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The Yabulu refinery of Queensland Nickel Pty Lld near Townsville now imports more than three million wet tonnes per year of nickel laterite ore from New Caledonia and Indonesia, making it the largest importer of any commodity in Australia. The project has illustrated that importing untreated bulk ore and re-exporting high value products makes good economic sense for the company and the nation.The economics of this exercise were considerably enhanced in 1994 by changing the project's principal product from nickel-oxide sinter to refined high-purity nickel metal. It is one of the few operations in the world where nickel ore is transformed to nickel metal at a single site.Several novel technological processes were developed at Yabulu and incorporated into the refinery to allow this product transition to occur. By utilising internally developed technology the new processes were installed at a capital cost of less than $10 million. It is unique for a large nickel producer to change completely the quality of its entire product range many years after the plant was constructed and considerable attention to marketing the new products has been required.The changes have meant that the project is no longer limited to selling lower-value oxide sinter to a relatively small number of large stainless steel mills. In the past year sales of the new high purity nickel metal products have expanded to include a broad range of international customers in the special alloy, foundry and chemical industries.

Jan 1, 1995

By Gunther L. M, Rich N

Remapping of the Burdekin Basin has resulted in the subdivision of the three formations (megafacies) previously recognised in the Late Devonian Dotswood Group. Nine dominantly volcaniclastic facies are now identified within the three megafacies, representing coastal plain, floodplain lake, alluvial plain, ephemeral lake and alluvial fan depositional environments. The Dotswood Group was deposited during a major regressive phase that began at the end of the Givetian, continued throughout the Frasnian and ended in the early Famennian.The proposed depositional model completes a southeasterly progradation of coastal plain facies over shoreline and nearshore marine facies established in the underlying Fanning River Group. Uplift and associated acid-intermediate volcanism to the south of the Burdekin Basin, resulted in the deposition of a volcanogenic alluvial fan facies locally preserved along the southwestern margin of the basin. Tuffs and ?ignimbrite were deposited in widespread floodplain lakes which lay behind the coastal plain. An alluvial plain traversed by southward flowing rivers, formed the northern margin of the basin.

Jan 1, 1990

The Porgera mine and treatment plant are located in the Enga Province of Papua New Guinea. Gold in the Porgera deposit is found free and in association with the primary sulphide mineral pyrite. The refractory nature of the gold in the pyrite r

Jan 1, 1997

The results of about 30 years of exploration and mining activities and research studies in the Kambalda mining district, Western Australia, have led to general agreement that the komatiite-associated Ni sulphide ores formed as a result of igneous processes (Ross, 1974; Ross and Hopkins, 1975; Gresham and Loftus-Hills, 1981; Cowden, 1988; Lesher, 1989 and many others). Despite this agreement, the controls on sulphide supersaturation and concentration of the resulting sulphide in a limited zone, remain uncertain and controversial. A major uncertainty is the source of sulphur in the ore deposits. Two principal sulphur sources have been proposed: 1. komatiite lava/magma (Hudson, 1972; Naldrett, 1973; Lesher et al, 1981; Cowden, 1988; Foster et at, 1995), and 2. sedimentary material (Groves, Barrett and McQueen, 1979; Lesher, Arndt and Groves, 1984; Lesher, 1989; Lesher and Campbell, 1993). Resolution of the uncertainty regarding the sulphur source is required for a complete understanding of the controls on ore formation, which in turn would significantly impact exploration strategies in the Kambalda mining district and elsewhere. This paper reviews the constraints on sulphur sources for the komatiite-associated Ni sulphide ores in the Kambalda mining district. The focus is on the general characteristics of the ores and surrounding rocks: individual ore deposits are not described, though specific examples are noted where appropriate. The stratigraphic and volcanic settings and geochemical (major and trace element and isotopic compositions) characteristics of the ore deposits and surrounding rocks are considered within the context of the competing sulphur source models, and future directions of research in the district are noted.

