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A construction material based on plasticized sulfur and mineral aggregate, that is superior in corrosion resistance and strength to portland cement concrete. The material can be used in the chemical, metallurgical, and fertilizer industries, and will also provide an attractive market for by-product sulfur resulting from compliance with pollution regulations. How It Is Made Sulfur concrete is thermoplastic material. Plasticized sulfur is mixed with sand and gravel aggregate heated to 375-400° F. The sulfur melts and acts as the binder or cement. The sulfur concrete is poured hot and sets at a temperature of 200° F. Full strength is attained in a few hours, compared to several days for portland cement concretes. Sulfur concrete even pours and sets in freezing weather. Although unmodified sulfur with aggregate will produce a sulfur concrete with good initial properties, it undergoes crystallographic modifications, and deteriorates with time, particularly when exposed to moisture or freeze-thaw conditions. The Bureau of Mines has developed plasticizers which, when reacted with the sulfur, give sulfur concretes with excellent moisture and freeze-thaw resistance. The plasticizers are based on mixtures of dicyclopentadlene (DCPD) and ollgomers of cyclopentadiene. About 5 percent by weight of the plasticizers is reacted with molten sui fur for several hours. The sulfur cement can be used directly or allowed to solidify for easier handling and storage.

Jan 1, 1981

IN this paper the author's intention is to convey a brief resume of the lead flotation treatment and lead flotation machines, which have replaced the May jigs and Wilfley tables at the plant of the North Broken Hill Ltd., and converted this mill into an all-flotation plant.Attention is directed to the fact that this drastic change from semi-gravity to all-flotation treatment, has been successfully accomplished without resorting to finer grinding than that previously in vogue for Wilfley table concentration, viz.: 10% to 16% plus 40-mesh I.M.M. screen.From the figures now available it is manifest that the scheme of all-flotation concentration-new as regards its successful application to Broken Hill ores is resulting in considerably higher-grade lead concentrates, and is substantially decreasing charges for labour, stores, and maintenance.The new treatment is far-reaching in its simplification of plant, as evidenced by the idle jigs and tables, and the results being obtained by North Broken Hill Ltd. may possibly influence metallurgical practice generally in Broken Hill.The outstanding features of the treatment are:(1) The coarseness, and high grade of lead concentrates obtainable.(2) The low time factor required for flotation.(3) The plant capacity, and the simplicity of its operation.(4) The low horse-power consumption.(5) The small cost for reagents used (not exceeding 3d. per ton of ore).

Jan 1, 1930

By Seth C. Schaefer

The Bureau of Mines investigated thermodynamic properties of Mn304 (manganomanganic oxide) and Mn203 (manganese sesquioxide). The standard Gibbs energies of formation (?Gf°) of Mn304 and Mn203 from their lower oxides were determined with high-temperature galvanic cells using stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, MnO, Mn304//Zr0 2//02(g, 0.0112 atm), Pt, with the overall cell reaction 6Mn0(c) + 02(g, 0.0112 atm) = 2Mn304(c), where- 02 refers to indicated partial pressure of oxygen at the reference electrode. Similar measurements were obtained for the cell Pt, Mn304, Mn203//ZrO2//02(g, 0.0115 atm), Pt, with the overall cell reaction 4Mn304(c) + 02(g, 0.0115 atm) = 6Mn203(c). Equilibrium oxygen pressures for the Mn0-Mn304-02 and Mn304-Mn203-02 systems were measured and may be expressed for the respective systems as [23,400 109 P02 T + 11.91 (764.9 - 1,208.6 K) and log p02 = - 11,957 + 9.66 T (968.6 - 1,208.2 K),] where pressure (p02) is in atmospheres and temperature (T) is in kelvins. Standard thermodynamic properties of Mn304 and Mn203 were derived from these measurements and auxiliary thermodynamic data from the literature.

