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By Ralph W. M. Lai, D. W. Fuerstenau

In aqueous solution, an oxide surface is considered to consist of positively charged surface sites, MOH, neutral surface sites MOH, and negatively charged surface sites MO-. From the mass action law, equations for the distribution of these sites have been derived in terms of the hydrogen ion concentration in solution and the point of zero charge of the oxide. Experiments on the flotation of futile were carried out with sulfonates and amines which are collectors that physisorb, and with oleate, which is a collector that chemisorbs. Flotation response was found to correlate with the site distribution model. A similar correlation was found with published data on iron oxide potation.

Jan 1, 1977

By C. A. Heiland

A. INTRODUCTION (C. A. HEILAND) I. PRINCIPLES OF TEMPERATURE COMPENSATION IN MAGNETIC INSTRUMENTS The principle underlying the majority of magnetic intensity variom-eters is a comparison of the force to be measured with another force of known magnitude. The known force may be (a) of a magnetic nature, such as magnetic fields produced by magnets or coils, or (b) of a mechan-ical nature, such as (1) the elastic forces of wires, or (2) the force of gravity, such as employed in bifilar magnetometers and magnetic balances. In instruments of such type, usually a magnetic system is employed, free to move about either a horizontal or vertical axis, on some sort of a suspension. If the earth's magnetic field alone were present, such a system would adjust itself into the direction of the field or that of its components. Owing to the simultaneous action of the comparison force, however, the magnetic needle assumes a position that differs from the direction of the magnetic force; for all such instruments, the angle of deflection a is given by tan a = F/X, where F is the known and X the unknown earth magnetic force component. In other words, the magnetic system merely serves as an "indicator" for the position of balance of the two forces. Considering the matter from this point of view, it is not immediately obvious why the temperature of such a magnetic system should modify the results. In magnetic instruments, we may distinguish two different effects of temperature: (1) a magnetic effect and (2) a mechanical effect. The first is due to the fact that the magnetic moment of a magnet drops with an increase in temperature. This drop is characterized by the temperature coefficient of the magnetic moment µ (see equation 1). The second effect is due to the change in the .torsion of suspension wires with temperature or to the expansion of lever arms of masses acting on magnetic balances.

