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By Lijun Liu, Yingwei Li, Jianhua Liu, Jinhui Peng

"As essential equipment in the metallurgical industry, current air heat exchangers cannot meet the requirements of high temperature heat transfer. In this paper, an energy efficient air heat exchanger, based on accumulation of the heat generated by microwave absorbing materials, is presented according to heat transfer theory and principles of the microwave field. A tubular shaped heat exchanger was designed and built up through temperature-rising curve, and experimental research of microwave high-temperature air heat exchangers was carried out. It was found from experiments that the tubular shaped heat exchanger fabricated using material B could be used for high temperature heat transfer system, and equilibrium temperatures could reach up to 457—485?.IntroductionHeating or cooling of air by heat exchangers is commonly practiced in a wide range of industries including construction, chemical, machinery, textile, printing, and dyeing [1-3]. Generally such heating or cooling of air is achieved in pipe heat exchangers. There are several drawbacks for such heat exchangers, namely, (i) the limitation of temperature to which the pipes can be heated, (ii) tendency to oxidize at high temperature, and (iii) poor strength of metallic pipes at high temperature. These limitations do not allow pipe heat exchangers to be operated at high temperatures [4-6].Microwave heating of inert solids, which are stable at high temperature, is a possible solution to achieve high temperature of the medium in air heat exchangers. It is well-known that microwave heating is an efficient, clean, safe, easy-to-control heating method. Microwave heating utilizes the dielectric and magnetic properties of a material. When microwaves penetrate and spread into the dielectric material, electrons, ions, etc move in the internal electromagnetic field, while the elasticity of inertia and friction impede these movements. This results in a significant thermal effect, increasing the surface temperature rapidly [7-8]. This paper studies mainly design and experimental research of microwave high-temperature air heat exchanger."

Jan 1, 2011

By Joseph A. DeCarlo

This publication presents statistical data on oven-and beehive-coke plants in the United States. Information on the carbonizing capacity of the coke industry is important because of the close relationship between the coke industry and most of the other basic industries of our country. Coke is an essential-raw material in pig-iron production; also, coal-chemical materials are used to make fertilizers, paints, plastics, synthetic rubber, explosives, detergents, nylon, pharmaceuticals, dyes, and many other useful products necessary to sustain and improve the high standards of living in our country. Oven-coke plants in the United States on December 31, 1958, are tabulated in table 1. This tabular presentation shows the location, classification, number and type of ovens, annual coke capacity, coal chemicals produced, and name and address of parent company for each individual coke plant. About 86 percent of the capacity of slot-type coke ovens in the United States is owned by iron and steel companies. In most of these plants the coke ovens are integrated with the blast furnaces to facilitate transportation of raw materials for steel making. This has resulted in large coke plants, and the average annual coke capacity of "furnace" plants in 1958 was 1.3 million tons. Nonfurnace or "merchant" plants include coke plants associated with chemical operations, gas utilities, as well as coke plants that produce metallurgical, industrial) and residential-heating grades of coke and coal-chemical materials for sale on the open market. These plants ordinarily are not as large as furnace plant~ and annual coke capacity of merchant plants in 1958 averaged only 500 thousand tons. At the end of 1958 there were 55 furnace plants and 22 merchant plants.

Jan 1, 1959

By Robert W. Bartlett

"Economic and other factors, mostly outside of metallurgy, that strongly influence applied research, development and especially successful commercial adoption of new processes for producing primary metals and other commodity materials are reviewed. These factors, which can be both positive and negative in their influence, are often too lightly regarded in the research planning stage. They include continuing imperatives that have long influenced new process development as well as more recent trends. Both are discussed. Nearly all new materials eventually become commodities--products made to standard specifications with no producer control over price. Success requires being a low cost producer on a world wide basis. Composites and other complex material assemblages are unlikely to escape this fate as they mature.INTRODUCTIONThe adoption of new processes, beginning with research and development, for primary metals and other commodity materials is particularly difficult because each new process must supplant an existing process that is already being used commercially. There are many requirements besides technical innovation and cost superiority that must be met by the new process. Consequently, few innovations make it all the way from the research laboratory to commercial success.This paper discusses some of the factors that influence success in developing new processes for primary metals and commodity materials, based on the authors experience as a research metallurgist and industrial research manager. It begins with some of the factors that are always present and constrain successful process research and development, and proceeds to current trends that are expected to continue long enough to influence processes in the year 2000. Many of these trends are contradictory in their effect on new process development, and the future remains uncertain.The prevailing importance of these trends will vary with the material, process concept and other factors intrinsic to each case. Nevertheless, an awareness of these influences can help to avoid some of the R&D pitfalls and dead ends. Such awareness is deemed to be a necessary condition to avoid failure when commercial adoption of a new process is the goal."

