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By J. A. Herbst, A. E. Oblad, Y. C. Lo

The major cost in comminution is energy consumption, which can be as high as 50% of the operating cost. Improvements in plant operations have resulted in up to a 15% reduction in energy usage (kw-hr/t). These improvements have been made through the optimization of grinding efficiency and the use of expert model-based control systems. Optimization involves the determination of the levels of the critical-operating conditions that result in the most efficient breakage of ore in the mill. These optimal levels are identified through plant/laboratory test work and through computer simulation using advanced process models. Model-based expert control achieves the maximum performance from the grinding circuit by identifying the characteristics of the ore in the mill with an optimal on-line estimator. Using this information, the control system dynamically determines the operating point that will yield the optimal performance. Two industrial applications of grinding-circuit optimization and model-based control are presented to demonstrate the power of this new technology.

Jan 1, 1997

By K. A. Johnson, F. H. Ellinger, C. C. Land

The Pu-La alloy systenz has been studied by thertnal, tnzcrographic, and X-ray diffraction methods. It is churacterized by a liquid miscibility gap, a maximum solubility of about 20 ut. pct PM in y lanthunum and 19 at. pct PI* in 0 lanthanum, very little soluibility of lanthanum in the plulonium allotropes, and the absence of intermediate phases. THE existence of immiscible liquids in the Pu-La system has been reported by Schonfeld.1 A tentative phase diagram based on the results of thermal-analysis experiments has been constructed by Poole et a1 2 This diagram shows a liquid immiscibility loop with a monotectic at 77 at. pct La and 846°C. 7 lanthanum is shown to dissolve 20 at. pct Pu and to decompose by an inverse peritectic reaction (y La = L , + p La) at about 82 at, pct La and 833°C. The ß lanthanum solvus was not determined, but the thermal work indicated a maximum solubility of 16 at. pct Pu in ß lanthanum. The present investigation has defined the solubility limits of plutonium in y lanthanum and 0 lanthanum, and, with the exception of minor discrepancies, has verified the results of Poole et al. 1) EXPERIMENTAL The electrolytic plutonium melting stocks were better than 99.9 wt pct pure, the main impurities being 90 ppm Fe and 50 ppm W. The lanthanum melting stocks, supplied by Research Chemicals and the Cerium Metals Corp., were about 99 wt pct pure, the main impurity detected by our spectrochemical analysis being 2000 ppm Fe. The components for each alloy button (-5 g) were weighed on an analytical balance and were melted together in a conventional arc furnace. If no significant weight loss occurred during melting, the as-weighed

Jan 1, 1968

By William J. Francart

In 2003, MSHA initiated a survey of the 11 Coal Mine Safety and Health Districts to develop a database for the implementation of Atmospheric Monitoring Systems (AMS) in underground coal mines. Mine operators continue to realize the benefits of improved fire detection capabilities, as the number of mines using the systems, as well as the percentage of mines, continues to increase. Fire detection data and new technology implemented in underground coal mines is discussed as well as regulatory compliance, diesel exhaust considerations and hydrogen interference in carbon monoxide detection.

Jan 1, 2005

By Roswell Johnson

PENNSYLVANIA will be remembered, as long as oil is produced, as the cradle of the industry of petroleum in North America. It was on Oil Creek, near Titusville, Venango Co., .that Cola Edwin L. Drake, superintendent for the Seneca Oil Co., brought in the first commercial oil well on Aug. 28, 1859. Great difficulty was experienced in getting the well down to the producing depth of 69 ft. (21 m.) with the spring-pole system then in vogue for punching shallow water wells, so the novel expedient of driving an iron tube through the surface clays and quicksand was finally resorted to. The well had an initial yield of 25 bbl. a day on the pump, but soon went off, though 2000 bbl. were produced by the end of the year. With the Drake well a success, a young industry sprang into being, the rapid growth of which has been second to none in the country and the value of whose product is only surpassed by that of coal. For years the only producing territory, the Pennsylvania-New York field attained its greatest production in 1891, when the bringing in of the McDonald pool, between Pittsburgh and the West Virginia line, gave a total of over 33,000,000 bbl. At present the field, combined with West Vir-ginia and southeast Ohio, gives 25,000,000 barrels. GEOLOGY AND STRATIGRAPHY In general, the Appalachian field is a huge geosyncline, the axis of which runs roughly northeast-southwest, from north of the New York state line south through Brookeville, Kittanning, Pittsburgh, Washington, through the southwest corner of the state of Pennsylvania into West Virginia. Minor folding has accompanied or followed the dominant fold of the field, and it is from these structures near the Pennsylvania-West Virginia line and their influence on the accumulation of oil and gas that I. C. White, state geologist of West Virginia, obtained his evidence for anticlinal guidance of prospecting.

