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By Syd S. Peng

The key design parameters of roof bolting using expansion - shell type support for underground coal mine roof support are bolt length, bolt spacing, installed load and anchorage capacity. Depending on the utilization of suspension effect or friction effect, the bolt length is dictated either by the distance between the roof surface and the first overlying strong strata encountered or the desired magnitude of reduction in bending stress at the roof surface, The current prevailing practices about the bolt spacing and installed load are that an initial torque of 125 - 170 ft-lbs is applied and the bolts are spaced at 4- or 5- ft. square grid pattern. This seems to be a rather broad generalization in view of the great geological variances which are expected in underground coal mines. A modest evaluation program to measure the effectiveness of current roof bolting practices is to monitor the load history of roof bolts during a complete mining cycle including the phases of room development and pillar robbing. The load history, when compared with the anchorage capacity of roof bolts determined by in-situ pull tests, will provide information for evaluating the installed load, the bolt spacing as well as the specifications for structural and anchorage characteristics of the bolt assemblies. This paper presents a case history of monitoring the complete load histories of roof bolts in an underground coal mine of Pittsburgh seam.

Jan 1, 1976

By Atul Bhatnagar, M. P. Sinha, Md Zahid Ahmad, Pallav Garg, Sanjay Kumar Singh, Shashi Ranjan, An Ecolab Company Nalco Water

"Froth Flotation is undoubtedly one of the most critical processes in coking coal washing plants. This work was carried out at Bhelatand Coal Preparation Plant of Tata Steel was with an objective of cost optimization in fine coal processing. The sources of raw coal for the plant include coal from underground mines of Jharia coalfield and procured open-cast raw coal. Coal from different sources vary in quality and possess different floatability characteristics.Synthetic collector is being used in plant as a flotation reagent. An alternate collector with new chemistry was developed for reducing total treatment cost without compromising product yield and quality. A series of laboratory tests were conducted to assess the performance of various sources of raw coal and plant scale trial was started. At first, the new generation coal collector was entirely substituted with the existing collector in the laboratory scale. However the plant scale trial data was not in accordance with laboratory results and indicated inferior flotation performanceThe issue was studied and data based conclusions were drawn that the new generation collector aids faster and uncontrollable kinetics. A decision was taken for co-dosing of the synthetic and new collector for the second phase of the trial. A detailed laboratory analysis was done again and few dosing ratios that predicted optimum results were selected for plant trial. The dosing ratio was optimised as per flotation yield and product ashes during the plant trial. The results showed significant improvement from the first phase and optimum dosing rates were decided based on plant observations and data collection. The influence of various process indicators including water quality, feed and product ashes and process yield was studied during all the trials and promising results were established. The co-dosing of both the collectors conferred cost advantage and enabled to achieve superior performance."

