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By R. G. Wheeler, J. W. Goffard

The Larson-Miller parameter was used to correlate time, temperature, and indentation creep of magnesium, aluminum, and some of their alloys. In the temperature range 300" to 450°C, the short-time Meyer hardness of pure magnesium was less than that of the magnesium alloys tested, but for long times the pure magnesium has greater indentation creep resistance. Aluminum (1100 alloy) had 1.5 to 2.5 times more indentation creep resistance than magnesium at 300" and 450oC, respectively. Hardening of aluminum with a dispersion of Al2O3 was effective in the time and temperature ranges studied. New technologies have required the development of new materials and the utilization of the more familiar materials for new and unusual applications. The use of magnesium and aluminum and some of their alloys, because of their desirable nuclear characteristics, light weight, low cost, and ready availability, has been extended to the 300" to 450°C temperature range. In this temperature range the basic consideration of these materials must be their rate of plastic flow rather than offset yield strengths. The indentation testing reported here arose from a need for design data for the load-holding ability of supports made of these materials. Test Procedure—Hardness indents were made with a 0.275-in.-diam quartz indentor and a 10.65-lb load. The indentor was made by fire-polishing a spherical surface on the end of a fused quartz rod. The samples were held at temperature in a graphite crucible controlled to ±2°C. A thermocouple was attached to the sample and test temperatures were recorded. The diameter of the spherical indentation was measured at the end of a test period and the compression stress (Meyer Hardness) was determined by: H___________load__________ m = projected area of indent Samples were 1 in. in diam and at least 1/4 in. thick. It was observed that at the higher temperatures and longer times, the quartz indentor would stick to the magnesium sample. The quartz indentor was, therefore, frequently inspected and fire-polishing repeated when necessary. The area of sticking was always a small fraction of the area of indent and was therefore considered to have an insignificant effect on results. Correlation of Hot-Indentation Test Data with Time-Temperature Parameter—Sherby and Dorn' have correlated creep or tensile data of a' solid solutions of aluminum with a temperature and strain-rate parameter suggested by Zener and Holloman. underwood2 used this parameter to correlate creep properties of some steels with hot hardness, and upon the basis of this correlation a means of obtaining creep properties from short-time (and inexpensive) hot hardness tests has been demonstrated. Since the validity of the correlation of creep properties with a time-temperature parameter and the correlation of creep properties with hot hardness have been shown, it follows that hot hardness may correlate with the time-temperature parameter. The hot-indentation data obtained was expressed as Meyer hardness, and was shown to be time and temperature dependent. Correlation of Meyer hardness, time, and temperature with the parameter was made using the relationship: Hm = Meyer hardness t = time, hours T = absolute temperature, OK K = constant A value for the constant K was calculated by equating In l/t + K/T at different temperatures and times but at the same hardness. The correlation was tested by plotting Hm vs the parameter, In 1/t +K/T. Since materials are being sought which have high hardness at low indentation creep, i.e., a high Meyer hardness for long time at high temperatures, low values of the parameter are ofthe most interest. TEST RESULTS Magnesium—Pure magnesium (99.98 pct) cut from extruded rod was indentation tested perpendicular to the rod axis at temperatures of 300°, 350°, 400°, and 450°C for times ranging from 6 sec to 112 hr. Fig. 1 shows the time dependency of Meyer hardness at the four constant temperatures. Fig. 2 shows the correlation of the Meyer hardness of pure magnesium with the time-temperature parameter using a K of 22,720 in Eq. [I]. At the bottom of Fig. 2, the effect of doubling the time of indentation t2 = 2(t1), on the abscissa for any time is shown graphically. This effect is of constant magnitude. Also shown graphically are the magnitudes of the effects on the

