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By William G. Gates

INTRODUCTION The Heath Steele mine is located in the Bathurst-Newcastle area of northern New Brunswick. It is jointly owned by American Metal Climax, Inc. and the International Nickel Company of Canada who hold a 75% and 25% interest, respectively. The ore deposits of lead, zinc and copper sulphide occur in very fine grained pyrite and/or pyrrhotite masses. A consistent spatial relationship with a quartz feldspar porphyry is characteristic of these deposits and the many other similar sulphide deposits in the district. The two principal mineral assemblages of pyrite-sphalerite-galena, and pyrrhotite-chalcopyrite-pyrite, occupy characteristic positions relative to the enclosing rocks. This feature and the nature of the sulphide mineralization are described and the variations in metal content are noted .with special emphasis on the lead-zinc ore zones. The mine product ion rate is 3,000 tons per day of a mixed lead- zinc and copper ore which is extracted from the B-1 zone. The complex nature of the ores presents many metallurgical problems. Optimum metal recoveries are achieved when milll feed grades are relatively consistent and proportions of the contained metals are with in acceptable limits. Ore outlines and stoping blocks are delimited by close spaced diamond drilling. From this information it is possible to forecast the grade of any portion of a stoping block. Production from the various stopes may then be scheduled so as to achieve an acceptable mill feed grade.

Jan 1, 1970

By W. N. Logan, P. Simpson

There was less activity in the petroleum industry in Indiana in 1933 than in previous years, owing largely to adverse market conditions. The only development of any consequence was for oil in Perry and Vander-burgh counties in southwestern Indiana, a few gas wells being brought in in Jay County in northeastern Indiana. Indications are that there will be more activity in southwestern Indiana in 1934. Little change may be expected in northeastern Indiana. One hundred and sixty wells were drilled in Indiana in 1933, of which 57 were dry, 44 produced oil, 38 produced gas and 21 either were not completed or information on them was lacking. There were 153 wells abandoned and plugged in 1933, as compared to 205 in 1932. Southwestern Indiana This area centers about Gibson County and is the principal source of oil and gas production in the state. Production is from the Lower Pennsylvanian and Upper Mississippian formations. Oil production for 1932 was approximately 847,000 bbl. and for 1933 was 804,000 bbl. Gas production for 1933 was 942,000,000 cubic feet. The Siosi field, in southwestern Vigo County and northwestern Sullivan County, discovered six years ago, produced approximately 244,000 bbl. in 1932 and 223,000 bbl. in 1933. Production is from Devonian and Silurian formations. The oil is high gravity, but contains considerable sulfur. The Shelburn and other small pools in central Sullivan County produced approximately 68,000 bbl. in 1932 and 2,000 bbl. less in 1933. Production is from one or more of five horizons in the Pottsville and is obtained at 600 to 800 ft. This area also produces approximately 19,000,000 cu. ft. of gas a year, supplying the city of Sullivan. The field is over 20 years old. The Gibson-Pike County area, made up of many small pools, including several in southern Knox and southwestern Daviess counties, produced approximately 486,000 bbl. in 1932 and 450,000 bbl. in 1933. This production is from the Mansfield sandstone of Pennsylvanian and/or

Jan 1, 1934

By Chris M. Healey

"Perhaps the single most significant variable in the evaluation of a mining project is the reserve estimate. Many parameters are considered when estimating reserves, among them geology. This paper examines the link between the quality of a reserve estimate and a good understanding of the geological controls for the deposit. A clear understanding of the geometry is essential to the accurate definition of the shape and size of the deposit. This includes the definition of any structural controls as well as the proper interpretation of the stratigraphy. Further when the distribution of grades is erratic and there is consequently a high nugget effect, there are significant problems in estimating the true grade of the deposit.Two Saskatchewan examples are presented, one with good knowledge of the controls and therefore good estimates of reserves, and the other with a poor understanding of the geology and resultant problems in deriving good estimates. In both cases the reserve estimates at various stages in the project development are compared to actual results from underground work. The first example is the Star Lake Mine where just about all the estimates were within 10070 of the actual on both tonnage and grade. The Laurel Lake deposit is discussed to show how problems in interpreting the geological data make reserve estimation very difficult. Laurel Lake has the additional problem of erratic grade distribution."

