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By W. M. Weigel

LESS advances in the technology of non-metallic minerals than for several years past mark 1931, and the cause is easily found. The universal depression and decreased markets for non-metallic as well as other mineral commodities has forced the producers to cut out all unnecessary expense and reduce operating costs to a minimum in order to keep going, even on a reduced output, and to prevent insolvency. The result. has been that but 'little research has been carried on, and such as has been completed has in but few cases been put into commercial practice on account of the expense involved in new equipment and plant changes. The trend in the industry has been more economic than technologic, and the greatest effort put on market studies and sales attempts to expand markets and scrutiny of present operating 'practice leading to reduction of cost of production. This tendency has been increased by highly competitive conditions and the buyer's market which has prevailed and to the fact that price has been a greater factor than quality in placing orders. Only in cases where improvements in technology would immediately and effectively reduce costs or where in special cases there was but little competition with almost a monopoly control has actual technical development taken place.

Jan 1, 1932

By George S. Rice

ARIAL maps of prospective mineral-bearing territory have become almost indispensable in all the branches of exploration, and have proved particularly useful in the great oil area of the Southwest. About nine years ago aerial photographic mapping in this area was begun. The early product was lacking in scale accuracy and other control features, which limited its effective use. Since then, the evolution of the technique of such mapping has been steady, with several mapping companies collaborating with five of the leading oil companies, and aerial maps have been prepared covering practically the entire area.Improvements in cameras, film, and developing equipment and practice have resulted in more uniform and clearer photographs, but the outstanding development has been the accuracy obtained with respect to scale and all other control features. Maps are no

Jan 1, 1936

Primarily, 1961 was a year for widespread application of tools and techniques which have become operational in the past several years • • • Raising --Raise climbers and climber raising techniques have been improved; narrow veins as low as 55° dip are now being mined from climber raises. Climber modifications include: larger motors, tighter radius curves negotiated, improved lubrication and new methods of stowing the climber during a blast. Climber raises are now ventilated in several ways: a 12-in. diam flexible vent tube behind the climber rail; a 6-in. diam pipe behind the climber rail (with fan); or a 6 to 8-in. diam drill hole along the axis of the raise. In hot raises, these ventilating techniques have resulted in more rounds per shift. When driving raises from crosscut and lateral development, mucking machine loading of raise rock is preferred over slusher ramp loading for the following reasons: a) faster set-up and teardown of climber facilities; b) easier access for climber maintenance, repair and loading of raising supplies; c) area at the bottom of the raise can be kept cleaner. Both wide and narrow veins are mined from 7 x 7-ft climber raises at Butte and at Republic, Wash. At Republic, climber rollers have been modified to support increased weight when driving 55°dip raises • Drilling-The new largebore, short-stroke push feed drills are much faster drilling than previous models and are most satisfactory in hard ground. Although reports on maintenance studies of the new drills are not yet available, increased steel and bit wear and breakage, and increased drill maintenance are seen as potential problems. Mines in Montana and Idaho continue to test rubber-collared drill steel. The fabricating methods used are successful but advantages in increased steel life have yet to be proved. Underground applications of down-the-hole drills continue. Drilling speed and accuracy are reported as the outstanding advantages. Manufacturers are now hopeful of making drills which will operate in any direction. Present applications are for ventilation holes (to 8 in. diam) for climber raises, holes for hydraulic fill distribution, drain holes and "predrilled" raises. Good drilling accuracy has been reported to a depth of 200 ft. Cutting holes in drifting is seen as a future application

Jan 2, 1962

By George S. Rice

GROUND movement and subsidence is an important matter from several points of view and it is regrettable that more papers have not been written on this subject in the past year. Damage may be done to surface buildings or to the higher workings of a mine, and a study of the subject gives valuable in- formation on hanging-wall or roof control. The latter objective is strikingly shown in a recent paper presented by Jack Spaulding on Oct. 21, 1937, before the Institution of Mining and Metallurgy, of Great Britain, entitled "Theory and Practice of Ground Control in the Kolar Gold Field, India." All may not agree with some of his theories that were deduced from studies of the many violent rock bursts at depths of 5000 to 7000 ft., but the data obtained are of great value. His theories of symmetrical ring stresses and symmetrical domes which are pictured as perfect are rather hard to understand as such uniformity is un- likely in view of the irregularities in the formation due to folds and fractures of various kinds. All will agree in principle with this idea of domal effects, which have been observed in many countries, but they are generally irregular.