Jan 1, 1960

By A. H. Hand

When considering the question of future demand for crude petroleum in California, one must first decide whether it is to be approached in the light of the definition of "demand" when used in economics; i.e., "The quantity of any commodity required or sought in the market," or in the light of markets developed to dispose of total supply. Therefore, is the California demand of future years to be predicated on a continuation of supplying markets developed following the surplus production commencing in 1922, or predicated on supplying what would be termed economic markets ? If the latter, what are economic markets ? Obviously, the Pacific Coast States and Canada, Alaska, Hawaii and probably the Pacific side of Central and South America, can be considered as normal markets for California petroleum products. While there have been small quantities of gasoline shipped into the PacSc Coast from East Texas, transportation costs, plus import taxes in the case of foreign oil, are a sufficient barrier to justify considering that these markets will be retained. But how about our participation in Atlantic and Pacific foreign and intercoastal markets? During the five years preceding 1931 California shipped substantial quantities of gasoline to the United Kingdom and to France, Germany and Italy. During recent years our business in European markets has been restricted to occasional shipments of gasoline and Kettleman crude. This loss of business is occasioned by the development of production in the Mid-Continent, principally East Texas, and in Iraq, Rumania, Venezuela and other closer producing areas, which makes it impossible at the prevailing crude-oil prices for California to be competitive in supplying any substantial portion of these markets. It is therefore apparent that under a stabilized price structure that will return the California producer a reasonable price for his oil, future Atlantic foreign -business will be restricted to occasional spot cargo sales. As to Pacific foreign shipments which, in addition to Central and South America, consist principally of shipments to Japan, China, Australia and New Zealand: A considerable portion of the business we had with Australia and New Zealand until four or five years ago is now being

Jan 1, 1937

By Gen-Hua Shi

The deformation of a discontinuous rock is a sum of individual translations, rotations, and strains of the component blocks. These produce opening and slip between blocks along the discontinuities. Rather than attempting to analyze such deformations with a mathematical model representing the geometric and stress/strain properties of all points, for the back-calculation of observed displacements we have produced a novel approach to solve the inverse problem. Using a field of displacement measurements and a map of the system of discontinuities, the method, determines the intrablock and interblock motions by a least squares formulation. In this brief paper we address only two- dimensional formulations. However, computer codes have also been developed for three dimensional problems.

Jan 1, 1984

By O. W. Walvoord

A Definition: An ore feeder is a mechanical device that, by virtue of its motion, causes ore to be supplied or carried forward at a desired metered rate to other milling equipment. From the viewpoint of economics there can be little question, even for small tonnage operations, as to the advisability of using mechanical feeders in the place of manual labor. Only a few short years ago, it was common practice to employ crusher men for the feeding of crushers, thus eliminating the capital expenditures required for mechanical feeding equipment. Having been a crusher man in several instances, the author does not favor such practice. The high cost of labor today eliminates the crusher man, and feeders become an economical capital expenditure when considered against the importance of obtaining maximum production efficiency from all the machines in a process flowsheet.

Jan 2, 1955

By R. A. David, D. J. Vink, D. L. Katz

A phase diagram showing boundary curve and quantity of liquid in the two-phase region was determined for a mixture of natural gas and natural gasoline in the region of its critical conditions. The temperatures and pressures of phase measurements were in the range of 85 to 212 F. and 1300 to 2600 Ib. per sq. in., respectively, with the critical conditions at 169.5 F. and 2615 Ib. per sq. in. abs. Color phenomena were observed in the region of the boundary curve from 102' to 192 F. Approximate densities of the single-phase and two-phase regions and analysis of the system are included. Boundary curves between the single-phase and the two-phase regions have been determined for several binary mixtures containing hydrocarbons. 2,3,4.6,7,10,11,12,14 These investigators did not report the relative amounts of liquid and vapor within the two-phase region. The equilibrium values obtained from the dew-point and bubble-point data can be used to compute the lines showing percentage of liquid on the pressure-temperature phase diagram8 but the positions of the lines near the critical temperature and pressure are uncertain. Relative amounts of vapor and liquid were obtained for a gasoline and a naphtha1 within the two-phase area but not in the region of the critical temperature and pressure. The bubble-point and dew-point lines, as well as the percentage liquid lines within the two-phase region, were determined by visual observations in glass apparatus. Apparatus An arrangement of the apparatus is given in Fig. 1, showing the Jerguson gauge A with glass windows B. Pressure was supplied by the