Jan 2, 1920

By V. D. Ayurov, N. O. Kaledina

The coal mines monitoring should be based on the usage of simple and evident models, letting in the total unity to reflect a structure of organization of mine, system ability of its construction and specific character of its functioning. Such models are offered to create on the basis of extracted hierarchies of objects of mine. All objects of mine are broken on levels of technological hierarchy. For objects of each level of hierarchy there are made balanced models of entering and leaving material flows. Then these balanced models are coordinated among themselves by the help of the inter hierarchical relations. So the structured-qualitative characteristic of the object of monitoring, reflecting in a kind of the table structure of formation of material flows on mine, their intensity and measure of transformation is formed under transition from one level of hierarchy of mine to another. An example of real us- age of hierarchical balanced models on mine is given. The mathematical models of coal mine monitoring should reflect objective laws of their structural organization and functioning. Therefore under the constructing of mathematical models it is important such a way to reflect a structure of the mine organization, that in totality the models has been reproduction of system ability of its construction. The knowledge of the separate parties of functioning of mine, reflected in particular mathematical models, should "to be packed" in combined unity. Or else, they should be connected in system, convenient for recognition by the person. Considering the mine, the expert allocates multi-dimensionality of the objects of making its elements. He always has the knowledge of laws of development of mining work that is connected with pithy stratification of researched object. In dependence of sparial-temporary level of abstracting there are allocated the horizon, wing of a mine field, layer, panel, extracting face, longwall in coal mine. The human thinking on each of these levels operates with a set of concepts peculiar to him, characteristics, definitions.

Jan 1, 1996

By Robert J. Willard

In its search for additional ways to increase understanding of rock behavior, the Twin Cities Mining Research Center has turned to the scanning electron microscope, an instrument rapidly finding application in research concerned with surfaces of materials. Since features indicative of the manner in which rocks fail may be recorded on the surfaces of fragments as disintegration proceeds, this microscope might be used as a tool for seeking and mapping these minute features. In pursuit of such features, we chose to scan a portion of the fracture surface from a quartzite disk compressively loaded to failure between two pins centered along the disk's axis. The resultant fracture appeared as a rough, diametric plane, and the fracture surface near one of the loading points was scanned with the microscope.

Jan 1, 1969

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metaliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land the surface of which is suitable for agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago, has become valuable agricultural land dotted here and there with growing towns. Frequent references. will be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are equally applicable to all coal-mining states. Briefly stated, the question: is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1927

By Thomas A. Edison, John Birkinbine

The Transactions already contain many valuable papers on the subject of ore-concentration, but with reference more to the treatment of other ores than those of iron. In this country much money, labor and thought have been devoted to the enrichment of iron-ores by roasting to drive off sulphur and carbonic acid, eliminate water, or make the ore more friable, and by washing and screening to remove the clay and sand from earthy ores. In concentrating magnetites and hematites more has been done than is generally believed; but, unfortunately, the results up to the present time have not been encouraging. On the contrary, so many attempts have proved unsatisfactory that any system of concentration is now unjustly looked upon with doubt, and the problem presented to individual mines must therefore be approached with caution. For many years the magnetites of the Adirondack region of New York State have been roasted, reduced to proper size by means of gang-stamps, and jigged on screens in water. Latterly plunger-jigs and rotary-jigs have been introduced, and in some places crushers and rolls have taken the place of stamps. In one instance in that region a plant for reducing the ore by crushers and rolls and separating it by magnetism was put up to treat a titaniferous ore; but, the titanium occurring as ilmenite, the result was unsatisfactory, and the plant is now being reconstructed at another mine, where apatite and silica are to be separated from the magnetite. A large concentrating works was erected at Negaunee, Michigan, in the Marquette region, Lake Superior, to enrich the leaner specular ores. This consisted of crushers, Cornish rolls and rotary-jigs. The results ohtained weye not satisfactory, and it has been abandoned. Another plan to treat the lean magnetites from a large dump-pile at Republic, Michigan, by means of pulverizers and water-jigs also

