Search Documents

By FREDERICK W. BRADLEY

MINING is one of the world's oldest industries and has pioneered the civilization of all new lands. Today, mining is not only one of the essential and basic industries of the world, but it is constantly growing in magnitude and becoming more important. We think that the most of our mining is done in the western portion of this country, but in the old State of Pennsylvania mines and products derived from minerals account for about two-thirds of the entire productive wealth of the State. As our forests are denuded, mining furnishes substitutes for timber in the way of concrete, gypsum board, etc. ; and as civilization increases the wants of mankind, mining is producing metals and minerals of every kind in increasing quantities. For example: during the past ten years the per capita consumption of copper in the United States has increased 49 per cent, to 14.56 Ib.; that of lead has increased 35 per cent, to 12.24 lb.; and that of zinc has increased 70 per cent, to 9.57 Ib. The consumption in European countries is about one-half of this, and there are other countries with large populations where there is virtually no consumption; so when all other countries catch up in consumption with our country, you can see what an enormous demand there is going to be for the metals, even to the extent of having to find substitutes for copper, lead, and zinc.

Jan 1, 1929

By AIME AIME

THE luncheon of the Milling Methods Committee in the Engineers' Club, on Feb. 16, was distinctly a social affair, although several matters of a non-milling nature were fruitfully discussed. The session* on Milling Methods, the same afternoon, attracted a gathering which overtaxed the capacity of the Board Room on the fifteenth floor. Galen H. Clevenger presided, with the moral reinforcement of Charles Butters. As all papers were available in printed form, and since synopses have appeared in MINING & METALLURGY, it is unnecessary to cover the contents of each in detail here. The first paper (T. P. 410), by Leaver and Woolf, on the "Flotation of Minor Gold in Large-scale Copper "Concentrators," was excellently summarized by R. S. Dean of the U. S. Bureau of Mines, who stressed the -very definite action of lime as a depressant of gold, and showed how the authors had worked out the best conditions of alkalinity, pH concentration and reagents for -optimum recovery of gold along with base metals, especially where lime had to be used to depress pyrite. No discussion was evoked.

Jan 1, 1931

By Owen F. Jensen

CONSTRUCTION of a ground-water supply includes many operations, which do not end with completion of facilities. Evaluations must be made of the quality of water in various areas and the history of production. Following an analysis of geologic, hydrologic, and chemical data there must be an exploratory drilling program and a study of resulting information. When the well is completed a continuous survey of operating records and basic data is necessary, since designs for future wells are varied as more data becomes available for those already completed. As the following discussion must be limited to a single undertaking, the customary procedure will be outlined for development and construction of a ground-water supply in which more than three wells are involved. Parts of this procedure are applicable for all ground-water supplies. Three possible sites were selected for construction of a paper mill. The problem was that the industry daily required approximately 15 million gallons of water of the best quality available; however, if water of the best quality were not available in the desired amount, water of a poorer quality could be used up to half the required amount, about 7 million gallons. In the preliminary survey approximately 1500 to 2000 square miles were covered for each site. Collected data consisted of several hundred electric logs of oil and gas wells; reports by the U. S. Geological Survey on ground-water resources of localities in and near the area; unpublished records of several hundred water wells including chemical analyses of the water produced and drillers' logs of the wells; records of periodic water-level measurements made in observation wells by the USGS; topographic maps drawn up by USGS and by army engineers; and highway and county road maps. A preliminary report based on study and evaluation of these data was presented to the client, recommending the site with the most favorable and economical ground-water conditions. The study indicated that water of the quality and quantity desired could be developed. In this particular area there were indications that the aquifer could be separated into two zones con- taining water of different chemical character. This chemical character varied somewhat with area, but principally with depth, a factor which later proved an economic advantage in design of the well field. After studying the preliminary report, the client weighed other economic factors as well as ground-water advantages and selected a plant site. Authority was given to proceed with detailed study of the chosen area. Evaluation of preliminary data concerning the area indicated that it should be supplemented with additional information derived from actual exploratory drilling and testing. A flexible plan of exploratory drilling was devised so that data obtained as each test hole was drilled could be correlated with existing data and additional test holes could be located and drilled accordingly. Specific data to be obtained from each test hole were: samples of all formations penetrated; the driller's descriptive log of formations; electric logging surveys; one or more samples of water from selected water-bearing formations; temperature; and water levels and their recovery after periods of production. The area studied in such detail was approximately 400 square miles. Choice of location for the original test holes was based on the preliminary study. The pattern for these test holes was designed to require a minimum number of holes and to allow for interpolation of data between two, three, and four holes. Geologic, hydrologic, and chemical data gathered after completion of the first four test holes showed that the north section was the most desirable in the area, which was then reduced from the original 400 square miles to about 150 square miles for more detailed and intensive study. On the basis of findings from the current test a tentative well field was laid out and a drilling program devised. One test hole was located on the actual plant site and later developed into a small pilot production well equipped with a deep well turbine pump. Water from this well was used for general construction requirements. Another test hole drilled near the pilot production well and adjacent to the proposed route of the well-collection system was used during the pumping test of the pilot production well to determine the degree of interference. From the data thus obtained, calculations were made to determine the coefficients of transmissibility and storage. Three additional holes

