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By James R. Coldwell

Mining and processing cost analyses were conducted by the U.S. Bureau of Mines on stratiform zinc-lead-silver, coal, and stratiform barite deposit types that are found in the Colville Mining District. Reserves and gross revenues which would allow these deposits to be minable were modeled. A 15% Discounted cash-flow rate-of-return economic threshold was selected as the minimum acceptable return on investment for the three deposit types. The economic modeling indicated combinations of grades and tonnages for stratiform sulfide deposits that could be economically viable for orebodies ranging in size from 25 to 130 million metric tons. The gross revenues for a surface mine range from $200/mt for a 5,000 mtpd operation using the proposed South corridor to $140/mt for a 17,000 mtpd mine using the proposed North corridor. The economic modeling indicated underground coal mining was subeconomic for deposits ranging in size from 42 to 250 million metric tons. The required gross revenues ranged from $300/mt for a 2,200 mtpd mine to $21 D/mt for a 13,000 mtpd mine. The economic modeling indicated supplying projected in-state barite demand was subeconomic for the three seasonal surface mines modeled. The required gross revenues ranged from $600/mt for a 90,000 mtpy mine to $840/mt for a 6,000 mtpy mine.

Jan 1, 1995

By Jr. Allan

"Although the advantages of large-capacity air receivers for underground mines are plainly evident from published information about various installations in the United States and abroad, details of their construction are not generally known in this country., Ordinary present-day air-compressor installations servicing mining machines are designed to supply air at a specified pressure in sufficient quantity to meet the peak demand of the mine,2/ although this demand may exist for only a few minutes out of 24 hours and, as usually happens, eventually exceeds the capacity of the compressor. Most of the receivers provided with these compressors (to a certain degree of standardi¬zation) are capable of storing a volume of air approximately equal to that compressed in 1 minute by the machine.3, 4/ As a result, during peak-load periods the compressor operates at full load capacity without maintaining kick-off pressure. At other periods of the work cycle, production of compressed air is intermittent.At least one large mine5/ has adopted large-capacity receivers to reduce wear on its air-compressing system caused by the sudden demand of peak loads. Under the old system, the compressors jumped suddenly from half speed to full speed; boilers furnishing steam to the compressors were taxed heavily to provide the increased requirements of power; and machines using the air, among which were four large hoists, were required to operate at 65 pounds per square inch rather than at the 90 pounds per square inch for which the compressors were regulated. Operation of air machines, especially drills, at pressures lower than those for which they were designed decreases their efficiency and increases maintenance costs. In addition, air that comes directly from the compressors has had little opportunity to cool and dry enroute.6./ As a result, quantities of compressor lubricant and water are carried into the machines that use the air. When expansion occurs in the cylinder or turbine of such engines, the temperature of the air drops, and this oil and water is precipitated. The water washes away lubricating oils in the machine, causing poor performance and high cost of maintenance; the compressor oil, in addition to being a poor lubricant for compresed-air engines, exerts a corrosive action on gaskets and rubber hoses.7/Reduction of peak demands on air compressors by large receivers lowers power costs by establishing more nearly constant load factors,8/ and in some cases by permitting the use of smaller compressor capacity.8,9/Load factor is the ratio of average demand to maximum demand; a low load factor costs money.10/Elimination of high-peak demands raises the load factor by making the average and the maximum demand more nearly equal. Further savings may be made possible by large receivers where their use permits charging to be done at night in regions having lower power rates during that period.11/Where ordinary receivers are used, compressor breakdowns cause immediate work stoppages in the mine owing to lack of air. Similarly, the capacity of a large receiver has been known to permit uninterrupted work in the mine until the compressors have been returned to service.9/Large-capacity receivers, either steel-tank or underground rock-chamber, offer a practical solution of many existing problems by providing a sufficient reserve of compressed air within the pressure range required for efficient operation of machines to level off peak demands on the compressor. The com¬pressors operate when the demand has reduced the pressure in the receiver below the regulating pressure and until all air used from the receiver has been replaced. It has been found possible in at least two mines,8.9/ one of which the author has visited, to entirely eliminate one compressor and to obtain more efficient performance from the remaining one by the construction of an underground coal-chamber receiver.8/"

