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By F. Calizaya

This paper describes the basic requirements for the utilization of belt air to ventilate working sections at remote locations in relation to the main fans. It highlights the risks involved, potential problems, and the provisions that must be followed by mine operators for the safe use of belt air. The paper also presents a brief review of the current regulations, conveyor belting tests, atmospheric monitoring system requirements, and the experience gained by mine operators to utilize the belt entries to ventilate remote working sections or areas where mechanized equipment is being installed or removed. The paper concludes with a set of recommendations with respect to the utilization of belt air and the composition of belt material in under-ground coal mines.

Jan 1, 2008

By Cao Shenggen

Experiences in the developed countries have shown that continuous increase of panel width (or face length) is one of the major technical trends for high production high efficiency mines. Increasing the panel width will increase not only the panel output, simplify the gateroad layout, facilitate high concentration of production, but also increase resources recovery and facilitate protection of surface structures. This paper uses the No.4326 super- wide panel, Wangzhuang Coal Mine as an example. This mine employs the fully-mechanized top-coal caving longwall mining method. Through surface subsidence monitoring, the dynamic characteristics of surface movement were obtained. The dynamic surface movement during mining and the final surface movement after mining were predicted using the Mining Subsidence Prediction System. The results indicate that after mining, the surface above the super-wide panel reached a state of full subsidence, So it can ensure the No.309 National Highway above is located in the flat bottom of the subsidence basin, and there is little impact on the national highways when panels on both sides of 4326 Panel are mined.

Jan 1, 2003

By H. T. Kennedy, J. E. Little

An empirical equation for the prediction of the viscosity of several pure paraffin hydrocarbons and nitrogen is presented. It involves temperature, pressure and six constants of the material, and it applies reliably to both liquids and gases. The equation is similar in form to van der Waal's equation of state. For the paraffin hydrocarbons methane through r-hexane and nitrogen, an average absolute deviation of 1.9 percent was obtained on 1,006 data points described in the literature by 14 authors. When this equation is extended to complex, liquid hydrocarbon mixtures, a correlation was obtained with an average absolute deviation of 9.9 percent. INTRODUCTION Equations describing the flow of gas and liquid through porous media contain the viscosity coefficient of the fluid. If other pertinent variables remain constant, the volume rate of flow is inversely proportional to this coefficient. In dealing with condensate fluids and volatile oils, however, the compositional effects resulting from changing pressure materially affect the viscosity. The effect of compositional changes also may be significant in certain secondary recovery or pressure maintenance processes, notably miscible displacement or gas injection. Early attempts to describe the performance of reservoirs utilized a volumetric material balance method wherein gas and liquid in the reservoir were identified as produced gas and liquid at the surface. This method of analysis proved adequate for reservoirs at moderate temperature and pressure that contained gas with moderately low amounts of condensable materials. The volumetric material balance procedures for "black oil" reservoirs leave much to be desired when applied to condensate and volatile oil reservoirs because phase behavior and compositional changes are relatively more important in these cases. The alternative is a compositional material balance, which in turn, requires a correlation of properties of the reservoir fluid with composition. This paper supplies this correlation in regard to viscosity, for reservoir crude oils. REVIEW OF LITERATURE The literature contains many empirical equations describing the effects of composition, temperature and pressure on the viscosities of pure liquids and binary liquid mixtures. However, the applicability of a majority of these equations is limited to very low pressures and to a small number of systems. Most of them, when applied to complex hydrocarbon systems, are of little value. The lack of utility of the majority of equations results from the fact that they were developed to show the separate effect of temperature, pressure or composition on viscosity, but not to predict the viscosity as a function of all three variables. And with the few exceptions noted below, they were developed to apply to much simpler systems than hydrocarbon mixtures. Eakin1 developed an equation for the viscosity of pure light hydrocarbons applicable in the gas, liquid and dense fluid regions, and in its most general form is written as µ - µo =A(ebP - e-cpk) The pure component viscosity at atmospheric pressure and temperature T, µo, was calculated using the Sutherland equation: µo = BT3/2/T + S The constants in Eakin's equation permitted the term e-CPk to become quite small at high densities (above 0.215 gm/cc), and the general equation would simplify to

Jan 1, 1969

By Theo Lehner

Turning matte into anodes continues to be an area to watch: for visitors to see pyrometallurgy in action; for metallurgists to keep up with modern smelting furnaces and ever increasing production rates; for management to remain profitable using more tools than taught in school; and for environmentalists to detect the last small clouds from the ever cleaner smelter. Current converting practices have been screened and analyzed, and today, converting and casting is a modern industry. An impressive, though typical learning curve of converter productivity may be detected. Local conditions such as availability and type of raw materials, products extracted, cost factors, etc., have stimulated the development of add-ons or even alternatives to the still dominant method of converting by Peirce-Smith technology. Turning blister copper into anodes follows a similar path, namely increased productivity and improved quality. We dare to predict that development will continue.