Jan 1, 1982

By John Campbell, William Trahant

"Total Quality Management (TQM) is becoming a reality in the mining industry. Widely adopted in the manufacturing and services industries, TQM has become the operating style of choice in numerous mining companies across the Americas and Australia. Iron Ore Company of Canada, Inco, MSA, Graniterock, Magma Copper, and CRA's Hamersly Iron - all are pioneers of TQM. These companies and others are confronting the challenges of implementing TQM and are managing the changes required of their people and cultures. What these companies are doing, why they are doing it, and how they are successfully managing the changes are the subjects of this paper.Driving the need for change in these organizations are a host of issues, some of which all mining companies are facing. Requirements from customers for ISO 9000 certification is becoming one of the initial motivators for Total Quality Management. These standards, commonly used in manufacturing throughout the European Community (EC), emphasize quality in the processes that create outputs, instead of just the outputs themselves. Iron Ore Company of Canada, for instance, responding to the requirement of one of its customers, British Steel, has become one of the first mining companies to meet the quality standard. Suppliers who meet the standards are highly desirable to customers who are themselves operating under the ISO or their national quality guidelines."

Jan 1, 1995

By Pradip, Beena Rai

A molecular modeling study was carried out on an adsorbed oleate monolayer on the surfaces of three calcium minerals, fluorite, calcite and fluorapatite using Universal Force Field (UFF) potentials. The cleavage plane of calcite {104} was the best template for oleate monolayer adsorbed since the surface structure enabled all the calcium sites available on the surface to be occupied by oleate anions. The area occupied per chain of oleate in this well packed monolayer was computed to be 20.2 Å, which exactly matches the value calculated to be the parking area per oleate molecule for a fully packed monolayer based on strictly geometric calculations. On the other hand, the precentage of calcium sites occupied by oleate to achieve a fully packed monolayer in case of fluroite and and fluorapatite was found to be 67% and 75% respectively. The results of this theoretical study suggest that while all the three adsorption conformations, that is unidentate, bidentate and bridging type are equally likely on fluorite and fluorapatite, bridging is most likely on calcite. Interestingly, all the conformations are observed experimentally for calcite-oleate system also. The reasons for this discrepancy between the theoretical predictions and experimental observations are not clear. More work is required to resolve this discrepancy, in particular simulation studies in presence of solvent water molecules on the surface.

Jan 1, 2003

By P. C. Kapur

An approximate but simple and practical solution to the discretized batch grinding equation has been obtained. The solution is based on a new grind function, a combination of selection and breakage parameters and particle-size distribution of the feed. The grind function, which is readily computed from limited experimental data, has significant implications for analysis of the particle-size reduction processes. Using the practical solution, three ball-mill comminution systems—dry dolomite, wet quartz, and limestone—have been simulated with acceptable precision. The application of the discretized batch-grinding equation1 to routine comminution analysis is frustrated by two principal difficulties. First, the selection and breakage parameters of the grinding equation must be computed separately. This is usually a difficult and uncertain task although, recently, a number of experimentally and computationally efficient strategies have been proposed for determination of these parameters?" Second, for actual computation, the solution to the batch-grinding equation becomes progressively tedious and unwieldly for finer particle-size range.1,2 The purpose of this part of the report is to present an approximate solution to the batch-grinding equation, which is practical in that it seems to overcome the aforementioned obstacles. The solution involves the concepts of a new grind function, a lumped parameter of the selection-breakage functions, and particle-size distribution of the feed, which is readily computed from a limited amount of experimental data.

