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By Howard A. Meyerhoff, J. Earl Frazier

It is not known when silica sand was first noticed along the north coast of Puerto Rico, but the first mention of its occurrence was made in 1922, by N. L. Britton,1 who described its presence in isolated patches extending from Loiza westward beyond Manati. Further observations were made in 1925 and 1926 by Meyerhoff,2 who extended the known occurrences still farther westward to the low hill belt in the Quebradillas limestone immediately south of Hatillo. The extraordinary purity of the sands, which in most localities exhibit no contamination from the non-siliceous materials surrounding them, was quickly appreciated, and the feasibility of utilizing them for the manufacture of glass was investigated, initially by the Committee on Mineral Resources3 and later (1936) by the Puerto Rico Recon-structionAdministration and by H. C. Ray, mining engineer of the Insular Bureau of Mines. In 1934 samples submitted to the Hazel Atlas Glass Co., of Washington, Pennsylvania, were reported to have the composition as shown in the table on column two. Appreciation of the quality of the sand prompted geological and quantitative studies of the deposits, as well as cornmercial investigations to determine the feasibility of utilizing it locally or on the mainland for the manufacture of glass containers. Distribution of the Sands The quartz sands consistently lie within the outcrop area of the Quebradillas limestone, the youngest of the Miocene formations in the Tertiary coastal plain that fringes the northern coast of the Island. Many of the deposits are closely associated with limestone outcrops, but some appear to be embedded in lagoonal sediments at some distance from rock exposures, and at least one deposit, near Dorado, has been reworked by waves and littoral currents. With this single known exception, the deposits consist of irregular, patternless patches of white sand, which have sharply defined contacts with the surrounding material. Although patches of sand are present in a 90-km. belt that is not more than 5 km. wide, extending from Loiza to Hatillo, they attain maximum size, purity and number in the north central coastal area between Dorado and Barceloneta. Fifty separate deposits have been mapped in Lago Tortuguero and to the south of it, some as small as 50 ft. in diameter but

Jan 1, 1948

By J. Earl Frazier, Howard A. Meyerhoff

It is not known when silica sand was first noticed along the north coast of Puerto Rico, but the first mention of its occurrence was made in 1922, by N. L. Britton,1 who described its presence in isolated patches extending from Loiza westward beyond Manati. Further observations were made in 1925 and 1926 by Meyerhoff,2 who extended the known occurrences still farther westward to the low hill belt in the Quebradillas limestone immediately south of Hatillo. The extraordinary purity of the sands, which in most localities exhibit no contamination from the non-siliceous materials surrounding them, was quickly appreciated, and the feasibility of utilizing them for the manufacture of glass was investigated, initially by the Committee on Mineral Resources3 and later (1936) by the Puerto Rico Recon-structionAdministration and by H. C. Ray, mining engineer of the Insular Bureau of Mines. In 1934 samples submitted to the Hazel Atlas Glass Co., of Washington, Pennsylvania, were reported to have the composition as shown in the table on column two. Appreciation of the quality of the sand prompted geological and quantitative studies of the deposits, as well as cornmercial investigations to determine the feasibility of utilizing it locally or on the mainland for the manufacture of glass containers. Distribution of the Sands The quartz sands consistently lie within the outcrop area of the Quebradillas limestone, the youngest of the Miocene formations in the Tertiary coastal plain that fringes the northern coast of the Island. Many of the deposits are closely associated with limestone outcrops, but some appear to be embedded in lagoonal sediments at some distance from rock exposures, and at least one deposit, near Dorado, has been reworked by waves and littoral currents. With this single known exception, the deposits consist of irregular, patternless patches of white sand, which have sharply defined contacts with the surrounding material. Although patches of sand are present in a 90-km. belt that is not more than 5 km. wide, extending from Loiza to Hatillo, they attain maximum size, purity and number in the north central coastal area between Dorado and Barceloneta. Fifty separate deposits have been mapped in Lago Tortuguero and to the south of it, some as small as 50 ft. in diameter but

