Search Documents

By Carrie Pourvahidi

The California High Speed Rail Authority (Authority) was created by the State of California through legislation in 1996. The purpose of the Authority is to plan, construct, finance and operate a statewide intercity high speed passenger rail system. In 2004 the Authority prepared a programmatic level environmental document in compliance with the California Environmental Quality and National Environmental Protection Acts (CEQA and NEPA).The Authority and Federal Railroad Administration (FRA) were the lead agencies overseeing the development of the environmental documentation. The resulting document includes two volumes and 64 supplemental technical reports analyzing the transportation needs for California and the selection of an approach to meeting the project transportation needs. The Programmatic Environmental Impact Report and Environmental Impact Statement (EIR/EIS) identified High Speed Rail as the most environ-mentally protective, sustainable and economical approach to meeting the state?s projected transportation needs.

Jan 1, 2008

By J. L. Cupp, R. C. Ford, B. R. Romig

The Climax Molybdenum Mine, located near Leadville, Colorado, is the site of a lengthy mining history spanning more than 80 years. In the 1960’s, extraction of molybdenum from oxide ore located adjacent to the massive molybdenite sulfide deposit resulted in the construction of an earthen core dam to impound fine-grained oxide tailing in the Eagle River Valley. Through recognized value of water storage and reclamation opportunities, a tailing removal project was initiated in 1993 to convert the impoundment facilities to a post-mining beneficial land use of developed water resources. An evaluation of the effect residual materials and lake dynamics would have on in-stream water quality was performed. Eagle Park Reservoir stands as a model for future reclamation efforts that involve water delivery to highly sensitive receiving waters. This paper provides a case study on project development, the evolution of water quality assessment, and the regulatory framework that contributed to this project’s success.

Jan 1, 1999

By D. Brady

The need for onsite gas monitoring during, or following, a major incident at an underground coal mine has long been recognised. Recommendations from inquiries following Queensland mine disasters have included ?qualified persons and equipment for rapid analysis of gas samples be available in times of emergency? and that ?this may be accomplished by either mobile laboratories or laboratories established in each mining locality.? Following the Moura No. 2 disaster, the Queensland Government allocated funds to Simtars for a mobile laboratory to respond should such a disaster occur again in the future. This vehicle was commissioned in 1997 and has been used at many mine sites under a wide range of scenarios. Simtars, armed with over ten years of operational experience with this mobile laboratory, has taken an active role in the design and construction of a modernised replacement unit. With a twenty point tube bundle system and ultrafast gas chromatograph the result is, arguably, the best equipped mobile gas analysis laboratory for mine emergency response in the world. This paper outlines the features of the new laboratory, its capabilities and the philosophy behind the design and inclusions.

Jan 1, 2012

By J. C. Reid

Pre-cambrian scheelite deposits in Northeastern Brazil are widespread in a high grade metamorphic terrain. Previously these deposits had been interpreted as contact-metasomatic. In this paper, a volcanigenic model is invoked based on the volcanic setting (proximal to distal) and the absence of associated felsic intrusives and spatially associated metasomatic skarns. The tungsten was introduced into sediments by volcanic- exhalative processes and subsequently remobilized and further concentrated by heat and metamorphis fluids associated with high-grade metamorphism and migmitization. An alternative syngenetic - diagenetic model is discussed which requires the transport of tungsten by heteropoly acids and deposition of the tungsten as a function of Eh and Ph conditions and different clastic depositional environments. While such stratabound tungsten deposits are considered rare in North America, the hypotheses developed in this paper may open new areas for exploration.

Jan 1, 1983

By D. McSwain-Santos

Soda ash is the trade name for sodium carbonate, a chemical refined from the mineral trona or naturally occurring sodium carbonate-bearing brines (both referred to as natural soda ash) or manufactured from one of several chemical processes (referred to as synthetic soda ash). It is an essential raw material in glass, chemicals, detergents and other important industrial products. Production U.S. soda ash production during 2004 increased to10.9 million Mt (12 million st). Five companies comprised the domestic soda ash industry. Four were in Wyoming operating five plants. One was in California with one plant.

