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By Keith Contor

The concept of using simulators to train operators of vehicles is not new. However, the Bureau of Mines initiated these programs to determine if computer controlled training devices would enhance production and improve safety in the coal mining industry. Two prototype devices have been constructed, tested and are currently operational. The continuous miner and dragline operator training systems both incorporate full scale operator stations using operational controls and displays. The operator interacts with the visual system through the cab controls to perform basic tasks and develop skills required for startup, operation and shutdown of the mining equipment. Data pertaining to the concepts and techniques applied during the design, development and evaluation of the training devices are presented. Descriptions of trainer designs and visual systems for training equipment are presented and the results of the system evaluation are summarized.

Jan 1, 1983

By John B. Gustavson, Thornton L. Neathery

A geochemical survey was conducted in the gold district in Alabama. Eight old mines were found to be sufficiently large in tenor and tonnage to be economical today. Four of these appeared to be amenable to exploration for new blind deposits. A gaseous aspiration AA method was used on soil samples. The results indicate that arsenic, antimony, and zinc may be good pathfinders for lode gold and residual placers in the saprolite. Antimony and zinc display a high correlation coefficient at gold-bearing locations in contrast to non-mineralized areas. The low cost of this method could make it a tool for selecting detailed targets to be drilled and trenched in the saprolite. Outcrop sampling was found to be inefficient due to paucity of outcrops and lack of correlation between the trace elements and gold in the rock samples, due to extensive weathering. Schistosity changes and silicification, on the other hand, have been found to be helpful in exploration around granite plutons.

Jan 1, 1977

By S. H. Shepard

During the past year, a number of significant events have occurred in the nuclear industry. These include a surge in nuclear power plant orders, delays in nu- clear plant licensing and construction, increased environmental concern and the new Atomic Energy Commission nuclear fuel policy. These events, particularly the AEC stockpile release policy, have lead us to take this opportunity to update National Nuclear Corp.'s (NNC) appraisal of the outlook for the U.S. uranium industry.

Jan 10, 1972

By J. A. Lund, A. M. Lawson

THE structures of quenched eutectoid and hypereu-tectoid Fe-Cu alloys have been examined by X-ray diffraction and by optical and electron microscopy. The relevant portion of the Fe-Cu phase diagram is given in Fig. 1. Several values have been reported for the solubility of copper in a Fe at the eutectoid temperature, including 1.4 wt pct by orton' and 2.13 wt pct by Wreidt and Darken.2 Alloys containing 4.8 and 7.5 wt pct Cu have been prepared from two batches of Ferrovac E iron (0.005C and 0.013C) and electrolytic tough pitch copper (99.90 Cu). Specimens of dimensions 0.8 by 0.8 by 0.1 in. were cut from hot-rolled material, austenitized, and quenched into brine at 25°C. Similar specimens were also cooled in the furnace, after a short soaking treatment at 1100°C, at a rate estimated to be 10°C per min in the temperature range of 900" to 500°C. X-ray diffractometry was performed on quenched and on furnace-cooled bulk specimens using iron radiation. Only a bcc phase could be detected in all samples. Lattice parameters were calculated from measurements on four lines, made up of two resolved high-angle doublets. Comparisons were made against a silicon standard. Results are shown in Table I. Based on X-ray diffraction studies of a series of alloys of lower copper concentrations, orton' estimated that the tattice constant of a Fe at 25°C increases 0.0014A per wt pct Cu in solution. Extrapolating Norton's data, it may be concluded that all copper was retained in solution in the brine-quenched 4.8 pct Cu alloy, and that approximately 5 pct Cu was also held in solution on quenching the 7.5 pct Cu alloy. Typical microstructures of brine-quenched specimens, as observed by optical microscopy, are shown in Figs. 2 and 3. Precipitation of the E phase (copper-rich) occurred along the y grain boundaries on quenching the 7.5 pct Cu alloy, rendering them readily detectable in the microstructure, Fig. 3. The original boundaries in the 4.8 pct Cu specimens were gener- ally not discernible, however. This indicates that the z phase which was seen in the higher-copper alloy was probably of proeutectoid origin. Thin foils for transmission electron microscopy were obtained from bulk specimens by spark machining to 0.006 in. thickness, followed by electrolytic polishing. Typical transmission electron micrographs