Jan 1, 1948

By Ram Song, Yohei Harada, Shinji Kumai, Kazuho Otsuka

"Recently, vertical-type high-speed twin-roll casting (HSTRC) has been developed. The HSTRC shows extremely high cooling rates over 1,000 K/s even at the mid-thickness area. The fabricated strip has many metallurgical characteristics; super-saturation of alloying elements, fine solidified structure, and homogeneous distribution of fine constituent particles. In Al-Mn based alloys, the Mn alloying element can be supersaturated in the a-Al matrix and also form Mn-containing constituent particles during solidification. The Mn supersaturation and the distribution of primary/secondary particles in cast products affect the metallurgical behavior in the down-stream processing and can improve mechanical properties of the final products. In this study, Al-Mn based alloy strips were fabricated by HSTRC with various Mn contents. The solidified microstructure, constituent particles and its distribution, and Mn solubility were investigated in the as-cast condition. Due to the high cooling rate of HSTRC, fine constituent particles were homogeneously distributed, and coarse intermetallics were not observed. Mn solid solubility was estimated by electrical conductivity. The estimated Mn solubility was equivalent between strip surface and mid-thickness area.INTRODUCTION Al-Mn based alloys, as non-heat treatable wrought aluminum alloys, are widely used in packaging and heat exchanger for automobile industry. Besides Mn, Al-Mn based alloys often contain Fe and/or Si as alloying elements or natural impurities. During solidification, Mn can be super-saturated in the Al matrix, and also form Mn-containing constituent particles. Additionally, in the subsequent thermal-mechanical processes such as homogenization, rolling, and intermediate annealing, Mn in solid solution precipitates out of the Al matrix as secondary particles. The size, distribution, type, and the amount of dispersoids including constituent particles affect to texture evolution, recrystallization behavior, and final mechanical properties of wrought Al-Mn based alloys (Huang et al., 2016; Huang & Marthinsen, 2015; Engler et al., 1995; Muggerud et al., 2013). Therefore, controlling the initial level of Mn super-saturation and the distribution of constituent particles are important in the cast Al-Mn based alloys."

Jan 1, 2018

By Martin Froehling, Curtis Mohns, Rahim Rajwani, Michael Fullam

"The Kemess mining and milling complex is operated by Northgate Minerals Corporation and is located in the mountains of north-central British Columbia, 430 kilometers northwest of Prince George. The complex consists of the Kemess South open pit mine and a 52,000 tonnes per day mill. Hypogene, supergene and leach cap ores are processed using conventional crushing, grinding, and flotation techniques to produce gold-copper concentrates with minor by-product silver value.The rougher flotation concentrate is re-ground in closed circuit before being cleaned to final concentrate grade. Historically, gold losses in the cleaner tailings were primarily associated with pyrite, with only minor amounts of free gold. More recently, with the processing of high pyrite ores, the major losses were found to be free gold less than 10 microns in size. The fine grind required for the high pyrite ores resulted in over-grinding of the free gold particles in the regrind circuit, contributing to poor flotation characteristics. It was thought that if this free gold could be recovered by gravity at coarser size in the regrind circulating load, the free gold losses in the cleaner tailings could be reduced.Preliminary test work carried out by Knelson Gravity Solutions indicated the potential for free gold recovery in the regrind circuit. A Knelson XD-30 Concentrator was installed with variable speed capability, and a series of optimization tests were carried out. In addition, cleaner tailings were characterized with gravity operating and with gravity not operating to determine the overall gold recovery benefit. The single Knelson XD-30 installation recovers ~10% of the total gold in the regrind circuit and increases overall recovery by 3% when high pyrite ores are processed."

