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By George W. Riter

(Canal zone meeting, November, 1910.) A DISTINGUISHED engineer, the active head of a large mining company, has said that surveying attains the dignity of a profession only in the hands of a few men-the few who know how to keep notes that will be understood by even a novice without further word of explanation. Of all mine-records, survey notes are perhaps the most important. The maps made from them serve as a working-guide, and as framework for other data ; and when, from any cause, access to underground workings is shut off, the surveyor's record often becomes invaluable. So seldom does a surveyor have a chance to check underground surveys by making a closure, that he is compelled to rely on the precision of each step of his work for the accuracy of the final result. When data are fully recorded on the spot, the notes, even in the hands of second parties, become evidence of the care and precision with which the surveying was done. It is worth a great deal to be able to pick up the work of a former surveyor where it was left o$; and to be able to carry it forward without retracing from the beginning. The purpose of this paper is to describe the survey-note system of a mine now under my direction, in which underground surveys had to be relied upon entirely for the proper division of rich ore-bodies between neighbors, thereby placing a premium on accurate surveying and permanent records. In survey-work, it soon turns out that paper is the least item of expense, and that little is gained by trying to economize note-book space. For many purposes it is best to record notes on cards or loose-leaves, which may be left in the office at the end of the day's work, and need not be carried into the mine again, there to become smeared with grime and grease. With the loose-leaf or card system, all notes relating to the same local-

Apr 1, 1911

By de Vaux. Deryck, Natalie J. Shackleton, Vratislav Malysiak Cyril T. O. Connor

"The major losses of PGM and base metals in the beneficiation of platinum group deposits occur during the separation of gangue from the value minerals by selective flotation. A number of studies have shown that this negative impact on flotation is due to surface passivation, caused by various ions that may originate from the external water supply or, as is likely in the majority of cases, from the oxidation of the mineral surfaces and the grinding media. This investigation aimed at reducing surface passivation of pentlandite and inadvertent activation of pyroxene, thereby improving ultimate valuable mineral recovery and selectivity. Both synthetic minerals and plant ores were studied in order to determine the effect surface passivation and inadvertent activation have on mineral surface alteration and floatability. Zeta potential determinations, microflotation, ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) analyses, laboratory batch flotation tests and continuous flotation testwork were used as tools to study the surface alteration and/or floatability.Zeta potential determinations and ToF-SIMS analyses showed that copper adsorption is non-selective. Both pentlandite and pyroxene become copper (II)-activated in the presence of copper sulphate and subsequently, in the presence of xanthate, adsorption of the collector will occur onto copper activated mineral surfaces. Zeta potential determinations also showed an alteration of the surface charge in the presence of polyphosphate, thereby inhibiting surface passivation of sulphides by slime coatings due to surface repulsion.The addition of diethylenetriamine (DETA) reduces the copper concentration on both minerals, predominantly on the pyroxene surfaces and polyphosphate further enhances the selectivity at pH 6.The microflotation and batch flotation data obtained has shown a significant improvement in the ultimate flotation response of valuable mineral recovery and concentrate grade compared to the standard reagent regime, while the continuous flotation results significantly improved the selectivity, however, at a similar ultimate recovery."

Jan 1, 2003

By J A. Meadows, M G. Annandale, G Castelain

Bauxite mining on Cape York Peninsula (CYP) commenced in the early 1960s in the region surrounding the town of Weipa. Rio Tinto Alcan (RTA) operates its bauxite mines on the homelands of 11 Indigenous Traditional Owner groups. The mining activity currently operates under three Aboriginal Agreements including an Indigenous Land Use Agreement – the Western Cape Communities Coexistence Agreement (WCCCA) – which provides RTA with access to the land in return for a range of benefits to the Traditional Owners, including employment, training, royalty payments and future relinquishment of the land (Klimenko and Evans, 2009). Despite reports of some ‘good progress’ in meeting the terms of the WCCCA (Klimenko and Evans, 2009, p 5), many of the region’s Traditional Owners remain dissatisfied. Two key areas of Indigenous community concern are the current premining management practices and the outcomes of post-mining landscape rehabilitation efforts.CITATION:Annandale, M G, Castelain, G and Meadows, J A, 2016. Sustainable mining – indigenous community benefit, in Proceedings Life-of-Mine 2016 Conference, pp 173–175 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By M Hitzman, E P. Nelson, J Skarmeta

