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By D Craw

Quaternary warping and uplift of antiformal schist ranges in Central Otago, New Zealand, has resulted in recycling of alluvial gold from widespread, generally weakly auriferous, Miocene fluvial gravels that unconformably overlie the schist, into aprons of fan sediments along the range margins. Basement erosion during uplift has been limited and so gold input from sparse gold-bearing quartz veins in the schist has been relatively minor. In an eluvial cycle on the slopes of the ranges, chemical remobilization of gold occurs during oxidation and erosion of the Miocene sediments. The typically fine-grained (300 - 400 ¦m) gold undergoes chemical modification and grain size enhancement of up to two orders of magnitude, and much of it is redeposited in a large number of relatively small alluvial fans along the range margins. Groundwater mobility within the fans results in minor additional gold mobility and grain size enhancement. During range uplift, a small number of relatively large axial streams and rivers have developed in structural lows between growing antiformal folds. Axial streams 'gather' their flow from consequent streams draining the folds, and flow parallel to a range axis for some distance before cutting across it in an antecedent gorge. The axial streams rework alluvial fan sediments along the range margins, and transport mainly fine-grained gold from the fans along the ranges. This gold is redeposited where the axial streams emerge from a range in the neighbouring structural basin. Axial streams drain relatively large areas of range surface, and thus reconcentrate significant quantities of gold in a small number of relatively large fans and fluvial deposits. The processes of gold collection and re-deposition by axial streams are essentially the same, regardless of stream size. Coarse-grained gold produced by chemical remobilization, is more difficult to transport in fluvial systems, and thus remains in close proximity to eluvial environment where it was formed.

Jan 1, 1995

To counter depressed world nickel prices, a continuing effort is being made at Kalgoorlie Nickel Smelter to reduce unit production costs. One major area in which production costs can be reduced is the substitution of coal for fuel oil. Two areas where this has been achieved to bring about a saving are, the addition of coal to flash furnace flux to reduce supplementary fuel oil requirements in flash smelting and the replacement of two oil-fired air preheaters with a coal-fired unit. These actions have resulted in coal replacing 67% of the current fuel oil requirement in flash smelting at the Kalgoorlie .Lckel Smelter.

Jan 1, 1987

A Study on Process Mineralogy and Mineral Processing of Complex Carbon-Bearing Cu-Pb-Co-Ni Multi-Metal Sulfide Ore by Bulk Flotation

Sep 13, 2010

The history of potential large scale development at Stawell in northwestern Victoria dates back to 1914, when Great Boulder Mines Limited, of Kalgoorlie, Western Australia, took up options on some of the major mines in the Stawell Goldfield. Despite this and other attempts by various groups over the next thirty years, mining activity on the field gradually dwindled to the retreatment of old mill tailings.A static price for gold and indifferent drilling results prevented a major effort towards reopening the field until the late 1970's. A renewed exploration effort led to the discovery of sufficient reserves to justify installation of a carbon-in-leach gold treatment plant.

Jan 1, 1984

By T Roache, K Yang, M Quigley, C Young

In late 2004 a large-scale evaluation of a new suite of tools for semi-automated core logging was carried out in the Eastern Goldfields of Western Australia. Known as HyLoggingÖ Systems, these combine rapid hyperspectral mapping of mineralogy and very high resolution digital imaging of cores and chips in their original containers. The resulting data is very information-rich and provides information about host rock, alteration and regolith mineralogy. This, in turn, can be used to test geological models about fluid/rock interactions, ore system architecture, ore feed characterisation and generally improve the objectivity of the normally manual and variable logging process. Results were obtained from the Kanowna Belle and St Ives gold deposits in the Kalgoorlie region, as well as numerous holes from across Western Australia stored in the Kalgoorlie Core Library. At the Kanowna Belle gold deposit critical spatial trends in the proportions of white mica, the chemistry and species of those micas, the presence of selected carbonate species and the absence of chlorite proximal to ore zones have all contributed to improved ore deposit understanding. Significantly many of these trends are not discernible to the naked eye, nor easily quantified, previously, across many thousands of metres of core from separate drill holes. At St Ives, the HyLoggerÖ was able to show that low-Al (phengite) and high-Al (paragonite to muscovite) white micas are spatially associated with D3 foliation zones that are proximal and distal to Au mineralisation, respectively. D3 foliation zones are also associated with the depletion of metamorphic chlorite and amphibole, and their replacement with biotite, relative to unaltered mafic host-rocks. The HyLogged GSWA drill holes yielded mineralogical characterisation of classic deposits, including Kambalda (Ni), Fimiston (Au), Teutonic Bore (Cu, Zn, Ag), Black Swan (Ni) and Hannans (Au), illustrating a wide variety of mineralogical trends due to both host lithologies, previously unrecorded lithological subdivisions, and alteration patterns. During 2005 a unique thermal infrared HyLogger was developed to map the important remaining silicates, such as feldspars, quartz, olivines, pyroxenes and garnets. This was successfully tested on a 9000 m subset of the same cores as the earlier study. Interpretation has focused, in particular, on silicification, albitisation, and the mineralogy of several high-grade, less hydrous deposits.

