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By M. F. Bradley, G. M. Schoen

The Magmont Mine, a 50/50 venture between Cominco American Incorporated (the Operator) and Dresser Industries, Inc., (Halliburton), is a metallic mining and milling facility in the new lead belt of Missouri. The mine is located approximately 100 miles southwest of St. Louis. Legislation passed in 1992 by the Missouri legislature requires all metallic mining and processing facilities to apply for a Metallic Minerals Waste Management permit (MMWM) for their waste facilities. Regulations were subsequently promulgated by the Missouri Department of Natural Resources (DNR). Cominco obtained a MMWM permit (MM-006) from the Missouri DNR in 1992.

Jan 1, 2001

By Petr Mostak, Miroslav Horacek, Miroslav Stancl

Detection of plastic explosives is an important task in the security measures against criminal misuses of this type of explosive. Particles and vapour detectors are basic instruments in this detection. Colour reactions and dogs are also used. Marking system in accordance with requirements of Montreal Convention was developed and applied in full scale production of plastic explosives including Semtex since 199 1. The influence of marking on technology, performance and other properties of plastic explosives is discussed. 2,3 dimethyl 2,3 dinitrobutan is the most popular marking agent which is broadly used. The detectability of this compound is not optimum by some detectors. The substantial effort has been given to development of plastic explosives with controlled shelflife. Some results of this work are presented. Technical and economic aspects of identification marking are discussed.

Jan 1, 2001

By Anil Saigal, Jr. Fuller, Said Jahanmir

"All-ceramic crowns, including glass-infiltrated spinel composites, are coming into widespread use because of their superior aesthetics and chemical inertness. This study investigates the residual stresses that are developed in these composites as a result of cool down from the glass-infiltration temperature to room temperature due to slight mismatch in the coefficients of thermal expansion and its effect on the mechanical behavior of these composites. Two-dimensional finite element simulations were performed using an object oriented finite element program OOF. The OOF program is a combination of two programs. The first program, PPM200F, is designed to read an image file such as a micrograph. The individual pixels that constitute the micrograph may be collected into groups and their material properties assigned. PPM200F is then used to create the finite element model/mesh that OOF then reads. The average residual stresses are found to be tensile in the spinel matrix and compressive in the infiltrated-glass. There is large variation in residual stresses and strains from location to location with presence of locations at which the glass is under tensile stress. The crack initiation and initial propagation in glass-spinel composites is at the glass-spinel interface in both the glass and the spinel. The presence of residual stresses can lead to lower crack initiation stresses and degrade the mechanical properties of the composites.IntroductionGlass-infiltrated spinel ceramics are in clinical use as core materials in all-ceramic crowns and as inlays and onlays (1-3). Advantages of ceramic composites include near net-shape forming with high strength in the infiltrated state. Besides, spinel is quite translucent and may potentially be used without a veneer. However, these ceramic composites are subject to damage accumulation from repeat oral contact loading and often fail after a few years of use (4). This paper examines the residual stresses that are developed in these composites, after cooldown from the glass infiltration temperature to room temperature, due to the slight mismatch in the coefficients of the thermal expansion of the two phases."

Jan 1, 2001

By Denise Corrêa de Oliveira

Common dry batteries use zinc as the negative electrode. Producers commonly use additives such as mercury to prevent corrosion and to increase the mechanical resistance of the zinc anode. Alkaline batteries also contain it, as an anti-corrosive agent. When mixed with the common municipal solid waste, heavy metals as zinc and mercury pollute soil and ground water supplies, moving to the food-chain and affecting human health. Due to these possible damages, this kind of waste must be properly disposed, or recycled. Thus, even in low amounts (ppm) in batteries, mercury has to be eliminated or, at least, its content should be reduced. This work presents the use of pyromettalurgical processes, to reduce mercury content and recover zinc. The tests involved batteries treatment at temperatures from 300° to 1000°C. Mercury is eliminated up to 650°C, and zinc is evaporated at higher temperature treatment. C

Jan 1, 2001

By Mark Cross, Hadi Abou-Chakra, Nicholas Christakis, Mayur K. Patel, John Baxter, Ugur Tiizful

