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By Rais SA

In June, 1986, Freeport Indonesia, Inc., in conjunction with Out- okumpu USA, laboratory tested the Flash flotation concept on Primary ball mill underflow. These laboratory results indicated a possible 10% increase in precious metal recovery and 0.6% increase in copper recov- ery were available over conventional methods. By October of the same year two Outokumpu Skim Air SK-240 units were operational on one mill circuit and were achieving 5 to 10% increased recovery in precious metals with equal copper recovery at one percent higher final concentrate grade. Two more cells were purchased and installed on the remaining grinding circuit in July, 1987. As part of the installation of the Skim Air cells, an existing cluster of six 508mm Krebs cyclones were replaced by four 660mm Krebs cyclones. To reduce high circulating loads, these new cyclones were made horizontal at 45 degrees. This arrangement succeeded in reducing the mill circulat- ing load by 100% and has allowed for a 10% increase in throughput at the same grind.

Jan 1, 1988

Revised throughput rates, as a result of current mining methods and tight controls on mine dilution, have dictated a change in metallurgical philosophy at Renison Limited. Emphasis on throughput capacity increases has altered to a reduction in circuit complexity and operating costs. Extensive surveys of the gravity and cassiterite flotation circuits led to several plant modifications between August 1989 and March 1990. The coarse and fine gravity retreatment roughing tables were by-passed, the coarse gravity retreatment roughing tables were re-commissioned, the cassiterite flotation rougher capacity expanded and the gravity regrind cyclones re-configured.

Jan 1, 1991

By Jr

This paper provides a comprehensive review of the requirements of a full due diligence study for a coal property acquisition in both text and table format. From the initial scoping of the assignment, the paper discusses in depth from reserve base validity and mineability; historic performance; plant and equipment; future mine plans; infrastructure; capital spending and operating costs; labour and management; future risk assessment and environmental liabilities; marketing; valuation and finally acquisition synergies. All are important areas to ensure the viability of the acquisition and to identify and minimise the project risks.

Jan 1, 2003

By J Nemcik, E Baafi, I Porter, G Spinks

Spray-on liners used in the mining industry for ground support and stabilisation applications are either cement based (æshotcreteÆ) or polymer based (æthin spray-on linersÆ). Some thin spray-on liners are a blend of both polymer and cement (eg Tekflex). A small number of thin spray-on liners (TSLs) have been trialled in Australia as potential replacements for steel mesh in roadways and other underground mining applications; however, they were found to cure slowly and the cured coatings became brittle after an extended time in place. The University of Wollongong in collaboration with the Australian coal mining industry has shown that a viable polymer-based alternative to steel mesh in underground roadway support applications can be developed to eliminate the use and handling of steel mesh. The work to date has: established the feasibility of developing polymeric alternatives to steel mesh in underground roadway support applications; identified the physical and material constraints to be endured by any new polymeric skin reinforcement system by measuring the mechanical properties of steel mesh; identified materials that can be spray applied; and demonstrated that polymer mechanical properties can be optimised to produce similar mechanical properties (elastic modulus, yield stress, elongation-at-break, etc) to steel mesh. The identified materials will: allow the face support cycle to be fully automated, or at least remotely operated and installed; remove personnel from the immediate face area; and substantially improve underground roadway development rates.

Jan 1, 2008

Over the last thirty years production of heavy minerals from Australian deposits has dominated the world market. The main incentive has been to suoply the raw material for titanium dioxide based pigments. These ~ninerals include ilmenite, rutile, leticoxene and more recently, synthetic rutile. Inevitably the viabilit/ of developing placer type deposits has seen influenced by other heavy minerals present, such as zircon and monazite, but these have been of secondary importance. For most of the sixties and seventies, Australia supplied the 'najority of free world rutile and zircon, and a large proportion of the ilmenite. With the run-down of rutile- rich reserves in eastern Australia, the emphasis has s:iifted in several countries, including Australia, to fill }the gap with i l Wen i to and its derivatives, leucoxene, synthetic rutile and titanium rich slag. over the next 15 - 20 years, as high grade beach placers in Western Australia are mined out, less traditional sources for mineral sands products will be opened up. Low grade placers (particularly those dominated by ilmenite) will be reassessed in Australia, U.S.A., Africa and Asia, and exploration will shift from beach and dune environment, to heavy mineral concentrations in alluvials, lake deposits and continental shelf deposits. At the same time, production of anatase and bastnaesite will be expanded, as required, from the huge resources contained in carbonatites in 3razil, U.S.A. and China.

