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By H. C. Miller

The energy stored in the compressed natural gas absorbed in or otherwise associated with the oil in reservoir sands is usually the most important factor in oil recovery. It is recognized that hydrostatic pressure and gravity may aid materially in the drainage of oil, but in the early life of the majority of fields the principal source of propulsive energy is the expansive force of the gas associated with the oil. Since gas is admittedly the most important factor in the production of oil, its control so as to produce the maximum amount of oil with the minimum amount of gas will be reflected in increased oil recovery from reservoir sands. Controlling the gas means regulating its expansion so that the velocity of flow of oil through the channels in the reservoir sands is neither so great that frictional resistance becomes excessive nor so slow that the gas, because it can travel more rapidly than oil through the irregular passageways in the sands, will by-pass and reach the well without. doing useful work in bringing oil from the sands. Oil and gas flow from the reservoir sands to the well because of differences in pressure. The rate of flow is dependent upon the differential pressures existing in the sands and in the well. By altering the amount of back-pressure maintained on the well this differential pressure can be regulated and changed from a maximum (well flowing "wide open") to a minimum when there will be no flow. Oil and gas flow through the irregular channels in reservoir sands at different rates mainly because of the fact that one is a liquid and the other a gas. Therefore, because oil and gas have different characteristics of flow, application of back-pressure, changes the rates of flow with relation to one another so that wide variations in gas-oil ratios are possible. Obviously, the formation gas energy will be utilized most efficiently when a unit of gas delivers the maximum amount of oil to the well. Determination of Necessary Back-pressure The amount of back-pressure that should be maintained against the producing sand in order that the minimum amount of gas will be produced with each barrel of oil can be determined only by actual field tests made

Jan 1, 1929

By W. R. Jones

composition, he cannot reasonably asl; the manufacturer to guarantee that this composition shall give certain physical results. W. R. Jones, Pittsburgh, Pa. : The question that naturally occlun to me is this: Has Dr. Dudley in his inveatigtrtions been aiming to prove a theory, or has he been guided by an earnest desire to discover what are the proper elements in the composition of a good-wearing steel rail ? Unfortunately, for correct chemical information, he has omitted in his analgw two very importnat elements,—sulpbur and copper. Now, before we will even begin to admit the correctnets of Dr. Dudley's conclusions and the formula he prescribes, we will at the start question the propriety of any chenlist or scientist prescribing a formula for making steel when he has iguared such important ele ments as sulphur aud copper. I, for one, will not accept any such formula. Are we sure, or is Dr. Daclley sure, that the chemical analyseq embodied in his paper are correct? This may seem a presumptuous queetion, yet, with my experience with chenlists, I naturally doubt the correctness of the analyse8, and, before I will accept them as correct, I will ask that comparative tests of phosphorous and man ganese be made by the Pennsylvania Railroad chemists and the chemists of the leading steel-works in the country. Let us first verify the correctness of the analyses before we consider the con clusions. I can enumerate a great number of instances in which chemists have differed very widely in their determinations of phos phorus and manganese. A prominent iron fitam made a contract with the Edgar Thomson Steel Company to deliver pig metal guar anteed to be between 0.07 and 0.08 phosphorus; an analysis by our chemist resulted in phosphorus 0.148 and 0.152,—a rather startling difference! Again, a sample bar of steel, in which our chemist reported phosphorus 0.11, was tested by a chemist of au other Bessemer works, ana his determinations were phosphorus between 0.07 and 0.08: A leading engineering establishmeut of Pittsbdrgh bought iron claimed by a chemical analysis to contain 0.08 phosphorus; our Mr. Ford found phosphorus 0.145. A chem ist connected with an open-hearth works reported manganese in a piece of steel, 1.14; in a second determination from the same piece of steel, by the same chemist, manganese was reported 0.43. The chemist was kept in ignorauce of the fact that both samples were from the saw piece of steel. Two dctermiuations for manganese

Jan 1, 1881

By Edgar R. Kendall

A knowledge of the fundamental principles of locating, sampling, testing and evaluating materials is essential in prospecting for mineral aggregates. In this discussion, mineral aggregates will be considered sand, gravel, crushed stone and slag that are used as materials of construction. The quantity of mineral aggregates produced in the United States during the year 1935 for such purposes was roughly 165,000,000 tons, about 60 per cent of which was sand and gravel, 37 per cent crushed stone and 3 per cent crushed slag. The total value of this material was approximately $100,000,000. It is apparent therefore that the prospecting for suitable mineral aggregates is of considerable economic importance. In prospecting for mineral aggregates, the methods employed are the same whether the organization is large or small. In the large organization there may be available geologists for locating sources of supply, a land acquisition department to arrange for the necessary options or permits, engineers to do the sampling, a laboratory for testing, and a board of consulting materials engineers to make the final selection. Even small organizations must follow the same general procedure, though the responsibility for the selection of aggregates may rest with one man, who may or may not be an engineer, but who must depend entirely upon his own judgment. Locating the Supply The initial step in prospecting for mineral aggregates is the locating of suitable, adequate and economic sources of supply for the project in mind. Commercial plants in the vicinity should be investigated and a survey made of the existing structures that have been built of aggregates from these sources. If the structures are rather old and show no signs of deterioration, it is fairly good evidence that the aggregate is satisfactory. If materials of the proper quality can be obtained from commercial sources in sufficient quantity, and delivered to the job economically, it