Jan 1, 2016

By D. R. Hay, E. Scala

STUDIES of structure-sensitive properties, especially mechanical behavior, have shown that grain and subgrain structure play an important role. The mechanical properties of tungsten, in particular, are sensitive to the nature of the intergranular structure. Substructure and dislocation networks in single-crystal and polycrystalline tungsten have been studied by Nakayama et al.' Various orders of substructure were observed ranging from a microscopic first order (grain diameter: 2 to 8 mm) to a microscopic second order (grain diameter: 50 to 300 p), and, within the latter, dislocation networks forming an even smaller order of substructure. In their single crystals, grown by arc fusion, the degree of misorientation in each order was small: 16'3OU, -11, and -10" for the first-, second-, and third-order substructure, respectively. To study the properties of polycrystalline tungsten, powder metallurgy tungsten is generally used. However, in a mechanical property investigation, the zone-melted or arc-fusion crystals are more desirable than the powder metallurgy product due to their higher purity and absence of porosity and other defects inherent in consolidation by powder metallurgy. Grain boundaries can also be produced in melted stock by working and recrystallizing. However, material with subgrain mis orientations of the order of several degrees (high-angle substructure) has not been reported previously and is the subject of this communication. Crystals were grown by electron-beam, floating-zone melting. The starting material, Sylvania Pure-tung welding rod, was given one zone pass at a traversal rate of -2 mm per min. Through control of the zone temperature, it was possible to influence the degree of crystal perfection. By maintaining the zone at a high degree of superheat, high-perfection crystals could be grown. However, at temperatures only slightly above the melting point, the zone-melted crystals contained a high-angle substructure. A sensitive control of the zone temperature was not possible due to the difficulty of estimating the temperature of the zone and of providing a constant supply of power to the sample. Therefore, an empirical method, using the shape of the molten zone as a criterion, was adopted as an indication of temperature. At high degrees of superheat, the surface tension of the molten zone decreases and a neck forms at the top of the zone, whereas at low zone temperatures the diameter of the zone remains reasonably uniform. Although it was not possible to obtain a continuous variation of misfit angle, the conditions could be directed toward the growth of either high- or low-angle substructure by maintaining only a slight neck in the zone (sufficient to establish that it was molten) or a well-necked zone, respectively. Mass spectrographic analyses of both types of material revealed no significant differences in the concentrations of their impurities. The degree of misorientation at high angles was obtained by measuring the angular spread of spots corresponding to a single reflection on a Laue back-reflection photograph. Fig. 1 shows a typical Laue back-reflection photograph of a crystal with a 3-deg spread. By measuring the angular deviation of the spots corresponding to a single reflection from the mean center of the spots around which constant angular deviation contours were drawn, an average angular spread of misfit could be calculated. The angular average was weighted by the number of spots observed in each angular interval. At angles greater than 5 to 6 deg the spots from different reflections begin to overlap, and cannot be associated with a particular reflection. Laue back-reflection photographs taken at different locations on samples .with approximately 3-deg spreads showed only a small difference in angular misorientation, less than 8' of arc, within individual specimens. The microstructure was examined using Berg-Barrett X-ray extinction contrast microscopy. Berg-Barrett photographs taken directly on the as-grown surface, Fig. 2, show an essentially equiaxed subgrain structure of -0.1 mm in average grain diameter in both high- and low-angle crystals. Fig. 2(a) is a photograph of a sample with a low misfit angle and Fig.

Jan 1, 1968

By Robert Cameron, Colin Ashton, John MacNeil, Leo Piciacchia

"The in pit dam construction and utilities relocation, known as the East Mine Corridor Relocation (EMCR) project, was developed to extend the life of the east side of the Base Mine pit by two veal's. This will result in the recovery of an additional 80 million barrels of oil and delay expenditures associated with the opening of the North Mine by two years. To accomplish this, a large in pit earth structure was required to provide a new embankment foundation for relocating a public highway, four powerlines, a natural gas back-up pipeline, a substation, and a conveyor train. This structure would also he required as a temporary dam 10 contain mature fine tails on the west side until mining is completed in the east mine corridor area, that will then be filled with fluid.The in pit dam, known as The Highway Berm, is 2.5 km long, 63 m high and has 42 million m3 of engineered soil added to the already existing end-dumped soil volumes. To complete the design and construction of a structure of this magnitude, in the very short time frame of two-and-a-half years, presented many new challenges. The main challenges faced were: designing while construction was ongoing; designing without the use of clay cores or sand filters; using relatively non-select overburden material; proper dewatering and base preparation; changing from construction of 50 m high spoil piles to a high specification construction operation; compacting lifts with heavy haulers; constructing during the winter; and monitoring movement of the structure with satellites."

