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By Timothy P. Smirnoff

Sustaining the region?s mobility needs, achieving projected economic growth, and maintain Midtown Manhattan as a center of regional, national and global importance has led to continued investment in commuter rail and transit infrastructure in New York City and resulted in design and construction of large underground caverns. The current plans for stations in Manhattan include New York Penn Station Expansion (NYPSE) caverns for Trans Hudson Express (THE) Tunnel Project for New Jersey Transit (NJ Transit) and the Port Authority of New York and New Jersey (PANYNJ), Metropolitan Transportation Authority Capital Construction Long Island Railroad (MTACC/LIRR) twin caverns for East Side Access (ESA) Project, and station caverns of the No. 7 Line Subway Extension Project and Second Avenue Subway Project for Metropolitan Transportation Authority Capital Construction/New York City Transit (MTACC/NYCT). This paper provides a general overview of these large caverns now in design or construction in Manhattan, the area?s geologic setting, the geotechnical factors considered and approaches commonly applied for cavern design.

By T. A. Rundle, K. Kim, W. M. McCabe, E. C. Gregory

Overcoring tests were conducted at the Near-Surface Test Facility(NSTF) to assess the suitability of five techniques (U.S. Bureau of Mines borehole deformation gauge (BDG), Commonwealth Scientific and Industrial Research Organization (CSIRO) hollow inclusion stress cell, Luleå triaxial gauge (LuH gauge), and Council for Scientific and Industrial Research (CSIR) doorstopper) for in situ stress determination in a closely jointed basalt. This effort is in support of the Basalt Waste Isolation Project, which is studying the feasibility of locating a nuclear waste repository in the basalts of the Hanford Site in southeastern Washington. This paper presents the results from the overcoring study that formed the basis for selection of two techniques to be used during the further exploration of the basalt formations at depth.

Jan 1, 1983

By A. Almeida, D. Castro, K. Ingmarsson, D. Ferreira, R. Tamir

Mine-to-mill improvements can be initiated at any stage, but it is our assertion that drilling accuracy is a practical anchor in any operating mine or quarry for a structured continuous improvement process. This paper will: 1. Define deviations from plan and provide some best practices for maintaining drilling accuracy. 2. Introduce tools and methods to monitor and calculate consequences of accurate versus inaccurate drilling. 3. Demonstrate the use of these tools and methods and their impact on one cost item, the mitigation of oversized material by a hydraulic hammer. 4. Provide recommendations for implementing improvements.

Feb 1, 2023

By J. I. Schoenherr, G. Schubert, F. Demczenko

The currently known and used plastics and rubber recycling or sorting processes cannot be applied efficiently and economically due to large amounts of fine bulky materials (<3 mm). These wastes are mostly given to specialized landfill sites. Starting out from classical and traditional beneficiation processes a new research project was initiated to work on certain new ways to efficiently separate plastic material mixes. First basic results show that the use of new and improved thermal beneficiation methods is a great implementation in the field of plastics separation. The results can be further increased by a suitable combination with other methods as well. This leads to high-quality and almost pure separated plastics and rubber products, easy to sell on recycling product markets.

Jan 1, 2002

By P. Eger

Minnesota contains a major low- grade copper-nickel sulfide resource within the Duluth Gabbro Complex. Several companies have actively explored this resource. Open pit mining would be required to develop portions of the resource, and as a result, large quantities of sulfide-bearing lean ore and waste rock would be stockpiled. Although the problems associated with high-sulfide tailings and acid mine drainage are well documented, the leaching characteristics of low-grade mineralized stockpiles must be understood for environmental impact assessment, siting, and planning. The Minnesota Department of Natural Resources and AMAX have cooperated in a research program to study leaching and revegetation -of test stock- piles, Six small (1600 &apos;tons) stockpiles were constructed at the MINNAMAX Project Site and they range in composition from 0.29 to 043 g % copper, 0.075 to 0.09% nickel, and 0.6 to 1.45% sulfur. Two of the stockpiles were covered with mineral soil, one was covered with topsoil, and three were not treated Revegetation plots were established on the piles which received a soil cover. Leachate samples and flow measurements were collected at the base of the piles. Initial results indicate that metal concentrations in leachate samples range from 10 to 10,000 times the concentrations found in the streams of the area. During the first growing season, the test pile covered with topsoil yielded 30% less water than untreated test piles. No reduction in yield was observed for the piles that were covered with the less fertile mineral soil. First-year vegetative growth, expressed as biomass, was four times greater on the-topsoil pile than on the mineral soil piles. The long-term effects of vegetation on leachate quantity and quality continue to be investigated.

