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By Lloyd A. Morley

This report abstracts project work performed under USBM Grant GO155003 during the period 4 November 1975 to 3 November 1976. The research was funded, as a continuance of previous support from USBM Grants GO133077 and G0155003, to gain further knowledge in mine electrical system safety. Five reports have been separately produced, all under the grant title, "Coal Mine Electrical System Evaluation," and are as follows: 1. Volume I - Continuous Monitoring, 2. Volume II - Transient Analysis, 3. Volume III - Shielded Cables, 4. Volume IV - Computer Modeling, and 5. Volume V - Battery and Battery-charging Safety. Abstracts of these comprise the balance of this document with one exception. The task ?d-c offsett currents," does not fall under the scope of the other report volumes and, further, the material to be presented does not justify a separate report. Hence, this subject concludes the Executive Summary.

Jan 1, 1977

By Jarvis ST

Colliery spoil is the major constituent of colliery spoil 'rockpaste' which has been used to infill abandoned limestone mines in the West Midlands of England since the early-1980s. The other constituents of rockpasle are pulverised fuel ash, lime and water. A key property of the rockpaste is its ability to flow within the mine workings over considerable distances before setting. This paper describes the work carried out to identify suitable sites as sources of colliery spoil for making rockpaste and goes onto consider the flow properties of the material and the monitoring methods used on-site. A full-scale trial comprising mulling a 6600 nt' section of an abandoned mine was conducted prior to the mulling of the Littleton Street Mine which had a volume of about 500 000 m'. As well as describing the methods used for monitoring the movement of rockpaste material, a description is also given of a dip-meter developed specifically for the purpose of measuring the level of paste in the mine. This paper shows how a colliery spoil based paste has been successfully rued for infilling abandoned mine workings. The monitoring systems developed for use in the two case studies presented in this paper are now being used extensively for infilling other abandoned mine workings. To-date over I I mines with a total volume exceeding two million cubic metres have been backfilled.

Jan 1, 1998

By D. W. Jessup

ONLY during the past few years, have the old-fashioned methods for treating ores and byproducts progressed to any marked degree. The advent of multiple-hearth roasting, blast roasting, the baghouse, and the Cottrell plant indicate this change. It is the ability to roast and smelt sulfide ores and concentrates that gave this later advance. Further investigations that will solve the problem of efficient handling of flotation concentrates and their attendant ills are of the utmost importance. With future developments, the metallurgist will be able to smelt more economically and to treat still more refractory ores, making the early methods appear small by comparison. GROWTH OF SMELTING Well within the memory of pioneer smeltermen, the ore was charged directly into the blast furnace as it came from the mine;, only the richer, ores were smelted, the lower grade and sulfide ores were undesirable. Matte was, at first, thrown away and only two products) were desired-slag and lead bullion. Scores of the early smelting companies failed because of improper reduction of ores, high costs, short- furnace campaigns, inability to treat sulfide ores, and ores containing-zinc. With the failure of weaker companies, consolidation eliminated many others, until today the field is dominated by a comparatively few organizations, each strong financially. Formerly, a few thousand dollars would erect a small plant, whereas the modern smelter costs over a million dollars. Ore and products to which formerly no attention was paid are now treated with comparative ease and at a good profit. Mechanical improvements have modernized smelting, furnace tonnages show an increase, and metal recoveries have made enormous strides. Even though costs have decreased, they have not dropped in proportion to the improvements, because of the higher wages, greater costs of fluxes and coke, more undesirable ores smelted, etc.

