Search Documents

By Ditze A., C. Scharf

Magnesium type 1 - scrap can be remelted without flux in the presence of different sulfur containing protective gases. Beside the draw back in the use of these gases, that either are contributing to the global warming potential (SF6) or are poisonous (S02), residues like dross and crucible sludge are produced. Dross and sludge now a days must be utilized. Partly these byproducts can be used in the aluminum industry and partly for desulphurisation of hot metal and steel. Another possibility is melting of dross and sludge with flux for the production of a secondary magnesium alloy. Then again residues are generated that must be processed. Therefore, the whole material cycle has to be considered to decide which kind of utilization practice is optimum. Based on experiments this question is discussed and the material balances for fluxfree melting, melting with flux and fluxfree melting plus other utilization of the residues are presented.

Jan 1, 2000

By Peter Wells, Gordon Marrs, Dominic Fragomeni, Warren Holmes, Daryl Macnamara

"LocationThe Strathcona mill ofFalconbridge Limited is located in Onaping, Ontario, 50 km northwest of Sudbury.GeneralOre from the Falconbridge mines in the Sudbury Basin (Strathcona, Fraser, Onaping, Craig and Thayer Lindsley mines) is processed through the Strathcona mill with 8500 t of nickel ore and 1500 t of copper ore being treated daily. Current capacity is -3 Mt of ore at 1.8% Ni, 1.9% Cu combined grade. Custom feeds are also processed. The valuable minerals in the ore are pentlandite (FeNi)9S8, chalcopyrite (CuFeS2) with some cubanite (CuFe2S3) and very minor nickel sulphides/ arsenides. Cobalt is present mainly in solid solution in pentlandite. There are small but economically important concentrations of precious metals including platinum, palladium gold, and silver. The common non-sulphide gangue minerals are feldspar, quartz, mica, talc, and chlorite while pyrrhotite (Fe7S8) is the major gangue sulphide. The pyrrhotite contains between 0.6% and 1.2% nickel in solid solution and additional nickel as exsolved pentlandite in micron sized blebs. The nickel and copper ores are batch-crushed in a two stage dry crushing plant and then ground in separate circuits. Concentration by flotation and magnetic separation produces a nickel concentrate assaying approximately 16% nickel plus copper and a copper concentrate assaying 30% copper and 0.4% nickel. The nickel concentrate is trucked as a slurry to the Falconbridge smelter while the copper concentrate is trucked as filter cake to the Kidd Division of Falcon bridge"

Jan 1, 2000

By Tim O’Neil

The search for precious metals opened up the American West. And Nevada was right in the heart of this development. In the mid-19th century, prospectors seeking gold roamed the hills of Nevada and discovered the ComstockLode. The development of this huge silver and gold deposit began in1859 and was responsible for Nevada’s early entry to statehood. Mining was Nevada’s first industry. In more recent years, the Nevada mining industry has led the nation in gold, silver and barite production. Nevada also produces many other minerals. These include aggregates, clays, copper, diatomite, dolomite, gypsum, lime and limestone, lithium and magnesium compounds, perlite, salt and silica. Even today, Nevada’s mining industry continues to be a major economic force in the state. The mining industry has made more than $10 billion in capital investments in Nevada since 1985. And the value of Nevada’s mineral production last year was about $2.7 billion.

Jan 1, 2000

By Douglas Bartley, Robert McClure

This paper discusses the advances in programmable, testable high accuracy electronic detonator technology. The operation and safety of electronic detonator systems are required to meet rigid safety standards and withstand the demanding environment of in-field applications. These requirements are discussed through comments on existing safety requirements in Europe.