Jan 1, 2006

By R. A. Frith, M D. Goodz

Ore-bearing minerals that are located along microfractures are always susceptible to loss during the breakage and sampling of the material. Further losses occur with on-site sample preparation and splitting prior to laboratory analysis. In these cases solid whole rock channel or core samples should be handled with due care to ensure all fines and loose particles are collected and included in the sample for total chemical analysis.Similarly open hole and reverse circulation drill methods are not usable in areas containing old mine workings, heavily fractured ground or highly degraded/oxidised mineral assemblages. Nor are these methods usable to assess a bulk mineable target where the enriched zones were peripheral to or between old mine cavities.

Jan 1, 1993

By Skinner J, Brackenbury K

The AuPlus" Systems have been applied in the gold mining industry to achieve improved gold recoveries, faster leach kinetics and reduced cyanide consumptions. Calcium or hydrogen peroxide, collectively known as peroxygens, can be used. The choice depending on plant design and the nature of the ore. Laboratory test work and plant trials are included in this paper to illustrate the benefits of peroxygen usage in extractive gold metal- lurgy.

Jan 1, 1991

By Jackson D. G

Iron ore mineralisation in the Paraburdoo environs is known to extend almost continuously over a strike length of 55 kilometres. Six formations of the Mount Bruce Supergroup con- tain high grade mineralisation in varying degrees of importance. Ore is currently being mined from the Joffre and Dales Gorge Members of the Brockman Iron Formation, with smaller, less significant amounts, occasionally taken from the lowermost units of the Weeli Wolli Formation and the upper parts of the Mount McRae Shale. Regional mapping has demonstrated the existance locally of a major unconformity at the base of the Wyloo Group sediments out- cropping south of the minesite. The basal con- glomerates at the unconformity are sometimes mineralised at Paraburdoo. A supergene enrich- ment process controlled by structure, strati- graphy and topography is the only one which can satisfactorily explain the disposition and chemistry of the Paraburdoo iron orebodies.

Jan 1, 1979

By Katsuyama K, Nag DK

Three aspects of rock mechanics, namely, in-situ stress estimation by acoustic emission (AE) method, strength of rock mass and role of chemicals to reduce the strength are covered. It is possible to detect the previously applied maximum stress by stressing a rock specimen to the point where there is a substantial increase in AE activity. This is known as Kaiser effect. From the AE signatures in the second and subsequent loadings, AE take-off point was identified more easily than in the first loading. In determining the compressive strength of rock mass, two factors have to be considered, namely, the size effect on the compressive strength of intact rock and the effect of discontinuities on the compressive strength of rock mass. Although a modified Bieniawski criterion gives best agreement with the triaxial test data, modifications have been suggested to Hoek-Brown criterion due to its popularity. It is possible to reduce the tensile strength of sandstone by saturating it with weak chemical solutions made with dodecyltrimethyl ammonium bromide, polyethylene oxide and aluminium chloride by up to 30%. In the case of compressive strength, there is no appreciable effect. The possible explanation is that the chemical solutions produce an effect on the strength of sandstone only when the failure mechanism is dominated by tensile mode.

