Search Documents

By R. M. Hudson

The removal of nitrogen from a nitrogenized low-carbon sheet steel that contained 0.011 wt pct N was determined during heat treatment in Hz-N, mixtures. TIze process followed a first-order rate law; that is, plots of the logarithm of nitrogen content in steel were linear with the time of treatment at a given temperature. The rate of removal increased with an increase in temperature from 900" to 1300°F. By 1400°F the rate in dry hydrogen had decreased to a value intermediate between the rates at 1200" and at 1300°F; in wet (2.47 vol pct water vapor) hydrogen the rate at 1400°F was less than the rate at 1300°F and nearly the same as the rate at 1200OF. The rate at a given temperature increased as the 3/2 power of hydrogen concentration in the atmosphere. While wet atmosplzeres were generally more effective than the corresponding dry atmosplzeres, the effect of water vapor was much less pronounced than the influence of hydrogen content. NITROGEN is the principal agent in the strain aging of ferrite, the effect of carbon being secondary.' To eliminate the return of the yield point after straining and aging, it is claimed2 that the amount of nitrogen in solution in steel must be reduced to 0.0002 wt pct. Strong nitride-forming elements (titanium, vanadium, zirconium, and aluminum) can act to eliminate strain aging by combining with nitrogen. It is extremely difficult to decrease the nitrogen content in commercial steels to the low level required by conventional coil annealing because of the poor contact between the strip surface and the reactive atmosphere. However, a variety of gas-metal reactions can be effected by use of the open-coil annealing method,3 in which the metal surface is fully exposed to the atmosphere. With this possibility in mind, the Applied Research Laboratory has studied the influence of time, temperature, and atmosphere composition on the removal of nitrogen from low-carbon sheet steel. MATERIALS AND EXPERIMENTAL WORK Samples from a commercial nitrogenized low-carbon steel (0.010 in. thick) in the cold-reduced condition were used. The chemical composition of this steel is given in Table I. The gas mixtures used are listed in Table 11. The moisture content in the "wet" annealing atmospheres was controlled at a +70°F dew point (2.47 vol pct water vapor) by passing the gas mixture through a glass tube packed with a solid mixture of 10 pct anhydrous oxalic acid and 90 pct oxalic acid dihydrate held at 127°F; this technique has been described previously.4 For "dry" atmospheres, the gas mixtures were passed through a cold trap immersed in liquid nitrogen. A hinged-top Hevi-Duty electric furnace was used with a Vycor-glass furnace tube. When the furnace was at the desired temperature, the gas mixture was passed through the furnace at a flow rate between 1.1 and 1.2 cfh; coupons (size 3 by 3/4 in.) of the steel were pulled into the center of the Vycor-glass

Jan 1, 1964

By Joseph F. Oesterele, Richard S. McCaffery

This investigation was undertaken to determine the quality of different iron blast-furnace slags as desulfurizing agents, and the possibility of using, in the blast furnace, materials of higher sulfur content than is now common. The solution of the problem would render possible the use of higher sulfur iron ores for pig iron and cokes containing more sulfur than now employed, and the economic manufacture of irons and steels of lower sulfur content. It is generally assumed that the sulfur that reaches the lower part of the iron blast furnace is removed from the pig iron by combining with lime to form calcium sulfide. Most of the sulfur introduced with the charge is in combination with iron or manganese or, perhaps in the coke, as a carbon compound.1 The iron and manganese sulfides are more soluble in the iron than is calcium sulfide, and as the latter is generally said to to be more soluble in the slag than the iron and manganese sulfides, this greater solubility of calcium sulfide in the slag tends to free the metal from sulfur. This greater solubility of the calcium sulfide is used not only to reduce the sulfur contents of the pig iron in the blast furnace, but by this means also low-sulfur steels are produced in the open-hearth and electric furnaces. The reaction2 FeS + CaO + CO = Fe + CaS + CO2 requires a high temperature and strongly reducing conditions in the presence of lime. The constitution of blast-furnace slags, first studied scientifically by Vogt13 indicated certain ranges of composition of the slag in which a

