Search Documents

By H. Copur

Experimental studies for quantification of force and brittleness indices relevant to rock cutting performance are presented. A simple interpretation method is developed, which quantifies the force-penetration response obtained from indentation tests. Basic parameters of the quantification are force increment and decrementrates, force increment and decrement periods, and number of increment and decrement data points. Blocks of eleven different rock samples were collected from different operating mines in Turkey and subjected to indentation tests to calculate the indices. The samples included harzburgite, serpentinite, trona, limestone, claystone, two different sandstone samples, siltstone and three different chromite ore samples. The concept was validated by a set of full-scale linear cutting tests using a conical cutter for measuring the cutting performance in relieved and unrelieved conditions, i.e. cutter forces, specific energy, size distribution of rock cuttings. The rock cuttings were sieved to determine coarseness index, indicates coarse chip generation characteristics, and size distribution. The force index is moderately correlated with the cutting performance and mechanical properties of the rocks, and poorly correlated with the coarseness index and size distribution of cuttings. A general and moderate trend is observed between the brittleness index and the coarseness index, cutting performance for unrelieved cutting conditions and mechanical properties of the rocks. However, additional data is required to fill the data gaps and to potentially establish relationship between the brittleness index and all other parameters.

Jan 1, 2003

By Greaves M. C, Amos M. D

A study was made of the instrumentation and technique of atomic absorption spectroscopy developed by Walsh of the Commonwealth Scientific and Industrial Research Organisation (C.S.I.R.O.), Australia.The method was evaluated for the determination of silver in lead sulphide concentrate. The precision of the procedure developed is equal to that of the uncorrected fire assay method and the accuracy is greater.Brief mention is made of the use of this technique for the determination of silver and other elements in ores and concentrator products.INTRODUCTIONThe fire assay method, although accepted on a world-wide basis as the umpire method for the determination of silver in ores and concentrates, is freely recognized as yielding results which are lower than actual due to unavoidable losses.King (1934) investigated the influence of the cupelshape, size and material on silver losses during cupellation. Using 100 mg silver prills he recorded silver losses ranging between l. and 10 per cent under extreme conditions and averaging approximately 2 percent under conditions which might be considered normal. Guerin (1957) made a detailed study, under carefully controlled conditions in a furnace similar to that described by Esdaile (1952), of the effect of temperature on silver losses during cupellation. He concluded that if cupellation were carried out at 840°C., then the amount of lead retained by the silver prill was insignificant and that the silver losses were governed by the equation: Y = 0·055 XO.74where X = the final weight of the silver priIl (mg)and Y = the silver lost (mg)

Jan 1, 1961

By Jochen Petersen, Diane Taggart

"At an average of 90.3% (for the period of 1 January 2009 to 30 September 2011), Zincor’s zinc recovery was well below the industry standard of 96%. The losses through the residues, in particular the iron residue, were the biggest contributors to the overall zinc loss. It was believed that this loss could be decreased with the implementation of seed recycling. A plant trial was run to test the implementation of a seed recycle. The rate of seed addition through recycle was increased over a 4-week period. The presence of seed decreased the insoluble zinc loss by providing additional surface area for iron to precipitate onto, and reducing coating of unleached neutralising agent. The soluble zinc loss was also decreased at low and moderate seed recycle volumes. The improvement was attributed to agglomeration growth of the recycled particles, which improves the dewatering characteristics of the precipitate. In contrast, the soluble zinc loss increased at high seed recycle rates. This result was attributed to particle crowding and a low wash ratio.INTRODUCTION The Zincor refinery, which closed in December 2011, was situated just outside of Springs in the Gauteng Province of South Africa and employed the conventional Roast-Leach-Electrowin process, which accounts for 75 to 80% of the annual primary zinc production in the world. The refinery fed up to 220 000 t/a of zinc sulphide concentrate. The major portion of the raw material was sourced in Southern Africa from the Rosh Pinah and Black Mountain mines. Between 20 000 and 40 000 t/a of material was imported to make up the deficit and to improve the grade of the feed material. The iron contained in the zinc concentrates, at an average of 6.03% (for the period of 1 January 2009 to 30 September 2011), resulted in the formation of zinc ferrite during roasting, which is insoluble under atmospheric leach conditions. At Zincor, most of the zinc ferrite was dissolved in the residue treatment plant at elevated temperature and high acid strength. The leach liquor from this aggressive leach contained between 15 to 30 g/L of iron, mostly in the ferric form, and was known as the hot iron solution (HIS). The presence of iron in the liquor had an adverse effect on the zinc operation, particularly on the current efficiency in the electrowinning circuit. Therefore the iron needed complete removal."