Jan 1, 1938

Correlation between Metallography and Mechanical Testing By H F MOORE (Henry Marion Howe Memorial Lecture Trans, vol 120 11,000 words ) The lack of effective correlation between metallography and mechanical testing from the days of Reaumur to the present is noted, and two general problems of such cor¬relation are stated (1) the correlation of qualitative test results with quantitative, and (2) the correlation of average results with maximum or minimum results Some correlation has been achieved, notably in the field of heat-treatment and in the study of elastic strength of metals Correlation is in the process of being developed in several other fields, including the quantitative study of the effect of grain size of metal on mechanical properties, of grain size and type of crystalline structure on the sensitivity of metals to weakening at holes, notches and other "stress raisers," and in the study of the starting phases of spreading, "fatigue" cracks Correlation of mechanical test results and metallographic study is needed in the study of such problems as the various theories of failure of metals, the meaning of and tests for service ductility of metals, and the relative damaging effect of defects inherent in metals, such as minute cracks and segregation, as compared with the damaging effect of "imposed" stress raisers, such as screw threads, sharp shoulders, etc The neces¬sity for more correlation of metallography and mechanical testing during student days is emphasized, and also the need of a better understanding on the part of engi¬neers of the significance and limitations of metallographic apparatus and results and of X-ray diffraction This should be matched by a better understanding on the part of metallurgists of the significance and limitations of mechanical tests of metals, of testing machines and strain-measuring apparatus

Jan 1, 1937

By N. O. Gray, John Henderson

Hydrogen-reduction data for naturally occurring single crystals and Prepared polycrystals of dense hematite have been presented. Results cover the temperature range 400o to 1000oC, for particles from ten sources, ranging in size from 0.07 to 10 mm and in shape from spheres to cylinders, cubes, and thin slabs. A consistent pattern of behavior has been demonstrated for single crystals and the reduction mechanism shown to be temperature-dependent. Below 579oC reduction is a simple topochemical process but at higher temperatuves it is complex and occurs in two distinct stages. Prepared particles from these laboratories behave in a similar manner to the single crystals. Data from two investigators showing topochernical reduction of Prepared particles above 575°C are inconsistent with that for other dense hematites. It is concluded that topochenzical reaction should not be used as a model for generalized rate expressions for dense hematites. SINCE 1958, McKewan1-6 has brought to prominence a simple concept of dense hematite reduction. This model is that oxygen is lost from a hematite particle undergoing reduction only from an oxide-iron interface that recedes in such a way that the oxide remaining retains the original shape of the particle, i.e., reduction occurs topochemically. An adjunct to this concept is that any intermediate oxides in the transition from hematite to iron only form thin layers so that oxygen cannot be lost from the particle without movement of the oxide-iron interface. Further, the rate of oxygen loss from the particle is said to be proportional to the area of the receding interface so that the iron layer grows linearly with time and the over-all reduction process can be described by the equation where ro and do are the initial particle radius and density, respectively, R is the fraction of the original oxygen lost, i.e., the fractional reduction, at time t, and K is the rate constant. The idea of an underlying simplicity in hematite reduction is attractive because it gives a tractable basis from which general theories of hematite reduction can be developed and it has received wide support,7-14 based mainly on the large amount of data13 that can be fitted to Eq. [I]. However, despite the fact that this equation has been derived for dense materials, the bulk of the data that have been used to test it13 have been for materials of only about 90 pct of theoretical density (5.26 g cm-3) or less, so that its generality for dense hematites has not been demonstrated. In any case, as will be seen, adherence of reduction data to Eq. [1] does not necessarily imply that reaction occurs topochemically. In this work only data for hematites approaching theoretical density are considered and it will be shown that in only one study besides McKewan's is topochemical behavior observed over the whole range of temperature investigated. For the majority of materials a linear rate of interface advance is observed to complete reduction only when wustite is not a stable intermediate phase in the transition of hematite to iron, i.e., at temperatures below about 575°C. Above this temperature, reduction is an exceedingly complex series of reactions that takes place in two distinct stages and it is only in the first stage that reaction in any way resembles a topochemical process. This means then that, far from representing general behavior as has commonly been supposed, topochemical reaction for dense hematites is only a particular behavior that may be observed under some circumstances. EXPERIMENTAL Hydrogen-reduction data have been collected and cross-checked in these laboratories by three techniques, weight loss, collection of water evolved in the reduction reactions, and direct metallographic examination. Details of these techniques are discussed elsewhere," where it is shown that results obtained by the three methods are in close agreement. The weight-loss method, by which most of the results were obtained, consisted of hanging the sample in a platinum mesh basket from an Ainsworth Model AV-AU-1 vacuum recording balance inside a vertical l 1/4-in.-ID alumina tube furnace. Dry deoxidized hydrogen was flowed downwards through the tube at 2 to 4 liters min-1 (stp). Single crystals from two sources and artificial oxides from three sources have been examined. The single crystals were from hematite deposits at Yampi Sound, Western Australia, and Brazil, the latter being obtained from Gregory, Bottley and Co., London, U.K. The "Yampi Blue" crystals were hand-picked from washed, magnetically concentrated, sized fractions, -200 mesh BSS (mean diameter ca 0.07 mm) and —36 + 44 mesh BSS (mean diameter ca 0.4 mm) while 10-mm cubes were cut from the Brazilian crystals with a diamond saw. The starting materials for the prepared particles were hematites designated, respectively, "Specpure Iron Oxide", Laboratory No. S639 from Johnson Matthey & Co. Ltd., London, U.K., "Calcined Ferric Oxide" from B.D.H. Laboratory Chemicals Division, Poole, U.K., and "Pigment Grade Oxide", EPR-50, from C. K. Williams & Co., Easton, Pa., U.S.A. Approximately spherical particles were prepared from the artificial oxides by rolling the material, moistened if necessary, in a glass jar, and cylindrical compacts approximately 10 mm in diam and of approximately equal height were pressed in a steel die at 200 psi. These spheres and cylinders were subsequently fired in oxygen for 20 to 100 hr at 1370°C. The

