Search Documents

By Ralph B. S

Bacterial leaching of low grade quartz felspar porphyry copper ore was studied in large-scale laboratory percolation leaching columns.Limitations in the release of soluble copper showed up before fifty per cent recovery, due to occluding precipitates of iron oxides and hydroxides. Precipitates were removed by increasing the acidity of irrigation feed four-fold with respect to sulphuric acid. However, irrigation at low pH (pH 1.5) inhibited copper leaching. Resumption of bacterial leaching at pH2 was achieved by introducing a period of non-irrigation. The results suggest a 'direct' attack by bacteria on the chalcopyrite substrate rather than an 'indirect' ferric-leach mechanism.

Jan 1, 1981

By M P. Simpson, J L. Mauk

The Golden Cross, low-sulfidation, epithermal deposit shows a number of features that are directly or indirectly related to boiling hydrothermal fluids. Occurrences of lattice calcite and their quartz pseudomorph equivalents in veins, and occurrences of adularia in veins and in the surrounding altered rocks in the vicinity of ore, are both direct evidence of deposition in the presence of boiling hydrothermal fluids. Loss of carbon dioxide causes calcite deposition (platy variety) near the level of first boiling, while adularia deposits due to the attendant pH increase along the cooling flow path. Indirect evidence of boiling include crustiform-colloform quartz banding, late massive calcite veins, clay-carbonate alteration in the shallow and peripheral parts of the ore zone, and the restricted vertical interval of precious metal mineralisation. The colloform quartz banding strongly resembles the banding in amorphous silica deposits found in geothermal surface pipes. This implies that fluids ascending the Empire Vein structure were saturated in amorphous silica. If so, then they must have undergone phase separation, which initiated at considerable depth (e.g. =1000 m) and very hot temperatures (e.g. =300¦C). On the basis of stable isotope data, late massive calcite veins appear to have deposited from CO2-rich steam-heated waters. Calcite deposited along heating paths as these waters descended into the upflow zone during late stage collapse of the hydrothermal plume. In active systems, such steam heated waters form by deep boiling. The high CO2 contents of these waters promote hydrolytic alteration and the formation of clay-carbonate alteration. Reaction path modelling using CHILLER and a deep, Broadlands-Ohaaki water as an analogue, shows that minerals deposit along boiling flow paths over discrete spatial intervals. Calcite and adularia deposit near the site of first boiling, followed by gold and then by amorphous silica. For deep boiling starting at 300¦C, these minerals deposit over a path length that exceeds 1000 m. The distribution of banded quartz and gold at Golden Cross are consistent with such a boiling model. However, the elevation of first boiling must have fluctuated over 500 m to account for the coincidence of lattice quartz (pseudomorphs of platy calcite) and adularia, crustiform-colloform silica and gold over distances of a few centimeters in veins. We deduce that a downward propagating boiling front and expansion of two-phase flashing in a flowing water column occurred during episodes of high vertical permeability and fluid flux in the Empire vein structure.

Jan 1, 2000

The Goonumbla district of central-west New South Wales, Australia, hosts four significant porphyry Cu-Au deposits that contain a combined probable ore reserve of 71.7 million tonnes at 1.2 per cent Cu and 0.5 g/t Au. Mineralisation in the Goonumbla deposits is associated with narrow, pipe-like intrusions of quartz monzonite porphyry, in which several intrusive phases have been recognised. Five textural characteristics have been used to distinguish the various intrusive phases recognised in the Goonumbla porphyry deposits: (1) phenocryst abundance; (2) nature of the groundmass; (3 and 4) proportion and mineralogy of the mafic and non-mafic phenocrysts; and (5) the presence or absence of anhedral quartz grains in the groundmass. In addition, each intrusive phase is classified according to its estimated original quartz, alkali feldspar and plagioclase contents. Features common to all of the intrusions are that they contain two types of plagioclase and two or three types of K-feldspar phenocrysts in variable proportions. Most of the intrusions also contain apatite micro-phenocrysts. The groundmass textures range from aphanitic through granular to euhedral K-feldspar in a quartz matrix. With only one exception, all of the intrusive phases recognised are either quartz monzonite porphyry or mafic (>5 per cent mafic minerals) quartz monzonite porphyry. The exception is a biotite - phyric monzodiorite, which occurs in the basal portions of one of the deposits. Textural variants of intrusive phases at Goonumbla have been investigated to establish whether specific combinations of characteristics indicate mineralised intrusions, while others suggest barren ones. Some correlations between intrusion types and Cu and Au grade have been recognised. The most important textural characteristic that relates to high grade mineralisation appears to be the low proportion of mafic minerals, because the quartz monzonite porphyry intrusions hosting most of the mineralisation in the two deposits studied contain

