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By R. H. Sweetser

AT the Buffalo meeting in October, 1898 (Trans., xxviii., 865), our Secretary, Dr. Raymond, in speaking of the obstacles he had encountered in securing contributions to the Transactions from members in practice, said: "It is the disinclination of many members to communicate incomplete or partial or preliminary results. They are going to write, ' some day,' a thorough and monumental paper; and meanwhile they prefer to communicate nothing. . . . It is the difficulty to which I have just referred that I have encountered in a wide correspondence with members, undertaken for the purpose of securing contributions of fact and opinion concerning the special subject of this discussion. . . . Almost none of them seem to recognize the value of preliminary, incomplete and indecisive reports of practice, as laying the foundation for a thorough inquiry." This remark was made in immediate reference to a discussion concerning blast-furnace tuyeres ; but, notwithstanding this appeal from the Secretary, little has been recorded regarding the distribution, the penetration, and the pressure of the blast at the tuyeres and inside the iron blast-furnace. I am therefore encouraged to contribute the following incomplete and crude observations of the blast-pressure inside the hearth. At the suggestion of J. H. Frantz, the General Manager of the Columbus Iron & Steel Co., a test was made at the East furnace of the company to determine whether there was any difference in blast-pressure at the different tuyeres. The apparatus used for this test was not sensitive enough to give accurate results. It consisted of a small pressure-gauge mounted on a 3/8-in. gas-pipe. A hollow plug, fitting into the peep-hole of the tuyere-cap, prevented the blast from blowing-out during the test. The test-pipe was held in place by means of the handle on the outer end.

Mar 1, 1909

By Frederic Dewey

(New York Meeting, February, 1913) This old and well-known method of determining, silver is, in bullion work, so far superior to the furnace-assay that it is looked upon with reverential awe by many, if not by most, users, and its-ease of execution, with proper equipment, commends it highly where much commercial bullion work on silver is required. The method is so thoroughly well known that a, description of it here may seem to be unnecessary, but many thousands of determinations are annually made by it in the U. S. Mint Service and its practice is there reduced to an art. This is necessary both for the sake of economy of time, acid because high-grade work with it requires constant practice. It is useless for a person who uses it only occasionally to expect to attain high accuracy with it, without spending more time upon a determination than is warranted in a busy commercial laboratory. It is always employed in the Mint service whenever possible, but its chief field is in the determination of silver in standard silver (ingots and coin), which is 900 fine in silver and 100 fine in copper, and I shall first briefly outline its use on this metal and then take up various points in detail, especially as related to the accuracy of the results obtained.

Jan 4, 1913

By Fun-Den, Wang

An open pit rock structure usually contains geological planes of weakness. They are formed by joints, faults, bedding planes, fractures, and cleavages. Rock slope failures often occur in the form of sliding of rock blocks along a plane or several planes. Such a rock block has three- dimensional geometry, and consequently a vector method of analysis has been found useful in evaluating its stability. Rock blocks of a tetrahedral shape with one free surface have been analyzed by Londe. Rock blocks formed by sets of parallel joints have been analyzed by Wittke. The present chapter presents the analysis of rock blocks formed by planes of weakness of arbitrary orientation, and of three-dimensional geometry.

Jan 1, 1972

By M. A. Mallinger

A series of laboratory tests was conducted to determine the limits of practicability in regulating the weights of various cement slurries. It was found that slurry weights of 12 to 19 lb per gallon could be obtained by adding bentonite to decrease the weight and barytes ore to increase the weight. It was also found that barytes ore was not usable in all cements. LIGHTWEIGHT CEMENT SLURRIES INTRODUCTION During the drilling and completion of oil wells the magnitude of the hydraulic pressures exerted on certain formations is critical. In many cases considerable care must be exercised to prevent drilling mud weights from becoming too high, and in those wells where loss of circulation is a problem, the use of normal weight cement slurries will generally result in lost returns during casing cementing operations. While mud weights can easily be controlled, it is necessary to exercise care in the selection of weight reducing additives for cement slurries in order that slurry weights may be reduced sufficiently to prevent the loss of a large portion of the cement to the thief formations without seriously affecting the setting properties of the cement. EXPERIMENTAL RESULTS An extensive search revealed that a large number of materials .that might have been otherwise practicable as a weight reducing additive were not acceptable for use with oil we cements because the imposition of pressure on the slurries caused the additive being tested to be compressed or to absorb water from the slurries, resulting in negligible decrease in the slurry weight. This search for lightweight additives disclosed that bentonite, a material very commonly used for reducing the weight of drilling muds and cements, produced the best results without undue harmful effects on the properties of oil well cements. It was found that there was a limit to the amount of benton-