Jan 1, 1942

During the war period of quicksilver activity there were a number of departures from what may be termed the classical quicksilver metallurgy. Attempts were made to beneficiate low-grade ores by gravity concentration and flotation; mechanical furnaces began to replace the Scott furnace and the vertical coarse-ore furnaces, and condensers of sewer tile and redwood tanks were used in place of the older brick and stone condensing chambers. Other developments that have occurred during the current period of quicksilver activity are mainly in the nature of improvement and further refinement of those started during the war period. Each period of quicksilver activity has been accompanied by the proposal of various new processes, including wet methods for the treatment of quicksilver ores and innovations in furnaces, retorts and condenser equipment. As far as the author knows, nothing of economic significance in the way of "new processes" has been developed. There is in fact no real need for any essentially new process for the treatment of quicksilver ores; the direct furnace treatment is simple and inexpensive. Moreover, with rare exceptions, the quicksilver industry has no complex or refractory ore problems corresponding to those which are receiving more and more attention from metallurgists in other branches of the nonferrous field. Untler these conditions improvements in quicksilver metallurgy must be looked for through the adaptation of current developments in engineering and metallurgy generally to the particular needs of quicksilver practice rather than through the invention of new processes. Preliminary Treatment of Quicksilver Ores At Sulphur Bank, in the treatment of old dump material left by the early operators, wet screening is being used as a preliminary step in concentration ahead of flotation. Power shovels and trucks are used to deliver some 400 tons of ore per day to the lower terminal of a hoist, which in turn discharges the material at the top of the screening plant. Wet screening is carried on in two stages. Depending on the character of the material, 1-in. or 2-in. punched screens are used on the first trommel.

Jan 1, 1930

By Edgar R. Kendall

A knowledge of the fundamental principles of locating, sampling, testing and evaluating materials is essential in prospecting for mineral aggregates. In this discussion, mineral aggregates will be considered sand, gravel, crushed stone and slag that are used as materials of construction. The quantity of mineral aggregates produced in the United States during the year 1935 for such purposes was roughly 165,000,000 tons, about 60 per cent of which was sand and gravel, 37 per cent crushed stone and 3 per cent crushed slag. The total value of this material was approximately $100,000,000. It is apparent therefore that the prospecting for suitable mineral aggregates is of considerable economic importance. In prospecting for mineral aggregates, the methods employed are the same whether the organization is large or small. In the large organization there may be available geologists for locating sources of supply, a land acquisition department to arrange for the necessary options or permits, engineers to do the sampling, a laboratory for testing, and a board of consulting materials engineers to make the final selection. Even small organizations must follow the same general procedure, though the responsibility for the selection of aggregates may rest with one man, who may or may not be an engineer, but who must depend entirely upon his own judgment. Locating the Supply The initial step in prospecting for mineral aggregates is the locating of suitable, adequate and economic sources of supply for the project in mind. Commercial plants in the vicinity should be investigated and a survey made of the existing structures that have been built of aggregates from these sources. If the structures are rather old and show no signs of deterioration, it is fairly good evidence that the aggregate is satisfactory. If materials of the proper quality can be obtained from commercial sources in sufficient quantity, and delivered to the job economically, it

Jan 1, 1942

By A. W. Allen

The technological study of the treatment of gold and silver ores has been largely responsible for the phenomenal strides which have marked the progress in this branch of metallurgy during recent years. In no other application of science to industry is system more imperative at every stage; correct formulation of result is only second in importance to efficiency of operation. Progress in method, on the other hand, is mainly due to individua1 initiative aided by the work of technical journals and metallurgical societies. There still remains a field for profitable discussion, and it is my intention to deal with some inconsistencies of expression common to a number of writers on the subject; and also to draw attention to the false impressions created by a statement which may, possibly, be only unintentionally misleading. I also take the opportunity of tracing the source of both metallurgical and economic result; and would question the desirability of the methods usually employed in arriving at a final statement. In the first place, I wish to deal with the question of extraction. This term may mean anything or nothing, and it is often used to mislead. In a report of a mining engineer as to the result of operations subsequent to the remodeling of a treatment plant prominence was given to the statement that the extraction had amounted to 91 per cent. On examination it was found that only a small percentage of the so-called extraction was calculated on actual bullion return, a proportion being figured from the gold left in the zinc boxes, and not recovered. In addition to this, a proportion of the extraction was said to be due to gold in concentrate. As there was no conrcentrating apparatus on the property and as concentration did not form a part of the scheme of treatment the matter was investigated, with the result that the concentrate, of lower gold content that the original ore, was found to be the result of an inegcient pumping system which failed to provide for the whole of the battery product delivered to it. The balance was stacked and, although itself of no marketable value, the gold content was allowed to form a basis of extraction figures. The illustration may be extreme, but it will serve to show to what lengths an engineer may go in the mutilation of the most vital term in metallurgical technology.