Jan 1, 1980

"Cast blasting is the primary means of overburden displacement in a surface coal mine. It serves two purposes; fragmenting the rock and throwing it directly to its spoil pile using explosive energy. Increased throw minimizes costs by reducing the amount of material that needs to be re-handled. Prior studies have shown that by only changing blast hole timing with the same blast design, fragmentation and throw alters. It is necessary in cast blasting to optimize both fragmentation and throw, since larger fragments will require more wasted energy to throw the same distance. In an operating mine in Georgia, an optimum inter-hole delay for fragmentation has been found by studying timings from 0ms to 45ms. Instantaneous timing between holes increased the throw by over 100 ft, but fragmentation was poor. Shock and detonation wave collision is a potential reason for this increased throw. This paper investigates this optimized inter-hole timing while altering top and bottom column primer time to potentially improve throw while maintaining optimum fragmentation. Timings studied are top initiation, bottom initiation, and top and bottom simultaneously. INTRODUCTION Explosives are utilized extensively by the mining industry in order to break rock, as either ore or overburden, for hauling, loading, and crushing. An effective production blast strives to achieve optimum rock fragmentation in order to increase the efficiency and reduce the costs of those downstream operations, while simultaneously meeting environmental regulations. The goal of blasting with respect to fragmentation is, according to Hettinger (2015), “to decrease the average particle size of the fragmented rock without overly increasing fines or, in other words, improve fragmentation.” Additionally, the distance the rock is transported by the explosive energy from the blast, also known as throw, can increase efficiency by reducing the amount of material that is re-handled by mine equipment. The primary situation in which this is desirable is the cast blasting of overburden across the narrow pit of a surface coal mine. A key variable in a blast design pattern that can be manipulated to optimize both fragmentation and throw is delay timing between detonations. The invention and increased utilization of electronic detonators has allowed for precise delay timings to be used between rows, holes, and even multiple primers within the same hole. These recent developments in the blasting community have also provided an opportunity to investigate whether or not the mechanism of shock or detonation wave collisions caused by short timing delays are responsible for any increased fragmentation or throw. This experiment attempts to demonstrate if an increase in throw can be achieved while maintaining optimum fragmentation. This study consisted of 3 full scale bench blasts at a granite quarry in Talbotton, GA. Each blast was characterized by the timing delay between the top and bottom primer in the blast column of each hole; one simultaneous blast with a 0 ms delay, a bottom-initiated blast with a 1 ms delay, and a top-initiated blast with a 1 ms delay. Fragmentation analysis of the resultant muckpiles was performed using a combination of the PortaMetrics handheld point-and-shoot rugged tablet from Motion Metrics and the software WipFrag from WipWare. Throw was measured by placing strategic distance markers on the floor of the bench and then taking overhead photographs of the muckpiles after each blast. High-speed video footage was captured of each blast using an MREL Blaster’s Ranger II camera."

