Search Documents

By D. Kimball, P. Chambers

"BACKGROUND In the event of an explosion or fire in an underground mine, workers can be exposed to a deficiency of oxygen, an excess of carbon monoxide, or both. These threats can occur as separate conditions or simultaneously. A lack of oxygen in the breathing air can only be addressed via the use of a self-contained breathing apparatus (SCBA) acting as a source of oxygen. An excess of carbon monoxide can also be addressed via the use of an SCBA, but if the threat occurs in isolation (that is, the atmosphere still contains sufficient oxygen to support life) and the concentration of the threat gas is not extreme (< 2%) then the carbon monoxide threat can also be addressed by the use of a filter self-rescuer (FSR). Used together, the SCBA and FSR offer a far more efficient and universally capable life support system than when used in isolation. However, the SCBA does not take advantage of the fact that the surrounding atmosphere likely contains some level of useable oxygen; i.e., the SCBA always supplies the total required oxygen from its limited supply, resulting in a ceiling on its useful life regardless of the level of oxygen in the surrounding air. To address this technology gap, what is needed is a ""smart"" SCBA that provides filtration and catalytic protection against threat gasses and has an extended duration life-sustaining oxygen inhale stream independent of the threat content and oxygen deficiency of the surrounding atmosphere. DEVELOPMENT Developed under contract with NIOSH the Smart Escape SCBA is comprised of three major components including; 1) oxygen supply, 2) oxygen sensing & dosing electronics and, 3) a CO catalyst and carbon bed broad spectrum FSR. The SCBA is designed as a hybrid system that provides non-toxic breathing air by using an approved Chemical, Biological, Radiological and Nuclear filter self-rescuer and a catalyst to convert high levels of carbon monoxide to harmless carbon dioxide (CBRN FSR/CO). In addition, the Oxygen Sensing & Dosing Electronics (OSDE) package adds sufficient oxygen to make up for deficiencies detected in the ambient air (Figure 1). By making use of the ambient oxygen, less oxygen is required for a one-hour unit life. This means that the Smart Escape SCBA fits in a smaller and lighter package than a similar-duration conventional Self-Contained Self-Rescuers (SCSR). Alternatively, taking advantage of available ambient oxygen could offer a significant increase in working duration in a unit with the same size as current SCSRs. The research performed under this NIOSH contract involved numerous tasks including: (1) definition of performance and system requirements for the Smart Escape SCBA, including keeping environmental stressors within acceptable ranges, providing at least one hour of breathable oxygen supply, and using a mask or hood that allows high-quality voice communication; (2) designing, building, and evaluating prototype units to support extensive bench top testing at Avon Protection and third party labs to demonstrate the device’s capabilities; (3) building sufficient quantity of Smart Escape SCBAs designed to be intrinsically safe (per MSHA criteria); (4) testing and evaluation by the National Personal Protective Technology Laboratory (NPPTL)."

Jan 1, 2015

By William H. Lehr

In recent years, we have witnessed many innovations in the equipment used in handling bulk materials. Not too long ago, any sizeable stockpile of coal or iron ore was attended by one or more material handling bridges. More recently, large stockpiles have been built with mobile equipment of&apos; the earth moving type with bulldozers and front end Loaders being utilized in reclaiming operations. The most recent stocking and reclaiming device is the rotary bucket wheel machine. The early bucket wheel machines built in the United States were developed for the strip mining of coal. We understand that the first American machine was built in the Midwest in 1944. This type of unit was developed in an effort to reduce the cost of removing overburden and to provide satisfactory spoil disposal. As the available coal reserves under shallow cover were exhausted, the cost of removing the deeper overburden with conventional equipment became too great for these operations to continue profitably. The first machine has now been followed by six or seven additional units, the largest of which can handle material at a rate of more than 7000 cubic yards per hour.

Jan 1, 1965

By W. L. Jacobsen, T. L. Dyer

Cortez Gold Mines completed a feasibility study for a new openpit gold mine in north central Nevada. The production schedule calls for a peak in material movement. This schedule is based on current operational efficiencies and equipment parameters observed at the company’s existing openpit operation. To mitigate risks of over/under predicting production, simulation modeling was used to validate the loading and haulage requirements during the peak production period. The advantage of simulation is the ability to provide a realistic model of a mining operation based on scheduled and unscheduled random events during the period under analysis.

Jan 1, 2007

By T. R. Ellis

The author attempted to concurrently apply the US Uniform Standards of Professional Appraisal Practice and the Australian VALMIN Code to a complex mineral property appraisal assignment. This led the author into many severe difficulties. These difficulties included the high standards needed in the work of others, and information and statements needed from the client. The exercise also highlighted many positive features of both documents. Some conflicts were found between the two documents. Implications and thoughts regarding the development of a set of US minerals appraisal standards are discussed.

