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By Charles White Merrill

A forecast of mineral demand during the remaining years of the 20th century can serve as an excellent starting point for student mining and mineral engineers in planning their professional careers. This approach of appraising demand before seeking supply is not new. of course, but, it is quite the opposite of the traditional attack on mineral resources in which adventurous prospectors, followed by practical miners and engineers, have in the past sought out and developed mineral supply with a faith that markets existed for the products they were preparing to offer. Such faith, even to this day remains fully justified if the product is gold, which still enjoys an unlimited market at $35 a fine ounce, but other mineral products must compete in markets of varying stability and capacity for adsorbing new supply. The world is in a period of rapid expansion. Most basic is the worldwide increase in the number of people which has reached proportions popularly termed "the population explosion." Conservative demographers, noting an increase from 1 ?h billion people at the beginning of the 20th century to 3 billion today, are predicting 5 billion by the year 2000; some predictions are much higher.

Jan 2, 1964

By Behrouz Abedian, Livia M. Racz

"We address dynamic interactions between high-energy, reactive surfaces of polymer-matrix composites and solid surfaces. A common characteristic of these interfaces is that bonding occurs readily upon contact. In many industrial and biomedical applications, it is desirable to suppress this bonding phenomenon. This interfacial effect is discussed in light of the development of our new method of handling polymer-matrix composites in dental applications. This method involves vibration of the solid-polymer interface at different frequencies. For each material, there is a critical frequency at which the sum of the viscoelastic and inertial energies of the fluid at the surface exceeds the energy available for bonding. When the polymer is vibrated at or beyond this frequency, it does not adhere to solid surfaces. An important aspect of the developed process is that it can be used to characterize surface and interfacial properties of polymers under dynamic conditions, whereas existing techniques are restricted to the study of bulk dynamic properties.IntroductionThe purpose of this paper is to report on the development of a new method for manipulating polymer-matrix composite materials used in dental applications, and the potential of this process for use in materials characterization. The materials under discussion have polymer matrices of a combination of bisphenol A-glycidyl methacrylate (BIS-GMA) and triethylene glycol dimethacrylate (TEGDMA), and contain filler particles of silica and/or zirconia glasses. These materials are called direct aesthetic restorative materials, and are used for filling of cavities, repairing chipped teeth, and for other restorations in which appearance is of importance. They have the appearance of natural tooth material, and are therefore in great demand for use in the anterior portion of the mouth(l,2)."

Jan 1, 1998

Blast Engineers frequently use the terminology "the blast showed good heave", or even "the heave was better this time". It is reasonably obvious that "good" and "better" are not the best terms to use. It is also noted that any variation in the data can be misleading. The author proposes a more precisely defined and objective set of measures as tried and tested in a project in 1988. Simple objective measurements of a muck pile profile can measure 1. distance thrown 2. spread of material 3. heaping of material 4. skewness, or bias in the heaping 5. rotation of the mass This technique enables one to compare the profiles from different blasts without relying on subjective experience or judgement. Simple, artificial profiles will be presented to illustrate the problems of description; and then application of the measurement techniques to these profies will be discussed with physical interpretations. The mathematical techniques will be presented, and results of the application of the techniques to real data collected during research carried out at Baimsdale in Victoria, will be presented as illustration. The use of these techniques in mathematical modelling will be discussed.

Jan 1, 1990

By Evans B. Mayo

As a result of studies distributed over the earth- including ocean basins as well as continents- some tectonists recognize four dominant structural trends: 1) northwest; 2) northeast; 3) nearly east- west, or equatorial; and 4) nearly north-south, or meridional. Baker' proposed a theory to account for these trends and Sonder5 called their world-wide arrangement the regmatic shear pattern. Moody and Hill6 proposed a much more complicated shear network which, although fascinating and perhaps ultimately useful, will not be followed here. In a recent review of deformation within the Cordillera, Wisser7 mentioned the four fundamental directions. The fact that many geologists deny the existence of the regmatic shear pattern implies that the fundamental structures are far from obvious. It may mean, also, that some geologists are not accustomed to examine regional and world maps analytically. The maps require much study, and certain features, should be isolated on overlays. Even so, with the present limited knowledge, uncertainties remain. The following analysis is a qualitative experiment, subject to change as information accumulates, and should be supplemented by the western sheet of the Tectonic Map of the United States.8