Jan 1, 1992

By F. Weinberg

INTEREST is currently being directed toward grain boundary morphologies in zinc in terms of grain boundary facetingl and grain boundary energies.' Some years ago the present author attempted to measure grain boundary energies in 99.999 pct purity Zn as a function of boundary angle, using the standard procedure of measuring equilibrium angles of the boundary traces at triple points. This followed an investigation he carried out on preferential melting of |H (112) Fig. 1—Electron transmission micrograph of a stacking fault, grain boundary intersection in copper. GRAIN BOUNDARY STACKING FAULT Fig. 2—Schematic representation of the intersection of Fig. 1, indicating inclination angles 0 and trace angles $. specimens were prepared by the Bollman technique in an electrolyte of 70 pct methanol, 30 pct HNO3 main-tained at -30°C. The interfacial free energy of the high angle grain boundary and of the stacking fault is assumed to be thermodynamically equivalent to the corresponding in-terfacial tensions. In terms of the true dihedral angles & between the intersecting interfaces, the equilibrium of interfacial tensions in the direction parallel to the stacking fault yields: ysF = -ygb(cos F1+ cos ±cosF2) Here, ysF is the stacking fault free energy and ygb is the grain boundary free energy, assumed equal on both sides of the intersection. Forces acting normal to the grain boundary, of the form ??gb/?F,l are assumed negligible as the grain boundary remains straight for a considerable distance on either side of the intersection. The micrograph of Fig. 1 may actually consist of several closely spaced stacking faults on the same slip plane. The actual point of intersection between the grain boundary and the first stacking fault, and the equilibrium configuration of the intersection, should not be affected by the presence of the other faults, as

Jan 1, 1970

By Roberta L. Hudak, Ellsworth R. Spencer, Eric R. Bauer, Adam K. Smith

The National Institute for Occupational Safety and Health (NIOSH) is conducting research with the objective of preventing hearing loss in the mining industry. Longwall mining is one sector that has received considerable attention. Studies involving the monitoring of worker noise exposures, characterizing equipment sound levels and dominant noise sources, evaluating engineering noise controls, analyzing hearing protection device (HPD) effectiveness, and testing of improved sound level monitoring techniques specifically for longwall mining systems, are being conducted. The research efforts revealed that stageloader operators are the most exposed longwall workers, with the discharge end being the noisiest location along the stageloader. In addition, the studies have shown that using stationary dosimeters, coupled with observational data of the cutting cycle and worker habits, has the potential for improved monitoring of the effectiveness of engineering noise controls. To address the ineffective use of soft foam earplugs, a simplified 3-step method was developed for inserting soft foam earplugs. Results indicate a 9 dB greater attenuation after training subjects on the 3-step method. Finally, muff type HPDs are being evaluated for effects of speech intelligibility in noise. The combined results of these studies illustrates that much can and has been done to prevent noise-induced hearing loss (NIHL) in the mining industry, especially with respect to longwall mining workers. This paper presents an overview of ongoing studies, a progress report of results, and the implications for reducing worker noise exposures and preventing NIHL in longwall mining workers.

By K. Kim

INTRODUCTION A thorough evaluation of the geologic material being considered must be conducted to determine the feasibility of constructing a large-scale underground facility in a deep geologic formation. The design and construction of a nuclear waste repository in basalt, due to the unprecedented nature of the project, adds significantly to the need for thoroughness of this evaluation and mandates that geoengineering data and analysis be of the highest quality. The investigations required to collect the data encompass in situ measurements and observations, as well as laboratory and field tests. Mathematical (numerical) models, which are required to predict the long-term performance of the repository structure, must be developed to evaluate rock mass behavior at canister, room, and repository scale and eventual 1 y must be validated through in situ tests and monitoring. The information generated from these geo- mechanics investigations is essential for assessing site suitability and will be utilized in the development of the repository design, the engineered barrier design, and the evaluation of repository performance. The Hanford Site near Richland, Washington is one of nine sites throughout the nation being investigated by the U .S. Department of Energy as a possible location for the first high-level nuclear waste repository in deep geologic formations. The process of site characterization is currently in progress. If the site is nominated by the U.S. Department of Energy, an extensive program will be undertaken, the culmination of which will be a decision on the suitability of the site for waste disposal. There are a mu1titude of elements to the proposed site characterization

