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By A. L. Blomfield, M. J. Trott

ThE Golden Cycle Mining and Reduction Co. operates its custom mill at Colorado Springs on Cripple Creek ores exclusively. These ores are straight sulfo-tellurides, with practically no base metals such as Pb, CU, Zn, As, or Sb. Upon entering the mill, the ore all passes through the sampler to storage bins, where beds of 5000 tons each are made to insure uniformity in roasting. Classification of ORes For efficiency, it has been found advisable to separate the ores into two classes according to their lime content. Other constituents have their effect, such as alumina and magnesia, but, speaking generally, these are roughly proportional to the lime, which, as CaO, is used as the indicator. Class A contains not more than 2 per cent. CaO and comprises about 66 per cent. of the ore treated. Class B contains over 2 per cent. CaO, and comprises 34 per cent. of the ore treated. Typical analyses of both classes are as follows: Class A a B Insol.......................... 86.70 75.90 Al2O3........................:.. 2.30 3.40 Fe.............................. 3.26 3.48 CaO............................. 1.57 5.12 S............................... 1.79 1.80 MgO........................... 0.21 1.08 Ignition loss..................... 3.20 6.50 99.03 97.28 The beds of each class of ore are made as large as possible with the available ore as it comes in, to avoid changing from one bed to the other any oftener than necessary. Each roaster will handle 50 per cent. more of class A ore than of class B, with practically the same results. This necessitates changing the rate of feed for each new bed and tends toward a poor roast and loss of tonnage at each change.

Jan 1, 1919

By Frank C. Stevens

Many changes have taken place in the "World Cement Market" since Joseph Aspdin discovered portland cement in the early 1800's. At the turn of the century, production of cement world wide was a few million tons; today, it is over one billion tons. By 1995, world production is estimated to reach 1.2 billion tons. Cement processing has changed from inefficient, small vertical kilns to large efficient, precalcining kilns, and large automated crushing, blending and grinding systems. Consequently the cost of production has declined in real terms, resulting in significant economic benefits to the general public. In addition, quality and uniformity of cement have increased, strengths have increased, and at least 25% fewer pounds of cement are needed for each cubic yard of concrete. Today, cement moves thousands of miles on the inland rivers and great lakes of the U. S., across Siberia and across the oceans of the world. The volume of cement moving more than a few hundred miles is almost 100 million tons, or 10% of world production. Today, on a per ton basis, it costs no more to move 40,000 tons of cement to the United States from the Western Pacific rim or from Europe than it does to truck cement 200 miles. For example, cement shipped by water from Spain costs $5.00 to $7.00 per ton compared to cement shipped by truck 200 miles at $16.00 per ton. This low cost water transportation has been a major factor for the increased movement of cement between countries. Table 1, Cement Production Summary-World, gives a global picture of production, export and import tonnages in recent years. Figure 1 is a graph showing CEMENT PRODUCTION SUMMARY WORLD WIDE.

Jan 1, 1987

By Zhao-shu Sun, Mao-lin Li, Rui Cui

"Fankou Mine produced pyrite concentrate (PC) from the tailings by rougher and scavenger flotation before 2010, with the averaged S grade of 40.54% at recovery of 79.34%. The economic value of PC increases with its purity. When the S grade of PC feed to sulfuric acid plant is over 47%, the pyrite cinder can reach a high Fe grade of 62% which can be directly sold as iron concentrate. On this background, engineers in Fankou Mine set the PC with S grade of 47% as target.The direct way to reach that goal was to clean the rough PC Lots of cleaner flotation tests were conducted and the balanced strategy was to produce two ranks PC with the S grade of 47% and 38% at the recovery of 44.20% and 36.17%, respectively. The dual-product flowsheet was successfully industrialized in 2010. In order to further improve the quality of PC, gravity separation was introduced into the flowsheet. The numerical simulation and tests were performed to evaluate the beneficiation and classification performance of hydrocyclone as it treated the rough PC. It was shown that the underflow of hydrocyclone could addressed the S grade of 47%, and the finer size overflow could also be enriched to PC with S grade of 47% by flotation, due to the contained pyrite with well liberation. That is to say, with the ingenious addition of hydrocyclone to treat the rough PC, single PC with S grade of 47% could be achieved. The new flotation-gravity separation flowsheet was commissioned to produce the high quality PC at the end of 2013. The averaged S grade is 47.20% at recovery of 82.26% in 2014. The two steps flowsheet improvement maximizes the enterprise benefits and leads to simple utilization of Fe in pyrite in downstream industry."