Jan 1, 1940

By R. A. David, D. L. Katz, D. J. Vink

A phase diagram showing boundary curve and quantity of liquid in the two-phase region was determined for a mixture of natural gas and natural gasoline in the region of its critical conditions. The temperatures and pressures of phase measurements were in the range of 85 to 212 F. and 1300 to 2600 Ib. per sq. in., respectively, with the critical conditions at 169.5 F. and 2615 Ib. per sq. in. abs. Color phenomena were observed in the region of the boundary curve from 102' to 192 F. Approximate densities of the single-phase and two-phase regions and analysis of the system are included. Boundary curves between the single-phase and the two-phase regions have been determined for several binary mixtures containing hydrocarbons. 2,3,4.6,7,10,11,12,14 These investigators did not report the relative amounts of liquid and vapor within the two-phase region. The equilibrium values obtained from the dew-point and bubble-point data can be used to compute the lines showing percentage of liquid on the pressure-temperature phase diagram8 but the positions of the lines near the critical temperature and pressure are uncertain. Relative amounts of vapor and liquid were obtained for a gasoline and a naphtha1 within the two-phase area but not in the region of the critical temperature and pressure. The bubble-point and dew-point lines, as well as the percentage liquid lines within the two-phase region, were determined by visual observations in glass apparatus. Apparatus An arrangement of the apparatus is given in Fig. 1, showing the Jerguson gauge A with glass windows B. Pressure was supplied by the

Jan 1, 1940

By Donald L. Katz, Leo B. Bicher

A correlation is presented for predicting the viscosities of light paraffin hydrocarbon mixtures such as natural gases for temperatures from o° to 4o0°F. and for pressures fro1 atmospheric to I0,000 lb. per sq. in. The correlation is based on the viscosity data for the methane-propane system and requires only a knowledge of the molecular weight of the naturaI gas. The viscosities of natural gases reported in the literature up to 2500 lb. were reproduced by the correlation with an average deviation of 5.8 per cent. Introduction The viscosity of a natural gas is required whenever calculations are made of the pressure drop that occurs while the gas flows through pipes or porous media. Methods of predicting the viscosities of gases at the present operating pressures are not available. This paper presents a simple method of predicting the viscosity of a natural gas in the single-phase region from its molecular weight, temperature, and pressure. Viscosity oF Methane-propane Mixtures The viscosity of methane, propane, and four of their binary mixtures, 20,40, 60, and 80 mol per cent, have been determined for pressures from 400 to 5000 lb. per sq. in. and temperatures from 77" to 437 F., with an experimental accuracy of 3.2 per cent.2 The apparatus used in the investigation was a modification of that employed in previous studiesaJ4 on the viscosity of normal paraffin hydrocarbons. It consists of a viscosimeter of the rolling-ball, inclined-tube type,5>k7 with auxiliary equipment for making up and charging binary mixtures into the viscosimeter.~ The viscosity data on the methane-propane mixtures have been plotted as a function of molecular weight with lines of constant pressure, charts of constant temperature in Figs. I to 3. These charts are extrapolated at temperatures below 77°F. and at pressures above 5000 lb. per sq. inch. Prediction OF Viscosity from Molecular Weight of a NaturaI. Gas At atmospheric pressure the viscosity of light hydrocarbon gases increased with increased temperature, contrary to the change of viscosity of liquids with temperature. The atmospheric viscosities of the normal paraffin hydrocarbons have been determincd by several investiga-tors 3,4,9,10,12,15,16,17,19 and are plotted in Fig. 4 as a function of molecular weight, with extrapolation to 896'F. and to 220 molecular weight. Data for isopentane and normal pentane show less than 2 per cent difference in viscosity, indicating that Fig. 4 can be used for isomeric parafin hydrocarbons with an accuracy of approximately 2 per cent. Trautz and Sorg'7 determined the atmospheric viscosities 01 methane-propane mixtures and showed that they are proportional to the molecular weight. The viscosities of these mixtures