Jan 1, 1988

By J. R. Thoenen

Up to 1914 almost all of the world's supply of potash came from Germany and Alsace. With the cessation of shipments from Germany during the World War the importance of a domestic suppler was evident. During the past 15 years the United States has been working toward the establishment of a domestic potash industry which would end foreign dominance in this commodity. The Federal government has taken an active part in this program. As its share in the work, the Bureau of Lines has ascertained the potash resources in certain district's through core drilling and has engaged in a comprehensive program of research on the extraction of potash from its various minerals. Until the passage of the Winter bill (H. R. 496) by Congress in 1928 the Bureau of Mines had not been able to give any consideration to the western ores, wyomingite (leucite) and alunite. With the massage of this bill, however, the ray was opened for the extension of the potash studies to cover these materials.

Jan 1, 1932

By J. R. Thoenen

Up to 1914 almost all of the world's supply of potash came from Germany and Alsace. With the cessation of shipments from Germany during the World War the importance of a domestic supply was evident, During the past 15 years the United States has been working toward the establishment of a domestic potash industry which would end foreign dominance in this commodity. The Federal government has taken an active part in this program. As its share in the work, the Bureau of Mines has ascertained the potash resources in certain districts through core drilling and has engaged in a comprehensive program of research on the extraction of potash from its various minerals. Until the passage of the Winter bill (H. R. 496) by Congress in 1928 the Bureau of Mines had not been able to give any consideration to the western ores, wyomingite (leucite) and alunite. With the Passage of this bill, however, the ray was opened for the extension of the potash studies to cover these materials.

Jan 1, 1932

By Langdon T. Mitchell, Karl Ingmarsson

The title is not referring to jewelry; nor is it about diamond core drilling. This article is instead about an emerging application for diamonds, hard rock percussive drilling with diamond drill bits. Diamond’s outstanding wear resistance has long been taken advantage of in core drilling. However, until now diamond has been less successful in hard rock production drilling in the mining and quarry industry.

Jan 1, 1999

By O. E. Traubert, E. G. Meiter

"The daily sulphur dioxide content of the air at the Pittsburgh Experiment Station of the Bureau of Mines was determined by the bureau at the request of Committee D-14 on Screen Wire Cloth of the American Society for Testing Materials. The purpose of the investigation was to obtain data for use in interpreting screen-corrosion tests, which were conducted simultaneously and jointly by the committee4 and the Bureau of Mines.The plan of this investigation was to vale a single daily determination, except on Sundays and holidays, of the SO2 content of the atmosphere at the exposed test screens, for a period of one year. No attempt was made to determine the variation during the day, except on the morning of October 15, 1927, when the atmosphere was unusually foggy and smoky. Several successive determinations were made on that date to ascertain changes in the SO2 as the morning haze disappeared. The SO2 determinations were begun on August 11, 1927, and continued until August 11, 1923.The Pittsburgh Experiment Station of the Bureau of Mines is in a residential section about 3 miles east of the central or main business district of Pittsburgh. The air samples were taken on the roof above the auditorium, or the center rear of the building. This was also the place where the pieces of screen were placed for corrosion tests. The height was about 40 feet above ground level. Several sources of considerable smoke and SO2 are in the immediate vicinity. On the west side of the building is a double-track railroad. At this point the line runs through a cat below the level of the building. The horizontal distance between the air-sampling position and the railroad tracks is about 400 feet, and the vertical distance about 70 feet. The power plant for the Bureau of Mines building is about 250 feet south of the sampling position. About 1000 feet farther to the south are the engineering building and power plant of Carnegie Institute of Technology, and 1/4 mile to the southwest is the power and heating plant for the Carnegie Library and Museum. About 1 to 2 miles farther south and also southwest"

