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By John S. McCartney, Ismaail Ghaaowd

This study presents the results from centrifuge modeling experiments performed to understand the effects of temperature changes on the pullout capacity of scale-model energy piles embedded in normally- consolidated clay layers. The energy pile under investigation is an aluminum cylinder instrumented with internal strain gages and thermocouples, and its temperature is controlled using an internal electrical resistance heater. The energy pile was first heated until the temperature, pore water pressure, and volume change of the surrounding clay layer stabilized, after which the energy pile was cooled. Pullout tests were then performed on the energy piles heated to different temperatures to understand the effects of the preceding heating-cooling cycle on the pullout capacity. In addition, the clay undrained shear strength profiles were measured using push-pull T-bar penetration tests before and after heating. INTRODUCTION When a heat source such as an energy pile is embedded in a saturated clay layer, temperature changes will result in changes in pore water pressure as the rate of heating is typically faster than the rate of pore water drainage (Campanella & Mitchell 1968, Abuel-Naga et al. 2007, and Ghaaowd et al. 2016). Although all soils will initially expand during undrained heating, normally consolidated soils typically exhibit permanent contraction while overconsolidated soils exhibit expansion after sustained heating when drainage is allowed (Vega & McCartney 2015). Subsequent drained cooling typically leads to elastic contraction. Thermally- induced changes in pore water pressure and volume during transient heating and cooling may affect the soil- structure interaction of energy piles, as well as the ultimate capacity of the energy pile. This study is relevant as relatively few studies have been performed on the behavior of energy piles in soft clay (e.g., Ng et al. 2014), with most focused on the behavior of drilled shaft energy piles in stiff rock or overconsolidated clays (e.g., Laloui et al. 2006; Murphy et al. 2015; Wang et al. 2015; McCartney and Murphy 2017).

Jan 1, 2018

By R. Newman

An inexpensive slow-speed data acquisition system has been adapted to digitally record multiple parameters simultaneously at intervals of 15 seconds. The system was built for use with standard soils testing equipment to automatically record load and displacement parameters at predetermined instants in time. Simultaneous readout is achieved by the use of special signal conditioner and sample-and-hold circuits which read the multiple signals simultaneously and hold them until the slow acting system can print out. Three channels of a 10-channel system have been converted and found to operate successfully during a series of direct shear tests. A unique feature of the system, which significantly reduced its cost, is the power supply units. Dummy circuits are used to maintain a constant power demand during sampling) thus eliminating the need for a costly power supply with rapid response characteristics. The entire system, having an overall accuracy of 0.25 percent, was put in operation for a cost under $2,500.

Jan 1, 1970

By E. D. Calvert

The room temperature tensile properties of commercially pure titanium and seven titanium alloys prepared by skull casting were determined in the as-cast and heat-treated conditions. Data were compared with property data from tensile tests on wrought alloys of the same compositions in the as-worked and heat-treated conditions. The alloys evaluated were Ti-5Al-2.5Sn, Ti-6Al-4V, Ti-6Al-4V-lSi, Ti-6A1-2Sn-4Zr-2Mo, Ti-6A1-6V-4Zr-4Mo, Ti-6A1-6V-2Sn, and Ti-11.5Mo-6Zr-4.5Sn. Test specimens were prepared from both static and centrifugal castings and from plate fabricated by forging and rolling vacuum-melted ingots. The data indicate that the alpha and alpha-beta alloys have strength properties in the as-cast condition that are reasonably close to the strength properties of their wrought counterparts in the as-worked condition. An exception to this was the Ti-6A1-6V-4Zr-4Mo alloy for which insufficient data were available to form any firm conclusions. Fine-grained cast structures of Beta III (Ti-11.5Mo-6Zr-4.5Sn) were shown to be generally stronger in the as-cast condition than the wrought alloy in the as-worked condition except for the yield strength of one structure that was unusually low. Heat treatment of this alloy produced properties that were unpredictable. Indications are, however, that optimization of heat treatment parameters for each cast structure could produce strength properties equal to that of wrought materials.

