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By Clarence E. Sims

DURING the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging. The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary abnormal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. 1, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity.

Jan 1, 1947

By Lon A. Williams

This report, authorized under Contract Number H0220065, Amendment Number Six, documents the results of an investigation of lighting system modifications and designs for working place illumination in high and low coal entries of underground coal mines. The portable and machine mounted system designs, both modified and prototype, represent a continuation of work performed under Contract Number H0111403, Amendment Number One. See the Final Technical Report dated May 26, 1972 for detailed information concerning this prior Contract. All modified and prototype systems met the performance requirements of Bureau of Mines Specification 2G, as proved by test. In addition, the systems met the requirement for illumination, as specified in the Contract and in the proposed standards which were generated in response to Public Law 91-173.

Jan 1, 1976

By J. B. Wagstaff, R. A. Buchanan, J. F. Elliott

High speed photography through blast-furnace tuyeres showed coke particles moving rapidly. Model studies showed a raceway was formed and gave quantitative results which were correlated with actual blast furnaces. Another study showed the similarity between hanging and the flooding of a packed column. This was explored by models. THE combustion zone before the tuyere in an iron blast furnace is a vital region because here are generated: 1—most of the gases on which the furnace depends to carry out its basic operation of reducing iron ore to the metallic state, and 2—the major fraction of the heat required in the nearby regions of the furnace for the various reduction reactions, the fusion of the slag, and the melting of the iron. Since the greater part of the coke is consumed in this region, the descent of the burden must be greatly affected by the characteristics of the tuyere zone. This region then would seem to be a profitable field for study. Fortunately, a view into this important zone is available to the operator through the tuyere peep sight. Here he sees relatively dark pieces of coke "dancing" in the blast. What he sees is of considerable help in interpreting the behavior of the furnace at a given time but the very rapidly moving particles and the intense radiation obscures what is happening very deep in the zone. This investigation was initiated in the hope that a better understanding of the combustion region could be obtained by using a high speed camera with a maximum speed of 3000 frames per sec. It seemed the best practical method of "slowing down" this characteristically violent action within the highly luminous field. Model studies and tuyere probing also have been used to aid in explaining the observed phenomena. Above the combustion zone, but below the fusion zone, there is probably a region in which the coke is comparatively stationary. Here are zones in which the gases must flow up through the granular bed counter to descending liquid slag and metal. There is no easy way to observe this zone in a blast furnace, but model studies have been of some help in explaining the nature of the zone and the laws governing the flow of the fluids involved. The whole problem is difficult and involved and any approach to a complete solution may require long investigation. This preliminary report has been written, therefore, because it is believed that appreciable progress has already been made that would be of interest to others. Tuyere Studies, Chemistry and Kinetics It is well known from the early work of Kinney and coworkers1,2 that combustion of carbon before the tuyeres appears to occur in two zones: Zone A: C + O, = CO2; AH77°F. = — 14,108 Btu per lb of carbon [I] Zone B: CO2 + C = 2CO; H77°F = + 6,183 Btu per lb of carbon [2] Zone A (Fig. 1) is close to the tip of the tuyere and zone B is somewhat farther back; there being a transition region in which both reactions occur. It is interesting to estimate the rate at which coke is burned before a tuyere with a wind rate of 90,000 cfm in a modern furnace having 18 tuyeres. Approximately 0.55 lb of carbon is consumed by eq 1 per tuyere per sec. A like amount disappears by eq 2 for a total consumption of 1.11 Ib per sec per tuyere. Assuming the coke is 85 pct C and has a bulk density of 30 lb per cu ft, this figure can be converted to a total of 1.30 lb of coke with a bulk volume of 0.043 cu ft disappearing per sec per tuyere. At the temperatures prevailing in the combustion zone (according to Kozlovich,³ he maximum is about 3400°F), the rate at which carbon is con-

Jan 1, 1953

By L. C. IlsLey

"There are two general classes of accidents that prevail in and about mines, namely - (1) those that through the nature of mining work can only be lessened, and (2) those that by proper precaution can be eliminated altogether. Explosive accidents that ordinarily take place while explosives are being transported in and about mines belong to the second class, that is, by proper care all such accidents can in general be avoided.The following table gives a brief summary of several accidents and disasters that have occurred in the United States and indicates the need of universal preventive measures as a basic part of all State regulations.ACCIDENTS AND DISASTERS OCCURRING WHILE TRANSPORTING EXPLOSIVES.***"