Jan 1, 1944

By Leo B. Bicher, Donald L. Katz

A correlation is presented for predicting the viscosities of light paraffin hydrocarbon mixtures such as natural gases for temperatures from o° to 4o0°F. and for pressures fro1 atmospheric to I0,000 lb. per sq. in. The correlation is based on the viscosity data for the methane-propane system and requires only a knowledge of the molecular weight of the naturaI gas. The viscosities of natural gases reported in the literature up to 2500 lb. were reproduced by the correlation with an average deviation of 5.8 per cent. Introduction The viscosity of a natural gas is required whenever calculations are made of the pressure drop that occurs while the gas flows through pipes or porous media. Methods of predicting the viscosities of gases at the present operating pressures are not available. This paper presents a simple method of predicting the viscosity of a natural gas in the single-phase region from its molecular weight, temperature, and pressure. Viscosity oF Methane-propane Mixtures The viscosity of methane, propane, and four of their binary mixtures, 20,40, 60, and 80 mol per cent, have been determined for pressures from 400 to 5000 lb. per sq. in. and temperatures from 77" to 437 F., with an experimental accuracy of 3.2 per cent.2 The apparatus used in the investigation was a modification of that employed in previous studiesaJ4 on the viscosity of normal paraffin hydrocarbons. It consists of a viscosimeter of the rolling-ball, inclined-tube type,5>k7 with auxiliary equipment for making up and charging binary mixtures into the viscosimeter.~ The viscosity data on the methane-propane mixtures have been plotted as a function of molecular weight with lines of constant pressure, charts of constant temperature in Figs. I to 3. These charts are extrapolated at temperatures below 77°F. and at pressures above 5000 lb. per sq. inch. Prediction OF Viscosity from Molecular Weight of a NaturaI. Gas At atmospheric pressure the viscosity of light hydrocarbon gases increased with increased temperature, contrary to the change of viscosity of liquids with temperature. The atmospheric viscosities of the normal paraffin hydrocarbons have been determincd by several investiga-tors 3,4,9,10,12,15,16,17,19 and are plotted in Fig. 4 as a function of molecular weight, with extrapolation to 896'F. and to 220 molecular weight. Data for isopentane and normal pentane show less than 2 per cent difference in viscosity, indicating that Fig. 4 can be used for isomeric parafin hydrocarbons with an accuracy of approximately 2 per cent. Trautz and Sorg'7 determined the atmospheric viscosities 01 methane-propane mixtures and showed that they are proportional to the molecular weight. The viscosities of these mixtures

Jan 1, 1944

By M. Gensamer

THE stresses which initiate deformation processes in metals are funda-mentally important in the study of the mechanical properties of metals. A point of inflection in the load-elongation curves obtained for single crystals1 has been rather too readily interpreted as a true yield point, and the critical resolved shearing stress on the plane of slip taken as a material constant. Even early work showed that the stress at this point varies with rate of loading, but it has not been generally appreciated that creep tests under static loads alone are suited for determining the existence or nonexistence of a yield point.2 It has now been shown by Miller that single crystals of zinc3 when loaded statically begin to yield at loads too small to measure; as a result there is no case now known, apart from that cited in the present paper, in which a true critical stress for yielding has been demonstrated for single crystals of metals. The case of iron has especial interest: the existence of an upper and lower yield point and of an elongation at the yield point in ordinary iron and steel marks this substance as unusual, though the effects have been found to a very minor degree in other metals and alloys. ? Most alloys do not show such marked phenomena when appreciable yielding begins, and accordingly modern practice is to speak of the yield strength of such materials, a stress read from the load-elongation curve after elongation has begun, rather than yield point. The special behavior of iron suggests that it is more likely that single crystals of iron should have a true yield point than other metals.

