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By Mark E. Schlesinger

Engineering design follows a six–step sequence. Demonstration of this sequence in materials engineering is less common. A case study is presented, using the 1989 paper by Gafner on the development of 990 gold-titanium alloy. This paper identifies a need, develops the problem, identifies alternatives, demonstrates the use of metallurgical principles to identify alternative responses, and shows how more favorable options are selected. The paper can also be used to illustrate engineering design as an iterative process. The paper is also useful as a starting point for more in-depth examination of specific elements of the design process, and lends itself to the creation of student exercises.

Jan 1, 2014

The district specially referred to in this paper comprises the very gently sloping country extending from the western shores of Port Phillip from the mouth of the Yarra to Footscray along the Bacchus Marsh railway to near that town thence in a southerly direction to the Little River, and along that river to the coast, 1 as may be seen on the accompanying map. Almost the whole of this area is covered by volcanic rocks, consisting of pumerous sheets of basalt, which have been poured out of various volcanic hills in the districts, such as Mts. Atkinson and Cotteril, near Melton; Mt. Maryand Bald Hill, 12 and 16 miles respectively N.W. of Werribee; and vents in different parts of the parishes of Tarneit, Mouyong, Mooradoranook, Pyweitjorrk, and Derrimut. These volcanoes were in an active state of eruption during a late period of the earth's historyprobably the late Pliocenll, or still younger Pleistocene.Occupying a narrow strip of country, for most of the distance along the coast from Williamstown to past the mouth of the Little River, there occur deposits of still younger age, belonging to the Recent period. These lie on the basalt, and extend for distances varying from a few chains to more than a mile back from the beach. They comprise superficial deposits of blown sand, and raised beaches, composed of marine sands...

Jan 1, 1902

By Erik Sundström, Magnus Nygren

The study explores the influence and consequences of safety initiatives on the development of safety cultures in the Swedish mining industry. It involves interviews with experts from four mining organizations, highlighting themes such as organizational structures, safety leadership, feedback, and communication.

Nov 1, 2023

By John Rajala

The Otjikoto Gold Mill was commissioned during November–December 2014 as Namibia’s first new gold producer in 30 years. Its operations consist of surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and gold recovery. The initial mill design capacity was 2.5 Mt/a. Its capacity was expanded after nine months of operation to 3.1 Mt/a, and process performance has significantly surpassed design expectations. After startup, the Otjikoto Mill’s throughput and gold recovery ramped up quickly, with both parameters exceeding design after only two months of operation. The robust process performance continued into 2019, with key performance indicators (KPIs) eclipsing design values in almost every aspect of mill operation. The Otjikoto Mill’s gold recovery is exceptionally high, exceeding 98 percent every year following startup, especially considering the low-grade nature of the deposit.

By Thomas D. Kelly

In 1900, the average U.S. citizen’s average life span was 47 years. He traveled about 1,900 km (1,200miles) in a lifetime and resided in a home with an ice-box for food storage and oil or gas for lighting. He communicated by mail, telegraph and crude telephones with limited availability and range. By 2000, the average citizen’s life span was 77 years. He traveled an average of 19,000 km/a (12,000 miles/year) by automobile alone. He resided in a home with many electrical appliances, including refrigerators and electric lights. And he communicated almost instantaneously with any other part of the globe by several widely available means, including portable phones and e-mail.

Jan 1, 2002

By I. H. Warren, Forward F. A

The reduction of aqueous slurries of uranyl carbonate at elevated temperature with compressed hydrogen m the presence of metal catalysts and certain organic promoters has been shown. to yield uranium dioxide. The reduction takes place in a sequence of steps. The purity and sintering properties of the dioxide make it of interest as a starting material for fuel element production. Simple control can be exercised over the surface area and oxygen/uranium ratio of the product during reduction. URANIUM dioxide for fueling atomic power reactors 1s conventionally produced as a powder by simultaneously decomposing and reducing ammonium diuranate with hydrogen in a furnace at high temperature. Fuel elements are then generally made from this powder by compacting and sintering ( 1). In order that elements approaching theoretical density may be obtained,

