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By O. Zach, K. Gamweger

"The Process of gas purging in molten Aluminium has been an industrial practise for many years. The melting of alloying elements and their rapid distribution in the bath is very important. To improve the mixing and homogenisation process, at RHI NON FERROUS METALS ENGENEERING GMBH a lot of CFD calculations were done. The so developed new ""purging program"" was tested at Alumino Catalan S.A., Spain. The results of the testtrials were very satisfactory and corresponds very well with the calculated data."

Jan 1, 2004

By Pedro Perata

"El siguiente estudio revisa la venta, uso industrial y posicionamiento de la antracita dentro de Lima y sus alrededores. En ese sentido, se busca encontrar posibles consumidores de otros combustibles que pueden convertirse en ancracita. Por ello, el campo doméstico se ofrece como la zona más idónea puesto que ofrece una mayor demanda de kerosene, al tiempo que el precio de venta es barato, que en un mercado libre de competencia y con kerosene a precio mundial, es más factible la posición de la antracita dentro del mercado. Otro posible lugar, lo encontramos en las chimeneas para calefacción, puesto que las briquetas de antracita son superiores a la leña u otro combustible y el costo es similar económicamente. En los usos industriales, se conoce que el consumo total de combustible alcanza 286 mil toneladas de petróleo residual y 46 mil toneladas de petróleo diesel, solo si el precio del petróleo desciende entre 360 y 400 por tonelada, la antracita podría competir. Finalmente, en algunas industrias pequeñas, el gas metanizado y construidode antracita en una planta central, es el preferible al del petróleo."

Jul 20, 1956

By A. Desbiens, R. del Villar

"This two-part paper summarizes the design and implementation of a distributed PIbased control strategy installed at the B grinding circuit, at the Kidd Creek Division of Falconbridge Ltd. Part I details the design of the control strategy using a grinding circuit dynamic simulator (DYNAFRAG). The first step consisted of sampling campaigns and data processing to calibrate DYNAFRAG. Then, several control alternatives were designed and tested with the simulator. The main feature of these strategies is their ability to regulate or keep within an upper and lower limit five output variables (circulating load, rod mill density, cyclone feed and overflow densities and pump box level) with only three manipulated variables (rod mill water, pump box water and rod mill tonnage). By simulation on DYNAFRAG, it was possible to discriminate among several control structures. The preferred control strategy uses a saturation algorithm, which allows the adequate regulation of two measured variables with only one actuator. Controllers located in interacting loops are appropriately tuned, taking into account the existing process coupling. Part II will present the implementation of the selected control strategy.IntroductionSteady state simulators are used to predict the stationary state of a given process under specific operating conditions. Tradi - tionally, steady state simulation has been applied for process flowsheet design, for evaluating process modification benefits or for determining key operating parameters in process operation optimization. Dynamic simulators add a new dimension to process simulation since they allow the prediction of the process transient behaviour, resulting from the application of a different set of operating conditions and/or from natural disturbances or equipment failure. Dynamic simulators can also be used for the training of new operators or for the design of control strategies."

Jan 1, 1997

By N. W. Perry

Some months ago a gentleman gave me a handful of minerals which he had collected in an arroyo, or dry stream-bed, that ran through the town of Ramos, State of San Luis Potosi, Mexico, as a sample of the class of ore that might be expected in the mines of that section. I was, however, familiar with those mines and their ores, and cast the pebbles aside as of no interest. I afterwards returned to Mexico and took charge of two groups of mines, one in the State of Zacatecas, and the other in the town of Ramos, State of San Luis Potosi. While I was thus engaged, it was a very frequent occurrence for parties to bring me specimens of rock, ores, etc., for my opinion on them; and one day a man brought me a half-dozen or more small pieces of a very black shiny mineral, desiring to know what it was. I did not recognize it, and desired him to give me the specimens for analysis, which he promised to do in a day or two. He never did give them to me, for he lost them ; but he said there were plenty more where these came from—at Ramos—and he could get them at any time for me. I thought no more of the matter until after my return to this country, when, one day, in looking over some of my old " trash," I came across the specimens at first referred to as having been cast aside so carelessly. I noticed two distinct minerals among the pebbles : one being erubescite or tetrahedrite, the predominating mineral of the mines of Ramos, and the other a hard black shining mineral, the same that I had wished to analyze in Mexico. On testing for hardness I was surprised that it scratched topaz with some degree of ease, thus placing it above 8 in the scale of hardness. Trying it with a corundum, I sometimes succeeded in scratching it, but at other times it would scratch the corundum, and at still other times neither would produce the slightest effect on the other. Crystallized topaz would be ground to a powder in attempting to scratch the black mineral, without abrading it in the slightest. It must, therefore, be placed at 9 in the scale of hardness. It is of the deepest opaque black, not unlike pitch-blende in ap-