Jan 1, 1938

By Jack F. Havard, John S. Lagarias

When ore bodies are faulted or mill feed turns refractory, mining managers and engineers act vigorously to convert imminent failure into eventual success. The recent proliferation of onerous environmental regulations and restraints is likewise a threat to successful mining enterprise, in some ways more insidious and dangerous than the problems presented by natural obstacles. The regulatory burden has become so heavy that a pall of pessimism covers much of the mining industry. In this paper we frankly recommend an approach that does not just "make the best of it" but rather directs the whole environmental process: first, to improve planning, engineering, and operating procedures; and, second, to demonstrate the need for modification of laws and regulations which are intolerably burdensome to both the mining industry and the public.

Jan 1, 1979

By Robert H. Richards

My first paper, read at the Cobalt Meeting of the Institute,' July, 1907, dealt with the behavior of a small Wilfley table when collceiltrating galena from quartz, the table being fed with natural products, with sized products, and with classified products. Since galena, having a specific gravity of 7.5, is among the heaviest minerals ordinarily concentrated by Wilfley table, it was desirable that a similar set of tests upon a mineral of lighter weight should be made. Chalcopyrite, of a specific gravity of 4, would have been the best mineral for this purpose, on account of its great importance as an economic mineral, but in carrying out the test I was obliged to content myself with a cupriferous pyrite, the specific gravity of which was 4.68 and the content in copper 8.80 per cent. Through the kindness of H. 0. Cummins, this material was obtained from Shasta, Cal., in very pure, clean, homogeneous condition. It was broken by rolls to 2 mm. in size, taking care to make a minimum of slimes. The quartz used to mix with it was pure, white, New England quartz, broken in the same way to the same size. In studying the accompanying tables, it should be borne in mind that the material concentrated was of low copper-content, and in many cases the quantity fed to the machine was 1 kg. or less. As a consequence of the smallness of the quantity treated it was very difficult to adjust the table and get it in condition to do its best work before the feed became exhausted, and for this reason many results were obtained which appear irregular.

Jan 1, 1909

By Charles W. Eichrodt

So much has already been wimitten on this vast subject of ground movement and subsidence, and so many data collected and commented upon, that in this paper the author proposes to confine himself to the submission of some plans showing what has actually occurred in the mining of several of the orebodies which have come under his direction during the last 20 years or so at Rio Tinto, Spain. Some notes are added for the purpose of describing the plans. The author does not attempt to give his opinion as to the reasons why the subsidences have occurred in the manner in which they are found, but confines himself to giving as true a picture as possible of the movements that have taken place. Effects of Excavation on Ground Movement Broadly, the effects of excavations on the overhead or adjacent ground can be classified under three headings, as follows: 1. Ground movements due to excavations made from surface only, such as those made in opencasts where no excavations underlie them. The stability and strength of the ground to resist movement must determine the slopes. 2. Ground movements due to underground excavations only; i. e., where the surface is not removed. 3. Ground movements due to a combination of both; i. e., from excavations taking place from the surface for the purpose of stripping an orebody and recovery of the ore to a certain horizon combined with excavations being carried out below, at the same time, for the winning of the ore below the horizon at which mining by stripping or opencasting under the specific conditions is no longer economical. Nos. 1 and 2 represent independent and distinct problems and No. 3 is a combination, which presents results much more difficult of explanation. The accompanying plans and sections give examples of what has occurred under the three conditions. Unfortunately, the class of ground is not exactly the same in them all, but the difference is not greater than is generally encountered over districts of equal area. Excavations from Surface To illustrate No. 1 three cross-sections are shown, of excavations made for the stripping and excavation from three different orebodies