Jun 1, 1930

By Daniel Saramak, Agnieszka Saramak

A big issue in crushing and grinding operations in raw materials handling is high energy consumption and low breakage effectiveness. According to the Legendre [7], only 10% of energy input is directly consumed on the feed material breakage, while the remaining portion is dissipated in the form of heat and noise [8]. In the industry of limestone powder production, the grinding operations constitute integral part of technological circuits, and the energy consumption in operations of industrial comminution consume as high as 2% of world energy [14]. High-pressure grinding is the technology with proved energy benefits both in ore processing circuits and in limestone grinding. The promising results concerned mostly the achieved energy savings and good results of material breakage were achieved and demonstrated in numerous investigations [1,3,12]. However, it appears that a proper selection of operational parameters of the press devise, determination the feed material characteristics and adjustment of process course san be of a key-significance in improving an effectiveness the HPGR operation. Operational parameters of devices and process course should be verified towards the characteristics of the feed material, which mainly applies to the particle size and shape of the feed material and its moisture, and also mineralization in case of ores [2,4,9]. There are various investigations concerning an impact of the operational pressing force on comminution results which mostly refer to the determination of energy consumption and crushing ratio [5,6,10,13]. Investigations on the moisture content are less common, however their results suggest that, in general, the HPGR feed with higher moisture shows the tendency to higher comminution intensity, while the energy consumption increases together with increasing of feed material moisture. Investigations on olivine sand feed [11] showed that crushing ratio decreases for higher moisture, especially when the material is crushed at higher pressing force. HPGR devices, however, shouldn’t be regarded as a unique and perfect solution for comminution of each type of material. But they indeed may bring technological and economic benefits, comparing to conventional crushing and grinding machines, resulting in more favourable breakage of material particles and lower consumption of energy per unit mass of processed feed material.

Feb 1, 2025

"How Wall Street Darling Molycorp Undermined the U.S. Economy, Degraded our National Security and Distorted the Global Economic Balance and How These Falsehoods Continue to be Promoted Even Today INTRODUCTION & SUMMARY In 2007 the Molycorp Mountain Pass rare earth mine was resurrected from its desert-grave in California by its then-owner Chevron Mining. Responding to elevated rare earth prices Chevron began processing on-site rare earth concentrates left over from past mining operations that were terminated in 1998i. Chinese demand had sparked what was being described as a commodities super-cycleii. Commodity prices were on the move. Wall Street smelled opportunity. In 2008 Goldman Sachs, Pegasus Partners, Resource Capital Funds, Traxys North America LLC and Carint Group LLC acquired the mining assets from Chevron. In an environment of ever-declining ethical standards and regulatory consequences the private capital group and their investment bankers would bring Molycorp to market. Molycorp, with its high powered investment banking team of Morgan Stanley and J.P. Morganiii, easily dominated the contest. Molycorp promoted itself, largely based on its past operating history and proven reserves, as the best company to challenge China’s monopoly control over the production of rare earths: a group of elements critical to most advanced technologies and U.S. defense systemsiv. Most of Wall Street’s hottest investment sectors were dependent on these materials: alternative energy, green technologies, computing, personal communications, advanced electronics and defense systems. By late 2010 there were dozens of prospective rare earth start-up ‘mining companies’ seeking capital. Eventually the number of prospective rare earth mining companies seeking capital exceeded 400, despite the reality that supply requirements of this market were disproportionally small when compared to other natural resource sectorsv. In the world of finance ‘smart money’ picks the winners. Consequently just twovi projects attracted nearly all of the capital (Molycorp and Lynas). Wall street picked Molycorpvii. This paper will primarily focus on Molycorp. By early 2010 the words “Molycorp” and “Rare Earths” electrified many people in the mining industry, most non-Chinese manufacturing technology companies, U.S. & allied defense contractors, technocrats in the U.S. national security community and eager investors across most of the world’s stock markets. It was the hottest story of the yearviii. The financial, technology and defense press coverage verged on euphoric: heaping fuel on fuel until the highly combustible Molycorp-pyre cast a long shadow over all of its rivalsix. When the IPO match was lit the spectacular flaming pyre sucked all of the oxygen out of the rare earth spacex. Molycorp was ranked the most lucrative IPO of 2010, resulting in record breaking profits to its private investors and massive returns for its early stock holding investors."

Jan 1, 2017

Surfaces forces have been measured between gold sphere and gold-coated glass plate in xanthate solutions using an atomic force microscope (AFM). The measurements conducted in potassium amyl xanthate (PAX) and potassium ethyl xanthate (KEX) solutions showed long-range hydrophobic forces, with the force curves showing no evidence for nanonubbles on the surface. The strongest hydrophobic force was measured at contact angle of 94° with a decay length of 23 nm. The hydrophobic force became weaker at higher concentrations and after a long immersion time, which may be attributed to the xanthate species adsorbed on top of the first mono layer. The hydrophobic force became stronger when the residual xanthate solution is displaced by pure water, indicating that hydrophobic force becomes the strongest in pure water.

