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By Sarthak Kaushik

Zeta potential measurements show that the isoelectric point of crandallite, in aqueous solution of 10-2 N sodium chloride is at about pH 5.5. Measurements of turbidity confirm the point of zero charge or crandallite. Calcium ions specifically adsorbed on the surface and thus changed the zeta potential and turbidity. From the measured data, it is confirmed that starch acts as a flocculent for crandallite. Oleic acid, which is a collector used in phosphate ore processing is weakly adsorbed on the surface of crandallite. This results in hydrophobic coagulation of particles resulting in a lower turbidity.

Sep 1, 2012

By C A. Locke, J Cassidy, J L. Mauk

The Waihi-Waitekauri region hosts numerous low-sulfidation epithermal deposits that both outcrop and occur at depth. Zones of intense hydrothermal alteration enclose the Au-Ag bearing quartz vein deposits. Hydrothermal alteration includes the destruction of magnetite by hydrothermal fluids, pervasive silicification adjacent to quartz lodes and potassium enrichment due to adularia and illite deposition. High-resolution airborne magnetic and radiometric, and new gravity data delineate distinct geophysical anomalies associated with hydrothermal alteration and mineralisation. Five magnetically quiet zones occur in the region varying in size from 3 to 34 km2 and in geometry from circular to irregular zones. These zones represent the near-surface extent of strong to intense hydrothermal alteration associated with fossil geothermal systems. All epithermal deposits in the region occur in magnetically quiet zones. Over 120 new gravity stations together with existing data across the Waihi district have defined a positive Bouguer gravity anomaly coincident with the magnetically quiet zone. Eastern and western gradients of 50 gu/km bound the anomaly that contains two flat gravity highs west and east of the Waihi deposit. Strong potassium signatures in airborne radiometric data correlate with outcropping zones of alteration and are consistent with the presence of adularia and illite minerals. Hydrothermally altered zones are represented by areas of low Th/K ratios as a result of low thorium concentrations in andesite and elevated potassium levels in altered zones.

Jan 1, 2003

By Murad Y. Abu-Farsakh

This paper presents the analyses of load-transfer (t-z) behavior of twelve prestressed concrete (PSC) instrumented test piles that were driven in different locations of Louisiana. The load transfer method is an efficient and practical tool for the analysis of single driven pile to predict the ultimate load. The test piles were instrumented with vibrating wire strain gauges in order to calculate the shear transfer for different soil layers during the static load test. The static load test was performed on all the test piles after 10 to 14 days of end of driving. Empirical load-transfer models were proposed previously by different researchers (Fleming 1992, Hirayama 1990, Krasinski 2012, Bohn et al. 2017) after analyzing the instrumented test pile results. For this study, load transfer of each soil layer was measured and compared with the previously developed existing model. The stiffness parameter (M) for the hyperbolic equation was calibrated in order to best match the measurements. The good agreement of the proposed curves was then confirmed by applying them to assess the overall load-settlement curve of other pile load test results available in the literature. INTRODUCTION The load transfer mechanism (stress-strain relationship) for an axially loaded pile usually comprises of three loading mechanisms: axial deformation in the pile (z), soil skin friction along the shaft (qs), and soil end-bearing (qb). The development of soil skin friction with axial deformation is referred as the t-z curve, and the development of soil end-bearing with axial deformation is referred as the q-z curve. Figure 1 presents the load transfer mechanisms in an axially loaded pile and the corresponding spring mass models for t-z and q-z curves (API, 2002). In order to construct the load transfer curve in clay under vertical load, the axial load transfer (t-z) curve and end-bearing load transfer (q-z) for that particular soil should be assessed separately. The axial load transfer (t-z) method is probably the most widely used technique to study the problem of single axially loaded piles. Therefore, the load transfer through the shaft of the pile and are getting more and more important compared to the only the pile capacity analyses. The load transferred from shaft to the surrounding clay soil is a function of the width of the pile and the surface roughness of the pile and clay properties. The development of a representative procedure allows the assessment of the t-z curve in soil (sand and/or clay) that leads to the prediction of a nonlinear vertical load-settlement response at the pile head.