Jan 1, 1930

By Richard M. Foose

FIVE miles southwest of Mt. Holly Springs, Cumberland County, Pennsylvania, the Philadelphia Clay Co. has been mining and milling a white clay since 1896; for use in white cement, as a filler in rubber, pigment and paper, in the manufacture of insecticides, and for other minor purposes. Until late in 1942, when the mine was abandoned because of labor shortage, combined underground mining and surface stripping produced approximately 30,000 tons of clay a year, of which 10,000 tons were refined in the mill. GEOLOGY Lower Cambrian Antietam quartzite and the Montalto quartzite, stratigraphically older, trend N.55°E. and make a sharp 1600-ft. anticlinal ridge of the South Mountains. The Tomstown dolomite overlies the Antietam quartzite on the southeast flank of the anticline, which is displaced near its crest by a steeply dipping oblique fault. Erosion of the less resistant Tomstown formation has resulted in a narrow valley at an elevation of 700 ft. Directly on top of the Antietam quartzite and at the base of the Tomstown formation is a zone of sandy white clay, lenticular along the strike of the formations, ranging in thickness from 10 to 300 ft. within a mile. All of the formations dip steeply to the southeast, from 65° to vertical. The clay crops out at an elevation of about 1000 feet. ORIGIN AND CHARACTER The uppermost part of the Antietam formation is sericitic and schistose at many places, and at all these places weathering is in an advanced stage. The clay is the residual product of weathering of this sericitic quartzite or sandy schist. The crude clay has the physical aspect of a sandy kaolin, but there are large areas in the clay formation that are low in free silica, and commonly the 30 ft. adjacent to the Antietam quartzite is notably free of silica. The overlying Tomstown dolomite has been weathered almost completely to a mixed yellow and brown clay, which carries a zone of nodular and chunky limonite and manganese ore, 4 to 12 ft. thick, about l00 ft. from the contact with the white clay. In mining, this zone is an important "marker," indicating where the white clay may be expected in an advancing tunnel. The contact of the white clay formation with the yellow and brown clay of the Tomstown formation is relatively sharp, although the line of contact is irregular and therefore responsible for the lenticular character of the white clay formation. Following is an analysis of the refined clay containing less than one per cent of moisture when dried at 212°F.: Si02, 67.05 per cent; A1203, 22.27; Fe203, 0.40; CaO, 0.00; Ti02, 1.05; MgO, 0.52; Na20, 0.04; K20, 0.88; ignition loss, 7.65; total, 99.86.

Jan 1, 1944

By Thomas P. Meloy, Duane T. Eppler

The science of particle shape analysis has expanded rapidly in the decade since precise numerical-statistical techniques were developed for use in characterizing the shape of closed forms. Use of Fourier descriptors permits shape to be quantified to whatever degree of precision is required. With this technique, particles and particle systems can be compared either on the basis of shape characteristics displayed by individual particles, or on the basis of aggregate shape characteristics representative of large samples of particles. Shape characterization work completed to date has shown that the physical characteristics of particle systems (porosity, permeability, strength, mechanical stability, chemical reactivity, and flow characteristics (viscosity)) are related directly to particle shape. Furthermore, it has been shown that particle shape is a function of chemical composition, process of formation, and post-formational history of the particle. In this light, particle shape analysis has potential applicability to a host of engineering and industrial problems encountered in processing particulate material. It can be used to optimize the efficiency of separation processes and particle feed systems, to trace particle pathways through processing systems, and to monitor the operation of specific processes, the wear of critical machine parts, and the quality of end products in processing systems. In this paper we discuss these specific applications of shape characterization to particle processing.