Jan 11, 1958

By A. A. Beard

ABOUT three years ago, I. L. Dunn, of Marietta, Ohio, found that wells could be cleaned by blowing with compressed air; this method has been used with great success on many wells in the Marietta, Ohio, district, where compressed air is being used to increase production, by forcing oil through the depleted sands. About a year ago, the process was successfully used to clean out wells in the Lenapah pool in Oklahoma, where an air plant had been installed, under the supervision of I. L. Dunn. Wells from 900 to 1000 ft. deep, with 40 ft. of sand and cavings in them, were cleaned out in from two to three days. The use of this process had, so far, been limited to properties using the Smith-Dunn process, where compressed air, under suitable pressure and volume, was available. For other properties, a portable compressor seemed essential; this was built and successfully demonstrated by Mr. Dunn, for the Tidal Oil Co. in September, 1924. The process of cleaning out with air has been described.1 It consists of lowering the tubing into the well, with a shoe or nipple of heavy pipe substituted for the perforated anchor on the bottom. Into the tubing, compressed air is introduced through a rotary swivel hose at the top, or by means of swing connections. The tubing is lowered to the top of the cave to be cleaned out, several barrels of water are put into the hole, and the compressed air is turned on. This blows out the material between the casing and the tubing, the tubing being lowered as the material is removed.

Jan 9, 1925

By Chuanfu Zhang, Jinliang Wang

"Brickless reaction shaft is the latest progress for flash smelting furnace. However, there are many factors influence the melting point of the freeze slag inside brickless reaction shaft, and their variational regularities are not obvious, thus, it is difficult for conventional methods to analyze accurately the complex data. In this research, the experiment data of slag melting point were processed based on optimal discrimination plane. For this method, two orthogonal vectors were firstly built up based on the Fisher's criterion, and then the experiment data were projected onto the two vectors, thus, two-dimensional feature vectors were extracted as criteria to determine the factors effect degree on the slag melting point. Results show that the CaO content is the greatest factor to the melting point of the freeze slag inside brickless reaction shaft, the content of Fe3O4, SiO2, Cu2 O and MgO is the second, and the FeO content is the last.IntroductionBrickless reaction shaft is the latest progress of flash smelting furnace reaction shaft. To research the influence factors on the slag melting point inside the brickless reaction shaft is significant to form freeze slag with compact structure, good heat insulation, certain intensity, appropriate thickness and reasonable distribution, to extend furnace life, to reduce energy consumption, and to promote safe production.However, due to the complex components, there are many factors influence the melting points of the freeze slag inside brickless reaction shaft, and their variational regularities are not obvious. Therefore, it is difficult for conventional methods, such as variance analysis, data fitting, etc., to analyze accurately the complex experiment data.Pattern recognition can easily classify information, even if there are many influencing factors. For pattern recognition, there are some sub-disciplines such as discriminant analysis, feature extraction, error estimation, cluster analysis (together sometimes called statistical pattern recognition), grammatical inference, parsing and matching (sometimes called syntactical and structural pattern recognition) [1, 2]."

Jan 1, 2012

By A. L. Muler

Since 1956, when Broadbent and Callcott 1 proposed to analyze breakage processes by matrix methods, several authors and their co-workers have proposed various models of grinding that, in principle, could lead to fully automated grinding circuits. In particular, Meloy and Gaudin2, Gardner and Austin3, Kelsall and Reid4, Neloy and Bergstrom5, Callcott and Lynch 6, and Draper and Lynch have, by either computer simulation or by experimental data, or by a combination of the two, verified that comminution is reasonably well described by at least two functions: a selection function and a breakage function. The stage concept proposed by Callcott and Lynch6 requires that a classification matrix be included to completely describe breakage in an open circuit rod mill. The purpose of this work, portions of which are herein described, is to accumulate sufficient information on the breakage characteristics of quartz and magnetite in an open circuit rod mill, so that several of the theoretical and experimental approaches proposed in the literature can be compared with each other. Data is being gathered to compare the experimental method used by Kelsall and paid against the stage approach of Callcott and Lynch.

