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By GEORGE S. POPE

This bulletin is a revision of Bulletin 63 and is published by the Bureau of Mines in order that purchasers of coal for Government, State, municipal, or private use may be informed regarding advances or refinements in sampling coal deliveries and preparing specifications for the purchase of coal. The purchase of coal by the Government under specifications depending on the heating value of the coal, its content of ash and of moisture, and other considerations, rather than upon the reputation or trade name of the coal, was based on the fuel investigations begun by the Technologic Branch of the United States Geological Survey in 1904. The plan was first adopted by the Treasury Department in 1906. Since then the plan, variously modified in form, but the same in principle, has been gradually adopted by other departments until, at present, of the coal used by the Government, the total value of which approximates $8,000,000 annually, more than half is purchased under specifications. The Government publications dealing with the adoption by the Government of the specification plan, the number of contracts awarded on that basis, and the quality of the coal delivered under such contracts in the several fiscal years covered by the reports are given in publioations a listed at the end of this bulletin. Under the authority of acts of Congress making appropriations for analyzing and testing fuels belonging to or for the use of the United States Government, a laboratory is maintained at the headquarters of the Bureau of Mines, Washington, D. C., where samples representing deliveries of coal purchased under specifications for Government use are analyzed and tested. At this laboratory more than 1,200 samples have been analyzed and tested in one month. With the complete equipment and the efficient force employed, the analytical work has been so perfected that the analyses and heating-value tests of the samples received are as accurate as may be reasonably expected in laboratory work of this nature. One of the serious drawbacks to the general adoption of the specification method for the purchase of coal is the difficulty of obtaining at reasonable cost samples of coal that can be considered fairly representative of the commercial product delivered in wagons, railroad cars, or ships. Therefore the method of taking and preparing samples for shipment to the laboratory has been given fully as much care as the making of the analyses and tests, and a general plan of collecting samples fairly representative of the delivered coal has been evolved through various modifications and improvements based on experience and increased knowledge of the physical and chemical characteristics of the various coals that are purchased by the Government. The method that is in general use by the Government is described in the following pages. In connection with studies of the coal deposits of the country, of the best methods of preventing waste in mining, and of increasing efficiency in the utilization of coal belonging to or for the use of the Government, geologists and engineers of the United States Geological Survey and of the Bureau of Mines have visited more than 2,500 coal mines scattered through all of the coal-producing States and Territories. From each mine 2 to 8 or more samples were taken, the number depending upon the size of the mine and its output. The analyses and descriptions of the samples collected up to the end of the fiscal year 1913 are published in Bureau of Mines bulletins 22 a and 85,b and those of samples collected in the fiscal years 1914 and 1915 are presented in a bulletin that will soon be published by the bureau. A study of the analyses of these samples and of the samples taken from cars shipped from a number of the same mines shows that the mine samples are as a rule of higher grade than the average commercial shipments, particularly with respect to containing a lower percentage of ash and having a correspondingly higher heating value. This difference is due to the fact that the Government inspector, proceeding on the basis of what can be done by a good miner, usually removes more of the partings of bone, slate, and other extraneous matter from his mine samples than the average miner does in ordinary practice, the aim of the miner being to get the maximum number of tons past the tipple inspection, as his earnings are based on his output. The average miner, therefore, does not always take as much care as he might in rejecting the impurities. The difference may be caused, too, by the presence of pieces of the mine roof and floor in commercial shipments. The Government inspector can readily