Jan 1, 1932

By C. R. Sandberg, L. S. Gournay, R. F. Sippel

The effect of fluid-flow rate and fluid viscosity on oil-water relative permeability determinations was studied using the "dynamic flow technique." In this work relative per-nleability curves were obtained for homogeneous small core .samples from several sandstorle outcrop form-utions. Radio-tracers were used for the determination of fluid saturation and for the detection of saturation gradients. Cobalt-60 in the form of cobaltous chloride was used as a water-phase tracer in some of the experiments. Iodine-131 in the form of iodobenzene and Mercury-20-3 in the form of mercury diphenyl were used as oil-phase tracers in other experiments. Flow rates for each phase were varied within a range of 2.5 to 140.6 ml/hr. Oil-phase vis-cosities under flowing condition,> were varied from 0.398 to 1.683 cp. The relative permbilities ob-tained were found to he solely a function of saturation and independent of flow rare, provided there was no .Saturation gradient induced in the core sample by "boundary effect." Even though equilibrium with re-sped to flowing conditions was obtained at the lower flow rates, where a saturation gradient exists, this equilibrium is of a "contingent"-type rather than the "steady-state" equi-librium implicit in the relative per-meability concept. The only effect of increasing the oil or non-wetting phase viscosity was to decrease the flow rate required for the elimina-tion of the boundary effect. Fairly good agreement between experimentally determined and calculated values of the boundary effect was obtained when the non-wet-ring oil phase was the only Flowing phase. INTRODUCTION In the characterization of reservoir rock, as well as in the solution of reservoir production problems, it is most desirable to have reliablc rela-tive permeability measurements for the rock and fluids of interest. Many techniques have been developed for the laboratory determination of the relative permeability of both large and small core samples. In varying degree, difficulties attend the use of all of the methods. Each of the methods requires the metered flow of fluids of known viscosity through the core sample under conditions wherein the pressure drop in the individual flowing phases can be measured or closely approximated. Since the relative permeability is a function of the saturation and distribution of the flowing fluids, some means of obtaining such information is also required. The laboratory determination of the relative permeability of a sample should give the same relative permeability saturation relationship that would exist if the sample were in place in the oil reservoir. The attainment of this objective is complicated by the fact that the use of small core samples for laboratory measurements is usually necessary. As a result, errors in measuring the relative permeability arise from boundary effects at either the fluid input or output ends of the sample; no significant boundary effect is anticipated at the sides of the sample normal to direction of fluid flow. At the input end of the sample a boundary effect exists if the flow fluids are not com- mingled as they would be in the reservoir. At the output end of the sample a boundary effect exists as a result of discontinuity of the capillary properties of the system. Here the flowing fluids leave the small flow channels and enter a collecting system having much enlarged flow channels. Thus, there is a tendency for the wetting phase to be retained by the core sample because of the attraction of the core sample for the wetting fluid. No reference is made to these boundary effects in either Darcy's equation or in the relative permeability concept. As a consequence the saturation effect peculiar to the input end of the core sample may cause an error in the effective permeability measurement, since some portion of the core sample must be utilized for commingling of the flow fluids. At the output portion of the core sample a saturation gradient or a saturation change along the axis of flow results. Since relative permeability is a function of fluid saturation, this saturation gradient may cause a variable permeability measurement, especially since extent and character of the saturation gradient can vary with fluid-flow rate. The most convenient method of minimizing the boundary effect, especially at the output end of the sample, is to flow the fluids of interest through the core sample at such high rates that the capillary forces arc insignificant as compared to the viscous forces involved in the fluid flow. Since recent work of a preliminary nature has indicated that fluid dispersion in the porous medium increases with the flow rate, the high flow minimizes the boundary effect at the input end of the core sample by enhancing the mixing of the fluids.

By Raymond B. Ladoo

Wollastonite is a calcium metasilicate, with the formula CaSiO3; containing theoretically 48.3 pct CaO and 51.7 pct Si02. It is one of many natural and synthetic silicates with varying CaO/SiO2 ratios, with and without water of crystallization. While it is a very common mineral, deposits of sufficient size and purity to be of commercial interest are unusual. There is only one producer (1958) of wollastonite for industrial use in the United States, Godfrey L. Cabot, Inc. at Willsboro, New York. There has been a small production of surface material for ornamental use from near Blythe, California. Carload tests have been made on California wollastonite for making mineral wool and a commercial plant for this purpose was projected in 1957. Properties Wollastonite is monoclinic and commonly occurs in masses or aggregates of bladed or needle-like crystals. It has a perfect cleavage parallel to the long prismatic axis. It is rather brittle and some types grind easily to a very finely fibrous product, but other types, due to interlacing of fibers, are tough and difficult to grind. Mobs hardness is 4.5 to 5; specific gravity 2.8-2.9; index of refraction 1.616 to 1.631; melting point 1,512°C. Color when pure is a brilliant white, but when less pure it may be gray or brown. Luster is vitreous, transparent to translucent. Common mineral associates are garnet (several varieties), diopside, calcite and quartz. The nature of the mineral impurities determines to a large degree the commercial value of a deposit. At Willsboro, New York, the impurities consist chiefly of iron garnet and iron diopside which are both magnetic and so are easily removable by magnetic separation, yielding a nearly theoretically pure product. Some deposits in California contain calcite and quartz which cannot be removed cheaply, thus limiting market possibilities. Occurrence Wollastonite is a contact metamorphic mineral occurring in most places within or associated with impure limestones. The deposits at Willsboro, New York1,2,3,5 consist of two or more beds dipping 15-50°E and striking NW-SE. The main bed, 30 to 70 ft thick, may be traced on the surface for at least 2 ½ miles. In this belt, the Pre-Cambrian Grenville limestone has been injected and partially replaced by the more liquid portions of an anorthositic magma. Buddington and Whitcomb3 have described the rock as "Mixed gneisses, pyroxenite and garnetiferous gneisses and skarns." Prospecting revealed the wollastonite at ten different places in the belt, overlain in most places by a garnet rock. Diamond drilling has proven several million tons with probable reserves around 15 million tons. Interbedded with the wollastonite are beds of garnet from a few inches to several feet in thickness. In the wollastonite ore itself the chief and almost only associated minerals are garnet (mostly almandite but some andradite and grossularite) with small amounts of green hedenbergite. Inasmuch as the almandite and diopside are magnetic they are easily separated from the wollastonite in high intensity magnetic separators. If grossularite should occur in quantity other means of separation would be needed. Wollastonite has been reported at 35 localities in California12 but only those in the Big Maria and Little Maria Mountains, 16 to 20 miles north of Blythe, Riverside County, are