Jan 1, 1950

By Michel Dupuy, Daniel Calais

The study of self-diffusion of plutonium in E phase has been carried out by the welded couples method. The tracer used was puZ4O which is detected by its X-ray emission (conversion lines of uranium which are computed between 13 and 21 kev). Intensities were measured with a scintillation counter. Each layer was removed in a direction parallel to the original interface with a grinding machine and a thickness measured with a pneumatic comparator. The concentration-penetration curves obtained were corrected for the effect of heating time from room temperature to annealing temperature and for the expansion due to phase transformations of plutonium. They were analyzed by the generalized Gruzin method. Self-diffusion of plutonium in E Phase is very fast cm per sec between 500" and 620°C) and the diffusion zones are 2 to 3 mm wide for annealing times ranging from 30 min up to 10 hr. The Arrhenius law gives the temperature dependence in the form: From the point of view of self-dqfusion, PUE phase falls into the anomalous bcc metals category (Tip , Hfp, Zrp, Uy) with a low-frequency factor and an activation energy lower than those provided by standard correlations. No theory proposed hitherto to explain these anomalies (influence of dislocations, of extrinsic vacancies bonded to inlpurities, of bi-vacancies) can clearly explain the self-diffusion coeffzcients of plutonium. DIFFUSION in bcc metals is a present-day problem. A recent symposium (Gatlinburg, 1964), followed by a book,' has been devoted to it. A great many experiments seem to show that diffusion in certain bcc metals obeys unexpected laws. The activation energies measured are sometimes strangely low (B hafnium, y uranium). For certain metals (0 zirconium, p titanium) the curves of log D (D = diffusion coefficient) as a function of 1/T (T = absolute temperature) are not linear. The frequency factors Do, which are of the order of 1 sq cm sec-' in fcc metals, vary from 1 to 10~6 sq cm sec-'. Various theories have been put forward to explain these anomalies; none is yet satisfactory. We wished to introduce a new experimental result by studying the self-diffusion in c plutonium. This allotropic phase, stable from 475°C up to the melting point (640°C), is in fact bcc. Unfortunately, nothing is known of the characteristics of the point defects in this phase, which limits the scope of the hypothesis which can be made about the mechanism(s) of self-diffusion in plutonium. 1) EXPERIMENTAL METHODS 1) Principle. We used the welded couple method. The two pellets of the couple initially have different 240 isotope contents (X emitter). After diffusion, the concentration/penetration curves are drawn up by the generalized Gruzin method. 2) Gamma Spectrography. The metal used in our study is plutonium, either low in puZ4O (isotopic content 1 pct) or high in puZ4O (8 pct). The latter also contains plutonium 241 (-1 pct) and 300 ppm of ameri-cium produced by the reaction Pu2U-AmM1 + 8-. The emission spectra of these two plutoniums placed in leak-tight vinyl bags have been studied by y spectrograph~. The detector is a thin crystal of thallium-doped sodium iodide. The activity of the plutonium rich in 240 is about twice that of the plutonium low in 240 in the energy band of 17 kev (L conversion lines of uranium); this band was used in these measurements. 3) Preparation and Examination of the Diffusion Couples. Diffusion couples were made from plutonium with a high and low PU"' content. Pellets (6 6 mm. thickness 3 mm) mounted on a polishing disc with ground parallel faces were polished mechanically on both sides. In this way, pellets with two parallel faces were easily obtained. The polished pellets were joined by a 6 phase anneal (420°C, 1 hr) in a small screw press (pressure of 20 kg per sq mm cold); a centering ring enabled the two pellets to be pressed coaxially. The couples then were subjected to the diffusion treatment by annealing in the E phase in sealed silica ampules in argon at atmospheric pressure. The annealing temperatures and times are given in Table I. The couples were encased in a mild steel ring, the joint interface being thus parallel to the ground face of the ring. The diffusion couple/ring assembly underwent successive abrasions by means of a magnetic plate grinder. The thickness of the abraded layer was measured with a Solex pneumatic comparator when it was less than 0.1 mm (accuracy 0.2 p) or with a mechanical micrometer (accuracy 3 p) for passes of the order of 0.2 mm. All these operations were done in glove boxes, as plutonium is particularly toxic. After each abrasion we determined the emission spectrum of the ground face. The emissive surface is defined by means of a diaphragm 3 mm in diam. We noted more particularly the X activity in the 17-kev

