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By S. K. Kawatra, T. C. Eisele

The separating efficiency of a flotation column is largely limited by the degree of back mixing of tailings into the froth zone, and the recovery is limited by the degree of short-circuiting of feed to the tailings. Current columns are typically constructed very tall (30 to 40 ft) to limit the effects of back mixing and short-circuiting. These effects can also be reduced in a much shorter column, provided that the flow in the column approaches plug flow. In this work, horizontal baffles were shown to improve the performance of a 6 -ft laboratory-scale flotation column treating a poorly floatable coal. Tests with variations in the baffle positions showed that baffles are needed both above and below the feed inlet to achieve the greatest benefit. Tracer tests with a fluorescent dye in water showed that baffles reduce the amount of feed water entrained in the froth at any given coal recovery.

Jan 1, 1996

A model has been developed for drum scrubbing which allows selection of geometry and power input. Specific aspects considered are: Calculation of total static and operating volumes. Total residence time based on total operating volume. Solids residence time based on solids operating volume. Selection of the aspect ratio. Alteration of operating fill to allow for smaller or larger feed openings. Selection of proportion of critical speed. Calculation of shell and motor power requirements. The model uses either solids or total residence time to calculate the required operating volume. The solids residence time is based on the proportion of coarse solids in the feed. Material finer than the reject size is considered as part of the slurry. The solids operating volume is the static volume plus the surcharge on the discharge weir required for flow of the solids from the unit. The total operating volume is the static volume plus the surcharge on the discharge weir for the total flow to exit the scrubber. The burden density is calculated from the coarse solids bulk density and the slurry density that includes all the fine solids. Power is calculated using the Liddell and Moys correlations for burden position and shape, and the operating rotational speed. Results from the model (especially power) have been verified from industrial installations of significant size. Predicted and observed power draws are within two per cent. A check against the JKMRC mill model shows power draw prediction agreement to within four per cent.

Jan 1, 2004

By C. S. Matthews, M. J. Fischer

Distortions caused by dip on five-spot sweep pattern were determined by visual experiments on a model composed of parallel plates of glass with holes drilled at the well positions. This model war designed to simulate a reservoir depleted of its primary oil and containing a gas phase. Prior to interference, it was found that the injected fluid took a nearly circular shape about the injection well for the cases studied. However, these circles moved down-dip considerably under the influence of gravity. It was concluded that pattern flooding should be practical for many dipping reservoirs. A quantitative measure is given of how much the well position should be altered to allow for dip. Experimental deternzinarions of injectivity showed this to be about the same in a dipping reservoir as in a horizontal one. INTRODUCTION This investigation was undertaken at the suggestion of the Pacific Coast area, Shell Oil Co., where a pilot water flood in a dipping reservoir was being carried out at the time this paper was in preparation. Prior to the undertaking of this flood there had been considerable speculation as to how gravity would distort a flood pattern in a dipping reservoir. The thought was expressed in some quarters that a five-spot flood would not be applicable to a dipping reservoir because the flood pattern would elongate in the direction of dip and would never form a "seal" around each five-spot. If the flood pattern elongated sufficiently, both the oil and the water might flow largely downdip rather than into the pattern producers. In view of the importance of the California water floods, it was deemed important to determine the effects of gravity on a five-spot pattern in a dipping reservoir. Previous work had also been carried out in this laboratory,1 but only for the single-fluid case. The present investigation extends these results to multifluid cases. Several sets of pictures of flood fronts are presented so that the process can be visualized. From these pictures, curves are obtained which show the correct drilling position for achieving equal times of oil-bank breakthrough. Several injectivity curves are also presented which may aid in prediction of injection rate. ASSUMPTIONS The present results were obtained with a model composed of two parallel plates of glass spaced about 1 mm apart. When the inertial forces are small, as in these experiments, the flow between the plates follows Darcy's law and is analogous to flow through porous media. In using these plates, it is not possible to scale effects of capillarity correctly as regards a transition zone between injected and displaced fluid. Calculations show, however, that effects of such capillarity should not be important in determining the gross flooding pattern in the field. In fact, in this model the capillary forces tend to circularize the pattern to a greater degree than in the field. To preserve a large ratio between the viscous forces and the circularizing capillary forces in the laboratory model, viswus glycerine was used as the flooding liquid and the rate of flooding was very high. The circularizing force is believed negligible in these experiments. In addition to the effect of the surface tension y, which tends to circularize the pattern, another capillary force must be considered. This is the adhesion tension y cos, which acts at right angles to the circularizing term y. If the plates in the model are "wetted" the same all around the periphery, then the adhesion tension,

