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By R. Q. Honaker

Although the fundamental principles of hindered bed classifiers are relatively simple, the complex interactions between the operating parameters provide a degree of difficulty that hinders the ability for on-line plant optimization. Thus, a dynamic population balance model was developed for determining the hindered settling velocity of particles varying in density and size. The steady-state results of the model include partition curves as a function of particle size and density as well as metallurgical data. A statistical comparison of the simulation results with those obtained from industrial units reveal a high level of accuracy with adjusted R2 values greater than 0.95.

Jan 1, 1999

By Ali Nadir Khan

Depleting copper resources and advancing technologies have challenged industries to develop more viable, adaptable and cost efficient processes using also secondary raw materials in copper production. This study is targeting to that goal by dynamic modelling of flow and heat transfer coupled with chemical kinetics in an industrial scale flash smelting furnace settler using commercial CFD software ANSYS Fluent. First, different physical phenomena occurring inside the settler, for example, settling and separation of the matte/slag phases, and heat transfer between slag/matte phases and settler walls are studied. Secondly, reaction kinetics between matte and slag, and between slag/matte and settler walls, and impurity element distribution will be studied. This would also include phase changes phenomena due to these reactions and the flow of the reaction gases inside the settler. Settling of polydispersed droplets, their coagulation, breakage, and WEEE particle behavior are further targets of the modelling work.

By M. Karamoozian

Modelling and optimisation of the power draw of large SAG mills are important due to the large power draw which modern mills require (5~10 MW). The cost of grinding is the single biggest cost within the entire process of mineral processing. Traditionally, modelling of the mill power draw has been done using empirical models. Although these models are reliable, they cannot model mills and operating conditions, which are not within the model database boundaries. Also, due to their static nature, the impact of the changing conditions on the power draw, within the mill, cannot be deter-mined using such models. Despite advances in computing power, on-line modelling of large plant scale mills could be a time consuming task. On the other hand, using on-line parameters for model-ling, result in more reliable control of SAG mill without performing any more costly tests. In this paper, SAG mill power draw is modelled using neural network approach. Six inputs, namely: solid percent, two bearing pressures, noise, recycle and feed rate were used to model the power draw. The produced model shows an acceptable correlation coefficient, R2 =0.9623.

Jan 1, 2014

By K. Nikkhah, N. Dhadli, G. Freeman

Ammoniacal pressure leaching operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation since 1954. Recent improvements have significantly increased the capacity of this circuit. The computer modeling of this process has proved to be a valuable tool in facilitating the evaluation of different operating scenarios in an effective manner. Reagent response in the ammonia leach of nickel and cobalt sulphides is examined using the dynamic process simulation capabilities of IDEAS(TM) software. The dynamic simulation enables accurate measurement of the sensitivity of the process to variables such as temperature, feed rate and ammonia concentration as well as compartmental analysis of metals concentration, pulp density, vent gas composition, and the formation of specific complexes. The complexity of the ammonia leach process makes it a logical choice for evaluation by computational analysis. The methodology for dynamic modeling of a pressure leach process is presented.

Jan 1, 2005

By D. Bahrami, W. K. Asante, G. L. Danko

It is prudent to interpret atmospheric monitoring signals in real time for checking the safe limits of the air conditions in underground mines. In gassy mines, real-time evaluation increases the safety of operations. In all mines, continuous monitoring and evaluation contributes to maintaining air conditions within healthy and safe limits. Signal interpretation for safety conditions in mines is difficult for many reasons. An increase in hazardous contaminant concentrations can be predicted by signal pattern recognition, root cause analysis of rapid changes toward deterioration, and forward prediction in time using algorithms and numerical models. The paper describes an early warning system for analyzing monitored signal patterns continuously in real time as well as forward predicting the various environmental and working conditions to recognize dangerous trends that may affect safety and health in underground mines. A dynamic, numerical ventilation model with heat and gas contaminant simulation components is used for the analysis of atmospheric data. Methods and test results are discussed with numerical examples for signal propagation prediction. Several mine examples are studied using controlled, synthetic data for malfunction simulations to evaluate time delays between the detection time of suspicious signal trends and the time of dangerous threshold crossing marking an accident scenario. Delay time is found in the order of 20 min in the examples, signifying the useful time period for preventive intervention between EWS warning and the likely breakout of a following accident.

