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By R. L. Beatty

The Bond International Gold (BIG) Colosseum Gold Mine was discovered in 1865, but no recorded production occurred until the 1930's, with production approximately 19k9 (615 oz) of gold. The mine was closed in 1942 as a non-essential industry during World War II. The property was acquired by Dallhold Resources in mid 1986. Construction of a 1.1 million Mt carbon-in-pulp, cyanide mill started in November, 1986, and was completed in September, 1987. Minable reserves are estimated to be 9,560,831Mt (10,539,000St), with an average grade of 2.1 g/Mt (0.062 oz/st). This paper describes a general view of process flow and plant equipment, as well as a look at the maintenance and operational problems encountered in the fist six months of operation.

Jan 1, 1989

A process was developed, on a laboratory scale, for the removal of iron oxides from Weipa pisolitic bauxite. The technique involves the chemical reduction ofthe iron oxides by carbon, followed by selective removal of the iron species by acid leaching or chlorination.To remove more than 90 per cent of the iron it is necessary to reduce the iron oxides substantially to iron metal by heating the bauxite, pre-calcined at 650-800°C, with reactive carbon at 1040-1100°C. Reduction proceeds via the intermediate formation of hercynite (FeO.Al2O3) and difficulties have been encountered in reducing hercynite formed under less favourable reduction conditions.Following reduction, efficient selective removal of iron species is readily effected by acid leaching using dilute hydrochloric acid at 100°C, or chlorination at 500-750°C using Cl2, Cl2/N2, or Cl2/N2/CO mixtures.After removal of unreacted carbon, the final products contain 0·5-1.0 per cent Fe203 and 87-92 per cent Al203.

Jan 1, 1971

By Edward D. Thimons, Jay F. Colinet

Underground coal mining operations in the United States continue to increase productivity as mining equipment and practices are improved. Unfortunately, increased production also results in the potential for increased respirable dust generation and worker exposure. In response, US operations are applying basic controls at elevated levels and looking to emerging technologies in an effort to better control respirable dust levels. Ventilating air and water sprays remain the basis of dust control strategies for both longwall and continuous mining operations, and the level of application for these controls continues to increase. In addition, new technologies are emerging that have the potential to further reduce dust levels. The National Institute for Occupational Safety and Health (NIOSH) has been conducting research into methods to optimize existing control technologies and evaluate emerging control technologies. This paper will summarize control technologies routinely being used in underground coal mine operations, as well as provide a review of new controls that are being pursued.

By A. Gülmez

The complex ore deposit containing fluorite, barite and bastnaesite minerals is located in Beylikova Region of Sivrihisar town of Eskisehir Province of Turkey. The ore contains 40.80% CaF2; 35.35% BaSO4; 2.01%Ce; 1.5% La; 0.39% Nd and 0.1% Th. Barite recovery from this ore by flotation of the HCl leached tailings is presented in this paper. Rare earths are recovered by leaching. The leached residue (tailings) containing fluorite and barite is subjected to froth flotation to recover barite. The effect of pH and collector concentration on the flotation of barite have been studied in this work.

Sep 1, 2012

By Carlos Virrueta

"El presente texto señala la importancia del comportamiento seguro en el sistema de riesgos aplicados al comportamiento de los trabajadores, salud y medio ambiente para así establecer los lineamientos yresponsabilidades requeridos para realizar el programa de Auditorías de Comportamiento Seguro, fortalecer el compromiso visible de liderazgo de los equipos de trabajo, así como crear y fortalecer en las personas el hábito de la prevención de los riesgos."

Oct 21, 2015

Operation of a pilot-scale Floatex density separator was studied using a pyrite concentrate slurry feed. Experimental measurements were further utilized in parameterization of a hindered settling simulation model. The model incorporates particle slip velocity calculation and also a separation efficiency function, adjusted to describe the feed material characteristics. The model was used to compute the overflow and underflow compositions when both fluidization bed pressure and teeter water flow rates were varied. In addition, prediction accuracy and the model validity were evaluated. The simulations gave good results when the teeter interstitial velocities were moderate enough to avoid excessive turbulence in the fluidization. Prediction of the cumulative overflow and underflow size distributions in most experiments yielded essentially less than 10% relative error between the sample data and the estimated value of the 50% passing sizes.