The Coastal Cordillera of northern Chile hosts the youngest and possibly best preserved iron oxide copper gold (IOCG) belt yet discovered and includes important deposits such as Candelaria and Mantoverde. The spatial and temporal relationships of hydrothermal alteration and mineralisation (Fe and Cu-Au) related to structural and lithologic features were investigated through geologic mapping and petrographic and geochronological studies along two W-E-transects crossing the Coastal Cordillera to the north of Vallenar. The project aimed to determine vectors for district-scale and regional exploration. Along with magnetite-apatite deposits (Central Iron Belt) and manto-type copper deposits, the IOCG deposits are hosted in a N-trending volcano-sedimentary sequence formed in a Jurassic to Early Cretaceous arc/back-arc setting (Sillitoe, 2003; Ramos and Alemßn, 2000). Calc-alkaline plutonic rocks intrude and metamorphose the volcano-sedimentary sequence, and become progressively younger from west to east reflecting a shift of arc magmatism (to Paleocene in the far east). From west to east along the Agua Grande-Chehueque profile, four domains of different economic potential are recognised. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By R. L. Levens

Researchers at the U. S. Bureau of Mines conducted investigations to evaluate the potential for ground water contamination by mine waste used as backfill. Samples of cemented waste backfill and water discharging from drillholes and seeps were collected to use in chemical analyses and laboratory tests to determine the physical and chemical factors that control release of heavy metals to ground water. Greater water retention by cemented backfill (as compared to uncemented sandfill) reduces the surface area exposed to oxidation, which in turn reduces the amount of acid produced. The acid is neutralized by the cement and minerals contained in the backfill. The grain-size distribution of tailings used for backfill affects the structural integrity of cemented backfill under attack by acidic water; breakdown of the backfill structure releases neutralizing materials faster. Backfilled stopes in rock with low hydraulic conductivities will constitute preferential flow paths after mine flooding; however, the rate of flow through backfill will be much slower than when the stope is partially saturated during mine operation. Considering all factors, acid generation and release of metal ions from cemented backfill should be less than in uncemented sandfill.

Jan 1, 2010

The impact of moves to introduce Abori- ginal land rights was felt in the Northern Territory as early as 1972 when the Federal Government froze the processing of all appli- cations for mining interests over vacant Crown land. The Aboriginal Land Rights (Northern Territory) Act was finally proclaimed on Aust- ralia Day 1977 and since that date the mining industry and the Territory legislature have struggled to make the Act work. Despite these efforts long delays have been experienced by those required to negotiate mining and explor- ation agreements under the Act. In fact explor- ation on Aboriginal land has been effectively stiffled since the introduction of the Abori- ginal Land Rights Act. The Northern Territory government and the mining industry have both sought amendment to the Act to remedy some of its more onerous problems. These efforts have generally been fruitless. Some of the recommendations put forward by Mr Justice Toohey following his recent review of the Act would provide relief in some important areas. However, any such improvements are more than offset by a number of Mr Justice Toohey's recommendations which would severely disadvantage the vast majority of Territorians. A recent survey of mining companies seeking exploration licences over Aboriginal land indicates that many of the existing diffi- culties could be overcome without significant amendment to the Act but rather by the adoption of a positive administrative approach by the Land Councils. It is now up to the Commonwealth and the Land Councils to demonstrate that their Act can work without crippling the Northern Territory economy and its mining industry.

Jan 1, 1984

By Bahaa Hussein

Considerable number of methods and procedures has been introduced for trending and progress reporting of engineering, procurement and construction projects. This paper introduces a novel method, designed to augment the set of indices for measuring schedule performance. The concept behind the developed method is to provide early warning by dynamically evaluating the schedule cumulative impact of construction projects. The proposed method is designed to highlight the gradual deterioration in schedule status resulting in a cumulative impact due to the aggregation of small delays encountered during the execution of non-critical activities, and can be used as an add-on utility to existing software systems that perform CPM scheduling. The proposed method is based on a developed formulation for quantification of the Schedule Compression Index, which takes into consideration the remaining project activities durations. The index is developed based on periodic comparisons of ?Current Schedules? and the project ?Baseline Schedule? using the summation of the remaining activities durations. A numerical example is presented to demonstrate the application and capabilities of the developed method. It is expected that the developed index together with other schedule performance indices would be of value to decision makers and members of project teams.

