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Computer simulation of the control systems for the heavy media coal washing process have been presented in this paper. The simulation model applies the Simulink module of the Matlab 5.1 software package and allows monitoring of variations of a

Jan 1, 1998

By WenCai Li, Yong Ren, Shuai Niu, Xin Hong

"Temperature measurement is very important in metal smelting process. Many devices are used to realize non-contact temperature measurements. Compared to conventional thermocouple, infrared temperature measurement has it's unique advantages. However, using an infrared temperature measurement at the top of the furnace can not obtain the desired optical signal because of disturbance from slag layer, high-temperature gases and other effects. A real time thermometry system with dual-wavelength radiation was presented to get optical signal emitted from molten metal through bottom-blowing nozzle. Taking into account the advantages and disadvantages of bottom-blowing devices, a MHP (Multiple Hole Plug) bottom-blowing device was used, through which the optical signal was transferred to the infrared thermometer by use of optical fiber. After conversion and analysis in real-time, the result was displayed and recorded in computer. After calibration, it could be a good predictor of temperature trend in a metallurgical process. IntroductionAt the refining stage of steelmaking, in order to achieve predetermined chemical composition and temperature, high-temperature molten steel is refined in a furnace such as converter. Because the refining process involved with chemical components and reaction velocities in the furnace rely on the temperature of steel, it is necessary to know the temperature accurately in real time during the process. And temperature measurement is also helpful for the end-point judgment. The temperature in the refining process changes quickly, for instance, in a converter, 300t molten steel is processed in only about half an hour.At present, traditional way of temperature measurement is using a thermocouple probe mounted on a lifter called a sub-lance. The thermocouple is immersed in molten steel and its temperature is measured during the short period until the thermocouple is fused. Accurate and reliable temperature can be obtained by this method, but in consideration of the discontinuous measurement and the costs, missing the end-point temperature may sometimes occur.According to the above background, a method in which a temperature-sensing element such as a thermocouple is immersed directly in molten steel is not suitable for the continuous temperature measurement because materials having such stability are not available. Therefore, radiation thermometry is promising. There have been some reports on radiation thermometry through an observation nozzle through the bottom or side of a refining furnace [1, 2]."

Jan 1, 2014

The kinetics of adsorption of gold di-cyanide onto activated carbon has been investigated extensively over the past two decades. These studies have demonstrated that both film and intra-particle mass transfer affect the kinetics. The dominant mechanism of intra-particle mass transfer has not yet been identified. In the work described, surface diffusion and pore diffusion are considered as possible rate-determining mechanisms of intra-particle mass transfer. Mathematical models are described that incorporate film mass transfer and the respective intra-particle mass transfer mechanism with equilibrium described by a Freundlich isotherm. Rate constants of film mass transfer and pore or surface diffusivities were estimated by the fitting of the respective models to experimental carbon adsorption data. The estimated pore diffusivities, after they had been corrected for the porosity and tortuosity of the carbon, were found in most instances to be higher than the molecular diffusivity of dilute gold di-cyanide in aqueous solution. This situation is not physically viable. The surface diffusion mechanism acting in parallel with the pore-diffusion mechanism is thus responsible for the intra-particle transportation of most of the gold.

Jan 1, 1996

By L. A. Beckett

Load-Haul-Dump machines (LHDs) have contributed significantly to high productivity in hard-rock mining in recent years and are now being introduced into the coal mining industry (Rao, Haycocks and Lucas, 1975; Mining Magazine, 1975). The superiority of the LHD when compared to loader-plus- shuttle-cars has been demonstrated for several operations (Rao et al., 1975), and the number of manufacturers now in the coal mining LHD market (Mining Magazine, 1975) indicates that the concept will be of considerable future importance in the U.S. coal industry. Currently more than 90 percent of U.S. underground coal production is obtained by room-and-pillar methods (Coal Age, 1976). This system presents certain complexities with regard to haulage analysis; among these are constriction of travel routes, variation of haulage distances as different faces are worked, and change in the overall physical layout as mining progresses. Furthermore, current experiments in the use of more than one continuous miner in a section (Mining Magazine, 1975; Coal Age, 1976) suggest the possibility of highly intensive mining operations, with loading proceeding from more than one point simultaneously, in which the overall patterns for machine movements must be carefully arranged to minimize delays.