Jan 1, 1916

THE most successful and largest meeting of the Auxiliary to the A. I. M. E. was held this year. Great praise is due Mrs. Arthur S. Dwight, the acting chairman of the Ladies' Committee in the ab-sence of Mrs. Barron, and the other members of her committee for the able way in which they planned and carried out a varied and interesting program. Miss Margaret Callow, chairman of the Junior Committee, with her co-workers, made the days delightful for the Junior members, as well as visiting daughters. Under the leadership of Mrs. Jenkins, the registration of the ladies proceeded smoothly Monday morning. At the Mrs. Jenkins became ill with pneumonia on the second day of the meeting and was taken from the dinner to a hospital where she died the following Sunday. Born in Kansas City fifty years ago, she was an active and valued member of the Auxiliary in which she had long represented the Puget Sound Section. Mr. and Mrs. Jenkins, the latter treasurer of the Utah Consolidated Copper Co., had previously lived at McGill, Nev., where they are well known. She leaves a son and a daughter. luncheon on the fifth floor, Mrs. DeGolyer and Mrs. Church arranged a delightful hour, when greeting visit-ing friends proved more. interesting than food. Mrs. Bain efficiently ushered the ladies through the after-noon's program, seeing that they all found the buses on time. The first stop was at the Cloisters, where the quaint carvings and the faint odor of incense trans-ported all the visitors to the Middle Ages. That atmos-phere still clung, as we all looked at the marvelous collection of old Chinese jade, at the Metropolitan Museum, which was the next stop. The buses then took us to the MacDowell Club, where Mrs. Dwight gave a charming welcome, in the absence of the hostess, Mrs. Barron. The program, by Mr. and Mrs. Hardesty John¬son, was such a delight that repeated calls induced the artists to graciously respond with an encore. Then Mrs. Coster and Mrs. Sharpless assisted Mrs. Dwight in serving tea, about the glowing fireplace. In the evening the theater-goers guided by Mrs. Jordan were thrilled by "Interference.:" A detailed account of the annual meeting, in many ways the most interesting the Auxiliary has had, will be published later. This held the attention. of the mem-bers both morning and afternoon, on Tuesday. The absence of the President, Mrs. Barron, was much re-gretted, and the letter and the cablegram with her cor-dial greetings were much appreciated. Miss Stone ably presided in the place of Mrs. Barron, and graciously welcomed the incoming President, Mrs. Hoover. Her well-worded speech, accepting the office, was received with much enthusiasm. The visiting members were especially pleased with her description of herself as a "peripatetic-president." promising to visit the various sections as she crossed the continent on her frequent trips to California. An inspiring report was read from each section, and most particularly pleasing was a greet-ing brought by Mrs. Bateman of Toronto, from our sister organization in Canada. The sections are surely to be congratulated on their splendid work, not only for their own members, but also in sending clothing and other aids to the needy, as Mrs. Reynders directed, and in supporting libraries under the leadership of Mrs. Huntoon. The important work of the Educational Com-mittee, with its presentation of scholarships to various deserving young men, has been most efficiently carried on by Mrs. Jennings. Mrs. Jordan has inspired many to help in Braille, and Mrs. Eilers has extended the hos-pitality of the Auxiliary to many. The Washington Section is leading a movement to extend the privileges of Girl Scouting to the girls in lonely mining camps. The officers of the past year received flowers and grate-ful appreciation, and the incoming officers received a warm welcome. Very delightful features of the after-noon were the speech by the President of the A. I. M. E. for the coming year, Dr. George Otis Smith, and when a visiting member rose to say how much all the visiting members had enjoyed the Auxiliary's hospitality. The banquet and dance at the Waldorf were the most brilliant the Auxiliary has attended. Nearly twelve hundred were there to enjoy the festivity and to hear the speeches given, as Mr. Hoover and the other re-cipients accepted their medals and awards. The young people, the future supporters of the A. I. M. E. and the Auxiliary, enjoyed more hilarious tables in the bal-conies, and all enjoyed the dancing later.

Jan 3, 1928

By Kenneth F. Whinery, John M. Campbell

Basically, the Buckley-Leverett theory involves two systems which are similar in nature but are differentiated by time. These systems may be described by the fractional flow and frontal advance equations which essentially characterize the mechanics of oil movement while being expelled from the reservoir. The fractional flow equation originally developed by Leverettl may be expressed in the more usable form The development of this equation is based on Darcy's law describing fluid flow through porous media and applies to the flow at only one point (it is a point function). For simplification, the fractional flow equation is written in the above form because the capillary forces always increase the fractional flow of the displacing phase regardless of the direction of flow or the displacing phase. If, for simplicity, the effects due to gravity and capillary pressure differences are neglected, the fraction of the displacing fluid, f, at any point in the flowing stream is related to the properties of the system by 1 Thus, it is seen that in the absence of capillary and gravitational effects, fd for a given sand and fluids varies only with saturation and pressure. The magnitude of the viscosity ratio, —a has an effective range (range of about 30) in the system where gas is displacing oil and a much smaller range for water displacing oil. In order to make the fractional flow equation more versatile, it is necessary to connect the fractional flow at a given point and saturation with time. This problem was approached by Buckley and Leverett" who developed the frontal advance equation, Eq. 3 states that the rate of advance of a plane that has a fixed saturation, Sd, is proportional to the change in composition of the flow stream caused by a small change in the saturation of the displacing fluid. It is, essentially, a transformation of a material balance equation representing the net rate of accumulation of the displacing phase within a homogeneous sand block. This accumulation is proportional to the difference between the rate at which the displacing fluid enters the sand and that at which it leaves. Eq. 3 describes the velocity with which a plane of constant displacing phase saturation advances through a porous system. Buckley and Leverett," Babson,' Kern," Welge, and others have adequately discussed the basic mechanism and application of the fractional flow and frontal advance equations. APPLICATIONS OF THE FRONTAL ADVANCE THEORY TO PETROLEUM RECOVERY Two general applications of the Buckley-Leverett frontal advance theory involve the system in which the oil is being displaced by an expanding gas cap overlying the oil zone and that in which the oil is being displaced by water. Displacement by Gas in the Presence of an Immobile Water Saturation A system in which gas is the displacing phase may be thought of as having two forces effecting the displacement process. These forces are the gravitational force and that force exerted by the displacing gas. The gravitational effects control the displacing efficiency of the gas. The gravitational effect will be less at higher rates of flow, thereby reducing the effectiveness of the displacement of the oil by the gas. The more efficient displacements occur at flow rates which are less than the gravity free fall rate. Capillary forces can be neglected without materially changing the magnitude of the gas saturation. The Mile Six pool is used herein to illustrate the calculating procedures in evaluating gas drive-gravity drainage field perfomlance. These calculations represent the determination of the gas-oil contact when the distribution of the hydrocarbon pore volume is considered. Two methods

