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By John Durkin

Field studies have been conducted in a large number of coal mines throughout the U.S. to determine the effectiveness of electromagnetic techniques in locating men trapped underground following a mine disaster. Data from these tests have been used to generate models of expected signal and noise distributions as found above mines throughout the coal fields. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results indicate an expected 45% probability of detecting a miner's signal from a depth of 1,000 ft, a depth which exceeds 903 of the coal mines within the U.S. and a 90% probability at a depth of 500 ft, a depth which exceeds 50% of the mines.

By Bradley V. Johnson

The Bureau of Mines constructed a microminer--a scaled-down (5-by 5- by 11-foot) continuous-mining machine of the drum type with a unique triaxially controlled head--for use in a research program to study the effects of continuous-mining-machine parameters on the generation of respirable dust. This report describes field research with the microminer at the Bureau's Experimental Mine at Bruceton, Pa. Experiments were conducted to determine the effects of depth of cut, rotational speed, and sump and shear rates on the generation of respirable dust. The cutting forces were also monitored and compared with depth of cut. There appears to be a reduction in the amount of respirable dust generated when the depth of cut is increased or rotational is speed lowered, Variation of other machine parameters seems to have little effect on dust generation.

Jan 1, 1975

By J. M. Mutmansky, R. A. Jankowski, M. A. K. Mohamed

"SYNOPSISKnown health hazards associated with the breathing of respirable dusts, particularly silica dust, during mining are becoming a great concern in many parts of the world. The search for effective and low cost dust control methods for underdeveloped countries will help in improving the productivity and keeping the mine environment safe. This article addresses the problem by providing suggestions concerning the easiest and most cost effective methods to control respirable dust in mining and mineral processing operations. INTRODUCTIONMedical BackgroundLung diseases caused by dust in mining operations have been recognized by mankind since the time of the Roman Empire. The writings of Pliny the Younger on natural history reported on maladies associated with dust in mining in the first century AD. However, no significant advances in controlling the lung diseases of miners came about for many centuries. The effects of mineral dusts were further described by Georgius Agricola in his sixteenth century book on mining (Agricola, 1556). After the appearance of Agricola""s book, lung diseases were more readily recognized, but the nature and severity of the ailments associated with mineral dusts could not be readily interpreted.In 1896, the discovery of x-rays by Roentgen advanced the diagnosis of lung diseases and the knowledge of what causes these diseases. In addition, the discovery allowed medical personnel some method of judging the extent and severity of the lung diseases in human beings. During the ensuing years, the term 'pneumoconiosis' became the common term to describe any of the diseases of the lung in which dust particles deposited in the lungs caused fibrous tissue and loss of some of the respiratory function. However, little in the way of social remedies for the diseases resulted until much later. Society was still not ready to act decisively to reduce the causes of lung disease due to the dusty conditions in the work place.Social action against lung diseases did not occur in the United States (US) until the 1930s. At that time, a tunnel driven through a sandstone mountain near Gauley Bridge. West Virginia, caused the death of several hundred workers due to acute silicosis, a severe form of pneumoconiosis caused by silica (Seaton, 1975). Dust conditions in this tunnel were quite bad, causing many of the workers to be subjected to extremely high silica dust concentrations. The severity of the disease in many of the workers became known to the public and prompted the US Congress and many of the states to enact laws to reduce the dust levels."

