, and water infusion tests. The removal of methane gas from coal seams in advance of mining is not a new idea with mining men—much attention has been given to the possibility for many years. In other parts of the world, a principal concern has been in the recovery and utilization of the gas and a number of successful projects have been developed in Europe and elsewhere. In this country, the principal motivation has been related to the safety aspect with some possible side benefits concerning costs and efficiency in mining as secondary objectives. To date, experimental work in this country has been largely or entirely exploratory to determine bed characteristics with respect to the liberation of combustible gases to investigate or establish the possibility of degasification in advance of mining and as an aid in projecting mine ventilation systems to provide for safe, effective and economical handling of combustible gases liberated during mining. With these objectives in mind, the School of Mines and Engineering Experiment Station at West Virginia University, in cooperation with the Christopher Coal Co. of Osage, W. Va., initiated some experimental work in May 1952 and the project has been more or less continuous since that time. The work has been centered entirely in mines of the cooperating company in Monongalia County, W. Va., and Greene County, Pa. LOCATION AND GENERAL CONDITIONS OF THE AREA The principal mining in the area involved is in the Pittsburgh coal seam which lies at the bottom of the Monongahela series of the Pennsylvanian. The Pittsburgh coal in the area is generally uniform in its structure and physical characteristics. The bed thickness averages about 7 to 8 ft and the coal has a characteristic blocky structure as the result of pronounced face cleats and definite, but somewhat less pronounced, butt cleavage. It is a medium volatile coal, averaging about 37 pct, and is marketed principally as a steam fuel and for metallurgical purposes. The Pittsburgh coal outcrops along the Monongahela River and dips gradually, but not uniformly, slightly north of west (about N75°W). The westward extensions of the bed, from the areas contiguous to the Monongahela River which have been heavily mined, constitute the principal reserves and are all well below drainage with the depth of cover increasing with the distance from the river. In general, with deeper cover, it may be expected that methane liberation will be more of a problem in future mining as compared to areas mined previously; therein lies the interest in possible de-gasification in advance of mining. Fig. 1 shows the Pittsburgh coal area in the vicinity of Morgantown in Monongalia County, W. Va., and Greene County, Pa., in which the experimental work discussed is located. Fig. 2 shows the contours on the Pittsburgh coal in the test area. It will be noted that the first two bore holes for the experiments were at the edge of a bench or terrace with considerable change in the gradient in the immediate vicinity of the test holes and that the same general condition applies to later test areas. Mining is intensively mechanized in the area and in the mines involved in the experimental work with corresponding rapid advance of working faces a typical characteristic. In the areas now mined the total methane liberation ranges from moderate to relatively heavy, but the actual face liberation is extremely variable and may range from practically

Jan 1, 1961

By J. B. Neale

FRom the beginning of its activities, the members of the National Production Committee have felt that the following points were essential to the success of its work: The operators must feel that their operations were not 100 per cent. efficient; that they should be courteous and fair in their treatment of their employees; and that they should set an example of hard work and patriotic interest in increased production. Every move made must appeal to the sense of fairness of all parties concerned. The men must feel that in working more faithfully, and consequently producing more coal, they are rendering a distinct service to their Government in the time of its great need. As the workers feel that greater efficiency on their part results only in greater profits to the operators, the advantage to the operator should be lost sight of, as far as possible, and the advantage to the Government in fighting the war emphasized. Both operators and workers should know that the Government considered increased production an obligation, and opportunity for service, resting on both parties and not on the operators or the workers alone, and that both parties could very much better the efficiency of the pre-war period. Had the committee intimated that it thought the coal shortage was due entirely to the idleness and inefficiency of the workers, its campaign would have failed, for the men would have resented the charge because only too frequently their efforts to produce more coal were thwarted by bad management; besides, the operators would have lacked stimulus to better effort. On the other hand, had the impression been given that the committee thought that the coal shortage was due entirely to bad management, the operators would have resented the charge because only too frequently their efforts to produce more coal were thwarted by the idleness and inefficiency of the workers; and the workers, having been thus indirectly pronounced 100 per cent. efficient and patriotic, would have lacked stimulus to better effort.

Jan 1, 1920

By John S. Johnson

THE purpose of this article is to describe several types of borehole lining in common use, and especially to offer a relatively new means of reducing the expense of maintaining boreholes where they are subjected to corrosive action of water flowing either inside or outside of their casing. In the Anthracite region of Pennsylvania, boreholes are used for many purposes, the principal ones being: openings between the surface and underground workings through which are passed steam, water and compressed-air lines, ropeways from surface hoists to underground rope haulages, conduits for electric power and signal lines, water-discharge lines from underground pumping stations, and inlets to mine workings for flushing material. LININGS FOR BOREHOLES The inadequacy of steel pipe for use in boreholes has long been recognized. Various substitute materials have been tried, including screw-joint cast-iron pipe (Fig. I). Cast-iron pipe, while very effective as a discharge line for acid water (mine water) being pumped to the surface, is not so effective when serving as a conduit for silt and crushed rock being flushed underground for filling mine voids. Terra cotta pipe (Fig. 2) has been used in boreholes, and lasts a long time if the glazed inner surface of the pipe remains intact. Its installation in a borehole is very difficult and is recommended only where it is certain that there will be no subsidence of the surrounding territory. Accessibility in order properly to join each section of the pipe is essential to a satisfactory job. In large water holes, where it is possible to lower a man into the hole for sealing the joints of the pipe, glazed terra cotta pipe has been used successfully for delivering mine water from pumps in the mines. For large holes used for flushing refuse into mine workings where the surface wash is shallow, standard paving brick have been used to form a tube through the wash to the bedrock. These brick are laid radially, backed by common brick and cobbles laid in cement. It is obvious that the shaft through the wash must be large enough to permit a man to work in it. The flushing material is carried through bare rock from the juncture at bedrock to the openings underground. This plan has been used, particularly where a cast-iron surface line is laid upon the surface to carry the flushing material from the breaker to the hole, and down the hole continuously, with no opening to the air at the top of the hole, thereby eliminating the necessity of an attendant at this point (Fig. 3). Another similar type of borehole lining is constructed of hexagonal pieces of vitrified brick (Fig. 4). This type requires a steel drive pipe through the surface wash large enough to provide a finished tube of the desired size surrounded by a brick wall about 4 in. thick. The special bricks are laid in cement, six to a circle, around a lubricated pipe used as a form, and lowered in sections inside the large drive pipe; the bottom section is seated in a socket drilled in the solid rock, having the same inside