Jan 1, 1923

By Richard S. McCaffery, Joseph F. Oesterele

This investigation was undertaken to determine the quality of different iron blast-furnace slags as desulfurizing agents, and the possibility of using, in the blast furnace, materials of higher sulfur content than is now common. The solution of the problem would render possible the use of higher sulfur iron ores for pig iron and cokes containing more sulfur than now employed, and the economic manufacture of irons and steels of lower sulfur content. It is generally assumed that the sulfur that reaches the lower part of the iron blast furnace is removed from the pig iron by combining with lime to form calcium sulfide. Most of the sulfur introduced with the charge is in combination with iron or manganese or, perhaps in the coke, as a carbon compound.1 The iron and manganese sulfides are more soluble in the iron than is calcium sulfide, and as the latter is generally said to to be more soluble in the slag than the iron and manganese sulfides, this greater solubility of calcium sulfide in the slag tends to free the metal from sulfur. This greater solubility of the calcium sulfide is used not only to reduce the sulfur contents of the pig iron in the blast furnace, but by this means also low-sulfur steels are produced in the open-hearth and electric furnaces. The reaction2 FeS + CaO + CO = Fe + CaS + CO2 requires a high temperature and strongly reducing conditions in the presence of lime. The constitution of blast-furnace slags, first studied scientifically by Vogt13 indicated certain ranges of composition of the slag in which a

Jan 1, 1923

By J. D. Bateman

At Giant Yellowknife, where high grade gold-bearing orebodies are highly irregular in shape, geology has been applied extensively to the mining of ore. The classical functions of the mine geologist in the fields of exploration and mine development have been extended to guide ore extraction, ensuring "clean" mining and effectively reducing waste dilution. THE property of Giant Yellowknife Gold M.ines Ltd. is situated west of Yellowknife Bay on the north shore of Great Slave Lake, a distance of 600 air miles north of Edmonton, Alberta. The Giant claims were staked in 1935, the company was formed in 1937, and the main orebody system was disclosed by diamond drilling in 1944 following a geological study of the property by A. S. Dadson,* Consulting Geologist for the company. Production began in 1948 at the rate of 200 tons per day and, during 1950, reached a daily rate of 425 tons. During the first 3 years of operation a total of 366,000 tons was milled with an average grade of 0.79 oz of gold per ton. Work is in progress with an expansion to 700 tons per day in view. A descriptive account of the geology and gold-bearing shear zone has appeared previously.* The rock formations in the vicinity of Yellowknife Bay have been subjected to protracted pre-Cambrian tectonic deformation culminating in a series of late faults having a cumulative horizontal displacement exceeding 11 miles. The Giant property is underlain by part of an Archean sequence, several miles thick, consisting of basic volcanic flows and minor intercalated tuffs. The volcanic succession forms the west limb of a major syncline, the flows facing east, but overturned on Giant property to dip west at 65" to 75". Orebodies are confined to shear zones up to 200 ft in width, which were formed along early thrust faults. The shear zones assume fold-like attitudes, the larger of which have an amplitude of several hundred feet. The rock formations beyond the limits of the zone of shearing do not reflect the simulated folds, the axes of which are within a few degrees of the strike of the flows. The schistosity and most of the planar elements in both the shear zones and the orebodies dip west • A. S. Dadson and J. D. Bateman: Structural Geology of Camdian Ore Deposits, Can. Inst. Min. Met. Jubilee Volume (1948), PP 273-283. at angles between 65" and 75", generally corresponding to the dip of the flows. The planar elements within the shear zone system thus dip more or less constantly west whether the shear zone is flat, vertical, or expressed as east or west dipping limbs. The shear zones reflect the deformation and alteration of the basic volcanic flows into chlorite schists which, in most places, have undergone metasomatic replacement to form chlorite-sericite-carbonate schists or sericite schists. The boundaries between the shear zones and country rock, although often gradational, usually can be defined within a few feet or even inches as they are expressed by the limits of metasomatic alteration. Orebodies may occupy a small or large proportion of the shear zone and, although they generally conform to the shape of the zone, their morphology is much more complex. Ore boundaries in some instances are sharp and can be delineated with a chalk line; but more generally, a large proportion of the ore boundaries is not visually obvious and can be determined only by the perception acquired by the geological mapping of ore or study of drill cores. Ore shoots in fold-like attitudes may transect the planar elements of the shear zone at any angle; yet the schistosity within the ore shoot may be coincident with that in the enclosing shear zone. Thus it is clear that problems may arise in the delineation of mining boundaries. Ore generally consists of 20 pct or more quartz with ferruginous carbonates in sericite schist deposited in two dominant stages. The earlier stage limits of quartz with carbonate, pyrite, and very fine-grained arsenopyrite in lenses and bands. The later stage consists of quartz-carbonate lodes, in