Jan 1, 1960

By Persifor Frazer

These properties, owned by Mr. William A. Butcher, of Philadelphia, are in the Panuco Mountain, which lies about thirty miles southwest of the town of Candela. It is a granite which penetrates the surrounding limestones and contains the famous copper-mine to which it gives its name. This mine, which is the property of a company in Philadelphia, has long been known to produce gold as well as copper from almost all its parts; and in corroboration of this be it said, that the undersigned has washed gold from a number of places where the works of the mine or natural sections had exposed the decomposed granite to view in the state of kaolin. It is well known that these junction- or contact-planes between two different formations are often the lodging-places of much freemilling gold, which through fissures are sometimes carried long distances perpendicular to the strata and into the interior of the formation. The structure of the Panuco Mountain, with its outlying spurs and adjacent foot-hills, forms a most instructive and unusual study. At a rough guess the area covered by this mountain will equal, perhaps, twenty-five to thirty square miles ; but its singular feature is the intimate welding together of two formations into one topographical unit. The lines of division between the granite and the calcareous sandstone are of such complicated character that they could not be mapped on a small scale. Unlike the majority of such contacts, the divisions between formations are not always marked in the Panuco Mountain by gulches, valleys, and streams (or the dry beds of the latter), but in the portion of the mountain which lies south of the Panuco copper mine, the lines of junction of these formations cross the gulches and promontories, and, in some instances, cannot be traced by any such topographical features. The house of the Panuco copper mine is 3742 feet above oceanlevel (by rough barometric observation), and the gold-mine about to be described is 235 feet above this, and about two miles distant,

Jan 1, 1886

By William E. Ford, Edward Salisbury Dana

276. Cohesion, Elasticity. - The name cohesion is given to the force of attraction existing between the molecules of one and the same body, in con- sequence of which they offer resistance to any influence tending to separate them, as in the breaking of a solid body or the scratching of its surface. Elasticity is the force which tends to restore the molecules of a body back into their original position, from which they have been disturbed, as when a body has suffered change of shape or of volume under pressure. The varying degrees of cohesion and elasticity for crystals of different minerals, or for different directions in the same crystal, are shown in the prominent characters: cleavage, fracture, tenacity, hardness; also in the gliding-planes, percussion-figures or pressure-figures, and the etching-figures.

