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By Ryan Weaver, Travis Coleman

The drilled shafts that support transmission lines and substations have been increasingly subject to testing to assess the integrity of placed concrete. Cross-hole Sonic Logging (CSL) has been used, but large diameter shafts with challenging site access are generally more favorable to Thermal Integrity Profiling (TIP) testing. TIP testing assesses the shafts based on measurements of the concrete temperature during curing. The TIP results provide assessment of integrity both within and outside the cage, along with information about the alignment of the cage and concrete cover. This data has allowed shafts with imperfect results to be subject to more detailed structural evaluations. However, it may not be well understood how to use this additional information by designers and engineers. The purpose of this paper is to present TIP results of transmission line foundations, both with and without issues with integrity, including cage shifting, minimal concrete cover, or soil inclusions. The intent is to provide general guidelines of the issues that merit additional investigation and those that should be recognized as inconsistencies inherent to underground construction. BACKGROUND This paper is intended to discuss some of the drilled shaft evaluations made when TIP testing is performed. The authors of this paper were recently involved with a transmission line project that was designed and constructed for a Confidential Utility Client located in the Midwest United States. The project was delivered as an Engineering, Procurement, and Construction (EPC) contract with the electrical line construction company as the prime contractor. The contractor then subcontracted several parts of the work which included engineering for transmission line and foundation design, foundation construction, and third-party testing intended to evaluate the concrete homogeneity and integrity of the place concrete in the deep foundations. The testing method selected was Thermal Integrity Profiling Method B, which uses thermal sensors embedded in the concrete. The TIP testing was administered by Mr. Travis Coleman with GRL Engineers, Inc. Mr. Ryan Weaver with Burns & McDonnell served as the owner’s engineer and technical consultant for the utility and was responsible for reviewing submitted TIP reports and providing recommendations to the utility on their acceptance, and if there were any issues that would warrant further discussion and analysis.

Jan 1, 2019

By Jeffrey Hedenquist

The Lepanto and Victoria epithermal deposits contain in excess of 8 Moz Au, associated with massive enargite-cemented breccia and quartz-carbonate-base metal veins, respectively. The two deposits are separated by 500 m, but the latter was not discovered until the former was nearly mined out. The sulfid assemblages of these adjacent deposits are characterized by high- and intermediate-sulfidation states, respectively. However, gold was introduced after enargite at Lepanto, associated with an assemblage that is similar to that of the Victoria ore. An even larger gold resource is present in similar to that of the Victoria ore. An even larger gold resource is present in the Far Southeast porphyry Cu-Au deposit, the top of which lies 200-400 m beneath and adjacent to these two epithermal deposits.

Apr 24, 2001

By Cem Şensöğüt, Özer Ören, Yaşar Kasap

The mining sector, which has an important place in terms of raw material and energy supply, is referred as a sector with one of the highest fatal accidents in comparison with other sectors. In this century, where occupational health and safety awareness has increased, it is important to review the past accident statistics and to determine the current deficiencies by using the information in the inventory. In this study, the Malmquist total factor productivity index (MPI) has been utilized to investigate the changes in the work accidents occurring in the Western Lignite Corporation (Turkey), where underground and surface production methods are applied, and to determine the measures to be taken. According to the results obtained, both the decrease in production amount and the increase in the number of accidents caused inefficiencies during the period in concern due to the expected 10-year economic life of the mechanized system operating in the underground production panel that came to an end in 2007 and the flooding took place in early 2017. Compared with the underground operations, it has been determined that production can be carried out at the appropriate scale despite the heavy working conditions encountered due to the changing climatic conditions and the progress of production in the surface operations.

