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By M Wortley, R Morrison, T Rivett

The tracking of ore through process hold-ups such as stockpiles has been traditionally been difficult to achieve. The inability to pinpoint the exact source in the mine of material that is feeding a processing plant has led to inefficient mine-mill reconciliation processes. In addition, a lack of understanding of the behaviour of ore in process hold-ups such as bins and stockpiles often leads to poor predictions of plant performance and to poor reconciliation of this to the orebody.This paper reports on two short case studies. One case study addresses tracking ore from various parts of two mines to the concentrator. The other follows synthetic particles through the coarse ore stockpile. Both studies use radio-frequency identification (RFID) tracer technology. The paper concludes by discussing general strategies for implementation of such concepts into mine-mill metal accounting and reconciliation systems. As shown in this paper, reliable ore tracking systems will allow much more effective mine-mill reconciliations as well as the ability to model process hold-ups with regard to size by residence time distributions. This should, in turn, allow metallurgists to have a better understanding of the size and grade of material that will report to the plant at different process hold-up (eg stockpile) conditions.

Jan 1, 2009

By C. Crussard, R. Tamhankar

It is the policy of The Metallurgical Society to provide, in the TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, a prompt and accurate medium for publication of reports of significant new research in both the scientific and engineering aspects of metallurgy. Papers submitted to the Society are judged by competent reviewers accord-ing to established criteria for technical merit, accuracy, originality, and presentation. STAFF: Editor, Gerhurd Derge Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Staff Coordinator, James J. Burke THE METALLURGICAL SOCIETY: W. R. Hibbard, Jr., President; J. C. Kinnear, Jr., Past-President; John Chiprnan, Vice President; T. D. Jones, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: A. W. Thornton, Chairman; Dennis Carney, John Chip-man, J. C. Fulton, J. H. Hollomon, H. H. Kellogg, A. E. Lee, R. Maddin, J. D. Sullivan, and D. Swan. Review and selection of manuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division: T. B. King, Chairman; S. J. Dickenson, R. P. Hermsdorf, R. Schuhmann, Jr., and P. T. Stroup. Institute of Metals Division: Robert Maddin, Chairman, F. Lincoln Vogel, Jr., Vice-chairman, W. A. Backofen, R. W. Balluffi, J. H. Bechtold, M. B. Bever, R. S. Busk, C. G. Goetzel, Paul Gordon, C. D. Graham, .Jr., Robert F. Hehemonn, R. I. Jaffee, F. E. Jaumot, Jr., Irving R. Kramer, A. J. Lena, Harold Margolin, C. J. McHorgue, Russell A. Meussner, J. B. Newkirk, H. W. Paxton, G. E. Pellissier, I. S. Servi, Alan U. Seybolt, A. J. Shaler, and Jack Washburn. Iron and Steel Division: J. C. Fulton, Chairman; T. B. King, F. C. Langenberg, W. 0. Philbrook, and T. 0. Winkler. Published bimonthly by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., 29 West 39th Street, New York 18, N. Y. Telephone: PEnnsylvania 6-9220. Subscription $20 per year for non-AIME members in United States and North, South, and Central America; $25, foreign; $5 for AIME members. Single copies, $4.00, single copies foreign, $5.00. The AIME is not responsible for any statement made or opinion expressed in its publications . . . Copyright 1958 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address, AIME New York ... Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts... Second class postage paid at New Yark, N. Y., and Ann Arbor, Mich. Volume 212, Number 6.