Jan 1, 1889

An attempt has been made in tftis paper to review the general situation regarding the needs of the Mining and Minerals Industry for skilled and qualified personnel. Having defined the behavioural objectives of the courses of study, reference is thereafter made to the factors influencing the effective design of courses for apprentices, technicians and Technologists.

Jan 1, 1981

By R. C. J. Goode

"In my Presidential address last year `The Institute in Retrospect and Prospect', I briefly reviewed the past activities of our Institute, I commented on the dynamic growth of the mineral activity of this country and of the great contribution towards this growth made by members of this Institute. I maintained that there was still further growth to come, pointing out that our future would be very much dependent on the availability and skills of our mining and metallurgical men. This Institute had, therefore, a most important task ahead to ensure that this country would have the necessary skilled engineers to develop our mineral industry so that we would be able to compete successfully in the wide world. In my address I highlighted many of the major achievements of our members and of our Institute. In today's review, I have no wish to repeat myself and I would, therefore, ask members and visitors to regard this review as complementary to my presidential address. I must also refer you to the very full resume of our affairs written for a special brochure in March, 1944, by E. H. Johnson, a founder member, on the occasion of our 50th Anniversary. There is no need to repeat what was given there, rather I will attempt to bring that history up to date. Our Institute was founded under the name of Chemical and Metallurgical Society of South Africa on 24th March, 1894, by a group of chemists and metallurgists The name was changed to Chemical, Metallurgical and Mining Society of South Africa early in 1903, and in July, 1956 became The South African Institute of Mining and Metallurgy. We were not the first technical organisation in South Africa, the S.A. Association of Engineers and Architects having been formed in 1892. In that year also the British Institution of Mining and Metallurgy started in London. A chronological table of some of the more important societies is as follows: British Societies: Society of Apothecaries 1617 Royal Society 1660 Geological Society 1807 Institution of Civil Engineers 1818 Institution of Mechanical Engineers 1847 Institution of Chemistry 1877 Institution of Mining Engineers 1889 Institution of Mining and Metallurgy 1892 Other Societies: Mining Society of Nova Scotia 1887 S.A. Association of Engineers and Architects-later the S.A. Association of Engineers which amalgamated with the Transvaal Institute of Mechanical Engineers 1892 Australasian Institute of Mining and Metallurgy 1893 Geological Society of South Africa 1895 South African Society of Electrical Engineers-disbanded 1904 1897 Mechanical Engineers' Association of the Witwatersrand-later, the