By E. Stemn

Incident investigation is of utmost importance in most high-risk industries. This study was undertaken to study the content of past investigation reports to determine the effectiveness of the incident investigations. The study uses a semi-quantitative method to assess the effectiveness of incident investigations in the Ghanaian mining industry by evaluating the quality of past investigation reports. The assessment tool consists of 5 elements with several indicators and rating scales for assessing the quality of an investigation report as a measure of the effectiveness of the investigation. The method was applied to 304 investigation reports of 3 Ghanaian large-scale gold mines, and the results correlated with incidence rates of the mines to determine if any relationship existed. The results showed that the mines differ significantly in the quality of their investigation reports, suggesting differences in the effectiveness of their investigations. In addition, the incidence rates of the mines negatively correlated with some elements of the assessment tool. In general, the method was found useful and revealed areas where improvement is needed. INTRODUCTION The importance of learning from incidents is well documented in the literature. For instance, some scholars regard learning from incidents as important for improving safety [1,2]. Thus, many organisations spend considerable resources in identifying lessons from incidents and subsequently on the process of improvement that follows the identification of lessons. It is therefore important for such organisations to determine the effectiveness of their learning from incidents processes, in order to identify specific areas where improvements are needed, so that interventions can be as specific as possible. The learning from incidents process models the plan-act-check-do approach of management systems, often consisting of four major stages, namely; data collection and incident analysis, planning interventions, implementing interventions and follow-ups and evaluation [3,2]. The investigating and analysis of incidents have been regarded as one of the vital stages of the learning process since it is the stage where lessons are identified [3,2,4]. It has also been noted elsewhere in the literature that results of the previous stage of the learning process are important for the next stage [3]. For example, ineffective incident analyses could result in the planning of ineffective remedial measures. One of the primary aims of incident investigations is to identify lessons from previous incidents which when implemented can prevent future recurrences or minimise the effects of future incidents. There is thus the need for organisations to assess the quality of their investigations periodically since it is one of the means they adopt to improve safety and the quality of remedial measures to some extent depends on the effectiveness of the investigations. Although previous studies [5,2] have assessed the effectiveness of the learning process, and some aspects of the learning process, such as incidents reporting, there is less focus on the effectiveness of incident investigations. The research described in this paper was therefore conducted to contribute to this gap, focusing more closely on incident investigation reports.

Jan 1, 2019

By Batric Pesic

Gold dissolution with bromine was studied by using the rotating disc technique. Geobram TM 3400 was used as a source of bromine. The parameters studied were: rotating speed, Geobrom 3400 concentration, pH, temperature, sulfuric and hydrochloric acid concentration, and the concentration of various cations (copper, iron, zinc, aluminum, manganese, potassium and sodium) and anions (chloride, bromide, sulfate, nitrate, and iodide) According to the Levich plot and activation energy, gold dissolution was controlled by a chemical reaction rate. Copper, iron, and manganese in their highest oxidation states, aluminum, zinc, sodium and potassium did not have any effect on gold dissolution rate. The presence of manganous ion dramatically decreased the gold dissolution rate. Kinetic performance of bromine, in the form of Geobram TM 3400, was compared with performance of cyanide and thiourea.

Jan 1, 1990

By W. A. Gow

"In January of 1964, a group known as the Canadian Gold Metallurgists was formed with the backing of the managers of most Canadian gold mining operations. This organization is composed of about thirty mill superintendents of Canadian gold milling operations where the cyanidation process is in use, and one member from the staff of the Mines Branch, Department of Energy, Mines and Re-sources, Ottawa. The aim of this group is to bring together gold mill operators, and research and development people from both industry and government for the purpose of discus-sing common metallurgical problems, and deciding on what operational R and D efforts can be made to help solve these problems. Since the conception of this organization, this approach taken by the gold industry to the study of metallurgical problems has resulted in benefits to all operators, both by assisting them with problems peculiar to their own individual operations and by providing developments of general interest to the industry.This paper describes events leading up to the formation of the Canadian Gold Metallurgists, and how the group has operated since its formation. Examples of progress made toward the group's objectives are given, and possible future programs are discussed."

Jan 1, 1968

By John A. THOMPSON, Pazcl D. Torrey, Frank Breayster

DISCOVERY of natural gas in the Dundee field of New York in February, 1930, and the subsequent discovery in Tioga in September of that year, focused the attention of the natural-gas industry on the enormous possibilities of production and distribution in - the most populous area of the United States-New York and New England. Prior to 1926 the natural-gas industry in New York State had settled into a definite and limited policy, with the distributing companies controlling the output from its discovery to the ultimate consumer. Production amounted to between G and 7 thousand mil- lion cubic feet a year, with another 10,000 million feet imported from Pennsylvania for distribution in New York State. This gas was primarily from the Medina sand stone in. the western part of the state.