Jan 1, 2016

By J. Durkin

The Bureau of Mines has conducted field studies in coal mines throughout the United States to determine the effectiveness of electromagnetic techniques in locating miners trapped underground following a mine accident. Data from these tests have been used to generate models of expected signal and noise distributions as found above these mines. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results show that at a 10% false-alarm rate, the expected probability o detecting a miner's signal" from a depth of 1000 ft is 54% at 500 ft it is 95%. These depths exceed the actual depths of 90 and 50%, respectively, of United States coal mines. Sensitivity studies have shown that at depth of 1000 ft, the probability of detection will improve approximately 2% for each dB of increase in signal-to-noise (SNR) ratio.

By Donald H. McLaughlin

PRICES paid for goods and services in paper currencies are undoubtedly determined by many interrelated factors, but among them none is more specific in pushing prices toward higher and higher levels than the vast increase in debts and monetary obligations of our own and practically all major governments. There is nothing unorthodox in the situation in which the gold miners find themselves today. With wages and the prices of all materials required in the production of gold at the high levels characteristic of a period of prosperity, phony or otherwise, and with shortages of both men and machinery to contend with as well, the spread between the returns in paper dollars that must be accepted for gold in the United States and the cost of producing it is rather painfully small for most producers. Technical

Jan 1, 1948

By E. A. Swedenborg

The unit agreement for the Wertz Dome field, Wyoming, was approved by the Acting Secretary of the United States Department of the Interior on November 4, 1937, effective on December 1, 1937. The stated objectives of the agreement are to conserve and put to beneficial use all oil and gas produced; to make possible a uniform withdrawal of oil and gas in order to maintain equalized reservoir pressures; to provide for an orderly determination of the structural features of the productive horizons; and to permit the injection of gas for pressure maintenance. The purpose of this paper is to show by a discussion of the problems involved and the engineering practices employed by the unit operator, how well the objectives of the unit agreement have been accomplished in the development and production of oil and gas from the field. HISTORY AND DEVELOPMENT The Wertz Dome oil and gas field is located 88 miles southwest of Casper and 38 miles north and westerly from Rawlins, Wyoming. It is served by a state secondary oiled road connecting with U. S. Highway No. 220 at Lamont, a distance of 3 miles from the field. It has been a producing field for 27 years, first as an important producer of gas and more recently of oil. The Producers and Refiners Corp. completed Well No. 1, NE1/4SW1/4 sec. 7, T. 26 N., R. 89 W., the first productive well in the field, in September. 1921, in the Muddy sandstone of Upper Cretaceous age, at a depth of 3435 feet for an initial production of 42,000,000 cu. ft. of gas per day. In 1922 pipe lines were laid to Casper, Wyoming, for supplying fuel to the Standard of Indiana refinery, 'the adjoining town of Mills. and the Producers and Refiners Corp. pump station No. 6 in Mills; and to Parco (now Sinclair), Wyoming, for supplying that refinery with fuel. The gasoline content of the gas was extracted in an absorption plant located near the town of Mills. No compressors were used as the line pressure was sufficiently high to flow the gas through the absorbers. As high as 30,000,000 cu. ft. of gas per day were treated in the plant extracting 6000 gallons of gasoline. In September 1937, the pipe line was discontinued and the plant was dismantled at which time 61,000,000,000 cu. ft. of gas had been produced from the seven Muddy, Cloverly, and Sundance gas wells drilled in the field. Of this volume of gas 800,000,000 cu. ft. were produced from the Frontier formation, 34,200,000,000 cu. ft. from the Muddy sandstone, 24,000,000,000 cu. ft. from the Cloverly, locally called Dakota, and 2,000,000,000 cu. ft. from the Sundance formation. The pipe line was discontinued because of the near depletion of the gas reserves in Wertz and nearby fields, and hecause of the local field requirements demanding the retention of the remaining gas reserves. In December 1936, the Sinclair Wyoming Oil Co. completed Well No. 10, SE1/4NW1/4 sec. 7. T. 26 N., R. 89 W., at a depth of 5886 feet. as the first Tensleep sand producer with an intial of 1700 barrels of oil per day. The well was originally drilled only 14 feet into the sand and in August 1939 was deepened to a depth of 6161 feet, 289 feet in the sand, and the daily produe tion increased to 8350 barrels of oil. In February 1948 Well No. 22, SE1/4 SE1/4 sec. 1. T. 26 N., R. 90 W., was deepened from the Tensleep to the Basal Amsden sand and completed at a depth of 6635 feet for an intial of 600 barrels of oil per day in the Basal Amsden. In April 1948, Well No. 2. SW1/4 NE1/4 sec. 1, T. 26 N., R. 90 W.. was deepened from the Tensleep to the Madison limestone and was completed at a depth of 7193 feet for an intial of 1145 barrels of oil per day in the Madison. Well No. 26, SE1/4SE1/4 sec. 1, T. 26 N.. R. 90 W., was deepened from the Ten-sleep to the Cambrian and in October 1948 it was completed in the Cambrian for an intial of 277 barrels of oil per day. GEOLOGY AND PRODUCTIVE ACREAGE The surface is Steele shale of Upper Cretaceous age, covered in part by gravel beds. The topography of the field is that of a rolling hill with a steep draw or gulch along the northern edge of the field. The Steele shale lies conformably on the lower formations as