Jan 1, 1999

The Sons of Gwalia Mine in Western Australia is situated about 140 miles north from Kalgoorlie in arid country, where supplies of fresh water are difficult to obtain.Mine salt water is used throughout the treatment plant, whilst fresh water for domestic, boiler, and power purposes is pumped from a number of shallow outlying wells. The waters from all wells are constant in character, although they vary in the quantities of salts contained.An average sample of mixed waters gave the following analysis (Gr. per gal.):Sodium chloride 70.82Magnesium chloride 33.03Calcium chloride 26.98Calcium carbonate .. 11.57Calcium sulphate 22.71Iron oxide and alumina 2.10Silica and insoluble 4.58When this water is used in the boilers in its natural state it is scale-forming and intensely corrosive.

Jan 1, 1927

A number of terrane reconstructions conflict with global plate histories or with data from adjacent regional studies. Paleogeographic maps have ignored terranes thus are over-simplified. This paper represents an attempt to "marry" Mesozoic global plate reconstructions and terrane analysis to produce examples of a "third generation" of global plate tectonic maps. The best approach to global terrane analysis involves intercomparison of all regional data and the evolving global model. Data conflicts within and between terranes and regions must be resolved by a system of relative data reliability "weighting." The most reliable and useful data are those which constrain "departure" (rift) and "arrival" (collision) times. Certain ad hoc decisions aid in the analysis (e.g. only one net vector allowed per plate). The maps that follow summarize Early Mesozoic global tectonic history at three critical junctures: 240 MA (Triassic); 180 MA (Jurassic); and 120 MA (Cretaceous). Due to space limitations, maps drawn at 20 m.y. intervals appear elsewhere. A preliminary Middle Triassic reconstruction is presented in Figure 1. Major plates and continental blocks are labeled; smaller blocks are marked with abbreviations. Examination of Figure 1 indicates the necessity of modeling Triassic tectonics with at least 68 blocks. Spalling- off of microcontinental slivers from Gondwanaland is active some 70 m.y. before the actual breakup of the supercontinent. In the SW sector of the Pacific, the Australian margins were embroidered with several terranes (e.g. Sumba) which eventually rifted away and crossed Tethys. The NW sector at this time included 10 microcontinental chips forming a huge archipelago along the Asian margin. All blocks inboard of Indochina collided by latest Triassic. Terranes of the NE sector include several (e.g. Arctic Alaska) along the North American margin, and at least six large blocks (e.g. Stikinia) drifting SE with the Farallon Plate. The SE sector

Jan 1, 1987

Attempts to rationalise the geological environment of nickel sulphide deposits associated with Archaean ultrabasic rocks has produced much speculation as to the origin of the sulphides and the relative importance of geochemical, mineralogical, textural and structural characteristics of the host rocks. From an economic viewpoint the object of such work is to establish geological criteria which can be used as an exploration guide. Exploration procedure for nickel sulphide mineralisation of the 'Kambalda type' (Hudson, 1972), which occurs at or near the basal contact of Archaean ultramafic flow units and lenses consisted of geological mapping, surface prospecting with soil sampling and rock geochemistry.

Jan 1, 1987

By D Laurence, L Ge

This paper demonstrates use of remotely sensed imagery in promoting sustainable mining. Remote sensing technology can be used during all phases of a mining project û from evaluating the resource, to making extraction more cost-effective, through to monitoring, mine closure and remediation. Use of the new generation of satellite platforms with the capability of acquiring satellite data with higher spectral and spatial resolution have the capability to emerge as essential indicator for sustainable development in the minerals industry. A life cycle approach to satellite imagery is discussed. The use of an imagery of the site prior to mining activity establishes the environmental baseline, guides mitigation measures and eventual help in suggesting remediation. Remote imagery provides the cost-effective means of monitoring reclamation, including the growth of planted vegetation, of the mine site and surrounding area. The latest advancements in satellite remote sensing are highlighted to meet the newer challenges of sustainable mining practices. Some of the worldwide successful remote sensing applications for the measurement and evaluation of the sustainable development impact of mining operations are described. Presently available source of imagery and its comparative advantages and disadvantages are provided as a guide. Finally, the limitations of this tool are indicated.