Jan 1, 2005

By Bruce Bryant

Silver ore was discovered at Aspen in 1879, but the district did not reach full production until 1888 after lawsuits were settled and railroads furnished less expensive transportation to the outside world. The boom years were 1888-92; production declined thereafter. From the middle 1920's until 1950, the Midnight mine in the Richmond Hill district furnished most of the output in the Aspen quadrangle. Since 1950, little mining has been done at Aspen. The metals produced were silver, lead and zinc. Native silver dissolved from the sulfide ores was redeposited by waters circulating as deep as 300 m below the land surface, resulting in great secondary enrichment of many of the deposits. Over 100 million ounces of silver were produced in the Aspen quadrangle. Low-grade lead-zinc deposits remain between the old workings locally, and data available suggest that primary ore below levels mined is also of low grade. The ore occurs in the Mississippian Leadville Limestone and the lower part of the Pennsylvanian Belden Formation in sites that were made favorable for deposition by a number of stratigraphic and structural factors.

Jan 1, 1982

By Mohamed Yusuff

Modern transportation systems are one of the most important achievements of our civilization and provide us with tools for broadening individual and social freedom of choice. The transportation system initiated today is handed dawn to the next generation, probably with little choice because of the enormous expenditure of monies involved, and influence their way of life as to where they should live and where they should work. The ever increasing antagonism between the citizens and the planners of the transportation systems necessitates a careful review of the entire planning process. The planning process can be broadly classified into: the goal formulation and decision making process; the plan development process; and the plan implementation process. THE GOAL FORMULATION AND DECISION MAKING PROCESS Goal formulation and decision making is one of the vital phases of the planning process and is primarily based upon social values. In measuring social values, the planner must employ an appropriate scale of measurement since in the absence of this yardstick, these values tend to became vague and abstract ideals. The need for major social programs and concerns (poverty, etc.) of the urban areas should be analyzed to determine the type of transportation system which would contribute to the solution.

Jan 1, 1974

Preface The intention of this paper is to provide the reader with knowledge gained here at Memorial University regarding the practical use of the Bruker SDD x-ray detector for applications in image analysis. Included below are descriptions of the detector’s characteristics and observations regarding precautionary use. What is described below is relevant to the XFlash® model 3001 detector only, whereas the model 4010 is the new and currently available detector. The manufacturer has provided up-to-date information and a figure that presents very different behaviour relative to the characteristics described in this paper. That information and figure is also included here as an addendum (see figure 9). Introduction It has been more than two decades since an image analyzer has been proposed based on the unique imaging characteristics and spatial resolution provided by the scanning electron microscope (SEM) together with energy discriminating x-ray (EDX) acquisition (Reid et al, 1984). From the inception of technique, technology of the day has played the major role for making applications increasingly more practical. Computers, digital imaging, and softwares together with computer automation of modern digital SEMs have all played their part in advancing the technique to where it is today.

Jan 1, 2007

By N. Ahmed

The collection of hydrophobic particles in the froth phase in flotation has been studied. A continuous flotation cell was developed, in which the froth phase could be isolated from the pulp zone. Hematite particles, d80 = 87 µm, were floated in the pulp, using a conventional oleate collector, while glass spheres of similar diameter, d80 = 82 µm, were introduced in wash water added to the froth. Four samples of glass spheres, with contact angles between 0 and 82 degrees, were used. The results indicate that the efficiency of collection of the hydrophobic particles in the froth can be very high. The process is strongly influenced by the hydrophobicity of the particles and the surface area available for attachment in the froth. Recommendations for the flotation of particles in the froth phase are made, especially regarding the desirable hydrophobicity as reflected in the contact angle, the froth depth, the solids concentration in the feed to the froth, the air rate and the wash water rate.

Jan 1, 2001

By K. Awuah-Offei

An aggregate plant may have difficulty balancing product stockpile inventories if hot mix asphalt (HMA) design engineers do not account for aggregate inventory during mix design. Yet HMA design engineers do not, often, take this into consideration during asphalt mix design. This is due to the lack of tools that enable the lab technician or engineer to optimize the mix for good performance while helping the aggregate plant manage its stockpile inventory levels and reducing the aggregate cost. This work presents a linear programming model of the asphalt mix design problem that helps aggregate plants manage their inventory levels while meeting HMA customer demands. The algorithm is implemented in MATLAB as an Asphalt Mix Design Optimization (AMIDO) program. The program is successfully validated with real-life data. The results show that AMIDO can be used to successfully produce any mix design while reducing the cost of aggregates by using the cheapest stockpile materials. The application of AMIDO will increase aggregate plant profitability when serving HMA customers and could potentially be modified for concrete aggregate customers too.

