Search Documents

By E. Ackerman, L. Y. Tu, S. C. Sun

The use of ultrasonics in forming emulsions is not new. As early as 1927 Wood and Loomis' reported preparation of emulsions with ultrasonics. In 1935 Rschevkin and Ostrawskyz described the use of great ultrasonic power in producing fine emulsions of various oils and paraffin in water. Recently Oyama and Tanakahmployed ultra-emulsification to increase the effectiveness of sodium ethyl xanthate in flotation of chalcopyrite and galena. An emulsion is a two-phase system consisting of two incompletely miscible liquids, the one being dispersed as finite droplets in the other. The dispersed liquid is known as the internal or discontinuous phase, and the surrounding liquid is termed the external or continuous phase. There are two types of emulsions; one is oil-in-water (O/W) and the other water-in-oil (W/O). The word oil refers to the liquid other than water. Circumstances exist in which the emulsion type is not clearly defined, and the internal and external phases both contain portions of the opposite phase. This is said to be a dual emulsion. Among the many hypotheses', 6v proposed for the formation of emulsions, the Bancroft's adsorbed film or double interfacial tension theory is widely accepted. Bancroft ""educed that in the process of emulsification the interfacial tension between oil and water is lowered by the formation of an emulsifying film, which contains the adsorbed molecules and/or ions from the emulsifying agent and the two liquids.

Jul 1, 1955

By Raymond Ladoo

THE milling of talc, as is the case of many non-metallic minerals, until recently, has not received adequate technical consideration, for the talc industry has become of importance only within the last decade. At first, talc was used only in the massive form, for foot warmers, griddles, and so on, and milling methods were unnecessary. As the demand for ground talc increased, producers adopted the machinery used in the milling of flour; in fact, many talc mills were rebuilt flour mills. Improvement has been slow, but today several types of grinding and separating machinery are in use; many of them, however, are still inadequate and inefficient. To determine the best methods of milling talc, it is necessary to understand the essential properties a talc must possess to fit it for a particular use. For toilet purposes, whiteness, freedom from lime and grit, fineness of grain, and good "slip" are essential. As a paper filler or coating, the talc must be white, have a good slip, be free from grit and iron, uniform, and fine grained; freedom from lime is a disputed point. Fibrous talc is supposed to be superior to massive on account of the interlocking of grains in the paper, thus increasing its strength; this point, though, is in doubt. In general, talc for the paper industry need not be of as high quality or as fine grained as that used for toilet purposes. Talc is usually bought by sample, for which reason it is difficult to state the essential properties for use in paint, rubber, roofing, and so on. The adoption of standard screen tests and standard grades by producers is necessary before an accurate basis for manufacturing or selling standards can be established. Off-color tales might be utilized, as in Germany and-Austria, by the establishment of standard grades of colored tales.

Jan 1, 1921

By Robert Berggren

THE hot-milling process for reconditioning rock-drill bits is not new. It has been employed by a few mines for years and in the past decade it has been widely adopted, as its advantages have become better known. Because of the extensive commercial development in England and Canada of machines to operate on this principle, general acceptance has been largely in the British possessions and until recently has been chiefly in the field of conventional steel. In the past two years there has been a definite trend toward hot-milling of detachable bits in Canada, t but only in the past year has any considerable attempt been made to build special machines for this type of work. Generally a machine designed for con-ventional steel has been used and special holders employed to manipulate the bit. As early as 1934 at least one operator in the United States had adapted hot-milling to conventional steel with a substantial saving in resharpening costs. Several other operators have taken it up but there has been no widespread adoption of the method in this country by users of conventional steel. This may be partly explained by the fact that until recently no American manufacturer produced this equipment and operators have been obliged to build their own hot-millers or import them. Several years ago a few machines were built in Seattle, Wash-ington, and operated in some mines in the northwest, but, for reasons not generally known, the effort was abandoned.