Jan 1, 1967

By R. Sprycha, J. Szczypa, W. Janusz, J. Neczaj-Hruzewicz

INTRODUCTION Because large aqueous suspensions of various fine solids originate during the beneficiation of ores, the Mining Industry constantly requires efficient and feasible dewatering methods. Among the techniques currently in use (1,2), filtration (vacuum, press) and centrifugation are fairly expensive and thus are limited to use with more valuable materials. Furthermore, installations of reasonable size produce only moderate outputs. Therefore, tailings from ore dressing plants are usually treated by sedimentation or settling techniques with a tailings dam as the ultimate sedimentation basin (3). Apart from growing environmental and economic questions, the solid product obtained from the tailings dam basin has in most cases, a rather high moisture content and a persistent semi-fluid consistency. Thus, it is difficult to transport and use further. On the other hand, the solids may be utilized as a filling material, fertilizer, etc. providing they are dry enough and properly granulated. Demands for an improved technique are met to a great extent, by the technique presented in this paper. AGGLOMERATION OF FLOCCIJLATED SLIMES Origin and Qualitative Description of the Process Phenomena of consolidation and pellet formation in flocculated fines were first observed by Yusa and Gaudin (4) while studying rheological properties of flocculated kaolinite. On this basis, methods of separating liquid from solids have been worked out (5-7) and many possibilities for application have been suggested (5,6). Yusa termed the technique "wet pelletization''.

Jan 1, 1980

By A. Cochardt, D. H. Feisel

HE success of the sintered aluminum powder material (SAP)' in raising the maximum useful temperature of aluminum alloys has stimulated effort in investigating similar systems in which the metallic matrixes have higher melting points. Examples of such systems which have been studied are nickel-alumina,2, 3copper-silica,4 copper-alumina,4 titanium-cerium oxide,5 and 80/20 nickel-chromium,8 cobalt,= and molybdenum7 matrixes with various hardeners. Conventional precipitation-hardened high-temperature alloys are often thermally unstable in service. The original fine particles that are responsible for good strength properties grow in size at elevated operating temperatures, a process termed "over-aging." This growth of precipitated particles causes a gradual loss in strength properties. A previous paperb describes the factors that govern the process of overaging, and estimates the time required for overaging of a nickel-alloy matrix dispersion-hardened by various precipitates such as are found in current high-temperature alloys, and by alumina. These calculations indicate that nickel-base alloys hardened with Ni3Al, Tic, or TiN are quite unstable at 1340" F (727°F). Such alloys should overage within a few hours at that temperature. A nickel-base alloy hardened with alumina, on the other hand, should behave differently. It should not overage appreciably within a thousand years. It was further shown8 that the thermal stability of the oxide-hardened alloy is mainly due to the low solubility of oxygen in equilibrium with alumina in the nickel-base matrix. Since the oxygen solubility is small, little oxygen can diffuse, and structural changes require very long times. This paper illustrates the effects of time and temperature on the structural stability of nickel alloy matrixes hardened by dispersions of Ni3A1, Ni3Ti, Tic, and alumina, and of nickel-chromium matrixes hardened by alumina. Hardness measurements and metallography have been used as a measure of structural stability. EXPERIMENTAL PROCEDURE Using the best information from published phase diagrams,'-l4 compositions of the Ni-Al, Ni-Ti, and Ni-Ti-C alloys were determined so as to have 5 vol pct of precipitate at 1350° F(732°C), the temperature selected to illustrate the effect of time on structural stability. Table I lists the chemical compositions of these alloys. Standard laboratory melting and alloying techniques were used in preparing ingots of the F-Series of alloys. The cast ingots, 1 3/4 in. in diam, were forged to 3/8-in. diam rods.