Jan 1, 1998

By Michael D. Fenton

Bauxite resources were primarily in Africa, Asia, Oceania, and South America. Only five countries combined, Australia, Brazil, Guinea, India, and Jamaica, contained most of the total world reserves available for extraction under current economic conditions and accounted for nearly 80 % of world production of bauxite. World bauxite and alumina production declined and prices for smelter-grade alumina remained below the $200/mt level during 1993 because of growing aluminum inventories on international markets and declining worldwide demand. The United States imported bauxite primarily from Australia, Brazil, Guinea, and Jamaica. U.S. alumina plant capacity remained essentially unchanged throughout 1993, but apparent capacity utilization decreased by the close of 1993. Chromium Most of the world's known resources and reserves of chromite are located in India, Kazakhstan, South Africa, and Zimbabwe. India, Kazakhstan, and South Africa accounted for 73 % of world production of chromite. The two largest producers of chromite, Kazakhstan and South Africa, were in the process of major economic and political change during 1993. South Africa's production and exports of chromite continued to fall during 1993, because of weak international demand and a flood of cheap metal from the former U.S.S.R. and China into world markets. Despite a significant increase in production, South Africa's ferrochrome producers continued to operate below capacity in 1993. Prior o the dissolution of the U.S.S.R., Kazakhstan was a major internal supplier of chromite ore to the U.S.S.R. consumer, but subsequent decline in demand led to a downward trend of chromite production in Kazakhstan and increasing exports to Europe during 1992 and 1993. The United States consumed, about 10% of world chromite ore production in various forms of imported materials. The United States imported nearly one-half of its required chromium contained in chromite ore and chromium ferroalloys and metal from South Africa; the remainder was from the minor producers Turkey, Yugoslavia, Zimbabwe, and others.

Jan 1, 1995

By W. L. Cornell

The Missouri Pb ores are the only domestic Co resource being mined and processed for other metals; therefore, they present a viable short-term opportunity for Co production. Lead, zinc, and copper concentrates are produced from the ore. The Cu concentrate can contain up to 30 pct Co and the Pb concentrate up to 15 pct Co. Since Co is detrimental to the processing of the Zn concentrate; the remainder of the Co is rejected to the tailings. The tailings can contain as much as 50 pet Co originally present in the mined ore. Researchers at the U.S. Bureau of Mines have successfully tested on a continuous basis a process that recovers a bulk sulfide concentrate from mill tailings. The concentrate contains up to one-half of the Co and from 50 to 90 pct of the Pb, Zn, and Cu. Concentrate weight represents 10 pet or less of the total tailings.

Jan 1, 1989

By R. L. Grayson, W. E. Wallace, T. Simonyi, J. C. Harrison

"Application of an SEM-based methodology suggests a reason for past contradictory results on the relationship between quartz and coal workers' pneumoconiosis (CWP). Results indicate that coal seams with the same bulk analysis of quartz may have different amounts of surface-availablequartz. Our research shows that the amounts of pure and surface-available quartz in a respirable dust vary directly with the rank of a coal seam, except in the case where rock materials are mined. The estimated amount of surface-available quartz therefore provides a measure of the quartz-related fibrogenic potential of a respirable dust.INTRODUCTIONFrom our previous work (Grayson, 1991), we have shown that the amount of pure quartz in a respirable coal mine dust sample appears to vary directly with the rank of the seam (using fixed carbon as the basis for comparison), except when a substantial rock parting, roof or floor are mined. Our other work (Wallace et al., 1989) showed that high-silica particles in a clay mine may generally be coated with clay, rendering the quartz core non-available for surface reaction in the lung. The combination of these findings led us to hypothesize that the coating phenomenon may indeed be present in coal mines as well, and that a rank relationship may be present regarding this phenomenon. Thus higher rank coal seams may have more surface-available quartz as well as more pure quartz particles in their respirable dusts. The scientific protocol for testing this hypothesis and the results obtained to date are discussed in this paper. Thus far, there is no reason to doubt that the relationship holds."

Mar 1, 1992

By Leonard J. Prosser, Joseph Cervik, John H. Perry

The Bureau of Mines has developed several techniques for draining methane from coalbeds in advance of mining. Drilling long horizontal holes from an underground location is one such technique, which was successfully demonstrated in the Pittsburgh and Sunnyside Coalbeds. The same technique has now been applied in the Mary Lee Coalbed at Jim Walter Resources, Inc. 's No. 4 Mine, Brookwood, Ala. , where two holes were drilled horizontally--one to a depth of 1,010 feet (308 m) and the other to 540 feet (165 m). The 1,010-foot (3083) hole proved successful in degasifying a portion of the Mary Lee Coalbed. The hole drained methane for 1 year, during which time the initial gas flow of 200,000 ft3/d (5,663 m3/d) declined to 65,000 ft3/d (1,840 m3/d). Total gas production was 40 x lo6 ft3 (1.1 x lo6 m3 ). The gas was of commercial quality, with 98 pct methane and a heat rating of 990 Btu/ft (36.89 Mj/m3). The methane emissions from the faces of the mine section advancing into the degasified zone were reduced by 60 pct. The 540-foot (165-m) hole was terminated prematurely when it became impossible to maintain an open hole. Because of caving, very little gas was drained through this hole.

