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By J. T. Hayward

Studies of the forces and conditions governing the recovery of petroleum from natural reservoirs indicate that a low gas-oil ratio increases ultimate recovery, retards the encroachment of water and tends to reduce lifting costs. Methods for controlling and reducing gas-oil ratios in producing wells consequently have been given considerable attention during the past few years. However, during this same period, the production from wells in nearly all fields has been fixed by proration agreements and it is the opinion of the writer that where a well is required to produce steadily at a predetermined rate, less than its "potential" or maximum capacity, the gas-oil ratio will depend only upon the rate of production, and will be independent of the method of production and of the design of equipment in the well. If no change in the rate of production is contemplated, efforts directed to improving the gas-oil ratio by altering the diameter of the flow string, changing the position of the choke, assisting the flow with gas-lift or pump, etc., will be unsuccessful. This viewpoint is not new. It was presented by H. N. Marsh and B. H. Robinson in 1929,' but it has not been generally accepted. Although engineers believe that the rate of withdrawal and not the equip ment used governs the water-oil ratio, a similar opinion regarding the gas-oil ratio is not so commonly admitted. The rates of flow of oil and gas into the base of an oil well depend upon the following conditions: 1. The characterist-ics of the oil and gas. 2. The characteristics of the underground reservoir. 3. Temperature and pressure conditions in the reservoir. 4. The back-pressure held against the face of the sand. In operating a well, the only one of these conditions over which control may be exercised through operating procedure and the use of equipment above the sand is the back-pressure at the face of the sand. Strictly speaking, the back-pressure varies over the face of the sand, owing

Jan 1, 1932

By Robert A. Cook

Among the new devices for cheapening the cost of material entering into the manufacture of iron is the mechanical drawing of coke, by which the coke from bee-hive ovens is extracted with a minimum of manual labor. About twenty years ago, an ordinary plate-conveyer was put in use at the plant of bee-hive coke-ovens owned by the firm of Bell Bros. & Co., near Middlesboro, England. This conveyer ran close along the front of the ovens, and carried the coke to the cars. The ovens were drawn by hand, and a very great saving in cost was secured, as one man could draw and clean out twice as many ovens after the conveyer was put in use—he having no forking to do, and the coke being carried away as fast as it was drawn to the mouth of the oven. The next step was further to eliminate hand-labor as far as possible; and Mr. Thomas Smith of the Thorncliffe Iron Works, near Sheffield, patented in 1891 the machine for drawing coke which I here describe. This machine, the outcome of several years of experimenting, has now been in successful use since 1891, and there are between twenty and thirty of them in operation at present, and others building. The machine, as may be seen from Figs. 1 and 2, consists of a wedge-shaped shovel of proper width and thickness, connected with a steel rack of sufficient length to reach the back of the oven. The rack is supported by rolls, and guided by a device operated by a hand-wheel, which directs the shovel in the oven. The rack is driven by a pinion on a vertical shaft carrying a bevel-gear on the upper end. This bevel-gear is driven by another on the engine-shaft. The engine is single-cylinder, with reversible gear; and engine and machine are mounted on a truck, which is propelled

Jan 1, 1897

By Emory Kemler

The problem of determining the most desirable operating conditions of an oil-well pumping unit, the selection of the proper material and size of sucker rods, and the design of the pumping unit, requires that the sucker-rod loads be known with a reasonable degree of accuracy. In production practice, it is also desirable to know the effects of operating speeds and strokes on a plunger motion, as well as on the rod loads. For a particular well, data on rod loads can be obtained by measuring the load in sucker rods with a dynamometer. This method is not satisfactory because it does not permit the various factors to be investigated independently. It is also impossible to measure the plunger motion simultancously with rod motion under operating conditions. The mathematical solution is impractical because of the simplifications that have to be made to get a solution and the tremendous amount of numerical work that is necessary after such a simplified solution has been attained. This paper shows how analogies and models can be applied to the solution of these problems. The loads set up in a sucker-rod string during the ordinary pumping cycle are made up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rod friction, stuffing-box friction, plunger friction, friction of the oil in the tubing and rods, arid friction loss through the valves. The problem of determining the sucker-rod load is further complicated by the fact that the long oil column and the sucker-rod column act as springs, which affect the transmission of the polished-rod motion. A further complication is the fact that the motion cannot be transmitted at a speed greater than that of the velocity of sound in the material, and this means that there will be a time lag in the transmission in the motion, as well as a modification of its magnitude and a phase displacement.