Jan 1, 1960

By James A. Barclay, Ralph C. Kirby

The US minerals posture will be increasingly dominated by three interrelated factors. First, when viewed over the long range, the US supply situation can be expected to steadily deteriorate as demand increases. Domestic high-grade ores have been used up, and other nations compete with the US for world supplies. Second, as environmental awareness becomes more acute, an aroused citizenry is demanding that minerals industries conform their operations to rigorous new standards. Finally, the changing energy situation that confronts the US is forcing an appraisal of energy-use patterns on operations previously guided solely by economic principles and not by national priorities. While future US mineral production and consumption patterns are unclear at this time, it is certain that US demand for minerals will continue to outrun domestic supply. Thus, the US is faced with a challenge of producing more minerals and metals from lower grade resources. Meeting this challenge means a strengthening of US research and development efforts, coupled with their application in the remaining leadtimes available. Some specific examples of how the US Bureau of Mines (USBM) is assisting in the processing of low-grade resources follow.

Jan 6, 1975

By Albert C. Harding

For several years barite (BaSO4) production has topped such better known minerals as feldspar and fluorspar in annual tonnage and is now well established among our foremost nonmetallic industries. Description Of widespread occurrence in the United States, barite is relatively soft (hardness, 2.5 to 3.5), inert, heavy (specific gravity, 4.5), and is also called "barytes" (sometimes pronounced "bear-i-tease"), "heavy spar" and "tiff." It occurs with granular and earthy structure but usually has coarse, orthorhombic crystallization. It is commonly white, and although occurring in various shades of red, yellow, and gray, barite always gives a white streak and can be scratched by the ordinary prospecting pick. Its softness and weight are usually sufficient to establish field identification. Another aid is the "rotten egg" odor of H2S which sometimes emanates from freshly fractured surfaces. Barite can be readily distinguished from two other minerals which have somewhat similar occurrences and characteristics. The relatively rare celestite, strontium sulphate, has a specific gravity slightly less than 4.00 and gives a distinctively crimson color in a flame test. The very rare wither-ite, barium carbonate, has a specific gravity of 4.3 but readily effervesces with dilute hydrochloric acid. Occurrence All known commercially important barite deposits in the United States occur as re- placements or cavity fillings in schists, shales, limestones, dolomites, and quart-zites, or as residual deposits from such formations. In Georgia, Tennessee, North Carolina, and Missouri, high-grade barite is recovered as fragments from residual clays covering quartzites and dolomites. In Arkansas, Nevada, and California, barite, usually of lower grade, is mined from replacement deposits. These seven states contributed the entire production reported by the U. S. Bureau of Mines for 1945 as given in Table I. Table i—Crude Berile Sold or used by Producers in 1945 State Short Tons Arkansas................... 260.660 Missouri.................... 225.467 Georgia..................... 110,393 Tennessee................... 32,812 Nevada..................... 28,919 Other States............... 37,811 Total..................... 696,062 ('other states,, included only california and North Carolina. Such a large part of this undistributed production came from California that that state probably outranked both Nevada and Tennessee. For the second consecutive year Arkansas was the leading producing state, particularly worthy of note because there was no commercial production of barite there prior to 1941 and because the entire production of Arkansas has come from one large deposit which is being operated by two companies. Consumption The 1945 consumption as reported by the Bureau of Mines was: 482,442 tons as ground barite 139,288 tons in making lithopone 99,173 tons in producing barium ------- chemicals Total 720,903 tons