Jan 1, 1949

By E. A. Swedenborg

The unit agreement for the Wertz Dome field, Wyoming, was approved by the Acting Secretary of the United States Department of the Interior on November 4, 1937, effective on December 1, 1937. The stated objectives of the agreement are to conserve and put to beneficial use all oil and gas produced; to make possible a uniform withdrawal of oil and gas in order to maintain equalized reservoir pressures; to provide for an orderly determination of the structural features of the productive horizons; and to permit the injection of gas for pressure maintenance. The purpose of this paper is to show by a discussion of the problems involved and the engineering practices employed by the unit operator, how well the objectives of the unit agreement have been accomplished in the development and production of oil and gas from the field. HISTORY AND DEVELOPMENT The Wertz Dome oil and gas field is located 88 miles southwest of Casper and 38 miles north and westerly from Rawlins, Wyoming. It is served by a state secondary oiled road connecting with U. S. Highway No. 220 at Lamont, a distance of 3 miles from the field. It has been a producing field for 27 years, first as an important producer of gas and more recently of oil. The Producers and Refiners Corp. completed Well No. 1, NE1/4SW1/4 sec. 7, T. 26 N., R. 89 W., the first productive well in the field, in September. 1921, in the Muddy sandstone of Upper Cretaceous age, at a depth of 3435 feet for an initial production of 42,000,000 cu. ft. of gas per day. In 1922 pipe lines were laid to Casper, Wyoming, for supplying fuel to the Standard of Indiana refinery, 'the adjoining town of Mills. and the Producers and Refiners Corp. pump station No. 6 in Mills; and to Parco (now Sinclair), Wyoming, for supplying that refinery with fuel. The gasoline content of the gas was extracted in an absorption plant located near the town of Mills. No compressors were used as the line pressure was sufficiently high to flow the gas through the absorbers. As high as 30,000,000 cu. ft. of gas per day were treated in the plant extracting 6000 gallons of gasoline. In September 1937, the pipe line was discontinued and the plant was dismantled at which time 61,000,000,000 cu. ft. of gas had been produced from the seven Muddy, Cloverly, and Sundance gas wells drilled in the field. Of this volume of gas 800,000,000 cu. ft. were produced from the Frontier formation, 34,200,000,000 cu. ft. from the Muddy sandstone, 24,000,000,000 cu. ft. from the Cloverly, locally called Dakota, and 2,000,000,000 cu. ft. from the Sundance formation. The pipe line was discontinued because of the near depletion of the gas reserves in Wertz and nearby fields, and hecause of the local field requirements demanding the retention of the remaining gas reserves. In December 1936, the Sinclair Wyoming Oil Co. completed Well No. 10, SE1/4NW1/4 sec. 7. T. 26 N., R. 89 W., at a depth of 5886 feet. as the first Tensleep sand producer with an intial of 1700 barrels of oil per day. The well was originally drilled only 14 feet into the sand and in August 1939 was deepened to a depth of 6161 feet, 289 feet in the sand, and the daily produe tion increased to 8350 barrels of oil. In February 1948 Well No. 22, SE1/4 SE1/4 sec. 1. T. 26 N., R. 90 W., was deepened from the Tensleep to the Basal Amsden sand and completed at a depth of 6635 feet for an intial of 600 barrels of oil per day in the Basal Amsden. In April 1948, Well No. 2. SW1/4 NE1/4 sec. 1, T. 26 N., R. 90 W.. was deepened from the Tensleep to the Madison limestone and was completed at a depth of 7193 feet for an intial of 1145 barrels of oil per day in the Madison. Well No. 26, SE1/4SE1/4 sec. 1, T. 26 N.. R. 90 W., was deepened from the Ten-sleep to the Cambrian and in October 1948 it was completed in the Cambrian for an intial of 277 barrels of oil per day. GEOLOGY AND PRODUCTIVE ACREAGE The surface is Steele shale of Upper Cretaceous age, covered in part by gravel beds. The topography of the field is that of a rolling hill with a steep draw or gulch along the northern edge of the field. The Steele shale lies conformably on the lower formations as

