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By Luiz C. Correa da Silva, Robert F. Mehl

An experimental study of the movement of markers in the systems Cu/a-brass, Cu/Sna-solid solution, Cu/Ala-solid solution, Cu/Ni, Cu/Au, Ag/Au, employing many types of markers and a variety of temperatures. Marker movement is confirmed and undoubtedly associated with the manner in which atoms move during diffusion. EVERAL years ago Smigelskas and Kirkendall' •S reported measurements on the interdiffusion of copper and a-brass and on the movement of inert markers placed at the original join. These markers were observed to move toward the a-brass side of the join, and from this it was inferred that zinc diffuses in a-brass more rapidly than copper. Similar results were reported a little earlier for the diffusion of solvents into high polymer solids.' This has attracted much attention, particularly from those interested in the mechanism and the theory of diffusion: Seitz3 has employed it in supporting the vacancy theory of diffusion; from the data Darken4 has calculated separate diffusion coefficients for copper and zinc, developing a "phenomenological" theory of diffusion; and Bardeen5 has employed it in constructing a general theory, including therein the work of Seitz and Darken, as has Le Claire. These matters have recently been reconsidered in a sympo~ium.7 Some reason has existed for questioning the work of Smigelskas and Kirkendall.' Their technique consisted in electroplating copper on a-brass, upon the surface of which Mo-wires had been secured, and then diffusing, measuring the extent of diffusion along the normal to the join, and measuring the marker displacement in the same direction by a comparator determination of the distance between Mo-wires on opposite sides of the electroplated brass sample. It has been suspected that the copper plate might have been porous, and that the original interface might have been an imperfect join, both contributing to the transfer of the volatile zinc by vapor transfer;' it has also been questioned whether the marker movement might not in a measure be a property of the marker itself; etc. These legitimate questions require experimental answers; the present paper offers such answers. Moreover, Smigelskas and Kirkendall studied the effect only in the Cu-Zn system and at one temperature; the attention which the work of Smigelskas and Kirkendall has commanded recommends similar

Jan 1, 1952

Falls of ground (FOG) still account for around 35 per cent of all fatalities in underground southern African mines. To help reduce FOG, appropriate support technology needs to be implemented, and a mindset and cultural change are required to make a significant change. Discipline plays a major role and needs attention, whilst appropriate first-world support technology is available to assist in the reduction of injuries and the improvement of productivity. Section 54 mine stoppages due to FOG are costly. Appropriate support should reduce these unnecessary stoppages. Coal mining has adapted leading support technologies over the years. Platinum and chrome mines have shown significant moves towards adopting leading and appropriate support technologies, seeing noteworthy changes in injury statistics for the better. In typical conventional underground mining operations, the use of temporary support components offers some protection to workers while the permanent and generally more elaborate support systems are installed or constructed. Nonetheless, FOG continue and still result in injuries to people. The author wishes to explore the options and practicality of making use of new-generation support products and technology to provide not only safer support operations, but to also enhance productivity at the working faces. This paper will examine the use of appropriate support technology as a means to making the working stope or development end a safer and more productive workplace.

Jan 1, 2012

By N Winkelmann

Underground coal heating is a significant hazard in some coal mines. The broad principles of how underground coal heatings occur is reasonably known, however the technique for locating the heatings in often inaccessible goaf has been proved to be difficult. Since 2002, CSIRO, with the support of the Australian Coal Association Research Program (ACARP) has been undertaking investigations to apply and develop innovative surface-based radon technique for locating the underground heatings in Australia. This paper presents the progress of the investigation.