Jan 1, 1979

By Michael J. Shulman

Outcrops of the Nubian Sandstone Series cover approximately 180,000 km2 in southern Egypt. Within the series, oolitic iron ore beds occur. The only comprehensive information available on stratigraphy of the iron beds is for the area east of Aswan, otherwise information is exiguous, sparse or unreliable. Based on this low level of information, the iron potential of the Nubian Sandstone Series was assessed and an exploration strategy formulated specifically tailored to the assessment. The area covered by the Nubian was divided into five regions, each comprised of 100 cells. A spatial distribution, i.e. negative binomial, was assumed adequate to describe the number of targets per cell and was indirectly calculated using a compound poisson distribution. Estimate of the only unknown parameter - the average number of targets per cell - implicitly/explicitly incorporated available geologic and economic information into the assessment. A probability distribution for the number of targets per region was then derived from the cell probability distribution. An allocation model based on the regional probability distribution assessment as well as on an estimate of the exploration effectiveness and on the exploration budget determines the optimal time to be spent in each region.

Jan 1, 1986

By George B. Clark, Edward E. Hornsey

Pulses from large underground explosions which traverse the rock beyond the "fracture" and "plastic" zones do not behave as a spherical elastic model. Observed attenuation is greater than that predicted by the elastic wave equation, and the pulse form changes in a different manner, i.e., it usually lengthens with the first power of the distance. To more clearly define a mathematical real earth-wave model, detailed analyses of the spherical elastic and the Voigt viscoelastic models have been made, and results compared with observed wave forms from large confined chemical and nuclear explosions. TRANSIENT SPHERICAL ELASTIC WAVES Scope of Investigation Transient elastic spherical waves were investigated in detail. However, an elastic model is not, in general, an exact representation of wave propagation in rock. An understanding of transient elastic waves is desirable for gaining insight into explosive-generated wave phenomena because it can be employed for comparison of more complex and realistic models, such as the Voigt model, or others which may simulate real earth waves. The study was concentrated primarily on the peak values of the radial wave parameters : displacement, particle velocity, acceleration, stress, and strain.

Jan 1, 1972

By Charles L. Kimbell

The final tables of this chapter, tables 25-50, extend and expand the statistical series on production that was started in the 1963 edition of the Area Reports: International Volume of the Minerals Yearbook and that was subsequently updated and expanded in the 1965 and 1967-90 editions. Continuing the practice started in 1989, a column has been included in each of these tables providing a 5-year average for 1987-91, inclusive. This should provide a clearer picture more rapidly of the role of each major producer over the 5-year period. The listing order of major producers, however, continued to be, as in past years, in descending order of rank in the year of review, 1991. This group of tables now includes each of the crude minerals that ranked from? 1st to 19th in 1983 terms of value of their output (as well as four others of lesser rank). These 23 crude mineral commodities accounted for 93 % of the estimated value of world crude mineral production in 1983. In addition, world output of five key downstream products-aluminum, steel, cement, nitrogen in ammonia, and refined oil-is included because of their significance as products.

Jan 1, 1993

By Keith Heasley

An eastern longwall mine was required to mine through a set of three entries located midway down the length of a panel. Of course, the mine desired to design a successful support system for the mine-through area at the least cost. To further complicate the design process, the mine-through entries were located directly under the end of a previously mined, overlying longwall panel and the entries were close enough to be subject to stress interactions from the overlying seam. In order to accurately evaluate the multiple-seam stresses and modify the mine-through support system appropriately, the boundary element program LaModel was used to model the stress and displacements in the two mines. Using the results of the model's stress analysis, the support density was systematically varied throughout the mine- through entries for optimum sup@ efficiency and economics. During the actual mining of the cross panel entries, the longwall experienced few, if any, additional delays, and overall, the support and mine through of the cross-panel en- tries at Harris #1 was very successful, saving the mine confineable time and money.