Jan 1, 1955

By D. B. Kibler

Pill Florida hard-rock field extends from Suwanee and Columbia Counties in northwest Florida to south of Croom, Florida, in Hernando County this area is approximately 100 miles long and varies from 2 to 30 miles 1n width Florida hard-rock phosphate was discovered at Hale Springs, about one mile northwest of the town of Dunnellon Marion County, in the year 1888, by Albertus Voight who lived within a few hundred yards of the spring Soon after this discovery there was a great influx of land speculators and wildcat operators into the vicinity of Dunnellon A few years later phosphate was found in Alachua, Levy, Citrus and Hernando Counties, and a great number of small crude plants were built from Newberry, Alachua County, all the way to Croom, Hernando County Phosphate was found in many places as "outcrops " Looking for outcrops was the first method used by the early prospectors in searching for deposits Several years passed before any systematic method of prospecting was used EARLY MINING The early method of mining hard-rock phosphate was with picks and shovels, wheelbarrows, mules and wagons The pick-and-shovel method was used altogether until about 1900, when some of the larger operators began to use railroad-type steam shovels of from 1/2 to 1-yd capacity Picks and shovels, with negro labor loading the phosphate ore (called "matrix") into wooden side-dump skip-cars, was continued until about 1907 From the discovery of hard-rock phosphate until approximately 1905, overburden was removed with mules and scrapers At some places, the overburden was loaded into side-du nip skip-cars by negro laborers and the cars were then pulled up an incline with a steam hoisting engine The maximum depth of overburden that could be economically removed by hand labor mules and scrapers was approximately 15 feet About 1905 one of the companies erected a producer-gas powerhouse near Dunnellon and generated its own electricity and about the same time the larger companies began using hydraulic methods for the removal of overburden From the year 1888 through the year 1939, approximately 75 companies were operating at one time or another in the hard-rock territory, on approximately 500 locations The hard-rock deposits are more irregular and have higher mining costs than the pebble-rock deposits, therefore they have not been competitive in the domestic market, but because of the higher grade of the hard rock it is in demand for the export trade Discovery of phosphate outside of the United States has made it increasingly difficult in recent years for the hard-rock companies to survive, so today only three companies are operating These

Jan 1, 1941

By Marlin J. Veesaert

Urban quarries offer one of the greatest opportunities for profit in nonmetallic mining with limited financial risk-if properly evaluated, planned and developed to meet market needs. Location, with respect to market, is the prime consideration. Geologic considerations and quality of rock are nearly as important. Cost factors and return on investment (ROI) are the principal financial considerations. Risk of capital is determined by weighing all factors that should be considered and how well judgments are based on information acquired. It is a simple, true axiom of business that an investment must be founded on amount of capital required with its expected return plus profit, expertise required to operate, and time involved. Urban quarries generally offer excellent stone product market opportunities. Costs of land with mineral containment and processing operations are much greater than in rural areas. Environmental problems have become increasingly severe. Competition from other quarries in the market area is usually directly proportional to the profit attractiveness. Risk of capital (initial, developmental and operational) can be evaluated and reduced only by thorough analysis of the entire situation. Time and money expended on planning and preliminary investigations probably represent the most productive investment of available company resources. Basic Reasons to Establish a Limestone Quarry Profit Motive: Certainly the dominant and overriding motive must be that of attaining a reasonable profit. In certain situations a quarry firm may acquire land, necessary rezoning (if required), and satisfy all of the other prerequisites preparatory to beginning operations but delaying the actual development.

