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By Charles H. Fulton

ONE of the events of note in mineral industry education circles during the year was the summer school for engineering teachers, devoted to mining and metallurgical engineering, which was conducted by the Society for the Promotion of Engineering Education in co¬operation with the University of Wisconsin. It was in charge of Prof. Harry P. Hammond, director of the summer school, and Prof. Richard S. McCaffery of the University of Wisconsin. It was attended by 63 people, and practically every educational institution offering mineral industry courses had representatives present. The session was successful and those in attendance spoke highly of the pro¬gram and results obtained. The Mineral Industry Education Division cooperated with the S.P.E.E. in this project. Prof. Hammond will discuss the purpose and results of this session at the February meeting.

Jan 1, 1934

By Spencer Ness, Yazen Khasawneh, William Tjaden, Mohammad Nassim

The evaluation of long-term performance of the wind turbine structures is essential in lowering the Levelized Cost of Electricity (LCOE) from wind sources. The required maintenance of the wind turbine foundation during the design-life time of the wind turbine may result in escalated cost, if not properly evaluated during the planning and designing phases. The degradation of the foundation soils’ stiffness due to the accumulation small plastic strains resulting from normal and/or extreme operating cyclic loading may result in escalating the O&M cost. The foundation’s stiffness degradation will result in a shift of the wind turbine system natural frequency, which may result in amplifying the vibrations generated at the hub. The anticipated shift of the wind turbine system natural frequency during the design-life time should be investigated through numerical simulations of the anticipated dynamic loading utilizing soil constitutive models that are capable of capturing the foundation stiffness degradation due to the accumulation of such small plastic strains. This study presents the validation of an element model that will be used to evaluate the performance of existing and/or proposed constitutive model.

Oct 1, 2022

By Benoit DeBecker

Laboratory-scale experiments have shown that chromium metal could be recovered from chromate wastes by modifying slightly the chromium electrowinning flow-sheet. After reduction by sulhr dioxide and precipitation of chromic hydroxide, the solid residue is dissolved in the chrome alum solution and the metallic impurities are removed by cementation on manganese. The presence of dissolved manganese in the electrolyte does not affect the cathodic deposition of chromium and it eliminates the anodic production of Cr(V1).

Jan 1, 1994

By J. Frenzel

The computation of hydrometallurgical equilibria is very difficult because of the many complex species in solution, the precipitates, condensed species, or solids, and the activity coefficient corrections necessary to non-ideal thermodynamics. Our objective was to tryout recently developed genetic algorithms to minimize free energy and solve the equilibrium computation. We selected test problems that were seemingly unsolvable with more traditional algorithms, and we applied genetic algorithms to them. We were pleased to find that genetic algorithms succeeded where other algorithms did not. We concluded that they are an effective tool for hydrometallurgical equilibria.

Jan 1, 1992

By H. J. Modi, D. W. Fuerstenau

pH effectively regulates the flotation of corundum through its control of the surface charge. Since collector ions function as counter ions in the double layer, the collector must be anionic when corundum is positively charged and cationic when it is negatively charged. Even a long-chained xanthate will float positively charged corundum. Association of the hydrocarbon chains of the adsorbed collector ions gives rise to increased adsorption and increased rate of flotation. Because of this phenomenon, neutral organic molecules aid flotation although the unionized collector cannot promote flotation independently. Na2SO4 was found to depress the flotation of corundum with animic collectors through ionic competition whereas the same salt activates corundum for flotation with cationic collectors. A close connection between ion association, electrokinetic behavior, and floatability is suggested. As part of the increasing interest in the physical chemistry of flotation, strong experimental evidence has been obtained which indicates that organic ions are adsorbed as counter ions by non-metallic oxide minerals mainly because of the electrical forces which exist at interfaces(1-3). Thus flotation of such minerals without activation should then be appreciable only when the mineral and the collector are oppositely charged. Since only limited work has been reported on the effect of surface charge upon flotation behavior(3) this general hypothesis on the flotation of insoluble oxide minerals has not been tested thoroughly. Investigating the flotation of a mineral for which extensive electrokinetic data exist yields a way to test this hypothesis more extensively. The electrokinetic behavior of corundum in solutions containing both organic and inorganic electrolytes has been studied quite thoroughly' Electro-kinetic measurements have shown that in the case of corundum, simply by controlling pH the solid surface can be charged either positively or negatively. For this reason corundum was chosen for study. The object of this paper is to present a study of the flotation of corundum and to explain the results in the light of our knowledge of adsorption mechanisms gained from streaming potential investigations. This paper is concerned mainly with the effect of surface charge on flotation with anionic and cationic collectors, but in addition such flotation phenomena as collector hydrolysis, Van der Waals attraction between hydrocarbon chains, ionic competition, and activation are discussed. While the present paper is confined to a reporting of the data obtained and some of the more immediate conclusions, it will be seen that the results, in combination with those on other systems, do promise a