Jan 1, 1995

By W. J. Leas, L. A. Rapoport

As a preliminary, consicleration is given to the conventional definition of relative permeability and to the conditions governing the simultaneous flow of oil and gas through porous media. For the conditions of flow prevailing throughout most of a gas drive reservoir, the oil and gas can reasonably be supposed to be in capillary equilibrium with each other. Under these conditions, and these conditions only, the relative permeability to liquid can be expressed as a function of saturation. The relative permeability to liquid in that case is dependent upon the distribution of fluids which itself is shown to be related to the capillary pressure, and, in turn, to the saturation. As a consequence, relative permeability to liquid can be expressed in terms of the volume and surface area of a network of liquid channels bounded by the rock and the gas phase. While the volume of this network can be evaluated accurately, the surface area cannot. However, for any such volume, maximum and minimum values of the corresponding surface area can be calculated from capillary pressure data. It is then possible to establish for any saturation the limits within which the value of the relative permeability to liquid must lie. As a consequence of the theoretical development, the validity of an experimental method for measuring relative permeability to liquid which utilizes a stationary gas phase is demonstrated. In this method capillary barriers are cemented to the ends of the core sample to permit the maintenance of capillary equilibrium between the two phases. At the same time, this procedure eliminates undesirable secondary phenomena such as end effects, fissure effects, etc., the presence of which adversely affect the results of other laboratory methods. The results obtained by theoretical calculations, and experimentally, are discussed. In view of the overall precision that can presently be obtained in reservoir calculations, the agreement between the calculated and measured relative permeability to liquid data can be considered satisfactory. In conclusion, for reasons of economy and simplicity, the procedure of calculating limiting relative permeability to liquid curves from capillary pressure data is indicated for general engineering purposes. It is shown that the above procedure can easily be extended to the cases where connate water is present. Its use for reservoir studies is particularly recommended in conjunction with the method for measuring relative permeability to gas' which simultaneously yields the capillary pressure data necessary for the calculations. THEORETICAL Definition of Relative Permeabilities — Basic Equations for Heterogeneous Flow The equations by which the relative permeability concept is defined and upon which the formulation of all of the gas-oil flow problems rests at the present time are expressed as: V, = — Grad PL = — Grad PL ....(la) PL µL, k k KG VG = —K - Grad PG k- Grad Pc .... (lb) Mo where ,. and G refer to liquid and gas; V is the volumetric rate of flow per unit gross area. µ the viscosity, Grad P the potential gradient. and k the specific permeability of the porous medium.* (For horizontal flow, Grad P becomes the pressure gradient; otherwise, gravity must be included.) According to these expressions, each of the constituent phases is considered similar to a homogeneous system where the volumetric rate of flow is proportional to the pressure gradient, and for each of which the constants of proportionality, k, and kG, are termed effective permeabilities. by analogy to the specific permeability as defined by Darcy's law in its original form. In order to obtain a convenient basis of comparison, the effective permeabilities are referred to the specific permeability, k, of the considered porous medium, with the help of the relations: k1. = KI. k kQ = Kn k..........(2) K,. and Kr. are defined as the relative permeabilities to the liquid and to the gas phase respectively, and frequently expressed in per cent of specific permeability. It may be seen that Equations (1); which appear to be a direct generalization of Darcy's law, correspond to the assignment at any given time of a set of "local" permeabilities to each point of the porous medium, and represent in a differential form the two fluid flow system as a simple superposition of the individual single flow systems. The above interpretation implies that the effective or relative permeabilities are independent of pressure or rate of flow,

