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By ROBERT R. ROUGH, FRANK L. BACON, John Dasher

(being shipped as bailast in ocean freighters). Within the last 10 years it has become more economical to use local sands, and there has been a general shift from the Belgian sand. Deposits of purer sand were treated and used for 'some time: but the suprly became limited, and means were sought to beneficiate the more bountiful subpay-f impure beach sands. These sands are composed of, 50 percent feldspar and 50 percent quartz, with small amounts of iron- bearing minerals, The most objectionable impurities in these West coast sands are the oxides of iron and aluminum. The Del Monte (Calif.) beach sand contains about 0.13 percent FeqQg and about 11.0 percent Aig03 (the latter being furnished by the large amount of feldspar present.) For the manufacture of feldspar present.) For the manufacture of flint-glass containers the maximuni quantities of these two impurities permitted in the sand are 0.05 percent F20 and 6 to 8 percent A1203.. The Fe0g occurs in the sand as follows: Traces of iron-bearing minerais resistant to weathering, ferruginous clay stains on the sand grains, and iron minerais not visible and possibly in solid solution or as colloidal incisions in the grains of feidspar or quartz. A good part of the iron in the sand is present in the traces of iron-bearing minerals, biotite, ilmenite, garnet, monazite; and hornblende. Biotite is present in larger quantities than the others. Samples of quartz, were freed of iron-bearing minerais by the use of heavy liquid (sp.gr. 2.70), leached with boiling HCI and SnCl2. Under a microscope a few apparently clean quartz grains were selected, and Fe203 was determined spectrographically to be 0.03 percent. The technique is similar to that described by Gabriel and Slavin. 4/

Dec 1, 1943

By J. E. Spurr

"Zinc Industry in BelgiumBy March F. Chase, Consulting Metallurgist, Bureau of MinesBelgium for many years was the principal spelter producing country of the world. Gradually its production was surpassed by that of Germany, and Germany in turn lost first place by the production in the 77ti.tad States. For the ten years previous to 1914, 21.6 per cent of the world's spelter was produced in Belgium. Of this production approximately 40 per cent was exported. A large percentage of the balance was rolled and of the shoots thus produced a considerable quantity was also exported.From an economic standpoint even before the war, the Belgian industry was in a unique, if not praoarious, position. Dependent upon foreign countries for ore and foreign markets for sale of products, smeltor was at a distinct disadvantage when compared with some of those of other localities. These disadvantages were partly offset by cheap coal and labor and by whatever there is of value in experience and what we may term for want of a better expression smelting tradition. However intangible this latter may be, it did have and has today an influence on commercial operations.One must not overlook the effect it will have on the revival of the industry. It may not be the determining factor but the fact that for so many years this industry flourished in Belgium, and played such an important role in the industrial life of the country will decide many operators to attempt to re-establish their operations.In 1913 the Belgian spelter plants produced 204,220 long tons of spelter or approximately 20 per cent of the world's production. During this year 500,000 to of ore were treated. The actual value of all of the products derived from treating sine ore amounted to 225 million frames."

May 1, 1919

By Robert F. Chaiken

A novel approach to eliminating environmental and public safety hazards that are associated with fires in abandoned coal mines and waste banks involves the use of in situ combustion technology developed by the Federal Bureau of Mines to accelerate the burning of the wasted coals in place. This technology would be used under exhaust ventilation control conditions that would allow for total management of the hot gases produced. Combustion stoichiometries would be optimized to minimize unburnt combustibles and to maximize the heat content of the gas products, which will be exhausted at one or more fan locations. When necessary, scrubber systems would be employed to remove air pollutants, such as sulfur dioxide; heat utilization systems (process heat, steam, and electricity) would also be employed to offset operational costs. Ultimately, complete burnout would solve the fire and acid water formation problems of the abandoned coal mine or waste bank. Pertinent technical data for burnout control are derived and discussed in terms of the important material and operational parameters. In general, it is believed feasible to operate a burnout system in an existing abandoned mine or waste bank fire at thermal power levels in the range of 10 to 100 Mw, and at exhaust gas temperatures of 1,000° C (1,830° F).