Jan 1, 1949

By Braden T. Lusk, Shannon P. Lusk, Kyle A. Perry

A high explosives shock tube has been constructed and developed to test blast resistant windows with pressure versus time waveforms similar to waveforms generated by arena testing. Calibration of the high explosives shock tube, or Large Arena Test Simulator (LATS), included numerous tests performed by detonating varying charge weights at different distances from three piezoelectric pressure sensors located at one end of the shock tube (where the test subject would be installed). The maximum reflected pressure and positive phase impulse were calculated for each waveform generated in the tests. Pressure versus distance and impulse versus distance graphs were generated. Results have been graphed in order to predict charge weights and distances that correlate to the desired pressure and impulse at the end of the tube for future tests. This is a valuable tool when testing expensive, job specific components so the loading requirements are met on the first attempt.

Jan 1, 2010

By Stephen A. Orr

Underground mining is a dynamic art and science with a diverse set of design, production, and economic criteria that must be considered before selecting an optimal method to extract the ore. While all methods can be technically classified as either self-supported, supported, or caving, the multitude of subsystems and existing variations bear witness to the fact that each orebody is unique and, as such, justifies an individual approach to optimize mineral extraction. In this sense, underground mining is an art. The ability to evaluate the unique characteristics of each ore body and utilize sound engineering principles to design the optimal system constitutes effective method selection. The task by no means ends at this juncture, however. Subsequent implementation requires an ability for modification. Very rarely are all the facts available to make a concrete decision prior to development of the resource. As a result, the risk of a wrong decision can never be eliminated. This requires a significant degree of flexibility with each method. Each unit of exploration, development, or exploitation work contributed to a deposit enhances knowledge of the ore body. The best mining methods are those that correctly account for the known parameters but provide an allowance for change at minimal cost and adapt to unanticipated conditions.

Jan 1, 2008

By Louis J. Sousa

In November 1989, the U.S. Bureau of Mines sponsored a 2-day conference to stimulate thinking and discussion about changing materials technologies and implications for the Government's materials information programs. On the first day of the conference, speakers provided overviews of developments occurring in each of the major materials groups. Emerging technological developments, applications, economic and national defense significance, intermaterial competition, and potential market growth in advanced plastics, polymer composites, ceramics, metals, and electronic materials were described. In general, the speakers forecast advanced materials market growth rates in excess of overall gross national product (GNP) though high costs will tend to limit growth outside of aerospace, defense, electronics, medical equipment, and other typically high value-added businesses. On the second day, a wide range of speakers representing several facets of the materials community described how advances in materials technology are creating a need for new types of data, statistics, information, and analysis. Reflecting the speakers' broad range of organizational, professional, and personal perspectives, an array of information needs was identified. Most requirements, however, seemed to fall into one of five major categories: Federal materials research activities, material standards, market and economic information, health and safety, and public policy.

