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By T. F. Torries

Market data commonly perceived as being useful to industry for decision making include prices, production and trade quantities, production and transportation costs, stocks, customer's needs, and competitor's qualifications. Costs and factors affecting costs are particularly important in determining competitive positions and possible future prices. These costs include relative cost of production as well as cost experienced by the buyer in making the final product. Care must be taken to calculate costs in a consistent manner to achieve meaningful analyses.

Jan 1, 1987

By Noel C. Joughin, Orrie Fenn, Brian E. Protheroe

Work has shown that the use of high-pressure water jets enhances the performance of mechanical cutting in very hard rock. To assess the potential of this approach for use in conjunction with free rolling cutters, a series of tests has been conducted using both disc and button type cutters, to determine the relative effects, on cutter performance, of variations in relevant jet and cutting parameters. In these tests it was found that water jet assistance can result in reductions in the forces on a free rolling cutter typically of the order of 40%.

Jan 1, 1985

By O. A. Bascur

Current competitive demands on the process industries stimulate the need for improved operating efficiencies and compliance to stricter governmental regulations. Emerging information technologies allow narrowing the gap between management business objectives and the process control level. Benefits come from enhanced energy management, operating costs reduction, enhanced scheduling of activities, reduced quality giveaway, enhanced market driven production and enhanced decision making. Plant management systems integrate economic performance monitoring by controlling the business rather than just throughput and product quality. Sound business based decisions about how to operate the plant can be achieved by adequate dynamic performance monitoring at the plant level and the enforcement of the desired targets at the process control level. This paper describes some of the key requirements to implement a process management system to meet stricter process performance standards. Extensions are made to facilitate conforming with regulations established by various governmental and industry monitoring agencies.

Jan 1, 1993

By H. Walqui, J. Drelich, J. Pletka, E. Luhta, E. Raber, J. Wieland, P. Boyd, N. Tervo, D. Herron, S. Boston

Mini-projects studying the flotation chemistry of paper de-inking were incorporated to an educational program at Michigan Technological University with support from the paper recycling industry. Interfacial activity of frothing agents, surfactants and polymers in de-inking flotation systems has been studied through flotation, atomic force microscopy, zeta potential, contact angle, surface tension, and froth stability measurements. These fundamental studies were developed to understand microscopic and molecular effects occurring in flotation of ink particles that may lead to improved designs in de-¬inking flotation processes. Fundamental studies indicate that ethoxylated alcohols are efficient frothing agents in flotation and can be used to clean the recovered paper from hydrophobic ink particles. Next, it was further supported in this research that the fatty acids activated by calcium ions act as collectors in flotation of ink particles. Finally, improvements in de-inking flotation are reported in laboratory tests involving aqueous solutions of polymeric flocculants.

Jan 1, 2001

By Robert L. Russell

Production at Freeport Indonesia's Ertsberg open pit copper-gold mine started in 1972 at a rate of 7.5 kt/d (8270 stpd). Mill throughput remained at that rate for several years until the discovery of the Ertsberg East (GBT) ore body. This discovery prompted three succes¬sive expansion stages from 1981 to 1988 that boosted production to 20 kt/d (22,000 stpd). In 1988, the discovery of the huge Grasberg porphyry copper deposit launched an era of much larger expansions. The first of these was the installation of a fourth primary mill in 1989 that increased throughput to 32 kt/d (35,270 stpd). That was followed by an expansion of the crushing and screening plant and in 1991 the addition of a new south concentrator to bring production to 57 kt/d (62,830 stpd). The addition of a primary ball mill and the changeout of the original Denver flotation cells in 1993 brought production to its current level of 66 kt/d (72,750 stpd).

Jan 1, 1994

By Lawrence K. Nordell, Vinit Sethi

Published standards and specifications do not adequately cover engineered class pulleys for modern high strength steel cord belt conveyors. This paper discusses the Conveyor Dynamics, Inc. (CDI) design criteria and stress analysis techniques emphasizing the finite element method (FEM), fatigue failure criteria, design limits and manufacturing requirements to ensure successful and safe pulley installations.

Jan 1, 1993

By Patrick J. Doig

The NS9 Drop Shaft contract formed part of the Waste Pollution Abatement Program (WPAP) conducted by the Milwaukee Metropolitan Sewerage District (MMSD). The contract involved the construction of two shafts, a deaeration chamber and connecting tunnel, and ancillary facilities. Portions of the construction were located in saturated overburden where dewatering was prohibited. Ground freezing was utilized for temporary support of the excavation. This paper concentrates on the freezing system and the excavation of frozen ground, with particular emphasis on the use of mechanical cutting equipment, including a raiseborer and a roadheader.