Jan 1, 1982

By John H. Perry

The Bureau of Mines has developed several techniques for draining methane from coalbeds in advance of mining. Drilling long horizontal holes from an underground location is one such technique, which was successfully demonstrated in the Pittsburgh and Sunnyside Coalbeds. The same technique has now been applied in the Mary Lee Coal bed at Jim Walter Resources, Inc.'s No. 4 Mine, Brookwood, Ala., where two holes were drilled horizontally--one to a depth of 1,010 feet (308 m) and the other to 540 feet (165 m). The 1,010-foot (308-m) hole proved successful in degasifying a portion of the Mary Lee Coalbed. The hole drained methane for 1 year, during which time the initial gas flow of 200,000 ft3/d (5,663 m3/d) declined to 65,000 ft3/d (1,840 m3/d). Total gas production was 40 x 106 ft3 (1.1 x 106 m3). The gas was of commercial quality, with 98 pct methane and a heat rating of 990 Btu/ft3 (36.89 Mj/m3). The methane emissions from the faces of the mine section advancing into the degasified zone were reduced by 60 pet. The 540-foot (165-m) hole was terminated prematurely when it became impossible to maintain an open hole. Because of caving, very little gas was drained through this hole.

Jan 1, 1982

By R. V. Ramani

"In Part 1 of this two-part paper the characteristics of mine disasters and their effects are presented with case studies from coal, metal and non-metal mines leading to an amplification of their causes and opportunities for control. The disasters discussed encompass those which threaten the health and the safety of miners and those which affect the general population. In Part 2 of the paper, which will be published in the November 1995 issue of Natural Resources Forum, the approaches to hazard and disaster control are reviewed with particular attention to laws and regulations to promote health and safety at the workplace, and general welfare in mining communities. Further, a systems approach to disaster control is outlined.The mining industry is one of the three basic industries the other two being agriculture, and wildlife and fisheries. It is the process of mining which makes available the riches of the earth - the energy and mineral resources - to benefit humanity. In fact the progress of the human race through the ages is indelibly attached to prowess in exploiting these riches. The stone, iron and bronze ages are markers not just of a time in history but achievements of monumental proportions in the mining and beneficiation of natural resources. Even in agriculture, the remarkable success stories are associated with the prudent use of mined products to enhance production and productivity. The significance of a thriving mining industry to the wealth and security of a nation is therefore unquestioned.Unfortunately, the public's image of the mining industry is often associated with the mining disasters which receive wide coverage in the local and national media. Mine disasters command tremendous attention because of their infrequent occurrence and the extent of human suffering involved. Whether it is an explosion or a fire, or the opening or closing of a mine, the lives of people are touched by the personal and societal impacts of these events.Courts of inquiry of mining disasters have often concluded that the disaster situation was ever present and could have been detected with diligent search. In addition human error has been identified as one of the most frequent immediate causes for the precipitation of the disaster. For the most part, then, mining disasters are caused by man."

Dec 1, 1996

By L. A. Readdy

No text. A set of geophysical well logs for U.S. B.M. Pilot Hole "X", Piceance Creek Basin, Colorado.