Sep 1, 1923

By L. Sturkey

Quantitative X-ray diffraction studies of the precipitation of thorium in a Mg + 3.3 Th + 0.51 Zr alloy (HK31A) in both the as-cast and cold-worked states show that the precipitation may be described by f = 1 - e(t/T)1/2 over most of the aging period. The effects of cold work and temperature changes are determined. The precipitation of tile equilibrium Mg-Th compotund is Preceded by the formation of a transition phase of higher thorium content, with the cowposition Mg2Th and with a Laves-phase structure. Thorium-containing alloys of magnesium have assumed considerable commercial importance, especially for applications requiring exposures to temperatures greater than 500°F for appreciable lengths of time. The principal commercial wrought alloys in this system are HK31A, containing nominally 3 pet by weight thorium and about 0.7 pet by weight zirconium: and HM21A. containing 2 pet by weight thorium and 1 pet by weight manganese. These two alloys retain a high level of properties even after exposures of 100 hr at 600°F, while the more common alloys containing aluminum and zinc are badly overaged by these conditions. Therefore, in order to obtain some insight into the mechanism by which thorium produces high temperature stability in these wrought alloys, it seems desirable to investi- gate the effect of temperature and mechanical working on the precipitation processes involving thorium. Since the scattering power of a thorium atom for CuKa X-ray radiation is about ten times that for a magnesium atom, the magnesium alloys containing about 3 pet by weight thorium are ideal for quantitative measurements by X-ray diffraction of the amount of Mg-Th compound present at any time. Such quantitative measurements should be of theoretical importance in the study of the effects of time, temperature, and deformation on precipitation and precipitation hardening. Of the two commercial alloys, HM21A and HK31A, the latter is certainly the most suitable for study: In the Mg-Th-Zr2 system, only Mg-Th compounds need be considered, since no ternary compounds or binary Th-Zr3 and Mg-Zr4 compounds exist. The Zr is added to this alloy as a grain refining agent and probably plays a secondary role in precipitation. On the other hand. thorium and manganese form many

Jan 1, 1961

By O. J. Restrepo-Baena, L. Rojas-Mendoza

Gold losses must be controlled during extracting processes, especially during cyanidation. Otherwise recovery decreases and therefore the profitability of projects too. One of the phenomena that generate such losses is known as preg-robbing which occurs when some mineral constituent adsorbs aurocyanide complex from a cyanide solution. There are some laboratory methods to identify potential preg-robbing in gold ores, highlighting the PRP method, the BGMI test, and cyanidation tests by conventional agitation without activated carbon (BRP) and with activated carbon (CIL). For this study we performed an initial characterization of a sample from Antioquia - Colombia and then we carried out the methods described above in order to identify the presence of carbonaceous matter. We obtained a percentage of preg-robbing of 78.7% by applying the BGMI test; the preg-robbing potential by the PRP method was 97.9% with an extraction of 0.77% and an inferred recovery of 36.6% if preg-robbing did not occur. Finally we obtained under the BRT test a recovery of 0%, while for CIL test an extraction of 33.6% what confirmed the presence of preg-robbers agents in the gold ore. We conducted all tests in the Institute of Minerals - CIMEX at Universidad Nacional de Colombia - Medellin.

Jan 1, 2014

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of Clarion County, Pa. Of the 15 samples collected, 1 was of metallurgical quality as received, 4 could be sufficiently upgraded to provide acceptable products, and the remaining 10 samples could not be upgraded to metallurgical quality because their sulfur contents could not be lowered to meet the standard. For steam or power generation, 1 sample was of low sulfur content as received, 1 sample could be upgraded to low sulfur content, and 10 samples could be upgraded to medium sulfur content. The original sulfur content of the remaining three samples can be appreciably reduced by removal of the sink 1.58 specific gravity material; however, these coals would be classified as medium sulfur coals both before and after removal of the sink material.