Jan 1, 1950

By Paul T. Allsman

Iron-ore deposits in southwestern Utah, as the major source of iron ore for western steel plants, were investigated by the Bureau of Mines in 1942-45 in cooperation with property owners and operators and with the assistance of the United States Geological Survey with a view to determining and extending the known reserves. The factual data resulting from that project were presented in a previous report and in a report on the geophysical surveys now in course of publication. The present report has been prepared in response to expressed public interest in the ore reserves of Iron County. Mining began in the district in 1871} but. did not become important until 41 1923. From 1923 to 1946, inclusive) production totaled 10,139,500 long tons. In 1945 the district yielded 1,931,749 long tons containing 52.84 percent iron; in 1946 the corresponding figures were 1,317,671 and 53.75. The deposits lie .in a narrow, 23-mile long belt extending northeasterly from Washington 'County into Iron County along a line of mountains, chief of which are Iron Mountain, Granite Mountain, 'and Three Peaks in Iron. County. The deposits are hematite-magnetite bodies, chiefly in limestone near its contact with the monzonite of the mountain masses, but with a few important veinlike bodies in the monzonite or at the contact. They range in size from small pods to several millions of tons, and in depth from surface or near-surface to a known maximum of 1,300 feet:

Jan 1, 1948

By Emory Smith

The preface of the United States Bureau of Mines Manual of First Aid Instruction contains the following paragraphs: One of the most important inquiries that Congress has authorized the Bureau of Mines to conduct relates to health condi- tions among those engaged in the mineral industries. Investigations made early with a view to bettering these conditions demonstrated the need of prompt care of injured miners, as, under the difficulties inherent to mining and other mineral industries; wounds seemingly unimportant, if not treated promptly, may become infected and possibly cause permanent crippling or even death of the porach. In the past many seriously injured persons have been treated by fellow workers ignorant of approved means of treatment and transportation and have been handled in such a manner as to cause suffering and to accentuate injuries to such a degree as to bring about permanent disablement. Accordingly, the need of general instruction in first aid became apparent. It must be recognized that the conditions in and about the mines, mills, smelters, quarries, oil fields, etc., usually present difficulties not found in large industrial centers where experienced surgeons are available and hospitals close at hand. Many mines are isolated and, when an accident occurs several miles underground, there may be a serious lapse of time before the injured person can be brought to the surface and taken to the hospital or given attention by a sur- geon who may have to come a long distance. Under such conditions it has been frequently demonstrated that, if effective first aid is not given, the injured person may die or become permanently crippled... First-aid instruction has been found to be an excellent aid3in pre- venting accidents. In addition to the immediate relief of injured persons, it has been found that most persons while in the act of practicing dressings for

Apr 1, 1931

By I. AITKENS

The opal , long in disfavor because it was considered " unlucky, " has become much more popular in recent years . For variety and beauty of color the precious opal is without a peer . These colors do not come from any chemical constituent but are produced by structural peculiarities , which in varying degrees deflect the light rays entering the stone and give a prismatic play of hues .