Jan 1, 1980

By Spencer P. Howell, J. F. Xrawshaw

"A recent premature explosion in a quarry that resulted in the death of nine men and the injury of several others, was directly traceable to a spark from a steam-shovel working under the face directly in front of the hole being loaded. This accident and similar accidents on record in the Bureau of Mines indicates the necessity for pointing out the dangers in quarries of explosives being ignited by sparks emitted from steam shovels and locomotives, and making recommendations for greater safety.Many premature explosions of which the following are examples, have resulted from sparks, both from steam shovels and passing locomotives. (A) The premature explosion occurred during August, 1920 at a limestone quarry, in a 100-foot drill hole, loaded with 1000 pounds of high-grade nitroglycerin and gelatin dynamites. This hole had been loaded with 500 pounds of 75 per cent strength gelatin dynamite, 300 pounds of 60 per cent straight nitroglycerin dynamite, and 200 pounds of 50 per cent straight nitro¬glycerin dynamite; but no steaming had been placed in the hole. The powderman loading the hole saw the spark enter the hole and was able to run a short distance before the explosion took place, thus escaping serious injury. The explosion of this first hole was transmitted to nearby hole similarly charged. The fall of rocks from these two holes buried the steam shovel and some of the gang of men working around it.(B) In September, 1909, in the Canal Zone, a steam shovel uncovered a misfired charge of dynamite. While the dynamite was being picked up the steam shovel continued working nearby. A spark from the shovel set fire to some loose dynamite spilled on the ground from the troken cartridges. This fire was transmitted to a hole which was being loaded close by and caused a premature explosion. One man was injured."

Nov 1, 1920

By V. R. Spironello

One of the primary objectives of the Bureau of Mines solid waste utilization program is the recycling of the magnetic fraction of municipal solid waste called raw refuse scrap. In this investigation, several types of scrap of differing quality, including refuse and turnings, were melted in a 1-ton electric-arc furnace in various combinations to produce steel in noncritical (construction) grades. In-formation on furnace operation and on the behavior of tramp and alloying elements was obtained. The research showed that it is possible to produce acceptable steel from a variety of steel scrap. Although some scrap is routinely used in steelmaking, it was found that up to 50 to 55 pct of the scrap charge can be ref-use, provided it is combined with higher quality scrap. The chemistry of the steels was generally acceptable, and all of them were rolled without difficulty. The specification (ASTM 615) for the steels produced was grade 40 or grade 60, containing 0.30 or 0.40 pct C, with mini-mum yield strengths of 40,000 or 60,000-psi, respectively. Most of the steels met the specification requirements. In-formation on typical microstructures of some of the steels is included. The composition of some furnace dusts showed high levels of Sn, Pb, and Zn.

Jan 1, 1981

The question of earth models has repeatedly arisen in our work. An accurate representation of the seismic properties is required for three reasons: 1.To be able to determine from a set of received arrival times, the location of a seismic source in the earth, and secondly the degree of accuracy required in the model used for calculating source location from the set of arrival time differences. 2. To be able to determine the expected arrival times at an array of geophones produced in response to a hypothetical source in the earth. 3. To be able to estimate received signal strengths more accurately. The work reported here on earth models is based on information from sever- al consultants and from others who expressed an interest in the problem and supplied information to us. II. COAL MINE GEOLOGY On one of our earlier assignments for the Bureau of Mines, Earth Science Research Inc. of Cambridge, Massachusetts prepared for us a short description of the lithology to be expected at coal mine sites. This description follows, together with the ranges of compressional seismic velocities (Figure I*) associated with typical materials comprising the layered structure of a coal mine area. Coal is primarily associated with fresh water sediments including sandstones, shales, and clays, and occasionally may be metamorphased to varying degrees. In the Appalachian Basin the coal beds occur within cyclical sequences of non-marine shales, sands tones, conglomerates, limes tones, and clays. The beds range in thickness from a few inches to 60 feet, averaging between 2 feet and 10 feet. They have generally broad areal extent, occasionally up to 5,000 square miles, and have an overall tabular or lens-like shape. Within a particular lens, local changes in thickness are normal.