Jan 1, 1969

By C. G., Fink

The dissolution of gold by cyanide solutions was studied by determining the time required for the solvents to dissolve gold leaf. Minute traces, even 0.5 ppm, of sulphide ion retard the dissolution of gold, and this behavior cannot be accounted for by the presently accepted hypotheses involving oxygen-depletion or thiocyanate formation. On the other hand, traces of the salts of lead, bismuth, mercury, and thallium considerably accelerate the dissolution. The beneficial effect of lead is dependent upon the pH and cyanide ion concentration of the solution.

Jan 1, 1950

By Linn Bradley

Introduction MARKED differences of opinion have been expressed by engineers interested in cleaning iron blast-furnace gases for use in hot-blast stoves and under boilers, in reference to the advantages of a hot-dry method over a cold-wet method. One point at issue involves the sensible heat energy in the moisture contained in the gas. Some advocates of the cold-wet methods claim that the condensation and resultant removal of the greater portion of this contained moisture by wet scrubbing, spraying or similar methods, results in a saving of some of this sensible heat energy, by reason of the fact that water vapor has a high capacity for sensible heat energy and may carry from the exit of a hot-blast stove, for example, more heat units than are sacrificed or lost when the gas is cleaned by this cold-wet method. Other advantages claimed for the latter method are: That gas burns more readily when it is free from moisture in any form; that because gas is made denser by cooling and removing the moisture it has a higher calorific value than hot gas carrying moisture; and that higher flame temperatures are obtained when the gas is cleaned by the cold-wet method. A search through the available literature fails to disclose any extensive calculations or records of conditions obtained in practice, bearing upon these phases of gas cleaning. This paper deals with these problems from the standpoint of the economy of using a gas of higher flame temperatures, of improved stove design, and of economy in the gas-cleaning department. Calculations have been made which show that by cleaning the gases by a cold-wet method the sensible heat energy of the blast-furnace gases is greatly reduced; and, in general, this loss of heat energy is far greater than that lost from the stoves or boilers due to the sensible heat capacity of the water vapor if carried away by the exit gases. By making use of the

Jan 2, 1917

By David J. Reddish, Barry N. Whittaker

The characteristics of surface ground strains due to longwall mining are reviewed with special reference to U.K. coal mining observations. The current empirical method of estimating ground strain is discussed. A method of determining surface ground strain above a longwall extraction is described whereby strain can be accurately represented along a line in any direction. The discussion is supported with examples of its application to common subsidence engineering problems.