Jan 1, 1932

By B. A. Bancroft

A quality assurance program consists of all those activities aimed at providing confidence to the purchaser that the suppliers quality system will provide a product that will satisfy the purchaser's stated quality requirement. An organizing principle is necessary for prioritizing the quality control activities of quality personnel in the face of a myriad of technical possibilities, data-analytic applications, and an overwhelming number of possible activities promoted in the literature and by quality "gurus". The organizing principle I like is that quality assurance exists when those involved in the quality process: (1) know what they are supposed to do, (2) can tell if they are doing it and are set up to continue doing it and, (3) if they are not, they can remedy the situation in a timely fashion. Any incremental activity which facilitates this organizing principle is a continuous improvement activity. That activity which has the chance to facilitate this principle to the greatest extent is the next one to work on. In these days of lean corporate and regional staffs it is as important to know what not to work on as it is to know what to work on. In this paper I shall discuss in general terms the implications of this organizing principle for the design of Quality Assurance (QA) Programs for coal mines and also provide some comments about the application of Statistical Process Control (SPC) methodologies in the coal industry.

Jan 1, 1994

By A. B. Walker

The effects of the injection of dry limestone additives into boilers for the sorption of sulphur dioxide have been studied in pilot and full-scale systems. The effects of such injections on boiler mass particulate emissions as well as collectability characteristics of the fly ash and reaction products are presented. Implications of the effects on the design and economics of particulate collectors, in particular electrostatic precipitators, are discussed.

Jan 1, 1971

By Mustafa Kumral, Yuksel Asli Sari

Economic evaluations of underground mining operations are made based on the estimated or simulated grades of the block model as the actual values are not known. Depending on how the planning decisions are made, the risk of the operation can be managed and decreased. This research introduces a mixed-integer linear programming (MILP) model for stope sequencing optimization that considers the uncertainty associated with net present value (NPV) using chance-constrained programming (CCP). The introduced method permits achieving a balance between maximizing NPV and reducing the associated operational risk through transforming the problem into a multiobjective problem, where the objectives are maximizing the NPV and minimizing the risk. This risk is expressed in terms of the standard deviation of project outcomes, taking into account multiple possible scenarios. In a case study, the efficiency of the method was demonstrated as a decision-making tool capable of translating a specified risk or reliability level into a stope sequencing plan.

Jan 1, 2024

By Scott Dodds

"The Oxford Hydroelectric Station was a unique project that incorporated a variety of dam strengthening methods to stabilize the facility in order to meet the standards required by Federal Energy Regulatory Commission (FERC). The dam stability and Probable Maximum Flood (PMF) remediation work consisted of (1) construction of a new emergency spillway; (2) installation of 75 high capacity rock anchors; (3) construction of an anchored concrete powerhouse buttress; (4) construction of cast-in-place and sheetpile flood walls; and (5) design and construction of a permanent soil nail wall. INTRODUCTIONThe Oxford Hydroelectric Station is one of 11 hydroelectric facilities owned and operated by Duke Power along the Catawba/Wateree River. The Catawba River originates in the foothills of the Appalachian Mountains just west of Morganton, North Carolina. The river flows east out of the mountains and, at a point just below the Oxford Dam, the Catawba River turns and heads southeast. The Catawba River continues to flow southeast past Charlotte and into South Carolina where it eventually becomes the Wateree River. The Wateree River eventually flows in to the Atlantic Ocean.Located a few miles east of Hickory, North Carolina, the Oxford Dam and Hydroelectric facility is in the upper reach of the Catawba River. Oxford Dam creates the third impoundment along the river known as Lake Hickory. Lake Hickory is well known locally for providing many outdoor activities such as boating, jet skiing, canoeing and fishing. The dam and powerhouse were put into operation in the spring of 1928.Key features of the dam include a short embankment section on the south end of the structure, a 391-foot (119m) long south bulkhead and powerhouse, 540-foot (165m) long gated spillway section and a 235-foot (71.6m) long north bulkhead. The maximum height of the dam is approximately 100-feet (30m) from the crest to the dam/rock interface. (See Figure 1).The work associated with this project is the result of licensing requirements of the Federal Energy Regulatory Commission (FERC) which mandates that all hydroelectric facilities have the capacity to safely discharge runoff created by a critical rainfall event defined as the probable maximum flood (PMF). Duke Power, a division of Duke Energy (DUKE) submitted an initial PMF report in 1992 which indicated that at the Oxford Dam would be overtopped by approximately 10-feet of water during the modeled PMF event. Given the duration and depth of the overtopping, significant damage to the facility and a possible breach could result. Therefore, modifications to the existing facility were necessary to satisfy the report of the PMF model."