Jan 1, 1984

By K. D. Jacob

ALL types of commercial phosphate rock produced throughout the world contain fluorine in quantities ranging from approximately 0.4 to 1.3 per cent in the Curacao and Christmas Island phosphates to 3.1 to 4.2 per cent in the phosphates of the United States and North Africa1. For a given type of rock, the fluorine content is usually roughly propor-tional to the phosphorus content. SIGNIFICANCE OF FLUORINE IN PHOSPHATE ROCK On the basis of chemical and X-ray diffraction studies, Hendricks and co-workers2 concluded that fluorapatite, Ca10F2(P04)6, is the essential phosphatic constituent of the commercial types of domestic phosphate rock. On the other hand, Bredig and co-workers3 have recently advanced the opinion, also based on X-ray diffraction studies, that the mineral phosphates usually contain carbon dioxide in the apatite lattice, and that the phosphate rocks of. the United States are really fluorcarbonate apatites. However, the domestic types of phosphate rock do not seem to differ greatly from coarsely crystalline fluorapatite in their behavior toward chemical reagents in general, and for the purpose of this paper it will suffice to consider fluorapatite as being the essential phosphatic constituent of these types of rock.

Jan 1, 1936

By Philip Wilson

THE genesis of some orebodies has been explained by the mingling and chemical interaction of water solutions of different compositions and the consequent precipitation of the mineral load of one or both solutions at their confluence. While this process can be proved in the laboratory, rarely can a positive demonstration be found in nature, for the conditions at the time an ore deposit is being worked are usually entirely different from those that existed when the orebody was formed. For this reason, the present deposition of copper carbonate in the southern end of the Briggs Mine of the Calumet and Arizona Mining Co. near Bisbee, Ariz., is of great interest. The developed orebodies in the Calumet and Arizona mines are roughly confined to two broad parallel zones separated at the north by a wedge of. Copper Queen ground and at the south by an undeveloped block of Calumet and Arizona ground about 2000 ft. (610 m.) wide. The more westerly zone includes the Irish Mag, Oliver, P. and D., and Cole mines, none of which have been operated since 1919. Much of the water from this division is carried from the 1400-ft., or bottom, level at the southern end of the Cole mine in a long water drift through the undeveloped block to the 1300-ft. level of the Briggs mine at the southern end of the more easterly zone.. Most of this water comes originally from outlying areas in the P. and D., mine, passing through parts of the lower levels of the Cole mine, which are heavily mineralized with iron and copper sulfides. This sulfide zone has been opened up and slowly oxidizing for years. Originally a pure, potable water, the analyses of which are shown under A in Tables 1 and 2, on its way through the mineralized area in the Cole mine it gathers copper, calcium, magnesium, iron, and aluminum sulfates, a load of dissolved mineral salts almost four times as great as that which it formerly carried; analyses B

Jan 7, 1922

By N. J. Gran, W. R. Opie

HYDROGEN in molten aluminum and aluminum alloys, which precipitates during cooling and solidification, is the principal cause of pin hole porosity in ingots and castings. Much attention has been given to determining the effect of temperature and pressure on the solubility of hydrogen in pure aluminum, but little data are available on hydrogen solubility in aluminum alloys. This investigation was undertaken to check results reported for pure aluminum and to show the effect of silicon and copper additions on the amount of hydrogen contained by molten alloys. Previous determinations of the solubility of hy-drogen in molten pure aluminum are plotted in fig. 1. The most reliable data appear to be those of Ransley and Neufeldl and of Baukloh and Oester-len.' The latter authors also report some results on the effect of copper and silicon additions. Up to 6 pct these elements decrease the solubility of hydrogen quite rapidly, with a definite minimum noted at 6 wt pct for both copper and for silicon, although no reason is apparent for these minima. Experimental Procedure The solubility of dry hydrogen in pure aluminum, aluminum-silicon, and aluminum-copper alloys was determined by the method of Sieverts.8 This consists of determining the volume of the gas system above the molten metal at a given temperature and pressure by using an insoluble gas. This volume is referred to as the "hot volume." The system is then evacuated and the soluble gas is introduced at the same temperature and until the same pressure is reached. It is necessary to introduce enough of the soluble gas to fill the space above the metal plus the soluble amount. The difference in the volume of soluble gas and the "hot volume" is the solubility. The accuracy of solubility measurements by the Sieverts' method is primarily depend-