Jan 1, 1957

By L. D. Tracy

"Introduction In the course of the investigations by the Bureau of Mines into the various causes of coal-mine explosions, the fact that several gas explosions had occurred during or very soon after a mine was being un-watered, attracted the attention of the Bureau's engineers. The apparent coincidence was so marked that there appears to be an extra hazard present, whenever water, which has been standing against the face of the coal for some time, is suddenly removed either by natural drainage or by mechanical means.Actual Occurrences Case 1. - A typical illustration of this hazard is shown in a gas explosion which occurred in a mine in Central Pennsylvania. Four main entries, 50 feet apart with an average grade of 6 per cent, had been driven with the dip of the coal, and from these mains 7 pairs of entries, at intervals of 800 feet, had been turned at such an angle that their grade was slightly rising. Prom these latter pairs of entries, rooms were turned practically at right angles.The main entries had been driven for 4,500 feet and at the face there was 400 feet of cover. As far as could be observed, the roof was of sandstone and the floor of clay.The coal bed being mined was the Lower Kittanning, which has a thickness of about 4 feet. A typical analysis of the coal in that section is as follows:"

Oct 1, 1924

By L. J. Buteau, R. E. Reed-Hill, W. A. Slippy

In a zirconium {1121} twins tend to have coherelzt boundaries and thus do not usually taper to a point when they intersect a grain boundary. Under the proper conditions, a (1121) twin may deform a boundary in such a manner as to clearly rcveal the twinning shear. Measurements of these grain-bounrlary rotatzons yield a value of 0.63 for the (1151) twinning shear. The magnitude of the observed shear and its shear sense are in excellent agreement with the assumption that the second undis-torted plme (K2) for this form of twinning is the basal plane (0002). The present value of the tzvinninz shear, which is approximately three limes larger than Rapperport&apos;s value? is in excellent agreement with reported results of Sokuskii and Prolsenko.5 RECENTLY westlake&apos; reported a study of the twinning modes of zirconium based on ~ap~er~ort&apos;s2 values for the twinning elements. He observed that two of the modes, (1012) and {1122), can be explained by relatively simple dislocation models. A workable model for (1121) twinning, however, proved to be very complex and questionable. Because Rapperport&apos;s second undistorted plane, (K2), for (1121) twinning has large indices, {ll2l6), it is possible that the difficulty in defining a model for (1121) twinning lies in an incorrect value for K2. A measurement of this twinning element has therefore been made, using a method based on observations of the shear displacement of grain boundaries at positions where they are intersected by (1121) twins. EXPERIMENTAL PROCEDURES The zirconium specimens were deformed in tension on an Instron machine either at the temperature of liquid nitrogen (77ºK), or prestrained at liquid nitrogen temperature and then further deformed at room temperature. Straining at 77°K was employed in order to nucleate (1 121) twins in large numbers, since simple ropm-temperature tensile deformation favors (1012) twinning. Specimens were machined from 1/2-in.-thick plate. The material was arc-melted sponge zirconium annealed to an ASTM grain size 4 and containing, in parts per million, 380 Fe, 880 0, <40 Hf, 32 N, and < 5 H. The specimen gage length and diameter were 1.25 and 0.130 in., respectively. To insure a gage section initially free of twins, the last 60 thousandths of the specimen diameter was removed by acid machining.

Jan 1, 1963

By Robert J. Mac Kinnon

A moving grid finite element model for the analysis of transients in a rock mass surrounding an underground coal conversion cavity is presented. Major model components are outlined, including a special element formulated to account for internal discontinuities. A numerical example is described.

