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By Edward H. Robie

OF the current Adirondack iron mine development, the Benson Mines operation of the Tones and Laughlin Ore Co. (Jones & Laughlin Steel Corp. wholly owned subsidiary) is the last to go into operation. Following an active construction program in 1943, the mine. concentrator and sintering plant were scheduled to enter production in the fall. This description therefore cannot include any operating data, and details of equipment and flowsheet have not as yet been released.

Jan 1, 1943

By H. J. Rahilly

MINE FIRES, in the Butte District, have been a source of trouble and expense for the past thirty years, for while the actual fire area in most of the mines has been comparatively small, the handling of the gas has generally been a much larger problem than the actual putting out of the fire. The chief causes of these fires have been: Defective electrical equipment, incendiarism or carelessness, and spontaneous combustion. While fires from the first two causes have been numerous, they have generally been discovered and extinguished before they became very serious. Spontaneous combustion has been the cause of most of the large fires. Sufficient heat has been generated by ground movement, high rock temperatures, and decomposition to set fire to inflammable materials (tarred ropes, canvas, dry timber, manure, and hay) left in the gobs some years ago. Also, the heat resulting from the oxidation of the fine broken sulfide ore is sometimes sufficient to set fire to the timbers. In 1906, a fire was discovered on the 1100-ft. level of the Minnie Healy mine about 400 ft. (122 m.) west of the Minnie Healy shaft, which presumably originated, in one of the upper levels, from spontaneous combustion. The fire was walled off by concrete bulkheads and a pillar of ground 100 ft. (30 m.) thick was left below and mining resumed underneath. During subsequent operations, this pillar became cracked and broken and the fire passed into the new workings. It travelled downward and spread rapidly until, in 1917, it had become necessary to wall off portions of the Tramway, Leonard, and West Colusa mines on the 1300, 1400, 1500, 1600, 1800, 1900, and 2000-ft. levels, and the top of the 2200-ft. raises were sealed. The fire area now consists roughly of a block 1000 by 1200 ft. and from the 600-ft. to the 2200-ft. level. This block is composed largely of a series of parallel northwest-southeast nearly vertical veins and stringers that form a large orebody, with no well-defined walls but badly fractured and faulted, and known locally as "Horsetail Ore." These veins, or orebodies, are mined by the square-set or the rill method.

Jan 2, 1922

By Walter Renton Ingalls

Metallurgical literature has no record of any ore beneficiated for cadmium alone, and the cadmium of commerce is derived from zinc ore, with which cadmium is generally associated. Zinc ores free from cadmium—e.g., the ores of the Franklin and Stirling mines, New Jersey, and of Broken Hill in Rhodesia—are rare. Blende concentrates of 50 to 60 per cent grade have contained (in production of important tonnage) as much as I per cent Cd, which is unusually high. The concentrates from the Tri-State district average from 0.3 to 0.4 per cent Cd, which is high. The concentrates from mines west of the Rocky Mountains seldom are higher than 0.2 per cent. In the periodic system of the elements, cadmium is in the same group with zinc. Its properties and compounds are similar. Its metallurgy is also similar. Cadmium has a melting point of 320°C. and a boiling point of 778"C., while the melting point of zinc is 415'C. and the boiling point gos°C. These conditions, together with the lower reduction temperature of cadmium oxide, indicate means for. separating cadmium from zinc. Cadmium in spelter is viewed, if not as an impurity, at least as an alloying element that may be objectionable, its special effect being hardening. However, for some purposes, a little cadmium in spelter is desired, and 0.4 per cent may be permissible, even in spelter for rolling. Cadmium in spelter for brassmaking is completely volatilized at the temperature of that process, and in bygone days an immense quantity of cadmium must have been lost in the fumes from these furnaces. Pyrometalltjrgy—Early Cadmium compounds, sulphide and oxide, being more volatile than the corresponding compounds of zinc, loss of cadmium begins to occur from the first furnace operation. In normal roasting, even with Tri-State ore, this loss may not be very high. Raw ore, assaying 0.4 per cent Cd, may be expected to give a roasted product of the same assay, which would imply a cadmium loss of about 15 per cent. Roasted ore, assaying 0.4 per cent Cd when distilled at ordinary furnace temperature, yielded spelter containing about half of that in the ore charged. The first draw of spelter under these conditions may assay 0.8 per cent Cd (accounting for 22 per cent of the cadmium recovery) and after the several draws of spelter have been equalized the cadmium content may average 0.35 per cent. If, therefore, 2000 lb. of blende averaging 0.35 to 0.4 per cent Cd is roasted and distilled, there may be obtained 1000 lb. of spelter, assaying 0.35 per cent Cd or 3.5 lb. content, which entering into Prime Western spelter will be sold at the spelter price. It will be observed from the outline hereinbefore (summarizing conditions prior to the introduction of sintering) that the main loss of cadmium occurred in the distillation process and by failure to condense, which could be ameliorated by attaching a prolong to the condenser, thus collecting