Jan 1, 1971

By L. C. Weiner

For zinc single crystals, xo = 3o, a surface coating raises both the cleavage and yield strengths over a large temperature range. The "brittle temperature," associated with slip after completion of twinning, does not coincide with the point of intersection of the flow and cleavage curves, which is associated with twinning. A surface film has no effect on the brittle temperature, while it lowers the intersection temperature some 20°. For crystals, yn = 83o, a coating decreases the cleavage strength, making it temperature independent, as well as increases the brittle temperature or its equivalent, the intersection temperature, 20°. These observations are described on the basis of a dislocation-pile-up-at-a-barrier model for brittle fracture; in crystals x,, = 3o the number and distribution of twins play a vital role. IN a recent investigation on the effects of solid environments on the brittle fracture of zinc single crystals,' it was demonstrated that the presence of a surface film changes the cleavage strength of these crystals, either increasing or decreasing it, depending on the crystal orientation. An increase in cleavage strength of some 43 per cent was found for coated crystals oriented x, — 3o K = 28",* while a decrease of 48 per cent was observed with crystals X" = y» — 83". Moreover, these effects were found

Jan 1, 1959

By J. B. Sabey, V. R. Degner, D. MacGillivray

"Hydrodynamics principals are applied to the design of a natural air ingestion flotation machine for coarse solids applications. Preliminary laboratory test data and subsequent operating plant flotation kinetic performance evaluations are reviewed. INTRODUCTIONThe concentration of potash (sylvite, KCI) from halite and other salts using flotation is well understood and practice a with much success. Reagent schemes and plant circuitry for obtaining the desired product recovery and grade have been established with proven performance. These flotation circuits normally process the medium and finer size particles, less than 30 mesh (600 microns).However, often the potash market trends specifically demand a coarse product size. This emphasis, accompanied by the existing high losses of coarse (+30 mesh) potash in flotation circuits, creates the need for development of a flotation machines specifically designed for coarse potash beneficiation.This technical challenge was undertaken by the WEMCO Research and Development Group. The specific objectives of this flotation machine development program were ( l) to achieve an ""Ultra Coarse Flotation Machine"" capable of adequately suspending and transporting particles in the 4 - 30 mesh (4.75 - 0.6 mm) size range at solids concentrations of 30% or greater and (2) ascertain metallurgical performance of this machine.This paper covers the development (both theoretical and mechanical/ hydrodynamic), the field test program and results, a discussion of applicable flotation kinetics, and conclusions of this ""Coarse Potash Flotation Machine"" development project."

Jan 1, 1986

By Dermot M. Ross-Brown

Introduction Slope angles are one of the major factors affecting the shape of the final pit and the location of the walls Due to differences in geology, the optimum slope angles vary from pit to pit and within different parts of the same pit. Indeed, it is not unusual to have different slope angles for the top and bottom portions of the same cross section. The optimization of these slope angles is a major study in itself and this chapter is intended as a general introduction to the subject. It is not intended to be a comprehensive text for the absolute beginner The objective is to put the various aspects of slope stability analysis into relative perspective by describing the vari¬ous analytical techniques available and indicating when each may be most appropriately used References are made to the many excellent texts and papers on slope stability for the reader who does not have a formal training in soil or rock mechanics. In writing this chapter, an assumption has been made that a tentative mining plan has been drawn up, includ¬ing a preliminary estimate of the slope angles. It has also been assumed that all the necessary field and laboratory data has been collected and reduced to a form suitable for input into the stability analyses.

Jan 1, 1979

By A. E. Gorum, J. Washburn, E. R. Parker

Experimental evidence was obtained in support of the idea that cleavage fracture can be initiated by dislocation pile-up. The high ductility of MgO crystals when tested in bending comPared to their relative brittleness in tension was explained on the basis that large pile-ups are more likely in a tension specimen. CLEAVAGE fractures have been a problem of major concern for many years. A number of large steel structures have failed in a brittle manner, usually suddenly and without warning; often the failures occurred for no obvious reason and at nominal stress levels well within the generally accepted range. A great deal of data have been collected about factors that contribute to failures,1 but the physics of the fracture process has never been revealed. cottrel12 has recently developed a theory of brittle fracture in ductile materials which was based upon the concept that dislocations moving on two intersecting planes can unite to form a crack nucleus. This theory accounts for the known effect of grain size and for the effect of testing temperature. There has, as yet, been no experimental evidence published that would substantiate this or the earlier theories based on stress concentrations due to piled-up dislocations. The study reported herein was conducted to obtain information that would either substantiate or disprove the

