Search Documents

By O. M. G. Newman

The Electrolytic Zinc Company of Australasia Ltd., generates a jarosite waste at its Risdon smelter. Since 1974 this waste has been disposed of at sea off south-east Tasmania. As part of a monitoring programme prescribed by the Australian Government, bottom sediments from the disposal zone are monitored regularly. QEM*SEM image analysis complements conventional chemical analysis, having the ability to partition the occurrence of an element between sediment particles of metallurgical and natural origin. The adaptation of QEM*SEM techniques to the evaluation of bottom sediments provides insight into the fate of the particles of jarosite waste.

Jan 1, 1989

By Walter Steiner, Claus Becker

INTRODUCTION General Switzerland is a densely populated country in the heart of Europe. With its total surface of 41.300 km2 and a population of 6,8 million in 1986 the average population density is 163 capita / km2. The population density is lower than in Germany (245 capita/ km2) or the Netherlands (355 capita/km2). The USA have a population density of 26 capita/ km 2. However, sixty percent of the Swiss surface is covered by the Alps and another ten percent by the Jura mountains the remaining thirty percent of the surface is covered by the Swiss plateau where the majority of the population lives. The population in the inhabitated areas is thus substantially higher and may possibly reach those in major metropolitain areas. Due to the high population density in Europe in general and Switzerland in particular future traffic demands cannot be fulfilled sole by car or plane. Environmental and land-use constraints lead to the third option for growing transportation needs: High-speed rail (Bovy, 1990). Switzerland has developed its own approach to promote public transportation and in particular rail transportation: "Rail 2000" (Stalder, 1990). The system "Rail 2000" is based on a series of hubs distributed over Switzerland where easy connections can be made.

Jan 1, 1991

By L. Diestelow

Evaporation and crystallization processes are used extensively in the mining industry to provide many pro-ducts. In the case of solution mining evaporators are used to concentrate, or to concentrate and crystallize the raw materials being mined. In the case of underground, or strip mining dissolving and crystallization are used in many processes in order to purify the ore to saleable materials. Presently evaporators and crystallizers are being used in the production of sodium chloride, potassium chloride, sodium carbonate, sodium sulfate, lithium chemicals, aluminum, and many others. The evaporator is a device designed to remove water or solvent from a solution. In an evaporator the energy released by steam condensing on one side of the heat transfer surface is transferred to the product solution on the other side of the heat transfer surface. As long as the boiling temperature of the product liquor is below the condensing temperature of the steam, the product solution will absorb heat. This heat absorption causes vaporization of the water (solvent) in the product solution resulting in concentration of the product. The simplest evaporator is the single effect evaporator. If we assume the feed introduced into the single effect evaporator is at its boiling point, ignore radiation losses, and assume the steam into the heat exchanger is dry and saturated, then the heat transferred will correspond to the latent heat of vaporization. Therefore, one kilogram of condensing steam will produce one kilogram of evaporation. Economies in energy usage compared to the single effect evaporator can be made by using multiple effect evaporators, or vapor recompression evaporators.