Jan 1, 1949

By E. A. Devuyst, M. A. Mosoiu, V. A. Ettel

Nickelic hydroxide is an important metallurgical reagent used for precipitating cobalt from nickel sulfate solutions. Existing methods of preparation of nickelic hydroxide involve electrolytic oxidation of Ni(OH)2 or the use of strong oxidizing agents such as chlorine, ozone and persulfate. Although the oxidizing properties of the SO2 + O2 system have been known for some time, e.g., detection of SO2 and oxidation on iron in acidic solution, the application of this system for the preparation of nickelic hydroxide as a process was not considered in the past. The present paper describes a new method for chemical preparation of nickelic hydroxide which has been developed in INCO laboratories. The technique consists of reacting nickelous hydroxide suspensions with a slurry of calcium sulfite in the presence of air or oxygen. The main advantage of the process is the cost of reagents and an absence of soluble by-products (e.g., C1-). The chemistry of this process is unusual since the redox potential obtained during the reaction exceeds that of the oxygen electrode. Therefore, the effect of CaS03 is not just a catalytic acceleration of the reaction NI(OH)~ + 02. The so3= must be involved in the stoichiometry of the overall reaction producing in the initla1 phase some strongly oxidizing intermediate species.

Jan 1, 1981

By Toshio Kurikami, Charles A. Brockmiller, John E. FitzSimmons

In the manufacture of sulfuric acid from SO2 bearing gases, the presence of mercury vapor in the gases may lead to unacceptably high mercury levels in product acid. Anticipating inception of regulations requiring low mercury acid, St. Joe Minerals Corporation and Toho Zinc Company, Ltd. independently developed new mercury removal technology. The processes may be used individually or in combination, depending upon the mercury content of the SO2 gases and the required mercury level in acid, for efficient control of maximum mercury levels in sulfuric acid. The St. Joe B Process removes mercury from roaster off-gas streams, while Toho’s NAK Process precipitates Hg from concentrated sulfuric acid. The combined process is commercially operated at St. Joe's zinc smelter in Monaca, Pennsylvania, and the NAK Process at Toho’s Chigirishima lead smelter and Onahama zinc roasting plant in Japan. Product acid mercury levels of 0.5 mg/kg are economically achieved.