Jan 1, 1991

By J. W. Leonard, C. L. Jiang, B. K. Parekh, X. H. Wang

The selective depression of pyrite from the Kentucky No. 9 coal seam was systematically examined using various kinds of inorganic and organic chemicals. Most of the organic chemicals tested showed little selectivity in pyrite depression. It was found that both orthophosphate and pyrophosphate were effective for the selective depression of coal pyrite in coal flotation using fuel oil as a collector. At substantially low concentrations of pyrophosphate, the flotation of coal pyrite was completely depressed over a wide pH range, while the coal flotation remained unaffected. The mechanism of the selective depression of pyrite by phosphates was explained with the help of thermodynamic calculations of iron-phosphate-water systems and zeta-potential measurements. It was shown that pyrophosphate reacts strongly with the iron ions of pyrite to form stable hydrophilic iron pyrophosphate complexes on pyrite surfaces.

Jan 1, 1999

"What is your assessment of the minerals business?My experience with mining has been primarily in the coal sector until about 10 years ago, when I also became heavily involved in the aggregates and industrial minerals sectors. I have also had peripheral involvement through family and partners in the gold sector, with just enough exposure to gold to become fascinated. In 1994, I visited Ghana and considered the possibility of taking an expat assignment at a surface gold mine that had just been started.It is not news that the coal sector in this country has suffered tremendously in recent years. Especially hard hit is the central Appalachian region, where a number of factors combined have had a devastating effect on production, jobs and the economy. These factors include federal regulations affecting coal production and use, higher production costs and decreasing market share of Appalachian coal by the switch from lower sulfur coal in favor of lowercost, higher sulfur coal from the Illinois Basin, as utilities have installed scrubbers to comply with Phase II of the 1990 Clean Air Act Amendments. Nationally, the lower cost of natural gas has been a huge factor affecting coal use. In Kentucky, for example, which exports to other states around 70 percent of its coal, those markets are disappearing, as utilities close coal units in favor of natural gas. This is a structural change in the electricity market, and one that will become more pronounced as federal greenhouse gas regulations are implemented.We often hear the phrase, "the war on coal." While there are certainly a number of market factors affecting coal production and use, this phrase captures a different element that is all too real. The attacks have come from environmental activist groups for many years; from some in the media and, in the last few years, from a White House administration that believes strongly in alternatives to coal. Then, there really is an alternative to coal in the form of the previously untapped unconventional gas reserves that allowed utilities to move away from coal.Coal mining will continue in this country. In fact, it appears that our production is holding fairly steady at about a billion tons a year. And predictions that I have seen indicate this will continue for the next few years. What impact the Environmental Protection Agency’s Clean Power Plan will have beyond 2020 is another question.What do you feel is the future of the minerals industry - near term and longer term?Our society depends on the future of minerals in this country being strong. Near term, we are going through some of the typical cycles. Having also been involved in aggregates during the last few years, the business follows government infrastructure projects, such as highway construction and public and private sector development. Those sectors are heavily dependent upon government spending and a strong economy. Increased spending in those sectors, which appears to be on the horizon, should provide additional market shares for aggregates."

Jan 1, 2014

By Ehsan Moradabadi, Debra F. Laefer

"To more rigorously address tunneling risks to above-ground structures, vulnerability evaluation of all structures along a tunnel route is required. This multi-block area along the route can be considered a district. To fully assess each structure within a tunnel’s zone of influence, a multi-block or district-level model may provide new insights as to risk evaluation and mitigation strategies. However populating such a model with the existing geometry of the built environment poses a major challenge as measured drawings are not readily available for all structures along a tunnel’s route. Cost-effective population of such a model could arguably involve remote sensing data in the form of laser scanning or photogramme-try. However even for unreinforced masonry structures, where external, above-ground geometries can be captured, without a prohibitively expensive building-by-building, in person survey many factors would remain unknown. To consider these uncertainties in an automatic way, a performance assess-ment framework is proposed. Such a framework allows a more rigorous, initial, risk quantification than is currently possible within the simple empirical models generally being used in industry when tunneling risk is initially assessed. This paper introduces (within the allowable space limits of this format) consider-ations for auto-population and application of a district-level, tunnel-risk screening tool. INTRODUCTION Challenging topography, intense urbanization and infrastructure development, combined with limited land availability and a growing awareness of environmental issues have lead to increasing usage of un-derground spaces to control aboveground traffic and provide essential services in metropolitan areas. Tunneling, however, is not without its own risks, especially with respect to aboveground structures whether it be widespread minor damage (Burland et al. 2001) or the more notable, although less fre-quent, large-scale collapses such as the 2003 Shanghai (Allianz 2015) or 2004 Singapore (Magnus et al. 2005) events."