Jan 1, 1944

By W. Smith, F. G. Rinker, D. Beggs

Early in 1965 the Surface Combustion Division of the Midland-Ross Corporation was awarded the contract to engineer and construct a taconite pelletizing plant for the National Steel pellet plant, administered by the Hanna Mining Co., near Keewatin, Minn. This plant, which will have an annual capacity of 2,400,000 long tons, will produce pellets from magnetite concentrate using a new process developed through a joint research program by Midland-Ross, Hanna Mining, and the National Steel Corp. The work that culminated in the decision to construct this plant is the result of a research program for the development of the Midland-Ross heat fast process for the production of prereduced or metallized pellets. PELLETIZING PROCESS There are many acceptable methods for producing oxide pellets from ground iron ores and concentrates, and all of these give an acceptable product for blast furnace utilization. The vertical shaft furnace, the traveling grate, and the grate-kiln have been installed in many pelletizing plants in the northern hemisphere; therefore, the acceptance of these methods and the problems associated with them are well understood. However, this research project investigated a method for improving upon these processes to produce a high quality oxide pellet at a low operating cost.

Jan 9, 1966

By C. S. Barrett, D. F. Clifton

THE transformation that occurs in lithium and its solid solutions containing magnesium1,2 is similar in many respects to other diffusionless transformations of the martensitic type. This general similarity makes it desirable to investigate the transformation curves in detail. The current interest in the phenomenon of stabilization in martensitic transformations has created a need for a careful appraisal of possible stabilization effects in both cooling and heating transformations in lithium alloys. The effect of prior heat treatment on the temperature at which transformation begins and the effect of various temperature cycles in partially transformed alloys also merit attention. Limited data on some of these features were presented previously,' but the present studies have been made with improved apparatus, in which erratic fluctuations were smaller than in the earlier work, and include many independent determinations of certain critical observations. Material and Methods Geiger counter X-ray spectrometers were used: a Norelco instrument, original model, and a General Electric XRD-3. The low-temperature specimen holder has been described elsewhere." Specimens 10 mm in diam and 1.5 mm thick were held in firm contact with a copper block which was attached to the lower end of a stainless steel tube that extended up to a reservoir of liquid nitrogen. A heating coil on the tube permitted a controlled temperature gradient along the tube, so that desired temperatures and rates of heating and cooling could be obtained by controlling the heating current. The specimen was surrounded by an atmosphere of evaporated nitrogen in an insulated chamber having double cellophane windows. The temperature of the specimen was read by a thermocouple imbedded in it close to the irradiated area; the specimen could be held at constant temperature within 1°C for long periods. The body-centered cubic 200 reflection near 8 = 26" was used as the index of the amount of b.c.c. material present; occasional checks were made using the most suitable line of the low-temperature phase, the close-packed hexagonal 110 line near 8 = 29". Copper radiation was used throughout. A continuous record was made of the reflected intensities on a strip chart recorder, both when the peak intensity of a line was being followed and when the lines were being scanned at constant temperature. On the continuous recordings of peak intensity, periodic checks were made on the background intensity between the lines, and on the setting of the spectrometer for maximum intensity. The lithium-base solid solution containing 12.4 atomic pct Mg (33.3 wt pct) that had been used previously' was chosen, as it had a transformation range at relatively high temperatures, so as to permit wide temperature cycling within the range. Just prior to use a pellet was cut from the ingot,