Jan 1, 1967

• "This country eventually may have to rely on foreign sources for some metals, not because it does not have them here but because it may have difficulty getting the labor to mine them. Few people realize the extent to which the 'old timers' are still the backlog of the important districts." --Fred Searls, Jr. • A new filter has been developed by Arthur D. Little, Inc., for the ABC which will remove all dust from the air. Submicroscopic asbestos fibers are used as filter media and are claimed to stop all dust and pollen while passing suitable quantities of air. •Out in front public relationswise is the Peabody Coal Co. which has launched a 15-min television news program on WNBQ at 10:30 C.S.T., Tuesday and Thursday nights. Clifton Utley, news commentator, will tell how coal is mined today and indicate, with pictures, the improvement in efficiency and safety which has resulted from today's mechanized operations. •Two hundred coal mining companies are using roof bolts as a means of supporting about 14 million sq ft of roof surface, Edward Thomas of the Bureau of Mines reported. Various types of metal and wooden pins can be used. The method was first used by the St. Joseph Lead Co. over 20 years ago, but is now being studied and adopted widely in metal, nonmetallic, and coal mines. * The first ten technical graduates have reported at Hanford Works in the state of Washington, to begin the newly installed General Electric rotational training program, believed to be the first of its kind at any U.S. atomic energy plant. The program is to provide suitably trained personnel for the nation's atomic energy program. •The need for top-notch scientists and engineers to stimulate mining programs in British colonies is acute. About 60 American experts are being sought for the ECA sponsored program. Positions for mining engineers, geologists, assayers, topographers, and petrologists are open. •Production of primary aluminum for the first quarter of 1950 was 322,4250008 lb which is 6 1/2 million lb more than was produced in the first quarter of 1949. Shipments of aluminum sheet, plate, and strip amounted to 259.772,1571b for the first quarter. •Policy on manganese procurement for the stockpile is being studied by a House Armed Services Subcommittee with the possibility of lowering specifications. The U. S. Bureau of Mines is drafting a bill to encourage domestic production for stockpiling through producer subsidies. 'It will have to be cleared by the Bureau of the Budget and other agencies before going to Congress. •Oil men consider dry holes a necessary evil in their search for oil. Last year 34 out of every 100 wells drilled were dry holes. Yet Texas Technological College is attempting to drill a dry hole on its campus at Lubbock, taking every precaution to make sure it is a "duster" so its petroleum engineering students can play around with experiments without being bothered by any messy crude oil. --Natural Resources Notes. •A portable alertness indicator which signals lethargy in persons doing monotonous jobs has been developed for the Navy's Special Devices Center. A possible application to hoistmen is indicated but broaching the matter to them would be tricky.