Jan 1, 2009

By D. G. Klaren

Self-cleaning fluidized bed heat exchangers are conquering the world for reason that they are able to solve any severe fouling problem in indirect heat transfer due to the circulation of cleaning particles through the tubes of vertical shell and tube exchangers. In most cases, these particles consist of chopped metal wire. Moreover, self-cleaning fluidized bed heat exchangers perform with excellent heat transfer at very low liquid velocities, which makes completely new designs of shell and tube configurations possible. Further, self-cleaning fluidized bed heat exchangers show a strong shear thinning effect in non-Newtonian liquids. All the above characteristics make the self-cleaning fluidized bed heat exchanger an ideal tool for the indirect heating of laterite nickel slurry in High-Pressure-Acid-Leach (HPAL) plants. Preliminary tests and evaluations of these heat exchangers have shown that the performance and price of these heat exchangers used for the production of nickel and cobalt from a laterite slurry, cannot be matched by existing conventional heat exchange systems. This article explains the principle, design, lay-out and enormous advantages of the self-cleaning fluidized bed heat exchange technology in a plant suitable for an annual production of approx. 45,000 ton nickel and 4,500 ton cobalt from laterite slurry through high pressure'acid leaching.

Jan 1, 2002

By M. Kuchta, A. Newman

LKAB’s Kiruna Mine, located in northern Sweden, produces about 24 Mton of iron ore yearly using sublevel caving. For efficiency, the mine must deliver planned quantities of three ore products. We use mixed integer programming to schedule Kiruna’s operations, specifically, which production blocks should be mined, and when they should be mined to minimize deviations from planned production quantities while adhering to mining restrictions (e.g., sequencing). A new production block database and a well-formulated mixed integer programming model dramatically reduce the size of the original problem; in less than ten minutes we generate five-year schedules with time fidelity of months.

Jan 1, 2002

By V. Galla

Waste rock facilities (WRF) generally have a large footprint depending on the strip ratio the mine plan provides. Considerable planning is involved during the initial phase of the mine plan regarding the location of the WRF. As the mining operations are commenced the locations of the WRF change accordingly with the variations in the mine plan involving feedback and support from local communities and stakeholders. Waste rock facilities management becomes challenging when the area available for placement is limited due to terrain topography, environmental and permitting constraints. Risks associated in the design of waste rock facilities constitute particle size of rock, chemistry associated with the rock for reactivity and stability of the over all facility. This paper will provide some insights on designing, scheduling and managing a WRF. Emphasis on geotechnical, geophysics and geochemistry aspects of waste rock with reference to design, construction process and scheduling of WRF are also presented. Design improvements in the reclamation slope of WRF for erosion control will be discussed. Continuous improvement (CI) methodology will be introduced in the process of WRF operations. Current practices and future recommendations towards sustainability and consistency in operating WRF will be discussed in conclusion.

Jan 1, 2011

By S. Fawell, H. R. Manouchehri

The main electrophysical properties, i.e., dielectric constant and electrical conductivity, of pure calcite, quartz and wollastonite mineral samples were measured and their triboelectric charge attributes were investigated by contacting minerals particles with different tribochargers made from different materials. In addition the energetic work function values for mineral samples were estimated due to their acquisition charge. Besides, the behaviour of triboelectrically charged of different particle size fractions of mineral samples were inferred. Finally an attempt were made to translate the findings from single mineral systems to a real carbonate ore. The results exposed good prospects to beneficate the examined minerals by triboelectric separation.

Jan 1, 2002

By A. D. S. Gillies

Inertisation is used to enhance the safety of underground mine areas either to avoid the potential for a combustion event or to stabilize a situation after an ignition, fire or heating. The primary objective of a recently completed Australian Coal Association Research Program (ACARP) study was to review coal mine inertisation and in particular to focus on use of the Polish mine fire simulation software Ventgraph to gain better understanding of how various inertisation units interact with the complex ventilation behavior underground during a substantial fire. Critical aspects targeted for examination under the project grant included location of the unit for high priority fire positions, size of borehole or pipe range required, time required for inertisation output to interact with and extinguish a fire, effects of seam gases on fire behavior with inertisation present and main fan management. A major accomplishment of the project has been to take findings from the simulation exercises to develop inertisation related modifications to the Ventgraph fire simulation program in conjunction with the Polish program authors. Selected mines were ?evaluated or audited?as to the ability to deliver inert gases generated from GAG units to high priority underground fire locations .A coding system has been developed and many potential underground mine fire sources cannot be successfully inertized with the GAG docked at the current specified point; this is particularly so for fires in extended areas of workings or in panels. There is a limit to the ability of the GAG jet engine to deliver exhaust down smaller dimension borehole. There is a need to examine the use of the GAG for production or proactive uses in a wider application in Australian mines responding to recovering from mine fires, spontaneous combustion heating?s, elimination of the potential explosibility of newly sealed gobs or inert mines or mine sections on closure. Some of the current uses of low flow inertisation facilities could be more effectively undertaken with the GAG unit.