Jan 1, 1951

By D. J. Weintritt, R. G. Hughes

Statistics show arz increase in the average depth of wells drilled in recent years. As a corollary to this trend, drilling fluids have been improved in an effort to meet the problems inherent at temperatures approaching 500°F. Of importance are (1) deterioration of mud components and (2) the effect of solids on filtration and rheological properties. High-temperature, stable water-base and oil-bare muds are discussed. Those areas in which differences exist are pointed out. Results are based on data taken from the Fann consistotneter, rheometer and shear-strength measurements, static and dynamic filtration tests, methy-lene blue test for bentonite solids and specific heat measLrrenlents of muds. INTRODUCTION Higher well temperatures go along with the fact that the average depth of wells continues to increase. Recent data by Gardner' lists 137 completions deeper than 15,000 ft for the first half of 1964 with a record second-half total of 167 wells drilling or proposed. In addition, there has been an increase in drilling for steam for power production or mineral recovery. In this application the depths are modest, but the mud may approach the critical pressure and temperature of water. Scearce and Magnon' report drilling mud used at temperatures of about 700°F in the Salton Sea area of California. Most deep wells have been drilled with water-base muds. In recent years, however, there has been a substantial increase in the use of oil-base muds because of technological advances in effective additives. The significance of this development was dealt with in considerable detail by Simpson and his co-workers.3 Additiona1 field data have now been obtained to indicate that oil muds are competitive in control, performance and cost with the best types of water muds for use at high temperaturc. This parallel offer of two very different fluid systems, each offering a similar variability in performance, cost and convenience, has created the need to evaluate the merits of these fluids under specified conditions so that the advantages and disadvantages of each can be weighed in relation to the over-all drilling program. This paper is not intended as a review of all the factors. Rather, it attempts to emphasize: (1) important condltions and facts peculiar to high-temperature drilling muds, (2) that more than one imposed test condition or testing method is necessary to describe the quality of a mud at high temperature and (3) that elaborate experimental precautions are necessary whenever laboratory data are used in selection of a mud for field use. WHAT IS A HIGH-TEMPERATURE DRILLING FLUID? For the purpose of this discussion, a high-temperature drilling fluid is any system so formulated or treated to economically minimize the effects of temperature on the properties of the fluid. Our experience in drilling fluids suggests that these effects become obvious for many mud materials at temperatures of 300F or higher. It is understood that hydrolysis of starches, depoly-merization of certain organic thinners, or irreversible chemical reactions (such as that of clay and lime) can affect filtration, viscosity and shear strength at less than 300F. However, the temperature level is not a serious point and in no way affects the precautions and techniques used in this study. An up-to-date review of the literature on high-temperature drilling fluids and the many variations was treated by Rogers'in 1963. EXPERIMENTAL REQUIREMENTS TESTING EQUIPMENT AND PROCEDURES With the advent of deeper drilling and increased demand for temperature-stable drilling fluids, new testing equipment and laboratory techniques were devised for the evaluation of drilling fluids subjected to elevated temperature and pressure. While the equipment has not been standardized, it is in widespread use. Milligan et al. Qescribe a filtration cell for determining the filtration properties of drilling fluids at temperatures in excess of 300F. They showed the effect of variations in temperature and pressure on oil and water muds filtered in the 300 to 400F range. The dynamic filtration apparatus described by Simpson6 permits the study of the filtration properties to temperatures of 350F for drilling fluids circulated over sandstone cores. Watkins et al.' describe the use of pressure bombs for studying the effect of prolonged periods of elevated temperature upon the gelation or solidification of drilling fluids. Chisholm et a1.' describe the use of a modified cement consistometer adapted for use in drilling fluid evaluations. A similar consistometer is used in this study, although the application and data-recording method have been changed. The consistency of a mud sample is measured by timing the movement of a soft iron bob which is magnetically moved up and down in the sample container.* Changer in the time of travel and the temperature of the mud at that moment are plotted with a two-point Brown Elec-tronik Recorder. A 10-in. chart with a speed of 4-in./hr is used. Fia.- 1 is a generalized internretation of the data ob-

Jan 1, 1966

By Robert S. Williams

On several occasions, when 60-40 brass is first obtained in the beta condition by quenching at about 825" C. and is then reheated, the writers have noticed that reerystallization will take place in the form of twin crystals at the grain boundaries of the original beta crystals. It was, therefore, thought that interesting results would be obtained if this twinning process was studied further, especially as to the temperature at which it first occurs. The material used in the investigation was a bar of extruded muntz metal, 1/2 in. in diameter, and of the following composition: Copper, 60.21 per cent.; zinc, 39.73 per cent.; lead, trace; iron, trace; tin, nil. Specimens 1 in. in length were sawed from this bar and a hole was drilled into the side of each specimen until it reached the center, and the tip of a platinum-platinum rhodium thermocouple was inserted. A small Hoskins' resistance-type electric furnace was used for heating the specimens. The specimens were first heated at 840' C. for 2 hr. and then quenched ' in cold water, in order to get the material entirely in the beta state. In every case, in the reheating process, the furnace was brought to the desired temperature before the specimen was introduced. The time occupied in preheating was from 20 to 30 min. By sawing back 1/4 in. on each side of the hole, two parts were obtained from each specimen and duplicate observations were possible. The specimens were held at the reheating temperatures for periods of 15 min., 30 min., 1, 2, and 4 hr. All specimens were etched with a freshly prepared mixture of equal volumes of concentrated NH4IOH and H2O2.

Jan 1, 1924

By V. H. Wilhelm

The trend initiated in January 1936, of stabilized gasoline prices, increased demand and extraordinary drilling activity, continued in California during the year 1937. Crude prices were maintained during the year at the highest level since September 1930. Wildcat activity with resultant new discoveries and development of proven acreage were greater than in any year since 1928. Many fields in California in former years have been produced at full capacity, with consequent loss of reservoir energy, but at the present time continued activity is maintained to develop adequate reserves, so that production in these fields can be taken at a rate to correspond with good operating practice. Naturally, this good operating practice will be influenced to some degree by gas outlets and, in certain instances perhaps, by oil outlets. In any event, these last two controlling features will result in favorable rather than detrimental operation. In fields producing from great depths, ultimate production will be practically limited to the flowing and compressor life of the well, since there is as yet no economical method for pumping wells below depths of approximately 7000 ft. Experience has shown, however, that such pumping difficulties will be overcome and that production secured by pumping will add some to reserves established on the flowing life of the wells. California continued to operate under voluntary curtailment, but with unlimited transfers of allowable between various fields. Even though there was at all times considerable production above the Umpire's established quota, a constantly increasing demand reduced storage during the year. This increasing demand was due mainly to the rapid rise in Pacific foreign shipments from May to September. It is questionable, however, whether this favorable condition will be maintained over a prolonged period. (See Fig. 1.) Field Discoveries The great drilling activity during the year resulted in the discovery of three new fields in the San Joaquin Valley, as well as many extensions