Jan 1, 1968

By James P. Dr. Kimball

SULPHUR is always present in mineral coal of every variety. In the oxidized state it may exist as sulphuric acid in combination with a base. In the unoxidized state it exists in combination with iron as bisulphide of iron. It is also supposed by some chemists to exist in unknown combinations with the organic elements of the coal. This supposition requires the demonstration as a fact that certain coals yield more sulphur than what may exist in a free state, or what belongs to recognized combinations, not only with the accompanying iron but with other inorganic bases abundantly occurring in coals, but which unfortunately are very rarely estimated. This practically as well as theoretically important question it is at present impossible to decide, simply for want of available thorough ultimate coal analyses including the ash. Such analyses, at the best imperfect, are laborious and intricate, and therefore seldom made, the much simpler proximate analyses, so-called, being resorted to by most chemists for technical purposes, and commonly substituted for more scientific work even in the laboratories of government surveys. And it is unfortunate enough that few ultimate analyses are extended to the composition of the ash, much less to its relation to the original constitution of the coal. Sulphur chiefly occurs in most coals in the form of yellow pyrites (pyrite) and white pyrites (marcasite), both minerals, characterized by differences in crystalline form and in physical properties as well as in color, but having the same chemical composition (FeS2). No coal is entirely free from one or both of these dimorphous forms of bisulphide of iron. It may be disseminated through the mass so as to be invisible, in plates or scales between the laminæ of the coal, or in conspicuous segregations or nodules, sometimes of considerable dimensions. Coals greatly differ as to the proportion of sulphur which they contain. They also differ as to the relative proportion in which its several forms of combination occur. Such qualitative and quantitative disparities are scarcely, if at all, more marked in separate coal seams of a uniform type than in different parts of one and the same coal seam, whether it be considered locally as constituted of several

Jan 1, 1880

By M. Leroux, S. R. Rao, J. Kim, J. A. Finch

"Continuous in-plant testing of collectorless Cu/Pb bulk flotation on Lyon Lake ore at Matlabi Mines Ltd. Was conducted using a portable circuit based on 5 L mini flotation cells. It is concluded that collectorless Cu/Pb flotation is a reliable phenomenon for this ore over the usual range of plant operating conditions.IntroductionFlotation of some sulphide minerals without the use of conventional collectors (e.g. xanthates) is now widely recognized. The requirement appears to be some degree of oxidation, although the nature of the surface product formed is still uncertain (Luttrell and Yoon, 1984; Buckley and Walker, 1988). The phenomenon has been termed ""collectorless"" or ""self-induced"" flotation. One of the minerals most responsive to coUectorless flotation is chalcopyrite; in contrast pyrite and sphalerite show little response and galena usually shows intermediate response (Hayes et al., 1987; Shannon and Trahar, 1986).Most of the work on collector1ess l1otation has involved single mineral or batch flotation on ore samples. There are only occasional references to collector1ess l1otation under plant conditions (Sandstrom and Jonsson, 1988; Vargas, 1990; Boyce et al., 1970). Creating and maintaining the appropriate oxidation conditions and differences in water quality are among the reasons why the phenomenon may not transfer readily to the plant (Grano et al., 1990). Periodically from the spring of 1989, Mattabi Mines Ltd. ran full-scale tests of collector1ess bulk CulPb flotation while treating Lyon Lake ore*: the observations confirmed the laboratory finding that chalcopyrite and galena floated without collector (Leroux et al., 1989).To explore this finding continuous in-plant testing using mini flotation cells was conducted which is the subject of this paper. The main objective was to determine if collectorless flotation was a reliable phenomenon over the expected range of redox conditions in the feed pulp to bulk CulPb roughing. As background, the previous work (Leroux et al., 1989; Martin, 1988) is briefly reviewed."

Jan 1, 1994

By F. A. Champion

The work described in this paper was carried out in the Research Laboratories of the British Aluminium Company Ltd., under the general direction of A. G. C. Gwyer, Scientific Manager of the Company. In considering the effect of stress?corrosion conditions on metals, or the failure of metal through stress corrosion, it is evidently advisable to adopt a clear definition of the meaning of those phrases. There appears to be general agreement that stress-corrosion conditions may be defined as the continuous application of static stress to a metal while it is exposed to corrosive conditions, but recognition of the occurrence of true stress-corrosion in a metal is often a difficult matter giving rise to some confusion. For the purpose of this paper stress corrosion in a metal is defined as the acceleration of corrosion by the application of static stress. On this view it is necessary to test a metal not merely under stress-corrosion conditions, but also under the same corrosion conditions without the simultaneous application of stress, if the liability of the metal to stress corrosion is to be assessed. Failure of a metal under stress-corrosion conditions is sometimes quoted as evidence of stress corrosion (for example, by Althof(1)2), but this evidence is totally inadequate if the above definition is

