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By N. Haghdadi, D. M. Maijer, A. B. Phillion

B206 is a recently-developed high-strength Al-Cu casting alloy with reduced Ti and Fe, as compared to the well-known AA 206 alloy, for improved hot tearing resistance. In the current study, the solidification kinetics of this alloy as a function of cooling rate from 1 to 15 K/min were studied using differential scanning calorimetry (DSC) and microscopy. Specifically, the evolution in fraction solid, grain size, and secondary dendrite arm spacing have been characterized. The DSC results show the occurrence of three peaks during cooling from the liquid state, which are related to the formation of primary aluminum, a pre-eutectic intermetallic, and the eutectic phases. Thermal analysis also indicates that while the liquidus temperature is not sensitive to the cooling rate, the temperatures at which the pre-eutectic and eutectic phases form are strongly coupled to the rate of heat extraction. A decrease in the latter temperatures was observed when the rate of solidification was increased, leading to a lengthening of the freezing range of the primary phase. The results will be useful for improving B206 casting processes, specifically through modification of mould cooling conditions.

Jan 1, 2014

By R. J. Rotzinger, K. W. Major

The Gibraltar Mine and Mill facility were commissioned in 1972 by Gibraltar Mines Ltd utilizing a flowsheet consisting of two stages of crushing followed by a rod mill / ball mill grinding circuit. During operations a number of opportunities were evaluated to expand the mill capacity; however, the economics of the day did not allow any of these projects to proceed. The mine continued to operate until late 1998 when it was shutdown and put on care and maintenance due to low commodity prices. Taseko Mines acquired Gibraltar in 1999 and in 2004, with the improvement in the metal markets, made the decision to restart operations. During the restart planning a number of opportunities for mill improvements and upgrades were identified and, after operations were successfully restarted, the decision was made to once again review expansion opportunities for Gibraltar. Taseko evaluated various expansion alternatives eventually deciding to install a SAG Mill, convert the existing rod mills to ball mills and distribute the SAG discharge to the resultant six 6 parallel ball mills. This paper discusses the design, implementation and commissioning of the SAG mill grinding circuit.

Jan 1, 2012

By H. Soto, P. Lacombe, R. del Villar

"During the summer of1989, Les Mines Selbaie, with the cooperation of Université Laval initiated a research project to evaluate the column flotation technology for its concentrator near Joutel, Quebec. The experimental work involved both a 5 cm by 11 m laboratory column and a 45 cm by 10 m home-made pilot unit Amenability tests were conducted using both units on various streams of the plant. Results showed that columns are not suitable for the copper cleaning circuit because the loss of precious metals, associated with the rejected pyrite, overcome the improved copper metallurgy. On the other hand, column testing at the zinc circuit showed improved zinc selectivity.Scale-up testing was', therefore, conducted on the first zinc cleaner concentrate using the laboratory-size column. The influence of variables such as porous parger grain size, wash water flow rate, airflow rate and froth depth values on column performance was' first assessed. Scale-up parameters were then determined using the optimal operating conditions from the previous tests. Simulation facilitated the determination of the most convenient plant-scale column arrangement.A number of conclusions concerning the experimental determination of scale-up parameters are also presented."

Jan 1, 1993

By Jerold Bishop

The application of the ?electro-hydrodynamic effect? (EHDE) to civil engineering has been made in the construction of drilled piles. Equipment for the commercial application of this process was developed in Russia in the late 1980's. The process is approved for general use by the Russian Federation building code and numerous projects have been successfully completed with this technique. EHDE is a process by which a moderately powerful shockwave is released in the bottom of a drill hole filled wet concrete slurry. The energy is carried outward through the fluid with minimal loss because it is an incompressible medium. Repetitive discharges provides a series of energy pulses which will compact the soil along the pile shaft and at base of the pile. The process is analogous to repeated applications of low energy blast densification or to dynamic compaction. In general, the process is not depth dependent. Repeated application of this treatment in a drilled pile hole can increase soil density at the base and along the shaft of the pile, as desired. The overall result is that the geotechnical capacity can be improved significantly. Test results documenting improvements are presented and other applications considered.

Jan 1, 2007

By Roger Henning

Although flotation is widely used throughout the minerals industry, it is a relatively inefficient process. The economic benefits of improved operation are considerable. A multivariable level stabilising system has been developed to reduce the amount of fluctuation in flotation levels. It has been shown on several plants that the better level control leads to improved metallurgical performance. A level measurement based on conductivity is also described. The device provides some insight into the behaviour of the froth.