Jan 1, 1959

By Fidelis T. Suorineni

Rockbursts are a major hazard in deep hard rock underground mining and tunneling. To date a significant number of rockbursts still defy conventional explanations. A review of rockburst case histories in the literature has shown that pillars and tabular excavations under shear loading are prone to rockbursting in situations where they are least expected under conventional knowledge of rockburst causes. Despite the evidence of the effects of shear loading on underground infrastructure, and the frequency of their occurrence, little is known about how this loading mechanism causes such large magnitude events and extensive damage. In this paper analytical and numerical modeling are used to understand the behaviour of pillars and tabular excavations under shear loading. The numerical modelling results show that pillars under shear loading are less confined than their equivalents in loaded in pure compression in the same geologic environment, and are therefore more brittle and weak. For tabular excavations under shear loading, the behaviour depends on whether such excavations are continuous, co-planar or offset with rock bridges. Analytical results based on slit theory show releasable potential energy in tabular excavations increases nonlinearly with excavation half-span. The study results are important for the safe and economic extraction of orebodies under shear loading.

May 1, 2011

By John Hoffert, Darren Colwell, Greg Tucker, Jeremy Kinch, Greg Rasmussen

"The Kemess Mine, a major producer of gold and copper, is located in north-central British Columbia. Kemess was brought into production in May 1998 by Royal Oak Mines. On February 11, 2000 Northgate Exploration Limited acquired Kemess Mine from receivership. Since acquisition in 2000 Kemess has seen many accomplishments, including the reduction of costs by 40%.One of the largest site capital costs was the construction of the tailings storage facility dam, which when finished will be one of the largest earth filled dam structures of its type. The existing construction design by AMEC called for a kilometer wide rock dam to be built from the 1350 M elevation to the 1504 M elevation at a 5.5:1 slope by hauling over 30 million tonnes of non-acid generating waste rock 7-kilometers from the open pit to the tailings dam, which was highly expensive.Kemess realized an opportunity for cost reduction was possible if the dam could be built from suitable quality tailings sand; however the sand did not meet the neutralizing potential ratio specifications. It was determined that cycloning combined with flotation to reduce pyrite concentration in the sand would produce a non-acid generating product for dam construction. The sand plant design challenges were to remove the sulphides from the tailings to obtain an NPR greater than 2:1 and provide a consistent sand product for the construction with a fines content of less than 15% passing 200 mesh. After a 2-year testing design and construction period, the sand plant was successfully started at the end 2002 resulting in higher than expected sand quality and production rates.This paper describes the plant design phase, commissioning, and operation of the tailings sand plant for construction of the tailing storage facility dam to enable us to meet all the engineering and regulatory requirements. The many challenges faced were successfully met using several innovative designs. The operational, economic, and environmental benefits are detailed."

Jan 1, 2004

By Polysius AG

"The Lone Tree demonstration was an important milestone in bringing High Pressure Grinding Roll (HPGR) technology into hard rock applications in the mining industry. HPGRs have become standard equipment in the cement, iron ore, and diamond industries over the past fifteen years, but their use in severe duties found in the hard rock mining sector has been restricted due to high roll wear and subsequent low availability. HPGR availability has historically been limited because of frequent downtime for edge weld rebuilding as the rolls wore and short tyre life from high roll surface wear rates.Recent advancements in HPGR wear protection are now being evaluated for commercial applications in the gold and copper mining industry where this technology may offer benefits in comminuting hard and/or abrasive ores and in improving metal recovery in heap leaching applications.Proving the feasibility of HPGRs for processing competent, abrasive gold ore, Newmont Mining Corporation, the world's largest gold producer, operated an HPGR demonstration plant employing a POLYSIUS (POLYCOM) HPGR incorporating some unique wear protection, at their Lone Tree gold mine near Winnemucca, Nevada. Results of the successful demonstration are presented and evaluated in this paper.The Lone Tree HPGR demonstration plant operated for three months, from April through June 2003. The HPGR operated for 1626 hours and processed 141,000 tons of ore. This technology demonstration focused on measuring operating performance, wear characteristics, and availability of today's HPGR technology.Polysius' innovative roll surface wear protection system eliminated edge-welding downtime. Improved surface wear protection extended tyre life to predicted durations acceptable for very abrasive service. The POLYCOM HPGR is now deemed suitable for selected hard rock applications."