Jan 1, 2005

By James L. Parks, David M. Kjos

"Designs, installation procedures and performance characteristics of martensitic cast steel concaves are reviewed. Longer wear life, fewer pieces to install and eliminating the need to scarf joints are the principal benefits of using martensitic steel to replace austenitic12% Mn (Hadfield's) steel, the traditional concave material for large gyratory crushers. Installation procedures that reduce the risk of breakage are described. Operating practices that affect concave performance are also discussed.IntroductionThe crushing machine considered to be the forerunner of the modem gyratory crusher was patented in 1878 by Charles M. Brown of the Gates Iron Works(1). The earliest gyratory crushers with receiving openings of 6 to 12 inches were fed by hand, and the crushing capacity of a mine was increased simply by installing more small crushers. The introduction of the steam shovel to open pit mining around the tum of the century provided an incentive for much larger primary crushers, and gyratory crushers with a 48 in. receiving opening were being built by 1910, followed not long afterward by machines with 54 in. and 60 in. openings to . Fortunately for the crusher maintenance people of that era, an austenitic 12% Mn steel with exceptional toughness was already available, having been discovered by Robert Abbot Hadfieldoi in 1882. Although small gyratory crushers working soft- to medium-hard rock reportedly used chilled cast iron (white iron) wear parts, these newer and much larger machines were fitted with ""Hadfield's manganese steel"" concaves and mantles to withstand the impact associated with handling large rocks .M E International first challenged the long-standing convention of using 12% Mn steel concaves in large gyratory crushers in the late 1960s when they supplied upper row concaves in martensitic cast steel for a 60-109 primary crusher at a taconite plant on the Iron Range. Since then, martensitic steels have been successfully substituted for 12010 Mn steel in concaves for more than seventy primary gyratory crushers processing iron, copper and precious metals ores, industrial minerals and crushed stone.This paper reviews materials, designs and performance characteristics of martensitic steel concaves in large gyratory crushers. The principal benefits include significantly longer wear life, fewer pieces to install and the elimination of scarfing. Obtaining the full measure of these benefits and minimizing the risk of breakage is strongly dependent on installation procedures, which are described in some detail. Operating practices that can affect performance are also discussed."

Jan 1, 1993

By Frederic Carter

THERE have been many attempts to prove that platinum was known to the ancients, but since no traces of the metal have been found in the relics of early times, it must be concluded that it had not been known to them. As far as records go, it was actually first discovered in the 16th century in a Spanish mine on the Pinto River in South America; from which source it received its name of Platina del Pinto (little silver from the Pinto). It was more or less of a rarity and was a subject of interest to a few chemists only, until the year 1822 when the metal was first discovered in Russia. In 1819 there had been noticed in the washings of the gold sands of the southern part of the Ural Mountains, grains of a heavy white substance, but it was not until three years later that this substance was found to contain platinum. While at first the amounts of platinum brought from the Urals had been meager, prospecting soon disclosed rich deposits extending over a considerable area, and nuggets from 10 to 20. lb. were by no means rare. This discovery assured to chemists an ample supply of platinum for their crucibles, etc. The ore is now found in various parts of the world but the richest deposits are still found in the Ural Mountains. The platinum of commerce is obtained entirely from alluvial deposits at depths varying from 6 to 40 ft. The sand and gravel of former river beds are subjected to a series of screenings and washings to effect the separation of the ore. Actually, probably all gold-bearing gravel beds of the world contain platinum, and it is more than likely that large quantities of platinum ore have been thrown away with the black sand washings from gold placer deposits. This is especially true of the alluvial deposits of the Pacific Coast in California and Oregon. Platinum ore is usually found in the form of rounded or, flattened grains of "sand," and occasionally in irregular lumps of the size of peas. Large nuggets are very rare. The ore has a metallic luster and is distinguished by its steel gray color, but shows light gray streak when rubbed on a hard white surface; it has a high specific gravity, 16 to 19; is infusible in the hottest blast furnaces, and insoluble in any single acid. Platinum ore is a complex body consisting of the metal in combination with varying proportions of the other members of the platinum group; iridium,