Jan 1, 2005

By R. Altindag

The rock brittleness is one of the most important rock properties that affect the drill-ability of rocks. It is supposed that the increase in rock brittleness causes the increase in penetration rate. The drill-ability of rocks depends on many factors. These factors can be separated as two parts depending on a machine, bit type, rotational speed, thrust, blow frequency, flushing, and rock properties, brittleness, compressive strength, structure, hardness, etc. In this paper, the relationship between brittleness and drill-ability index, which is used in the prediction analysis of the penetration rate of rotary blast hole drills, were examined using regression analysis. It is also seen that significant correlations exist between brittleness and the drill-ability index.

Jan 1, 2002

The West Coast region of the South Island is situated astride the Pacific û Australian plate boundary zone. The most significant component of this zone is the Alpine Fault. A variety of reconstructions of the pre-Alpine Fault plate tectonic configuration of the New Zealand continental area have been attempted over the past 25 years or so. Most of these have not been closely constrained by a regional compilation of field data related to the age and horizontal displacement history of the Alpine Fault. A model in which the Alpine Fault was initiated no earlier than the interval 18 - 16.5 Ma (B.P.) is proposed, a significantly younger age of inception than has been widely accepted as the onset of dextral displacement along the plate boundary through the South Island. A subsequent history of displacement is presented consistent with the West Coast basin stratigraphy. The alluvial gold content of some parts of the Miocene to Pleistocene conglomerate sequences is also discussed.

Jan 1, 1996

By O. C. Blade

Total sales of diesel fuel in the United States continue to Increase. This growth is due primarily to two causes: More conversion to diesel units by the rail-roads In recent years, and the greater use of diesel engines in trucks, busses, and tractors. Following are some figures on the distribution of the fuel computed from data issued by the Bureau of Mines.2/ [ ] Deliveries of diesel type fuel from refineries totaled 91,522,000 barrels during the first six months of 1955,3/ corresponding figure for 1954 was 91,170,000 barrels. Information on the properties of this engine fuel is very important to the petroleum industry, engine manufacturers, and consumers. To supply such information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under cooperative agreement, are conducting annual surveys of diesel fuel oil produced in refineries in this country.

Jan 1, 1955

By Donald L. King, Frank A. Baczek

Sedimentation-based equipment is used in applications where separation of solids from liquid by gravity settling is desired. If a concentrated solids slurry is desired, the equipment is designed to "thicken"; if a clear liquid is desired the equipment is designed to "clarify." Thickeners normally handle higher solids loading rates than clarifiers, which usually process feed slurries containing low concentrations of suspended solids. Thickeners are therefore designed for heavier-duty requirements, and clarifiers have extra features to ensure more complete suspended solids removal. Major components (Figure 1) that are common to all sedimentation-based equipment are: tank, drive-support structure, drive unit and lifting device, rake structure, feed well, and a means of overflow and underflow withdrawal. Specific features are designed interdependently after the overall separation approach is defined conceptually. This conceptual approach is usually based on past experience or evolves from sedimentation studies conducted on samples of the slurry to be handled. Because many variations and combinations of components are possible, the overall conceptual approach has a number of possible designs that will accomplish the desired results. The final choice is based on practicality, potential for minimizing upsets, and cost.

Jan 1, 1986

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By G. J. Ballmer

Drilling and blasting 12-in. blastholes started about the middle of 1946 and has worked out so well that about one half of the blasting, formerly done with 9-in. holes, is now done with 12-in. holes. In most of this work the harder benches were chosen for the 12-in. size because these were the areas where the greatest difficulty was encountered in thorough fragmentation. At the start of this experimental work a 42-T Bucyrus- Erie churn drill was available whereas all other blasthole drilling was being done with 29-T rigs. The large drill was first equipped with a standard 9-in. string of tools but it could not drill quite as fast as the 29-T drills. How- ever, when the weight of the string was increased about 700 lb, or to a total weight of about 3500 lb, it was found that the 42-T exceeded the drilling speed of the 29-T by about 25 per cent. When a 12-in. bit was substituted for the 9-in. bit the 42-T rig again dropped behind the drill- ing rate of the 29-T rigs. At this stage of the experiment the 42-T was using a 12-in. bit with detachable points and the total weight of the string of tools was about 3800 lb. It took longer to change the drill points than it did the regulation bit and this accounted for some of the slower drilling rate. When a heavier stem and standard construction 12-in. bits were used it was found that the 42-T could drill a 12-in. hole slightly faster than a 29-T could drill a 9-in. hole even in the hardest rock in the pit.