Sep 1, 1931

By Raymond B. Ladoo

Toward the end of 1920 , the average grades of ground feldspar offered to the pottery industry were so poor and so generally unsatisfactory that many of the largest consumers decided to take active steps for their own protection . A few of the potters made arrangements to grind their own feldspar , while others asked the Bureau of Mines to make a detailed study of the problem and to suggest methods of improvement . Accordingly such a study was undertaken, the partial results of which are outlined in this preliminary report . The outstanding features of the present feldspar industry which are of interest in this connection are stated below. (1 ) Many grinding companies do not own or control all or even a major part of their sources of crude material , but buy in job lots from many sources . (2 ) There is great need of more adequate engineering and chemical control over mines and mills . ( 3) ~ Out of date , inefficient methods and equipment for mining and grinding are in common use . (4) Little or no cooperation exists between feldspar producers , but on the contrary many feldspar companies are exceedingly secretive . This tends towards (a) preservation of obsolete methods ; ( b ) want of knowledge of the essential features of production , market requirements , and the relation between total milling and consuming capacities of the country; ( c ) inefficient and often mistaken trade practices ; ( d) unprofitable and even ruinous competition in dull periods . (5) The small size of many feldspar deposits precludes maintenance of an efficient organization at each individual mine . ( 6 ) Many of the best deposits of feldspar situated close to railroads are becoming depleted , which results in gradual lowering of grades , and increase in cost for better grades . (7) There is a lack of exact mowledge of the ceramic properties and behaviour of feldspar by some consumers , which results in ( a) purchase of feldspar on the basis of price alone , thus encouraging low production costs at the expense of quality , and ( b) inefficient and expensive cross- hauling of both crude and ground feldspar .

Jan 1, 1922

By C. P. Lazzara, Y. Miron, A. C. Smith

This report presents a U.S. Bureau of Mines study to identify the causes of self-heating events beneath the floor of a deep underground coal mine. Mine samples from both heated and unheated areas were examined by various techniques, including visual, microscopic, thermal, chemical, and instrumental tests. The combined results led to the conclusion that pyrite (FeS2) oxidation was the prime cause of the beatings. However, adiabatic oven tests of selected samples did not indicate the effect of the pyrite on the self-heating process, probably because of the experimental conditions. A fast, simple procedure to assess the concentration of pyrite in the mine samples was developed, utilizing the reactivity of the sample with an aqueous solution of hydrogen peroxide (H2O2)

Jan 1, 1992

By R. M. Santmyers

This paper represents one of a series of digests of foreign mining legislation that is being prepared in advance of a general report relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries . This interpretation of the mining legislation of Tunisia was prepared from a copy ( in French ) of the Mining Decree of Tunisia promulgated December 29 , 1913 , by the Resident General of France in Tunisia and effective January 1 , 1914. It is released subject to correction and amplification , if necessary , by the proper American diplomatic and consular officers , to whom it will be referred through the courtesy of the Department of State .

Mar 1, 1933

By W. M. Weigel

Langley is about nine miles north of Augusta, Georgia., on the Sou them :l;.ilv1ay. According to the South Carolina. Geological Survey, tr.e district is known a.s tr. Horse Creek and Town Creek sub-areas of the Aileen or Savannah River Area f the South Ciil.Z'olina Coastal Plains. The geology and origin of the clays 3l"e Jscribea in a bulletin of the South Carolina Geological Survey (Series 4, Bull, l; "A Preliminary Report on Cl.:.ws of South Carolina.-), According to this report, i.he clays are sedimentary kaolins, in the Mid.dendor! and Hamburg series of the Cretaceous Age.

Aug 1, 1922

By Scott Turner

I have been asked to speak briefly about recent progress in the mining industry of the United States, and to touch on the general advancement of en- gineering science as applied to mining. By recent, I shall mean within the past 20 or 30 years. Such a period includes a great many of the changes which are of particular interest to the present generation of engineers, and the undergraduates of today will hardly turn back farther than the beginning of the present century in their study of develop- ment of methods and processes. Also, my own professional life spans this period, and I have seen or have been aware of most of these developments as they were taking place. In my review of developments, for the sake of simplicity and clarity, I shall deal separately with improvements in metal mining, coal mining, mechanical and electrical machinery for mines, metallurgy, petroleum engineering, and safety practices. Under each of these headings I have set down what appear to me to be the outstanding changes brought about during the past 2 or 3 decades. Other points will occur to other engineers; I do not represent that the following re- view is complete; it is only intended to be suggestive. In general, improvements in mining and metallurgical practices have come gradually, the charges being effected little by little, simultaneously in widely scattered places, and through the experience and inventive genius of many men. These changes have has small beginnings, and are generally the cumulative result of many steady and unsensational progressions, which still continue. What we today might be inclined to consider the culmination of a series of betterments in mining is, of course, but an instantaneous phase of developments which will continue in the future at even a more rapid pace than they have in the past. We are looking at but a flesh of a moving picture, with an endless reel to come after we finally leave the theatre. Behind all the changes in the mineral industry, the driving force has been the increasing demand of an expanding population for more metals and minerals with which to advance civilization. More people, with an increasing per capita consumption, together with the exhaustion of the richer but smaller, and more