Jan 1, 1977

By Mark S. Stagg, Virgil J. Stachura, John W. Kopp, David E. Siskind

The Bureau of Mines studied airblast from surface mining to assess its damage and annoyance potential, and to determine safe levels and appropriate measurement techniques. Research results obtained from direct measurements of airblast-produced structure responses, damage, and analysis of instrument characteristics were combined with studies of sonic booms and human response to transient overpressures. Safe levels of airblast were found to be 134 dBL (0.1 Hz), 133 dBL (2 Hz), 129 dBL (6 Hz), and 105 dB C-slow. These four air- blast levels and measurement methods are equivalent in terms of structure response, and any one could be used as a safe-level criterion. Of the four methods, only the 0.1-Hz high-pass linear method accurately measures the total airblast energy present; however, the other three were found to adequately quantify the structure response and also represent techniques that are readily available to industry. Where a single airblast measuring system must be used, the 2-Hz linear peak response is the best overall compromise. The human response and annoyance problem from airblast is probably caused primarily by wall rattling and the resulting secondary noises. Although these will not entirely be precluded by the recommended levels, they are low enough to pre- clude damage to residential structures and any possible human injury over the long term.

Jan 1, 1965

By R. V. Ramani, K. V. K. Prasad

"Solution of most engineering problems requires, in addition to vast ·numerical calculations, substantial use of practical judgement and expertise. With advances in applied mathematics and computer technology, the numerical aspects of problem solution have reached a considerable level of maturity; However; it is only .recently that approaches like the expert systems methodology have been developed to ·incorporate the Judgemental aspects as well. For rapid development and prototying of expert systems, expert system building tools or ""shells"" have become widely available. For the expert system developer, identification of the key characteristics of the problem domain and selection of the right expert system tool are of crucial importance. In this paper, the important attributes required in an expert system shell for use in the development or a mine ventilation planning expert system are discussed. These attributes are general in that most engineering problems in mining would have these requirements. Also, the results of an exercise undertaken to evaluate commercially available shells for application to mining engineering problems are presented.INRODUCTIONExpert systems (ES) are interactive computer programs which use high quality specialized knowledge in some narrow problem domain to solve complex problems in that domain. These complex problems lack structured and/or standard ways of solution and involve substantial use of subjective and experience based knowledge. One of the first expert systems was MYCIN, developed in 1974, in which subjective and heuristic knowledge of expert physicians was used to diagnose infectious diseases and provide antimicrobial therapy (Buchanan arid Shortliffe, 1984). Since MYCIN, expert systems applications have appeared in other areas such as mineral prospecting (Gaschnig, 1982), configuration of computers (McDermott, 1982) and structural engineering (Bennett and Englemore, 1979)."

Jan 1, 1989

By F. Varley

Researchers from the National Institute for Occupational Safety and Health (NIOSH), in cooperation with mine operators, conducted a study of heat stress exposures among mine rescue workers in underground mines. Mine rescue workers face extreme heat loads as they enter hot and poorly ventilated environments, particularly when they are wearing breathing apparatuses. The burden of wearing a closed-circuit breathing apparatus (CCBA), the inability to drink fluids for extended periods of time, and the potential for ventilation disruptions and fires combine to increase the risk of heat illness during a response to an emergency. In this research, ambient environmental conditions and heat strain indicators were measured using conventional ventilation monitoring tools during mine rescue training exercises. Heat strain was measured with an ingestible temperature-sensing pill that measured core temperature continuously. In addition, a heart-rate monitoring chest strap was used to indicate physical strain resulting from physical activity and heat. Both core temperature and heart rate data were transmitted to a remote recorder worn by a rescuer and time-stamped. Team activities were also observed to determine the contribution of work rate to a person’s total heat load. The effectiveness of several engineering controls, such as cooling the air inhaled by rescuers through an apparatus, wearing cooling vests, and supplying water through the CCBA masks, were investigated. Administrative controls, such as limiting the duration of exposure and controlling the work rate through forced-rest regimens, were also evaluated. Results to date are discussed, and tools for evaluating team condition and estimating the length of time it would be safe for rescuers to work are proposed.