Jan 1, 2017

By Steve Skelhorn, Dan Ifrim

"A tunnel project poses many challenges; the operation of the Tunnel Boring Machine (TBM) being one of them. Mechanized tunneling is known as a safe and effective alternative to other methods in terms of schedule and cost; however, efficiency can be severely affected by a bad TBM selection and qualification and employment of inexperienced operators. The success of a mechanized tunneling project involves a comprehensive and interdisciplinary consideration of all contributing factors such as TBM technical specification and selection, TBM design and procurement including ancillary equipment and tunnel linings. The tunnel equipment selection along with the operation can make or break the project. The objective of this paper is to address the importance of the skills and qualifications of the TBM crew with particularity to the TBM Operator. The study includes the Owner and Consultant involvement in the selection and pre-qualification of the TBM crew and specifically the TBM operator as well as the role of Contractor and TBM manufacturer in TBM operator training. This paper also analyzes the possibility of issuing a TBM operator certification, and discusses the benefits and significance of periodic training and certification programs. INTRODUCTION Training in the tunneling industry is not a new topic. The industry continues to evolve and become more complex with technology advances and expansion of mechanical tunnelling to mechanized shaft construction, large diameter drilling and mining industry applications. The need for professionals trained to operate mechanized tunnelling equipment is ever increasing, while there is a significant number of veterans who will be ageing out in the next 5 years. Consequently attracting young professional is a very important aspect of sustaining a qualified pool of professionals. For any given tunnel project, the owner and the engineer spend up to several years, studying the ground conditions during preliminary and final design. Post contract award the contractor spend additional months studying the ground again to develop the optimum means and methods for construction. All this time and money spent at the beginning of the project has the purpose of developing the optimum tunnel design, assessing the risk associated and implementing mitigation measures to reduce risks to acceptable levels. Following the tunnel design process, sophisticated TBMs are being specified and sourced to ensure the best tool for the job. The question raises here: Are there available experienced/trained professionals capable of operating these sophisticated machines?"

Jan 1, 2016

By R. H. W. Chadwick

We in Kennecott are well aware that Alaskans are interested in the progress of our project at Ruby Creek. We would very much like to be able to present you with a final report at this time and tell you about a new mine. I&apos;m afraid, however, that it will be several years at best before such a report can be made. This, then, is an interim report to describe briefly some of our findings to date, and to acquaint you with some of the problems, both geologic and economic, which must 5e resolved favorably before we can talk about a mine. There are several things about this project which make it unusual and interesting to those of us who have been connected with it. Firstly, there is the fundamental importance to Alaska, in the present stage of its economic history, of any undertaking which offers promise of turning a natural resource into a competitive export product. I am sure all of us would get a lot more satisfaction out of having a part in bringing in a new mine in Alaska than we would out of adding another one to the long list in, say, Arizona.

Jan 1, 1960

By A. T. Yu, K. A. Young, Ronald M. Hays, Sanford Terry, D. R. Campbell, J. K. Lovrien, W. L. Price, C. W. Matthews, W. R. van Slyke, S. P. Cole