Jan 1, 1952

By Strathmore R. B. Cooke, Paul B. Queneau

The kinetics of the dissolution of scheelite in basic solutions of carbonate and fluoride were investigated. Work was also done with solutions of alkali metal chloride, hydroxide, phosphate, and mixtures of phosphate and fluoride. The study was conducted at 90 psig and at temperatures ranging from 100" to 155"C, and both natural and synthetic scheelite single crystals were used. The interaction of scheelite with carbonate solutions generally followed a parabolic rate law, and resulted in the formation of calcite crystals on the attached surface. The transport of the CO3 through the calcite to the scheelite surface was probably rate -controlling between 115" and 135°C. Positive deviations from Parabolic behavior were observed at 100" and 155?C, presumably due to the calcite grain growth, and to the formation of a noncoherent calcite layer, respectively. The leaching of scheelite with alkaline fluoride solution produced a calcium fluoride reaction-product which covered the surface as a sheet-like layer. Below 110°C the dissolution rate was parabolic; at 115" and 135°C it was linear. In the linear region, the periphery of the calcium fluoride layer lifted from the sample. Only the lower layers, braced by the scheelite substratum, remained unbroken. This bound layer, approximately constant in thickness, limited the rate at which the fluoride could attack the scheelite. The phosphate and phosphate-fluoride leaches dissolved scheelite at a linear rate; solid reaction products were respectively hydroxyapatite and fluorapatite. Sodium hydroxide and chloride were not effective leachants, and did not produce observable solid reaction products. THE feasibility of pressure leaching of scheelite pulps with basic solutions containing either carbonate or fluoride ions, as indicated by the following equations, has been established by previous investigators:1-3 200°C CaWO4s + CO37q - CaCO3s+WO4aq [1] 200°C CaWO4s + 2Faq ^ CaF2s+WO4aq [2] It is to be noted that a commercial process employing reaction [I] is in use at Union Carbide's operation near Bishop, Calif. In the earlier work referred to, it was apparent that the precipitation of the solid reaction-product on the scheelite particles sharply reduced contact of the leachant with the scheelite. We have extended this work by studying the kinetics of dissolution employing single crystals of scheelite of known exposed surface area. In addition, the effectiveness of solutions of phosphate, of phosphate with fluoride, and of chloride and hydroxide as leachants for scheelite have been investigated. EXPERIMENTAL Apparatus. The low-pressure autoclave used in this wo (100 psig maximum) is essentially that of J. Halpern4 as modified by F. A. Forward.5 Constructed entirely of 316 stainless steel, its maximum capacity is 4000 ml. The temperature in the autoclave was regulated to *0.5?C by a Wheelco thermocouple controller. A 4-in. diam, three-bladed impeller, circulated solution upward against the sample, and a strobo-scope permitted holding the stirring rate to *15 rpm. A check valve and a "pop" type safety valve were installed, a sample holder was fixed to an externally adjustable rod, and a water-cooled condenser was placed in series with the sampling valve. The stainless steel sample holder, Fig. 1, held the epoxy-mounted sample (f) five mm above the impeller. Tightening the tapered sleeve (d) positioned the epoxy-resin specimen-mount by forcing it back against the spacer (c). The mount (e) was 1 in. diam. Sample Description and Preparation. Both synthetic and natural scheelite crystals were leached. The former were single crystals of 99.95 pct purity which were leached approximately perpendicular to the "c" axis; they were supplied by the Gallard-Schlesinger Chemical Manufacturing Corp. The natural crystals, supplied by Minerals Unlimited, were transparent, analyzed 99.8 pct CaWO4, and in ultraviolet illumination exhibited the characteristic blue glow of substantially molybdenum-free scheelite. To permit exposure of an essentially constant surface area of scheelite to the leachant, the samples were mounted in Scotchcast Brand Resin No. 250 (Minnesota Mining and Manufacturing Co.). The mount-