Jan 1, 1960

By Bruce D. Sartwell

The Bureau of Mines is using characteristic X-rays produced by proton bombardment of a solid surface to provide quantitative compositional analyses of surface layers of metals. An integral X-ray yield equation has been developed that quantitatively relates the measured X-ray yield to the thickness of thin films ranging from less than a monolayer to several thousand angstroms. The use of the integral yield equation is demonstrated for the growth of a thin film by vacuum evaporation. Results are presented that show haw proton-induced X-ray emission (PIXE) has been used to determine the oxidation kinetics of iron that had been implanted with several different species of heavy ions. The sensitivity of PIXE for the measurement of very-thin-film growth kinetics is demonstrated from studies of the effect of fractional mono-layer coverages of sulfur on the initial oxidation kinetics of iron. Results are also presented in which PIXE has been used to study the redistribution of alloying elements in components of a gas turbine that had fractured due to corrosion fatigue. By combining PIXE with low-energy ion sputtering, quantitative composition depth profiles of surface layers are obtained. Examples are presented for the profiling of iron samples implanted with 25-kev nickel ions and for a platinum coating on an Fe-5Cr substrate.

Jan 1, 1980

By G. C. Hancock

The operating plant of The Broken Hill Associated Smelters Pty. Ltd. is situated at Port Pirie in South Australia and it treats to finality the whole output of lead concentrates from the mines of The Zinc Corporation Ltd., North Broken Hill Ltd., and aroken Hill South Ltd. at Broken Hill, New South Wales. Lead bearing ores from other sources are also purchased for treatment and lead scrap and residues are treated on a toll charge basis. The present output of the plant is approximately 200000 tonnes of refined lead per annum and there is a substantial production of by-products including refined silver, gold, cadmium, antimonial lead alloys, copper matte and sulphuric acid. Recently the Company commenced the production of zinc by slag fuming and electrolysis from a six million ton dump of lead blast furnace slag, which has been accumulating at Port Pirie for over fifty years. The slag fuming plant contains two furnaces of conventional design, but features a high degree of pre-heat for the blast air and this is obtained by the use of all-metal recuperators. The raw zinc oxide fume produced by the plant is roasted in a rotary kiln prior to treatment in the leaching and electrolysis sections, which follow conventional practice for nigh current density plants. Present output is approximately 36000 tonnes of electrolytic zinc per annum.

Jan 1, 1970

By Jan Mehren, Arild Neby

Underwater Tunnel Piercing or Lake Tap, often also called the Norwegian Method, will in many projects be an important part of the hydro electric development scheme. The very last blasting round in the Lake Dorothy Lake Tap Tunnel, which penetrated into the lake at a depth of 120 ft (36 m), was such a key step in constructing the Lake Dorothy Hydroelectric Project. A lake tap project is multidisciplinary. Besides the pure blasting and construction technique aspect, engineering geological and geometric considerations that aim to optimize the tunnel alignment making a lake tap possible at minimized risk are of significant importance. Output data from numerical model analysis of the hydrodynamics resulting from the blasting is vital for the final adjustments to the geometrical layout. The planning of monitoring systems for the surveillance of hydrodynamic impact on valves and pipes as well as control with water levels and air pressures prior to and during the blasting, are all additional crucial elements in the design. More than 600 lake taps have been successfully performed in Norway since the 1890`s. The technique, which deserves to be called well proven, has been applied mostly in the hydropower sector but over the last 20 years also for shore approaches in the oil and gas industry. The demand for this technique seems to be ever more growing.