Jan 1, 2003

By C. K. Rose

A hydraulic scaling rig was placed in operation at the Bureau of Mines oil-shale mine near Rifle, Colo., in 1953. The rig consists of a self-leveling platform mounted on a hydraulic-powered boom. The boom is mounted on the bed of a diesel truck. The equipment provides a movable work platform from which two men can work in safety and comfort while barring loose rock from the backs and walls of the rooms, pillars, and haulageways. INTRODUCTION As a part of its synthetic liquid fuels program the Bureau of Mines has developed a mine in the richer oil-shale beds of the Green River formation near Rifle, Colo. An important part of the work of the Oil-Shale Mining Branch is investigation of techniques for low-cost mining of oil shale on a commercial basis. It is evident that scaling loose rock from the high backs and walls of the mine represents a portion of the direct mining cost. This paper describes the development of a scaling rig for operation in the upper heading of the mine, which is 39 feet high.

Jan 1, 1954

By R. Altindag

Engineers and researchers need to estimate the mechanical properties of rocks from P-wave velocity. In previous studies, the researchers have investigated either the limited values or all the data belonging to sedimentary, igneous, and metamorphic rocks together in the same statistical analysis. In this study, the raw data pertaining to only sedimentary rocks was taken from previous studies and evaluated. For this purpose, a total of 97 samples of sedimentary rock types were subjected to statistical analysis. First, the relationships between P-wave velocity and physical-mechanical properties were investigated by simple regression analysis. All the data were then subjected to multi-regression analysis. Some empirical equations with high correlation coefficients were derived for rock engineers. The equations obtained from the analyses are compared with previous equations found in literature.

Jan 1, 2012

By Mostafa Mossaad, Ali Helwa, Manal Salem

Support of excavation (SOE) design practice tends to model SOE elements using two-dimensional (2D) analyses to avoid the complexity associated with three-dimensional (3D) analyses. Such practice overlooks soil arching in the horizontal plane and prevents designers from accounting for elements such as capping beams as part of the statical system. This study simulates square excavations supported by cantilever slurry walls in dry cohesionless soil using 2D and 3D finite element (FE) models. First, side support wall behavior is compared from 2D and 3D FE models for variable excavation length to depth (L/H) ratios. Second, the effect of slurry wall lateral bending stiffness on wall behavior is studied by modeling the wall using plate element with isotropic and anisotropic wall stiffness. Finally, the sensitivity of cantilever wall behavior to the presence of capping beam is illustrated. The study concludes that unbraced excavations with L/H ratios greater than 5 almost resemble plane-strain conditions. Slurry walls are better simulated in 3D FE models by dividing the plate element into discrete panels or by assigning anisotropic bending stiffness to the plate element. Finally, the presence of capping beam affects the behavior of cantilever walls resulting in reduction of deflections and redistribution of bending moments. INTRODCUTION Support of excavation (SOE) design practice ranges in complexity from conducting simple hand calculations to performing three dimensional numerical modeling depending on several factors among which is the geometry of the design problem. This paper addresses walls that are designed using numerical modeling, and discusses the factors governing the choice of the most suitable modeling approach. It has been believed for a while that modeling excavations using 2D numerical models would lead to a more conservative solution, which turned out to be incorrect in specific cases. This paper attempts to describe cases where 2D finite element modeling could be on the conservative side and other cases where it could be less conservative than the more complex 3D modeling.

Jan 1, 2018

By J L. Kanau

In this study some drawbacks of using Bond grindability as a measure of grindability characteristics for mill control have been discussed. After reviewing the merits of alternative methods of determining the Bond grindability published in the literature, a new alternative method has been proposed.

