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By D. Eriksen

Zero Emission Gas power, ZEG, is a novel concept where a high temperature solid oxide fuel cell (SOFC) is integrated with a reforming reactor producing hydrogen from natural gas through Sorption Enhanced Steam Methane Reforming (SESMR). The SOFC is used as a high temperature heat source for regeneration of the CO2-absorbent. Moreover, by using part of the produced hydrogen as fuel for the SOFC, the waste heat of the process is considerably reduced. Thus, the process has a very high thermal efficiency and produces both electricity and hydrogen from natural gas. In addition, a stream of pure CO2 is produced in the regeneration step and can be deposited or used commercially. Initial cost estimates indicate a cost of electricity and a cost of hydrogen well below today's prices. A small (1kWel + 1kW H2) demonstration set-up is under construction and experimental results and related research will be presented. This set-up comprises one 2.5kWth H2 SESMR-reactor (about 0.85 Nm3/h H2) operating batchwise with dolomite as the CO2-sorbent. The reactor developed is designed like a parallel plate heat exchanger where the mixture of sorbent and reforming catalyst is packed between the heat exchanging plates. The demonstration set-up includes a 1kW SOFC operating in a continuous mode. The set¬up will therefore demonstrate continuous simultaneous hydrogen- and electricity production, but cannot demonstrate simultanuous electricity- and CO2-production. The set?up is well equipped for on-line monitoring of gas composition, flows and temperatures. This important part of the demonstration set-up is developed and provided by Christian Michelsen Research (CMR). A minor part of the project is the development of a continuous circulating fluidized bed SESMR-reactor system and in another related project the focus is on the development of more suitable sorbents. In these two projects co-operation with University of British Columbia and Lousianna State University, respectively, is highly appreciated.

Jan 1, 2005

By L Maw

New ZealandÆs largest gold producersÆ OceanaGold Macraes Mine is characterised by a large tonnage and relatively low grade operation. To survive in diminishing real gold prices, the operation must focus on a culture of continuous improvement. This paper presents the outcome of a supplier sponsored continuous improvement project known as the Orica Advanced Mining Services project.   In March 2004 OceanaGold (then GRD Macraes) entered into an Advanced Mining Services (AMS) project with Orica Mining Services. The motivating factor behind OceanaGoldÆs need to improve bulk waste productivity and SAG mill throughput was the planned increase in production from five million to 5.4 million tonnes per annum. A stripping ratio of ten to one meant that optimisation of the drill, blast and production functions was paramount.   The primary focus of the project was to optimise the drill and blast parameters to suit the variable rock conditions throughout the mines main operating pit (Frasers Pit). Fragmentation of the ore for presentation at the SAG mill, and cost reduction on the mining of bulk waste movement, were the primary objectives. A number of additional initiatives complimenting the interface between drill, blast and ore production were also established. These included; +        reduced ore loss through delineation of ore boundaries to allow for blast movement; +        established blasting parameters for variable geological conditions, resulting in improved fragmentation; and +        improved asset utilisation by establishing a blasting regime that angled grade control holes to be used as blastholes in the stockworks area.   A year into the project, the philosophy of continuous improvement is now in-grained at the Macraes minesite. As the project continues, the focus is on the further refining of those procedures established, to ensure a continued focus on lower unit mining production costs.

Jan 1, 2005

By E S. Weiss, S P. Harteis

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments, to evaluate the strength characteristics of various seal designs, used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests conducted within the multiple entry section of PRLÆs Lake Lynn Experimental Mine (LLEM) is currently the only accepted test method used by the Mine Safety and Health Administration (MSHA), for deeming a seal design suitable for use in American mines. These explosion tests are labour intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. The PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in situ testing of seals in an operating mine. Two chambers within LLEM and one within PRLÆs Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from these chamber tests compare favourably with those from the large-scale explosion tests in the multiple entries. In addition to testing seal designs at the required 20 psi static pressure level, the chamber test approach also allows for the determination of the sealÆs ultimate design strength. Size-scaling relationships for predicting the strength of seal designs as a function of entry size are also presented.