Jan 1, 1976

By Karl F. Peterson, H. K. Najarian, Robert E. Lund

PRIMARY products of the Josephtown smelter are zinc metal of various grades, lead-free zinc oxide pigments, cadmium metal, and sulphuric acid. Zinc concentrates of domestic and foreign origin are blended and desulphurized at the roaster plant. The equipment includes five, 12-hearth Herreshoff roasters and two modified Trail-type suspension roasters. The sulphur dioxide containing gases from the roasting operation are diverted to a four-unit contact acid plant for the manufacture of sulphuric acid. The roasted calcines are agglomerated by sintering on Dwight-Lloyd-type sintering machines; the sinter is crushed and sized within required limits; and the sized sinter is smelted in vertical shaft-type electro-thermic furnaces. Of the 13 electrothermic furnaces of various sizes now in operation, four are designed to produce American process zinc oxidc of various specifications; and the remaining nine furnaces are equipped with vacuum-type condensers and produce zinc metal. Papers describing the general smelting practice at Josephtown have been published by AIME. Since both High Grade zinc metal and lead-free zinc oxide pigments are produced direct from the electrothermic furnaces without need for subsequent refining, the elimination of impurities such as lead and cadmium has to be accomplished during roasting and sintering operations. To effect the producing of both High Grade and Prime Western zinc products, the roasting and sintering operations are on two separate circuits. A High Grade circuit produces finished sized sinter low in lead, cadmium, etc., for the High Grade furnaces; and the Prime Western circuit produces finished sinter destined for the furnaces producing Prime Western metal. Sintering at the Josephtown smelter differs in many important respects from the sintering practice in smelters operating horizontal retort zinc furnaces. Requirements of the electrothermic smelting furnaces define the physical characteristics of the sinter, while the chemical composition of the sinter is controlled according to the grade of metal and oxide to be made as final products. Three principal objectives in the sintering process at Josephtown smelter are: 1. To transform the zinc calcine from the roasting operations into a hard, yet porous agglomerate that will not crumble in the smelting furnace. 2. Crushing and sizing of the sinter to obtain a proper screen analysis which is normally —% in. down to +1/4 in. particle size. 3. To eliminate, particularly in the High Grade circuit, as much of the impurities such as sulphur, lead, and cadmium as possible. The sintering plant as originally built in 1930 was equipped with three standard 42 in. x 44 ft Dwight-Lloyd sintering machines. Each machine was equipped with a 15x60 in. sintering corporation fan driven by 150 hp, 900 rpm synchronous motor through a magnetic clutch and capable of delivering 30,000 cfm of air at 15 in. of water and 150°F. Each sintering machine was driven by 7½ hp dc motor with controllers for varying the speed of the machine from 8 to 32 in. per min. The pallets were cast iron and the grates of the herringbone type. The charge was mixed in a 4 ft diam x 8 ft Stehli pugmill and transported by belt conveyor, elevator and tripper conveyor to a small bin over each machine. Shortly after the start of operations the following changes were found necessary: 1. The herringbone grates which plugged very quickly and were difficult to keep clean were replaced by straight, narrow cast-iron grate bars running at right angles to the travel of the pallets. These grate bars are held in place by a center bar extending across the pallet on the 24 in. dimension and by removable retaining plates which form the sides of the pallets. 2. Mechanical grate knockers were developed in conjunction with new grate bars for continuously and automatically cleaning the grates. 3. As the cast-iron pallets cracked, they were replaced with cast-steel pallets. In 1938, the capacity of the sinter plant was increased with the installation of two 42 in. x 22 ft machines which were brought from the company's Herculaneum lead smelter. With a circulating load of some 250 to 300 pct, production of finished sinter on the 42 in. x 44 ft machines at this time amounted to about three tons of sized sinter per machine hour. In 1945, one of the 42 in. x 22 ft machines was replaced by a 60 in. x 44 ft machine of our own design. In 1948, as part of the plant-wide expansion program, the sinter plant not only was expanded but also divided into two separate plants; namely, Prime Western and High Grade circuits. The sinter destined for furnaces producing Prime Western zinc metal is made in a new plant comprising two 60 in. x 44 ft Dwight-Lloyd-type sintering machines, each having a 45,000 cfm Sturtevant fan at 18 in. water static pressure and served by an 8 ft diam x 12 ft long rotary charge pclletizer and auxiliary crushing and sizing equipment. The sinter destined for furnaces producing High Grade zinc metal and zinc oxide pigments is produced in the old sinter plant which was expanded to accommodate four of the 60 in. x 44 ft sintering machines, replacing the old sintering units. In the High Grade sinter circuit, two units of the 60 in. x 44 ft machines are used as preliminary soft sinter machines; and the remaining two units of the 60 in. x 44 ft machines are used to make finished hard sinter. Purification Theory Partial elimination of lead and cadmium in the sintering of zinc ores is common knowledge. However, by some manipulation and by taking advantage of the double circuit, it is possible to make zinc sinter which is nearly free of contaminators. Lead

Jan 1, 1952

By John Jermain Porter

The chief purpose of this paper is to indicate the laws governing the fuel-economy of the cupola, to examine the feasibility of some of the proposals for increasing its fuel-economy, and to show that the conditions limiting fuel-economy here are altogether different from those prevailing in the blast-furnace. The two methods available for studying the thermal efficiency of the cupola and determining the factors limiting fuel-economy are: 1, by the determination of the total heat-balance; and 2, by the application of the theory of critical temperatures. The case selected as an example represents a cupola operating under fairly efficient conditions. The data are as follows : Cupola, GO in. in diameter, 15 ft. high to the charging-door, with a 9-in. lining. Bed-charge, 2,000 lb. of coke and 4,000 lb. of iron. Subsequent charges, 400 lb. of coke and 4,000 Ib. of iron. Total number of charges, 20. There was 800 lb. of coke recovered from the drop, hence the total coke burned is 8,800 lb., or 0.11 lb. of coke per Ib. of iron. Coke contains 90 per cent. of fixed carbon and 2 per cent. of moisture. 300 1b. of kindling-wood is used in lighting. 80 lb. of limestone (95 per cent. of CaCO,) is used per charge, or 0.02 lb. per Ib. of iron. Melting-loss, 4 per cent.; distributed thus : Fe, 3.5; Si, 0.25; Mn, 0.25 per cent. Average analysis of top-gases : CO2, 15.1; CO, 10.0 per cent. Average temperature of top-gases, 1,600" F. Temperature of air and stock charged, 60" F. Dew-point of air, 50 F. The items entering into the total heat-balance and their calculation are as follows: 1. Heat of combustion of fuel.—Total heat evolved = 14,580 x lb. of carbon burned + 7,200 X Ib. of wood burned. Hence B.t.u. per lb. of iron charged =