Jan 1, 1949

By Gregg R. Gitschlag

There are more than 4,000 oil and gas structures present in the U. S. Gulf of Mexico. Approximately 100 structure removals occur each year and 66% of these are removed with explosives. From 1993-1995 an intensive study was conducted on the fish kill resulting from the explosive removal of 6 platforms off the Louisiana coast in water depths from 14-28 m (45-92 ft). After explosives were detonated, all floating fish and a sample of the dead fish which sank to the sea floor were collected.

Jan 1, 1997

We can look at the water treatment and management strategies at some recently commissioned mines and minerals processing sites to see the likely future of water in mining. The future of water in mining will be based on a holistic approach to understanding the site water balance, appropriate treatment, reuse where possible, and environmentally managed discharge where required. This paper describes advanced and innovative water treatment and reuse processes as used by mines and mineral processing operations from around the world. Underground mining can often require dewatering to prevent groundwater seeping into and flooding the mine workings. Mining and processing often accumulates wastewaters in a tailings dam. The mine water can contain contaminants such as dissolved salts, iron, arsenic, manganese, heavy metals and acidic and odorous sulfates. On-site reuse, environmental discharge requirements, as well as community needs for water, drive mine operators to consider the most appropriate water treatment process. Mining water treatment for the future is described using case studies of innovative processes. The case studies include treatment of mine dewatering water for beneficial application from Australian mines, Ballarat Goldfields and Bendigo mining, treatment of produced water from oil and gas projects, and treatment for arsenic removal of tailings water from mining and processing at Goldcorp mines in Canada. Advanced and innovative processes including membrane filtration, reverse osmosis at extreme conditions, advanced biological treatment and water management are all part of these case studies. This paper uses real case studies of advanced and innovative mine water treatment processes to explain and examine the technology and the reasons for designing specific processes. The focus is on innovative processes that may be more widely used in future mining û where the water is used for sustainable environmental discharge or treatment to a quality that can be beneficially used by the mine or the local community.

Jan 1, 2008

By I. R. Kramer

The apparent activation energy, U, JOY plastic deformation of aluminium, copper, and gold single crystals and polycrystalline aluminum was found to he dependent upon surface condition. At low strains, the value for U for aluminum single crystals was 4200 cal per mole ; however, this value decreased to 920 cal per mole when the specimens were polished during the test at a rate of 50 X 10-5 win-1 The activated volume also was found to increase with the rate of metal removal. That the surface plays an important role in plastic-deformation processes has been adequately demonstrated.1-4 Of particular interest at this time are the observations4 that the creep rate of single crystals of fee metals is increased markedly when specimens are polished during the deformation process. These observations were interpreted in terms of a dislocation debris layer at the surface regions of the crystal. This layer, which appears to be a region containing a high concentration of dislocations or segments of dislocations, not only will impede the egress of dislocations on the primary slip system, but will also provide a barrier against which dislocations may pile up. By this means, a stress which opposes the motion of dislocations will be generated. It is considered that this stress must be taken into account in any theory which describes the plastic-deformation process. Although a detailed dislocation model cannot be given at this time, it may be stated that the stresses opposing the motion of dislocations arise from the dislocations in the debris layer, Ts, and ti due to the resistance to motion imposed by internal obstacles such as Lomer-Cottrell barriers, subgrain and grain boundaries, forest dislocations, and so forth, as well as the resistance due to the presence of jogs on dislocations and the interaction of the stress fields of dislocations, and so forth. In essence, we have added an additional term, ts, to the usual form of the equation T = Ta- Tb, where Tb is the back stress due to the various types of obstacles which impede the motion of dislocation. Accordingly, the net stress, t, acting on a dislocation may be written as where Ta is the applied shear stress. For deformation which occurs by a thermally activated process5,8 ?=Ae-u/kT = A e(u,-VT)/kT [2] and U = Uo- Vt PI where U = activation energy for plastic flow, y = shear strain rate, Uo = activated energy for plastic deformation in the absence of stress and depends upon the particular deformation process, V = activated volume, k = Boltzmann constant, T = temperature, OK, and A = frequency factor. From Eqs. [I] and [3], U = Uo- V(Ta - Ti - TS) [4] and it is seen that if Ts decreases, the activation energy, U, must decrease if V remains constant. However, as will be shown, V is a function of the surface conditions. In their work on aluminum, Lytton and coworkers7 reported that at low strains the activation energy was 3400 cal per mole and at high strains it was 28,000 cal per mole. The lower value was interpreted in terms of the energy necessary to overcome the Peierls force, while the higher value was associated with the energy necessary for dislocations to move by a cross-slip process. It will be shown that the lower activation energy is associated with the surface debris layer rather than with the Peierls force. EXPERIMENTAL PROCEDURE Single crystals having a nominal cross section of 1/8 in. and a 3-in. gage length were prepared by a modified Bridgman technique using a multiple-cavity graphite mold. The initial purity of the metals was 99.997, 99.999, and 99.999 pet for aluminum, copper, and gold, respectively. The orientation of the specimens is given in Fig. 1. The measurement of the activation energy as a