Jan 1, 2016

By E. W. Murbach

The oxidation of uranium carbide by oxygen at various pressures, and by air, has been investigated at temperatures up to 600°C. Arc-melted and cast uranium carbide displays oxidation behavior that appears to be dependent on its treatment after melting. ccReactive" uranium carbide, which results from exposure of freshly melted material to laboratory air, ignites in oxygen at about 275° to 350°C depending on pressure, and in air at about 350°C. The product of the initial oxidation appears to be UO2+.. Continued heating produces U30,. The initial oxidation rate is poportional, roughly, to the square root of the oxygen pressure. The activation energy determined for the initial oxidation reaction is 7.1 kcal, from 400° to 600°C in 10 mm of oxygen. AN investigation of low-decontamination methods for reprocessing uranium carbide reactor fuels is being carried out at Atomics International. One of the reprocessing cycles includes oxidation of the fuel at relatively low temperature (300° to 500°C) and reaction of the product oxide with carbon at elevated temperatures (above 1500°C) to produce uranium carbide. A number of small-scale experiments have been carried out in which uranium carbide was oxidized in air and oxygen at various pressures to measure reaction rates and to obtain other information concerning the oxidation process. In initial experiments with arc-melted UC, ignition was observed at about 275°C in oxygen or 350°C in air. However, similar experiments by Neymark' at 426°C in air showed no ignition. It was soon determined that the difference in oxidation behavior was due to the treatment of the UC following arc-melting. Neymark's experiments were carried out with freshly melted UC while those reported in the

Jan 1, 1963

By Jack L. Taylor

WITH the exception of the work of Vogel,&apos; and Rolla and Iandelli, very little information has appeared in the literature on titanium binary systems with the rare earth elements. Rare-earth additions to titanium alloys may possibly parallel the beneficial effects on the physical properties of certain steels. Having this in mind, some knowledge of solubility limits and intermediate phases, if any, would be useful. An investigation of the titanium-rich Ti-Ce system was started. Alloy Preparation The iodide titanium from the New Jersey Zinc Co. and the cerium metal from the Institute for Atomic Research Ames Laboratory used in this work were supplied with the typical analysis shown —iodide titanium: 0.0065 pct Mn, 0.0022 pct Fe, 0.0015 pct Cu, and 0.0042 pct Pb; cerium metal: <0.01 pct Fe, <0.03 pct Si, <0.05 pct Ta, <0.02 pct Pr, <0.03 pct Ca, <0.02 pct Mg, with no trace of Nd, La, or Th. The cerium metal, stored in oil, was washed and scraped just before weighing into capped cups machined from iodide titanium. The cold hearth helium-arc furnace described by Schramm et al3 was used for melting. The alloy buttons from the arc-melted cup were cut in two, mounted, and examined. Homogeneous alloys were demounted and rolled to approximately 1/4-in.sq bars. Sections l/8 in. thick were cut from the bar to provide samples. The Ti-Ce alloy buttons analyzed for cerium were of the following composition: 0.19, 0.36, 0.48, 0.61, 1.15, 2.52, 3.06, 3.70, 4.30, 9.20, 14.26, and 18.50 wt pct. Nominal