Jan 1, 1986

Esso-BHP have installed a Production Supervisory Control System that is presently controlling the offshore oil and gas facilities on the Barracouta and Marlin platforms from an onshore master station. This control is achieved with a computerized master station onshore which uses a UHF radio system for telemetry and control. The system is designed to control, monitor, and gather data from a large number of oil and gas production platforms and has flexability to handle future variations in operating conditions. Thn -etom ..ill kn nvt,,ndnd to thn I-lalihn+ rJ,+f, rr , Into +hie -- -A +n the lei...,fieh .,lo+fnrmc A.,;- 1071

Jan 1, 1970

By J. A. Herrick

SOME time ago the writer needed a cheap, light, and portable hydraulic lift or crane, that would be universal in its application, and that might -be suspended from crane-arms, overhead tramways, beams, etc., and serve all the uses of ordinary hydraulic cranes. This was accomplished by the use of a closed cylinder of wrought-iron hydraulic pipe, provided at its top with the ordinary gland and stuffing-box, through the centre of which passed another similar pipe of slightly smaller diameter, forming in effect the ordinary plunger of the regular hydraulic crane. Over the top of this centre pipe or plunger or piston a disk of iron is placed with two arms projecting several inches from the rim, as may be required. Through these arms long iron rods pass, one on each. side, and are fastened in place by nuts screwed to a bearing immediately above and below the disk. These rods also pass through the enlarged head of the lift down through a casting which closes the bottom of the cylinder, which, at the same time, gives them a bearing, and they terminate at a point below the casting equal to the height of the lift of the crane. The rods at this point pass through a disk similar to the top disk and are similarly secured in place. A common hook arranged with a swivel passes through the centre of the disk, and on this hook the load is suspended. For a stationary hanging crane the apparatus is suspended by two rods passing through the head of the lift in similar manner to the two already described, at right angles to the first, and of sufficient length to let the first set play between them and rise to the full height which the plunger will allow. The second set of rods terminates in an iron disk similar to the one at the bottom of the first set, and a hook through this in turn suspends the entire apparatus. In order to adapt the lift to an overhead tramway, single or double, in place of the suspending rods, a projection or offset is arranged on each side of the head of the lift and a journal cast in, allowing the lift to be suspended on pivots arranged as follows

Jan 1, 1879

By J. A. Herrick

Some time ago the writer needed a cheap, light, and portable hydraulic lift or crane, that would be universal in its application, and that might .be suspended from crane-arms, overhead tramways, beams, etc., and serve all the uses of ordinary hydraulic cranes. This was accomplished by the use of a closed cylinder of wroughtiron hydraulic pipe, provided at its top with the ordinary gland and stuffing-box, through the centre of which passed another similar pipe of slightly smaller diameter, forming in effect the ordinary plunger of the regular hydraulic crane. Over the top of this centre pipe or plunger or piston a disk of iron is placed with two arms projecting several inches from the rim, as may be required. Through these arms long iron rods pass, one on each side, and are fastened in place by nuts screwed to a bearing immediately above and below the disk. These rods also pass through the enlarged head of the lift down through a casting which closes the bottom of the cylinder, which, at the same time, gives them a bearing, and they terminate at a point below the casting equal to the height of the lift of the crane. The rods at this point pass through a disk similar to the top disk and are similarly secured in place. A common hook arranged with a swivel passes through the centre of the disk, and on this hook the load is suspended. For a stationary hanging crane the apparatus is suspended by two rods passing through the head of the lift in similar manner to the two already described, at right&apos; angles to the first, and of sufficient length to let the first set play between them and rise to the full height which the plunger will allow. The second set of rods terminates in an iron disk similar to the one at the bottom of the first set, and a hook through this in turn suspends the entire apparatus. In order to adapt the lift to an overhead tramway, single or double, in place of the suspending rods, a projection or offset is arranged on each side of the head of the lift and a journal cast in, allowing the lift to be suspended on pivots arranged as follows:

Jan 1, 1879

By Robert Lamarre

In today?s environment, the availability of production equipment is a must to increase throughput and profits. For a number of mining organizations around the world, spare parts availability is key to achieving this goal. Fortunately, having less production equipment immobilized by a lack of spare parts does not equate to increases in inventory levels or in carrying costs. Advance operations research has shown a number of avenues to increase equipment availability while reducing total investment in stock. The presentation will explore these avenues by focusing on key inventory management changes that can be implemented by organizations to optimize their service and stocking levels. We have successfully applied our approaches in start-up mining projects, in mature projects and in end of life mining operations. We will illustrate our methodology using examples from our work with > 30 mining sites around the world.