Jan 1, 1913

By Tomek Ulatowski

This presentation discusses the necessary ingredients for the creation of an acceptable credit structure, i.e., the structure that enables the borrower to attract the funding from different groups of lenders. As the amount of debt in the capitalization of new projects increases, it becomes quite critical that the mining venture sponsors obtain funding in a manner which maximizes the project economics. Attention normally is focused on the inherent operating cost characteristics of a venture such as the cost of mining, milling, transportation, smelting, and refining. The projected costs are derived from lengthy feasibility studies often taking millions of dollars and years to prepare. For a variety of reasons as the amount of equity directly provided by the sponsors declines, the balance must be made up from external credit sources. As a result, once the project becomes operational, debt service requirements assume crucial importance. For most new ventures, in the early years of production, the total amount of periodic debt amortization charges together with the projected interest expenses equals or exceeds the total operating cost. Utmost care must be taken, therefore, to reducing these costs which will then increase the chances for the implementation of the project. Project sponsors must carefully evaluate different funding sources in terms of their potential economic impact and, concurrently, evaluate alternative credit structures in order to be able to attract the selected funding vehicles. In this presentation I will discuss credit sources in the order of their relative appeal; i.e., from the standpoint of maximizing rates of return to the project owners. The tenor of the credit, that is the period from signing a loan agreement to the time of last repayment under the loan agreement, is undoubtedly the most important variable in evaluating the attractiveness of debt sources. Therefore, I will begin by discussing debt sources with the longest maturities and will end with a description of credits with relatively shorter tenors. The availability of different funding possibilities will naturally depend on the geographic location of the proposed venture, the creditworthiness of the borrower and the sponsors, the project economics, and finally the actual liquidity conditions in the capital markets at the time that the funds are committed. U.S. LONG-TERM DEBT MARKET - PUBLIC OFFERINGS AND PRIVATE PLACEMENTS The long-lived nature of most mining projects dictates that the majority of the mine financing be raised from long-term sources. In today's world capital markets U.S. debt issues probably carry the longest maturities available. The maturities can range from 5 to 40 years. Various types of long-term corporate debt instruments can be differentiated from one another by their terms, seniority as to claims against the assets of the issuer, legal form, and whether issued privately or through a public offering. The terms of these debt issues vary widely. For example, the interest rate which is typically fixed at the time of issuance, is determined by the credit quality of the issuer, the maturity, the average life, the seniority of the debt, the quality of control covenants or type of assets pledged as security, and other exogenous factors such as: economic policy, general level of interest rates and cur-rent level of financing activity. The entire principal amount of the debt may be due and payable at maturity (known as a "bullet" maturity) or, more typically, through periodic repayments in equal or staggered amounts. Almost all such debt issues allow for prepayment at the option of the issuer, but require varying amounts of repayment penalties. Disbursements are made over a relatively short period after signing of the debt documentation which may not coincide with the actual funding needs of the project. Financial covenants can be quite stringent, covering areas such as the issuer's financial leverage, working capital, payment of dividends and other distributions, merger and acquisition activities, and limitations on the disposition of property. Long-term debt issues may also be distinguished by the seniority of their claims against