Jan 1, 1974

By B. J. Moore

The Bureau of Mines has estimated helium resources of the United States at 727 billion cubic feet as of January 1, 1979. These resources are divided into four categories in decreasing degrees of assurance of their existence: (1) Helium in storage and in measured natural gas reserves, 185 billion cubic feet; (2) helium in indicated natural gas resources, 150 billion cubic feet; (3) helium In hypothetical natural gas resources, 186 billion cubic feet; and (4) helium in speculative natural gas resources that makes up the remaining 206 billion cubic feet. The identified helium reserves, which are made up of that in measured and indicated natural gas categories, are further divided into depleting, non- depleting, and stored classifications. The depleting resources are those that are associated with natural gasfields that are, or will be, produced for the natural gas they contain. All of the helium in undiscovered natural gas resources are included in this classification. These depleting resources comprise 600 billion cubic feet of the total resource base. The nondepleting helium resources are estimted tototal 88 billion cubic feet. There is 39 billion cubic feet of helium in storage in Cliffside gasfield near Amarillo, Tex.

Jan 1, 1980

East Otago gold deposits are hosted in Otago Schist that is the metamorphosed equivalent of Permian-Triassic Torlesse terrane greywackes. Relatively undeformed Torlesse sequences in Canterbury have <l m - 50 m bedding, with c. 500 m - l km and c. three kilometre scale units, typically either: 1) thick-bedded, massive, sandstones; 2) thin-bedded sandstone-argillite flysch; or 3) siltstone- or argillite-dominated units. Such lithological layering in Otago was intensely folded, deformed, and overprinted by metamorphic fabrics during Jurassic-Cretaceous regional metamorphism. Although primary sedimentary structures can no longer be recognised, a æghostÆ lithological variation is still present in Otago represented by psammitic (sand-derived), interlayered (sandstone-siltstone derived) and pelitic (siltstone-mudstone derived) schist. Lithological æunitsÆ in the schist are typically either 20 100 m or c.1 - 2 km thick, and are oblique to faults and shears hosting gold mineralisation at Macraes, Barewood, Nenthom, and Oturehua. Lithological variations and folds in lithological units are important in the along-strike distribution of gold in these deposits, and in the development of relatively high-grade pods and shoots at l00 m - 1.5 km scales. Ramps, flats and step-overs (known to be locally important for controlling mineralisation) are commonly located at lithological boundaries, presumably by local refraction of faults or shear zones as they propagated through folded stratigraphy. The various lithologies have also responded differently to deformation, causing variations in permeability that affected the penetration of mineralising fluids. Mapping lithological variations in barren host-rocks, either directly+ by fieldwork or indirectly by aerial geophysics, is a key to understanding and predicting the distribution of gold at mine and deposit scales.

Jan 1, 2001

By W. H. Coghill, F. D. DeVaney

"Introduction Numerous investigators have studied grinding. Each has contributed his bit to a literature that is difficult to correlate. Too many of the results have been transformed into curves with no many ""inflection points"" and ""counterflexures"" that they obscure the issue.Some of the investigators have neglected the very essence of the problem, namely, the power and the amount of material to which a known amount of work was applied. The purpose of this paper is to show the ease with which results can be interpreted when these quantities are duly recognized. Some grinding tests will be given for illustration.Grinding studies are of two kinds: (1) Study of the character of the ore and (2) study of the performance of the machines. Several ores may be crushed by a given machine, or several machines may be used on a given ore. The illustrations given in this report cover both objectives.Grindability Characteristics When the ores are being studied the information sought is grindability characteristics (grain-size distribution) and the grindability (work required to produce new surface) of a group of ores.When the study is of the machines, several machines are used for a given ore or given types of ores, and the grinding performances of the machines are compared by a grain-size study.Table 1 gives the grindability characteristics and grindability of six substances, one of which is coal. The substances are arranged from left to right in progressing order of tons per horsepower-hour. Curves and graphs are not needed for elucidation. The secret of the ease of interpretation is the order mentioned and the similarity of the sizing analyses. Power records must be complete in grinding studies.The grinding device was a ball, plunger, and mortar called the drop weight.' It may be used to advantage when the amount of material to be tested is too small for the orthodox machines.The upper part of table 1 shows the grindability characteristics by the cumulative-sizing analyses. Note how closely the percentage weights agree for a given sieve size. The lower part shows the grindability in terms defined elsewhere. The present paper should be read in conjunction with that paper."