Jan 1, 1940

By J. D. Miller, P. J. McDonough, H. Q. Portillo

Previous investigations have demonstrated the catalytic effect of silver additions in the ferric sulfate leaching of chalcopyrite [ ] The enhanced rate of leaching was found to be due to the formation of an intermediate Ag S film which forms on the Cures2 surface by an exchange reaction Under these conditions, unlike the uncatalysed ferric sulfate leach, the elemental sulfur forms a nonprotective reaction product on the Ag S crystallites As a result, the rate appears to become limited by an intermediate electrochemical reaction in {he Ag2S film rather than by transport through the elemental sulfur reaction product [ ] The reaction rate was found to have a complex dependence on the Ag+, Fe++ and Fe+3 concentrations, but independent of the Cu concentration Electrochemical measurements with a Ag,S-coated chalcopyrite electrode provide further information regarding the nature of the reaction mechanism The kinetics of the rate limiting, intermediate electrochemical reaction are analyzed in terms of the Butler-Volmer equation

Jan 1, 1981

By Heinrich Ries

In another place,* the writer has called attention to the modern methods of the laboratory investigation of clay, and it is desired here simply to discuss one branch of the subject, which, though of considerable importance, has heretofore received little attention in this country, viz., the rational analysis of clay. In order, however, the better to point out the bearings and advantages of this procedure, it is necessary to refer briefly to the ultimate analysis as well. The remarks in this paper refer only to the use of clay for the manufacture of clay-products. Pure clay or kaolin-f is extremely refractory, possesses little plasticity, and usually shrinks aud warps considerably in burning. Even the smallest proportion of impurities changes these properties, so that the kaolin exhibits variations in shrinkage, plasticity, tensile strength, fusibility, and often color when burned. The majority of nearly pure kaolins consist of kaolinite (A1,O2 2SiO,, 2H20), undecomposed feldspar, and quartz. The kaolinite generally forms the finest particles of the clay and is known as the clay-substance, while the rest of the clay-particles are collectively spoken of as sand. In the ordinary or ultimate analysis, the substances generally determined are silica, alumina, ferric oxide, lime, magnesia, alkalies and water. An analysis of this type simply regards the clay as a mixture of elements or oxides, but gives no clue as to the actual condition in which these substances exist, i.e., whether as silicates, oxides or carbonates, etc., a point which it is of the highest importance to know; for the individual components of the clay influence its properties not only according

Jan 1, 1899

By N. Nakanishi, C. M. Wayman

The effect of small copper additions on the mar-tensitic transformation behavior in Au-47.5 at. pct Cd was studied by measuring electrical resistivity as a function of temperature. The transformation behavior was found to change and transformation start (M,) temperatures for both the ß to ß' and ß to ß' transformations were depressed substantially by the addition of small amounts of copper. Both M, temperatures were lowered approximately 70°C per at. pct Cu. Copper also had the effect of narrowing the transformation hysteresis region (resistivity us temperature), and for the alloy Au-47.5 Cd-1.5 Cu there was little or no hysteresis; in this alloy, the reverse transfmmation upon heating apparently occurs below the thermodynamic equilibrium temperature, To. THE ß phase in the Au-Cd system occurs at the electron/atom ratio 3/2, and is similar to other ß phases in alloys based on copper, silver, or gold. It is of the CsCl type, in which a considerable degree of long-range order persists to the melting temperature.' The phase boundaries of the ß phase are not known precisely below 300° C, but at room tem- perature the phase exists from approximately 46 to 52* at. pct Cd.2 At low temperatures, the ß phase transforms in a diffusionless (martensitic) manner. Alloys having a composition near 47.5 pct Cd transform upon slow cooling to an orthorhombic3 phase, ß', at - 60°C. Alloys having a composition near 49.0 pct Cd, transform at - 30°C into a phase, ß", which has been recently identified as trigonal.4 Alloys having compositions near 48.5 pct Cd will transform into both the 0' and 0" phases over a range of temperatures. The progress of transformations can be observed

Jan 1, 1963

By Robert F. Winkle

A detailed breakdown of mining costs, available to management on monthly and year-to-date bases, is mandatory for a controlled and efficient mining operation. A simple lump sum reporting of costs may indicate a profit or loss differential, but it does not allow an effective search for areas of possible cost reduction. Moreover, functional reporting is necessary on a timely basis so as to note trends of increasing costs In specific areas, which in turn allow possible preventive action by management. Definitive cost information helps to eliminate the tendency to overlook areas where cost Improvements can be made. A good cost control system points out salient operational weaknesses by: ( 1 ) allowing comparison of functional costs with similar costs of other mines and (2) pinpointing sudden increases over unit empirical costs within the organization. In general, the cost accounting structure is relatively uniform within large open pit mines, but surprisingly some systems will overlook the need for detailed breakout in comparatively high cost areas. In some other systems, unrelated costs will be lumped together, preventing careful analysis of cost accrual.