Jan 1, 1958

By C M. Ramotsabi, F Bornman, W Erasmus

Spiral concentrators are gravity based separation devices used for the preparation of coal, iron and heavy mineral ores (Wills, 1992). Gravity concentration remains the main separation method for fine iron ore and is used extensively for treating many minerals. Gravity concentration methods separate minerals of different specific gravity by their relative movement in response to gravity and one or more other forces, the latter often being the resistance to motion offered by a viscous fluid such as water or air (Wills, 2006).The main operating variables for a spiral concentrator are the feed rate, the slurry concentration, the wash water addition and the position of the splitters used to separate the tailings, middlings and concentrate streams (Sadeghi, Bazin and Renaud, 2014). Wash water is an important control variable used to wash away entrapped light minerals from the concentrate stream (Burt, 1984; Bouchard, 2001). Sadeghi et al concluded the spiral operation to be sensitive to the wash water flow addition and resultant economic trade-off. Increasing the wash water flow rate increases the concentrate grade at the expense of the iron recovery.The paper addresses the effects of dripping wash water onto the concentrate stream of a spiral processing fine iron ore. The dripping wash water system offers a low flow alternative and could possibly provide a good balance between grade and recovery of valuable minerals without using excessive water. The Multotec SC20HC/7 WW spiral was used for the experimental test work. The spiral was tested at varying solids concentrations; the wash water rate and the splitter positions were kept constant.The use of wash water at 30 per cent, 35 per cent and 40 per cent solid concentration improved the Fe grade in the concentrate by about 1.5 per cent, six per cent and eight per cent respectively. The additional SiO2 rejected by the wash water is approximately three per cent, nine per cent, and 11 per cent at 30 per cent, 35 per cent and 40 per cent solid concentration respectively. Addition of wash water is shown to have minimum effect on grade at 30 per cent solid concentration, and Fe upgrades obtained with and without wash water were found to be similar. Notable upgrades were observed at 35 and 40 per cent solid concentration with wash water. The results obtained suggest that the additional SiO2 rejection by wash water increases with an increase in solid concentration. This suggests that the benefit of using the drip system is notable at higher solid concentration. It is believed that at lower solid concentration SiO2 particles are reasonably free to move around and are possibly less entrapped than at high solid concentration.The Fe grade/recovery and solid concentration relationship with wash water showed a non-linear correlation. The Fe grade increases with an increase in solid concentration up to a somewhat optimum point and then drops as solid concentration increases further. The recovery of Fe on the other hand follows a converse relationship with solid concentration, the recovery decreases from 30 per cent to 35 per cent solid concentration and then increases again at 40 per cent solid concentration. The increase in recovery at higher solid concentration could possibly be explained by the fact that the mass yield to concentrate also increases with solid concentration. Since recovery is a function of both grade and mass yield, the higher recovery at 40 per cent solid concentration is likely due to the high mass yield obtainable at 40 per cent solid concentration.The drip system could therefore possibly offer a safe guarding against grade and solid concentration variations without using excessive water, and possibly ensure that a product within specification is maintained.CITATION:Ramotsabi, C M, Erasmus, W and Bornman, F, 2015. Optimisation of wash water on an iron ore spiral to improve grade, in Proceedings Iron Ore 2015, pp 175–184 (The Australasian Institute of Mining and Metallurgy: Me

Jul 13, 2015

By O Rojas

The Tel&#233;grafo copper – gold deposit is located in the Centinela district of the Antofagasta region in northern Chile. Tel&#233;grafo is a porphyry copper deposit of Eocene – Oligocene age which has a total mineral resource in measured, indicated and inferred categories equal to 2.6 billion tonnes with an average grade of 0.38 per cent copper.Currently the project is in the prefeasibility study phase, including an infill drilling campaign to improve the knowledge of the deposit that should result in an improvement of the mineral resource classification. In this context was decided to review the classification criteria in order to optimise the drill hole density necessary to support the project.This paper presents an application of conditional simulation to evaluate the risk related to drill hole spacing, using a geostatistical approach that mimics the process of evaluation of resources from the perspective of geological modelling and grade estimation. The first step of the approach is the generation of conditional simulations using the available samples to generate several plausible scenarios of the deposit in terms of copper grades and geological units. These scenarios are considered as the unknown reality of the deposit and sampled by synthetic drill holes in order to replicate the geological model process and copper resource estimation. In this way it is possible to establish differences between the possible scenarios and the generated resource estimation models for several simulated drill hole spacing alternatives. These differences or errors can then be quantified in terms of estimated mean, metal content and tonnage over different production volumes.The resulting errors were useful in assisting the decision making process related to the design of drill hole spacing for each category of mineral resource in the Tel&#233;grafo project, and to redistribute the budget associated to the drill campaigns for the next stage of the project.

