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By P. C. Thakur

Frictional ignitions (also called face ignitions) is defined as the rapid oxidation of a mixture of methane and air with a visible flame that could last from a few seconds to several minutes. These ignitions have a potential to turn into a mine explosion and eventually a large-scale mine fire. Over the last 22 years, U.S. coalmines have had 1566 frictional ignitions. There were no fatalities but serious injuries have occurred. Every effort, therefore, should be made to prevent frictional ignitions. The preventative measures fall under four categories: (a) degasification of coal seams prior to mining, (b) adequate ventilation, (c) wet cutting or water-jet assisted cutting and (d) machine design to minimize ignitions. The paper discusses each of these techniques in detail.

Jan 1, 2006

By A. M. Gaudin

THE purpose of ore dressing is to separate the rough ore into one or several valuable concentrates and a discarded tailing. The first step is to crush the ore so that the resulting particles may be individually valuable or worthless. The next step generally has to be a sizing operation, because the property by which concentration is effected depends on the size of the in-dividual mineral particles as well as on their physical properties. These two effects may cancel each other if a preliminary sizing is not resorted to. Sizing is accomplished by screening or classifying. Screening depends almost solely on the dimensions of the particles; classifying depends also on the specific gravity of the particles and the viscosity of the settling medium in which the classifying operation is conducted. Classification, therefore, is to a certain extent a con-centrating operation as well as a sizing operation. Before the days of concentration by flotation, the available screens were mechanically poor. As a result classification was employed for sizing in the range. of comparatively coarse sands (table feeds). In recent years, the advent of stage-grinding to flotation size has brought about the development of good screens, which are more economical than classifiers down to about 20, -mesh. With decreasing size at which separation is to be made, screens become increasingly uneconomical, while classifiers become increasingly economical. The line of demarcation between the respective fields of screening .and classification is, therefore, fairly sharp. With the development of processes of concentrating finely comminuted ore, the need for classifiers or other sizing devices operating so as to make efficiently a split at a very fine size has become increasingly apparent. Such classifiers might be termed de-slimers, from the fact that they separate a material having a slimy ap-pearance from one having the characteristics of a sand. Sizing-tests are carried on by means of testing sieves, the finest of which have apertures of about 1/500 of an inch. The 200-mesh sieve, which has an average open-ing of 0.0029 linear inches is generally considered the limit of practical test-sizing. As a result, little is known of minus 200-mesh material and the advantages of classifying concentrator feeds within the minus 200-mesh range has been overlooked. An extension of the -present sieve scale beyond the 200-mesh screen is given in Table 1.

Jan 2, 1927

By N. Ahmed

The collection of hydrophobic particles in the froth phase in flotation has been studied. A continuous flotation cell was developed, in which the froth phase could be isolated from the pulp zone. Hematite particles, d80 = 87 µm, were floated in the pulp, using a conventional oleate collector, while glass spheres of similar diameter, d80 = 82 µm, were introduced in wash water added to the froth. Four samples of glass spheres, with contact angles between 0 and 82 degrees, were used. The results indicate that the efficiency of collection of the hydrophobic particles in the froth can be very high. The process is strongly influenced by the hydrophobicity of the particles and the surface area available for attachment in the froth. Recommendations for the flotation of particles in the froth phase are made, especially regarding the desirable hydrophobicity as reflected in the contact angle, the froth depth, the solids concentration in the feed to the froth, the air rate and the wash water rate.