Jan 1, 1961

By Patrick J. Coleman, John C. Kerkering

Problem: Mining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injury rates over the last century. Coal mine fatality rates, for example, have dropped almost a thousand fold since their peak in 1908. While incidence rates are very important indicators, lost worktime measures offer an alternative metric for evaluating job safety and health performance. The first objective of this study examined the distributions and summary statistics of all injuries reported to the Mine Safety and Health Administration from 1983 through 2004. Over the period studied (1983 2004), there were 31,515,368 lost workdays associated with mining injuries, for an equivalent of 5,700 person years lost annually. The second objective addressed the problem of comparing safety program performance in mines for situations where denominator data were lacking. By examining the consequences of injuries, comparisons can be made between disparate operations without the need for denominators. Total risk in the form of lost workday sums can help to distinguish between lower and higher risk operations or time periods. Method: Our method was to use a beta distribution to model the losses and to compare underground coal mining to underground metal/nonmetal mining from 2000 to 2004. Results: Our results showed the probability of an injury having 10 or more lost workdays was 0.52 for coal mine cases versus 0.35 for metal/nonmetal mine cases. In addition, a comparison of injuries involving continuous mining machines over 2001 2002 versus 2003 2004 showed that the ratio of average losses in the later period to those in the earlier period was approximately 1.08, suggesting increasing risks for such operations. Discussion: This denominator free safety measure will help the mining industry more effectively identify higher risk operations and more realistically evaluate their safety improvement programs. Impact on Industry: Attention to a variety of metrics concerning the performance of a job safety and health program will enhance industry's ability to manage these programs and reduce risk.

By P K. Banerjee, S Kumar

Indian iron ores with less than 62 per cent Fe are currently unexploited, except for a few sectors which export them to foreign countries. It is anticipated that by 2012 the countryÆs domestic steel production is likely to rise to the tune of 60 million tonnes per annum. To meet this requirement, it is necessary to utilise not only the existing high-grade deposits but it is also necessary to look into exploiting the leftover iron ores of lower grades. Hence, reserves with Fe content 62 per cent and below (particularly the ores with In the present paper, an attempt has been made to beneficiate three different types of low-grade iron ores selected from three different parts (states) of the country. In the paper, alternative routes for beneficiation and effective utilisation have been tested using different techniques in the laboratory in an attempt to match their (Al2O3/SiO2) ratio after thorough characterisation and liberation studies. The paper also encompasses the geological formations, occurrences and distribution of Indian iron ores as well as highlighting the problems associated with the fines, possible metallurgical routes, and their market segregation from the perspective of end users.

Jan 1, 2007

By N. Romani, R. Provost

"Commissioning of a circulating dry scrubber (CDS) plant was recently completed at an existing facility in Québec, Canada. The CDS plant treats the sulphur dioxide off-gas emitted from rotary kilns in order to meet increasingly stringent environmental requirements. This installation enables the existing facility to reduce their sulphur emissions by over 90%.Proper planning of the different commissioning stages and staffing an integrated team are the most important factors required for a successful plant start-up. A strong Operational Readiness plan must be in place as early as the start of construction in order to ensure a smooth transition from commissioning to operations. Plant performance can meet or exceed performance criteria within the required timeframe if the proper group dynamic and good communication is established between construction, commissioning and operations teams.The road blocks encountered are often from systems that one assumes will operate without trouble such as air-conditioning, or design assumptions that were taken years earlier in feasibility process stages, namely the capacity of existing systems that will connect the new plant to the existing facilities. The challenges associated with rectifying these issues in addition to the requirements to properly start-up and operate a new plant without impacting production are great, and it is imperative to have the necessary resources to react quickly to any problems.IntroductionCommissioning of a circulating dry scrubber (CDS) plant was recently completed at an existing facility in Québec, Canada. The CDS plant treats the sulphur dioxide off-gas emitted from rotary kilns in order to meet increasingly stringent environmental requirements. This installation enables the existing facility to reduce their sulphur emissions by over 90%.The CDS ProcessA general overview of the CDS process is presented in Figure 1 below. The combined, de-dusted off-gas from multiple kilns is sent to the CDS, which acts as an entrained fluid bed, where the gas is contacted with a water mist, re-circulated solids and hydrated lime. The SO2 from the gas stream and the available calcium hydroxide (Ca(OH)2) from the hydrated lime dissolve in the water and react to ultimately form calcium sulphites and gypsum. The solid residue (referred to as CDS residue), is the primary by-product of the process."

Jan 1, 2016

By Kristian E. Waters, Hao Ma, Haibei Wang

Heavy metal ions exist in waste effluents including mining tailings, manufacturing discharges, and smelting and metal plating process wastes. Various methods are available to treat industrial effluents containing high levels of metal ions, but when confronted with wastewater that has low metal ion concentration below 500 mg/L, most techniques suffer from low removal or separation efficiency as well as high operating cost. ELM-based techniques can be used to solve these problems.