Jan 1, 2005

By Remo Grandori

The Umiray Angat 13,2 km long tunnel in Philippines have been bored through extremely variable and difficult ground conditions including a number of special events. In particular the following adverse conditions were found: faults in decomposed ground, high temperature rocks, extremely rapid and important convergence phenomena, water inflows up to 800 litres per second. The special El Nino climatic conditions caused a long dry season and lower the level of the lake that was granting the access by barge to the site under the minimum navigable level. Many equipment have had therefore to be transported to site by a 10 ton capacity helicopter, after having been partially dismounted. For the same reason most of the tunnel drive have been bored servicing the site by 1 ton capacity helicopters to transport materials, spares and personnel. In order to overcome the above geological and logistic problems several innovation were introduced and tested in this project. Despite all that difficulties the 13,2 km of tunnel were bored in about 24 months, with a global average of 500 m/month.

Jan 1, 2001

By K. K. Landes

The north central and northeastern states supply over 50 pct of the chemical and metallurgical limestone produced annually in the United States, and Ontario is the leading source of this material in Canada. About three fourths of the chemical and metallurgical stone produced in this area comes from Michigan, Pennsylvania, Ohio, and Ontario. The specifications, physical and especially chemical, for chemical and metallurgical stone depend upon the end use, but in general the tolerance for impurities is so low as to rule out most limestones and dolomites. Both high calcium limestone and dolomite are used in the metallurgical and chemical industries. The principal metallurgical use is as a flux in iron ore blast furnaces and open hearth steel furnaces. The major chemical uses are in lime burning and soda-ash manufacture. Other important uses include glass manufacture, in making calcium carbide, and in sugar factories. All deposits of high quality carbonate rock are definitely finite. Invariably and inevitably they diminish in either thickness or quality laterally so as to become unworkable as chemical and metallurgical stone. The size of these high quality lenses ranges from a few thousands of tons to hundreds of millions of tons. The best hunting for new supplies is in the geologic formations known to contain premium quality deposits. However, because of high transportation costs, carbonate rocks, to be workable, must be close to market, dollarwise. Definitions: Chemical stone is limestone or dolomite used as a raw material by the chemical industry. The major chemical uses are in lime burning and soda-ash manufacture. Other important uses include glass manufacture, making calcium carbide, and in sugar factories. The specifications for chemical stone depend entirely upon the end product. Some uses require dolomite, some require high calcium limestone; in a few instances, notably in lime burning, either type of carbonate rock can be used as raw material. As a general rule, a fairly pure stone is necessary and for certain particular uses the tolerance for some elements such as sulfur, iron, and phosphorus may be extremely small. Metallurgical stone is used as a flux in furnace operations, especially in the blast furnace where iron ore is converted into pig iron and in the open hearth furnace where pig iron is made into steel. Either limestone or dolomite can be used in the blast furnace, but only high calcium stone is charged in the open hearth (except for rice-size dolomite used as a refractory). There are no rigid chemical specifications for blast furnace stone, but low silica, alumina, sulfur, and phosphorus are desirable. For open hearth use, in addition to low magnesia, a very low sulfur content is also specified by many furnace operators. For furnace use, fluxstone also must be sufficiently shatter resistant that it will remain in lump form during transport and charging into the furnace. Commercial stone is the term applied in the trade for crushed stone used for roadstone and in concrete aggregate. Many of our best chemical and metallurgical limestones are too soft to qualify in the Los Angeles abrasion test for use as commercial stone. However, some limestones, and a higher proportion of dolomites, do qualify for commercial stone and so can be sold to either market. Place Value: Even the highest grade limestone is still a bulk commodity with a relatively low value per ton. As a matter of fact there is very little difference in the average price per ton between high grade chemical and metallurgical stone and crushed limestone used commercially. Most high quality stone is produced in large operations with consequent low cost per ton whereas most commercial stone is produced in relatively small local quarries. As in the case of other bulk commodities most limestone buyers pay more for transporting the raw material than the cost of the stone at its source. For this reason steel furnaces and chemical plants