Jan 1, 2009

By J. M. Pilcher

The application of oil to coal for-the reduction of dust has greatly increased the consumers' satisfaction with solid fuels, especially those for domestic use. The combination of oil-treated coal and automatic firing by a small stoker has made possible clean, automatic heating with bituminous coal. This, with the added pressure of competition by other fuels, has caused a rapid development of oil treating practice. A variety of materials derived" from petroleum oils is available from which one may choose for treating a par-ticular coal. Until recently, however, little information had been published to guide the choice. It is most im-portant that the proper type and amount of oil be used in order that all coals marketed as "dustless" will be reason-ably dustless, and thereby maintain a good reputation for oil-treatment. During the past two and one-half years, an investigation of a number of the problems related to the treatment of coal with oil has been conducted at Battelle Memorial Institute. This project was jointly sponsored by Bituminous Coal Research. Inc., Standard Oil Company of New Jersey, Sun Oil Company, and Viking Manufacturing Company. A progress report giving the principal results of the work of the first year was presented before the American Society of Mechanical Engineers in December 1937.1 The present paper is a summary of the entire inves-tigation.

Jan 1, 1939

By Eric R. Bauer

Skin failures of roof and rib in underground coal mines continue to be a significant safety hazard for mine workers. Skin failures do not usually involve failure of the support systems but result from rock or coal spalling from between the support elements. For instance in 1997, over 800 miners were injured by roof and rib falls, of which 98 pet were the result of skin failures. Also, nearly 80 pct of the roof and rib failure injuries occurred at or near the working faces in development sections. The face area is a zone where the potential for skin failure accidents and injuries and roof and rib failures, in general, is high because of mining activity, ground readjustment due to changing stress conditions, and the higher exposure of mine workers. In addition, failures occur where the roof and rib are unsupported. This paper features a review of the roof and rib accident statistics resulting from skin failure, highlighting the incidences by average days lost, in-mine location, state, MSHA District, and worker activity at the time of injury. A detailed analysis of recent fatalities caused by skin failure is included. Also discussed are the causes of roof and rib skin failures, current methods and support materials for skin surface control, as well as a historical literature review of skin failures and control methods.

Jan 1, 1999

By Willard H. Mutchler, Henry S. Rawdon

As part of the study of the scratch-hardness method for metals and alloys in coöperation with one of the technical committees of the American Society for Testing Materials, the authors devoted considerable time to the study of the changes in hardness of metals when cold rolled. Various seemingly contradictory statements in the technical literature concerning the applicability of the serateh-hardness method to such cold-rolled materials were among the principal reasons for the investigation, the results of which are in part presented here. The effect of cold deformation, at least in moderate degrees, on the hardness as measured by the Brinell aid other common methods is so well known that further reference is unnecessary. Concerning the scratch hardness of cold-worked metals, Martens and Heyn state1 that hardness, whether measured by the ball-pressure rnethod (Kugeldruck) or by the scratch method (Ritzverfahren), will be increased by cold deformation. Jeffries and Archer give a seemingly diametrically opposite view. They state,2 that "the sclerometer (indicating scratch hardness) shows little difference between cold-worked and annealed metals." Portevin3 has shown that the rate at which the Brinell hardness of cold-worked copper and brass increases is very high for relatively slight deformation after which it drops to zero, while Merica and Walten-berg4 have observed that monel metal shows evidence of softening on

Jan 1, 1924

By Grader F. E

A linear motor properly wound can serve as a mechanism for separating paramagnetic sulphide minerals, like pyrrhotite, from other sulphides and associated gangue minerals. The effective- ness of separation depends on the energising current of the separator, the frequency of the a.c. cycle, and the particle size of the minerals. The speed of travel of the minerals over the surface of the separator is also a function of particle size, and appears to be constant. The movement of pyrrhotite, magnetite and iron filings of comparable size fraction (150um +74pm) on the linear motor surface has been observed using a cine camera. An attempt has been made to give a theoretical basis for the movement of the particles by calculating the minimum electrical energy required to move them. Further, the rate of decay of magnetic moment of the particles has been estimated for magnetite and it has been found that sufficient residual magnetism existed in the particles after they had been exposed to the first half of an a.c. cycle for them to have like polarity with the second half of the cycle. The particles are therefore repelled from the motor surface every second half of the cycle. This repulsion due to remanent magnetism is the probable cause of particle movement over the linear meter surf, e.