Jan 1, 2011

By C. Hilgendorf, J. Gingerich, J. R. Boniwell, M. Drouin, D. David on, J. Boldy

The initial discovery of gold in the Eastmain River area, 310 km northeast of Chibougamau, was made by Placer Development Limited in 1970. This discovery resulted from the drill testing of an airborne E .M. Target located in an area of extensive glacial overburden, within an unexplored Archean greens tone belt considered prospective for base metal deposits. Intermittent exploration by another company between 1973-1977 failed to obtain promising results and the existing claims were allowed to lapse. In 1981, Placer reactivated the project and initiated intensive exploration during the next two years which included aerial E .M. surveys, claim staking, ground E .M. and magnetic surveys, geological mapping, diamond drilling and attendant borehole P,E.M. surveys. Beginning in 1983, exploration has been conducted on a joint venture basis with Eldor Resources Limited, The greenstone belt under investigation has an arcuate distribution pattern relative to a centrally located granitic core. Occurrences of gold mineralization defined to date are located to the south of the granite along a strike length of 7 km, and appear to be restricted to the lowermost of two mafic volcanic cycles. This lower cycle is dominated by basaltic flows with subordinate rhyolitic flows and pyroclas ties. Concordant, variably magnetic, massive to talcose ultramafic units occur towards the stratigraphic top of the lower mafic volcanic cycle and appear to crudely define areas considered prospective for gold on a regional bases. Economic interest in centered on a s tratabound, siliceous, sulphide-bearing unit hosted in a 15- 25 metre thick sequence of rhyolite tuffs, basalts and intercalated ultramafics, The siliceous ore bearing unit ( interpreted as a recrystallized chert) contains from 10%-30% pyrrhotite and pyrite with subordinate chalcopyri te and minor sphaleri te. Alteration is characterized by mica development, silicification and carbonatization. Garnets are also occasionally present in close proximity to the ore horizon. The sequence is south facing, and overturned to the northeast at 35°-55°. Explora tory drilling in the vicinity of two conductive targets has been on 100 metre centres along a 1 km strike length of the prospective sequence. To the end of 1983, two ore zones (A and B) have been partially drill tested with estimated indicated and inferred geological reserves of 1 million tonnes grading 11.7 g/t gold , 14.7 g/t silver and 0.26% copper. The system is open at depth. This discovery is the result of the effective integration of geophysics and geology with contributions by many over a long period of time. Key events that can be emphasized are: ( 1) initial area selection of a remote greenstone belt in 1969 - albeit for base metal deposits , (2) utilization of an airborne E .M. system which successfully targeted the A Zone in 1970 , (3) the timely reactivation of the project in 1981 and the subsequent recognition that the original discovery represented a sulphide bearing stratabound horizon with implicit volcanogenic connotations , (4) the intensive effort in 1982-83 deploying aerial and ground geophysics coupled to volcanogenic concepts of ore distribution which resulted in the discovery of the B and C Zones in 1982, and (5) the integration of downhole P . E.M. surveys and geology to successfully delineate ore at increasing depths . To the end of 1983 , $2.6 million has been expended, and it is hoped that continued effort will result in the eventual delineation of an economically viable ore deposit for the joint venture partners .

Jan 1, 1984

By AIME AIME

SCANDINAVIAN countries seem somehow to furnish an amount of talent and leadership far be- yond their population and among them Sweden is possibly at the top. The United States has many eminent citizens born in the latter, country or who are of Swedish descent and the engineers may claim their full share. In fact, the number is so large that a flourishing Swedish-American Engineering Society has been formed, including a number of A. I. M. E. members. Dr. Waldemar Lindgren is more scientist than engineer, though his work in economic geology has contributed directly to the development of many mines, and he is the valued- adviser of a number of our larger companies. Probably he, himself, values most highly the contributions he has been able to make to scientific theories of the occurrence and genesis of ore deposits. His fellow scientists have placed upon these the high mark of approval by electing him to the National Academy of Sciences, and Princeton University in 1916 recognized his position by conferring on him the degree of Doctor of Science.