"In recent years significant effort has been put into using continuum mechanics for the description of granular flows. Although these models are partially successful in capturing some flow characteristics, they lack essential information on material properties, which are needed to account for the interactions between different particles. Thus, they are incomplete and can not be used to describe processes such as hopper filling/emptying and pneumatic conveying, where particle-particle interactions can lead to phenomena such as segregation, degradation and agglomeration. In this paper, a 3-D unstructured finite-volume framework is presented, which employs interface tracking techniques to solve for the individual material components of the granular mixture in the bulk and thus, determine the material-air interface. Various transport processes, arising from the micro-mechanical properties of the different particle species in the granular mixture, can be obtained through kinetic theory. The transport coefficients of each of the individual species can be determined and analysed in a micro-mechanical framework and the transport process parametrised in the form of constitutive models. These models provide the continuum theory with information on the micro-mechanics.This work describes the continuum framework and the micro-mechanical parametrisations, which are used to describe the processes and interactions at the microscopic level. Numerical simulations and comparisons with experimental data are then presented for the case of binary granular mixtures and conclusions are drawn on the capability of the model to realistically predict and quantify the main characteristics of granular flows."

Jan 1, 2001

By Greg Mclellan, Mark Johnson, John Pepper

In this paper, the measured vibrations are plotted in terms of the individual PPV components versus Scaled Distance (SD) on logarithmic scales. The maximum PPV is pIotted on a separate graph and equations are presented to predict the maximum PPV based on sealed distance and prediction level usmg power fits. The prediction levels include a 99.9% curve, which encompasses the data points and provides an envelope formula for determining the maximum PPV at South Florida sites. The dominant frequency distribution is established for the PPV components.

Jan 1, 2001

By David Sainsbury, Bevan Thompson, Yuejun Cai

The practice of placing loose rockfill as passive support in open stoping voids, of narrow vein mineral deposits, lends itself to the sterilisation of substantial mining reserves in the requirement for regional crown/sill pillars. Significant benefits are to be gained by the Australian mining industry via the development of improved guidelines for the extraction of such sterilised mine pillars. The application of selectively injecting specifically developed ettringite (calcium sulphoaluminate hydrate) type cement grout into loose rockfill, enables an artificial pillar to stabilise the surrounding rockmass and prevent the caving of loose rockfill from the previously backfilled void during extraction of remnant crowdsill pillars. This paper presents the results of laboratory testing used to reduce the technical risks associated with the design of cemented rockfill pillars. A laboratory testing program was devised to investigate the critical parameters influencing the performance of a stabilised rockfill matrix, along with the critical parameters influencing the interpretation of laboratory test samples. The factors investigated include; sample size and shape, particle size distribution, curing time, water quality, cement : water ratio and the confinement effect.

Jan 1, 2001

By J. F. T. Agapito, R. R. Goodrich

Yield pillars have been used for many years to help reduce stresses near mine openings and improve roof and floor stability. A yield pillar is often defined as a pillar that fails but retains residual strength. Stress transfer occurs through the roof and floor after the peak strength of the pillar is reached. High stresses are transferred from around the openings onto abutments that can be barrier pillars or unmined ground. This mechanism, often referred to as pressure arching, is possible as long as the width of yield pillars is less than the critical width above which stresses cannot be carried by the overburden. Significant stress transfer also can occur due to small amounts of pillar and/or floor yielding before the peak strength is reached. This is accomplished in a quasi-elastic manner with little or no visible roof and pillar fracturing or floor heave. Long-term stability may be achieved when stresses and mechanical properties are favorable to pre-failure yielding. This paper gives practical examples where improvements in stability and resource recovery were achieved with this mechanism. Yielding was assessed by comparing measured and calculated vertical pillar stresses. Results indicated that calculated stresses in the pillars were 25 to 40 percent higher than the measured stresses, demonstrating significant arching load transfer to the abutments. Pre-failure yielding is probably often present but unintentional in both development and production areas. Better recognition and use of this mechanism should lead to improved designs as mines become deeper.