Jan 1, 1984

By W. R. Davis

This paper presents a sunimary of the results of a study of the Dornick Hills-Springer sand reservoir of the Velma Pool. Stephens County, Oklahoma. The data are of interest because this type of reservoir is unusual in the mid-continent area. The reservoir is characterized by very steep dips and a relatively thick producing section. Its up-dip productive limit is defined by truncation of the productive sands, and the down-dip limit is defined by deterioration of sand quality rather than by the presence of an oil-water contact. The crude oil is of 29" API gravity, is relatively viscous and was saturated with dissolved gas at the original reservoir pressure. Consideratiqn of the physical characteristics of the reservoir indicates that natural water encroachment will be negligible, and that the producing mechanism will be a dissolved gas drive augmented by gravity drainage. Performance to date tends to confirm this. INTRODUCTION It is the purpose of this paper to present some of the features of the Dor-nick Hills - Springer sand reservoir which are unusual in mid-continent operations. The study was undertaken in an attempt to define the producing mechanism or mechanisms that will control reservoir performance, as an aid in determining well completion and production practices. GEOLOGY The reservoir under consideration is a series of sand bodies of Pennsylva-nian age found in the Lower Dornick Hills and/or Springer formations. For the purpose of this paper, the sand series is referred to as the Dornick Hills-Springer sand. This sand series lies on the northeast flank of the Velma anticline, and dips very sharply to the northeast in TWP 1S-5W, the average dip being about 45º. However, as shown in Fig. 1. the trend of the pool swings eastward in TWP 1S-4W with a coincident de- crease in dip angle. In this portion of the pool the average dip is about 25". Faults in Sections 30-1S-4W and 32-1S-4W are shown in Fig. 1. These faults show only minor displacements for the horizon contoured in Fig. 1, but they do show a pronounced displacement of the immediately overlying beds. Similar faults are thought to exist in TWP 1S-5W; however, since the detailed geological studies necessary to properly define these faults were not available to the author, no attempt to show them in Fig. 1 has been made. The up-dip productive limit throughout the pool is determined by the truncation of the Lower Dornick Hills-Springer sand. The down-dip productive limit does not appear to be defined by edge water, but by a gradual reduction in permeability of the sands. No dry hole has produced a significant volume of water from this sand section. There was a small gas cap in TWP 1S-5W. Most of the wells in TWP 1S-SW encountered an oil sand 70 ft to 150 ft thick, a shale 20 ft to 80 ft thick, and another oil sand 50 ft to 130 ft thick. A few scattered wells in this area encountered other and bodies below these

Jan 1, 1951

By W. R. Davis

This paper presents a sunimary of the results of a study of the Dornick Hills-Springer sand reservoir of the Velma Pool. Stephens County, Oklahoma. The data are of interest because this type of reservoir is unusual in the mid-continent area. The reservoir is characterized by very steep dips and a relatively thick producing section. Its up-dip productive limit is defined by truncation of the productive sands, and the down-dip limit is defined by deterioration of sand quality rather than by the presence of an oil-water contact. The crude oil is of 29" API gravity, is relatively viscous and was saturated with dissolved gas at the original reservoir pressure. Consideratiqn of the physical characteristics of the reservoir indicates that natural water encroachment will be negligible, and that the producing mechanism will be a dissolved gas drive augmented by gravity drainage. Performance to date tends to confirm this. INTRODUCTION It is the purpose of this paper to present some of the features of the Dor-nick Hills - Springer sand reservoir which are unusual in mid-continent operations. The study was undertaken in an attempt to define the producing mechanism or mechanisms that will control reservoir performance, as an aid in determining well completion and production practices. GEOLOGY The reservoir under consideration is a series of sand bodies of Pennsylva-nian age found in the Lower Dornick Hills and/or Springer formations. For the purpose of this paper, the sand series is referred to as the Dornick Hills-Springer sand. This sand series lies on the northeast flank of the Velma anticline, and dips very sharply to the northeast in TWP 1S-5W, the average dip being about 45º. However, as shown in Fig. 1. the trend of the pool swings eastward in TWP 1S-4W with a coincident de- crease in dip angle. In this portion of the pool the average dip is about 25". Faults in Sections 30-1S-4W and 32-1S-4W are shown in Fig. 1. These faults show only minor displacements for the horizon contoured in Fig. 1, but they do show a pronounced displacement of the immediately overlying beds. Similar faults are thought to exist in TWP 1S-5W; however, since the detailed geological studies necessary to properly define these faults were not available to the author, no attempt to show them in Fig. 1 has been made. The up-dip productive limit throughout the pool is determined by the truncation of the Lower Dornick Hills-Springer sand. The down-dip productive limit does not appear to be defined by edge water, but by a gradual reduction in permeability of the sands. No dry hole has produced a significant volume of water from this sand section. There was a small gas cap in TWP 1S-5W. Most of the wells in TWP 1S-SW encountered an oil sand 70 ft to 150 ft thick, a shale 20 ft to 80 ft thick, and another oil sand 50 ft to 130 ft thick. A few scattered wells in this area encountered other and bodies below these

