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By D. Vavadakis

Abandoned bauxite surface mines in the Parnassos area may be rehabilitated using bauxite residues as filler. The objective of this study was to estimate the percentage of precipitation that may infiltrate through the bauxite residues to the lower geological formations when they are disposed off in mine open pits. Two scenarios were investigated simulating: a) available field tests, and b) a demonstration test that was planned to be performed in an abandoned open pit close to the Aluminium of Greece plant. It was indicated that the annual infiltration from bauxite residues disposed off in the demonstration test for the most probable scenario is very low, equal to 13.17mm corresponding to 3.1% of the annual precipitation. Furthermore, it was estimated that the annual percolation from the field tests is approximately 4.4%, very close to the infiltration values measured in the field tests for the same period.

Jan 1, 2006

The Wellington Dam catchment has high value water, agriculture and coal and power generating resources. These conflicting land uses are managed through consultation and regulation. The Wellington Dam catchment is unique in that the Collie Coal Basin is located almost to the edge of the dam and has coal mining and power generation as its primary land use. Currently the dam is only used for irrigation due to its high salinity. The State Government has committed to reduce the damÆs salt levels to below 600 mg/L by 2015 so that it can be considered for public drinking water supply. The coal industry in conjunction with the community and State Government has worked together to enhance the water quality within the Wellington Dam to maximise its value and use by using mine dewater for industry, diverting saline Collie River flows, providing environmental (social) flows and enhancing water quality of mine voids to encourage new industry to the Collie Region. Both surface and groundwater in the coal basin are generally fresh, whereas the salinity in the Collie River East Branch generally ranges between 3000 to 20 000 mg/L and 1700 to 10 000 mg/L in the South Branch. Mine dewatering is currently two to three times greater than the recharge to the coal basin. As a result, all mine dewater is sent to power stations in the area, with excess discharged into drainage lines which flow into the South Branch of the Collie River. To maintain environmental and social flows some groundwater is also pumped to the South and East Branches of the Collie River during summer months. Completed mine voids are used for recreation and options for aquaculture are promising. However, handback criteria are yet to be finalised.

Jan 1, 2006

The mineralogy of the platinum group metals is fairly complex, and it is therefore not surprising that the different minerals have variable responses to metallurgical processes, in particular, flotation and leaching. The PLATSOL® leach process was developed to extract simultaneously base metals, gold and platinum group metals from various materials. Extensive research has indicated that most PGM?s were amenable to the PLATSOL process, with the notable exception of cooperite PtS. Further work showed that a thermal pretreatment at 500-700ºC transformed the structure of the cooperite and similar refractory minerals (Pt,Pd)S into Pt metal and Pt-Pd alloys that responded well to the PLATSOL® process. Examples are presented of the mineralogy of PGM concentrates as produced, in the residue from the PLATSOL® leach and after thermal pretreatment.

Jan 1, 2006

By K. Kavouridis

On 30 April 2004, a large scale slope failure incident occurred at the external waste dump facility of the South Field Mine, in the Western Macedonia Lignite Center, Greece. This landslide involved the mobilization of waste overburden material (that was continuously deposited for the last 20 years) in the order of 40 Mm3, while the material that moved outside the boundaries of the waste dump was in the order of 3 Mm3. The factors that led to failure as well as the procedures and measures taken in order to stabilize the failure and resume normal operations at the South Field Mine are presented and discussed. Emphasis is given to the impact on mine operations and the cost related to resuming of normal production operation as well as to implementing important modifications and improvements of the materials handling system.

Jan 1, 2006

Iron control and iron residue management and disposal are significant issues in all zinc production processes. This paper briefly reviews the most important primary zinc production routes and discusses the challenges posed by iron control in each of them. The technologies and strategies that have proven successful in controlling and managing iron are discussed. SNC-Lavalin's experience in designing and commissioning zinc plants provides a unique perspective from which to review this aspect of zinc production.