By Louis I. Briggs

Evaporite rocks, salts of the more soluble ions in seawater, are deposited when seawater becomes concentrated by excess evaporation in marginal basins having restricted circulation with the open sea. The simple conceptual model of an evaporite basin (Figure 1) has a single inlet connecting the basin to the open ocean, the restriction to open circulation being caused by a bar or reef near the mouth of the inlet. As the oceanic water flows from the inlet into the basin it tends to form a thin layer of brine that spreads out over the surface of the basin brine, and as it does so, the salt concentration In the surface layer gradually increases owing to continued evaporation of the water. When the solubility products of the salts in the surface layer are exceeded, the salts precipitate and settle to the bottom of the basin, The order of precipitation follows their order of least solubility. Normally the carbonates separate first, followed by the sulfates and chlorides and the more complex double salts. In nature there is considerable overlap in their ranges of precipitation. The water flow in the basin, also shown schematically in Figure 1, diverges from the inlet essentially perpendicular to the lines of' equal salinity in the surface brine. The distribution of salts deposited in such a model will parallel the isosalinity lines, being arcuate and concave toward the inlet (1)

Jan 1, 1967

By G Baiden

The removal of rock blockages in mining operations has long been a risky undertaking, especially in high overhead conditions. Moreover, the assessment of where to put charges and the placement of them has been difficult due to the lack of visibility and safe access to the area. Traditionally, wedging long poles with explosives on them to keep the operator at a relatively safe distance has been the tried and true method of attempting to remove the blockages. Unfortunately, this is not a perfect system as it usually takes several attempts to remove the blockage. Each successive attempt results in even more dangerous conditions for workers and/or damage to the mine due to the successively larger amounts of explosives used until the hang-up finally comes down.Over the years, different ideas have been proposed to improve this process and reduce the inherent safety risks. Some of the technologies that have been trialled include projectiles fired at the hang-up; large, cumbersome arms; and massive amounts of explosives, each of which come with their own inherent safety risks that result in dangerous situations for miners and the mine.After gaining a thorough understanding of the process, Penguin Automated Systems Inc has developed a robotic system that is capable of working in a rock blockage safely. The idea combines the latest in telerobotics technology with 3D scanning and underground geospatial positioning. The hang-up removal is performed by scanning the inside of the hang-up to rapidly develop a geospatially placed 3D model for the operator to use. The 3D model is detailed enough that the operator can attempt to pick the ‘keystone’. A blasting engineer or the operator can then determine the exact position where the explosive charge should be placed in the 3D model and thus at the actual hang-up. The operator, controlling the robotic arm, uses the 3D virtual reality model of the robot system and the actual drawpoint information model to display the location information, the arm can then reach into the hang-up to position the charge using the kinematic model of the robot system. The 3D model is used to provide views inside the hang-up so that the operator can move the arm safely and precisely. This process allows the operator to place the charge (using the 3D representation of the drawpoint) from a long distance away. As the process continues, the end of the arm drills the rock and precisely loads the explosives. The robot then returns the blasting cable to the command station, which is located in a truck at a safe distance from the blockage.This paper will review the development of the system and present the results to date.CITATION:Baiden, G, 2016. Robotic hang-up assessment and removal of rock blockages in mining operations using virtual reality for safety, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 745–754 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Yun Zhang, Haijun Jiang, Shenggen Cao, Chen Wang

The distribution of front abutment pressure is closely related to the force, deformation and energy distribution of hard roof before periodic weighting. So it is necessary to carry out research on the relationship between them. According to front abutment pressure distribution feature, using the location of peak front abutment pressure as the dividing point, coal seam is divided into two parts along the direction of mining: the yield zone that is the area between the faceline and the point where the maximum front abutment pressure occurs, and the elastic zone that is the part before the point of peak front abutment pressure. The proposed mechanical model of unit width hard roof at the panel center periodic weighting consists of five parts including the yield zone. All parameters of the deflection equations for each of the five parts that satisfy the continuity conditions and natural boundary conditions are obtained by using the Matlab software. The continuous curves of front abutment pressure, deflection, bending moment and bending strain energy density distribution of hard roof are obtained by iterative approximation method. The following conclusions can be drawn through analyzing those curves: (1) The position of peak front abutment pressure is located at the transition of coal seam foundation from yield zone to elastic zone (elastoyield critical point), the distance of it to the faceline is equal to the width of yield zone. The peak front abutment pressure increases with yield zone with. (2) The peak bending moment in front of the faceline, and the distance of it to the faceline increase with the yield zone width. The deflection of hard roof at the face and midspan also increase with yield zone width. (3) As the yield zone width increases, the accumulated elastic energy of hard roof in front of the faceline increases, and the core zone of energy moves forward away from the face. (4) When the yield zone width is zero, the whole coal foundation is regarded as elastic foundation, and the peak front abutment pressure occurs at the faceline.