By R. Kerby, T. R. lngraham

The rates of cadmiuln cementation from buffered solutions were studied on both the cylindrical and circular faces of a rotating zinc disk. The activation energies are equivalent on both surfaces, but the rate is more rapid on the cylindrical face. At higher temperatures and at pH values above 6.4, the rate of deposition increases because of an increase in the cathodic area of the deposit. The rate may also be increased by decreasing the thickness of the diffusion layer by rapid stirring. The presence of small amounts of copper, cadmium, lead, iron, or aluminum in the zinc does not affect the cementation rate, but when srnall amounts of copper, cobalt, and arsenic were present in the solution cadmium deposition ceased shortly after it started. Small amounts of copper in solution become cemented with the cadmium to form a coarse deposit of Cd3Cu. When zinc ores containing cadmium are processed for electrolysis, the cadmium appears with the zinc in the leach liquors. Because of the discharge potential of the cadmium ion and the hydrogen overvoltage on metallic cadmium, the cadmium ion must be removed prior to zinc electrolysis to prevent its codeposition. Cadmium is usually removed from acidic zinc sulfate solutions by cementation on zinc. When zinc sheets are used with the appropriate conditions of pH and temperature, a finely divided, high-purity cadmium powder is obtained; it floats to the surface with attached hydrogen bubbles and, after careful washing, may be processed directly to a marketable product.' The reaction on zinc sheets is relatively slow because of the limited amount of exposed cathodic area on the sheets. A much more rapid reaction is obtained when zinc powders are stirred into the solution, but this procedure does have a potential disadvantage: some unreacted zinc may be trapped in the cemented cadmium and thus lower its grade.1 The equilibrium constant at 25°C for the displacement of cadmium by zinc is of the order of lo", which indicates that at equilibrium the displacement would be essentially quantitative and no back reaction need be considered. This indication is not entirely true, however, because in the presence of oxygen any loose cadmium which is out of contact with metallic zinc tends to redissolve after cementation.' The overall effect is much the same as that to be expected if the equilibrium constant were much smaller. Previous experimental work on cementation reac- tions3 is in general agreement that the rates of cementation usually follow first-order kinetics. The metal on which cementation occurs is considered to consist of anodic areas from which metal dissolves and cathodic areas onto which the reactive metal is cemented. For the reaction to continue, the cemented deposit must remain open and porous for the removal of ions. Usually, the deposited metal influences the rate of cementation; when it blocks the pores in the deposit, the rate of cementation will be decreased. Alternatively, when the cemented metal grows as den-drites or as coarse powder the cathodic area is correspondingly increased and the rate of cementation increases,3 Thus, it is only during the initial stages of cementation, prior to the development of deposit effects, that the kinetic behavior of the reaction may be studied without ambiguity. In this paper, experiments will be described for cementation of cadmium from dilute solutions onto the surface of a rapidly spinning zinc cylinder. The effects of ionic concentration, disk rotation speed, temperature, and impurities will be described. APPARATUS AND PROCEDURE The apparatus used for the experiments was described in a previous paper.4 It consisted of a 2-liter vessel in which the contents were protected, against oxidation, by a stream of prepurified nitrogen. The vessel was immersed in a water bath which controlled

Jan 1, 1970

By George A. Guess

The increasing demand for greater speed and more accuracy, in making daily assays of ores and products from mills treating material containing but very small quantities of lead and copper, has caused the older analytical methods to be supplanted by new ones devised to meet the needs of modern work. For " control" work in copper-analyses, I had, previous to the present equipment, introduced in my laboratory the ordinary electrolytic method, using hollow cylindrical electrodes; and with these I began a series of experiments in determining the lead-content of daily mill-samples and controls. The results, proving accurate and satisfactory, I then devised, with Mr. H. E. T. Haultain, a cheaper electrode than the ordinary jaCket-electrode, which costs from $15 to $20,—the expense of the older form making the installation of many units very costly. The form of cathode finally adopted as the most satisfactory, shown in Fig. 1, is cut from 0.001-in. platinum foil. It is 12.5 cm. long, and is divided into a blade 4 cm. wide and 6.25 cm. long, and a tongue 0.7 cm. aide and 6.25 long, the immersion area being 50 sq. cm. and weight 1.5 grams. The blade is first sand-blasted and then corrugated lengthwise, in order to impart the necessary rigidity. Strips of platinum foil 0.001 in. thick, 12.5 cm. long and 0.5 cm. aide, having a median corrugation, form the anodes. Three electrodes are used in each cell; one anode in the middle and one cathode on each side of the anode. These electrodes are connected to slotted aluminum terminals, in which they are held by contact pressure. The terminals are 5/16in. rods, projecting 2 in. horizontally in front of the wall of the cabinet; at the back the middle electrode (anode) is connected with one pole of the current, and the two outer ones (cathodes) with the other pole.