Jan 1, 2018

By O. D. Staman

The risk assessment project examines the likelihood of inorganic contaminants from copper dump-leaching operations to contaminate domestic water supplies. The project examines contaminant transport by modeling contaminant movement from the base of a leach pile through the unsaturated zone and into the saturated zone. The modeling effort is unique in that it models infiltration, contaminant transport in the unsaturated and saturated zone combined with geochemical modeling of the unsaturated zone. The project incorporates probability theory to reflect the uncertainty of hydrogeologic parameters.

Jan 1, 1994

By S. Floreen

Seven iron alloys ranging from 5 to 12 pct Ni and 5 to 14 pct Cr were studied. All alloys transformed to bcc massive martensites. Tempering increased the strengths , probably because of relief of residual stresses generated by the martensite transformation. The major strengthening mechanism appeared to be solid-solution hardening by nickel and chromium. Studies of the work-hardening behaviw, of the effects of prior austenite grain size, and of the effects of changing strain rate and test temperature gaue results very similar to iron or low-alloy steels. Increasing nickel contents markedly improved the toughness at subzero temperatures. Studies of the flow properties did not, however, indicate the reason for the beneficial effect of nickel on toughness. The marine atmosphere corrosion resistance of the alloys was improved primarily by chromium additions, but increasing nickel contents were also beneficial at low levels of chromium. J\ number of maraging and PH stainless steels are strengthened by precipitation hardening in a low-carbon Fe-Ni-Cr martensite matrix. To some extent the resultant properties of these steels must depend upon the properties of this matrix. The present study therefore was conducted to evaluate the transformation characteristics and mechanical properties of a series of Fe-Ni-Cr martensitic ternary alloys. A limited evaluation of the corrosion resistance of the alloys in marine atmosphere was also made. ALLOY PREPARATION Seven 100-lb air induction melts were prepared using electrolytic iron, nickel, and chromium metal additions. The initial Fe-Ni charge also contained 0.05 wt pct graphite to produce a carbon boil during melt down. After melting of the base charge, the heats were refined with 0.1 wt pct additions of manganese, silicon, aluminum and titanium and poured into cast-iron molds. The ingots were homogenized at 1250°C and uni-directionally hot-rolled to 2-in. plate. They were then homogenized another hour at 1250°C, and unidirection-ally hot-rolled to %-in. plate at a finishing temperature of approximately 1050°C. The compositions of the heats are given in Table I. Two additional heats were prepared as 40-lb vacuum-induction melts using electrolytic iron, nickel, and chromium metals, and commercially pure molybdenum chips. A carbon boil, and 0.1 wt pct additions of aluminum and titanium were again employed, but manganese and silicon were not added. The heats were converted to %-in. plate using the procedure described above. The compositions of these heats are included in Table I.

Jan 1, 1967

By S. C. Essack

"Tenova Pyromet has designed a slag flow control valve that throttles the flow of slag in order to control the tapping rate. In addition, the valve has proved to be a reliable tool for closing the furnace during normal operation as well as emergency conditions. The valve makes use of a water-cooled copper element that is hydraulically operated and attached directly to the slag tap-hole. The equipment is compact, simple to maintain, and cost-effective to purchase and install. It can be retrofitted to most existing slag tapholes with minimal modifications.During the development phase, finite element method (FEM) and computational fluid dynamics (CFD) software was extensively used to model predicted operating conditions and to optimize the design. By using CFD, it was possible to understand the flow patterns inside the copper and to optimize these to improve overall performance.The slag valve was installed and commissioned in 2011/2012 on a 12 MW furnace as part of a new mineral wool plant in the USA. It has performed well since its installation despite operating under conditions in excess of the original design criteria. During the first 6 months of operation it quickly became the preferred method of closing the furnace, although the design intent was for occasional use during emergency shutdown conditions only. Since replacing the mudgun as the main method of closing the tap-hole, a few minor changes have been made to the installation in order to cope with the increased heat load and much higher frequency of use."