Jan 1, 2015

Hoisting ropes are constructed of wires and strands positioned helically around the axis. This helical positioning causes that, in the rope loaded at the end with the weight Q, the longitudinal displacement u, axial force P, torsional displacement v and constant torsional moment M are generated. More over, the proper weight of the rope q gives the force acting along the axis of the rope. This force changes its value from 0 at the bottom to qL at the top. This force gives, along its length, a variable torsional moment making the rope rotate. During the movement of the conveyance downwards the falling part of the rope rotates, which makes it untwist on the section up to the half-depth of the shaft and twist on the other half-depth. As the result, the twisting lay of the rope changes increasing in the upward direction and decreasing downwards. The angle of twist of the strands changes in an apposite way. When moving upwards, the uplifted rope does not twist and retains its state of deformation up to the moment when it passes over the pulley. Next, the cycle of untwisting and twisting repeats during the movement of the other conveyance downwards. This phenomenon is known from mining practice. It was also analysed, in the works of Glushko (1966) and Popowicz (1963).

Jan 1, 1995

By W. F. Stowasser

downdraft traveling grate process to agglomerate pelletized iron ore concentrates has been successfully demonstrated in a pilot plant at Carrollville, Wis. Work there followed several years of development in the Allis-Chalmers Mfg. Co. laboratories, and the pilot plant phase was carried out in cooperation with Arthur G. McKee & Co., consultants and engineers to the iron and steel industry. End result of the process is conversion of iron ore concentrates into a form which can easily be transported and smelted in the blast furnace. Process Description The first of two process steps incorporates the art of balling and prepares the concentrates for burning. The second step consists of burning the green balls on the grate machine to the hardness required for shipping and handling purposes and for reduction in blast furnaces, see Fig. 1. Facilities are provided at the pilot plant to receive carload quantities of concentrate. The concentrates are loaded into a 50-ton bin direct from railroad cars. Because of the variable moisture content of the concentrates after shipment in an open railroad car it is necessary to repulp and refilter the concentrates to maintain a uniform and proper moisture content for the balling operation. Concentrates are conveyed to slurry tanks, and the slurry, at 50 to 60 pct solids, is pumped to a 4x4-ft drum filter. The filter provides feed of uniform moisture to the plant. Magnetite concentrates are normally filtered to produce a cake containing about 10 pct moisture, a necessary requirement for the following balling operation. The filtered concentrate is conveyed to a rotary bin table feeder which acts as a surge bin for the filter cake and delivers a steady flow of concentrates to the balling drum. It is often desirable to make additions to the concentrates as they are fed to the balling drum. These additives, such as bentonite, increase the strength of the finished green pellet and improve ballability of the concentrate. A vibrating feeder supplies additive to the feed belt, and the additive is mixed with the concentrate in the balling drum. The balling drum, shown in Fig. 3, is 8x3-ft diam. An oscillating cutting bar maintains the lining in the drum by trimming off the buildup of excess concentrate as it forms. The drum is operated in closed circuit with a lx4-ft rod-deck vibrating screen. Undersize pellets or seed pellets from the screen are returned to the balling drum until they grow to the desired size. Size of pellets is controlled by the opening in the screen deck. The formation of pellets in the balling drum is affected by many variables. Some of these are: the size distribution of the feed, the particle shape of the concentrate, the feed rate to the drum, the moisture in the concentrate, the speed of rotation of the drum, the slope of the drum, and the type of trimming obtained with the cutting bar. In this process, attempts are made to control the pellet size within the limits of % to 5/8 in. diam. The screened oversize pellets are conveyed under a coal feeder where sufficient powdered coal is added to the belt to produce desired results in the burning process. The top size of the coal successfully used has been 20 mesh, and anthracite was used in the test program. Fig. 4 illustrates the vibrating screen and the coal feeder. The pellets and free coal are conveyed together to the 5x3-ft diam- reroll drum that rolls the coal onto the surface of the pellets. This drum is also equipped with a cutting bar. The prepared pellets, containing bentonite, water, and surface coal, are elevated to the traveling grate, which consists of a continuous strand of 37 pallets. Each pallet, with a grate bar area 2 ft wide by 1 1/2 ft long, has 14-in. high side plates, Fig. 5. Feeding and distribution of the green balls to the grate is handled by a short conveyor which oscillates back and forth across the 2-ft width of the grate. An adjustable vertical plate located several inches in front of the head pulley of the oscillating conveyor controls the height of the bed and levels the moving bed of pellets. This method of feeding prevents segregation of various size pellets as well as fines and produces a uniform, permeable bed. The pallet train moves under the furnace and across four windboxes, located beneath the pallet frames, see Fig. 2. As the green pellets are deposited on the grate, partial drying of the pellets begins over a 2-ft long updraft windbox. The low temperature air reduces the moisture in the pellets in the lower level of the bed and this operation is essential to prevent sagging of the bed during later stages of the Process. The air used for this drying is recuperated from cooling the pellets on the grate, and supplemental heat, required for starting the Process, is obtained from an auxiliary burner. The pellets are then moved by the grate into the furnace and over an 8-ft windbox, designated as the downdraft waste windbox. Products of combustion are exhausted from this windbox to atmosphere. The furnace, shown in Fig. 6, is constructed with three chambers to provide downdraft drying, preheating, and ignition, respectively, to the pellet bed as it passes through. Overall length of the furnace is 5.57 ft; however, the exterior wall ends may be moved to reduce the length and also adjusted to Obtain the bed height desired, The drying, preheating, and ignition sections of the furnace are supplied with medium temperature