Jan 1, 2016

By E. D. Attanasi

Exploration for non-fuel minerals has declined since 1988 as recessionary pressures have slowed growth in the industrialized economies. By most accounts, however, 1990 expenditures were still significantly greater than the low levels experienced in the mid-1980s. The Persian Gulf crisis introduced instability in energy prices and greater uncertainty into an already cloudy economic picture. As 1990 unfolded, the US savings and loan problems spread to the commercial banking system, leading to the failure of several major US commercial banks. The Japanese stock market also suffered significant losses as Japan's Central Bank raised interest rates. The Soviet Union experienced shortages of food and other basic items. Its government faces resistance to changes leading to a market economy. Individual Soviet republics also are seeking more control of their own destiny. The cost of German reunification, in terms of the capital required to bring the east's infrastructure and industrial base to western standards, also appears to have been underestimated.

Jan 1, 1991

By Robert Stefanko

The results of a recent study on the influence of continuous and conventional mining techniques on the size consist and wash- ability characteristics of coal are presented. Eight samples, four each from continuous and conventional mining sections were collected. Each sample was screened in seven size fractions, and each size fraction was totally fractionated at five gravities. The data thus collected was statistically examined for the influence significance of mining techniques, size, and gravity on the quality of the mined product. The paper presents the sample collection method, data gathering and analysis procedures, and major conclusions. The study revealed that there are pronounced differences in the products from the two mining systems and that conventional mining yielded a better product in terms of size-consist, and yield, ash, and sulfur in both the raw and washed products. The results of the study are significant in regard to consideration of resource utilization and conservation, and environmental impacts.

Jan 1, 1974

By T. Tamagawa, S. H. Tabaian, I. Iwasaki, N. X. Fu, M. Kobayashi

A gaseous chlorination process for the hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low-temperature chlorination -selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide. In this article, the chlorination phase of the process is described. Initially, the chlorination behavior of chalcopyrite concentrate micropellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established were used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 2000

By B. W. Cavender

Capital investments are made for a variety of reasons, ranging from providing incremental capacity at existing operations to developing and implementing new technologies intended to radically improve a company's capabilities. These projects generate very different business opportunities and create value in distinctive ways. For incremental improvements, the capital budgeting process assures at least a loose fit between short-term goals and readily available resources. However, the criteria used to evaluate capital projects often prevent a company from committing to more aggressive goals, which lie beyond the firm's current abilities or resources. Such projects may not have clearly identifiable future cash flows, and the degree of interaction with other projects and the nature of the risk incurred may be difficult to estimate. Additionally, by focusing only on quantifiable benefits, the budgeting process often fails to recognize "soft" improvements such as increased operating flexibility or new knowledge generated by such projects. By rejecting these projects, the capital budgeting process may actually harm the company's future competitive position.

Jan 1, 1999

By C. J. Webb, C. J. Paterson, A. Davis

This work focused on identifying, examining and ranking the physical and environmental hazards at inactive and abandoned mine sites in the Black Hills of South Dakota. Earlier inventory projects in the Black Hills concentrated on federal lands, while more recent efforts have examined abandoned mines on state and private lands. The more recent efforts are a result of passage of legislation by the State of South Dakota requiring a comprehensive inventory. The inventory information provides criteria for identifying those sites that require further investigation or characterization of the physical safety or environmental hazards. For most AML sites in the Black Hills, location information is all that is typically needed, because the majority of sites pose little environmental or physical hazard.

Jan 1, 1999

By S. Amirshenava, S. Nadimi

"Premature and unplanned mine closure can result in significant adverse impacts on the environment and community and need to be managed appropriately. Risk management techniques can reduce the negative impacts and risks of early mine closure. Risk Assessment 3D Model, is an efficient tool to quantify risk. The aim of this paper is to identify the mine closure risks in Choghart iron ore mine, and calculate the overall mine closure risk level. The result shows that 51.4% of assessed risks have low risk level and the overall risk level of early mine closure is low. Keywords: mine closure, risk assessment 3D model, Choghart iron ore mine INTRODUCTION The modern mining life-cycle can be divided into three main stages; exploration, mining (opening and production) and post mining (mine closure, and reclamation). Mine closure is the critical component of the modern mining life-cycle and it refers to the period of time when the operational stage of a mine has permanently ceases (Heikkinen et al, 2008). Planned closure occurs due to the depletion of ore reserves, but sometimes it is premature. Laurance (2006) shows that only 25% of mine closure in the past 30 years was due to resource depletion and in 75% of the cases the mines were closed for the other reasons. Ghanbari et al (2010) demonstrated that 48.6 % of copper mine closure in the past 100 years was due to resource depletion and 51.4 % of copper mines have been closed due to other reasons. The main reasons of premature mine closure are as follow (Laurance, 2006; Ghanbari et al, 2010; Maiti, 2013): • Economic, (low commodity prices or high costs) • Geological, (over-estimation of grade and tonnage) • Geotechnical (adverse geotechnical conditions) • Technical (equipment failure) • Regulatory, due to safety or environmental breaches • Social or community pressures • Closure of downstream industry or markets • Flooding or inrush Minaei Mobtaker and Osanloo (2013) developed a mine closure prediction model based on the data collected from closed iron ore mines in the past 100 years. They showed that economic factors, exhaustion of ore reserve and geological conditions are the main reasons of iron ore mine closure. They treated mine closure as a decision making problem in order to predict the causes of mine closure, including the uncertainties of some mine plan parameter such as iron ore price, production and consumption."