Jan 1, 1968

By W. Vickers

Single-point rotating cantilever fatigue tests have been carried out at 550" to 650°C on beryllium produced by a variety of fabrication routes. All the specimens gave similar plots of stress against number of cycles to failure but failure occurred at a lower stress range in the hot-pressed material than in the extruded material. A discontinuity or "kink" appears to exist in the curves and this is considered. A true endurance limit was not evident up to 10 cycles. When Brush hot-pressed warm-extruded beryllium was tested at 600oC a relationship where Nf = number of cycles to failure, ?ep = plastic strain range, and c = constant, was shown to be applicable for values of ?ep > 6.3 x 10-4. Further for this moterial and temperature and for frequencies between 150 and 4500 cycles per min, the variation of number of cycles to failure with frequency obeyed the expression N = Af0.44 where N =number of cycles to failure, f = frequency, and A = constant. Examination of the fracture surfaces indicated that they were generally intergranular and in all cases the higher the stress the more irregular was the fracture. Microexamination has shown that grain boundary cavities and fine intergranular cracks were associated with the fractures. REVERSING or cyclic stresses set up in fuel elements can lead to failure by fatigue. Fatigue stresses may be developed by instability of the fuel element in the coolant flow leading to rattling against the channel wall or fin vibration. Thermal cycling also sets up reversing stresses due to differential expansion of fuel and can. Fatigue resistance is of some importance therefore in the evaluation of canning materials. At the time the work described in this paper was initiated, beryllium was being considered for the can and endcaps of an advanced gas-cooled reactor fuel element. With this in mind, beryllium obtained from different manufacturing routes was tested on single-point rotating cantilever fatigue machines at temperatures the same as those envisaged in the reactor to obtain appropriate fatigue data. The results obtained indicated a discontinuity in the S-N curves coinciding with the yield stress in the specimens. Although in some cases the data is insufficient to warrant a detailed quantitative analysis, a qualitative analysis of this effect was thought to be justified. 1) EXPERIMENTAL DETAILS The materials used are given in Table I together with the production route and available analyses. The specimen shape is shown in Fig. 1. The fatigue specimens were machined slightly oversize, after which they were given a stress-relieving anneal of 1 hr at '750° C in vacuum. This was followed by an etch in sulfuric-phosphoric-chromic acid mixture down to the finished dimensions given in Fig. 1. Etching served to remove the interference colored oxide film formed on the surface during annealing and very small recrystallized surface grains too. The specimen was mounted in the grips of a cantilever machine and rotated inside a furnace controlled at the testing temperature. The specimen was loaded in increments as the speed was increased until the required load was applied at 5000 cycles per min. A revolution counter was used to record the total number of cycles.

Jan 1, 1964

By A. L. DeVegt, H. G. Bayer, C. J. Buisman

During the last ten years, Paques Inc. has been engaged in the development and installation of treatment systems to remove sulfur compounds from water and gaseous streams using biotechnological processes. Metal and sulfate can be removed from mine waters in two biological steps. In the first step, sulfate-reducing bacteria converts sulfate to hydrogen sulfide (H2S). The HS reacts with the dissolved metals to form insoluble metal sulfide precipitates. In the second step, sulfide-oxidizing bacteria convert excess H2S to elemental sulfur. The Budelco Zinc Refinery in The Netherlands installed a groundwater treatment system to remove metals and sulfate using the biological steps described above. The system has been operating since May 1992 and has been treating 5,000 m3/d (180 thousand cu ft/day). A pilot plant began operation in November 1995 at Kennecott's Bingham Canyon Utah copper mine to develop processes for metal and sulfate removal from groundwater and for the selective copper recovery from leach water. The principle of the biotechnological methods, the full-scale experience and an overview of the test program at the mine are presented