May 25, 1998

By Richard E. Sylwester

Evaluating surface and subsurface conditions for marine foundations (bridges, causeways, terminals, etc.) is often done with a limited amount of data. Subsurface information for these projects is primarily acquired using traditional methods, such as boreholes, test pits or divers, which tend to be expensive and limited in the area of coverage. A number of geophysical methods, including precision bathymetry, sidescan sonar, and seismic reflection or subbottom profiling are extremely cost-effective and obtain significantly more data than can be acquired using traditional intrusive methods. These geophysical methods provide detailed surface images and continuous profiles of the subsurface stratigraphy. This information can be invaluable for selecting the best location for geotechnical boreholes and to map potential geohazards such as submarine slides and filled or open scour holes. Offshore investigations conducted for a proposed highway bridge (Knik Arm Bridge, Cook Inlet, AK), the retrofit of two existing bridge (Antioch and Dumbarton Bridges, CA) and a proposed cruise ship terminal (Ketchikan, AK) used a combination of geophysical methods to map water depth, detect and map debris on the seabed, map the thickness of unconsolidated sediment, determine the depth to bedrock and identify potential geohazards such as scour holes. The results of the geophysical investigations will be used to select locations for obtaining geotechnical borings, to extrapolate geologic information between existing or proposed boreholes, evaluate the potential depth of scour and design a pile support pier. Geotechnical engineers, offshore contractors and bridge designers are realizing the importance of the early use of offshore geophysics for (i) site characterization, (ii) to reduce the uncertainty of geotechnical conditions thus avoiding designs that may be overly conservative and thus more expensive and (iii) to assist in selecting locations for geotechnical borings.

Jan 1, 2013

If the industry keeps doing what it has always done, it will continue to get what it has always got - rising operating costs. Why is this so? Generally grades being chased are becoming lower, stripping ratios becoming higher, ability to attract personnel to the industry becoming harder and/or more expensive, higher safety standards are being demanded and environmental governance is being enforced.   How then should the surface mining industry plan for the future whilst delivering on improved safety and the environment? In-pit crushing and conveying (IPCC) points the way, as a partial or complete substitute for trucks.   IPCC systems promise significant advantages over traditional truck and shovel operations, including improved safety, reduced operating costs, reduced dust and noise emissions, far greater efficiency in energy use (electric versus diesel motors predominantly and the ability to regenerate electricity back into the local grid for downhill situations), reduced carbon emissions (dependent on power generation source) and reduced water consumption. Despite these advantages, there is a general industry reluctance to migrate from truck and shovel operations. This reluctance stems from a familiarity with truck and shovel operations and a perceived concern that IPCC lacks flexibility which will negatively impact on the mining operation.   In studies conducted since 2007 (with the new modular builds) comparing IPCC with truck-optimised pit designs, IPCC has delivered up to USD$0.82 per tonne moved less than an equivalent truck operation. In addition, IPCC is easily automated from a central control room (local or remote) - something that trucks have yet to commercially achieve.   IPCC is a proven process that, with a fresh mindset, can make a significant improvement to mining operations - its safety, the impact on the environment and its costs. It maybe of interest to note that there is over 200 IPCC installations worldwide today.   This paper and presentation will assist in furthering the understanding of IPCC and its applicability.

Jun 1, 2010

By N S. Weerasekara, S Town, E Lessing, J A. De Torres

Philsaga Mining Corporation (Philsaga) had three main aims in converting their lining system from steel to metal cap. They wanted to increase mill availability, minimise localised high wear and optimise particle breakage to deliver increased efficiency within the milling circuit. Combining Discrete Element Method (DEM) modelling and empirical interpretation of liner wear resulted in a rigorous approach to understanding the impact of mill liners on overall mill performance. This new understanding was subsequently used to not only derive a new lining design to optimise performance and thereby improve overall plant economics, but also to guide further lining development.In this work, detailed DEM modelling, developed from actual plant data, together with optimising liner design for wear paved the way towards the installation of a Metal Cap lining system at Philsaga’s Ø6100 mm SAG Mill. The results were a reported increase in SAG mill throughput of 16 – 20 per cent due to improved breakage through more efficient use of installed power, a reduction in localised high liner wear with overall increase in liner life and reduction in liner replacement time. Site also reported an increased gold recovery of 2 per cent which the improved breakage might have contributed to. This paper will present the design challenges and compare the Metal Cap lining systems performance against Steel lining system. CITATION:Weerasekara, N S, Lessing, E, Town, S and De Torres, J A, 2018. Metal cap versus steel lining system at Philsaga Mining Corporation’s Ø6100 mm SAG mill, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 653–664 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

The procedures for an audit and review process upon which continuous improvement programs may be based are described. The case for regular audits of mining operations to establish performance trends is advanced. Analysis of performance data using the parameters of the capacity equation used in conjunction with learning curves is described. The extrapolation of learning curves in performance target setting, operating and capital cost budgeting is advocated.