Aug 1, 2013

By O. P. Arora, M. Metzger

Single-phase aluminum containing 1 to 600ppm copper was studied in 7 to 26 pct HCl. The corrosion rate in the autocatalytic stage was resolved into a constant intrinsic component and an acdelerating autocatalytic component, and attention was focused on the part of this stage where the corrosion rate could be described by a simple empirical relation. Autocatalytic corrosion in this period was localized and its rate increased rapidly with copper content and with the strength and chlaride content of the acid. The effects of adding cupric ion to 16 pct HCI were functionally and quantitatively inconsistent with the autocatalytic rates observed. A theory of these rates was given based on the deposition in nzetallic contact with the aluminum of part of the copper introduced by corrosion. It has long been known in a general way that aluminum containing sufficient copper suffers in hydrochloric acid an autocatalytic acceleration of corrosion resulting from the introduction into the acid of copper ions and their reduction on the specimen as elemental copper, which provides cathodes of low hydrogen overvoltage.&apos;-3 In a previous paper, this phenomenon was identified in single-phase high-purity material at copper levels as low as 20 ppm and an empirical equation describing autocatalytic corrosion rates in 16 and 20 pct HC1 was presented. In the present work the range of acid strength and chemistry studied was extended, a more accurate empirical equation for the autocatalytic rate was determined, and a theory of this rate was formulated. A major source of interest in this system is the intergranular corrosion, which is also strongly influenced by copper content,= and an objective of the present work on general corrosion was to provide a basis for studying the role of copper content in intergranular corrosion, which is experimentally much less accessible.

Jan 1, 1963

By M. Clotilde Apua, A. F. Mulaba-Bafubiandi

"The efficiency of hydrochloric acid (HCl) leaching of gold from low grade gold-bearing material has been investigated in the presence of sodium hypochlorite (NaOCl) to produce in situ chlorine gas which is an oxidizing agent able to oxidize gold metal to its soluble forms. The effect of concentrations of HCl, NaOCl, and mixtures of HCl + NaOCl was sought. Iron and potassium present in the feed were leached and consumed all the HCl. Gold found as inclusion in pyrite was not exposed to the lixiviant. Therefore, leaching of gold from low grade gold-bearing material in aqueous chlorine solution is not an effective process for now.INTRODUCTIONHydrometallurgy of gold is commonly based on cyanide leaching solution. Due to the environmental concerns related to cyanidation and mercury processes, and inefficiency of cyanide gold leaching to dissolve refractory ores, sustainable alternative lixiviant systems, capable of generating gold (I) and gold (III) complexes must be studied. Amongst non-cyanide gold lixiviants there is the chloride/chlorine system (Hilson and Monhemius, 2006; Senanayake, 2004; Pilsniak and Trochimczuck, 2007; Wang et al., 2007; Reeves et al., 1999; Khodadad et al., 2008).In practice, the most oxidizing agents utilized for the leaching of gold as chloride, are chlorine (Cl2) or hypochlorite (HOCl) which are either generated in situ by suitable reaction or added in solution (Adamson, 1972). The dissolution of gold concentrate using hydrochloric acid, sodium chloride and sodium hypochlorite (Cl-/HOCl system) were studied (Puvada and Murthy, 2006). The effect of NaOCl and NaCl concentrations were also investigated. The leaching was performed under the following conditions; time: 4h, solid–liquid ratio = 1:4, at room temperature. It was found that the increase of the NaOCl concentration from 25 to 75 g/L did not have any meaningful effect on the recovery of gold which was about 30% (experimental conditions; S/L ratio = 1:4, NaCl concentration: 25 g/L, HCl concentration: 0.35 M). It was also found that from 25 g/L to 200 g/L NaCl, the recovery of gold rose from 30% to 40% (experimental conditions; S/L ratio: 1:4, NaOCl concentration: 25 g/L, HCl concentration: 0.35 M)."

Jan 1, 2012

By Kenneth Medearis

There is considerable evidence that more rational damage criteria need to be generated with regard to low-rise structures subjected to blasting vibrations. There is not sufficient basis for specifying a maximum ground particle velocity damage criterion such as 2 inches/second. A peak ground velocity guideline does not currently take into account a number of significant parameters, including the predominant frequencies of the ground motion excitation and the structure being excited. Although a number of states have adopted, or are adopting, maximum particle velocity criteria, such criteria have been ruled inadequate in certain legal decisions affecting blasting operations. The development of more rational damage criteria is thus of significant importance.

