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By Lawrence K. Nordell

This paper reviews practices used In the selection and sizing of belt conveyors and stacker systems commonly used in crushing and grinding plant facilities. Historical and modern methods of sizing this equipment are presented. The new methods Include: 1) probability theory applications for establishing component reliability, 2) "Monte Carlo" simulation techniques used in evaluating alternative system designs and in establishing service factors and corresponding availability Indices of each system, 3) quantifying the system and component operating characteristics using computer assisted modeling tools simulating rigid body and elasto-mechanic behavior for starting and stopping large and/or complex belt conveyors.

Jan 1, 1982

By W. C. Shanks

Seventeen deeps, which contain hot or cold brines and/or metalliferous sediments, have been discovered in the axial rift zone of the Red Sea. Metalliferous activity results from the unique geological setting of this incipient ocean basin: oceanic crust intruding in a central rift zone flanked by thick evaporite sequences. Brine pools tend to occur in structural depressions where- transform faults intersect the spreading axis. The most significant metalliferous occurrence is in the Atlantis II Deep, which contains approximately 227 Mt (dry weight) of metalliferous sediment which averages 1.04% Zn and 0.28% Cu. Higher potentially economic grades (3-6% Zn, 1% Cu, 50 glt Ag) occur in the Southwest Basin of the Atlantis II Deep, comprising total metal tonnages of 1.7 Mt Zn, 0.4 Mt Cu, and 5000 t Ag. The Pre-Pilot Mining Test conducted in 1979 raised 15 000 m3 of mud by a slurry process and demonstrated the feasibility of mining, concentration by froth flotation, and tailings disposal at sea. A Pilot Mining Test is scheduled for 1983-1984. The metalliferous discoveries in the Red Sea provide a model example of deep marine mineral exploration. Detailed mapping of bottom bathymetry and brine-interface reflectors using a high-resolution narrow-beam echo sounder has been the most effective exploration tool in the Red Sea. Followup coring has discovered additional metalliferous deposits in basins without present-day brines, and potential exists for additional discoveries. Geochemical exploration using heavy metals values in sediments (iron, manganese, zinc, copper, and mercury) and sulfur isotope values of sulfides are considered to be the most promising techniques for discovery of currently inactive deposits. Positive sulfur isotope values in the range I to 17 are an indication of hydrothermal sulfides in the Red Sea, and there is considerable contrast from back- ground bacteriogenic sulfides ( - 10 to - 45).

Jan 1, 1983

By T. Turner, C. L. Zimmerman, U. Kappus

The purpose of the project is to divert flood flows of North Potato Creek. The project is located in the southeast corner of Tennessee near Copperhill, approximately 160 km north of Atlanta, GA. The project consists of: a 28-m high dam, a 0.9-m diam outlet conduit, an emergency spillway, and a 4.0-m diam hard rock transbasin diversion tunnel. This flood-water management system was part of Cities Service Co. mine safety program for the Cherokee ore body, which is partially located within the creek channel. The following paper describes the entire project development from feasibility studies to design and construction management.