By Scott Turner

Since my whole life has been spent in the mining business , I naturally tend to address my remarks particularly to the newly- graduated mining and metallurgical engineers among you . To a certain extent , all forms of engineering principles are involved in the training of the mining engineer , and most sorts of engineering are certainly utilized by him , so that every one of this graduating class is concerned with the field I propose to discuss . The fact that , beginning with to - day , you will always be styled engineers , indicates that you have passed successfully through preparatory school , and have survived the hard grind of the technical college . One object of your training here has been to instruct you in accurate , close , and clear thinking . Your minds have been taught to act directly , calmly . and always to the point . By now , you should know how to get facts , look far , and think through . You are supposed to be willing to recognize and adopt sound engineering principles and practices , in so far as they are known to you , and to furnish character , ability , and devotion to your calling . Some of you may have had a general college course before coming here to specialize in engineering . Where that has been possible , I hope it is the case , since a liberal educational course tends to make the alumnus more flexible and adaptable than the purely scientific graduate. The broader education enables one to change , with less serious loss , from one job to another; ready adaptability is a great asset ; the engineer should be capable of much more than a single special task . The necessary preliminary training for a professional occupation is intellectual in character , involving knowledge , and to some extent learning , as distinguished from mere skill . The well -balanced engineer is expected to embody a happy combination of theory and fact , of pure science and material reality ; experience shows that he is apt to give a good account of himself , once he gets the chance . For the long pull , the importance of unquestioned integrity can not be overemphasized . Leaders of big business sometimes have need for a man as agile and unscrupulous as a cat on a back fence ; on occasion , they may have to employ brilliant , smart , spectacular , and crafty people , but when the special purposes for which such men are hired have been accomplished , they are no longer wanted . Given natural health , intelligence , ability , and adequate training , probably the characteristics most admired in the young employee are steadiness , dependability , and loyalty . The last is the best . If you can not be simple , direct , and faithful in your dealings with your administrative superiors , no one will want you for long . I believe these points are of primary importance to the young engineer . Your groundwork must be right before you can get far . These personal characteristics are what eventually determine your relations with men and affairs . They are vital in the human engineering which may be a large part of your work .

Aug 1, 1932

By John B. Umhau

In 1930 , 65,448 long tons of virgin or primary tin were consumed by 1,292 establishments in the United States , representing about 91 per cent of the total consumption as computed from imports , exports , and stocks at the beginning and the end of the year . The reported consumption was equivalent to 38 per cent of the world's tin production in 1930 , estimated at 171,000 tons , and was 12 per cent less than the 74,369 tons consumed by 1,307 establishments in 1928 . Decreased consumption of new tin in 1930 ás compared to 1928 was a reflection of the general industrial depression . All of the tin- consuming industries showed substantial decreases except tin plate and terneplate , white metal , and tinning , which showed small tonnage increases aggregating only 1,200 tons . The largest tonnage decrease was in the use of new tin in babbitt which declined 33 per cent in 1930 as compared to 1928. This was largely attributable to the decreased production of automobiles and trucks , which was 24 per cent lower in 1930 than in 1928. Percentage decreases in other important tin- consuming industries were as follows : Solder 18 per cent , bronze 19 per cent , tin foil 40 per cent , chemicals 23 per cent , tin oxide 44 per cent , and type metal 46 per cent . The distribution of the amount consumed by various uses during 1927 , 1928 , and 1930 is shown in table 1 . Consumption studies indicate the fact that variation in tin consumption from year to year parallels the fluctuations in demand for the already wellestablished tin products . For example , the manufacture of motor cars and trucks3 required only 11,000 tons of tin in 1930 compared to 19,000 tons in 1928 ; the canning industry continues to require the greater portion of the tin plate and much of the solder . Recently developed industries , while affecting total consumption of bearing metals , solders , etc. , to some extent , have made little change in the relative importance of these commodities as consumers of tin .