Jan 1, 1974

By James Paone

The Bureau of Mines conducted laboratory drillability studies on nine rock types using two mining-type percussive drills. Percussive-bit action was simulated by dropping a known weight on a rock sample to obtain a coefficient of rock strength for each rock drilled. While no single physical property of a rock is completely satisfactory as a predictor of penetration rate, coefficient of rock strength showed a better correlation with penetration rate than did other physical properties. Results also indicate that over the range of energies investigated, energy per unit volume in a given rock is independent of blow energy. A drillability index for the percussive system is proposed that utilizes the coefficient of rock strength test to determine energy per unit volume for a given rock which, along with the work rate of a given drill and the bit diameter, is used to predict the penetration rate as shown in the following equation: [R = 4P pD2 E, where R = penetration rate, in/min, P = work rate, in lb/min, D = bit diameter, in, and Ev = energy required to produce a given volume of rock, in lb/in3.] Laboratory tests indicate this method's potential as a simple and reasonably accurate method of predicting penetration rates with any percussive drill and bit combination.

Jan 1, 1969

The twelve latexes listed in Table XI penetrated A horizon soil as shown by elution through a laboratory soil column and gave good sealing efficiency. See details in Table XII. High elution through laboratory soil columns of 4 to 6 inches depth is desirable because it predicts penetration of latex to a greater depth in the field. No definite correlation was evident between penetrating ability and particle size, surface tension, or pH. Most of the materials, however, were characterized by low surface tensions in the 36 to 53 dynes/cm range while particle sizes were usually in the intermediate range of about 1500 to 2500 Å. Naugatex J-3471 (a highly crosslinked styrene-butadiene copolymer) was the most promising of this group for stability, penetrating ability; and sealant efficiency. It also showed utility with [B] profile soil. Many of the other latexes tested in this investigation showed good sealing efficiency but were judged unsatisfactory because they gave low penetration or formed surface films with & horizon top soil. In general, latexes containing cationic surfactants were not satisfactory because they formed a heavy surface film. This is due to neutralization of the positive latex charge by the negatively charged soil particles.

Jan 1, 1972

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

A. 4 Illustrative Simulations The capabilities of the program are demonstrated by simulating various evacuation cases in different situations for a particular mine. The mine selected for the illustrative simulations is the mine I C' , as described in Section 2, chosen particularly because of availability of mine characteristic data and mine evacuation results for test drills. These evacuation results can be used to verify validity of the predictions made by the program A.4 1 Mine Characteristics A schematic diagram of the mine is shown in Figure 19. The figure shows all the major shafts, drifts, raises and stopes of the mine in the form of a network. There are four hoists, Hoist No. 1 and Hoist No. 2 are assumed to be single drum hoists and Hoists Nos. 3 and 4 form part of a double drum hoist, with Hoist No. 4 being the main hoist (master hoist) The positions of the 133 miners, typically working in a day shift of the mine, are also shown in the figure. The miners are identified by a miner number, and their total number on each level is chosen from the data on the fire drill simulated as Case No. 1 in the illustrative simulations.

Jan 1, 1976

By A. F. Colombo

In an effort to maintain an adequate supply of iron to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, is conducting research on methods for beneficiating the oxidized taconite resources located on the western Mesabi range in Minnesota, thus expanding domestic iron ore reserves. The selective flocculation and cationic flotation process was investigated in a pilot plant using an ore feed rate of 410 kg/hr (900 1b/hr) and 88 percent recycled water. Lime and a cationic flocculant were used to clarify the waste slurries treated in the water reclamation circuit. An oxidized taconite assaying approximately 36 percent Fe yielded concentrates averaging 63.5 percent Fe and 4.3 percent SiO2 and having an average iron recovery of 84.4 percent. The estimated reagent cost per tonne of concentrate was approximately $1.10. In an attempt to recover more of the iron lost in the flotation tailing, wet high-intensity magnetic (WHIM) separation was incorporated in the pilot plant circuit. The flotation concentrate grades obtained from beneficiation circuits with and without WHIM scavenging were similar, but when WHIM separation was used the overall iron recovery was increased by 2 to 9.5 percent, depending on the iron assay of the flotation tailing.