Jan 1, 1951

By M. E. Wadsworth, R. D. Groves, B. W. Madsen

Experimental results obtained from large-scale (7 ton), long-term (500 days) leaching of low-tenor copper sulfide ores were interpreted by a geometric model involving the movement of a reaction zone through the ore fragments. The postulated leaching mechanism involved mixed kinetics and included diffusion of the reacting species through the host rock and a chemical reaction at the surface of the mineral particles. Ore properties which were considered were Ore particle size and shape, grade of ore, and mineral content. Excellent agreement between the mixed kinetic model and the laboratory leaching results was obtained when -1/2-in. ore particles were not included in the leach. Also, a satisfactory prediction of copper recovery from +1/2-in. ore with a different particle size distribution was made; however, it was necessary to modify the shape factor in the model. Prediction of copper recovery from an ore sample which included the -1/2-in. fine fraction and leaching for 460 days was 56.5%, and the recovery from leaching was 47.0%. The presence of fines caused solution channeling and a deficiency of oxygen which inhibited the leaching rate. Also, compaction of fines around coarser particles interfered with circulation around the ore particles, and bulk solution transport probably was a rate controlling factor.

Jan 1, 1976

By Arthur V. Corry

GOLD was discovered in Alder Gulch, Virginia. City, Mont., on May 26, 1863. In a short time some 6000 people flocked to the new discovery, and on the banks of Alder Gulch six settlements sprang into existence, the principal one, Virginia City, alone surviving. This town today has a population of 800, and is the county seat of Madison County. It is estimated that between forty and fifty million dollars in gold was produced up to 1904. Virginia City is situated at the mouth of Alder Creek where that stream leaves the narrow canyon that cuts the steep foothills flanking Old Baldy Mountain, elevation 9572 ft., 12 mi. south. Virginia City itself is 5700 ft. above sea level.

Jan 1, 1936

By P. de Vitry, Willis P. Mould

The wire saw is a tool not less than 60 years old, probably nearer 100 years old. It was developed in Europe and is reputed to have originated in Belgium. Frombold is said to be the original patentee. Wire sawing equipment, as indicated in Fig. I, is very simple. It consists of a three-strand wire cable, usually pis or 1/4 in. in diameter, or a single flat ribbon of medium hard, tough, alloy steel twisted into a helix of those diameters, made to form an endless belt of any length up to several thousand feet. The wire is guided into the cut by sheaves mounted in slides on steel columns situated close to either end of the cut. The feed motion usually is controlled either by gravity or by hand-operated feed screws. The steel columns or "standards" range from 15 to 30 ft. in length. At the top is a swiveled arm supporting a sheave similar to the traveling sheave below. Immediately under the swivel-mounted sheave is a guy plate or collar with shackles attaching four chain or wire-rope guys with suitable tightening devices, or with two guys and two jack legs for supporting the standard vertically or at any desired anale. The usual drive is by a 10-hp. motor through a gear reducer, on which are Insti- two grooved sheaves, One of which is keyed and the other free running On the shaft. Tension is provided by a car running on a track in line with the driving sheave

Jan 1, 1948

By P. de Vitry, Willis P. Mould

The wire saw is a tool not less than 60 years old, probably nearer 100 years old. It was developed in Europe and is reputed to have originated in Belgium. Frombold is said to be the original patentee. Wire sawing equipment, as indicated in Fig. I, is very simple. It consists of a three-strand wire cable, usually pis or 1/4 in. in diameter, or a single flat ribbon of medium hard, tough, alloy steel twisted into a helix of those diameters, made to form an endless belt of any length up to several thousand feet. The wire is guided into the cut by sheaves mounted in slides on steel columns situated close to either end of the cut. The feed motion usually is controlled either by gravity or by hand-operated feed screws. The steel columns or "standards" range from 15 to 30 ft. in length. At the top is a swiveled arm supporting a sheave similar to the traveling sheave below. Immediately under the swivel-mounted sheave is a guy plate or collar with shackles attaching four chain or wire-rope guys with suitable tightening devices, or with two guys and two jack legs for supporting the standard vertically or at any desired anale. The usual drive is by a 10-hp. motor through a gear reducer, on which are Insti- two grooved sheaves, One of which is keyed and the other free running On the shaft. Tension is provided by a car running on a track in line with the driving sheave