Jan 1, 1990

By W. C. Winegard, A. Galibois, C. J. Beingessner

The effects of solutes on the distribution of two-dimensional configurations of grains in zone-refined tin have been studied. When solutes with partition coefficients (ko) greater than unity are added, three-sided pains become more prevalent and the growth law changes. It is shown by electron-Probe micro-analysis that a solute buildup occurs ahead of a moving grain boundary when ko > 1. It has been found recently1, 2 that solutes with partition coefficients greater than unity have a larger retarding effect on grain growth than solutes with k, less than unity. ko is defined as the ratio of the concentration of solute in the solid to the concentration of solute in the liquid with which the solid is in equilibrium. Niessen and winegard2 have suggested that this effect is probably due to the complex shape changes which occur during the process of grain growth and that no theory based on single boundary motion3-5 can explain the results. They suggested that the dissociation of the unstable fourfold junction was delayed in alloys where ko was greater than 1 because the boundaries at the junction had to move into a region of high solute concentration. If indeed this mechanism were correct, it was felt that not only would the dissociation of fourfold junctions be affected by the solute buildup ahead of the boundaries, but the collapse of three-sided grains would be impaired. These combined effects would naturally lead to a modification in the distribution of the number of sides per grain seen on a two-dimensional section. The present investigation was undertaken to test these hypotheses by examining the grain-growth process in detail. EXPERIMENTS The Distribution of Grain Configurations in Zone-Refined Tin as Seen on a Two-Dimensional Section. Following the method of Bolling and Winegard,6 zone-refined tin was cast into button-shaped specimens and, subsequently, plastically deformed under a drop hammer at room temperature. The resulting flat coin-shaped samples were annealed at 200°C, some for 50 sec and others for 100 sec. The specimens were then examined to determine the distribution of the number of sides per grain, i.e., the num- ber of crystals adjacent to any particular grain in the section. For simplicity, the grains were classified as three-sided, four-sided, and so forth; this concept is schematically illustrated in Fig. 1. As indicated by smith,' it was necessary to examine every grain within an enclosed area to obtain a proper distribution of the relative frequency of each type. The distributions for the two annealing times are illustrated in Fig. 2. The total number of grains examined is also indicated on the figure. It is evi-

Jan 1, 1965

By J. R. CAMERON

Gypsum is mined in all Atlantic Provinces except Prince Edward Island. It is generally thought to have been derived from the hydration of anhydrite in areas of minimal drainage. Late Devonian downwarping and crustal oscillation east of the Appalachian fold belt allowed the Windsor Sea to advance and retreat in a depositional trough and deposit about 1,000 m of sediments in Mississippian time, much of which were evaporites. The best areas for further gypsum development are lowland basins such as the Cape Breton Lowlands, the Hillsborough area of New Brunswick and the St. George's Lowlands in Newfoundland, all of which are already sites of gypsum quarries. Nova Scotia's gypsum is mined from the Lower Windsor Group, which is divided into subzones 'A' and 'B'; 'B' provides most of the province's gypsum production. The Atlantic Provinces gypsum industry has markets from the St. Lawrence waterway to the mouth of the Mississippi River.

Jan 1, 1984

By R L. Brathwaite

The gold-scheelite-quartz lodes of the Wakamarina valley were the most productive of the mesothermal gold-bearing areas in the Marlborough Schist. Most of the production came from the Empire City and Golden Bar mines which worked the Golden Bar lode. Only 134 m of its 1800 m strike length are accessible, in the No.2 level of the Golden Bar Mine. A fault has downthrown the Golden Bar Mine section by = 47 m and displaced it left-laterally by 18 m. The lode is a typical ribbon-banded mesothermal vein, averaging c. 1.75 m wide, and enclosing narrow horses of schist country rock. It is composed of bands of milky æbuckÆ quartz with thin laminae of schist. Scheelite occurs in short strings of grains within quartz on the footwall side of the lode and also in small quartz-carbonate veinlets in the foot wall and hanging wall schist. The lode quartz contains only localised traces of pyrite and arsenopyrite. They are more abundant in the wall-rock schist.   The Golden Bar lode lies within a steeply dipping normal fault, which, on its footwall side, is adjacent to a 40 m-wide, shallow-dipping mylonite shear zone. Within 1 m of the lode, the shear foliation has been dragged down to nearly parallel the lode footwall. Wall rock alteration is manifested by a marked increase in K and Rb, which correlate with abundant illite/muscovite and K-feldspar within 2 m of the footwall of the lode. Amphibole, stilpnomelane, and pumpellyite show a progressive decrease towards the lode. As and Sb increase close to the lode, but are at background levels within the lode itself. Enhanced Cr (150-430 ppm) in the quartz, relative to the schists (~40 ppm), suggests that the source hydrothermal fluids passed through and leached mafic rocks, such as the metabasites from the hanging wall of the lode (~400 ppm Cr).