Aug 22, 2011

By J. Gartelmann, B. Zaslavsky, Y. Vojta, D. J. Chaiko, W. Mego, A. N. Rollins

"Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that we have studied are generated by combining an aqueous salt solution with an aqueous polymer solution.We have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. We have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this chapter we review the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation.IntroductionAqueous biphasic extraction (ABE) is a highly adaptable separation technique that can be used in a wide range of applications. We have been evaluating various types of ABE systems for possible applications in the treatment of solid radioactive wastes (1,2), liquid nuclear wastes (3,4), and contaminated soils (5-7), and in the removal of organics from aqueous salt solutions (8). We have also conducted fundamental studies of the solution microstructure of ABE systems using small angle neutron scattering (SANS) (9).The extraction systems are generated by combining an aqueous salt solution and an aqueous polymer solution. This produces two distinct liquid layers that are as immiscible as oil and water, yet each liquid layer contains at least 70 to 80 wt % water. The biphasic systems that we have been working with consist of immiscible polyethylene glycol (PEG) and salt solutions. Some inorganic salts that promote biphase formation with PEG solutions include the sodium/potassium salts of sulfate, carbonate, phosphate, and hydroxide (10)."

Jan 1, 1996

By Joseph Bernhardt

THE Cornwall Ore Mines, Division of the Bethlehem Steel Co., at Cornwall, Lebanon County, consists of two separate magnetite ore bodies, approximately one mile apart. The one ore body was an outcrop in which open-pit mining operations were begun in 1742 and continued without interruption. This mine is also served by a shaft for mining that portion of the ore body not recoverable by open-pit methods. The other property had no outcropping and is entirely an underground operation. This mine, cap-tioned No. 4 mine, is serviced by two shafts 220 ft apart. The No. 4 shaft is for hoisting rock and ore, and the No. 5 shaft is for handling men and ma- terials. The shafts are on a catenary curve, closely following the dip of the ore body. Slope of the shafts at the collar is 36", flattening to 26" at the bottom. The footwall at Cornwall is a traprock which varies structurally from solid to highly fractured. Grizzly stations at the top of each chute raise were reinforced by setting timber sills on concrete. Occasionally it was necessary to concrete the entire chute raise. Concreting was done by using 35-yd electric mixers set up in the breaking subs. Sand, stone, and cement were hoisted up through the chute raises to the breaking subs. Late in 1937 it was decided to eliminate chute raises and breaking subs in future development. Haulage levels are 50 ft apart vertically. When ore is below a 40 " dip, slushing drifts are driven normal to the haulages and on 40-ft centers. In a few areas, ore dips greater than 40" and slushing drifts are then placed parallel to the haulage drifts. Finger raises are opposite each other and on 20-ft centers making 20x20-ft draw areas (fig. 1). For loading