Jan 1, 1961

By W. G. Hatch

Introduction Classified equipment originally installed in 1923 in the Britannia mill consisted of eighteen Model C Dorr Simplex classifiers, each in closed circuit with a pebble-mill. These machines were only three feet wide and of light construction, so that their raking capacities were necessarily limited, the maximum being about 20 tons per hour for each classifier. On conversion from pebble-mills to ball-mills, in 1924, attempts to increase circulating loads with higher rake speeds resulted only in overflowing a coarser product to the flotation cells. The elevator type of classifier was developed locally in 1935 and during that year two units, each having a sand carrying capacity of from 30 to 40 tons per hour, were installed. With such loads, a material increase in the grinding capacities of the ball-mills was noticed, and, after further development work on the elevator classifier, fifteen of the small Dorr classifiers were replaced by units of this type, capable of handling approximately 75 tons of sand per hour, with later alterations increasing this capacity to well over 100 tons per hour. In the meantime, the three remaining ball-mills had been placed in circuit with Dorr FX classifiers, one of which was six feet wide and the others five feet wide. Impartial and exhaustive tests conducted on the Dorr FX versus the elevator classifier showed the average results on these machines at Britannia to be substantially the same. A large amount of testing was carried on to determine the effect of circulating load on the output of the grinding units. This work indicated a rapid increase in the grinding rate as the ball-mill feed increased up to about 60 tons per hour, after which a relatively slow increase took place up to 100 tons per hour. No benefits were derived from higher circulating loads. A 300 to 500 per cent circulating load, depending on the nature of the ore treated, is considered to be within the economical range for the grinding of Britannia ores.

Jan 1, 1946

By R. Venugopal, T. C. Rao, N. Suresh

Experiments were carried out using the cyclone to treat coal in the size range -2.0+0 mm. The diameters of the cyclone outlets (vortex finder and spigot) were varied to study their effects on cyclone performance. The cyclone products were deslimed over a screen with an aperture of 0.075 mm. The performance of the separator was studied for washing coarse coal (-2.0+0.075 mm) and fines (-0.075 mm). Performance curves were plotted for the separation of -2.0+0.075 mm coal. The concept of a generalised distribution curve was adopted to predict cyclone performance. A mathematical representation was derived from the generalised distribution curve. The specific gravity of separation for individual size fractions showed a decreasing trend with decreasing particle size down to 0.85 mm, beyond which a reverse trend was noted. It was also found that the fine size fraction (-0.075 mm) does not separate on the basis of size or specific gravity but follows the water distribution

Apr 1, 1995

By C. J. Cohen, L. A. Dahners

"SUMMARYA method has been developed for surveying, drill holes without lowering into the hole any surveying equipment other than an etch tube. The orientation of the rods at the collar of the hole is maintained as the etch tube is lowered. The attitude of the etch ellipse in depth with respect to the rod orientation at the collar can then be observed. This relationship permits the bearing of the hole in depth to he calculated. The rod orientation is maintained during the lowering by means of a pair of alinement clamps. One clamp is fastened to the top of each rod as the rod is coupled and is removed when the alinement has been transferred to the other clamp at the top of the next succeeding rod. A particular advantage of this survey technique is that surveys can be readily made in magnetic country rock.PRINCIPLE OF THE TECHNIQUEAn axial lamina of the column of drill roes is the lamina in which one fiber would be the centerline of the rods. In the new survey technique, the rods are fed into the hole in such a manner that the axial lamina of each successive rod maintains its position at the collar of the hole. In depth, as the rods bend in following the drill hole, the axial laminae also bend. The lamina that was originally vertical will, in general, be tilted away from the vertical. The trace of this lamina is marked on the glass etch tube before the tube is lowered in the hole. The axial lamina that becomes vertical at the survey station is recognized as that axial lamina which contains the long axis of the etch ellipse. The angle between the lamina originally vertical and the lamina vertical at the survey station is thus measurable. When the vertical axial lamina at one survey station has been determined by the etch ellipse at that station, angle R between this lamina and the vertical axial lamina at the next survey station becomes measurable also. By moans of angle R, and dip angles D1 and D2 at the two stations, the change in bearing (z) of the drill hole between the two stations can be calculated."