Jan 1, 1928

By J. F. McMahon

Introduction The greater portion of the information presented in this paper was obtained in the course of an investigation on clay gathering and its cost in the provinces of Quebec and Ontario (1). For assistance in the preparation of the paper, the writer wishes to record his thanks to Mr. Howells Fréchette, Chief of the Ceramics and Road Materials Division of the Mines Branch. Clays are mineral substances consisting essentially of hydrous aluminium silicate which become plastic when wet, fairly hard when dry, and stony masses when burned to a sufficiently high temperature and re-cooled. Shales are clays which have been indurated by the processes of nature. Millions of tons of clays and shales are won yearly for the production of brick, tile, sewer pipe, drain tile, roofing tile, fire-brick, china-ware, wall and floor tile, cement, and a host of other products. There are certain types of clay which, due to their particular qualities and limited distribution, are mined entirely or in part for sale to manufacturers, and are even exported from one country to another, as for example china-clays or kaolins, utilized in the manufacture of white-wares and in the paper industry, due to their consistent whiteness; ball-clays, utilized in the white-ware industry, due to their bonding power and whiteness; slip-clays, used in the stone-ware industry because of their glazing properties, and in the grinding-wheel industry for their burned bonding properties; and suspension-clays, such as are used in the enamelling industry. However, the great bulk of clays and shales won are used in the production of heavy clay products, and the manufacturer of these generally owns and operates his own deposit of raw material.

Jan 1, 1933

The Council of the Institution of Mining and Metallurgy submitted the report of the affairs of the Institution for the session 1970-71, and the Statement of Accounts for the year ended 31 December, 1970. The statistics given in the report refer to the calendar year 1970. Details are included of membership, officers, representation on other bodies, honours and distinctions, awards, meetings, publications, library, overseas activities, fellowships and grants, the revenue and expenditure account, the balance sheet, trust fund balances, contributing companies, and schedule of investments

Dec 1, 1971

By John L. Hatton

The author will introduce and describe the nature of Fiberglas-Reinforced Plastics. Successful applications of corrosion-resistant structures will be shown and described, including pipe, ducts, tanks and other equipment. These structures are generally designed to handle corrosive liquids and gases and have proved both satisfactory and economical in service in various industries in Canada. The specification of structures will be discussed in relation to materials, construction and workmanship, physical properties and methods of testing.

Jan 1, 1970

By P. T. Brooks

The selective recovery of nickel and cobalt from impure raw materials is being investigated by the Bureau of Mines as part of a program to develop improved procedures for preparation of pure metals. A combination solvent extraction-electrolytic process has been developed in the laboratory that enables preparation of high-quality nickel and cobalt from nickel oxide containing, in percent, 76 nickel, 0.8 cobalt, 0.5 magnesium, 0.2 iron, and lesser quantities of copper, zinc, and other metals. The oxide was smelted, using carbon as reductant, and cast into anodes. These anodes subsequently were dissolved in diaphragm-type electrolytic cells. Nickel and cobalt were deposited separately from appropriate electrolytes, concurrent with dissolution of the impure anodes. Anolyte containing nickel and cobalt in the form of chlorides and sulfates was treated for removal of impurities and separation of nickel and cobalt. First, iron and aluminum were removed as hydroxides by adding nickel hydroxide to raise the pH of the anolyte from 2.3 to 4.5. Next, the pH was adjusted to 2 by adding hydrochloric acid, and the solution was treated by solvent extraction to separate nickel and cobalt.