Jan 1, 2000

By Derek H. C. Wilton, David T. W. Evans

"Abstract - The Midas Pond gold prospect, central Newfoundland, is hosted by sheared and altered felsic and mafic pyroclastic rocks of the Tulks Hill volcanics, Victoria Lake Group, and has been trenched and tested by 19 diamond-drill holes. Gold values are sporadic, with the best diamond-drill intersection assaying 7.3 g/t over 0.9 m, and the highest grade channel sample containing 14.7 g/t over 1.15 m. Alteration and mineralization are confined to a 200 m wide brittle-ductile shear zone. This shear zone formed in response to regional D1 deformation, and the shear zone fabric parallels the regional S1 foliation. D2 deformation resulted in broad Z-shaped flexuring of the shear zone. The deformation was probably related to the ca. 396 Ma to 420 Ma Salinic Orogeny.Advanced argillic alteration and an extensive halo of Fe-carbonate and pyrite surround the gold mineralization. Alteration minerals include pyrophyllite, paragonite, quartz, plagioclase, chlorite, fluorite, Fe-carbonate, and pyrite. As such, the alteration seems to reflect combined epithermal (argillic) and mesothermal (carbonate) mineralizing environments. The argillic alteration and fluorite represent a regional hydrothermal effect on the felsic volcanic rocks; whereas, the Fe-carbonate and pyrite represent a mesothermal alteration associated with auriferous quartz veins. The Au, which is spatially associated with pyrite, occurs in three structurally-controlled vein sets. These veins are confined to the contact between a highly deformed breccia (the banded mafic tuff) and structurally overlying, altered felsic tuffaceous rocks. The vein sets include: V1 boudinage veins that parallel the shear-zone fabric (C-shear veins), and V2 and V3 extensional fracture veins which are controlled by an S2 fracture cleavage. V1 veins are the earliest and contain the lowest concentrations of Au. V2 and V3 veins are concentrated within the hinges of the D2 flexures.Pb isotope data for galena separates indicate that the Pb in the vein systems was probably of local derivation. Sulfur, C, and O isotope data for mineral separates are similar to data for typical mesothermal lode gold deposits. Fluid inclusion data suggest the presence of at least three hydrothermal fluid types in the region, viz., (1) an early saline fluid which produced the argillic alteration, (2) a CO2-bearing fluid directly related to the auriferous mineralization, and (3) H2O-NaCl fluids which flowed through the Midas Pond shear zone at a lateral distance from the zone of mineralization. The mineralizing fluids are interpreted to have been CO3 -2-rich types which originated through metamorphic dehydration and decarbonation of mixed island-arc and continental crustal rocks. Gold precipitation resulted from the reaction of these fluids with the Fe-rich breccia unit. Pre-existing and simultaneously crystallizing pyrite served as loci for Au precipitation."

Jan 1, 2000

By Dave Otto, Ron Elliot, Ed Hatch

This paper is a summary of the work carried out by an international team of specialists in the successful explosive compaction of the sand fill core of the Molikpaq offshore oil production structure. The sand fill core is an essential element for the stability of the structure. The sand core must resist liquefaction forces caused by heavy wave action, ice loading, and earthquakes. Explosive compaction methods were used to improve the stability of 220,000 cubic meters of coarse dredged sand placed in the core area. This project was challenging for a number of reasons. It was performed offshore in Russia, seven kilometers off the East Coast of Sakhalin Island. Logistics were a challenge, not just in getting the men and materials to the site, but also working with restricted headroom inside an operating oil drilling platform. This project called for the use of specialty explosives, strict blast vibration controls requiring a complex sequential blast design, and use of custom designed drill rigs. As Russian equivalent explosives were not available, the project involved getting approval for use of North American explosives in Russia, and use of a combined Russian - Canadian blasting crew. The blasting program was carried out successfully, meeting the required densification target _in a safe, effective manner, with no damage to the structure.