Jan 1, 2007

By Cheng Pan, Xuewei Lv, Guibao Qiu, Chenguang Bai, Meilong Hu

"Physic-chemical properties of slag at high temperature play an important role in the pyrometallurgical process of production of ferronickel alloy. It determines the operation efficiency, metal recovery ratio, energy consumption and the distribution of elements like S and P between the slag and metals. In the present work, the effect of MgO content in the slag on melting features and viscosity of the slag was investigated. The MgO content in the SiO2-CaO-MgO-Al2O3 -FeO in the quinary slag system varied from 14.5% to 22.5%. The results shown that all slag samples begin to softening at the same temperature, the softening temperature, melting temperature, flowing temperature decrease with the increase of MgO content when the MgO content is in range of 14.5 and 20.5 pct mass, and when MgO content up to 22.5 percent, the temperatures increase sharply. Besides the inflection point temperature of viscosity-temperature curve increase with the increase of MgO when the MgO content is in range 16 and 22.5 pct mass.IntroductionNickel is very important to modern society, without it, we would not be able to share many things in our daily life, such as airplanes, computers and many stainless steel appliances in our homes and workplaces1.. It is the essential element of the stainless steel making, and about 65% of the nickel consumed in the world is used to make stainless steel2., so with the increase of stainless steel, the nickel production and demand has continued to increase3.Nickel is produced from two distinct ore types: nickel sulfide deposits and oxide nickel laterite deposits. The great majority of world’s known nickel resources are contained in laterite deposits3.. The laterite ores are normal classified into two groups: the high-iron laterite ore and high-magnesia laterite ore1. Typical composition of high-magnesia laterite ore is in the range 1-3%, and these ores are suitable for pyrometallurgical process to produce ferronickel4."

Jan 1, 2012

By L. G. Schumskaya, ?. S. Yusupov, ?. ?. Kirillova

"It has been shown on the example of cassiterite that grinding in mills of the increased power lead to destruction of the fine crystal structure and consequently to change in physical and chemical properties of the mineral, that is its transition into mechanically activated state. The increase in mineral reactivity is related to both the growth of mineral specific surface and sharp decrease in the sizes of primary crystallites accompanied by essential increase in number of microdefects that is clearly expressed in its increasing solubility during interaction with corrosive mediums, especially with acids. Calorimetric measurements indicate that the thermal effect of SnO2 solubility increases considerably.These observations allow us to propose two techniques of hydrometallurgical treatment of cassiterite: direct dissolution of the mechanically activated mineral in acids, although it is a very power-consuming process, and mechanical activation of cassiterite in presence of metals that are able to release hydrogen from acids. Active hydrogen is released during interaction between the mechanical mixture of SnO2 and metal with acids and reduces tin from the mineral transferring it into solution.In addition to other technological properties, the flotability of cassiterite has been thoroughly studied. It has been found that it steadily decreases as activation proceeds because of increase in the degree of hydratability of particle’s surface. In this case, the mechanical activation is provided through tribotreatment of a surface rather than through fine grinding. On this basis we developed the technique of inverse cassiterite flotation with its subsequent transfer into a chamber product that considerably increase the quality of a tin concentrate.The observed technological effects may be generally explained by occurrence of the valenceundersaturated, strained (deformed) chemical bonds and other active centers on the cassiterite surface while decrease in its flotability - by formation of the hydrolyzed tin species and impurity iron, such as Sn(??)4°, Fe(??)2 +, Fe(??)3° hydroxocomplexes and others."

Jan 1, 2003

By G. L. Oldright, Virgil Miller

"This paper is the eighth; of a series on smelting in the lead blast furnace, and the third' of a group on the modifications brought about by the introduction of rich charges.ACKN0WLEDGMENTSThe data that appear in these articles were obtained through the courtesy of the operators of the Bunker Hill smelter at Kellogg, Idaho. The authors take this opportunity to express their appreciation to Stanley A. Easton, the vice-president and general manager, Frank M. Smith, smelter director, and to A. F. Beasley, the smelter superintendent, and his staff.INTR0DUCTI0NIt has been noted that the gases issuing from the top6 of the charges in the International Smelting Co.'s furnaces at Tooele, Utah, were very similar in composition to the gases from the top of the iron blast furnace, as they contained about 26 per cent of CO and 12 per cent of C02, the rest of the constituents being mainly nitrogen with a very little hydrogen and oxygen. It has been seen that where the column of coke was sufficiently high, the production of C0 gas to carry out the reduction of lead ores was accomplished in about the same manner as in a gas producer. In some cases, there was a little oxygen in the ""top gas"" -- usually not over a few tenths of a per cent, but at times amounting to several per cent. The presence of this gas was attributed to irregularities in operation that permitted air to come up through the tuybres to the surface without meeting any coke that was incandescent. Only a hundredth of a per cent or so of sulphurous oxides was present in the gases issuing from the top of the furnace."