Jan 1, 1980

By H. Kreye, E. Hornbogen

An increase in electrical resistivity during aging or after quenching from high temperatures is known in a large number of alloys. Plastic deformation of alloys in this condition leads to a decrease in resistivity. This anomaly has been called the K effect. This effect has been reported in Ni-A1 alloys by several authors.'-4 The nickel-rich solid solution y is in equilibrium with Ni,A1 (y') with CkAu structure. With this alloy it is therefore possible to produce a homogeneous solid solution as well as a coherent mixture of y and y. The changes in resistivity should be determined for these two conditions. In the present literature on the K effect no distinction is made between them, because of experimental difficulties to determine small coherent particles. In the present work transmission electron microscopy and image formation by (100) and (110) superlattice reflection of the y' phase was employed for a detailed determination of the temperature dependence of solubility of aluminum in nickel and the resulting microstructures with alloys up to 15 at. pct Al. The solubility line follows the equation indicating a smaller solubility than given in the literature at temperatures below 700°C. X-ray scattering was used to get evidence for short-range ordering in the homogeneous solid solutions.5 Parallel to the determination of the microstructure electrical resistivity was measured as a function of aging tempera- ture, time, and aluminum content, which led to the following results: 1) Resistivity increases slightly during aging of a homogeneous solid solution which was quenched from a high temperature as a consequence of short-range order, Fig. 1, curve c,. 2) Resistivity shows a maximum during aging of all alloys which are heterogeneous according to the phase diagram, but which were obtained as a supersaturated solid solution by quenching, Fig. 1, curve c,. The increase in resistivity is mainly due to coherent precipitation of y'. In Fig. 2 the effects due to short-range order pN and due to precipitation of particles APT are shown for an aging temperature of 450°C and different aluminum contents. 3) The increase in resistivity depends on the size !f the coherent particles. A critical diameter of 15 5A for the maximum was found for all alloys and aging treatments by extrapolating particle sizes determined by electron microscopy. 4) The maximum of resistivity of the heterogeneous conditions does not occur if particles, larger than the critical size, have formed already during quenching. 5) Plastic deformation destroys short-range order as well as small coherent particles. Therefore a decrease in resistivity is observed if the increase in resistivity caused originally by these phenomena is

Jan 1, 1967

By HILLARY W.

THAT colleges and technical schools constitute a vital factor in our industrial system is being realized more and more of late years. Consequently it is desirable that there should be a constant interchange of ideas between the 'school and the industries and that there should be a more intimate contact between the student and his future employer. Business and industry demand certain proficiencies and qualifications of the student and he, in turn, sees certain rewards and advantages in the industry. . In a meeting of this kind, whose primary purpose is to promote a greater intimacy between the students and those men who are active in the mining profession, it is quite fitting that each state his demnds upon the other in order to establish a common understanding. It is probable that a student, not being conversant with actual conditions in the industry, may be unfair in what he asks of his employer. Therefore criticism, constructive or other- wise, is not only accepted, but is invited.

Jan 1, 1930

By Albert R. Ledoux

Discussion of the Paper of Albert R. Ledoux, read at the Atlantic City Meeting, February, 1904. ARTHUR JARMAN, Sydney, New South Wales, Australia' (communication to the Secretary*): Some remarks upon. Dr. Ledoux's interesting paper from one who has not visited America may, I hope, be of interest to members. It appears to me that there is considerable difference between the training of the American and of the British mining engineer. Not that the subjects are different, but rather in the way in which they are handled, the illustrations being, as far as possible, mining in character. Colloquial instruction is unknown in English curricula, but could be introduced with advantage. Students here assure me that an hour of conversation is of tar more use to them than an hour of the best lecturing. In England a school-year of 6 or 7 months would be considered very short indeed; but Americans do not consider it so, for the reason that the rest of the year is mostly spent in acquiring practical acquaintance with their subjects in works or in the field, and the shorter courses, when coupled with this large amount of outside expe¬rience, produce an essentially practical-minded engineer, who is also more of a business man; whereas the English system, though excellent from a scholastic point of view, produces the theoretical rather than the practical man. British schools are waking up, however, and the practical aspect of the engineer's training is receiving greater consideration. Once launched upon his career, the American engineer is immediately called upon to exercise his self-reliance and ingenuity, if he is to retain the confidence of his employers; but what can we say of English directors? In how many cases is the engineer allowed to guide the destinies of his company? Witness several recent cases of gross waste of money upon unsuitable plants, and the perpetuation of prehistoric methods of