Jan 1, 1884

By M. M. Veras, C. H. Sampaio, A. S. Young, D. Neto, C. O. Petter

"Due to new technological developments, automatic sensor based sorting has made progress within industrial minerals, precious metals, diamond, and coal mining in recent years (Lessard et. al. 2016). In order to re-introduce the technology to other mining sectors, this research discusses its application to iron, manganese, and zinc ores through test works performed by the authors. These test works were performed using Dual Energy X-ray Transmission (DE-XRT) sensor technology. In each case, pre-concentrations of the ore were created demonstrating the possibility to reduce waste material, energy costs, and water consumption while improving product quality of the ores. INTRODUCTION Sorting of mining ores is as old as mining itself (Salter, 1991). Sensor based sorting applications in coal mining began as early as the late 19th century (Louis 1928). New sensor technologies were developed and implemented sequentially for uranium, nickel, coal, and gold mining (Refining, 1949, Rose et al, 1950, Bloomfield et al, 1966, Clayton et al, 1987, Robben and Mosser, 2014). While these sensor technologies were developed decades ago, computational capacity to keep pace with the vast amount of information required utilizing the sensor technology did not arrive until recently (Lessard et. al., 2016). The sensor based sorting (SBS) process was effectively described by Salter and Wyatt in Minerals Engineering in 1991, and Wotruba and Harbeck in 2010 in the Ullmann’s Encyclopedia of Industrial Chemistry under Sensor Based Sorting. Both descriptions include the following key steps: 1. Presentation of the material or particles. 2. Examination or detection of the material or particles. 3. Processing or analysis of the data generated. 4. Physical separation of the material or particles by external means. Effective presentation of the material or particles is achieved when the sensor is capable of identifying each particle individually. This step requires that each fragment of the material be isolated, and it often involves acceleration of the material fragments by chute or mechanical means, as well as the spreading of particles by vibratory feeders (Salter and Wyatt, 1991, and Wotruba and Harbeck, 2010). The isolated particles typically are conveyed into an area wherein they are subjected to electromagnetic irradiation (except in cases of some radioactive ores), either in the form of x-ray, visible light, infrared, or other energies. A wide range of applications for sensor based sorting exists in the literature. The majority of applications fall into one of two camps, (1) pre-concentration of mineral ores, or (2) characterization of the material during processing (Buxton and Benndorf 2013). While there is much to be gained from in-line material characterization and the resulting control both of quality and processing, this article focuses primarily on the camp of pre-concentration of mineral ores."