Jan 1, 1979

By R. R. Sayers

VENTILATION may be defined as the process by which vitiated air of an inclosed or partly inclosed space is continuously replaced by fresh air. Fresh air has been defined as invigorating pure air. Pure dry air at sea level contains the following gases:1 Analysis of Air at Sea Level PER CENT. Oxygen 20.94 Nitrogen 78.09 Carbon dioxide 0.03 Argon 0.94 Helium, krypton, neon, xenon, hydrogen, hydrogen peroxid, ammonia, ozone traces CARBON DIOXIDE LIMIT For many years carbon dioxide was used as an index of the purity of the air vitiated by the metabolism of people. It was, however, well known that the untoward effects produced on those exposed to such air was not due to the concentration of the carbon dioxide. It has been found that the untoward effects on the comfort and efficiency of those so exposed are due to the increased temperature and humidity. It has been found that men can breathe air containing many times the amount of carbon dioxide found in our worst ventilated theaters and assembly halls, which, according to Rosenau, do not contain above 0.5 per cent. carbon dioxide.

Jan 7, 1926

By Donald R. Williamson, Edward R. Mueller

Cyprus Pima Mining Co.'s open pit operation was started in 1957 with the normal assumption that the ore reserve estimate was accurate within an acceptable range of values. Over the years, a number of attempts have been made to refine and polish the ore reserve figures using a variety of established standard procedures. None of these attempts have produced results which are totally satisfactory, particularly when comparisons are made between ore reserve estimates and short to medium range production figures. Statistical studies of operations data revealed relationships which could be used to subdivide ore blocks in much the same way as they are actually mined. Comparisons between these newly developed ore blocks and production data show that the new method of evaluation yields excellent results.

Jan 1, 1978

By George J. Bancroft

AT the New York meeting of the Institute, April, 1907, I presented a paper entitled, The Formation and Enrichment of Ore-Bearing Veins,1 in which paper I advanced the following propositions (1) That the majority of mineralized veins are the product of expiring vulcanism ; (2) that most of these veins were primarily mineralized by comparatively rich solutions in comparatively short periods of time; (3) that the solutions gained their metal-values from a comparatively rich source; (4) that there is a barysphere containing large amounts of the useful metals; (5) that eruptions spring from various depths and bring various kinds of magmas towards the surface; and (6) that only those eruptions which disturb the barysphere and bring a magma rich in metals sufficiently near the surface to be leached by vein-making solutions are productive of valuable ore-deposits, other eruptions producing barren veins. Ore-deposits due to magmatic segregation were not included in this general survey. As a result of considerable further study I have modified my views in some respects, while in others I feel more sure than ever of the ground taken at that time. That ore-bodies are infrequent occurrences and born of extraordinary conditions I think is now generally accepted. The theory that persisted for a time-namely, that ore-bodies were formed by the ordinary ground-water, which consists of extremely dilute solutions, derived from leaching extremely lean surface-rocks, and which must occupy enormously long periods of time in concentrating the values so leached, is, I think, now pretty generally regarded as not applicable to the great majority

Jan 1, 1913

By Y. Wang, M. M. Singh, H. L. Hartman

Knowledge of the state of stress at the bottom of a drillhole is of practical importance in rock drilling, since the induced stresses must exceed the strength of the rock in order to cause fracture. This note reports on a numerical method to determine the stress distribution at the bottom of a borehole induced by a static bit load and overburden and fluid pressures. The procedure adopted is similar to that for the plane-strain, discrete model employed by Harper and Ang.1,2 The rock medium is considered to be homogeneous, isotropic, and elastic-perfectly-plastic. METHOD OF ANALYSIS AND PROGRAMMING The discrete model adopted consists of two types of points: mass points and stress points. The configuration and numbering notation are depicted in