Jan 1, 2001

By S. Malinov, J. J. McKeown, W. Sha, S. McShane

"A model is developed for prediction of fatigue stress life S-N diagrams for Ti-6Al-4V alloy at different conditions, using Artificial Neural Network (ANN). Different factors which have influence on the S-N diagram are involved as input parameters of the NN, namely microstructure, environment, texture, test/work temperature, surface treatment and stress amplitude. As the output the S-N fatigue diagram is simulated and plotted.The model is based on standard multilayer feedforward neural network. The NN is trained with a comprehensive data set collected from the literature, using Levenberg-Marquardt training algorithm in combination with Bayesian regularisation. A very good performance of the trained Neural Network is achieved. Good correspondence between ANN"" prediction and experimental S-N diagrams is observed. Using the model S-N diagrams for different conditions are predicted and analysed. Graphical User Interface is developed for use of the model. We believe that the model will be important for practical applications in solving various problems on fatigue behaviour of the titanium alloy.IntroductionTitanium and its alloys have an increasing range of applications due to their very good combination of mechanical properties, corrosion and erosion resistance. They are currently finding widespread applications in many industries due to their desirable and versatile properties. Most important among the alloys is Ti-6AI-4Y. Jet aircraft manufacturers are the principal 'consumers of Ti-6Al-4V and it is often specified for critical parts, the failure of which could result in the loss of an entire system. A generic class of Ti-6AI-4V has been developed over the past years and it has become the best understood of all the titanium alloys. The advantages of titanium alloys include: (i) low densities, giving very attractive strength to weight ratios allowing lighter and stronger structures; (ii) superior corrosion and erosion resistance in many environments; (iii) high temperature capability. Although the titanium materials are still considered as expensive materials, for many applications the cost of titanium alloys can be justified on the basis of their desirable properties."

Jan 1, 2001

By A. Bothma

The Impala No. 1A ventilation shaft is located approximately 15 kms north of Rustenburg and is accessed via the R510road from Rustenburg to Northam/Thabazimbi. This situation is shown on the location plan in Figure 1. The geology at the site consists of an upper layer of black turf of about 1 metre in thickness, grading into weathered norite. The depth of weathering is generally less than 5 metres. Zones of deeper weathering may occur along fracture zones associated with faults and dykes. Groundwater occurs mainly within the weathered/fractured aquifer system. The ventilation shaft is a 5.1 m diameter upcast shaft ,and forms part of a system of ventilation shafts to complement the existing infrastructure as mining progresses down the new twin decline extension of Impala 1 shaft. The principal reason for these shafts is to lessen the risk of an extended RAW and also to counter the effects of the heat build-up as the mining goes deeper, with the resultant effect that the existing cooling centre (fridge plant) becomes more remote from activities. The No. 1A shaft (upcast) is positioned approximately 1,2 km on down dip from the main shaft and the No. 1Bshaft (downcast) approximately 1,2 km further. Geological information was used from a borehole 1,2 km away on strike from the upcast shaft. The first shaft (1A) is a 5,1 m diameter hole to be fitted with two 2,2 MW fans, whilst the second shaft (1B) is 4,1 m diameter to accommodate a 7MW fridge plant.

Jan 1, 2001

By Thomas M. Barczak

The initial Support Technology Optimization Program (STOP), Version 1.0, was released at the 19th Gmund Control Conference. This original program has since been updated to Version 2.3 which was released in May, 2001. This paper describes the additional features of Version 2.3, focusing primarily on the following three aspects: (I) including uncontrolled convergence into the design requirements for standing roof supports, (21 the addition of design procedures for cable bolts as an alternative secondary roof support, and (3) the addition of new standing roof support technologies. Another new feature which should facilitate the development of design criteria for standing roof support is the capabilily to define ground reaction curves through convergence measurements alone wthout having to make support loading measurements. There are several other new features provided in Version 2.3 which are only briefly addressed in the paper. These include: (I) additional graphics capabilities to facilitate rapid assessment of support comparisons. (2) an East-West designation for support selection to more accurately provide cost and support availability data, (3) additional safety measures including a safety factor to identify support design near the peak support capacity, checks to see if the support dimensions comply with aspect ratio requirements, and measure of roof coverage for the design layout of the support system These new features of STOP provide more capabilities to design and analyze secondary roof support systems for conditions whlch could not be fully analyzed in the original version of the program.

Jan 1, 2001

By Larry Rayburn

In the spring of 1999, construction commenced on the new Steelers Football Stadium in downtown Pittsburgh, Pennsylvania. Richard Goettle, Inc. (RGI) was the successful bidder to install the specified augercast piles for the foundation package. Description - Pittsburgh Steelers Stadium The new stadium will house the Pittsburgh Steelers Professional Football Team. It is widely believed that if a team is provided with a modern playing facility, that a winning season will ensue (Not always the case). The new stadium location is on the north side of Pittsburgh on the Ohio River, and just downstream of the confluence of the Monongahela and Allegheny Rivers. The site is west of existing Three Rivers Stadium. The Three Rivers Stadium was built during the late sixties and housed both the Pirates Baseball and Steelers Football Teams. The Public Auditorium Authority elected to replace this outdated stadium with two new stadiums, one for each professional team. The landmark stadium was imploded in February of 2001.