Oct 1, 1930

By S. H. Ash

Unusual mining conditions prevail in the State of Washington because the majority of the coal seams lie on extra steep dips, and the roof and floor of the seams are of such a character as to require an excessive amount of timber- ing. The seams as a rule give off a considerable amount of methane, which makes good ventilation imperative. Due to physical conditions, supervision is costly and travel about the workings is difficult. Because of the facts stated, the accident rate has been above the average, and for some time considerable thought has been given the idea of making promotion of safety in and about the mines a responsibility to be shared equally by the employees and the management. With this idea in mind the legislature of the State of Washington, turing March, 1927, passed laws providing that safety committees be selected to function at the coal mines of the State and at the same time recognizing the fact that first-aid education is an integral part of any safety movement; legislation was passed making it mandatory to have all persons in and about the ines trained in first-aid administration. The provisions of the State mining law3 are as follows: "In every mine a general safety committee shall be selected, composed of the mine superintendent or manager of mines, one man selected by the employees or any association of employees in or around said mine, and a third member selected by these two. "The general safety committee shall elect one of the members to act as chairman and one to act as secretary. The duties of the chairman shall be to preside at all meetings of the general safety committee, enforce its rules and regulations and see that its business is conducted in a prompt and business-like manner. The secretary shall keep an accurate written record of the proceedings of all meetings, conduct its correspondence and post notices of regular and special meetings and other matters pertaining to safety. The duties of the general safety committee shall be to investigate all serious and fatal accidents; make bi-monthly.

Jun 1, 1930

By Paul M. Tyler

Syria is a federation of States under French mandate , comprising the Republic of Syria , the Lebanese Republic or Great Lebanon ( Grand Liban ) , the State of the Alouites , and the Djebel Druse Territory . Beirut is the center of government for the whole area , about 60,000 square miles . Syria is essentially an agricultural country . There is little manufacturing ; and with the exception of the production of asphalt and salt , the mineral industries have not yet risen to commercial importance . Whether this condition is due to a dearth of workable deposits or merely to insufficient exploration is not apparent . The mineral resources , as reported by various authorities , include asbestos , asphalt rock , bitumen , chromite , coal , copper , gold , gypsum , iron , lead , magnesite , manganese , marble and other building stones , nickel , ocher , pandermite ( a hydrous borate of calcium) , petroleum , phosphate rock , pyrite , salt , silver , sulphur , tin , and titanium ( ilmenitic beach sands ) .

Mar 1, 1933

By Richard L. Sayrs

The Idol zinc prospect, formerly known as the Comstock, was examined by Harold B. Ewoldt, a Bureau of Mines' engineer, accompanied by Deane F. Kent of the United States Geological Survey on July 22, 1943. Previous to that time, the Geological Survey had contoured and studied the area. As a part of the war minerals program, further investigation of the area was recommended. The Dalton property, a mile and a half northeast of the Idol property, was examined during the progress of the work at the Idol, and it was decided to include this property also in the project. From February 7, 1944, to May 16, 1944, six holes totaling 2,739 feet were diamond-drilled on the Idol property and eight holes totaling 1,850 feet were diamond-drilled, and three pits channel sampled on the Dalton property. The drilling showed sphalerite to be sparsely distributed through a 100 foot thickness of the Kingsport member of the Knox dolomite.