Jan 1, 1996

The exploration and mining risks are investigated and compared to the risks of smelting, secondary processing and other normal industrial activities. This study concentrates on the risk before, or at the investment decision. Internal and external risks are distinguished. Internal risks are the risks inherent in every engineering design and common to all projects. The main external risks are the financial risk, changes in prices, location problems and geological factors. Financial risks concern every capital-intensive and export-oriented project and cannot be considered as typical mining risks. Changes in prices, i.e. the market risk, concern every industry using raw materials, but the market risk is especially accentuated in the mining industry. Problems of location and infrastructure are normally more significant in mining than in other projects, and geological risks are unique to mining. All these risks associated with mining projects combine to form a risk at least twice as high as that for other normal industrial activities. Within the range of profitability of mines, which on average is the same as in the manufacturing industry, only a few highly profitable mines exist. These few mines are the sole reward for the high risks taken.

Jan 1, 1986

Railway cuttings require the highest care in design and construction, as the pro- bability of failure concept does not allow any risks to be taken with hundreds of lives being dependent on continued stability. The usual geological influences on stability such as bedding dip and faulting are often discus- sed, but other major problems may come from the presence of sheet joints, cross joints differential weathering and seasonal or daily changes of ground water level. The design of rail cuttings has taken little note of the problems imposed by cons- truction methods, and low cost quarrying methods may seriously weaken a designed shape. The presence of berms and drainage ditches is often difficult to achieve as blasting imposes cumulative stresses and jointing on rocks. Contractors face difficulties in bidding extensive rock cuttings as variations in rock properties are often concealed and overshoot- ing the toe of a batter can easily occur. Modern blasting methods offer some solutions, but the best guide to safe successful cuttings is extensive investigation and the continued involvement of engineering geology at the stages of feasibility, design, construction and maintenance. Two case histories show the influence of folding, faulting and construction methods in the case of slope failure and slope stability.

Jan 1, 1979

By H Beucher

The uranium grade in roll front deposits is the result of successive processes that can be summarised in two steps. First a sedimentary phase, which gives the deposit support, then an oxidation-reduction phenomenon, which leads to the uranium deposit itself. In order to simulate such a deposit, it is important to mimic these different phases. The final aim of such a study is to localise the uranium itself and to reproduce the internal heterogeneity of the orebody in order to simulate the recovery process. The idea in this paper is not to reproduce a genetic approach but to consider the final image of the deposit. Three approaches are proposed. The first one consists of simulating the facies of the sedimentary deposit. The second approach reproduces the distribution of facies resulting from oxidation phenomenon (reduced or oxidised facies). The third approach consists of simulating the mineralisation at the interface of reduced and oxidised areas using the definition of a new data set determined by the grade values. At the end of each approach, the uranium grade could be simulated facies by facies according to the corresponding distribution characteristics. The plurigaussian method dedicated to random set simulations is well-suited for the facies simulations of deposits resulting from several sedimentary processes whether correlated or not. In this paper, the benefit of this method is demonstrated in an actual case study.

Jan 1, 2006

Three separate and unconfined aquifers occur in the Hilton area, named relative to position in relation to ore horizons: Footwall Aquifer in the east; Ore-Zone Aquifer within the ore-bearing Urquhart Shales; and the Hangingwall Aquifer in the west.It is the on-going strategy it Hilton to drain the Ore-Zone Aquifer which occupies structurally- and sulphide-controlled leached zones in the steeply west dipping strata. The aquifer affects considerable ore reserves to 480 m below the surface. Dewatering began in 1976, and is essentially completed to 4 level (240 m below surface). Dewatering efforts are now based on 8 level (480 m below surface).