Jan 1, 2006

By Guo-Sen Zhu

Research on the formation mechanism and control of corner transverse cracks was carried out. The optical microscope and SEM were applied to analyze the characteristics of cracks. It is found that the cracks occur at the relatively lower temperature due to unbending strain and have almost nothing to do with the mold cooling and powder. The keys to prevent corner transverse cracks are to optimize the corner temperature of slab and maintain the good state of casting machine. Increasing casting speed and decreasing the cooling water flux at the corner in the unbending segments, resulting in mild cooling, were applied during investigation to control corner temperature above the upper limit temperature of the No.3 brittle zone of Nb-contained steel tested by Gleeble-1500 system. As a result, corner transverse cracks were minimized, but centerline segregation got worse. And then increasing the cooling water flux at the corner (intensive cooling) was applied to make corner temperature below the lower limit temperature of the No.3 brittle zone. Great diminution of both corner transverse cracks and centerline segregation was achieved finally.

Jan 1, 2006

By A. Le Kouby

We present in this paper the results of a parametric study carried out in a calibration chamber on instrumented model piles. The aim is to point out group effect on piles within a group through their resulting shaft friction and tip resistance. The methodology relies on the study of the influence of adjacent piles on a "reference" pile. The soil used is a silica sand (Fontainebleau sand). The influence of parameters like pile spacing, number of piles and installation order are evaluated. The results show a positive effect on shaft friction of the group effect and a negative effect on tip resistance. Efficiency factors are defined in order to have a better view on the parameters influencing the response of the pile within a group.

Jan 1, 2006

This presentation is a 20 minute snippet of my professional career, and my progression in the mining industry, from a lazy uni student to an up-and-coming blast engineer in the middle of a mining boom.My name is Daniel Hepburn and I am a blasting engineer for Orica Mining Services. I graduated from Royal Melbourne Institute of Technology (RMIT), in Melbourne in 2003. I completed both of my final year projects with Orica Quarry Services and was offered an assistant shotfiring job, which I accepted and worked for eight months. Having missed the cut-off date for the Orica graduate program, I planned to work with Quarry Services until the following year where I hoped my marks and the experiences I had gained would secure a graduate position. I didnÆt have to wait long, as in August of that year, I was offered (and I accepted) a graduate position in Perth as a technical services engineer for Orica Mining Services. The Orica graduate program is based over two years, and consists of real roles from day one; however, there is also opportunity to fast track the program for high performers. There is a structured rotation, from site to site, interstate or even international if you are so inclined. This includes the backpacker program, which allows graduates to experience the Orica culture in countries of their choice. There are also opportunities to try cross-functional roles in the different Market segments within Orica. I was lucky in that I knew what I wanted to do and where I wanted to work, so I stayed in Perth for my entire graduate program. I was also lucky enough to be fast tracked and finished my graduate program in 15 months. At the end of 2005 I accepted a position as an open cut blasting engineer based in Perth and even in such a short period of time I have already completed a number of major accomplishments. Some of these accomplishments are described below. This paper is available as a PowerPoint presentation only.

Jan 1, 2006

By Tiebao Yang

In high pressure die casting processes, a die plays a critical role in removing heat from the molten metal during the cavity filling and solidification stages. Proper control of die temperature is essential for producing superior quality components and yielding high production rates. This paper proposes a local temperature control scheme for die thermal management based on a computerized intelligent real-time monitoring and control system (IRMCS). In this scheme, cooling water lines are controlled by a pump and solenoid valves. A controller is designed according to the law of die temperature fluctuations. The results obtained from the experiments carried out on a laboratory die casting process simulator indicate that the controller can limit the local die insert temperatures in a given band. Hence, the desired thermal pattern of the die insert becomes achievable.