Jan 1, 1951

By Joseph Bernhardt

THE Cornwall Ore Mines, Division of the Bethlehem Steel Co., at Cornwall, Lebanon County, consists of two separate magnetite ore bodies, approximately one mile apart. The one ore body was an outcrop in which open-pit mining operations were begun in 1742 and continued without interruption. This mine is also served by a shaft for mining that portion of the ore body not recoverable by open-pit methods. The other property had no outcropping and is entirely an underground operation. This mine, cap-tioned No. 4 mine, is serviced by two shafts 220 ft apart. The No. 4 shaft is for hoisting rock and ore, and the No. 5 shaft is for handling men and ma- terials. The shafts are on a catenary curve, closely following the dip of the ore body. Slope of the shafts at the collar is 36", flattening to 26" at the bottom. The footwall at Cornwall is a traprock which varies structurally from solid to highly fractured. Grizzly stations at the top of each chute raise were reinforced by setting timber sills on concrete. Occasionally it was necessary to concrete the entire chute raise. Concreting was done by using 35-yd electric mixers set up in the breaking subs. Sand, stone, and cement were hoisted up through the chute raises to the breaking subs. Late in 1937 it was decided to eliminate chute raises and breaking subs in future development. Haulage levels are 50 ft apart vertically. When ore is below a 40 " dip, slushing drifts are driven normal to the haulages and on 40-ft centers. In a few areas, ore dips greater than 40" and slushing drifts are then placed parallel to the haulage drifts. Finger raises are opposite each other and on 20-ft centers making 20x20-ft draw areas (fig. 1). For loading

Jan 1, 1951

By Robert A. MacGregor

"Following several months of test work, water leaching in mined-out areas at Stanrock commenced on a production basis in February, 1963. A combination of fast high-pres-sure washing and rewashing of stopes on a predetermined cycle, and the intermittent sprinkling of low-grade heaps, using both fresh water and recirculated acid water, has proved most successful. There was also a correlation of daily sampling data points to a relationship between the leach water grade and the grade of the material being washed, the leaching time and the location along the dip. An increasing tolerance for uranium by the acid-producing bacteria is also indicated. A steady production rate of 10,000 to 12,000 lbs. of u.08 per month is being maintained, with an over-all mine water grade of 0.25 lb. per ton and a pH of 2.3."

Jan 1, 1966

By Geraldo Morón

En este trabajo, Minera Aurífera Retamas S.A., Es una empresa de minería subterránea dedicada a la exploración, explotación, beneficio y comercialización de oro. Dentro de su política organizacional viene asignando recursos y orientando esfuerzos en la gestión ambiental para calcular, reducir y compensar la Huella de Carbono producto de su actividad minera desarrollada en su Unidad Económica Administrativa Retamas, (UEA Retamas), la cual geográficamente se ubicada al norte del territorio peruano y políticamente en el distrito de Parcoy, departamento de La Libertad. La gestión ambiental adoptada por MARSA en su UEA Retamas radica en tres etapas principales; Calcular, Reducir y Compensar la Huella de Carbono.