Aug 1, 1944

By Walter Fuchs

It is now generally conceded that coal is the product of deposition and transformation of debris of forests and swamps.29 Ample data are available to illustrate the metamorphosis of biochemical substances through biological action; other data show the progressive regional metamorphism existing in coal beds;25 and numerous examples of change effected by intrusion of igneous dikes into coal deposits have been established.23 However, often the relative importance of the biological and the geological factor in determining the character of the various natural coals is a debatable question. Since both biological and geological factors are ever present in nature, the problem, at first glance, would appear to resemble certain probability problems: specifically the simultaneous toss of two coins, with the biological factor as heads and the geological as tails. The probability is 2:I for the combined effect of both factors, as compared to the exclusive effect of either one, if the a priori probability is the same for each factor. This condition can be analyzed by a thermodynamic treatment of data, which may be obtained from a consideration of pertinent biological, chemical, geophysical and geological facts. Synopsis of Biological and Chemical Facts The biosphere is not sterile; i.e., microorganisms are always present. Microor- ganisms have been established in the ocean deep, under the ice of the polar regions, in the sand of the deserts, and in swamps far below the surface. The various biological media may be acid, neutral, or alkaline, and they may or may not be readily accessible to air. Microorganisms are encountered almost everywhere, except where the temperature is not within the range tolerable by microbial life. Of course, with changing conditions, the type of microorganisms will change. All chemical products of life—proteins, fats, carbohydrates, lignins, waxes, resins— may serve as a habitat of microorganisms. In the decomposition of a medium, some microorganisms macerate organic matter mechanically and remove certain constituents for their own nutrition; others decompose a large part of the organic matter but may leave certain constituents undecomposed. Some attack only certain specific ingredients of the organic matter. All of them build up cell substance. The nitrogen content of the medium largely determines the degree of decomposition. Below 1.7 per cent nitrogen, growth of microorganisms and hence decomposition of organic material is retarded; consequently organic material will accumulate.17,32 Such accumulations of organic material may give coal eventually. Coals differ in type and rank. The nature of the original vegetation and the conditions attending the transformation of the accumulated debris determine the type of coal such as bright, splint, cannel, and algal or boghead coals. Chemical analysis of representative samples of a given type of

Jan 1, 1942

By Walter Fuchs

IT is now generally conceded that coal is the product of deposition and transformation of debris of forests and swamps.29 Ample data are available to illustrate the metamorphosis of biochemical substances through biological action; other data show the progressive regional metamorphism existing in coal beds;25 and numerous examples of change effected by intrusion of igneous dikes into coal deposits have been established .R3 However, often the relative importance of the biological and the geological factor in determining the character of the various natural coals is a debatable question. Since both biological and geological factors are ever present in nature, the problem, at first glance, would appear to resemble certain probability problems: specifically the simultaneous toss of two coins, with the biological factor as heads and the geological as tails. The probability is 2:I for the combined effect of both factors, as compared to the exclusive effect of either one, if the a priori probability is the same for each factor. This condition can be analyzed by a thermodynamic treatment of data, which may be obtained from a consideration of pertinent biological, chemical, geophysical and geological facts. SYNOPSIS OF BIOLOGICAL AND CHEMICAL FACTS The biosphere is not sterile; i.e., microorganisms are always present. Microorganisms have been established in the ocean deep, under the ice of the polar regions, in the sand of the deserts, and in swamps far below the surface. The various biological media may be acid, neutral, or alkaline, and they may or may not be readily accessible to air. Microorganisms are encountered almost everywhere, except where the temperature is not within the range tolerable by microbial life. Of course, with changing conditions, the type of microorganisms will change. All chemical products of life-proteins, fats, carbohydrates, lignins, waxes, resinsmay serve as a habitat of microorganisms. In the decomposition of a medium, some microorganisms macerate organic matter mechanically and remove certain constituents for their own nutrition; others decompose a large part of the organic matter but may leave certain constituents undecomposed. Some attack only certain specific ingredients of the organic matter. All of them build up cell substance. The nitrogen content of the medium largely determines the degree of decomposition. Below 1.7 per cent nitrogen, growth of microorganisms and hence decomposition of organic material is retarded; consequently organic material will accumulate.17,32 Such accumulations of organic material may give coal eventually. Coals differ in type and rank. The nature of the original vegetation and the conditions attending the transformation of the accumulated debris determine the type of coal such as bright, splint, cannel, and algal or boghead coals. Chemical analysis of representative samples of a given type of