Jan 1, 1936

By John C. Calhoun, Raymond G. Loper

Theoretical calculations for the decline of pressure and the variation of instantaneous producing gas-oil ratio with increased cumulative production have been made for reservoir systems under various producing drawdown values and for various spacings. These variables have been included by a modification of previously Published techniques. This consists essentially of utilizing a radial system flowing gas and oil in a succession of steady state calculations. The results of the calculations do not show any variation in the predicted behavior of the internal gas drive reservoir when either the drawdown or the spacing are changed. The prediction of performance on an internal gas drive reservoir has been presented by various authors. ',"' These predictions are in the form of a pressure decline and an instantaneous producing gas-oil ratio as a function of cumulative oil withdrawal. In making these predictions a basic assumption has been that the saturation of the reservoir is uniform throughout at any time, or that the pressure differential imposed on the reservoir system is zero. Because of these assumptions the validity of such predictions has been questioned. Their application to actual systems, where saturations are not uniform and where producing differentials exist, has been a hazardous procedure. The authors cited have used different methods of approach to the derivation of equations for making their predictions and for arriving at a solution of both equations, but basically the same relationships are utilized in each case. In all instances the instantaneous producing gas-oil ratio is calculated from the equation: In utilizing this equation an average reservoir pressure and an average reservoir saturation must be known, the former to define ß, v, s, and uo/ug and the latter to define kg/ko. Predictions can be made, therefore, only for the conditions of a uniform reservoir saturation and a uniform reservoir pressure. This restriction of requiring a uniform oil saturation can be resolved by applying two-phase steady state flow for the radial system to the reservoir's history. Radial steady state flow is defined when the ratio of phases flowing,

Jan 1, 1949

By S. R. B. Cooke, H. S. Choi, I. Iwasaki

In magnetic taconite of the East Mesabi range, quartz, magnetite, and cummingtonite (OH}(Fe, Mg)(Si4O11)2) are the three major ore-forming minerals.' Fine grinding and magnetic separation of the taconite leads to a concentrate analyzing 64 to 65 pct Fe and 8 to 9 pct insoluble; the gangue content of the concentrate arising from the presence of locked magnetite-gangue particles, and of occluded gangue particles in magnetic floccules. To further upgrade such taconite concentrates, flotation appears to offer a particularly promising approach. To evaluate its effectiveness in separation, a knowledge of the flotation characteristics of each mineral comprising the concentrate becomes desirable. The floatability of magnetite and of quartz have already been reported in a previous paper,2 in which the flotation characteristics of the two minerals were correlated with the electrokinetic properties at the mineral-solution interfaces. Since cummingtonite has somewhat intermediate chemical composition between the above-named oxides, the electrokinetic and the flotation behavior of this mineral becomes of interest for both practical and fundamental reasons. In the present article the results of electrophoretic mobility measurements and of Hallimond tube flotation tests on cummingtonite are reported and are compared with those of quartz and magnetite. MATERIALS AND METHODS A sample of cummingtonite-rich taconite, received from the Mitchell pit, near Babbitt, Minn., was crushed and ground through 100 mesh, and the product was fractionated magnetically into three portions. First, a drum-type laboratory cobber was used to separate a highly magnetic portion, consisting mainly of free, but also containing locked, magnetite particles. The cobber tailing was then passed in two stages through a Franz isodynamic separator. The middle fraction was isolated, and, upon examination petrographically, was ascertained to be principally cummingtonite. The 100 to 150 mesh fraction of this sample was selected for the present study. It was cleaned by leaching briefly with hot, dilute HC1 and then by rinsing repeatedly with demineralized water. A ground and elutriated fraction of -5p cummingtonite was used for the electrophoretic measurements.