Mar 1, 1905

By F. N. Rhines, B. H. Alexander

MUCH attention has been directed to the effects of grain size upon the properties of alloys, but there has been scant study either of the conditions that determine the pattern and dimensions of den-drites in metal systems, or of the influence of their shape and size upon the overall properties of cast-ings. The aim of the research that is about to be described has been to investigate the effect of vari-ous factors upon the mode of formation of dendrites in alloys by measurements of the distance between adjacent dendrite arms (dendrite spacing). Early investigators, including Grignonl and Tschernoff,2 showed that a metal dendrite is com-posed of a tree-like system of stalks and branches arranged in a simple geometrical pattern. North-cott and Thomas3 demonstrated that, in the face-centered cubic solid solutions of copper-base, these stalks and side arms all lie in (100) directions in the crystal. Several investigators, including Sauveur and Chou,0 Sauveur and Reed,' and Martin and Mar-tina have reported that the addition to steel of alloy-ing elements, such as nickel, chromium, and molybdenum, not only makes the dendrites easier to reveal by etching, but makes them coarser. The latter authors8 proposed that the coarsening of the dendrites is roughly proportional to the increase in the temperature range of freezing, caused by adding the alloying elements. Sauveur and Chou6 showed, in addition, that the dendrites are coarsened by a decreased rate of cooling of the casting. Measurement of Dendrite Arm Spacing Among the physical conditions that could be ex-pected to have an influence upon the dendrite arm spacing, that appears in a cast metal, are: composi-tion, rate of freezing, crystal structure, and type of constitution. The relationships obtaining between these variables and the dendrite dimensions have been examined, in the present research, by measur- ing the arm spacing in a wide variety of alloys, listed in tables II through VI. Alloy compositions are recorded in the tables by showing the symbol of the major metal followed by the percentage and symbol of the alloying agent; thus, "Al-10Ag" is an aluminum-base alloy containing 10 pct of silver. Although none of the alloys were analyzed, an im-pression of their degree of purity may be obtained from that of their component metals given in table I. Five hundred grams of each alloy was made by melting in small clay-graphite crucibles in an elec-tric muffle furnace. After alloying the temperature was adjusted to 50" to 75°C above the liquidus and the melts were poured into cast iron molds, at room temperature, the molds having a wall thickness of 1 in. and a cavity 11/2 in. sq in cross-section. Each ingot, thus cast, was sectioned at mid-height and the sectioned surface was polished and etched for metallographic examination. Dendrite spacing meas-urements were made at three positions, namely, ad-jacent to the mold wall, midway between the wall and the center of the ingot, and at the center (desig-nated e, m, and c respectively, in the tables). A typical series of microstructures is presented in fig. 1. For each measurement, the average was taken of the dendrite spacing of several grains covering a zone about 2 mm wide. Only those grains which had a major dendrite axis nearly in the plane of polish were selected in order to eliminate corrections for orientation differences from grain to grain. Although the dendrite spacings were measured to the nearest thousandth of a millimeter, the values listed in the tables are thought to be significant only to the nearest hundredth of a millimeter. The larg-est difference in readings found, when various ob-servers rated the same specimens, was 0.012 mm; the largest difference between corresponding meas-urements upon duplicate specimens was 0.027 mm.

Jan 1, 1951

By Robert J. Linney

IN the latter part of the year 1943, it was decided to experiment with diamond-drill blast holes in the Old Bed magnetite mine at the Mineville mines of the Republic Steel Corporation, in sections of the ore body where vertical dimensions were large and where development for sublevel bench stopes had already been done. Other possibilities of application for this drilling method were in the reclamation of old floors and pillars in the pitching folds of the Lower Old Bed ore body and in the reclamation of large vertical pillars in the " 21 " Bonanza-Joker ore body. The cross sections and views of the two ore bodies will show the conditions to which the diamond-drill method has been applied. The Lower Old Bed magnetite ore body is lenticular and dips approximately 30° toward the southwest and strikes generally southeast and northwest. An intensely folded structure, which pitches generally on an axis approximately at right angles to the strike, is continuous from the uppermost old workings down to the present bottom of the mine, and probably continues with depth. On successively lower levels this folded structure becomes greater in vertical dimensions and the two folds are closer together in a horizontal dimension. As shown in Fig. 1, this folded structure gives to parts of the ore body considerable vertical dimensions, which provide areas that were developed for sublevel bench stoping above a slushing drift, as shown in Fig. 2. It was in one of these previously developed sublevel bench stopes, No. 26 on the 1185-ft. level, that the diamond-drill blast-hole method was applied for mining the upper sublevel. The lower sublevel was underhand-bench-drilled to the finger raises of the scram drift below. The roof of this stoping area began to break and spall on the lower sublevel, causing the roof to become inclined. Along the hanging wall of the stope this reached an elevation about half way between the two sublevels. A smooth schistose seam in the hanging wall causes the ore to break away freely. Therefore, if bench mining had been carried on in the upper sublevel, a dangerous condition of poorly supported benches would have resulted. When the drillers were slashing across the sublevel to footwall and hanging wall to make a bench, spalling roof of the opening below would probably have carried away part of the bench, and would have left a dangerous place in which to continue underhand benching. A 6 by 8-ft. raise had been driven between the lower stope and the upper sublevel about 200 ft. from a manway. It was decided to use this raise for a starting cut and to arrange holes as shown in Fig. 3, so that a slot would be opened across the ore body between the footwall and hanging wall. This slot would then be used for the purpose of breaking into the ore; by blasting vertical rings of holes drilled at right angles to the axis of the pitching folds as nearly as possible. Layouts of this slot drilling and the rings adjacent are