Jan 1, 1915

By Henry Louis

The work performed by the Royal Commission on Mining Subsidence is likely to prove of permancnt value, less perhaps for the conclusions it has reached and for the recommendations it has based upon these than for the admirable exposition which it affords of the law concerning mining subsidence and of the legal status of the person who has suffered damage by reason of such subsidence, as also of him whose working has caused the damage. The Commission was appointed by Royal Warrant in the middle of 1925 and delivered its final report in the middle of 1927. The terms of reference to the Commission were as follows: "To consider the operation of the law relating to the support of the surface of the land, and of buildings or works on or under the surface, by underlying or adjacent minerals; to enquire into the extent and gravity of the damage caused by subsidence owing to the extraction of minerals and the incidence of the resulting liability; and to report what steps should be taken, by legislation or otherwise, to remedy, equitably to all persons concerned, any defects or hardships that may be found to arise in existing conditions." Report on the Doncaster Area The Commission submitted an interim report at the end of 1925, which referred solely to one area, usually spoken of as the Doncaster area, and recommended that a Commission of a more technical character be appointed to investigate this particular case. This recommendation was acted upon, and the Commission thus appointed reported early in 1928. Here it is necessary only to indicate the nature of the special problem that had to be solved, the proposed solution being mainly of local interest. The Doncaster area consists of about 330 sq. miles of low-lying land in the southeasterly portion of Yorkshire and adjoining parts of Lincolnshire and Nottinghamshire. No less than 78 per cent, of this land lies below the 25-ft. contour line, and a good deal is even below high-water level. It includes a large tract of land known as Hatfield Chase, swampy ground which has always been a source of trouble on that account, so much so that in 1626 a Dutchman, Cornelius Vermuyden, was called in by King Charles I to devise and execute schemes of drainage for its reclamation. The entire Doncaster area is

Jan 1, 1930

By R. E. Hathaway

INTRODUCTION For a number of reasons, the mineral processing industry has been slow to adopt significant automation of its processes. Most ore grinding operations can be operated manually so the pressure for automation to run the process has not been there. Furthermore, many plants had proven over years of operation that manual operation would produce a profit, so why automate? Until recently, the instrumentation necessary for automation of the grinding process was not available. All this has now changed, however. Increasing costs for labor, fuel, power, grinding media, reagants, and capital equipment have not been matched by the market price of the finished product. This cost-price squeeze has made it mandatory to reduce operating costs and improve the efficiency of the process to remain profitable. A number of other factors have added to the direct operating cost to make the problem even worse. These include environmental pressures to conserve natural resources and reduce smelter stack emissions; increased competition--especially from developing countries, varying economic conditions, stockpiling, governmental controls, and to top it all off, lower grade ore bodies. Although many of these other influences are good overall, they take their toll in cost per ton of delivered product. Fortunately, many operators are finding the solution to the cost-price squeeze in instrumentation and process control. Automated processes yield tighter spec. products, require less operating labor, produce more product from a given plant, and reduce unit cost by increasing process efficiency. The plant manager has a "handle" on the plant through process control so that he can change operating modes as economics dictate by changing the set point of some process controllers. He can even respond to economic conditions by switching control strategies from one that maximizes production to one that maximizes recovery, or minimizes unit cost, etc. This has all been made possible by the advent of on-line analytical instruments and practical process control computers. On-stream particle size (1), x-ray, and silica analyzers are now available and in use in many plants. Digital computer hardware and software has become practical so operators can use it without trying to become computer experts. This chapter describes the approach toward design and implementation of automatic grinding circuit control that has proven to be the most cost effective, based upon results from a number of

Jan 1, 1982

By Laurence Delisle, Arron Finger

The alloys formed by the addition of nickel to iron by conventional metallurgical procedures show physical properties that differ widely from those of the individual metals. The effect of alloying on the mechanical properties is most pronounced in alloys containing between 15 and 25 per cent nickel. The tensile strength of an alloy containing, for example, 20 per cent nickel and 80 per cent iron (with 0.06 per cent carbon), in an annealed condition, is above 150,000 lb. per sq. in.$ owing to a martensitic type of transformation, as compared with about 50,000 lb. per sq. in. for pure iron in the same condition. The object of this work was to determine whether the same beneficial alloying effect coulcl be obtained in alloys of iron and nickel prepared by powder metallurgy technique. Procedure Bars and pellets for tension and compression tests, respectively, were made. Two groups of specimens were prepared: (I) by cold-pressing the powders and sintering; (2) by cold-pressing the powders, sintering, repressing and resintering. Raw Materials Nickel powder supplied by Metals Disintegrating Co., marked MD-151, was used. A typical analysis of this powder was as follows: sulphur, 0.040 per cent; copper, 0.18; iron, 0.23; manganese, 0.002; magnesium, o.oo15; lead, 0.035; tin> 0.025; silicon, 0.08; chromium, 0.008. Electrolytic iron powder supplied by Plastic Metals Inc. was used. A repre-sentative chemical analysis for impurities other than gases, supplied by the vendor, gave the following results: carbon, 0.005 per cent; manganese, 0.002; silicon, 0.003; phosphorus, 0.001; sulphur, 0.004; nickel, 0.008. The fractions from these powders passing a 325-mesh sieve were reduced in hydrogen at 600°C. for one hour, to clean the sur-faces of the particles. The reduced pow-ders, slightly caked, were ground in a mortar and screened again through a 325-mesh sieve. Mixing The proper proportions of the powders were mixed overnight on rolls, in glass jars fitted with iron-wire baffles to break aggregates of particles that might form. Pressing All specimens were compacted on hy-draulic presses. The pellets were com-pacted in a cylindrical die, 34-in. diameter. The ratio of thickness to the diameter of the pellets was maintained as nearly as possible at 0.9, as specified for standard short compression pieces. The tensile bars were made by compacting 30 grams of powder. Their shape is shown in Fig. I. The compacting pressures for the pellets and the tensile bars were:

Jan 1, 1946

By Arron Finger, Laurence Delisle

The alloys formed by the addition of nickel to iron by conventional metallurgical procedures show physical properties that differ widely from those of the individual metals. The effect of alloying on the mechanical properties is most pronounced in alloys containing between 15 and 25 per cent nickel. The tensile strength of an alloy containing, for example, 20 per cent nickel and 80 per cent iron (with 0.06 per cent carbon), in an annealed condition, is above 150,000 lb. per sq. in.$ owing to a martensitic type of transformation, as compared with about 50,000 lb. per sq. in. for pure iron in the same condition. The object of this work was to determine whether the same beneficial alloying effect coulcl be obtained in alloys of iron and nickel prepared by powder metallurgy technique. Procedure Bars and pellets for tension and compression tests, respectively, were made. Two groups of specimens were prepared: (I) by cold-pressing the powders and sintering; (2) by cold-pressing the powders, sintering, repressing and resintering. Raw Materials Nickel powder supplied by Metals Disintegrating Co., marked MD-151, was used. A typical analysis of this powder was as follows: sulphur, 0.040 per cent; copper, 0.18; iron, 0.23; manganese, 0.002; magnesium, o.oo15; lead, 0.035; tin> 0.025; silicon, 0.08; chromium, 0.008. Electrolytic iron powder supplied by Plastic Metals Inc. was used. A repre-sentative chemical analysis for impurities other than gases, supplied by the vendor, gave the following results: carbon, 0.005 per cent; manganese, 0.002; silicon, 0.003; phosphorus, 0.001; sulphur, 0.004; nickel, 0.008. The fractions from these powders passing a 325-mesh sieve were reduced in hydrogen at 600°C. for one hour, to clean the sur-faces of the particles. The reduced pow-ders, slightly caked, were ground in a mortar and screened again through a 325-mesh sieve. Mixing The proper proportions of the powders were mixed overnight on rolls, in glass jars fitted with iron-wire baffles to break aggregates of particles that might form. Pressing All specimens were compacted on hy-draulic presses. The pellets were com-pacted in a cylindrical die, 34-in. diameter. The ratio of thickness to the diameter of the pellets was maintained as nearly as possible at 0.9, as specified for standard short compression pieces. The tensile bars were made by compacting 30 grams of powder. Their shape is shown in Fig. I. The compacting pressures for the pellets and the tensile bars were:

Jan 1, 1946

Granduc lies near the Alaskan border in British Columbia, about 600 miles (960 km) north of Vancouver. Prospecting in the area must take place in the short summer months of fog and rain because the winter is bitter cold, with snowfall up to 960 inches (24.4 m) accompanied by avalanches. Despite these difficulties, the mineral ized area was discovered in the 1920's. By 1956, Newmont Mining Corporation had developed mineable ore reserves estimated at 32,500,000 tons of 1.93% copper. Newmont and ASARCO, in a joint venture, then began development of the ore body, which was partially covered by glaciers. It was apparent a concentrator could not be built at the mine site where overland access was impossible due to the weather conditions and the terrain. Years of engineering studies of all possible access routes finally dictated the driving of an 11 mi long (17.6 km) tunnel passing under three glaciers and three mountain ranges to the nearest feasible concentrator site at Tide Lake. Even then, a mountain road subject to an average snowfall of 800 in. (20. 3 m) had to be built 32 mi (51 krn) from the concentrator through Alaska to Stewart, British Columbia, the nearest port. At Stewart, which is located at the head of a fjord 120 mi (192 krn) from the Pacific Odean, a fully equipped marine terminal was built. The tunnel, the lifeline between mine and mill, was to be driven from both ends; however, in 1965, an avalanche occurred at the Leduc portal, killing 26 crew members and wrecking much of the camp. The tunnel was then driven from one heading adjacent to the concentrator site at Tide Lake, a distance of 53,744 ft (16,381 m) to a point under the ore body. The remote location, type of terrain, and bad weather made supply of crews, equipment, and construction materials difficult; but in spite of these extremely adverse conditions, the tunnel crews set many world records. Mineralization throughout the ore zone is generally uniform in grade and composition and is primarily chalcopyrite and pyrrhotite associated with pyrite. Mining is mainly by sublevel caving. After blasting, rubber-tired load-and-haul equipment moves from level to level by means of an internal connecting ramp system on a 15% slope. At the gathering haulage level, 15-ton bottom-dump cars deliver the ore to a 600-ton pocket equipped with a Hudson "Rock-Flo" dump. The bottom of the ore pocket forms the feed chute to the primary