Jan 1, 1951

By John B. Miles

The present period of depression in the iron industry, with the resultant close approximation of the cost of production to the selling-price of pig-iron, should make the discussion of this subject at this time not only interesting but profitable. It is possible that it may result in the collection of data, which when added to those set forth in this paper will clearly indicate the influence of the rate of driving a blast-furnace upon its fuel-economy. The question is not whether an excessive rate of driving (meaning a rate definitely in excess of the average rate in the United States) results in an increase in the fuel-consumption, but rather whether a rate considerably less than the average does not result in a marked decrease in the fuel-consumption. The commercial and metallurgical sides of this problem must be kept separate. With a large margin between the cost of production and the selling-price of pig-iron, and a plant already in operation, it is frequently profitable to sacrifice a couple of hundred pounds of fuel per ton of pig-iron in order to secure the greater gross profits resulting from a larger tonnage. When this margin decreases with a plant in operation, or when the determination of the size of a new furnace intended for a certain production confronts the management, a clear understanding of the effect of the rate of driving upon fuel-economy becomes necessary. If it be granted that slow driving leads to low fuel-consumption, it should be borne in mind in the design of a new plant for the production of a certain tonnage that the adoption of an economical rate of driving increases only the size of the furnace proper, whereas, due to the decrease in quantity of blast required on account of the decrease in fuel burned, the stoves, the blowing-engines, the boilers and the piping may be de-

Jan 1, 1909

By H. V. Churchill

THERE are two distinct methods of combating corrosive conditions. The first and most popular method is to choose a surface or material which will give adequate service under the specific and general conditions which are present. The second is a control or modification. of the corrosive conditions to the end that metals and materials which would be attacked and corroded without such control or modification may be used. Under the first method of attack of the corrosion problem may be grouped such devices as the selection of metals or alloys which offer great resistance or the use of protective coatings such as paints, lacquers or metallic coatings. Such procedures are exceedingly useful. It is, undoubtedly true that most of the problems of corrosion will be solved by recourse to this first method of attack. However, it must be remembered that there are many conditions in which metals are used where the choice of the particular metal to be used must depend upon other factors than corrosion behavior. Some of the factors which may govern the selection of metals for specific use are the physical and mechanical properties of the metals. But there is another factor which is of prime importance and that is relative price. It is the pressure of these factors of mechanical properties, physical characteristics, and relative price that has acted as the stimulus for the second method of combating corrosion. The producer and user of various metals is confronted with the fact that because of mechanical properties, physical characteristics, or price, the use of a particular metal is desirable even though the corrosion conditions are adverse to the use of the metal. In many cases, the successful use of the metal may be made even though it is impossible to protect the metal by coatings. This is rendered possible by control or modification of the corrosive media.

Jan 1, 1929

By Peter I. Brooker

Elementary estimation methods in which blocks are assigned values according to a geometrical area of influence concept are investigated for a tabular deposit. This quantitative assessment of the estimation technique is made using Matheron's geostatistics which allows the variance of the error between actual block values and estimated values to be found once the semi-variogram is known. For the deposit in question it is shown that the elementary technique makes poor use of the available information. There is a 20% relative error associated with it, whereas by using the optimal technique of kriging this can be reduced to 9%. An infill drilling program, which might have been suggested on area of influence results, would reduce the estimation variance only marginally over that of the current campaign; the relative error being lowered to 6%. Thus the geostatistical analysis shows this would be an unnecessary expense. The accuracy of an earlier drilling stage is also studied and it is shown that with the information available at the earlier stage block values could have been known with a relative error of 13%. Drilling could have stopped then if this were reckoned a tolerable error level. These results are all obtained for blocks whose size is dictated by the mining engineer and is set at the current grid size. In the area of influence approach smaller blocks are considered as the grid becomes finer and a study of the accuracy of area of influence estimates and kriged estimates for differing block sizes is presented. Between drilling stages more information from which the semi- variogram is calculated becomes available. The sensitivity of the estimation to changes in the semi-variogram parameters between earlier and current drilling programs is investigated.