Jan 1, 2009

By T. O. Dauda, L. O. Ojo

One of the results of the Earth summit (The United Nations Conference) on Environment and Development - UNDP is the statement of forest principles. Others include: the Rio Declaration which is that the human beings are entitled to a healthy and productive life in harmony with nature; Agenda 21-for achieving sustainable development in the 21st century; the convention on biological diversity and the frame work convention on climate change. In the preservation of the biological diversity, Government at various levels took series of steps such as legislation, establishment of forest reserves including strict nature reserves, Forest guards, afforestation projects and others. Omo Forest Reserves is one of the Forest reserves owned by the Ogun state Government of Nigeria. It houses the Omo Biosphere Reserve (that is Strict Nature Reserve of International standard). This biosphere reserve is surrounded by buffer zones, which are meant to serves as protection for the biosphere reserves against encroachments. This study showed that the richest plot in term of species composition (that is plot 15 with the species frequency of 123) is almost the least diverse (with Simpson diversity index of 0.9127 which is 0.0238 higher than the least). It could also be established from this study that the diameter size class of trees with the highest frequencies are the lower size classes (5cm-10cm and 10cm -20cm). These results revealed a magnanimous encroachment on the buffer zones, which is an indication of bad status for the Biosphere Reserves as well as against the spirit of the sustainable use of the natural resources.

Jan 1, 2005

By J. Gholamnejad

In open pit mine planning and design, push back mine sequencing is widely used for long-term production planning. In push back design, a series of nested pits is generated and then considered as possible push backs with regard to the minimum push back width requirements. These nested pits are produced by parameterizing on one economic parameters like commodity price, mining or processing cost, stripping ratio etc. The most important characterization of these push backs is that the inner most push back has the highest value per ton, the second inner most push back has the second highest value per ton and so on. These nested pits are generated based on the best estimates of grade within a representation of the ore body in a three dimensional matrix form. Therefore, the inherent uncertainty associated with reserve estimation (for our discussion grade uncertainty) is not taken into account when push backs are designed. These methods do not attempt to establish which part of the deposit is likely to be worth most. This paper introduced a new algorithm that incorporates ore grade uncertainty during push back design process. The suggested strategy tries to seek to schedule risky blocks later in the extraction sequence.

Jan 1, 2007

By J. MacFadyen

The U.S. cement industry experienced its best year ever during 2004 in terms of production and shipments of cement. Clinker, portland and masonry cements production and shipments were up considerably. Clinker production as reported to the U.S. Geological Survey (USGS) was 87.75 Mt (96.73 million st), an increase of 5.4 percent. Gray and white portland cement production from domestic and imported clinker was estimated to be 91.6 Mt (101 million st), up 5 Mt (5.5 million st) from 2003.

Jan 1, 2005

By A. J. Hendron, J. E. Monsees

INTRODUCTION This paper is the outgrowth of work done by the authors to prepare the seismic design criteria for underground structures on the Southern California Rapid Transit District (SCRTD) Metro Rail Project. It is a follow-on to a similar paper presented at the October, 1984, ASCE National Convention (17). For design, the earthquake-induced distortions recommended herein are to be added to the normal static loading conditions for the underground structure. This design approach has been used by 18 section designers on the SCRTD Project. Preliminary results from two- and three-dimensional finite element solutions have partially verified the approach. Areas where additional research is needed for special cases are identified. EFFECTS OF EARTHQUAKE The effects of earthquakes on underground structures may be broadly grouped into two general classes -shaking and faulting. In response to earthquake motion of bedrock (shaking) , the soil transmits energy by waves. Seismologists identify various types of earthquake waves, but underground engineers are generally interested in the effects of transverse shear waves which produce a displacement of the ground transverse to the axis of wave propagation. The orientation of propagation is generally random with respect to any specific structure. Waves

Jan 1, 1985

By Fritz Grübl

Modern shield TBMs allow tunnel drives through almost any type of ground. Thanks to high elaborated technical measures, significant subsidence of the ground surface can be almost entirely avoided. The tunnel lining behind the TBM must be capable of withstanding all loads without deforming, especially during ring erection and advance. Single-shell tunnel linings behind the TBM, usually reinforced concrete segmental rings, can be designed to fulfill this demand. With many projects, however, damage occurs to the lining. Repair costs may be extremely high. Reasons for damages and possibilities to avoid them are shown and explained.

Jan 1, 2001