Jan 1, 1970

By M. H. Caron

THE most outstanding property of ammonia liquors, used in the ammonia leaching process is their very limited ability to dissolve all compounds present in reduced ore except nickel and cobalt. Although they do have such a high degree of purity, even the smallest amounts of impurities contaminate the precipitate of basic nickel carbonate that may be obtained from pregnant liquors by straight distillation. Figures have been given in a separate paper regarding the extent of such contamination. The product of straight distillation is likely to contain small amounts of Fe, Mn, MgO and SiO2 as well as some sulphate and sulphide. The sulphur can be readily eliminated by calcination of the product at the proper temperature and MgO and SiO2 by reduction and melting of the metal with a suitable flux. After such treatment the metal is relatively pure, and the iron and manganese content will be very small. The cobalt content, however, may vary considerably, depending upon the ore treated. The metal obtained from pure true garni-erite ores usually has only a small cobalt content of less than 1 pct. Metal obtained from medium grade iron-rich nickel ores may show cobalt values from 2 to 3 pct, and the alloy obtained from laterite is likely to contain as much as 10 pct cobalt. By proper treatment a good deal of cobalt may be recovered from lateritic nickeliferous iron ores, and cobalt will become the major constituent of the pregnant liquor if asbolan ores or similar products are treated. The pregnant liquor of "run of mine" nickel ores may have a pinkish shade, indicating the presence of cobalt. It is evident that from such liquors the metals should be recovered separately. Even if cobalt is present in only very small amounts, it would probably be economically justifiable to recover both metals as pure as possible if a suitable process could be devised. The author has made investigations along this line and has patented some processes adapted to the treatment of this type of solutions. Selective Dissolution of Nickel from Basic Nickel Carbonate Containing Some Cobalt: Basic nickel carbonate obtained from true garnierite ores by straight distillation of the pregnant liquors, always contains some cobalt as well as the normal impurities. In. order to improve the quality of the nickel product and to recover most of the cobalt, the following process has been devised. By using liquors with a low CO2 to NH3 ratio, nickel can be redis-solved preferentially to cobalt. It is not a sharp and clean separation but a selective one, for the bulk of the nickel may be redissolved with a small amount of cobalt, and a small residue may hold the bulk of the cobalt. The greatly increased cobalt content of the residue is indicated by a pronounced olive green color, in contrast with the light green color of pure basic nickel carbonate. The following example is given from Dutch patent No. 52788, Klasse 40a. 43 granted June 17, 1942: The original precipitate contained about 0.55 pct cobalt calculated on total nickel + cobalt. Eight hundred and fifty grams of the basic nickel carbonate were redissolved in leach liquor containing 7.12 pct NH3 and 2.12 pct CO2. The weight of the dry residue was about 3.5 pct of the original weight. By analysis it was found that the residue contained: Fe 1.93 pct, Co 6.01 pct, Ni 34.87 pct and also a certain amount of silica. The clear filtered blue liquor was distilled and the precipitate of basic nickel carbonate from this analyzed: Fe 0.008 pct, Co 0.0146 pct, Ni 42.37 pct. It is obvious that this product is considerably more pure, since calculation shows that about 94 pct of the original cobalt remained in the residue. Cobalt and nickel can be recovered by further