Jan 1, 1941

By Walter Fuchs

IT is now generally conceded that coal is the product of deposition and transformation of debris of forests and swamps.29 Ample data are available to illustrate the metamorphosis of biochemical substances through biological action; other data show the progressive regional metamorphism existing in coal beds;25 and numerous examples of change effected by intrusion of igneous dikes into coal deposits have been established.23 However, often the relative importance of the biological and the geological factor in determining the character of the various natural coals is a debatable question. Since both biological and geological factors are ever present in nature, the problem, at first glance, would appear to resemble certain probability problems: specifically the simultaneous toss of two coins, with the biological factor as heads and the geological as tails. The probability is 2:I for the combined effect of both factors, as compared to the exclusive effect of either one. if the a priori probability is the same for each factor. This condition can be analyzed by a thermodynamic treatment of data, which may be obtained from a consideration of pertinent biological, chemical, geophysical and geological facts. SYNOPSIS OF BIOLOGICAL AND CHEMICAL FACTS The biosphere is not sterile; i.e., microorganisms are always present. Microorganisms have been established in the ocean deep, under the ice of the polar regions, in the sand of the deserts, and in swamps far below the surface. The various biological media may be acid, neutral, or alkaline, and they may or may not be readily accessible to air. Microorganisms are encountered almost everywhere, except where the temperature is not within the range tolerable by microbial life. Of course, with changing conditions, the type of microorganisms will change. All chemical products of life-proteins, fats, carbohydrates, lignins, waxes, resins may serve as a habitat of microorganisms. In the decomposition of a medium, some microorganisms macerate organic matter mechanically and remove certain constituents for their own nutrition; others decompose a large part of the organic matter but may leave certain constituents undecomposed. Some attack only certain specific ingredients of the organic matter. All of them build up cell substance. The nitrogen content of the medium largely determines the degree of decomposition. Below 1.7 per cent nitrogen, growth of microorganisms and hence decomposition of organic material is retarded; consequently organic material will accumulate. l7,32 Such accumulations of organic material may give coal eventually. Coals differ in type and rank. The nature of the original vegetation and the conditions attending the transformation of the accumulated debris determine the type of coal such as bright, splint, cannel, and algal or boghead coals. Chemical analysis of representative samples of a given type of

