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By S McKnight, S Hall

Much of the research regarding the use of bacteria for the oxidation of sulfide minerals has been conducted using pure bacterial strains or synthetic minerals, often under ideal conditions, which does not reflect the conditions commonly encountered in commercially operating plants. This has also led to much conjecture as to the exact mechanism by which bacteria are able to enhance sulfide oxidation and as to which species of bacterial microflora are the most dominant. Recent advances in 16S rNA sequencing has confirmed that many of the bacterial species once thought to dominate commercial oxidation circuits were simply more willing to grow under the culturing conditions used and may only play a minor role in the oxidation process (Rawlings, 2002). Consequently this research will look at bacterial oxidation under conditions more reflective of commercial operations, focusing on the presence of organic carbonaceous material within a refractory sulfide orebody to be sourced from the Fosterville deposit of Perseverance Corporation Limited.

Jan 1, 2004

By Murray G

This paper outlines the processes involved in acid generation from sulphides and the key factors in identifying and predicting time dependent changes in the nature of acid mine drainage (AMD). The initial characteristics of mine water; whether drainage from exposed mining faces, runoff and seepage from waste dumps or seepage from process tailings; do not necessarily reflect the long term potential for AMD. The ultimate quality of mine drainage is a function of the interaction of many chemical, physical, biological and engineering (operational) factors. Techniques are available that can predict the qualitative nature of acid generation and mine drainage quality but accurate quantitative predictions are essentially impossible at the present time. As more and more mining operations exploit sulphide ore, the AMD and acid waste issue will become a. far greater concern. The significance of time dependent factors in the production of acid mine drainage-.is not just restricted to particuL.ar mine sites but needs to be recognised by the mining industry as a whole.

Jan 1, 1988

By Hendrix JL, Nelson JH

Three ores (sulfidic, oxidized and carbonaceous) were analyzed to determine the effects of leaching time, ore depth, and ore mineralogy on cyanide species concentration. NaCN solutions were percolated through opaque columns filled with milled ore. Column design made liquid sample collection possible from various depths at specific times. The concentrations of weak acid dissociable(WAD) and total cyanide, Fe(CN)63 , Fe(CN)64 , SCN , and Cu(CN)43 were determined for each sample. Extended percolation time led to increases in WAD cyanide concentra- tions and decreased SCN and Cu(CN)43 concentrations regardless of ore depth. WAD cyanide concentration decreased while Fe(CN)64 concentra- tion increased with ore depth. Highest concentrations of Fe(CN)64- SCN and Cu(CN)43 were found in the sulfidic ore, with expected low WAD cyanide concentrations. Lowest concentrations of Fe(CN)64 , SCN 3 and Cu(CN)4 were found in the oxidized ore. Intermediate concentra

Jan 1, 1988

By S Furman, M Caccetta, A Hacket, B McDonald, M A. Wells, D Lau

In 2004, the Western Australian Department of Industry and ResourcesÆ Burrup Rock Art Management Committee commissioned a number of independent scientific studies to evaluate the condition of rock art in the Burrup Peninsula near Karratha (Western Australia). These studies are evaluating the physico-chemical aspects of the effect of environmental modification on the visible appearance of the rock art. Because of the cultural significance of the sites, the research approach has been to employ non-destructive testing strategies and work in the field has progressed with respect for the importance of the area. This paper only reports the spectral mineralogy monitoring at each of the sites to evaluate whether changes in mineralogy are observed on rock surfaces. Reflectance spectroscopy is a non-destructive, in situ materials characterisation technique that provides information about the mineralogy. The minerals detected include haematite, kaolinite, chlorite, goethite, gibbsite and manganese oxides. Current results indicate that the surface mineralogy of the rock art has not changed in the last four years.