Jan 1, 2005

By James J. Scott

Longwall mining has not received a great deal of attention in the United States; however, this system offers many advantages over the conventional room-and-pillar methods now being used. In order to conserve the coal resources of this country, the U. S. Bureau of Mines has investi¬gated the feasibility of adapting European longwall mining methods to American coal seams. Their studies showed longwall mining to be well suited to thinner seams and, greater depths; and, in addition, permitted almost 100 percent recovery of the coal. Most, experiments with this method resulted in higher overall production-costs than were commonly obtained with highly mechanized room-and-pillar techniques This high cost-was largely due to the excessive amount of labor required to maintain adequate roof support with conventional longwall mining techniques. With the substitution of hydraulic-powered, self-advancing roof support systems for conventional supports, this excessive labor cost has been decreased, and longwall mining costs are now competitive with those of modern room-and-pillar mining.

Jan 1, 1964

By C. L. Shapiro, R. Schempp

DuRing the past few years, general interest in the steel-producing and steel-consuming industries has been centered on the so-called "inherent characteristics" of steels. While often vaguely described, these characteristics are known to influence the response to heat-treatment and the hardening characteristics of the material. Although most of the recent papers and discussions have associated the "inherent characteristics" with the austenitic grain size and emphasized the importance of it, comparatively little is known of the variables that may affect the size of the austenite grain. The work to be described in this paper was carried out during the course of a study on the inherent characteristics of tool steel containing one per cent carbon. The discrepancies encountered in the determination and classification of the austenitic grain size led to an investigation of some of the variants influencing the austenitic grain size as determined by standard methods. Methods of Determining Austenitic Grain Size The present methods used for the determination of the austenitic grain size may briefly be classified in two groups: 1. Etching at room temperature to reveal the austenite grain size prior to cooling. 2. Etching at elevated temperatures, cooling to room temperature, and observing the structural conditions that existed at the temperature from which cooling occurred. The outstanding methods of the first group are: (1) the McQuaid-Ehn test, (2) optimum rate of cooling, (3) quenching and etching. McQuaid-Ehn Test.—This established and accepted test does not need much elaboration. It consists of pack carburizing at a definite temperature for a standard period of time and slowly cooling in the furnace. The temperature is 1700" F. (925' C.) and the time is 8 hr. The interpretation and evaluation of this test are fairly well defined in the A.S.T.M.

Jan 1, 1937

By P. L. Swanson

Stability analyses of fractured and faulted rock masses require delineation of the position, extent, and orientation of geologic discontinuities. The size of the smallest active discontinuity that may potentially be resolved using the spatial distribution of microseismic event locations is Limited by the accuracy and precision of the location methods. At a hard-rock mine in the Coeur D'Alene mining district of northern Idaho, two data sets consisting of calibration blast signals from a known source site and origin time and microseismic event signals were recorded using a stope-wide accelerometer array. These seismic signals are used to quantify various sources of error in event location. Five factors influencing source location errors are examined in this U.S. Bureau of Mines study: (1) biases of the numerical source location techniques, (2) receiver array geometries, (3) uncertainties in receiver positions, (4) errors in picking arrival times, and (5) uncertainties in seismic velocity structure, including the effect of mine openings. In addition, synthetic data (accelerometer positions, travel-time picks and wave velocity) are used to determine the effect of known systematic and random errors on source location calculations. It is shown that the commonly accepted association of minimum travel-time residuals with the best location solution does not necessarily hold true when there is a systematic error in seismic velocity. Recommendations are made for increasing the accuracy and precision of locations of microseismic events detected under similar field conditions.