Jan 1, 2001

By P. T. Bloomer

Introduction Mining of the orebody of the Sullivan mine, which is owned and operated by the Consolidated Mining & Smelting Company of Canada, Limited, has reached a point where pillar extraction is rapidly becoming a major part of the operation. Very few of the larger pillars have been completely extracted; consequently, this paper contains much that is theory and expectation. Due to early mining methods and the physical characteristics of the Sullivan deposit, similar conditions may not exist in other older mines facing the problems of pillar extraction, but it is thought that the methods employed and those contemplated may be of general interest. History The Sullivan orebody, which is at Kimberley in the Fort Steele mining division of the East Kootenay district of British Columbia, was discovered in May, 1892, by Messrs. Sullivan, Smith, Cleaver, and Burchett. After passing through the hands of several owners the property was optioned in 1909, and purchased in 1910, by The Consolidated Mining and Smelting Company of Canada, Limited. Early mining was highly selective, the objective being a clean, high-grade silver-lead ore. By 1923 the difficulties of milling the very complex ore had been overcome and the first unit of a concentrator was completed with a capacity of 2,500 tons daily. Capacity was increased by stages to the present rate of 8,500 tons per day. Concentrates are shipped over the Canadian Pacific railway ? to the Company smelter at Tadanac, British Columbia, for final treatment. Approximately 45,000,000 tons of ore has been mined to date.

Jan 1, 1948

The first part (lH of this work dealt with the process of recrystallization of single crystals of lead after deformation by creep, as revealed by macroscopical examination. It was shown that when recrystallization commenced, a crystal, termed the primary crystal, started to grow at the edge of the specimen and extended into the body of the specimen along the slip planes. At some stage during the growth of this crystal, other crystals appeared at the boundary of this first crystal and fragments of the parent crystal. From thispoint, recrystallization was accelerated with relatively rapid necking down of the specimen until fracture occurred.All those crystals formed after the primary crystal were given the term secondary crystals. In the present paper is given a detailed account of the orientations of the primary and secondary crystals.EXPERIMENTAL METHODThe size of the test pieces and the manner of loading were given in the previous paper (1). X-ray back reflection photographs were taken of the individual primary and secondary crystals and from them were determined the orientations. The path of the X-ray beam was perpendicular to the surface of the creep specimen.In view of the large number of photographs needed, gold...

Jan 1, 1940

By C. W. Elder

"INTRODUCTION This report describes a method of horizontal drilling in an oil-producing formation underlying a 400-acre, approximately square plot of land in the Franklin Heavy oil field in Sugar Creek Township, Venango County, Pa. The method, which was developed on two previous projects in Ohio, 3/ consists of sinking a shaft to the bottom of a shallow oil sand and drilling holes in a general horizontal plane outward from the chamber in a pattern similar to that of the spokes of a wheel. The project was undertaken by the Venango Development Corporation in an attempt to find an efficient method of recovering oil from partly depleted sand formations.The Venango Development Corporation is composed of the following oil-producing and oil-refining companies and individuals: South Penn Oil Co., Forest Oil Corporation, Kendall Refining Co., Minard Run Oil Co., Quaker State Oil Refining Co., The Pennzoil Co., Alliance Oil Corpo¬ration, United Refining Co., Franklin Creek Refining Corporation, Canfield Oil Co., Pennsylvania Refining Co., Page Oil Co., Freedom Oil Co., D. W. and D. S. Grant, and J. P. Herrick, C. M. Davison and N. V. V. Franchot. Engineering features of the project were supervised by a committee off three engineers A. J. Saxe, chairman, W. M. Shoemaker, and C. N. Pfohl, who supervised the excavation of the shaft and the drilling of the first two holes by alternately spending a week at a. time at the project. The drilling method was under patent license from Leo Ranney, who served as technical advisor to the Venango Development Corporation; in addition, he furnished the design for the shaft and work chamber."

Sep 1, 1944

By C E. J de Ronde, I C. Wright

Oceanic subduction-related volcanic frontal arcs extend over 20 000 km within the western Pacific basin and over 21 500 km worldwide, yet they remain largely unexplored with respect to active seafloor mineralization. Systematic exploration of 26 major submarine volcanoes along ~840 km of the Kermadec arc northeast of New Zealand has documented ten (39 per cent) as being hydrothermally active. This frequency of venting is comparable to that on slow-to-moderate rate spreading mid-ocean ridges, which comprise ~80 per cent of the 60 000 km-long global system of spreading centers. The chemistry of fluids discharged from the Kermadec arc volcanoes is moderated by magmatic components in both the gaseous (CO2 + SO2-H2S) and liquid (Fe) phases at very high concentration.The high frequency of venting coupled with chemically rich discharge discovered during this first systematic survey of any arc system forecasts submarine arcs as being important sources of chemicals to the oceans and as potentially lucrative exploration sites for seafloor mineralization. The exploration protocols developed during these surveys include bathymetric mapping of mostly unknown volcanic edifices, followed by detailed water column profiling and sampling to detect and characterize volcanic fluid emission signatures. These procedures are being refined as the survey progresses, both for efficiency and as direct seafloor observations become available for predictive application of water column plume information to guide seafloor mineral exploration.