Storage and transport systems are essential for mineral processing. Section 10 includes systems for storage and transport of dry bulk materials, slurries, and water necessary for operation of mineral pro¬cessing plants. All aspects of these systems are presented, including material characteristics; dry material placement in and reclamation from storage stockpiles and bins; dry material conveyance; hydraulics (liquid flow and pumping); slurry characteristics; slurry storage and reclaim, slurry flow (distributors, launders, and pipes), and pumping; water (primary and secondary process, reclaimed, fire, cooling, and domestic) supply, transport, and storage; equipment selection and sizing; power transmission; controls; and health and safety. The mate¬rials considered include crude ore; process and other water supplies; initial, intermediate; and final in-plant materials; finished materials; and tailings and other waste products. Section 10 is a compilation of practical operating data for engineers, technicians, and plant opera¬tors. For the design of mineral processing plants, including selection and sizing of equipment, the design engineer should consult with equipment manufacturers, suppliers, engineering firms, and plant op¬erators with specialized experience in particular materials handling methods. When unusual conditions are encountered, actual pilot or full scale testing may be required to insure adequate design. Operation of mineral processing plants is dependent on the proper engineering and construction of storage and transport systems for dry bulk materials, slurries, and water. It is obvious that processing plants cannot produce the required quantities of semifinished and finished products unless these material can be transported adequately to, through, within, and from the plant. Costs of storage and transport systems may exceed 50% of the total capital and/or operating costs. Considerable attention must be given to the design, layout, and engineering of these systems. These systems are interrelated with the mineral processing method and it is necessary to determine the best combination of mineral processing method and storage and transport systems. Storage and transport systems perform a major supportive func¬tion to mineral processing. The final selection of these systems depends on the final selection of the processing method and related systems (environmental control, tailings and waste disposal, etc.). The process¬ing method determines the characteristics of materials to be stored and transported; distances, elevations, flow rates for transport; and storage requirements. Flowsheet After selection of the processing method and related systems, a flowsheet must be developed. This flowsheet should indicate produc¬tion rate, percent solids or moisture, and specific gravity for all initial, intermediate, and final products or product flow streams. It also may be necessary to know the size analysis, chemical analysis, abrasiveness, and other physical characteristics of various product flow streams. The flowsheet provides basic information for plant layout, storage requirements, and selection and sizing of process and transport equip¬ment. Storage and transport systems often function improperly be¬ cause of inadequate flowsheet data or process revisions, resulting in improper equipment selection and sizing. Further details on plant design are presented in Section 33. After selection and sizing of process equipment, it is necessary to select the type of material transport equipment to be used for in¬plant materials handling as well as crude ore, tailings, and final prod¬ucts. The storage and/or surge requirements, including capacity and location, then are determined. Storage and/or surge capacity is neces¬sary for leveling production rate fluctuations due to variations in material characteristics; production scheduling; equipment mismatch¬ing, failure, or breakdown; and scheduled maintenance downtime. Variations in ore grindability will cause fluctuations in throughput or production rate for grinding mills and variations in ore grade will cause fluctuations in production rate for concentrating equipment. Variations in material moisture content and percent solids can have serious effects on the capacity of material transport equipment. In some cases, a blending system may be desirable or necessary to reduce variations and to obtain uniform production and/or metallurgy. Storage capacity often is needed because of different production schedules for various phases of the mining and mineral processing complex. As an example, the mine and coarse crushing plant may operate on a one- or two-shift-per-day schedule while the fine crushing plant and concentrator on a three-shift-per-day schedule. This would require storage between the coarse and fine crushing plants. Another example would be load-out storage where unit trains are used to haul concentrate or final products. The concentrator could be operated on a three-shift-per-day schedule while only I to 2 hr may be scheduled for unit train loading. This would require adequate load-out storage so that the concentrator can be operated continuously. Process equipment with mismatched capacities requires storage or surge capacity between the mismatched equipment to achieve oper¬ating efficiency. As an example, the fine crushers may have greater capacity than the rod mills. Storage between the fine crushers and the rod mills permits both the crushers and rod mills to be operated at optimum capacity with the crushers actually operating or running a lesser number of hours per day. Mismatched capacities for process and transport equipment also may require storage or surge capacity. Mismatching of equipment capacities most often occurs because of the difficulty in equipment sizing. Thus, the design engineer must anticipate where in the flowsheet these mismatching capacities are likely to occur while making every effort to assure that equipment is selected and sized properly. Equipment breakdown can cause major operating difficulties and lost production. These breakdowns can be reduced with adequate scheduled maintenance. Lost production due to nonscheduled down¬time caused by equipment breakdown can be reduced further by standby equipment and storage and/or surge capacity ahead of essen¬tial mechanical and electrical equipment. As an example, standby pumps and conveyors often are available as part of the in-plant trans¬port system. Storage and/or surge bins and tanks often serve dual functions, such as dewatering, mixing, and smoothing production rate fluctuations.

Jan 1, 1985

By R. G. Graber

Field testing of GPS mining applications has confirmed the technical and operational viability of GPS for precise, centimeter-level positioning in harsh taconite environments. GPS hardware has provided consistent availability exceeding 90%, with precision in certain applications of ± 0.07 foot at 95% confidence levels. Despite these technical successes though, challenges persist in achieving effective GPS integration. These challenges include the acceptance of new job tasks by mine personnel, the capacity of typical mine data communications infrastructure and the need to design GPS interfaces for new mining equipment.