Jan 1, 1999

By Jr. D. C. Williams, D. V. Carter

The four new oil-field discoveries made in the East and East Central Texas districts during 1941 were the East Long Lake field, Anderson County; Pickering field, Shelby County; Pleasant Grove field, Rusk County, and Tri-Cities field, Henderson County. The discovery of oil production in the Pettit lime of the Lower Glen Rose was made in the Groesbeck (Barron) field in Limestone County and the Willow Springs field in Gregg County. Important extensions were made to the Pittsburg field, in Camp County, the Chapel Hill field, in Smith County, and the Hawkins field, in Wood County. The Hawkins field was extended sufficiently to more than double the number of proved surface acres. As usual the East Texas field led the district in the number of completions for the year. The second most active field during the year was the Hawkins field, with 250 new wells completed. The third most active was the Long Lake field, in which 50 wells were completed. Approximately 964 wells were completed in the district during 1941. Production and Probation The district is credited with having produced 163,566,695 bbl. of oil and distillate during the year. This represents a decrease of 4 per cent from the 170,424,685 bbl. of oil and distillate produced during the preceding year. The production of 130,378,620 bbl. of oil and distillate from the East Texas field represents 79.7 per cent of the total production of the district; that is, 6.3 per cent less than the production for the year 1940, The district had an estimated basic daily allowable of 614,982 bbl. of oil on Dec. 31. Approximately 33 per cent of the state's annual production was produced in the district, compared with 34.9 per cent for 1940. Since the majority of the fields in this district are subject to proration, any change in the annual production is attributable largely to changes in proration schedules and number of shutdown days. Fields subject to shutdown days were closed in for 113 days during the year, with the exception of the East Texas field, which was shut down 111 days. An order was promulgated by the Oil and Gas Division of the Texas Railroad Commission for encouraging the disposal of salt water and reservoir-pressure maintenance in the East Texas field. Discoveries Tex Harvey Oil Company'sNo. I S. E. J. Cartmel was completed as the discovery well for the East Long Lake field, Anderson County. Production was found in the Woodbine sand, the horizon from which the Long Lake field produces. The Pickering field, Shelby County, secures its production from the Nacatoch sand, found at an approximate depth of 1510 ft., in A. E. McKiernan's No. I, Pickering Lumbering Co. This field is in an area near the state line in which a number of relatively unimportant and

Jan 1, 1942

By Jr. D. C. Williams, D. V. Carter

The four new oil-field discoveries made in the East and East Central Texas districts during 1941 were the East Long Lake field, Anderson County; Pickering field, Shelby County; Pleasant Grove field, Rusk County, and Tri-Cities field, Henderson County. The discovery of oil production in the Pettit lime of the Lower Glen Rose was made in the Groesbeck (Barron) field in Limestone County and the Willow Springs field in Gregg County. Important extensions were made to the Pittsburg field, in Camp County, the Chapel Hill field, in Smith County, and the Hawkins field, in Wood County. The Hawkins field was extended sufficiently to more than double the number of proved surface acres. As usual the East Texas field led the district in the number of completions for the year. The second most active field during the year was the Hawkins field, with 250 new wells completed. The third most active was the Long Lake field, in which 50 wells were completed. Approximately 964 wells were completed in the district during 1941. Production and Probation The district is credited with having produced 163,566,695 bbl. of oil and distillate during the year. This represents a decrease of 4 per cent from the 170,424,685 bbl. of oil and distillate produced during the preceding year. The production of 130,378,620 bbl. of oil and distillate from the East Texas field represents 79.7 per cent of the total production of the district; that is, 6.3 per cent less than the production for the year 1940, The district had an estimated basic daily allowable of 614,982 bbl. of oil on Dec. 31. Approximately 33 per cent of the state's annual production was produced in the district, compared with 34.9 per cent for 1940. Since the majority of the fields in this district are subject to proration, any change in the annual production is attributable largely to changes in proration schedules and number of shutdown days. Fields subject to shutdown days were closed in for 113 days during the year, with the exception of the East Texas field, which was shut down 111 days. An order was promulgated by the Oil and Gas Division of the Texas Railroad Commission for encouraging the disposal of salt water and reservoir-pressure maintenance in the East Texas field. Discoveries Tex Harvey Oil Company'sNo. I S. E. J. Cartmel was completed as the discovery well for the East Long Lake field, Anderson County. Production was found in the Woodbine sand, the horizon from which the Long Lake field produces. The Pickering field, Shelby County, secures its production from the Nacatoch sand, found at an approximate depth of 1510 ft., in A. E. McKiernan's No. I, Pickering Lumbering Co. This field is in an area near the state line in which a number of relatively unimportant and

Jan 1, 1942

By Cyril Wells, Robert F. Mehl

The two earlier papers in this series1,2 presented data on the rate of diffusion of carbon and of manganese in gamma iron. Apart from their scientific interest, these data are needed chiefly in order to treat data on carburization, on rate of formation of pearlite, and on rate of austenit-izing in a quantitative way.1'2'9'10 In the present investigation rates of diffusion of nickel in ?-Fe over wide temperature and concentration ranges have been determined, and the effects of carbon, of im- purities, and of grain size on these rates have been studied. Claussen,3 using the data of Fry,4 has calculated the diffusion coefficient of nickel in y-Fe as 9.2 X 10-11 sq. cm. per sec. at 1200ºC., but had no data from which to calculate the variation of D with concentration, temperature, and percentage of carbon. Method and Materials Method.—Nickel was diffused along the axis of a cylindrical specimen across a concentration gradient, concentration-penetration curves were determined and D values calculated from Grube or Matano solutions.5 Details of the method are given