Jan 1, 1980

By R. Schuhmann

As a response to rapidly growing specialization in various branches of metallurgy, it is proposed that undergraduate education in metallurgical engineering should be built up around four principal scientific themes: 1—thermodynamics, 2—structure, 3—mechanics, and 4-—rate processes. THE following quotation from a recent article by von Bertalanffyl describes very well the situation which today challenges curriculum designers in all branches of science and engineering: "Modern scientific education is presented with a well known dilemma. The amount of facts in modern science, and in any of its smallest branches, is enormous. Life in general, and the academic curriculum in particular, is short. The abundance of factual data, as well as the intricacy of modern scientific techniques, experimental and theoretical, necessitates utmost specialization. This specialization, unavoidable though it is, involves serious danger for both the education of the scientist and the social function of science. "In so far as the advancement of science is concerned, history shows that interconnection of different fields and problems is a most important basis of progress. Many of the paramount achievements of science arose on borderlines, and from the synthesis of formerly separate fields . . ." Specialization in subfields of metallurgy has become a serious educational problem only in about the last decade. The growth in specialization, almost as a necessity, has paralleled the rapid growth in metallurgical knowledge during this period. Moreover, in planning future educational policies, the educator must be concerned not only with the rate of increase in metallurgical knowledge and with the concomitant rate of increase in specialization, but also with the second derivatives, that is, with the rates of increase of the rates of increase. These second derivatives are positive and large; the growths being dealt with are self-catalyzing, or like a chain reaction. As a measure of specialization, the length of the list of different kinds of metallurgies can be considered, the kinds of metallurgy which represent one person's particular interests and those of other practicing metallurgists. To start with, there are physical metallurgy, process metallurgy, and mineral dressing, then mechanical metallurgy, metal processing, foundry metallurgy, corrosion, solid state physics, high temperature metallurgy, welding, powder metallurgy, nuclear metallurgy, etc. Each of these fields is growing so rapidly that any one metallurgist can hope at best to keep up to date in only one or two. What is the impact of all these "metallurgies" on metallurgical education and metallurgical curricula? In answering this question, it can be said, first, that educators have resisted fairly well the temptations to split up metallurgy, with different curricula, different options, degrees with different labels, and the like—degrees are still given in plain Metallurgy and Metallurgical Engineering. In other ways, though, the pressures of specialization have had noticeable effects. There is a tendency to think of these "metallurgies" as the important subdivisions of Metallurgical Engineering and to work up

Jan 1, 1956

By C. D. King

The advances in basic open-hearth practice which have occurred during the past decade have been principally in the direction of the physical development of larger units, decreased fuel consumption and increased length of furnace campaigns. However gratifying the economies which have resulted from these improvements are, it must be granted that like advances in chemical, physical-chemical and metallurgical knowledge pertaining to open-hearth practice would have added greatly to these already attained reductions in costs and it is the purpose of this paper to stimulate the discussion and study of these phases of cooperation and their relation to ingot yields. Definition and Calculation oF Losses In discussing basic open-hearth yields, the writer refers to the ingot yields obtained in the process of converting pig iron, scrap and ore to steel. In this conversion some scrap is produced. The difference between the total weight of ingots and scrap produced and the original metallic charge constitutes the loss. Basic open-hearth yields vary considerably, and while some of the divergencies can be explained metal-lurgically because of differences in slag analysis, proportion of pig charges, and character of steel made, there often remain differences that apparently do not readily disclose themselves. In reconciling yields by the usual accepted methods of calculation, one is often forced to evaluate large losses as ((unaccounted for." Such a system is prone to accept these large losses as inherent to the operat.ion and not, susceptible of appraisement and correction. It is obvious that if the ingot yield plus the scrap recovered subtracted from 100 per cent. determines the loss, a drop in yield may increase the loss or the scrap, and both contribute to a monetary loss. To be sure, one can subdivide these unaccounted for losses into various components, such as metallics in slag, free Fe in slag, spillage, etc., and thereby reduce the amount of losses considered as "unaccounted for." If empirical methods could indicate with some degree of accuracy all losses, however slight, the undetermined losses become appreciably smaller and resultant calculations will check actual

Jan 1, 1929

By W. C. Ralston

This note will give the cost of driving an adit at the Melones mine, in 1898, and, for purposes of comparison, the cost of similar work, in 1888, at the Hogsback mine, Placer county, Cal. The property of the Melones Consolidated Mining Company is situated on the Mother Lode of California, on Carson Hill, near Robinson's Ferry, and adjoins on the south the famous Morgan mine. The Mother Lode of California extends for a distance of over 100 miles in length through several counties, with a general strike of northwest and southeast. Three veins (commonly called the east vein, middle vein and west vein) comprise the " lode " in this section. The Melones property is situated upon the east and middle vein, and includes 1407 feet on the east vein and 5166 feet upon the middle vein. A shaft had been sunk on the Reserve mine, which is on the east rein, and within 230 feet of the Morgan mine. At the bottom of this shaft drifts and cross-cuts had been run and a large body of ore developed. It was deemed advisable by the Melones Mining Co., which holds this property under bond from the Melones Consolidated Mining Co., to run a tunnel and develop this body of ore at a greater depth. An option was obtained upon the South Carolina mine, which adjoins the property on the south, and is on the same east vein, upon which a tunnel had been run a distance of 1080 feet. This tunnel was cleaned out and continued to a point within forty feet of the Morgan mine. It passes directly under the Reserve shaft, 425 feet below the 200-foot level. The additional length of tunnel to be run was 1923 feet, and