Jan 1, 1998

By F. Carew

Accurate knowledge of what mass and grade is to hand and where it is stored is key to mine efficiencies and overall profitability. In order to make the right decisions and align production with stockpile capacity, feed and contract demand, a clear and accurate view from production through blending and processing is required. The use of a mine production management solution can provide you with a high degree of confidence in and visibility into validated data as well as auditable and traceable material movements, activities and surveys. A robust calculation engine enables mass and grade changes to propagate to material movements and stockpiles to ensure you are getting the most accurate view at all times. Tracked changes in material balances can be readily incorporated in revised production schedules to close the loop. The availability of accurate, timely information, coupled with predictive trend indicators, is a significant advance in narrowing the gap between claimed and planned production that is common to many mines, regardless of commodity. This paper provides an overview of a Mine Production Management System (MPMS) and explains how the system helps address the challenges listed above.

Jan 1, 2011

By S. Coats, G. Norton, A. Benham, P. Ková

The Aynak copper deposit, located 30 km south of Kabul in Afghanistan (Figure 1), was discovered by Soviet geologists in the 1970s. Extensive exploration undertaken in the area between 1974-80 included several hundred boreholes, seventy trenches and nine exploratory adits. This work identified a “drill-indicated resource” of 240 Mt at 2.3% Cu (ESCAP, 1995).

Jan 1, 2007

By G. Watson, S. Sawyer

A Method to Calculate Hydrodynamic Loads on Underground Bulkheads Bulkheads are structures built in openings in underground mines to impound water, preventing the water from entering the active mine workings. These structures not only have to be designed to withstand the static, hydraulic pressure, but also the dynamic or seismic pressure, which would be generated by an earthquake. Bulkheads can be considered underground dams. Unlike dams on the surface, bulkheads are often subjected to hydraulic heads that exceed the heights of the bulkheads. Theodor von Karman in 1933, and Westergaard earlier, developed the equation by which the hydrodynamic pressures on surface dams could be calculated. Civil engineering handbooks of today contain this equation. In this paper, using the methodology developed by von Karman and Westergaard, the authors have developed an equation by which the hydrodynamic forces on bulkheads could be calculated when the hydraulic head exceeds the height of the bulkhead.

Jan 1, 2007

By Dale D. Teeters

Today, I would like to talk about ways to maximize the efficiency of surface coal operations. I doubt I will present any startling new ideas, but my comments may, hopefully, stimulate some conversation today and later back at your own operations. Strip mining is a very old technique used by ancient societies. Only with the coming of the machine age in the early twentieth century did we attempt to increase the magnitude of our operations. The industry, as we know it today, really only got started in the early 1900s with the advent of steam shovels. In the first portion of this presentation, I will attempt to show that we have, in many cases, not changed the basics of strip mining, only the scale. In doing so, quite often we have complicated the operations to the point of being unmanageable and unprofitable.

Jan 1, 1981

By G. A. Grandy, P. F. Thomas, C. D. Danecki

When considering the mill drive system for a grinding application, a large number of questions must be answered. Depending on the mill size and type, the mill can be driven by several configurations of drive systems: a single low-speed motor connected to a pinion driving a ring gear, two low-speed motors connected to two pinions and driving a ring gear, or a gearless motor mounted directly. In addition, a gear drive system can have a reducer placed between a high-speed motor(s) and pinion(s) or a power path splitting pinion stand. In some designs the reducer is integral with the pinion stand driven by a high-speed motor. The technical and commercial implications of several mill drive options are presented. Initial cost, cost of installation, cost of commissioning, and cost of operation and maintenance are presented for each drive option considered. The impact of each drive system on the design, cost and operation of the overall plant electrical system is discussed. Also, consideration is given to mill drive availability, and the potential cost resulting from delays in plant production.

Jan 1, 2001

By G. Petrakis

The selection of suitable species of plants for the rehabilitation of mining disturbed lands is one of the most crucial decisions to be made concerning the success of planting revegetation. Native plant species are best suited for use in the work of reintroducing vegetation in rehabilitated areas. By using such species an increase in the success rate of rehabilitation is attained not only as regards yield due to their better growth ability (they are adapted to local climatic conditions), but also because of a better adjustment to and better visual harmonization with the surrounding unspoiled areas.