Jan 1, 1945

By N. Bartie

Realising the circular economy (CE) is faced with some significant challenges. Process metallurgy and its infrastructure play key roles at the heart of making the CE work. Therefore, the enabling role of process metallurgy within the CE will be central to the discussion in this paper, touching among others on product and system design as well as the key metallurgical and other process fundamentals that need to be investigated and understood to make the CE a reality. The central role of materials and its processing will be discussed in an integrated circular cities perspective. A key focus will be a discussion on designing a resilient “Smart Materials Grid” using and innovating metallurgical process engineering tools, which will manage the flows through Sustainable Circular Cities. The discussion will be using copper as leitmotiv of the discussion i.e. from copper ore, to metal, to complex products, recycling, product design and simulation and its impact. INTRODUCTION The transformation of our economies from linear to circular models in which waste materials become resources is the focus of the Circular Economy (CE) paradigm. Its important intentions: to take control of the damage we have been doing to the planet to ensure its livability and the welfare of future generations. This can only be achieved through careful utilisation of human, natural and economic resources. The concept is derived from several others (Beaulieu et al., 2015), of which Cradle-to-Cradle, Extended Producer Responsibility (EPR), Industrial Ecology, and Life Cycle Thinking are just a few. Other relevant concepts include resource efficiency (RE), design-for-recycling (DfR), and various others discussed by Blomsma and Brennan (2017) and Homrich et al. (2018), as well as various R-hierarchies e.g. Reduce, Reuse, Recycle (3R). However, does society comprehend these concepts, the actors and actions that influence them and how they interact? Do we know the limits of CE? Does society understand the key role of Copper and other metals to rendering the CE operable? True life cycle and systems thinking, focussed on simulation-based, process and metallurgical design are required to answer these questions. Lieder and Rashid (2016) identify nine widely-varying fields that study the concept ranging from sustainability sciences and engineering to economics, business, law, and social sciences. Overlap between questions addressed highlights the need for interdisciplinary collaboration (Nanz et al., 2017) in the assessment of the current status, and further steps needed to transform to CE. This doesn’t apply just in academia, but also in industry where concrete implementation of CE needs to occur at multiple levels, thus necessitating cooperation between government, civil society and other stakeholders (Beaulieu et al., 2015).

Jan 1, 2019

By Robert Glass Cleland

[Incorporated under the laws of the State of New York OFFICE, 41) WALL STREET, NEW YORK 5, N. Y. Authorized4,000,000 shares $150,000,000.00 Outstanding-5,071,260 shares 126,781,500.00]

Jan 1, 1952

By S. D. Maksirnovic, Fred N. Kissell

The use of vertical surface degasification boreholes with bleeder systems and the use of a timbered bleeder system to degasify gob areas were studied by (the Bureau of Mines. This report describes three gob degasification studies ,conducted in the Pittsburgh coalbed. One study was conducted to determine the number of panels degasified with one large borehole . The study showed that the borehole provided degasification for three panels. Another study was conducted during the retreat of a 35-acre panel with a single-entry and a two-entry bleeder system and a large surface borehole. A major portion of methane emitted from the panel was carried away by the bore- hole, leaving the bleeder entries relatively free of methane. The last study was made to determine the effectiveness of a timbered bleeder system. The bleeder entries successfully degasified the gob area when enough entries were available and adequate pressure was available to force the air through roof falls.

Jan 1, 1980

By Roy H. Grau

The trend in underground room-and-pillar cod mining is to employ remote-control continuous mining machines to take extended cuts of 40 A or more. Roof fall safety hazards to the mine worker associated with 4ed cutting are not completely de6ned but are known to include removal of the miner operator from the protective canopy, non-compliance with approved cutting depth and CM operator positioning. This report summarizes ground control research performed by the National Institute for Occupational Safety and Health (?-JIOSH) researchers at the Pittsburgh Research Laboratory concerning extended cuts. A combination of statistical analysis and underground investigations have been conducted. Statistical analysis of extended cut use, along with roof fall accidents and fatalities data delineate the extent of the problem in U.S. coal mines. Additionally, an underground study is described where the long-term roof stability of extended cut areas are compared to standard cuts.