Jan 1, 1951

By L. A. Rapoport, W. J. Leas

As a preliminary, consicleration is given to the conventional definition of relative permeability and to the conditions governing the simultaneous flow of oil and gas through porous media. For the conditions of flow prevailing throughout most of a gas drive reservoir, the oil and gas can reasonably be supposed to be in capillary equilibrium with each other. Under these conditions, and these conditions only, the relative permeability to liquid can be expressed as a function of saturation. The relative permeability to liquid in that case is dependent upon the distribution of fluids which itself is shown to be related to the capillary pressure, and, in turn, to the saturation. As a consequence, relative permeability to liquid can be expressed in terms of the volume and surface area of a network of liquid channels bounded by the rock and the gas phase. While the volume of this network can be evaluated accurately, the surface area cannot. However, for any such volume, maximum and minimum values of the corresponding surface area can be calculated from capillary pressure data. It is then possible to establish for any saturation the limits within which the value of the relative permeability to liquid must lie. As a consequence of the theoretical development, the validity of an experimental method for measuring relative permeability to liquid which utilizes a stationary gas phase is demonstrated. In this method capillary barriers are cemented to the ends of the core sample to permit the maintenance of capillary equilibrium between the two phases. At the same time, this procedure eliminates undesirable secondary phenomena such as end effects, fissure effects, etc., the presence of which adversely affect the results of other laboratory methods. The results obtained by theoretical calculations, and experimentally, are discussed. In view of the overall precision that can presently be obtained in reservoir calculations, the agreement between the calculated and measured relative permeability to liquid data can be considered satisfactory. In conclusion, for reasons of economy and simplicity, the procedure of calculating limiting relative permeability to liquid curves from capillary pressure data is indicated for general engineering purposes. It is shown that the above procedure can easily be extended to the cases where connate water is present. Its use for reservoir studies is particularly recommended in conjunction with the method for measuring relative permeability to gas' which simultaneously yields the capillary pressure data necessary for the calculations. THEORETICAL Definition of Relative Permeabilities — Basic Equations for Heterogeneous Flow The equations by which the relative permeability concept is defined and upon which the formulation of all of the gas-oil flow problems rests at the present time are expressed as: V, = — Grad PL = — Grad PL ....(la) PL µL, k k KG VG = —K - Grad PG k- Grad Pc .... (lb) Mo where ,. and G refer to liquid and gas; V is the volumetric rate of flow per unit gross area. µ the viscosity, Grad P the potential gradient. and k the specific permeability of the porous medium.* (For horizontal flow, Grad P becomes the pressure gradient; otherwise, gravity must be included.) According to these expressions, each of the constituent phases is considered similar to a homogeneous system where the volumetric rate of flow is proportional to the pressure gradient, and for each of which the constants of proportionality, k, and kG, are termed effective permeabilities. by analogy to the specific permeability as defined by Darcy's law in its original form. In order to obtain a convenient basis of comparison, the effective permeabilities are referred to the specific permeability, k, of the considered porous medium, with the help of the relations: k1. = KI. k kQ = Kn k..........(2) K,. and Kr. are defined as the relative permeabilities to the liquid and to the gas phase respectively, and frequently expressed in per cent of specific permeability. It may be seen that Equations (1); which appear to be a direct generalization of Darcy's law, correspond to the assignment at any given time of a set of "local" permeabilities to each point of the porous medium, and represent in a differential form the two fluid flow system as a simple superposition of the individual single flow systems. The above interpretation implies that the effective or relative permeabilities are independent of pressure or rate of flow,

Jan 1, 1951

By H. Bernatowicz

The Nucoalyzer (On-Line Nuclear Analyzer) is a new method recently made comercially available for monitoring the elemental composition of a process stream. Applications for the Nucoalyzer include grading ore on a conveyor belt before or after it has gone through primary crushing, monitoring the slurry being transported in a pipe to the concentrator, and monitoring the stream of concentrate or the tailings from the concentrator. The Nucoalyzer may also be used at the smelter to monitor elements in the feed that include copper, sulfur, iron and silicon where a uniform feed is desired. The advantage of the Nucoalyzer over most other techniques are (a) it performs the measurement directly on the process with no sampling necessary, (b) the analysis can be performed on streams of particulate and slurries, and (c) the system does not have to make contact with the material it measures. These Nucoalyzers are operating at coal fired power plants and several more are about to be placed in service. This paper discusses the principles of operation of the Nucoalyzer, our experience in the field, application of minicomputers to data reduction, and potential applications in the ferrous and non-ferrous industries.

Jan 1, 1982

By G. S. Nus

Technology for treating man-made metal-containing raw materials in DC electric furnaces with polarization of the bottom phase (PDF furnaces) has been developed and proven on a semi-commercial scale. PDF furnaces permit processing of man-made raw materials, i.e. current and accumulated intermediate products with rather high contents of valuable metals (i.e. slags, sludge, residues, Waelz slag, etc.), as well as secondary raw materials and virtually any type of waste using an environmentally safe technique based on sublimation of volatile metals and transfer of non-volatile metals and sulfur into the bottom phase in the furnace. Processes developed on the basis of the use of PDF furnaces make it possible to take advantage on a full commercial scale of electrolysis of molten materials, including electrochemical reduction of metals, intensification of their settling into the bottom phase and sublimation of volatile components, as well as to significantly improve recoveries of nonferrous metals, resolve the problem of excessive accretion formation in slagging processes and substantially improve the environmental situation. The low-grade discard slag obtained can be utilized in the construction industry; in particular, slag can be added to the limestone feed for cement manufacture.