Jan 1, 2000

By Thos. B. Douglas

In 1907, the Oklahoma Portland. Cement Company built a small dry process plant at Ada, Oklahoma, then Indian Territory. This plant was later acquired by the Ideal Cement Company of Denver, Colorado, who in 1918 built a new wet process plant along side the old dry plant. The older plant was later shut down .and eventually razed. In 1955, the Ideal Cement Company decided to increase the production at its Ada, Oklahoma operations. After many studies it was decided to build a complete new plant along side the old, near the site of the original 1907 plant. .The new plant was to have a. production of three million barrels annually while the plant then in. operation had an annual production of two and one quarter million barrels

Jan 1, 1961

By Phil Pennington, D. Jack Adams

Mining and processing of minerals, metals, and fossil fuels can release selenium and arsenic into wastewaters. Both selenium and arsenic are difficult to remove to levels that meet current drinking water and discharge criteria. These metalloids can be used as electron acceptors by microorganisms transforming them back to reduced states, thus removing or stabilizing them. Bioremediation cost effectiveness will be discussed in terms of site information required, microbial populations, co-contaminants, pH, redox, and nutrients. Full-scale, economical ex situ and in situ biotreatments are possible and can produce 1,000’s of times less sludge than conventional precipitation technologies.

Jan 1, 2005

By W. Z. Rogers

U.S. feldspar output sold or used in 2005 was an estimated 760 kt (838,000 st), valued at $44 million free-on-board plant. This was below the 2004 volume and was the second year of decline in a row. Output included flotation concentrates, feldspar content in feldspar-silica mixtures, potash feldspar and aplite. The strong housing market in the United States maintained demand for ceramic tiles, plumbing fixtures and fiberglass insulation requiring feldspar. Shipments of glass containers were about the same as in 2004. Imports of ceramic tiles and plumbing fixtures continued to increase, taking the place of U.S.-produced goods and the feldspar required to make them. For 2005, 80 percent of the ceramic tiles sold and 50 percent of the plumbing fixtures sold in the United States were imported. Since 2000, manufacturing plant closures in the plumbing fixtures industry have reduced the demand for feldspar and feldspar-silica mixtures by 100 kt (110,000 st). Increased demand from the ceramic tile industry has partially offset the lost volume.

Jan 1, 2006

By D. Bogh

Wound rotor motors are used in difficult mining applications where there is a need to start high inertia, hard starting loads while limiting inrush current They are recognized as robust and simple to control. This paper will cover the performance, specification, and important issues to be considered when applying medium voltage wound rotor motors in mining applications. Medium voltage grinding, crusher, and conveyor applications will be discussed. Specifically covered are motor efficiency, speed range, and rotor control. Crane motors often have wound rotor construction, but their load cycle and ratings are outside the scope of this paper.

Jan 1, 2011

By P. Harris, G. Groenmeyer, L. Parolis

The effect of molecular weight, charge and the presence of the cations Ca2+, Mg2+and K+ on the adsorption of carboxymethyl cellulose on pure talc obtained from Balmat, New York have been investigated. Higher adsorption densities were obtained in the presence ofCa2+ and Mg2+ ions than with K+ ions and higher ionic strength solutions resulted in higher adsorption densities. Changing the molecular weight did not influence the adsorption however increasing the charge (DS) of the polymers resulted in lower adsorption densities.

Jan 1, 2004

By Ray H. Hario

Background of Erie Mining Company Erie Mining Company, managed by Pickands Mather & Co., is one of the largest producers of iron ore pellets in the United States. The plant is located at Hoyt Lakes, Minnesota, sixty-five miles north of Duluth on the eastern end of the Mesabi Range. Taconite Harbor, situated on the north shore of Lake Superior, is the location of its Power Plant and shipping facilities. (Figure 1) Even though the plant commenced operation in September, 1957, its true be-ginning can be traced back to 1931 when Pickands Mather, in conjunction with Bethlehem Steel Corporation and Youngstown Sheet and Tube Company, began investi-gating the possibilities of processing low grade ores. In 1940, Erie Mining , Company was formed. During the early and middle 1940&apos;s, laboratory and pilot plant research was proven to a point where a preliminary plant was deemed feasible and built in 1948. This plant had an annual capacity of 203,200 t (200,000 long tons) per year and, until mid-1952, was the only taconite plant in existence using commercial-size equipment. During this period, ownership of Erie Mining Company was expanded to include Interlake, Inc. and The Steel Company of Canada, Limited. In 1953, authorization was obtained from the owners to build a 7.62 M t (7.5 M long tons) per year plant at a cost in excess of $300,000,000.