Jan 1, 1985

By R. K. Waring, E. C. Truesdale

The Research Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kinds of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein1 some years ago: ZnO+ CO = Zn + CO2 [1] C + CO2 = 2 CO [2] Each of these reactions is dependent upon the other for the supply of CO and CO2 , respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + H2 = Zn + H2 O [31 C + H2O = CO + Ha [4] While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction I is still the faster. He also says (p. 48), "At temperatures . . . between IIOO° and I3oo°C., . . . the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates." In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier's statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented. *

Jan 1, 1943

By E. C. Truesdale, R. K. Waring

The Research Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kinds of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein1 some years ago: ZnO+ CO = Zn + CO2 [1] C + CO2 = 2 CO [2] Each of these reactions is dependent upon the other for the supply of CO and CO2 , respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + H2 = Zn + H2 O [31 C + H2O = CO + Ha [4] While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction I is still the faster. He also says (p. 48), "At temperatures . . . between IIOO° and I3oo°C., . . . the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates." In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier's statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented. *

Jan 1, 1943

By E. C. Truesdale, R. K. Waring

THE Research Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kinds of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein1 some years ago: ZnO + CO = Zn + CO2[I] C + CO2 = 2CO[2]. Each of these reactions is dependent upon the other for the supply of CO and C02, respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + H2 = Zn + H2O[3] C+ H2O=CO+H2[4] While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction I is still the faster. He also says (p. 48), "At temperatures . . . between 1100° and 1300°C the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates." In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier's statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented.*

Jan 1, 1941

ARTICLE I NAME AND OBJECT SEC. 1. This Institute is incorporated under the Membership Corporations law of the State of New York; its corporate name is American Institute of Mining and Metallurgical Engineers, Inc.; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II- MEMBERS SEC. 1. The membership of the Institute shall comprise four classes, namely: 1. Members; 2. Honorary Members; 3. Associates; 4. Junior Associates. All members shall be equally entitled to the privileges of membership, excepting that Honorary Members, Junior Associates, and Members and Associates whose residences shall be outside of the United States, Mexico, and Canada shall not e entitled to vote. Members and Associates residing within the United States of America, Mexico, and Canada, and not in arrears for dues, shall be entitled to vote in person at the meetings of the Institute, or, as hereinafter provided for, by letter ballot. SEC. 2. Members shall comprise all those persons who on the third Monday of February, 1918, were members of the Institute, and in addition thereto, all those thereafter elected or transferred into the class of Members. A person to be eligible for election or transfer into the class of Members must be at least 27 years of age and must have had at least six years' employment in the practice of-engineering, mining, geology, metallurgy or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. Graduation from the scientific course of a college, approved by the Committee on Membership, shall be considered equivalent to two years' employment, as required in the previous sentence. Employment as a teacher of engineering, mining, geology, metallurgy or chemistry, if in direct charge, may be considered a position of responsibility as specified in the second paragraph. Persons employed in research or any scientific literary work or in teaching in the scientific departments of colleges, approved by the Committee on Membership, who at the same time are engaged in consulting or in the active practice of mining, geology, or metallurgy, shall be entitled to consider the time so spent in active practice as equivalent to an equal length of time of employment in positions of responsibility, . provided the work done or the positions held seem to the Committee on Membership to warrant the. equivalency. The requirement of three years' employment in positions of responsibility may be waived by the Committee on Membership in the case of persons who have done notable original work in mining,. geology, or metallurgy, or have won distinction by