Jan 1, 2006

By A. García-Gutiérrez, A. Aragón-Jerónimo, R. Salazar-Mendoza

A theoretical analysis of a two-region solid-liquid flow system in horizontal pipes is presented, which considers a stationary bed of drill cuttings as a porous medium (-region) below of a two-phase dispersed flow (-region).The method of volume averaging was applied in this study to derive a rigorous mathematical model in which each variable is precisely defined. This model includes the volume-averaged transport equations for both the two-phase dispersed flow and the porous medium regions and terms from a macroscopic forces balance. The solution of the two-region model allowed evaluation of the behaviour of pressure gradient as a function of velocity, total volume fraction of cuttings and the relationship of the height of the stationary bed and pipe diameter. The solution is based on a backward finite difference explicit scheme. The simulated physical system is a pipe of 4.135 m in horizontal length and 0.0508 m in diameter. A one-dimensional, mesh-centred grid, consisting of 100 nodes, is used. The numerical results were compared with experimental data on slurry flows and a good agreement was found. Keywords: two-phase, cuttings transport, solid-liquid flow, drilling modelling, volume averaging.

Jan 1, 2007

The Bowen Basin of Central Queensland covers a total area of 3 200 000 ha. The Basin has proven reserves of about 24 000 000 tonnes of coking coal and steaming coal which constitutes about 70 percent of the known coal reserves in Queensland. Large scale open cut coal mining in the Bowen Basin commenced at Moura in 1959. There are now 16 open cut mines operating in the Basin and they collectively mine through about 3000 ha of land each year. Most of the land which has been mined has previously been used for extensive grazing. No mining has yet taken place on cropping land although coal reserves underlie land which has been cropped or has potential for cropping. The primary objectives of almost all of the mining companies operating in the Bowen Basin are to rehabilitate mined land to a stable and productive form which is compatible with surrounding land use which is dominantly grazing. The acceptability of these objectives is considered against the prospect of mining of cropping land and the qualified success of the return of rehabilitated land to grazing uses.

Jan 1, 1987

By Juan Eduardo Barrera

SUNNARY AND CONCLUSIONS Argentina presents to the foreign and local investors a mineral wealth that is largely unexplored, untested, underdeveloped and therefore incompletely evaluated. In view of the above, the new administration of President Raul Alfonsin through its Department of nines has designed and implemented a strategy ( Plan de Expansión Ninera P.E.M.), whose main objective aims at improving the "investment climate" in the sector. It is the Government's basic intention to apply the Mining Promotion Law with responsibility but with generosity to encourage the attraction of investment (local and foreign) to the sector. The establishment of a Data Bank system to evaluate possible new potential ore mining developments will help to connect the owners of potential projects with investors outside the sector. Argentina has an interesting gold ore potential. Estimated reserves of individual projects already known amount to almost 300 tonnes of gold for potential production. The government strongly believes and present information indicates that more systematic exploration has to be undertaken in the Jurassic areas that almost cover the whole of Patagonia. Two recent gold discoveries (Angela in the Chubut province, and Cerro Vanguardia in Santa Cruz province) indicate the potential of this area.

Jan 1, 1988

By Chris Pritchard

Falconbridge Ltd., a major base metal producer in the Sudbury Basin of Ontario, Canada, identified a need to find a safe and cost effective replacement for welded-wire mesh used to support loose ground during underground nickel mining. Safer and lower operating costs are a must to maintain mine viability in lower base metal price environments. Stringent material strength parameters were put in place to determine if a spray-on liner was acceptable for testing and application trials. Falconbridge Ltd. took a methodical approach to the concept of a spray-on liner as a screen replacement proving the strength characteristics of the liner as a safe, cost effective, and suitable method of supporting ground. Materials testing was undertaken at Laurentian University to further understand the capacity of the material Laboratory and field tests indicated excellent adhesion and good tensile strength. Further, it maintains significant tensile strength even after elongation of over 25%. Compact, hydraulic mixing and spraying equipment have been developed and successfully utilized in the Fraser Mine of Falconbridge's Sudbury Operations Currently the Tekflex material has been approved as a wire-mesh replacement and is undergoing full-scale production trials in selected locations at Fraser Mine.