Jan 1, 1978

By Barnabus Bryan

THE normal statistics of supply and demand of petroleum and its products have little more than local influence on the market movements of oil securities. The two major reasons for this condition might be called the technique of production and the technique of refining. The speed of improvement in each and the complete lack of control of their, inter-relation have resulted in overproduction of both crude oil and gasoline in the face of immense in-crease in demand. The trouble with oil securities has been that of the mushroom radio companies, where too frequent changes have killed the possibility of profits. It is a case of too much efficiency. During the past ten years there has been continual talk of wasting reserves of crude oil. This has been based on "present methods of production." Yet the methods of ten years ago in the oil industry are as antiquated today as the kerosene lamp.. The fear of famine has transformed the industry. The refiner, through the cracking process, has doubled the gaso-line output from a barrel of crude oil, thus doubling reserves and changing a current undersupply into oversupply. When the automobile driver desires he can again double reserves and transform want into abundance by demanding an automobile which will deliver twice as many miles per gallon of gasoline. Entirely apart from refining and in complete dis-regard for its needs, the oil producer has forged ahead at a pace too rapid for his own good. The science of geology has developed with experience and' lavish expenditure into a constant danger to profits in the production of oil. Two and one-half per ;cent of the producing wells in the United States are yielding one-half of the oil, while their flush production is used as an excuse to force down the price of crude oil until 200,000 wells must be abandoned or produce at a loss. The fabulous yield of the new high-pres-sure fields enables the fortunate owners to make a profit regardless of the price of oil. Such a condi-tion is unhealthy from the standpoint of oil itself and as a national policy. It is manifestly absurd to suppose that such a condition can endure for a gen-eration. There will come a day when the sequence of discovery will be temporarily broken, and at that time the consumer will be forced to pay heavy interest on the foolhardy policy of today.

Jan 6, 1927

By A. P. Cohen, D. W. Fuerstenau

Methods of accounting for the feed size in analyzing the size distribution shift during comminution have been discussed in a number of papers.1,2,3 Based on experiments which charles2 performed with single Pyrex specimens, Schuhmann4 pointed out that the size modulus of an assembly of particles should be determined by the energy expended per unit volume (or mass), independent of the size of particle being comminuted. In this same paper, Schuhmann derived the Charles energy-size reduction relationship by considering that complex comminution operations can be considered to be the summation of many individual comminution events, each of which must be governed by Were 6wi is the mass of a particle receiving the impact, 6Ei is the energy delivered to the particle, ki is the size modulus of the product resulting from the impact, a is the distribution modulus of the assembly of particles, and A is a constant. Recent experiments on the compression loading of Pyrex spheres ranging in size from 1/8 to l-in. diam have shown that the size modulus of the fragments is determined by the strain energy at fracture per unit mass, independent of sphere diameter.' The objective of the present investigation has been to determine experimentally whether the size distribution of the product from such a complex comminution process as rod milling is determined only by the energy expended per unit mass independent of feed size. Samples of each Tyler sieve fraction ranging from 4x6 to 48x65 mesh were prepared from crushed Brazilian quartz crystals. One kilogram of each fraction was ground at 60 pct solids in an 8x9 1/4-in. mill containing 17.5 kg of rods (26 rods, 5/8-in.; 10 rods, 3/4-in.; and 5 rods, 7/8-in. diam). In each test, the mill was run at 77 rpm for 15 min. Size distributions were determined by a wet-dry sieving technique. Table I presents the size distribution of the products obtained by grinding each of the size fractions. Because the size distributions are so nearly alike, they are plotted in Fig. 1 by shifting each size distribution for the different feed sizes one screen fraction to the right. Thus, the lowest point in each size distribution represents 400 mesh and each of the other sieve sizes must be shifted accordingly. A single regression line was calculated by combining the data for the six tests, excluding the coarsest feed and the two finest feed fractions. 6 This regression line, which is given by (Y \0.88 where y is the cumulative percentage of material

Jan 1, 1962

By Robert W. Elayer

In August 1973, Fluor Utah, Inc. was awarded a contract by the Office of Coal Research (now part of the Energy Research and Development Administration), Department of the Interior, for the examination of the unique problems of large-scale surface coal mining to supply coal conversion complexes. The project consists of two phases: (I) data base development and organization and the formulation of a mathematical computer modeling system for surface mining; and (II) computer manipulation of the data base in accordance with the model to formulate several typical preliminary mine and preparation plant designs. Phase I is scheduled for completion by the end of July 1975 and Phase II is scheduled to be complete by the end of January 1977. This paper briefly discusses the effort for only one aspect of this project-the foundation for geologic modeling developed in Phase I. The Phase I task of geologic modeling can be broken down into two subtasks: (1) identify areas containing sufficient resources of surface-minable coal to support at least one large-scale mining complex, and (2) characterize the coal deposits in these areas for computer storage and retrieval. Identification of Resource Regions The basic production design criteria for large-scale surface mining, as stated in the contract, is the production of 75,000 tpd, or more, of bituminous coal. Based on a constant total Btu delivered to the preparation plant, daily production requirements for the different coals are as follows: Bituminous Coal 75,000 tons Subbituminous Coal 99,500 tons Lignite 143,500 tons Although surface mining on this scale is presently non-existent, it is deemed that future operations, in order to meet the increased energy demands, will have to look forward to much larger scale mining complexes. These tonnage requirements are meant to be used only for the delineation of general areas suitable for large-scale surface mining, termed "Strippable Coal Resource Regions." They were determined largely from the latest complete detailed coal resource estimates of the U.S. Bureau of Mines. Nine strippable coal resource regions, containing over 100 billion tons of strippable coal resources, were identified [(see Fig. 1)]. The delineation of these regions was based entirely upon estimates of surface-minable coal resources and the production design criteria for large-scale surface mining. If surface-mined coal was combined with underground production, or if smaller production rates were specified, then other areas which were omitted here would be included in the regions. Changing the outline of the regions, however, would not add any new mining situations to be studied in Phase II. Characterization of Coal Deposits The second subtask involved the general characterization of the coal deposits contained in the strippable coal resource regions. The geological information gathered