Jan 1, 1922

By T. Yamasaki, S. Usu

Adsorption of potassium dodecyl xanthate from aqueous solutions on artificial and natural zinc sul-fides was studied by means of infrared absorption spectroscopy. The adsorption species and their stabilities varied depending upon the conditions of the surfaces of the zinc sulfides. Adsorption products were analyzed after they had been removed from the surface with pyridine. Zinc dodecyl xanthate was confirmed for surfaces covered with oxidized products while dodecyl alcohol and carbon disulfide were detected on purified or weakly oxidized surfaces. It is of great significance to study the adsorbed species of collectors on the surface of sulfide minerals with a view of increasing our understanding of the mechanism of flotation. Compared with other methods, infrared spectroscopy promises to be of particular value in determining the nature of the species adsorbed at the mineral/solution interface since it gives direct identification of the adsorption products; and, furthermore, it has an advantage over the electron diffraction technique which has been employed in similar problems in that infrared spectroscopy utilizes radiation of very low energy so that the probability of changing the unstable surface films during examination should be correspondingly decreased. Infrared spectroscopic studies concerned with sulfide mineral flotation have already been reported by several investigators on zinc sulfide-hexanthi01' and lead sulfide-xanthate2,3 systems. The purpose of the present study was to investigate the adsorption of potassium dodecyl xanthate (KDX) at the zinc sulfide-aqueous solution interface by means of infrared spectroscopy. Rarely is the pure zinc sulfide-xanthate system encountered in practical flotation since zinc sulfide is usually activated with small amounts of certain metallic ions, such as copper ion. However, investigation of the pure zinc sulfide-xanthate system appeared promising for studying the fundamental mechanism of the adsorption of xanthate on the sulfide minerals. Although there are few cases where xanthates having an alkyl radical higher than hexyl are employed in practical operations, KDX was used in this study since it was reported that the adsorbability of xanthate on zinc sulfide was increased with an increasing number of carbon atoms of the alkyl radicals.4 EXPERIMENTAL Samples: Experiments were made on artificial zinc sulfide and natural sphalerite. The artificial zinc sulfide was obtained commercially from Dainihon Toryo Co. as a fluorescent pigment of the purest grade A. Considering the fact that there are often cases where the surface of sulfide minerals are apt to be oxidized so that the adsorption of xanthate at sulfide mineral/solution interfaces may be substantially affected, two different procedures were employed in preparing the samples of the artificial zinc sulfide. 1) The zinc sulfide was washed with hot concentrated ammonium chloride solution (300 g per liter) to remove surface oxidation products and followed by washing with deoxygenated hot distilled water by centrifugation until the constant electric conductivity of the solution was reached (Sample I) (specific conductivity of the solution = 8.6 x l0-5 ohm-' cm-'). 2) Sample I in a suspension of 5% by weight was oxidized with a 1.5% aqueous hydrogen peroxide solution for about one hour, and then was washed with distilled water as mentioned in the preparation of Sample I (Sample 11) (specific conductivity of the solution = 1.0 x 10"4 ohm-' cm-'). Both Samples I and II were dried under vacuum and stored in a vacuum desiccator. The specific surface areas of the samples determined by the BET method using carbon dioxide gas were 19 x l04 cm2 per g for Sample I and 35 x l04 cm2 per g for Sample 11. In addition, a sample which was derived from Sample I was also prepared. In 40 ml of 3 x 10-2 M zinc sulfate solution was placed 2 g of Sample I for 2 hours, washed with distilled water by successive centrifugation until no sulfate ion could be detected and dried under vacuum (Sample 111). The purpose of this treatment will be described later. Natural sphalerite was carefully selected by hand, ground in a mechanical agate mortar for about 40

Jan 1, 1965

By Alexander L. Holley

A CHARACTERISTIC, and, to Americans, an amusing discussion of the three-high rail-mill, arose out of the reading of Mr. Lauth's paper on three-high plate-mills, at the Glasgow meeting of the Iron and Steel Institute. From the report of the meeting in the English papers, it appears that Mr. Menelaus, the celebrated rail-maker of Dowlais, could not wait for the discussion of Lauth's plate-mill, but launched at once into the British objections to the three-high rail-mill, which is quite another matter. The American mill, which is very different in principle and ar288