Aug 1, 2013

By Elliot P. Rexford

IN the early days of concrete construction, the question of quality of sand or gravel to be used as aggregate in concrete was given little or no consideration. If the construction engineer had sufficient quantity for his structure within a reasonable distance, he was contented and gave no thought to the possibility that the material might have adverse physical, chemical, or thermal properties which could cause future deterioration of his concrete and possible failure of his structure. Today a very different situation exists. With the building of larger and larger concrete structures, with a longer and longer life expectancy, the quality of the aggregate material has become of major importance. Even in small concrete structures aggregate quality cannot be passed off lightly and the quality of the aggregate must be such as to give the anticipated life without costly maintenance. The first question to arise in the selection of an aggregate is what makes a sand or gravel suitable or unsuitable for use in concrete, and how can its quality be judged. No one rock type can be depended upon to furnish sound durable material in all instances. Granitic rocks, for example, make very satisfactory aggregates in some cases, but they are among the most unsuitable of materials when they are fractured, weathered, or highly micaceous. Limestones make excellent concrete aggregates on the one hand, and on the other they may be unsound and lack durability if they contain appreciable clay, they may have a harmful chemical reaction with the cement if they contain amorphous silica, or they may have thermal characteristics which make them highly unsuitable for use in concrete. Each rock, gravel, or sand must be proved on its own merits for the particular job under consideration. The selection of suitable aggregate materials may be divided into two major phases, the geological phase which is carried on largely in the field, and the testing phase which of course is a laboratory problem; both are important. Very often the geological phase alone is sufficient for the selection of satisfactory aggregates for minor structures but for major structures both phases must be thoroughly investigated. Geological Phase In the southwest part of the country nearly every major rock type, igneous, metamorphic, and sedimentary, may be found with all imaginable intermediate phases and in all imaginable stages of alteration. Frequently very different rock types, different as to geological age, composition, and condition occur very close together. Alluvium and stream-bed sands and gravels will consist of many different rock types and even ledge rocks may vary radically as to texture and composition within the area of a quarry site. Some of the rocks make suitable aggregate materials whereas others are highly deleterious in concrete. Too often the good and the bad occur together and more than ordinary caution is required in aggregate selection. Aggregate Sources: Concrete aggregates are usually obtained from stream-bed sands and gravels or from ledge rocks. Each has certain favorable and unfavorable characteristics and it is sometimes necessary to investigate both types to determine the most suitable source for a specific structure. Stream Beds: The predominant sources of aggregate materials in southern California and Arizona are stream beds. Vast quantities of sands and gravels are brought from the mountain ranges by the rivers during times of flood but most of these streams are dry a large part of the time and hence these deposits make easily accessible sources of aggregate materials. From many standpoints stream-bed materials make very acceptable aggregates. The gravel pebbles and the sand grains are