Jan 1, 1976

By N. J. Sather

A detailed description is given of Bunker Hill's concentration process employed at the company's lead-zinc property in the Coeur d'Alene district, Idaho. The plant is equipped to process 3000 tpd of Pb-Zn ore. The history of the Bunker Hill mine dates back to Aug. 26, 1885, when Noah S. Kellogg found the outcrop of the Bunker Hill orebody on the hillside of Milo Gulch above the present town of Wardner, Idaho. A small concentrator was erected in 1886, and before the railroad came, the mine output was transported by mule teams to the head of navigation on Coeur d'Alene Lake. After ten years of production, an interest was purchased in the Tacoma smelter at Tacoma, Wash., to which the entire output was shipped. In 1916 and 1917, a modern lead smelting plant and refinery was erected, and a modern electrolytic zinc reduction plant was built in 1927-1928 by the Sullivan Mining Co. which was 50 pct owned (and now totally owned) by the Bunker Hill Co. The first concentrator, a 100-tpd capacity plant, was built in 1886 near the Reed Tunnel in Wardner. The treatment consisted simply of crushing ore to 2 in. and then to 1/2 in. through rolls in closed circuit with a bucket elevator and trommel screen. The undersize was further sized in trommels to 10 mm and 3 mm. Oversize from the latter was treated in Hartz jigs. The 3 mm undersize was classified in crude hydraulic classifiers furnishing sands to sand jigs, the overflow being dewatered in a long V tank which supplied sands to a Cornish buddle and to Frue vanners. The concentrates were of excellent grade, old records showing assays of 69 pct lead and 29 oz. of silver per ton. Tailings were high inasmuch as the provision for treating the slimes was inadequate. Since the erection of the first mill, the Bunker Hill plant has gone through many changes and improvements. In succeeding years, the flowsheet was enlarged somewhat with Huntington and Chilean mills, vanners, tables, ball mills, and flotation cells being progressively added. In the transition period to the present day practice, the object was not only to improve the equipment for better mechanical performance, but to add new equipment whenever practicable so as to improve both grade and recovery of the product at a lower cost. For the modern plant and flow-sheet, see Figs. 1 and 2. The history of flotation at Bunker Hill dates back to 1913 when experimental work was done in a cell in which the pulp was circulated through a centrifugal pump set outside the cell and discharged against a baffle in the cell. The cell was built with a spitzkasten, and the quiet zone in the latter tended to let the froth break down before it got to the overflow weir. To remedy this situation, a belt drag with light metal flights was arranged for drawing off the froth over a ramp in each cell. Recovery of lead was not as high as present day practice, but was so much better than the vanners that the cells were multiplied gradually to eight cell units. The mill men called them mud hens. Flow between the cells was controlled by a weir, which determined the pulp level in each cell. These early machines were called Bunker Hill machines. The tailings were later treated in pneumatic scavenger flotation machines in a series, producing concentrates for retreatment in the Bunker Hill cleaners as well as the final tailings. This system of flotation served with minor changes until the Fahrenwald machine was developed at Bunker Hill during the period from 1921 to 1925. In 1925, the Fahrenwald flotation machine gradually replaced the Bunker Hill machine, although the Hearing pneumatic scavengers for retreatment of the tailings from the Fahrenwald machines were retained in the lead section until 1928. The use of the Hearing pneumatic machine for cleaning the rougher concentrates was begun in 1924. In 1941, plans were made for remodeling and modernizing the concentrator, the goal being a modern concentrator employing the latest equipment and milling practices. The old wooden building was to be replaced by a steel and concrete structure. Shortly after preliminary work got under way, the United States entered World War II and the demands for metals increased. To meet this requirement, the management decided to increase the capacity of the concentrator to 1800 tpd. This was accomplished in record time by the construction and operation of a sink-float plant. Installation of this plant was the first step in the general plan for modernization. In 1947 the concentrator (including the sink-float plant) was enlarged to handle 3000 tpd. Milling operations today are at the rate of 2300 tpd, five days per week. During 1959, 453,000 tons of ore was beneficiated. The Bunker Hill concentrator is in three sections: the crushing plant, a 3000-ton capacity storage bin, and the concentrator building. The crushing plant is of wood design with a gunnite coating on the exterior.