Jan 1, 1992

By E. F. Loros, T. J. Smolik, V. G. Lofftus

Since plant start-up in January 1983, Golden Sunlight Mines Inc. has implemented several process changes and improvements. Among these are a pulp preaeration circuit and a sand tailing retreatment circuit. The preaeration circuit reduces reagent consumption during gold dissolution. The sand tailing retreatment circuit was added to recover and process separately pyrite concentrate to maintain acceptable overall gold recoveries with the more refractory sulfide ores. Research and plant operating data along with process and improvement descriptions are presented.

Jan 1, 1987

By A. F. Saavedra, N. E. Richards, C. J. McMinn

"The aluminum industry in general and Reynolds Metals Company in particular have continued to support development work for improvement of the Hall cell design and for alternative processes for the reduction of alumina. The evolution of the Hall cell design will continue into the next century as a result of further development of mathematical models, sophisticated control systems and new materials for cell components. This paper discusses the areas in which the new generation cell advances will differ from the present day design. Additionally, Reynolds Metal s has supported work for the development of a carbo thermic process to reduce alumina. Theoretical work has indicated that this process could possibly have economic advantage over the Hall process. Several complicated furnace configurations have been proposed to provide the conditions for successfully reducing alumina. The results of small pilot scale operation and most promising furnace design are discussed. For comparison, projected capital investment costs and operation costs are discussed. IntroductionThe evolution of the Hall-Heroult process will continue into the next century. This evolution will be influenced by economics, more .restrictive environment and worker protection requirements, and technological development. These factors will also cause changes in the competitive position of alternate processes for aluminum production.Several aluminum producers have made major investments in alternate processes for aluminum production in the past three decades and there is continued support in some companies for improvements in the Hall-Heroult process and for alternate processes. The more visible development work in reduction technology, not aimed at significant process changes, is in the areas of higher amperage cells with bus bar designs to reduce harmful magnetic effects, more advanced and automated feed, voltage and electrolyte composition control, improved energy efficiency and sol id waste disposal . Efforts to bring significant change to the reduction process are being made in development of materials that can function as inert anodes and cathodes. These materials could lead to the development of reduction cells with multiple bipolar electrodes operating on oxide feed and fluoride electrolytes. Development work on new processes was reduced in the last decade by several companies because of economic and technological realities. Reynolds Metals supported work on a carbothermic process to reduce alumina and produce commercial pure aluminum. This work progressed through small pilot plant operation, and resulted in development of furnace designs and operation regimes. This paper reviews how this and other technologies could influence the reduction of alumina beyond the year 2000."

Jan 1, 1988

By Whiten W. J

An investigation on the breakage characteristics of closely sized orc samples at different levels of input energy was carried out to determine an appearance function for possible use in ball mill modelling. A consistent pattern of breakage behaviour was observed and the resultant size distributions could be described by a one-parameter, ('t'), family of curves. For each particle size range tested, this parameter 't' has an exponential relationship with input energy below an upper energy limit. A tentative linear relationship between the input energy at a constant value of 't' and the work-index leads to reconstruction of 'I' - input-energy curves from the work-index values. To normalise the efrect of particle size and input energy, multidimensional cubic spline regression was performed on thc entire range of data. The results indicated that the parameter 't' can be determined, reasonably accurately, as a function of Ln (input energy, kWh/tonne) and Ln (particle size, mm) for input energies between 0.5 and 8.0 kWh/tonne.