Apr 1, 2023

By PETER ROBINSON, KEVIN BARBER, OLIVER WHATNALL

The investigation and uptake of filtered tailings continues to grow around the world, but cost and scalability are deterrents for mining companies. Filtration technology that is currently in use is unable to meet the needs of many operations and projects that would otherwise adopt filtered tailings. For tailings to reach the desired moisture content for dry stacking, the majority of processes require pressure filtration, with significant upfront and ongoing maintenance costs. Given the comparative lower costs associated with low-pressure Viper vacuum belt filtration, this technology has the potential to alleviate dependency on high-pressure applications and make efficient dewatering and handling of tailings a more economic and sustainable solution.

By M. -C. Noël, G. P. Demopoulos

In this work the formation and environmental stabilization potential of arsenate-containing fluoroapatites is considered. In particular in this research various compounds were precipitated from synthetic solutions containing fluoride, arsenate/phosphate and calcium by varying different parameters-temperature, Ca:As ratio, pH, and P:As ratio, and aging time. The results obtained helped determine the operating window that should be used for the formation of highly crystalline fluoroapatites, in particular svabite (Ca5(AsO4)3F). It was found that svabite has a specific pH range of precipitation, with lower pH yielding CaF2 and calcium arsenate compounds such as CaHAsO4•H2O. At higher pH, a mixture of svabite and johnbaumite (Ca5(AsO4)3OH) precipitated, yielding a less stable material. This range of precipitation varied with the concentration of arsenic in the starting solution, and widened with higher initial concentrations of Ca2+, AsO4 3- and F-. Furthermore, svabite/fluoroapatite solid solutions were formed by using the same procedure as svabite but replacing some of the arsenate in solution by phosphate. The increase in phosphate content yielded a gradual change in morphology and crystallinity. Work on stability evaluation is currently under way.

Jan 1, 2014

The latest in mining technology and equipment will be show-cased this month at MINExpo International 2004. The event, billed as the world’s largest mining equipment exhibition, is set for Sept. 27-30at the Las Vegas Convention Center. MINExpo, sponsored by the National Mining Association (NMA), is held every four years in Las Vegas, NV. This year’s event is expected to attract more than 40,000 mining industry professionals and executives from around the world. And several key members of the U.S. Congress and other senior government officials are expected to attend. In addition, senior industry and government officials from Asia, Europe, Australia, Africa and South America will be on hand.

Jan 1, 2004

By Hazel J. Stratton

IN THE HALF-CENTURY that has passed since the Bureau of Mines was established in July 1910, the research and technologic investigations conducted by the Bureau's scientists, engineers, and other personnel have helped significantly in improving health and safety in the mineral industries and have contributed substantially in conserving the Nation's mineral resources through improved techniques in the mining, treatment, and use of mineral commodities. From Bureau laboratories have come new materials for industry and better methods of extracting and processing minerals and mineral fuels. Bureau safety investigations-complemented by equipment testing and by programs of mine inspection and education-have brought about safer and more healthful working conditions.