Jan 1, 1981

By Werner Schwartz, Wolfgang Haase

Lead sulfide concentrates, which may include other lead concentrates, are sintered on an up-draught sintering machine without the addition of any diluting agents or fluxes. Subsequently they are melted in an oil- or gas-fired rotary furnace. The sintering and melting processes are based upon the following roast-reaction: PbS + 2 PbO = 3 Pb + SO, PbS + PbSO, =2 Pb + 2 SO, For obtaining a lead bullion free from sulfur, the sintering process is carried out in such a way that the sinter product contains a small amount of excess oxygen above that to react with the sulfides. At the end of the melting process, when the reactions are finished, the remaining small amount of oxide residues is reduced with coal to which a certain percentage of soda ash (about 1 pct of the lead bullion) is added. For the lead smelting process described neither coke nor fluxes—except soda ash—are required. This process is being utilized by a European smelter successfully and with a high lead recovery. The consumption figures for the smelting of 100 tons per day of lead concentrates are indicated. The lead content of the lead concentrates from modern ore dressing plants ranges from 65 pct to above 80 pct. In most lead smelters of the world these concentrates are smelted in a blast furnace. For blast-furnace smelting the concentrates have to be desulfurized and agglomerated by sintering. A requirement for the perfect operation of a down-draught sintering machine and of a blast furnace is a maximum lead content in the feed of 40 to 45 pct. For this reason, some lead concentrates have to be diluted by adding return slags, limestone, and possibly iron oxide and sand. As an example, 100 tons of lead concentrate with 72 pct Pb would contain 13.5 tons of gangue (including the zinc). To produce a perfect sinter with 42 pct Pb it would be necessary to add 70 tons of flux and return slag, more than five times the original weight of the gangue, to the sinter mix and blast-furnace charge. A correspondingly large amount of coke would be required in order that all of these materials reach the heat of formation and the melting temperatures of the slag (1200" to 1400°C) inside the blast furnace. The roast-reaction process presents a possibility for lead recovery without dilution of the concentrates. In this process the concentrate mixed with coal is placed upon a Newnam-hearth and air is blown through nozzles into the heated mix. AS a result metalllic lead and a relatively great amount of so-called .'Grey Slag" with a lead content of 25 to 35 pct are formed. The slag is sintered to eliminate sulfur and, after addition of the requisite fluxes, treatt:d in a blast furnace. Owing to the poor recovery of lead from the hearths and to the unavoidable heavy hand-work plus the risk of poisoning this process is utilized in very few 112ad smelters today. Since in mxny countries of the world coke is expensive and difficult to obtain, it appeared feasible to use the principle of the roast-reaction by modern sintering and melting methods with recovery of the lead in electric, or oil, gas, or coal-fired furnaces. Two processes are utilized on an industrial scale: A) Lead smelting in the electric furnace of the Bolidens Gruv A/B in Sweden, as described by S. J. Walldcn, N. E. Lindvall, K.G. Gorling, and S. Lundquist. B) The self-fluxing lead smelting of Lurgi Gesell-schaft fiir Chemie und Huttenwesen m.b. H., Frankfurt a M, Germany, which is described in this paper. In the Boliden process referred to above the sinter mix is pelletized by enveloping return fines with layers of flue dust, limestone powder, and dried galena concentrate. The roasting and agglomeration are carried out on a down-draught machine, and a slight excess of sulfur is left in the sinter product. During the smelting in the electric furnance the roast-reactions occur and a slag poor in lead and a sulfur bearing lead are formed. This latter is subsequently oxidized in a converter to obtain lead bullion and dross. The Lurgi-process achieves the maximum possible extent of the roasting reaction on the sintering machine. The wet flotation concentrates are blended with return fines (lead content 70 to 80 pet), any existing flue dusts and lead slimes—but without the

Jan 1, 1962

By A. B. Kinzel

SILICON and its metallurgical uses have been the subject of speculation since the earliest days of modern civilization. The early philosophers, Theophrastus and Pliny, believed that silica was a special form of ice, an opinion that was not seriously challenged until the seventeenth century. The first comprehensive view of the nature of silica was advanced by Lavoisier in 1787. He assumed silica to be an oxide of an unknown metal. In 1808 Berzelius produced ferrosilicon by heating silica, iron and charcoal. Probably the first produc¬tion of crystallized silicon was in 1854 when H. St. C. Deville accidentally produced the material while electrolyzing a double chloride of aluminum and sodium containing siliceous impurities. It is not strange that the early investigators should have given so much attention to silica and silicon, because of the great natural abundance of the former. Although silicon does not exist in the elemental state in nature, it has been estimated that the lithosphere contains approximately 60 per cent silica; quartz and rock crystal are found in practically every part of the world.