By Patrick J. Hannigan

The pile foundation designer typically performs a subsurface exploration program and static pile capacity calculations before selecting a pile foundation type, length, and capacity. During construction, a pile installation criterion must be established to meet these design requirements. This installation criterion usually consists of a minimum penetration resistance or blow count to confirm pile capacity and may also include a minimum embedment requirement. This text will focus on use of wave equation analysis and dynamic measurements to meet design requirements. BEFORE THE WAVE EQUATION Since the mid-1800s, over 450 dynamic formulas for pile driving control have proliferated. In their simplest form, these formulas relate hammer energy to the work of soil resistance, or simply: W ? h = R ? s (1) Where W = ram weight h = ram drop height or stroke R = pile capacity s = pile penetration per blow

Jan 1, 1990

By D. Michael Holloway

The realignment of Interstate 880 replaces the double-decked (Cypress) viaduct collapsed in Oakland, California during the 1989 Loma Prieta Earthquake. The California Department of Transportation (CALTRANS) evaluated several pile foundation schemes for supporting the proposed structures. Structural support demands led to the selection of steel pipe piles (16-, 24-, and 42-inch-(406-, 610- and 1067-mm-)diameter), filled with concrete and steel reinforcement. Deep penetrations required through layers of very dense/cemented sands in some locations, caused serious drivability and pile integrity concerns. The need for large pile driving hammers and large diameter steel pipe piles pushed the engineers and prospective contractors well beyond the limits of local experience. Such questions as the feasibility of driving the pipes closed-ended through dense upper strata, and quantifying the effects of installation on the long-term capacities of the piles, led CALTRANS to develop a comprehensive pile test program to address the design and construction issues effectively. The results were furnished to prospective bidders on the production stages of the ensuing contracts.

Jan 1, 1996

By Garfiansyah Rayes

In 2023, an Indonesian coal mine experienced significant contamination of an emulsion blend explosive by dynamic mud and water flow, triggered by flooding due to exceptionally high rainfall. This intrusion into explosive columns compromised the stability and efficiency of blasting operations, thereby impacting overall mining productivity. The extent and impact of these contaminants on the stability and performance of the emulsion blend explosive were rigorously analyzed through a robust assessment methodology that included comprehensive field measurements and controlled laboratory experiments designed to replicate the challenging site conditions. Utilizing a combination of theoretical calculations and Computational Fluid Dynamics (CFD) simulations, this study evaluates the kinetic interactions between dynamic mud flows and emulsion explosives within drill holes. The methodology integrates Torricelli’s theorem for velocity assessments and Darcy’s Law for understanding the penetration mechanics of mud into the emulsion blend. CFD simulations are further correlated with actual blast data to assess discrepancies between theoretical predictions and real-world outcomes. Results demonstrate a significant reduction in the velocity of detonation (VOD) of the explo-sives, traced directly to mud contamination levels, which align with the quantified penetration rates in the study. Practical measures for mitigating such contamination are proposed, including the reinforcement of water-ways, culverts, and bund walls at drilling locations based on validated simulation data. Additionally, rec-ommendations for operational adjustments during high rainfall events are discussed, aiming to enhance blasting safety and efficiency. The paper concludes by suggesting future research directions towards the development of more resilient emulsion formulations and enhanced predictive modeling techniques to better forecast the impacts of en-vironmental variables on explosive performance in mining operations