Jan 1, 1956

By Scott D. Neely, Donald R. Clark

"An existing landslide located at the southeast corner of the Telluride Regional Airport has been in an active state of failure for several years. The presence of the landslide has represented an on-going liability for the Airport, the Federal Aviation Administration and the Colorado Department of Transportation. A catastrophic failure of this landslide occurring in a manner similar to that which occurred at the Airport in 1987 has posed an on-going threat to closing Colorado State Highway 145 south and below the slide area. The existing landslide has been characterized as a series of multiple failed block areas located downhill of the airport runway that have occurred in severely weathered Mancos Shale.A total of 12 alternatives were evaluated to mitigate the landslide, including the preferred alternatives of either partial or total landslide removal. However, prior development has left essentially no place on the airport property that would allow for the disposal of the landslide debris for either the total or partial removal alternatives, and the closest off-site disposal area was approximately 40 miles from the site. As a result, in-situ stabilization of the landslide, including a primary system of isolated tie-back anchor plates with strand anchors, and a secondary system of high strength steel mesh and intermediate anchors was selected for the ultimate design of the project to stabilize the landslide in place.For design purposes, geotechnical characterization of the slide area was accomplished through geological mapping, conventional borehole exploration and geophysics using multiple electrical resistivity. The paper discusses the design process utilized and the unique challenges faced one-third of the way through construction when discovery of a survey error required redesign of the entire landslide mass stabilization system using the prefabricated anchors that had already been delivered to the project.INTRODUCTIONTelluride Colorado is located at the toe of the Colorado Rocky Mountains on the western slope. The Telluride Regional Airport is located on Deep Creek Mesa about 5 miles west of the town of Telluride.The landslide is located at the southeast corner of the airport just below an abandoned portion of the quarry access road on a south facing slope. The quarry access road is located below the elevation of the runway and outside the elk fence that surrounds the air traffic area of the airport property. Since the reconstruction of the runway, the access road to the quarry and the construction access road for the reconstruction of the airport runway and safety area were rerouted to stable ground north of the previous access road location and off of the head scarp of the landslide."

Jan 1, 2015

By Minoru Sasabe, Mayurni Sorneno, Kazuhiro Goto

I) The Object of the Present Experiment. When the oxygen chemical potential in the gas phase is changed, the oxygen chemical potential in the liquid metal or in the liquid oxide phase will be subsequently changed. The object of the present experiment is to develop a method of measuring the change in the chemical potential of oxygen in liquid metals and in liquid oxides with respect to time, when the oxygen potential in the gas phase changes. II) The Experimental Method. The following types of the oxygen concentration cells with the solid electrolyte of Zr0z-CaO are used: KAZUHIRO GOTO, MemberAIME.MINORU SASABE,and MAYUMl SOMENO are Associate Professor, Research Associate, and Professor, respectively, Department of Metallurgical Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan. Manuscript submitted March 12, 1968, EMD. Igas phase liquid Ag or Pb ZrO2-CaO electrolyte!, The measured reversible electromotive force can be expressed by the next equation, provided that the transference number of the oxygen anion in the electrolyte is unity: E = RT/nF log (at electrode I)/P~ (at electrode 11) where is the electromotive force, R is the gas constant, T is absolute temperature, n is valence of oxygen anion, and Pq is the oxygen pressure at the electrodes. As shown in the previous work1 of the authors, the electromotive force is determined by the difference in the chemical potential of oxygen at the vicinity of the interfaces between the solid electrolyte and the electronic conductors used for the two electrodes. Fig. 1 shows the two kinds of the cell assembly used to measure the change of the chemical potential of oxygen in liquid metals and liquid oxides with respect to time. In both cases, the change of the oxygen pressure in the gas phase is measured by the independent oxygen concentration cell located above the

Jan 1, 1969

By W. B. Daly

THE sampling and estimating of, the orebodies in the mines of the Anaconda Copper Mining Co., at Butte, have been made a part of the work of the geological department. The wisdom of this assignment is apparent, considering the organization of that department, the nature of, its records, and the scope of its regular work. In the first place, the district is divided into units of two or three mines each and a geologist is assigned to each group. His trips to all the working places are frequent and he follows the mining operations closely. His notes are graphic and detailed. In the office, he posts his notes on the standard maps and sections and on special maps for correlation purposes. With the approval of the chief or assistant chief geologist, he recommends development work underground and watches its progress. This gives the geological department a precise knowledge of the character of each orebody. Sampling is done by one or two samplers at each mine working under a chief sampler stationed in the geological office. The chief sampler has access to all the office maps and is in frequent consultation with the geologists; his instructions to the samplers are issued with the approval of the chief or assistant chief geologist. Not only is it important that the geologic information be used to direct the sampling but the reports of the samplers and the records kept by their chief are useful to the geologist, who needs them in his work of I estimating ore reserves and deciding on recommendations for development work. The sampler, moreover, is at the mine every day and makes a daily report, which keeps the geologist in close touch with 'the progress of development work. The sampler is attached to the mine office and thus comes under the jurisdiction of the operating department. In fact, any special orders prepared by the chief sampler are submitted to the general superintendent, after approval by the geological department. The mine foreman may.