Jan 1, 1961

By James R. Lang

The Xietongmen deposit is located 350 km west of Lhasa, Tibet. It is a new, high-grade porphyry copper-gold discovery and the first deposit to be systematically explored by a western company in southern Tibet. In 2005, Continental Minerals Corporation drilled 21,332 m of core in 63 holes and demonstrated excellent lateral and vertical continuity of high-grade copper-gold mineralization over an area 750 m by up to 350 m in size which remains open in all lateral directions. Drill intersections repeatedly yield grades >1% Cu equivalent (based on gold and copper prices) and include 308.5 m at 0.87% Cu and 1.25 g/T Au (1.60 CuEQ%), and 315.6 metres at 0.61% Cu and 1.11 g/T Au (1.26 CuEQ%). Extensive drilling in 2006 will expand and delineate the deposit, and metallurgical, engineering, environmental and socio-economic evaluations will begin. Xietongmen is hosted by volcanic and intrusive rocks of the Gangdese belt, a magmatic arc active between 120 and 30 Ma along the southern margin of Eurasia. Pervasive alteration is dominated by a well-mineralized K-feldspar and biotite assemblage, and by a more peripheral sericitic assemblage also with strong chalcopyrite. Major vein stages include chalcopyrite-bearing quartz, biotite, magnetite and pyrite-pyrrhotite types.

May 1, 2006

By K. Coleman, C. Visser, N. Selby, X. W. Pan, T. Letwaba

A prototype weightometer soft sensor is under development at DebTech, De Beers in partnership with Venetia Mine. Its main function consists of an online data source; data validation; dynamic weightometer models; online detection of weightometer failure; alarming and replacing a weightometer when it fails. 31 dynamic models have been developed. All models with R2>= 85%are accepted as good models and they generally have satisfactory results with a daily error of less than 8% within 90% confidence level. By using those models, a set of soft sensors can be set up to cover all weightometers in the entire processes starting from primary crushing to the stock piles of dense medium separation (DMS). Some practical issues and concerns on model development are discussed, including data collection, data analysis, data pre-processing, variable selection, time delay, model training and model validation. When deploying the weightometer soft sensor system, the potential benefits could include: reduction in plant downtime; reduction in unplanned maintenance and even replacement of non-critical weightometers, particularly where nuclear weightometers are used. Keywords: soft sensor, weightometer, dynamic modelling, neural network modelling

Jan 1, 2003

By Mathew Avery, Colby Barrett

In November 2016, a 7.8-magnitude earthquake caused more than 100,000 cubic meters of rock and debris to tumble down and bury the transportation infrastructure below Ohau Point in New Zealand. All routes between the northern and southern portions of South Island were severed. To undertake the rebuilding efforts, the New Zealand government established North Canterbury Transport Infrastructure Recovery (NCTIR) – an alliance to repair the road and rail networks between Picton and Christchurch. NCTIR’s aim was to have the road open by Christmas 2017, but work also continued into 2018 to complete a number of safety improvements along the highway. The presentation will review the initial remediation attempts, the necessity to re-evaluate the original efforts, the need to incorporate techniques that were “outside-the-box” and different from traditional methods, and the logistics and planning that were required to complete the work safely. INTRODUCTION Shortly after midnight on Monday 14th November, a magnitude 7.8 earthquake struck the small South Island settlement of Waiau in North Canterbury, 100km north of Christchurch. The quake was the largest in New Zealand since the magnitude 7.8 Dusky Sound earthquake in 2009 (GNS 2016). While shaking was widespread with over 15,000 recorded ‘felt reports,’ the worst shaking occurred about 50 seconds after the quake rupturing started. The energy of the tremor progressed north over several minutes with surface rupture recorded on a total of 21 faults. The length of all the fault ruptures combined was close to 100km (GNS 2016). The degree of ground shaking was high, recorded as Modified Mercalli Intensity Scale (MMI) Level 8 – Severe. This level of shaking causes considerable damage in ordinary buildings with partial collapse including fall of chimneys, factory stacks, columns, monuments, walls, etc. At a human level, people experience difficulty standing; while furniture and appliances shift. Geologically, the damage depends on the geological setting. In Kaikoura and the surrounding area, especially the coastal highway State Highway 1, north and south of the town, many of the slopes consist of over steepened weathered, fractured greywacke. During the quake, the shaking caused significant and widespread damage with a total of 26 major slips (and many smaller slips); closing both State Highway 1 and the Main North Rail Line between Picton and Christchurch.