Jan 1, 1998

By Nightingale RJ

A column (50 cm 4) provided with a bell charging mechanism and a rectangular perspex insert was used to investigate the inter-relationship between charging pattern, size analysis and velocity profile for a number of charging methods. It is shown that a strong correspondence exists between size distribution and velocity profile for bell charged ore and coke and that decreased coke volumes cause higher pressure drops and increased central flow in beds with "V" shaped layers. It is also shown that a bell charged mixed burden exhibits greater segregation than when it is bell charged as layers and that when uniformly charged the mixed burden shows least segregation and a virtually flat velocity profile. A relationship is derived for "V" profile charges showing the extent of central segregation with furnace size.

Jan 1, 1975

DuPont is a chemical and energy multi-national of approximately 90,000 employees. Often regarded as the world leader in injury reduction and process safety management, DuPont operate 140 manufacturing sites around the globe. Conoco is a wholly owed subsidiary of DuPont which is involved in oil, gas and coal exploration.   Throughout this paper I will discuss DuPont statistics, developing a safety culture and training process as well as discussing possible short comings in the New Zealand safety focus. I will conclude with my recommended improvements and issues for New Zealand companies to focus on.   It is very difficult to compare DuPont and New Zealand statistics through lack of compatibility in recording methods and my ability to interpret ACC's Injury Statistics. However through considering DuPont's statistics, and comparing them to your own companies or departments, you will agree they are indeed impressive. I hope that by discussing DuPont's safety philosophy, and possible shortfalls within New Zealand Legislation many of you will find ideas and inspiration which will help you to further reduce your own injury rates.

Jan 1, 1997

Twelve years ago, Jeffrey Mining Machinery Division of Dresser Industries Inc. developed the 120H HELIMINER. This machine was the world's first fixed-drum continuous miner and soon became the standard among manufacturers of continuous miners throughout the mining machinery industry. This paper will first outline a brief history of continuous miner development, then discuss significant parameters which are essential to a successful continuous miner design, and finally describe a number of specific applications of Jeffrey continuous miners in a variety of materials, such as coal, potash, iron ore, and trona, around the world.

Jan 1, 1978

By Terlich R. E, Finlayson J. M

A combination of high virgin rock temperatures, deep workings and extensive utilisation of heavy diesel equipment has presented North Mine (A Division of North Broken Hill Limited) with challenging ventilation problems. These problems have been addressed in a variety of ways which include in the order of 6000 kM of underground refrigeration. The future of North Mine depends on the successful development and extraction of ore in excess of 1100 m below the shaft collar using mechanised cut and fill mining. The success of this will depend on the installation of a complex chilled water reticulation circuit in this area. This will involve planning and constriction of a number of large dams, installation of pups and turbines, and the successful commissioning of several large water to air heat exchangers.

Jan 1, 1988

Broken Hill South Limited's discovery of phosphate deposits in the northwest of Queensland in 1966 prompted intensive exploration which has proved phosphate rock in excess of 2,000 million tons at ten separate deposits.Systematic exploration for phosphate in Australia was initiated by the company in 1964. Early in 1966, an investigation of oil wells in the Georgina Basin in the Northern Territory and Queensland revealed widespread anomalous phosphate in early Middle Cambrian Beetle Creek Formation and Thorntonia Limestone. Phosphorites recognized in oil wells in the southeastern part of the Basin, Queensland, led to the discovery of the Duchess deposits. Exploration of the Beetle Creek Formation since 1966 has disclosed nine other sizeable deposits north of Duchess around the eastern margin of the Basin. The Lady Annie and the adjoining Lady Jane deposits, by reason of their location, 160 miles south of the Gulf of Carpentaria, are expected to be the first to be brought into production.Beneficiation testing and engineering investigations commenced in 1967. Transport between the deposits and various port sites in the Gulf of Carpentaria has been extensively studied and a slurry pipeline as a means of transport to a deep water island port, is now being investigated.