Jan 1, 2014

By Jeffrey B. Smith

Introduction The gas shortage is going to be with us for some time to come. If we can set aside political and industry rhetoric (along with subjective personal opinions), we still are confronted by two serious "facts of life": (1) for almost a decade the U.S. has been consuming natural gas at a greater rate than we have been finding new reserves; and (2) there is a finite amount of natural gas present within the earth&apos;s crust. Much of the known and easily exploitable sources of gas (the so-called "conventional" sources, such as the high permeability sand reservoirs of the Tertiary sequence along the Gulf Coast) already have been developed; their production is declining rapidly. The total producible reserves from conventional gas reservoirs amount to only 216 Tcf, less than an 11-year supply. However, several large potential resources of natural gas remain to be developed. These "unconventional sources" have low permeability and/or peculiar producing characteristics. The DOE program for development of these unconventional sources of gas is called the enhanced gas recovery (EGR) program. The primary goal of this program is to provide a data base of resource characterization and production technology that will lead to commercial development. DOE will encourage and support industry participation in developing and demonstrating technologies needed to reach this goal. Unconventional Resources Four major unconventional resources of gas have a high potential for commercial development. There are other unconventional sources (such as gas hydrates) that are too poorly defined to warrant a major development thrust at this time. The four unconventional sources of gas currently included in the EGR program are: 1. The carbonaceous shales of Devonian age in the Appalachian, Illinois, and Michigan sedimentary basins are the targets of the Eastern Gas Shales Project (EGSP). 2. The low permeability, low porosity so-called "tight" gas sandstones of the Upper Cretaceous/Lower Tertiary in the Rocky Mountain areas constitute the resource target for the Western Gas Sands Project (WGSP). 3. The free methane trapped in coal beds of both the eastern and western U. S. constitute the Methane from Coal Beds Project (MCBP). 4. The abnormally high pressured, high-temperature saltwater aquifers of the Texas-Louisiana gulf coast are targets of the Geopressured Aquifer Project (GPAP). Basic implementation strategy for these EGR projects involve (1) assessing and characterizing the resource potential of the resource; (2) conducting cost-shared field testing with industry to improve, develop, and demonstrate various stimulation and production technologies; (3) coordinating EGR activities within DOE and with other federal agencies (such as the Bureau of Mines) to minimize duplication; and (4) aiming all projects toward commercial development of the gas resources. EGSP What type of "geological animal" is the EGSP dealing with? While gas undeniably is related to the occurrence of natural fracture systems within the shale, the overall producing mechanism and precise location of fractured, gas-bearing locales within each basin is still poorly understood. By developing reliable resource characterization techniques and applying effective stimulation technologies we intend to elevate the Devonian shale from the status of a potential gas resource to that of a proven gas reserve. Once we have done this the private sector can take over the large-scale commercial development of the Devonian shale gas resource. WGSP The second largest project (both in terms of complexity and level of funding) is the WGSP. The primary targets for this project are the low permeability (< 1 md) gas sandstones of the Piceance, Uintah, and Greater Green River basins and the Northern Great Plains Province. Project success in these four primary geologic locales will permit investigating additional low permeability sandstones in 16 other sedimentary basins. It appears that the only practical means of increasing permeability and resultant flow rates from these sandstones lies in the use of massive hydraulic fracturing techniques. Unfortunately, it is still too early to design such jobs with predictable results. MCBP The MCBP is to be involved in producing and utilizing methane derived from coal beds. The coal, like portions of the Devonian shale, is impermeable, highly fractured (termed "cleat" by

Jan 9, 1980

By A. M. Tweedy, Felix A. Vogel

Since the publication of Prof. J. W. Richards&apos;s paper on The Schumacher Briquetting Process,&apos; this process has been in operation on a practical scale in two plants in the United States, and a few notes on the results obtained may be of interest. An experimental plant, consisting of a toggle press and a hydraulic press, was installed at Johnstown, Pa., together with the necessary bins and other equipment, and an attempt was made to briquette a mixture of Mahoning fines and blast-furnace flue dust, in a ratio of 7 parts of ore to 3 parts of dust. The results were unsatisfactory, in that the briquettes made were not hard enough to stand the severe handling to which they were subjected in the various transferences necessary between the press and the furnace. The trouble was due to several causes: First, the mechanical arrangement of the plant, which did not lend itself to a proper hardening and loading of the briquettes into the cars. Second, the irrrgular composition of the flue dust, as to both its lime and its fine coke contents. Third, the variability of the moisture content of the ore, and its viscosity when wet. Fourth, the ratio of fine ore to flue dust; that is, it was attempted to bind in too large a quantity of fine ore for the small amount of flue dust used. The first trouble could be overcome, and has been improved upon in the plant as it stands to-day. The second trouble was important, because of the small amount of dust used as a binder, and might have been easily removed by mixing the flue dust of the different furnaces, which, however, was never done. The third difficulty was more serious, but could have been partly solved, had it been possible to meet this along with the fourth difficulty, by decreasing the percentage of ore in the briquettes. It was proposed to do this, but it seems that the problem at the works in question is, primarily, to prepare Mahoning fines for reduction in the blast furnace, and only secondarily to use up the flue dust, and a solution along this line did not seem to be interesting.