Sep 1, 2017

By H. F. Bishop, F. A. Brandt, W. S. Pellini

The solidification mechanism of experimental steel ingots (7x7x20 in.) was studied by thermal analysis. It was determined that solidification proceeds in wave-like fashion at rates which are determined by the carbon level, superheat, and mold thickness. The thermal cycles of the mold walls were related to the course of solidification. ESPITE marked advances in the field of solid state transformation, metallurgical research has contributed comparatively little exact quantitative data on the mechanism of solidification of metals. There is, therefore, a great need for such data in the various metallurgical industries. The mechanics of solidification of ingots have been investigated in the past primarily by studies of the rate of skin formation as indicated by bleeding or "pour out" tests. The "pour out" method, however, is a tool which gives only approximate information. In the case of alloys with wide solidification ranges, such as irons and certain nonferrous alloys, the method will not work at all; in the case of alloys of intermediate solidification ranges, such as commercial steels, the information may be misleading. Thus, the general adoption of this method has resulted in divergent conclusions regarding the solidification process. Chipman and Fondersmith1 by means of bleeding tests have shown that the linear growth of a solidifying ingot wall follows a parabola of the general form, D = K C, with the start of solidification delayed until superheat is exhausted, as indicated by the constant C. These tests were carried only to a wall thickness of about 5 in. using an ingot of approximately 17x39 in. in cross-section; hence the latter stages of solidification were not studied. Matuschka2-3 indicated that linear solidification of ingots is rapid at first, then slow, but toward the end of solidification the rate becomes extremely rapid again. Spretnak&apos;s4 bleeding studies indicated that, wall growth is expressed more rigorously by two parabolas, and that their point of intersection corresponds to a change of solidification mode from columnar to equiaxed. Spretnak also showed that the K values of the first parabola are always the same regardless of superheat. Nelson bled ingots of square cross-section and found that linear wall growth is initially rapid but decreases continually until the end of solidification. He also concluded that rate of solidification in ingots of square cross-section increases 2.15 pct for every 10 pct increase in cross-sectional area of the mold. The mold ratios considered (ratio of cross-sectional area of the mold to cross-sectional area of the ingot) were all less than 2 to 1. The subject of solidification has also been treated mathematically in many cases, but because of the lack of accurate thermal constants and the simplifying assumptions required, as their authors generally acknowledge, they represent only approaches to the actual conditions of ingot solidification. A third method of studying solidification is the electrical analogue method promulgated by Pasch-kis6-7 and by Jackson and coworkers.8 This method treats solidification as a heat transfer problem with the solidification cycle synthesized on an electrical circuit. Paschkis in his treatment of solidification considered the fact, which was generally ignored, that solidification of steel is not simply the growth of a plane solid wall but a more complex process occurring over a temperature range as indicated by the constitution diagram. Undoubtedly, the anomalous results obtained by bleeding tests arise from the inability to measure quantitatively this mushy condition. The shape of Paschkis&apos; solidification curves are more nearly in accord with those of Matuschka, in that they indicate rapid linear solidification at the beginning and end of solidification with intermediate solidification occurring at a slower rate. Paschkis indicates a definite lengthening of solidification time with increasing superheat. Thermal analysis is a direct method providing exact information for all types of metals regardless of solidification range and was thus adopted in the present program to follow the entire course of solidification from the surface to the centerline of the ingots. The method has the added advantage of being adaptable to following the thermal cycle of the ingot mold during the course of solidification. Test Methods The ingots studied were of square cross-section, 20 in. long, tapered from 71/4 in. at the top to 63/4 in. at the bottom, and fed with a hot top 7 in. in diam and 12 in. high. The molds were uniform in wall

Jan 1, 1953

By Tzung-mow Yao, S Ki, J Word, J Vinson

Properly designed evapotranspirative (ET) cover systems can greatly reduce the amount of infiltration and groundwater recharge (deep percolation) into potential acid generating mine waste. In arid and semi-arid environments, infrequent precipitation, low measurable subsurface fluxes, spatial variability within mine waste and cover material, and evapotranspiration from below the cover system create challenges to monitoring moisture flux in these systems. Sloped ET single-layer (monolayer) cover depths and a variety of reclamation treatments are being studied at a copper tailing impoundment in Arizona, USA. To monitor the performance of different ET cover systems in response to precipitation patterns, four different test plots consisting of two different cover depths and two different vegetation densities were instrumented with heat dissipation sensor nests. The sensors measure the soil water pressure potential and allow hydraulic gradients to be determined within and below the cover systems to depths of 180 cm. Three replicate sensor nests were installed in each test plot to account for variability in materials and test plot treatments. Data collection occurs twice daily and is ongoing. Weather during the 26-month monitoring period was characterised by two months of greater than normal precipitation followed by nine months of normal precipitation and 15 months of abnormally dry conditions. Monitoring data indicate that deep percolation occurs in response to periods of extended precipitation, however, drying was observed to depths of six feet below the surface in all test plots. Using conservative assumptions regarding tailing hydraulic properties, one-dimensional downward flux predictions based on the monitoring data indicate very low (Additional long-term monitoring and installation of deeper and replicate monitoring sensors into tailings without cover systems are recommended to evaluate the long-term ET cover system performance and develop a better understanding of deep percolation rates at the sites.