Jan 1, 1993

By A. Moergeli, Philip Sander, John J. Reilly

"Estimating and managing the costs of complex infrastructure projects – in the planning/design and construction phases, for both owners and contractors – has been a challenge for decades. The more complex and technologically advanced the project, the greater the uncertainty, including potential risks that are important to owners and contractors, such as:• Cost risks to owners – meeting budget and schedule, maintaining public credibility.• Cost risks to contractors – profit, consequences of loss, impacts to reputation/future work.This concern has been addressed in various ways by the underground construction industry for some time (Reilly, 2001). In particular, while significant advances have been made in cost estimating for the planning and design phases (Reilly et al., 2004), that are important to agencies and political decision-makers, it is not apparent that these advances have been widely adopted for construction cost estimates. The reasons for this may relate to lowbid considerations – any method that tends to increase the contractor’s cost estimate, by including risk or likely costs, could lead to an erosion of the contractor’s competitive position – if others are not similarly required to include such costs.Different cost estimating methods produce different levels of information. Specifically, there is a large difference in the character and depth of information if a deterministic (quantities times price plus a contingency) and risk-based cost methods are used. It is this difference in character and depth of information that is the reason that risk-based cost estimating has potential value for owners and contractors. Figure 1 presents hypothetical cost results from deterministic and risk-based methods and illustrates some of these differences.In Fig. 1, the results for deterministic and risk-based cost estimates are given related to the potential profit or loss for a typical project. As is evident in this example, there is significant potential for costs to be realized that are higher than the proposal/bid value estimated using a deterministic approach, with a 15 percent probability of a loss. There is a 30 percent probability that the project will have a reduced profit. There is a 55 percent probability that the project will return a good profit. Using a risk-based approach, it is possible to better recognize this potential outcome in the bid phase and, as a consequence, develop a strategy to:"

Apr 1, 2016

By Trevor R. Ellis

In August 2011, the Southern African Institute of Mining and Metallurgy (SAIMM) contacted mining institutes and related societies internationally to assess their interest in participating in coordination of the review of the South African Code for Mineral Valuation (SAMVAL) with reviews of other mineral valuation standards. The main mineral valuation standards are the CIMVal Standard of The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), the VALMIN Code of The Australasian Institute of Mining and Metallurgy (AusIMM), the SAMVAL Code, and the extractive industries? guidance note of the International Valuation Standards Council (IVSC), Valuation of Properties in the Extractive Industries, GN 14, designed for application within the full set of International Valuation Standards (IVSs). By January 2012, SAIMM had concluded that the level of respondent interest was adequate to organize a meeting. A meeting was scheduled for April 18, 2012 in Brisbane, Australia in conjunction with a VALMIN mineral valuation conference organized by the AusIMM. The stated purpose of the meeting was to develop an accord on terms of reference for pursuing harmonization of mineral asset valuation standards adopted by the participating mineral institutes. SME decided that, although it has not developed its own mineral valuation standard, it should participate in the Brisbane meeting and the harmonization process, as also did the American Institute of Minerals Appraisers (AIMA).

Jan 1, 2012

By Peter Johnson, David Barber, Lachlan Henderson

"The traditional approach to rail tunnel fire safety design is to follow NFPA 130, which assumes a major tunnel fire could occur and requires bi-directional emergency ventilation. There is no regard to the impact of ventilation on fire growth and smoke production. In Europe and other parts of the world, the need for tunnel ventilation systems to provide smoke management in the event of fire is being questioned. The European Commission’s Safety in Railway Tunnels TSI is based on a philosophy that improved running capability (preventing fires and other events stopping the train in the tunnel) and elevated fire performance of materials means the chances of a major fire in a tunnel is highly unlikely, with only small fires expected, and no tunnel ventilation required. This approach is reinforced by the International Tunneling Association which has recently published an Engineering Methodology for Performance Based Fire Safety Design on Underground Rail Systems, which includes a methodology that does not require assessment of tenability in tunnels, but requires a scenario based risk assessment to be undertaken to determine overall fire safety measures. Recent research by the University of Edinburgh has shown that forced airflow from a mechanical ventilation system may promote fire growth and increase smoke volumes much more than with natural ventilation. Whilst the concept of no mechanical ventilation (i.e. natural ventilation) is a new concept for some, for many rail tunnels it is worthy of serious further consideration. RAIL TUNNEL SMOKE MANAGEMENT AND STANDARDS Smoke management using mechanical bi-directional ventilation systems has been a central part of the fire safety design solution under NFPA 130 for rail tunnels since 1982. The current version of the standard, NFPA 130: 2014, states that mechanical ventilation should be fitted to rail tunnels of length greater than 305 meters and an engineering analysis should be undertaken for tunnels of length 61 to 305 meters to determine whether mechanical ventilation should be fitted. However, this approach is not necessarily reflected elsewhere in the world. In Europe in particular, mechanical ventilation systems for smoke control within rail tunnels have taken a much less central role within the standards framework."