By David R. Mitchell, R. B. Hewes

MANY processes for cleaning coal that are in use depend primarily on physical properties of coal and refuse other than specific gravity and surface conditions relating to froth flotation. These properties are shape, coefficient of sliding friction, resilience, friability, magnetic susceptibility, and electrical conductivity. In many of these processes specific gravity does have some effect and many separators are designed to utilize more than one of the physical properties cited. Although the processes described herein do not have a widespread application, yet for specific coals and specific conditions, they are economically important. A problem confronting many coal-mining districts is the marketing of the slacks or screenings and dust passing the final sizing screens. Processes in commercial use installed primarily to increase the form value, and hence the market value, of these slacks and dusts include briquetting, packaging, and low-temperature carbonization. MECHANICAL PICKERS Machines utilizing shape, frictional resistance, and differences in resilience of coal and impurities are usually called mechanical pickers. They require a closely sized feed, therefore their use is confined to the pea, nut, and egg sizes. Various types of these devices are described by Berrisford, 1, 2 Taggart,3 and Peele.4 Shape In general, coal differs in shape from its accompanying dirt throughout the range of commercial sizes. Coal, breaking into roughly cubical particles, contains a greater number of axes that are approximately the same length than does the dirt. The latter, consisting of pieces of slate and shale and lenses of pyrite, is flatter in nature. Further, flat coal often has a dirty, slaty appearance, even though of high quality. Mechanical pickers known as flat pickers, or "flatters," are widely used in the Pennsylvania anthracite region to remove flat coal .from the final clean coal. This practice greatly improves the appearance of the final market product. Flat pickers for removing impurities or flat coal ("flats") are usually installed on shaker screens, shaking conveyors, and chutes. In Fig. 1 three

Jan 1, 1950

By J. N. Hobstetter, J. J. Becker

Slip lines in deformed copper single crystals exhibit very pronounced cross-slip and clustering if the stress axes are not too far from <100>. This orientation dependence seems to persist whether or not attempts are made to reduce the bending constraints of ordinary mechanical tests. THE purpose of this paper is to report some microscopic features of the plastic deformation of copper single crystals. The material used was OFHC copper obtained from the American Brass Co. Single crystals about 3 in. long and 5/16 in. in diameter were made by lowering graphite crucibles containing this copper out of the hot zone of a vertical tubular furnace at a rate of 1 1/4 in. per hr. The furnace atmosphere was nitrogen. The orientations of the crystals were determined by the back-reflection Laue technique.&apos; The X-ray spots usually indicated a slight lineage structure of not more than a degree or two. The crystallography of slip is discussed in Schmid and Boas.&apos; The terms classical slip, cross-slip, and conjugate slip are used here with the same meanings as in ref. 3. Compression Specimen 17 (Fig. 1) was selected because the resolved shearing stresses on eight slip systems dif- fered at most by a factor of 1.2. It was hoped that in this situation such effects as cross-slip might be made more prominent. Two intersecting planes parallel to the stress axis were ground on the crystal, using optical abrasive on a lead lap. The large plane was approximately perpendicular to the plane of the axis and the primary slip direction. Its exact orientation was determined by X-ray. The smaller made an angle of 49" with the larger, measured by reflecting a small light source. The specimen was etched with nitric acid until its diameter had been reduced 0.010 in., and then was given a metallographic polish and very

Jan 1, 1954

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared fot these tests by high-temperature methods, especially by crystallization from borax melts. FLOTATION test work on Bolivian tin ores some years ago led to the development of several workable schemes of selective soap flotation, but left unanswered many questions of soap-flotation chemistry.&apos; Accordingly, the study of the activation and soap flotation of quartz just reported? was undertaken as a start toward the elucidation of some of the unanswered questions. The experimental work on quartz flotation consisted primarily of small-scale, vacuum-flotation tests in which activator and collector additions and pH were varied between wide limits. In the work to be described in this paper, the soap flotation of cassiterite and fluorite was studied by the vacuum-flotation technique developed in the previous study of quartz. Using oleic acid as collector, conditions for floating cassiterite and fluorite in the absence of modifying agents were first determined. Then the effects of barium, calcium, and alizarin dyes on the flotation of cassiterite, fluorite, and quartz were studied. Alizarin dyes were chosen for study because of the promise they have shown as selective modifying agents in the flotation of non-sulphide minerals.12,1 Also, they form a family of reagents in which there should be a systematic correlation of chemical properties with composition. As a preliminary to the study of cassiterite flotation, an investigation of the preparation of synthetic cassiterite and X ray studies of natural and synthetic cassiterite were undertaken. Experimental Methods The flotation technique and most of the reagent preparations were described fully in the previous paper.&apos; In addition, for the present work it was necessary to prepare satisfactory stocks of clean cassiterite and fluorite and to obtain samples of alizarin dyes. Cassiterite: High-grade cassiterite from the Netherlands East Indies was crushed, sized, and cleaned