Jan 1, 2016

By R. A. Winters

At the operations level, productivity is a principle key to profitability. If you are competing with other mines that are paying roughly the same wage rate and the same prices for capital, materials, and energy, the only way your profit can be greater is by producing more output per unit of input. Mines with higher productivity have higher profit margins. Higher profit margins lead to greater operating cash flow, and cash flow is what distinguishes a dog from a cash cow. The turnaround in U.S. metals during the 1980s was in large part due to incredible improvements in productivity. According to statistics compiled by Kaufmann, 1991, labor productivity, measured as tonnes of primary production/manhour, increased 64% in steel, 94% in copper, 75% in lead, 143% in zinc, 132% in molybdenum, and 75% in gold. These improvements were hard won. However, with most modernization programs now complete, measuring and monitoring productivity becomes even more important as producers strive to maintain the gains they have achieved.

Jan 1, 1993

By Kostas Fytas

Canada still remains today a strong resource nation with a huge geological potential. Canada ranks among the top five leading countries in the production of 15 major minerals. Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage production. It is estimated that across Canada there are a few thousand abandoned mine sites as a result of the last fifty years of mining. Most of these sites are acid producing presenting a serious threat to the environment. It has been estimated that the cost of stabilizing and reclaiming these sites across Canada will be over $5 billion over the next twenty years. Current practices for decommissioning acid producing sites are water covers (flooding), dry covers, revegetation and treatment of the acid effluents. This paper presents the technical and legal issues of mine closure and reclamation in Canada. The methods used in the revegetation of acid producing mine sites is also presented This paper also reviews the financial guarantee requirements for mine closure by the provincial legislations in Canada. A case study of stabilizing and reclaiming a sulphide tailings area in the Sudbury region is presented. It illustrates the challenges facing the Canadian Government and the mining companies in restoring and revegetating the closed and abandoned mine sites across Canada.

Jan 1, 2002

By R. D. Doepker, P. L. Drake

The dissolution of metals from various metal- mine tailings has been studied through a series of submerged tailings batch tests at US Bureau of Mines laboratories. Tailings selected for this study included both reactive (as determined by column leaching studies) and benign tailings. Metal mobilization in aerated (97% saturated with oxygen) samples appeared to be consistently greater than metal dissolution from stagnant (79% or 70% saturated with oxygen) waters. In the early weeks of the study, sulfate concentrations increased with solid-liquid contact time, while calcium dissolution remained early constant. Metal concentrations varied in relation to solid-liquid contact time and aeration. Leachate pH appeared to be nearly independent of solid-liquid contact time for basic tailings. Reactive tailings having both a submerged and a surface component demonstrated increased metal mobility.

Jan 1, 1991

By R. F. Kovar, R. N. Torbin, R. E. Gundersen

I have to express my .surprise and must send a note of warning concerning the use of polyurethane foam as described in a paper by R.N. Torbin and R.F. Kovar, entitled "Innovative Shaft Lining Method," published in your February 1989 edition. In September, 1986, 177 miners lost their lives when they were exposed to fumes downwind from a fire in a tunnel lined with polyurethane foam. Whilst polyurethane exhibits reasonable fire retardent properties in small-scale tests, mass use in a tubular configuration, exacerbated by the furnace effect of cross-radiation, can lead to a rapid, uncontrollable conflagration. I do not wish these comments to detract from the engineering achievements of the authors but rather to sound a loud warning as to the application of the system. Any shaft designed for human access- be it for transport or shaft work - and any intake airway, should not consider the use of polyurethane foam. It only needs a slip with a cutting torch or an electric fault to initiate a disaster. Many countries have banned or restricted the use of polyurethane foam in the workings of a mine and maybe alternative foams (e.g. phenolics) can be used or developed

Jan 1, 1991