Jan 1, 1961

By Don C. Blackmar

THE production of non-ferrous secondary metals has become a large and important industry in the United States, and deals with practically every type of manufacturing concern. Its business is unique in that it generally buys from its customers as well as sells to them, whether they are individuals, cities, corporations, or the United States government. Its operations are of vital importance to the success and prosperity of many of the nation's most important manufacturers; yet there are few industries about which less is generally known by those outside it, whether concerning the magnitude of its operations or the details of its actual technique. The industry itself is to blame for this meager publicity, because its technical men have made few attempts to openly exchange ideas, in spite of the excellent examples set by the iron and steel or the copper and brass industries. Whether this is due to the ancient shroud of secrecy generally supposed to cover smelting operations, or because its technical men actually felt that the industry was too puny to be interesting, is hard to say. This paper will consider its subject in a general way, attempting to show something of the size and importance of the industry, as well as its fitness to do its work well. Attention will be called to the sound economic reasons for the handling of non-ferrous wastes by specialists, and to the often unseen losses of metals and labor which occur when manufacturers reclaim their own metallic wastes. MAGNITUDE OF THE MODERN INDUSTRY No particular thought is given to the kitchen accident whereby a ruined saucepan is sorrowfully tossed into the ash can, yet it is a fairly safe guess that within a month this saucepan, together with hundreds of its fellows, will again be in service, perhaps in an automobile crankcase, or in an electric vacuum sweeper. It is by this conversion of the useless into the useful, whether from home or large manufacturer, that the secondary tonnage is built up.

Jan 1, 1928

By R. W. Mancantelli, J. R. Woodward

IN 1947 a large low grade deposit of uranium was located in the northwest corner of Saskatchewan, in the Beaverlodge property of Eldorado Mining & Refining Ltd. Most of the values occur as thin seams and as coatings on other minerals, and the ore, which is light and friable, is not amenable to the usual gravity methods of concentration. The acid leaching process developed to retreat the company's Port Radium tailings was also impractical, as the percentage of carbonates is high and the percentage of sulphides relatively low. Construction of the mill building and installation of equipment, both scheduled for 1952, awaited selection of a satisfactory ore dressing process on or before Oct. 1, 1951. An extensive research program on dressing of ores from the Ace mine therefore was undertaken by the Mines Branch in Ottawa, a research team at the University of British Columbia, and an ore dressing group at the company's Port Hope refinery. Pilot plant operations were conducted at the Ottawa plant of Sherritt Gordon Mines Ltd. under the general direction of C. S. Parsons, consultant on metallurgy and ore dressing for Eldorado. In mid-September, having compared results of the several research programs, Dr. Parsons recommended a process employing a carbonate or basic leach. He reported that, while the chemistry of the process had been proved, engineering of the flowsheet was incomplete, and he suggested that under normal conditions further pilot plant work at the Ace mine might be profitable. However, since this would involve a delay of 12 to 18 months in bringing the property into operation, he recommended that design of the concentrator proceed immediately. Concentrator capacity was determined by two considerations: 1) the amount of ore then available and 2) the expectation that continued improvements would be made in the ore dressing process as a result of the intensive research being carried out by the Mines Branch of the Department of Mines and Technical Surveys. As these improvements could affect both the chemistry and the en-