Jan 1, 1977

By J. M. Wempen

As development in underground coal mines progresses away from the critical components of the ventilation system, including the main fans and ventilation shafts, resistance is markedly increased. This results in higher pressure and flow requirements from the main fan(s) to maintain adequate face ventilation, which often requires that the primary ventilation system is upgraded with additional shafts and surface fans. The use of booster fans underground is a potentially practical alternative. This study presents simulations of the use of booster fans in two underground ventilation scenarios, one longwall and one room and pillar. The booster fan effects on the power requirements of the ventilation systems are evaluated.

Jan 1, 2011

By J. D. Bliss

The discovery that triggered the current gold rush in southeastern Peru was made in about 1975 along the Rio Madre de Dios in Madre de Dios Department (Fig. 1). About 5000 to 10,000 miners (called chichiqueros) were working in the area as of 1990. Placer mining is the principal source of revenue for people living along the Rio Inambari and west of Puerto Maldonado. As in past gold rushes, working and living condition are harsh. Supplies are expensive, and the area has poor access compared with other areas in Peru. Food, fuel and all mining supplies are trucked over dirt roads from Cuzco, a three-to-five-day trip (Fig. 1). Some material also comes from Brazil. Many placers have a similar life cycle, beginning with small-volume mining (surface or underground). At the end of this small-scale mining, the placer is exhausted or it has a sufficient volume of gravel high enough in gold grade to be worked by large-volume methods, which lead to exhaustion of the resource. The level of maturity of a placer can be determined from its gold grade. The amount of gold production from large-volume mining can be predicted, given detailed, cumulative gold-production data on placer deposits during small-scale mining (Bliss et al., 1987). Using this general model, the authors analyzed the placers in the Rio Madre de Dios area. Small-volume mining Most placer mining in the Rio Madre de Dios area is in alluvial deposits either in or bordering the major rivers. Locally, some placer mining is in terrace deposits above the rivers. All minerals (including the subsoil) in Peru belong to the state. However, a mining claim (denuncia) is easily obtained for mineral exploitation. It is separate from property ownership.

Jan 1, 1992

In 1991, Placer Dome Venezuela established a 70% stake in Minera Las Cristinas, to mine the Las Cristinas gold deposits in Bolivar. This case study examines the multi-sectoral partnership arrangement that was developed to improve health services near the proposed Las Cristinas gold mine. The investment climate in Venezuela is uncertain and the socio-economic circumstances are potentially hostile. Despite that, the partnership between the mining company, local communities, government agencies and an international health nongovernmental organization (NGO) collectively leveraged nearly $2.5 million to build and operate a community health center.

Jan 1, 2002

By J. Kallioinen

The development of mechanical flotation cells has resulted in larger and better cells. This has led to flotation banks with only a few units, even in large-scale operations. This equipment development makes the old operational considerations ineffective. The flotation cell must be considered as a single reactor unit capable of handling specific tasks and getting excellent metallurgical performance. The result of the unit reactor concept development was the new large TankCell that comes in sizes up to 113 m3 (4,000 cu ft). The TankCell construction includes new modified rotor-stator designs, new tank geometries and a froth-handling capability independent from subprocesses taking place in the pulp (i.e., air addition). The conventional idea of a single flotation cell type for fine, intermediate and coarse materials does not give optimal results. Optimal flotation of coarse and fine particles needs different mechanism designs, impeller tip speeds and different froth control objectives.

Jan 1, 1995

At present, discounted cash flow analysis is generally accepted as the preferred method of valuation of mine projects in surface coal mining. One of the major reasons for that is its ability to take into account the time effect of money over the life-of-mine. As a looking-forward method, it requires forecasts be made with regard to economic, technological, technical, geological, and environmental conditions that will prevail in the future. All forecasts are inherently uncertain as they are a function of the uncertainty of all variables of the discounted cash flows analysis. This indicates that the only alternative for modeling the uncertainty in the project evaluation is the development of adequate risk models to serve the decision-making process. The paper offers a model of project cash flows at risk in strip coal mining, which is an integrated corporate risk management solution. The model is based on a stochastic approach that provides the answer to the question about how large is the deviation between stochastic cash flows and the planned value (or that used in the budget) at each time step of the discounted cash flows analysis, that is due to the uncertainty in the model variables. A solution is worked out for the allowable range of the stochastic cash flows variation that determines the probability of achieving the planned value of a mine project. The Monte Carlo simulation technique is used to model the stochastic behavior of the project variables. A case study of an opencast coal mine project is provided to illustrate the applicability of the risk model. The results obtained provide a new understanding of the mine project risk as a component of the project discount rate.