Jan 1, 2001

By J. Wickens

This paper discusses how Bald Mountain Mine dramatically reduced mercury production by treating process solutions with a liquid reagent called UNR 811A. The reagent is marketed by Cherokee Chemical Co., Inc. A summary of the bench tests comparing several different reagents is given. The ensuing plant trial is discussed and results are presented. The plant trial treatment costs are discussed. Finally, potential cost savings are discussed.

Jan 1, 2001

By H. Bilgin, Sedat Esen

In this paper, the ground vibrations induced by blasting for stripping work at Sekkoy Open Cast Coal Mine belonging to TKI Yenikoy Lignite Mine (YLI) are investigated and the procedures for monitoring and control of ground vibrations are presented. Ground vibration measurements are conducted in the direction of Turkish Electricity Authorities’ Yenikoy Establishment and social facilities because of the complaints and annoyance arising from this site. Forty ground vibration records are taken in this direction and the vibrations are measured in transverse, vertical, longitudinal components together with peak vector sum. After then the scaled distance relationship is determined at 95% confidence value. Further, Fast Fourier Transform analyses are carried out to determine dominant frequencies for both ground and the structures and amplification factors. When the records taken at four different structures together with the ground are evaluated, it is observed that one of the apartment buildings is amplified the amplitude of longitudinal component 4.3 times. The maximum allowable amount of explosive that can be fired safely at this mine is calculated and recommended on. In the determination of safe amount, 95% confidence line, USBM RI8507 and OSMRE criteria, the dominant frequencies of both ground and the structure, amplification factor and the human response are taken into account.

Jan 1, 2001

By Nils Lippmann, Ulrich Weber, Siegfried Schmauder, Jr. Mishnaevsky

"A computational approach to the optimization of fracture resistance of multiphase materials (here - high speed steels) by varying their microstructure is presented. The main points of the optimization of steels are as follows: (1) development and verification of the model: numerical simulation of crack initiation and growth in real microstructures of steels, (2) computational experiment: simulation of crack growth in different idealized quasi-real microstructures and (3) the comparison of fracture resistances of different microstructures and the development of recommendations to the improvement of the fracture toughness of steels. Numerical simulations of crack growth in real microstructures of steels and different idealized carbide distributions are carried out. On the basis of the simulations, recommendations for the improvement of high speed steel microstructures are given. It is shown that the fracture resistance of the steels is much higher for the fine than for the coarse version of the same type of microstructures.IntroductionThe purpose of this work is to develop an approach to the optimal design of multiphase materials on the basis of numerical simulation of their behaviour under mechanical loading. We suggest here the following strategy:1. Collecting input data for the simulations: taking a micrograph of a microstructure, and determining mechanical properties and failure conditions of the material constituents [1, 2],2. Simulation techniques and assumptions are tested for a real microstructure of the material: crack growth in a real microstructure is simulated and then compared with the experimental data,3. Computational experiments: different microstructures of materials are tested in the numerical model under the same loading conditions. The calculated service properties of the different microstructures are compared, and recommendations are developed. As differentiated from the ""real"" experimental techniques, the computational experiment is much cheaper and not labor- and time-consuming."

Jan 1, 2001

By B. Erik Ydstie, Dimitrios I. Gerogiorgis, Sridhar S. Seetharaman

"Carbothermic production of aluminium is an important alternative to electrolytic processes and has in fact been identified several decades ago as a potentially feasible and profitable process. The cornerstone principle is to take advantage of the endothermic reduction reaction between carbon and alumina instead of resorting to extreme amounts of electric energy to ionize and reduce aluminium oxide to aluminium. Electric energy is necessary only for heating purposes.The present study focuses on constructing and solving a steady-state electrothermic model for obtaining the spatial distributions for electric potential, electric field intensity and temperature. The complex issues of reaction kinetics and multiphase flow are handled by an approximation and are not addressed at the present stage, due to the lack of complete validated models. Because of its inherent complexity, the reaction slag is considered a pseudohomogeneous layer.An electrothermic simulation encompasses important research challenges, due to the limited knowledge of thermophysical properties for high-temperature multi component molten slags. Therefore, thermophysical property modeling and a systematic compilation of published data is a necessary and major first step towards enhancing understanding of the process fundamentals. Models are obtained by analyzing measurement data from numerous literature references for the density, viscosity, thermal and electrical conductivity and specific heat capacity of the slag.The electric potential, field intensity and temperature distributions obtained reveal interesting maxima which indicate localized superheating and lead to important engineering conclusions. The temperature profile calculated will serve as the foundation for the flow problem solution. This computational study will form a basis for future research towards combining the scopes of microscale CFD modeling and mesoscale process modeling into a unified modeling approach."