Jan 1, 2018

By Naresh Koirala

The Greater Vancouver Regional District completed installation of a 2.5 Km long, 2400 mm diameter concrete sewer in Delta, British Columbia in 2000. The sewer traverses through area of peat and soft ground. The ground investigation along the sewer alignment consisted of cone penetration tests and auger drilling with standard penetration tests. The gravity sewer is supported on precast, pretensioned spun concrete piles imported from Malaysia which had never been used for a major project in North America. The capacities of the installed piles were tested using pile driving analyzer (PDA) and three static load tests. A total of 46 PDA tests were carried out during pile installation. The paper describes the pile vetting process the owner went through prior to accepting the piles for use in the project and performance of the piles. It compares the pile capacity estimated from the PDA tests with that estimated from soil mechanics methods using data from cone penetration tests and standard penetration tests. The ranges of estimated capacities calculated by different methods are discussed from design capacity selection considerations.

Jan 1, 2004

By Michelle Lostra, Red Blanchette, Jan Babendererde, Greg Colzani

The City of Portland’s Westside CSO Project is constructing a deep tunnel system to reduce combined sewer overflows (CSO) from entering the Willamette River. Several kilometers of microtunneled pipelines connect the existing system to the new tunnel. The alignments encountered a variety of ground conditions, including fill, manmade obstructions (wood, steel piles, debris), fine-grained to dense coarse-grained materials, cobbles and boulders, all below groundwater. A slurry MTBM convertible to varying diameters, equipped with mix shield capabilities, was selected to cope with the conditions. This paper will discuss access shaft construction,

Jan 1, 2005

By J. P. Gous, J. J. Sutherland

"Transalloys is a silicomanganese (SiMn) producer located in South Africa, and uses only local manganese ores to produce SiMn alloy. The plant operates five open submerged arc furnaces (SAFs) with an annual capacity of 180 000 t of saleable SiMn.Maintaining tap-holes is critical for effective furnace operation, allowing proper drainage of the furnace with minimal operator interference. Using a claygun and drill arrangement installed at each furnace, tapping occurs every four hours. Tap-holes are maintained through mickey replacement and brick repairs. Three furnaces have SiC tap-holes and two have graphite tap-holes.This paper gives a review of SAF operation, furnace and tap-hole design, daily tapping operation, and maintenance practices for repairing tap-holes.IntroductionDefining tap-hole life cycle, Steenkamp et al., (2016) highlighted four main steps: installation during furnace relines, day-to-day operations, tap-hole maintenance, and tap-hole repair. The authors argued that the design of the tap-hole area should allow for all four stages in the tap-hole life-cycle. Design principles for each stage were presented using silicomanganese (SiMn) production as a case study. Here we present a further analysis of the case study by providing practical examples of how the tap-hole life-cycle is managed at Transalloys during the design, operation, and maintenance of submerged arc furnaces (SAFs) applied in the production of SiMn.BackgroundTransalloys is the largest producer of SiMn in Africa. Its smelter complex is based outside the town of eMalahleni, in the Mpumalanga Province of South Africa. Transalloys was commissioned in the mid- 1960s as a high- and low-carbon ferrochromium plant based on the Perrin process. In 1967 the plant was converted to SiMn production because of constraints in the ferrochrome market (Basson, Curr, and Gericke, 2007; Bezemer, 1995). Today, the installed production capacity is 180 000 t of SiMn annually. Plant operations consists of five SAFs (see ratings in Table I), operating 24 hours a day, 365 days a year (including maintenance), involving 280 permanent employees, with up to 120 contract employees on site at any given time."