Jan 1, 2009

By Mason L. Dicks

For many years The Hanna Mining Company has been investigating the flotation of the non-magnetic iron ores located in the Western Mesabi Range of Minnesota.1 During the 1950's a number of anionic iron procedures were evaluated and in the late 1950's and early 1960's the anionic silica floats and the cationic silica floats were tested with improved results.2 The cationic float became more attractive and effective by the use of the improved ether amines. About 1962 a desliming process by selective flocculation was developed by the U.S. Bureau of Hines at Minneapolis', Minnesota.3, 4, 5 This is a very efficient method of desliming and was first tried with the anionic silica float and then the more practical cationic silica float. In the mid 1960's The Hanna Research Laboratory began studies to optimize the selective flocculation process for our ores. This was followed by studies to optimize the cationic silica float after desliming by selective flocculation. This testwork was done on large, 500 to 1000 tonne bulk samples of oxidized taconite which were later successfully piloted at .68t/h (1500 Lbs. /hr.). A program was then begun to test the oxidized portions of numerous taconite drill holes to outline the ore bodies and develop mining plans. This paper will discuss our optimization results of both the selective flocculation and the cationic silica float as applied to our various ores. In addition the pilot plant studies and drill core testwork will be discussed.

Jan 1, 1978

By G. B. Harris, C. W. White

Cyanide has been used for the recovery of gold since the mid 1800s, but several jurisdictions have already banned its use, and environmental pressures are increasing to finding an alternative. Gold also forms chloride complexes similar to those of cyanide, but the use of chloride has never achieved widespread acceptance. This paper describes a chloride-based flowsheet, wherein the key unit process is the recovery and recycle of chloride ion. It is shown that the chloride-based flowsheet is competitive economically with the conventional cyanide-based flowsheets, and that it has a number of other advantages, particularly environmentally.

Jan 1, 2011

By Bo R. Arvidson

High-energy product permanent-magnet materials of rare-earth cobalt alloys are being used in applications where space or weight are at a premium cost. New applications like friction-free bearings are also made possible. However, such magnet materials have not been commercially used in magnetic separators until now due to the high cost for the overall magnetic flux generation relative to commonly used ceramic magnets or AlNiCo magnets. The design of the new high-intensity permanent- magnet roll separator (PERMROLL) takes advantage of the unique properties of rare-earth cobalt magnets rather than just substituting for conventional magnet materials now in use for magnetic separators. Hence, the new generation of high-intensity magnetic-roll separators has some unusual characteristics that make known magnetic separation applications more economically attractive, and even expands the magnetic separation technology area to include applications for which no other feasible methods are presently known.

Jan 1, 1983

By I T. Ross

In the last 50 years there have been tremendous improvements in equipment used in development on underground mines. Compressed air powered jacklegs have been replaced by high powered electro-hydraulic drifters on sophisticated drill jumbos and load haul dump units have taken over from small shovels and rail cars.Despite the increase in power applied in key parts of the development cycle, average advance rates have fallen and costs have increased. The factor that is most often regarded as the main contributor to slowing advance rates is increased support requirements. Whilst there is no denying that the drive to improve safety has resulted in the requirement for more bolting and the installation of a skin support (mesh or shotcrete), this is not the only factor.Within the industry as a whole, many of the basic principles of development appear to have been lost over time. This paper looks at a historical case study and discusses some of the features of old development cycles that are no longer in use. This highlights some of the basics that appear to have been forgotten. These may be indicators to what may provide improvements in the conventional drill and blast development cycle.CITATION:Ross, I T, 2014. Development – back to basics, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 67–74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Paul Hatmaker

A primary, function of the Bureau of Mines is to encourage elimination of waste and the most profitable use of mineral raw materials. In line with this objective the Bureau has frequently stressed the importance of waste utilization at stone quarries. From time to tine studies both technical and economic in character have been made of problems pertaining to the most efficient use of natural, stone, particularly that which may be classed as a by-product of the higher grades of dimension stone. Every quarry producing ornamental or building stone yields large quantities of material that for one reason or another is unsuited for high-grade products, even though a great deal of work has been expended upon it more or less unavoidably. It is obviously good judgment to sell this odd-sized or off-grade stone at whatever price can be obtained rather than to spend more money to place it on the waste dump. In many cases, however, a really profitable side line has been developed.