Jan 1, 2006

By R N. Robson, A B. Christie, I J. Graham

Strategy development by the minerals industry identified the fragmented management of mineral resources as a significant impediment to the discovery and development of New Zealand Æs mineral resources. The total gross value of New Zealand Æs potential resources of coal and minerals is estimated at about $400 billion, but their potential value is not being realised. The management of minerals is now largely under the control of 86 local authorities (regional and district councils) and the lack of recognition of the significance of the sector has lead to inconsistencies in the way minerals are managed. The industry strategy influenced science funding for minerals, with the result that the 'mineral wealth' component now includes research on making better use of resource data in minerals management. Initially this research has targeted Otago and Northland regions where a number of initiatives are now in progress.   In Otago the Regional Council has budgeted to contribute $1 million towards a regional geophysical survey to advance mineral exploration and the management of subsurface resources in the region, to work cooperatively towards improving public awareness of the significance of minerals to regional economic activity, and to better coordinate policy-making for minerals at regional and district levels.   Crown Minerals, and the Far North and Whangarei district councils are considering providing funding support for an economic study of the mineral potential of Northland, building on a mineral resource assessment undertaken by GNS Science. Enterprise Northland is adding minerals to their list of potential growth sectors, and is supporting the operation of a Northland region minerals focus group.   Regional development agencies and local authorities have shown that they are willing to include mineral resources in their development strategies and to provide for them in policies and plans when supplied with information and assisted with technical support.

Jan 1, 2006

By E. S. Geskin

New material processing tools should be developed and reduced to the practice in order to meet the challenges facing the contemporary material production industry, One of such potentially important tools is supersonic liquid projectiles. It was shown that at the speed of 1500-1750 m/s the water projectile are able to demolish reinforced concrete plates, forge, to pierce and weld metals, to destroy with no explosion non dischargeable mines, etc. These projectiles are generated by simple, low cost launchers run. It is obvious that these projectiles can be applied to the ore mining and comminution. Thermodynamic considerations show feasibility of the use of these projectiles also for smelting, refining and forming. The presented paper discusses the results of the experimental study of supersonic liquid projectiles as well their potential metallurgical applications.

Jan 1, 2006

By P. Bakke

Following extensive R&D efforts, Hydro Magnesium has launched a new alloy series with remarkable combinations of properties. The AE alloy family is based on additions of aluminium and rare earth elements to control mechanical properties, including elevated temperature creep strength. By combining these alloying elements with manganese additions, high purity alloys with outstanding corrosion performance are defined. A basic philosophy behind the developments has been to simultaneously approach all the critical issues related to developing a commercial material. Apart from the obvious requirements for material properties, the critical issues relate to die casting performance, as well as alloy production, recycling and environmental compatibility. Some of the important elements related to alloy production and recycling are addressed in the present paper.

Jan 1, 2006

By P J. Grobler

The current commodity boom is depleting the ore bodies at a rate not seen in the past. As the existing ore bodies get depleted, only the more inferior bodies are left for exploitation. This places an emphasis on beneficiation to upgrade the lower grade ore to high-grade feedstock for downstream processes. This paper discusses the role of dense medium separation in this quest for high-grade feedstock for the future. It covers the production and utilization of ferrosilicon and gives a future perspective of the technology. It concludes about the way ahead and the challenges facing the processing fraternity and mining industry.

Jan 1, 2006

By Carole L. B. Mitchell

The increased use of micropiles and soil nailing presents a growing database of verification and sacrificial load test data. In Washington State, the use of micropiles is becoming common, and soil nails are now almost as widely used as tiebacks; yet the state of the practice in understanding load transfer rates has not improved. This research compiles load test data for micropiles and soil nails from Shannon & Wilson?s records in the Puget Sound region of Washington. Ultimate and maximum load transfer rates for design are correlated to geologic units and soil types found in the region. Variables such as pressure versus tremie grouting, hole diameter, soil density/consistency, and the presence of groundwater are compared to load transfer rates for similar geologic units and soil types. Results are also compared to published PTI, AASHTO, and FHWA guidelines. Our results indicate that published ranges may be conservative for some soil types in the Puget Sound region, especially for micropiles. Performing verification tests to failure instead of typical verification or performance tests is needed to improve correlations and provide less conservative design load transfer rates.