Jan 1, 2008

By Dawson RD

For the past 45 years, the casting of refined lead ingots by The Broken Hill Asso- ciated Smelters Pty. Ltd. (B.H.A,S,) at Port Pirie has been mainly by use of manually operated rotary casting wheels of Newnam design. This style of operation was quite satisfactory as far as standard of product was concerned, but was manually intensive and a relatively high cost operation. With most other large scale lead producers already using automated-casting equipment, an investigation which commenced in 1966, progressed through stages of enquiry, design and development until the present plant commenced trial operations in late 1973, and fully operative in late 1974. While certain features of the plant are sed on overseas practices the plant was signed and built within Australia to BRAS ecifications. As constructed it consists two almost identical casting lines each pable of producing 25 kg ingots at 25 tonnes r hour using straight line casting machines d automated stacking weighing and strapping

Jan 1, 1975

This paper discusses a number of examples of how environmental factors have been incorporated into the water management aspects of mining projects. One example is the Kingston Lignite Project in the South-East of South Australia where the most significant environmental issue was considered to be the effect of drawdown from mine dewatering and depressurization upon the use of groundwater. By proposing an alternative mining method - the use of floating dredges rather than a two-pass dragline method - drawdown effects would no longer be a concern. A second example is the Pine Creek Gold Mine in the Northern Territory. In this case the principal area of interest from an environmental viewpoint was water management - in particular effluent disposal, contaminated seepage from overburden and tailings, and project water supply. Through an integrated approach to the management of wastes and water the potential for water quality impairment was significantly reduced and external water supply requirements were also significantly reduced.

Jan 1, 1987

By Fengyan D

Removing the interference of latter events, the data of geophysical (such as gravity and aeromagnetic) anomalies may indicate whether the mobile belt exist and whether the adjacent terrains of the mobile belt originally belong to one single unit. The petrotectonic assemblage can provide informations about the tectonic setting where it was generated from. The structural style can exhibit the kinetic and kinematic processes. The form of ancient isogeotherm may reflect the ancient geothermal regime which is related to the tectonic mechanism. In general, the early Precambrian terrains suffered polymetamorphism and multiple structural deformation. The researches must be carried out for the distribution of paleogeotharm and m.tamo'phic facies and zones on the basis of recovering the early structural style with structural analysis method; then a relatively correct conclusion may be geined on the ancient geothermal regime. This method can be known as "Ancient Thermotectonic Analysis". Through the sythetical research, a real knowlege about the tectonic setting of early Precambrian mobile belt can be obtained.

Jan 1, 1990

The planning, design and construction of a service tunnel, under a major arterial road between two hospitals are described. The multiple uses of the tunnel combine to provide a favourable cost-benefit ratio for the tunnel as part of a rationalisation of services between hospitals. The driven tunnel provides economic, program and approval advantages over that of a cut and cover construction. The cross sectional shape of the tunnel was determined during feasibility studies by the degree of weathering of the Silurian mud- stones, the shallow cover and the proposed excavation equipment as well as the functional requirements. The site investigations covering geotechnical, building, noise and level surveys provided input to the design documentation and construction phases. Monitoring of settlement levels and primary support stresses during early construction stages confirmed the adequacy of the proposed tunnelling methods and support to be used adjacent to the major building foundations. The 140 metre long tunnel was success- fully completed in April 1980 at a cost of $650,000.

Jan 1, 1981

The Kanowna Belle deposit was discovered in 1990 following encouraging assays from soil sampling and RAB drilling. At the end of September 1993, diamond drilling had been completed to a vertical depth of 1,000 metres and a resource of 22 million tonnes grading 5.73 grams of gold per tonne containing a million ounces of gold had been defined. The deposit remains open at depth. Pre-production mining for the open pit began in November 1992, construction of the oxide treatment plant began in January 1993 and the first gold was poured in September 1993. Sulphide ore roasting commenced in December 1994 and the underground mine development commenced in July 1995. The Kanowna Belle project is owned by the Golden Valley Joint Venture (GVJV), an unincorporated joint venture with equal shareholdings between North Gold (W.A.) Ltd and Delta Gold N.L. North Gold are the managers of the development and operations and Delta Gold are the managers of exploration throughout the GVJV tenements.

Jan 1, 1990

During 1995 a catastrophic accident took place at the No 2 Vaal Reefs shaft in South Africa, when a locomotive fell onto a cage, causing the death of 104 people. The subsequent Commission of Enquiry found that the safety detaching hook had opened when hit by parts of the falling locomotive, detaching the cage from the rope and allowing the cage to drop 400 m down the shaft. It was believed that had the hook not detached, the rope would have been sufficiently elastic not to have failed, implying that many fatalities may have been avoided. In addition, the risk of accidental opening of hooks due to impact with smaller falling objects in shafts became a concern. This paper deals with a comprehensive statistical investigation that was performed to quantify this risk, establish acceptable levels of such risks and to derive criteria for the resistance of detachment hooks against accidental opening caused by impacts. The investigation involved a survey, dynamic finite element analyses and Monte Carlo simulations.