Jan 1, 1986

By Morinaga K

The optical basicity (A, Pb2+ as probe ion) of various oxide glass systems has been measured to establish the new basicity scale of slag melts. Best conditions of glassy fragments to measure A were as follow, (1) 1 ti 4 x 10-2 wt% Pb content, (2) 0.2 mm in thickness, (ii) enough annealing (about 10 hr) at a temperature 200¦C below Tg., and (4) polishing a surface well. the variation of A with composition was correlated to that of relative oxygen activity of slag melts. The estimation of basicity of slag melts from it could be valid. The A of opaque and coloured quenched slags could not be measured. An approximately linear relationship, however, exsisted between the isomer shifts (b) of Fe3+ ion in slag derived from the Mossbauer effect and A. Therefore, -4 of various metallurgical slag could be estimated from this relationship. These results can be expected to establish the new basicity scale of slag melts as the Louis basicity.

Jan 1, 1980

By Just J, Nguyen G, Dunn J. G, Graham J

A sample of pyritic gold concentrate was investigated by wet chemical and electron optical techniques. Sub-samples were roasted in a laboratory scale fluidized bed roaster in the temperature range 400-700¦C. The calcine was characterised, and cyanide-leached using a standard bottle rolling test. Gold extraction efficiencies varied with roasting temperature. At temperatures of 400 and 450¦C gold ex- tractions of less than 40% were achieved, but between 500-700¦C the extraction had increased to 93--98Z. The surface area of the calcine varied with roasting temperature, reaching a maximum at 500¦C. There was no correlation between the surface area of the calcine and the efficiency of gold extraction.

Jan 1, 1987

By Gilbert DJ, Lemon NM

A case history of a two year study of low grade ores in the Middleback Range area with the objective of defining possible areas of interest from a combination of geological- petrological-metallurgical criteria. Covering the general geology of the area and ore types; the results of metallurgical testwork and the pattern of evolution of these tests; the petrological explanation of the results of the testwork; the culmination of the work in the selection of areas of best potential for more intensive work. Jaspilites consisting of magnetite, hematite and limonite with quartz and silicate-carbonate-sulphide minerals are hosts to high grade iron mineralisation but also constitute a large low grade iron Reserve.

Jan 1, 1975

Those developing or planning a new mining operation base their financial projections on amounts of gold produced as soon as practically possible. The choice and ongoing operation of mobile plant figures significantly in their projections. The implications of mobile plant selection are not always clear - until its too late.Our 'typical' gold mine would be a mine processing 800,000 tonnes of ore per annum, producing 37,000 ounces of gold with a life of mine of 10 years. Overburden layers are only evident in the first two years of operation.The pit will eventually, after some 5 years of mining, be some 300 metres deep, but confined to a mine radius of 2 kilometres.

Jan 1, 1986

Expert systems have been employed in a number of areas for a considerable number of years. However, the traditional long development times associated with these systems have restricted their application. With the advent of powerful Expert System Development Tools such as COMDALE/X and the use of efficient development techniques, the time required can be drastically reduced. This results in the availability and applicability of this technology to a wide range of applications. This paper discusses some of the 'rules' which indicate amenability (or otherwise) of a particular problem to an expert system solution. Various problem types are examined and these are illustrated with reference to examples of their use at various operating sites.