Jan 1, 1951

By Elliot P. Rexford

IN the early days of concrete construction, the question of quality of sand or gravel to be used as aggregate in concrete was given little or no consideration. If the construction engineer had sufficient quantity for his structure within a reasonable distance, he was contented and gave no thought to the possibility that the material might have adverse physical, chemical, or thermal properties which could cause future deterioration of his concrete and possible failure of his structure. Today a very different situation exists. With the building of larger and larger concrete structures, with a longer and longer life expectancy, the quality of the aggregate material has become of major importance. Even in small concrete structures aggregate quality cannot be passed off lightly and the quality of the aggregate must be such as to give the anticipated life without costly maintenance. The first question to arise in the selection of an aggregate is what makes a sand or gravel suitable or unsuitable for use in concrete, and how can its quality be judged. No one rock type can be depended upon to furnish sound durable material in all instances. Granitic rocks, for example, make very satisfactory aggregates in some cases, but they are among the most unsuitable of materials when they are fractured, weathered, or highly micaceous. Limestones make excellent concrete aggregates on the one hand, and on the other they may be unsound and lack durability if they contain appreciable clay, they may have a harmful chemical reaction with the cement if they contain amorphous silica, or they may have thermal characteristics which make them highly unsuitable for use in concrete. Each rock, gravel, or sand must be proved on its own merits for the particular job under consideration. The selection of suitable aggregate materials may be divided into two major phases, the geological phase which is carried on largely in the field, and the testing phase which of course is a laboratory problem; both are important. Very often the geological phase alone is sufficient for the selection of satisfactory aggregates for minor structures but for major structures both phases must be thoroughly investigated. Geological Phase In the southwest part of the country nearly every major rock type, igneous, metamorphic, and sedimentary, may be found with all imaginable intermediate phases and in all imaginable stages of alteration. Frequently very different rock types, different as to geological age, composition, and condition occur very close together. Alluvium and stream-bed sands and gravels will consist of many different rock types and even ledge rocks may vary radically as to texture and composition within the area of a quarry site. Some of the rocks make suitable aggregate materials whereas others are highly deleterious in concrete. Too often the good and the bad occur together and more than ordinary caution is required in aggregate selection. Aggregate Sources: Concrete aggregates are usually obtained from stream-bed sands and gravels or from ledge rocks. Each has certain favorable and unfavorable characteristics and it is sometimes necessary to investigate both types to determine the most suitable source for a specific structure. Stream Beds: The predominant sources of aggregate materials in southern California and Arizona are stream beds. Vast quantities of sands and gravels are brought from the mountain ranges by the rivers during times of flood but most of these streams are dry a large part of the time and hence these deposits make easily accessible sources of aggregate materials. From many standpoints stream-bed materials make very acceptable aggregates. The gravel pebbles and the sand grains are

Jan 1, 1951

By I. A. Mutemererwa

This paper investigates the role of vertical integration between chrome ore mines and ferrochromium smelters in the location of ferrochromium production capacity in South Africa and Zimbabwe. Vertical integration is important in understanding the increasing competitive position of these two countries as observations show that an increasingly larger share of the global market has been coming from integrated producers. The paper argues that the increased vertical integration between mines and smelters in South Africa and Zimbabwe has led to a lower cost of chrome ore as an input compared with other producers. Underlying this hypothesis is the basic tenet that, more likely than not, production will take place where the costs are lowest. The paper concentrates on high carbon ferrochromium (HCFC) production in market economy countries (MEC). Using an ordinary least squares model, the study tests the relationship between low chrome ore costs and vertical integration shows a statistically significant relationship. These findings partially support the view that the control of sources of chrome ore is a major source of competitiveness. Keywords: competitiveness, ferrochromium (ferrochrome), ordinary least squares, dummy variables, vertical integration, southern Africa.

Jan 1, 2000

By D. Moradkhani

The objective of this research was, to evaluate the hazard of heavy metals in the soil around the National Iranian Lead & Zinc (NILZ) Company. In this study, 38 samples of soil around the NILZ factory were collected using standard sampling method, so that, the heavy metals Pb, Zn, Cd and Cr have been evaluated. The concentration of heavy metals were measured and compared with standard limits. The results show that the hazard of heavy metals in soil is not so serious and the content of Pb in just 5 percent of samples, and the content of Zn in just 3 percent of samples were above standard limits and the concentration of Cd and Cr were under the standard limits. Average, variance and standard deviation of the elements are calculated and with due attention to the standard deviation, Pb and Zn are seen to be more distributed than Cd and Cr. Also the isograde curve of heavy metals was drawn using software called Surfer. These curves showed that the heavy metals are concentrated at particular distances from the factory. Keywords: heavy metals, remote sensing, sampling method, isograde curve, Surfer software

Sep 1, 2012

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014

By Noel C. Joughin

In making judgements on tolerable levels of risk in industry, and in all spheres of life, it needs to be understood that every action gives rise to risk. Without risk, nothing can be done. Without risk, no economy could be advanced. There is a strong tendency to emphasize the risk at work, but persons who are not working are exposed to a different set of risks. Often persons who are not working face greater risks than persons who are working. Simply, in being alive, one is exposed to the risk of an accident, the risk of contracting a disease, and an extremely diverse variety of other risks. According to the Health and Safety Executive of the UK, it is not possible to have a state of zero risk, because ?a state of zero risk does not exist?. Because zero risk is a physical impossibility, it is not possible to design for a state of zero risk in all engineering design. While the strategic target of achieving zero risk is laudable it does not provide any practical guidance to engineers as to what acceptable limits of risk should be. This causes a significant and real problem in the design for and the management of risk. Without meaningful guidelines, engineers, managers and the authorities often find themselves in disagreement. Thus, it has become essential to establish criteria for tolerable levels of risk and unacceptable levels of risk in order to design and manage engineering systems properly.