Jan 1, 1993

By J Brisebois

The Wisemans Creek derelict mine site is located in native forest approximately 150 km west of Sydney. Mean annual rainfall at Bathurst, 20 km to the north, is 634 mm and reasonably distributed throughout the year, with slightly more rain falling in the summer months. Evaporation is 1350 mm per annum and considerably exceeds rainfall in all but the winter months (May to August). This results in a water deficit for much of the year. Groundwater is relatively deep, as it has not been intercepted in the shallow open cut workings. Investigation of the groundwater regime was beyond the scope of the current study. Mining has taken place on the site for almost 100 years, during which copper, talc and gold have been sequentially extracted from surface and shallow underground workings. The site is now characterised by the presence of small open pits, unprotected shafts and adits, mullock heaps and an unconfined tailing deposit from a small cyanidation plant. From a distance, the mine area is visible because of two distinct steep bare slopes below the relatively small mine workings and mullock heaps. The mining area was characterised in terms of its environmental, safety and heritage issues. Mullock from the early copper mining was found to be acid forming and leachate from this, combined with clearing of timber, has most likely resulted in death of vegetation below the heaps. The mullock also contains elevated concentrations of heavy metals. The gold tailing is apparently benign and not acid forming, although there are indications of oxidation and acid formation in the derelict gold open cut. Oxidation of the acid forming mullock still appears to be taking place even after being exposed to the atmosphere for at least 50 years, resulting in continued contamination of the slopes below the heaps with heavy metals. The concentrations of metals decreases with distance below the mullock heaps and also is confined to the ground surface the further away from the mullock, providing further evidence to support the theory that the mullock is the source of contamination. Despite this continuing contamination, its spread beyond the immediate mining area appears to have been limited because of the relatively dry climate, with only intermittent rainfall and stream flows. Irregular storm flows in the nearby creek could also have washed any contaminated soil some distance from the site and beyond the area investigated in this study. Remediation of the site and restoration of vegetation on the bare slopes will therefore depend on elimination of the source of acid and metals. Options for remediation, focussing on minimising cost by retaining the materials on or close to the site, are identified. The volume of the open cuts would appear to be close to that required for burial of the acid-forming mullock, thereby removing the source of surface contamination while keeping it above the groundwater table. However, implementation of this remediation plan will depend on the availability of funds to undertake the work through the New South Wales GovernmentÆs Derelict Mines Program.

Jan 1, 2003

By J-S Zhang

In this paper, the author briefly introduces the resource characteristics of Chinese iron ore, as well as the present increasing market demand for iron concentrate. The SHP-3200 wet high-intensity magnetic separator (HIMS) is used to separate complicated weak-magnetic iron ores being composed of specularite, limonite and siderite in Jiuquan Iron and Steel (Group) Co Ltd. Some technologies have been used to improve SHP-3200 HIMS, including modifying the angle of magnetic polar from 90¦ to 83¦, cooling the exciting coils by oil instead of air, adding reverse-washing equipment to wash off magnetic particles and adjusting the tooth-space of the matrix from 5.0 mm to 3.5 mm or 2.5 mm to enhance the recovery of fine particles. It is still difficult to meet the requirement for recovering more difficultly separated iron and the demands for high-grade concentrate of iron. In order to improve the recovery of difficult-separated iron, the film-magnetic separation technique is applied into the HIMS and a new LY matrix is designed to form magnetic gradient vertically. A flowing-film feeder is also added and the feed mouth is modified to make a slurry flow formed in the form of film along the wall of matrix. The microstructure and dissemination character of the mineral particles is studied, and the specific susceptibility of the primary minerals is measured. Then the distributive characteristics of a magnetic field for the separator with film-magnetic technique and the motion of particles in the process of separation are all analysed. By introducing the film-magnetic separation technique to SHP-Φ700 HIMS, the recovery of iron can be raised from 69.45 per cent to 76.07 - 78.96 per cent with the similar grade of concentrates of iron. Such an increase of 9.51 per cent in the recovery also shows that it is feasible for such film-magnetic separation technique to be applied into HIMS.