Jun 1, 1934

By John Gross

Studies in grinding efficiencies carried out at the Midvale plant of the U. S. Smelting, Refining & Mining Co. and at the Tooele plant of the International Smelting Co. Were made possible by the cooperation of these two companies with the U. S. Bureau of Mines. Mr. Alan Probert of the U. S. Smelting, Refining & Mining Co. and Mr. E. C. Peterson of the International Smelting Co., devoted their entire time to the work during the respective tests, and their services are hereby gratefully acknowledged. It is a pleasure to acknowledge also the assistance and kindness of the staffs of both companies in making it possible, at considerable trouble and expense, to sample the entire mill circuits and in furnishing the necessary supplies and special apparatus required in the work.

Jan 1, 1929

By Robert H. Peters

This U.S. Bureau of Mines report identifies the types of serious accidents that occur most frequently at small underground coal mines and describes the strategies that could help prevent these accidents. A wide variety of methods for improving safety are suggested, including improvements in the design of equipment, work procedures, work schedules, safety programs, and emergency response plans, as well as techniques for diagnosing the potential hazards associated with new technologies and work procedures. Some of the papers in this volume focus on preventing specific types of mining accidents--ones associated with materials handling (primarily back injuries), equipment maintenance, improper machine guarding, and ground failure during retreat mining. Although the recommendations in this volume are heavily influenced by research performed at underground coal mines in the Appalachian coalfields, most of the papers contain advice that is equally pertinent to almost any type of mine.

Jan 1, 1994

By Mark E. Smith

Oxide ores can consume enormous amounts of expensive sulfuric acid. The problem is amplified with increasing heap heights. One solution is to provide a thin liner and drainage system between each lift of ore, thereby intercepting the pregnant leach leach solution (PLS) after it exits the active lift. However, these liner systems require special attention to hydraulics, slope stability and geomembrane design criteria. Inadequate attention to the first two can result in reduced recoveries, increased acid consumption andsystem failures. The geomembrane selection criteria are different from the base liner, and optimizing its selection can have significant effects on the operation’s bottom line.

Jan 1, 1996

By W. G. Pariseau

Equivalent elastic properties of discontinuously jointed rock masses are computed using a non-representative volume element(NRVE) approach within a three dimensional finite element program. Joint persistence, defined as the percentage of a joint plane that is actually occupied by joint material, is used in the NRVE computations as a step towards greater realism in stability analysis of mine openings. Persistence p is also the probability that a segment of a joint plane is occupied by joint material. Computations reveal a threshold phenomenon in jointed rock mass moduli similar to that observed in percolation theory. A rapid decrease in moduli occurs above a critical value pc(about 0.6). A detailed analysis of the well-known solution for stress about a circular opening in isotropic, elastic ground illustrates the effects of joint set orientation, spacing and persistence. Although stable “on average”, joint segment failures reveal a threat to stability and point towards rational design of reinforcement or support of discontinuously jointed rock masses.

Jan 1, 2003

By R. August Heindl

A process for recovering manganese from open-hearth steel-plant slags was investigated. The proposed method of accomplishing this is indicated by the flow diagram in figure 1. Mixtures of open-hearth, steel-plant flush slags and limestone, so proportioned as to have molar [CaO -3P205] ratios of approximately 2, were fired at approximately 2,400° F. in an oxidizing atmosphere and then cooled slowly. This treatment produced a clinker consisting principally of two solid phases comprised of (1) various combinations of the oxides of manganese, iron, aluminum, and magnesium, probably in spinel complexes, and (2) a dicalcium silicate phase, which contains the phosphorus. Reduction of these clinkers with hydrogen or with gaseous mixtures containing CO, CH4, and other hydrocarbons at about 1,300° F. formed manganous oxide as well as varying amounts of ferrous oxide and iron. Carbon monoxide and mixtures of hydrogen and carbon monoxide effectively reduced the clinkers but also gave higher proportions of soluble iron when the manganese was extracted from the reduced clinkers by leaching at about 80° F. with ammonium carbonate solutions containing 26 to 28 percent ammonia and 15 to 26 percent carbon dioxide. It is believed that the manganese is in solution as an ammonia-manganese complex. Concentrations of about 90 grams of manganese per liter were obtained by batch countercurrent procedures. By distilling 50 percent of the ammonia, the ammonia-manganese complex was decomposed, and approximately 90 percent of the manganese was precipitated as the carbonate with the simultaneous precipitation of 15 to 30 percent of the iron, the larger amounts of iron precipitating in the continuous tests. The manganese-iron ratio in the product could be increased either by recycling more manganese from the distillation to the extraction or by aerating the liquor to purge it of iron before, rather than after, the distillation step. Calcination of the pelletized manganese carbonate in an oxidizing stmosphere at 2,000° F. or above gave a final product, Mn304, resistant to crushing and apparently possessing the other physical properties essential in a ferromanganese blast-furnace feed.