Jan 1, 2011

By J. L. Ellenberger, T. Miller

"A limestone mine in Ohio has had roof instability problems that have led to massive roof falls extending to the surface. This paper describes a collaborative study of these events undertaken by the National Institute for Occupational Safety and Health and the mine owners. The study focuses on the roles that weak, moisture-sensitive floor and weak bands in pillars play in a general instability that led to roof falls at this mine. The NIOSH Stone Mine Pillar Design software (S-Pillar) does not include analysis for weak floor or weak bands and recommends that when such issues arise they should be investigated further using a more advanced analysis. It is important to recognize that without the impact of the floor or weak bands, the calculated inherent stability factor for these pillars is within the recommended design range. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3D numerical models were employed to help determine the failure mechanism. Roof-to-floor extensometers were also installed in the areas predicted to have further instability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface. This recent case demonstrates that weak floor can be a significant factor in pillar stability and should be assessed during the design stage of the mine.To an area-wide failure (Zipf, 2001). In that case, it appears that the pillars had actually remained intact. However, moisture-related yield of the weak floor caused deformations which passed through pillars and into the roof, triggering roof collapse around the intact pillars (Esterhuizen et al., 2011). This previous case and the case presented in this study, while not identical, both demonstrate that weak floor and/or bands within pillars can be a significant factor leading to instability."

Jan 1, 2015

By José Luis Calderón

En los tres anexos (Pueblo Nuevo, Zarumilla y Chuquitambo) del área de influencia directa (AID) de Compañía Minera Poderosa se ha institucionalizado y formalizado una nueva gestión del agua de consumo poblacional, lo que ha permitido prevenir conflictos socioambientales y mantener la estabilidad social que posibilita el normal desarrollo de las operaciones mineras en el distrito de Pataz, región La Libertad.

Jul 30, 2019

By Gregory E. Smith

"Tensionable headed roof bolt systems are common in the U.S. mining industry. In the last 15 years or so, they have made a comeback as a hybrid system where a mechanical anchor is used in conjunction with resin. When such a system is used, it is common to use a spherical washer to comply with the requirements of 30 CFR Part 75.204(f)(8). This standard requires an angle-compensating device be used in installations where the bearing plate is offset from the roof bolt axis by an angle greater than five degrees. This paper evaluates system performance of four different traditional angle-compensating device/plate combinations including a new patented extruded plate/extruded washer system that improves overall load capacity and stretch.INTRODUCTIONA large western U.S. underground coal mine was using a fully grouted headed rebar system as their primary support. They had developed their component specifications over many years of working with suppliers to improve and optimize these components to integrate well as a system. As shown in Figure 1, the components included a patented 7 /8"" -diameter Grade 60 headed rebar bolt with a flange capable of full bar load (Walker, 2009) and a patented 8 in x 8 in Grade 3 extruded hole bearing plate manufactured by DieMatic Corporation.The mine decided to pursue a fully grouted tensionable system using a mechanical anchor as the tensioning device. Their primary goal was to eliminate the need for the roof bolt operator to secure (hold) the bolt during resin set time. An additional benefit was the increased initial tension on the bolt. To comply with the requirements of 30 CFR Part 75.204(f)(8), regarding tensioned roof bolts, they were required to include an angle-compensating device because a share of the bolt population would be installed at angles greater than five degrees from the perpendicular to the bearing plate. Also, to improve cycle time and torque/tension consistency, the mine desired to have the washers and anchors assembled at the factory. This required the use of a bearing plate with a center hole large enough to accommodate the 1-3/8-in-diameter mechanical anchor to pass though it during assembly by the roof bolt operator. The mine wanted to continue to use an extruded hole bearing plate in the tensionable system, and EMS was asked to propose a plate and angle-compensating device."