Jan 1, 1977

By H. C. Lay

No one who knows the conditions of altitude, difficulty of access, shortness of working-season, etc., under which the work of the U. S. Geological Survey in the Rocky Mountains is carried on, can fail to be impressed with the magnitude and accuracy of the results obtained. Yet, in the necessarily brief time given to any one district, maily minor features must remain unregistered. The purpose of this paper is merely to place on record observations, made during nearly eighteen years, of local phenomena in themselves unimportant, which, however, if collated with similar memoranda from neighboring regions, may lead to something of value. The Telluride quadrangle in southwest Colorado is a tract of fifteen geographical minutes on a side, the NW. corner of which is in Long. 108º W., Lat. 38º N. Topographically it is essentially a lofty horseshoe, some of the peaks of which rise more than 14,000 ft. above tide, the interior (with an average altitude of 9000 ft.) being the eastern edge of the rolling Colorado-Utah plateau, and, in its turn, deeply cut by the canons of the San Miguel river and its tributaries. The range-summits are mainly igneous rocks, partly intrusive (such as massive " stocks" and laccolites, left bare by superior erosion), but mostly bedded volcanics of an average vertical thickness of 3500 ft., which change with changing height from andesite to rhyolite. The lowest series of these volcanic rocks, known as the San Juan formation, lies conformably upon the sedimentary San Miguel conglomerate, which dips gently east., and is attributed provisionally to the

Jan 1, 1902

By P. W. George

THE rapid increase in cost of discovering new orebodies by churn drilling in the Tri-State district has led to some attempts to lessen the expense by using geophysical methods. Electrical prospecting was tried three or four years ago, but no successful results were recorded. In 1926, the Federal Mining and Smelting Co. engaged the North American Exploration Co., of Houston, Texas, to make some tests with the torsion balance. At first, it was thought that the most favorable conditions for discovery of ore deposits with the torsion balance would be in locations where the ore was known to occur at rather shallow depths, FIG. 1.-CROSS-SECTION OF DUENWEG LEASE. therefore the first trial was made at Duenweg, east of Joplin, where some zinc ore had been developed at a depth of 130 ft. The gravity gradients at 61 stations on a tract of about seventeen acres indicated plainly one large zone of maximum gravity and a smaller narrow zone of minimum gravity. Fourteen churn-drill holes, half of which struck ore, show that all the ore found was located outside the zones of maximum and minimum gravity. In the zone of maximum gravity the limestone beds were closest to the surface, and the first chert beds encountered were at the greatest depth. The results (shown in Table 1) indicated that the gravity of the limestone was greater than the gravity of the fractured chert together with its orebodies, and probably also greater than the bouldery soil and clay on top of the limestone. A cross-section of the Duenweg lease is shown in Fig. 1.

Jan 1, 1928

By Wilhelm in der Schmitten

A necessary condition for a uniaxial stress distribution in compression testing is that the specimen end surfaces make full contact with the apparatus compression plates. In addition all compression surfaces must be machined perpendicularly to the loading axis. In general this condition is not sufficiently fulfilled in a simple apparatus. Therefore on application of the load the compression plate may first touch the specimen at one point only. This may cause crumbling of the specimen if the material under investigation is brittle (e.g., ionic crystals). It also precludes a precise study of the beginning of deformation as the effective cross sectional area is unknown. In addition a complex stress state is set up which renders quantitative work impossible, e.g., on dislocation density and arrangement as a function of stress. To overcome these difficulties a "self-adjusting" upper compression plate is required. A simple and reliable method of achieving this is shown in Fig. 1: A steel hemisphere is placed on the specimen. As soon as the compression plate (which no longer needs precise machining) makes contact with this hemisphere the load is uniformly distributed over the whole specimen surface, and a homogeneous uniaxial state of stress results. An advantage of the method is that the loading is always central, even when the specimen surface is not parallel to the compression plate (Fig. 1, dashed line). Therefore to a first approximation a uniaxial state of stress is maintained if the misorientation of the specimen end surface is small. Two typical stress strain curves of identically prepared sodium chloride crystals are shown in Fig. 2; curve 1 was taken without and curve II with the hemisphere under otherwise identical conditions. The improvement in the accuracy of defining the beginning of elastic and plastic deformation is clearly indicated. The writer wishes to thank the Deutsche Forschungsgemeinschaft for financial support, and Professor P. Haasen for providing facilities for this work.