Jan 1, 1961

By E. B. Brauer, B. F. Pennington, E. W. Hough, G. L. Stegemeier

Interfacial tension divided by the difference in density between the liquid and the vapor phases was determined experimentally by the pendant drop method on several isotherms in the two phase region below the critical point for the methane-normal decane system. The density difference data of Sage and Lacey was used in the calculation of interfacial tension. Both interfacial tension and and interfacial tension divided by density difference were found to vanish at the critical point. Interfacial tensions of less than one dyne/centimeter were observed as far as 1,000 pounds per square inch below the critical pressure. EXPERIMENTAL PROCEDURE The interfacial tension divided by the density difference for the methane-normal decane system was determined at the 100°, 130°, 160' and 190°F isotherms, from pressures of about 1,000 psi to the critical pressure, which is more than 5,000 psi for these isotherms. Particular emphasis was placed upon the investigation at pressures slightly below the critical pressure where the interfacial tension is less than 0.5 dyne/cm. Volumetric properties in the two-phase region, including the critical pressures and temperatures, were taken from the work of Sage and Lacey.1 The experimental pendant-drop technique used for the determination of interfacial tensions at high pressures incorporated the ideas of Michaels and Hauser,2 Hough, et a1,3 Walker4 and Heuer.5 In addition, the technique for determination of extremely small interfacial tension by Jennings6 was utilized in the region near the critical points. A detailed description of the apparatus is given in a dissertation by one of the authors.7 Cleaning operations on the stainless-steel sample system included successive washings with chromic acid, tap water and, finally, distilled water. Subsequent cleanings were performed with re-distilled normal pentane, which had an extremely low residue upon evaporation. Specific composition requirements necessitated a fairly precise sample introduction — although, fora two-phase, two-component system, the composition of each phase is completely determined if pressure and temperature are controlled. The normal decane was delivered into the evacuated sample system as a liquid from a burette. The methane was then introduced into the system from a calibrated isothermal container, so that pressure differentials could be used to determine the amount introduced. High pressures were obtained by compressing the sample with a mercury injection pump until the critical pressure was reached for the particular isotherm being studied. Experimental data were then obtained for specific pressures by first decreasing the pressure slightly so that two phases would appear, and then photographing a drop at that pressure. Subsequent photographs were made at increments throughout the pressure range. Calculation of interfacial tension divided by density difference was made from measurements

By R. J. S. Brown, B. W. Ganison

A new logging method has been developed, based on measurement of the nuclear magnetism of formation fluids. The nuclear magnetism log (NML) is the only log that responds solely to formation fluids. It operates equally well in both oil-base and water-base muds and in empty holes, and can be used in all kinds of formations except strongly magnetic ones. Two separate NML measurements can be made, one of which provides a continuous formation fluid curve. This fluid curve is called the free fluid log (FFL) and is believed to indicate a minimum effective porosity in most formations. The FFL not only delineates fluid-containing zones, but provides an excellent correlation curve that can be obtained under conditions where conventional correlation logs are ineffective. Preliminary tests indicate that the second kind of NML measurement may help distinguish oil and water zones and provide information concerning permeability and wettability. (The FFL itself appears to provide some information on permeability.) The second kind of NML measurement requires stopping the logging tool for a short time opposite a zone of interest and taking more extensive NML data that can be displayed as nuclear magnetic relaxation curves. In some instances, oil and water saturations for the region immediately adjacent to the borehole can be read from these relaxation curves. INTRODUCTION In 1946, Bloch, Hansen and Packard and Purcell, Torrey and Pound3 independently announced the successful demonstration of the phenomenon of nuclear magnetic resonance. During the past 13 years, there have been many applications of nuclear magnetic resonance, including applications to the study of chemical structure and to the measurement of magnetic field strengths. Preliminary experiments on the feasibility of using nuclear magnetism measurements in well logging were made independently by California Research Corp. and Varian Assoc., the Varian work being sponsored by the Byron Jackson Tools, Inc. Since then a cooperative research program on nuclear magnetism logging has been carried out by the Byron Jackson Div. and Research Center of Borg-Warner Corp., and California Research Corp., subsidiary of Standard Oil Co. of California. The use of nuclear magnetism in well logging is of special interest because it offers a way of making direct measurements on the hydrogen in the formation fluids and not on the rock matrix. Within the past 1 1/2 years, successful measurements have been made with a research model logging tool in wells in California, Tex as, Utah, Louisiana and Wyoming. NUCLEAR MAGNETISM SIGNALS Polarization, Relaxation and Precession Many atomic nuclei possess magnetic moments and spins; that is, they are similar in some respects to bar-magnet and gyroscope combinations. Molecules and their nuclei are subject to thermal motion, which has a scrambling effect, tending to leave as many nuclear spins oriented in any one direction as in any other. However, if a magnetic field is applied, the magnetic nuclei tend to align in the direction of the field. The scrambling and aligning forces compete with each other, with the result that a few more spins are oriented parallel to the field than in other directions. This gives a net magnetization, or polarization, which is directly proportional to the strength of the applied magnetic field (aligning influence) and inversely proportional to the absolute temperature (scrambling influence). When the magnetic field in, or temperature of, a liquid sample containing protons is changed, the new equilibrium value of proton polarization is not established immediately but requires an amount of time which depends on the nature of the hydrogen-containing materials. The process of approaching the equilibrium value of polarization is called relaxation.'.' Polarization is a vector quantity, and the components parallel to and perpendicular to the magnetic field must be considered separately. Relaxation of the component parallel to the field is called "thermal relaxation", or "longitudinal relaxation", and the corresponding time for this component of non-equilibrium polarization to decay by a factor of e (natural log base) is denoted T. The relaxation of the perpendicular component is called "transverse relaxation", and the corresponding relaxation time is denoted T,. The potential energy of a magnet in a uniform field depends on the angle the magnet makes with the field; therefore, a change of the component of net polarization parallel to the magnetic field involves an exchange of energy between the spin system and the thermal motion of the molecules, leading to the term thermal relaxation for the relaxation of this component. Suppose we subject a sample to a strong magnetic field at right angles to the earth's field for a time greater than TI. A polarization, thus, is established at right an-