Jan 1, 1938

By W. A. Hutchins

Water laws important to the mining industry are those which govern or affect the right to use water, to dispose of water after using it in mining or milling, and to discharge waste material into watercourses. They include statutes and court decisions having general applicability, as well as others that pertain specifically to mining. THE INDUSTRY'S CONTRIBUTION TO WESTERN WATER LAW Despite sharp differences of opinion, the water law the Spaniards brought to the Southwest appears to have included some form of appropriation of water. The Mormons, who settled in Utah in the mid-nineteenth century, also developed a system of appro-priative water titles. But by far the most profound impact on western water law was made by the gold-seekers who flocked to the Sierra Nevada foothills of California after the discovery of gold in 1848. Much of the gold was extracted from the ground by hydraulic or placer mining, and so the miners' rights to the use of water became fundamentally important. Since there was no organized government in the foothills and no laws other than those made by the miners, they helped themselves to the land, the gold, and the water needed to work their claims.1 They established and enforced regulations governing the acquirement and holding of mining claims and their rights to the water they needed.' In 1879 Justice Field, former Chief Justice of the California Supreme Court, spoke for the U. S. Supreme Court in saying that the miners were "emphatically the law-makers, as respects mining, upon the public lands in the State."" Rules of the California mining camps were based on two essential principles: 1) priority in discovering claims and appropriating water by diverting it from streams and putting it to use, and 2) diligence in working claims and applying water in mining. The customs so developed, which were copied in mining areas of other states and territories, were enacted into law in one western jurisdiction after another. They form the basis of what is called the arid-region doctrine of prior appropriation of water, which received the attention of Congress in legislation recognizing and protecting appropriations of water for mining, agriculture, and other purposes on the public domain.' In several western states a great number of water cases decided in the early years involved relative rights to the use of water for mining purposes or for milling connected with mining." The miner's inch, the customary unit for measuring water in the mining camps, is still used in various western communities, although its relation to the cubic foot per second varies from one area to another. Undoubtedly, the miners of a century ago made the major contribution to the appropriation doctrine as it is now recognized and applied throughout the West. What inspired the California gold-seekers to develop these principles? Thoughtful writers have pointed out that their regulations and customs were strikingly characteristic of much earlier mining enterprises in the Old World.D It is said that the right of free mining and free use of flowing water therefor —so similar to the California conditions and practices—-was a part of the customs of Germanic miners in the Middle Ages, that it spread from middle Europe to other countries and colonies, and that the doctrine of prior appropriation was widespread in the important mining regions of the world. Certainly the Forty-niners came to California from many countries. It does not tax the imagination to consider that they may have brought with them some knowledge of the old Germanic customs and applied this knowledge in their new environment. RIGHTS TO USE OF WATER IN GENERAL In the West, rights to the use of water of watercourses fall into two categories—appropriative and riparian. The doctrine of prior appropriation is recognized in each of the 17 western states. The riparian doctrine is recognized concurrently with the appropriation doctrine in some of these states but has been abrogated in the others. The riparian doctrine prevails generally throughout the East, although there is now considerable interest in developing something else. Generally speaking, the appropriation doctrine has been highly developed in the West, whereas the principles of riparian doctrine have been comprehensively established in only a few states throughout the country. The subject of water rights is a big one. Space permits no more than a brief discussion of aspects that bear upon the title of this article. RIGHTS OF PRIOR APPROPRIATION Fundamental to the doctrine of prior appropriation is the principle first in time, first in right. Although in some states there are statutory exceptions. the original and still generally prevailing rule is that the first one who initiates a right to divert and use water of a stream, and who completes his undertaking with reasonable diligence, acquires thereby the first right of appropriation of the specific quantity of water involved. Each succeeding right in point of time is junior to all earlier rights but senior to all later ones. The practical effect of this priority system is that when the water supply is not enough for all, the earliest rights must be fully satisfied before any water may be taken by those later in time. Acquirement of Appropriative Rights: Each of the 17 western states has a statute under which water may be appropriated pursuant to a prescribed procedure. Generally, the first step to be taken by the intending appropriator is to file application in the office of the State Engineer for a permit to make the appropriation. In most but not a11 states, valid ap-

Jan 1, 1961

By HUGH E. McKinstry

OPENING the sessions of the Mining Geology Committee, the program on postwar mineral controls drew a larger attendance than any other session of the entire meeting. In view of its general interest, the papers of this session, or a substantial portion of them, are printed elsewhere in this issue. Whether control of mineral resources can help to promote peace, how controls could be applied and to whom, are questions so far-reaching that naturally no pat answer was agreed upon. In fact the discussion took on something of the flavor of a debate between those who favor strict control and those who felt that attempting to ration nations in peacetime would defeat its own ends. Discussion from the floor emphasized the difficulties in administering any international control and the $64 question, that no one cared to answer, asked by a courageous young lady who was induced to mount the rostrum for the purpose, was whether the United Nations should exchange mineral controllers to police each other.