Jan 1, 2016

By Steve Kral

The list of environmental issues facing industry in general, and the mining industry in particular, has placed greater emphasis on the concept of risk assessment and risk management. In informal terms, risk can be defined as the chance of injury, loss or damage. More formally, it is defined as the probability of an occurrence and its consequences. In simple terms, risk assessment involves three questions: What can go wrong? How probable is it to go wrong? If it goes wrong, what are the consequences? Experts on the subject of risk assess¬ment and management met in St. Louis, MO in October 1992 to discuss the extensive and innovative technology that has been developed in this arena. Each agreed that a consistent framework can be used to approach risk assessment/ management considerations in siting and design alternatives, as well as when considering financial aspects of mine development. And the environmental planning process for mines, as well as planning for operation through closures, will rely more heavily on risk assessment and management techniques. Risk assessment is a tool to assist engineers, scientists and managers make better, defensible operational decisions. A realistic and probabilistic risk analysis, coupled with a sound financial model, can combine a large set of alternatives and criteria to arrive at a defensible decision. Organizers of this regional SME conference believe that mining professionals should become fully conversant with risk assessment techniques and approaches because this arena provides opportunities to develop more rational decision-making techniques. Current health risk assessments rely heavily on Environmental Protection Agency (EPA) approaches. Several speakers and papers show how this approach has been applied to a variety of topics. Two major advantages come forward when applying risk assessment techniques to environmental clean-up options for contaminated sites. They are the selection of practical options and cost-effective alternatives. A probabilistic risk assessment provides results that can be directly related to clean-up costs. It has been shown that small reductions in risk are obtained for large increases in cost after a certain threshold value is reached. A preferred, practical clean-up alternative that provides permanent solutions can be selected based on a probabilistic assessment. Here are summaries of some of the papers presented at the meeting.

Jan 1, 1993

By Joseph A. Kantor

Several wall rock porphyry or pyrometascmatic copper deposits occur within the metamorphosed Paleozoic formations along the northern and eastern flanks of the Little Dragoon Mountains. Rocks ranging in age from Precambrian to Recent occur in the area. The Tertiary age Texas Canyon Quartz Monzonite intruded the sedimentary section in the eastern half of the range metamorphosing the Paleozoic carbonate units to tactites composed of garnet, diopside, and tremolite. Copper, zinc, and molybdenum minerals deposited in sites which are structurally controlled and stratigraphically favorable. Because the deposits are covered by alluvium, the information on structure, alteration, and mineralization is based upon a study of the diamond drilling programs. The mineralized district can be divided into four areas: 1) The Johnson Camp copper-zinc deposits; 2) The Dragoon copper deposit; 3) The I-10 copper-molybdenum deposit; 4) The Strong & Harris copper-zinc deposit. On the southwest end of the range beneath alluvial cover, the Cretaceous Bisbee Group was thrust over Precambrian and Paleozoic formations. The Tertiary Texas Canyon Quartz Monzonite intruded and metamorphosed them. In the upper plate, the Cretaceous sediments near the intrusive were metamorphosed to metaquartzite and andalusite and sillimanite schists. In the lower plate the Martin and Horquilla formations were marbleized. The lower Abrigo was metamorphosed to epidote rich calc-silicate tactites and biotite hornfels. A composite geologic cross section, based upon diamond drilling,, through the Dragoon copper deposit is shown in Fig. 1. The geologic events which formed this deposit are: 1. A faulted section of Precambrian Pioneer formation and diabase and Cambrian Bolsa and Abrigo formations was thrust over Pennsylvanian Horquilla formation. The Dripping Spring quartzite if present, has not