By F. C. Blickensderfer

During 1914 and 1915, extensive experiments were conducted at the concentrator of The Detroit Copper Mining Co. of Arizona, at Morenci, Ariz., in order to test the relative grinding efficiencies of the Marathon, the Chilean and the Hardinge Mills. The Marathon mill used in the experiments was the first one ever built by the manufacturers; and since this was the first time that it was given a thorough tryout, with such remarkable results, the data have been assembled in the following paper and submitted in the interests of the milling profession. Description of the Flow Sheet The concentrator flow sheet, as it existed at the time of these tests, is shown in Fig. 1. The total mill feed, as delivered from the crushing plant, had as its maximum size 1-in. material. This material was screened dry on Cole Zig-Zag screens fitted with 4-mesh openings; the oversize going to one pair of coarse rolls, the undersize to five Wilfley tables fitted with Butchart National riffles. The coarse-roll product was elevated and screened wet on Zig-Zag screens fitted with 4-mesh openings, the undersize going to the five tables mentioned above and the oversize to one pair of fine rolls. The fine-roll product was elevated and screened together with the coarse-roll product; so that, before any concentrating operations took place, the total mill feed was reduced to pass a 4-mesh screen. After concentration on Butchart-riffled tables, the tailings from these tables passed to de-sliming hoppers, where two products were formed, viz., an overflow and a discharge. The discharge constituted the feed for the Chilean mills. It contained 16 per cent. slime (—200 mesh) and 3 parts of water to 1 of solids. The concentrator was equipped regularly with four Chilean mills (Monadnock type) to the unit; but, in order to

Jan 1, 1917

By C. W. Burrows

The burden a man can endure depends on its magnitude and the number of times it is applied, as well as on many other factors. The resisting power of steel likewise is dependent on many factors. The maximum load it can support indefinitely is much less than its possible momentary burden. A light load straining the metal far within its elastic limit, if repeated indefinitely, ruptures the metal. The magnitude of the stresses that may be alternately applied and removed without rupturing the material depends on the number of repetitions of the cycle; the intervening periods of rest; the thermal, electric, and magnetic conditions, as well as the presence of secondary streessses. While we are unable to formulate the law between the magnitude of repeated stresses necessary to produce rupture and the length of time during which these alternating stresses may be applied before rupture, my experience is that the time increases as the magnitude of the force decreases, according to a law which! to a first approximation, is exponential. In other words, F = Ce-t where F= magnitude of alternating stresses; t= time for which stresses are continued; C = constant, which depends on the conditions under which the operations are carried out. It is quite probable that the same type of law holds for the magnitude of a continuous force and its duration. When a rod of steel is subjected to the blows of a drilling hammer several things happen. First, one end is struck by the hammer and the other end is driven into the rock, thus causing a bodily displacement of the entire material of the steel drill. The greatest stresses involved in this bodily displacement are located at the two ends of the steel and manifest themselves by the distortion of these parts. Second, after the blow has been delivered, the steel drill, due partly to its own resiliency and partly to the resiliency of the rock, experiences a vibratory motion as a whole, this motion is quite similar to the bouncing of a rubber ball thrown violently upon a smooth pavement. Third, the free vibration of the drill is determined only by its own natural period of vibration. This motion involves all the characteristics of any vibrating body emitting sound. Certain elements of the rod will experience alternations of condensation and rarefaction and, in these regions, the individual steel

Jan 1, 1922

By H. B. Northrup

Mineral Industries Extension instruction was pioneered by The Pennsylvania State Colleges Extension work was organized in 1893 and constituted what is believed to be the first vocational adult educational effort in that field in America. From 1894 to 1899, twenty-seven extension bulletins were printed and distributed free for the benefit of classes in the coal-mining industry and the records show that free lectures wore delivered by a corps of teachers of the mining department of the College "to the mining employees at their customary lace of assembly upon matters of interest to them in their occupation." In 1899, the State Legislature reduced the appropriation to the College and therefore the extension pamphlets and lectures were discontinued. Several sporadic attempts were made to resume the extension services in mining through industrial grants for travel and publications, and through voluntary contributions by members of the resident staff. The work. consisted mainly of lectures and demonstrations and served the purpose of creating the desire for more training and information of a more formal character. In 1928, the nave of the school was changed, by trustee action, from School of Mines and Metallurgy to the School of Mineral Industries and the working structure of the school was organized under the three functional collaborating headings: Resident Instruction, Correspondence and Extension Instruction, and Mineral Industries Research. The three functional bodies are separate, yet interdependent. The Federal Smith-Hughes law, passed in 1917, made Federal and State funds available for vocational educational work. Mining extension was revived in 1919 and the College employed one full-time extension professor to reorganize the work and instruct the classes. In 1923, the State Department of Mines and the State Department of Public Instruction entered into, a formal agreement with the School of Mineral Industries to assist the College in its extension program.. Classes were organized to study the State mining laws and State Department of Mines' previous examination questions and answers, in preparation for coming state examinations for certification of competency as underground officials. Mimeographed lesson material was used at first, and in 1947 and 1929 mining instruction and mining teacher-training lessons were printed. In 1931, the extension activities of the school were placed on an organized basis compatible with the newly formed school organization and a director was appointed to tale full charge of the work. During that year, at a conference in Harrisburg, an agreement was consummated between the State Departments of Public. Instruction, Mines, Labor and. Industry, and the College whereby extension classes in the field of the, mineral industries could be organized by the College, throughout the State, under "public supervision and. control," in close cooperation with the State Department.

Jan 1, 1941