Apr 1, 1931

By Wolfgang Güter, Paolo Romualdi

Current extensions of the European railway network require long TBM drives in the diameter range of 10 m under critical and varying rock conditions. In view of that and in particular for a 7 km long high-speed railway tunnel in Spain to be started in mid-2003 a new design for a hard rock Double Shield TBM has been developed by SELI (Italy) and Jäger (Austria) in collaboration with Mitsubishi (Japan)and Robbins (USA). Due to the new design and operational features that new type of TBM has been named Universal Double Shield TBM with a further extended area of application. Special attention has been given to outstanding torque and thrust capacities combined with the shortest possible length of an innovative shield arrangement, different advance modes in various ground conditions and further developed exploration and treatment facilities.

Jan 1, 2003

By Florian Kongoli

New operating conditions and process parameters are often necessary in today's industrial practice of non-ferrous smelting and converting in order to accommodate various new chemical compositions of mineral charges and environmental requirements or to conceive new and more efficient industrial technologies. An important parameter in non-ferrous smelting and converting is the liquidus surface of multicomponent slags. This surface is affected by multiple factors such as temperature, gaseous potentials, the content of each component in the slag, etc., and cannot be quantified by the existing ternary liquidus diagrams. In this work a new type of representation of the liquidus surface of multi component systems has been presented by means of a thermodynamic model. This representation waives the need of the multidimensional representation of multi component systems and yields practical two-dimensional diagrams, which can be easily used in the industrial practice.

Jan 1, 2000

By G. W. Binkley, R. E. Collins, G. K. Dumbauld

A mathematical analysis has shown that the primary factors affecting the deposition of cement in unfractured perforations during squeeze-cementing operations are: the properties of the cement slurry, the geometry of the perforations, and the filtration time. The validity of the analysis has been substantiated by laboratory investigations. The information presented in this paper makes possible the prediction of the rate of deposition of cement in and about unfractured perforations under given squeeze-cementing conditions, the proper filtration time to control the amount of deposition to any desired value, and the deposition properties needed in cement slurries to restrict to any desired degree the formation of nodes of cement .Solids inside the casing. INTRODUCTION The deposition of solids against a permeable medium by the process of filtration is an important property of a cement slurry. General recognition of the role of filtration in the use of cement in wells is evident in view of the fact that several patents on low-water-loss cements have been issued during the past few years. In the conventional, high-pressure squeeze-cementing technique, a large volume of cement slurry is usually displaced into the area surrounding the perforated interval after the formation has been fractured hydraulically.&apos; Near the end of the job, the pumping rate is slowed or stopped intermittently in an effort to obtain a high pressure in the wellbore. The way in which a high pressure is obtained is not understood thoroughly. but it is be- lieved to be caused by the deposition of a rigid mass of compacted cement particles either in the fractures of the formations or inside the casing opposite the perforated interval. In a method of squeeze-cementing introduced several years ago, a small amount of cement slurry is squeezed into the perforations at a low pressure to avoid fracturing the formation. The filling of the unfractured perforations with cement particles by the process of filtration is important to the success of this technique. Early in the development of this low-pressure squeeze-cementing technique, laboratory and field-size experiments showed that conventional, neat cement slurries were unsatisfactory if the tubing was extended into or through the perforated section of the casing. The extremely high filtration rate of neat cement slurries caused the deposition of a compacted mass of cement inside the casing and made it impossible to remove excess cement by reverse circulation and difficult to withdraw the tubing. Because the need for cements with a reduced filtration rate was obvioils and urgent, modified cements containing 12 per cent bentonite were used until research was completed on modified cements containing 25 per cent bentonite.< These modified cements were useful in the solution of the immediate problem, but the following questions remained unanswered: (I) what is the optimum filtration rate of cement slurries for this application, (2) how long should the squeeze pressure be applied. and (3) how great are the effects of squeeze pressure and well temperature on the rate of deposition? Furthermore, the relationship of the filtration properties of cement slurries to the dimensions of the perforations and the wellbore was unknown. In order to obtain information relative to these basic considerations, a systematic evaluation of all the factors involved in the deposition of Cement during low-pressure squeeze-cementing operations was initiated. Although the work was directed toward an evaluation of the factors influencing the deposition of Cement in the low-pressure squeeze-