Jan 1, 1944

By H. Y. Yancey, B. M. Bird

During the past four years the experimental work in coal washing carried on by the U. S. Bureau of Mines and the University of Washington has been devoted mainly to the development of special methods for the tabling of fine sizes of coals that are difficult to wash. One important outgrowth of this investigation has been the application of hindered-settling classification to coal tabling. Although used for many years in ore dressing, the term "classification" as used here may be new to many readers. It may be defined as the separation obtained when a bed of particles is held in a uniform state of suspension in an upward current of water, either continuous or pulsating, just sufficiently strong to keep the bed in a mobile condition. A common example of this type of separation is a jig in which there is no suction stroke. When the hindered-settling classifier is used with the coal-washing table, the fine-size raw coal, instead of being fed direct to tables, as is the prevailing practice, is first fed to the classifier and grouped, according to the rate of settling against the upward current of water, into perhaps six separate products. After dewatering, each of these except the sixth, a refuse product, is elevated to a seperate feed bin arid washed on a separate table. This paper gives a brief discussion of the basis for the use of hindered-settling classification of a table feed; a description of the experimental work; a comparison of the results obtained with and without classification; and a discussion of the application of the classifier in commercial coal washing. Basis for Use oF Hindered-settling Classification of Table Feed Although theoretical reasoning might be used to justify treating a table feed by hindered-settling classification,l the simplest method of demonstrating the need of such a step before tabling is to show the

Jan 1, 1930

Edgar Archibald Collins was born at Truro, Cornwall, Nov. 16; 1877. He was the fifth (and youngest) son of J. H. Collins, a well known Cornish geologist and engineer, who died in 1916. Edgar Collins spent part of his childhood at Rio Tinto, in Spain, and after returning to England was educated at Alleyne's School at Dulwich, near London. His technical training was acquired by practical experience in Cornwall, supplemented by private study and by his father's teaching. This method of training for the work of a mining engineer was preferred by his father to that of the technical schools then available, and judging by its result, was not unsuccessful. It is,-however, noteworthy that all members of the Collins family who were products of this system later sent, or planned to send, their own sons to technical schools. Edgar Collins came to Gilpin County, Colorado, in 1894, and returned there in 1898, after several intermediate years spent in Cornwall. In Colorado he worked, under his brother Arthur, in the California and other mines of the Gilpin County district, and thereby gained a practical skill and experience as a working miner, and a habit of minute observation of vein phenomena, which proved of the greatest value in later years. In 1899 he went to the Smuggler-Union it Telluride, as general assistant to his brother Arthur, and stood the brunt of 3 years of struggle with the Western Federation, gaining a reputation, for quiet courage and sound work under the most difficult conditions. After Arthur Collins' assassination in the Smuggler-Union office, in November, 1902, Edgar left Telluride, and shortly thereafter entered the employment of a syndicate headed by Arthur Winslow, of Boston, to search for and develop new mines. While so engaged he spent several unsuccessful months near Parral, in Mexico, and later visited and sampled the- newly discovered district of Grandpa, afterward known as Goldfield, in Nevada. This led to the acquisition by the Winslow syndicate of the Combination mine, at first under lease and option; and Edgar Collins was placed in charge. The Combination was really the starting point of Goldfield. It was a profitable mine before the discoveries at the Jumbo were made; and while the Combination, being a "Company-account" mine, controlled by a few responsible men, never attracted the publicity that centered around the sensationally profitable leases on the Jumbo and Mohawk, which publicity was used to further the feverish stock-dealings that characterized the new district. The Combination was really the pioneer mine, made the first shipments of rich ore, constructed the first water-line, and built the first mill (designed by F. L. Bosqui, an old friend and associate); and while it pursued a quiet and unobtrusive. career up to the time of its sale to and incorporation with the Goldfield Consolidated, was probably, in ;proportion to the amount of money risked, the most profitable bonanza in the recent history of gold mining.