Jan 1, 1941

By Walter Fuchs

It is now generally conceded that coal is the product of deposition and transformation of debris of forests and swamps.29 Ample data are available to illustrate the metamorphosis of biochemical substances through biological action; other data show the progressive regional metamorphism existing in coal beds;25 and numerous examples of change effected by intrusion of igneous dikes into coal deposits have been established.23 However, often the relative importance of the biological and the geological factor in determining the character of the various natural coals is a debatable question. Since both biological and geological factors are ever present in nature, the problem, at first glance, would appear to resemble certain probability problems: specifically the simultaneous toss of two coins, with the biological factor as heads and the geological as tails. The probability is 2:I for the combined effect of both factors, as compared to the exclusive effect of either one, if the a priori probability is the same for each factor. This condition can be analyzed by a thermodynamic treatment of data, which may be obtained from a consideration of pertinent biological, chemical, geophysical and geological facts. Synopsis of Biological and Chemical Facts The biosphere is not sterile; i.e., microorganisms are always present. Microor- ganisms have been established in the ocean deep, under the ice of the polar regions, in the sand of the deserts, and in swamps far below the surface. The various biological media may be acid, neutral, or alkaline, and they may or may not be readily accessible to air. Microorganisms are encountered almost everywhere, except where the temperature is not within the range tolerable by microbial life. Of course, with changing conditions, the type of microorganisms will change. All chemical products of life—proteins, fats, carbohydrates, lignins, waxes, resins— may serve as a habitat of microorganisms. In the decomposition of a medium, some microorganisms macerate organic matter mechanically and remove certain constituents for their own nutrition; others decompose a large part of the organic matter but may leave certain constituents undecomposed. Some attack only certain specific ingredients of the organic matter. All of them build up cell substance. The nitrogen content of the medium largely determines the degree of decomposition. Below 1.7 per cent nitrogen, growth of microorganisms and hence decomposition of organic material is retarded; consequently organic material will accumulate.17,32 Such accumulations of organic material may give coal eventually. Coals differ in type and rank. The nature of the original vegetation and the conditions attending the transformation of the accumulated debris determine the type of coal such as bright, splint, cannel, and algal or boghead coals. Chemical analysis of representative samples of a given type of

Jan 1, 1942

By A. B. Dyes

In the operation of a water-driven reservoir, a free gas saturation can he established by maintaining production rates fast enough to cause the reservoir pressure to decline below the bubble point. The benefit of such a procedure on the displacement efficiency of the oil by water is illustrated for two types of sandstone samples from one reservoir. Those rock samples showing the poorest recovery to water drive in the absence of a free gas saturation give the most improvement in the presence of a free gas saturation. Employing one type of reservoir fluid (low .shrinkage) the benefit of evolved gas on oil displacement is calculated at several reservoir pressures below the bubble point. This demonstrates the presence of air optimum pressure for water displace,rnent which is .several hundred pounds per .square inch below the bubble point. Displacement of oil at the optimum pressures results in the removal of 7 to I? per cent more oil than would be obtained by displacement at the bubble point pressure. In some instance. this magnitude of increase may be worthy of consideration in establishing the maximum efficient rate of production from many water-driven fields. INTRODUCTION For many years the belief that the use of gas could be combined with that of water to result in a better recovery operation than the use of either of these phases alone has been prevalent in the oil industry. This is evidenced by the several field trials which have employed the injection of gas and water in combination.1.2.v In most cases the small amount of any additional recovery, in combination with the limited knowledge available on the older reservoirs, has left uncertain the influence of gas on recovery in these earlier attempts to combine the use of gas with water. Research studies in recent years have demonstrated through laboratory. floods the magnitude of the benefit of the presence of gas on the displacement of oil from sandstones by water.5,6,7,8,9,10,11 In addition, studies of the distributions of the phases which are present during the displacement process have developed concepts concerning the mechanism by which this benefit is obtained."." It now remains for the engineer to incorporate these findings into the general technology of reservoir operations. It is the purpose of this paper to illustrate that the production of a water-driven reservoir at pressures below the bubble point is one such operation whereby improved oil displacement efficiency can be obtained as a result of gas evolution. The establishment of a gas saturation by evolution of dissolved gas was one of the techniques used by several investigators in the laboratory studies. The possibility of obtaining the benefit of gas evolution in water-driven reservoirs by producing at pressures less than the bubble point has 3150 been pointed out previously." The desirability of this operation has undoubtedly