Jan 1, 1995

By D. R. Spears

As part of its mission to develop technology to assure a continuing supply of minerals, the US Bureau of Mines has investigated the flocculation of a Stillwater, MT, chromite ore. The ore was flocculated at different solids contents and at different stirring speeds to determine the importance and effect of hydrodynamic factors. In acidic and basic pH, the chromite ore was flocculated with high molecular weight polyacrylamides differing in the degree of hydrolysis. Polyacrylamides were found to bind to chromite ore particles through hydrogen bonding. The anionicity of the polymer and the pH affected the degree of polymer-particle interaction, which in turn affected polymer conformation at the surface. A polymer conformation with many loops and tails was used to explain high flocculation efficiency. It was found that such a conformation could compensate for poor hydrodynamic conditions.

Jan 1, 1992

By Daniel Harrington

For several years the United States Bureau of Mines has been making a study of ventilation in metal mines, this study covering practically all the important mining districts of the country. One of the districts where a close and extended study was made was that of Butte, Mont., with its numerous interesting problems and conditions. In February, 1916, Daniel Harrington, mining engineer of the United States Bureau of Mines, was detailed to investigate the circumstances surrounding the death of 21 men in the fire at the Pennsylvania mine at Butte, and during that investigation he made underground visits to several of the large mines through the courtesy of the mine operators, and became much interested in the ventilation conditions. In May, 1916, Mr. Harrington was detailed te work in cooperation with Dr. A. J. Lanza of the United States Public Health Service in an investigation of the prevalence and causes of miners' consumption in the district. This work broadened so much that the investigation was not completed until late in 1918, the investigators making a detailed inspection of all working places in four large mines and a more or less extended examination of conditions in about 20 other mines. Ventilation was recognized immediately as being an important factor in the health of miners, and from the outset of the investigation a large part of the work consisted in obtaining and compiling data relative to the flow of air, humidity, and temperature. The officialsof the North Butte mine were engaged in making a study of ventilation problems before the coming of the investigators, so that opportunity was given to work with those officials for several months. Detailed data on air flow, temperatures, humidities, and an analyses had been obtained before the fire in the North Butte mine June 8, 1917, which resulted in the loss of 163 lives. Much information was obtained during the progress of the fire, and a detailed examination was conducted after the fire, hence an exceptional opportunity existed to study conditions relating to ventilation. This bulletin is a result of studies made from the data collected during the two and one-half years of study and observation a-boveoutlined. Its publication has been delayed through lack of funds for printing. Other publications relative to metal mine ventilation -in other parts of the United States are expected to follow.

Jan 1, 1923

By S. K. Singh

To meet increasing demand of coal, underground mining is largely being replaced by the exploitation at deeper horizons and with greater complexities. The exploitation-proposition may be below not-to-be-disturbed surface properties or below water-bodies, posing a constant threat of inundation. Also, the mounting pressures to limit the adverse impacts on the environment bring the extraction-undertaking to face more challenges. An understanding of subsidence-mechanism and a rational quantification of subsidence parameters is a requisite herein. This paper presents such pragmatic quantification, validated at mine-sites in India. In comparison, better productivity, conservation and safety is ensured in this approach.

Jan 1, 1999

By HOWARD RICHARDS

THE dollar was, selected as the unit of currency by the Congress of the United States of America on Apr. 2, 1792. This "Dollar" currency is so much more convenient than the older British currency that the Canadian Government, among others, has adopted it with corresponding success. Just as the dollar is the unit of United States currency, so the meter is the international unit for measuring length. The various weights and measures used in - the United States have since Apr. 5,. 1893, been based on the metric standards. These fundamental standards are kept by the International Bureau of Weights and Measures, which is supported by the United States, Great Britain and the, other leading countries. of the world. Copies are held-in Washington and other capitals. (2) As the dollar is divided into 100 cents, so the meter, which is 10 per cent. longer than the yard, is divided into 100 centimeters or cm. And as the cent is divided into 10 mills, so the centimeter is divided into 10 millimeters or mm. In measuring clothing and other articles which do not require great accuracy, the centimeter is most con¬venient, so that such work is done in terms of centi¬meters.. Instead of speaking of a 15;2-in. collar, a 40-centimeter or 40-cm. collar is referred to. Where accuracy is needed, as in mechanical drawing, machineshop work, etc., millimeters are employed. Thus 8 mm., is the convenient equivalent for 5/16 inch.