Jan 1, 2009

In line with DML Resources continual forward management policies, the Roscommon Quarry operation has recently installed and commissioned a Nordberg 7 ft Symons cone crusher and a HP 300 cone crusher. Both machines have enhanced the production capabilities and quality control of the Roscommon comminuition circuit and they will provide efficient and reliable crushing well into the next century.

Jan 1, 1994

Operations of the new copper smelter at Mount Isa commenced on the 6th February, 1953. Prior to this date a paper by R. V. Anderson (1953) outlined the smelter layout, proposed operation and expected performance.Nominally a 50-ton per day plant, output is currently at the rate of 85 long tons per day. In the first 3t years, of operation to 30th June, 1956, '71,339 tons of blister copper were produced. Operation has been stabilized' and a number of modifications to plant and operation have been made. This paper reviews the progress made to date.GENERAL LAYOUT AND EQUIPMENTThe general layout and equipment follows well-established practice as study of Figs. 1 to 4, and Appendix II will show. This diagrammatic representation of layout (Fig. 1) and flow sheet (Fig. 2) is intended for the purpose of brevity to take the place of a detailed plant description.Choice of site for the smelter was limited by the necessity for close proximity of the waste heat boilers to the powerhouse.Much excavation was necessary before foundation work commenced, but the plant is compact and further expansion is possible.CHARGE MAKE-UPRoaster charge initially comprised concentrates, purchased ores, revert materials, mine sulphide ore and barren sand. As purchased ore receipts increased and as domestic black rock oxidized ore became available, the latter two fluxes were eliminated from the charge. Fluxes at minus i-in. sizing are trucked from crushing plant or stockpile by motor lorries. Filtered mill concentrates are dropped from an overhead conveyor on to the storage patio floor adj acent to the two concentrate bins.

Jan 1, 1957

By R J. Merchant

The Hauraki goldfield is located east of Auckland in the North Island of New Zealand. It includes Great Barrier Island, the Coromandel Peninsula and the Coromandel and Kaimai Ranges as far south as the town of Te Aroha and south east to Te Puke. It has a total north-south extent of about 180 km and an area of 3000 km2. The goldfield is the most productive in New Zealand, and while production at present is negligible, the area has undergone continuous exploration over the last seven years.

Jan 1, 1984

By R Sridhar, M Fe, W G. Bacon

The problems of magnetite build-up have plagued the non-ferrous pyrometallurgical industry for many years. To better understand these problems, a study was undertaken to determine the thermodynamic variables that affect the behaviour of magnetite under different smelting conditions. Equilibration studies were performed in the nickel smelting systems of matte-gas and matte-slag(silica saturation)-gas. The relationship of thermodynamic variables such as temperature, sulphur and oxygen partial pressure and matte grade on iron and magnetite activities were calculated and the significance on smelting parameters such as metal losses and partition coefficients were defined. The experimental data from this study were employed to develop practical methods which could be used to control the build up of magnetite, as well as to obtain additional metallurgical benefits. In general, a lower sulphur partial pressure and higher temperature operation was shown to enhance the metallurgical benefits of nickel smelting by decreasing the magnetite activity. Operating in this manner can also have added benefits such as higher metal recoveries, more efficient vessel utilisation and efficiency and lower smelter emissions at equivalent or higher primary furnace matte grades.

Jan 1, 2000

The process of electrostatic separation was developed in the late 19th century, but did not make much headway for about 25 years. High dc voltages, of the order of 20 kilovolts, are involved, and the only means of obtaining such voltages at that time were by the use of frictional machines, such as the Wimshurst. These were not reliable, for two reasons:-a. If a spark discharge occurred it took an appreciable time before a steady voltage was again attained.b. In damp weather the machines were almost useless.In the first 20 years of the 20th century the advent of mechanical and vacuum-tube rectifiers led to promising developments of 'the process. In the early 1920's flotation became widely used commercially, and proved to be more reliable, and capable of wider application, than electrostatic separation. During the last 15 years or so, with a better knowledge of the fundamentals forming the basis of the process, electrostatic separation is beginning to compete with flotation, especially in the treatment of smallsizedgranular material, such as beach sands. Electrostatic separation can be, and is, widely used in many cases where flotation is impossible, such as in the cleaning of food products which must be kept dry.