Jan 1, 1931

By Herbert H. Einstein

Swelling ground is one of the most feared problem in tunneling. Although usually not causing sudden failures during construction, the very large and long- lasting deformations give contractors and designers the impression of facing an inevitable phenomenon against which there is no technical defense. Examples are concrete liners of up to 1 m that have been cracked or crushed, tunnel inverts that are heaving at a rate of 0.1 m per week during construction and continue to heave during decades. This author (Einstein (1979). Einstein et al. (1972) (1975)) and others (Huller (19761, Grob (1972) (1976). Golta (1967), tienke (19761, Krause (1976). Lee et al. (1976)) have described many cases of swelling tunnels that illustrate the significance and magnitude of the problem. This paper intends to show that tunnels in swelling rock can be built to perform satisfactorily. . For this purpose the tunnel builder needs to know how to determine the existence and specific behavior of swelling ground, how to select appropriate structural characteristics of the tunnel and predict its performance under the specific ground conditions, and finally how to construct the tunnel such that the anticipated performance will be achieved. This concept of a design-construction procedure is the same as that for tunneling in general; it is mentioned here for NO reasons: 1. To point out that design and construction cannot and should not be separated. The way in which the tunnel will be built has to be an integral part of the design. 2. This paper will be structured corresponding to the procedural concept.

Jan 1, 1981

By J. Drelick

Among the wide variety of modern surface chemistry analytical techniques, contact angle measurements still remain attractive for wetting characterization of solid surfaces. The captive-bubble and sessile-drop techniques are the most popular methods for the examination of flotation systems. Systematic measurements of advancing and receding contact angles for several three-phase systems using the captive-bubble and sessile-drop techniques show that the contact angle measurements depend on the technique used and may differ significantly for some heterogeneous and rough solid surfaces. Importantly, it was found that these discrepancies in contact angle measurements depend on the bubble (drop) size. Contact angles as measured with the static captive-bubble technique are compared with those measured with the dynamic captive-bubble technique, in which the capture of a bubble at the solid surface results after buoyant transport and attachment The dynamic captive-bubble technique allows for the formation of much smaller bubbles than is possible with the static placement technique in which a bubble is placed at the solid surface with a microsyringe. Although this dynamic technique cannot be recommended for the systematic wetting characterization of solid surfaces, its significant advantage is the ability to examine the contact angle/bubble size relationship over a wide range of bubble sizes, from several micrometers to several millimeters in diameter.

Jan 1, 1995

By Charles Parmelee

When Professor Silliman made his first examination of the newly-discovered Pennsylvania rock oil in 1859, he noted that different rates of heating produced different results in fractionation—longer heating produced larger percentages of light fractions. In 1862, it was found that when petroleum vapors are condensed in the still crown and dropped back into the hot liquid, the result of the distilling operation is materially modified. These early dates mark the beginning of what is called cracking petroleum and is explained as separating the component parts of the hydrocarbon molecules into more and smaller groups of the same elements. The phenomena were utilized for the next 30 years to increase the yield of burning oil. The procedure was that regularly practiced today in dry or destructive distillation. Considerable scientific study was given to the subject from 1862 to 1905, and a number of patents were obtained, but the work done was not continuous or intensive until about 1905, when the increasing demand for gasoline attracted attention of petroleum refiners to the possibilities of cracking. The first equipment built and operated essentially for cracking petroleum on a large scale was placed in successful operation in 1912. The commercial practice is, therefore, less than 15 years old. Comprehensive intense study of the controlling factors during this period has resulted in rapid increase in our knowledge, and material improvement has been made in the practice of the art. It is the purpose of this paper to outline briefly the state of our knowledge and to suggest some of the questions which are attracting attention of researchers at the present time. The major purposes for which petroleum hydrocarbons, including natural gas, are or have been cracked are: 1. To obtain products used to increase the heat value and illuminant content of artificial gas. 2. During the World War, to increase the supply of toluol. 3. To increase the amount of products capable of conversion into industrial chemicals. 4. To produce pure carbon.