Jan 1, 1921

By Robert C. Weisner

Current production costs and market conditions in the potash industry of the Carlsbad area were studied to determine the potential values of the potash mineral resource that would be lost or foregone if the Waste Isolation Pilot Plant (WIPP) facility is constructed on the proposed site in that area. The purpose of the WIPP project is to investigate the possibility of developing a nuclear waste disposal plant in the salt formations at the site. Analyses were made of all potash deposits determined to be in the site. Mining and processing under the most favorable recovery systems were considered. Value determinations were based upon estimated operating and capital costs of current mine-mill operations in the Carlsbad area. This study was made for the Energy Research and Development Administration (ERDA) by members of the Federal Bureau of Mines Minerals Availability System staff.

Jan 1, 1979

By Paul M. Tyler

The literature on radium is already voluminous, but mcuh of it is too technical to be intelligible to the average reader, and there is no single publication that covers certain economic features of the radium industry. As a result of the renewed interest in the possibilities of domestic carnotite deposits a number of requests have been made to the Bureau of Mines for information, more particularly with reference to the business aspects of the industry. In order to meet this apparent need, the present paper has been prepared from material available in the files of the bureau. The technical data are compiled from various sources and are believed to be reasonably dependable, but the attempt has been not so much to achieve meticulous scientific accuracy as to brim; together facts of industrial significance and popular interest. GENERAL DESCRIPTION Radium is a brilliant white metal that melts sharply at about 700°C. and volatilizes appreciably at that temperature. With an estimated specific gravity of nearly 6.0, it is more than twice as heavy as aluminum and 25 per cent lighter than irons. Although it has been isolated in its metallic state, it is not used in that form, partly because it tarnishes rapidly even in dry air (forming a nitride), partly because of the greater expense of reducing it to metal, and partly because of the difficulty of dealing with such minute quantities of material. It is used always in the form of its compounds, the most important of which from the vie point of utilization are the bromide, chloride, and sulphate.

Jan 1, 1930

By J C. Volkwein, A D. A Hansen, E Sarver, C Barrett

Ensuring that diesel particulate matter (DPM) levels in underground metal and non-metal mines are maintained below statutory limits is an essential requirement of mine ventilation systems. However, despite the cost of providing ventilation, air ventilation rates are usually based upon models, assumptions, or measurements integrated over long durations rather than actual need. Real-time measurement of DPM, interpreted in terms of mine activity schedules, can offer better ventilation management to keep DPM within regulated levels while controlling costs. This work presents data from three demonstration sites with in-mine applications of an environmental particulate sensor that measured black carbon (BC) as a surrogate for DPM.Aethalometers are a class of environmental monitors that measure the light absorbance of aerosol particles at several optical wavelengths. A model AE33 Aethalometer was operated in three separate mines for periods of two weeks, three months, and seven-plus months, and the data was reported in real time as a concentration of BC. Concentration of aromatic organic compounds, which can indicate other forms of combustion, was also reported. The data was used to:- measure the relative efficiency of a new scale-model DPM air scrubber- determine if ventilation could be reduced in a shotcrete loading facility without compromising air quality- evaluate diurnal and weekly DPM levels in a large-entry stone mine. Instrument data were displayed locally and stored for later downloading in all cases. In one mine, the instrument was connected to a local controller, and in another it was connected to the mine’s underground network so that DPM data was presented in real time to a display in the mine ventilation engineering office on the surface.The results showed that the air scrubber removes from 82 per cent to 95 per cent of the DPM; that DPM produced during shotcrete loading is only a minor part of overall DPM levels; and that wide variations in DPM levels exist in the limestone operation. The DPM monitor operated continuously for extended periods in these underground environments. The only maintenance required was the routine replacement of filter tape, typically on a two-week schedule. A sample diluter, which is currently being tested, could extend the intervals between filter changes. The real-time data output of the Aethalometer is appropriate for direct integration into ventilation-on-demand control systems.CITATION:Volkwein, J C, Barrett, C, Sarver, E and Hansen, A D A, 2017. Application of an environmental ‘black carbon’ particulate sensor for continuous measurement of DPM in three underground mines, in Proceedings Australian Mine Vent Conference 2017, pp 143–150 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017