Jan 1, 2010

By J. Hupka

Some aspects of kerosene penetration into tar sand have been investigated. The natural tar sand porosity was measured and used to analyze the performance of the hot water process. Subsequently, pretreatment experiments, using 20 kg tar sand samples (Asphalt Ridge and Whiterocks, Utah), and kerosene as a diluent were carried out at the expected summer temperature (26°C) and the expected winter temperature (-14°C). The natural tar sand porosity accessible by diluent has a crucial impact on the reduction of bitumen viscosity, and influences the penetration time required for successful bitumen separation from tar sand by hot water processing. Thus the tar sand porosity is an important variable which determines appropriate operating conditions. Experimental results indicate that diluent penetration into the Asphalt Ridge tar sand (high porosity) is almost complete after 30 min, whereas for the Whiterocks tar sand (low porosity) the penetration process is much slower, and still not complete after 15 hours regardless of the ambient temperature.

Jan 1, 1992

By H. Manurung, I. M. Bendiayasa, W. Astuti, and H. T. B. M. Petrus, F Anggara, K. C. Wanta

The leaching kinetics of cerium (Ce) and yttrium (Y) in sodium-hydroxide-digested non-magnetic coal fly ash using acetic acid were investigated. The variables analysed were pH, solid-to-liquid ratio (S/L), and temperature. The results show that cerium and yttrium's maximum recovery was 57.33% and 58.36%, respectively, under leaching temperature of 90°C for Ce and 60°C for Y at pH of 1,74 and 10 g/mL solid-liquid ratio in 240 minutes. Increasing the leaching time to more than 120 minutes did not significantly improve the results. After the magnetic separation process, the ICP-OES analysis shows a slight increase in the concentration of cerium and yttrium on nonmagnetic components. The XRD and ICP-OES analysis for the sample before and after silicate digestion shows that 40% silicate was dissolved. The calculation of apparent activation energies of leaching using the Arrhenius law for the leaching of cerium and yttrium gives 22.72 kJ/mol and 35.84 kJ/mol, respectively. The kinetic leaching model of cerium and yttrium all fit Dickinson's new shrinking core model. The calculation results show that the leaching reaction is controlled by combining interface transfer and diffusion across the product layer.

Nov 6, 2024

By Andrea Zanon

Slitting processes have been used for many years to increase the productivity of smaller diameter deformed bars, without making major investments in the rolling mill. This technology is used mainly for the production of reinforcing bars (7-20 mm diameter), but successful applications exist also for round bar production. The multi-slitting process enables to produce up to 5 bars starting from one billet, thus increasing the productivity of the smaller products. Danieli Morgårdshammar, world leader in the supply of rolling mills for long products, has been a front-runner in slitting technology since its first applications and has recently developed, first in the world, the technology to produce 5X8mm rebar. This process has been recently applied in BRSM steel, a company based in Bangladesh which is a worldwide benchmark for slitting technology performances. This paper presents the necessary modifications which need to be considered when developing a 5-strand slitting project (and multi-strand slitting projects in general), as well as the results obtained at BSRM Steel when the process was implemented in 2016, the first rolling mill in the world rolling 5X8 mm slit rebars.