Jan 1, 2017

The iron ore deposits of the Port Hedland district of North Western Australia are associated with band'ed sedimentary iron formations that form part of the local succession of folded and faulted Archaean volcanic and sedimentary rocks. The iron formations are regarded as the protore beds or sources of the iron which became concentrated by supergene processes to form commercial grade iron ore deposits.Iron oxide deposits occurring in situ within the protore beds are considered to be of residual-replacement origin, due to supergene leaching of gangue minerals and' deposition of secondary iron oxides in their place, Two types of deposit have been recognized. Lode deposits are deep lenses of massive hematite located adjacent to major faults. These deposits are thought to be very old and to have originated by supergene processes during the long period of erosion represented by the major unconformity between the Archaean rocks and the overlying Proterozoic beds. The other type, known as crust ore deposits, are shallow cappings of hematite and goethite on hills formed by the outcrops of steeply dipping protore beds. These deposits could have originated as far back as the early Mesozoic and it is possible that the ore-forming process is continuing at a slow rate at the present day.Deposits formed by erosion and re-deposition of material derived from pre-existing residual-type deposits are known as derived deposits. These include conglomerates and scree accumulations of various types and ages and pisolitic deposits formed by supergene leaching of transported detritus. Derived deposits range in age from early Proterozoic to Recent. The presence of pebble accumulatio,ns of lode-type hematite in the Proterozoic basal conglomerate provides good evidence that lode hematite deposits existed in pre-Proterozoic times.INTRODUCTIONThe existence of iron ore deposits in the Port Hedland district of Western Australia has been known since the beginning of the century, but little attention was paid to them untIl the 1930's, when the Commonwealth Aerial, Geological and Geophysical Survey of Northern Australia carried out investigations of most of the then known mining fields of the Northwest Division. The only iron...

Jan 1, 1964

By John E. Hamak

The U.S. Bureau of Mines estimates the identified helium resources of the United States at 630 Bcf as of December 31, 1990. This includes 295 Bcf of demonstrated reserves, 87 Bcf of demonstrated marginal reserves, and 42 Bcf of demonstrated subeconomic resources. The identified resources include 161 Bcf of helium in inferred and marginal reserves and 45 Bcf in inferred subeconomic resources. The identified helium resources contained on Federal lands are approximately 170 Bcf, including 32 Bcf in underground storage in the Cliffside Gasfield near Amarillo, TX. In addition to the identified helium resources, undiscovered helium resources in the United States are estimated at a most likely volume of 103 Bcf, with a maximum volume of 259 Bcf and a minimum volume of 41 Bcf. Also reported are 43 Bcf of helium in nonconventional and low-helium-content natural gases. Current extraction of helium in the United States occurs mostly from natural gases produced from the Hugoton gas area in Kansas, Oklahoma, and Texas, and the Riley Ridge area in southwest Wyoming. Helium extracted from natural gas in the United States in 1990 was 2.5 Bef. If current trends continue, some shortfalls in helium supply may occur in about 5 to 10 years.

Jan 1, 1993

By Francis F. Pitard

The presence of elements, minerals, or chemical compounds in materials at very low concentrations is becoming a constantly increasing concern for several segments of the Industry. Some trace elements or chemical compounds may be considered as hazardous, some are simply considered as undesirable In complex processes where they could be constantly recycled and end up as the major factor of decreasing quality for some valuable products. In some other cases, the presence of a trace element or mineral may be highly desirable because of its economical value: precious metals are falling into this category, they probably were the first trace elements to draw our attention. Tremendous quantity of money is spent for analysis at the trace level, also the analytical "tool" has been considerably improved during recent years, but still the sampling aspect of the problem remains obscur for many, and because of it, large quantity of analytical efforts become meaningless. Not only the absence of sampling strategies is badly affecting the representativeness of a large majority of samples, but furthermore for the same reasons, many laboratories are failing In their endeavor to prepare reliable standard reference materials. The reason of this failure has its roots in the unability to estimate effectively the sampling characteristics of the element, mineral, or compound of interest, not to mention the unability to perform precise and accurate complete analysis, so essential for the instrumental analyst (1). In this paper a strategy to perform a better sampling operation is recommended. SELECTION OF A PROBABILISTIC APPROACH AS SOON AS PRACTICALLY POSSIBLE It Is essential to differentiate probabilistic sampling from non-probabilistic sampling. As Illustrated in Figure 1, the sampling operation Is a selection process which could be performed In two different ways: I. A probabilistic selection process according to which all elements of a lot of material to be sampled are submitted to the selection with a same probability of being selected. 2. A non-probabilistic selection process according to which all elements of a lot of material to be sampled are submitted to the selection with different probabilities of being selected.