Jan 1, 1933

By Z. F. Oszter, D. Vincent, W. K. Behrands

With the expansion of open pit operations, belt conveyors are going to be used in the 13 608 to 18 144 t/h (15,000 to 20,000 stph) capacity range, which calls for a review of some of the horsepower calculation methods. This paper presents methods (based on German research data, field tests and theoretical considerations) for the evaluation of the Ky factor in the CEMA formula for belt conveyors of large carrying capacity, which fall beyond the limits of the data given in tables in the CEMA book. (The CEMA limits are 407 N\\m (300 lb ft) and Tave = 7.3 Mg (16,000 lb). At these large loads, the impression resistance of the belting on the idlers plays a major role, which in turn influences the magnitude of the drive horse power required. An example will illustrate the order of magnitude difference of the horsepower values obtained by using a conventional calculation method and the suggested method, as well as the beneficcia1 influence of the 4-roll idler in comparison to the standard 3-roll unit for a large caving capacity belt conveyor. This paper concerns itself with the analysis of the resistance to motion of belt conveyors, emphasizing the evaluation of the frictional resistance to motion due to load and belt pressure on the idlers and the flexing resistance of the belt and material when passing over the idlers. In the case of long and heavily loaded belt conveyors, the aforementioned resistances reach extremely high values calling for close analysis of the phenomena, presently not calculable with normally used formulas. This paper establishes correlation between experimental and empirical data presenting practical formulas a tool for the designer of high-capacity belt conveyors. The application of the formula is illustrated in an example in the Appendix.

Jan 1, 1981

By William Hurst

THE content of this paper is a presentation of the diffusivity theory for the calculation of the water drive on an oil reservoir in which b the history of reservoir pressure with time are the essential parameters for the determination of the rate and cumulative water encroachment into a field. The paper is divided into two parts-the main portion and appendix. The main body is essentially the application of the principles underlined here to actual field data. It consists of the work plots of the radial-flow case, and includes a discussion of an illustrated problem for which the water-drive calculations are treated in conjunction with the volumetric-balance equation. The appendix is a mathematical treatment of the linear, radial, and spherical cases of water influx into a reservoir.

Jan 1, 1942

By R. W. Harper, M. C. Fuerstenau, J. D. Miller

Data were obtained with hematite with octyl hydroxamate and oleate as collectors to determine the mechanism of collector adsorption and also to establish the roles that conditioning time and temperature assume in this system. The presence of hydroxy complexes of iron are apparently necessary for chemisorption of collector to occur, and it appears as if extended conditioning times and elevated temperature promote greater dissolution of the mineral and hence greater concentrations of hydroxy complexes. Data were also collected with two natural hematitic ores. With one ore that was ground to 70% - 15u, an addition of 0.4 lb per ton hydrox-amate resulted in a final concentrate recovery of 86% at a grade of 64% iron. Satisfactory concentrate grade could not be obtained with fatty acid under these conditions. The effect of conditioning time prior to the addition of collector was also examined with another ore. When the ore was conditioned for 3 min, 19% of the iron was recovered in the concentrate at a grade of 67% Fe. With a conditioning time of 7 min, 73% of the iron reported to the concentrate at a grade of 62% Fe. These products were obtained with an addition of 0.2 lb per ton hydroxamate. This ore also responded well to flotation with fatty acid. The use of potassium octyl hydroxamate as a collector for iron oxide has been the subject of an earlier study.1 From this initial study, it was suspected that hydrolysis of surface ferric iron was involved in collector adsorption. More recent work in other systems has shown that slight mineral dissolution, followed by hydrolysis of cations common to the mineral lattice, is apparently necessary, and that adsorption of these hydroxy com- plexes probably occurs prior to the adsorption of collector. In view of these facts, work has been continued on the hydroxamate-hematite and oleate-hematite systems to gain better insight into the mechanisms of collector adsorption on iron oxide. Microflotation experiments in conjunction with infrared analysis were used in this regard. In addition it was felt necessary to establish more clearly the responses that can be obtained from natural ores when hydroxamate is used as collector as compared to those obtained when fatty acid is used. Experimental Materials and Techniques Pure potassium oleate, potassium octyl hydroxamate, synthesized from hydroxylamine hydrochloride and methyl octanoate, and a distilled Tall Oil were employed as collectors. Conductivity water was used in the