Jan 1, 1906

By C. G. Dunn, F. W. Daniels, M. J. Bolton

IN recent papers on interface energies in metals¹,² the concept of an equilibrium of forces has been used in the measurement of interfacial tensions. Mathematically the equilibrium of three forces is given by the relations: where the 2's are the interfacial tensions (interface energies per unit area of interface) of three phases or grains meeting at angles 21 22 and 23 (212 relates to the 1-2 boundary formed by grains 1 and 2;223 to the 2-3 boundary, etc.). If these relationships are valid, one can calculate relative values of the interface energies from measured boundary angles on specimens which have been brought to equilibrium. Since Eq 1 may be derived through a mathematical process of minimizing the grain boundary energy under the restriction that the ?'s be independent of boundary orientation: the concepts of surface tensions and equilibrium of forces are not particularly essential. To deal with the general case involving dependence of boundary energy on boundary orientation, it becomes desirable to drop certain concepts formerly held (namely that energy per unit area is identical with force per unit length or surface tension) and to use the energy concept alone. It is appropriate, therefore, to use E in place of ? in deriving and using the more general equations that express the anisotropic nature of the grain boundary energy. Herring3# ' recently has derived the required general equations using the principle of minimization of energy. Specifying the boundary orientations in terms of angles (4) measured with reference to crystal axes within the grains, Herring's equations take the form E23 + E21 cos?8 + E12 cos?2 — sin ?12 + sin?2-?E12/?12 =O [2] where the partial derivatives are measured in the direction of counterclockwise rotation of the boundaries. Eq 2 implies that an infinitesimal displacement of the triple point along the 2-3 boundary produces no change in the boundary energy. Similar equations apply for infinitesimal displacements along each of the other two boundaries. From such equations Herring obtains the following general relationship (1 + E1 E2) sin?8 + (E2 — E1) cos?3 ________ E38______________ = (1+ E2 E8) sin ?1+ (E3— E2) cos ?1 __________^5____________[3] (1 + E sin ?2, + (E1 — E8,) COS ?2 1 E28 where E1 = 1/E23- E25 and PC and c8 have similar expressions. It is apparent that Eq 3 reduces to Eq 1 when the c's vanish. Eq 3 also reduces to Eq 1 when the E'S are all equal. Shockley and Read' have pointed out one limitation to these equations. When E plotted versus 4 appears as an energy cusp, as their theory requires, for example, for the energy near a twin boundary position, then Eq 3 (and therefore Eq 1 also) no longer applies if one boundary is in the minimum energy position. One of the equations of form Eq 2, however, applies if the infinitesimal displacement is along the boundary associated with the energy cusp. From the foregoing treatment it will be apparent that equilibrium angles alone are not sufficient in general for calculating relative interface energies.

Jan 1, 1951

By P. de Vitry, Oliver Bowles

THE conventional wire saw, introduced in the slate district of Pennsylvania by the Bureau of Mines in 1927, and used thereafter with remarkable success, consists of a three-strand steel cable having a diameter of 3/16 or 1/4 in. The equipment, methods used, and accomplishments have been described in previous reports.1-7 Similar wire saws have been used extensively in Europe, in quarries and in shaping blocks and slabs. During the period 1932-1937, competition in European marble quarries was keen, prices were declining, and orders were not abundant. When orders were received, there was generally an urgent call for speedy delivery. Because of the diversification of demands, it was impossible to maintain in stock marbles of the color, size, and thickness called for, therefore the material generally had to be fabricated after the order was received. The wire saw enabled stone mills to fill such orders promptly. With skillful handling, 7/8-in. slabs could be cut accurately and rapidly with this equipment. It was found, however, that, as the three-strand wire became worn, the cutting speed dropped rapidly and the cut became less accurate. To overcome these difficulties the junior author of this paper, after much experimentation, developed a new type of wire consisting of a single ribbon-shaped strand, twisted as shown in Fig. 1. To ensure straight sawing, the twist of the ribbon is reversed from right to left and vice versa every 25 ft. The reversal of the [ ] twist is shown in Fig. 2. This is not a new feature; it has been used to advantage with the three-strand wire both in Europe and America for several years. However, some difficulties arise in splicing the three-strand reverse-twist wire, and the claim is made that cutting is less accurate as the wire becomes worn. To make an endless belt, the ends of the single-strand wire are brazed together with