Jan 21, 2025

By Scott Webster

Dynamic pile Monitoring Services (DMS) have been used for testing of offshore piles for several decades. However, most of this testing was to measure hammer performance and pile stresses rather than pile capacity or soil resistance. As the need for more economical solutions for foundation support increases, the use of DMS has provided a better means of evaluating in-place pile capacity for offshore structures, and therefore a method of determining pile acceptance. The authors have been involved in several offshore projects where DMS has been the primary source of data for acceptance of the driven pile foundations. The use of DMS for evaluation of offshore foundations requires considerations quite different from land applications and these considerations are often necessary for the careful and thorough analysis of the collected data in nearly real time for determination of pile acceptance. Case Method capacity estimates are often of little use due to the non-uniform cross sections of the foundation piles and their deep penetrations. Therefore, capacity assessments should be made using CAPWAP which is a signal matching program whose utility and reliability has been proven on thousands of projects every year, both on land and offshore. Depending upon the soil conditions at a given location, capacity assessment after soil setup effects may be necessary. In addition, tension capacity is often critical when pile refusal occurs significantly before the design pile penetration depth. Evaluation of uplift capacity can be accomplished by a CAPWAP analysis, which results in a total capacity prediction and its shaft resistance component. The use of hydraulic hammers for driving of these piles also adds the requirement of controlling hammer energy such that over-stressing of the pile is avoided. The calculation of non-axial stresses such as bending or eccentric stresses may also be involved in order to prevent pile damage.

Jan 1, 2010

By G. G. Goble

Dynamic pile testing is now over 20 years old as a routinely applied tool for evaluating driven pile installation. The first test on a cast-in-place pile was performed more that 15 years ago. The research that produced the method began almost 30 years ago. But, questions still arise regarding the appropriate use of this technique so some review is useful. Today a number of methods including dynamic testing all depending in some way on the application of dynamics are in routine use. First, Wave Equation analysis can be used to predict pile driveability before going to the field. The same approach can be used during driving to estimate the bearing capacity based on the blow count observed in the field. Dynamic measurements, on the other hand, can only be used after pile driving has begun. They offer predictions of pile capacity as well as measurements of hammer, driving system, and pile driving performance characteristics. The first part of this paper will be devoted to discussing how the foundation engineer can use these tools. First, a brief review of what dynamic methods actually do. In Wave Equation analysis a numerical model of the hammer, driving system, pile, and the soil is created by the engineer. The hammer is dropped on the pile and using a discrete, dynamic analysis the motion of the individual pile elements is calculated as a function of time. Of course, input information must be supplied by the program user to describe the hammer, driving system, pile, and soil. In the current state of development, the primary problem in input data is with the hammer performance (efficiency) and the soil description. Research may be able to do a better job with the soil data, but hammer performance will always vary from hammer to hammer and is dependent on the affectiveness of the inspection process. Prior to beginning pile driving the Wave Equation analysis supplies the best available estimate of what will happen when driving begins. It gives an estimate of blow count during driving, driving stresses, both tension and compression in the pile, and for diesel hammers, stroke. The selection of the driving system can be checked with the results of Wave Equation analysis and modifications can be made if required. For example, if the blow count at the required capacity was deemed excessive by the contractor a larger hammer could be tried or if driving stresses were too high changes could be made in the cushion or the hammer selection could be modified. All of these modifications are possible with only the cost of a computer run. The primary questions regarding the accuracy and reliability of Wave Equation analysis at this time is with regard to the assumptions made to represent the soil characteristics and the difficulty in predicting hammer performance.