By George S. Rice

The subject of violent bumps in coal mines has been again brought to attention by a recent succession of such occurrences in the coal mines of the Cumberland field of eastern Kentucky and southern Virginia, which have caused fatalities and injuries to underground employees, a report on which is being issued by the United States Bureau of Mines1. The A.I.M.E. has had two valuable papers on bumps in the No. 2 Mine, Springhill, Nova Scotia, each followed by general discussion on bumps and their causes2. This paper gives a brief review of suggested causes and remedial measures given in English, Canadian and United States reports on blimps in coal mines, and then presents suggestions arising from the writer&apos;s recent investigation of the bumps in the Cumberland mines, made at the request of the mine operators, to determine the causes and remedies. These bumps, which occur under the simplest natural conditions, provide better opportunity for analysis of causes and effects than afforded under more complex conditions. The simple conditions in this field consist of relatively thin and level coal beds and uniform roof strata free from folding and faulting. Definition of Bumps Bumps in coal mines, as defined in this paper, are sudden violent bursts of coal that usually occur without warning in the extraction of pillars and may or may not be accompanied incidentally by falls of draw slate, upheaval of bottom and smashing of timbers. They are not known to occur where the advancing longwall method of mining, accompanied by

Jan 1, 1936

By George S. Rice

The subject of violent bumps in coal mines has been again brought to attention by a recent succession of such occurrences in the coal mines of the Cumberland field of eastern Kentucky and southern Virginia, which have caused fatalities and injuries to underground employees, a report on which is being issued by the United States Bureau of Mines1. The A.I.M.E. has had two valuable papers on bumps in the No. 2 Mine, Springhill, Nova Scotia, each followed by general discussion on bumps and their causes2. This paper gives a brief review of suggested causes and remedial measures given in English, Canadian and United States reports on blimps in coal mines, and then presents suggestions arising from the writer&apos;s recent investigation of the bumps in the Cumberland mines, made at the request of the mine operators, to determine the causes and remedies. These bumps, which occur under the simplest natural conditions, provide better opportunity for analysis of causes and effects than afforded under more complex conditions. The simple conditions in this field consist of relatively thin and level coal beds and uniform roof strata free from folding and faulting. Definition of Bumps Bumps in coal mines, as defined in this paper, are sudden violent bursts of coal that usually occur without warning in the extraction of pillars and may or may not be accompanied incidentally by falls of draw slate, upheaval of bottom and smashing of timbers. They are not known to occur where the advancing longwall method of mining, accompanied by

Jan 1, 1936

By K. N. Han, H. C. Cho, R. Kim

"As an extension of the work on the effect of OH- on various cations in hydrometallurgical systems, the effect of Cl-, Br-, I- and CN- on cations such as Ag+, Cd2+, Hg2+, Cu+, Cu2+, Co2+, Zn2+, Pb2+ and Sn2+ has been examined in detail. The Newton-Raphson technique has been used to determine the amounts of various metal species as a function of the concentration of anions. Some practical implications of various metal complexes in metal separation and removal from solutions have been examined and discussed.IntroductionUnderstanding the role of anions in hydrometallurgical processes often determines the success of an operation. The successful choice of concentration and type of anions not only leads to an effective extraction and removal of metals (Esmaeili et al., 2005; Brbooti et al., 2011; Wei et al., 2005; Jeppesen et al., 2009; Al-Tarazi et al., 2004), but also to assisting effective separation of various metals, whether it is a solvent extraction, ion exchange operation or even a simple precipitation (Farha et al., 2011; Sevenich and Fritz, 1983; Rashid, 1974).This paper continues the discussion of the role of anions in hydrometallurgical systems beyond the role of OH-, which was the topic of a previous paper (Kim et al., 2014). Table 1 lists various anions that are frequently used in conjunction with metal ions to be selectively separated or precipitated. As seen in the table, many anions are used frequently in hydrometallurgical practices. Some of the more frequently used anions include OH-, SO4 2- and CO3 2-. The halogen elements, Cl-, Br- and I- , as well as CN-, are also used in hydrometallurgical applications, especially in relation to noble metal recoveries (Meng and Han, 1994; Zhang et al., 1996; Sun et al., 1996; Starovoytov et al., 2007)."