Jan 1, 1971

Jan 1, 1938

Jan 1, 1938

Jan 1, 1969

By S. R. Zimmerley, John Gross

The method of measurement of surface on quartz particles was given in a previous paper.' With such a method the relation of surface produced in crushing quartz can be compared to the work in crushing without recourse to sieve sizing or microscopic measurement. In crushing, the work input must be known with a fair degree of accuracy. With crushers, rolls, ball mills, and similar apparatus the measurement of the work in crushing is subject to possible errors, due to friction in the transmission as well as in the machine itself. Moreover, relatively large quantities of material must be crushed to get an average figure. In the selection of a method of crushing, simplicity in design and operation was desired and this was most readily obtained by the use of a free-falling body. A description of the apparatus embodying this principle is given herewith. The Crushing Device The apparatus used is shown in Fig. 1 and in cross-section in Fig. 2. The material to be crushed is placed in the crushing chamber C in the steel mortar M. The mortar is 3 in. dia. by 3 in. high. Two mortars are used, one having a crushing chamber 1 in. dia. by 36 in. deep, with a capacity of 4 g. of quartz, the other having a crushing chamber 1 1/2-in. dia. by % in. deep, with a capacity of 12 g. of quartz. The position of the mortar is adjusted by means of three centering screws A. The steel plunger P, which fits neatly into the chamber, is placed on top of the material to be crushed. Plungers of different lengths were tried and as they were found to give practically identical results the length adopted was equal to the depth of -the chamber. The mortar rests on a solid steel base B but is separated therefrom

Jan 1, 1930

By J. R. Long, T. R. Graham, R. S. Dean

FOLLOWING the development of elec¬trolytic manganese production by the Bureau of Mines, an extensive program was planned to study the character of this high-purity product and its possible utilization in various alloy combinations. Previous work reported in the literature concerning alloys containing substantial amounts of manganese dealt largely with material prepared from relatively impure grades of the metal, and in many instances the impurities thus introduced did not permit true evaluation of manganese as an alloying element. One phase of the Bureau's program included a general review of the system and the establishment of the physical properties of copper-manganese-zinc alloys, using electrolytic manganese, and with particular emphasis directed to com¬positions within the alpha solid solution area. A number of reports of the work on alloys in this system, giving specific data concerning the equilibrium system and some of its alloys, have already been published. One study1 established the alpha solid solution area at various temperature levels and composition ranges up to 50 pct manganese. Other investigation reports presented the properties of selected alloys; namely, a 65 pct copper, 10 pct manganese, 25 pct zinc alloys' a sensibly white manganese brass composed of 70 pct copper, 20 pct manganese, 10 pct zinc,3 and a series of alloys with a constant copper content of 60 pct and 5 to 25 pct manganese, balance zinc.4 In these reports tensile properties as influenced by cold-working and subsequent annealing were given in detail. Additional data are now available on other alloys of the alpha region up to 50 pct manganese, and these, together with previously published information, are sufficiently complete to establish the relationship between properties and composition for this portion of the ternary system. The present report is a summary of the tensile properties of wrought alloys in the form of sheet and rod stock. The summary is necessarily limited to data for only one condition of cold-work and a single annealing temperature, since a complete exposition of all the data available would be too extensive for this presentation. Nevertheless, it is possible to make a reasonable approximation of the tensile properties in other conditions of cold-working and annealing by a correlation of the data previously presented on specific alloys and the data given here.

Jan 1, 1947

By R. J. Murphy, N. J. Grant, J. W. Dowding

A large number of blast furnace slag-metal tests were examined to determine if the manganese reduction could be used as a primary indicator of the degree of oxidation or reduction of the slag and of its desulphurizing power. Slag basicity and temperature were also evaluated. Two laboratory heats were made and sampled prior to reaching equilibrium to check blast furnace data. IN a recent investigation of the factors affecting desulphurization in the blast furnace, is was evident that manganese reduction appeared to parallel the course of desulphurization. Grant, Kalling, and Chipman1 pointed this out in a series of time studies utilizing closely controlled laboratory melts. Fig. 1 is a composite plot of sulphur removal and manganese reduction as a function of time under two slags of different basicity. Manganese reduction appears to approach equilibrium at approximately the same rate as does sulphur. It was also demonstrated that the addition of oxygen to the slag, as manganese oxide, caused a sharp reversal of sulphur from the slag to the metal.' It has been shown that "Excess CaO" was a primary factor in measuring the degree of desulphurization under ideal reducing conditions,1,2 the following reaction being representative of the process: CaO (slag) + S + C (solid) = CaS(slag) + CO (gas) It was also evident that a second reaction could drive the sulphur from the slag into the metal. A suggested reaction was' CaS (slag) + 0 = CaO (slag) + S Any change in the oxidizing power of the system would thus affect both the sulphur and the manganese without causing any change in the calculated basicity of the slag. "Excess CaO," "Excess Base," and other similar basicity values, under such oxidizing conditions, would therefore not be the best measure of desulphurizing power; instead, as was shown by and Chipman" he oxygen content of the slag at low oxygen levels would be the controlling factor. Unfortunately, the extent to which FeO is reduced in the blast furnace makes it difficult to utilize slag FeO as an accurate indicator of the degree of oxidation. By comparison, manganese reduction in the blast furnace proceeds more slowly and is generally only about 40 to 70 pct complete. manganese, which is present in significant amounts and is readily analyzed, offers an opportun-