Jan 2, 1922

By F. A. Linforth, W. B. Daly

The sampling and estimating of the orebodies in the mines of the Anaconda Copper Mining Co., at Butte, have been made a part of the work of the geological department. The wisdom of this assignment is apparent, considering the organization of that department, the nature of its records, and the scope of its regular work. In the first place, the district is divided into units of two or three mines each and a geologist is assigned to each group. His trips to all the working places are frequent and he follows the mining operations closely. His notes are graphic and detailed. In the office, he posts his notes on the standard maps and sections and on special maps for correlation purposes. With the approval of the chief or assistant chief geologist, he recommends development work underground and watches its progress. This gives the geological department a precise knowledge of the character of each orebody. Sampling is done by one or two samplers at each mine working under a chief sampler stationed in the geological office. The chief sampler has access to all the office maps and is in frequent consultation with the geologists; his instructions to the samplers are issued with the approval of the chief or assistant chief geologist. Not only is it important that the geologic information be used to direct the sampling but the reports of the samplers and the records kept by their chief are useful to the geologist, who needs them in his work of estimating ore reserves and deciding on recommendations for development work. The sampler, moreover, is at the mine every day and makes a daily report, which keeps the geologist in close touch with the progress of development work. The sampler is attached to the mine office and thus comes under the jurisdiction of the operating department. In fact, any special orders prepared by the chief sampler are submitted to the general superintendent, after approval by the geological department. The mine foreman may

Jan 1, 1923

By F. A. Linforth, W. B. Daly

The sampling and estimating of the orebodies in the mines of the Anaconda Copper Mining Co., at Butte, have been made a part of the work of the geological department. The wisdom of this assignment is apparent, considering the organization of that department, the nature of its records, and the scope of its regular work. In the first place, the district is divided into units of two or three mines each and a geologist is assigned to each group. His trips to all the working places are frequent and he follows the mining operations closely. His notes are graphic and detailed. In the office, he posts his notes on the standard maps and sections and on special maps for correlation purposes. With the approval of the chief or assistant chief geologist, he recommends development work underground and watches its progress. This gives the geological department a precise knowledge of the character of each orebody. Sampling is done by one or two samplers at each mine working under a chief sampler stationed in the geological office. The chief sampler has access to all the office maps and is in frequent consultation with the geologists; his instructions to the samplers are issued with the approval of the chief or assistant chief geologist. Not only is it important that the geologic information be used to direct the sampling but the reports of the samplers and the records kept by their chief are useful to the geologist, who needs them in his work of estimating ore reserves and deciding on recommendations for development work. The sampler, moreover, is at the mine every day and makes a daily report, which keeps the geologist in close touch with the progress of development work. The sampler is attached to the mine office and thus comes under the jurisdiction of the operating department. In fact, any special orders prepared by the chief sampler are submitted to the general superintendent, after approval by the geological department. The mine foreman may

Jan 1, 1923

By Maurice Ewing, L. Don Leet

Assuming that wave velocities in seismic prospecting increase as a continuous linear function of the depth, the authors have derived formulas for computing, from two time-distance observations, the amount of velocity increase, depth of penetration and a graphical determination of the path of the vibrations, and have discussed the ground, reflected and refracted waves. The application of the formulas is illustrated numerically. Earlier Investigations Observations of the energy propagated from the center of an earthquake disturbance have been used to give information about the velocities and paths of elastic waves in the interior of the earth. One method of accomplishing this depends on the use of the times of transmission. Herglotz(7) § and Bateman(3) obtained a solution of the integral equation involved, which determines the velocity of propagation at any point as a function of the distance from the center of the earth, with no assumption as to the manner in which the velocity of the disturbance varies with depth below the earth's surface. The expressions on which the value of the time and the form of the ray of propagation depend contain an unintegrable definite integral, involving the velocity as an unknown function of the distance from the center of the earth. Wiechert and Zoppritz(15) obtained a manageable form for this function by assuming a law of variation which required a constant curvature form for the path within each of a succession of concentric spherical layers of the earth. C. G. Knott(9) worked out the problem for the first time by an absolutely rigorous method from the data of observation (Zoppritz-Turner tables), without making any assumptions as to the functional relationship connecting the speed of propagation and the distance from the earth's center. His method is a numerical solution of an integral equation, giving each velocity and the corresponding distance from the center of the earth in figures.