Jan 1, 1951

By Brahm Prakash, R. Schuhmann

Chemical conditions for flotation and nonflotation of cassiterite and fluorite with oleic acid as collector and with alizarin dyes as modifying agents were studied by means of small-scale, vacuum-flotation tests. Artificial cassiterite was prepared fot these tests by high-temperature methods, especially by crystallization from borax melts. FLOTATION test work on Bolivian tin ores some years ago led to the development of several workable schemes of selective soap flotation, but left unanswered many questions of soap-flotation chemistry.&apos; Accordingly, the study of the activation and soap flotation of quartz just reported? was undertaken as a start toward the elucidation of some of the unanswered questions. The experimental work on quartz flotation consisted primarily of small-scale, vacuum-flotation tests in which activator and collector additions and pH were varied between wide limits. In the work to be described in this paper, the soap flotation of cassiterite and fluorite was studied by the vacuum-flotation technique developed in the previous study of quartz. Using oleic acid as collector, conditions for floating cassiterite and fluorite in the absence of modifying agents were first determined. Then the effects of barium, calcium, and alizarin dyes on the flotation of cassiterite, fluorite, and quartz were studied. Alizarin dyes were chosen for study because of the promise they have shown as selective modifying agents in the flotation of non-sulphide minerals.12,1 Also, they form a family of reagents in which there should be a systematic correlation of chemical properties with composition. As a preliminary to the study of cassiterite flotation, an investigation of the preparation of synthetic cassiterite and X ray studies of natural and synthetic cassiterite were undertaken. Experimental Methods The flotation technique and most of the reagent preparations were described fully in the previous paper.&apos; In addition, for the present work it was necessary to prepare satisfactory stocks of clean cassiterite and fluorite and to obtain samples of alizarin dyes. Cassiterite: High-grade cassiterite from the Netherlands East Indies was crushed, sized, and cleaned

Jan 1, 1951

By C. W. A. Muir

Laboratory and plant-scale testwork on the extraction of gold from highly refractory antimonial and arsenical concentrates using both direct low-alkalinity pressure cyanidation, and acidic pressure pre-leaching followed by ambient low-alkalinity cyanidation, is described. A novel method for treating effluent solutions containing extremely high concentrations of base metal cyanides, as well as arsenic and antimony compounds, was developed in order to make the process ecologically acceptable.

Jan 1, 1984

By Roy Moore

THE Tom Reed Extension and Big Jim mines of United Eastern Mining Co. are situated in the Oatman district, Mohave County, Ariz., about 28 miles southwest of Kingman, the nearest railway point. Articles descriptive of the mine surface plant, mill construction, and plant operations have been written by Otto Wartenweiler1, the designing engineer; Wheeler 0. North,2 when he was assistant general manager for the company, and Earle M. Bagley, mill superintendent.3 The last article covers average costs for the full time the mill was operated. The geology of the mines is described by F. L. Ransome4 of the United States Geological Survey. Production was started in January,. 1917, and the known orebodies were exhausted in May, 1925, showing a life of seven years and five months. On account of the comparatively short life and the fact that stoping operations were confined to two orebodies, little experimenting was done with mining methods. The two orebodies were in what is generally called the Tom Reed-United Eastern vein, which occupies a fault fissure having a normal displacement of several hundred feet. Seven or eight very productive ore shoots were mined along this vein in a distance of 1 ½ miles, the two worked by the United Eastern being 1 mile apart. The maximum dimensions of the Tom Reed Extension ore shoot were height, 750. ft.; length, 950 ft.; thickness, 48 ft. The vein structure varied from a solid quartz-calcite filling to a series of parallel stringers separated by andesite. From this body, 511,976 tons of ore were mined. (Fig. 1.)