Jan 1, 1956

By Ira B. Joralemon

The sampling of disseminated copper deposits has been describeu often but the method of combining assays to give the true shape and value of the orebody as it will be mined has received less attention. As the ore mined during five or ten years at several of the great disseminated properties has averaged materially lower in grade than the published estimates, the question of the sampling and estimating of these orebodies seems timely. In this paper, attention is given particularly to factors that may cause errors in the final estimate. Sampling of diamond-drill holes, churn-drill holes, and underground workings is briefly described in the first part of the paper; then the method of combining assays to give the average grade and tonnage that will be mined is taken up in some detail. The necessity of study of the geology of the deposit and of probable costs is emphasized. Finally, the methods of calculating tonnages are outlined. DlAMOND-DRILL SAMPLING There are three main requisites for accurate diamond-drill sampling. First, the core should be removed and the hole cleaned out at the beginning of every sampling interval, usually 5 ft. (1.5 m.). After the rods are let down, water should be run through them until it becomes clear. The water must be clear before drilling starts. 'In this way the material knocked down from the sides of the hole by the descending rods is washed away, instead of being left to salt the sludge sample. The second requisite is to save all the sludge and all the core from every sampling interval. Where the material is uniformly heavy, the cuttings will settle suffciently in a box, through which the sludge flows s1owly.l Where part of the material is too light to settle readily, the sludge should be run into barrels, and allowed to settle until the water becomes clear. Then the clear water is siphoned off, and the sludge evaporated to dryness over a slow fire, sacked, and assayed.2 To obtain

Jan 1, 1925

By John C. Calhoun, Raymond G. Loper

Theoretical calculations for the decline of pressure and the variation of instantaneous producing gas-oil ratio with increased cumulative production have been made for reservoir systems under various producing drawdown values and for various spacings. These variables have been included by a modification of previously Published techniques. This consists essentially of utilizing a radial system flowing gas and oil in a succession of steady state calculations. The results of the calculations do not show any variation in the predicted behavior of the internal gas drive reservoir when either the drawdown or the spacing are changed. The prediction of performance on an internal gas drive reservoir has been presented by various authors. ',"' These predictions are in the form of a pressure decline and an instantaneous producing gas-oil ratio as a function of cumulative oil withdrawal. In making these predictions a basic assumption has been that the saturation of the reservoir is uniform throughout at any time, or that the pressure differential imposed on the reservoir system is zero. Because of these assumptions the validity of such predictions has been questioned. Their application to actual systems, where saturations are not uniform and where producing differentials exist, has been a hazardous procedure. The authors cited have used different methods of approach to the derivation of equations for making their predictions and for arriving at a solution of both equations, but basically the same relationships are utilized in each case. In all instances the instantaneous producing gas-oil ratio is calculated from the equation: In utilizing this equation an average reservoir pressure and an average reservoir saturation must be known, the former to define ß, v, s, and uo/ug and the latter to define kg/ko. Predictions can be made, therefore, only for the conditions of a uniform reservoir saturation and a uniform reservoir pressure. This restriction of requiring a uniform oil saturation can be resolved by applying two-phase steady state flow for the radial system to the reservoir's history. Radial steady state flow is defined when the ratio of phases flowing,

Jan 1, 1949

By John Fulton

Early in the year 1875, some difficulty was experienced in the " Old blast-furnaces " of the Cambria Iron Company, at Johnstown, Pennsylvania, arising from the increased use of native coke, prepared in Belgian ovens near the furnaces, in mixture with Connellsville coke, in the production of Bessemer pig-iron. This was the more surprising at that time, because a very caulplete coal-crushing and washing apparatus, after the Bradford plan, had just been put into successful operation, affording a pure coal for coke-making. It was confidently expected that this thorough cleansing of the coal would improve the quality of the coke and fit it for the increasing manufacture of Bessemer pig-iron. But the trouble with the native coke continued. Experiments in fuel charges-increasing and reducing them—failed to correct the irregular working of these furnaces. Increasing the charge of native coke produced abnormal heat at the top of the furnace, reducing it cooled the furnace below. At this stage of affairs, the Hon. Daniel J. Morrell, general manager of the Cambria Iron Company, requested the writer to make the requisite investigation to determine the nature of this coke-difficulty, and to ascertain why the Johnstown coke could not be used in blastfurnace work as well as Connellsville. This task at first did not appear to present any special difficulties, but subsequently it expanded into proportions that caused no little anxiety. The first effort was directed to procuring average samples of Johnstown and Connellsville coke. At this period of the investigation, it was assumed that the whole matter could be intelligently solved by comparing the chemical analyses of the two cokes: Johnstown Coke. Connellsville Coke. Moisture,.......... 0.30 Volatile matter,......... 0.46 Fixed carbon,.90.48 89.57 Ash,.8.96 9.11 Sulphur,.0.56 0.82 Phosphorus,..... 0.014 100.00 100.274 Analysts, T. T. Morrell. A. S. McCreath.