Jan 1, 2005

By V. Kamavaram

Keywords: Recycling, Aluminum Metal Matrix Composite, Ionic Liquids, BMIC Recycling of aluminum metal matrix composites (MMC) via electrolysis in ionic liquids at near room temperature was investigated. The electrolytic melt comprised of 1-butyl-3-methylimidazolium chloride (BMIC) and anhydrous AlCl3. Impure aluminum composite (Duralcan MMC Al-380, 20 vol % SiC) was electrochemically dissolved at the anode and pure aluminum (>98%) was deposited on a copper cathode. The deposits were characterized by scanning electron microscope, X-ray diffractrometer, and mass spectrometer. The influence of various process parameters such as concentration of electrolyte, and applied cell voltage on the recycling process was studied. The recycling process yielded current densities in the range of 200-500 A/m2, and cathode current efficiency of about 85%. The results indicated that impurities such as Cu, Si, Ni, Fe, Mg, Mn, and SiC particles were removed as anode residue. Energy consumption of about 3.7-6.3 kWh/kg-Al was obtained at a cell voltage of 1.0-2.0 V and cell temperature of 100 ± 5°C. Low energy consumption and no emission of pollutants are the two main advantages of this process compared to present recycling processes.

Jan 1, 2005

By J Kinal, P Steinier

A considerable volume of work exists in the literature examining the electrochemical interactions between grinding media and sulfide minerals. Broadly, most sulfide minerals are more noble than forged steel grinding media used during comminution, therefore a galvanic couple between the media and the sulfide mineral(s) exists, which increases the corrosion rate of the grinding media. The corrosion products of the grinding media, iron oxy-hydroxide species, invariably precipitate on to the surfaces of the sulfide minerals thereby affecting their floatability. This paper explores the science behind these corrosion reactions, and provides an explanation of their impact on the pulp chemistry of sulfide mineral slurries and subsequent flotation behaviour. A number of laboratory and plant case studies are used to illustrate the benefits of changing to a more inert grinding media.

Jan 1, 2005

By Kerry Gee, Gary Colgan, James Fricke

Introduction Elevated zinc concentrations are observed in groundwater within alluvium adjacent to Silver Creek east of Park City, Utah. The study area is located in a small valley one and one-half miles northeast of Park City, Utah in Summit County, Utah (Figure 1). Although surface water concentrations in Silver Creek are typically less than 1 mg/l, groundwater concentrations have been measured as high as 85 mg/l in a near neutral pH environment. The elevated zinc concentrations in groundwater result from several factors including: (1) dissolution of zinc from tailings exposed at the surface and within the alluvium, (2) oxidizing conditions created by surface/ground-water exchange, and (3) ideal geochemical conditions for the dissolution of zinc-containing minerals. These ideal conditions include readily soluble minerals, available anions for complexation, and lack of available surface adsorption sites.

Jan 1, 2005

By K. Viking

This article deals with some of the civil engineering related problems to be encountered when offshore wind energy projects transform from prototype offshore wind energy converter farms, developed and installed during the 1990's, to commercial farms that's currently planned to be built. The offshore wind energy converter (OWEC) installations encounter a wide range of problems, only partial of these are geotechnical. In Europe both onshore and offshore wind farms have, from a historical point of view, usually been founded by using the monopole technique, installed with traditional impact hammers, or by using gravitational foundations. However, the rapid development of bigger turbines and larger wind farms, together with increasing considerations of fatigue aspects, has lead to financial benefits of developing and exploring other foundation techniques. This paper reviews some Scandinavian experiences regarding critical components of the design phase in relation to connecting the superstructure to the ground, and some of the main considerations of how the loads applied to the structure are transferred to the surrounding soil. Keywords: Offshore Wind Turbines, Wind Farms, Foundation, Pile, Gravity Structures

Jan 1, 2005

By Vicki Seppala

Phelps Dodge Mining Company operates some of the world’s largest open pit mines. Safely mining in these deep pits requires the commitment to a proactive integrated slope management process. The slope management process also includes the continued look for improved slope design, construction, and maintenance of slope faces. This paper discusses integration of such technology as electronic programmable detonators, 3D imaging using ground-based LiDAR scans, and reflectorless slope monitoring systems in a slope management program.