Jan 1, 2000

By Paul Mitchell, Amy Wheaton, James Rybock

Acid rock drainage (ARD) represents one of the most intractable problems faced by the non-ferrous metal and coal mining sectors, and the creation in the recent past of a number of high-level national and international initiatives reflects the growing concerns of industry, government and other stakeholder groups. ARD is certainly considered one of the most serious environmental impacts caused by mining and the industry's greatest environment-related technical challenge. Additionally, the global depletion of non-acid generating oxide ore deposits and the increasing dominance of sulphide ores means that the potential for ARD incidents will continue to increase. Once initiated, the cycle of chemically and biologically mediated and catalysed reactions leading to ARD generation is difficult to stop. While there is evidence to suggest that the degree of contamination of ARD will decrease rapidly within a relatively short timeframe (Wood et al., 1999), experience in historic mining regions of the world indicates that the problem may persist for centuries at certain sites. Current best practice in dealing with ARD puts the emphasis on prediction and prevention, planned from the outset of the operation and integrated with each phase of the mine site life cycle. The elements that constitute best practice are becoming more clearly defined and as this process of clarification continues industry will undoubtedly accelerate the process of best practice implementation, burying at last the image of mining as a despoiler and polluter of landscapes, an image based on past, rather than current, practices. However, it is equally clear that despite the best efforts of industry and regulators, many sites will continue to generate ARD during operation and following closure - in many cases, a legacy of ARD has been derived from operational and strategic decisions made decades ago, before the risks and impacts of the self-sustaining cycle of ARD generation were properly understood. Add to this ARD generation from poorly managed operations and from historic and abandoned sites, and it becomes clear that the treatment of ARD will be required for the foreseeable future to protect water quality, and ecosystem and human health.

Jan 1, 1999

By R. L. Perrine

A stability theory is developed for miscible liquid-liquid displacement within a porous medium. In the usual case considered, a high-density high-viscosity "oil" is displaced downdip by a low-density low-viscosity "solvent'! Perturbation methods are used to find the conditions under which the spreading mechanism changes from the stable dispersion process to unstable viscous fingering. We find that instability is conditional, that there is a dependence on the shape of a disturbance leading to a"diameter" effect and that very difficult experimental scaling problems may result. A useful consequence is the definition of a minimum "slug size" for stable miscible displacement. This should make possible optimum use of the solvent process for oil recovery. The results may apply to many situations in which one fluid displaces another of somewhat different fluid properties within a porous medium. INTRODUCTION The process of miscible liquid-liquid displacement looked very favorable when it first received serious consideration as a means to increase petroleum recovery. Some early laboratory results were interpreted to mean that only a small "slug" of solvent was needed, perhaps 2 to 3 per cent of a hydrocarbon pore volume. This "slug" could recover the oil in an entire reservoir provided the fluids remained miscible.1,2 Only a slow growth of the "mixing zone", or gradual transition from oil to solvent, should occur. This would follow naturally from mixing by a dispersion mechanism such as that described by Scheidegger.3 And, indeed, laboratory cores have shown this kind of behavior provided solvent viscosity was at least as great as that of the oi1.2,4-6 The same kind of behavior has also been observed with solvent viscosity lower than that of the oil after the distance traversed became large. Not all laboratory results have been this favorable, however.7-9 Mixing zone growth may become proportional to the distance traveled rather than the square root of this quantity. Such behavior accompanies high rates in short systems of large diameter, provided the viscosity ratio is adverse. If this more rapid spreading were to persist in a reservoir, the solvent requirement for miscible "slug" displacement could exceed 30 per cent of a pore volume. There is considerable economic importance in the difference between 3 and 30 per cent solvent. A 1ogical conclusion is that two different kinds of flow behavior are possible, with each kind leading to a different result. One kind gives efficient displacement, the other does not. In the efficient case, the solvent bank spreads out only by the mechanism we have termed dispersion. Under these conditions, displacement is as near piston-like as possible. In the second kind of flow, found only with adverse viscosity ratios, viscous fingering occurs. That is, permeability variations cause a small finger of low-viscosity solvent-rich fluid to move ahead of its average position within the mixing zone. This creates a path of low resistance to flow, and an even greater amount of solvent-rich fluid follows. Thus, the process is autocatalytic. Once started, the fingering mechanism rapidly becomes dominant. The question to be answered is this. Under what conditions will each of these two different kinds of flow occur? In particular, what conditions denote the transition from dispersion to viscous fingering as the solvent spreading mechanism? The answer may tell us whether or not the desirable, near piston-like miscible displacement process is practical. An answer to this problem can be obtained from theory by the use of perturbation methods. The procedure is as follows. We first formulate a mathematical representation of the system. Then a small disturbance (or perturbation) in solvent concentration profile is introduced and observed to see what happens. Unstable flow is indicated when a small disturbance will grow larger. This will lead to eventual viscous fingering. If on the other hand the disturbance dies out, the displacement is stable. In this latter case, with dispersion as the spreading mechanism, near piston-like displacement is possible. Thus, this paper presents the development of a stability theory for miscible liquid-liquid displace-