Jan 1, 2005

By Adshead ND, Blake KL, Rotherham JF, Rotherham M, De Jong G

Magnetite deposits with distinctive ¦ actinolite ¦ apatite -bearing gangue and spatially-extensive sodic-calcic wall rock alteration occur in both Proterozoic metamorphic terrains and Mesozoic-Tertiary magmatic arcs. Examples from both settings constitute significant sources of iron ore (e.g. Kiruna, Sweden; El Romeral, Chile) and some host major Cu-Au deposits that have a local association with K-silicate alteration (e.g. Cloncurry district, NW Queensland; Copiapo district, Chile). A growing body of evidence points to a hydrothermal origin for these systems involving high temperature, low S oxidized fluids. The Cloncurry magnetite-Cu-Au deposits are products of the local structurally channelized influx of a specialized high salinity ore fluid into larger-scale alteration systems developed during pluton emplacement at greater depths than those associated with subvolcanic (porphyry) Cu-Au deposits. The geological characteristics of deposits in magmatic arcs are consistent with a similar mode of origin albeit in rather different tectonic settings.

Jan 1, 1995

By Johnson RD

The variation in coal properties and the coal seam reduced level can be analysed using partial trend-surface analysis techniques. For the area studied seam reduced level and seam thickness data from the Bulli Coal yield trend-surfaces with a high coefficient of determination, since they have relatively small systematic local and random components in their overall variation. Sulphur content appears to have no significant re.gi_onal trend, and phosphorus content has a very weak regional trend. Other analytical variables have regional trends which are of intermediate strength. The strike-directions of.the statistically significant first degree! trend-surface are similar, sug-gesting.: that the variation of the several coal properties was controlled by a set of- related causes. The relations apparent from the dip and strike of the first degree trend-surfaces are similar to- those which are apparent from the trend- surface residuals and'from the results' of canonical trend-surface analysis.'.. It is probable that differential subsidence controlled the areal

Jan 1, 1975

By Doyle J

The direct method of gas content determin ation developed by McCulloch and Diamond of the U.S.B.M. has been adapted to estimate the gas content of coal seams from slim exploration borecores in the Southern Coalfield. Emphasis has been placed on the measurement of this parameter without the physical destruction of the core which is required for subsequent chemical analysis. In field and laboratory equipment is simple and inexpensive. It enables the determination of lost and desorbed gas from a fresh geological core. Residual gas is not measured but is considered to be relatively low and of no consequence in ventilation considerations. Results to date show good correlation with those obtained from underground face samples. Gas contents from the mined seams varying from 2 m3/tonne to 14 m3/tonne have been measur- ed with this apparatus. Gas desorption characteristics of South Coast coals have been found to closely follow exponential mathematical Models.

Jan 1, 1983

By Armstrong ME

The gas bubble energy generated by an explosive plays a major part. in the fragmentation, muckpile movement and damage produced. Previously, the interaction between gas pressure and the rock has been interpreted from a theoretical basis or a qualitative study of breakage mechanisms. A method to measure the fluctuations in gas pressure in rock adjacent to the blast has been developed. This peak pressure will vary with structure, as well as with distance and explosive type. The technique is simple to apply and can be used to observe the flow rate of gas at. varying distances. The apparent velocity of penetration is an indication of whether gas has travelled through pre-existing or blast induced cracks. The technique provides a ?n:eans of determining the suitability of an explosive for a given rock type, depending on the amount of displacement desired. The technique has application in optimir.irig throw blasting and predicting and controlling damage, particularly in highly structured rock masses.

Jan 1, 1986

By Burnett C. C H

GEMNet, (Grade Estimation using Mapping Networks), is a grade/reserve estimation software system that uses the artificial intelligence technique known as neural networks to perform reserve estimates from both two- and three-dimensional data samples from a mineral deposit. The system is the result of research carried out over the past three years into the feasibility of using neural networks for reserve estimation at the AIMS Research Unit in the Department of Mineral Resources Engineering at the University of Nottingham. This paper describes the architecture of the GEMNet system including details of the neural network components of the system. The performance of the GEMNet system is then compared to several other widely used reserve estimation techniques on two reserve estimation examples. The results produced by the GEMNet system compare favourably with more conventional estimation techniques, but require fewer assumptions to be made about the form of the data used, and do not require the use of complex mathematical modelling.