Jan 1, 1997

By E. O. Wagner, V. F. Parry, J. B. Goodman

The low-rank coals containing 10 to 50 pct natural bed moisture represent over half of the tonnage reserve of the available solid fuels of the United States, but only about 2 pct of United States coal production is derived from these fuels. Increased utilization of these large reserves will result if the bed moisture can be removed at the mine in high-speed low-cost processes. This paper presents a theoretical and experimental study of the factors affecting high-speed drying of coal dusts. The time required to heat particles of coal is proportional to the square of their diameter, and it is calculated that the probable time in minutes is equal to 6D2. In other words, a 1/16 in. coal particle should be heated to drying temperature in 1.5 to 2.0 sec. Likewise, 1/8 in. particles should be heated in about 6 sec. The net heat required to dry subbituminous coal and lignite varies from 240 to 375 Btu per pound, depending upon the moisture removed, and this heat can be obtained from 42 to 61 cu ft of hot gases at 600°F. The necessary heat also can be obtained from 7.5 to 11 cu ft of gas at 2000°F. A description of the design and operation of a pilot plant for flash drying coal dusts is presented. This plant dries 1/16 in. by 0 coal dust in suspension in 1.5 to 2 sec with 600°F gas at a rate of 1300 lb per hour per square foot of column area and operates continuously at an efficiency of about 85 pct. The design and operation of another pilot plant for drying 1/8 in. by 0 coal dusts Is also described. This unit dries coal in the fluidized state using the sensible heat of gases introduced at 2000°F and processes coal at a rate of about 1500 Ib per hour per square foot of grate area at 85 to 90 pct efficiency. Over 90 pct of the bed moisture of low-rank coal dusts can be removed by the methods described. The heating value of lignite can be increased 45 pet and that if subbituminous coal 25 pct in a few seconds. The physical and chemical properties of coal dusts before and after drying are presented in the report, and it is shown that the bulk density of the dried coal is equal to that of the raw coal. This phenomenon makes it possible to ship 25 to 45 pct more heat in a railroad car with consequent savings in freight costs. Introduction For several years the Subbituminous Coal and Lignite Section of the Coal Branch of the Bureau of Mines at Golden, Colo., has been concerned with upgrading low-rank coals by removal of natural bed moisture. These fuels contain 10 to 50 pct total moisture, which reduces their industrial value considerably. In 1938, investigations were initiated in cooperation with the University of North Dakota to study drying of lignite by the Fleissner process with heat derived from high-pressure saturated steam. Two pilot plants were built, and two reports were published giving the results of this work.l,2 It was demonstrated that lump lignite and subbituminous coal

Jan 1, 1950

By Jean Igor Margem, Rômulo Loiola, Sergio N. Monteiro, Foluke S. de Assis, Frederico M. Margem

"Fibers extracted from the ramie plant have been traditionally used in textile and are now being considered as polymeric composite reinforcement owing to their superior strength. Recently the mechanical behavior of ramie fiber reinforced polyester composites was investigated but no significant improvement was found. Therefore, the objective of this work was to carry out a similar investigation by changing the type of polymeric matrix. Specimens with up to 30% in volume of ramie fibers incorporated into epoxy were bend-tested until fracture. The results showed a moderate improvement with a tendency of decreasing stress for higher amounts of ramie fibers due to the weak interface developed with the epoxy matrix.IntroductionThe engineering application of natural fibers extracted from cellulose-containing vegetables, also recognized as lignocellulosic fibers, is presently considered an environmentally correct alternative to replace more expensive, non recyclable and energy-intensive synthetic fibers [1-3]. In fact, composites reinforced with traditional fibers such as coconut, sisal, jute, hemp, etc ... are already on the market in substitution for common glass fiber automobile components [4-6]. Even less known fibers like curaua from the Amazon region are being industrially used [7]. Economical and environmental reasons sustain a promising future trend for natural fiber composites. In comparison with the less expensive glass fiber among energy-intensive synthetics, lignocellulosic fibers are approximately five times cheaper. For the current situation of our planet, natural fibers are regarded as ""green"" environmentally friendly materials. They are abundant, renewable, biodegradable, and recyclable, above all, neutral with respect to carbon dioxide emission, associated with global warming.Several relatively unknown lignocellulosic fibers such as piassava [8], sponge gourd [9], sugar cane bagasse [10], buriti [11] and ramie [12], with simple and limited applications, or just byproducts, are now being investigated for their potential as composite reinforcement. This could widen the offer of new lignocellulosic fibers for composite reinforcement. The banana fiber, in particular, has a tensile strength around 700 MPa [13], which is comparable to the strongest lignocellulosic fibers used as composite reinforcement.In addition to polyester, the epoxy is another relatively strong polymer used as composite matrix. Therefore, the objective of the present work was to assess the mechanical properties obtained by flexural test, for epoxy composites reinforced with different amounts of banana fibers."