Jan 1, 1932

By Jan M. Mutmansky, Christopher J. Rise

"One of the most serious long term health problems associated with underground,mining is Coal Workers Pneumoconiosis (CWI'), more commonly known as Black Lung Disease. It occurs in some coal workers, normally after 15 or more years of exposure to coal mine dust, and leads to a variety of respiratory problems. Two types of pneumoconiosis are recognized simple CWP, which has been estimated to affect 6.9 percent of miners and is a condition that does not impair the miner's ability to work nor reduce life expectancy; and a more severe form of black lung (called progressive massive fibrosis) that occurs in about one percent of the cases and results in severe lung damage.Although the relationship between coal dust and CWP has long been recognized, detailed knowledge of the relationship is insufficient for setting up authoritative guidelines to reduce the health risks for those employed in dusty,underground environments. CWP is not only a health problem for workers that causes considerable distress, it is also a very expensive problem the total annual costs associated with CWP approach two billion dollars.As part of its efforts to combat CWP, the U.S. Bureau of Mines in 1983 established a Generic Mineral Technology Center to carry out basic research into all aspects of respirable coal dust:— control of dust generation — the behavior of dust in the mine — characterization of dust particles interaction of dust and lung— the relationships among dust generation and mobility and the mine environment, geology, and seam characteristics,Penn State, West Virginia University, the University of Minnesota, and the Massachusetts Institute of Technology are involved in this research, which is administered from the Department of Mineral Engineering at Penn State.Our work is one of the seven projects to be conducted at Penn Slate. We are concerned particularly with the characterization of dust and its relationships with the mine environment, and our main goal is to establish standard procedures for describing and measuring these variables.Coal DustCoal dust is a very complex material that varies greatly in chemical and mineralogical properties. Moreover, it is not the only constituent of respirable dust in the mine. When a coal seam is mined, it is inevitable that rock particles other than coal are included in the material. This rock comes from the mine roof, the floor, and the partings and inclusions within the coal scams. Since the roof and floor strata, the partings and inclusions are often stronger than the coal, mining them frequently causes more dust than mining the coal itself. One of the objectives of our research is to find the relationships between a specific coal's characteristics before it is mined and the respirable dust characteristics after it is mined. We are particularly interested in the size distribution of particles, the chemical properties, and the mineralogical properties."

Jun 1, 1988

By A. B. Hooker, E. J. Coggeshall

"INTRODUCTION Ignitions of gas at the coal face when a blast is fired electrically are often a tributed to the explosive; but sometimes the ignition cannot be explained satisfactorily in this way-in fact, ignitions have occurred when the detonator has failed explode.The possibility of such electrically by sparks from the blast between poorly insulated leading wires and detonator leg have been recognized. Several countries have provided safe types of single-shot blasting units; some have permitted the use of larger multiple-shot blasting units provided each unit is equipped with a time-limiting switch that prevents unnecessarily long application of voltage on the leading wires after the shot has occurred, the assumption being that the firing line will this be dead before damage to the wires and subsequent sparking can take place. An extensive research was made by a French commission relative to the characteristics of electric detonators and methods of firing. Along other tailings they investigated the probability of ignitions by sparks across the leading wired at the face, also the time and duration of the various events in blasting, such as ignition of the detonators, movement of the coal face, and application of firing current. They suggested, as a means of eliminating or reducing tilt possibility of gas ignitions from the blasting unit, that the timing switch of the blasting unit be designed to disconnect the blasting"

Oct 1, 1934

By Sean Gallagher, Rhys Llewellyn, Jay Mattos

This paper contains the results of an examination of accident, injury, employment, and production information reported to the U.S. Department of Labor's Mine Safety and Health Administration (MSHA) and provides information on some of the measures longwall mine operators are using to prevent accidents In all industries, technological advances play a key role in determining those who will survive as competitive participants in an increasingly global marketplace. While mining is among the most basic of industries, technological change is neither unfamiliar nor unwelcome to miners. Historically, technological advances in mining, particularly coal mining, have tracked closely with fluctuations in demand. In the early 1900's, coal accounted for more than three quarters of all the fuel consumed in the U.S. To meet this tremendous demand, underground cuffing machines were introduced, resulting in faster, more efficient coal extraction. Transporting coal to the surface, however, remained labor intensive. In the 1920's, nearly all underground coal was still being hand loaded. Demand for coal then declined as the price of oil, natural gas, and electricity became competitive. In the late 1930's and throughout the duration of World War II, coal demand and production was high. By 1940, more than half the coal mined was being mechanically conveyed to the surface. In 1948, the continuous mining method was introduced in the U.S., further accelerating the extraction process. By the 1950's and 1960's, however, coal production again declined as railroads converted to diesel fuel and gas and oil provided a larger share of the home heating market. Underground coal mines required even more mechanization to remain competitive as an energy source. The first longwall system was introduced in 1960. By 1995, longwalls were producing more than 189 million tons of clean coal annually, surpassing continuous mining production for the second straight year. The mining of coal and other materials has not come without a huge loss of life and considerable human suffering. More than 103,000 workers died from injuries in U.S. mines in the last 85 years. Between two and three thousand miners died each year from the turn of the century until 1931, many from underground fires and explosions. The U.S. has witnessed a tremendous drop in fatalities in underground coal mines. Credit for that is due to safety inspections and enforcement activities, better safety awareness and practices among management and labor, improved ventilation, the use of safer equipment, and increased mechanization which removed many miners from the hazards at the face and also reduced the size of the mining work force. There is little doubt that longwall mining has greatly increased underground coal mine productivity. The degree to which longwall mining has contributed to a safer work environment for underground miners is more difficult to ascertain.