Jan 1, 1991

By X Zheng, P Manton

Pebble recycle crushing circuit performance at Telfer has historically fallen significantly short of the design product P80 of 12 mm. An investigation was undertaken to evaluate the current pebble crusher circuit performance, quantify the optimum performance achievable with the existing circuit and examine the impact of pebble crusher performance on the overall grinding circuit throughput. The primary objective of this investigation was to develop an operating strategy that could consistently deliver the finest possible pebble crusher product to maximise the overall plant throughput.The pebble crusher specific energy (Wc) was proposed as a key control variable for pebble crusher operation based on the results of plant survey work. Over the range of pebble crusher specific energies encountered at Telfer, a strong linear relationship was found to exist between Wc and the crusher product size. This direct linear relationship between specific energy and crusher product size remained constant regardless of how the change in specific energy was generated, ie through changes to the crusher closed side setting (CSS), feed rate, liner profile or moisture content. Key findings for the Telfer pebble crushing circuit were: each 0.1 kWh/t change in Wc resulted in a 4.9 per cent to 6.0 per cent change in plant throughput, each 1 mm change in pebble crusher CSS resulted in a 2.2 per cent to 2.6 per cent change in plant throughput, and 0.57 tonne of new feed was displaced for each tonne of crushed pebbles recycled to the semi-autogenous grinding (SAG) mill. The presence of an existing 3000 tonne pebble stockpile between the SAG mill and pebble crushers provides an opportunity to manipulate the feed rate to the pebble crushers independently of the SAG mill pebble production rate. This flexibility, along with excess pebble crushing capacity, enables the pebble crusher specific energy to be maximised the majority of the time. Pebble crusher specific energy has subsequently been incorporated as an online crusher control measure to assist in maximising plant throughput.

Jan 1, 2009

By N Fullelove

The Renison Bell Tin Mine on the West Coast of Tasmania has recently installed a new underground ore handling system incorporating underground crushing, conveying and hoisting facilities. Contracts for the sinking of the shaft and the development of the mine were let and managed by the operator, Renison Limited. Hardcastle & Richards was responsible for the design, procurement and construction management of the fixed plant and equipment including civil, structural, mechanical, electrical and instrumentation services. The system demonstrates worldÆs best practice in design and incorporates a state-of-the-art integrated control system allowing the entire system to be controlled by a single operator located in the underground crusher chamber. A rapid construction period was achieved, despite the difficult and constrained underground environment, without affecting the ongoing operations of the mine. The mine, which was established in the mid-1960s, had previously operated by trucking ore to the surface via a decline. Truck haulage distances and costs had increased as the mine became deeper over the years. By the 1990s it had become apparent that, in order to remain economically viable, it was necessary to reduce truck haulage distances and allow the mine to go still deeper to access orebodies such as Rendeep beneath the current workings. The Internal Shaft System achieved this by eliminating approximately 5 km of truck haulage. It allows the production rate to be increased to up to 1 Mtpa compared with a limit of 628 kt per annum by direct truck haulage to surface. The access it provides to the Rendeep ore and other deep orebodies greatly increases the amount of ore which can be economically mined.

Jan 1, 1998

By L S. Barbour, M K. Meiers

Soil covers for mine waste are subject to changes in structure as a result of root development, and wet/dry or freeze/thaw cycling. The purpose of this study was to evaluate the changes in the hydraulic conductivity of three non-compacted clay covers over time. The covers are located on a sodic/saline overburden fill (30-Dump) at the Syncrude oilsands mine in Fort MacMurray, Alberta, Canada. Monitoring of these covers for temperature, matric suction, and water content by the University of Saskatchewan has been ongoing for more than three years. The three covers (D1, D2, and D3) were constructed in 1999 and are 50 cm, 35 cm, and 100 cm thick. The covers are comprised of a surface layer of reclaimed peat/mineral mix over a secondary reclaimed mineral soil (glacial till or glaciolacustrine clay), placed over a sloping shale surface. Field measurements of hydraulic conductivity within the secondary layer were obtained using a Guelph Permeameter during the 2000, 2001, and 2002 summer field seasons. Repeated measurements were made within the D1, D2, and D3 covers at depths of approximately 40 cm, 30 cm, and 60 cm, respectively. The values of hydraulic conductivity for the covers were similar to each other during each of the field study seasons. The mean hydraulic conductivity of the secondary layer increased every year: 2.5 + 10-6 cm/sec to 2.1 + 10-4 cm/sec to 4.3 + 10-4 cm/sec from 2000 to 2001 to 2002. Soil temperature data shows that one freeze/thaw cycle occurred each year at the measurement depths.