Jan 8, 1925

By Jorge Munoz Reyes

There are three main oil areas in Bolivia (Fig. 1) although so far only one has yielded petroleum in commercial quantities. The Sub-Andean zone is along the easternmost ranges of the Andes, bordering the large eastern and northeastern lowlands. It extends from the Peruvian frontier, north of Lake Titicaca in a southeasterly direction towards the city of Santa Cruz and from there southward to the Argentine border. This zone forms a belt about 1200 km. long by 100 km. wide, and comprises a series of parallel, very rugged, low ranges. Oil has been known and utilized by the natives in these regions since colonial times, from the large number of seepages, which in modern times have led to the discovery of many fields. The second oil zone of Bolivia lies along the eastern and southern borders of Lake Titicaca, on the Andean high plateau, at an average altitude of 13,000 ft. above sea level. It comprises an area of approximately one million hectares (2,470,000 acres). Several seepages are known here, but little development has taken place, because of the difficulties encountered, as the greater part of the territory is covered by volcanic tuffs and ashes, which conceal the structure underneath. The third area is called the "Central zone," and is in the heart of the country, in the Department of Cochabamba, covering approximately five million hectares (12,350,000 acres). This area consists mainly of broad valleys flanked by low rolling ranges. Natural seepages are not known to exist, but there are secondary evidences of the presence of oil. The outcropping rocks are mainly Paleozoic (Silurian and Devonian sandstones and shales). Albertite and other forms of polymerized petroleum have been found in this region. Of these three main oil areas, only the first one is at present productive on a small commercial scale. This zone, developed almost exclusively by the Standard Oil Co. of Bolivia, a subsidiary of the Standard Oil Co. of New Jersey, is divided from south to north into the following local fields: 1. Bermejo (On the Argentine border) 3. Sanandita 5. Camatindi 2. San Telmo 4. Caigua 6. Machareti

Jan 1, 1935

By J. O. Marsden

The 1980s saw a revolution in gold extraction technology, paralleled only by the implementation of the cyanide leaching process in the late 1800s. This revolution was led by the widespread adoption of carbon adsorption processes for gold recovery, heap leaching of low-grade ores and development of a variety of oxidation processes to treat refractory ores. In the late 1980s, gold production in almost all regions of the world increased, with the notable exception of South Africa. This geographical variety is creating a greater diversity of challenges for gold metallurgists. This is due to a wider range of ore types, new and varied environmental regulations and legislation, and a requirement to select the most appropriate technology to suit local needs. North America has led this technological revolution in the gold industry and is responsible for commercialization of most of the major innovations: carbon-in-pulp, heap leaching, whole ore pressure oxidation and whole ore roasting. Process selection trends A general trend in precious metals extraction technology has been the treatment of ores with progressively lower grades. The lowest cost treatment, dump leaching of material at run-of-mine size, has been increasingly applied. ZortmanLandusky, in Montana, is successfully leaching material above a cutoff grade of 0.2 g/t (0.006 oz/st) at an average rate of about 28 kt/d (31,000 stpd). At this scale of operation and in the absence of any cyanide-consuming species in the ore, process operating costs for a ge¬neric run-of-mine leaching operation are estimated to be between 60 and 75 cents/ t (66 and 77 cents/st). One of the largest heap leach opera¬tions treating crushed ore is the Round Mountain Mine in Nevada. It processes about 45 kt/d (49,000 stpd) at an average grade of 1.1 g/t (0.032 oz/st) at a nomi¬nal crush size of 80% -19 mm (-0.7 in.). Round Mountain also treats lower grade ore above a 0.2 g/t (0.006 oz/st) cutoff by dump leaching at run-of-mine size.

Jan 1, 1993

By D. W. R. George, J. L. Stewart

Developments in the last decade, which have contributed to increased productivity and decreased coke rates in the iron blast furnace, are reviewed. Future progress in blast-furnace practice is also considered.

Jan 1, 1966

Five conclusions that emerged from ADL's Contractor Noise Measurements Assessment done for the Bureau of Mines and the 7 December 1971 Bureau of Mines Contractors' Round Table Meeting in Boulder, Colorado were: ? a limited amount of good data has been obtained for characterizing the noise environment for electromagnetic (EM) coal mine operational/emergency communications systems; ? significant noise date gaps still exist; ? suitable instrumentation and data analysis methods are available for filling these data gaps; ? the immediate and most important data gaps should be filled by means of a timely field measurement effort that is purposely limited in scope and duration; ? this field measurement effort should preferably be carried out by a team knowledgeable and experienced in coal mine EM noise measurements.