Jan 1, 1963

By V. N. Mackiw

IN the process employed by Sherritt Gordon Mines Ltd. for the production of metallic nickel, a sul-fide concentrate is leached with ammonia and air under pressure. Following the removal of iron, copper, and other impurities, there remains a purified solution having the following analysis: 40 to 50 g per liter Ni, 200 to 400 g per liter (NH4)2 SO 4, and 20 to 30 g per liter NH3. Metallic nickel is reduced from this solution by hydrogen under pressure at 300' to 350°F in mechanically agitated autoclaves. A catalyst, ferrous sulfate, is required to initiate the first reduction. After the reduction, the depleted solution is discharged, leaving the metallic nickel in the autoclave. The nickel produced, being in a finely divided form, is used as a catalyst for the reduction of the next batch of solution. Upon repeated use the metallic nickel particles increase in size and become more compact, resulting in the production of a powder with higher apparent density. For this reason, each reduction is termed densification. Finally, when the burden of metal powder in the autoclave becomes too great to obtain effective agitation, both powder and depleted solution are discharged. The autoclave is then filled with fresh solution, ferrous sulfate catalyst added as before, and a new cycle started. The operation is described in earlier publications.1-6 A comprehensive historical review of the reduction of metals from solutions in general was given in a paper by Schaufelberger.7 The experimental data presented in this paper were taken from the work done in the Research Laboratory of Sherritt Gordon Mines Ltd. in Ottawa during the development of the process in 1951 and 1952. The results of the work were tested on a pilot plant scale in Ottawa in the period 1952 to 1953. Following laboratory and the pilot plant studies a commercial process has operated successfully since 1954 in the Nickel Refinery of Sherritt Gordon Mines Ltd. in Fort Saskatchewan, Alberta. General Experimental Technique The experiments were carried out in a stainless steel, 1-gallon, agitated autoclave designed and manufactured by Autoclave Engineers Inc. The inside dimensions of the vessel were 5 in. diam and 12 in. depth. The stirrer consisted of a 1/2 in. diam shaft 11 in. long fitted, with an axial flow type impeller (three blades bent to throw downwards) and a radial flow

Jan 1, 1958

By T. G. Nilan

Steels containing 0.4 and 0.8 pet C have been transformed isothermally at pressures up to 34 kbuv. Decomposilion mechanisms are so intimately related to phase equilibvia that, as the equilibria shift under high pressure, the microstruclures of the decomposition producls change, maintaining at pressure the same correspondence between a given phase equilibrium and a given microstructure as a1 1 atm. A bainitic unicvo-structure occurs in these steels at high pressure that IS observed only at 1 aim abole 1.4 pct C. This strrrcl111,e 1s ruliorzalized in terms of the effect of pressure on the transformation to lower bainite. The pressuve depetlderlce of the kinetics of pearlile formation is descrihed by an absolute rule theory amalysis. The activation volume for the transformation is 7 cu cm per mlole, which is indicative of a phase-interface transformation-rate cotntrol mechanism. This fortmulation, when expressed in terms of known solule effects on the energelics of tvansformation, gives promise of explaining the effects of alloying elemenls on hnrden-abilily, particularly that of 'coball. KINETIC processes in solids are functions of the primary thermodynamic variables of state: composition, temperature, and pressure. Until the development of high-pressure techniques' that permitted the generation of sustained high pressure at high temperatures, metallurgical studies of such reactions were largely limited to isobaric conditions at atmospheric pressure. The data so obtained, and theoretical deductions based on these data, were necessarily incomplete For the particular case of austenite decomposition, a knowledge of the phenomenology of the reaction in terms of all the state variables should lead to a clarification of the process. This deeper understanding should facilitate a decision between conflicting theories that have been proposed to rationalize these phe- nomena. An analysis, derived from an understanding of the transformation mechanisms, may aid in the optimization of alloy steel development. The first studies of the effect of pressure on transformations in steel were made by Kulin et al. in 1952.' In a study of the influence of applied stress on mar-tensite formation in a 30 pct Ni steel, they found that the martensite start (M,) was depressed 8°C per kbar* by hydrostatic pressure. Jellinghaus and Friedewold3 were apparently the first to investigate the effect of pressure on isothermal transformations above the Ms. They found that the bainite transformation rate in a 1.2 pct C, 3.8 pct Mn steel was reduced by a factor of 3 by a hydrostatic pressure of 4 kbar. In both of these investigations,2,3 the M, of the steels studied was below room temperature. Austenitizing and quenching were done at atmospheric pressure, followed by the decomposition of the metastable austenite under pressure. The maximum temperature at pressure in the bainite study3 was 350°C. Until the advent of the present high-pressure devices, it was not possible to conduct isobaric high-pressure heat treatments from austenitizing through isothermal decomposition and quenching. The exploitation of high pressure as a variable in metallurgical studies was greatly advanced by the apparatus and techniques developed by Hall4 and co-workers. Utilizing these techniques, Radcliffe et a1.5 and Hilliard6 etermined the pressure dependence of phase equilibria in the Fe-C system. Hilliard and cahn7 examined the pearlite transformation rate in an AISI 1080 steel and also in a high-purity 0.92 C Fe-C alloy at 1 atm and at 34 kbar and found a 700-fold reduction in rate at pressure in the 1080 steel but only a fivefold reduction in the high-purity alloy. In agreement with the shift of phase equilibria under pressure, the microstructures were hypereutectoid at 34 kbar pressure, whereas they are eutectoid at 1 atm. Determination of the effect of pressure on carbon diffu-