Jan 1, 1995

By Tsuchiya N, Takada Y, Okabe K

Alkalis in the blast furnace are removed mainly by the slag, Alkali removal by the slag was studied as a rate process of alkali vapor- ization from the slag flowing through the dropping zone in the blast furnace. The vapor-, ization rate of I:20 from CaO-Si02-A1203 IZ20 slag was- measured under various experimental conditions. An empirical formula for the vaporization rate was obtained as a function of slag basicity, temperature and surface area per unit mass of slag. A simulation model of IC20 vaporization in the dropping zone was evaluated using the rate equation when the true velocity and surface area of the slag was de- termined from a flow dynamic model of counter- current gas-liquid flow through packed beds. The influence of the dynamic conditions of flow, as well as the slag basicity and temperature, on alkali removal by the slag was estimated.

Jan 1, 1980

This paper forms part of a series of papers relating to the Melbourne Underground Rail Loop and presented to the Fourth Australian Tunnelling Conference in Melbourne, March 1981. The Design of Electrical and Mechanical Services in Museum Station and adjacent Running Tunnels and their relation to Rail.wruy Operation through the Loop are described. The descriptions, while specific to Muscrio Station, are generally representative of those being provided at Parliament and Flagstaff Stations. The Museum Station comprises some 6500 square metres of platform and track area, 5000 square metres of booking hall concourse and entrances and 1200 square metres of offices and plant rooms. The Mechanical and Ilectrical Services for this complex are .imilar in many aspects to those of a large !.gr.hrise city building, but in general the i::;ign is directed more strongly towards :.arety, durability and reliability, and subject to many restraints imposed by L'mitations of space and accessability.

Jan 1, 1981

By OÆBrien D, Priddle D

In order to avoid costly moisture penalties on coal shipments and to minimise rail freight costs, screen bowl centrifuges were selected and installed in the Mount Thorley Coal Preparation Plant for dewatering fine coal product. The Mount Thorley fine coal circuit consists of desliming the -0.5 mm (ww) fine coal in two stages of classifying cyclones prior to recovery by froth flotation. Provision has been made to bypass the flotation circuit with the classified flotation feed reporting directly to product and the centrifuge dewatering circuit has been designed to handle either flotation feed or flotation product. Major mechanical failures of the gearboxes and the ceramic tiling occurred early in the operation life of the machines which led to design changes being made to achieve satisfactory operation. This paper discusses the operating experience at Mount Thorley with respect to both mechanical and metallurgical performance of the screen bowl centrifuges since their installation in 1985.

Jan 1, 1989

Tailings facilities tell a story to the public about how the mining industry manages its activities. They also create a risk that must be managed for the long term. All the knowledge and technology is available to safely design, build, operate and decommission tailings facilities.   Tailings at Waikato North Head Minesite are pumped as slurry, over long distances and against high static discharge heads to backfill the excavated area. WNH is, under the mining licence, obliged to reconcile the topography of mined areas to the closest possible resemblance of the original terrain. The active tailings areas are located near main operational facilities and detailed plans and procedures have been developed to ensure a safe and continuous operation.   The concentration plant is designed as two identical and independent plants. Each plant has its own tailings slurry pumping system.   This paper represents a general overview of the tailings disposal practice at WNH mine site. It discusses tailings delivery, construction and water management.

Jan 1, 2004

By Fabjanczyk MW, Guy RJ, Tarrant GC

The design of the reinforcement systems required to stabilise mine roadways has developed through the application of field measurement techniques. These techniques have allowed the level of security of a given opening to be determined from an assessment of the loading within the reinforcement, the extent of roof deformation and experience. The design systems developed are now used extensively in a wide variety of geological environment. Recent interpretative techniques have been developed to improve the level of confidence when designing roadway reinforcement. The techniques are particularly applicable for roadways subject to either weak materials or extreme stress levels. A second area of application is where roadway advance rates and hence the timing of reinforcement placement are critical. The newly developed techniques include both analytical and computational models. The validated computational techniques allow a more rational approach to investigation of the effect of varying reinforcement type, timing of placement and density on the level of stability achieved.

Jan 1, 1992