Jan 1, 1949

By Oliver Bowels

Many inquiries are received by the United States Bureau of Mines for the names of elementary books on geology, mineralogy, methods of identifying minerals, prospecting, and similar subjects. In response to this demand the following brief bibliography has been prepared. As many of the inquiries are received from those who have limited technical knowledge of the subjects involved, the bibliography includes the simpler texts which present the subjects in nontechnical language. Other texts contain glossaries which define the technical terms used. A short note following the title indicates the character of each book, the number of pages, and the price. Thus, elementary mineralogists or geologists, prospectors, mineral collectors, nature students, or travellers may select the texts that best suit their requirements and their capabilities. To supply the needs of more advanced students, quite a number of the standard texts used in schools and colleges are included in a second group. A short list of books on economic geology and mineralogy has also been added.

Jan 1, 1929

By M. L. Davis

The principal causes of many methane-gas explosions that have occurred in anthracite mines, especially in thick pitching veins, during recent years can be traced to lack of a satisfactory method of testing for such gas in areas adjacent to those in which blasting is to be done or other sources of ignition introduced. As coal-mine officials and inspectors are required to make examinations for methane in all accessible open workings, including high places, and permissible flame safety lamps have been used almost universally for making these examinations, considerable difficulty has been experienced in proper testing of atmospheres at elevations beyond the normal reach of the examiner, and resultant explosions have often indicated perfunctory tests. The accepted practice of testing for gas in voids or high places generally consists of raising a flame safety lamp, suspended from the end of a long drill, stick, or pipe, into the atmosphere to be tested. Disadvantages noted are: Action of the flame within the lamp cannot be seen readily when the lamp is more then 18 inches overhead, the flame will not be extinguished when less than about 4-1/2 percent of methane is present, and indications of small percentages of methane within the lamp may disappear entirely while the lamp is being lowered slowly to view; the examiner must usually be exposed unnecessarily to falling material; and the lamp may fall and be broken. Thus, the need for a more reliable, safe method of testing for gas in out-of-reach places is apparent. Several electrical methane detectors, tested and approved by the Bureau of Mines, have been used satisfactorily, though infrequently, for making the aforementioned gas tests. Some of these detectors employ a rubber aspirator bulb and rubber tubing of suitable length to draw the atmosphere from high places through and over energized parts of the detector. However, the original expense, susceptibility to damage, and awkwardness of tarrying these instruments in steep-pitch workings has precluded their general use in everyday examinations. Although not as efficient as the electrical detector for determining small percentages of methane or as reliable because of the limitations imposed by oxygen-deficient atmospheres, the modern per¬missible flame safety lamp can, it is believed, be used safely with the rubber aspirator bulb and tubing to greater advantage and with comparative reliability in testing for gas in out-of-reach places. Slight reference to this method of introducing air into a safety lamp is made in a Bureau of Mines publication of l921,2/ and it is quite possible that the method has been utilized in some manner by individuals in American mines during the intervening years. A similar method was used in connection with a nonpermissible Wolf flame safety lamp in at least one coal mine in Japan before World War II. A major change in the construction of this lamp would bar its approval by the Bureau of Mines. An American adaptation of the Wolf lamp, developed

Jan 1, 1954

By M. D. Schlesinger

Experimental data for coal hydrogenation are presented to show that when a vehicle oil produced from coal is present, coal is hydrogenated to the same high conversion whether molybdenum catalyst is impregnated on the coal or intimately mixed with the slurry. Differences in product distribution could be related to the severity of operating conditions. No minimum mixing time was established, but 2 hours was sufficient. Longer periods of mixing, to 14.75 hours, had no effect on the results. The hydrogenation conditions were in the pressure range of 8,500 to 10,000 p,s,i. at 400° to 500° C. Most of the experiments were made in duplicate. The results were obtained with molybdenum concentrations of 0.01, 0.1, and 1 percent. Al the mentioned pressure range and a time at temperature of 15 to 60 minutes, coal conversions higher than 98 percent were obtained.