Jan 1, 1967

By Frederick Crabtree

WHEN Professor Stock asked for a paper on the above subject, it was too late to prepare by June 1, or near that time, one that would involve any appreciable amount of experimental work or original research; but the suggestion was made that a review of the literature bearing on the subject might be submitted in good time, and that later this could be supplemented by any experimental data obtained during the summer, if experiments were carried out. In accordance with this suggestion, there are submitted the following notes on references found in the literature of recent years bearing on sulfur in gas. It is to be, understood that, ill general, these notes express the opinions of the authors whose papers are abstracted, not necessarily the opinions of the abstractors. Very little published information was found bearing directly on producer-gas sulfur, so this has been supplemented, in certain phases of the subject, by references to illuminating gas. Methods of analysis and processes for the elimination of sulfur from the gas are, without much doubt, very closely related in these two products. As in illuminating gas, sulfur is found in producer gas mainly as hydrogen sulfide, mixed with a much smaller and variable quantity of carbon bisulfide.1 The presence of minute quantities of other organic-sulfur compounds has been intimated, but no definite statement is made concerning these. The amount of sulfur present in producer gas is variable and depends on several conditions. The primary factor is the quantity of sulfur in the fuel, but the form in which the sulfur exists, the temperature of the producer, the air-steam ratio, and the efficiency of the scrubbing process are all determining factors. When the coal used contains less than 0.5 per cent. of sulfur, the sulfur in the gas will not exceed the quantity found in the average illuminating gas.2 Sulfur in producer gas may safely

Jan 9, 1919

By C. K. Leith

THE questions as to what grades of ore it pays to conserve for the future, and the valuation of low-grade reserves, are becoming immediate and definite as applied to individual ore deposits, and seem to call for some sort of quantitative answer. Both opinion and practice involving these questions differ widely. The number of variables in this problem is so large that final solution will perhaps never be agreed upon, yet there seem to me to be certain controlling factors which can be placed in quantitative relation and serve to reduce the number of variables which it is necessary to consider in a given instance. I assume that it will not pay either for the individual or for the State to conserve any ore when the present cost of conservation (by stock piling or otherwise), when compounded at 6 per cent. interest for the number of years which would elapse before this ore is used, will exceed the profit which the ore will yield when it is used. It may be urged that any loss to the individual may be made up in gain to the State. This might be true if there was any definite limit to the amount of iron ore, but when we remember that iron makes up .4 per cent. of all the rocks of the earth and the amount of rock carrying iron in excess of 20 per cent. is for practical purposes, unlimited, it is apparent that posterity is assured of its iron ore. The changes will be mainly in methods and cost of extracting the ore. Therefore, any expenditure of money or effort now, which when compounded will exceed the worth of the effort or money needed in the future to utilize the iron, is a net loss both to the individual and to the community.

Jan 2, 1914

By J. Gordon Parr, L. P. Srivastava

DUWEZ1 has shown that pure titanium and pure zirconium transform martensitically during rapid cooling at temperatures about 30° and 15°C re spectively below their To temperatures. Holden et al.2 determined M, temperatures of Ti-Cu alloys by a metallographic technique applied to isothermally treated samples. Their results, superposed on the McQuillan3 version of the partial Ti-Cu diagram are shown in Fig. 1. Sources of metals were: Titanium: Iodide bar; Foote Mineral Co. Ltd. Zirconium: Iodide bar; Foote Mineral Co. LM. Copper: Spectrographic Standard; Johnson Matthey and Co. Ltd. Alloys were prepared by levitation melting under argon to the following nominal compositions:* 0.5, Quenching, at rates to about 8000°C per sec, was performed by cooling in a stream of helium (99.999 pct pure) a 3/64 in. cube of material previously heated by a tungsten coil in a system operating at. 10-5 mm Hg. Cooling rates below 200°C per sec w were obtained by controlling the current to the heater coil. The specimen was supported on a 32 gage Pt, Pt-Rh thermocouple attached through a DC amplifier to an Edin magnetic oscillograph (Model 8082) with a maximum chart speed of 250 mm per sec. Transformation temperatures were read off the oscillograph charts at the location of the beginning of the thermal arrest. The same specimen was quenched several times, and all runs were repeated on new samples. Regular calibrations of the oscillograph against a potentiometer were made between quenching experiments. The criterion of martensite formation was the effect of surface rumpling. Previously polished samples that showed a rumpled surface after transformation are assumed to have undergone martens itic transformation: transformations of a diffusion type produce no surface disturbance, Figs. 2 and 3. Electrochemical measurements were made in a cell described elsewhere4 whose electrodes were the martensitic and the diffusion-transformed materials in the following electrolytes:

Jan 1, 1962

By H. F. McCullough

MECHANICAL loading and conveying equipment has been available for the coal-mining industry for more than twenty years. The earlier equip-ment-was admittedly crude and ill-fitted to perform its intended functions, but there are available today a variety of mechanical loaders and conveyors which may be said to be almost on a par with coal-cutting machines. Despite the fact that such equipment is available and that better and other types of equipment are continually being developed, mechanical loading of coal cannot yet be said to be economically successful, except in a few special cases. It is not an accomplished fact in the sense that machine cutting of coal and electric haulage are accomplished facts and a part of accepted practice. There are two general opinions why we have failed to obtain better results with mechanical loading and con-veying equipment. The equipment manufacturers will say that coal-mine operators have generally failed to establish and maintain the conditions required for suc-cess. The coal-mine operator says that the equipment is not adapted to cope with his specific conditions to the extent required for economically successful results. Just what is the objective of this movement toward mechanical loading? We speak of mechanical loading in such a way as to lead one to believe that we are mere-ly seeking a mechanical equivalent of the human loader and his shovel. Really, we are impressed with the fact that the coal-mining industry has not advanced toward greater productive efficiency to anything like the degree achieved by practically all of the other productive in-dustries, and we are seeking the means to remedy this. We have seen the advantages which follow the intro-duction of coal-cutters and electric haulage-locomotives. The loading of coal is the one major operation in coal mining which has not been mechanized. We believe that a satisfactory, mechanical substitute for the man with the shovel will help us increase our productive efficiency to the same degree as has been accomplished in the other productive industries.

Jan 3, 1927

By J. Wes Blakely

In the mid-1950s the importation of foreign oil began to encroach on traditional coal markets such as railroad steam engine fuel, home heating, electrical generating plants, and others. Many of the smaller coal companies with substantial coal reserves subsequently found that they could no longer continue to mine economically and merged in various ways with larger established coal mining concerns. As the seats of top management and authority were removed from the mines to large metro centers such as New York, Pittsburgh, and Chicago, the more personal relationship between mine workers and management that had existed prior to these mergers began to be eroded and replaced by 'remote control mine management. The disappearance of this face-to-face contact of upper management with mine employees tended to create barriers blocking simple effective communications between coal mine management and labor. In examining the human relations aspects of the coal mining industry, many elements, some concerned with work and others not, have depicted the industry as almost devoid of good applied human relations and communications practices, and, in truth, little has been done to alleviate this situation . In past years many coal producing companies, with the exception of one of the largest, failed to adequately define the term “communications” as it applied to their companies, whether internally or externally. Internally many still place heavy reliance on written communications such as company-wide newspapers to do the job of communicating with their employees which they feel ought to be done. One company puts an inordinate belief in its company "newspaper" as the primary instrument to stimulate its work force into increasing productivity. Primarily aimed at the workers, who greatly outnumber the salaried administrative people, this publication mainly documents the fortunes of individual mine workers who are felt to have achieved something with their lives, e.g., a mine worker who had managed to put four children through universities, the

Jan 1, 1981

By Eugene A. Smith

Geological Relations. In his second report upon the Geology of Alabama, Prof. M. Tuomey calls attention to a rock occurring near Florence, in the Tennessee valley, the composition of which is as follows: Per cent. Carbonate of lime,.. .. .. ..16.41 Phosphate of lime,.. .. .. ..14.19 Peroxide of iron,.. .. .. .. .36 Quartz and other insoluble matters,. .. ..68.72 99.68 This rock was referred by Prof. Tuomey to the Carboniferous, because he found the Carboniferous limestones always resting conformably upon it, whilst both rest uncomformably upon the underlying Silurian or Devonian rocks. The recent discovery in Tennessee of phosphate-rock of this age (or approximately so) has stimulated the search in Alabama for similar rich material; but our search has been, up to this time, unrewarded by the finding in quantity of anything of better quality than the rock whose analysis is given above. It is, however, in high degree probable .that the rich phosphaterock of Tennessee will at some time be found to have its counterpart in Alabama. Materials of several kinds, containing a notable quantity of phosphoric acid, have been found in Alabama in both the Cretaceous and the Tertiary formations, and for our present purpose they may be most conveniently considered in their geological relations.