Jan 1, 1927

The Autogenous milling of ores holds an increasing attraction as the focus moves towards reducing energy usage, both direct and embodied in grinding media. However, most of the early AG mills were converted to SAG for improved stability and increased throughput. This imposes a huge penalty in steel grinding media consumption. The LKAB iron ore operations in Sweden process highgrade magnetite through fully-autogenous milling lines to a final product P80 of about 45µm. The outcomes of P9O AMIRA research surveys, covering a wide range of mill fillings and throughputs and with different feed blends, are presented. Insights are provided on operational strategies, opportunities, the influence of feed size control and balancing the blend of competent gangue and softer magnetite. Areas of importance in the successful operation and control of energy-efficient autogenous circuits are highlighted.

Jan 1, 2012

By William Laird

In the process of mining coal today, our greatest asset, the coal miner, is faced with the indirect and direct consequence of underground mining operations. The indirect considerations may be the rank of the coal seam, the amount of overburden, geological factors, seam permeability and cracks. The introduction of newer, bigger and faster coal-producing face equipment having the capability to cut or rip through the bedding planes, cleats and micropores of the coal seam brings about rapid liberation of gas accompanied by greater concentrations of coal dust, has exerted a direct consideration and greater demand upon mine ventilation systems and dust control. The purpose of mine ventilation is to provide sufficient pure air to the miners working underground and to dilute, render harmless, and carry away all the dangerous and noxious gases. The mining operations which create coal dust are cod cutting, drilling, blasting, loading, hauling, dumping and movement of face equipment. The created fine dust causes the propagation of explosions. When quantities of coal dust with no methane present are raked in a sufficiently dense cloud in the presence of a source of ignition, an explosion is possible.

Jan 1, 1980

By G. Guzman

In the framework of the optimization of Teniente Converter operation the new system of automatic flux feeding through gar-gun was implemented in the Potrerillos Smelter, Codelco Chile, Salvador Division. The control algoritm based on simple iron and silica balance adjusted by empirical coefficients was incorporated in the logical programmer. The programmer works in real time gathering information from the plant instrumentation events and introduced chemical assays of concentrate, slag and flux. Through the auto-tuning of the automatic operation the criterions of optimal flux dosage were determined. Four month of operation of the automatic flux feeding system demonstrated the stabilization of magnetite content in the slag in the narrow range from 18 to 20% and the decrease of flux consumption, corresponding to annual savings US$ 340,000. Additionally, the automatic system helps operators in the control room in fast determination of optimal fluxing and avoid the errors in flux dosage affecting the slag quality and its impact on refractory wear.

Jan 1, 2007

By W. L. Fink, H. C. Stumpf, L. A. Willey

VERY few studies of the aluminum-sodium system have been reported. Heycock and Neville1 were unable to detect any solubility of sodium in liquid aluminum. Mathewson2 prepared an equilibrium diagram consisting of two horizontal lines at the melting points of the two metals. He was unable to detect solubility at either end of the system. Scheuer3 first developed a method for the chemical determination of sodium in aluminum and then studied the solubility of sodium in liquid aluminum. His method involved heating aluminum with excess sodium under hydrogen until the two liquids were at equilibrium, chilling the melt, and analyzing the aluminum-rich layer. He reported the solubility to be 0.l0 pct sodium at 700°C, 0.115 pct at 750°C, and 0.128 pct at 800°C. This paper on the aluminum-sodium system is the twenty-first in a series from the Aluminum Research Laboratories describing equilibrium relations in aluminum alloy systems. MATERIALS The alloys for this investigation were prepared from electrolytically refined aluminum (99.99 pct) and sodium of reagent quality conforming to specifications of the American Chemical Society.4 Chemical analysis of the aluminum showed the following impurities: 0.002 pct Si, 0.002 pct Fe, 0.002 pct Cu, <0.001 pct Mn, 0.002 pct Mg and 0.001 pct Na. The sodium content of all alloys was determined by either chemical or spectrographic standard procedures5 No. IIA and No. SII respectively. DETERMINATION OF LIQUIDUS The boundary of the miscibility gap was determined by a modification of the method of Scheuer3 and of that used by Henry and Cordiano.6 As finally developed the method was as follows: A fused alumina crucible 25 mm id with 75 mm depth and 1.5 mm wall thickness was placed on the bottom of a container made from a 4-in. length of 1 ½ -in. iron pipe and pipe caps. The space around the sides of the crucible was filled with 40 mesh crystalline alundum. A charge of 60 g of aluminum and 10 to 15 g of sodium was placed in the crucible, the sodium first being trimmed and rinsed with iso-pentane to remove kerosene. The container was tightly capped, filled with argon (99.6 pct pure), and heated to the desired temperature (between 670 and 800°C). A positive pressure of argon (about 8 mm of mercury) was maintained through a small pipe to the upper cap. After soaking for from 2 to 5 hr, the container was quenched by directing a stream of water onto the base, so that solidification of the aluminum-rich layer was rapid and essentially unidirectional. Analyses were made on drillings taken from the bottom of the ingots after machining off the surface layers. Pre-