Jan 1, 2013

By Seneviratne SP

The excessive displacement of the seam floor in headings (i.e. roadways) called 'floor-heave' is often experienced in the underground mines of the Southern Coalfield of New South Wales. Apart from interfering with the mining operations, the phenomenon could be detrimental to the stability of the pillars left for support leading to an unpredictable increase in the subsidence of the overlying strata. The latter could pose a serious problem, particularly in the design of partial extraction layouts of mining for areas where subsidence is to be controlled. The susceptibility of the floor of different rock materials and thicknesses in a given `panel and pillar' partial extraction geometry was examined by two- dimensional Finite Element Modelling of the displacements, stresses and failure zones around the excavations. The modelling, assuming elastic behaviour of the materials, indicated that the maximum vertical displacements of the floor increased substantially as the Young's Modulus of the material decreased to less than 7GPa and the thickness of the layer increased. The results also discount the possibility of a properly designed panel and pillar geometry in the Southern Coalfield of New South Wales being unable to adequately control surface subsidence through the pillar, or its core independently of the yielded ribs, penetrating the floor.

Jan 1, 1992

By H. Y. Yancey, B. M. Bird

One of the problems studied by the U. S. Bureau of Mines in cooperation with the University of Washington has been the re-treatment of table middlings. Hydraulic classification has given the best results. Instead of using the classifier to prepare the feed to the tables, as has been the practice for many years in ore dressing, it is used to separate part of a middling product that cannot be re-treated successfully on the table. Middlings are desirable in a table plant because the separation according to specific gravity is incomplete; that is, in the products of the table there is always an overlapping of free particles of coal and refuse that can be distinguished with heavy liquids such as are used in the float-and-sink test. The causes of this overlapping may be divided into two groups, those outside the table separation itself and those inherent in the table separation. The first of these groups includes, among other causes, the following: (1) poor adjustments of the table, (2) overloading or underloading the table, (3) irregularities in the quantity and quality of the feed, (4) irregularities in the power and water supply, and (5) a vertical dancing motion of the table deck due to weak foundations. These causes of overlapping are largely unnecessary in a properly designed and constructed plant; but whenever they are present they materially affect the character of the middling product, and hence the problem of re-treatment. The other group includes three additional causes: (6) small differences in specific gravity between coal and impurities, (7) a size-specific-gravity relationship of the coal and refuse particles in the table feed such that the sizing action of the table opposes the separation according to the specific gravity, and (8) shapes of particles that prevent a separation. The sixth, small differences in specific gravity, may be a very important reason for an incomplete separation. The change in specific gravity from coal to shale is always gradual and the designation of one part as coal and another part as refuse is arbitrary. If some specific gravity, such as 1.45, is chosen as the dividing point between washed coal and refuse,

Jan 1, 1930

By G J. Harbort, Z Pokra

It has been observed in several Jameson cell installations where the source for flotation feed is deslime screens, that the recovery of coal particles greater than 0.5 m is not as great as that of finer material. Consequently, a research project was undertaken at a CHPP in the Bowen Basin, Queensland, to assess the possibility of increasing the recovery of coarser particles (+0.5 mm) within the downcomer of the Jameson Cell. The effect of decreasing turbulence and agitation in a commercial-scale downcomer was investigated to assess the effect on the recovery of both coarse and fine coal particles. This paper details the findings of the testwork, summarising the results relating to differences in the operating parameters within the downcomer.

Jan 1, 2005

By F. Habashi

"The rare earths industry started in Austria in 1887 by Carl Auer von Welsbach (1858-1929) Professor of Chemistry at the University of Vienna. The process was based on monazite sand transported from Brazil as shipping ballast free of charge. This made possible producing thorium, cerium, and other rare earths at a low cost, thus permitting the growth of the industry. However, once the Brazilian authorities realized the strategic importance of the sand, shipping was stopped. Brazil then started its own processing of the sand in 1949. The background for Auer’s work, the role of Robert Bunsen in Heidelberg, and the invention of the spectroscope will be presented. INTRODUCTIONHeidelberg on the Neckar (Figure 1) was the meeting place for chemistry students from all over Europe in the nineteenth century. Her university founded in 1386 had already a famous professor of chemistry and medecine in the Faculty of Medicine by the name Leopold Gmelin whose three - volume Handbuch der theoretischen Chemie appeared in 1817-1819, that became later a multi-volume monumental work. As successor to Gmelin came Robert Bunsen (Figure 2) in 1852 who made this university town the Mecca of chemistry students. One of his students, the English Henry Roscoe (1833-1915) who became later a distinguished professor in Manchester, described him as follows: ""As an investigator he was great, as a teacher he was greater, as a man and a friend he was greatest""."

Jan 1, 2012