Jan 1, 1941

By H. E. Mussey

WHEN the American Institute of Mining Engineers visited the Birmingham district in May, 1888, the four Ensley furnaces (Fig. 1) then FIG. 1.-BLAST-FURNACE DEVELOPMENT IN ALABAMA. completed were referred to as monumental.1 Their dimensions are given in Table 1. Mr. Gordon stated, with considerable satisfaction, that on the preceding day one furnace had produced 165 tons. The blast was

Jan 10, 1924

By AIME AIME

The following abstract of the minutes of the final Adjourned Annual Business Meeting, held Nov. 12, 1912, in the office of the Institute, 29 West 39th Street, New York City, is here presented for the information of the membership at large. On the announcement by the Secretary that there was a quorum present, President James F. Kemp called the meeting to order. The minutes of the Adjourned Annual Business Meeting of Oct. 7, 1912, were read and approved. (Sec p. xi,Bulletin No. 71, November). Prof. Jos. W. Richards, in behalf of the Special Committee of the Board of Directors and the Council (Messrs. Richards, Kirchhoff, and Rand), withdrew the two proposed amendments to the Constitution offered by the said Committee at the Adjourned Annual Business Meeting of Oct. 7, 1912. (See Bulletin. No. 70, October, 1912, p. vi., and Circular Announcement No. 8, Oct. 15, 1912, p. 15.) Professor Richards presented a syllabus of the proposed amendments to the Constitution and By-Laws prepared by the Special Committee. Several members present discussed various sections of the proposed Constitution, and the Committee advised that the suggestions would he duly considered before submitting the final document, which would be duly presented and sent to the membership at large at least 30 days before the next Annual Business Meeting, Feb. 18, 1913. Professor Richards presented a resolution, seconded by Mr. Kirchhoff, making a change in the present Certificate of Incorporation, so that it would conform to the proposed changes in the Constitution and By-Laws; said resolution was unanimously adopted. Professor Richards presented another amendment to the Constitution, which had been purposely omitted from the printed list, but had been requested by many members, namely, the creation of a " Class of Fellows." This question was freely discussed at the Cleveland meeting (see Bulletin No. 71, November, 1912, p. 1348), and in view of the diversity of opinion it was-decided to present it in separate form for separate action of the membership at large at the Annual Business Meeting, Feb. 18, 1913. In answer to question, the President announced that the proposed amendments to the Constitution and By-Laws presented by Messrs. Corning and Stone at the Adjourned Annual Business Meeting, Oct. 7, 1912, and published in Circular Announcement No. 8, Oct. 15, 1912, were still on record. Professor Richards presented a syllabus of the proposed amendments to the By-Laws, and several sections were discused by members present, but no action of record was taken. Mr. Charles F. Rand read a letter from Mr. L. K. Armstrong, Sec-retary of the Spokane Local Section of the Institute, referring to the proposed amendments to the Constitution, and he announced that many of Mr. Armstrong's suggestions were, in one form or another, already incorporated in the proposed amendments submitted by the Special Committee. A special vote of thanks was passed to Dr. Albert R. Ledoux for the valuable assistance rendered by him to the Special Committee in the preparation of the proposed amendments to the Constitution and By-Laws.

Dec 1, 1912

By Oscar M. Wicken

Industrial minerals - being the basic materials for much of the industrial activity in the world -suffer or gain in the market place with changes in that activity. The period 1970 and early 1971 has been one of little growth in many of the mineral-consuming industries, particularly those associated with building and construction. Consequently, the production of many commodities revealed little or no increase above 1969 levels. The pick-up of construction activity in the last half of 1971, however, is expected to be at an intensity which will result in an over-all good year; for example, cement shipments may, establish a record. Some industrial minerals products that bucked downward trends were those allied with the agricultural industry. Phosphate rock shipments increased, particularly from Florida which contributes over 400/c of the phosphate rock in the western world. Potash had higher sales and production for the third straight year, which means that inventories are being eased. The catch-all term of ecology is an oft-mentioned theme among industrial minerals suppliers. Specifically, the need for control of dust emissions is adding a heavy capital investment burden to many of the producers; such a burden, in fact, that plants have had to cease operations because the cost of dust collection equipment could not be born. As an order-of-magnitude estimate, dust collection equipment for cement plants can run $2-3 million for a single plant; some estimates are that the total cost of dust collection equipment in a new plant can be approximately 20% of total investment. All minerals processers have dust control expense of greater or lesser proportion.

Jan 1, 1972