Jan 1, 1896

By Claus Guenter Goetzeil

(New York Meeting, February, 1937) The object of this investigation was to determine whether silver alloys could be used instead of the currently employed insert of high-expansion Average Coefficient per Deg. C. over Range 20° to 200° C. Pure aluminum..................................... 24.6 X 10-6 Cast low-expansion Si-Cu-Ni-A1 piston alloy............ 20.0 X 10-6 High-expansion austenitic Cu-Ni cast iron.............. 19.3 X 10-6 Cast steel (0.25-0.35 C, 0.40-1.0 Mn).................. 12.6 X 10-6 Cast iron (3.15 total C, 2.16 Si)....................... 12.8 X 10-6 Pure silver.......................................... 18.9 X 10-6 austenitic ferronickel alloy, to reduce the wear of ring grooves in light metal pistons. A typical example of a piston containing a ferronickel insert is shown in Fig. 1. The high coefficient of expansion of silver made it worthy of consideration, while the small size of the insert would render its use feasible in Germany as an emergency measure. The coefficients of linear expansion of several metals and ailoys are as shown in the table above. Obviously the melting point of the insert must be high enough to prevent it from melting when the light alloy is cast around it. This imposes a lower limit of about 850" C. for the solidus of the silver alloy. Pure silver melts at about 961" C., so that the tolerable depression in the solidus is rather small. To avoid deformation of the insert during use a Brinell hardness number of at least 60 appears necessary.

Jan 1, 1937

By V. S. Rood, J. A. Norden

The general system of workings at the Utah-Apex is similar to that found in many of the western metalliferous mines. There is a vertical three-compartment shaft extcnding to the surface, from which the various levels have been driven to the orebodies. The 1000-ft. (305-m.) level, about 3/4 mile long, was driven as a haulage and drain adit. Geology The formation is a flat north-dipping series of alternating limestone and quartzite beds. Extensive north-south faulting and fissuring have taken place, resulting in the formation of large replacement orebodies in the crushed zones in the limestone. The orebodies are irregular in shape and size, but follow closely the trend of the mineralizing fissures. The ore consists of galena, pyrite, sphalerite and small values in silver and gold. Large masses of non-commercial pyrite are frequently found in or adjacent to the orebodies, and more or less pyrite is found for some distance in the walls of the orebodies. Lenticular bodies of a black pyritic shale also occur in the zones where extensive faulting has taken place. Mining Methods and Condition of Workings Geological conditions, mentioned before, have made the ground extremely heavy. In mining above the 1000-ft. level, square-set and filling methods were used, but not altogether successfully. The crushing of timbers extended even into the filled portions of the stopes. The filling material itself, consisting of limestone, shale, and pyrite, possessed swelling qualities which added to the difficulty of maintaining

Jan 1, 1920

By Carl Scholz

During November and December, 1907, four serious mine-explosions occurred in the Appalachian coal-field, which resulted in the loss of nearly a thousand lives and caused an eliormous damage to propcrty. These accidents attracted more than the usual attention; coal-trade and engineering papers contained many comments and suggestions on the cause and prevention of accidents; the daily press in many instances condemned the coal-operators and charged these accidents to their negligence, or their anxiety to make money without adopting precautionary measures. Immediately after cach accident the respective State authorities ordered close investigations to be made, with the view of establishing the cause and suggesting remedies to prevent recurrence. Representatives of the Technologic Branch of the IT. S. Geological Survey, to whom the investigation of mine-accidents had recently been delegated by the Secretary of the Interior, visited the mines and co-operated with the local authorities in their determinations. It may be safe to say here that an investigation of a mine after an explosion has occurred discloses but little, because the causes hare been removed and conditions have been entirely changed. On Jan. 8, 1908, the coal-operators of West Virginia organized an association at qTashington for the purpose of making extensive investigations, and sufficient funds were pledged to carry out this work. At this organization meeting, the representatives of the Geological Survey present had no suggestions to offer as to the cause of these accidents. An examinatiou of the various reports concerning these accidents indicates that the explosions were caused by the ignition of gas or dust; they show the point of origin and the direction in which the force was expended, and give a detailed description of the damage done. Very little has bee11 said as to what

Jan 1, 1909