Jan 1, 2005

By M. van Schoor

The bulk of the world?s platinum production originates from the Merensky and UG2 reefs within the Bushveld Complex, South Africa. Both the Merensky and UG2 reefs are disrupted by faults, dykes, potholes and iron-rich ultramafic pegmatite bodies (IRUPs)?features that impact negatively on production, planning and safety. It is therefore advantageous to know of their presence and geometry ahead of mining. To date, no geophysical technique has been successfully applied to the routine mapping of mine-scale potholes and IRUPs. These disruptive features may vary from a few metres to several tens of metres in diameter. In this paper the applicability of in-mine electrical resistance tomography (ERT) to map potholes and other disruptions to the continuity of the Merensky and UG2 reefs ahead of mining is demonstrated using two case studies.

Jan 1, 2005

By Luciano R. G. Santos

Keywords: biosorption, cadmium, copper, biomass, spent zeolite. The majority of the industrial activities produce some kind of solid wastes. In this work two industrial residues (spent zeolite and wood sawdust) were chemically modified to increase their heavy metals sorption capacities. Manilkara longifolia (a Brazilian plant known as parajú) sawdust was first treated with NaOH and modified with different citric acid concentrations (0.6-1.2 mol/L) at 120°C, for 90 min. Infrared spectroscopy confirmed the presence of carboxylate groups in the wood structure as result of their mixing. Similarly, spent zeolites were also submitted to a chemical treatment (NaOH) to remove carbon deposited during oil cracking and to recover its sorption capacity. Batch experiments carried out at ambient temperature showed that both materials present sorption capacity for copper and cadmium comparable to weak acid ion exchange resins. A maximum of 78 mg-Cd/g and 59.7 mg-Cu/g as well as 29.9 mg-Cd/g and 14.6 mg-Cu/g were observed for the sawdust and the zeolite, respectively. The results were modeled according to the Freundlich and Langmuir equilibrium isotherms and compared with results of other studies.

Jan 1, 2005

By G. K. Quainoo

In the automotive industry, the awareness to meet Corporate Average Fuel Efficiency (CAFE) standards has evolved the need to reduce vehicular weight in new automobile designs, with the overall goal of reducing gas emissions into the atmosphere (Kyoto protocol), One efficient method has been to use lighter materials such as aluminum in outer body panels, Heat treatable AA6111 is one of the materials employed due to its unique combination of formability, paint bake strengthening and superior corrosion resistance characteristics, Researchers have applied various thermo-mechanical processes on 6000 series aluminum alloys and have found an improvement in the mechanical properties of these alloys, For a formed and painted automobile panel, the final mechanical properties involve a combination of strength components arising from cold work, strain aging and precipitation minus recovery. In this study, the evolution of microstructure resulting from the interaction of cold work and precipitation in AA6111 has been studied by means of transmission electron microscopy (TEM) after subjecting samples to various heat treatments, tensile testing and differential scanning calorimetry (DSC), This has been done to understand the evolution of microstructure and its influence on the properties of the alloy, The results show a considerable improvement in strength with a corresponding increase in strengthening precipitates with increasing level of cold work in the alloy. DSC results following the application of various levels of cold work also show acceleration in the precipitate phase formation, as precipitates are observed to form at lower temperatures, with increasing level of cold work/