Jan 1, 1914

By R. J. Matetic

The impact of longwall mining on the local hydrological regime has become an important environmental focal point. Unfortunately, only a few studies have addressed the timing and range of well fluid level fluctuations and the associated ground movement. Furthermore, even fewer studies have determined the influence of longwall mining on water quality. The U.S. Bureau of Mines is providing insight into this environmental concern through a program of field case studies. One such study was conducted in Cambria County, PA where five observation water wells were drilled above two adjacent longwall panels. In this study, three wells were completed as nested piezometers and the remaining two served as producing wells. The piezometers were positioned along a line oriented subparallel to the longwall face and were located at the centerline of each panel and over the intervening chain pillars. The piezometers were designed to monitor fluid level fluctuations in both shallow and deep water-bearing zones. Slug tests were conducted before and after mining to characterize changes in hydraulic conductivity of the respective water-bearing zones. Pressure transducers and data loggers were installed to provide continuous fluid level fluctuation data as mining developed through the study area. The producing wells were drilled to provide water quality information. One well was located directly above the centerline of a panel and the other was positioned over the panel&apos;s set-up rooms. The wells were designed to simulate domestic use and were produced daily, for four hour intervals, throughout the study. Samples of the produced water were collected before and after mining progressed through the area. In addition, an array of monuments was installed near the study wells and was periodically surveyed to characterize mining-induced surface deformations. This study shows that: a) the observed changes in ground water chemistry did not affect the potability of the water; b) short-term major water level fluctuations occur at the approximate time of undermining; and c) water level recovery begins before the process of subsidence is complete.

Jan 1, 1986

By J. J. Carlson

Studies were carried out to determine whether filtration rate changes observed in an iron ore concentrator were due to variations in particle shape. It was confirmed that ores mined from different locations differed in filtration rates by as much as 60%. However, when image analysis was used to quantify the shapes of the individual particles in the filtration feed, it was found that the particle shapes showed almost no variation, and the shapes did not correlate with the filtration rate. It was also determined that the filtration rate variations were not caused by changes in particle size distribution. These results suggest that the differences in filtration rate are due to factors other than size and shape, such as surface chemistry.

Jan 1, 2008

The Drake-Rivertree area lies in the far north east of the New England district of New South Wales. Drake is some 500 miles north of Sydney by road and 36 miles west of Lismore. Rivertree is situated 24 miles north of Drake.The Drake deposits were first worked in 1878 for gold which occurred in a very fine state in ferruginous gossan but at depth copper ore became more significant. The lodes at Rivertree, discovered in 1887, were worked for silver but mixed sulphides became more prominent in deeper levels.Several mines operated at each centre and each locality smelted its own ore.The mines at both centres were operated sporadically for many years though production was not particularly substantial.A number of the larger mining companies have shown a recent interest in this mining field with special emphasis on the Drake locality.GENERAL GEOLOGYThe two mining centres are situated to the north and south respectively of a belt of Permian marine sediments and volcanics similar to, and probably representing an easterly extension of, the rocks of the Emmaville district further west.E. C. Andrews (1907) recognized two stratigraphic units within what he called the Drake Series. The Lower Division consists of rhyolite flows, tuft&apos;s, breccias and agglomerates, followed by trachytic and andesitic tuft&apos;s containing cladochonns, thanmopora willcinsoni and other Permian forms.