Jan 1, 1962

IN international affairs, the great event of June was the meeting of representative bankers at Paris -for consideration of the arrangement of a large loan to Germany. The conference dissolved in futility. Following this abortive conference, the delegates to the parley at the Hague assembled there on June 15. America is not represented at the Hague, any more than at Genoa. The British view the conference seriously and have Leslie Urquhart, the highest authority on Russia, attending in an official capacity. The Irish had their election and voted by strong majority in favor of the treaty with Great Britain, which was happy, but the general situation in Ireland is miserable. In China there were spectacular military and political events. Economically, Japan was in trouble. Conditions are becoming better in India, although no yet settled. Egypt has troubles still. Australia has a better chance for welfare, following the overthrow of its labor govern-ment early in April last. In Europe it is hard to discern any improvement except in Great Britain. Business in Great Britain has been slowly widening. The future of Great Britain, which is chiefly an in-dustrial country, depends on finding employment for its, 1,750,000 idle men. Personalities figured largely in June. Lenin's health was represented as having failed so that the govern-ment of Russia has had to be-turned over to a trium-virate. All of this has been denied. It is clear that some. mighty events are transpiring there. The assassination of Doctor Rathenau in Germany is probably also an occurrence of portent. The murder of Field Marshal Wilson, in London, tended to in-crease anger in England against the Irish. In the United. States the attention of Congress was concentrated on the soldier bonus, the tariff bill and the subsidy for shipping. All of these projects are economically bad and are of the same nature, viz., the allotment of a bounty to some classes of people, without consideration to the general national interest and welfare.

Jan 7, 1922

By S. K. Kawatra, T. C. Eisele

"Coal-fired electrical power generation plants produce 56% of all the electricity in the U. S., burning approximately 860 million tons of coal annually. This results in production of 58 million tons of fly ash; 19 million tons of bottom ash and boiler slag, and 23 million tons of desulfurization sludges. These are a considerable disposal problem, and it would therefore be very valuable to be able to sell these residues and byproducts as useful materials, rather than paying to dispose of them in landfills. However, utilization rates are currently very low, below 32% even for the most thoroughly commercialized combustion byproduct (fly-ash). This poor utilization rate is a result of the high impurity content of combustion byproducts, which make them unsuitable for existing markets. The experiments described in this paper were therefore carried out to study the application of mineral processing techniques to upgrading combustion byproducts.Experiments were conducted to upgrade and purify low-grade combustion products to produce highgrade, readily saleable materials. A process was developed for removing unburned carbon from coal fly-ash by froth flotation, using reagents originally developed for flotation of oxidized coals. This technique could reduce the carbon content of fly-ashes containing up to 11.1% carbon to less than 2%. The froth product was sufficiently carbon-rich that the recovered carbon has value as fuel, or as low-grade activated charcoal.Fly ash was also examined as a binder for producing iron ore pellets, primarily as a substitute for bentonite. It was found that Class F fly ash in combination with an activator (calcium hydroxide) was an effective pellet binder at dosages comparable to the currently-used dosages of bentonite clay. While the flyash worked very well alone, tests in combination with bentonite showed that fly-ash/bentonite mixtures had significantly worse binding performance than either pure bentonite or pure fly-ash-based binder. This was determined to be due to the fact that bentonite and fly ash have profoundly different binding mechanisms, with fly-ash undergoing a pozzolanic chemical reaction while bentonite binds through a physical attachment process."

