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By Dolf Gielen

This paper discusses the results of a Western European energy and materials systems engineering study that analyses the impact of greenhouse gas (GHG) emission reduction on the future of the steel and aluminum industry. he technology selection will be significantly affected by future CO2 policies. The avail- ability of C02 removal and storage technology and the social acceptance of this strategy for GHG emission reduction is of key importance for the strategy selection. The use of coal based smelting reduction technologies is optimal in case of weak C02 policies or in case of strong C02 policies and low CO2 removal and storage costs. The selection of CCF or Corex technology depends on the penalty regime. However, if C02 removal proves to be problematic, CCF development fails and strong C02 policies are introduced, the gas based DRI production processes will become more attractive. In both cases, the energy efficiency of the iron and steel industry will further increase in the next decades. The impact of GHG emission reduction on aluminum prices and aluminum use can be significant. However contrary to common notions the aluminum production will be positively affected by GHG emission reduction, notwithstanding the currently high emissions in aluminum production. A combination of emission mitigation in production and significant GHG emission reduction effects further down the product chain cause this effect. A significant potential exists for improved materials efficiency. This potential is generally neglected in energy efficiency and CO2 reduction studies. However improved steel qualities are of similar importance for C02 emission reduction as increased energy efficiency. It remains to see if this potential will be used to its full extent in the next decades. Model calculations indicate that the impact of C02 policies on the competition with other materials will be limited. Greenhouse gas emission mitigation will have much more impact on materials production and waste handling than on materials consumption.

Jan 1, 1999

By John Frostiak, Lloyd Buckingham, Kenneth G. Thomas, Luis Wilson

"The El Indio roasting facility associated with El Indio Mine in Central Chile has operated since 1981. It is a facility developed to remove arsenic and antimony from gold bearing enargite/pyrite flotation concentrates.The three installed roasters are Nichols Herreschoff units each with 14 hearths and measuring 4.85 metres diameter. Hearths are rabbled by central shaft driven rabble arms. Product is progressively heated to 750°C under neutral to reducing atmospheric conditions to drive off labile sulphur, arsenic and antimony.Ancillary equipment includes skip hoist feed arrangements, water cooled screw conveyors for transporting and cooling calcine, gas cyclones, post combustion chambers, heat exchangers, electrostatic precipitators, bag houses, gas scrubbers and packaging facilities .Operating practices, history, mineralogy and results are reviewed. The improvements to arsenic and antimony extraction, ambiental conditions and environmental achievements are discussed.INTRODUCTIONHistoryThe El Indio property lies in the El Indio belt, a copper, gold and silver area approximately 175 km long by 10 km wide. The property is located in the Andes Mountains of the central part of Chile at latitude 30"" South and 160 km from the sea-side city of La Serena. Plant location is at 3850 meters above sea level.The property currently consists of two underground mines feeding the El Indio plant and an open pit feeding the newer Tambo leach plant. The property has been controlled by a succession of owners (St. Joe Minerals, Fluor, Bond Gold International and Lac Minerals Ltd.) before acquisition by Barrick Gold Corporation in 1994."

Jan 1, 1999

By Weber P, Sneyd S

The total world steel production in 1998 amounted to approximately 780 000 000 t. The share of electric steelmaking was in the range of 35 per cent and is expected to increase further to over 40 per cent of the world's production within the next ten years. As electric steelmaking is primarily based on the use of scrap and as it is progressing more and more into higher steel grades the need for low-residual metallics will become increasingly important. Consequently, the demand for scrap substitute material will increase, reflected in the world wide spate of interest for DRI (Direct Reduced Iron) and HBI (Hot Briquetted Iron). The increased significance of DRI/HBI as a substitute for steel scrap has obviously emanated also from its comparatively lower and more predictable costs per ton and definable chemistry. In 1998 already 37 million tons of DRI/HBI were globally produced.

Jan 1, 1999

By Fogarty J. G H

Ausmelt Technology has a unique capability of removing the impurities, phosphorus and sulphur, from the feed materials to the process. Sulphur is removed to the gas phase almost completely because of the interactions of ore and coal in the reaction region at the top surface of the slag bath. Phosphorus is removed to the slag phase, with both basic and higher, controlled iron oxide levels in slag being achieved in the process. The significance of these features of the process relate to the production of pig iron with very low levels of these impurities for the further processing to steel, and to the treatment of high phosphorus and high sulphur raw materials. The marketability of pig iron and the raw materials are discussed in relation to this feature of Auslron.

Jan 1, 1999

By D. Kump

The Bullfrog Mine is an underground gold mine that uses the underhand-cut-and-fill mining method. The portal was established on June 18, 1991. Mining is expected to be completed by the summer of 1999. This paper starts by discussing what it took to get from nothing to 2000 tons-per-day backfill, and ends with a hindsight commentary on things that did and did not help.