By R. E. Reed-Hill

A simple accurate graphical method for orienting fcc crystals using (111) slip traces on a single surface is described. Solutions placing the pole of the surface in a unit stereographic triangle are obtained using a Wulffnet, a (111) standard projection showing the four (111) planes, and a (111) standard projection ruled into unit stereogmphic triangles. The multiplicity of solutions is described in relation to this method. AN accurate, rapid single-surface technique for orienting fcc crystals, using (111) slip or twin traces, has been a matter of continuing interest, as evidenced by the periodic appearance of papers on this subject.'-4 This note presents a new method possessing some advantages over those previously reported. It is an analog to the technique for hcp metals5 where the solution is based upon a stereographic rotation of the specimen surface on a (0002) standard projection that contains the planes of the possible features that might account for the observed traces. In the hexagonal solution, the axis of rotation is the basal-plane trace in the surface. In the fcc case, the axis of rotation is one of the observed ( 111) slip or twin traces. It has been observed that the solution is greatly facilitated if the indicated movements of the (111) traces during the rotation of the surface are plotted directly on a paper copy of a Wulff net as shown schematically in Fig. 1. The trace selected to represent the axis of rotation is assumed to fall at the north-south poles of the Wulff net. The directions of the other traces are then plotted as points at the proper angles around one-half of the basic circle of the net. The loci of points corresponding to the movements of these traces (directions) during a 90-deg rotation of the surface, about the polar axis of the net, are then easily and accurately drawn by following the appropriate small circles on the Wulff net. The solutions to the problem are obtained with the aid of a (111) standard projection of the (111) planes, see Fig. 2. This is normally a Xerox copy of a carefully drawn master made on high-quality tracing paper. The (111) standard projection is superimposed over the Wulff net and rotated about its center until the points of intersection of the loci of surface traces, drawn on the Wulff net, and the great circles representing the (111) traces, all lie along a common meridian of the Wulff net as demonstrated in Fig. 3. This latter great circle represents a possible position of the surface. The pole of this plane is then plotted on the (111) standard projection. Its location in a unit stereographic triangle may be readily obtained by superimposing (over the standard projection) another tracing paper (111) standard projection subdivided into unit stereographic triangles. The result of this last operation is shown in Fig. 4. MULTIPLICITY OF THE SOLUTIONS The maximum possible number of (111) traces on a single grain surface is four. Any one may be selected as the axis about which the surface is rotated. Corresponding to each such choice are three possible surface-pole orientations, related to each other by a simple 120-deg rotation about the pole of the (111) basic circle. This is a direct result of the threefold symmetry of the (111) standard projection. Since each of the four rotations will normally give a different set of three-pole positions, there are, accordingly, twelve possible solutions. Each of these twelve solutions places the surface pole in the same relative position in a stereographic triangle so that all are crystallo-graphically equivalent. Accordingly, only a single solution is required to obtain a basic orientation of the crystal. It should be noted, however, that the orientations obtained by reflecting* any of these twelve orien- *The reflected orientations may be obtained by a 90-deg rotation of the opposite sense to that shown in Fig. 1. This rotation places the correspond-ing trace loci in the lower hemisphere of the Wulff net rather than in the upper hemisphere. tations through the surface are also possible orientations that could account for the surface traces. Thus, a given set of four traces always corresponds to a pair of basic orientations related by reflection through the specimen surface. This ambiguity can only be re-