Jan 1, 1948

By J. M. Hartman

ONE of the most important subjects to the blast-furnace engineer is a thorough knowledge of the conditions affecting the temperature in the different portions of the furnace. All efforts to decrease the consumption of fuel and improve the working of the furnace must be based upon it, and I may, therefore, be permitted to place before you the results of my observations, and detail the conclusions to which they have led me. Tracing the thermic conditions from below upwards we have at the bottom of a blast furnace making No. 3 iron a temperature of 2900° F., which increases slightly to a point a little below the tuyeres. In the immediate vicinity of the tuyeres the temperature is somewhat lower, owing to the entering blast ; but a short distance above the tuyeres, where all the oxygen of the blast has been converted into carbonic acid, the highest temperature in the furnace must be attained. This carbonic acid is, however, almost as soon as formed, converted by the glowing coal into carbonic oxide, a process which absorbs heat, reduces the temperature, and provides the active agent for the reduction of the iron ores. In its ascent the hot carbonic oxide gradually parts with its heat, first melting the descending iron and earthy materials, which drop down to the hearth of the furnace. The limit of this zone of fusion is rather sharply defined, and the temperature above this zone suddenly decreases. In its further ascent the hot gas drives off the carbonic acid from the limestone, which causes a further absorption of heat, and finally the gas escapes at the top, at a temperature of about 250° F. if the furnace is working well. These changes of temperature 1 have attempted to represent graphically,

Jan 1, 1880

By W. P. Yast, R. R. Slyers, J. H. Hildebrand

 The Bureau of Mines, in conducting investigations of atmospheres in mines and tunnels for the purposes of determining and combating hazards to the health and safety of workers, has from time to time closely cooperated with municipal, State and Federal agencies in safety work in engineering and ventilating probleme. Recently the writers have conducted experiments with animals and men breathing helium-oxygen mixtures under pressure. The object of this work was to determine whether helium-oxygen atmospheres can be utilized to advantage in place of normal air for caisson and diving work. In such work the permissible pressures and times of compression and decompression are limited by the physiological effects on man. The major effect is that the nitrogen, (which is the inert con- stituent of normal air and is absorbed by the body tissues and fluids in abnormal amounts when under pressure,) tends to form bubbles in the tissues on too rapid discompression from high pressures. The Bureau of Mines is interested in this problem on account of the pos- sibilities of mitigating caisson illness in tunnel construction and other engine eering operations requiring men to work in compressed air. In addition, the Navy Department is interested on account of the possibilities for extending the range of salvaging and marine engineering operations. The results of the experiments conducted by the writers lead to the following conclusions: Helium is without odor or taste and has physical properties which promise to be of interest physiologically and which have been found to have possibilities of creat practical use, especially in making a synthetic atmosphere that will re- duce the hazard of caisson disease. The substitution of helium for the nitrogen ordinarily present in the air we breathe has been found to result in an atmosphere which it as respirable as that provided by nature. The results obtained indicate that helium not only has the advantage of being less soluble than nitrogen, but

Feb 1, 1925

By Flann R. C

A small modification to current industrial practice should lead to better nickel powders for use in alloying, electroplating, and powder metallurgy. Nickel powder compacts sold for alloying are not always suitable for electroplating applications, since some presently used commercial powders will expand on sintering. Further, such nickel powders are unsuitable for use in the production of powder metal parts, because of expansion during heating of the near-net-shape preforms. Research in these laboratories has enabled the elimination of expansion, and led to techniques for the production of compacts suitable, in particular, for commercial use in both alloying and electroplating. The techniques include: powder pretreatment, cold pressing and sintering, hot pressing, and hot pressing and sintering. In this way compacts are readily prepared with densities of at least 93 per cent of solid nickel, and these, when used as anodes in Watts general purpose and bright baths, give both cathode current and plating efficiencies of 90-98 per cent.