Jan 1, 1955

By G. Whitney, J. Steiner

Introduction The Summitville Mine located in southwestern Colorado is an example of the potential impact that natural weathering and mining activities can have on environmental quality. Acid rock drainage and metals leaching from active and historic mine districts are a major environmental problem facing the mining industry today. Sulfide ore exposed naturally or during mining operations has the potential to produce leachates that contain high concentrations of dissolved metals. These leachates can affect the quality of plant and animal health in surface water used for agriculture, recreation and human consumption. Pintail Systems has developed biological processes for detoxification of cyanide in heap-leached spent ore and process solutions. During application of spent ore cyanide bio-detox processes we have also observed a substantial reduction in many of the leachable metals in biotreatment solutions. These field observations of soluble metal reduction led us to propose that metal bio-mineralization should be a secondary treatment goal of spent ore detox in Focused Feasibility Studies (FFS) for the Summitville Mine. In the FFS (described in a companion paper) for Summitville, spent ore from the heap leach pile (HLP) was loaded into PVC test columns (six inch X ten foot) and was leached with bacteria/nutrient solutions. Two treatment designs were studied: a standard percolation leach (aerobic) and a saturated leach design where the ore was saturated with the heap leach solution to which bacteria and nutrients were applied in a continuous biotreat leach. The bacteria for all column treatment tests were isolated from the spent ore at depth through the Heap Leach Pile (HLP) in the saturated and unsaturated zones. Bacteria isolated from the heap material were tested for cyanide oxidation capacity and were submitted to a bioaugmentation program to improve reaction kinetics and metals tolerance. The final treatment population consisted of several distinct species including aerobic heterotrophs, facultative anaerobes and sulfate-reducing bacteria. The remineralization of soluble metals was observed through a decrease in copper in column leachate solutions and the formation of observable mineral products on ore surfaces in the columns. Several of the tests were run in clear PVC columns to facilitate observation of mineral formation. The column ore contents were photographed before, during and after the biotreatment process which ranged from 10 to 20 days for each test column. Ores were collected from each column after the treatment was complete and were submitted for SEM and TEM study at two laboratories - the USGS SEM Laboratory in Denver, Colorado and the City College of New York SEM laboratory. Treatment Process Description Numerous species of bacteria, fungi and yeasts are capable of accumulating many times their weight in soluble metals. Both living and dead biomass are effective in removing soluble metals from waste streams containing gold, silver, chromium, cadmium, copper, lead, zinc, cobalt and others. Soluble metals may also be immobilized in soils by natural or engineered biomineralization reactions. Several commercial processes using biological reactions are being applied on an industrial scale for metal remediation. Bacteria found in natural and extreme environments have developed a wide variety of metabolic functions to adapt to these environments. These natural microbial functions contribute to global mineral cycling that continuously forms, transforms and degrades minerals and metals in the environment. Biomineralization is described as a surface process associated with microorganism cell walls where the remineralization occurs. The biogeochemical activities initiated by microorganisms in ores, soils, surface and groundwater environments can dominate the formation and transformation of those mineral environments.

Jan 1, 1995

By Griffiths J. B

From its mining lease at the northern end of Cohens Reef at Walhalla in the North Gippsland Mountains, the Long Tunnel Extended Gold Mining Company produced 13,695 kg of gold, which at 1980 prices represents a value significantly in excess of $200 million. In the period 1885 to 1908 the mine was one of Australia's principal reef gold producers, being top Victorian producer in six of these twenty-four years. Prior and subsequent occupants of the lease produced an additional 160 kg of gold. The Extended and the other mines on Cohens Reef whilst contributing importantly to the financial resource of Victoria, were the sole important support for the substantial town of Walhalla that had grown up around them. When the mines closed, Walhalla gradually reduced from a bustling developed town to the present attractive mountain village so favoured by tuurriSts. To allow the visitor to obtain a better ;ri.icrstanding of Walhalla's mining past, important parts of the Long Tunnel Extended Gold Mine workings and site are being