Jan 1, 1899

By William Plank

In practically all rock-excavation problems there is need for a careful study of the rock structure, its fault, cleavage or bedding planes, and even the texture of the rock itself. These studies should form the bases upon which an excavation method is selected and they should be carefully considered in predicting the amount and extent of the excavation. The need for such studies was forcibly illustrated in the problems involved in a cut made in 1929, along and underneath a 200-ft. high rock projection for a State-highway near the City of Easton, Pennsylvania. The rock mass was badly faulted and also contained a number of cleavage planes at approximately right angles to the fault planes. Much of this structure was visible and could have been studied and analyzed before' the work was begun. The State had rigid specifications as to finished grade and slope of cut, which apparently were made without reference to the geologic structure. The contractor complied with the specifications, under the close inspection of the State engineers. A tunnel blast was, placed in the base of the cliff, with the result that 65 per cent more rock was broken than was intended by the specifications. About four years after the blast, the writers of this paper studied the circumstances surrounding the operation, to determine the cause of this excess excavation.

Jan 1, 1935

By Frank A. Wardlaw

MY subject covers the effect that recent metallurgy has had on operations at the Utah-Delaware mine. This mine is the old Highland Boy mine of Bingham Canyon, Utah, one that has now been in operation for about 30 years. It was first operated by Messrs. Weir and Newhouse as a gold mine, under direction of the Highland Boy Gold Mining Co. The ore was oxidized gold ore and it was treated on the property in a cyanidation plant. During the process of development, sulfide ore was found assaying about 5 per cent copper. It proved to be the discovery of what is yet the largest sulfide copper orebody in the State. The first shipment was made in December, 1896. A smelter was built in Salt Lake Valley to treat this ore and not long after the property was sold to the Utah Consolidated Mining Co. From 1900 to 1924, the mine was a large producer of direct-smelting ore which averaged for many years 4.5 per cent. copper, then later dropped to 2 per cent. copper. During the years 1912 to 1920, direct-smelting lead ore was also mined. In 1918'and 1919 ore developments at depth showed a decided increase in silica content and a porphyry sill so closely associated with the ore that it was impossible to mine the ore clean and it was found necessary to build a copper flotation Eoncentrator at Tooele. The mill had a capacity of 1000 tons a day and made a recovery of 90 per cent., and would have been responsible for a continuance of profitable operations had it not been for a slump in the copper market and the necessary high cost of mining ore on the lower levels. RESULTS OF SELECTIVE FLOTATION In 1924 the mine was on the point of a shutdown which had all the earmarks of being permanent; it was being operated at a heavy loss and preparations were made to pull the pumps and salvage the machinery. The plant at Tooele was remodelled for selective flotation by the Inter- national Smelting Co. in order to treat custom ores, and incidentally to clean up a possible 10,000 tons of lead-zinc ore which it was thought possible to get in the Utah-Delaware before shutting the mine down. Results were so encouraging that an effort was made to develop more lead-

Jan 1, 1928

By C. E. SWANN

NOT long ago an engineering study was made to determine if the time had arrived to lower the head of standing water in abandoned Rock Springs mines Nos. I and 3 of The Union Pacific Coal Co. so that this water would not become a menace to the future operations of adjacent mines or mines developed on seams lower in the coal measures. This survey resulted - in a decision to unwater the No. 1 mine workings and, incidentally, the old No. 3 mine workings by drilling a large-diameter hole from the surface to an opening in No. 1 mine at the sump below 21 entry, provided it was found practical to operate a large-capacity, vertical, deep-well pump under the existing conditions. This would relieve the static bead of 200 ft. of water at the fault that separates Rock Springs mines Nos. 1 and 4, which is the

Jan 1, 1935