Jan 1, 2001

By Lon Santis

Although unproven, it is suspected that there have been eleven locations since 1988 where explosive generated carbon monoxide (CO) gas moved through the earth and accumulated in nearby underground enclosed spaces. This paper summarizes the incidents, which involved about 30 suspected or medically verified CO poisonings and 1 fatality. Ten incidents occurred in residences and one occurred in a manhole. Although practically nothing is known about the mechanism behind the suspected gas migration, review of the incidents and available information indicates there are certain warning signs and a successful remediation technique available. In each case, overburden heavily confined the explosive in the blasts, preventing release of explosive-generated gases to the atmosphere. All the blasts were in residential areas, and none were excavated immediately. Where the distance from the blast was recorded, 5 of the blasts were within 20 to 50 feet (ft) (6 to 15 meters [m]) of the underground enclosed spaces, 3 were 100 to 150 ft (30 to 46 m) away, and 1 was 400 to 500 ft (120 to 150 m) away. Investigators often identified suspected pathways from the blast site into the underground enclosed spaces. One technique appeared successful at quickly correcting an existing condition. This technique involved applying negative pressure to the earth and removing the CO from the ground surrounding the underground enclosed space.

Jan 1, 2001

By A A. Struthers, A D. Farmer

Power ultrasound may be applied to enhancing the processing of minerals. The enhanced performance is achieved through the very localised high-energy release at the mineral surface from the collapse of cavitation bubbles produced by power ultrasound. This gives rise to two effects: initially, the rapid cleaning of mineral surfaces û of oxidation products and coatings of fine adhering gangue minerals û and the attenuation of the boundary layer at the mineral surface during leaching, which allows fresh leachant to contact the surface more readily. Work carried out at CSIRO in conjunction with Tiwest Joint Venture has demonstrated that it is feasible to apply ultrasound to the leaching process in order to enhance the removal of contaminating minerals. When applied to the production of synthetic rutile from reduced ilmenite produced by the Becher process, the use of ultrasound proved beneficial to both the aeration and the final acid leach process. The effect of ultrasound was less marked in the case of the aeration process, once the method of introducing and dispersing the air was optimised. In the subsequent acid leaching step of the Becher process it was found that the application of power ultrasound could reduce leaching time to about one quarter of the time required when only agitation was employed. Projected capital and operating costs, based on currently available commercial equipment, are also presented, and indicate that the use of ultrasound is commercially as well as technically feasible.

Jan 1, 2001

By Karl H. Brandt

In the Auguste Victoria mine a bolted rectangular roadway has been kept open for the first time in the seam D/C after retreat. The target of the project was to gain a basis for planning and experience for future mining layouts in the same scam in view of the reuse of boated rectangular roadways. For this the roadway was additionally secured in sections with longbolts before the influence of the retreating panel had taken place. On retreat a concrete sidepack was concurrently put in place on the face side. The installed monitoring systems consisted of endoscopic devices, multiple extensometers (Tell-Tales), shear-tales, extensometers and convergence measurements. The experience that was gained was carried over into a physical and numerical model.

Jan 1, 2001

By Ali Porbaha

Rapid growth in the urban development requires continuous search for innovative technologies to construct complex infrastructure systems. Deep mixing is one promising construction technology that has a wide spectrum of applications for development and expansion of complex urban facilities. Large number of reported case history of the projects in Europe, Japan, and the US demonstrate the versatility of the technology compared to conventional methods of ground modification. A large number of factors influence the quality of the soil cement columns; some of these are rooted in the installation process and the effective use of machinery during construction. This paper attempts to present some issues related to installation of deep mixing that affect quality of the treated columns. Presented here are various installation patterns, installation machinery, installation sequence, effect of penetration/withdrawal injection methods, penetration/withdrawal speed, effect of number of shafts, rotation of the blade, shape and orientation of mixing tools, and rotational speed of the shaft on quality of the treated ground.

Jan 1, 2001