Jan 1, 1980

By G. W. Brock

Experiments in the form of aging of overstrained tension specimens and elevated temperature tension testing, have been carried out on recrystallized arc-cast molybdenum. The aging behavior of molybdenum was found to be strongly dependent on the degree of plastic strain present in the lattice: the reason for this being the low solid solubility for the common interstitial elements in molybdenum. GEORGE W. BROCK, formerly Research Associate, Department of Theoretical and Applied Mechanics, University of Illinois, Urbana, III., is Research Associate, Department of Engineering Sciences, IBM Research Center, Yorktown Heights, N. Y. Manuscript submitted January 19, 1961. IMD THE term strain aging is familiar in connection with the recovery of the yield point in mild steel after tensile overstraining, and there are other instances where it is known to exert an appreciable effect on mechanical properties. For example, steel exhibits a greater tensile strength at mildly elevated temperatures than at room temperature and serrated stress-strain flow curves occur under certain conditions. It has been known for a number of years that the phenomenon of strain aging is directly connected with the presence of carbon and nitrogen in the lattice; and extremely small amounts of either element are sufficient to produce the effect. In this study, the aging behavior of overstrained tensile specimens of recrystallized molybdenum has

Jan 1, 1962

By Neil H. Bostick

A specialized electronic data system processes data taken from normal gologic maps and stratigraphic tables to yield predictions of uranium resource location for an area such as much of the United States. Strata underlying specific quadrangle cells of the earth are evaluated for uranium favorability on the basis of selected criteria of lithology, structure, and stratigraphy but not specific past production in the area. Stored data are computer processed to yield volume of likely host rock beneath each cell to a given depth and at a given favorobility level. Results are plotted by machine directly as maps. A specialized and simplified procedure for predicting approximate uranium resources has been devised at Stanford Research Institute (SRI). The prediction is based on general geology beneath specific area cells of the earth in order to provide complete volume coverage; the strata underlying these areas are evaluated for uranium mineral favorability on the basis of a few selected geologic criteria in order to allow rapid data input. In order that the predictions be generally applicable, they are based on geological factors only, not past ore production of a given cell. Since the bulk of U.S. resources are in elastic host rocks, only such strata are considered in this work. This paper describes the structure and some details of the resource system and how it was tested in an area of the western United States.

Jan 1, 1971

By André Zingano

Pillar collapses have been studied for several years and can be classified into two types: nonviolent squeeze or violent pillar collapse, i.e., controlled or uncontrolled pillar collapse. Underground coal mines in Brazil are considered shallow mines, because the overburden thickness varies between 20 and 400 meters. For this reason, the coal pillars should be designed as permanent pillars to avoid subsidence and groundwater problems. In the last two years, various pillar collapses occurred, one being a violent collapse and the others being squeeze collapses. All these collapses were considered massive pillar collapses because many pillars were involved. In the violent pillar collapse case, the width¬to-height (w/h) ratio was less than three; although, the pillar safety factor (SF) was more than 1.3. There was a collapse of about 100 pillars in less than three hours. The objective of this study is to determine the mechanism of pillar collapse for this violent pillar collapse. Convergence monitoring and numerical modeling were applied to combine field data and theory to simulate the pillar collapse. Convergence field measurements introduce the arc-effect behavior for the roof. The results showed that other factors besides pillar geometry caused the pillar failure. Other parameters, mainly dip of the coal seam and presence of fractures and faults may affect the strength and failure mechanism of a pillar.

Jan 1, 2004