Jan 1, 1941

By Cyril Wells, Robert F. Mehl

The two earlier papers in this series1,2 presented data on the rate of diffusion of carbon and of manganese in gamma iron. Apart from their scientific interest, these data are needed chiefly in order to treat data on carburization, on rate of formation of pearlite, and on rate of austenit-izing in a quantitative way.1'2'9'10 In the present investigation rates of diffusion of nickel in ?-Fe over wide temperature and concentration ranges have been determined, and the effects of carbon, of im- purities, and of grain size on these rates have been studied. Claussen,3 using the data of Fry,4 has calculated the diffusion coefficient of nickel in y-Fe as 9.2 X 10-11 sq. cm. per sec. at 1200ºC., but had no data from which to calculate the variation of D with concentration, temperature, and percentage of carbon. Method and Materials Method.—Nickel was diffused along the axis of a cylindrical specimen across a concentration gradient, concentration-penetration curves were determined and D values calculated from Grube or Matano solutions.5 Details of the method are given

Jan 1, 1941

By A. Koursaris, J. B. See

An investigation is described in which the resistivities of Mamatwan manganese ore, Delmas coal, and Iscor coke, at temperatures or up to 1400°C were determined, as well as the resistivities of mixtures of ore of a constant size range with Delmas coal or Iscor coke of three different size ranges. The resistivities of the ore and the coal were characteristic of those for semi-conducting materials, were strongly influenced by temperature, and decreased by several orders of magnitude between room temperature and IOOO°C. The resistivity of the coke changed only slightly between room temperature and 1400°C, and the resistivity of the coal approached that of the coke at I300°C. This provides support for the theory that the resistivity of carbonaceous reducing agents is primarily a function of heat treatment, and not of the rank and composition of the coal. Above 1200°C, the resistivity of mixtures of ore and coke fell steeply owing to an increase in the volume fraction of coke in the mixture and to the formation of slag. The results were similar for the three different size ranges of coke. The extremely high resistivities of ore-coke and ore-coal mixtures at Iow temperatures indicate that there is unlikely to be much conduction of current in the higher regions of a furnace. Thus, the resistance of a furnace is governed mainly by the conditions at the electrode tips and in the molten regions. To explain the very Iow resistances of furnaces, usually, about I m£?, it would be necessary for investigations to be conducted under conditions similar to those in the active zone of a furnace.

Jan 1, 1980

By Vincent C. Smith, Agit Singh, Bernard Muller

The control of minerals processing plants is by no means trivial. In order to address some of the difficulties, it was decided to develop and test a model predictive controller (MPC) for a milling circuit. A milling simulator was written to test the MPC controller. Due to the large number of tuning parameters in a controller of this type, an optimising algorithm was written that automatically tunes the controller. Good, robust control was obtained when the controller was tuned using this algorithm. The controller was tested for various scenarios that are often encountered in the minerals processing industry. When problems were encountered, the MPC algorithm was specially adapted to accommodate for these difficulties. Control was further improved by using feedforward control as well as quadratic programming. The movement of the manipulated variables was reduced by using a region of uncertainty that allows the controlled variable to vary within a specified region around the setpoint. Integrators were handled by adapting the algorithm slightly and adding an optional integral error portion in the MPC controller. The performance of the enhanced MPC controller was compared to PI controllers on both the simulator and a commercial plant. The MPC controller showed faster responses with less interaction in both cases.