Jan 1, 2000

By K. J. Martchek

"This introductory presentation will highlight recent efforts to quantify the positive value of recycling metals such as aluminum, magnesium, lead, zinc, nickel and copper in relation to the three pillars of ""sustainable development"" - environmental protection, economic development and improve social consequences.This presentation will provide an overview of life cycle assessment profiles increasingly being utilized by customers, regulators and environmental advocacy groups to holistically evaluate the environmental performance of materials and products. The environmental profiles of prodi.lcts containing recycled metal will be presented based on rules established by the International Organization for Standardization (ISO).Significant to the life cycle profile of metal products is recent confirmation. that recycling has the potential to reduce materials production energy consumption by 95% for aluminum, 80""/o for magnesium and lead, 75% for zinc, and 70% for copper. Furthermore, . ""metals are eminently and repeatedly recyclable, while maintaining all their properties (1 ). "" Their durability relative to many hydrocarbon based materials enhance .their life cycle performance. However, the persistence of metals when dispersed into our natural environmental makes recovery and recycling particularly important Overall, when considering life cycle effects, recycling is critical to a sustainable future for metal products.Finally, regional and international regulations will be highlighted which will effect the efficient recovery and recycle of metals and their overall contribution to environinental protection, economic development and the enhancement of society."

Jan 1, 2000

By Florian Kongoli

New operating conditions and process parameters are often necessary in today's industrial practice of non-ferrous smelting and converting in order to accommodate various new chemical compositions of mineral charges and environmental requirements or to conceive new and more efficient industrial technologies. An important parameter in non-ferrous smelting and converting is the liquidus surface of multicomponent slags. This surface is affected by multiple factors such as temperature, gaseous potentials, the content of each component in the slag, etc., and cannot be quantified by the existing ternary liquidus diagrams. In this work a new type of representation of the liquidus surface of multi component systems has been presented by means of a thermodynamic model. This representation waives the need of the multidimensional representation of multi component systems and yields practical two-dimensional diagrams, which can be easily used in the industrial practice.

Jan 1, 2000

? Hollow Stem Auger ? Drill Bits ? Leads/Torque Arm ? Hydraulic Gearbox ? Hydraulic Power Unit ? Grout Pump ? Crawler Crane

Jan 1, 2000

By Edward Fitch

The DOE is evaluating Yucca Mountain, Nevada as a potential site for disposal of high level nuclear waste. Yucca Mountain is located approximately 160 km northwest of Las Vegas on the western edge of the Nevada Test Site and the Nellis Air Force Range. An exploratory tunnel has been constructed through Yucca Mountain for site characterization. A controlled drilling and blasting technique, smooth wall blasting, was used to excavate the TBM starter tunnel and alcoves off the main tunnel to provide areas for scientific investigation. Fundamental to the blasting program has been the use of two blast design equations used in concert to minimize blast damage to the surrounding rock mass. The first of these equations was developed by Roger Holmberg and estimates near-field peak particle velocity that is the basis for minimizing blast damage to the host rock. The second of these equations was developed by B. H. Sanden and provides bore hole pressure estimation which allows controls to minimize crushing of the rock mass along the perimeter yet allowing enough force to create tensile failure between perimeter bore holes. This is key to the smooth wall blasting technique. To date, essentially the same controlled drilling and blasting program has been in place for all excavation requiring controlled drilling and blasting at the ESF. The controlled drilling and blasting program uses an iterative process to achieve continuous improvement in the blast rounds. This involves interaction between Architect and Engineer (A/E), Constructor, and Testing Coordination O&e (TCO) to ensure each blast round successfully meets the expectations of affected participants. The A/E requested that the TCO provide validation of the near-field peak particle velocity estimation under the Construction Monitoring Program. Data gathered under this program were reduced by statistical analysis and used to verify blast design parameters and provide a site specific blast damage relationship.

Jan 1, 2000

This paper discusses the requirements for a successful simulation modelling study, and the steps involved in the modelling process. Advantages and disadvantages of simulation are described, and a case study highlights how not to go about it. Two other case studies, for a decline truck haulage and a block caving production operation, are used to illustrate the types of variables whose impact may be investigated. Typical results are presented to indicate the sorts of presentation styles the author has found useful for conveying study results to project sponsors. Standard spreadsheet charting techniques can be very useful in this respect, but the possibilities are limited only by the imagination of the study team.