Jan 11, 1918

By Vasily P. Muravjev, Gennady I. Razgildeev

The theory of reliability is a powerful mathematical tool for determining optimum selection of components and application of electrical power to coal mines. In order to make this tool useful, statistical material on equipment life must be gathered and all failures carefully recorded. Statistical data can be applied to new apparatus design and can be used to determine optimum configuration of network and maintenance to reduce costs. Reference is made to underground power systems in the USSR. Technical progress in the last few years has occurred in the design and application of highly productive coal mining and transporting machinery. One of the most important problems facing mining engineers is to increase the availability of the machine to obtain higher productivity. However, machine failures and breakdowns of electrical power supply components cause serious delays in the coal-winning processes. In spite of the fact that electrical equipment and the power supply contribute only a small percentage of direct mine costs, electrical failures as well as power supply delays can result in severe indirect losses. It is necessary, therefore, to consider reliability and safety in the application of electrical equipment underground. To obtain the best results, it is necessary to investigate and evaluate the reliability of the electrical mining components (starters, breakers, motors, cables, etc.) and optimal methods for minimizing maintenance, the desired result being equipment which is efficient and safe. Electrical equipment reliability directly influences economics: the lower the reliability the more frequently failures occur, causing serious working delays and possibly huge economic losses. By the same token, while increasing the number of preventive maintenance calls per unit time might result in fewer failures, thus reducing delays, the cost of making more frequent maintenance inspections will increase; this is one aspect to be discussed in detail. Obviously, failures of identical types of electrical equipment (starters with the same current and voltage, etc.) are influenced variably by different working conditions, environments, quality of the apparatus, maintenance procedures (personnel, frequency, quality), load, and other factors. Hence, the lifetime of identical types of equipment will vary depending upon usage in terms of the foregoing factors. Thus for a given type of electrical component, these factors must be considered quantitatively; the interaction of all these factors are evaluated quantitatively by a statistical method using probability theory. Equipment reliability must be quantitatively determined from a study of equipment life, since no one laboratory test can reproduce all working conditions and environmental effects. Nevertheless, reliability theory applied to electrical mining equipment is a very powerful mathematical tool for selecting as well as evaluating certain parameters. It is necessary to select several reliability parameters so that one can obtain an expression for the total overall economic situation in terms of cost, taking into consideration damage caused by electrical equipment failure and cost of maintenance. To accomplish this result, such characteristics as apparatus lifetime, breakdown idle time, and losses (damages) can be determined quantitatively on a statistical basis. For identical electrical equipment working under similar conditions, the previously mentioned reliability factors are random variables and therefore can be characterized readily by a probability density function. Investigations carried out by the authors in the Kuznetsk Basin (Kuzbas) in West Siberia, USSR, show that the reliability factors of electrical mining equipment are well described by the exponential, normal, or Erlang's distribution in most cases. Mining electrical equipment life is well-described by the exponential law. The distribution of lifetime density is

Jan 1, 1971

The eastern part of the state of Rhode Island on both sides of Narragansett Bay, including the island of Rhode Island, is underlaid with carboniferous rocks which carry veins of anthracite. This formation extends into the neighboring portion of Massachusetts, including the area from the state line, the towns of Mansfield, Brockton and Bridgewater,: and extending probably ten miles east of the latter two towns, to Middlesboro, and to Fall River. In Massachusetts the coal formation extends over nearly the whole of Bristol, and parts of Plymouth and Norfolk Counties. In Rhode Island and Massachusetts the area covered is about 400 square miles. In both states the exact limits of the coal measures cannot be determined on account of a thick layer of drift which overlays it. Along parts of Narragansett Bay, the coal measures outcrop in the cliffs on the west side of Rhode Island, and the presence of coal here seems to have been noted as early as 1760, and in 1768 a patent was granted to parties who "were about to dig after pit, coal or sea coal" at the back of the town of Providence. In 1807-08 Benjamin Silliman, later a geologist, visited some openings,' and in 1808 a mine was opened near Portsmouth, in the northeast part of Rhode Island. Work was done here until about 1814 when the mine was abandoned. No anthracite had been used in New England at that time, all coal used came from Nova Scotia, Virginia or England, and was high volatile bituminous; neither experience nor the means of firing favored the use of the local fuel? This mine was again working in 1827, was again abandoned and operations were resumed in 1847. In 1837 a note in a magazine mentions, "the immense coal mine in Cumberland-about six miles from the city of Providence" as having a shaft 14 ft. in diameter and 80 ft. deep, that the horses then used for hoisting the coal were to be superseded by a steam engine and another shaft was to be sunk. With these improvements 30,000 to 50,000 tons were to be produced the following year at a cost of $1 per ton and a sales realization of $6.1 Hitchcock's report refers to a number of localities in both states where definite knowledge of coal existed. These are:

Jan 1, 1942

By R. D. Rubright, Owen J. Hart

In the Bingham district over a span of more than 90 years, 43,947,104 tons of "non-porphyry" copper, lead, zinc, gold, and silver ore have been mined from a folded and faulted alternating series of Pennsylvanian and Permian limestones and sandstones and from some Tertiary intrusives. This ore came from six major mine areas located east, south, and west of the Bingham stock, site of Kennecott's porphyry copper deposit. The sediments were affected by varying degrees and types of metamorphism within 2000 feet or more of the Bingham stock. The intrusives consisting of the mineralized Bingham and the unmineralized Last Chance stocks and numerous dikes and sills of granite and monzonite were intruded into the asymmetrical northwest-trending and plunging Bingham syncline. Extrusives, although present, contain no ore. The bulk of the non-porphyry ore in the district was found above the Midas thrust. The primary ores are found in three major types of deposits: concordant bedding fissures, crosscutting fissures, and replacement deposits. These deposits consist of both copper and lead-zinc ore bodies that contain various amounts of gold and silver. These are in places roughly zoned both laterally and vertically and have been mined for up to 10,000 feet outward from the center of the Bingham stock and up to 5000 feet vertically below the surface. Secondary ore was of minor importance and was found in and under the oxidized zone at shallow depths. Genetically the Bingham stock, the ores, and related phenomena have had a common source.

Jan 1, 1968

By W. N. Poundstone, G. R. Spindler

A comprehensive report on extensive experimentation in degasification of the Pittsburgh Coal seam is presented. Detailed accounts of the procedures and results are given for permeability tests, vertical bore hole tests, measurement of gas flow from sealed drainage areas, horizontal rib hole tests, and water infusion tests. The removal of methane gas from coal seams in advance of mining is not a new idea with mining men—much attention has been given to the possibility for many years. In other parts of the world, a principal concern has been in the recovery and utilization of the gas and a number of successful projects have been developed in Europe and elsewhere. In this country, the principal motivation has been related to the safety aspect with some possible side benefits concerning costs and efficiency in mining as secondary objectives. To date, experimental work in this country has been largely or entirely exploratory to determine bed characteristics with respect to the liberation of combustible gases to investigate or establish the possibility of degasification in advance of mining and as an aid in projecting mine ventilation systems to provide for safe, effective and economical handling of combustible gases liberated during mining. With these objectives in mind, the School of Mines and Engineering Experiment Station at West Virginia University, in cooperation with the Christopher Coal Co. of Osage, W. Va., initiated some experimental work in May 1952 and the project has been more or less continuous since that time. The work has been centered entirely in mines of the cooperating company in Monongalia County, W. Va., and Greene County, Pa. LOCATION AND GENERAL CONDITIONS OF THE AREA The principal mining in the area involved is in the Pittsburgh coal seam which lies at the bottom of the Monongahela series of the Pennsylvanian. The Pittsburgh coal in the area is generally uniform in its structure and physical characteristics. The bed thickness averages about 7 to 8 ft and the coal has a characteristic blocky structure as the result of pronounced face cleats and definite, but somewhat less pronounced, butt cleavage. It is a medium volatile coal, averaging about 37 pct, and is marketed principally as a steam fuel and for metallurgical purposes. The Pittsburgh coal outcrops along the Monongahela River and dips gradually, but not uniformly, slightly north of west (about N75°W). The westward extensions of the bed, from the areas contiguous to the Monongahela River which have been heavily mined, constitute the principal reserves and are all well below drainage with the depth of cover increasing with the distance from the river. In general, with deeper cover, it may be expected that methane liberation will be more of a problem in future mining as compared to areas mined previously; therein lies the interest in possible de-gasification in advance of mining. Fig. 1 shows the Pittsburgh coal area in the vicinity of Morgantown in Monongalia County, W. Va., and Greene County, Pa., in which the experimental work discussed is located. Fig. 2 shows the contours on the Pittsburgh coal in the test area. It will be noted that the first two bore holes for the experiments were at the edge of a bench or terrace with considerable change in the gradient in the immediate vicinity of the test holes and that the same general condition applies to later test areas. Mining is intensively mechanized in the area and in the mines involved in the experimental work with corresponding rapid advance of working faces a typical characteristic. In the areas now mined the total methane liberation ranges from moderate to relatively heavy, but the actual face liberation is extremely variable and may range from practically

Jan 1, 1961

By John Hays Hammond

The Transvaal comprises about 120,000 square miles (nearly • the size of the United States Territory of New Mexico). Besides the famous Witwatersrand, which will here be de scribed in detail, there are two quartz-mining districts of some importance, viz., Lydenburg and De Kaap. The Lydenburg district first attracted attention in 1876, when the alluvial deposits of that section began to be exploited. At a later period vein-rnining was started, and at the present time several companies are operating in that district. The product in 1898 of five companies, running 137 stamps, was 154,560 tons of ore, yielding 108,884 crude ounces of gold (an average of 14.09 dwt. crude gold per ton) valued at £392,378. The De Eaap gold-fields were discovered in 1884. In 1898, seven companies, running 200 stamps, produced 89,760 crude ounces of gold, valued at £314,792. I. Mining Titles in the Transvaal. The mining laws of the Tranuvaal are most excellent in char acter, and while the claims cover every square foot of land for an area of nearly 40 miles long by from 2 to 3- miles wide, there have been practically no conflicts over extra-lateral rights. Notwithstanding the change in the political status of the Transvaal likely to follow the present war, it may be coufi dently assumed that the main features of the mining law of the South African Republic will be retained, and certain op pressive featureu of monopolies, etc., bearing with special weight on the mining industry, will be abolished. The dynamite mo nopoly was one that bore most heavily on the mining industry; and, according to the Reports of the State Mining Engineer, explosives, including fuse and detonators, amounted to nearly 10 per cent. of the total working costs of the mines. Further more, it was impossible to obtain the proper quality for the most economical working, and often 80-per-cent. or 40-per-cent. gelatine had to be used- in many instances where 60-per-cent.