Jan 1, 1978

By Paul W. Jeran, Michael A. Trevits, William P. Diamond

In this U.S. Bureau of Mines study, production trends have been analyzed for 82 gob gas ventholes on 7 longwall panels in the Lower Kittanning Coalbed, Pennsylvania. Cumulative production from individual holes was found to vary considerably, ranging from 0.03 x 106 to 10.1 x 106 m3. Peak production rates were generally about 0.03 x 106 to 0.06 x 106 m3/d, but rates over 0.10 x 1@ m3/d were observed. The variability of gas production from individual holes can be attributed to several factors, including completion practices and problems, the extent of fracture development in the strata above the extracted panel, water production, and location on the panel. Of particular significance is hole location. Holes on the ends of the panels, where overburden strata are in tension because of the support of the surrounding pillars, were generally the highest and longest producers. This observation led to the experimental placement of gob gas ventholes in the zone of tension along the margin of a panel, instead of in the traditional centerline location, which is in compression. Analysis of 7 months of gas production data indicates that the experimental near-margin holes produced 77 pct more gas than did centerline holes on the same panel.

Jan 1, 1994

By David W. Houseknecht

Probabilities of encountering coalbed discontinuities during vertical or horizontal drilling in a specific coalbed can be estimated based on analysis of mined-out areas of the coalbed where the size, shape, orientation, and distribution of discontinuities are known. The result-ant probability estimates can be applied to cost-risk evaluations of drilling programs proposed for exploratory, developmental, or methane drainage purposes in undeveloped areas of that coalbed. Data compiled from mine maps of the Beckley Coalbed in southern West Virginia were used to estimate the probabilities that discontinuities would be encountered in two illustrative hypothetical drilling programs--one for drilling vertical boreholes and the other for drilling horizontal boreholes. Analysis based on a mined-out area of the Beckley Coal bed indicated that vertical methane drainage boreholes spaced 1,000 feet apart in a square grid pattern would each have a 29 percent probability of encountering a discontinuity in a geologically unexplored area of the coalbed. It was also determined that exploratory vertical drilling could locate most of the discontinuities if a borehole spacing of 2,500 feet were used. For horizontal drainage boreholes in the Beckley Coalbed, the analysis indicated a linear relationship between hole length and the probability of encountering a discontinuity.

Jan 1, 1982

By J. Douglas Causey

In 1987, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied 11,069-acres of the 12,290-acre Eldorado Wilderness Study Area (NV-050-423) in order to evaluate its identified mineral resources. The study area is located in Clark County, NV, adjacent to and northeast of the town of Nelson. There are inferred subeconomic resources on the Paul (gold, silver), Bel (gold, silver), Big Horn-Inez (silver, copper, lead, zinc) claims, and Montezuma (gold, silver, copper, lead, zinc) patented claim group in the Eldorado study area. Because of lack of exposures, tonnage and grade on these properties could not be determined. No resources were identified for the other five properties examined in the area. The southern two-thirds of the area is in the Eldorado mining district, a base- and precious-metal district which has been intensely explored for over 100 years. Nine claim groups were examined in the study area. Eight claim groups are within the Eldorado district and include the Montezuma (patented -M.S. 3966), Bel, Eldorado, VAR, SINJUN, Paul, Rusty Bit, and Big Horn-Inez. One property, the Flintstone claim group, is north of the Eldorado mining district at the north end of the study area.

Jan 1, 1988

By Walter O. Snelling, C. G. Storm

Although descriptions of the methods of analysis of explosives are to be found in many books on explosives, and in works on engineer- ing chemistry or chemical analysis, most of these descriptions are incomplete and lacking in details. The methods of analysis employed in the laboratories of most explosives factories are frequently treated as trade secrets, and very little information is published from such laboratories. This bulletin outlines the methods of analysis that are used by the Bureau of Mines in the examination of certain classes of explo- sives. The present form of most of these methods has been worked out in the bureau's explosives laboratory. The methods employed by Prof. C. E. Munroe were taken as a basis, and were elaborated to meet the demands incident to the treatment of complicated mix- tures and to the development of the explosives art. A subsequent bulletin will discuss the methods of analysis of "permissible" explosives, many of the latter being of decidedly complicated char- acter and requiring special treatment. This bulletin presents the methods of analysis of "ordinary" dynamite, and the ammonia, gelatin, low-freezing, and granular dynamites, and the common grades of black gunpowder and black blasting powder. The bulletin is published by the bureau for the information of all persons inter- ested in explosives and their safe and efficient use in mining work. As the term "ordinary" dynamite, though much used, has no conventional meaning, and may be used to cover a wide variety of compositions of matter, it may be noted that the standard dynamite used at the Pittsburgh testing station is a good example of the "ordinary" dynamite known in this country. This testing station dynamite has the following composition:

Jan 1, 1913

By H. H. Storch

Methane is the chief constituent of natural gas, and large quantities of it are also obtained in coke-oven gas and in the off-gases from cracking higher hydrocarbons. Perhaps the most important potential chemical use of methane is in the production of higher hydro- carbons, both aliphatic and aromatic. The results of a relatively large number of researches have been published in the technical and patent literature on the thermal decomposition of methane, the objective being an industrial process for the production of "antiknock" motor fuel. No industrially feasible process has, however, been developed. An inspection of the literature on this subject indicates that the chief difficulty in the way of accomplishing this object lies in controlling the decomposition so that undesirable products are eliminated. A considerable number of quantitative experiments have been reported, the results of which provide only a vague and confusing picture of the various steps in the thermal decomposition of methane. The reaction mechanism has not been subjected to rigorous fundamental study, and the necessity for such a study is obvious if further progress is to be made. The thermal decomposition is only one of the reactions of methane which are of potential industrial importance and which require further fundamental investigation. The oxidation, hydrolysis, and halogenation of methane are other reactions which must be studied further. In view of the importance of methane as a raw material for various industrially desirable products, it is appropriate that a survey be made of the important facts concerning the physical and chemical properties of methane which will serve as an aid in subsequent experi- mental work. No attempt will be made to present a complete chronological review, but rather a condensed critical description of the important literature will be presented.

Jan 1, 1932

By J. W. Paul, A. C. Fieldner

"In cooperation with the New York and New Jersey State Bridge and Tunnel Commissions, the Bureau of Mines has just completed the construction of an experimental tunnel in the Bureau's experimental mine at Bruceton, Pa., near Pittsburgh, Pa. The purpose of this tunnel is to make a final study of the ventilation problems arising in the adequate ventilation of vehicular tunnels for automobiles and trucks, especially the 9000-foot tubes that are being designed. to handle the traffic between New York City and New Jersey under the Hudson River.Chief engineer, Clifford M. Holland, of the Tunnel Commissions has shown that there are three principal problems involved in planning the ventilation of this tunnel, namely - (1) The amount and composition of exhaust gases from motor vehicles; (2) The dilution necessary to render these exhaust gases harmless; (3) Determination of coefficients of airflow and horse-power required in ducts, bends and openings.Composition of automobile exhaust gases.The answer to the first problem was obtained by making road tests on 101 automobiles and trucks at the Pittsburgh experiment station. These machines were taken from service without any previous adjustment so that the composition and amount of the exhaust gas may be taken as representative of actual operating conditions prevailing in the tunnel. A report covering the results of these tests was submitted to the chief engineer of the Tunnel Commissions, on November 1, 1920, and 411 be published in the report of the commissions. Several papers a have also been published in the technical journals summarizing the important results as regards tunnel ventilation and also with reference to gasoline losses in present-day motor car operation due to the general use of unnecessarily rich mixtures"