Jan 1, 1993

By Jonathan G. Cannon

"This paper will describe dynamic pile testing conducted during installation of driven octagonal precast prestressed concrete piles used as the foundation for this bridge. The piles were long and hence spliced. A number of the piles showed damage near the splices and the damage location was near the ground surface so that the damage could be verified using visual inspection. The piles and splice configuration are still in use today without modification. Further WEAP driveability analysis has been conducted which demonstrates the effect of the splice on pile stresses and a likely failure mode. A slight modification is proposed to the splice that should prevent the damage on future projects.INTRODUCTIONThe bridge site is located on the Olympic Way, Route 41, about 20km north of the regional centre of Albury, NSW. For a long distance north of the site the Olympic Way ""shadows"" the main Melbourne to Sydney rail line and is located on the Western side and in close proximity. At the bridge site there was previously a sharp dog-leg in the road and a right angle level crossing with the road changing to the Eastern side of the rail line, eventually joining up with the Hume Highway, which in turn now becomes a ring-road through the eastern outskirts of Albury. The dog-leg and rail crossing had warning signs and bells, speed restrictions and rumble strips to warn approaching motorists to reduce speed. Site distance was exceptionally good.Approximately 2years before construction a group of five ""high spirited"" young men from the local area were driving south on the Olympic Way adjacent to a south-bound train. It is understood they interacted with the train crew for a period of time. Unfortunately the car and train collided at the level crossing and all of the young men were killed. There were outpourings of grief in the local community and a decision was made to replace the level crossing with a road-over-rail bridge.The bridge was highly skewed with two piers and two high level abutments with fill embankments on both approaches.GROUND CONDITIONSThe site is open grazing country with approximately level ground at the site with surrounding low hills. The geology was unremarkable with consistent stiff clays for a considerable depth.The design required driven precast prestressed pile foundations with the piles to be driven to a considerable depth.Hard driving with high tension stresses were evident from the start of driving and a variety of different pre-bore lengths were adopted in an attempt to minimise driving and potential for damage. At the abutments the pile locations were predrilled for at least the full embankment depth.PILESThe piles were 550mm octagonal prestressed concrete with the pier piles being single piece and the longer abutment piles being two-piece with a ""standard"" epoxy glued box splice. Pier piles and the initial length of the abutment piles were 24m. The add-on piece used at the abutments was 12m. Pile concrete was grade 50MPa."

Jan 1, 1900

By Juan M. Antorena

A dynamic testing program was performed to evaluate installation procedures, assess capacity of 610-mm (24-inch) diameter open ended steel pipe to evaluate set-up and provide minimum pile tip elevation based on the dynamic testing results. The program was performed for a marine terminal project consisting of a 570-meter (1900-foot) long, overwater railroad trestle. The project location is Santa Marta, Colombia, South America. The subsurface profile generally consisted of 4m (12 ft.) of water and soft to hard silty clays. The piles were installed to an approximate tip elevation of -22 meters (MSL). Three piles were initially dynamically monitored during installation and then later monitored during restrike driving to evaluate pile drivability and bearing capacity including time related capacity increases due to soil "set-up". Knowledge of change in pile capacity with time after end of initial driving is important for design of pile foundations.

Jan 1, 1995

By S Graskoski, S Craig, C Myburgh

Too often in mine planning, maximising revenue-generating material takes precedence over minimising costs. The ability to target both revenue and cost optimisation enables mine plans to fulfil corporate objectives of targeting maximal project net present value (NPV). The state of current mining costs and increasing government regulations in Australia are forcing many mine planners to pay closer attention to cost minimisation. Dumping waste material, which ultimately forms waste landforms, represents a large cost to mining operations. A general mine, with a waste to ore strip ration of 6:1, allocates approximately 32 per cent of total mining costs to waste haulage alone (Gregory, 2003).Most scheduling packages do not dynamically build economic or minimal cost dumps as part of the scheduling process. In most cases, waste dumps are built after a mining schedule has been defined. Automated software is now available which dynamically schedules the pit and waste dumps together. The overall shape of the waste dump is therefore dictated by minimum cost or minimum haulage hours.The purpose of this paper is to compare dynamic pit and waste schedules to traditional methods which apply haulage estimations after defining the mining schedule. This paper includes a case study on the large open pit operation at Tropicana Gold Mine, a joint venture between AngloGold Ashanti Australia Ltd (70 per cent) and Independence Group NL (30 per cent). The operation will focus on mining three large open pits over a 13-year mining life. A total of 397 Mt of waste is mined and directed to multiple destinations including waste dumps, the run-of-mine (ROM) pad and tailings storage facility (TSF) perimeter.Due to these complexities, management of the haulage fleet, especially during the critical period of operation readiness and start-up, is essential. Critical infrastructure such as the TSF and ROM pad will need to be built early and these areas, as well as the sequential development of the waste dump, will need to be developed within the constraints of structured mining fleet build-up.This paper investigates the influences of haulage estimation accuracy and compares traditional approaches for waste planning to automated approaches using EVORELUTIONÖ.CITATION:Graskoski, S, Craig, S and Myburgh, C, 2013. Dynamic pit and waste dump schedule optimisation at Tropicana Gold Mine, in Proceedings World Gold 2013 , pp 121-128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By A T. Spathis, M G. Wheatly