Jan 6, 1950

By Robert Keeney

IMPORTANT recent developments in the melting and annealing of non-ferrous metals include: 1. Melting of nickel silver in the vertical ring induction furnace. 2. Electric melting of stereotype metal. 3. The rotary-drum gas-fired brass melting furnace. 4. The low-frequency coreless induction furnace. 5. Finishing annealing of brass sheets with city gas1 replacing wood. -in the large brass-rolling mill. 6. Electric annealing of brass and copper tubing and sheets. 7. Replacement of oil by gas and electricity in the annealing of nickel-silver shells and stampings.

Jan 1, 1930

Jan 1, 1967

By P. E. Fitzgerald

SOME readjustments in the research programs of most of the oil companics and petroleum engineering schools have been made necessary by the war. The most obvious change has been the conversion from production engineering to problems more closely related to the nation's was effort. Many laboratories now devote much of their time to studies on products to be derived from petroleum. such as synthetic rubber, toluene, and substitutes for critical materials. Others are working to improve motor fuels including high-octane gasoline and the special lubricants required by the wide geographical range of the present conflict. Of great importance is the experience of the geophysicists, who are now devoting a great percentage of their time on instrument research and production or special apparatus required by the armed forces.

Jan 1, 1943

By C. S. Land

Relative permeability functions are developed for both two- and three-phase systems with the saturation changes in the imbibition direction. An empirical relation between residual nonwetting-phase saturation after water imbibition and initial nonwetting-phase saturations is found from published data. From this empirical relation, expressions are obtained for trapped and mobile nonwetting-phase saturations which are used in connection with established theory relating relative permeability to pore-size distribution. The resulting equations yield relative permeability as a function of saturation having characteristics believed to be representative of real systems. The relative permeability of water - wet rocks for both two- and three - phase systems, with the saturation change in the imbibition direction, may be obtained by this method after properly selecting two rock properties: the residual nonwetting-phase saturation after the complete imbibition cycle, and the capillary pressure curve. INTRODUCTION Relative permeability is a function of saturation history as well as of saturation. This fact was first pointed out for two-phase flow by Geffen et al. 1 and by Osaba et a1.2 Hysteresis in the relative permeability-saturation relation also has been reported for three-phase systems.3 Since saturations may change simultaneously in two directions in a three-phase system, four possible relationships arise between relative permeability and saturation for a water-wet system. The four saturation histories of this system were given by snel14 as 11, ID, DI and DD. I and D refer to the direction of saturation change (imbibition and drainage), with the first letter of the symbol indicating the direction of change of the water phase. As used in this paper, the second letter of the symbol refers to the direction of saturation change of the gas phase, i.e., D and I indicate an increase and decrease, respectively, in gas saturation. Only a few three-phase relative permeability curves have been published. Leverett and Lewis5 published three-phase curves for unconsolidated sand, and Snell4 reported results of several English authors for both drairrage and imbibition three-phase relative permeability of unconsolidated sands. Three-phase relative permeability curves for a consolidated sand were published by Caudle et a1.3 for increasing water and gas saturations (ID). Corey et a1.6 reported drainage (DD) three-phase relative permeability for consolidated sands. Recently, Donaldson and Dean7 and Sarem8 calculated three-phase relative permeability curves from displacement data on consolidated sands, also for saturation changes in the drainage direction. The only published three-phase relative permeability curves for consolidated sands with saturation changes in the imbibition direction (11) are those of Naar and Wygal.9 These curves are based on a theoretical study of the model of Wyllie and Gardner 10 as modified by Naar and Henderson.11 Interest in three-phase relative permeability has increased recently due to the introduction of new recovery methods and refinements in calculation procedures brought about by the use of large-scale digital computers. The scarcity of empirical relations for three-phase flow, and the experimental difficulty encountered in obtaining such data, have made the theoretical approach to this problem attractive. RELATIVE PERMEABILITY AS A FUNCTION OF PORE-SIZE DISTRIBUTION Purcell used pore sizes obtained from mercury-injection capillary pressure data to calculate the permeability of porous solids.12 Burdine extended the theory by developing a relative permeability-pore size distribution relation containing the correct tortuosity term.13 The works of Purcell and Burdine were combined by Corey14 into a form that has

Jan 1, 1969

By F. M. Lewis, Johnson. E. C.