Jan 1, 1925

By P. W. Ramsey, G. L. Werley

THERE have been numerous examples in recent years of the similarity between aging behavior and diffusion behavior, where a plot of the logarithm of the aging rate versus the reciprocal of the absolute temperature yields an approximate straight line, analogous to a similar plot of the diffusion coefficient D (log D vs. 1/T). Austin and Rickettl have pointed out that this linear relationship holds empirically for the de- composition of austenite into pearlite and bainite in carbon steels, and Robertson' has shown similar trends in the aging of 24S-type aluminum alloys. Jenkins and Bucknall³ have also demonstrated the association between aging and diffusion rates for nickel-silicon-copper alloys. Jetter and Mehl,4 however, have shown that the maximum rate of dilation of a series of aluminum-silicon alloys does not show this linear relation and Mehl5 has pointed out that careful study of available knowledge indicates that "aging rates increase with temperature approximately exponentially, whereas D increases precisely exponentially." He further notes that "the rate of aging at a given temperature is the greater the lower the melting point of the alloy, which is also true for D." This paper describes the aging changes occurring in a zinc-25 pct manganese-15 pct copper-0.1 pct aluminum die casting alloy. It was found that this alloy does show this linear relationship and use was made of this relationship to estimate aging rates at low temperatures from data acquired at elevated temperatures. It should be noted that the aging reaction is being studied only indirectly, using changes in certain properties as criteria of the progress of the phenomenon. This alloy is purely an experimental one and is not available commercially. Zinc-Manganese-Copper System: The zinc-rich portion of the zinc-manganese-copper diagram which is of significance in the present work is quite uncertain. X ray examination of the alloy as die cast shows a phase similar to the epsilon phase (hexagonal close packed) of the copper-zinc system. All of the data accumulated indicate that the epsilon phase of the zinc-manganese-copper alloy is stable at high temperatures; that is, 500°C or above. Below this temperature a new phase is precipitated on annealing, and a decrease in specific volume occurs. At elevated temperatures this phase change occurs quite rapidly, while at room temperature the alloy has shown no change after several years. According to X ray data, this precipitated phase resembles the gamma phase (cubic) of the copper-zinc system, a hard and brittle structure. From examination of the microstructure and from X ray examination of the alloys annealed at

Jan 1, 1951

By F. W. Metzger

INTRODUCTION Coal quality control in mining and mine planning has always been important and has become even more essential in recent years due to environmental considerations. The primary consumers of the sub-bituminous coals found in the Powder River Basin are electric utilities that require low sulfur coals to meet government air quality regulations. Electric generating plants are designed to burn coal of a specific quality, and the supplier of that coal must be able to guarantee shipments within specified quality tolerances. Over the past several years, Exxon Coal USA and, more recently, The Carter Mining Company, a division of Exxon Coal USA, have established an evaluation and development program to accurately define the geology and quality of their coal properties. This requires an adequate drill hole density so that detailed correlations of the coal seam and the lithologic units, or benches, within the coal seam can be made. These units are recognizable in the core and also on geophysical logs. Like any systematic approach, geologic modeling has been refined and improved through new technologies. Today, coal seam properties are mapped using computer applications. Rapid access and manipulation of these data allow for optimization of mining efforts. This presentation will demonstrate how a detailed mapping program can be important in both pre-mine development and in-pit quality control.

Jan 1, 1983

By Robert Greenwood

The advent of the space age and its promise of interplanetary flight has prompted new ideas for propulsion systems that will allow maximum energy with minimum fuel weight. The use of cesium as the source of energy for such rocket flights has been found desirable. Theoretical efficiency of a rocket fuel is measured in terms of specific impulse, defined as the number of pounds of thrust per pound of propellant consumed per second. Specific impulse is usually expressed in seconds (the number of seconds for which one pound of fuel would produce one pound of thrust) although it is really a measure of total energy, not of power. The most sophisticated chemical fuels have a specific impulse of 300 to 400 sec; liquid hydrogen heated by nuclear reactor has a specific impulse of 1000 to 1200 sec. Specific impulses as high as 20,000 sec, however, are theoretically attainable with the ion rocket, in which free cesium ions are accelerated across a voltage drop and ejected at high velocity.' Characteristics of the system have been sketched by Boden. The desirable properties of an ion propellant are: 1) low ionization potential, 2) low boiling point, and 3) high atomic weight. Alkali metals best fulfill these requirements, and Table I indicates the superiority of cesium. The use of heavy complex ions such as UCl; is ruled out by their instability and other disadvantages.

Jan 5, 1960