Jan 1, 2005

By Umetsu Y, Su Qing-quan

The electrical conductivity of electrolytes is very important in metal electrowinning and electrorefining processes as it has a very large influence on the energy consumption. There are few measurements of the electrical conductivity of zinc electrowinning electrolytes available. The electrical conductivity of zinc electrowinning electrolytes were measured over the following range of concentrations, 100 to 200 g/L H2SO4, 0 to 80 g/L Zn and 0 to 20 g/L Mg, at temperatures from 25 to 60 C. The specific conductivity of zinc electrowinning electrolytes may be expressed as a function of concentrations of sulphuric acid, zinc and magnesium and temperature by the following equation: k(S/cm) = 0.004 + 0.00115 t + 0.00282 [H2SO4] t - 0.00114 [M] t + 0.3442 [H2SO4] - 0.0451 [1-12SO4]2 - 0.1058 [M]ò[H2SO4] - 0.0224 (M] + 0.0286 [M] 2 where t is temperature (C), [H2S04](moI/L) is sulphuric acid concentration and [M](mol/L) is a sum of zinc and magnesium concentrations, ([Zn]+[Mg]). The specific conductivity of zinc electrolytes is a function of the concentrations of the hydrogen ion and free water molecule, which are calculated by taking into account the second ionisation constant of sulphuric acid and the stability- constants of zinc-sulphate and magnesium-sulphate complexes at 25 C.

Jan 1, 1993

By S Basu, P M. Midhun

Electro-Slag Remelting (ESR) is a process capable of producing ingots with much lower centre-line segregation and better internal soundness than conventional ingot casting processes, as well as lower inclusion and sulfur concentrations. This process is commonly used for alloyed steels intended for critical applications like components of marine turbines, supercritical powerplants and rocket motor casings. It involves melting a metal electrode using electrical resistive heating in a slag pool and re-solidification of the resulting metal droplets beneath the slag layer, forming an ingot. Conventional ESR fluxes consist primarily of CaF2, Al2O3 and CaO, along with minor concentrations of SiO2, MgO etc. The emission of fluoride vapour from the molten slag causes several environmental and health problems, triggering a need to develop and reduce the fluoride content in the ESR flux. The present study aims to develop low-CaF2 alternatives to commercial ESR fluxes without compromising on productivity and the surface quality of the refined ingot. Thus, the modification in chemical composition needs to satisfy properties like electrical resistivity, viscosity and liquidus temperature, essential for efficient ESR operation. Since electrical resistivity and viscosity are highly dependent on the ionic structure of the molten slag, it is important to understand the effect of compositional modification on the structure of the flux. The present study employs Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy to investigate the structural variations in the modified fluxes, especially the effect of changing SiO2 concentration, in comparison with conventional CaF2-rich fluxes. Additionally, thermal analysis (Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA)) has been carried out to characterise the melting behaviour of the fluxes. The findings are compared with simulations carried out using the FactSage™ software, ver 8.3 (GTT Technologies, Aachen, Germany). Simultaneous analysis of liquidus temperature and the structure is expected to help in identifying the practical suitability of modified ESR flux compositions for industrial implementation.

Jun 19, 2024

By D E. Thorp

The mining and concentration operations of New Zealand Steel have been carried out initially from the Waikato North Head (WNH) deposit since 1969 and subsequently from the Taharoa deposit since 1972. Over the years the WNH operation has produced about 1.2 million tonnes of concentrate which has been converted into steel, while total exports to the Japanese Steel Industry from Taharoa reached five million tonnes in February of this year. Recent expansion plans both in domestic steel production and in the ironsand concentrate export market have made it necessary for the company to look closely at, among other areas, the mineral processing of the titaniferous ironsands in both deposits. This paper deals with the recent test work carried out at WNH and Taharoa on the use of the cone concentrator unit as a primary gravity concentrating unit ahead of the magnetic separation stages and as a cleaner concentrator following the primary magnetic separation.