BY now application of the liquid-solid cyclone to various classification problems in the chemical and metallurgical fields is more or less familiar. A less publicized application receiving wider consideration as time goes on is its use as a classifier in closed-circuit grinding operations. This paper presents the costs involved and the experience gained from operating a unit of this kind. In May 1951 the Tennessee Copper Co. installed in its London mill at Copperhill, Tenn., a liquid- solid cyclone in closed circuit with a 6x12-ft ball mill. The circuit in which this cyclone is used is the regrind or secondary grinding circuit of a copper flotation plant. Originally it consisted of a 7x1-ft conical ball mill in closed circuit with a bowl classifier. Changes made in the primary grinding circuit of the mill necessitated a regrind circuit of greater capacity. The bulk concentrate to be ground was raised from 900 or 1000 tpd to 1200 or 1300 tpd, and to accommodate this increase a 6x12-ft ball mill which had been in the primary grinding circuit was moved into the regrind circuit. When this was done it was found that the classifier was too small to give efficient operation. Space in the plant was at a premium, and since use of the cyclone offered considerable economy the installation shown in Figs. 1-3 was made.

Jan 6, 1954

By J. R. Sturgul, J. C. Wynn

Computers and computer applications in geophysics are fairly recent innovations. The area of data handling is one that has found many immediate applications. Initially, the use of computers involved in almost all cases, a batch-input arrangement requiring a trip to the local computer center, a wait and another trip. Even though the computer worked at incredible speeds, the time-delays, in case an error in the input data developed, often could be several days. Use of computers in mining exploration by medium-sized or small-sized companies and contractors has been almost non-existent beyond simple data reduction work. The principle J. R. Sturgul, SME member, and J. C. Wynn, both affiliated with the Dept. of Geosciences, University of Arizona, Tucson, presented this paper at the Eleventh International Symposium on Computer Applications in the Minerals Industry, reasons appear to be the time factor and the inconvenience of the frequent trips involved. With the advent of time sharing systems, whereby a company need only have access to a terminal, the main objections can be overcome. An Apparent Solution An apparent solution to the time and distance inconveniences which would permit more extensive use of computers in geophysical exploration, is to buy or lease/purchase a medium-sized computer and install it in or near one's office. This is a formidable proposition in terms of cost and programming time on both respects, but several mining companies of larger size have already gone this route. In most cases, the computers have been expensive devices with a limited memory or core size. For routine data handling this memory size is not restrictive; however, for many geophysical applications such as three-dimensional modeling this can be critical.

Jan 10, 1973

By W. J. Joslin

The frontal-advance equation can determine how the fluid withdrawal rate and subsurface operating pressure influence oil recovery from pressure-maintained reservoirs having characteristics favorable for efficient vertical segregation. For effective vertical segregation in formations having low dip angles, the requirements are: thick, massive sands, low viscosity oil and high vertical permeability with few discontinuous shale members. This approach has been successfully applied to the LL-370, which is a massive Eocene sandstone reservoir containing crude with an average gravity of 26" APT, a dip of only 3" and vertical permeability of ½ darcy. The average gas cap saturation was calculated for various rates of vertical gas-oil contact movement corresponding to a wide range of reservoir producing rates. This method also evaluated the effect of different pressure maintenance levels on oil recovery. Applicability of this procedure for calculating the present oil saturation in the LL-370 gas cap has been substantiated from field performance, where the oil saturation was computed by comparing oil recovery with the gas cap volume vacated. INTRODUCTION During the natural depletion history of the LL-370 reservoir, located in Lake Maracaibo, Venezuela, excellent vertical segregation resulted in the formation of a thin gas zone over a substantial portion of the oil-productive area. Subsequently, gas injection forced this thin gas-saturated zone slowly downward, reducing the oil saturation in the gas cap to a low value. The oil recovery has been raised considerably above earlier predictions where vertical segregation effects were under-estimated. In order to determine the maximum efficient producing rate and optimum operating pressure for this reservoir, a vertical gas frontal-advance analysis has been made through application of the fractional flow equation. LL-370 RESERVOIR CHARACTERISTICS The reservoir consists of a truncated monocline of massive. highly-permeable Eocene sandstone, called the B-b formation, covering an area of more than 13,500 acres. The original oil in place was 2.17 billion STB. Internal non-sealing faults subdivide the structure into four blocks called the B-6-x.6, 10, 11 and 13, which are effectively bounded by major faulting on the flanks, an unconformity updip to the west, and an immobile aquifer to the southeast. The producing formation occurs at an average depth of 5,250 ft subsea and has a closure of more than 1,500 ft. A typical producing section has a net oil sand thickness of 170 ft. Scattered throughout the section are a few randomly-positioned shale lenses which increase in thickness and areal extent downdip. The reservoir rock and fluid properties vary with depth. The permeability and produced oil gravity are 1600 md and 28" API at the top, compared to 300 md and 18° API at the water-oil contact. The productivity of updip wells is, therefore, much higher than the reservoir average. The reservoir oil was originally saturated at the crest, grading to a slight degree of undersaturation at the water-oil contact. There was no original gas cap; and material balance and the field performance indicate no water influx. Except for the northern B-6-x.6 block, the fluid and rock properties have already been published.' Average LL-370 reservoir properties are shown in Table 1. RESERVOIR PERFORMANCE UNDER NATURAL DEPLETION Fig. 1 shows production performance from 1939 to date. Early development was gradual, with 30 wells pro-