By G. R. Hopkins

One of the largest items in the expense of operating a refinery is the cost of the fuel used in distillation and for miscellaneous purposes such as in the heating of buildings and in the generation of electricity, On a B. t. u. basis, the average refinery consumes approximately one-tenth as much fuel as it produces. Theoretically, the fuel consumption at refineries should be much smaller than this, but furnaces can riot be designed to be 100 per cent efficient' and, in addition, a large part of the waste heat is low-temperature heat which would not pay for the expense of recovering it. Annual surveys of fuel consumption at refineries have been made by the United States Bureau of Mines, beginning with 1925. During the 5-year period, 1925-1929, the refineries made steady progress in fuel economy. This is evidenced by the Computed figures of heat requirement Per barrel of crude oil refined, which show a decline from 829,000 B. t. u. in 1925 to 639,000 B. t. u. in 1929 (see fig. 1). In 1930, however, the trend in fuel economy was reversed and the quantity of heat utilized in refining the average barrel of crude oil rose to 672,000 B. t. u. There were undoubtedly a number of reasons for the apparent decrease in fuel economy at refineries in 1930, chief of which were the tendency to carry the distillation farther instead of merely topping the crude and a gain in the consumption of waste oils, such as acid sludge, which in actual practice yield less heat per unit consumed than has been theoretically assigned to oil. The consumption of natural as fuel at refineries has declined since 1927, but this has been more than compensated by a rapid increase in the use of refinery or still gas. The total consumption of oil as refinery fuel in 1930 was not much below the 1925 total, but the consumption of coal has declined rapidly, so that in 1930 liquid and solid fuels contributed only 56 per cent of the total heat units- utilized at refineries as compared with 77 per cent in 1925 (see fig. 2).

Jan 1, 1931

By JOSEPH F. CULLEN, Dorsey A. Lyon

In connection with its investigation looking to the prevention of waste and the increase of safety and efficiency in the mineral indus- tries the Bureau of Mines has undertaken a study of the possible uses of the electric furnace in metallurgy. This bulletin presents a com- pilation of such data as seem to be useful for the information of persons who may be interested in the matter. In the application of electricity to metallurgy three kinds of processes are involved, namely, mechanical, thermal, and electrolytic. Under the mechanical application of electricity come those proc- esses of dressing and concentrating ores that are known as either electrostatic or electromagnetic processes. In electrothermic processes the current is used as a source of heat. The fundamental differences between the various types of electric furnace that are at present in commercial use relate to the manner in which the electric current is applied, as may be noted by reference to that part of this report in which the subject is discussed. In electrolytic processes the electric current is used for depositing metals from solutions. The process may be conducted in one of the following ways: (1) The material to be treated may be put into solu- tion and then electrolyzed, the material thus treated forming the electrolyte; (2) the material to be treated may form the anode or be placed in contact with the anode; or (3) the material to be treated may form the cathode or be placed in contact with the cathode. This report treats of electrothermic processes, with the possible exception of those for the reduction of aluminum from its ores. Moreover, of the processes used in the so-called electrochemical in- dustries only those for the reduction of an ore to metal, or to a com- pound of the metal that is of value in itself, or is an aid in metallurgical work, are here discussed.

Jan 1, 1914