Jan 1, 1972

By AIME AIME

This volume, an octavo of 626 pages, is now ready for delivery. By its aid, any subject treated or alluded to in the Transactions can be instantly tracked. The names of persons, mines, works, towns, etc., have been included; and abundant cross-references and classified sub-headings have been added to facilitate rapid consultation. Thus, the student remembering the name but not the locality, or the locality but not the name, or neither the name nor the precise locality of a gold-mine, can find it under ?Gold-mines," or under either of the other heads. For a more extended statement of the nature and use of this Index, which is intended specially for the benefit of those who do not possess complete sets of the Transactions, and who consult the Library by correspondence, see the Bi-Monthly Bulletin for September, 1907. The price of the Index bound in cloth is $5, delivery charges prepaid. Half-morocco binding costs $1 extra. Buy at once a copy of this Index, and also as many back-volumes of the Transactions as you can afford. Every such purchase from the stock on hand is so much added to the income of the Institute. As far as possible, the money thus received will be devoted to maintaining and perfecting the Library, and making it useful to members in all parts of the world.

Jan 11, 1907

By George W. Toth

In a recently completed research project for the U.S. Bureau of Mines - Twin Cities Research Center, a computerized costing procedure for uranium in situ leach mining was developed by the NUS Corporation. This costing procedure, termed a cost model, employs a process engineering approach for estimating total project costs as well as equipment and manpower requirements for uranium in situ leaching operations in either Texas or Wyoming. 80th capital and operating costs are generated by the model along with the overall production cost/pound U3O8 subject to a known rate of return. Conversely, rate of return on equity can be solved for, subject to a given price of yellowcake. During the course of the research effort, this cost model was applied 50 typical site conditions in Texas and Wyoming. Sensitivity rests were conducted for numerous key parameters to determine the cost influence attributable to incremental changes In parameter values. The results of these sensitivity tests along with a description of the in situ leaching cost model have been documented as Bureau of Mines, Mineral Research Contract Report No. J019912, "Cost and Sensitivities Analysis for Uranium In Situ Leach Mining," dated March 1981.

Jan 1, 1981

By Y. Rama Murthy

Around 90% of the chromite resources of India are concentrated in the Boula-Nuasahi Sukinda belt of Orissa state. In order to conserve these valuable ore resources strategically, several companies established chrome ore beneficiation plants in this region. The general beneficiation process in these plants consists of gravity unit operations such as Floatex density separator, spiral, wet shaking table etc. Most of these gravity circuits suffer huge losses of valuable minerals in the tailing. Any attempt towards decreasing these losses would not only increase the limited reserves in India but also make the economics of the operations more attractive. Apart from the liberation phenomena, in many of the operating plants considerable quantity of values are lost in the tailings, due to inconsistent feed quality, inappropriate selection of operating and design parameters. Mineral engineers in this regard have to play a proactive and continuous role to improve the performance of all separating units by modifying even small changes based on tests conducted in laboratory under controlled conditions followed by attempts to make necessary changes in the plant. For such improvements, accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play a very critical role in performance of the circuit. Databank collected over a period of time under various conditions would also help in overcoming the future problems related to either variation in the feed characteristics or specific demand by metallurgical industries. The above concept was adopted in one of the operating chromite beneficiation plant at Sukinda. The approach adopted and practical problems encountered during the study were reported in this paper. The result of trial campaign has shown that, an overall product assaying 30.2% Cr2O3 from the feed (18% Cr2O3 ) can be produced to in single stage. The final discards of the process contain 12% Cr2O3. Keywords: chromite, chromite beneficiation, chromite losses, gravity concentration techniques, plant operating data bank

Sep 1, 2012

By J Steyn

Block Cave mining is one method used to extract ore from underground diamond mines as well as other massive orebodies such as copper. This necessitates the excavation of many kilometers of tunnel within the ore body. The integrity of these excavations needs to be maintained over a number of years. Most Kimberlites and weak orebodies are extremely susceptible to degradation when exposed to moisture and the atmosphere. It is therefore essential that some form of weathering protection is applied as soon as possible after exposure. Conventional methods of weathering protection such as shotcrete do not easily fit in with the production schedule, hence the need for a more efficient system that could be applied immediately after exposure and serve as a temporary support or even as a permanent support medium. The main advantages of thin sprayed liners (TSL) compared to shotcrete are the ease of application, speed of application, early strength, much reduced transportation of material, less labour intensive and cost effectiveness. Several Thin Sprayed Liners suitable for various mining environments and geotechnical conditions are available and could be well suited as additional support the undercut level development in a block cave where this may be required. TSL offer a cost effective support solution as an alternative to shotcrete in areas where the building of a support structure is not a requirement.