Jan 1, 1999

By K R. Sharpe, A Davitt

CXA is currently evaluating, in co-operation with Inco Metals, a new idea in small diameter hole blasting - the Unidelay Nonel initiation system. In concept, the Unidelay system is a hybrid of the conventional multi-period Nonel system and the safety fuse assembly/igniter cord system. It combines the operational advantages of the latter, simplicity and flexibility, with those of the former, safety and compatibility with all commercial explosives.

Jan 1, 1982

By Michael Epstein, Daniel E. Rosner

Fume nucleation sufficiently close to vaporizing suvfaces can augment net vaporization rates into cooler environments. Environmental conditions favoring large vaporization rate enhancements are briefly discussed and a previous theoretical treatment of this nucleation phenomenon is generalized to account for the self-regulating effect of condensalion-heat release within the boundary layer. Despite kinetic limitations on homogeneous nucleation, and latent heat release, non-diffusive condensate removal processes appear to make possible large enhancements in steady-state vaporization rates, provided surface temperatures are well below the boiling point. When condensed phases vaporize (or dissolve) into cooler media, the diffusion-limited mass loss rate can be strongly influenced by the process of nucleation/con-densation (or precipitation) within the thermal boundary layer. This condensation process (which typically leads to mists or fumes in the case of evaporation into cooler gases) has the effect of steepening the vapor pressure profiles near the evaporating surface, since the condensation zone acts as a vapor sink. However. the resulting enhancement in the diffusion-limited evaporation rate can be estimated (as first done by Turkdogan1 for the case of molten iron/nickel alloys evaporating into helium) only if one has independent knowledge of the critical supersaturation, sCrit(T), required to homogeneously nucleate the vapor.* In a recent reformulation and generalization of the theoretical model of Ref. 1 it has been shown that, when log sCrit is approximately linear in reciprocal temperature, rather simple expressions can be derived4 for the ratio of the actual rate of vaporization j" to either the minimum (no condensation) rate j"min, or the maximum (equilibrium condensation) rate j"max In the present communication we wish to briefly report on further developments and implications of the formulation of Ref. 4, with emphasis on i) environmental conditions favoring large enhancements in vaporization rate, and ii) the self-regulatory influence of condensation heat release (neglected in Refs. 1 to 4) on predicted vaporization rates. Additionally, we take this opportunity to correct several misprints appear- ing in Ref. 4, and comment on Elenbaas's recent criticism5 of Ref. 1. MAXIMUM POSSIBLE VAPORIZATION RATE IN PRESENCE OF CONDENSATION A nonequilibrium theory is of interest because of the very large difference between the minimum (no condensation) and maximum (equilibrium condensation) vaporization rate. The magnitude of this maximum possible enhancement can be shown quite clearly by combining a result of Refs. 3 and 4 with the fact that for most liquids there is a simple relationship between the molar heat of evaporation, A, and its boiling point, i.e., A/(RTBp) = C, where the constant C, often called the Trouton ratio, takes on values not very different from 11.* More generally, for any substance (including The Trouton ratio (which for water is 13, for methane, 10, and so forth) will be recognized as the ratio of the molar entropy change upon vaporization (at TBP or Ttransf) to the unlversal gas constant R. Its near constancy reflects the fact that the change in atomic order upon vaporization depends only weakly on the kinds of molecules involved. those that sublime under ordinary conditions) we can define a characteristic transformation temperature. Ttransf, by a relation of the form Ttransf =A/(CR), and then examine the maximum possible evaporation rates as a function of how far removed from Ttransf are the surface temperature, Tw, and ambient temperature, T. Subject to the assumptions: 1) equilibrium vapor pressure, pv,eq, everywhere small compared to prevailing total pressure, p, and 2) negligible effect of condensation heat on temperature profile, the maximum enhancement ratio was found (Eq. [17], Ref. 4) to be: where, for most vapors, Nu/NuD (the ratio of heat transfer coefficient to mass transfer coefficient for the same configuration) is a number near unity.* Ex- *An alternative derivation of the Nu = NuD special case of this equation. revealing its validity for arbitrary velocity/temperature profiles in a laminar boundary layer, is given in Ref. 3. amining this result for a "Trouton substance", one obtains the results shown in Fig. 1, constructed for C = 11. Since we are concerned with vaporization enhancements (j'max/J"min > 1) at surface temperatures below Ttransf, this area of interest is shown unshaded. One notes that at a fixed ambient temperature (hence, T/TtranSf) there is a unique surface temperature, 2T , at which j"max/j"min attains its peak value; moreover, the peak enhancement ratio, see dashed locus. Fig. 1, is: (NuA/NuD)(C/4)(Ttransf/T,). Hence, if Nu = NuD, when the ambient temperature is less than 1/4 of TtranSf the peak enhancement exceeds the Trouton