Jan 1, 1951

By R. F. Sheldon

The discovery of the Carlin deposit was the result of discriminating geologic research and prospecting devoted to the objective of finding a gold deposit that could be mined by open pit methods. By the late 1950s, Newmont Mining Corp. was becoming increasingly concerned about the trend of rapidly rising underground mining costs unless bulk mining methods could be applied. The desirability of finding an open-pittable gold deposit was apparent. The attention of Newmont geologists was directed to Nevada by the publication of two papers: "Paleozoic rocks in North-central Nevada" (1958) and "Alinements of Mining Districts in North-central Nevada" (1960), both authored or co-authored by Ralph J. Roberts of the United States Geological Survey. John Livermore, geologist of Newmont Exploration Ltd., attended a talk given by Roberts in Ely, Nevada in the summer of 1961. These papers and the address by Roberts gave details concerning the Roberts Mountain overthrust, a 483 km (300-mile) long, shallowdipping fault which pushed clastic and volcanic rocks of early and middle Paleozoic age eastward over younger marine formations. Subsequent uplift and doming with consequent erosion had locally removed the upper plate strata exposing windows of lower plate carbonate rocks. Roberts noted that the principal mineral deposits of the region, including gold, were associated with these windows which exhibited a preferred alinement. In the summer and fall of 1961 Newmont's exploration geologists John Livermore and J. Alan Coope began a systematic examination of gold occurrences associated with these windows, aided by further discussion with geologists of the US Geological Survey. Attention was directed to the Lynn and Carlin windows, particularly to those formations lying immediately above and below the Roberts Mountain fault. It was appreciated at the time that many of the gold occurrences in the region were unusual in that no colours were obtained even when panning high grade samples. A large number of rock samples were collected and analysed using fire assaying procedures, and background values for gold were established. This systematic rock sampling resulted in the identification of a distinct area of anomalous gold values, and a block of claims was staked in late October, 1961. These claims, plus an adjoining optioned 32.4 ha (80 acres) of ground, cover the main area of the present Carlin gold mine. Prior to snowfall that winter, one of the bulldozed assessment pits required to establish a claim's discovery exposed 24 m (80 ft) of mineralization assaying 0.007 kg/t (0.22 oz per st) gold. In the spring of 1962 a program of trenching, sampling, and geological mapping followed by rotary drilling was underway. Other properties in the area were acquired. The generally undistinguished nature of the dolomitic siltstones and silty dolomitic limestones hosting the micron-sized gold particles, coupled with the lack of visually associated guide minerals, made identification of the gold bearing areas very difficult. The entire drill column had to be assayed to ensure that values were not overlooked, as very often sections that might be assumed to be waste turned out to be high grade. On September 10, 1962 a high grade intersection of 24 m (80 ft) assaying over 0.03 kg/t (1 oz per st) gold was encountered in the third hole drilled. An expanded program of both rotary and diamond drilling led to the further delineation of the ore body. By December 1963, the exploration program had established an initial reserve of 10 Mt (11 million st) grading 0.01 kg/t (0.32 oz per st) gold. A 1.8 kt/d (2,000 stpd) processing plant was constructed and the first gold bullion was poured in May, 1965, just two years and eight months after the discovery hole was drilled. REFERENCES Roberts, R.J., Holz, P.E., Gilluly, J., and Ferguson, H.G., 1958, "Paleozoic Rocks in North-central Nevada," Bulletin American Association of Petroleum Geologists, Vol. 42, No. 12. Roberts, R.J., 1960, "Alinements of Mining Districts in North-central Nevada," Professional Paper 400-B, US Geological Survey, Article 9.

Jan 1, 1985

By George D. Dub

INTRODUCTION OWENS LAKE is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.2H20) and borax, (Na2B407.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. CLOSED BASINS Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I Chloride type; largely sodium chloride (NaCI) and of oceanic type, such as Great Salt Lake. Related is the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. 2. Sulphate type; largely sodium sulphate (Na2S04) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate-chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate-Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1947