Jan 1, 1950

By H J. Stedman

A Transient Electromagnetic (TEM) geophysical survey was trialled in Bowen Basin Permian coal measures overprinted by Cretaceous intrusion. The trial’s intention was to compare whether TEM could assess residual coal more accurately and economically than drilling.TEM results were promising but had limitations. TEM did not compare to drilling for defining coal thickness or relative level definition. However, TEM resolved conductive anomalies laterally; providing a qualitative picture of remnant coal.Three material types and associated conductivities occur within the trial area: overburden (sandstone/siltstone), intrusive sills and heat affected coal.Ground conductivity was analysed by measuring decay of residual current within the TEM loop. Fast decay related to resistive overburden and intrusion, attenuated decay related to conductive coal.Generally speaking, carbon content governs coal resistivity where good quality, low ash, bright coal is more resistive relative to dull, high ash coal. Though in the trial area, relative to intrusion and overburden, coal was found to be the most conductive of the three materials.By modelling conductive anomalies, a general picture emerged of remnant coal regions. Subsequent highwall exposure reconciled with conductive TEM anomalies.CITATION:Stedman, H J, 2017. Findings from a transient electromagnetic trial for heat-affected coal, in Proceedings Tenth International Mining Geology Conference 2017, pp 233–238 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By S Benson

Staurolite is one of the major contaminant minerals contained in the Tiwest Cooljarloo orebodies. Approximately 80 per cent of staurolite in mined ore, reports to the heavy mineral concentrate that is supplied to the Dry Mill. Staurolite in heavy mineral concentrate is typically five per cent by weight and has no significant effect in the Dry Mill other than to occupy equipment space, reporting as a tailing, that requires transportation and disposal back to the mine site. Staurolite is an aluminosilicate with a MohÆs hardness of 7.5. It is known to have potential as an abrasive blast agent and it is produced in substantial quantities in the USA for that purpose. Research indicated that there was potentially a market for staurolite within Australia, as a replacement for some of the lower grade abrasives as well as a material of choice. A small tonnage of staurolite product was manufactured through a simple circuit within the Dry Mill in December 1998. This was subjected to industrial scale tests by external companies specialising in sand blasting. The most significant batch of tests were conducted at the Tiwest Chandala site on plant and equipment undergoing corrosion repairs. Staurolite was tested against three other commercially available abrasives and compared very well with respect to surface profile, surface texture, coating adhesive strength and dust generation. As part of a due diligence study, free silica, radiation and heavy metals contents of spent abrasive and dust was investigated. This information was needed to seek approval from the appropriate Western Australian statutory authorities to sell staurolite as a product. Approval was received in November 1999. Tiwest has since installed a production circuit in the Dry Mill capable of producing 20 000 tpa of Staurolite.

Jan 1, 2001

By G J. Massoth, K Faure, A G, R G. Ditchburn, I J. Graham

From modest beginnings in 1996, research into the mineral potential of New ZealandÆs Exclusive Economic Zone has progressed into a major multidisciplinary component of GNSÆs recently funded 6-year æMineral Wealth of NZ and its EEZÆ Programme. In excess of $7.5 M of research funding has been expended, plus $10 M leveraged via collaborations with NIWA (NZ), NOAA (USA), JAMSTEC (Japan), U. Kiel (Germany) and ANU (Australia), whose scientists have contributed hugely to research cruises, as well as subsequent analysis and publication. The 1999 NZAPLUME I cruise was the first research expedition to systematically locate, and chemically characterise, submarine hydrothermal venting associated with arc volcanoes of the southern part the Kermadec intra oceanic arc system. This was followed by the 2002 NZAPLUME II and 2004 NZAPLUME III cruises to the mid- and northern-sections of the Kermadec arc, respectively. Combined, these cruises have surveyed 1300 km of the volcanic chain (from Whakatane to Monowai), including 34 major volcanic centres. Together with concurrent surveys in the Tonga arc, this is now the longest continuous stretch of intra oceanic arc to be surveyed for hydrothermal emissions. Most of the volcanic centres are characterised by simple cones although 30 per cent contain caldera complexes, and compositions range from basalt through to rhyolite. Massive sulphide mineralisation has been recovered from several volcanic centres in the southern Kermadecs (Clark, Rumble II West and Brothers), suggesting the existence of significant Au and base metal bearing deposits along the arc front.