Jan 1, 1967

By James P. Connell

The Berkeley Pit of The Anaconda Company is located on the southeast slope of the Butte Hill, the legendary "Richest Hill on Earth," and is one of the largest pit operations in the world completely dependent on truck haulage. Through October 31, 1968, the Berkeley stripping and mining operations have moved more than 442,589,000 tons of material. Present scheduled production is at the rate of 260,000 tons per day, with a record quantity of 306,900 tons having been hauled on September 23, 1968. Although the Berkeley Pit has been in production only a little more than ten years, it has been the proving ground for many of the presently used large trucks. Beginning with the original R. G. LeTourneau 75-ton electric truck in 1960, Unit Rig 85- and 100-ton electric drives, Haulpak 65- and 105-ton electric drives, and Caterpillar 100-ton electric drives have all been tested under production conditions. In addition, engine development has kept pace with both 1000-hp diesel and 1100-hp gas turbine engines now under test. As the size of the Berkeley operation has grown, the truck fleet has changed in size and appearance in order to maintain economic mining costs. The original fleet consisted of forty-three 36-ton trucks with conventional mechanical drives. The present fleet is made up of eighty-nine trucks: nineteen 85-ton Unit Rig electrics with 700-hp diesel engines; sixty-nine 100-ton Unit Rig electrics with either 700- or 1000-hp diesel engines; and one 100-ton Unit Rig electric with an 1100-hp gas turbine engine.

Jan 1, 1969

By K L. Temel, W P. Player

The underlying message of this paper is that investment in prospecting, exploration and mining in New Zealand is welcomed. The Government's policy with respect to Crown owned minerals is for continuing investment in prospecting, exploration and mining which is in accordance with good exploration or mining practice. To encourage continued investment requires a business-friendly environment. Government policies and initiatives to enhance the business environment for the minerals and coal exploration and mining industries are discussed in this paper. As well, new initiatives under consideration, which have the purpose of enhancing the investment environment, are discussed.

Jan 1, 1997

By Christopher C. Woomer

Cyprus Shoshone Mine uses the longwall method to extract a deep, thick, pitching coal seam in the Hanna Basin of South Central Wyoming. The immediate, and main roof rock consists of weak, thinly-bedded, silty mudstones with weak, interbedded fine-to medium-grained sandstone. Tailgate ground control has been a critical factor impacting productivity at the mine. A gateroad condition mapping program for the 11 left longwall gateroads indicated potentially severe ground control problems for the tailgate. It was predicted that the existing, secondary support pattern of wood cribs would not provide adequate support capacity. As predicted, severe deterioration of the tailgate occurred in the form of a roof cutter, sloughing ribs, and failing wood cribs. Productivity was affected and additional support was required. Shoshone personnel evaluated several options for providing the additional support needed in the tailgate. The additional support system and placement method had to satisfy several requirements with respect to access, materials handling, placement method, set-up time and support capacity. Approximately 6,000-ft. of deteriorating tailgate had to be supported. The initial wood crib support system left a 6-ft. walkway for access and construction of the additional support. This access was further reduced as the roof loaded the wood cribs. This eliminated the possibility of mechanized material handling to the construction locations. All materials would have to be transported by hand. The additional support system had to be placed quickly to stay ahead of, and keep pace with, the required longwall advance rate. It had to incorporate the existing wood cribs and provide at least 500 tons of extra support capacity. And most critically, the system could not affect longwall ventilation. Longwall coordinators and engineers made the decision to use a low density, pumpable cement known to the industry as TeksealTM, to provide the system required. A 200 psi ultimate strength mix was decided on to provide the required load capacity. The existing cribs were formed with 1-in. by 6-in. boards and brattice cloth to provide the containment. To overcome the access limitations, three boreholes were drilled from the surface to the tailgate on 2,000-ft centers. A mobile pumping station was established on the surface and the TeksealTM was pumped 900-ft. down the boreholes through a 1.5-in. steel pipe, then as much as 1,800- ft. along the tailgate entry through 1.25-in. miner spray hose. The materials required for the TeksealTM supports could all be carried into the construction locations by hand. As a direct result of incorporating relatively new methods of pumping high yield, low density, cementitious grouts, the Shoshone Mine reduced downtime due to tailgate ground control problems by approximately 70% in comparison with previous Longwall panels. The longwall set three monthly production records while mining the 11 left longwall under the deepest cover, steepest pitch, and most extreme ground control conditions ever encountered at the mine.