Jan 1, 2002

By K. L. Paciorek

The aim of the present study is to determine on a gram per gram basis the toxic products of the thermal oxidative degradations of selected compositions. Four families of materials were investigated under the subject contract namely polyvinyl chloride and neoprene compositions, rigid urethane foams I and woods. Three methods were employed to conduct the thermal oxidative degradations: a sealed system (quiescent environment) I a stagnation burner arrangement (dynamic environment) I and a flow-through apparatus (dynamic I but less severe than stagnation burner conditions). The majority of tests were conducted using the first two systems; only limited experiments were carried out employing the third decomposition procedure. All decomposition was done at temperatures of 370 -4000C I the higher temperature being used in the stagnation burner. It has to be stressed that the nature of the products and the relative product concentration are temperature dependent. Thermogravimetric and differential thermal analyses were performed to supplement and extend the above delineated studies and to explore the feasibility of using these analyses as a method for material differentiation.

Jan 1, 1973

By J. D. Miller

Characterization of feed material with respect to expected concentrate grade and recovery is fundamental to the design of improved separation efficiencies and to achieve sustainable development in the utilization of our mineral resources. An important reference point for this characterization is the liberation-limited grade/recovery curve which represents the perfect separation, the best separation which can be achieved for a given feed material limited only by the extent of liberation. Now, liberation-limited grade/recovery curves can be determined based on 3D mineral liberation analysis of feed material. Thus, actual separation efficiencies can be compared to what might be expected for a perfect separation limited only by the extent of liberation. It is shown that 3D mineral liberation analysis based on X-ray micro CT (XMCT) is preferred to 2D section analysis which overestimates the extent of liberation. By way of example, procedures and experimental results are presented and discussed for feed material in the case of phosphate rock flotation.

Jan 1, 2009

By Hwasoo Park

Keywords: FC mold, Argon, Magnetic, Solidification Fluid flow plays a significant role for steel surface quality in continuous casting. Although water models are able to model fluid flow, the flow pattern is not of practical interest since the moving solidifying shell cannot be accounted. Computer modeling has become a popular and dependable tool to analyze the complex phenomena occurring in continuous casting. In this numerical simulation we coupled momentum and energy equations considering the solidification of steel along with turbulence ?-e model. The vertical bending mold is equipped with bifurcated nozzle with 15 degrees of port angle. FC mold is supplied with DC induced magnetic fields. Influence of argon and magnetic fields on molten steel flow and heat transfer is investigated by solving momentum equations adding source terms due to multiphase ? magneto hydrodynamics. The results show that magnetic fields reduce the jet velocity from port by lower magnetic core induced field but the influence on meniscus velocity is complex to describe. Magnetic fields increase surface temperature and homogenize its distribution on surface and inside a mold.

Jan 1, 2005

By Jeffrey Meissner, Charles Dowding

Cracking is one of the concerns cited by owners of structures adjacent to construction or mine blasting. During the past decade a large number of measurements have documented the low level of crack response produced by typical, ground motions compared to those produced by climatological effects. These data support the observation that there is a level below which ground motions do not cause even cosmetic cracking. As with all new findings, these crack response measurements need to be thoroughly investigated for all possible alternative interpretations. Among these alternatives is that uncracked locations are more affected than cracked locations. This paper presents measurements to shed light on the influence of existing cracks and the response of uncracked, but weak locations. Blast and weather induced responses of cracked and uncracked areas of gypsum wall board are compared in two structures: one near a surface coal mine in Indiana, the other near a limestone quarry in Florida. The ground motions that excited one of the structures were unusual in that the dominant excitation frequencies of 5 Hz were near the structure’s natural frequency and amplitudes exceeded 0.7 ips (18mm/s).