Jan 1, 2016

By F G. Cooke

"This paper describes a medium-sized copper mine's results in making innovations and changing operational practices to combat increasing expenditures due to higher labour and supply costs, extended workings, scarcity of experienced manpower and problems created by deteriorating ground conditions.OPEMISKA COPPER MINES (QUEBEC) LIMITED is located at Chapais in the Chibougamau area, in central eastern Quebec, approximately 300 miles north of Montreal and 150 miles north west of Lake St. John. The latter area, developed by lumbering and farming, has supplied the majority of the employees, who, with training and experience and a desire to work and improve themselves, have become the backbone of the Company's 600 personnel.Opemiska began production in 1954 at a rate of 400 tons per day, using diesel power and road transportation. The rate was progressively increased and, by 1959, with hydro-electric power and rail transportation, the mine had reached its present production rate of 2,000 tons per day. It has produced concentrates containing over 430 million lbs of copper."

Jan 1, 1968

By U. Schoepf

Economic and at the same time environmentally acceptable mining of small vertical ore bodies and veins to great depths has always been a challenge for miners. The Bauer cutter system, widely used in civil engineering, has been further developed for applications in exploration and mining, to a sustainable system for selective mining with a focus on small vertical ore bodies and veins, as well as residual ore in open pit operations. Current situation of conventional mining of small ore bodies and vertical veins Small ore bodies and vertical or near-vertical ore veins often pose a challenge to the mining industry. The relatively small size of the ore deposit over great depths or lengths, with only limited exposure to the surface makes economical mining difficult. Open pit mining of such ore bodies must either be terminated early because of the high stripping ratio and the enormous environmental impact or is unprofitable from the very beginning. The required massive stripping of waste rock leads to high material hauling times and costs, intensive roadway and bench construction and maintenance, possible safety hazards due to heavy vehicle movement, pit wall stability risks, intensive surface water management and massive waste dump requirements. In addition, it can be assumed that increasingly extensive rehabilitation measures will be required in the future after mine closure. Particularly in vertically oriented magmatic and hydrothermal deposits the technical, economic and environmental limits for further pushbacks, to extend the open pit depth, can lead to an early end of mine life even if a significant quantity of residual ore is left behind. Going underground is only a viable option in a limited number of mines with very high ore values and volumes. The high development cost of an underground mine, as well as the higher underground mining costs, often prevent further mining to greater depths.

Feb 1, 2023

By Sheng-li Wu, Guo-liang Zhang, Bo Su

One of the major challenges for the Canadian Gen IV Super-Critical Water-cooled Reactor (SCWR) concept is the selection of fuel cladding materials. The Canadian SCWR concept will operate at a core outlet temperature of 625 oC and 25 MPa of pressure with peak cladding temperature reaching as high as 800 oC. Corrosion resistance is an important factor for material selection. Austenitic stainless steels that contain Cr contents greater than 18 wt.% are generally considered to provide adequate corrosion resistance. In this work, the pressure dependence of the corrosion of austenitic stainless steel 310 containing 24 wt% Cr is assessed at 625 C for exposures of 1000 hours to evaluate the suitability of superheated steam as a surrogate for supercritical water at 25 MPa. Transmission Electron Microscopy (TEM) revealed that 310 exposed to different pressure conditions at 625 oC. (i.e., 0.1, 8 and 29 MPa) had generally the same type of the oxide structure, i.e., a Cr-rich oxide with the spinel structure on outer surface adjacent to the water phase. The material exposed at 8 and 29 MPa had a double layer oxide structure, with the outer oxide layer having a much larger grain size, while the samples exposed at 0.1 MPa showed only a single spinel-phase oxide layer. Cr-depleted recrystallized austenite grains were found underneath the spinel phase oxide. The adjacent large-grained austenite substrate had M23C6 carbides in the grain interior. The implications of these results are discussed.

Jan 1, 2015

By G. W. Grove

The Joseph A. Holmes Safety Association acid the Holmes Association have fostered many chapters that have served as a medium in increasing safety in the mining industry. Details relating to the formation, operation, and achievements of the J. J. Forbes District. Council of the Holmes Safety Association, which operates in the Uniontown-Brownsville bituminous coal district of western Pennsylvania will be of interest to all who are striving to increase safety in mines, quarries, and in the oil fields. The Joseph A. Holmes Safety Association The Joseph A. Holmes, Safety Association' was organized in 1916 by 24 of the leading technical societies and mining organizations to perpetuate 'the memory of Dr. Joseph Austin Holmes, first Director of the United States Bureau of Mines.

Jan 1, 1929