Jan 1, 1971

The paper describes a computer model developed within the State Electricity Commis- sion of Victoria for use in open cut planning. The purpose of the model is to simulate all the typical occurrences in, and influences on, the coal supply and overburden disposal systems in order to be able to assess their performance. The model incorporates much of the long term and day-to-day operations planning logic required for the allocation of resources within an open cut. This logic takes account of power station demands, bunker stocks, plant and crew availability, the balance of reserves between dredgers, planned maintenance, etc. The perfor- mance of plant within the system is simulated using random selections from statistical distri- butions of Time to Failure and Time of Failure for each plant item. The application of the model in selecting a suitable bunker capacity in a notional open cut development is described to illustrate the potential of the model in optimising plant selection.

Jan 1, 1982

By Mistra M, Hu JS, Wadsworth ME

The fluorite/oleate system has been studied extensively since the begin- nings of flotation research. The well-defined relatively simple crystal structure of fluorite and its ionic bonding make it a model system for study. Our understanding of fluorite/ oleate flotation chemistry continues to grow but as yet remains incomplete. Besides a review of our understanding of this system, recent findings are presented in this paper, and new research horizons are identified.

Jan 1, 1984

Feasibility is a value improvement process for projects. At any stage in project development, a feasibility study can be undertaken, but although the scope generally remains unchanged the extent of detail and level of accuracy usually increases with time. The main scope elements are a business definition, project description and an execution plan. The studies are designed to assess the potential of the project and to secure funding for on-going examination. Invariably, the investigations loop back to earlier stages to establish more appropriate development criteria but a critical stage is reached when a project construction decision is requested. This feasibility study requires very detailed presentation and analysis to a higher accuracy for the owner(s) and their potential lender(s).

Jan 1, 1997

Segregation studies in ternary systems of glass ballotini, iron ore and coke particles (with size range of 1-8 mm in each) in filling and emptying a laboratory size Paul Wurth hopper are described. In-bin segregation is shown to be a function of the position in the hopper, the nature of the material and the feed composition. The in-bin results are correlated by the equation C = C0k, where C and C0 are the size compositions (wt per cent) in the hopper and feed respectively, and k is an experimentally obtained segregation constant. The results of now pallern measurements show that material discharges from the hopper according to the sequence; core now - wall now - scaffold now, where the latter represents stagnant material at the hopper wall that discharges last. Size segregation in the discharge stream from the hopper is shown to be a function of in-bin segregation and hopper now pallern. A method of predicting discharge segregation from these two sets of data is suggested. The results of the model studies are also compared with industrial data and these show satisfactory agreement. Discussion of the hitherto ignored effect of size segregation on hopper now rates, stoppages and other operating problems is also included.

Jan 1, 1985

By Fourney W. L, Dick R. D

A small-charge rapid excavation system employing a novel penetrating cone fracture initiation and propagation technique has been demonstrated to be capable of excavating the hardest of rocks at efficiencies (energy per unit volume of rock removed) four to ten times greater than attainable with conventional drill and blast. Significant enhancements to the concept developed during the research efforts include the use of propellant rather than explosive charges and a device for containing the charges and effectively sealing the shot-holes. The experimental results, including the excavation of several tons of hard rock in a research mine, have confirmed the novel breakage process and provided a data base for the design of a continuous hard rock mining machine based upon the concept. The small-charge excavation system would be attractive for civil construc-tion operations where sensitive structures, equipment and personnel would be in close proximity to the excavation face. The system would be attractive for selective mining operations where the ore rock could be fragment-ed and processed separately from the barren country rock. The barren rock could then be backfilled underground and eliminated from the traditional hauling and milling operations.

Jan 1, 1990

By Slechta JJ

The performance of a hydrocyclone treating fine coal has been examined over a wide range of feed and operating conditions.The results were expressed in terms of partition curves from which the water split to the oversize flowstream,the corrected separation size and reduced partition curves were determined-.The following conclusions were obtained. (a) The water split to the oversize flowstream was found to be dependent upon the vortex finder and spigot diameters of the cyclone and the flowrate and solids content of the feed slurry. (b) The corrected separation size was dependent on the solids content of the feed,and the vortex finder and spigot diameters.The hydraulic pressure (or flowrate) of the feed slurry did not have a significant effect.This phenomenon could be explained in terms of crowding of the particles at the Spigot.

Jan 1, 1984