Jan 1, 1983

By Guo Qian, Du Guangyin, Deng Yongfeng, Liu Songyu, Wang Ningping

"Metakaolin (MK) can efficiently enhance the strength and the impermeability of concretes and mortars. However, it has rarely been attempted in admixtures of cement-stabilized soils until presently. As deep mixing method is wildly used in ground improvement, the strength of cemented soils (soilcrete) and the applicability of the MK should be considered. This paper focuses on the macro-strength development of cement-stabilised silty soil mixed with MK. The result shows that the addition of MK can enhance the unconfined compressive strength of the soilcrete, which attributes to a combination of the rates of OPC hydration and the MK-CH reaction. Note that the strength of soilcrete was influenced by the properties of soil, water-to-binder mass ratio (W/B) in admixtures, which needs to be reconsidered since the binder mass composes that of cement and MK totally.INTRODUCTIONCement was used in ground modification techniques, such as the jet grouting, deep mixing method (DMM) which was put into practices in Japan and Nordic countries in the middle of the 1970s, and then spread to China, South East Asia[1]. For last decades, fly ash, slag or silica fume was mixed with cement to form the new cement base stabilizing agent in the view of economy and performance improvement. The mechanical behavior of these soil-binder admixtures (nominated as “soilcrete”), was investigated. But the soilcrete modified with the metakaolin (MK) was still not investigated much and lots of further work needs to be conducted.Some laboratory experiments of the soilcretes modified with MK have been taken[2~4]. Kolovos et al. (2013) indicates that the unconfined compressive strength has a more significant improvement when W/B equals 0.4 than that when W/B equals 1.20 concerning the water-to-binder mass ratio (W/B). Sonebi et al. (2013) investigates the mechanical behaviors of cement grouting containing MK with W/B equals 0.4, and also found the effectiveness of the addition of MK. Zhang et al. (2014) performed the studies on Lianyungang marine clay improvement showed that MK obviously enhanced the quality of cemented soils.In this paper, the strength of soilcrete modified with MK is further investigated, where the unconfined compressive strength at different curing time, the content of MK and cement (w/w) in lab conditions was discussed."

Jan 1, 2015

By Steven W. Hunt, Isabelle Lamb, Steven B. Fradkin

Groundwater control is generally an important consideration and significant source of risk during most tunneling projects. Proper baselining of groundwater conditions requires: 1) a thorough understanding of the geological environment; 2) a focused site investigation; 3) identification of construction and adjacent property damage risks associated with inflows and short and long term piezometric level changes; and 4) consideration of contractual issues including restrictions on means and methods and pay items for associated work. This paper provides an overview of groundwater baselining issues and risks based on selected design studies and construction case histories.

Jan 1, 2005

By Joseph Meyers

Explosives techniques and technology are constantly evolving and improving, yet basic communication and business skills are not being used regularly. Many potential blasting projects never occur due to simplistic, basic factors, such as a lack of communication. Articulate communication is the key component in the blast approval process, which has changed remarkably from how business was conducted fifty years ago. Imperative to the approval process is communication outlining the safety and benefits of the blasting project. Information and transparency with the stakeholders and the Authority Having Jurisdiction (AHJ) will greatly improve the chances of having a blasting project approved. This open communication starts at the inception of the project when the memorandum of understanding (MOU) is obtained, and involves the AHJ through all steps of the approval process. The blasting industry and regulators must work collaboratively to improve safety, security, regulations and licensing. Implementing state of the art blasting techniques, security, safety measures, vibration monitoring and strict licensing allows the AHJ and all stakeholders to remain integrated and informed, contributing to process approval. Regulatory operators should strive to achieve success thru communication, cooperation and compliance which is accomplished thru continued education and transparency. These steps, combined with regular meetings, has proven to be a benefit to both industry and regulators. Relationships are built through trust, teamwork, transparency and communication –including the take holders and AHJ in the approval process from the inception solidifies these relationships and improves teamwork

By A Jurg, F Leclercq

The total drill and blast concept is widely known in the mining industry. On the contrary, the quarry industry rarely adopts such working methods. Based on the experience of the CBS quarry in the North of France, this paper shows how up-to-date blasting technology and simple control methods can significantly improve the overall Mine to Mill efficiency of a quarry. The CBS quarry, in partnership with the EPC group and Nitro- Bickford Company, adopted a new working process three years ago aimed at increasing blast performance and related productivity of the downstream process (loading, hauling and crushing). The pattern geometry of each blast is controlled and explosive charging is carried out following the æconstant specific energyÆ CSE concept. This method provides a homogeneous fragmentation distribution and reduces vibration peak-particle-velocities. The impact on downstream productivity is controlled by means of a simple information management system, which collects and measures key parameters of the production process such as; hauling cycles, crusher throughput, secondary breaking and vibration peak particle velocity. This information system has clearly proved over time that consistent blast quality could be achieved, leading to a 30 per cent improvement in quarry productivity. Improved energy control of blasting through optimisation with electronic detonators, allowed a significant reduction in vibration impact on the environment. Improvement in blasting security, reduction in the environmental impact and productivity enhancement are major benefits that quarries can obtain from these CSE optimisation blasting methods.