Jan 1, 1928

By F. D. Mahone

MUCH crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in&apos; globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the .influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under, the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than 2-per cent. with commercial success.

Jan 7, 1924

By Dennis H. Laubscher

INTRODUCTION The selection of mass mining methods is the situation facing not only planners of new operations, but also those involved with cur- rent operations, including the eventual change from open-pit to underground. Increasing ground control problems on many mines, plus a better understanding of dilution and ore loss problems have meant a review of current mining methods and support techniques. Experiments are only successful if conducted in the right mining environment and on the right scale. Mining personnel have been known for their conservatism and will tend to persevere with an established method rather than change; often, hidden costs will obscure the correct economic assessment. An established mining sequence is not necessarily correct in the long term. However, recommendations to change are usually met with opposition because of inconvenience, temporary production problems and the desire for a trouble-free guarantee. In any planning exercise, care must be taken that time and money are not wasted in trying to achieve the unattainable. During the decision-making period, production personnel must be involved, and, if possible, they should visit similar omrations to that proposed. Co-operative production personnel will help ensure success. Descriptions of mining methods are available in technical papers and books, and it is not intended to discuss this aspect, but, rather, the various factors which must be recognised before arriving at a final selection. In another paper presented at this Conference (Heslop and Laubscher, 1981) factors affecting ore recovery and dilution are discussed in greater detail for various cave mining methods. PRELIMINARY CONSIDERATIONS Comprehensive Geological Data. Geological information is available during the exploration stage, but, often, core from exploration drilling is not analysed with the selection of a mining method in mind. Drilling costs are high, therefore the maximum benefits must be derived from this operation. Holes which have not intersected ore may provide data on possible shaft sites, and 35 mm colour slides of core, sound logging and geomechanics classification, will provide a record which can be used with confidence at a later date. Intersections of the various rock types should be kept for future study; for example, is weathering likely to be a problem, bearing in mind that this can be accelerated in the warm, humid atmosphere of an underground mine. The accumulation of data required to select a mining method starts with initial geological work in the target area, whether this be surface mapping or a diamond drill hole. Publications. As technical papers, reports and books are used in the selection of mining methods, an appeal is made to authors to describe the geological environment so that readers can relate to their own conditions. Not enough emphasis is given to the problems experienced and the techniques employed to overcome them. Follow-up papers are seldom written and we should be prepared to discuss our failures. Diagrams are often misleading, as the ideal and not actual situations are depicted. The caved ore/waste interface is not a straight line, and whereas this may not be significant in a diagram of a 200-117 draw height, it certainly is in sub-level caving with draw zones only 1 - 2 m width but up to 20 m high. SUMMARY OF FACTORS AFFECTING THE SELECTION OF UNDERGROUND MASS MINING METHODS (a) Regional rock stresses and mining geometry. (b) The geomechanics rock mass classification of the orebody and surrounding rock mass. (c) Ratio of the surface area of the ore/unpay interface to the contained ore which determines ore losses and dilution. (d) The cavability and fragmentation data of the ore and hangingwall. (e) The mineral distribution in the orebody and its dilution zone.

Jan 1, 1981

By F. M. Hamilton, R. G. Fleck

As the result of extensive small laboratory experiments, the metallurgical results of sintering iron ore from the Benson mines at Star Lake, N. Y. were clearly defined. But the practical operation had not been proved; so, the sintering strand, which went into operation at the mines in 1952, was designed to minimize the risk involved. It was built by the Dwight-Lloyd Div. of McDowell Co. Inc.

Sep 1, 1956

By A. B. Parsons

When the Seeley W. Mudd Memorial Fund was established in. 1929 the donors mentioned certain types of projects to which preference might be given in selecting those to he financed by the income from the Fund. One suggestion. was that the projects "be of particular benefit to young engineers." This modest little book meets this specification most aptly. It seeks to guide the engineer-particularly the young one-with the least loss of time and effort to the most convenient source of authentic information regarding any topic in which he may at the moment be interested. Knowing the best place to find the literature on a subject is almost as valuable-and far more practicable-than maintaining a library of one&apos;s own large enough to provide the information.