Jan 1, 1962

By I. Hawke, K. Barron

I. Hawkes (Postgraduate School in Mining, University of Sheffield, Sheffield, England) — The photoelastic stressmeter is proving to be a very practical tool for &apos;in-situ&apos; measurements in the fields of civil and mining engineering and Barron&apos;s article has therefore come at a very opportune time, supplementing as it does, the considerable amount of laboratory and field data which is being accumulated.1,2,3 There are however several points relating the application of Barron&apos;s conclusions to the practical use of the meter which require further elucidation. EASE OF READING If the photoelastic stressmeter is to have a wide application, the fringe orders must be easily measured. The system adopted by the writer and his colleagues at Sheffield for the uniaxial stress case is to read the fringe order at the 45 point, 0.20 in. from the center (11/4 in. diam meter). This procedure has been recommended because the fringes not at this point form a very distinct &apos;eye&apos; which is obvious even to those who have had little experience with photoelastic fringe patterns. Barron points out that this point can also be used up to a stress ratio of 0.33 and in practice this is normally done. In biaxial fields above a ratio of 0.33 the &apos;eye&apos; is no longer apparent and the fringe order must be ascertained at some other point. The writer and his colleagues experimented at various points and finally chose a point at a distance 0.175 in. (11/4 in. diam meter) on the minor stress axis and fixed this point on the meter by inserting a collar of this diameter. This procedure enables the &apos;eye&apos; technique to be used for uniaxial stresses as the &apos;eye&apos; falls outside the collar; any other technique for biaxial patterns would require lines to be engraved on the meter itself and reading difficulties would be experienced by all but the most highly trained. It is interesting to point out that in a great many field applications ranging from underground pillars to building foundation piles the stresses measured have been uniaxial. In such cases, reading the fringe order has been simple even for unskilled persons. SENSITIVITY The photoelastic stressmeter acts as an inclusion, and as such its theoretical behavior is as described by Barron&apos;s mathematical analysis. When considering its practical application, however, it must be remembered that rocks and concrete are not mathematically ideal substances. The theory relates the fringe order in the meter to the stresses and the E (Young&apos;s Modulus) and the µ (Poisson&apos;s Ratio) values of the surrounding material. There is of course no unique E or µ value for rocks or concrete. These values change both with stress level and time load application sometimes to the order of 300%. We at Sheffield have very accurately calibrated the photoelastic stressmeter in a wide range of materials and have also measured the average E values for these materials. The results prove that the meter sensitivity

Jan 1, 1965

By Jos. R. Guiteras

This paper describes the operations of the St. Joe Mining & Milling Co. in Boulder County, Colo., as of June 1936. Later a brief visit was made to the mine in September 1936; information obtained at that time has also been recorded. The company operates a gold mine, the Grand Republic, in the Sugar Loaf mining district; a 100-ton flotation mill in Lefthand Canyon near Gold Hill; and a custom sampling punt, the Boulder Ore Sampling Works, at Boulder, Colo.

Jan 1, 1937

By Denis J. Kemp

The 20th Century saw changes in the mining and metallurgical industry not only technically but also in social and environmental expectations. As projects continue to become larger to maintain competitiveness the visibility of their potential impacts raise concerns among many groups. The need for transparency, openness and early engagement of all parties are fundamental to assure success. An equally important task is to anticipate the standards that will be required to meet society?s expectations in the 21st Century. Historical Observations The mining industry of the 18 and 19th Century was dominated by opportunistic Companies and individuals with an entrepreneurial flair for adventure and risk. Those who promoted had the chance of great reward, while those willing to risk their life were assured a short one for their efforts because of the physical and health dangers that abounded. Disregarding conditions miners rewards were high even in those days, with an average Cornish miner known to be earning two pound a month in 1800. Coal and iron ore mines were driven by the needs of the industrial revolution and were the first to embark on larger scale output. Base metal mines were smaller as industrial demands for their use did not start to expand greatly till the late 19th Century. Electrification, the automobile and the 1st World War drove the increased demand for a variety of metals. Early mines were foul smelling and dusty and what was taken from below ground left spoil piles around the surface countryside after recovery of the coal or concentrate. The image of barren blackened hills is one that is easily conjured up and is an environmental legacy that still lives with us today.