Oct 1, 1921

Objective The Roof Monitoring Safety System (RMSS) introduced in late 1997 has been modified to improve durability and simplify the measurement of roof or rib movement. Greater knowledge about the stability of roof and rib rock is expected to result in safer conditions for the mine worker. Developing safety tools and methods is part of NIOSH’s mission to prevent work-related injuries and deaths. A mining operation with a proactive approach to control ground conditions is in a better position to make essential decisions related to mine development and take remedial actions in the event of roof or rib falls. Background Falls of roof and rib rock are responsible for a high number of mining injuries and fatalities. Visual inspections and the sound of breaking or cracking rock are often relied upon to indicate unstable roof conditions. In some mines, roof bolt holes are checked for separations or gaps with a scratch tool; this provides further information about the stability of the roof. Monitors such as the RMSS can confirm roof movement that was surmised only by eye or ear, or potentially detect movement that was missed by these means. An added safety feature of the RMSS is the capability of locating the measurement station at a distance from where the monitor is placed in the roof. Stone and other industrial minerals are the basic raw materials used in construction. Continuing economic growth and highway building in particular have resulted in record demand for stone. This high demand, coupled with increasing constraints on surface mining, have caused many new .stone mines to be developed underground. These new mines in many cases will be employing new and inexperienced miners who may not have the ability to recognize unstable ground conditions using just sight and sound. From the initial introduction of the RMSS, it was anticipated that improvements and modifications would occur. We correctly assumed that, once miners and operators were exposed to the monitor. suggestions would evolve. In one case, the RMSS was used to determine if an impact hammer used on a mechanical scaler was causing or increasing instability of roof rock. The test showed little or no movement resulted from this method of scaling under the particular conditions at this mine. In another instance, an operator needed to monitor the stability of a haulageway in a benched area that had very high ceilings. The RMSS requires a 2-in-diam hole for installation; however, only roof bolt holes of a smaller diameter were available, and it was impossible to drill new holes at that height. The operator attached a 2-in collar at the roof line and was able to install the RMSS. These examples illustrate the potential for further enhancements of this tool. NIOSH continues to seek additional candidate sites for use of the RMSS. As usage increases, we anticipate further refinements and additional applications. How It Works The new RMSS, cable, and read-out box are shown in figure l. The read-out box has a green light that stays lit until battery replacement is needed. The red light is set to conic on to indicate movement. The red light can he adjusted for increments of movement as low as .010 inches. The RMSS red light should not be considered as a primary or only means of determining the stability of roof or rib. It is intended to serve as a supplement to existing methods or procedures for determining stability. An overview of the RMSS components is shown in figure 2. Movement of rock layers within the mine roof is measured relative to a fixed-point calibration at the monitor housing. The housing contains a potentiometer, roller switch, plastic rack, and spur gear. Movements are detected by the transfer of electromotive forces

Jun 1, 2000

By Raja V. Rarnani, Robert L. Frantz

"The Generic Mineral Technology Center for Respirable Dust (GTCRD) was created at The Pennsylvania State University and West Virginia University by a congressional initiative in 1983 responding to recommendations in the 1980 National Academy of Sciences study on the Measurement and Control of Dust in Mines. Many of these recommendations dealt with the need to initiate focused fundamental research for further professional progress in dust control. Long-term, sustained support was emphasized to develop expertise in respirable dust research. In creating this Center, Penn State and West Virginia University were specifically recognized for their expertise in and facilities for research on coal mining and medicine. Today, the Center includes the Massachusetts Institute of Technology, the University of Minnesota, and the Michigan Technology University. The Respirable Dust Center is the only organization that coordinates and integrates the medical, scientific, and engineering aspects of respirable dust disease. The Center works with the U.S. Bureau of Mines (USBM), Mine Safety and Health Administration (MSHA), the National Institute for Occupational Safety and Health (NIOSH), the United Mine Workers of America (UMWA), and the U.S. coal industry in defining the research priorities for the programs of the Center to enhance research synergism.The Center's mission is to enhance the health, safety and productivity of miners by advancing the fundamental understanding of all aspects of respirable dust associated with mining and milling and the interaction of dust and lungs to reduce the incidence and severity of respirable dust disease.All Dust Center activities are focused to be responsive to this mission, which is shared by the several federal agencies closely associated with the GTCRD. While significant progress has made mine atmospheres cleaner and healthier, respirable dust-related disease remains the nation's most pernicious industrial hazard.The goals of the GTCRD were formulated with recognition of the diverse scientific, engineering, and medical aspects of respirable dust, in addition to a need to enhance researcher interaction, as well as education and technology transfer efforts, in the respirable dust area. These goals reflect the needs of the mining industry as determined by the National Academy of Sciences Committee on Measurement and Control of Respirable Dust study done in 1980. The report of this committee encouraged the Bureau of Mines to redirect its research efforts ""...toward obtaining fundamental understanding of the origin, transport and characteristics of respirable coal mine dust."" The GTCRD's goals, detailed in chapter three of this document, were formulated to mesh with NAS recommendations."