Jan 1, 2005

Grey River Gold Mining Ltd commenced dredging alluvial flats in the Grey River Valley in 1989. Previous drilling indicated over 100 million cubic metres of gravels with some 90 per cent of the gold in the bottom seven metres. The dredge built by Rahco, Spokane, was innovative in a number of aspects but particularly in the fact that a separate ladder with a cutter and pump was used to strip the overburden and a bucketline to mine the gold bearing wash below. Metallurgical studies and exploration were initiated when the project commenced. Leasing and environmental considerations were investigated and action taken. While progress is being made, the operation at this stage is not meeting required production and performance. Main problems have been with the stripping system and wear.

Jan 1, 1990

Several glacial episodes have been distinguished in the Shotover Valley. These produced fluvioglacial aggradational deposits downvalley from the terminii, commonly with well-preserved terrace treads, as exemplified near Skippers. Chronological links can be determined between the Shotover tills and sediments and assessed equivalent deposits in the Wakatipu Basin/Kawarau Valley region through axial valley profiling. Constructed relationships suggest older Shotover events were probably large and left little detrital deposits within the valley. In contrast, the younger advances were smaller and valley-constrained. They are modelled as being wholly of Waimea or Otira Glaciation age, advances from the latter period producing the visually distinctive flights of terraceremnants. Both the terraces and the inner gorge, now occupied by the Shotover River, have been extensively worked for alluvial gold. Enrichments in the former environment have predominantly been as bottom or intermediate lags produced during degradation phases of catchment erosion. Surface lags have been locally targeted. Placer mining in terrace areas involved both tunnelling and sluicing techniques. In the modem river the greatest concentrations were on the schist or false bottoms, although flood gold has always contributed to the returns. Placer mining techniques here were highly variable.

Jan 1, 1998

The Southwest Pacific is a region of active volcanism and geothermal systems. Only in New Zealand have the geothermal systems been exploited for electricity generation and industrial processing. At present, approximately 280 MWe of geothermal electricity is generated in New Zealand. A considerable amount of further exploration work is required before the total geothermal potential of the region can be assessed and before the significance of these resources can be judged against other local energy sources.

Jan 1, 1990

In the estimation of reserves the known values of the variables of interest from surrounding drill holes are used to compute or estimate the unknown value of the orebody over a given region or at a given point of interest. The classical means of doing this are: 1. The Polygonal Method û where the region is divided into polygons centred on bore holes, each variable is then assumed to have constant value over each polygon. 2. Inverse distance methods, where the variable is assumed to vary linearly with the distance between the known values of the drill holes. 3. Inverse distance squared method û a quadratic variation is assumed for the variables between the bore holes.

Jan 1, 1983

By H Firdausi, I Pasek, T Chenier

The Grasberg Block Cave (GBC) Mine is one of the future underground mines of PT Freeport Indonesia (PTFI). Located in the remote highlands of Papua, Indonesia, the GBC mine is scheduled to start production in 2017 reaching its peak production capacity of 160 000 t/d in 2023.In order to reach planned production capacity, the GBC mine will utilise an ore handling system consisting of rail haulage, crushing and conveying. The rail haulage system will utilise over 20 km of track while crushing is accomplished by way of three gyratory crushers each with a capacity of 3300 t/h. Nine conveyors operating in two parallel systems, each system over 3 km in length, will move the ore from the crushers to the stockpiles. These systems require a network of larger tunnels and mass excavations to accommodate the planned production facilities.This paper will describe the ore handling system, tunnel and mass excavation methodology as well as some of the challenges encountered with ground conditions and excavation quality during the execution of the project. A combination of lateral and vertical development methodologies and equipment, including drill jumbos, mechanised raise climbers and specialised ground support equipment, have proven successful in the development of a quality ore handling system.CITATION:Pasek, I, Firdausi, H and Chenier, T, 2016. Development of the ore handling system at the Grasberg block cave mine, Indonesia, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 599–608 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016