Jan 1, 1884

By J. Stubbins

1 1.4-1. Source of Water. Precipitation in the form of rain or snow is the original source of water that enters most surface mines. The precipitation, which does not escape to the atmosphere, either becomes surface run- off or infiltrates into the ground to become ground water (3,4). Evaporation and surface run-off can be measured. The water that infiltrates the ground disappears from view and is more difficult to evaluate. In general, it moves in a pattern similar to the surface run-off, but at a much slower rate, since its progress is impeded by many subsurface conditions. The infiltrating water descends through the soil and rock by whatever passageways permit flow until the water table or top of the zone of saturation is reached. Though usually pictured as a level surface, it is dependent upon the topography and the permeability of the enclosing material, and therefore it can be as erratic and unpredictable as the subsurface geology. Ground water may become surface run-off again at a lower point, and likewise, surface run-off of lakes and streams can infiltrate to become ground water. Should the ground water be confined to a permeable zone overlain by an impermeable barrier, a pressure is created. Such water is said to be artesian if the pressure head is sufficient to raise the confined water to the surface. These conditions are more commonly found in relatively flat-lying bedded formations. 11.4-2. Recognition and Estimation of Water. Dewatering and flood control should be considered by the design engineer at an early stage in all surface mine planning. Recognition of the possible problems, and making allowance for their solution, is an inexpensive precaution. Circumstances which should lead to investigation are: 1. High rainfall 2. Experience of other mines in the area 3. Evidence of water and caving in drill holes 4. Presence of springs and artesian wells 5. Geological evidence of aquifers.

Jan 1, 1968

By C. P. Melloy

INTRODUCTION Ventilation practice at Isa Mine has been evolving since underground mining began in 1931. Much fundamental work has been conducted and reported regarding the primary ventilation system [Mathews K.E. et a1 (1967) and Brown J.R., Fisher T.H., Gibson K.L. (1979) 1. However, ventilation networks for subsystems such as open stopes, have evolved with experience. This paper outlines current ventilation practice for open stoping. Mount Isa Mine The mine is located in semi-arid North-West Queensland, Australia, and currently produces 20 000 tonnes of copper ore and 10 000 tonnes of silver-lead-zinc ore daily in each five day working week. Mining extends over a north-south strike length of 3.5 km with a maximum width across dip approaching 1 km, and is to a depth of 960 m (Figure 1). At present approximately 90% of the mine's copper production is from the 1100 Orebody, which contains ore reserves of 121 million tonnes of 3.2% copper. Open stoping is currently the mining method employed, and is used for primary stoping and pillar recovery adjacent to cement fill walls. The development of stoping methods in the 1100 Orebody has been documented by Kirkby R.W., Blair J.R., and Hutton R.C. (19781, Hornsby B. and Sullivan B.J. (1978), and Alexander E.G. and Fabjanczyk M.W (1981). As many as thirteen open stopes may be producing concurrently in the Orebody (Figure 2). The multiple silver-lead-zinc orebodies containing reserves of 54 million tonnes of 150 g/t silver, 6.4% lead and 6.5% zinc, are mined by open stoping, and cut and fill techniques. These methods have been documented by Goddard I.A. and Bridges M.C. (1977 1, and Goddard I. A. (1981 1. Only the ventilation of the 1100 Orebody open stopes will be discussed. However, the same ventilation philosophy is employed in open stope design in the lead orebodies.