Jan 1, 1932

By C. A. Heiland

The new geophone described herein was developed by Charles H. Hull, instrumentmaker of the Colorado School of Mines, and the writer. The first geophone was invented during the war for the purpose of detecting enemy sapping or underground mining operations and for locating enemy artillery. It is based on the principle of the seismograph—a heavy lead mass suspended by one or two diaphragms, which are clamped to an air-tight case. When the ground vibrates during the transmission of sound waves, the case moves with it while the so-called steady mass remains practically motionless. Attached to the top of the casing is a hose leading to an earpiece shaped like a stethoscope. When the mass and the diaphragm move up and down in the case, the air is compressed and rarified in the inside; thus the vibration is communicated as sound wave to the human ear. The geophone combines a surprising simplicity of construction with an extreme sensitivity. Other listening instruments were developed during the war, adaptations of the telephone and the microphone—that is, instruments operating through the medium of electricity—of which the so-called seismicrophone, an adaptation of the carbon-granule microphone receiver, probably has found the greatest application, but such instruments apparently have not proved as useful as the simple geophone despite obvious advantages arising from the use of electricity. The carbon receivers were more subject to extraneous noises and to what is called "frying," and they did not offer the advantage possessed by the geophone; namely, the simultaneous use of two receivers, which makes it possible to determine the location of the source of sound. During the war, the U. S. Bureau of Mines made a study of the geophone and of the propagation of sound waves through rock. These studies have been continued, as the earlier results proved the possibility of using the geophone in various non-military ways, principally in mining, and the results of these studies have been published.'

Jan 1, 1932

By Arthur Notman

(San Francisco Meeting, September, 1915) SACRAMENTO HILL is a mass of granite porphyry intruded along a fault between Paleozoic sediments and pre-Cambrian schists in the Bisbee district, Cochise County, Arizona. The intrusion invaded both walls of the fault to a large extent, and the accompanying extensive mineralization of the Paleozoic limestones is the locus of the great high-grade copper orebodies of the Bisbee mines. Prior to 1909, although the presence of ore in the mass of the hill itself had long been suspected, systematic exploration had not been attempted. A few shallow pits on the surface here and there had disclosed some chalcocite with associated carbonates as stringers in a mass of strongly brecciated, silicified, and iron-stained porphyry. The workings in the surrounding limestones had penetrated the porphyry in a dozen or so places for some distance from the contact but had disclosed no ore. However, the rock had been largely altered to quartz and sericite and very thoroughly impregnated with pyrite and traces of the copper sulphides. A close geological study of the conditions, both surface and underground, strengthened these suspicions, and plans for prospecting the hill were made in 1909. Reference to the accompanying illustrations, Figs. 1 and 2, will give an idea of the general appearance of the surface. The mineralization is more intense in two main zones, one at the west end and the other at the east end of the hill. The outcrop of the hill is elliptical and approximately 3,000 ft. long by 1,400 ft. wide. The Sacramento shaft, which is the main hoisting shaft of the mine and situated at the east end of the hill, as shown by the accompanying map (Fig. 3), offered a convenient base for prospecting that end of the hill, while the workings from the Holbrook shaft offered a similar opportunity at the west end. The choice of level for the first work was determined by analogy with the most favorable depth for enrichment below surface observed in the other disseminated deposits of the Southwest.

Jan 8, 1915

By E. J. Horwood

The varying physical character and large extent of the Broken Hill lode necessarily involve the employment of a variety of underground methods. The lode had its origin in an extensive fault plane traversing metamorphosed schists conformably, as a rule, with their beds of stratification. The underground waters carrying minerals in solution deposited their contents. in the original cavities formed by the faulting action, and in the enlargements of these cavities due to dynamic forces brought to bear on the rocks, more especially on the hanging-wall side of the fault, This deposition was supplemented by metasomatic replacement of a portion of the original rock contents by the argentiferous sulphides of lead and zinc which form the staple products of the district. Although the orebody is practically continuous throughout the mines, its width varies greatly, ranging from a few feet to about 350 ft. The widest portions occur in conjunction with huge folds in the inclosing country rock, almost exclusively on the hanging-wall side. The ore it these folds pitches to the south in the southern half of the field, and to the north in the northern half; there are, however, undulations in these ore channels evidently due to compression of the rocks in the direction of the channels. In the earlier days, before the orebodies had been opened up: vertical cross-sections across these bulges in the hanging wall gave the lode the appearance of the "saddle formation," so well exemplified at Bendigo in Victoria; but subsequent development of the ore channels ha; long since proved that the formations in the two districts are entirely different. The depth reached by the zone of complete oxidation of the sulphide, varies from about 250 to 550 ft. from the original outcrop while partial oxidation extends in places below the 1,000-ft. level. The result of oxidizing influences has been the production of ore of every grade of cohesiveness, from that of dry sand to that of hard compact rock.