Jan 1, 2007

By Mi, Dong Liang, Jingyuan Bai, Victor Zhou, Xujun

Squirrel cage induction motors are the mostly used motors at present. Currently, the rotors of the squirrel cage induction motors are produced by aluminum die casting technique with the advantages of low cost of rotors. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size. Considering the huge quantity of motors, the die casting process is the best solution to produce copper rotor with economic cost. Because of the characteristics of copper, it is difficult to produce copper rotors by casting similar to that done in aluminum rotors. In order to improve the die casting quality of copper rotor, a new tooling structure was developed and the casting process of copper rotor was simulated and analyzed by Any-casting software. The filling process, solidification process, inner gas distribution and residual melt modulus were analyzed. It was found that the design of symmetrical runner and inner runner on both sides was helpful to reduce the impact of molten copper to the cavity surface during the filling process. The use of Slag traps array can reduce die casting defects inside the end rings. That will be helpful to improve the rotor quality. INTRODUCTION Squirrel-cage AC induction motors are most widely used in the world. In 2017, the total installed capacity of AC motors in China has reached more than 1.2 billion kW, and the annual power consumption accounts for about 60% of the total national electricity consumption. To improve the efficiency of squirrel-cage motor will be helpful to energy conservation and environment protection. There are several ways to improve efficiency of induction motors, using copper rotor is one of the most effective solutions. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size.

Jan 1, 2019

By Vijaya Bhushan Rao, Jason Redgers

A mixed-use development comprising of multistoried residential towers, retail and associated infrastructure covering an area of 500,000 m2 is under construction in Dubai. The subsoil conditions consist of calcareous sands with high carbonate and shell content with hard and competent strata encountered at varying depths. To achieve the design requirements of soil stiffness, friction angle, limit differential and total settlements and mitigate the liquefaction due to a seismic event then ground improvement were deemed necessary. In order to provide the most time and cost efficient solution numerous techniques were applied to meet the requirements for all depths such as Vibrocompaction, VC (depth >8m), Dynamic Compaction, DC (depth < 8m)] and Rapid Impact Compaction, RIC (depth <4m). The specified ground improvement requirements were translated into a target Cone Penetration Test, CPT line that served as the defacto performance requirements for the project. Suitable correction factors were applied to the CPT results to account for the high carbonate content following the works of Al-Homoud and Wehr 2006, Belotti and Jamiolkowski , 1991 and Vesic, 1965. Furthermore, the alpha factor, α, used to obtain stiffness from CPT results was applied following A.C. Meigh 1987 and Massarsch & Fellenius, 2005 where high over consolidation ratios (OCR) could be demonstrated.

Sep 8, 2021

By Vijaya Bhushan Rao, Jason Redgers

A mixed-use development comprising of multistoried residential towers, retail and associated infrastructure covering an area of 500,000 m2 is under construction in Dubai. The subsoil conditions consist of calcareous sands with high carbonate and shell content with hard and competent strata encountered at varying depths. To achieve the design requirements of soil stiffness, friction angle, limit differential and total settlements and mitigate the liquefaction due to a seismic event then ground improvement were deemed necessary. In order to provide the most time and cost efficient solution numerous techniques were applied to meet the requirements for all depths such as Vibrocompaction, VC (depth >8m), Dynamic Compaction, DC (depth < 8m)] and Rapid Impact Compaction, RIC (depth <4m). The specified ground improvement requirements were translated into a target Cone Penetration Test, CPT line that served as the defacto performance requirements for the project. Suitable correction factors were applied to the CPT results to account for the high carbonate content following the works of Al-Homoud and Wehr 2006, Belotti and Jamiolkowski , 1991 and Vesic, 1965. Furthermore, the alpha factor, α, used to obtain stiffness from CPT results was applied following A.C. Meigh 1987 and Massarsch & Fellenius, 2005 where high over consolidation ratios (OCR) could be demonstrated.

Sep 8, 2021

By James J. Olson

Most of the projects summarized in this paper are funded under the Bureau&apos;s Advancing Metal-Nonmetal Mining Technology program and are part of the in situ mining subprogram coordinated at the Twin Cities Mining Research Center. The borehole mining equipment development, are funded under the Bureau&apos;s Advancing Coal Mining Technology program, is essential to accelerated progress in the in situ mining subprogram, and some background information on this concept is included. The initial in situ research projects started in 1971-72 evaluated some of the critical blast design parameters for in situ copper leaching. The present program totals about $1 million per year and includes in-house research projects, cooperative (cost-sharing) projects with the mining industry, and research and development contracts. Two different extraction schemes are under investigation: inplace leaching and borehole (or slurry) mining. The principal commodity targets for the Bureau&apos;s improved in situ mining technologies include copper, uranium, coal, and potash. The principal purpose of this paper is to inform the mining industry of the in situ mining research recently completed or being conducted by the Bureau of Mines. In addition the Bureau encourages companies to comment on the program accomplishments as well as offer suggestions on top priority research needs for improving the in situ mining methods described in this paper.

Jan 1, 1977