Jan 1, 1965

By C. H. Mathewson, E. M. Thalheimer

In planning the present experiments, we have made a particular effort to secure that adjustment of working conditions which would render the forthcoming tests most serviceable by way of indicating the comparative properties of the three different commercial grades of copper used. More specifically, we have endeavored to obtain certain definite information with respect to the relative behavior under test of ordinary electrolytic copper and furnace-refined lake copper containing (a) a moderate percentage of arsenic and (b) a rather large percentage of arsenic, in addition to the usual content of silver and other impurities. These comparisons were made systematic and comprehensive by testing throughout a series of (eight) reductions running from 0 to 70 per cent. in the case of cold-rolled metal, and throughout a series of (15) temperatures running from 100' C. to 1,000" C. in the case of annealed metal. In other words, a survey of properties similar to that made by Grard,' in the case of electrolytic copper, was here repeated (with modifications) and extended to two other commercial varieties of copper. The great importance of copper both as a material of construction and as the base of our most important alloys (aside from steel) has led to innumerable investigations of its properties, particularly in commercial forms. Naturally, the merits of furnace-refined lake coppers us. those of the very pure electrolytic product have furnished the subject of much experimental work and animated discussion, wherein the effect of arsenic has by no means been overlooked. In the literature of the past 10 years,

Jan 1, 1917

By F. Windolph

There are no hard and fast rules for building tailing dams, and each case has to be analyzed individually because of special conditions encountered at each location. Certain criteria are used for building dams at Climax, Colo., where they must be placed in rather steep mountain valleys on foundations that are practically impermeable. The tailing is relatively coarse, and a coarse fraction stays near the berm where it is deposited, while most of the fines flow with the water to the pool. Thirty years experience has led to certain design for toe dams, decanter lines and towers and tailing dams. A new tailing disposal area, started at Climax in 1958, will ultimately have a height of 495 ft and impound about 300 million tons. The following applies to the construction of this new tailing area.

Jan 11, 1961

By Raymond Franz

Of the many types of capital equipment found in a surface operation, draglines and mining shovels are probably subjected to the most severe service. Yet, some excavators have seen a generation or more of continuous service-proof, if any is needed, of their ruggedness. To keep these expensive pieces of machinery operating, a continuing maintenance program which includes field weld repairs is essential. During an excavator's working life, minor cracks may appear in parts of the steel structure, caused by fatigue and sometimes material defects-defects so small they could not be detected during manufacture.