Jan 1, 1941

By Noel Stearn

WHEN the Age of Machinery was suddenly thrust upon civilization about the beginning of the nineteenth century, an unprecedented demand for mineral resources sprang up. This demand brought about the rapid development of the known ore deposits and the discovery of such other deposits as could be encountered by energetic and canny pros-pectors. Thus in the countries now reasonably ac-cessible nearly all orebodies have been located except those which are totally concealed even from the eyes and "senses" of experienced and expert prospectors. The high rate of exhaustion of known ore deposits and the necessity of looking farther and farther ahead for raw materials as a matter of insurance on the stu-pendous capital outlays involved in mining, develop-ment, and conversion operations, have resulted in excep-tional activity in three different fields of effort. The first is purely geographic. Prospectors are now pene-trating the few hitherto inaccessible regions in the hope of stumbling upon exposed ore deposits or locating visible indications of their presence. The second is chemical. Industrial chemists and metallurgists are seeking to facilitate the exploitation of lower grade ores to find methods of recovering valuable metals from common substances. In the third field of effort. lie the activities of the economic geologist and the mining engineer, who en-deavor to locate concealed ore deposits, which would remain hidden from the prospector, no matter. how expert or conscientious he might be. Obviously the task which such a man must face is both exacting and indefinite, and the tools which he has heretofore been permitted to bring to it are, for the most part, abstract-a knowledge of certain fundamental princi-ples and processes involved in the origin, occurrence, structure, and distribution of deposits. of natural re-sources and of the rocks which form the environments of those deposits, and a process-of reasoning by analogy supplemented by the .use of the diamond drill, or such artificial exposure as the test pit, trench, shaft or tunnel. His primary efforts are usually bent on acquiring a knowledge of the distribution of the rocks-as accurate -is possible-which is a natural prerequisite to any conclusion as to how they became so distributed. Over very extensive areas, however, he meets. the extreme difficulty of being unable to see the rocks, except at rare intervals, since .they have been concealed by an overburden of glacial material, of alluvium, of soil, or of other rocks.

Jan 9, 1928

By O. G. Bell

While all of the Southwest Texas fields lie within the Gulf Coastal Plain this area may be divided into three subdivisions—the Coastal Plain zone proper, the Reynosa Escarpment zone, and the interior zone. The Coastal zone includes that strip adjacent to the Gulf of Mexico and . extending inland for a distance of about 60 miles and includes the Palo Blanco, Palangana, Piedras Pintas, Kingsville, Agua Dulce, Saxet, White Point and Refugio fields. The Reynosa Escarpment zone includes a Pliocene overlap over older Tertiary sediments lying west of the Coastal zone. The western margin of the Reynosa formation forms a more or less well-defined westward facing escarpment with which the so-called Reynosa Escarpment fields are indirectly related. These fields include those in eastern Zapata, eastern Webb, western Jim Hogg, western Duval, McMullen, Live Oak, Bee, Goliad and Victoria counties. The interior zone includes these fields west of the Reynosa Escarpment which are not in any way related to it and are on separate types of structure. Production data by fields and wells are shown in Table 1. Roma.—During 1928 the Texas Co. completed two small gas wells at 198 ft. on the Roma Structure near the town of Roma on the Rio Grande in Starr County. This gas is of no commercial importance but was used for fuel in drilling other deep tests on this structure. Three dry holes ranging from 3600 to 4200 ft. were drilled; then their No. 4 Guerra, the fourth deep test, was completed during December as a small producer of 37" Bé. oil from a sand at 3560 to 3590 ft. No production was marketed during December but arrangements were being made to handle the output from this well during 1930. This is the first commercial producer in Starr County. Driscoll.—In 1929, Robert Driscoll discovered gas on his Santa Rosalia Ranch in Duval County while drilling water wells. Two sands were developed, one at 2400 ft. and another at 2936 ft. and several gas wells were completed in each, ranging in volume from 15,000,000 to 40,000,000 cu. ft. and in reservoir pressure from 500 to 1,000 Ib. Early in January of 1929, Mr. Driscoll's No. 14 Fee was completed as a 50-bbl. oil producer at 2894 ft. Two other oil producers were completed early in 1929. Mr. Driscoll's death early in the year curtailed develop-