Jan 1, 2015

By MARK J. VANARELLI

Estimating groundwater inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies for estimating steady-state groundwater inflows into deep rock tunnels. The case studies included the Chattahoochee and Nancy Creek tunnels. In this paper, statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations. A semi-empirical procedure was utilized for estimating groundwater inflows into these deep rock tunnels. It is the most widely used method/procedure in the tunnel industry. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels which exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semi-empirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Packer test data plotted in histograms were observed in all cases to be log-normally distributed for the radial flow condition. Modeling using Monte Carlo simulations was observed to be an effective tool for removing irregularities in the distribution of the data and incorporating high-end permeability data to derive reasonable groundwater inflow estimates. This paper is based on the PhD thesis entitled “Improvements to the Current State of the Practice in Steady-State, Groundwater Inflow Estimates into Rock Tunnels based on the Application of Statistical Analysis Methods of Packer Test Data obtained from Exploratory Borings During Geotechnical Site Investigations.”

Oct 9, 2020

By M. J. Nicol

The kinetics of the dissolution of colloidal silver in aerated cyanide solutions has been investigated with the aim of developing a relatively rapid and convenient method for monitoring the ?leaching power? of solutions typically used in the cyanidation process. Experimental results obtained are consistent with an electro-chemical model, in which the mixed potential is set up in the active region of the polarization curve for the anodic dissolution of silver, giving rise to a rate of dissolution which is controlled by the rate of mass transport of either cyanide or oxygen to the surface of the silver. The rate of dissolution of colloidal silver was found to respond to variations in the reactant concentrations in a similar manner to gold (and silver) in a typical free-milling ore. The use of this technique for the monitoring and control of the cyanide leach process is discussed.

Jan 1, 1998

By Clinton M. Young

The experiments herein described were carried on in 1908-9 by- the State Geological Survey of Kansas. Some months before taking up work on black powder the Survey had resumed work on an interrupted investigation of explosions in coalmines, a subject which is engaging the attention of numerous investigators. An unusual number of serious disasters has directed to the subject a study which discloses the disquieting fact that, in the United States, the ratio of lives lost per ton of coal mined has been 011 the increase. Methods of coal-mining have changed to some extent with the great increase of output, attained in comparatively recent years. These changes involve the working of very extensive mines, with increased difficulty of ventilation, increased accumulation of coal-dust, and a very great increase in the amount of explosive used. This last point assumes truly startling proportions when it is carefully observed. In the fields of the Middle West it is not now uncommon for a miner to use six kegs (150 lb.) of black powder in a " pay" of two weeks, while within the memory of men still active, one keg (25 Ib.) would last two men for a " pay." So great has the use of explosives become in some fields that the skilled coal-miner is hard to find, and the coal is not mined, but blasted. A preliminary study of the subject of explosions in coalmines has led to the belief that the use of large quantities of explosives, in some cases by slightly-trained men, had riot been