By E. W. Stewart, G. P. Conard, J. F. Libsch

The effects of several additives upon the reduction characteristics of hydrogen-reduced ferrous formate are described. The various additives inhibit sintering of the reduced iron particles by apparently different mechanisms. The magnetic properties of the low density compacts produced from the resulting ultra-fine iron powders were improved markedly. THE permanent magnetic characteristics of ultra-fine iron powder prepared by various means have been a subject of considerable interest and experimentation in the past few years. When such particles are small enough to show single domain behavior, they possess' 1—permanent saturation magnetization, and 2—high coercive force. In the absence of domain boundaries, the only magnetization changes in a particle occur through spin rotation which is opposed by relatively large anisotropy forces. With decreasing particle size, the coercive force tends to increase to a maximum and then decrease because of the instability in magnetization associated with thermal fluctuations. Kittel' has calculated the critical diameter at which a spherical particle of iron can no longer sustain domain boundaries or walls to be approximately 1.5x10-' cm. Stoner and Wohlfarthr in England and Neel4,6 in France have shown from purely theoretical calculations that the high coercive force expected from single domain particles is dependent upon crystal anisotropy, shape anisotropy, or strain anisotropy contributions. Further work by Weil, Bertaut,' and many others has contributed much to the understanding of fine particle theory. Neel and Meikeljohn" have demonstrated that a decrease in particle size below a critical value of approximately 160A leads to a quite rapid decrease in coercive force because of the prevention of stable magnetization by thermal agitation. Lih1, working with powders prepared by the reduction of formate and oxalate salts of iron, has shown the marked influence of powder purity upon magnetic properties. Maximum coercive force was obtained in powders of approximately 65 pct metallic iron content while the maximum energy product, (BxH) occurred in powders of 85 pct metallic iron content. Careful consideration of the preceding theoretical considerations and experimental results has led to the manufacture of permanent magnets from ultra-fine ferromagnetic powders by powder metallurgy techniques. Such work has been done by Dean and Davis," the Ugine Co. of France, and Kopelman." The aforementioned work of Kopelman and the Ugine Co. was concerned somewhat with the effect of various additives upon the properties of hydrogen-reduced ferrous formate. Virtually no work, however, has been published on the effects of additives on the reduction rates of metal formates, although unpublished work by Ananthanarayanan16 howed promise of improved energy product in ultra-fine iron compacts prepared by the hydrogen reduction of a coprecipitated mixture of magnesium and ferrous formate. After consideration of the preceding information, it was hoped that a better balance between the metallic iron content and particle size of the reduced iron powder could be accomplished by a prevention of the attendant sintering of the partially reduced iron powder during the reduction reaction. It appeared possible that magnesium oxide might interpose a mechanical barrier between adjacent iron particles and prevent their sintering together, while metallic cadmium and metallic tin would interpose a liquid barrier which might accomplish the same purpose. The degree to which these materials were effective in accomplishing the foregoing objective and the experimental details associated with the work are reported in the following sections of this paper. Experimental Procedure Preparation of Formate and Oxide Mixtures: To obtain ferrous formate of reproducible reduction characteristics, a slight modification' was made in the technique of Fraioli and Rhoda." A supersaturated solution of ferrous formate was mixed with an equal volume of 95 pct ethyl alcohol and the formate crystals precipitated by stirring and screened to —325 mesh. These crystals were in the shape of elongated hexagons, approximately 4x10 micron in dimension. Various preparations of such ferrous formate, designated as lot 111, were reduced for 2 hr, yielding ultra-fine iron particles of exceedingly reproducible size, metallic iron content, and magnetic properties. The magnesium and cadmium formates were prepared by the reaction of dilute formic acid with their respective carbonates, while the tin formate was prepared by the reaction of dilute formic acid with stannous hydroxide. To evaluate the effect of metallic formate additives in intimate mixture with the ferrous formate, varying amounts of magnesium, cadmium, and tin formates were coprecipitated with the latter. The designations of these materials and their chemical compositions are given in Table I. Due to the differing solubilities of the various formates in aqueous media,