Jan 1, 1977

By D Craw

Otago Schist and Klondike Schist are two Paleozoic-Mesozoic metamorphic belts on the circum-Pacific margin in which there has been a long history of abundant alluvial gold mining, but only minor hard-rock gold mining.   Modern exploration for hard-rock gold is ongoing in both belts, and the active Macraes mine in Otago (>2 Moz production) highlights the hard-rock potential of the geological setting of these belts. Hard-rock gold mineralisation in both belts formed in the latter stages of schist exhumation, after rocks were subjected to major regional ductile folding and then uplifted through the brittle-ductile transition. The majority of known hard-rock gold-bearing systems in both belts consist of well-defined, but generally discontinuous, vein swarms. Most Otago veins are hosted in steeply dipping post-metamorphic normal faults and fractures. However, the Macraes mine is hosted by a late-metamorphic shear zone, and much ore is sulphide-impregnated auriferous schist. Goldbearing veins in the Klondike schist are hosted primarily in extensional sites associated with post-metamorphic compressional structures. Some disseminated sulphide mineralisation is associated with Klondike veins and this is important as it extends the exploration target for these veins. No foliation-parallel late metamorphic mineralisation has been identified in the Klondike but exposure is relatively poor compared with Otago and both schist belts are highly prospective for deposits of this type.

Jan 1, 2007

By Lynch P

Oaky Creek Coal Pty Ltd. currently mines high quality coking coal from both underground and open cut operations at its Oaky Creek Mine. Coal is transported by rail to the Dalrymple Bay Coal Terminal south of Mackay and to the Gladstone Coal Terminal. Oaky No.1 Underground Mine, Open Cut and Highwall Mine have concentrated on seams from the German Creek Formation, one of the major productive coal measure formations in the Bowen Basin Coalfields. (Fig. 1) location map.

Jan 1, 1998

By Laing W. P, Neill D. M, O&apos

The Reward polymetallic massive sulphide deposit occurs 35 km south of Charters Towers, adjacent to the Highway gold deposit (Fig. 1). It is hosted within rhyolitic lavas and interlayered volcaniclastics of the Cambro-Ordovician Mt Windsor Volcanics. Reward is a "blind" deposit discovered in 1987 after a long history of exploration by various companies in the area. The main pyrite dominant massive sulphide body occurs under 100m combined thickness of Tertiary fluviatile sediments overlying deeply weathered gossanous volcanics. The exploration case-history provides a striking example of how geological and structural models can be built up almost exclusively from drill information. Four different styles and ages of mineralisation are present: 1) volcanogenic Cu+Pb+Zn+Ag+Au massive sulphides of probable syngenetic origin; 2) remobilised Cu+Au in massive pyrite of metamorphic/deformational origin; 3) supergene and 4) oxide Cu+Au mineralisation of weathering origin. The massive pyrite body, containing chalcopyrite lenses, transects the stratigraphy and is inferred to contain in excess of 5 million tonnes. Overlying the primary mineralisation a supergene chalcocite rich zone contains a measured/indicated resource of 634,231 tonnes of 6.77% Cu which includes 287,000 tonnes of 1.32 g/t Au and 18 g/t Ag. In addition a measured/inferred oxide resource of 309,000 tonnes of 5 g/t Au and 27 g/t Ag overlies the supergene zone.

Jan 1, 1989

By Bothe C

Froth flotation processes use different surface properties of the minerals to be sorted. In an aqueous environment the hydrophobic mineral attaches selectively to air bubbles and is lifted to the surface of a separation vessel, while the tailings settle towards its bottom. Besides the surface properties, the hydrodynamic conditions play an important role. With respect to the hydrodynamics the flotation process can be divided, for simplicity, in two sub-processes. The attachment of hydrophobic particles to air bubbles, the so-called mineralisation, demands a large number of collisions and therefore high turbulences. The phase separation however needs a deterministic movement of both the particle-bubbles-aggregates and the tailings particles and therefore a quiescent flow field. The optimisation of the overall process requires a separation of both sub-processes, especially when fine particles have to be sorted. In conventional mechanically agitated flotation cells both sub-processes take place in the same turbulent volume. For this reason they suffer from a decreasing selectivity with decreasing particle size. In flotation columns the mineralisation of air bubbles and the phase separation are performed in a quiescent environment. This results in high concentrate grades and at the same time in a very slow attachment kinetics, which must, especially for fine particles, be counterbalanced by a long residence time of the slurry.