Jan 1, 1948

Jan 1, 1900

By Benny Langston, Frank M. Stephens

Although little information is available concerning small-scale equipment for dust collection in laboratories, it is possible to adapt standard equipment for laboratory use. Dust from laboratory processes may be collected by cyclone separators, filters, electrostatic separators, scrubbers, and settling chambers. IN recent years much attention has been given to recovery, treatment, and disposal of dusts discharged into the atmosphere from operations of industry. considerable data has been accumulated on both operation and design of dust-collector equipment for commercial installations. On the other hand, there is almost no published data on design and construction of small-scale equipment to handle dust problems that arise in the ore-dressing laboratory. Dust-collection equipment such as multiclones, single-cyclones, scrubbers, chemical and mechanical filters, settling chambers, and electrostatic separators has proved its efficiency for collecting dust in industry. In the laboratory, however, the engineer is faced with the problem of collecting small quantities of dust, inexpensively, without diverting the major effort from the metallurgical problem to the problem of collecting dust produced by the process. For most applications standard dust-collection equipment is too large for use in the laboratory; however, for control of dust in large working areas it is often possible to use a standard dust collector, such as an air filter, with branch ducts to eliminate a health hazard. For example, the well-furnished sample-preparation room containing small jaw crushers, rolls, and pulverizers, in addition to the riffles and screens necessary for preparation of samples, presents a perennial source of dust. The authors' experience has shown that a combination system consisting of overhead branch ducts to the individual equipment and floor ducts with grills, where applicable, connected to a central dust collector effectively removes dust generated in preparation of samples. Fig. 1 is a sketch of a downdraft dust-collector for table installation. Similar systems can be built with floor grids. For portable equipment such as laboratory vibrating screens this type of installation with a steel grill to support the heavy load is reasonably efficient. Overhead branch ducts to individual crushing and grinding equipment, although efficient, must be carefully controlled by dampers to prevent excess loss or a change in the composition of the sample. Change in sample composition can result from excess velocity, which causes selective removal of constituents of low specific gravity. Fig. 2' shows the theoretical effect of terminal velocity on spherical particles of different specific gravities in air and water under action of gravity. Fig. 3 shows the effect of air velocity on composition of CaCO, coal mixtures. Although the entrainment of dust particles in a moving air stream is the basic mechanism by which all dust-collection equipment functions, usually intake velocity of the dust-collection system must be controlled to prevent loss of part of the sample. As an example of what may happen when excess velocities are used, a mixture of 50 pct coal and 50 pct limestone was crushed to —10 mesh and fed to a pulverizer equipped with an overhead dust-collection system. Fig. 4 shows the overhead dust-collection equipment used in this test. The pulverizer was set to give a product 95 pct —100 mesh in two stages. Velocity of air passing over the lip of the pulverizer was measured with an anemometer. After grinding, the finished product was analyzed to show the amount of calcium carbonate present. Fig. 3 shows graphically the increase in calcium carbonate as velocity through the dust-collection duct was increased. These data show that at a velocity of 1 ft per sec little if any of the coal was entrained by the overhead draft. At the maximum velocity, about 6.5 ft per sec, approximately 7 pct more coal was entrained than calcium carbonate. From an operating standpoint, this problem can be remedied easily by dampering the line to control velocity. The lowest velocity commensurate with satisfactory dust control should be used to prevent excess loss and, in some cases, selective dust loss. Collection of Dust in Laboratory Processes As in industry, the engineer desires to collect efficiently the dust produced by processes being investigated on a laboratory scale. However, in the collection of laboratory dusts he is faced with two additional problems: 1—The volumes of gas and the quantity of dust that must be recovered are small when compared with the capacity of standard dust-collector equipment, which must be scaled down in design except for collection of dust from large pilot-plant operations. 2—In addition, because of the variety of problems studied in the process laboratory, the engineer cannot design today a dust collector that will meet the conditions imposed by the processes of tomorrow. Sometimes, therefore, he must compromise collection efficiency to minimize the cost of fabrication and the amount of time diverted from the metallurgical to the dust-control problem. For collection of dust from laboratory processes a cyclone separator, filters, electrostatic separators, scrubbers, and settling chambers can usually be adapted for small-scale operations. The following