Jan 1, 1911

By T. C. Vogt

Earlier we described the uranium mineralogy of an areally broad sampling of Crownpoint ore, including the characterization of organic carbonaceous material associated with the uranium mineral. (1) We also reported on the leaching behavior of Crownpoint ores with a mild alkaline leaching system, oxygen (02)-sodium bicarbonate (NaHC03). (2) There was a wide range of leaching responses, with samples from some areas leaching at a slow rate with low uranium recovery. Evidence indicates that in these samples the organic material is intimately associated with the uranium mineral and shields it to some extent from contact by the leachate. (1,2) One method to obtain faster leach rates and higher recoveries is to use a chemically severe leaching system such as sodium hypochlorite (NaOCI) as an oxidant. (3) The use of sulfuric acid (H2SO4) and an oxidant for leaching ore in surface milling operations is widely practiced to effect high recovery of uranium (U308) from the ore. (4,5,6) The U308 is mobilized as the disulfate complex, U02(S04)224-, or possibly, the trisulfate complex, U02(S04)34-, is the soluble species. (7) Sulfuric acid leachate formulations were used in the first in-situ leaching operation in the Shirley Basin in Wyoming. (8) More recently H2S04 formulations have been used in the Rocky Mountain Energy field tests in the Powder River Basin (Bear Creek) and in the Teapot forma¬tion at Nine Mile Lake site near Casper. (9,10) Laboratory studies related to the use of H2SO4 for in-situ leaching have been reported (11-17) and Yan has .reported packed column leach studies on Crownpoint ore using H2504 and oxidant. (18)

Jan 1, 1981

By P. van Meurs

This paper describes a technique which permits visual observation of oil displacement processes througlrout the interior of a porous structure as thick as 2 in. A model having glass walls is filled with finely powdered glass. Such a model becomes completely transparent if the powdered glass pack is saturated with an oil having the same refractive index as the glass. When water or gar, with a refractive index different from that of the oil (glass) is injected, the model becomes opaque in the space occupied by the water (gar). visual observation and photography of these displacement processes are thus rendered possible. The following processes have been studied: (I) displacement of oil by water (linear drive) in a homo-geneous formation and in a stratified formation, (2) water flooding (five-spot well pattern), (3) solution gas-drive process, and (4) oil-bank formation. INTRODUCTION Most of the scaled model experiments heretofore carried out in the Koninklijke/Shell Laboratorium, Amsterdam, have been done in steel containers, in which oil-saturated sand packs represented the oil-bearing formation. In such experiments, for instance those on the displacement of oil by water, the cumulative oil production was measured as a function of the cumulative water injection. In order to interpret the measured production data, a need has for some time been felt for a means of observing visually what happens in the course of such experiments. Some information of this kind was obtained earlier by observing the water-oil distribution in various cross sections of the sand after the conclusion of the experiment.&apos; However, the technique used did not guarantee that the fluid distribution remained undisturbed. Moreover, the procedure was somewhat elaborate and the information obtained limited. Therefore a new technique has been developed, which is described below. DESCRIPTION OF EXPERIMENTAL TECHNIQUE AND APPARATUS Glass models simulating part of an oil reservoir are filled with ground Pyrex glass of a specific grain size, representing the porous structure of the prototype. Before an experiment is started, the porous formation has to be saturated completely with an oil having exactly the same refractive index as the Pyrex glass powder. All light-scattering surfaces of the glass grains become invisible and the formation is then transparent. If the oil is displaced by another fluid (e.g. by water in a water-drive experiment, or by gas liberated from the oil in a solution gas-drive experiment) the formation becomes opaque in the region where the oil is expelled from the rock.* The back of the apparatus is painted black and illumination is from the front; therefore, in the photographs of the experiments, the oil-bearing formation appears black, whereas the water- or gas-invaded areas are white.