Jan 1, 1986

By Nicholas J. Grant, Oliver Preston

A series of dilute solid solutions of a1uminum and silicon in copper, in powder -form, were internally oxidized, compacted, and extruded, to produce Cu-A12O3 and Cu-SiO2 alloys with 0.1 to 12 vol pct of oxide. Room-temperature tensile tests, creep-rupture tests from 450oto 850°C. conductivity measurements, and recrys-tallzzation studies were made. Oxide particle size and interparticle spacings were determined in an effort to relate the structure to measured strength values by means of known dispersion strengthening theories. A new dispersion strengthening theory, based on the effect of the dispersed phase on the retention of strain energy from the deformation step, zs proposed for this type of alloy, THE study of dispersion strengthening is of partitular interest in high-temperature materials technology in view of the excellent creep-rupture Properties and thermal stability achieved with SAP.1-5 Considerable effort has been devoted to this study in recent years, and encouraging results have been obtained in a number of systems.6 In general, the most

Jan 1, 1962

By Jerry Danni

In order to remain viable today, corporations must view the environment as a strategic issue, and integrate environmental management throughout the organization. Corporate programs that used to be based primarily on regulatory compliance now must emphasize strategic environmental management systems, and must integrate these environmental systems with basic business functions. The mining industry today is global, and must have an organizational structure that can embrace different cultures, physical settings, and regulatory regimes. Sound environmental management practices are not different from good management principles. An effective environmental management system should be a complementary system to an organization?s overall management framework, integrated and aligned with the existing management structure. Integrating environmental management into core business functions is just good business. An effective environmental management system is a critical component of a company?s commitment to environmental, social and economic accountability. This paper presents the elements of the Kinross Gold Corporation strategic environmental management system and discusses the integration of the environmental management system into the core business functions throughout the Company

May 1, 2003

By G. R. Fitterer, C. H. Herty

"INTRODUCTION Manufacturers and consumers of steel have come to realize during the past few years that cleanliness is of great importance in steels which must meet rigid specifications for various physical properties. Of equal importance is the consistent production of steel which is uniform in these properties. For maximum utility steels should be uniform not only from heat to heat, but also from ingot to ingot and within each ingot. In the manufacture of killed steels such as the higher carbon forging grades, uniformity as indicated by the usual chemical analysis in easy to obtain, provided that a normal top discard is taken, as is always the case in steels poured with hot—top practice. No such uniformity, however, holds true for the nonmetallic matter, which consists for the most part of the products of deoxidation of the steel.For a large tonnage of steels which go into articles manufactured by deep—drawing processes, killed steel has never been successfully applied because with the present deoxidation practice, low—carbon killed steel is almost invariably extremely dirty. To obtain the desired qualities for deep drawing, the steel is rimmed, — that is to say, deoxidized with manganese and perhaps a small amount of aluminum, — the resultant product being of high purity in the skin of the ingot, but very badly segregated at the center of the ingot, particularly in the upper—central section. This segregation necessitates a very heavy top discard, and one of the major segregates is carbon which renders the steel too hard to draw properly. If clean, low—carbon killed steel could be made successfully, much better ingot yields would be obtained than by the present rimming steel practice. Furthermore, banded structures and outside and inside seams, which are undoubtedly due in a large measure to blowholes in the ingot, are defects which are very difficult to control in rimmed steel. These defects would be minimized by clean killed steel."

Feb 1, 1931

By D Vidyarthi

Blasting is the most important activity in the mining industry, the world over. It is a well known fact that only part of the explosive energy gets utilized in causing the actual rock fragmentation. The rest of it gets converted into blast-induced ground vibrations and noise. Though blast vibrations cannot be totally eliminated, it is possible to minimize them by optimization of blast parameters. This paper highlights various in-house efforts put forth by the author towards site specific blast optimization and the monitoring of blast vibrations. It also deals with the prediction curves developed by regular regression analysis for the prediction of ‘blast vibrations’, ‘peak particle velocity’, ‘safe charge’ for various blasts.

Jan 1, 2007

By F. J. Cservenyak

The Bureau of Mines Solid Waste Program is directed toward three main areas of research: (1) Extraction of mineral, metal, and energy values from urban refuse; (2) recovery of mineral and metal values from wastes generated in the industrial extraction, processing, and utilization of raw materials and mineral-base products; and (3) upgrading and utilization of automotive scrap. The Bureau also has a contract and grant program which supplements the in-house research and aids in the training of personnel in the proper management of mineral- and metal-based solid wastes.