Jan 1, 1969

By Honggang Zhong, Tan Yi, Qijie Zhai, Zhao Dan, Xinping Mao, Huigai Li

"The influence of superheat degree on the distribution and volume content of inclusions were studied in 65Mn thin slab produced by compact strip production(CSP) in Zhujiang Steel in China, The results showed that the diameters of inclusions are mainly less than 5µm. Most of the inclusions gathered at the 1/4 thickness direction for the thin slab of 27? superheat degree, compared with the center position for that of 37?. There are more inclusions larger than 50µm in the low superheat samples, which is caused by the short floating time. In addition, the inclusions were observed and analyzed by metallurgical microscope, SEM and EDS in order to ensure their composition, type and further find their source. It was find that the types of these inclusions mainly are Al2O3, SiO2,CaO and their composites, a few of them are TiN and MnS.IntroductionIt is well known that inclusions have a great impact on the strength, plasticity, fracture toughness, cutting performance, fatigue property and corrosion resistance of steels. Especially, with the demand for thinner slab, the cleanness is increasingly becoming more significant as a quality criterion[1]. High manganese and carbon steels not only demonstrate high strength but also proper plasticity. There are many problems unsolved for 65Mn steel as a result of the low solidification rate, bad thermal strength, crack sensitivity and low casting temperature[2,3].The superheat of the molten steel has a great impact on the erosion of refractory lining, molten steel fluidity and non-metallic inclusion behavior[4]. The serious erosion situation of ladle lining, nozzle and casting tundish will give rise to more inclusions at a high superheat. Meantime higher superheat will make second dendrite arm spacing coursing and element segregation which lead to inclusion, bubble formation and shrinkage cavity. On the contrary, it is hard for non-metallic inclusions to float up with a low superheat value. Inclusions of 65Mn steel, which produced in different superheat condition by CSP, were studied for the sake of higher slab properties including statistics and EDS analysis."

Jan 1, 2012

By Wills BA, Barley RW

A brief description of viscosity measuring devices used in Dense Media Separation (DMS) plants is given, including a new On-line viscometer system. The various factors which affect suspension viscosity are identified. The effect of temperature variation on viscosity and viscosity measurement is examined in detail. Practical problems in using a modified Stormer viscometer for laboratory testwork are noted. Likely problems of continuous viscosity measurements are also discussed.

Jan 1, 1987

By B. Ramanathan

The results of a pile load test on a 1200 mm dia and 25 m long bored Cast-in-situ pile in soft rock is reported. The subsoil has a high N value of above 60 from 7 m to 21 m. The soft rock was observed below 21 m and N value exceeded 100. The theoretical calculations showed that the safe carrying capacity will be about 410 t. But the actual load test on the pile indicated that the allowable load is only about 140 t. This is attributed to the fact that the soil is cemented and loses strength due to remoulding caused by pile installation. It is concluded that great care should be exercised in determining the carrying capacity of piles in cemented soils and soft rocks and that 'N' value alone should not be used.

Jan 1, 1996

By W. P. Sykes

IN an earlier paper1 the composition-temperature limits of the gamma iron phase in the iron-tungsten system were reported as approximated Fig. I.-DIAGRAM OF ALPHA-GAMMA LOOP AS DETERMINED BY MICROSTRUCTURE AND THERMAL ANALYSIS. by thermal analyses. At that time no attempt was made to develop metallographic evidence of the coexistence of two phases in the iron-rich solid solution at temperatures between 900° C. and 1400° C.