Jan 1, 1977

By Sandy Worden

Coal mining companies in Australia are managing the high-consequence risks across their operations more effectively by using an interactive online risk management system known as Riskgate Developed by the Minerals Industry Safety and Health Centre (MISHC) at the University of Queensland, Australia, Riskgate contains detailed information about 11 high-consequence risk areas (called topics in the system) for opencut and underground coal mines (Table 1). The existing topics are: fires; strata control for underground mining; ground control for opencut mining; tires; isolation; collisions; explosions and explosives; manual tasks; and trips, slips and falls. Every Riskgate topic is focused on coal industry activities (mining, processing, transport and storage). The scope includes mine sites, lease areas and mine infrastructure (mobile, fixed plant, field equipment, buildings, road and rail transport), and all aspects of the mine life cycle from design through to decommissioning. The topics uniformly recognize that a loss of control can result in injury or fatality, equipment damage, production loss, reputation loss and environmental damage. However, the priority focus for Riskgate is the safety of mine personnel.

Jul 1, 2013

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The Vermilion range extends from the vicinity of Tower to and beyond the ""international boundary, crossing into Canada at the eastern end of Hunter's Island. Merchantable bodies of ore have been discovered at but two localities along this extent, at Tower and at Ely, twenty-one miles east.The iron bearing formation of this range occupies the lowest position geologically of any of the Lake Superior iron formations, being placed by Van Rise and Clements in the Archean, as shown from the following succession:Lower Huronian Intrusive granites, granite porphyries, dolerites, and lamprophyresKnife Lake slatesAgawa formation (iron-bearing) Ogishke conglomerate(Unconformity.)ArcheanIntrusive granites, granite porphyries, and some greenstonesSoudan formation (the iron-bearing formation). (Minor unconformity.)Ely greenstone, an ellipsoidally parted basic igneous and largely volcanic rock The ores of the Vermilion series occur in the Soudan formation (the Agawa iron bearing rocks are not of commercial importance).At the Minnesota mine at Soudan the ore is a dense, hard hematite, occurring in irregular connected and disconnected lense shaped bodies in the jasper, which is intricately infolded in the ellipsoidal greenstone or green schists, so called on account of a characteristic ellipsoidal parting. The strike is about east and west and the dip approximately vertical, with a westerly pitch. The underground workings at this mine are some 4,500 feet in extent east and west, and over 1,500 feet in depth. The structure here is probably the most complex in the Lake Superior iron districts. Above the iron bearing formation, geologically, comes the basal conglomerate of the Lower Huronian, carrying large boulders and Masses of the iron bearing rocks."

Jan 1, 1920

By R. C. Guimareãs

Serrana's deposit contains three types of ore: oxidized, micaceous and silicate-carbonate. The results presented refer to characterization and fundamental studies performed on fractions resulting from the purification of five samples from the silicate-carbonate type collected in the mine. Each type was purified and submitted to mineralogical characterization, zeta potential determinations, and microflotation experiments. The samples, with exception of the barite, are mineralogically complex and the selectivity between apatite and gangue minerals is poor. Under the current state of art, it is impossible to feed the plant with the silicate-carbonate ore, unless it is blended with the standard oxidized ore.