Jan 1, 1981

By Masaki Kitazume

"Abstract The wet type and dry type of deep mixing methods have been developed and widely applied for on-land and marine constructions in Japan. The quality assurance (QA) of the methods has been usually carried out by unconfined compression test on field stabilized soil sampled by core boring in Japan. In some other countries, stabilized soil excavated by the wet grab sampling instead of core sampling is often subjected to unconfined compression test for quality assurance. There are several merits and demerits in each method, but few studies have been carried out to compare the stabilized soil strength of these two types of specimens to discuss their applicability to practical construction. The author has conducted a series of field and laboratory tests to compare the stabilized soil strength and discuss the applicability of wet grab sampling to QA for wet and dry types of deep mixing method.In this study, the wet grab sampling was carried out at two road embankment construction sites where the wet type and dry type of deep mixing were applied. The cement stabilized soil was excavated at the three depths by a wet grab sampler soon after the DM column construction. The test result is compared with the other test data in the previous study to discuss the applicability of the web grab sampling method for QA of cement stabilized soil.IntroductionThe Deep Mixing Method (DMM), an in-situ soil stabilization technique using cement and/or lime as a binder, is often employed to improve soft soils (Kitazume and Terashi, 2013). A variety of factors and their interactions affect the eventual strength of a deep-mixed column, while some of which are controllable (e.g. binder type and dose) by engineers while the others are not (e.g. soil types, ground temperature, etc.; Babasaki et al., 1997). In addition to laboratory mix tests, which in essence are a parametric study to estimate the influence of these factors on a particular soil’s strength, the quality assurance (QA) practice in Japan usually involves unconfined compression test on sampling cores from the stabilized columns after a given curing period. It has been recognized, however, that the ‘field strength’, or the strength of the retrieved core, quf is on average lower than the ‘laboratory strength’, qul, evaluated by laboratory mix test. Also allowing for the inevitable variability, existing guidelines (for example, PWRC, 2004 and CDIT, 2008) recommend the design quf /qul values of, for example, 0.5-1.0 for the CDM (Cement Deep Mixing; a wet-type technique, in which binder is added as slurry) and 0.2-0.33 for the DJM (Dry Jet Mixing; a dry-type technique, in which binder is added as powder)."

Jan 1, 2014

By M. Zhang, H. Ni, F. Zheng, M. Guo

"In the present work, we investigate the effects of roasting temperature and time on the transformation of the titanium (Ti)-bearing phase and magnesium aluminate spinel (MgAl2O4) phase in Ti-bearing electric arc furnace molten slag during the molten sodium hydroxide (NaOH) treatment process. With applied temperature of 700 °C for 60 min, and a mass ratio of Ti-bearing electric arc furnace slag to NaOH, or Rslag/NaOH, of 1:1.2, the conversion ratios of the Ti-bearing phase and the MgAl2O4 phase reached about 98.3 percent and 88.1 percent, respectively. Moreover, investigation of the reaction kinetics indicate that the conversion of these phases during the molten NaOH treatment process is a typical solid-liquid reaction, and it can be theoretically described by the unreacted shrinking core model. The conversion ratio of the Ti-bearing phase was found to be controlled by the chemical reaction step, with an apparent activation energy of 41.76 kJ/mol. The decomposition of the MgAl2O4 phase was found to be controlled by the surface chemical reaction in the early stage of 0 to 20 min from start of reaction, changing to diffusion control in the later stage of 20 to 60 min. The apparent activation energies of the process were determined as 55.88 and 22.72 kJ/mol, respectively.IntroductionChina has rich mineral resources of vanadium–titanium magnetite ore deposits, and the iron and steel industry in the country produces millions of tons of titanium (Ti)-bearing slag every year. The problem of how to dispose of the Ti-bearing slag has attracted much attention, and various approaches have been developed, including the acid process (Li et al., 2007; Zhang et al., 2011; Zhang and Nicol, 2010; Li et al., 2011), alkali fusion process (Han et al., 2012; Middlemas, Fang and Fan, 2013; Nayl, Awwad and Aly, 2009; Lasheen, 2008; Zhang, Qi and Zhang, 2009), carbonization and chlorination process (Liu et al., 2008; Tao et al., 2012; Fu et al., 2012; Liu, 2009), selective crystallization process (Lei and Xue, 2008; Li et al., 2011; Zhang et al., 2007a, 2007b). However, these processes have been beset by various functional, economical and ecological problems (Yu and Chen, 2010). With environmental protection regulations becoming increasingly rigorous, and demand growing for the comprehensive utilization of resources, the focus is on methods to treat Ti-bearing slag with high efficiency and mild reaction conditions (Nazari and Riahi, 2011; Wu et al., 2013)."

Jan 1, 2017

By Pedro S. Zúñiga S.