Jan 1, 1945

By C. C. Herrick

The vapor pressure of indium has been measured by the torque-effusion technique, as a function of temperature between 1102o and 1422oK. For liquid indium, the vapor pressure (in atmospheres) can be represented by the equation -R In P = 5.782 x104/T - 25.29from 1000o to 1422oK. Extrapolation yields a calculated normal boiling point of 2329°K and a heat of vaporization at 298 oK of 58.09 kcal per mole by the third-law method and of 58.39 kcal per mole by the second-law method. Calculations indicate that the free-energy functions of Hultgren are to be preferred to those of Guruich. BECAUSE of the potential uses of liquid metals, it is important that convenient experimental methods be developed which will lead to a sufficient body of thermodynamic data so that reasonable estimates of properties of liquid metals can be made. Indium is particularly well-suited to investigation, since it remains liquid over a long temperature interval, it alloys readily, suitable containers for it are easily procured, and relatively few investigations of its thermodynamic properties in the region above 1000°K have been made. PREVIOUS RESEARCH The first determination of the vapor pressure of indium was made by Anderson,' using the Knudsen method and silica-lines stainless-steel cells. Kohlmeyer and spandau2 determined the normal boiling point, and a mass-spectroscopic investigation has been made by Lyubimov and Lyubitov.3 (Unfortunately, only an equation representing the data of the latter investigators has been available to us.) Hultgren et al.4 and Gurvich5 have published discordant tables of the free-energy functions for indium. EXPERIMENTAL METHOD The torsion-effusion principle has been described amply in the literature.8,7 With this method, one observes the angular deflection induced by effusion of vapor from a multihole effusion cell which is suspended from a filament producing a small rotational restoring force. The pressure within the effusion cell can be computed from the relation ziaifiai where k is the torsion constant of the filament, 6 is the observed angular deflection, and ai, fi, and qi are the area, force factor, and moment arm of the ith effusion orifice. The force factor f is analogous to the Clausing factor,' and corrects for the reduction in effusive force attributable to the finite geometry of the effusion orifice. Schultz and Searcy' have tabulated the force factors for various tube geometries. EXPERIMENTAL APPARATUS The physical arrangement employed in this study is shown in Fig. 1. The furnace elements are six Globar heat rods with 15-in. hot zones. Temperature is maintained to * 1°K by a Beck mechanism driving two 26-amp Powerstats in parallel. A Pt (Pt, Rh 10 pct) thermocouple serves as the sensing element. Four inner tubes act as vibration isolators; the air pressure required for maximum isolation was determined empirically, and is maintained by a solenoid valve. The tungsten fiber, 9 by 0.002 in., is joined to an 0.008-in. tungsten wire or graphite rod via a machined lightweight chuck.

Jan 1, 1964

By Robert J. Linney

In the latter part of the year 1943, it was decided to experiment with diamond-drill blast holes in the Old Bed magnetite mine at the Mineville mines of the Republic Steel Corporation, in sections of the ore body where vertical dimensions were large and where development for sublevel bench stopes had already been done. Other possibilities of application for this drilling method were in the reclamation of old floors and pillars in the pitching folds of the Lower Old Bed ore body and in the reclamation of large vertical pillars in the "21" Bonanza-Joker ore body. The cross sections and views of the two ore bodies will show the conditions to which the diamond-drill method has been applied. The Lower Old Bed magnetite ore body is lenticular and dips approximately 30° toward the southwest and strikes generally southeast and northwest. An intensely folded structure, which pitches generally on an axis approximately at right angles to the strike, is continuous from the uppermost old workings down to the present bottom of the mine, and probably continues with depth. On successively lower levels this folded structure becomes greater in vertical dimensions and the two folds are closer together in a horizontal dimension. As shown in Fig. I, this folded structure gives to parts of the ore body considerable vertical dimensions, which provide areas that were developed for sublevel bench stoping above a slushing drift, as shown in Fig. 2. It was in one of these previously devel-oped sublevel bench stopes, No. 26 on the 1185-ft. level, that the diamond-drill blast-hole method was applied for mining the upper sublevel. The lower sublevel was underhand-bench-drilled to the finger raises of the scram drift below. The roof of this stoping area began to break and spall on the lower sublevel, causing the roof to become inclined. Along the hanging wall of the stope this reached an elevation about half way between the two sublevels. A smooth schistose seam in the hanging wall causes the ore to break away freely. Therefore, if bench mining had been carried on in the upper sublevel, a dangerous condition of poorly supported benches would have resulted. When the drillers were slashing across the sublevel te footwall and hanging wall to make a bench, spdlling roof of the opening below would probably have carried away part of the bench, and would have left a dangerous place in which to continue underhand benching. A 6 by 8-ft. raise had been driven between the lower stope and the upper sublevel about 200 ft. from a manway. It was decided to use this raise for a starting cut and to arrange holes as shown in Fig 3, so that a slot would be opened across the ore body between the footwall and hanging wall. This slot would then be used for the purpose of breaking into the ore, by blasting vertical rings of holes drilled at right angles to the axis of the pitching folds as nearly as possible. Layouts of this slot drilling and the rings adjacent are