Jan 1, 1999

By A J. Burchell

The introduction reviews the tunnelling carried out in Singapore since the early 1980s. Between 1983 and 1990, Phases 1 and 2 of the mass rapid transit system were constructed. These included some 20 km of bored and cut and cover tunnels together with 18 underground stations. Some particular points of interest in this massive project are briefly commented upon. Reference is also made to other underground or underwater schemes undertaken during this period such as the proposed large caverns project and the submerged tunnel to Pulau Seraya. A description of the subsurface works, now under construction in Singapore, follows. This includes an all underground North-East railway line 20 km long with 16 stations. At a budget of US$ 3 billion, this is a major civil engineering undertaking. Another project is the extension of the railway to Changi Airport which involves 3.5 km of twin tube tunnelling together with a major underground station which is fully integrated into the airport terminals. An on-going program of further major railway extensions over the next 10 to 15 years is in place and an outline is given of some of the most important underground sectors. Other proposed projects such as the underground roads system and the deep level sewers are briefly described. Together they demonstrate the very significant volume of underground construction scheduled for the next century in Singapore.

Jan 1, 1999

By Chidchai Loyprasert, R. A. Stoehr

"A computer model has been developed to predict grain structures in alloys solidified under unidirectional flow using a combination of three techniques -- solution of the equations for flow of an incompressible fluid bounded by curved surfaces by the SOLA-SURF algorithm, calculation of heat flow by a finite difference method, and simulation of grain formation by a two-dimensional cellular automaton (CA) model. The changing rigid surface has been taken into account. Heterogeneous and homogeneous nucleation are considered, and the growth kinetics of a dendrite tip are evaluated by the Kurz-Giovanola-Trivedi (KGT) model. These calculations were applied to solidification of an Al-4.5% Cu alloy flowing over a chill on the bottom of a channel, a system for which experimental results were available. Using a variety of flow rates and superheats, agreement between the computed and experimental results were very good including transitions between columnar and equiaxed grains, the aspect ratio of the grains, and the inclination of the grains to the flow.IntroductionModeling of casting and solidification processes has developed over the years along two distinct tracks: (1.) modeling of macroscopic heat transfer and fluid flow for design purposes, and (2.) modeling of microscopic processes such as nucleation and growth in order to improve the scientific understanding of the phenomena involved. The present work is an attempt to combine the macroscopic and microscopic approaches for the solidification of an alloy flowing over a chill. The specific case chosen is that of an aluminum-4.5 % copper alloy flowing linearly over a water-cooled copper chill for which experimental results were available over a range of flow rates and superheats. For the macroscopic calculations, the SOLA-SURF algorithm for solution of the twodimensional fluid flow equations was combined with the finite difference method (FDM) for calculating heat transfer. For the microscopic calculations, heterogeneous and homogeneous nucleation were considered, and the growth kinetics at the dendrite tips were evaluated. The cellular automaton (CA) technique was used to apply the microscopic kinetics to the temperature and .flow conditions."

Jan 1, 1999

Maximizing margins in competitive markets demands superior productivity. Unfortunately, management systems developed early this century for other industries often drive counterproductive behaviors choking mining productivity. Many executives and managers waste valuable time and effort relying on simply training and communicating to improve managerial practices and attitudes. In covering practical human behaviour, the paper explains why this fails -and explains how to use systems to successfully drive improved managerial practices and attitudes. It highlights use of modern performance Measurement, Analysis and Reporting systems to drive behaviors and improve margins -without capital investment -and make executive and managerial work easier and more effective.

Jan 1, 1999

By Michael Cooper, Eric Konigsmann, A. Moerman

"A paste backfill plant and underground piping distribution system was commissioned at the Brunswick Mine in June, 1998. Concentrator tailings, composed mainly of pyrite and lesser amounts of silicate minerals with a P80 of 37um (45 YO-20 pm), are pumped to the backfill plant. The backfill plant uses conventional thickening and disc filtering to dewater the solids, which are then mixed with binder in twin screw mixers. The paste is discharged through a gob hopper and one of three boreholes by gravity. Approximately 65% of the concentrator tailings will be placed underground at full production. The remaining thickened tailings will be pumped to an existing impoundment area. Application of paste technology will completely replace the use of cemented rock fill in the mine by the end of 1998.The design capacity of the paste backfill plant is a total of 360 dmtph of cemented paste through two parallel production lines. The plant is highly instrumented and controlled via a hybrid Programmable Logic Controller (PLC-5) and Fisher ProVox Distributed Control System that is in communication with the property information highway. Video and audio signals from the underground system are carried to the surface plant via a leaky feeder communications/fiber optic system.The underground distribution system consists of a network of 200mm diameter boreholes and piping. There are approximately 3.5km of boreholes and 5.5km of piping in the system. To minimize pressures, the greatest piping length from any borehole is approximately 400m with all piping being open-ended. There are no valves in the entire paste distribution system.Construction of the plant, including installation of piping to and from the plant and preparation of the underground distribution system, was completed in less than one year from the time of management approval for the $M 22.3 project."