Jan 1, 2003

By D. Newman

The objective of this is paper is to review the current state of knowledge and practice in highwall mining (HWM). HWM has become a standard method in surface mining, commonly used alone or in conjunction with contour or slot mining. It provides 800-feet to 1,200-feet of additional recovery when the economic stripping ratio is reached in contour mining or in slot mining when surface access to a reserve is limited. A significant attribute of the highwall miner is its versatility. HWM has been used successfully to mine abandoned pre-reclamation law highwalls, points or ridges uneconomic to mine by underground or other surface methods, outcrop barriers left adjacent to underground mines, separate benches of the same seam where the parting thickness or quality differences between benches render complete extraction uneconomic, previously augered areas containing otherwise inaccessible additional reserves and close or widely spaced multiple seams. The theory and design methods to assess roof; pillar, and floor stability are presented followed by three case histories. Simple design charts for sizing HWM web and barrier pillars are also presented. A recommended web pillar width may be obtained from the design charts given the overburden depth, the HWM cut width, and the mining height. Given the depth and panel width for a set of HWM cuts, another set of charts gives a suggested barrier pillar width. The case histories, hm Northern and Southern Appalachia are used to illustrate the application of rock mechanics to quantify the stability of the highwall, roof, web pillars, and floor. The case histories involve 1) mining through a previously augered highwall, 2) mining under back-stacked spoil and 3) selective mining of closely spaced benches of the same seam. Because each site is unique, the appropriate pre-mining geotechnical analyses range from the calculation of roof, web pillar, and floor bearing capacity stability factors to detailed numerical modeling of the auger and underground mine workings. When operating in the vicinity of existing underground mine or auger workings, the determination of ground deformation and strains resulting from highwall mining is a necessary facet of a ground control investigation.

Jan 1, 2005

By Wilbur E. Sanders

At some period during the operation of metalliferous and other commercially valuable mineral-deposits in connection with their underground mining, when the developments therein have become so extensive that their description is tedious and confusing, some scheme for naming or numbering the various workings and their parts is necessary for convenience of reference. A simple and symmetrical yet expansive system of classification must be devised, one that is capable of being extended to cover all possible exigencies and conditions of future operations within the property. Such a scheme, properly arranged, greatly simplifies communication between the various departments of the mining business, as, for instance, between the administrative and the operating departments of the concern, and is of the greatest assistance to the officers of the mine in enabling them to locate and describe particular points and parts of workings and specific kinds of work. Again, in the proper segregation and differentiation of mine-accounts, when they are carried out with that detail which will furnish ready information concerning the cost of a particular piece of work, or the various items and totals of expense connected with the development, operation and repair of each or all of the mine-workings, some such method of clesignatioi~ becomes a necessity. Moreover, such a plan is acl- mirably adapted to the needs of the mining engineer, who, in connection with his reports upon mining-properties, is sometimes required, in his descriptions of certain blocks of ore, to locate lists of assays of samples taken from many and various places, and to designate workings and parts of workings that are located in different parts of the mine, sometimes at points wide apart. To write out in full a sufficient description of any particular

Jan 1, 1907

By Enrique Touceda

As in the case of steel and the non-ferrous alloys in general, the use of the microscope in connection with the manufacture of malleable cast iron has proved of inestimable value to the industry. Had its use not been invoked, many facts either would not be known at all or, if suspected, would be confined to the realms of conjecture. No fairer statement could be made than that the start of real progress in the industry was coincident with the application of metallography to the product, though the full significance of this statement can hardly be appreciated except by those who not only are conversant with conditions as they existed at the time referred to, but are familiar with the character of works' practice at the present time.. A few years ago, about the only test made to ascertain the physical properties of the product, except in the case of certain plants, was the bending of a casting to destruction, not only with the object of discovering whether or not the metal was ductile, but for the purpose of inspecting the fracture. The characteristics of the fracture, if correctly interpreted, were known to be of value in locating the trouble in castings that were inferior. In general, it was found that if a casting of medium or heavy section would bend through a wide angle before failure took place, the fracture in the majority of cases would have a black velvety appearance; while if it was held at different angles to the direction of the rays of light, it would show a change of color and an iridescent sheen. But an inferior air-furnace heat or anneal might yield castings which, if thin and consequently largely decarburized, could be bent double on themselves and still not possess the fracture described. If, on the other hand, a casting broke short, its fracture might have one of a great many different color and structural peculiarities. Depending on the cause of the trouble, such castings might have any of the fracture characteristics, of which the following is but a partial list.

Jan 1, 1922