Jan 1, 1954

By C. H. Ault, D. D. Carr

Four counties in Indiana- LaPorte, Vigo, Vanderburgh, and Switzerland-have potential for deep underground limestone mining because they are in or near high population areas and have no surface-mineable limestone deposits. The principal markets are Gary-South Bend, Terre Haute, Evansville, and Cincinnati. Mineable seams suitable for aggregate are 120-150 m (400-500 ft) below the surface in LaPorte and Vigo Counties, about 90 m (300 ft) below the surface in Switzerland County, and about 600 m (2,000 ft) below the surface in Vanderburgh County. Some deposits are also suitable for high-purity uses or for cement raw materials, which enhances their potential for exploitation.

Jan 1, 1983

By J. H. Reynolds

The possibility of using a semiconductor, metal, semiconductor structure as a light detector is discussed. A brief theoretical argument is presented which predicts that this structure should have pho-toresponse characteristics similur to those of a metal-semiconductor diode, but with the magnitude of the current increased by a transistor gain factor. Measurements made at low frequencies on a particulur S-M-S device agree u~th this prediction aizd shoul that significant gain factors are attainable. The current gain is substantially higher than that predicted for the metal base transistor. It is proposed that the operation of these units is more closely approxinzated by the metal-gate model which predicts higher current gains. A qualitative discussion of its high-frequency performance indicates that detection of light modulated at microwave frequencies by a S-M-S deuice is possible. ADVANCES in the technology of chemical vapor deposition'-4 have made it possible to form a S-M-S structure consisting of a thin metallic layer sandwiched between layers of single-crystal semiconductor. It has been proposed5-7 that, if the metal layer is made sufficiently thin, this structure could be used in an amplifier having several advantages over presently available transistors including higher-frequency performance. Calculations8 predict that the maximum gain-bandwidth product is nearly an order of magnitude higher than that of a bipolar transistor having the same geometry. Maximum oscillating frequencies in the microwave range are predicted. Electrical measurements made on S-M-S devices have shown that, although the theoretical frequency characteristics are not presently attainable, current and power gain is obtained. Another possible application of the S-M-S structure is its use in a light detector. This structure is a three-layer relative of the metal-semiconductor diode. Light detection using M-S diodes is the subject of considerable present interest. They are known to have a short response time and the ability to detect light having a photon energy below the semiconductor bandgap. In this paper, the mechanism by which S-M-S photocurrent is generated is discussed. An expression is derived which shows that the response characteristics are similar to those of a M-S diode, but that the magnitude of the current is increased due to the transistorlike behavior of the device. The results of low-frequency response measurements on a particular S-M-S structure are presented. These agree with the theoretical predictions and show that significant gain factors are attainable. A qualitative discussion of the high-frequency characteristics is presented which predicts that detection of light at microwave frequencies by a S-M-S device is possible. THEORY In this discussion, the photocurrent, iT, measured across terminals attached to the semiconductor emitter and collector layers is related to the current pho-toemitted from the metal base layer. The latter will be referred to as the primary photocurrent. The behavior of the primary photocurrent is determined by the characteristics of the two metal-semiconductor diodes. The diode photoemission is illustrated in Fig. 1, which shows the emitter and collector potential barriers. The metal thickness has been greatly exaggerated. As will be discussed later, the actual barrier shape can be much more complex, but this diagram illustrates the essential features of the photoemission process. An absorbed photon having an energy greater than the barrier height can emit an electron into the emitter or collector. Since this process is discussed