Jan 1, 1946

By R. B. Walker, R. Palmer, L. C. Bryner

The purpose of this investigation was to further study some of the factors affecting the air oxidation of sulfide minerals. Data obtained from laboratory studies on the effect of temperature, concentration of iron salts, pH, and other catalysts on the biological and nonbiological oxidation of sulfide minerals are presented. The oxidation of copper sulfide minerals and subsequent leaching of the soluble copper has long been a profitable operation. The chief oxidizing agent is oxygen from the air. This reaction is influenced by a number of different factors such as temperature, light, hydrogen ion concentration, oxidizing agents, and various catalysts. Sullivan1 found that copper sulfide minerals are slowly oxidized by the air and that dilute sulfuric acid and iron (111) increased their solubility. At that time it was not known that bacteria were involved in the oxidation of the sulfide minerals. It has been shown that pyrite, molybdenite, free sulfur, and the copper sulfide minerals found in the waste rock dumps in Bingham Canyon, Utah, are largely oxidized by chemosynthetic autotrophic microorganisms found in the leaching streams.2-6 Similar organisms have been isolated in other mining areas7,8 and from the effluents from coal rnines.9 The following are some of the questions that have arisen regarding the mechanisms of the reactions involved in the leaching process. How dependent is the leaching operation upon the biological reactions? How does the temperature effect the biological and non-biological reactions? How does the concentration of iron (II) and (111) effect the rate of oxidation of copper (II) sulfide? Does the iron act as a catalyst? Does activated carbon act as a catalyst on the oxidation of sulfide minerals? What effect does the hydrogen ion concentration (pH) have on the above reactions? The purpose of this paper is to report the results of laboratory studies on these problems. EXPERIMENTAL The apparatus used in this investigation was an air lift percolator described in our earlier work.' The percolator consisted essentially of an air lift which enabled the leaching solution and microorganisms to pass freely through a suspension of mineral (substrate) in Ottawa sand. The air lift served the additional purpose of maintaining an ample concentration of oxygen and carbon dioxide in the nutrient (leaching) solution. (See Fig. 1.) The percolators were so constructed that they could be immersed in liquid constant temperature baths for temperature studies. The thermostats were controlled to +0.5°C. The reactions were all run in the dark. The percolators were charged with one to three g of mineral, dispersed in 100 g of Ottawa sand and 100 ml of nutrient or leaching solution. The sand was purified to remove traces of iron by digesting with concentrated hydrochloric acid and washng with distilled water until free from chloride. After drying, the sand was ready for use. The compressed air supply was regulated to 5 psi and bubbled through an aerator containing distilled water, which was maintained at the same temperature as the bath used. The air was filtered through cotton plugs to maintain sterile conditions. The tops of the