Oct 30, 2017

By F. O. Garrabrant, F. S. McNicholas, Robert Henderson, R. U. King

Several years ago, it was decided to experiment with the use of high-pressure water to bring in finger hangups and reduce the amount of secondary blasting necessary. It was argued that the velocity effect of the high-pressure water would bring down hangups without unduly wetting the ore. Water under a head of about 550 ft. was installed in certain slusher drifts. Ordinary ¾ in. water hose, with a nozzle opening of % in., was used, and water was impinged on the fines under a hangup. Results were excellent. About half the total number of hangups were brought in with high-pressure water without blasting and the cost of this part of the slushing operation was reduced about 50 per cent. Operations were speeded up, dust counts and safety hazards were reduced, and a more desirable working place was secured. The additional water added to the ore was under one per cent and caused no inconvenience in slushing, haulage, or crushing operations. Usually the ore would absorb all of the water, so that none of it would enter the loading drifts. The entire mine, developed by slusher drifts, is being equipped with high-pressure water. Heating Mine by Compressor Cooling Water Several years ago, the problem of heating certain sections of the mine during freezing weather became important. It was calculated that there was sufficient heat in the compressor cooling water to heat the incoming ventilating air current to above freezing, if such heat could be transferred from the water to the air. All schemes of radiation from pipe were rejected as too cumbersome, costly and impractical. It was thought that by spraying the heated water from the compressor cooling system into the incoming air, a satisfactory heat exchange could be accomplished. The only objection was that the sprayed water would freeze and might fill the air-intake drift. However, when water at about 75° to 80°F. was sprayed at the rate of 200 gal. per minute through a bank of sprays into the incoming and freezing air current, this air was thereby heated to above freezing; and although some ice was built up in the air drift, the amount was not objectionable. Occasionally the built-up ice was picked down into the outgoing water stream, which removed it. The entire south and westerly parts of the mine were prevented from freezing. Concreting for Hangups Considerable trouble was experienced in securing hangups of fine ore in slusher fingers that needed repairing. Regular methods of timbering were unsatisfactory. Now, a slab of concrete is poured over the top of the muck by Pumperete machine, almost filling a finger, which gives a satisfactory slab to work under for making the needed repairs. Derailers Some trouble has been caused by motor-men not observing safety lights and

Jan 1, 1946

By J. Aravena, S. Gajardo, M. Ayala, P. Salinas

Both, Teck Carmen de Andacollo (Teck CDA) and Orica, work hard in the implementation of new technologies available in the explosives industry and drilling and blasting techniques, with the objective of sustainable development of their operations, regeneration, and protection of the environment, also considering the welfare and relationship with the surrounding communities. The open-pit Carmen de Andacollo mine is located adjacent to the town of Andacollo. Therefore, both companies together have developed the implementation of different techniques and technologies to mitigate the impacts of mining operations in the community, considering an important part of this challenge to minimize the impact of their perception of blasting by reducing the level of vibrations and sound pressure (airblast), in addition to the control of dust and smoke, strengthening sustainable production in harmony with communities. The technologies and techniques that have been implemented are the installation of airblast and vibration monitoring stations stands out, whose database has records since 2011. Using the vibration database, different models were developed to predict the vibration level of blasting in its design phase, achieving a difference of 4.1% between the estimated and measured values in the last year. Two techniques stand out to minimize the ejection of material, "Hydraulic Dome" and "Dual layer blasting", the first consists of water irrigation on the surface to be blasted and the second is an unconventional blasting technique, which was awarded in 2015 for its results in the environment. Also pre-splitting engineering has been modified in a positive evolution, where through different configurations, the airblast has been reduced by 15% compared with records from 2011 to 2022. Finally, due to the impact of operational restrictions, such as days available to blast, number of holes, and powder factors, the wireless initiation technology was implemented, which allowed reducing the limitations in the loading, generating an improvement in terms of blasted materials over conventional systems. Understanding the restrictions and challenges in terms of impact on communities, the correct implementation of all these techniques is important, and in conjunction with collaborative work, it has been shown and validated that producing in a sustainable and sustainable manner is possible.

Jan 1, 2024

By W E. vanSteenburgh

The Polar Continental Shelf Project was initiated in 1959 to provide an administrative and logistic vehicle for research in the physical sciences of the land, sea and channel area of the Arctic Archipelago. Most of the scientists are supplied on secondment from the professional branches of the Department. The yearly expeditions number some eighty scientists and sub-professional staff, and they are supported by a fleet of fixed-winged aircraft and helicopters. Accurate positioning is obtained by the use of a Decca Lambda navigational system which is moved as the area of interest is shifted. The Project is designed to accommodate not only physical scientists, but to provide facilities for other scientist who may have an interest in the area under study. The main research scope of the Project includes topographical surveys, hydrography, oceanography, geology, including marine sedimentary studies, gravity, magnetics, seismology, glaciology and geography. The Polar Continental Shelf Project was initiated and recommended by the Committee on Northern Development in 1958.

Jan 1, 1963