Jan 1, 1968

By William R. Webster

I have continued the investigation of the Pottstown Iron Com pany's basic Bessemer keel plates on the line referred to in my paper of last October (Trans., xxi., 766)) and have added a study of the hardening effects of sulphur, which were not taken into account at that time. The results are so encouraging that I now give them in full. For some months we have graded all the steel at these works by the table given in my former paper, and checked the grading by the forging-tests as described in the paper of Mr. Joseph Hartshorne, read at the same meeting (Trans., xxi., 748). The steel thus graded was bloomed for the plate orders. Then one slab was rolled into a plate for the order, and a tension-test was made of this plate. By the result of this tension-test we were guided in rolling the balance of the heat. Out of several hundred heats graded in this manner, 95 per cent. met the requirements of the orders in every respect, and were accepted; but these results will no doubt be improved upon, when the influence of sulphur is also considered.. The hardening effect of sulphur seems to be about 500 pounds per each .01 per cent. of increase. In the table accompanying the pres ent paper, the ultimate strength with .06.5 per cent. sulphur agrees with the old table where sulphur was not considered; that is, for all steels with less than .065 per cent. sulphur we now get lower re sults, and for those with more sulphur, higher results. Making this allowance for sulphur, the assumed ultimate strength of a 3/8-inch plate of pure iron is reduced from 38,000 pounds per square inch to 34,750 pounds. With this as a basis, I have constructed my new table, giving each of the elements, carbon, phosphorus and manganese the same hardening effect as before, to wit : Carbon is credited with a constant effect of 800 pounds per each, 0.01 per cent. Phosphorus shows greater effect in high-carbon than in low-carbon steels. For 0.07 and 0.08 C, it has about the same effect as carbon, that is, 800 pounds for each .01 P. This increases to 1500 pounds per .01 P in 0.15 C steel, or nearly twice the effect of carbon. This

Jan 1, 1894

John P Hammond '59, President T C Frick '58, Past President Basil Kantzer '60. President-elect George R Gray '58, Vice-President Earl M Kipp '58, Vice-President G M Stearns, Treasurer Joe B Alford, Executive Secretary 800 Fidelity Union Bldg Dallas, Texas

Jan 1, 1957

Jan 1, 1883

By AIME AIME

COMMITTEES. LOCAL COMMITTEE.-R. C. Crawford, Chairman; Harrison W. Craver, Secretary; Julian Kennedy, Taylor Allderdice, E. W. Pargny, Charles L. Miller, W. H. Rea, S. A. Taylor, M. E. Wadsworth, W. A1. Henderon, A. C. Dinkey, W. L, Jones, E. L. Messier, George Mesta, J. H. Jones, G. H. Riley, S. L. Goodale, D. W. McNaugher. LADIES' COMMITTEE.-Mrs. Taylor Allderdice, Chairman; Mrs. Julian Kennedy, Mr. R. C. Crawford, Mrs. E. M. Herr, Airs. J. W. Marsh, Mrs. T. A. Mellon, Mrs. G. P. Bassett, Jr., Airs. D. M. Clemson, Mr. Charles L. Miller, Mrs. V. L. P. Shriver, Mrs. W. A. Bostwick, Mrs. A. C.. Dinkey, Mrs. A. P. Childs, Jr., Mrs. F. R. Dravo, Mrs. Hermon Griffin, Mrs. W. H. Nimmick, Mrs. F. H. Lloyd, Mrs. S. G. Cooper, Mrs. S. H. Church, Mrs. E. N. Ohl. The Institute Headquarters was established at the Hotel Schenley, where a bureau of information was maintained for the benefit of the visiting members and guests of the party during the time of the meeting. TECHNICAL SESSIONS. The first session, held Tuesday evening, Mar. 1, 1910, in the large lecture hall of the Carnegie Institute, was called to order by Harrison W. Craver, Secretary of the Local Committee. Mr. Craver introduced Dr. John A. Brashear, who extended to the members and guests a hearty welcome to the city of Pittsburg, to which David W. Brunton, President of the Institute, responded. The following papers were presented in oral abstract by the authors: Biographical Notice of Dr. Charles B. Dudley, by Dr. R. W. Raymond, New York, N. Y. Biographical Notice of William Metcalf, by Col. II. P. Bope, Pittsburg, Pa. Development of Hindered Settling Apparatus, by Robert H. Richards, Boston, Mass. (Illustrated by lantern-slides.) A Few Mining Districts in the Argentine Republic, South America, by Z. S. Beyl. (Illustrated by lantern. slides.)

Apr 1, 1910