Jan 1, 2002

By Alexander N. Winchell

"The deposits of the east end of the Mesabi Range cover very large areas, and consist of the same taconite that produces the hematite of the central and western Mesabi. It is not deeply covered with drift, but outcrops boldly in large masses. It is not concentrated locally into enriched bodies separated by leaner areas, but is all a fairly uniform, hard, banded, unaltered chert, carrying about 25 to 30 per cent iron as magnetite.The Mesabi Iron Company, organized by Hayden, Stone & Co., and under the direction of D. C. Jackling, has taken over these deposits and is building a Concentrating plant at the new town of Babbitt, about fourteen miles east of Mesaba, Minn. This plant is to have a capacity of 2,000 to 3,000 tons per day, and is based on the application to this low grade material of the methods which have made the so-called porphyry copper properties so successful.In 1916, an experimental mill was built in Duluth; containing full sized machinery and capable of handling from 100 to 200 tons daily. A considerable tonnage of material was concentrated here during 1916, 1917 and 1918. The work showed that the resulting product could be varied, almost at will, between 60 per cent and 70 per cent iron and .006 per cent to .030 per' cent phosphorus, and that this could be made on a large scale well within the limits of cost set by iron trade conditions. A small special cargo was sent down the lakes, late in 1918, assaying 63.27 per cent iron (natural and dry) and .008 per cent phosphorus; but it is assumed that large scale shipments will normally be of a Bessemer' grade carrying about 63 per cent iron and .020 per cent to .030 per cent phosphorus. This material is a sinter, carrying only traces of sulphur and titanium, with silica between 6 per cent and 10 , per cent, and alumina, lime, magnesia, and manganese, each below 1 per cent. Some of the iron in this sinter is hematite and some is magnetite, the percentages varying according to the treatment given on the sintering machine. Like the analyses, this hematite percentage is within reasonable control. Sinter made from finely ground magnetite has much the structure of coke, being firm yet porous, and gives good account of itself in the blast furnace."

Jan 1, 1920

By K. M. Kolin

ABSTRACT OF ORAL PRESENTATION A discussion of current U. S. Bureau of Mines research into the problem of strata control in multiple Western coal seams will be presented. The problem and research priorities will be described as determined from interviews with major Colorado and Utah mine operators as well as governmental agencies responsible for Federal leases. Proposed contract research and ongoing in-house studies will be discussed, including case histories and results from projects being conducted at two multiple seam operations in Utah.

Jan 1, 1977

By Jerome F. Thomas

The primary purpose of this paper is to review the fire and explosion hazards associated with hydrocarbons heavier than methane. Methane is the classical hydrocarbon encountered in mines whose presence is generally due to bacterial decomposition of organic debris. The higher hydrocarbons are more likely to be found during tunneling when petroleum products either natural or man made are encountered. Fires may be defined as rapid gas phase oxidations accompanied by the rapid evolution of light and heat. Explosions may be defined as uncontrolled fires. The rapidly expanding gases resulting from combustion exceed the speed of sound and generate percussive forces. The essential elements for a fire or explosion are shown on Figure 12: (1) a gas phase explosive mixture and (2) an ignition source. The paper will attempt to review various aspects relative to the explosive mixture; The concentration and composition; Techniques for detection; Techniques for ventilation to reduce concentration below explosive limits. The ignition sources are also listed on Figure 12. An arc originates from an electrical source such as electrical switches, relays and motor brushes. Static electricity can also be an arc source and may be generated by air flowing through rubber bases or a rapidly moving endless belt. A spark is generally associated with abrasion of iron metal. A flame source may be a match, candle. cutting or welding torch, or engine exhaust. If

Jan 1, 1974

By K. Hartman

Certain external forces affect the manner in which business is conducted. and in recent years changes in the business environment have altered how some of these external forces affect the management of a business. These changes must be understood and considered in definition of the strategy of the business. Implementation of the strategy must assure commitment from all departments within a company, and this commitment sometimes involves compromises to assure that a department's goals mesh with the overall business objective such compromises must be externally motivated. i.e. for benefit of the customer. Complete implementation transcends internal departments to all aspects of managing the efforts in the marketplace.

Jan 1, 1989

By Stanley Dempsey

Mine developers commonly undertake projects that require more funds than they can invest themselves. From that point until they are able to complete a "bankable" feasibility study, they require access to venture capital. In the United States, most venture capital has been provided to the small mining segment of the industry through tax advantaged limited partnerships. Recent changes in Federal tax law makes other forms of financing competitive, and the use of corporations and private and public offerings of shares may soon become more popular ways of securing venture capital. A number of new financial services firms have entered the mining finance business in recent years. They provide mine developers with access to venture capital.