Jan 1, 2003

By Porter I, Singh RN

An advanced elasto-plastic finite element model adopting a modified Von Mises yielding criterion was used to simulate progressive failure of the rock strata surrounding a room and pillar mine structure. The model conformed to the strain-softening behaviour of rock and accounted for post-failure residual strength. The simulation was achieved in such a way that material values were updated after each FE run, according to the stress criterion until the solution reached the final equilibrium steady state of the mine structure. The suggested structural stability analysis approach accounted for the main features of the structure degradations produced during loading through changes in rock material stiffness and subsequent evolution of stresses. Comprehensive parametric analysis was performed and the inevitable effect of interaction of the roof, pillar and floor on the overall mine stability limit was investigated. The numerical results clearly showed that linear models could not realistically represent the true behaviour of the mine structure. The results obtained are in good agreement with that predicted in the field.

Jan 1, 1992

By Fabjanczyk MW, Aziz NI, Hii J

The paper presents the results of a series of pull out tests performed on roof reinforcement systems currently being adopted in mines in Australia 7mm wire, dividag bar, 15.2mm strand cable, and birdcage cable. The study also investigated the load deformation chara- cteristics and the various design parameters controlling the effectiveness of a cable-grout system. Suggestions for continued work are Highlighted.

Jan 1, 1986

From a personal view that encompasses both research and assessment of major projects the author outlines the two competitive pressures that will force more rather than less metallurgy viz the increasing difficulty in purchasing the latest overseas developments and environmental concerns. This paper then goes on to argue that Australian metallurgy or more precisely process engineering may be in a unique position to deliver the required results.

Jan 1, 1993

Pilot plant work has played a major role in the process development and design phase of the Iscor Heavy Minerals project. The pilot plant campaigns have been aimed at three process areas, namely primary beneficiation (wet gravity circuits), heavy mineral separation and ilmenite smelting. A process development structure was put in place, and the various pilot plants designed and built. A number of pilot campaigns were conducted during the project phase since 1995, and most of the key objectives were achieved. Various other valuable ælessonsÆ were learnt, and were incorporated in the full-scale plant designs, or used to change operating philosophies, equipment choices et cetera. The cost and durations of the pilot runs were significant, and an analysis indicated that the major risk and technology area of smelting has contributed more than 70 per cent of the total cost.

Jan 1, 2001

By Booth GW, Robertson IG

The Paddington Gold Mine ties within the Norseman-Wiluna greenstone belt, in the celebrated Eastern Goldfields province of the Yilgarn Block, Western Australia. Regionally, tropical to subtropical weathering has effected development of a prominent regolith and a deep lateritic profile. Detailed examination of the clay mineralogy, largely from a single drill hole which traversed the original Paddington I deposit, outlined three separate, vertically gradational assemblages, which are, in part, rock-type dependant. These include; 1. kaolinite with minur to trace quantities of sericite/illite (0-22m), 2. smectite and/or interstratified clay minerals, together with variable amounts of kaolinite, relic chlorite and illite/sericite (22-81m), and 3. chlorite and sericite (> 81m). Near surface, kaolinitic assemblages may be directly correlated with the intensity of lateritization, whereas smectite and interstratified clays from intermediate zones appear in association

Jan 1, 1989

By M van Kampen

The Resource Management Act 1991 has been amended on a number of separate occasions since its enactment in 1991, and has recently be subject to further amendment by way of the Resource Management Amendment Act 2005. The amendments as proposed in the Resource Management and Electricity Legislation Bill would have had revolutionary and far-reaching consequences. However, as finally enacted, the amendments are a greatly watered down version of what was initially proposed.   Nonetheless, the Resource Management Amendment Act 2005 has provided for a number of amendments that will impact on the minerals industry to varying degrees. This paper discusses in particular the changes and impact of the changes to the definition of æcontaminated landÆ, clarification with respect to the duty to consult, amendments to the provisions relating to National Environmental Standards, and to the council and Environment Court hearing process.

Jan 1, 2005

By Eggleton T, Taylor G

The lateral and vertical distributions of gold and a wide range of other elements in the regolith, close to Au and Cu mineralisation have been investigated at Goonumbla, NSW. Open cut mining has exposed deeply weathered profiles which have been used for this investigation. Determination of secondary mineralogy and micromorphology of profiles have facilitated the broad interpretation of processes that determine element mobility and dispersion from primary mineralisation as a result of weathering. This in turn has led to better interpretation of geochemical data and enhanced understanding and knowledge of regolith geochemical processes which are invaluable in the formulation of improved exploration Procedures.

Jan 1, 1997