Jan 1, 1955

By S. R. Rao

Interaction of potassium amyl xanthate with pyrrhotite has been studied thermochemically. Heats of adsorption of xanthate on unactivated mineral and the mineral activated with cupric ions have been compared with heats of reactions between potassium amyl xanthate and ferrous and cupric salts. It is shown that xanthate is consumed by stoichiometric exchange with anions present at the mineral surface. The floatability of the unactivated mineral is poor since xanthate is precipitated in bulk without creating a hydrophobic surface on the mineral. At the activated mineral surface, xanthate is adsorbed in certain isolated patches (active spots) and thereby creates a hydrophobic surface. The hydrophobicity of the mineral is greatly improved by lowering the pH to 4.5.

Jan 1, 1972

By H. Tabachnick, N. Hedley

The extraction of gold and silver from ores with alkaline cyanide solutions is well known. Cyanide solutions are also good solvents for many base metal minerals, particularly most of the copper minerals. Leaver and Woolf,1 who determined the solubilities of copper minerals in 0.10 pct sodium cyanide solution, showed that malachite, cuprite, chalcocite, and bornite are readily soluble in cyanide; least soluble are chalcopyrite and chrysocolla. The Mining Chemicals Laboratory of American Cyanamid Co. has studied the possibilities of using cyanide solutions for leaching base metals. In this article the authors present the results of their experiments with cyanide leaching to reduce the copper content of a zinc concentrate from 0.050 pct to the desired specification of less than 0.02 pct. Zinc Ore Sample: The sample of commercial zinc ore used in this investigation to produce zinc concentrates was ball mill feed ranging from 1/2 in. to fines. The ore was crushed to —10 mesh and riffled into 600-g charges for zinc flotation. Analysis revealed 4.54 pct Zn and 0.005 pct Cu. Examined microscopically, the ore consisted essentially of cream-colored sphalerite and carbonate gangue. It contained a small amount of pyrite, partly tarnished. The only copper mineral identified was chalcopyrite, mostly smaller than 20µ, some of which occurred as attachments on sphalerite. Flotation Procedure: Batches of zinc concentrates were made as required according to the following general procedure. A 600-g charge of —10 mesh ore was ground for 4 min at 60 pct solids in a laboratory steel rod mill. Screen sizing showed it to be all —35 mesh with 42 pct —200 mesh. The pulp was transferred to a Fagergren laboratory flotation machine, diluted to 25 pct solids and conditioned for 5 min with 0.6 lb per ton CuSO4, . -5H2O. It was then conditioned with 0.10 lb per ton Sodium Aerofloat promoter and floated for 5 min with pine oil as frother and creosote as froth stiff-ener. The pH during flotation was 8.5. A typical analysis of zinc concentrate subjected to leaching is 44.41 pct Zn and 0.051 pct Cu. The ratio of concentration was close to 10 to 1. Leaching Procedure: Aero Brand cyanide, technical calcium cyanide analyzing 49.5 pet NaCN equivalent, was used for all cyanide leaching tests. For each test three rougher concentrates floated as described were combined (total weight close to 180 g) and the water content adjusted to 150 ml. The percent solids in the pulp was thus 55. After a weighed amount of cyanide flakes had been added, the pulp was agitated on rolls for a given period, then filtered and washed. Filtrate and washed concentrate were assayed for copper content. The procedure for ammonia leaching was similar to the cyanide process. A series of tests was run in which the effects of ammonia as a solvent for copper in the zinc rougher concentrate were investigated. In each test 180 g of zinc rougher concentrate was leached with 150 ml of ammonia solution. Various strengths of ammonia and times of leaching were investigated. The results are shown in Table I. It is apparent that ammonia was a poor solvent for copper in the zinc concentrate; 60 min of agitation with a relatively strong NH:, solution extracted only 2 pct of the copper. CYANIDE LEACHING TESTS Effect of Solution Strength: The solvent effects of 0.125, 0.187, and 0.250 pct NaCN equivalent solutions were compared for leaching periods of 15 min. Residue and filtrate were assayed for copper content. The copper content of the filtrate plus wash was calculated back to the original volume of cyanide solution (150 ml). The effects of cyanide strength are given in Table II, It will be noted that 15 min leaching with 0.25 pct NaCN equivalent solution extracted 74.6 pct of the copper in the zinc concentrate. The leached product assayed 0.013 pct Cu, appreciably below the required specification of 0.020 pct. Effect of Leaching Time: Portions of zinc concentrate were leached with 0.25 pct NaCN equivalent