Jan 1, 1931

By Francis R. Conley, John A. Sievert, John N. Dew

A brief review is presented of the past performance of a number of large, thin, highly permeable reservoirs with low dips in the Bolivar Coastal fields of Venezuela. The performance of these reservoirs indicates that the fluids are segregated vertically within the sand section by gravity. With this assumption, equations are developed which describe the performance under pressure maintenance operations. Methods of solving these equations and results of simple example calculations are presented. Example calculations indicate that under pressure maintenance conditions injected gas tends to {tow preferentially along the top of the sands and that encroaching water has a tendency to flow preferentially along the bottom. The expected performance of segregated fluids is discussed and compared with that of fluids which are uniformly distributed in any sand section. INTRODUCTION The field performance of a number of reservoirs described herein indicates that the fluids are segregated vertically within the sand section by the force of gravity. Thus, it was felt that any method used to predict the future performance of these reservoirs should consider the effects of segregation in the sand sections. A study of the available information on some of the reservoirs suggests that increased recoveries may be expected if the reservoir pressure is maintained by either crestal gas injection or flank water injection. To predict future performance of reservoirs under pressure maintenance operations, a method of analysis was needed which would account for segregation of fluids in the sand sections. Several methods of analysis have been developed to take into account the segregation of fluids in the reservoir as a whole1,3 To our knowledge no method considers segregation of the fluids within sand sections in the manner indicated by the past performance of several reservoirs in the Mara-caibo Basin. This paper outlines part of the work done in studying some of these reservoirs and contains a description of their performance characteristics. The analysis presented is restricted to pressure maintenance conditions, since space limitations prevent a full discus- sion of the development of the mathematical relations and the various methods of solving them. Only a sketch of the development of the mathematical relations is given. The various methods of solving these relations are pointed out, but the actual determination of solutions to various problems are omitted except for one example. It is felt that these results may aid in the study of reservoirs outside the Maracaibo Basin. Some concepts on which the present analysis is based are outlined by D. N. Dietz. However, the analysis presented herein includes several factors not considered by Dietz: (1) variations in permeability and in the cross section, (2) various shapes of the cross section, and (3) the production of fluids. Also, the mathematical development presented by Dietz differs considerably from our corresponding analysis. RESERVOIR CHARACTERISTICS The reservoirs under consideration, large and thin, with low dip and high permeability, are large to the extent that they contain from 0.5 to over four billion bbl of oil initially in place. The section thicknesses vary from 100 to 400 ft and the lengths from 10,000 to 40,000 ft. Thus, a length-wise cross section of the producing formation appears to be long and thin. The dip angles vary from 0 to 6 degrees and the average permeabilities vary from 0.5 to over three darcies. The reservoirs contain from 20 to 50 per cent shale inter-laminated with the productive sands. Most shale breaks within the major sands do not correlate from one well to the next, and correlation is often difficult, even between wells drilled from the same location. However, it is often possible to correlate the shale breaks between major sands for some distance. Herein we are concerned with the performance of reservoirs containing oil of gravities over 20" API. Past reservoir performance indicates good pressure communication and, in cases where pressure sinks have developed, large amounts of fluid migration have occurred. Few of the reservoirs have had initial gas caps, but also, few have been found to be highly under-saturated. Due to gravity segregation, secondary gas caps usually form before the pressure has been reduced more than 25 per cent of its initial value. The effect of gravity has not only been apparent on a reservoir-wide basis, but has also caused segregation of the reservoir fluids in productive sections. Proof of this is found from the results of selective well tests, workovers, and electric and various other types of logs. Evidence that

A study of the electrolysis of PbS in molten PbCl2 showed cathode efficiencies which increased with current density at fixed sulphide concentrations, and decreased with increasing sulphide concentration at fixed current densities. The anodically produced sulphur dissolved rapidly in the melt, the rate increasing with temperature and sulphide concentration. Experiments with diaphragm cells, made to determine the relative effects that dissolution of lead and sulphur have on the cathodic current efficiency, demonstrated that dissolution of sulphur was the major contributor to the lowering in efficiency.

Jan 1, 1973