Jan 1, 1956

By C. R. Kyle, R. L. Perrine

A transparent model of a reservoir has been used to study some characteristics of instability in miscible displacement. The linear model dimensions are 1/4 in. x 91/2 in. x 10 ft. The model is packed with spherical glass beads. Thee groups of experiments have been performed. The objectives were to measure, respectively, the rate of growth of the transition zone, flow velocity variations in the transition zone, and the effect of a graded viscosity zone on stability. All experiments were compared, where possible, with theory. The transition zone grew almost linearly with distance traveled, regardless of flow rate, where adverse viscosity ratios were used. At very adverse viscosity ratios and large distances traveled, some reduction below linear growth was noted. This could be attributed to the effects of mixing. General similarity in flow pattern was commonly shown in different tests, although exceptions occurred at the higher viscosity ratios. Injection of tracer spots permitted direct experimental measurement of velocity variations. Statistical methods were used to compare observed velocity variations with recently published theories. Surprisingly good agreement with some theoretical predictions was obtained. In the experiments using an initially graded viscosity zone, macroscopic stability was reached before predicted by theory. Under conditions theoretically considered to be slightly unstable, any fingering tendency was too slight to become observable within a 10-ft long system. The general correlation of all experiments with published theory was good, and suggests that theoretical predictions can be extended to reservoir problems. INTRODUCTION Early laboratory studies of miscible displacement demonstrated the high recovery efficiency possible with this method. Linear laboratory models showed that, under some circumstances, all in-place hydrocarbons could be recovered using as little solvent as 5 per cent of the pore volume. These results led to a series of pilot field projects. Under realistic conditions, however, other laboratory studies showed that a small solvent bank may not recover much more oil than a conventional gas drive. The cause of this lack of efficiency is unstable viscous fingering. The size of the solvent bank required to give optimum recovery is, therefore, a question of great economic significance. The object of the experiments described in this paper was the quantitative measurement of unstable flow parameters, the verification of present theories on the miscible displacement process, and correlation of these theories with ex peri mental observation. Of the theories which have been advanced, those by Dougherty, Koval and Perrine show promise of predicting reservoir performance with reasonable accuracy.l-7 The present experiments were correlated, where possible, with the theories of Koval and Perrine. Dougherty's theory was not used because of the additional computational difficulty it presented and the belief that no further information would result. EXPERIMENTAL EQUIPMENT A transparent reservoir model, consisting of a vertical reinforced plexiglass column, was used for the experiments. The column was packed with glass beads, which served as the porous medium. To induce a known velocity disturbance in the flow, a double cosine wave restriction in the transverse cross-section was placed at the top of the column. To mark the flow field and provide a means of measuring the local fluid velocity, a dye-spot injection system was provided. The column was 10 ft high by 1/2 in. wide by 1/4 in. deep. The cosine restriction was placed 16 in. from the top of the column. The glass beads were smooth and spherical and had a mean diameter of 0.0102 cm. Liquids entered the top of the column through a manifold allowing three points of entry (left, center, and right, or any combination of these). A positive-displacement pump with variable-speed drive was used to control liquid flow rates. The pump transferred viscous oil from a reservoir to an accumulator, which displaced the test liquid into

Jan 1, 1966

"Located on Missouri River 16 miles N. E. from Helena, 67 miles from Butte and 18 miles below Canyon Ferry. River drainage area 16,000 sq. miles.DAM: Built in 1907; rebuilt of concrete in 1911. Maximum height 129.3 ft., length over all 720 ft.; elevation of crest 3621; elevation of bridge 3640; normal head 60'; normal tail water elevation 3568.5.SPILLWAY: Length over all 491 ft.; clear opening in 24 sections; 445' flashboards, 14 high to elevation 3635, which is 3.5' above Canyon Ferry normal tail . water elevation.PENSTOCKS: 5 of steel, 12 ft. diam., about 75 ft. long from canal to main turbines, and 3 40-inch diam. from canal to exciters.WHEELS: 5 main pairs, horizontal, center discharge, 48-inch bronze turbines, 225 rev., 4,000 h-p. at 60 ft. head, made by S. Morgan Smith Co., direct coupled to generators, and--3 single, horizontal, 25-inch units, direct coupled to exciters.GENERATORS: 5 W. E. & M. Co. water wheel type, revolving field, 2,800 k-w., 2,400 v., 225 r. p. m., 3 phase, 60 cycle alternators.OPERATION: The plant has a larger water storage than Canyon Ferry and can also use stored water from Canyon Ferry storage. Separate transmission lines 13 miles long connect to lines from Canyon Ferry to Butte, and the Plant operates in parallel with the Canyon Ferry plant."

Jan 1, 1913

By C. A. Mezger

DURING my stay at Raposos, State of Minas Geraes, Brdzil, I had the opportunity of making some observations, which, in the shape in which I am able to lay them before the Institute, are only to be considered as an experience which may possibly have important consequences. The ore-bodies worked there for gold are exclusively chimneys, mostly cylindrical, following the dip of the argillaceous slates (about 45° E.), without any visible connection with each other, without veins, and only exceptionally with some small stringers along the stratification, pinching out at short distances from the chimneys. They are composed of quartz with about 8 to 10 per cent. of pyrite and pyrrhotite, and different iron oxides.

Jan 1, 1895

By Nicholas J. Grant, Olaf Troili, John Chipman

D. C. Hilty (Union Carbide & Carbon Research Laboratories, Niagara Falls, N. Y.)—How does this effect of silica compare with the effect of silica in combining with the lime in the slag to reduce the activity of CaO, thereby affecting the first equation? John Chipman(authors' reply)-—That is the object of showing this effect for slags of two different basicities. In the more basic, the silica is more firmly tied up in the slag and is less easily reduced. It is therefore less able to interfere with desulphurization. The important point is that silica is acting in two ways. Of course it is an acid and as an acid it ties up lime and in tying

Jan 1, 1952

HAVING described and taught you the method of assaying silver for gold in the preceding chapter, and therein having proceeded in the order and Drover wav followed in the working of quantities of gold and silver, I could have fled this task of describing to you the first part of parting. In truth, there is no other difference in the method of arriving at the end except in respect to certain precautions that must be taken against the dangers causing loss. In order that you may guard against these, I shall repeat the procedure completely, in addition to the second part of this art, which is the method of reducing the silver to its body.