Jun 1, 2019

By John R. Eckel

A Iaboratory drilling rig has been devised and placed in operation which permits the application of hydrostatic, terrastatic, and formation pore pressures to a rock sample for drilling under controlled conditions. Calibrated rests of this equipment in-dicate qualitative agreerment with field results on the effect of weight on bit, rotary speed, and rate of circ~~lation on drilling rate. Tests under pressure, using water and air as the drilling fluids, indicate that when drilling saturated limestone samples, a pressure differential between hydrostatic and formation pressure is the only pressure which affects drilling rate. A differential in either direction causes a reduction in rate, but the same diflerential from the wellbore into the formation causes the greater reduction. Also, in lime.stone, air favorably affected drilling rote only when compared to water at high hydrostatic pressurre, all other conditions remaining constant. Large increases in drilling rate with air could be obtained in the laboratory only while drilling a shale, which offered a limited permeability to nitrogen and which could be drilled with a differential from the formation into the wellbore. In general, the magnitude of the changes due to the pressure effect were small compared to changes in drilling rate obtainable by changing either bit weight or rotary speed. INTRODUCTION In the course of Humble's drilling research program, the desirability of investigating several factors which lend themselves to laboratory rather than field study became obvious. Principal reasons for this are the expense involved in field studies and the difficulty of exercising the required degree of control. Of primary importance are investigations of the effect of fluid pressure on rock rate, the effect of pressure on rock drillability, and a study of the fundamental mechanics of rock failure and chip generation. Several years ago some work in the laboratory on the effect of mud properties on drilling rate was re- ported to the API', but the completion of this work and the investigation of the other variables affecting drilling rate required equipment somewhat more elaborate than that used on these earlier tests. This equipment has been assembled to form Humble's Drilling Engineering laboratory. To date only the effect of pressure on rock drillability while using water and air has been investigated, and this work is not yet complete. Facilities are available to investigate the effect of fluid properties on rate of penetration, and information is being assembled on a current basis on the mechanics of drilling. The sequence of presentation in this progress report is somewhat different from that in which the data were obtained since the order of ex-

By J Wei, A Yo, R Levy

Waste water reuse from municipal and industrial effluents is becoming increasingly important in many areas around the world. Water scarcity, local regulation and environmental impact are driving many industries like coal and copper mines to reuse the large volume of waste water they produce. For example, the Chinese coal industry generated about 4.2 billion tons of mine waste water in 2005 of which only approximately 30 per cent was reused. Coal energy represents 76.6 per cent of the total energy generated in China in 2007 and most of the coal-fired power plants are located in north-west of China, which is a water stressed area.The selection of mine waste water treatment process is challenging as the effluents typically contains high levels of organic compounds and salinity and their composition can vary significantly. In recent years there has been a growing interest in the integration of ultrafiltration (UF) and reverse osmosis (RO) membrane technologies for mine waste water treatment and reuse.In this paper, an overview of the design and performance of ultrafiltration and RO membranes applied for reuse of mine waste water are discussed. A study was carried out in two effluents treatment plants treating copper and coal mine waste water, which are located in Chile and China respectively. The following topics will be discussed to demonstrate the performance of an integrated membrane system in mine waste water reuse: The main challenges from copper mine waste water treatment: high level of chemical oxygen demand (COD); high level of total suspended solids (TSS); high salinity; high concentration of silica, sulfate, iron and other contaminants; and fluctuation of raw water quality. The main challenges from coal mine waste water treatment: high level of total dissolved solids, and waste water quality fluctuation. Design parameters for waste water treatment systems: Selection of pretreatment for dual-membrane system in the copper mine: Clarifier with coagulation and flocculation to remove high TSS; Dissolved Air Flotation (DAF) to remove non-settling solids; Media filtration to handle fine solids and particulate organics; Activated Carbon filters (ACF) to remove dissolved organics, colour and odours. Selection of UF and RO membranes and specific design of their recovery, flux, chemical dosage and cleaning regimes. Finally, the performance of UF and RO, including the main fouling factors and efficient cleaning procedures, will be presented and compared to the design parameters to demonstrate the efficiency and performance of the selected integrated membrane systems in each case.