Jan 1, 2003

By H. Landsberg

THE curriculum presented here is an outgrowth of discussions by the Committee on Geophysics Courses of the A.I.M.E. in previous years. It had to be a compromise between the desires voiced by employers of geophysicists, professional geophysicists and the possibilities at an average college. There one has to face the questions of the available teaching staff, the inertia of administrators and teachers set in their ways, and the red tape involved in modernizing antiquated curricula. It is, of course, not ideal to have colleges and universities lag 10 years behind the times. Rather, instead of being prodded by industry, -they should be ahead of industrial needs. There should also be a certain amount of leeway for the student in any college curriculum. All these points had to be considered in drawing up a curriculum, which, instead of being narrowly termed "geology" or "geophysics" was rather called "earth science." It gives the student a chance to specialize in one of the various branches represented by teachers on the faculty of The Pennsylvania State College, giving as options Geology (with subdivisions of Mineralogy and Paleontology), Geophysics, Geography, and Meteorology. Table IA. represents the option of geophysics in the curriculum that envisages that a student may want to make his career in any of the fields encompassed by the American Geophysical Union or in geoexploration. This is, of course, only the start of an education that in most cases will have to be followed by graduate work for complete professional training. The outlined curriculum is definitely of an engineering type and is identical for all of the four options mentioned for the first two years. Specialization will start in the junior year but even thereafter the branches are kept as closely allied as feasible in order to permit a student to change from one to the other (e.g., because of a different aspect in the employment situation) with a minimum of additional work. Table IB shows the geophysics option according to subject matter, indicating the considerable amount of work in the fundamentals of mathematics, physics and chemistry with a liberal number of geology courses, and some engineering. The courses in the field of geophysics are limited-just two lecture courses as a general introduction and one field course, to permit the student a visualization of the correlation between mathematically analyzed physical data and the geological realities. Thesis work is considered essential to teach the student, while he is still in college, some things S. F. Kelly has mentioned as desirable: (I) following of instructions for somewhat independent work; (2) organizing of material, and (3) producing a readable report. This, together with the personal contact with the advising faculty member, will help in forming a student's personality. The seminar course attempts to get the student into the habit of reading current literature, so that he can keep abreast of the times.

Jan 1, 1941

"An atmospheric process for the synthesis of scorodite(DMSP®)has beendeveloped,in which ferrous ions were oxidized by oxygen gas in the presence of pentavalent arsenic ions. Under optimum conditions, the synthesized scorodite (FeAsO4?2H2O) was well crystallizedand the crystals were faceted; the particle sizes were as large as 15 to 20 µm. In thisstudy, iron (II) sulfate heptahydrate (FeSO4·7H2O), arsenic (V) acid (60mass%H3AsO4) solution, and distilled water were used to prepare the original experimental solution (700 ml), in which the contents of Fe(II) and As(V) were 55.9 g/L and 50.0 g/L, respectively. The effects of various synthesis conditions, such as the type of oxidizing gas (oxygen or air), gas injectionrate, temperature, and the initial pH of the solution, on the size and shape of the scorodite particles wereinvestigated. From the experimental results, the changes in the shape of the scorodite particles wereclarified for each synthesis condition.INTRODUCTIONDOWA has developed a processfor synthesizing well-crystallized scorodite (FeAsO4•2H2O). Theprocess is named andtrademarked as DMSP® (Fujita et al., 2008; Fujita et al., 2008; Fujita et al., 2009; Fujita et al., 2009; Fujita et al., 2009, Kubo et al., 2010). In this process, oxygen gas is injectedinto a sulfuric acid solution containing large amountsof As(V) and Fe(II). Facetedscorodite crystals as large as 15–20 µm weregeneratedthrough the pre-formation of a gel-like precursor. However, it is known that the synthesized scorodite particles become smaller and more aggregatedwhen the synthesis conditionsdeviate from the optimumconditions.In this study, the effects of various synthesis conditions, such as the type of oxidizing gas (oxygen or air), gas flowrate, temperature, and initial pH of the solution, on the size and shape of the scorodite particles were investigated. The experimental resultsclarified the changes in the shape of the scorodite particles for each synthesis condition."