Jan 1, 1933

By A. N. Pritchard

The development of vibrating screens over the last century has seen many variations to suit the exacting requirements of industry. Indeed, as each year passes, industry has presented the challenge to screen manufacturers of supplying larger machines than those used in the past and the question is often posed - what is the maximum limit? Not only must size or screen area be considered but excellence of performance in terms of screening efficiency must be maintained or maximized.

Jan 1, 1983

By George J. Conroy

Results of a long-term program of electrical parameter measurement in under-ground coal mine working sections, performed by The Pennsylvania State University under U. S. Bureau of Mines sponsorship, are utilized as the basis for an analysis of the electrical energy requirements during operation. A model section is hypothesized, developed from the average or most representative characteristics as determined from tabulations of the measurements. Performance factors of the model section's machine complement are then analyzed, particularly with regard to the energy required per ton of raw coal cut and delivered from the section. Results are given in kilowatt-hours per ton.

Jan 1, 1977

By M. F. Ameur, M. Habak, H. Aouici, M. Kenane

Present study interest by aluminium alloy (Al 7175-T5173) drilled without cooling fluid. The influence of the machining parameters (spindle speed and feed rate) on the holes quality was analyzed. Drilling tools are made of carbide (WC); high speed steel (HSS) and TiN coated carbide (WC-Ti).The Experiment design was reinforced by the application of statistical analysis of variance (ANOVA).The results show that the thrust force is influenced principally by the spindle speed and feed rate. Though, both feed rate and tool materials have statistical significance on the surface roughness. In addition, the objective of correlations between spindle speed and feed rate with the evolution of the machining parameters was established. These correlations were obtained by quadratic regression using the response surface methodology. Finally, useful to select optimum values of drilling parameters, that would minimize thrust force, torque, cutting temperature and surface roughness.

Jan 1, 2015

By M. N. Plis

This report describes the initial results of long-range research on bit life conducted by the Bureau of Mines. Three commercial bit designs -a round-nose radial, 60° conical, and 90° conical with tungsten carbide (WC) inserts -and five experimental bits were tested. Four of the experimental bits were radial designs using polycrystalline diamond compact (PDC) inserts. The fifth was a 90° conical with an oversize WC insert. Bits were worn on a high-silica sandstone typical of coal mine roofs. The bits were mounted on a 34-in-diam drum section that provided a bit speed of 565 ft/min. Cutting forces were measured on a modified vertical slotter using a three-axis force dynamometer and recorded on an FM magnetic tape recorder. Changes in cutting forces, bit weight, and airborne dust due to gradual abrasive wear and catastrophic insert failure are presented. Tabulated and graphed data, photographs of the progression of bit wear, and selected qualitative visual and auditory observations of the bits taken throughout the experiment are found in the appendixes. The results show that bit life ranged from approximately 16,000 ft for the WC round-nose radial bit to over 125,000 ft for a PDC round-nose radial. Performance, in terms of bit life, cutting forces, wear rate, frictional sparking, machine vibration, and noise was in general best with the PDC bits, followed by the rotating WC bits, with the nonrotating WC bits (round-nose radial and locked 60° conical) being the worst. The results show variations in the included tip angles of new conical bits have an insignificant influence on bit performance when the effects are averaged over the life of the bit. In addition, new bits were generally found to entrain more primary respirable dust for a given cutting distance than worn-out bits. It is hypothesized that this is due to the difference in frictional behavior between new and worn bits. The results from these tests are being used in the Bureau's cutting system model (CSM).

Jan 1, 1988

By M. D. Flavel

Research programs conducted by Allis-Chalmers Corporation are showing that the most efficient energy use in crushers is achieved when the forces applied to particles undergoing breakage are increased. Laboratory bench scale tests have been developed to confirm this phenomena, which was first observed in the field using HYDROCOME crushers with automatic setting controls. A new testing machine is described and methods of maximizing such benefits are postulated. FOREWORD Allis-Chalmers Corporation was founded in Milwaukee, Wisconsin, in 1847 as the E. P. Allis Company, which had an initial interest in manufacturing components in the grinding of flour. As such, its roots were started in reducing material size, which is covered by the generic term, comminution.

Jan 1, 1981