Jan 1, 2011

By William X. Chavez

The Mantos Blancos copper-silver district, a major copper-producing area since 1961, is located on the Tropic of Capricorn about 45 kilometers northeast of the northern Chile port city of Antofagasta, as shown in Figure 1. Copper oxide minerals occurring as atacamite (Cu C1(OH)3) and chrysocolla (copper silicate-hydrate) were discovered in the district in the early 1900's (Knobler and Joseph, 1962). The mine is situated in the northern Atacama Desert, one of the most arid regions on earth, and presently receives less than 1 cm per year of precipitation. The extreme aridity of the Atacama Desert is thought to have prevailed since at least Middle Miocene time (Mortimer et al., 1978) when development of important supervene copper enrichment was slowed in many areas of northern Chile (e.g., Chuquicamata, Exotica). Despite the paucity of precipitation, landform development is mature, with large alluvial fans and alluvial-filled valleys covering much of the region. In addition, the aridity and presence of salts have led to the formation of a sub-surface cementing of alluvium and colluvium by halite-rich caliche ranging from a few centimeters to over 3 meters in thickness. These factors, resulting in poor outcrop exposure, make even reconnaissance mapping difficult.

Jan 1, 1983

By Tim O’Neil

If you build a big truck, build a big tire to match it. Let that haulage synergy aid the economics, productivity and lessened maintenance for the unit. Now, Cater-pillar and Michelin have done just that. Discussions began in 1996. Caterpillar was making plans for its 797 ultra-class haul truck. The development team realized the need for a tire that could withstand extreme loads. The 797 would weigh 558 t (615 st) and be capable of 64 km/h (40 mph) speeds. So Caterpillar approached Michelin. The two companies realized the benefits of jointly developing a tire for the 797.

Jan 1, 2002

By Donald E. Ralston

The Huntsville study area in northeastern Alabama consists of Jackson, Limestone, Madison, and Marshall Counties. Major emphasis was placed on the Huntsville urban area in Madison County to analyze the relationship of urban growth and the minerals industry. Huntsville was delineated into its component urban, suburban, and rural parts for 1964, and the primary area of growth was predicted for 1990. Population estimates were made for the four-county area as a unit and Madison County separately, and projected to 1990. Demand estimates for crushed stone and sand and gravel were made for the same area units and projected to 1990. Analysis of quarry sites in the Huntsville area was made for the present and for the future. The mineral operations of the study area are all located in rural areas; in the case of Huntsville, the mineral sites are located in areas defined as "rural" in the component urban-suburban-rural system. The operations outside Madison County can expect to have minor problems with urban encroachment, while those operations in Madison County can expect major problems associated with urban growth and development. Some of the problems associated with limes tone production can be reduced if producers invest in capital equipment that will reduce the nuisances inherent in this activity. Although urban expansion endangers some quarry operations in Huntsville, topographic and political restrictions which prevent urban expansion can effectively shield quarry operations for some time.

Jan 1, 1970

Study on Ball Mill Grinding of a Cassiterite-Polymetallic Sulfide Ore

Sep 13, 2010

Coal-bearing regions cover about 18,464 square miles or one third of Iowa, primarily in the south-central part of the state. Coal quality ranges from subbituminous to high volatile bituminous. Iowa's coal reserves are estimated to be 2.2 billion tons, less than one-half of one percent of total U.S. reserves. Coal beds are typically thin seams with a maximum thickness of five feet. Coal deposits in Iowa were fist mined in the 1840s for blacksmithing and domestic purposes. Demand for coal increased with the use of coal to fuel steamboats and railroads. Production peaked in 1917, when Iowaproduced9 million tons of coal. Since then, conversion to natural gas and fuel oil has decreased the demand for coal. Today, electrical power generating plants have created a continuing, but declining, demand for Iowa's coal. Coal production in Iowa is by surface mining methods. The Iowa regulatory program was conditionally approved January 21, 1981. Full approval was received March 28,1982, and the Abandoned Mine Land Program was approved March 28, 1983.