Jan 1, 1981

By John B. Hastings

The origin of the watery vapors of vulcanism has always been an object of interest and speculation to the seismologist, and as theories of the genetic origin of ore-deposits have of late years been pretty well narrowed down to the expiring forces of plutonic action, the same question has attracted mining engineers and geologists, as is well shown by the discussions of the subject in our Transactions. The important part taken by volcanic emanations in the origin of pegmatites and quartz-veins, described in my paper, Origin of Pegmatite,' and their latent power to concentrate into useful deposits such scattered gold as occurs in the Hartsel granite, make a discussion of their derivation but a natural third and final step. It is coilceded that enormous amounts of vapor accompany vulcanism, though perhaps we are apt to forget that steam has 1,700 times the volume of water, besides which the column seen over Vesuvius and other volcanoes is greatly mixed with air; the immensity of such volumes compared with solids and liquids is shown by the experiment of Gautier, who, by heating dessicated granite to 100' C., evolved from it gases 20 times, and steam 90 times, its own volume. Dana appraised the average amount of water left in ordinary rocks as 2.5 per cent. T. M. Read estimated that the Mississippi river carries to the sea annually 150,000,000 tons of rock material. If these Mississippi sediments, as deposited, contained 20 per cent. of water, it would be 600,000,000 cu. ft., or 4,500,000,000 American gallons, annually. Allowing the vapor suspended over a volcanic cone to be mixed with 80 per cent. of air, this amount of water converted into steam would replenish anew, every 9 min., a column 15,000 ft. high, 2,000 ft. in diameter at the base, and • 10,000 ft. at the top. Read's estimate is only half of the amount given in a more recent and probably correct one.2

Jan 1, 1909

By Emory Kemler

The problem of determining the most desirable operating conditions of an oil-well pumping unit, the selection of the proper material and size of sucker rods, and the design of the pumping unit, requires that the sucker-rod loads be known with a reasonable degree of accuracy. In production practice, it is also desirable to know the effects of operating speeds and strokes on a plunger motion, as well as on the rod loads. For a particular well, data on rod loads can be obtained by measuring the load in sucker rods with a dynamometer. This method is not satisfactory because it does not permit the various factors to be investigated independently. It is also impossible to measure the plunger motion simultancously with rod motion under operating conditions. The mathematical solution is impractical because of the simplifications that have to be made to get a solution and the tremendous amount of numerical work that is necessary after such a simplified solution has been attained. This paper shows how analogies and models can be applied to the solution of these problems. The loads set up in a sucker-rod string during the ordinary pumping cycle are made up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rod friction, stuffing-box friction, plunger friction, friction of the oil in the tubing and rods, arid friction loss through the valves. The problem of determining the sucker-rod load is further complicated by the fact that the long oil column and the sucker-rod column act as springs, which affect the transmission of the polished-rod motion. A further complication is the fact that the motion cannot be transmitted at a speed greater than that of the velocity of sound in the material, and this means that there will be a time lag in the transmission in the motion, as well as a modification of its magnitude and a phase displacement.

Jan 1, 1936

By Robert Phelps

A STUDY of solid solutions has long been a source of interest because of the conditions -controlling their formation. X-ray investigations so far have been conducted with the idea that there were two types of solid solutions. In the first type, an atom of the solute was supposed to replace an atom of the solvent in the crystal lattice. In the second type, an atom of the solute was supposed to lie in one of the interstices between the atoms of the solvent. These pictures both require that the sizes of the atoms must play an important part in the process of solution. It is the purpose of the present investigation to study the mechanism of solid solution, using pure silver as the. solvent, and pure aluminum as the solute. X-ray measurements show that these elements have the same "shape" of atomic domains (they both crystallize as face-centered cubes) and that their atomic diameters differ by less than one per cent.1 The results of the present investigation point toward a chemical rather than a physical picture of the nature of solid solution, and make the older' pictures merely special cases of a more general picture. The new theory has the advantage, too, that it offers a rational explanation of certain phenomena which hitherto have been only interesting detached facts. The aluminum-silver system which was, chosen for this study has been studied by various methods by several workers. By means of thermal analysis Gautier2 and Petrenko3 have determined the phase diagram. Hansen4 studied the aluminum-rich alloys by means of thermal and microscopic analyses. , He showed that at high temperatures silver dissolved in aluminum to the extent of 47 per cent by weight at 5600 C. But this solubility decreased to 1 per cent at 200° C. Westgren and Bradley5made an extensive X-ray study of these alloys. They used the change in the lattice parameter of silver as a criterion of the solution