Jan 1, 2000

By Mitsuhiro Ito

"To allow various wastes containing high levels of chlorine to be used as alternative raw materials for Portland cement, two practical methods of chlorine removal were developed. In the first method, chlorine is extracted from the wastes during the cement manufacturing process. In the second, ash-dust waste with high chlorine content is first washed and then dehydrated to cake before being introduced to the cement manufacturing process. This cake can be used as an alternative for some cement raw materials. By combining the two methods, various wastes previously considered unsuitable for recycling due to their chlorine content can often now be used in cement manufacturing plants. As such, these methods represent a major contribution to environmental protection as well as a solution to problems relating to the diffusion of heavy metals and dioxins from cement plants.1. IntroductionWaste generation levels have risen rapidly in recent years. in both the consumer and industrial sectors and today, the need for effective, efficient waste management is one of the most pressing and serious problem of today's society.The Japanese cement industry has reacted to the increase in waste generation by using certain materials as alternative raw inputs or fuels for cement production, in an effort to contribute to society and conserve energy resources.These wastes often contain non-negligible levels of chlorine and heavy metals, however, both of which are unsuitable for cement production. Depending on the element content, Heavy metals have a particularly negative effect -on cement quality; in addition, they can be released into the environment. Chlorine, on the other hand, is contained in large amounts in incinerated ash from household wastes as well as in certain plastics. Both substances are considered impediments in cement-production, not only because they reduce the quality of the cement produced but also because they impair operating safety on cement production lines.To address this problem, two practical technologies have been established for separation and recovery of chlorine components during cement pre-processing and production. This paper introduces the application of these technologies with a special focus on incinerated ash from urban wastes, a representative form of waste material having notably high concentrations of chlorine, heavy metals, and dioxins. We also outline the technologies enabling this material to be used as an alternative input to cement production."

Jan 1, 2000

By D. J. Cassidy

This document discusses commercial strategies and applications of specialty processing plants for the recycling of nickel, copper, zinc and cobalt bearing by-products. For this discussion, I will focus on materials originating from the metal plating, electronic circuit board· and chemical industries. The review of select processes and the required service, sourcing, material handling, processing and marketing strategies necessary for a successful recycling program are highlighted. Materials discussed in this summary include filtercakes, filters, dusts, spent catalysts, spent solutions and solids. Both pyrometallurgical and hyrometallurgical applications to these materials are addressed. A comparison of targeted finished markets, including smelter feeds and value added products are also reviewed.

Jan 1, 2000

By I. R. Muirhead, A. L. Craven

The trend in mining thermal coal is only to mine coal with the lowest sulphur content. In many coal seams, bands of coal with high sulphur content are often present, generally occurring either at the roof or floor level. Methods of selective mining are, therefore, necessary to recover only the low sulphur coal. This paper examines the methods currently in use in mines and the alternative methods that are able or have potential to offer control of shearers and continuous miners where greater thicknesses of coal have to be left in the roof and floor. These alternative methods rely on such characteristics as neutron gamma radiation; electromagnetic waves; vibration; infrared; infrared; optical; pick force; X-ray fluorescence; conductivity; gyroscopes and laser systems.

Jan 1, 2000

By using knowledge-based technology to create a Virtual Mining Enterprise and integrating it with existing technical and financial computer systems, a gold mining company has been able to reduce the time taken to produce a mine plan from 14 weeks to less than one week. Typically, the mine planning process requires circulating and managing large amounts of information. Even with the use of computers in todayÆs business, this is often still a manual process involving file transfers and individualised spreadsheets. Mine planning also involves understanding and managing large quantities of complex and interrelated variables. Added to this is the ever changing dynamics and constraints associated with the business of mining. These issues not only hamper the planning process but also question the validity and usefulness of the mine plans being generated. By integrating the information and knowledge of the numerous departments involved in mine planning into one core Knowledge Base - so called æone version of the truthÆ, - mining companies are able to overcome these pitfalls experienced in traditional planning methods. Once set up, the Knowledge Base creates and runs a virtual mining enterprise with which to visualise and test various scenarios of mining, business and logistical activities. The final output is an optimised enterprise-wide plan with clear and detailed instructions for each of the divisions of the company.