Jan 1, 1978

By H. L. Washburn, G. L. Judy

DURING recent years thermal drying of fine coal has increased at a tremendous rate, but very little discussion of the several excellent units has found its way into print. This is particularly true for operating and maintenance costs, and the operator who is faced with his first fine coal drying installation must depend chiefly on hearsay when trying to determine what his drying costs will be. This article presents the maintenance and operating costs for the seven drying units now installed in preparation plants of Pittsburgh Consolidation Coal Co. and lists other cost information that should be obtained before any particular drying unit is selected.

Jan 10, 1957

By A. Guan, K. N. Han, J. J. Kellar, D. A. Boyles

Metal ions associated with effluent streams pose an increasing environmental problem for the mineral industry. Various techniques currently in use to combat this problem including bioremediation, chemical precipitation, and ion exchange are reviewed, and their relative advantages and disadvantages discussed. An alternative technique for metal ion removal, adsorption on surface modified alumina substrates is presented. Alumina surfaces were modified by adsorption of organofunctional silanes, and metal ion removal occurs by chelation of the ion by the adsorbed silane molecules. Experimental data is presented for the removal of cupric ions by this method and is compared to cupric ion removal by adsorption on alumina without prior surface modification.

Jan 1, 1994

By R. S. Rickard

Chemical processing of ores has gained new im¬petus in recent years. The reasons are many. They range from the need to process ores that are difficult to beneficiate to the avoidance of pollution. Although many think of chemical processing as a hydrometallurgical operation there are other techniques. An example is chlorination. Chlorination, although examined and discarded by many investigators, is again being considered as a means of extracting uranium1, treatment of silver-lead ores2, and the recovery of base metals from pyrite cinder and ores3. Segregation roasting of copper and nickel ores, a process similar to chlorination, is another chemical treatment being revived.

Jan 1, 1970

By DAVID C. MILLER

Barite deposits occur worldwide and in a variety of geological environments. In recent years, several deposits of barite and barite-lead-zinc have been discovered in northern British Columbia, Yukon Territory and Alaska. Most are associated with Devonian-Mississippian age sediments, and many are syngenetic, bedded-type deposits. The Mel is a barite-lead-zinc deposit; it lies within Lower Cambrian strata and appears to be of epigenetic replacement origin. Figure I is an aerial view of the property from the south. Observations herein described are based largely upon field work, megascopic studies and two recent B.A.Sc. theses (Biasucci 1979, Rennie 1979).

Jan 1, 1984

By J. P. Stone

The Mining Regulatory Affairs review arrived in time for the May issue. The Managing Editor inadvertently buried it in one of his paper piles. Regulatory developments at the federal level involving the minerals industry solid waste disposal under the Resources Conservation and Recovery Act (RCRA) remained at the forefront of concern. The Environmental Protection Agency (EPA) received public comments on two major documents. One was a strawman draft rule covering wastes from mining and beneficiation. The other was a report to congress covering selected mineral processing wastes. The regulation of minerals industry waste management is moving forward on parallel paths. Mining and beneficiation waste is somewhat further advanced.

Jan 1, 1991

By Paul Hopkins

The following methods have been selected from a large number tried while assaying several hundred samples of placer concentrates. It is thought that some of these methods may be useful to those who are required to assay similar products containing large quantities of metallic articles, such as jeweler&apos;s sweepings. No great difficulties will be encountered in assaying black sand from beaches or river bars. Such samples require care in grinding and sifting so that no oversize particles of sold or platinum are lost. It is also necessary to have sufficient silica in the flux to form a fluid slag with the excess of iron, magnesium, or chromium Which such samples contain.

Jan 1, 1934

By Z. Zhang, R. G. Reddy

The viscosities of industrial lead slags of varying compositions were measured as a junction of temperature using a Brookfield viscometer. Based on the experimental data obtained from this study and based on other investigations reported in the literature, an expression was developed to correlate the viscosities of industrial lead silicate slags as a function of composition and temperature. The effect of each individual slag component on the variation of the slag viscosity is identified. The composition dependency of lead silicate slag viscosity is discussed. The calculated results using this viscosity expression are in good agreement with the measured data. Key words: Viscosity, Lead silicate slags

Jan 1, 2003