Jan 1, 2006

By D. A. Beattie

Talc is a commonly encountered gangue mineral in metal sulfide flotation. Talc is naturally hydrophobic, resulting in high recoveries if polymeric depressants are not used to specifically reject this MgO containing mineral. We have studied the adsorption of a selection of polymers onto talc using a variety of techniques. Adsorption isotherms have been determined using ex situ depletion techniques and in situ ATR-FTIR spectroscopy has been used to determine adsorption kinetics. Adsorbed layer thicknesses have been determined for the polymers on cleaved talc surfaces using the AFM. The effect of the adsorbed polymer layer on the properties of the talc surface has been quantified through contact angle measurements and single mineral flotation tests. Distinct correlations are observed between the adsorbed layer properties and the flotation performance of the polymers. These observations are discussed with reference to the bubble-particle attachment process and the molecular structure of the polymers.

Jan 1, 2006

The term æindustrial mineralsÆ covers a wide range of minerals, from diamonds to silica sand, which are fundamental to the sustainability of a wide range of industries, from drilling mud to autocatalysts. The paper commences with an overview of the industrial minerals markets, with particular reference to the characteristics that impact on the development of a successful marketing strategy. This is followed by the identification of the steps to be taken in the negotiation and execution of an industrial minerals sales contract, from identification of the appropriate product through negotiation of the contract to ongoing customer relations. An understanding of your customerÆs business is fundamental to a mutually successful long-term relationship with that customer. The paper concludes with an overview of the techniques and approaches through which such a relationship may be achieved and maintained.

Jan 1, 2006

By Yanping Xiao

In submerged-arc furnace (SAF) for smelting chromite ores into ferrochrome, there exist large temperature gradients and wide distributions of mineralogy and compositions in the furnace, due to the complexity of feed structure and electrical-thermal-chemical interactions. This leads to various zones in the furnace and thus different reaction mechanisms. In the present paper, the behaviour of chromium in the submerged arc furnace is discussed in various reaction zones, including solid state chromite reduction in the packed bed zone, chromite dissolution and reactions in the smelting and coke bed zone, and recovering chromium from slag to metal. In the gas-solid reaction zone, the reaction mechanism is discussed based on the experimental observations and analysis. In the smelting zone, the behaviour of partially reduced chromite and slag formation are analyzed based on the information in literature. The slag in FeCr process contains mainly Al2O3, MgO, SiO2, CaO and CrOx, featured by chromium with both divalent and trivalent oxidation state, which plays an important role for chromium recovery into metal. The factors influencing the slag and metal interfacial reactions and the chromium recovery are addressed.

Jan 1, 2006

By John W. M. Lambert

This paper describes the execution and the results of a new method to seal off leaks in water retaining constructions. The new method, called BioSealing is based on activating the bacteries, present in soil and groundwater. The method was tested under field conditions in 2004 and applied at the HSL aqueduct of the 'Ringvaart Haarlemmermeer' in 2005.

Jan 1, 2006

By W. J. Schlitt

The development of forced aeration as an approach to enhancing copper sulfide leaching is traced from its earliest development up to present day operations using this technology. Both large-scale field tests and commercial operations are covered. The historical portion is preceded by an introductory discussion of the role of air (oxygen) in sulfide leaching. Sufficient aeration may be achieved via naturally induced convective airflow. However, cases are identified where this is insufficient, leading to retardation of the sulfide leach rate. For these situations, forced aeration may be beneficial. The historical portion of the paper focuses on the major field tests that have been conducted in Montana, Nevada and Utah, along with commercial operations in the United States, Australia, Chile and Peru. The paper concludes with some general comments about the applicability of forced aeration, which are based on the information developed to-date.

Jan 1, 2006

By Helen S. W. Chow

The use of piled raft foundations for tall buildings has been increasing in this decade as it is an economical alternative to conventional piled foundations. Piled rafts are composite structures comprised of the piles, raft and soil and so soil-structure interaction is important in computing the behaviour of the foundation. In this paper, the behaviour of piled rafts subjected to non-uniform loadings will be examined where the raft is supported by piles of different lengths. Finite layer techniques are used for the analysis of the horizontally layered soils and finite element techniques are used for the analysis of the raft and piles. This method accounts for the soil-structure interaction and the lateral resistance of the soil on the piles and raft. Results provided from the present method are compared with the results of a full 3D finite element analysis.

Jan 1, 2006