Jan 1, 2005

By M Harris, C Goodall, B Knopjes

The objective of this work was to investigate the effect of milling and flotation circuit configuration on flotation performance of platinum-bearing ore from the UG2 reef of the Bushveld Igneous Complex in South Africa. Pilot plant trials were conducted at Lonmin Platinum using a highly automated pilot plant (a floatability characterisation test rig or FCTR), with a pilot ball mill, a stirred media detritor and an ISA mill. Different milling and flotation configurations were tested, without changing the overall grind size distribution or flotation residence time from one circuit to the next. Results from the pilot plant tests indicate that staged grinding, with intermediate flotation stages, can achieve significant performance benefits in comparison to a single grind-float circuit, for an equivalent overall grind and flotation residence time. These findings are explored qualitatively, in terms of the recovery and transportation of fast, slow and non-floating platinum-bearing particles through the various milling and flotation stages, and an optimum strategy for the separation of this type of ore is explored and discussed.

Jan 1, 2005

By Michael Kelly

Inertial navigation technology has, for the first time, allowed the position of a longwall shearer to be mapped in three dimensions. Following the success of the technology in highwall mining and successful trials on a longwall face, the Australian Coal Association Research Program (ACARP) commissioned a three year "Landmark" project that aimed to advance longwall automation to the level of "on-face observation" by the end of 2004. This project has been completed with the following successful technical outcomes: Automatic face alignment was achieved, using an inertial navigation-based sensor on the shearer, to accurately measure face geometry and feedback signals used to move OEM (Original Equipment Manufacturer) roof supports. Operational on-line measurement of creep with creep information incorporated into face alignment corrections. Inertial Navigation System (INS)-based enhanced horizon control was bench-tested. Operational broadband communications system to shearer using wireless Ethernet on a commercial-product basis. Acquisition of located coal-face features for use in thermal infrared-based horizon control. Automated Longwall Information System (LIS) developed which integrates information from multiple systems and sensors and provides high quality visualisation and control interfaces. Automatic roadway and face convergence monitoring tools successfully tested. Condition monitoring tools developed and demonstrated for improved face reliability. This paper summarises the outcomes of the project and describes the work being undertaken for the 2 year Landmark Extension project approved in April 2005. Consistent with the conference theme, the paper focuses on the ground control aspects of the project.

Jan 1, 2005

By S. Southall, F. McCaffrey, F. Stober, M. Darini

Electrode Columns are commonly used in electric furnaces to deliver current and regulate furnace power to the smelting or melting process. Hatch has developed an innovative patent-pending system for lowering ("slipping") and/or raising ("back-slipping") the electrodes through an electrode column, without requiring the release of any clamping devices. All clamping forces are applied by springs. Unlike systems employing hydraulically applied clamping forces, (e.g., water bladders) the spring system is failsafe. Its inherent simplicity virtually eliminates the need for maintenance. The Hatch system is particularly applicable to Soderberg electrodes, and comprises two axially movable slipping clamps and a stationary power clamp, each of which apply a distributed, radial clamping force to the electrode. The magnitudes of the slipping sleeves' clamping forces and sequencing of their axial movements are selected such that the slipping clamps, in conjunction with the weight of the electrode, provide slipping or back slipping without release of any clamping force.

Jan 1, 2005

By Felicity Lloyd, Stuart Kearns, Roger McLimans

The metamorphic terrane of southwestern India is a geological environment containing ilmenite source-rocks, transport drainage systems, and resultant beach sand deposits that contain altered ilmenites greater than 60wt% TiO2. As such, this environment provides a geological laboratory, from source to deposit, for the investigation of ilmenite origin, alteration, and geochemical character. Ilmenite samples from potential source rocks, river sands, and beach sands all show degrees of alteration and a variety of alteration textures (iron leaching) producing leucoxene (here defined as >70 <90wt% TiO2) and progressing to rutile (here defined as >90wt% TiO2). Distinct alteration textures are specific to different source rocks and are used together with trace element geochemistry as provenance criteria. Ilmenites are classified on the basis of their trace element content. In India, the ilmenites are classified principally according to the Mg, Nb, and Mn content and this signature defines potential source rocks, even where the ilmenite is altered to a TiO2 content of 70wt%. The trace element data may fingerprint source rocks whose ilmenite is more prone to iron leaching and that criterion has application in exploration for higher-grade ilmenites.