Jan 1, 2008

By Shinichi Konda, Gary Nishimura

"Thousands of years ago large glaciers carved much of the landscape in Puget Sound, depositing abrasive and granular soils including cobbles and boulders along with layers of clay and sand. Tunneling in this geology – common throughout much of the northern and Midwestern U.S. – is challenging and can be unpredictable. The use of pressurized face tunneling, most commonly with EPBs and slurry type machines, has made excavation in this geology more efficient, but difficulties still remain. Through analysis of recent projects in Seattle, Washington, USA, the authors draw conclusions as to the best TBM designs and operational parameters for this variable, abrasive and often difficult ground. Performance data is analyzed with an eye towards advancements that could further improve TBM tunneling in glacially deposited soils. INTRODUCTION Over the past several ice ages, extensive glaciers reaching across much of North America transported large amounts of soil and rock as they moved across the land. The substantial weight of the ice sheets mixed together a wide range of soil types along with a variety of rocks and boulders of all sizes. Many rock formations were reduced to pebbles or particles containing highly abrasive characteristics. Any boulders able to survive were generally comprised of harder materials which were scattered throughout the soil. This highly variable mixture of abrasive soils and high strength boulders can be found in many areas across the Puget Sound and other regions of the country. Wherever they are encountered, they often create a difficult and unpredictable mining environment for both equipment design and operation. Modern TBMs are optimized early in the design process for specific types of geology, and unexpected conditions can require extensive modifications. In addition, several operational parameters need to be adjusted to balance ground characteristics, and advance rates can be significantly affected in mixed and rapidly changing soil conditions. Both EPB and slurry machines can be used successfully in these conditions, provided their respective operating criteria are met. Ideally, an EPB is operated with a relatively thick muck consistency, which accommodates moderate changes in soil permeability and maintains a reliable pressure differential through the screw conveyor. However, this also causes higher wear on rotating components and requires more energy at the cutterhead. Alternatively, slurry machines typically operate best with a more fluid muck consistency that can be easily pumped through the extensive piping system. This tends to reduce the wear on the cutterhead and the power requirements of the cutterhead drive system, but also makes the machine more sensitive to changing soil conditions. Generally, the slurry piping system is also more capable of controlling high face pressures, although the screw conveyor of an EPB can also be designed to accommodate most high-pressure conditions."

Jan 1, 2016

By E. C. Wright

FOR many years the cost of making pig iron and steel in the Birmingham district has been about the lowest in the United States. The close proximity of the important raw materials such as coal, iron ore, limestone, and the large available scrap supply made it possible to assemble all of the important ingredients necessary for steel- making with only nominal costs for transportation. Both iron ore and coal were being mined in this district at one time for about $1 per ton from underground operations. At that time mining wages were low everywhere and the labor rate in the South was considerably below that of other mining districts. This situation persisted until the emergence of labor unions as an economic and political force, emigation of southern labor to northern plants, and continued growth of industry in the South in the years following the depression of 1932. Since that time union organizing of miners and steel workers throughout the nation has increased labor costs in mining and steelmaking. This influence has been felt particularly in underground mining operations since the proportion of labor cost to total cost is still high. The previous advantage in basic labor rate in the South has been almost entirely eliminated by the equalization of labor rates in basic industries by national unions. Since 1945 these influences have been especially noticeable in increasing the cost of mining coal and iron ore in the South. The northern steel districts are still being largely supplied with iron ore from the Minnesota open-pit mines and the cost of this ore has not increased nearly as much as the cost of ore obtained from underground mines in Birmingham. A similar situation exists in coal mining; the thinner seams in Alabama are not so amenable to mechanization as the northern mines and, as a result, the output per man-day in southern mines is only about three tons of coal as compared to five or six tons per man-day in the large captive mines of West Vir-