Jan 1, 2003

By John V. Beall

The mining industry of Japan is not very large, but it is very old. Some of the mines have 1000 years of history. At Nara, the capitol 1300 years ago, the great Buddha of bronze that was cast at that time was of metal mined from several localities in Japan including the Akenobe-Ikuno district, one of the present Mitsubishi properties. Methods of smelting copper and iron, it is believed, came from China via Korea. A characteristic of the Japanese mining industry today is one of buying abroad and treating at home, a variety of ores of different compositions. All in all, Japan&apos;s mineral deposits under its own flag are inadequate for its great industrial strengths.

Jan 5, 1969

By R. W. Bartlett

The extensive central Idaho black sand placer deposits are a potential source of rare earth elements, particularly the heavy rare earth elements that are not prevalent in commercial bastnasite deposits. These placers derive from the Idaho batholith. The geology, occurrence, and extent of these deposits are reviewed and the diverse mineral assemblages and complex mineral chemical compositions of these sands are described. Niobium, yttrium and thorium are also present in significant concentrations. The results of prior mining practice, including concentration and separation of the heavy minerals are reviewed. Technical approaches to extraction of rare earths from Idaho black sand concentrates are discussed.

Jan 1, 1992

By B. R. Conard

Copper refining at Vale Canada (previously known as Inco) has been associated with Ni production. Because Cu and Ni carry risks for adverse health endpoints through inhalation exposure, it is critical that their aerosol levels, and the metallurgical processes through which they enter the air, are understood. Because certain Ni substances have been linked to respiratory cancers, it is also important to characterize the amounts and types of Ni compounds in occupational settings. This paper describes electrorefining and electrowinning operations near Sudbury, Ontario (1930–present), and gives aerosol measurements (1978–present).

Jan 1, 2014

By R. Hendricks

"IT IS a pleasure for me to appear before yon today and to have this opportunity of reviewing with you recent developments in the world lead and zinc industry. To provide essential background material, I propose reviewing the period from 1950 to the present, a period which has undoubtedly been the most hectic in the long history of the industry.In capsule form, the pattern for this period is one of repeating cycles of boom and recession, of failure through research to develop adequately new markets and new uses for lead and zinc, of surplus production and growing inventories, of price instability, and lastly, of an abdication in some sections of the industry of responsibility for control of its own destiny by turning to governments for support in time of stress. This is not a pretty picture but, as the 1950 decade ends, there are signs of a new maturity and of a growing determination on the part of the industry to put its own house in order.The difficulty suffered by the world's lead and zinc industry in the current decade originated with the support extended to it in 1950 by the U.S. Government at the time of the Korean conflict. Recalling the shortage of base metals in World War II and fearing that the Korean conflict might develop into World War III, the U.S. Government in 1950 adopted a policy to encourage the production of lead and zinc, both domestically and abroad by means of development loans and long-term floor priced purclu.se contracts."

Jan 1, 1960

FOREWORD5 INTRODUCTION 7 ACKNOWLEDGMENTS II BERGBÜCHLEIN TRANSLATION OF THE TEXT 17 HISTORY AND BIBLIOGRAPHY OF THE Berghüchlein 49 NOTES ON TRANSLATION AND ACKNOWLEDGMENTS 63 THREE ILLUSTRATIONS FROM THE EARLIER UNDATED EDITION 65 [ ]

Jan 1, 1949

By R. A. Beall

As part of an ongoing program to develop high-quality materials with improved performance and service lives, and to conserve critical minerals, Bureau of Mines, U.S. Department of the Interior, researchers studied the process of hot-rolling metals, alloys, and composites in vacuum. First, a comprehensive review of the literature is presented, including the advantages and disadvantages of using vacuum. Next, details of hot-rolling titanium, chromium, and molybdenum-iron bimetal are given. Finally, the design of new equipment is described. At this time, it is uncertain whether hot-rolling metals in vacuum will gain commercial acceptance in the future.

Jan 1, 1979