Jan 1, 2009

By Michael V. Mergentime, Prakash M. Donde

The Nutley Quarry Trunk Sewer Project is a good example of a tunnel that went through difficult and complex ground. The 2 m (7ft.) diameter and 840 m (2,750 ft.)long tunnel passed through soft ground, mixed face, and hard sandstone. The soft ground and mixed face tunneling provided several challenges. During excavation of the tunnel, the Contractor encountered a number of unanticipated large boulders. In addition, the length of the mixed face portion of the tunnel increased by 100%. The Contractor tried various construction techniques to overcome the difficult ground conditions and complete the project. The tunneling progress was slower than expected. The Contractor claimed extra costs for differing site conditions. Through discussions and negotiations between the Contractor, Engineer, and Owner, all of the changed condition claims were settled before the construction of the project was completed. This paper addresses the difficult ground conditions, claims evaluation, and how they were resolved by cooperative efforts between the Contractor and the Owner/Engineer.

Jan 1, 2001

By S. Frimpong

Cable shovels are used for primary excavation in in-situ and/or pre-fragmented formations in surface mining operations. Poorly fragmented hard rock formations and random occurrence of hard boulders in soft formations cause extreme variability of material diggability, resulting in varying shovel stress loading. The stress loading of a shovel’s front-end assembly could result in fatigue failure. Conventional design process, which uses physical shovel simulation studies, is very costly and time consuming for achieving statistically significant results. In this paper, rigid and flexible multi-body dynamic theories are used to develop component stress loading and deformation models of the cable shovel, and solved in the ADAMS/NASTRAN/FLEX environments. Detailed simulation experiments are carried out to examine the performance, reliability, durability and efficiency of the P&H 4100A under varying in-situ formation conditions. The results show areas of high stress fields with a maximum stress of 313.31 MPa at node 441 within the hoist rope. The reliability of the results is confirmed by comparing existing test data. The study is significant because it provides a solid foundation for further study of failure life analysis of the cable shovel components.

Jan 1, 2007

By Robert B. Bittner

Large diameter piles (2 to 3 m diameter, both driven and drilled) are being used more frequently by designers of bridge foundations. The use of these large piles allows the pile cap to be positioned off the bottom but usually still below water. Conventional cofferdams as shown in Figure 1 below are not suited to this type of pile cap. However, float-in cofferdams offer a viable alternative. This paper describes the float-in cofferdam system, its initial development for use on the Bath-Woolwich Bridge in Maine and its most recent application on the new Carquinez Bridge in California.

Jan 1, 2013

By Zajber A, Kulchen R, Letzel D, Weyer A, Schwellenbach J

The search for modem casting plant concepts today focuses more and more on the harmonisation and optimisation of overall concept lines to obtain a continuous quality control and reduce the cost of production (Figure 1). Fin I As far as continuous casting plant concepts are concerned, this specifically requires an optimal adaptation and flexible operation when converting liquid steel into a directly processable product without any in-between treatment. Continuous casters need to fully satisfy the requirements of both the upstream steelmaking facilities as well as the downstream rolling facilities.

Jan 1, 1999

By Phillip M. Dight

A number of impending and actual pit wall failures have been observed and documented which have been interpreted to initiate on newly generated structural features. This infers failure through intact rock. Failure mechanisms have been postulated resulting from circumferential stress, extensional strain and brittle flexure. These will be discussed in the context of the failures and the associated monitoring. The implications of failure initiating on ?unknown? features has a significant impact for deep open pit mines where designs are based on the expected structural regime. Being able to anticipate such failures is important for design. Equally important is management of such changes as they arise. In this context, monitoring using high resolution microseismic techniques will be discussed as a means of providing early warning of such failures.

Jan 1, 2006