Jan 1, 1950

By D. H. Newland

On the bulk basis New York's contribution to the production of oil is small, representing, as it does, a bare half of one per cent of the annual total for the United States. Yet it has more importance than is implied by such a statement. Petroleum includes a variety of organic compounds, some more and some less valuable. It would be a fairer estimate of the situation to say that New York in recent years has produced around 10 to 12 per cent on the average of all Pennsylvania grade oil, the supply of which is strictly limited and the demand steady even in times of overproduction of other grades. One may not infer from this that New York and other Appalachian states enjoy an independent position in the market with a price structure uninfluenced by that of the Mid-Continent, Gulf or California fields. On the other hand, the recent market demoralization in the South and West brought about by uncontrolled production caused prices to drop to a point where the life of the local industry was seriously threatened. The current cost of producing oil in New York under the methods of water-flooding, by which most of the output is now obtained, has been estimated by competent authority at not less than $2.50 a barrel. The

Jan 1, 1934

By C. C. Shale

A semicommercia1, high-temperature electrostatic precipitator and adjunct equipment are described, and operating characteristics at 1,470° F and 80 psig are presented for both positive and negative polarity. Removal efficiency for negative corona waS about 91 to 96 percent while that for positive corona was only about 75 to 77 percent. Results are compared with those from bench-scale investigations, and equipment limitations are discussed. Theoretical aspects of the precipitation process are related to the operating characteristics.

Jan 1, 1969

By D. W. Scott

Ontario has a diverse industrial mineral resource base including abundant resources of structural industrial minerals such as sand and gravel, crushed stone, building stone, clay, shale, limestone and dolostone. These resources are used in the production of aggregates, brick, metallurgical stone, fillers, lime, cement and other construction materials. The majority of the operations are in deposits of Paleozoic and Quaternary age in southern Ontario, close to the major markets. Province-wide, there were over 140 million metric tonnes of aggregates produced in 1985, approximately 115 million tonnes of which was produced in southern Ontario with the remainder being largely from Crown land in northern Ontario. The structural industrial minerals account for over 80% of the value of total industrial mineral production, with the remaining 20% of the value king accounted for by the non-structural minerals being led by salt which is produced in southwestern Ontario. A host of other non-structural industrial minerals are known but production is currently restricted to calcite, gypsum, quartz, talc, nepheline syenite and by-product metallurgical sulphur products (Fig. 1). Location and Market Area Major production is in the area closest to the large markets of urbanized southern Ontario and the northeastern and north-central United States. In general, with the abundant variety and widespread resources of industrial minerals and the large population within 400 miles of most deposits, the market offers great potential. Ontario's 9 million population accounts for about 35% of the entire gross domestic product of Canada of $476.361 billion dollars in 1985. This equates to about 113 of the nation's buying power being within a 200 km (125 miles) radius of Toronto. This major concentration of industrial and economic activity has resulted in a well developed industrial minerals industry fulfilling most of the structural industrial minerals demand in Ontario, as well as a subsidiary demand in neighbouring provinces and states.

Jan 1, 1987

By Laszlo Kadar, J. D. Lavers

"In the continuous casting of aluminum killed steel, the tundish nozzle often experiences clogging problems. Water model studies have shown that the clogging problem is dependent on the flow pattern in the nozzle entry region. In particular, the flow can separate at the entrance to the nozzle, leading to the development of a recirculation region. Although a nozzle can be designed such that no recirculation develops, even a small misalignment from the vertical positioning of the nozzle may render the design ineffective.To reduce the possibility of nozzle clogging, the recirculation zone must be reduced or eliminated. This may be achieved by moving the fluid downwards or raising the turbulence level in the separation region. In the case of a tundish nozzle, it is proposed that this can be achieved by using electromagnetic forces.To generate the required electromagnetic force, two systems are considered. The first is based on injecting a DC current; the second by using electromagnetic induction. Both methods are described in this paper. Order of magnitude calculations are provided to illustrate that both methods are essentially feasible. The performance of each method in terms of modifying the turbulent flow characteristics in the nozzle entry region is then examined using a numerical model. It is shown that both methods can greatly reduce the recirculation zone. A cylindrical nozzle was chosen for the model studies since it represents a worst case situation.On the basis of the model studies, it can be concluded that whereas both of the proposed methods have the potential to reduce the troublesome recirculation zone, the induction method appears to be simpler in terms of practical implementation."