Jan 1, 1932

By Don C. Blackmar

The production of non-ferrous secondary metals has become a large and important industry in the United States, and deals with practically cvery type of manufacturing concern. Its business is unique in that it generally buys frorn its customers as well as sells to them, whether they are individuals, cities, corporations, or the United States government. Its operations are of vital importance to the success and prosperity of nlany of the nation's most important manufacturers; yet there are few industries about which less is generally known by those outside it, whether concerning the rliagnitude of its operations or the details of its actual technique. The industry itself is to blame for this meager publicity, because its technical men have made few attempts to openly exchange ideas, in spite of the excellent examples set by the iron and steel or the copper and brass industries. Whether this is due to the ancient shroud of secrecy generally supposed to cover smelting operations, or because its technical men actually felt that the industry was too puny to be interesting, is hard to say. This paper will consider its subject in a general way, attenlpting to show something of the size and importance of the industry, as well as its fitness to do its work well. Attention will be called to the sound economic reasons for the handling of non-ferrous wastes by specialists, and to the often unseen losses of metals and labor which occur when manufacturc~rs rcclairn thrir own metallic wastes. Magnitude of the Modern Industry No particular thought is given to the kitchen accident whereby a ruined saucepan is sorrowfully tossed into the ash can, yet it is a fairly safe guess that within a month this saucepan, together with hundreds of its follows, will again be in service, perhaps in an autonlobile crankcase, or in an electric vacuum sweeper. It is by this conversion of the useless into the useful, whether from home or large manufacturer, that the secondary tonnage is built up.

ONE of the fundamental reasons for the extreme rapidity with which the Porphyries developed after the trail had been blazed at Bingham was the amenability of the deposits to prospecting and proving of the ore either by churn-drilling or by diamond-drilling. At Ray churn-drill data formed the principal basis for early calculations of ore reserves; and in 1913, Inspiration floated its first bond issue for $6,000,000 on the strength of the estimate of 45,000,000 tons of sulphide ore assaying just over 3 per cent copper. The money was obtained in spite of the fact that no one ever had actually laid eyes on more than a minute fraction of that ore. The customary method of developing a copper deposit before the Porphyry era had been to sink shafts or drive adits and then to follow and expose the veins or lodes with horizontal and vertical underground workings-drifts, crosscuts, raises, and winzes. The excavated material sometimes was sampled in bulk; but always the walls of the openings would be channeled at intervals to obtain small samples representative of the ore left in place. This process was known as "blocking out" ore. It was costly and it required a great deal of time to prove the existence of immense tonnages. The early development at Utah was done in this way; likewise, at Miami. This fact helps to explain why only 3,000,000 tons of ore was reported as being developed when J. Parke Channing wrote the report on which the original Miami financing was based in March, 1908. Fortunately, his 3,000,000 tons averaged 3'per cent copper. At Ray, Seeley W. Mudd estimated 3,000,000 tons of ore in June, 1908, developed principally by underground working; but by the end of 1909, Henry Krumb was able to report 50,000,000 tons as the fruit of a little more than a year of churn-drilling.