Jan 6, 1978

By Martin T. Broome

INTRODUCTION The Luanshya Mine is situated in the southern part of the Zambian Copperbelt. The copper ore deposit is stratiform, and is preserved in a synclinorium known as the Roan/ Muliashi basin. Roan shaft (formally called No.14 shaft) is located at the eastern end of the syncline and is theoldest of the presently operating hoisting shafts, being sunk during the 1930's. It presently hoists some 45 per- cent of the total Luanshya Mine production. A cross-section through the shaft is shown in figure 1. The ore formation on the south limb is unmined on this section because until recently it was believed that such mining might cause damage to the shaft. This paper examines the influences of adjacent mining on this so-called 'shaft pillar', and describes the mechanics of subsidence of the pillar itself. GEOLOGY AND STRUCTURE Figure 1 shows the general form of folding in the vicinity of Roan shaft. The north and south limbs of the main syncline approach parallelism, with the bottom of the trough fairly smoothly rounded. The axis of the - trough plunges to the west-north-west at 6° - l0°. A brief summary of the major lithologies present in the Roan basin is given in table 1, however, the performance of the overall structure during progressive mining of the ore horizon is controlled by the following features in addition to the mining method. Intraformational Contacts These are characteristically weak in most geological environments. The BC/RL7 contact is an unconformity between moderately weak quartz-biotite schists below (unconfined compressive strength 40 - 80 MN/M 2), and strong quartzites above (U .C .S. 170-200 MN/M2) Subsequent formations are conformable, and planes of weakness are generally the result of contrasting lithology (see below). Weak Interbeds The Rt7, RL6, RL5, RL3 and RU2 horizons consist predominantly of quartzitic rocks, i.e. conglomerates, quartzites and argillites, and as such are generally strong and considered suitable for the positioning of development. Between these however, lie two much weaker dolomitic horizons, the RL4 and RU1. The Rt4 is the main hangingwall aquifer, and must be drained prior to mining. Drainage results in an extremely weak, blocky cavernous horizon which usually requires support if exposed by development. Similarly, the RU1 formation is comprised mainly of dolomites and dolomitic arqillites which are weak and cavernous. In the eastern part of the Roan/

Jan 1, 1981

By Arno C. Fieldner

METALLURGICAL coke and the by-products of the carbonization of coal continue in strong demand. Nearly 500 new by-product ovens were constructed in 1943. Output of by-product coke in the first ten months of the year was about 2 1/2 percent higher than in the corresponding period of 1942, but beehive production remained on approximately the same level as last year and constituted about 11 per cent of the total coke output.

Jan 1, 1944

The income of the Institute is derived from dues, subscriptions to Mining and Metallurgy and sale of publications. These sources are fortunately supplemented by the interest from invested funds now amounting to over $500,000, a considerable portion constituting endowments for especial purposes. Aside from the medal funds the principal endowments are the James Douglas Fund for support of the Library, the Rocky Mountain Fund and the Seeley W. Mudd Memorial Fund. The income from the two last named is available for the support of research and a variety of other purposes, It is allocated by the Board of Directors upon recommendation of standing committees in each case. An active effort is being made to increase the endowments of the Institute, it being felt that unusual opportunities exist for research and public and professional service through the organization and at a minimum of expense. J. V. W. Reynders is chairman of the Endowment Committee. Seeley W. Mudd Memorial Fund THE Seeley W. Mudd Memorial Fund, consisting of $100,000, was given the Institute in 1929 by the family of Colonel Mudd who had served the Institute as Director, Vice-president and on many important committees. His long career of distinguished professional and public service is fittingly commemorated by this fund. The income is available for support of research and other special purposes. In view of Colonel Mudd's life work with the nonferrous metals and his keen interest in the younger men of the profession it is purposed to apply the fund particularly to the benefit of these two. Control of income is exercised by the Board of Directors on recommendation of a Committee consisting of the President and Secretary, ex officiis, together with three others selected by the Board. The Committee consists at present of the following members: W. H. Bassett, President; H. Foster Bain, Secretary; Harvey S. Mudd serving until October, 1931; Edgar Rickard serving till October, 1932; George Otis Smith serving until October, 1933. On recommendation of this Committee the Board has authorized as a first project the preparation of a series of small books designed especially to be helpful to the Junior Members. These are now being written and it is hoped will be available for distribution in 1931. The list includes: A Brief History of American Mining, by T. A. Rickard; Mining Costs, Why and What, by Arthur Notman; Introduction to Mineral Economics, by H. Foster Bain and T. T. Read; Choice of Methods—A Record of Experience in Making Decisions, with chapters by W. H. Bassett, F. W. Bradley, E. DeGolyer, Howard N. Eavenson, A. B. Parsons, J. V. W. Reynders, L. D. Ricketts, Robert E. Tally, Pope Yeatman and others. One other book is projected but final selection has not been made. The purpose of these books is to afford the younger men who now come into a highly specialized profession some substitute for the broad

Jan 1, 1930