Jan 1, 1970

By J. Organiscak

A majority of continuous mining machines employ a water spray system and a machine-mounted flooded-bed scrubber to suppress and capture dust during coal mining. These machine-mounted dust control systems must be designed to function within the localized face ventilation system at the mining section to control both dust and methane. Spray systems can impede or improve the scrubber effectiveness in controlling dust or methane at the mining face. Laboratory experiments were conducted to examine the effect of spray type, spray pressure, machine body blocking sprays and scrubber airflow on dust and gas levels, while using a 12.2-m (40-ft) exhaust ventilation curtain setback from the face. These experiments were conducted with the mining machine positioned at the end of a simulated 6.1-m (20-ft) sump and slab cut. Results indicate that the hollow cone nozzles with blocking sprays best complement the flooded-bed scrubber performance in an exhaust ventilation system. This external spray system notably reduced dust and gas levels on the off-curtain side of the mining machine for both the sump and slab cut compared to the flat spray nozzles. Higher scrubber airflows reduced dust and gas levels on the curtain side and in the return of the continuous mining machine. The remote operator position, located on the off-curtain side and parallel to the inlet end of the exhaust curtain, sustained the most stable and lowest dust levels around the mining machine.

Jan 1, 2010

By David Wilson, T. V. Rao

INTRODUCTION The Alchem trona mine, owned and operated by Allied Chemical Corp., is located approximately 32 km (20 miles) west of the town of Green River, and 8 km (5 miles) north of Interstate 80 in southwest Wyoming. Trona, a naturally occuring sodium sesquicarbonate (NaCO3 • NaHCO3 • 2H2O), is used for the production of sodium carbonate (Na2CO3), commonly known as soda ash. Present annual US consumption of soda ash is approximately 9.07 Mt (10 million st), out of which approximately 7.3 Mt (8 million st) is produced from the Wyoming trona mines. About 44% of soda ash is consumed by the glass industry; 3 % by exports; and the remaining portion by paper, chemical, soap, textile, and nonferrous industries. Allied Chemical operates an underground mine at an average depth of about 488 m (1600 ft). There are three other trona mines in the area operated by FMC Corp., Stauffer Chemical Corp., and Texasgulf Inc. (see Fig. 1). Allied Chemical became interested in southwest Wyoming trona deposits in the early 1940s. Explora¬tion work was begun in 1959 with the acquisition of federal leases. Exploitation of the reserves began in 1968. Two shafts, one 6.1 m (20 ft) and another 3.7 m (12 ft), were completed prior to 1968. The 6.1-m (20-ft) diam service shaft is divided in half by a cur¬tain wall, with one half used for men and material and the other for ventilation as a return air shaft. During the period from 1968 to 1974, the 3.7-m (12-ft) shaft was used as production shaft with two 7.3-t (8-st) skips. Due to the increased demand for soda ash, plant and mine expansions were completed during 1974. Under this expansion, the material handling system capacity was increased by constructing a new 2721-t (3000-st) capacity ore bin, sinking a 6.1-m (20-ft) diam produc¬tion shaft, and installing a friction hoist with two 22.7-t (25-st) skips. The Alchem mine manpower is 484 employees and about 2.3 Mt (2.5 million st) of trona was produced during 1976. Three different mining systems are used at the Alchem mine: conventional, continuous, and longwall. Allied Chemical introduced its first longwall unit in 1973, which was also the first longwall system introduced in the Wyoming trona district. At present, four conventional, seven continuous, and two longwall units are in operation. This equipment is operated in ten production areas. GEOLOGY The bedded trona and trona-halite in the Green River basin of southwestern Wyoming is a major re¬source for the nation. There are 25 beds that exceed 0.9 m (3 ft) in thickness and underlie areas of about 2590 km2 (1000 sq miles). There are other minor beds that range in thickness from 0.3 to 1.2 m (1 to 4 ft). Allied Chemical's Alchem mine is located in bed 17. The trona bed numbering system starts at the lowest elevation and increases upwards. The trona beds are in the Wilkens Peak member of the Green River formation. The Green River formation was deposited in a lake that began in early Eocene as a large body of fresh water, shrank in size and became saline, and then became fresh water again. The sedi¬ment during the saline phase of the lake, which includes the trona beds, is called the Wilkens Peak member. The underlying freshwater lake deposit is called the Tipton member and includes a 25.9-m (85-ft) sand unit which is a high pressure, low permeability aquifer. The over¬lying sediment is called the Laney shale. The Green River formation is underlaid by the Wasatch formation and overlaid by the Bridger formation (see Fig. 2). The structure of the beds in the area of the Allied Chemical mine is mostly postdepositional asymmetrical folds of small amplitude. These folds range in size of 3 to 6.1 m (10 to 20 ft) to as much as 45.7 m (150 ft). The trend of the folds is northwesterly with the north¬east flank of the anticlines having a steep dip and the southwest having gentle dips. Trona bed 17 varies in thickness from 2.4 to 3.4 m (8 to 11 ft) over the 93.2 km2 (36 sq miles) holdings of Allied Chemical and is flat lying except for the rela¬tively minor folding and a negligible regional dip of about 0.017 rad (1°). Trona occurs naturally in several physical forms in the Green River basin, being both massive and crystal¬line. The trona ore in the Alchem mine is a fine-grained massive ore with a compressive strength of approxi-