Jan 1, 2000

By J Player

Big Bell Mine started experiencing relatively large mining related seismic events, and accompanying rockbursts, from February 1999. Twelve rockbursts damaged access development from February 1999 to June 2000, with severe damage extending for up to 100 m along footwall drives. Five seismic events associated with the rockbursts were recorded by the AGSO, measuring 1.9, 2.2, 1.7, 2.4 and 2.2 on the Richter scale. These events affected 485 and 460 footwall drives in August and November 1999 and 535 footwall drive in June 2000 (drive level nomenclature is equivalent to the depth below surface and RL). After the third event (July 1999) it was apparent that the seismicity was not a once-off phenomenon. This (sudden) onset of seismicity required management to implement a series of precautionary measures:to ensure the safety of the workforce, to maintain continuity of production, and to reduce rockburst damage rehabilitation. The measures included extended re-entry periods and exclusion zones in high-risk areas, improved rockburst resistant support systems in areas prone to damaging seismic activity and improved support systems in areas prone to shakedown damage. A full-scale minewide ISS seismic system was ordered in October 1999 and commissioned in February 2000. A portable eight-channel CSIR-Miningtek system was installed at short notice as an interim measure in August 1999. This CSIR system covered the northern producing stopes, where the majority of the rockbursts had occurred. The objective of the seismic monitoring was to monitor relative activity and to determine trends with regards to time and location. MAP3D numerical modelling was used to investigate the relationship between seismicity and various combinations of stress components to assess the relative seismic risk in both current and proposed working areas. This information is used to determine where and at what stage in the mining cycle the rockburst resistant support is required. Analysis of the seismicity has determined two distinct modes of seismicity û small-scale localised, high frequency events in high stress areas and larger events related to shear along previously intact foliation surfaces. This paper includes a summary of the seismic history, seismic data analysis, support system design, mine design adjustments and management action to minimise the effects of seismic activity at Big Bell Mine.

Jan 1, 2000

By Paul Morrison

The paper describes the design process, trial testing and contract pile installation of 772 pre­cast concrete piles at a site in Surrey, South East England. Recommendations on how to improve the design, construction trials and main contract piling phases of the project are made. The building layout is shown in Figure 1 and is comprised of a central circulation area with five office wings radiating out from its southern side (only three of these wings were constructed in Phase 1 of the project). Approximately 60% of the circulation area and one office wing were built with a single level basement. The basement was constructed "bottom-up" in open cut with the void between the basement walls and the cut slope being back-filled with compacted site won soil above a perimeter drainage system at basement slab level. The building has up to 3 stories above basement level and is a reinforced concrete structure. The client for the project is Pfizer Ltd. Pfizer Ltd was represented on site by Laing Project Management (Laing). The consulting engineer was Ove Arup and Partners (Arup) while the piling contractor was Roger Bullivant Ltd (RBL).

Jan 1, 2000

Magnetic separation using particle rotation in a continuously rotating magnetic field offers very low to insignificant non-magnetic particle entrapment, and precise magnetic fractions. The precision of rotating magnetic field separations makes the method ideal for dry laboratory magnetic analysis work, where conventional laboratory magnetic separators can give misleading or uncertain data. The very low entrapment characteristics make the method ideal for entrapment-critical separations within the diamond exploration industry or in gold recovery. A single wet rotating magnetic field (RMF) unit is able to achieve a cleaner separation (at similar or better recovery rates) than a three-stage separation using conventional wet drum separators. The RMF separator is able to work effectively at particle sizes below 50 ¦m, and RMF separation could, at least in theory, be used down to single domain particle sizes. Rotating magnetic field (RMF) separation is carried out by magnetically spinning the particles at frequencies up to 300 Hz. The particle rotation itself may be used to roll the particles out of the separator. At angular velocities of 100 Hz, magnetic flocs are unable to form, and any entrapped particles are energetically expelled. In an RMF separator, the outer drum can be stationary while the inner magnet rotor rotates, allowing, for example, the injection of cleaning water underneath the separating magnetics to help remove small suspended non-magnetic particles.