Jan 1, 2002

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

"Duluth & Iron Range Railroad. The Duluth & Iron Range Railroad was built from Two Harbors to the Vermilion range at Tower, a distance of 67.6 miles, in 1884, and extended to Ely, twenty-one miles east of Tower, in 1888. It was built into Duluth in 1886, and branches were extended from its main line to the Mesabi mines in 1892 and 1893. The original grades on this road are very steep, going north, and in the thirteen miles from Two Harbors to Highland there is a rise of 1,150 feet. A new line between these points has been built with an increase of three miles in distance and with maximum grades of 1 per cent. Duluth, Missabe & Northern Railway. The Duluth, Mis¬sabe & Northern Railway was constructed from Stony Brook to Mountain Iron, a distance of 48.62 miles, in 1892. The Biwabik branch from Iron Junction to Biwabik, a distance of 15.54 miles, was constructed in 1892. The Superior branch from Wolf to Hibbing, a distance of 16.06 miles, was co11structed in 1893. The Alborn branch from Coleraine Junction to Coleraine, a distance of 53 miles, was constructed in 1906. The total main line mileage is 242 miles, of which 82 miles from Duluth to Hibbing is double tracked"

Jan 1, 1920

By H. Nagel, A. P. Schissler

"INTRODUCTION Anadarko Petroleum Corporation (Anadarko) owns a region of oil shale properties acquired as part of the original Union Pacific Land Grant of the 1800’s in southern Wyoming. These holdings are greater than 2 million acres and occur throughout the Green River Formation in southwestern Wyoming. One area was prioritized for further study by Anadarko Minerals called the Kinney Rim in the Washakie Basin due to low environmental impact, proximity to infrastructure, high ore grade, and low mining cost. The area is a low-overburden oil shale resource that can be developed using surface mining methods, processed by conventional surface retort, and placing waste rock disposal back on the bench for a design capacity of 10,000 barrel per day. The purpose of this papers is to present the results of environmental analysis and timeline, the mine plan, and surface ore processing to offer a resource-ready energy source.Mineral rights for the Kinney Rim area are owned by Anadarko, the United States Bureau of Land Management (BLM) and the State of Wyoming. Mining of oil shale for this study targets Anadarko owned mineral resources.GEOLOGY The study area is in the Green River and Washakie Basins in western Wyoming. The host geologic member is the Laney Oil Shale. Figure 2 illustrates the Laney shale within a generalized lithologic cross section.OIL SHALE LEASING The proposed Kinney Rim oil shale mining project is located in an area dominated by a 1 square mile checkerboard landownership pattern with every other section typically administered by Bureau of Land Management (BLM) and Anadarko. Surface and mineral ownership is a split estate legal entity. The immediate Kinney Rim mine plan is all on Anadarko sections."