Jan 1, 2006

By Stephen Davies

Mining at Hudson Bay Mining & Smelting&apos;s Snow Lake Division is now in the mature stage of the mines&apos; lives. These base metal copper-zinc mines have been operating for more than 30 years. Stopes had small pillars called "crown pillars" left between them. These pillars range up to 100 m (330 ft) long by 40 m (130 ft) wide and 15 m (50 ft) thick. Hudson Bay have been successful in removing these pillars by using cable slings, electric scoops, longhole mining and diesel load-haul-dump equipment. The different shapes and sizes of these pillars has required that many innovative techniques be tried in order to find acceptable economic mining methods. An overview of the different methods will be outlined. Background Hudson Bay Mining & Smelting&apos;s Snow Lake Division is located in Manitoba some 800 km (500 miles) north of Winnipeg and 200 km (125 miles) by road from the Hudson Bay smelter complex located in Flin Flon, Manitoba (Fig. I). There are currently three producing underground mines and one open pit operating at the Snow Lake Division, producing copper and zinc concentrates. Pillar recovery is intensive and vital to continued production of these mature mines. The crown pillars are producing more than 50% of the current mine production. This figure will increase in the future. The two mines at which crown pillar recovery is taking place and that will be discussed are the 400 t/d (440 stpd) Rod Mine and the 1000 t/d (1100 stpd) Stall Lake Mine, both five-day-a-week producers. Crown pillar mining has been applied for some time at these mines. However, it was only recently that the crown pillars became vital to production. This has necessitated a number of innovative techniques to recover them.

Jan 1, 1992

By DING TANG, JINGHE CHEN, Shuiping Zhong, CHEN KUANG

The Zijinshan gold-copper mine, in spite of the low-grade nature of the ore, has become one of the largest production-scale and most profitable non-ferrous metal mines in China. The successful application of hydrometallurgy as well as proper engineering design are the key factors for large-scale development of the Zijinshan gold-copper mine. In this contribution, the practical experience acquired in the development of the Zijinshan gold and copper mines is summarized. This covers most aspects of the production process including mining, beneficiation, ore stacking, heap (bio)leaching, carbon-in-leach, solvent extraction, electrowinning, wastewater and tailing treatments. The authors believe that this practical experience will not only help to promote the development of hydrometallurgy, but can also serve as a model for other gold and/or copper plants around the world.

Jun 3, 2020

By T. Mudder, R. Cellan, R. Waterland, J. Whitlock, B. N. Nelson

The effectiveness of anaerobic in-situ biological treatment for the immobilization of selenium, molybdenum, and uranium in an alluvial aquifer was examined using long-term column tests. A series of organic substrate and nutrient combinations were tested to determine removal effectiveness, optimum supplement concentrations and ratios. Final column testing was conducted to determine the chemical stability of the treatment by-products/treatment compounds by dosing the columns continuously with elevated redox untreated alluvial groundwater.

Jan 1, 2002

There is wide agreement that sustainability has multiple dimensions, but substantially less agreement on the appropriate balance among those dimensions. This occurs because peoples’ vision of a sustainable future, their goals for sustainable development, and their objectives for resource management are reflections of their values, culture, and life experiences. Even assuming agreement about the objectives of sustainable resource management can be reached; there is still a need for policy and decision makers to choose from among alternative courses of action, each of which has its own set of impacts and outcomes. One of several tools used to compare the consequences of alternative actions is the Computable General Equilibrium (CGE) model. This paper uses CGE modeling to demonstrate how policy decisions do not take place in a vacuum and how policy-makers must be aware that there are trade-offs involved in any decision.

Jan 1, 2005

By M. Javier

Mining is an industry of experimentation throughout human history. Recently, societies are giving a clear message about mining because many projects are being rejected around the world. These refusals are a generational reaction to the activity of mining. In practice, it generates the perception that mining is using the same methodology without attending to the gradual initiation of conflicts. This is in spite of the best engineering and technology of the time that are put in place at the presentation of those mining projects. Some of these rejected projects are geographically distant from each other, but the communities? rejection occurred during many cases under similar characteristics. This concern shows that the current model of mining projects needs to be replaced with a new one: A new Design, one within which the socio-environmental values of this millennium are inherent. This paper describes Mining Project 101 to help the industry to set the highest and cleanest standards for mining. It also presents its aspects to sustainability and nature, which provides the principles and procedures for designing, planning, and operating mining projects with sensitivity to nature. It offers methods of diagnostic, remediation, and extraction while at the same time preventing and preserving a physical, chemical, and biological equilibrium of nature. This emerging process will be a step up from having a mining industry unaccountable to the socio-environmental conflicts it perpetrates and will abandon the ?cosmetic? repair on the caducity of traditional models in today?s practice. In conclusion, we have the opportunity to change this model. KEYWORDS: Equilibrium in Nature, Geomímic, Deproduction, mine design.

Feb 27, 2013