Jan 1, 1999

By S. K. Kawatra

Outokumpu Electronics has designed a new on-line coal slurry ash analyzer, based on an instrument developed at Michigan Technological University. The primary goal was to build an accurate instrument at the lowest possible cost. The instrument determines ash content from measurements of x-ray backscatter, iron Ka fluorescence, and low-energy y-ray absorption. It is capable of measuring the ash content with a standard error of 1.1% ash over an analysis range of 9-21% ash and 7-22% solids. The analyzer was tested on coals from United States, Poland, Great Britain and the USSR.

Jan 1, 1992

By Y. Y. Jiao, J. G. Cai

To investigate the dimensional effect on shock wave propagation in jointed rock masses, a 2-D and a 3-D calculation of a site test are performed respectively by using Discrete Element Method, the simulated results are compared with test data. It shows that, in modelling shock wave propagation and attenuation in jointed rock masses, when the explosive along explosion chamber is long enough and the joints are dense enough or uniformly distributed, the model can be considered as plane-strain problem, 2-D results are good enough to fit with test data. 2-D modelling, with much more details of rock masses taken into account, can be applied to make critical engineering judgements instead of 3-D modelling in some cases.

Jan 1, 2003

By Jean-Marc Simard, Vincent Jourdain, Denis W. Roy

"Seven lithologic units, informally characterized, were recognized in the vicinity of the Montauban orebody. The first five lie in stratigraphic order. From structural bottom to structural top these are: (1) grey composite gneiss; (2) dark grey quartz-biotite gneiss; (3) quartz-biotite-garnet gneiss hosting several calcareous, aluminous and magnesian members and gold mineralization; (4) light grey quartz-muscovite-(sericite)-biotite gneiss; and (5) metabasafts. The last two intrude the sequence: (6) amphibolite dykes and (7) pegmatite veins. The orebody lies on the inverted limb of an overturned synform verging to the west with the metabasafts marking the core of the fold. As the foliation is folded, this fold is attributed to deformation ""D2""; deformation ""DI"" being responsible for the formation of the foliation. A late brittle deformation developed shear zones with probable strike-slip motions. The refined stratigraphy and the identification of the structural position of the orebody provide new tools for regional interpretation and prospecting.RESUMESept unités lithologiques ont été définies informeffement à proximité du gisement de Montauban. Les cinq premieres reposent en ordre stratigraphique; ce sont de la base au sommet structural: (1) le ""gneiss mixte gris""; (2) le gneiss gris forcé à quartz biotite; (3) le gneiss a quartz-biotite-grenat comprenant plusieurs membres calcareux, alumineux et magnésiens ainsi que la minéralisation aurifère; (4) le gneiss gris clair à quartz muscovite- Isericitel-biotite; et (5) les métabasaltes. Les deux autres unites sont intrusives dans la sequence: (6) les dykes d ‘amphibolite et (7) les veines de pegmatite. Le gisement se sitlie sur le flanc inverse d'un synforme déverse vers I' ouest dont les métabasaltes occuperaient le cœur. Comm e la foliation est plissée, ce pli est considère appartenir d la deformation ""D2""; la deformat ion ""DI"" etant responsable de la formation de lafoliation. Une deformation cassante tardive se traduit par des zones de cisaillement, d rejet apparemment directionnel. Cette stratigraphie plus précisé et l'indentification de la position structurale du gisement fournissent de nouveaux omits de prospection et d'interprétation regionalé."

Jan 1, 1987