Jan 1, 2015

By H. Ipek

Industrial grinding machines used in the mineral processing industries are mostly of the tumbling mill type. These mills exist in various types: ball, rod, pebble, autogenous, and semi-autogenous. Balls and rods are traditionally media shapes used in the tumbling mills. In resent years, as an alternative to balls, grinding charges with various shapes are being used. Cylpebs are slightly tapered cylindrical grinding charges with length equaling diameter, and all the edges being radiused. Cylpebs of equal diameter and length have 50% greater surface area and 45% greater weight than balls of the same material. In addition, they have 9% higher bulk density than steel balls, or 12% higher bulk density than cast balls. An important advantage of cylpebs over balls is that cylpebs produce narrower granulometric distribution due to their shapes. However, some discrepancies were found in the literature regarding the milling performance of cylpebs in comparison with balls (Chi, 2004). In recent studies, Chi (2004) has provided detailed information on cylpebs and has compared these to balls in relation to media mass, size distribution, surface area, and input specific energy. Ipek (2006) has investigated the effects of cylpebs and balls with equal mass and surface area on the breakage rate of quartz, using cylpebs and balls separately. Similarly, Lameck and Moys (2006) have investigated the effects of balls and worn balls on breakage rate of material using worn balls as grinding environment. However, no study has attempted to investigate the effects of grinding environment other than balls on the brekage distribution. As indicated by Prasher (1987), the breakage distribution function is independent of the following variables in ball mills: hold-up (Mika et al., 1967; Kelsall et al. 1969), mill speed and ball load (Herbst and Fuerstenau, 1972), media load and ball density (Kelsall et al., 1973), mill diameter (Malghan and Fuerstenau, 1976), and powder charge (Shoji et al. 1980). The aim of the present paper is to compare the effects of cylpebs and balls on the breakage distribution function of quartz with respect to same mass and same surface area. BACKGROUND Comminution as a rate process is called kinetic approach. Studies on the kinetic approach are reviewed by Oner (2001). Oner states that grinding kinetics are based on studies by Kolmogorov in 1941 and that Robert (1950) is the first to suggest this approach. Later, Melzak, Loeveday, and Reid have improved the grinding kinetics equation; and, Austin and Lynch have conducted two basic studies on the analytical solutions of these equations. Considering the results of studies comparing the size reduction mechanisms, it has been accepted that breakage constitutes of two operations. These two basic operations, first defined by Epstein (1948), are those of selection of material for breakage and the distribution of breakage material to particle sizes smaller than the initial size (Lynch, 1977). Epstein defined the two operations as: ? Pn(y), the probability of breakage of a particle size in the nth step of the breakage process. ? F(x,y), the cumulative distributions by weight of particles of size x<y arising from the breakage of a unit mass of a size y. Probability of breakage is called a selection or a breakage-rate function (Si). Characteristics size distribution after breakage is called a breakage distribution or appearance function (Bi,j). Due to the difficulties in representing particle size distributions mathematically and constantly, the batch equation based on particle size fraction is suggested. Thus, as is the case in breakage distribution and specific rate of breakage, the breakage parameters were defined by batch grinding experiments conducted in laboratories (Oner, 2001). When effective breakage occurs in the mill, the breakage of material with single feed size fraction usually fits first order grinding kinetics and the specific rate of breakage values can be calculated through the slope of semi-log plot. The values of the breakage distributions are deduced from the size distributions at short grinding times where there is mainly size 1 material breaking and only small amount of smaller sizes to rebreak (Austin et. al., 1984). B values can be calculated by using BII. [ ] where j is the top size of the charge, Pi(t) is the cumulative percent undersize of i th size interval at the short grinding time which gives no more than about 30% broken out of the top size interval. Cumulative primary breakage distribution, Bi,j, is also defined in an empirical form by [ ] where xi is the top size and Bi,j is the weight fraction of primary breakage products. The parameters F, ? and ß define the size distribution of the material being ground. On plotting size versus Bi,j on log scale, the slope of the lower portion of the curve gives the value of ?, the slope of the upper portion of the curve gives the value of ß, and F is the intercept as in Fig.1. [ ]

Jan 1, 2009

By Georgios Kalamaras, Chiaia Dinu, Platania Paolo, Alessio Carlo, Giampiero Cirvegna, Claudio Santucci

The Project alignment initiates north of Pinerolo, along the State Road 23[S.S. 23] that is one of the principal arteries to the northwestern Alps where a number of Olympic events for the 2006 Winter Games will be held. The 3.5 km ring road bypasses the Porte habitat by traversing twice the Chisone River. It consists of the following principal structures [Figure 1]: San Martino bridge [130 m in four bays] Prarostino viaduct [130 m in four bays] Craviale tunnel [1055 m] Turinella bridge [a 50 m long bridge that connects the two tunnels] Turina tunnel [665 m] Malanaggio viaduct [350 m in 9 bays]. The road section is 13 m wide and is made up of two 3.75 m lanes, a hard shoulder [1.50 m wide] and a 1.25 m wide curb for each lane. The Project maximum velocity is 100 km/h.

Jan 1, 2005