Jan 1, 1995

By Koichi Nishimura

Japan's coal reserves are estimated at 8,583 million tons (according to the materials on X World Energy Conference,. 1976). Japan is a long island country in the shape of an elongated cashew nut whose top is pointing to the north and its lower tip is pointing to the west. And her major coal fields are located in the two extreme far parts of Hokkaido in the north and Kyushu in the south. On the other hand, Japan's major industrial center are located in the central part of the country far from either coal-producing areas. This fact places coal a great geographical disadvantage in comparison with petroleum whose refining bases are concentrated on the coastal regions virtually next to major industrial centers.

Jan 1, 1982

Winzes are usually sunk 9 ft. 6 in. long by 6 ft. 0 in. wide and are divided into two compartments, 4 ft. 0 in. by 5 ft. 0 in. inside the timbers. The general practice is to sink the winze to a depth of from 9 to 12 ft., put in bearers and three or four rings of timber, and then erect a sinking headframe before continuing sinking operations.GENERALThe main feature governing the design of the headframe was that all parts could be transported on timber trolleys in No. 2 Shaft. Except for some minor details the structural members consist of steam pipe. Joints are sections of steam pipe welded to one member and into which the other member fits and is held in place by a 1-in. bolt. The headframe consists essentially of two bedpieces to carry the winch and to form a seat for the four legs. The legs support the sheave bearers, the tipping door and the brace.Except during tipping operations the door is in a nearly vertical position. For tipping it is lowered to an inclined position and a hook suspended from one of the bracing members of the headframe is attached to a "D" welded to the bottom of the kibble. This causes the kibble to tip when it is lowered on to the tipping door. The capacity of the kibble is 4 cubic feet.THE HEADFRAMEThe dimensions of the headframe are:Height to top of sheave .. .. 14 ft. 10 in.Distance centre to centre of legs 4 ft. 4 in.Length of bedpieces .. .. .. .. 8 ft. 9 in.The weight is approximately 2,000 lb., the tipping door and bedpieces being the heaviest members. They weigh 240 lb. and 170 lb. respectively.One compartment of the winze is decked over, and the bedpieces, which are 8 ft. 9 in. lengths of 6 in. pipe with three short lengths of plate welded to the underside, are placed over the sinking compartment, either transversely or parallel to the winze. Three 3 inch pipes act as spreaders between them.Welded to the top of each bedpiece is a 6-in. by iHn. plate 3 ft. 0 in. long with four 4-in. by 1.5-in. slots cut longitudinally at 10 in. centres. Two 10 in. by 4-in. timbers are bolted to these plates, the distance between them being adjusted to suit the holes in the winch bedplate, which is bolted to the 10-in. by 4-in. timbers.Two short lengths of 3 in. pipe are welded to each bedpiece at 4 ft. 4 in. centres. These form the seats for the legs of the headframe, which are...

Jan 1, 1941