Some preliminary dynamic pressure data were obtained from several charges detonated in a tunnel situated in massive granite rock. The context of the work is the potential for desensitisation of explosives, failure of detonators, and sympathetic detonation due to the close proximity of inter-hole and inter-deck explosive charges to each other. Dynamic pressures were measured using piezoelectric gauges in water-filled 45 mm diameter holes adjacent to the charges. Some of the first arrival peak pressures were noisy, and although not fully resolved, may be due to reflections and the physical arrangement of the transducers and their size with respect to the monitoring holes. The estimated peak pressures were between 0.1 to 8.7 MPa at approximate distances of 2.8 to 0.8 m, respectively. Further work is planned with gauges that are disposable, have a higher pressure range, and can be used within a few borehole diameters rather than the piezoelectric gauges used in the present work.

Jan 1, 2016

By Alejandro Rosario, Ricardo Dumuihual, Guillermo Silva, be nito Danial Valde, Carlos Scherpenisse

A monitoring campaign to record dynamic pressures generated by detonation of a single blasthole was implemented at Barrick Gold´s Pueblo Viejo Open Pit mine (PVDC), located in the Dominican Republic. Pressure amplitudes beyond the dynamic compressive strength of the electronic detonator´s capsules have the potential to damage these electronic devices, generating misfires along with all the associated risks and entailed safety implications. In most instances, misfires generated from high dynamic pressures are a direct consequence of drilling deviations resulting in blasthole distances smaller than originally designed. Tourmaline Crystal Sensors specifically designed for high dynamic pressure measurements in aqueous media were selected to address the challenge. These sensors are custom-made and require additional instrumentation for proper operation, including signal conditioners and recording equipment capable of capturing simultaneous events, both in their amplitude and frequency components. Field-testing comprised detonation of a single blasthole using current explosive loading practices along with an arrangement of sensors positioned within water-filled drillholes in a spiral configuration. Distances, explosive weights and all 23 dynamic pressure record amplitudes are included along with additional data regarding arrival time and P-Wave velocity estimations. As with typical vibration models, the Scaled Distance concept (D/W1/2) was used to construct an attenuation model relating Dynamic Pressure as a function of Distance (D) and explosive Weight (W). The resulting model, adjusted to a 95% statistical confidence limit (covering 100% of the recorded data) was used to generate a series of curves (Abacus) estimating dynamic pressure as a function of distance for different explosive charges. These curves, in association with permissible pressure limits defined at 50% (FOS = 2) of the dynamic pressure strength reported by manufacturers for both, the 1000bar (Al) and the 1400bar (Cu) capsules; allow for the determination of critical (safe) distances between blastholes. Tests were implemented to cover a variety of field scenarios, accounting for different rock mass types, qualities and water conditions; however, preliminary analysis indicate the convenience of developing a unique trend that considers said variability. This approach allowed construction of a single, simple, unambiguous and operationally applicable design tool to address entailed safety issues.

By Ricardo González Dumuihual, Carlos Scherpenisse

A monitoring campaign to record dynamic pressures generated by detonation of a single blasthole was implemented at Barrick Gold´s Pueblo Viejo Open Pit mine (PVDC), located in the Dominican Republic . Pressure amplitudes beyond the dynamic compressive strength of the electronic detonator´s capsules have the potential to damage these electronic devices, generating misfires along with all the associated risks and entailed safety implications. In most instances, misfires generated from high dynamic pressures are a direct consequence of drilling deviations resulting in blasthole distances smaller than originally designed.