Jan 1, 1958

By L. E. Murr, P. J. Smith

A study has been made by transmission electron microscopy of thin foils of 304 stainless steel fatigued external to the electron microscope in reversed bending, and of thin foils fatigued directly within the microscope in alternating tension. The build-up of stacking faults in the thin foils during fatigue zoas correlated with the dislocatirm structures found in thin films prepared fror fatigued bulk specimens. The performance of the special devices designed for fatigue of thin foils so outlined and the importance of alternative methods of preparation of more uniform fatigue specimens bY vapor deposition are emphasized. INVESTIGATIONS on fatigued bulk aluminum1,&apos; and stainless stee13j4 have revealed the existence of dislocation substructure on examination by transmission electron microscopy of electrolytically thinned foils representative of these bulk specimens. While this technique has proved extremely valuable, it has several shortcomings. First, the method of fatiguing bulk specimens and then thinning to foil for electron-transmission observation allows only one observation of internal structure at any one portion of the fatigue life. Second, thinning the bulk fatigued specimens to foil results in the loss of at least one original surface. Thus, what one sees in the remaining electron-transparent sections is an internal dislocation or fault structure which in many cases cannot be correlated with the original surface markings. This is an undesirable feature, since it is well-known that metal surfaces play an important part in the fatigue process.5 An obvious third undesirable feature of the thinning-from-bulk technique is the fact that static observations have difficulty (in the case of fatigue) explaining the mechanism of a dynamic process. What is required then is a method whereby a selected thin area can be continuously observed either while undergoing cyclic deformation or at various fixed stages of fatigue deformation. While Murr and wilkov6 have reported some success with an apparatus designed to fatigue thin metal foils directly within the electron microscope, the nature of the specimen-mounting procedure and the mechanical features involved in the adaptation of the fatigue device to the electron microscope make this method difficult to operate. It was not possible, for example, to make frequent observations of a selected area because of difficulty in maintaining a chosen area in a stable viewing position inside the electron microscope. Except for the build-up of a dislocation substructure and what are commonly referred to as "slip striations", little else has been reported from observations on thin-foil sections prepared from bulk fatigue specimens. segal17 has found "slip striations" in stainless-steel fatigued specimens which were electropolished from both sides, but gave no explanation as to their origin or identity in terms of lattice imperfections. The research to be reported in this paper was undertaken with the following objectives in mind. First, an attempt was made to devise a technique or techniques whereby thin metal foils could be fatigued and repeatedly observed by transmission electron microscopy. Second, it was hoped that some correlation could be made between deformation striations found in fatigued thin transmission specimens and thin foils prepared from bulk fatigued specimens. These investigations illustrate quite convincingly that a feasible method is available for the direct study of the fatigue mechanism and similar dynamic phenomena in thin transmission specimens inside the electron microscope. I) EXPERIMENTAL METHODS Three modes of specimen fatigue and observation of fatigue damage were used. These involved fatigue of thin-foil specimens in a special arrangement external to the electron microscope and observation of a selected area at various stages in the fatigue life, the fatigue of thin-foil transmission specimens inside the electron microscope, and the fatigue of bulk specimens external to the electron microscope followed by thin-foil preparation for direct observation at predetermined stages. Design of the External Fatigue Clip and Specimen Holder for the Hitachi H.U.11 Electron Micro-scope. The purpose of the fatigue clip was to provide a reversed bending fatigue stress to a thin-foil transmission specimen outside the electron microscope. In order to accomplish this, a flat-bottomed, U-shaped brass clip was made as shown

Jan 1, 1965

By S Kowalczuk, S V. L Barrett

The potential for adverse surface settlement during tunnelling in soil and rock poses a significant risk to the successful completion of any tunnelling project. Undesirable ground movement may lead to unacceptable level of damage to surface infrastructure, buildings and the environment, resulting in safety concerns as well as causing significant delays and costs to a project. One of the empirical methods which is commonly used to predict surface settlement in the early stages of a project’s development is the volume loss approach as described by Mair, Taylor and Burland, 1996. This method was developed for use in soft ground; however it has also been applied in weathered and soft rock to provide an initial indication of potential surface settlements along a proposed tunnel alignment. This paper presents some initial thoughts on the use of this method in weathered and soft rock and the associated limitations which need to be taken into consideration when interpreting the results. This includes complex weathering profile cases where the strength and stiffness of the ground does not necessarily increase with depth.CITATION:Kowalczuk, S and Barrett, S V L, 2014. Initial thoughts on application of the volume loss approach for estimates of surface settlement due to tunnelling in weathered rock, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 641–646 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014