Jan 1, 1995

By Scott Turner

The settlers of a new country necessarily suffer at first from the lack of accumulated stocks of metals - in-use that are possessed in older countries . Our American colonists were at first compelled to import their metals in manufactured forms , and it must have proved difficult to produce an exportable surplus of commodities with which to pay for them . These circumstances stimulated a search for domestic ore deposits . Various discoveries resulted , so that as early as 1628 , we find the colonists importing two craftsmen from England to establish iron -works in Massachusetts to beneficiate local ores . In 1648 , an iron -works at Lynn was producing metal at an annual rate of 400 tons . Later on , the colonial iron industries became of importance , some metal being actually exported to England . The people of this country thus early became convinced of the necessity for domestic mineral production . It is now little realized how persistent were their efforts to - make mineral discoveries , before the gold- rush to California ; the extraordinary success of our subsequent mineral explorations has overshadowed the earlier record . Precise and complete accounting of our mineral production , having the character of national bookkeeping , is available only for the series of years beginning with 1880 , when commences the official record that is provided by the Government publication called Mineral Resources of the United States . In the period of 52 years , from 1880 through 1932 , the value of mineral production of the United States amounted to more than 122 billion dollars . Only 12 billions of this total were produced in the 21 years , 1880-1900 , while nearly 110 billions were produced in the first 31 years of the present century . Of this 110 billions , over 53 billions were produced in the most recent decade , 1921- 1930 , the production of the previous decade , 1911-1920 , having been only 37 billions , though it included the war period ; that of the decade 1901-1910 was 16 billions . In 1931 , the total value of mineral products of the United States was $ 3,180,000,000 , compared with an average annual value of $ 5,556,000,000 during the previous five - year period , 1926-1930 . The decline in 1931 from that average was therefore 43 per cent . As to the three great groups of mineral commodities , metals fared worst , with a decline of 55 per cent in the value of their production , while the value of fuels declined 39 per cent , as did that of the nonmetals group .

Jan 1, 1933

By Thomas P. Meloy

"The presence of respirable quartz-bearing mineral par-ticles has been well documented in many coal mines, and the Mine Safety and Health Administration regulations address the quartz content of mine dusts. Unfortunately, the correlation between the quantity of respirable quartz-bearing mineral particles and the pathogenicity of the dust is not strong. Work is currently underway by the National Institute for Occupational Safety and Health/U.S. Bureau of Mines and work is being included in the Respirable Dust Center Program by Dr. Seehra to determine the surface availability of quartz in mixed composition mine dusts. However, this paper propose a possible source of surface quartz or a spe¬cial region in the coal that may contribute to the pathogenicity of selected particles in the respirable dust.Assumed in this model is the hypothesis that either the cleat surface is coated with quartz or some cytotoxic sub-stance that in the body is capable of destroying macrophage and thus inducing a fibrotic response (1) that during the frag¬mentation a reasonable proportion of the respirable size coal particles contain some of the original cleat surface and that these particles have the same order of in vivo cytotoxicity as do the quartz particles. It may be that these cleat surfaced respirable size particles are only contributory to the overall pathogenicity of the coal dust, nevertheless, there are enough of these particles to to considered as a potential source of the cytotoxic dust particles.This paper demonstrates that if the cleat surfaces are mineralized with quartz or have a pathogenic coating, then in many mines there will be enough respirable coal dust particles containing some cleat surface to cause a fibrotic reaction. To understand why some of the dust particles contain as part of their surface some of the cleat surface, consider what happens when a beer bottle is broken. While there are a large number of beer bottle fragments, many of the fragments, particularly the larger fragment sizes, will have as a fraction of their surface part of the original beer bottle surface. The model and mathematics of this problem have been worked out by Meloy.(2-4)In the homogeneous IAC model, (2-5) a fragment or par-ticle resulting from comminution is equally likely to occur anywhere in the material being broken. Therefore the probability of a particle of size x having part of the cleat surface in it, p(x), is proportional to x. Thus:"

Mar 1, 1989