Jan 1, 1968

By S. S. Peng

In this paper, the precise definitions for a number of commonly used subsidence parameters are given. The subsidence parameters have been determined using an integrated approach for 110 subsidence cases collected in the major US coal fields. Attempts have been made to establish empirical formulae for the parameters. The results of this study indicate that some traditionally-held concepts should be changed.

Jan 1, 1995

By Roe-Hoan Yoon, Kaiwu Huang

Derjaguin and Dukhin (1961) were the first to develop a model for bubble-particle interaction in flotation from first principles by considering the surface forces in wetting (or flotation) films. The model predicted that the energy barriers to bubble-particle attachment arise from the ζ-potentials of fine particles, which corroborates well with an earlier work of Fuerstenau (1957) reported for the flotation of quartz using dodecyl ammonium acetate (DAA) as collector. In the present work, a series of surface force measurements have been conducted by accurately monitoring the changes in bubble curvature during bubble-silica surface interactions. The curvature changes are then used to determine the capillary force, which is the sum of the hydrodynamic and surface forces. By subtracting the former that can also be determined from the curvature changes, one obtains the surface forces (or disjoining pressure). The results obtained as functions of pH and collector concentrations show that control of the ζ-potentials of bubbles relative to those of the silica surfaces is critical for maximizing the negative disjoining pressure, which is conducive to promoting bubble-particle attachment in flotation.

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By D R. Seaman, B Adamson, F Burns, B A. Seaman, P Manton

The Telfer concentrator, located in the Great Sandy Desert of Western Australia, consists of a dual train gold/copper operation processing ore from one underground and, currently, two open pit mines with differing mineralogy. The flotation circuit of each train was designed to operate in several modes depending on the feed mineralogy. The majority of ore mined at Telfer is processed in a sequential mode where copper minerals are first floated into a saleable copper concentrate followed by the flotation of an auriferous pyrite concentrate which is treated in an on-site hydrometallurgical plant (carbon-in-leach (CIL)). Gold is recovered as a gravity product within the primary grinding circuit, to the copper concentrate, and to a lesser extent, the CIL circuit.Since Telfer was re-opened, with a new concentrator, in 2004, the processing plant has struggled with poor copper concentrate grades, partially due to the excessive entrainment of non-sulfide gangue minerals in the copper flotation circuit and, more recently, due to composite copper particles produced when processing ore from a supplementary satellite pit that has not previously been processed through the new Telfer concentrator. Gold recoveries in the CIL circuit have also been below industry standard. This paper presents the implementation of recent changes made to the circuit to address these performance issues. The reconfiguration of the circuit has involved the installation of the following major equipment items: two ISAMillsÖ in ultra-fine grinding applications (one in the copper circuit and one in the pyrite circuit), two Jameson Cells to improve fine gangue rejection and a bank of 5 + Outotec TC30s to recovery copper and gold from the reground pyrite stream. The equipment was purchased direct from vendors and an engineering firm contracted to design and install the multi-vendor reconfiguration upgrade.CITATION:Seaman, D R, Burns, F, Adamson, B, Seaman, B A and Manton, P, 2012. Telfer processing plant upgrade - The implementation of additional cleaning capacity and the regrinding of copper and pyrite concentrates, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 373-382 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By J. Groyecki, M. Markuszewicz, J. Lassota, A. Zawada