Jan 1, 1993

By S T. Jarvis

Colliery spoil is the major constituent of colliery spoil ærockpasteÆ which has been used to infill abandoned limestone mines in the West Midlands of England since the early-1980s. The other constituents of rockpaste are pulverised fuel ash, lime and water. A key property of the rockpaste is its ability to flow within the mine workings over considerable distances before setting. This paper describes the work carried out to identify suitable sites as sources of colliery spoil for making rockpaste and goes onto consider the flow properties of the material and the monitoring methods used on-site. A full-scale trial comprising infilling a 6600 m3 section of an abandoned mine was conducted prior to the infilling of the Littleton Street Mine which had a volume of about 500 000 m3. As well as describing the methods used for monitoring the movement of rockpaste material, a description is also given of a dip-meter developed specifically for the purpose of measuring the level of paste in the mine. This paper shows how a colliery spoil based paste has been successfully used for infilling abandoned mine workings. The monitoring systems developed for use in the two case studies presented in this paper are now being used extensively for infilling other abandoned mine workings. To-date over 11 mines with a total volume exceeding two million cubic metres have been backfilled.

Jan 1, 1998

By Hiddlestone D. C

Effective exploration, testing and analysis is essential for good process design and optimisation of coal preparation plants. Coal processing relies on the sizing and washability characteristics of the particular coal to define the most cost effective design to meet the market requirements. Flowsheet development and equipment selection is dependent on the natural quality characteristics of the coal, its physical properties and the value of the final product in its market. The methodology of process selection and the key elements in design are discussed. Coal is consumed in two general markets: ò steaming coal - both domestic and export, and ò metallurgical coal. This paper discusses the typical economic analysis required to evaluate the potential for, and cost benefit of, providing the flexibility to switch coals between markets. A case study illustrates the methodology of process selection in a typical high value metallurgical coal.

Jan 1, 1997

By Buisman C. J N, Koch R. O

Soil and groundwater beneath the Budelco zinc production plant at Budel-Dorplein (The Netherlands) are contaminated with metals and sulphate. To avoid contamination of nearby drinking water aquifers in the very distant future, a geohydrological containment system (GCS) and a microbial treatment plant for extracted contaminated groundwater have been developed. As a first step in the design of the system groundwater data from over 150 wells and geological profiles were used to model geohydrological conditions beneath the site. Several configurations of water-extraction wells were deduced from the model. Data gathered during additional fieldwork were then used to improve the model. Finally results that were calculated for the various configurations were used to select an optimal groundwater containment system. Currently some 5000 m3/day groundwater are extracted from a combination of 12 shallow and deep wells. Heavy metals and sulphate have to be removed from the extracted water before it can be discharged into the river system or used as process water. Several water treatment methods have been studied and pilot-tested at the site. The preferred and selected process is based on the activity of sulphate reducing bacteria (SRB) and combines sulphate removal and heavy metal removal in one single step. The anaerobic bacteria reduce the sulphate to sulphide resulting in the precipitation of metal sulphides. A pilot plant gave promising results and a commercial-scale plant has been designed. The proposed design has been tested in a demonstration plant which included all main process units. Test results for all process units are presented. The collected information was then used to optimise the design of the commercial-scale plant. Special attention was paid to automation and safety items. Construction of the plant was finished in May 1992. Start-up, commissioning and operational experience are reported. The concentrations of metals and sulphate in the effluent of the SRB water treatment plant are well within the limits set by the authorities for discharge to public waters.

Jan 1, 1993