Jan 1, 1999

By Nathalie Neveux

For the first time, dehydrated ferrous sulfate was successfully used for the dry synthesis of potassium ferrate. In addition, ferrate ion is stabilized as a solid solution where hexavalent iron is partially substituted by S(V1) leading to a sulfato-ferrate having the following formula K2(Fe,S)04. This substance has an efficient life time of about six months. Ferrate ion is a powerful oxidant ( EO = 2.2V ), a bactericidal agent and possesses coagulant, flocculant properties. Its reduction generates nascent oxygen, hydroxyl groups and Fe(OH)3. Alkali metal ferrate is probably the future global agent for water treatment. Applications of this material in the field of urban and industrial effluents treatment have been investigated. Heavy metals cations such as Cu, Cd, Mn, Ni, Pb, Zn, ... were successfully removed. The results of sulfato-ferrate use for cyanide destruction, decrease in COD, soil, discoloration of pulp and paper effluents will be summarized.

Jan 1, 1999

By R. C. Berry

The Environmental Impact Statement (EIS) has become a routine requirement for mining operations on federal lands. A similar document is being required in developing countries. Baseline studies are needed prior to writing an EIS and these studies involve surface water, groundwater, air quality, and wildlife/ native plant evaluations. The required baseline hydrology and geochemical studies are often the most expensive and lengthy evaluations. This paper summarizes the hydrology and geochemical baseline studies required for .An EIS and presents suggested methods to expedite these studies and to shorten the time and the cost to complete the studies and the EIS.

Jan 1, 1999

Conditional simulation provides a model of the ore body that represents variability in the data. This can be used to determine the impact of various grade control and mining strategies. A number of transfer functions are discussed that assist in optimizing grade control sampling. The cost effectiveness of various drilling and trenching techniques are discussed. Modelling of the expected performance of a mill head grade sampler is investigated. Conclusions are drawn about the likely impact of various sampling techniques on the economic performance of an operation and about applying sampling theory to grade control sampling.

Jan 1, 1999

By S. Mathur

Oxide particles are commonly used as fillers in plastics, paper, rubber, etc. (particulate composites). The successful fabrication of such composites is dependent upon the adhesive strength of the filler particles to the matrix. The compatibility of the matrix and the filler particles is generally enhanced by the adsorption of surface modifiers such as surfactants and polymers at the particle-matrix interface. To develop a scientific basis for the selection of the appropriate modifiers it is necessary to understand their adsorption mechanisms. specifically, the adsorption of polymeric additives is attributed to a combination of chemical and electrostatic interactions, hydrogen bonding and van der Waals forces. Hydrogen bonding has been suggested to be the primary adsorption mechanism for nonionic polymers. However, a literature survey of the Poly(ethylene oxide) (PEO)-oxide system suggested that PEO, a nonionic polymer, was substrate specific. A systematic study was undertaken to investigate the adsorption mechanisms of PEO on oxide particles. It was determined that strong Bronsted acid sites on the surface interact with the ether oxygen, a Lewis base, of PEO to induce adsorption. In this work, characterization of PEO binding sites on oxides is reported and the mechanisms of PEO adsorption are discussed.

Jan 1, 1999

By S Porter

The Melbourne City Link Project is a privately funded road infrastructure project linking three significant existing freeways in the vicinity of the Central Business District. The State Government, through the Melbourne City Link Authority, has contracted Transurban to build, own and operate City Link for a concession period of 34 years before the road network is transferred to the State. Transurban has a contract with Transfield Obayashi Joint Venture (TOJV) to design and construct the works. The project is divided into the southern and western sections and the tunnel works comprised the significant component of the Southern Link. Outside of the cut and cover tunnels at the portals, the driven tunnels component was constructed by TOJV direct labour. TOJV subcontracted all design work to a joint venture of Hyder Consulting and CMPS&F (Hyder/CMP). The geology in the tunnel corridor and generally below the city of Melbourne is highly variable and constantly changing. The tunnels were driven, for the most part, in siltstone and sandstone of the Silurian age, but also intersected overlying basalts and clays. The Silurian bedrock is a fractured aquifer that is connected to overlying alluvial aquifers. Consequently, the construction of the tunnels was a complex engineering task. This paper details the operational relationships and procedures developed to deliver a design that was aligned to the construction constraints and delivered an end product that met all technical, quality, cost and program goals.