Jan 1, 1964

By Tatsuya Oki

Tantalum capacitors can be found mounted on printed circuit boards of domestic appliances such as personal computers. These capacitors contain a considerable quantity of expensive metal tantalum and can be detached and liberated from printed circuit boards by impact breakers. In this study, the size and density distribution of the liberated electronic devices were investigated. Then, tantalum capacitors were recovered from other electronic devices using size separation and pneumatic gravity concentration methods. More than 70% of Newton's separation efficiency was obtained for tantalum capacitors. High Newton's separation efficiency could be also obtained for other types of electronic devices such as chip resistors.

Jan 1, 2011

By Andrea M. Ouchi

A major focus of ground control research presently being conducted by the Geomechanics Group in the University of British Columbia Mining Engineering Department is to incorporate weak rock masses (RMR76 less than 50) into existing empirical design relationships. An emphasis is being placed upon the updated span design curve/critical span graph originally developed at UBC. The original database has been augmented by mapping of one mine in Montana and of several mines within the Carlin and Getchell Trends of Nevada. In addition, a neural network analysis has been performed and modifications of the span design curves at the lower RMR76 range have been made. The common factor in all the above mentioned mines is a weak back and/or walls. In most cases, the ore zone is the weakest rock unit and must be dealt with to safely extract the mineral bearing rock. This work attempts to provide rock mechanic tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment.

May 1, 2004

By X. Cao, P. Wanjara, J. L. Fihey, X-T. Pham, F. Mirakhorli

Single-pass hybrid laser-arc welding of 10-mm thick cast plates of CA6NM, a low carbon martensitic stainless steel, was carried out in butt joint configuration using a continuous wave fiber laser at its maximum power of 5.2 kW over welding speeds ranging from 0.75 m/min to 1.2 m/min. The microstructures from the fusion zone to the heat affected zone and base metal were characterized after post-weld tempering at 600°C for 1 hour. From optical and scanning electron microscopy examination, the fusion zone was observed to mainly consist of tempered lath martensite and some residual delta-ferrite. The mechanical properties including microindentation hardness, ultimate tensile strength and Charpy impact energy were evaluated in the post-weld tempered condition and correlated to the microstructures and defects. The ultimate tensile strength and Charpy impact energy values of all the fully penetrated welds in the tempered condition were acceptable according to ASTM, ASME and industrial specifications. The failure mechanisms during tensile deformation and Charpy impact loading were examined by scanning electron microscopy, fractography and optical metallographic analysis near the fracture origin.

Jan 1, 2015

By Anwar-ul Karim

In one of our recent papers, Cheng, Karim, Langdon, and Dom1 analyzed the creep mechanisms in a Fe-4 pct Si alloy. The experimental results of apparent ac-

Jan 1, 1970

By J. T. Cherry

A fundamental goal of the Plowshare Program is to predict crater dimensions when an explosive of known yield is buried at a given depth in a given medium. In this paper a technique is presented that seems to calculate adequately, from first principles, the mound and cavity growth that occur during nuclear and high-explosive cratering events. The technique features a standard, numerical approach to high- intensity stress-wave propagation coupled with a unique model of material behavior in brittle failure. A schematic of stress-wave propagation is presented in Fig. 1. The equation of motion provides a functional relation between the applied stress field and the resulting acceleration of each point in the medium. Accelerations, when allowed to act over a small time increment [A]t, produce new velocities, velocities produce displacements, displacements produce strains, and strains produce a new stress field. Time is incremented by [A]t, and the cycle is repeated. The time increment [A]t is determined by an independent stability condition which requires the increment to be smaller than the time necessary far a compressional wave to travel across the smallest zone. We assume that failure occurs in a brittle material when either the tensile strength or the maximum allowable strain energy of distortion is exceeded. When either of these two conditions is violated, the code uses the cracked equation of state to determine the stress. A preshot testing program is used to determine the consolidated and cracked equations of state. In situ properties to be determined by field logging are density and elastic velocity (compressional and shear ve-

Jan 1, 1967

By Wing G. Agnew

[This report presents the results of tests made by the Mining Division, Bureau of Mines, on the relative durability of manganese-steel drill rods and carbon-steel drill rods for use with the detachable bolts]

Jan 1, 1941

By James D. Cooper

COMBINED tonnage or natural abrasive materials sold or used in the United States in 1962 was 10 percent greater than that of 1961 and value was 9 percent higher. Production of crude artificial abrasives in the United States and Canada was up 14 percent in volume and 9 percent in value. Value of grinding-wheel sales increased 13 percent, and the value of coated-abrasives sales was up 10 percent. The value of imports and reexports declined, while the value or exports increased. [ ]

Jan 1, 1963