The ratio of stable to unstable inclusions was found to ploy an essential role in the process of sccorldar-y recrystatlizalion in Si-Fe. The analysis of the free energy of inclusions in the range of heat-treatment of individual inclusions to be predicted. The effects MnS. ns inslable inclusions. were investigated. TO secure a high induction, the secondary recryslulliztt-lion associated wilh the texture is necessary. To obtain a low core loss an additional refiuing in the solid state is required. It has been found that sulfur can be more easily removed in racunm than in hydrogen and thai this process was hindered by the prescrzce of INCLUSIONS play an essential role in the development of cube-on-edge texture in Si-Fe. Their function consists in restraining the growth of primary grains up to about 900°C and in passing subsequently into solution at higher temperatures. This process is accompanied by the selective growth of secondary grains with (110)[001] orientation. The general effect of inclusions depends on such factors as the type of impurities, their amount. dispersion and stability, the conditions of diffusion in the space of lattice of metal, and the reactions at the metal/gas interface. In recent years, some of these factors were the subject of a special investigation. A positive influence of Mns, siN,' and vN3 has been established. The quantity of impurities4 and their dispersion5 have been found to be of major importance. Attention was called to the vital importance of diffusion and the conditions under which the impurities are removed from metal., It has also been demonstrated that in Fe-Si alloys by the techniques of powder metallurgy a special opportunity exists to obtain the (110)[001] type texture. 6 The aim of this work was to conduct qualitative investigations on the influence of inclusion stability on the development of cube-on-edge texture in a metal containing approximately 3 pct Si. Experiments were carried out on cast alloys and on those manufactured by powder-metallurgy techniques. The results obtained from these experiments were utilized to explain the phenomena involved and to analyze the relationships between stable and unstable inclusions and the magnetic properties of alloys. EXPERIMENTS AND RESULTS The raw materials used in these experiments were the powder of carbonyl iron with the analysis (in pct) 0.044 C, 0.01 Mn, 0.005 Si, 0.009 P, 0.002 S, traces of Cu, 0.06 Ni, 0.0015 Al, 0.03 Cr, 0.02 Mo, 0.01 Ti, 0.002 Co, traces of Pb, and the powder of silicon containing 94.14 Si, 0.003 S, 0.048 C. The powders were ground and mechanically mixed in 100-g batches. and then pressed at 9 tons per sq cm into 74 by 24 by 8 mm blocks. Sintering was carried out at 1100°C for 12 hr in vacuum (2 x lo-' Tr) or in hydrogen. In this instance the material was heated slowly and subjected to prolonged soaking at 350°, 650°, and 750 2C, respectively, to secure reduction of ferro-oxides. This was checked by making measurements of the dew point, which was found to change from -15" to -35°C after reduction. The compacts after sintering were hot-rolled to 2.4 mm, annealed at 800 C, and finally cold-reduced to 0.35 mm with intermediate annealing at 800°C at a gage of about 0.8 mm. Impurities were added in the powdered form and mixed with iron and silicon powders. Sulfur in the elemental state, electrolytic manganese, and pure aluminum oxide were employed. Besides, to obtain a material with low contents of impurities, especially

Jan 1, 1967

By A. J. Kwitowski

Remote control for mining machines ordinarily means the operator is not seated on the machine, but is located within direct view of the machine and work area Thus, remote control operators are exposed to the hazards of roof/rib falls and dust/methane explosions. The U.S. Bureau of Mines has developed a method to disassociate remote operators from these hazards. Off-board, computer-based "tele-operational" systems are utilized that station the operators one-hundred meters or more distant from the working faces. Details are provided for tele-operated systems for thin-seam extraction and haulage equipment in highwall and deep, room-and-pillar coal mines.