Jan 1, 1930

By Terra Dinamica, Frank Lucca

This paper discusses blast design for vibration control in tight construction blasting. Topics include blast pattern geometry, blast design formulas, loading, explosives & initiation selection, and utilizing borehole deviation equipment and lasers, and rules of thumb. The paper will also explore vibration prediction, neighbor relations, and related topics, such as blast plan submittal. Various projects from metropolitan construction blasting operations will be used as examples. Examples include blasting in the inner city, next to pipelines, and in housing developments.

Jan 1, 2005

By F. E. Steigert, A. H. Geisler

THE permanent magnet alloy comol, which contains 17 pct Mo, 12 pct Co, balance Fe, exhibits a precipitation reaction analogous to that at the iron end of the binary Fe-Mo system. The equilibrium precipitate, (P,), has a structure isomorphous with Fe,Mo, which is rhombohedra1 with parameters a = 8.97A and a = 3038.6&apos; according to the work of Arnfelt and Westgren.&apos; In the ternary alloy the parameters are a = 8.87A and a = 31°0.5&apos;. Oscillating crystal patterns of a single matrix crystal, M, in which P, was precipitated by slow cooling from 1300°C, showed that the orientation relationship of the two lattices is as follows: (110)P3 // (110)* (111)p3 // (110)m There are crystallites of P, in 12 different orientations in a single crystal of the parent solid solution. Microscopic examination shows that the crystallites are generally plate-like with their lateral dimensions parallel to (110) matrix planes. When precipitation in a supersaturated alloy quenched from 1300°C progressed isothermally at temperatures between 600" to 800°C, the evolution of the P, structure could be traced. Diffuse diffraction effects in Laue patterns provided early evidence of the precipitation process. Analyses of these by a previously described technique2 showed that they corresponded to rod-like elements parallel to <110> matrix directions in reciprocal space. With further aging to promote growth of the precipitate, the rod-like elements contracted to points in reciprocal space for normal Bragg reflection from the precipitate as shown by the left diagram in Fig. 1. Thus the diffuse scattering was attributed to the small thickness of the plate-like particles which was inadequate for sharp diffraction. When the precipitate particles were first thick enough to give normal diffraction their structure was different from that of the equilibrium precipitate, P,. The first structure, P1, presumably is a coherent transition struc-

Jan 1, 1952

By C. E. Shoenfelt

The outstanding development in the Rocky Mountain region for 1937 was the discovery of oil on the Wilson Creek dome in Rio Blanco County, Colorado, in the Morrison formation of Jurassic age. This discovery opens up a vast territory to exploitation and definitely establishes the western slope of Colorado as one of the region&apos;s more important oil areas. In former years, a large number of structures on the western slope were tested dry in Upper Cretaceous rocks but are now believed to hold possibilities in older formations, and a number of such structures are in line for drilling in 1938.

Jan 1, 1938

By M. J. Nicol, G. Cromberge, C. A. Flemming

A relatively simple rate equation for the kinetics of the absorption of gold from cyanide solutions onto activated carbon was lI5ed as the basis in the development of a model for multistage carbon-in-pulp and carbon-in-Ieach absorption circuits. The model was used in the prediction of both the steady-state and the transient behaviour of the absorption process, and the results were found to be in reasonable agreement with those observed in an extended pilot-plant campaign. A number of practical implications of the model are discussed, and an assessment is made of the economic consequences of the various process options available for the design of a carbon-in-pulp plant.

Jan 1, 1983