Jan 1, 1955

By A. B. Needham

In November 1940, the Bureau of Mines started exploration of the Three Blacks manganese properties - Black Diablo. in Pershing County and Black Eagle and Black .Rook in Lander County. The purpose was to determine possible reserves of manganese in the deposits. It is reported that a small amount of manganese was mined from the Black Diablo during World. War 1. No mining except that necessary for assessment work had been done on the Black Eagle. Shipments were being made from the Black Rock deposit to a concentrator at Vain, Nev., while the Bureau's development work was progressing. The Black Diablo deposit consists of one patented claim owned by the Charleston. Hill National Manes Co. Mary L. Clough of Winnemicca, Nev., president. The deposit is about 20 miles by a gravel and dirt road southwest of Golconda, a town on U. S. Highway 40 and the Southern Pacific Railway, Pershing County, Nev. The deposit lies at an elevation of about 5,600 feet on the east flank of the north-south trending Sonoma Range. The property was leased by Messrs. Hollis Chatwin, T. E. Chatwin, and R. H. Richards of Salt Lake City and Mammoth, Utah. The lessees installed a crusher and erected an ore bin below the open cut on the deposit and mined and, shipped about 5,000 tons of about 30 to 52 percent manganese ore to the Columbia Steel Co., Provo, Utah.

Jan 1, 1950

By Thomas Novak, Robert Goldstein

The analysis of a machine-luminaire configuration is a time- consuming process requiring the construction of a machine mockup, installation of a designated lighting arrangement, and an extensive set of illumination measurements. This entire process, however, is well suited to computer analysis. By simulating the machine geometry and the characteristics of the desired luminaires, the incident light levels can be calculated at the required set of points. This Bureau of Mines paper presents a general description of the techniques involved in performing this simulation.

By Paul Downing

A typical day for a blasting company includes what seems to be an infinite list of tasks dealing with numbers. Whether determining the exact amount of explosives material in inventory, the number of holes in the shot, the exact distance from the blast site to the nearest exposure, or the capacity of bulk hoppers, the accuracy of numbers is key to ensuring the safety of the public, property and personnel.

Jan 1, 2008

By W. H. Gauvin, N. J. Themelis

I N ADDITION to its practical importance in the beneficiation of iron ores and in direct-iron processes, the study of the reduction of iron oxides involves many aspects of challenging theoretical interest. The complexity of the reduction process combined with the fact that under different experimental conditions the controlling stage for the reaction may not necessarily be the same, has led experimenters in this field to a wide diversity of opinion regarding the reaction mecl1anism. As a rule, each investigation has been restricted to the study of one or two variables over a comparative]~• narrow range of experimental conditions, and consequently, it be-comes necessary to examine the significance of each published work in the light of the results of other experimenters in the field.

Jan 1, 1962

By Yuanbo Zhang

Keywords: Complex Iron Ores, Roasting, Tin, Zinc, Pellets, Comprehensive Recovery. The complex iron ores containing tin, zinc are typical refractory ores. Large reserves of the ores are found in China and have not been utilized efficiently so far. A new process of tin and zinc recovery and pellet preparation from iron concentrate containing tin and zinc by controlled atmosphere roasting is developed in this investigation. The results of 2573 N/P compression strength of product pellets, the 91.49% and 82.22% volatilization of tin and zinc respectively, are achieved for a concentrate containing 0.39% tin and 0.28% zinc. The strength and chemical compositions of the pellets meet the requirement of blast furnace ironmaking. Volatilization mechanism of tin and zinc are investigated. Thermodynamic study shows that the reduction balance curves of SnO2(s) and SnO(g) are proximate in the presence of carbon, and the standard formation free enthalpy of FeO and SnO2 is also approachable. Therefore, it is difficult to realize the complete volatilization of tin in the form of SnO(g) by selective reduction. But SnO2(s) and SnO(g) will form SnCl4(g) or SnCl2(g) in the presence of chlorides and can be easily volatilized from the ores.