May 1, 2002

By Mario Aiezza

This paper outlines the results of a relationship developed during the design and construction of the foundations for the Gallery Towers project in Melbourne. Both the builder and the piling contractor were determined to arrive at a satisfactory foundation solution to the problems encountered at the site. The scope of piling work was to provide load-bearing piles under the building columns, some of which were located within a retention system that also required a piling solution. Geological conditions were variable and challenging. The site area was small and located adjacent to the National Arts Centre in the developed Southbank area, a high density office area. This presented logistical problems in limiting construction traffic on site and also demanding minimal noise and vibration emanating from piling activities. The piling contractor, Vibro-Pile, and the builder, Walter Construction Group, faced the challenges presented with a refreshing cooperative attitude that was beneficial to both companies. Commercial issues rising from design and construction problems were first put apart in order to allow the respective technical department of each company to work with minimum constraints to achieve the most cost effective solution. In the process usual adversarial attitudes resulting in loss of time and money was avoided. A number of issues were addressed successfully at minimum cost and time during this contract. Despite the difficulties encountered, the job was completed on time and with negligible claims for extras, resulting in the development of a strong mutual respect between both companies.

Jan 1, 2002

By P. A. K. Wilkinson

This paper is concerned with the development of an in situ recovery of boric acid from a deep-seated colemanite deposit in California. The deposit contains 147 million tons of borate ore containing 6.4% boron oxide (B203). It is the largest undeveloped colemanite deposit in the United States and because of its unique occurrence and grade, in situ extraction appears to be the most economic viable process. The paper covers the geological, mineralogical, hydrological, well-field development, and extraction considerations leading to the initial pilot plant and subsequent demonstration plant phases of the project. Market potential aspects and preliminary economics of the project are also covered.

Jan 1, 1987

By Richard J. Hartman

Current design practice is to select steel sheet piling sections using sufficient section modulus and yield strength to resist the calculated bending moment. Thus, section modulus is the only property of the sheet pile cross section used in the selection process. Full scale laboratory testing documented that section modulus alone is insufficient to predict the strength of sheet piling. During testing, sheet pile sections with equivalent section modulus exhibited as much as 75 percent difference in load resisting capacity. Analytical study following the testing established that, in addition to the traditional longitudinal (vertical) stress in sheet piling, transverse (horizontal) stresses are also present. Transverse stresses reduce the ability of the sheet piling to function in the intended manner. It was found that transverse stresses result from the pressure applied by soil and water and that the capacity of the sheet piling diminishes with increased pressure. All sheet piling is subject to this behavior. This paper describes the testing and the results and establishes that a problem exists. A two dimensional procedure is described that assists in evaluating transverse stresses and their effect on sheet pile capacity. A method of creating design aids for use by engineers is illustrated.

Jan 1, 2006

By Robert M. Cox

Abrupt tailgate roadway ground failures, described as floor bumps, sometimes occur in the tailgate entry outby the face during the high-speed extraction of coal from mechanized longwall panels. These floor bumps typically damage the tailgate entry support structures for a distance of from 12.2 to 24.4 m (40 to 80 ft) outby the face. The relative closure of the tailgate entry may be a key indicator of potential tailgate ground control problems. Regression analyses of tailgate entry convergence data conducted by the U.S. Bureau of Mines (USBM) indicate that entry closure may be characterized as an exponential function of the distance outby the longwall face. Assuming that the entry closure is caused by the abutment loads created by the excavation of the longwall panel, the resulting convergence equation can be integrated to locate the centroid of abutment loading. This information can be used to document zones of potential ground failure ahead of the operating face.

Jan 1, 1994

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Jan 1, 1938

By M. Staite

This paper analyzed the feasibility of converting a 5kW natural gas SOFC power generator system designed to operate on natural gas to be fuelled by methanol. The analysis included laboratory methanol fuel processing experimentation, methanol reformate SOFC cell testing, and SOFC system mass and energy balance modelling. Methanol fuel processing experimentation indicated that theoretical reformate compositions can be achieved for high temperature (600-900°C) methanol steam reforming. A 6% open circuit voltage decrease and a 10% peak power current density decrease between cell operation on humidified hydrogen and methanol reformate was observed. SOFC system mass and energy balance modelling indicated that a natural gas SOFC system can be converted to operate on methanol fuel with minimal (1%) efficiency impacts, however the systems&apos; thermal integration can be impacted.

Jan 1, 2005