Jan 1, 1960

By R. W. Bartlett

DISILICIDE coatings, MeSi2, on refractory metals are usually grown by a solid-state diffusion reaction similar to the parabolic oxidation of metals. Two or more silicide compounds occur in each of the binary silicon-refractory metal systems. When an adequate source of silicon is available during the coating process, the lower silicide compounds are usually not formed.1 However, during service application of the coated refractory metal, continued heating causes further diffusion and growth of the lower silicides. A study of the growth kinetics of the lower silicides in the molybdenum and tungsten binary systems with silicon was previously reported.2 The present study is concerned with the growth kinetics of Ta5Si3 and Cb5Si3, formed as conjugate layers between TaSi2/Ta and CbSi2/Cb diffusion couples, respectively. Diffusion couples consisting of disilicide-coated tantalum and columbium sheet coupons were subjected to diffusion heat treatments, cross-sectioned, and scanned by an electron-microprobe analyzer to determine the relative X-ray intensity profiles. These profiles correspond closely to concentration profiles for the constituents, and were used to identify phases and locate phase boundaries. The analysis of a single specimen after a diffusion-anneal provides only one value for the Me5Si3 phase thickness, corresponding to the time and temperature of the diffusion treatment. Consequently, each isothermal curve showing the rate of accumulation or depletion of silicide phases required several samples with identical diffusion temperatures but different diffusion times. The disilicide coatings were prepared by pyrolizing commercially pure silane in a hydrogen carrier gas. The hydrogen was purified by passage through a palladium membrane. Commercially pure tantalum and columbium sheet metal coupons, 0.005 by $ by 2 in., were used. All of the coated specimens for each system were prepared together in a single group in order to minimize coating variations among individual specimens. During pyrolysis, the brightness temperature was maintained at 1200°C. With suitable flow rates at this temperature, only the disilicides of tantalum and columbium were formed in detectable amounts. Coated specimens were subjected to diffusion an-neals in a tube furnace with automatic proportional control within ±10°C. A H2-Ar mixture, deoxidized and dried over anhydrous magnesium perchlorate, was used to prevent oxidation during the diffusion anneal. Diffusion couples were cross-sectioned, polished and examined with an A.R.L. electron-microprobe X-ray analyzer. Both metal constituents in each specimen were simultaneously scanned using a 1-p beam spot size and either 1- or 2-µ steps. Analyses were performed using the Ka radiation of columbium and silicon, and the La, radiation of tantalum. For all specimens, an acceleration voltage of 30 kv was used, and integration was made against the specimen current. LiF and A DP monochrometers were used to isolate characteristic radiations. Three or more traverses were made on each specimen. The intensity scales were adjusted using the constituent metals and standard samples of the silicide compounds which had been verified by X-ray diffraction. The relative intensity profiles were used directly, in conjunction with the standard samples, to identify compounds and phase boundaries. The stoichiometries differ considerably between the silicide compounds in both systems, and the homogeneity range for these silicide compounds is narrow. These characteristics result in marked differences in relative intensities of the fluorescing elements—differences which permit ready identification of phases and phase boundaries. Projections of both electron back-scattered images and characteristic

Jan 1, 1967

By F. E. Chase

Mobile roof supports are shield-type support units mounted on crawler tracks. Mobile roof support (MRS) units are used during retreat mining, and they eliminate the setting of roadway, turn, and crosscut breaker posts which are required during pillar recovery operations. Mobiles are a more effective ground support than timbers, and their usage enhance the safety of section personnel and reduces material handling injuries. MRS usage is rapidly increasing, and approximately 40 U.S. coal mines have successfully employed this relatively new technology. This paper is in response to increasing requests from operators, State and Federal Regulatory Agencies, and others on the practical aspects of MRS usage in underground coal mines. During this investigation, nearly half of the U.S. mines which have utilized mobiles were visited. This report depicts the more common pillar extraction methods which operators have found successful. The Christmas tree and outside lift methods are illustrated and discussed. Roof control plans that do not require breaker posts or allow pillar extraction with fewer than four mobiles are also examined. In addition, operators' experiences with setting pressures, loads, and rates of loading during pillar extraction are addressed. Mining and support strategies to more effectively control hillseams, weak roof, and gob overrides which have entrapped equipment are also discussed.

Jan 1, 1996

By Steven W. Wilson, Brigitte Lacouture, Nichola A. McKay

"The Aqqaluk deposit is a lead-zinc ore body that lies immediately north of the Main Pit at Teck Cominco’s Red Dog Mine in Alaska. It is scheduled to begin production in 2011 or 2012. A project team was formed in late 2004 to plan and implement an ore characterisation and metallurgical evaluation on the Aqqaluk ore. The main objective of this program was to facilitate the transition from Main Pit to Aqqaluk ore in the Red Dog concentrator. The program will develop a detailed, spatially-oriented characterisation of the Aqqaluk deposit attributes including lithology, ore geochemistry, bulk mineralogy, ore texture, as well as evaluating the metallurgical characteristics of ore hardness, process water geochemistry, bench-scale floatability and mineral liberation in ground feed, concentrate and tails. Developing correlations between the metallurgical response and the ore characterisation data is key to the emerging science of geometallurgy. This on-going program is a technical due diligence study that aims to reduce the risk associated with processing a new ore and to provide predictive information for mining and stockpile preparation.The test work to date has focused on characterising the five ore zones currently identified in the Aqqaluk deposit, namely: Siliceous (sub-divided to High Zn:Fe and Low Zn:Fe), Vein, Median Plate and Baritic ores. It identified a number of challenges associated with surface oxidation, or weathering, of the core samples and outlined a program for future sample collection and storage. Metallurgical testing evaluated ore hardness by a variety of methods. Preliminary floatability studies have been completed and some initial links have been established between the ore characteristics and the flotation response. Soluble mineral weathering products, the relative abundance of pyrite and marcasite and the iron content in the sphalerite grains have all shown a correlation to mineral recovery.As new core is received, both the ore characterisation and the metallurgical testing will be continued with a view to strengthen the existing correlations and develop new links."