Jan 1, 2005

By Jon G. Bredeson

A survey of electromagnetic noise reports was performed and a summary of the results are given. Industrial concerns were surveyed for techniques to minimize the effects of electromagnetic noise and are presented. The common types of communication links used in mines today are presented. A mathematical development was presented which determines the probability of bit errors versus distance for various types of communication links designed for in mine use. The probability of undetected errors for the protocols of the communication links is given together with burst error detection.

Jan 1, 1981

By Yasser Mohamed

Daily field management of earthmoving operations requires quick and regular decisions for allocating available equipment to different jobs on a project. A general foreman?s day starts with matching several activities with a suitable set of available equipment to achieve the highest productivity and lowest unit cost. Usually, this decision-making process needs to be quick, and depends to a great extent on the foreman?s experience, which varies from one individual to another. Many analytical solutions with various degrees of sophistication and optimization exist to address such decisions. However, adopting any of these solutions is contingent on how accessible and easy-to-use the solution is. This paper discusses the development process of a webaccessible solution for evaluating earthmoving fleet composition and allocation scenarios. The solution relies on discrete event simulation and an optimization backend engine, but introduces the user with a simplified and easy-to-use interface that is accessible from any mobile device, and is customized to specific user?s needs. The developed system gathers most equipment and site-related input data from a company?s information systems to minimize user input. The user mainly needs to formulate equipment and job combinations and allocation scenarios (e.g. soil type, quantity, and hauling distance), according to equipment availability each day. Then the system will evaluate the productivity and unit cost estimates for each scenario, allowing the user to choose the most suitable one. It may also be used to automatically recommend the optimum solution given an available list of equipment. The paper presents the process followed in prototyping the proposed system in collaboration with a major Canadian earthmoving contractor, and customizing it to the user needs within the company. It also describes the overall structure of the developed system and its core simulation model.

Aug 1, 2013

By B. R. Broekman, K. J. R. Ford

Over the last decade significant development and use has been made of a simulation model that describes the HCFeMn smelting operations in Assmang Ltd. This spreadsheet based, semi-empirical, predictive model is derived from data from the submerged arc furnaces at Assmang?s Cato Ridge, KwaZulu-Natal smelter site. Departures from the empirical base case mass balance due to changes in the ores, reductant feeds and operating parameters are accounted for by use of fundamental relationships and heuristic type ratios which are applied in an iterative manner in the model. The model performs a sequential set of calculations to iteratively converge on a fully consistent mass and energy balance solution, which predicts Mn alloy and slag output masses and compositions for a given set of feeds. 440 MWh per operating day is used as the basis of energy input. The paper describes the key model components, assumptions made and calculation approach. Added to the mass and energy balance is a cost and revenue balance, which allows prediction of the economic performance for each simulation. Substantial use of the model has been made in simulating the performance of the current Assmang HCFeMn furnaces for both smelter investigations and future production planning. The model has also been a valuable tool in the strategic analysis of the use of future Mn ores and has formed the vital link between mine ore grades (metal and slag elements) and the expected alloy output, grade and profitability. Additionally, the model has been used in benchmarking exercises to predict other Mn smelting operations with remarkable accuracy. The paper highlights some aspects of the approaches taken in using the model to benchmark Assmang?s own furnace performance and cost competitiveness with other producers. For Assmang the development and application of this modelling technology has led to transformation in understanding of the Assmang HCFeMn furnace operations and increased awareness of the potential of its Mn ore bodies.

Jan 1, 2004

IN all wet concentration processes it is of primary importance to determine to what degree the crushing must be carried in order to obtain the maximum profit per ton of ore milled.To effect a clean separation, either by gravity or flotation treatment, between either one valuable sulphide from another, or a sUlphide from the gangue, the ore must have been subjected to grinding to such an extent that the particles to be separated are completely liberated from each other.Insufficient crushing will result in either an incomplete separation of the sulphides from each other, and thus a loss of the one sulphide in the other, or else a loss of the valuable sulphide in the gangue.This being so, the question arises whether the added cost of extra crushing would be economically warranted by the increased recovery consequent on such a step.

Jan 1, 1927