Jan 1, 1999

By Peter L. Dunn

With the advent of new high-strength magnetic materials, rare-earth magnetic separators have become more common place for processing heavy mineral sands. In many instances, rare-earth magnets have replaced conventional separators such as electromagnetic cross-belt and induced-roll type machines. This paper will present the results from a detailed test program developed to evaluate the performance of rare-earth drum and roll separators for processing heavy mineral sands. The effect of machine design parameters, such as magnetic element configuration and separator diameter, will be reviewed in light of these test results. The impact of basic operating parameters (i.e. feed rate and roll speed) on separation efficiency will also be presented.

Jan 1, 1999

By M. J. Virnig

A flowsheet for the recovery of nickel and cobalt from laterite ores has been developed which involves acid leaching followed by hydroxide precipitation of the metal values and then releaching of the hydroxide cake with ammonia. Investigations of the chemistry of extraction of nickel by LIX® 84-1 and a developmental reagent, XI-84-IT, along with the physical properties of the organic phases are described. Based on these investigations, suggestions with regard to design of a solvent extraction plant and operating conditions are made.

Jan 1, 1999

By Paul Cartwright

A rockbolted roadway risk assessment procedure has been developed specifically for the Parkgate seam at Thoresby Colliery by Rock Mechanics Technology and colliery engineers. The purpose of this assessment is to identify any areas of significant risk in relation to roof instability due to potential failure or overloading of the rockbolt support system. This allows appropriate additional support to be installed in sections of roadway considered to be at increased risk. The assessment of risk in rockbolted coal mine roadways, in terms of fall of material, has to be based on an understanding of the rock mass behaviour at that site. The development of an appropriate risk assessment system is therefore site specific. A consistent approach to developing such a system can, however, be applied by adopting the same general logic to each individual site. The use of risk assessment to categorise areas with increased risk of roof instability has been undertaken for four longwall panels at Thoresby. The procedures used for these assessments are discussed and the operational benefits examined. The approach successfully used at Thoresby has been developed into a routine tool to assist mine personnel in assessing areas of potential roof instability in rockbolted roadways and as a means of communicating the position of these areas to both supervisors and workmen. The system provides a rational and objective interpretation of the current underground conditions based upon a logical, consistent and structured approach.

Jan 1, 1999

By C. Villa Diniz

It is proposed that battery grade Mn02 can be produced directly from a manganese ore from Azul Mine in Brazil, by leaching with HCI to remove heavy metals selectively. We are working to find a way of selectively separating Cu, Ni, Co, Pb and Fe from the resulting acidic manganese chloride solution, to detoxify it and produce marketable chloride solution. Chelating ion exchange resins are proving more promising for this separation than solvent extraction with commercially available reagents. Results from batch and column ion exchange tests that characterize the behavior of copper, nickel, cobalt, lead and iron are reported.

Jan 1, 1999

By David Rees

Tomago Aluminium, a 400,OO tonnes per annum primary aluminium smelter in Australia, has installed Ozone for biological control of its process water. The system was designed in Australia by Ionics Watertec Engineering, whilst ANCO Australia monitors the water quality and provides technical support for the project. The motivation was initially to reduce operating costs, however investigations indicated that there were substantial environmental benefits to be achieved by the elimination of a part, or all of, the chemicals being used to control the system. Also the existing chemicals appeared to be losing their ability to control biological growth in the system, in particular, the legionella bacteria. Ozone water treatment commenced in January 1998 and after a short transition period has operated without chemical addition since. There appears to be no doubt that the biological control is effective, the clarity and purity of the water has improved and initial testing indicates that the corrosion control rate is acceptable, although some chemical corrosion control may be introduced after further testing around the total circuit to guarantee protection

Jan 1, 1999

By J. L. Cupp, R. C. Ford, B. R. Romig

The Climax Molybdenum Mine, located near Leadville, Colorado, is the site of a lengthy mining history spanning more than 80 years. In the 1960’s, extraction of molybdenum from oxide ore located adjacent to the massive molybdenite sulfide deposit resulted in the construction of an earthen core dam to impound fine-grained oxide tailing in the Eagle River Valley. Through recognized value of water storage and reclamation opportunities, a tailing removal project was initiated in 1993 to convert the impoundment facilities to a post-mining beneficial land use of developed water resources. An evaluation of the effect residual materials and lake dynamics would have on in-stream water quality was performed. Eagle Park Reservoir stands as a model for future reclamation efforts that involve water delivery to highly sensitive receiving waters. This paper provides a case study on project development, the evolution of water quality assessment, and the regulatory framework that contributed to this project’s success.

Jan 1, 1999