Jan 1, 2007

By C. C. Anderson

"While conducting investigations in connection with the helium program of the Bureau of Mines, the Cryogenic Laboratory has improved an apparatus for the rapid and accurate determination of the helium content of natural gas and gaseous mixtures derived from that source. The separation of helium is effected by the use of activated coconut charcoal which, when cooled to liquid-air temperatures, absorbs the nitrogen and other constituents of the gas, leaving the helium in a. spectroscopically pure state. This absorptive property of activated charcoal was discovered- by Dewar3/ in 1875. Several years later, while conducting their original researches on helium in natural gas, Cady and McFarland employed the charcoal method for the absorption and removal of the common constituents of natural gas and constructed an efficient apparatus in which this operation could be effected.4/ Shortly after initiating the government's helium activities during the World War period, the Bureau of Mines adopted, with Minor modifications, the Cady and McFarland apparatus and method of analysis. Seibel.5./ described this modified apparatus and method of procedure as part of a publication on helium-bearing natural gas. Subsequently, the Bureau's apparatus for helium analysis has been simplified and improved to facilitate more rapid and positive operation. The apparatus and method of procedure now being used by the Bureau of Mines Cryogenic Laboratory arc described in this paper.The personnel of the Bureau of Mines Cryogenic Laboratory has improved and brought the helium apparatus described herein to its present state of perfection. The writer's contributions have been-of minor importance, and he wishes to give the various members and former members of the laboratory staff full credit for the improvements they have made. He also desires to express his appreciation for suggestions and criticisms offered during the preparation of this paper to the following members of the Petroleum and Natural Gas Division, Bureau of Mines, which now includes the Amarillo Helium Plant and Cryogenic Laboratory: H. A. Cattell, chief engineer; C. W. Seibel, supervising engineer of the Amarillo Helium Plant; W. M. Deaton, chemist-in-charge of the Cryogenic Laboratory; and H. S. Kennedy.The quantitative determination of helium in a gaseous mixture is accomplished by the removal of the other constituents from the sample, either by chemical or physical Means, leaving only the helium which can be measured directly. Chemical methods, when applied to natural gas, require the burning of the hydrocarbons in oxygen, the, absorption of the resulting carbon dioxide in a caustic solution, the removal of the excess oxygen in a suitable solution such as an alkaline pyrogallate, and the elimination of nitrogen by sparking or by combination with hot calcium or magnesium.. Such procedures are very slow and tedious compared with the physical method which employs the absorptive property of activated charcoal to effect the separation of the other constituents from the helium."

Jun 1, 1934

By Jacob L. Brinkman, Catherine E. Johnson

Researchers are exploring the use of unmanned aerial vehicles (UAV) to measure concentrations of gas emissions in situations where such measurements are otherwise extremely difficult to obtain, such as NO and NO2 (NOx) emissions from surface mine blasting. Recently, countries have imposed or are planning to impose surface blasting gas pollution regulations, which creates a need for an improved understanding of UAV-based gas measuring systems. The experiments detailed in this paper were performed to determine if airflow generated by the rotors, also known as downwash, unnaturally alters concentration measurements. Downwash turbulence could create locations of varying pressure, which could affect density-based concentrations as measured by some governing entities, including the Occupational Safety and Health Administration (OSHA). 

Ground conditions at the Kencana mine, Indonesia, are generally poor and an underhand cut and fill mining method is used for extraction. Due to these poor ground conditions, all vertical development has been conducted using blind, top-down, sink and line excavation methods. Due to time constraints, raiseboring was considered the only viable excavation method for the installation of a return ventilation system for the K2 (Kencana extension) project. In order to achieve successful raiseboring in the poor ground conditions a number of strategies were used including: a detailed geotechnical study for optimal position of the shaft/s, splitting shaft excavation vertically, raiseboring of multiple smaller diameter shafts, extensive pregrouting, installation of drainage holes, and rapid installation of support following excavation.

Nov 25, 2010