Jan 1, 1902

By A. B. Parsons

LAST YEAR (1934) saw the completion of a ten-year program of reconstruction and modernization of the world's largest lead- smelting plant, that of the ' Broken Hill Associated Smelters Proprietary, at Port Pirie, South Australia, which has a capacity for smelting and refining 220,000 (short) tons of lead per year. It deals with the entire output of lead concentrates from the famous Broken Hill district in Australia, being owned .jointly by the three leading companies: North Broken Hill, Broken Hill South, and the Zinc Corporation. These companies, together with the Sulphide Corporation, are credited with a production of 198,000 tons of lead in 1934. When one says regarding any metallurgical plant that modernization is "completed" he should add "for the moment." Development in the art of metallurgy and in the equipment used never ceases; that which seems close to the last word today is likely to be obsolete in a few years even in a process so well standardized as smelting and refining lead. However, the reconstruction at Port Pirie has altered the procedure materially. More im-

Jan 1, 1935

By C. S. Barrett, O. R. Trautz

Previous investigations have shown that lithium is body-centered cubic from near its melting point to the temperature of liquid air.1,2,3 Nevertheless there was an incentive to search again for a transformation at low temperatures: C. Zener4.5 has remarked that the low value of the elastic modulus (C11 — Cl2)/z of body-centered cubic metals and alloys implies a rapid increase in free energy with decreasing temperature, which would favor the occurrence of a transformation; also the shear movement to which this modulus applies is one that can transform a body-centered cubic structure into a slightly distorted face-centered cubic structure. It was confirmed that lithium does not transform spontaneously at liquid nitrogen temperature, but it was found that a transformation can be induced at this temperature by cold working the metal,6 and at slightly lower temperatures a different transformation occurs spontaneously. Transformations were also found in solid solutions of magnesium in lithium. The Nature of the Transformations Before presenting a detailed treatment of the technique used and the specific data obtained, it would be well to give a brief survey of the general characteristics of the transformations. A new crystal structure begins to form spontaneously in a specimen when it is cooled below a critical temperature. In lithium the structure appears to be close-packed hexagonal; in theLi-Mg alloys most of the diffraction lines (but not all) are near those for hexagonal lithium. The transformation proceeds as the temperature is lowered and soon stops if the temperature is held constant or raised. The course of the transformation on cooling is indicated by the curve at the lower left of Fig -I. This curve is drawn in stepped fashion because the transformation goes by discrete steps with audible clicks. Because of the similarity to the decomposition of austenite into martensite in steels, it seems appropriate to designate the beginning of the spontaneous transformation on cooling as the Ms point. On heating to room temperature after the low temperature treatment only the usual BCC structure is found. On heating, the low temperature modification begins to disappear at a temperature which will be designated as Ac. The transformation on heating is halted when the rise in temperature is halted. The temperature must be raised 40 to 50°C above Ac before the reversion is complete—an interval which is sensitive to the rate of heating and to the time of holding at temperatures above Ac. This behavior on heating thus has similarities also to the formation of martensite in the cooling of steels.

Jan 1, 1949

By THOMAS LEONBRD WATSON

INTRODUCTION. IN a paper read by title at the Washington meeting of the Institute, May, 1905,1 discussed at considerable length the geological relations, node of occurrence, and the genesis of the lead- and zinc-ores of the Virginia-Tennessee region. The present paper treats of the purely economic phases of the zinc-ores of the district; such as methods of mining the ores, their preparation and treatment. The Albemarle county mines and plant were discussed in the paper referred to above, and will not be considered here. METHODS OF MINING. Until very recently the mining of lead- and zinc-ores in Virginia was limited wholly to the surface belt of weathering. The mode of occurrence and the character of the ores to be mined were such as to demand the employment of methods used in mining secondary concentrated ores. Accordingly, a system similar to that practiced in mining brown iron-ores was employed, being modified to meet the changed conditions. Oxidized or Soft Ores.-Up to the present time practically all the ore mined in the Virginia district has been of the oxidized or soft type;-the silicate, calamine, and the carbonate, smith-sonite; largely the former, which has been localized and concentrated at only slight depths below the surface. Because of the extreme irregularity with which the limestone weathers when stripped of the overlying residual clay, it presents a roughened surface of large and small irregular "chimneys"

Mar 1, 1906