Jan 1, 1962

By H. H. Fukubayashi

This Bureau of Mines report describes the development of a pyrometallurgical process for the recovery of the zinc and lead contained in brass smelter flue dusts, which constitute a recycling or disposal problem. Tests on brass flue dust from several sources were made in a quartz tube, heated by an electric furnace to temperatures as high as 1,050° C. The dusts were mixed with carbon and heated in an oxygen-free atmosphere. It was demonstrated that 98 pct of the zinc and 12 to 25 pct of the lead, both in the metallic state, could readily be removed from the dusts. It was also found that 75 pct of the zinc could be recovered, with less than 0.1 pct of the lead, in the absence of chlorides. Pelletization techniques were investigated and 0.6 inch pellets were found to be optimal. Pelletizing results in a tenfold reduction in volume.

Jan 1, 1974

By J. B. Gayle

Numerous investigators have studied the addition of inert4 substances to coking blends. Generally, the results have yielded trends applicable only to the particular coals and inerts studied. Recently, somewhat more general results were obtained for cokes produced from blends containing added inerts, using the sole-heated oven. The present investigation represents an extension of this work to include a wider range of inerts and to determine the applicability of the various conclusions to cokes produced with the Tuscaloosa oven. The results indicated that an increase in dry-coal charge density of 1 pound per cubic foot (p.c.f.) caused a corresponding change in the hardness (1/4-inch tumbler index) of Tuscaloosa oven cokes of 0.9 percentage points. This value compares favorably with the value of 0.7 determined previously for the sole-heated oven and Bureau of Mines-American Gas Association (BM-AGA) retort.

Jan 1, 1961

By G. R. Palmer

The Bureau of mines evaluated the elution of uranyl carbonate from a strong base resin with a mixed carbonate eluant in a fluidized system. The system consisted of a multiple-compartment ion-exchange (MCIX) elution column with a continuous flow of solution, except for short periods when the resin increments were withdrawn. The exchange of uranyl carbonate from the mill-loaded strong base resin with an eluant composed of 1.0 [M] NaaCOs plus 1.0 [M] NH4HCO3 was studied. The effects of solution flow rate, aqueous-to-resin flow ratio, column diameter, compartment height, initial resin concentration, and column length were examined. The experimental data indicate that for the eluant examined, a resin residence time of 240 minutes is necessary to attain 90-percent elution efficiency. Also provided is a technique for sizing an elution MCIX column form pilot plant experimental data.

Jan 1, 1979

To improve electrical safety and lengthen light bulb life on trolley haulageways. Approach A resistor inserted in series with each pair of light bulbs, decreases the voltage applied to the bulbs and eliminates heavy arcing when voltages rise. How It Works Under certain conditions, incandescent light bulbs connected directly to a 300-volt d-c trolley wire can be a hazard, particularly during weekends when electrical equipment is nut in use. When little electrical power is being used, the voltage (on the trolley lines and at the substation) can rise to a value which will destroy the bulb filament, cause arcing, and damage the bulb holder. In one coal mine where light bulbs in certain locations fre¬quently failed, the problem was overcome by inserting a 100-ohm, 50-watt resistor in series with each pair of light bulbs. The light bulbs are rated at 300-volts and 100-watts. Figure 1 shows the light bulbs and resistor circuit. This resistance was added in order to reduce the current through a short circuited bulb holder, from several hundred amperes to a much safer value of 3 amperes. However, the resistor in series with each pair of light bulbs, also reduces the voltage across the lighted bulbs to approximately 240 volts during periods when the trolley line voltage is up to 300 volts. With this arrangement, no light bulb failures occurred over a 6-month period. The resulting light reduction has not been objectionable.

Jan 1, 1976