Jan 1, 1982

This paper describes major technical developments in rod mill design and operating practice since its introduction into the North American minerals industry over fifty years ago. The basic operating characteristics of the wet, overflow rod mill are described, and significant operating variables are reviewed in terms of their effects on mill power draw, power efficiency, and practical aspects of circuit operation. Key factors for improving the economic performance of rod milling circuits are identified.

Jan 1, 1986

By R. A. Swalin

IN this paper, the results of an investigation concerning the diffusion of three elements, magnesium, silicon, and molybdenum, in nickel are presented. The work represents a continuation of a diffusion program relating to solute diffusion in nickel. The program has the dual aim of obtaining useful diffusion data and of yielding insight into the factors governing solute diffusion in close-packed metals. The first paper of this series has been published earlier? In both investigations, in agreement with recent results from other laboratories, the activation energies for solute diffusion were found to be close but not identical to that of self-diffusion in the pure solvent in question. In order to obtain valid diffusion data, certain experimental pitfalls recognized only in recent years had to be avoided. Chief among these were the necessity for minimizing short-circuiting diffusion paths such as grain boundaries and the necessity for using low solute concentration gradients. In this series of investigations the following precautions were taken in an attempt to minimize such errors. 1) Samples with large grain sizes, 0.5 to 10 mm, were prepared. 2) The diffusion coefficients were measured at relatively high temperatures, since imperfections such as dislocations play a less important role at such temperatures than at lower temperatures. 3) Alloys containing less than 1 atomic pct were chosen for study. Experimental Work Materials—A diffusion couple technique was employed in the experimental investigation. Briefly, this technique consisted of the following. A diffusion couple was fabricated by placing a flat face of a cylindrically shaped alloy disk against a similar face of a pure nickel disk, and a bond was formed at an intermediate temperature under pressure. The diffusion couple thus fabricated was subjected to a diffusion anneal at higher temperatures for a measured period of time and then sectioned perpendicular to the direction of diffusion. After analyzing the sections for solute concentration the diffusion coefficient was determined from a probability, plot of concentration vs distance from the diffusion interface. Vacuum melted Mond nickel was used in the experimental program. The chemical analysis of this nickel is listed in Table I. Alloys used were prepared