Jan 1, 1961

By J. L. W. Birkinbine

INTRODUCTION. This paper is a discussion of a part of the mineral wealth of the States of Oaxaca and Puebla, Mexico. It does not refer to the precious metals, some miles of which, in these States, are said to have been worked before the advent of the Spanish conquistadores in the sixteenth century, as my purpose is to invite attention to the exploration of deposits of coal and iron-ores in the Mixteca region. The prominence given to coal is warranted by the great effect of the scarcity of fuel upon the industrial development of Mexico. Under the progressive administration of President Porfirio Diaz, the Republic has made wonderful advances in the past three decades; and this progress would have been greater but for the limitations imposed by expensive fuel. In the spring of 1906 I was detailed by the Birkinbine Engineering Offices, of Philadelphia, to accompany A. B. Adams, of New York, in a reconnoissance of reported deposits of iron-ores in the State of Oaxaca. The result of this expedition was the formation, in 1907, of the Oaxaca Iron & Coal Co., of which Mr. Adams became, and has remained, President and General Manager, and I have spent the past three years as Chief Engineer of this company in Mexico, principally in western Oaxaca, where field-headquarters were established. GEOGRAPHY AND POPULATION. Although the geographical anti topographical, features of the Republic of Mexico are well known, few realize that the majority. of its population is domiciled in the States which immediately surround the capital city of Mexico, including the Federal District, Mexico, Tlaxcala, Morelos, Puebla,

Sep 1, 1910

By E. P. Valby

A method is presented in which the hydrocarbon weight fractional analyses of the well effluents from a true gas-tip-portion well and a true dark-oil-ring well furnish the basic data for determining the properties of any mixture of production from the two sources. The effect of injected gas on these properties can be computed. Comparison of similar properties of a given well effluent to the properties of mixtures of the basic well effluents will give the relative amounts of production from the two sources and injected gas. Presentation of Problem Oil fields having an area of gas-cap, or light-oil production, over the dark-oil area present a problem of increasing gas-oil ratios during the production of an oil well. The use of pressure maintenance in a field such as above, or a cycling project, wherein residue gas from an absorption plant is injected into the reservoir, adds to the problem, because a part of the increased gas-oil ratio may be due to the production of injected gas. The usefulness of a means to determine the amount of injected gas in a well effluent led to the development of a method in which well-effluent analyses of a true gas-cap-portion well and a true dark-oil-ring well furnish the basic data needed to determine whether injected gas of a known composition is present in a given well effluent. Development op Method The method presented herein is based upon the principle that if two fluids, or well effluents, having different properties are mixed in known proportions by weight, • the properties of their mixtures can be computed. Conversely, if these basic data are known, the properties of a mixed well effauent can be used to compute the relative amounts of each type of well effluent in the mixture. A convenient way of making these computations is to have the fractional analyses of the base well effluents and mixtures expressed in weight fractions The mathematical equations expressing the properties of mixtures will be developed for a two-component system consisting of the well effluents from the dark-oil ring and the gas-cap area. The added effect of injected gas, a third component, will also be developed. The following assumptions have been made in developing the method: 1. The gas-cap and dark-oil fluids exist initially in separate portions of the reservoir. 2. The fluids in each portion exist in a single phase at pressures above the saturation pressure for the dark-oil fluid. 3. The composition of each fluid is substantially constant throughout its respective portion of the reservoir. 4. Changes in reservoir pressure and temperature will not change the composition of the fluid entering the well bore. 5. The injected gas displaces original gas-cap fluid 100 per cent. •• 6. AS the injected gas travels through a

Jan 1, 1945