Jan 1, 1992

By I. J. Duckworth

Due to improved, stringent safety regulations, many modern road tunnels are statistically safer, per kilometer, than above ground roadways. However, the public perception and reaction in the event of a serious tunnel fire is very different to that associated with a surface incident. Vehicle fires in road and rail tunnels are recognized to represent an immediate and extreme danger to the patrons of those systems. Unlike workers in the mining and civil construction industries, the general public are neither trained nor equipped to fight fires or evacuate under deteriorating smoke conditions. Accordingly, for the majority of modern transportation tunnels the ventilation infrastructure is sized on the requirement to control the combustion products from worst-case fire scenarios and to provide a tenable evacuation route for the tunnel users. It is common for these same emergency ventilation systems to be employed, often in a reduced capacity, for other operating modes such as the dilution of pollutants during congested traffic conditions. This is one of the fundamental differences to mine ventilation, where primary ventilation systems are not typically sized based on fire scenarios. This paper presents an overview of the subject of fires in vehicular tunnels. This includes a brief history of major transportation tunnel fires followed by a discussion on the resulting legislation and standards that govern the design and operation of tunnel emergency ventilation systems. A summary is provided on the common criteria, theory, and design techniques that are employed during tunnel emergency ventilation systems design. Information is provided on fire detection and suppression, with a discussion on the growing acceptance of wet suppression as a means to mitigate major fires in road tunnels worldwide.

Jan 1, 2009

By N. Andersen

During the preliminary design phases and feasibility study of a proposed vertical shaft, a vertical diamond drill-hole is normally drilled on the site. This paper outlines how rock mass characteristics, in-situ rock stress, rock strength, hydrological characteristics, and structural parameters can be determined using wireline logging of this borehole. In addition, a rock mass classification scheme is developed, based on published work, and in particular the Q-factor is adapted to assess the stability of raise-bored shafts. The ‘stick plot’ is introduced, which combines all geotechnical parameters applicable to the stability of a vertical shaft into a colourcoded format where cross-correlations can readily be made on a day-today basis during the shaft-sinking process.

Jan 1, 2015

By L. C. Graton, Joseph Murdoch

I. Introduction......................... 26 1. The Relations of Scale in Geologic Work........ 26 2. General Characteristics of Copper Sulphide Ores..... 29 3. Scope of Present Study................. 31 11. Description of the Important Minerals............ 36 1. Pyrite....................... 36 2. Pyrrhotite....................... 41 3. Chalcopyrite...................... 41 4. Bornite........................ 40 5. Covellite....................... 50 6. Chalcocite....................... 52 7. Enargite...................... 59 8. Tetrahedrite and Tennantite.............. 61 III. Conclusions.......................... 62 I. Introduction. The Relations of Scale in Geologic Work. Many features of human accomplishment rest upon the possibility of representing natural objects on a scale of different magnitude from the actual one. Most drawings, for example, are of very different scale from that of the object depicted, and indeed are useful mainly 011 this account. More important than the question of mere convenience, however, is that of meeting the physical limitations of vision.' Thus, a mural

Jan 1, 1914

By Ronald T. Mayerle

The Condrey Mountain RARE II area lies mostly within the Elliot Creek mining district, a significant producer of gold from placers, and gold, Silver, copper, and minor soapstone from lode deposits. No mineral production has occurred within the study area; no resources are known in the area. However, significant resources in lode and placer deposits are just outside the west and northwest boundary of the area. The Blue Ledge Mine (fig. 1, no. 15) adjacent to the western boundary, is reported to contain 226,000 ton; (205,000 t) of identified resources averaging 0.05 oz gold per ton (1.7 g/t), 2.16 oz silver per ton (/4.0 g/t), 3.5 percent copper, and 3.95 percent zinc. The mine has produced 11,131 tons (10,114 t) of ore that yielded 1,026 oz (31,908 g) of gold, 58,431 oz (1.8 million g) of silver, and 2.7 million lb (1.2 million kg) of copper. Exploration is currently underway at `he mine and vicinity, including part of the study area.

Jan 1, 1983