Jan 1, 1958

By Everett P. Partridge, J. E. Conley

Available statistics show that the demands of the American chemical industry for sodium sulphate have been increasing slightly in recent years. The supply from domestic sources, particularly in the form of byproduct salt cake from the acid manufacturers, has been tending to decrease this to the growing manufacture of synthetic acid. Both hydrochloric and nitric acids are being synthesized from their elements. The natural result has been that a smaller amount of salt cake is available. Simultaneously, the expansion of the kraft-paper industry, especially in the South, has brought about greater demand for sodium sulphate in that section. This demand is being met by domestic byproduct salt cake, by imported German sodium sulphate made from potash waste liquors, and by favorably situated domestic deposits of Glauber salts and the anhydrous salt, thenardite. No shortage of natural sodium sulphate exists in the United States, but usually such deposits occur in semiarid regions far removed from transportation facilities and from markets. Moreover, the major portion of the natural deposits is Glauber salt or mirabilite (Na2 504 • 10H20), which must be dried or dehydrated in order to meet consumer requirements. The water of hydration represents, roughly, 55 percent of the total weight of the crude salts and therefore has a very important influence on transportation costs, in many instances the cost of getting even the dehydrated product to market is the deciding economic factor. Therefore, the recovery of production of anhydrous sodium sulphate from plant-waste liquors or from natural brines of suitable composition might be economically feasible.

Mar 1, 1936

This paper examines the new water-hydraulic (hydropowered) drill rigs that have been developed and proven in the last decade primarily in tabular, shallow-dipping, narrow-reef hard-rock South African mines. These include drill rigs for flat-end tunnel development, narrow inclined raises and winzes, large inclines and declines and longhole-based developments such as ore passes and vent raises. The hydropower technology rigs offer advantages both in safety and performance over traditional compressed-air-powered, hand-held development, and are generally more cost-effective than imported oil electro-hydraulic drill rigs. Furthermore, hydropowered rigs are inherently energy-efficient. The benefits of hydropower are discussed and a ?comprehensive development model? is presented which demonstrates that ore-bodies can be accessed in significantly shorter times. ?Localized? half level hydropower systems are introduced and a range of ancillary equipment available is listed.

Jan 1, 2012

By E. S. Wheeler

THE conversion plant of the Climax Molybdenum Co. is at Langeloth, Washington County, Pennsylvania, approximately 30 miles west of Pittsburgh. The molybdenite concentrates converted originate in the company's mine and mill at Climax, Colorado.1 They are delivered to the Langeloth plant by rail packed in 175-lb. bags. War production of concentrates at the mill started in 1918 but it was not until about 1920 that any peacetime uses of the metal began to develop. Early conversion of Climax concentrates was mainly into ferromolybden um, produced for the company by a custom smelter. CHRONOLOGY OF PLANT DEVELOPMENT In 1924 a small hand-rabbled roaster was built at Langeloth, the roasted concentrates being used principally in the production of calcium molybdate by a conventional wet method. The size of the original plant is indicated by the fact that during 1925 about 400,000 lb. of molybdenum was converted. In 1925-1926, a multiple-hearth roaster was erected (12-ft. o.d. 8-hearth Nichols-Herreshoff); also the first experimental ferromolybdenum was produced at Langeloth. At this time calcium molybdate was produced in the furnace by a process to be described. With continued interest in and increased use of molybdenum, it was necessary to arrange for enlargement of plant facilities. Although only one 12-hearth 16-ft. o.d. roaster was erected at this time (1929), plans were prepared for a duplicate unit, which was completed in 1935, giving a potential roasting capacity of some 16,000 lb. Mo per day under the then prevailing roasting practice. Shortly after this second unit had gone into production, increased demand overtaxed the plant, and as a result two 12-hearth 18-ft. o.d. roasters were placed in operation in 1936 and 1937. This gave the plant a potential roasting capacity of 40,000 to 50,000 lb. Mo per day, and necessitated major changes in auxiliary handling equipment as well as improved facilities for producing ferromolybdenum. Following the introduction (1938) of a new product-molybdic oxide briquets and because of the constantly growing demand for molybdenum, plant facilities were again enlarged in 1940 and 1941 by the erection of two 16-hearth 18-ft. o.d. roasters. These two new units, along with a change in roasting practice, brought the potential roasting capacity to 150,000 to 190,000 lb. Mo per day, based on about 15 lb. per sq. ft. of hearth area. Other departments of the plant have necessarily grown, until today the plant is modern throughout and completely mechanized, with equipment geared to produce marketable products as follows:

Jan 1, 1944