Jan 1, 1979

By Jack L. Taylor

Single crystals of tungsten grown from powder -metallurgy swaged rod by high-temperative annealing were deformed in tetzsion at temperatures from 2500 to 5000 OF. Orientation of specittzen tensile axis, strained ratrix, and defortnation bands was determined optically by reflections from {110} etch pits. Slip traces meve analyzed and slip directiorz determined. Results indicate that {110}(111) , {112){111}. and {123}{111} type slip occur in tungsten over the terpe,atuve rutge investigated. Slip is orientation-dependent occuvring on tCuzt cowzbitzation oj slip plane and direction which has the highest critical resolved shear stvess. Overshooting appears to be a general occurrence between 2500&apos; and 5000°F. Dejornatiotz bands show rotation in a directiorz opposite to the yotation of tire tensile axis. DEFORMATION in bcc metals has been reviewed by Maddin and Chen,&apos; Keh and eissman,&apos; and most recently by Nabarro, Basinski, and olt. From these reviews it is apparent that some disagreement exists concerning the crystallography of plastic deformation in bcc metals. There is evidence of noncrystallo-graphic slip, the crystal slipping on or near a noncrys-tallographic plane in the (111) zone for which the resolved shear stress is greatest. There is also evidence to indicate that crystallographic slip occurs in the planes of the same zone. On the other hand, there is agreement that the close-packed direction ( 111) is the slip direction in bcc metals. Further, in pure bcc metals4 and alloys the operative crystallographic slip systems are strongly dependent on temperature. Both crystallographic and noncrystallographic slip have been reportede8 in tungsten, a group VIA bcc metal. The number of slip families which operate in the case of crystallographic slip, however, has been in question. The earliest study by oucher&apos; of single-crystal tungsten tested at temperatures of 1800 to 5000°F led to the conclusion that only {112)( 111) type slip operated. Raymond and eumann recently reached the same conclusion studying deformation by rolling of plasma-flame single crystals at 1800°F; however, only [loo] and [110] orientations were studied. Work at high temperatures by Leber and Pughs on tungsten and Chen and Maddin9 on molybdenum suggests that conjugate slip on nonparallel (110) planes may account for the slip on (112) and (123) planes found by others working with bcc metals. The present paper presents evidence of three families or modes of slip in tungsten in the temperature EXPERIMENTAL PROCEDURE Material. Standard microtensile specimens, 0.160 in. diam by 0.640 in. gage length, were ground from commercial powder-metallurgy swaged tungsten rod, type MK. Specimens were heated for 10 min at 5150°F or 6 hr at 5400°F in vacuum of 1 x 105 Torr or less to produce single crystals. At the lower temperature an average of two out of seven specimens heated in a group developed single crystals throughout the specimen length as shown in Fig. 1, the rest remaining wholly poly crystalline. At the higher temperature, three or four out of seven specimens became single crystal. Other than to note that Laue X-ray photographs generally showed sharp, well-defined spots, no attempt was made to assess crystal perfection or measure dislocation density. Two tungsten single crystals grown from the melt by the plasma-arc process were also used for this study.

Jan 1, 1967

By I. E. Odom

The physiocemical properties and industrial uses of the clay mineral montmorillonite are reviewed. Montmorillonite is the most abundant species of the smectite clay mineral group and is the predominant mineral composing bentonite deposits. The crystal structure, chemical composition, exchangeable ion type, and small crystal size are responsible for several unique properties, including a large chemically active surface area, a high cation exchange capacity and interlamellar surfaces having unsual hydration characteristics. The type of exchangeable ion Na, Ca and/or Mg has a major influence on industrial and chemical uses of montmorillonite because of their hydration characteristcs. Natural occurrences of Na montmorillonite in commercial quantities are geographically limited, but Ca-Mg montmorillonite deposits are known world wide. Foundry, well drilling, pelletizing and civil engineering constitute the major uses of montmorillonite, but the total array of uses of montmorillonite exceeds that of any other mineral.

Jan 1, 1986