Jan 1, 1968

By Robert S. Dewey

More wells were drilled in West Texas† during 1944 than in any year since 1941. As compared with 1943, there was an 82.5 per cent increase in the total number of completed wells. The 1646 wells required an estimated 140,715 days to complete for a total of 7,632,249 ft. An average of 85 completion days was required to drill to an average of 4630 ft. This depth is approximately 100 ft. greater than that of the previous year. It is estimated that $100,000,000 was invested in drilled wells. As of Dec. 31, 1944, there were 270 field and 91 wildcat wells being drilled. While an identical number of wells were drilling Dec. 31, 1943, the proportion of wildcats increased in 1944 from 19.7 to 25.2 per cent. During 1944, oil wells were completed in 103 of the 164 fields in West Texas. Of the 1361 oil wells, 385 were in Slaughter, 116 in Fullerton, 63 in North Cowden, 62 in Fuhrman-Mascho, 59 in Wasson, 52 in Westbrook and 47 in North Ward. Approximately 22 per cent of the wildcat drilling was to pre-Permian formations. Despite the increasing proportion of wildcat wells drilled, the wildcat discovery rate has declined since the year 1942. AS compared with 1943, the number of wildcat wells drilled increased from 11.7 to 12.7 per cent and the footage in wildcat exploration increased from 13.3 to 13.8 per cent of the total. The monthly production of crude continued to increase to a peak of 15,336,000 bbl. in October 1944. As compared with a similar peak production in October 1943, there was a 37.3 per cent increase. The yearly production increased from 98,165,-ooo bbl. in 1943 to 159,943,000 bbl. in 1944, an increase of 62.8 per cent. Based upon an assumed average price of $1.00 per barrel and less 1/8 royalty, the gross return to the producer amounts to $140, 000,000. From 1943 to 1944, the average number of producing wells increased 6 per cent while the average daily production per well increased 53.1 per cent. The average daily production per well increased from 17.5 bbl. in 1943 to 26.8 bbl. in 1944. The proportion of flowing wells decreased from 50.5 per cent in January to 49.1 per cent in December 1944. Drilling With the continued shortage of labor and materials, drilling costs have risen sharply. Just how much is difficult to ascertain. Owing to competition for available drilling rigs, contractors are reluctant to assume drilling risks. In consequence, some contracts are let on a cost plus basis, or day work below some specified depth with the operator furnishing part of the consumable materials, such as mud and drilling bits. Contractors are having difficulty in maintaining full and effective drilling crews with insufficient and inexperienced labor. Service companies have inadequate labor and equipment to meet their appointments promptly. Pipe Lines The Gulf Pipe Line Co. increased the capacity of its 10-in. main line by filling in gaps amounting to 75 miles on the loops between Judkins and Weatherford, Texas.

Jan 1, 1945

By Edwin Ludlow

I DEEPLY appreciate the honor which has been conferred upon me by my election to the presidency of this Institute, as I feel that it is the highest honor a mining engineer can receive, and I also feel that I am especially fortunate in being called to take the presidency in the year following Mr. Hoover, as I may be enabled in that way to carry on the work which he has initiated. The constructive work that Mr. Hoover has inaugurated has been of inestimable benefit in bringing not only this Institute but the entire engineering profession into a place in the public esteem to a degree which it had never before occupied.. This work Mr. Hoover will now carry on in the broader field of the Federated American Engineering Societies, of which he is president. Through that organization the engineers of this country, in all branches of the profession, will be welded into one compact body reaching from the Atlantic to the Pacific, making the united engineering profession a power for maintaining American . . ideals and standards throughout the land.,

Jan 1, 1921

J. T. LITTLETON, JR., ? Corning, N. Y. (written discussion?).-This. discussion will add little that has not been brought out but will show how the problems encountered in the Corning Glass Works were overcome. The chief points of consideration in any equipment are, first, the work the equipment is called upon to do; second, the installation; and, third, the man who will use it. These three points should determine the type of apparatus adopted. If only rough measurements, merely a little better than the eye, are desired, the cost of the instruments should be considered; but if accurate temperature control is necessary, the cost of the equipment deserves only small consideration. There is no question that the real problem for any factory is the installation, making sure that the elements really give the temperatures desired; also, the instruments must be so designed that any man can use them.

Jan 12, 1919

By W. L. Batt

MODERN war means mechanization, and mechanization means raw materials, especially minerals-and lots of them. Let me recall a few events of recent history-events that constitute mile- stones down the road to the war now blazing on three continents and threatening to spread still farther. In 1932, Japan took Manchuria, largely upon the excuse that she needed raw materials; in 1935, Italy invaded Ethiopia, largely upon the excuse that Mussolini's growing nation needed raw materials-in this case oil; from 1933 to 1935, Germany cried out for a greater share of the world's natural wealth, and since 1938 has invaded or occupied ten other countries, frequently upon the excuse that she needed-and had a right to-more raw materials.