Jan 1, 1987

By A. A. Mathews

INTRODUCTION When Palmer King asked me to prepare a paper for this conference, it seemed quite appropriate, since I am Chairman of Subcommittee No. 4 of the U. S. National Committee on Tunneling Technology and we are presently making a detailed study of contracting practices. Before the end of this year, we expect to publish our report containing guidelines aimed at improving our contracting practices and minimizing the problems which develop therefrom. The American construction and mining industries today are glowing examples of the ingenuity of man pitting his wits against the unknown. Without the promise of rewards commensurate with the perils faced and the effort expended, it is doubtful that these industries could have reached their present state of advancement. Nevertheless, these industries are still primitive compared to many others such as aerospace and electronics. That our present contracting practices leave something to be desired is evidenced by the fact that many of our underground projects wind up with tremendous increases in estimated cost, financial disaster, and costly dispute and litigation. The situation is aggravated by the current economic uncertainty, energy crisis, and shortage of materials. At the same time, if our industries are to develop their maximum technologic potential, we must employ contracting practices which will encourage that development. Most of the contractual problems related to underground construction are associated with risk and its management. Unless all of the ramifications of this subject are understood, it will be difficult

Jan 1, 1974

By Chee Theng

"It is not surprising that the most popular key takeaway from the Developing Diversity in Mining workshop (see box) held on the first day of the SME Arizona Conference in December was, “Have more parties!”The adage that mining professionals work hard and play hard was clearly demonstrated at the two-day conference in the JW Marriott Tucson Starr Pass Resort & Spa in Tucson, AZ. Nearly 550 participants, some of whom had left behind frigid temperatures and thick parkas in their hometowns, attended a full slate of technical sessions, shared industry experiences and knowledge, reconnected with buddies in the industry, and made strategic new contacts in the conference’s collegial environment, aided by the mild Arizona winter.To start off the technical sessions, John Mansanti, president and chief executive officer of Crystal Peak Minerals and 2017 SME president, entertained a packed lecture room with his keynote lecture on “Tariffs, Embargos, and Cartels ... Oh My! A Perspective on Potash.” Mansanti gave the audience the benefit of his more than 35 years of experience at companies including Barrick Gold, Newmont Mining Corp., Placer Dome, Freeport-McMoRan and Intrepid Potash, where he was senior vice president for operations, technology and strategy. At the luncheon, Justin Cross, general manager of Freeport-Mc- MoRan’s Bagdad operations, spoke on how the role of a leader in mining is transforming from one based on technical expertise to one based on the ability to collaborate, to lead and to adapt to changes in technologies and skill sets, in his talk on “Knowing When to Learn, When to Lead and When to Manage.”"

Feb 1, 2019

By Jackson G. Jenkins

Magma Copper Company's San Manuel SX-EW facility has operated since May, 1986. The original facility had a design capacity of 25,000 tons per year of electrowon copper cathode produced by processing pregnant leach solution from an open pit/heap leach operation. In 1988, the plant was expanded to 50,000 tons per year to incorporate processing in-situ leach solutions. This paper focuses primarily on the heap leaching area with regard to exploration, testing, feasibility, permitting, design and construction, and operating practices. Research utilizing surfactant leaching aids to enhance copper recovery is also discussed.

Jan 1, 1993

By P. Riveros, A. Pratt, G. Deschênes

The effect of pyrite, pyrrhotite, chalcopyrite, realgar and arsenopyrite on gold dissolution in cyanide media was investigated. The cyanidation of synthetic gold ores, in the presence of various concentrations of sulphides, was studied under constant experimental conditions. A mineralogical analysis of the minerals was performed. The leaching kinetics were determined. The negative effect of sulphides on the gold dissolution rate varies with the sulphide mineral, and decreases according to the following order: realgar > pyrrhotite > chalcopyrite > pyrite > arsenopyrite. The chemical characterization of gold and sulphide minerals surfaces using X-ray photoelectron spectroscopy (XPS) was undertaken to identify the mechanisms involved. XPS analysis showed that a passivation layer of sulphides, arsenic or iron compounds may form on the gold surface as a result of the dissolution of the sulphide minerals.

Jan 1, 2002