Feb 1, 2020

By L. Jiang

This report investigated the dynamic recrystallization (DRX) phenomenon in magnesium alloy AZ31 billets to understand the deformation mechanisms and microstructure evolution during extrusion and other metal forming processes, Compression tests of coarse-grained as-cast magnesium alloy billets containing lamellar Mg17Al12 eutectic phase and (Al, Mn) particles suggest that temperatures higher than 300°C, strains greater than 0,25 and strain rates above 0,l/s lead to the formation of fine DRX grains in the deformed samples. Microstructural observations also indicate particle-stimulated DRX nucleation (PSN) during hot deformation of the AZ31 alloy, facilitated by the presence of Mg17Al12 and (Al, Mn) particles, While the Mg17Al12 is dissolved into the matrix at about 350°C, (Al, Mn) particles may remain effective for PSN at temperatures up to at least 400°C, This study suggests that alloy design with a proper distribution of second-phase particles can provide the desired microstructure for improved properties and formability in wrought magnesium alloys.

Jan 1, 2004

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Seals and build-in-place (BIP) refuge alternatives (RAs) are two main underground structures to isolate an area from the active working zones with different purposes. While seals are used to prevent methane gas that seeps from coal seams and blast pressures from a possible detonation of the contained gas, RAs are used to provide a safe haven for miners who are unable to escape their working locations after an accident like an explosion or fire. The recommended BIP RA designs can be similar to seals constructed with steel-reinforced concrete. Both seal and BIP RA are constructed in different locations of the mines for a period of time, exposed to a certain convergence due to stress redistribution which can change their responses during an explosion. In this study, a steel-reinforced concrete wall to be used in such applications is simulated to examine the structural performance during an explosion for a coal mine model with different strata conditions using dynamic analysis by a 3D distinct element method (DEM) code. The main purpose of this study is to reveal any possible effects or trends on the wall deformation with changes in strata conditions by implementing different combinations of roof, seam, and floor material properties. The model is calibrated by the experiment conducted on a steel-reinforced concrete wall by the NIOSH researchers in the Lake Lynn Experimental Mine. The results show that strong adjacent rock and coal units are the least favorable condition for the survival of the wall subjected to a simulated explosion pressure. The results indicate that changes in the roof and seam conditions can have dramatic effects on the deformation characteristics of the wall when compared to the floor conditions. The results of this study might be enlightening for future BIP RA and seal applications.

Feb 8, 2023

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Mine explosions are one of the most concerning risks related to underground coal mining, as a single gas explosion can cause injuries and fatalities among miners. Underground infrastructure seals and build-in-place (BIP) refuge alternatives (RAs) are employed to isolate an area from active workings to mitigate coal mining-related accident risks. They are designed to withstand blast pressures from a possible accidental detonation of the contained gas or a coal dust explosion. Crosscut seals and BIP RAs, typically consisting of steel-reinforced concrete, are prone to strong convergence and have a significant leakage potential due to high convergence damage near mined-out areas. The roof-to-floor convergence can change the structural integrity of these structures, and altered structural integrity can lead to less explosion resistance capability. Hence, a thorough analysis is needed to further understand their explosion response under various strata conditions.

Jul 1, 2023

By Francis O. Otuonye

A time series and system analysis modeling technique was applied to signals from strain egages mounted on a fully grouted resin roof bolt and signals from accelerometers mounted on the bolt head and roof rock to determine the roof bolt's response to repeated blast loading. The derived model gives a comprehensive quantitative description of the modes of vibration of the roof bolt response to each blast loading. The damping ratios and natural frequencies of the modes of vibration can reveal the alteration of the process dynamics due to the deterioration of the roof rock and can be used to identify the incipience of instability in the roof bolt system.

Jan 1, 1987