Jan 1, 2016

By Hall J. S, Zuiderwyk M, Reid A. F

A prototype version of a computer controll- ed on-line scanning electron microscope image analyser, employing the real-time signals ob tamed by digital control of the electron beam has been used to obtain statistical quantificat lion of a wide range of mineral grain character istics, including composition, size distribut- ion, and degree of liberation. These propert lies have been determined for suites of whole particles of flotation concentrates, mounted without further preparation. The facility is also well adapted to the measurement of general Istereological parameters. The computer control software is based on an operating system which includes the device drivers and which is linked to FORTRAN programs [containing the procedural algorithms. The beam scanner provides a 4000 x 4000 point raster swept at a 10 Mhz rate in steps of 1 to 200 points and a set of up to 8 signal channels which respond to electron or energy dispersive X-ray signals to provide a digital attern.characterizing the sample composition. the beam is stepped at high speed until a part- 'cle or phase boundary is encountered; a longer well time is set if X-ray data is required. he digital scanner interrupts the computer

Jan 1, 1977

By William P. Jones

THE consumption of sulphuric acid, one of the most important commodities in our modern industrial world, is often used as a barometer for industrial activity. The economics of acid manufacture are largely dependent upon the location of the place of consumption and the availability of raw materials in that locality. Sulphuric acid is made from SO,, oxygen from the air and water. Therefore the sulphur dioxide is the only raw material to be considered in an economic study. SO, can be obtained from almost any material containing inorganic sulphur, such as elemental sulphur, pyrites, coal, sour gas and oil, metallurgical gases, waste gases, or gypsum and anhydrite. Many tons of acid can also be reclaimed by the recovery and concentration of spent acids. The aim of this paper is to present a guide to the economic aspects to be considered when the installation of an acid plant is contemplated. It must be remembered that 1 ton of elemental sulphur produces 3 tons of sulphuric acid and that the shipping of sulphuric acid by tank car is very costly. The size of the plant must also be given careful consideration. For instance, operation of a plant producing 5 tons of acid per day might be warranted in Brazil or Pakistan, whereas economics usually favor buying quantities up to 50 tons per day for use within the United States. Elemental sulphur, when available at the low price of 1M4 per lb delivered at an acid plant, has always been the raw material most frequently used for sulphuric acid. All conditions favor its use at this price. The so-called sulphur shortage has been the subject of so many technical papers, magazine articles, and newspaper items during the past y6ar that it hardly seems necessary to mention it again, but a very brief review of the matter will serve as a foundation for the discussion that follows. There is no shortage of sulphur. Only a shortage of low-cost Frasch-mined brimstone exists today. Other more expensive sulphur-bearing materials are plentiful, both in the United States and abroad. The low cost of Frasch-mined brimstone has discouraged the development of higher cost sources. However, the approaching depletion of Gulf Coast dome deposits and the greatly increased demand for sulphur here and abroad have made it necessary for industry to prepare for conversion to utilize sulphur in other forms. For future planning this situation must be considered permanent and not temporary. This conclusion is based on the fact that although sulphur demand will continue to rise, the production of Frasch-mined sulphur probably will not increase greatly beyond its present level of about 5,000,000 long tons per year. The International Materials Conference in Washington estimates 1952 requirements of the free world at nearly 7 million long tons; and the Defense Production Administration has recently set a new goal for 8,400,000 long tons annual domestic production by 1955. The total sulphur equivalent produced in this country in 1950 was 6 million tons. What, then, are the alternatives for the manufacture of the vital chemical, sulphuric acid? Today about 85 pct of this country's sulphur, and nearly 50 pct of the world supply, comes from our Gulf Coast salt domes and is extracted from the earth by Frasch's hot water process. The Gulf Coast salt dome deposits have been the most important known natural deposits in the world, producing 90 million tons of sulphur during the past 50 years. However, at the present rate of extraction these deposits cannot be expected to last indefinitely. Pyrites Pyrites are, and have been for many years, the source of more than 50 pct of the world's sulphur requirements. The principal use, of course, is in the manufacture of sulphuric acid. The use of pyrites in the United States has diminished greatly because of the availability of low cost native sulphur, but pyrites have continued a major source of sulphur in many other countries. The most available pyrites for use in this country are in the form of lump pyritic ore and in mill tailings from flotation of other minerals such as lead, zinc, copper, gold, and silver. An important factor, when the use of pyrites for acid manufacture is being considered, is the disposal of calcine. A ton of sulphuric acid requires approximately ton of high-grade pyrite and results in 1/2 ton of calcine. If the calcine is a fairly pure oxide, free of harmful impurities, it can be used, after sintering, in an iron blast furnace burden. Its value might be as high as 15d per unit of Fe at the blast furnace; or possibly $10.00 per ton of sinter, if it assays 65 pct Fe. This might result in a credit of $4.00 per ton of acid if the sintering plant and blast furnace are both located adjacent to the acid plant. On the other hand, several factors must be considered before this credit can be realized, i.e., freight to blast furnace, availability of sintering facilities, methods of eliminating impurities, and the removal of valuable metal values. In some locations it would be most economical to dump the calcines.