El presente trabajo señala la optimización de los parámetros de perforación en el yacimiento minero de Cuajone a través del control de presión hidráulica y velocidad rotacional en la operación de máquinas de acuerdo a las formaciones geológicas consideradas. En este sentido, se busca mejorar el rendimiento respecto al desgaste de brocas y conservación de la máquina perforadora.

Oct 14, 1980

By J. Ambrose, R. W. Zimmerman

"Shales are highly anisotropic in their mechanical behavior. The strength ( ??1) of anisotropic shales depends not only on the magnitude of the other two principal stresses ( ??2, ??3), but also on the bedding plane orientations (?) relative to the principal stresses. In this study, the role of the intermediate stress ( ??2) on the strength of shale is evaluated using new data from triaxial compression and extension tests. To understand the failure behavior of shales, we have carried out triaxial compression tests ( ??1 > ??2 = ??3) on two organic rich mudstones, at different confining stresses and loading angles. We first fit the triaxial compression data with Jaeger’s plane-of-weakness model, and find that the model is able to represent the strength behavior of anisotropic shales reasonably well. We then carried out five triaxial extension tests ( ??1 = ??2 > ??3) for a high strength-anisotropy shale, and two extension tests for a low strength-anisotropy shale. Results from the compression and extension tests for failure along the weak plane shows that the role of ??2 is not significant for weak plane failure. However, for the low strength-anisotropy shale, the failure strength of the intact rock (i.e., at ??= 0o and 90o) for compression and extension tests were significantly different. This indicates that for intact rock failure, the role of ??2 is important and cannot be ignored.INTRODUCTIONFor many years, various researchers have studied the roles of ??2 for failure of isotropic rocks. (Mogi, 1967 and 2007; Colmenares and Zoback, 2002; Al-Ajmi and Zimmerman, 2005 and 2006; Haimson, 2009; Ma and Haimson, 2012). The findings from these studies show that the effect of ??2 on the strength of isotropic rocks is generally significant, and cannot be ignored.Since the role of ??2 in the failure of isotropic rocks was recognized, other researchers attempted to extend some of these isotropic failure criteria to anisotropic rocks, but with limited success (e.g., Tiwari & Rao, 2007; Singh et al., 1998; Zhang and Zhu, 2007; Pei, 2008). Smith and Cheatham (1980), on the other hand, conducted true-triaxial experiments on the Green River Shale and used a J2-I1 type relationship to predict the strength behavior, but without considering the effect of the three-dimensional orientation of the weak plane on strength. Therefore, unlike for the case of isotropic rocks, additional studies need to be done to determine the role of 2 on the failure of anisotropic rocks."

Jan 1, 2015

OF the many categories into which scientific knowledge has been arbitrarily 'divided, the one that has proved most. applicable in our attempts to gain an insight into the details of steelmaking processes is physical chemistry. To the young metallurgist who has only recently survived a college course in this subject, the application of its principles to reactions in liquid steel should not be difficult. The many excellent textbooks of physical chemistry provide ample material on the principles of this subject for the student of steelmaking processes. It is the purpose of this chapter to provide a concise review of the principles of physical chemistry that have proved useful in studies of steelmaking and at the same time to present some of the data that are essential to the application of physical chemistry to reactions at high temperatures. Certain parts of physical chemistry require rather formidable mathematics for their complete development, but in the main those applications in which we are here interested can be expressed in fairly simple terms. Many of the equations are logarithmic, and we shall use the symbols In X and log X to represent, respectively the natural and the common logarithm of X. The two are related-by In X = 2.303 log X. Logarithms may, be read from a good slide rule with sufficient accuracy for our purposes. In a few spots a knowledge of the calculus will be helpful. MATTER Innumerable forms of matter may, be recognized, and these may be converted by chemical processes into others, as ore, coke, and air are converted into iron, slag, and gas.. Whenever such a change occurs there is a corresponding change in the amount of energy associated with the matter. The process may require an input of energy, as in the electrolytic production of aluminum, or it may result in an output of energy, as in the combustion of fuel. The basic laws of the conservation of matter and of energy tell us that we cannot change the total amount of matter or the total amour t of energy.. When the fuel pile is used up, we realize that it has simply been converted into other forms of matter; .i.e., ash

Jan 1, 1964