Jan 1, 2005

By E. De Souza, J. F. Archibald

"Many underground mines use cemented backfill to mitigate environmental effects associated with tailings disposal. The large energy needs associated with mine backfilling and cement production operations create significant CO2 and Greenhouse Gas Emissions. This paper introduces post-consumer glass as an alternate, equally effective and lower cost binder agent strategy for cement in backfill that may be implemented to assist in reducing solid waste production, lowering energy costs, and restricting Greenhouse Gas Emissions. Extensive engineering testing, consisting of pipe flow loop tests and strength tests, has been implemented in order to demonstrate the technical feasibility of process integration within industry. An economic analysis has demonstrated that glass is competitive in cost relative to cement and a socioeconomic study has further indicated that the utilization of glass in mine backfill would create a new market for waste glass that requires less processing and reduces costs."

Jan 1, 2005

By S. Hamilton

Borates are essential to life, and to many products that are essential to an acceptable standard of living. They occur naturally in seawater at an average concentration of five milligrams of boron per liter. Fresh water lakes, rivers, streams and ground water generally have concentrations of about one milligram boron per liter. Borates are also present in soil at concentrations ranging from 0.1 to three milligrams of boron per kilogram. Because most of that boron is locked into insoluble minerals, clay or organic matter, boron deficiency is more widespread than boron enrichment. Borates evaporate into the atmosphere from seawater, rain, snow and hot springs. In rain and snow, natural boron concentrations range from 0.002 and 0.1 milligrams boron per liter. All told, boron moves through the atmosphere at a rate of 5 Mt to 7 Mt/a (5.5 million to 7.7 million stpy).

Jan 1, 2005

By A E. C Peres, J D. Donda

With the aim of producing a concentrate with silica content lower than 1.0 per cent SiO2, laboratory experiments were conducted using a sample of the final concentrate from the Samarco iron ore flotation plant (mechanical cells circuit). The sample contained 3.08 per cent SiO2. This sample was split in two size ranges: >105 ¦m and 2. The >105 ¦m fraction, representing 23.3 per cent of the initial mass, was re-ground to 100 per cent 2 content were obtained. Considering the mass proportions of the two size fractions, the calculated silica content of the combined concentrate was 0.68 per cent, which is considered satisfactory for the objective of this investigation. The major reasons for the higher (0.90 per cent) silica content of the concentrate from the coarse fraction are the presence of silicon in the lattice of goethite and the presence of residual silicious slimes in the pores of porous hematite.

Jan 1, 2005

By Georgene Renner, William R. Yernberg, Steve Kral

ABB offers complete electrical revamps of mining shovels with ac or dc drives, drive control, frequency converters with insular gate bi-polar transistor technology, intelligent control packages and visualization. Many of the world’s shovel excavators and draglines (walking excavators) were built in the1980s. After 15 to 20 years of round-the clock operation in openpit mines, these machines start to feel their age. Electrical parts are particularly vulnerable. Their performance deteriorates and availability and productivity fall. Even with regular ser-vice and maintenance, a machine of this age will accumulate 400 hours of unscheduled downtime a year. The need for a replacement becomes pressing, but the expense is often prohibitive.

Jan 1, 2005

By Zach Ahinga, Mike McRae, Dave Hopkins, Steve Klein

The San Vicente Pipeline project involves the construction of an 8-1/2 foot diameter water pipeline in an 11 mile long tunnel in San Diego, California. The tunnel will be excavated in extremely variable geologic conditions consisting of strong granitic and metamorphic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. This paper discusses the challenging geologic conditions and some of the key design evaluations for the project. Currently design work for the project has been completed and construction will be underway by mid-2005.

Jan 1, 2005