Jan 1, 1933

By Barry N. Whittaker

INTRODUCTION Considerable progress has been achieved with long- wall mining in recent years especially in enabling increased rates and levels of output to be gained, higher standards of safety and increased usage of advanced technological developments. Longwall mining also has major long term advantages, prominent amongst which is general minimisation of the effects of pillars and room intersections giving rise to future instability problems as can be the case with room and pillar mining operations. The fact that longwall mining is not presently limited by depth below surface inclination of seams or thickness of seam to be worked strengthens its position as the most popular underground mining method for extracting coal seams in Europe. Its wider application in North America and Australia can give rise to significant economic benefits coupled with higher levels of safety and recovery of coal. This present paper reviews recent progress achieved and draws attention to the more important factors influencing longwall mine design and layout. LONGWALL STRATA PRESSURE ABUTMENTS A longwall gives rise to major redistribution of strata pressures. The roof behind a longwall is normally allowed to cave and permit subsidence of the overlying strata and eventually giving rise to a trough depression at the surface. Consequently, reestablishment of strata loading within the caved region behind the longwall depends upon effective caving and subsequent recompaction. This requires sufficient depth pressure and/or adequate width of extraction in relation to the depth to achieve breaking of overlying roof beds necessary to reload the extracted region. Figure 1 shows results of an analysis carried out by Whittaker and Singh (1979) indicating the pattern of redistribution of vertical stress around a longwall in the plane of the seam. The analysis represents the average depth of longwall working in the UK, and was performed using a stress balance assumption of compatibility before and after mining. The main stress abutments are indicated by (1) the front abutment strata pressure zone which travels with the longwall, and (2) the flank abutment strata pressure zone which

Jan 1, 1982

By B. E. Fernow

MINING interests in the Western mountains are very seriously affected by the danger to property and life from destructive snowslides and avalanches. This is a danger which the miner has largely brought upon himself by an improvident stripping of the timber from the mountain slopes, and, therefore, he might be expected to take an interest in the reforestation of the areas thus devastated. A canvass was lately undertaken by the writer to ascertain approximately the extent of the damage suffered from this source, but the difficulty of obtaining reliable data has proved too great to permit, as yet, even an approximation. So much, however, is certain : that the loss of life is considerable, and that much property is destroyed almost every winter. True, neither the number of avalanches, nor their destructiveness, nor the amount of loss compares with what Switzerland experiences. This is due not only to the greater precipitousness of the Alps and to different climatic conditions, but also to the fact that in Switzerland a larger number of settlements is exposed to these dangers. A very complete and interesting official report on the very numerous and destructive avalanches occurring in Switzerland during the season of 1887-1888 has just been published as a contribution to the inquiry, whether and how these dangers can be averted. Peculiar weather-conditions, in addition to heavy falls of snow, were the reasons for the frequency of the phenomenon during that winter. This report records 1094 avalauches, by which 850 houses were destroyed or severely damaged; 84 persons and 752 cattle were buried; traffic on railroads and on highways was greatly interrupted, and the damage to personal property alone was valued at over $100,000. One of these snow-masses covered about half an acre, with a cone 250 feet in height. During the same year in Tyrol the number of avalanches was 3647. Of these 1355 run over permanent beds; that is, they recur annually, so that they are

Jan 1, 1890

By Dorsey Hager

DORSEY HAGER, Tulsa, Okla.-I have been asked why the Dexter region is dry. I would like to know myself. I drilled two dry wells on that same anticline which has production to, the east and west and south and north. That same anticline has seven domes that have been drilled and only three have proven productive out of the seven. In other words, you have one well-defined anticline with seven domes along its length, all mappable, all checked carefully, and only three of those seven have produced. Now why the others did not produce, I do not know. L. L. HUTCHISON, Tulsa, Okla.-There is no appreciable difference in the character or structure of the sands? DORSEY HAGER.-NO, I have never .been able to see any appreciable difference in the sands where we got production and Where we did not get it. I will say that the deepest wells we drilled, in the vicinity of Dexter, had no sands at the point where they got the production farther north. I. N. -KNAPP, Ardmore, Pa.-I first went to the Kansas-Oklahoma field in 1895 and occasionally thereafter until 1899, when I began drilling; for oil. I started close to wells that were producing gas and which, when drilling, lead made good oil showings in a sand above the gas. I thought these showings were good enough evidence of an oil pool for me without looking for any anticline and I made a paying development in what' I was afterward told by geologists was probably a synclinal trough. If I remember correctly Dr. Orton's report on the lola gas pool (about 1898) he distinctly said that he found no evidence of anticlinal structure and concluded from the records of a large number of wells that there, was a terraced structure of the productive gas sands, of which there were no surface indications.

Jan 4, 1917