Jan 1, 1940

By J. A. Botin, K. H. Singh

INTRODUCTION The Alfredo underground mine is one of the three mining operations of Rio Tinto Minera, S.A., all near the community of Rio Tinto in Huelva province of southwest Spain. The other two operations are Corta Atalaya open pit (Pyrite ore) and Cerro Colorado open pit (Copper ore 1. Underground mining of Alfredo Mine for pyrites started in the nineteenth century and continued without interruption until 1979 when it was discontinued due to economical reasons. In 1972, a new project was started for the mining of copper bearing ores on the footwall of the pyrite deposit. This copper ore is locally named “Cloritas” and it forms a nearly vertical and tabular shaped orebody which forms an envelope at the footwall of the San Dionisio pyrite orebody. Mining of the Cloritas commenced in 1975 using cut and fill stoping. In 1977, the original project was completely revised which led to the introduction of a bulk mining system to achieve a planned production of 3,000 tonnes of ore per day. This paper covers the economic and planning aspects of the mine and discusses the evolution of the mining method for the Cloritas orebody. A GENERAL DESCRIPTION OF THE CLORITAS OREBODY The “Masa San Dionisio” (figure 1 ) is a massive sulphide orebody located in the town of Rio Tinto, about 90 kilometres west of Sevilla, Spain. Extensive vein-type sulphide mineralization exists in the volcanic host rocks of the Masa San Dionisio. Within this area of stockwork veins, there is a higher concentration of copper in the form of chalcopyrite in a zone adjacent to and paralleling the contact with the massive sulphides. This copper envelope is locally referred to as the "Cloritas Orebody” and the ore within it is called "Cloritas”. The main zone of the Cloritas orebody, (figure 11, is tabular and nearly vertical having a length of 375-400 m east-west, a thickness of 20-50 m north-south, and a vertical extension of 500 m from the surface. In addition to this area, there is a second less important low grade area called zone 2A located to the north of the main zone below 26 Level which, in some sections, is not fully separated from the main zone. MINING METHODS Mining in Rio Tinto area can be traced back to the Phoenecians and the Romans. Modern day mining started with the demand for sulphuric acid during the last half of the nineteenth century. By 1971, more than 33 million tonnes of pyrite had been mined out of Alfredo Mine, (San Dionisio Orebody), using labor intensive drift and fill methods and also by open pit method. During the last decade, underground mining of the pyrite had become uneconomic due to lower prices and a slackening demand for pyrite, and the underground mining operations for pyrite were finally stopped in 1979. In 1971, a major change in the long range mining plans for Masa San Dionisio was established. Between 1971 and 1975, underground mining of pyrites was progressively reduced while open pit extraction was increased in

Jan 1, 1981

R. W. Raymond, New Pork, N. Y.:—I think Mr. Bache has put his finger on the chief source of the danger of dust-, or gas-and-dust, explosions in collieries. 1 mean the persistent determination of the miners' unions to increase their weekly wages by the excessive use of explosives. This would not be feasible if coal-miners were paid by the day; but this form of payment is, for many reasons, not economically practicable; and the universal practice is to pay for the winning of coal according to the quantity produced. If the miner, by using a large amount of powder, can throw down a large amount of coal without corresponding labor on his own part in undercutting and drilling, he will receive more money for less work, provided he is paid for everything—merchantable coal, worth-less dust, slate, and " bone "—resulting from such a method. My attention was called to this matter many years ago by an admirable report of Prof. W. B. Potter, a past- President of the Institute, on the conditions obtaining in this respect in the Illinois coal-field. It was made very clear in that report that considerations of danger to workmen or loyalty to employers could not be relied upon to prevent miners from employing this perilous and wasteful method of increasing their own immediate receipts. So far as I know, only three remedies have been attempted, namely: the enforcement of discipline as to the methods of mining; the refusal to pay for dust, etc., produced by the miners'methods; and restriction upon the use of explosives, effected by requiring the miner to purchase them from the employer, at a price so high as to make it unprofitable for him to use them in excess. All of these attempted remedies have encountered the bitter opposition of the miners' unions. The enforcement of discipline has become almost impossible, if discipline be (as it should be) understood to involve punishment for the violation of rules when no disaster has followed. I

Jan 1, 1910

By W. L. Zeigler

THE year 1930 in the Ceur d? Alene district was one of curtailment in production. Many of the small properties were closed entirely and only three large. producers, the Bunker Hill & Sullivan, Hecla, and the Morning mines were left producing at capacity. No innovations in milling were evident, but progress was made in reducing costs as is always necessary in times of low metal prices. One new concentrator was constructed, a 500-ton daily capacity selective flotation plant for, the Jack Waite Mining Co. This mill uses coarse crushing, followed by hand sorting, for both a high-grade ship- ping ore and waste. The remainder of the ore leaving the sorting belt is crushed in a new type Traylor reduction crusher to %-in. size and stored in large capacity mill ore-bins. The grinding is done with ball mills, in closed circuit with a Dorr classifier to 75 per cent - 200 mesh. Minerals Separation 24-in. flotation machines are used both for a lead and a zinc concentrate, with double cleaning in each case. The concentrates are dewatered in Dorr thickeners and filtered on Oliver late-type filters.

Jan 1, 1931