Jan 1, 1933

By D. M. Kehn

A method has been devloped for chromatographic analysis Of the vapor and liquid phases Of a a system containing methane to components having 20 or more carbon atoms. The method uses a windowed equilibrium cell in which volumetric phase behavior of the system can be observed accurately and from which small samples of gas or liquid can be withdrawn for analysis. Analyses are made using two chromatographs, one for the lighter and one for the heavier components in a sample. Combination of the two analyses yields a detailed analysis of the gas or liquid sample. The complexity of the condensate heavy ends is evident from the chromatograms of these fractions, and the predominance of the paraffin hydrocarborn serves as a useful marker in interpreting the chromatograms. The K-values obtained in this analytical method are presented for a high-pressure condensate system and predict closely the observed volumetric behavior of the system. INTRODUCTION Quantitative analysis of hydrocarbons from natural gas reservoirs is necessary for several reasons—to calculate the amount of sales gas produced, to calculate the amount of natural gasoline produced, to plan a liquid recovery system, or to calculate the potential economic value of a reservoir produced under one or more of several different conditions. Analysis of natural gas fluids produced to the surface consists of identifying and computing the mol fraction of each component of the mixture. Although methane is the predominant component, varying amounts of ethane, propane, butane, pentanes and heavier components are also present. Materials containing up to 30 carbon atoms occur in amounts which decrease with increasing molecular weight. However, the quantities of components in the 20 to 30 carbon atom range are usually so small that their importance is negligible, and they are undetect-able in natural gas by ordinary analytical methods. All the components up to those having 20 carbon atoms may sigsficantly affect phase behavior, however. Commonly, only the methane-through-pentane fraction is analyzed quantitatively for each component, while components heavier than Pentane are lumped and repored as "hexane- plus". Expensive, tedious techniques are required for analysis of this fraction. Consequently the detailed analyses needed for prediction of reservoir behavior are usually undertaken only when major gas fields are being developed. The need for complete analyses of condensate systems is apparent when it is recalled that most gas fields are produced by pressure depletion. As the pressure declines, some of the heavier hydrocarbons are lost as liquids which are in the reservoir. In many instances the amount of liquid in equilibrium with the gas phase at high pressure constitutes only 1 or 2 mol per cent of the total system. Flash calculations generally must predict the actual amount of liquid with an accuracy of a few per cent in order to be useful. This retrograde condensation has been understood for years, but accurate correlation methods to permit quantitative prediction of phase behavior in the retrograde region are not presently available. The increasing importance of natural gas has made accurate prediction of phase behavior and composition of produced natural gas streams an economic necessity. The work reported here was undertaken to provide a rapid, economical method for obtaining the vapor-liquid equilibrium information needed to predict accurately the composition of the fluids produced from a gas reservoir throughout its life. TO develop this method, a pressure cell equipped with windows was designed and built for observing the volumes of liquid and gas present at reservoir pressures and temperatures. Use was made of established chromatographic methods for rapid and detailed analysis of both phases. This paper describes the equipment and techniques developed for obtaining vapor-liquid equilibrium data, presents the results of analyses of a condensate system, and indicates the usefulness of these data in predicting hydrocarbon phase behavior. DESCRIPTION OF EQUIPMENT USED The equipment used in obtaining the required information on phase behavior and the complete analysis of hydrocarbon mixtures through C, will be described first, followed by a discussion of the operation of the equipment. It will be helpful, however, to consider first a brief outline of the technique used. A sample of separator gas and liquid is charged to the windowed cell (see Figs. 1 and 2) where volumetric equilibrium phase behavior at reservoir pressures and temperatures can be determined. Then samples of the coexisting phases are withdrawn. The methane-through-pentane fraction is analyzed with a chromatograph equipped with a hot-wire detector, and the pentane-plus fraction is analyzed with a second chromatograph equipped

Jan 1, 1965

Jan 1, 1929