Jan 1, 2000

By Kazuyoshi Sato, Keizo Uematsu, Nozomu Uchida

"Confocal fluorescence scanning laser microscope was applied to characterize the surface flaw of ceramics in great detail. A high potential -of the characterization technique is presented first. Then the technique was applied to clarify the relationship between the flexural strength of ceramics and the surface flaw. This kind of direct information of surface flaw should be essential for the fundamental study in this area, but has been lacking. The examination revealed that large defects are present on the machined surface of ceramics. Their size is consistent to the flexural strength measured on the material. The characterization tool was also applied to examine the formation of surface flaw in machining of ceramics.IntroductionClarification of fracture origin should be the starting point in the study on strength in ceramics. However, this task has been extremely difficult in some ceramics, such as an alumina ceramics. It may break from both internal and surface flaws. The former should reflect the quality of production process and the latter the machining. Examination of surface flaws should be very important for developing a better machining method for ceramics. The knowledge may valuable for establishing a better production process also.ExperimentAlumina Referceram (JFCC) was used as samples. They are cut to size of 3x4x40mm, and the surfaces were ground to meet the requirements of testing method for flexural strength of fine ceramics, JIS R 1601. They were soaked in an aqueous solution of fluorescence dye and evacuated with an aspirator for an hour to allow the solution penetrate into surface flaws. After excessive solution remained on the surface was removed by gentle washing, the specimens were dried at 120°C for 48 hours. The 4 point bending mode was applied to measure the fracture strength."

Jan 1, 2000

By lchiro Aoi, Hideo Nakae, Makoto Yoshida, Makoto Ishino

"The influence 6f gravity on the microstructure of unidirectionally solidified Cu-Pb monotectic, Ag-Si and Fe-C eutectic alloys is studied. In order to examine the influence of gravity in a lg environment, both the upward (opposite to direction of gravity) and downward (direction of gravity) unidirectional solidifications are carried out. The results are as follows: (1) For the upward solidified Ag-Si eutectic alloy, the eutectic Si continuously grows. On the other hand, in the downward solidified Ag-Si alloy, the Si grows discontinuously and disperses into the ex-Ag matrix. (2) No morphological difference in the eutectic growth is observed between the upward and downward solidified Fe-C eutectic alloys. (3) In the case of the upward solidified Cu-Pb monotectic alloy, a banded structure, which consists of Pb-rich layers and Cu-rich layers, is observed. However, such a banded structure -is not observed in the downward specimen. (4) The banded structure is not found in the upward solidified Cu-Pb-0.05 mass % Al and Cu-Pb-0.1 mass % Al alloys. In the Cu-Pb-0.05 mass% Al alloy, a fibrous -L 2 phase grows continuously parallel to the growth direction at low growth rate. Only 500 mass ppm addition of aluminum induces the morphological change of the monotectic L2 phase.IntroductionThe influence of gravity on the solidification of eutectic and monotectic alloys has been investigated in microgravity environments [l-9]. The purpose of these studies was to obtain a homogeneous microstructure of eutectic or monotectic alloys, most of which alloys tend to solidify with macro-segregation under gravity. However, in most of the previous experiments, e.g., in free fall systems, in aircraft or in space laboratories, the growth rate was too high to realize a planar solid/liquid interface. This would be due to the limited time for solidification. Thus, it was difficult to examine the influence of gravity on the planar coupled growth of the eutectic or monotectic alloy. In this study, both the downward U.D.S. (unidirectional solidification by gravity) and upward U.D.S. (opposite direction to gravity) are carried out in order to examine the influence of gravity on the coupled growth in a lg environment [l0, 11]. In the case of the downward U.D.S. using the current Bridgman method, the molten alloy must be confined between the crucible and the solid."

Jan 1, 2000