Jan 1, 1942

By W. M. Duncan, F. S. Kendorski, C. V. Jude

After shotcrete had been in use for a short time al the Climax Mine of the Climax Molybdenum Co., Climax, Colo., it was noted that regular longhole undercutting blasts would severely damage or detach slusher drift shotcrete linings. If this were to be a usual occurrence, the widespread application of shotcrete would have to be reexamined or abandoned. Concrete drift linings are affected less by blasting because of occasional significant gaps between the placed concrete and rock and the greater thickness of poured-in-place linings. Research Project Organized A research project was organized to determine: 1) the seriousness of the problem, 2) more complete in-use shotcrete strength data, and 3) possible solutions.

Jan 12, 1973

By Thomas M. Barczak

The resultant load vector is the representation of the forces applied to a longwall roof support element by caving strata into a single, quantifiable measure of support resistance. The relatively complex kinematics of the shield support prohibit a determination of support resistance simply by summation of leg forces. A method is being investigated by the Bureau of Mines to determine the resultant load vector by instrumenting supports with pressure transducers and strain gages to measure leg, canopy capsule, and lemniscate link forces. This concept has been laboratory tested in the Bureau's Mine Roof Simulator. Functional relationships among variables have been assessed, and confidence intervals have been established for prediction of the resultant load vector parameters.

Jan 1, 1984

By F. Lynwood Garrison

The enormous growth of the manufacture of Bessemer steel in this country within the last few years, due to the almost constant large demand for steel rails, renders it very desirable that our knowledge of the physical and chemical properties of a material upon which we place so much dependence should be increaqed by every possible means. It was with this end in view, and also in hopes of learning something of the causes affecting the regularity of the Bessemer product, that I took up the subject of this paper a short time ago. The lise of the microscope as an instrument of research in the metallurgy of iron and steel is now fairly well established;

Jan 1, 1887

By H. Yoshida, B. G. Liebmann, R. E. Green

In recent years considerable work has been undertaken in order to gain an understanding of the mechanisms responsible for the generation of recrystal- lization textures in face-centered-cubic metals. Two theories have been proposed, that of oriented growth1 and that of oriented nucleation,' and several attempts have been made to check these theories directly by recrystallizing deformed single crystals.3-5 Two groups, Graham-Cahn and Liebmann-Liicke-Masing, studied the orientation of recrystallized grains and their rate of growth, both using strained aluminum single crystals of commercial purity (Graham et al., 99.6 pct, Liebmann et al., 99.8 pct). Surprisingly, the results obtained by the two groups were completely

Jan 1, 1960

By Carl Swartz

IN the course of a recent investigation1 to develop a more satisfactory white-metal. bearing alloy, a number of alloy systems were studied. The cadmium-nickel system showed characteristics desirable in a bearing alloy, and the system was therefore studied in some detail. EXPERIMENTAL METHOD Alloying cadmium with nickel offered no serious difficulty. After melting the cadmium, clean sheet nickel was added while the temperature was maintained at 500° to 600° C: A few crystals of ammonium chloride2 served to clean the nickel when the latter did not "wet" readily. In preparing the individual alloys for thermal and microscopic investigation, a "hardener" containing about 10 per cent nickel was used.

Jan 1, 1933

By Louis A. Panek

Ground movements in the zone adjoining an active cave were measured at four sites in the San Manuel Mine. Measurements were made to detect extension and inclination, basic components of displacement, which can readily be duplicated by mine personnel using relatively simple equipment. The displacements demonstrated the development of a zone of strain relief surrounding the active cave, within which the ground tends to migrate toward the cave, and extension cracks develop tangential to the cave. This expansion of the ground surrounding an active cave can be exploited to promote future caving; it also creates special problems with respect to the design of an effective ground support system for mine openings in the production area.

Jan 1, 1981