Jan 1, 1992

By Daniel A. Wasson

A review of the history of boosters is given with examples of the prominent types that have been made commercially. The performance and design features of protected core boosters are discussed in detail. A new gel booster is discussed with its advantages to the mining industry. Booster size, hole configuration, performance and safety aspects are reviewed. Important features of boostering in above ground and underground blasting are related to an economic analysis. This presentation will cover different types of boosters commonly used in mining. However, for the purpose of this paper a few terms need to be defined to clarify the action of different parts of a priming system. Booster* - "Any unit of explosive or blasting agent to be used in a charged hole for the purpose of perpetuating or intensifying the initial detonation". Primer* - "A unit, package or cartridge' of explosives containing a detonator or detonating cord which is used to transmit detonation to other explosives or blasting agents". Detonator - A device for initiating a detonation from a flame or a small electric current, the former being represented by a fuse cap and the latter an electric blasting cap.

Jan 1, 1981

By J. Brune, P. J. Coleman, L. Martini

Research in the field of mining safety and health in the United States plays an important part in protecting the lives of miners. The National Institute for Occupational Safety and Health (NIOSH) Mining Program conducts surveillance, studies and developmental work aimed at improving the safety and health of miners. With recent reviews of the Mining Program by the National Academy of Sciences and the Mining Program response (NIOSH, 2008), the importance of setting goals, conducting high quality engineering and scientific research and evaluating the outputs, outcomes, relevance and impacts of these projects has been reemphasized. Surveillance of reported injuries is a first step in deciding on research directions and in designing specific projects. Groups of injuries often share features and attributes that suggest common causes and may respond to similar preventive efforts. Identifying groups of injuries also serves to prioritize intervention efforts. The Mine Safety and Health Administration (MSHA) Accident and Injury database (MSHA, 2008) provides individual case reports of mining injuries, illnesses and certain no-injury accidents (events such as roof falls that stop mine production or miners’ activities for more than one hour). This database is an indispensable resource for researchers and stakeholders needing information on the statistics of these events. From an epidemiological perspective, research projects target groups of miners at risk due to specific patterns of work, equipment, mine settings and the management of safety and health in their mines. Incidence rates are provided by the MSHA data for selected variables, such as surface/underground location, standard industrial classification and state. While incidence rates are the preferred measure for all variables, denominators are not typically available; for example, to more clearly understand the data about injury by occupational type, it would be necessary to conduct demographic surveys. A current survey of the demographics of the mining industry should be complete by 2010, which will allow incidence rates to be developed for a number of variables such as age, occupation and experience. This survey will provide the first update of its kind since the first survey was conducted in 1985. This report describes an alternative method of analyzing and presenting MSHA data for the purpose of identifying high-cost, high-severity injuries and illnesses. Researchers at the NIOSH Spokane Research Laboratory (SRL) developed programs to find the top five most frequent accident classes, natures of injury, types of accidents and other selected variables from the MSHA database. Studying these variables gives a cross-sectional snapshot of the most frequent groups of injuries within a commodity, regional group or time period, and allows researchers to quickly understand developing patterns for new research projects. The primary benefit of this approach is to

Jan 1, 2009

By F. T. Paleari

Radial gas holdup profiles have been measured in a 50x400 cm flotation column using a multi-cell conductivity probe. Three different bubble generation systems were examined: up to eight vertical filter cloth spargers, three horizontal filter cloth spargers, and three (horizontal) Cominco-type spargers. The variables tested were: number of spargers, symmetry of their arrangement, and height above spargers. Batch water with up to 20ppm frother concentration was used. The general observation is that the profiles tend to be uniform (i.e. flat) with some exhibiting a slight wavy shape. The vertical sparger arrangement proved the most difficult to achieve profile symmetry. The horizontal spargers gave uniform profiles at right angle to their length but a decreasing gas holdup along their length; the Cominco-type spargers gave slightly less scatter in the data. Switching off selected spargers (to simulate malfunction) did not produce strong asymmetry in the profiles.

Jan 1, 1993