Jan 1, 1953

By William P. Jones

THE consumption of sulphuric acid, one of the most important commodities in our modern industrial world, is often used as a barometer for industrial activity. The economics of acid manufacture are largely dependent upon the location of the place of consumption and the availability of raw materials in that locality. Sulphuric acid is made from SO,, oxygen from the air and water. Therefore the sulphur dioxide is the only raw material to be considered in an economic study. SO, can be obtained from almost any material containing inorganic sulphur, such as elemental sulphur, pyrites, coal, sour gas and oil, metallurgical gases, waste gases, or gypsum and anhydrite. Many tons of acid can also be reclaimed by the recovery and concentration of spent acids. The aim of this paper is to present a guide to the economic aspects to be considered when the installation of an acid plant is contemplated. It must be remembered that 1 ton of elemental sulphur produces 3 tons of sulphuric acid and that the shipping of sulphuric acid by tank car is very costly. The size of the plant must also be given careful consideration. For instance, operation of a plant producing 5 tons of acid per day might be warranted in Brazil or Pakistan, whereas economics usually favor buying quantities up to 50 tons per day for use within the United States. Elemental sulphur, when available at the low price of 1M4 per lb delivered at an acid plant, has always been the raw material most frequently used for sulphuric acid. All conditions favor its use at this price. The so-called sulphur shortage has been the subject of so many technical papers, magazine articles, and newspaper items during the past y6ar that it hardly seems necessary to mention it again, but a very brief review of the matter will serve as a foundation for the discussion that follows. There is no shortage of sulphur. Only a shortage of low-cost Frasch-mined brimstone exists today. Other more expensive sulphur-bearing materials are plentiful, both in the United States and abroad. The low cost of Frasch-mined brimstone has discouraged the development of higher cost sources. However, the approaching depletion of Gulf Coast dome deposits and the greatly increased demand for sulphur here and abroad have made it necessary for industry to prepare for conversion to utilize sulphur in other forms. For future planning this situation must be considered permanent and not temporary. This conclusion is based on the fact that although sulphur demand will continue to rise, the production of Frasch-mined sulphur probably will not increase greatly beyond its present level of about 5,000,000 long tons per year. The International Materials Conference in Washington estimates 1952 requirements of the free world at nearly 7 million long tons; and the Defense Production Administration has recently set a new goal for 8,400,000 long tons annual domestic production by 1955. The total sulphur equivalent produced in this country in 1950 was 6 million tons. What, then, are the alternatives for the manufacture of the vital chemical, sulphuric acid? Today about 85 pct of this country's sulphur, and nearly 50 pct of the world supply, comes from our Gulf Coast salt domes and is extracted from the earth by Frasch's hot water process. The Gulf Coast salt dome deposits have been the most important known natural deposits in the world, producing 90 million tons of sulphur during the past 50 years. However, at the present rate of extraction these deposits cannot be expected to last indefinitely. Pyrites Pyrites are, and have been for many years, the source of more than 50 pct of the world's sulphur requirements. The principal use, of course, is in the manufacture of sulphuric acid. The use of pyrites in the United States has diminished greatly because of the availability of low cost native sulphur, but pyrites have continued a major source of sulphur in many other countries. The most available pyrites for use in this country are in the form of lump pyritic ore and in mill tailings from flotation of other minerals such as lead, zinc, copper, gold, and silver. An important factor, when the use of pyrites for acid manufacture is being considered, is the disposal of calcine. A ton of sulphuric acid requires approximately ton of high-grade pyrite and results in 1/2 ton of calcine. If the calcine is a fairly pure oxide, free of harmful impurities, it can be used, after sintering, in an iron blast furnace burden. Its value might be as high as 15d per unit of Fe at the blast furnace; or possibly $10.00 per ton of sinter, if it assays 65 pct Fe. This might result in a credit of $4.00 per ton of acid if the sintering plant and blast furnace are both located adjacent to the acid plant. On the other hand, several factors must be considered before this credit can be realized, i.e., freight to blast furnace, availability of sintering facilities, methods of eliminating impurities, and the removal of valuable metal values. In some locations it would be most economical to dump the calcines.

Jan 1, 1953