Jan 1, 1916

By Arthur Notman

SacRamento Hill is a mass of granite porphyry intruded along a fault between Paleozoic sediments and pre-Cambrian schists in the Bisbee district, Cochise County, Arizona. The intrusion invaded both walls of the fault to a large extent, and the accompanying extensive mineralization of the Paleozoic limestones is the locus of the great high-grade copper orebodies of the Bisbee mines. Prior to 1909, although the presence of ore in the masa of the hill itself had long been suspected, systematic exploration had not been attempted. A few shallow pits on the surface here and there had disclosed some chal-cocite with associated carbonates as stringers in a mass of strongly brccciated, silicified, and iron-stained porphyry. The workings in the surrounding limestones had penetrated the porphyry in a dozen or SO places for some distance from the contact but had disclosed no ore. However, the rock had been largely altered to quartz and sericite and very thoroughly impregnated with pyrite and traces of the copper sulphides. A close geological study of the conditions, both surface and underground, strengthened these suspicions, and plans for prospecting the hill were made in 1909. Reference to the accompanying illustrations, Figs. 1 and 2, will give an idea of the general appearance of the surface. The mineralization is more intense in two main zones, one at the west end and the other at the east end of the hill. The outcrop of the hill is elliptical and approximately 3,000 ft. long by 1,400 ft. wide. The Sacramento shaft, which is the main hoisting shaft of the mine and situated at the east end of the hill, as shown by the accompanying map (Fig. 3), offered a convenient base for prospecting that end of the hill, while the workings from the Holbrook shaft offered a similar opportunity at the west end. The choice of level for the first work was determined by analogy with the most favorable depth for enrichment below surface obscrved in the other disseminated deposits of the Southwest.

Jan 1, 1916

By A. C. Bulnes

This paper applies the methods of statistical analysis to the interpretation of core analysis data of dolomitic limestone from the San Andres formation at Wasson and the Clearfork formation at Fullerton. Probability relationships are shown to connect the porosity and the permeability and the porosity and the fluid saturation. For example, the porosity-permeability relationship expresses the probability that a sample of porosity,f, will or will not be permeable. The over-all porosity frequency distribution of the reservoir together with the frequency curves of permeability (one for each class interval of porosity) provide a precise basis for computing the weighted average productive porosity of the reservoir for any assigned value of the minimum productive permeability. The probability that the permeability of a core specimen from Fullerton will exceed a given value appears to be dependent on the percentage porosity of the specimen, its void structure type (i.e., porosity in the qualitative sense), and the given value of the permeability. If continuous profiles of void structure type and porosity are available together with the appropriate porosity-probability of permability plots, the nes pay thickness may be estimated. The Invasion Index of a well is defined in terms of the porosity and permeability data. This index is suggested as a basis for comparing wells as regards their suitability as fluid-injection wells. Three problems of importance in the exploitation of limestone reservoirs may be stated as follows: 1. The determination of the productive porosity of the reservoir. The productive porosity is defined as f = fPVP/V [II in which Vp, is the volume of the reservoir that is sufficiently permeable to oil to give up an appreciable fraction of its original oil in place during the economic life of the reservoir; fp, is the arithmetic mean porosity of the permeable volume v*, and V is the total volume of the reservoir. 2. The determination of the number of feet of oil-bearing porous rock that will produce at a commercial rate into the well bore; i.e., the net pay thickness. 3. The choice of fluid-injection wells in a secondary recovery program. The ultimate recovery of the reservoir is proportiona1 to the productive porosity. The productive capacity of the well is proportional to the net pay thickness. The principal purpose of this paper is to show that the methods of statistical analysis when applied to core analysis data of dolomitic limestones offer a useful approach to the solution of these three problems, as well as others of importance in reservoir engineering. The use of these methods was suggested by the work of Jan Law.1

Jan 1, 1946

By A. C. Bulnes

This paper applies the methods of statistical analysis to the interpretation of core analysis data of dolomitic limestone from the San Andres formation at Wasson and the Clearfork formation at Fullerton. Probability relationships are shown to connect the porosity and the permeability and the porosity and the fluid saturation. For example, the porosity-permeability relationship expresses the probability that a sample of porosity,f, will or will not be permeable. The over-all porosity frequency distribution of the reservoir together with the frequency curves of permeability (one for each class interval of porosity) provide a precise basis for computing the weighted average productive porosity of the reservoir for any assigned value of the minimum productive permeability. The probability that the permeability of a core specimen from Fullerton will exceed a given value appears to be dependent on the percentage porosity of the specimen, its void structure type (i.e., porosity in the qualitative sense), and the given value of the permeability. If continuous profiles of void structure type and porosity are available together with the appropriate porosity-probability of permability plots, the nes pay thickness may be estimated. The Invasion Index of a well is defined in terms of the porosity and permeability data. This index is suggested as a basis for comparing wells as regards their suitability as fluid-injection wells. Three problems of importance in the exploitation of limestone reservoirs may be stated as follows: 1. The determination of the productive porosity of the reservoir. The productive porosity is defined as f = fPVP/V [II in which Vp, is the volume of the reservoir that is sufficiently permeable to oil to give up an appreciable fraction of its original oil in place during the economic life of the reservoir; fp, is the arithmetic mean porosity of the permeable volume v*, and V is the total volume of the reservoir. 2. The determination of the number of feet of oil-bearing porous rock that will produce at a commercial rate into the well bore; i.e., the net pay thickness. 3. The choice of fluid-injection wells in a secondary recovery program. The ultimate recovery of the reservoir is proportiona1 to the productive porosity. The productive capacity of the well is proportional to the net pay thickness. The principal purpose of this paper is to show that the methods of statistical analysis when applied to core analysis data of dolomitic limestones offer a useful approach to the solution of these three problems, as well as others of importance in reservoir engineering. The use of these methods was suggested by the work of Jan Law.1

Jan 1, 1946