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By Turco E, Pelizza S, Vona A

Within the project against pollution in the Gulf of Naples (Italy) it was envisaged to build a sewage collection tunnel whose tunnelling section is about 30 m2 and whose length is over 4 km. The formations to be bored through feature heteregeneous volcanic deposits made up of either lenses or lava, lapilli and pozzolan layers and ashstone silts. The cover ranges between 10 and 30 metres. The surface is heavily built-up requiring then an accurate monitoring and reduction of noise, vibrations and settlements. The building of the tunnel is therefore carried out by means of a boom tunnelling machine equipped with a mechanized shield. Support along the complete excavation perimeter is provided by linerplates together with an immediate cement grouting behind them. At a later stage the concrete lining will be cast in place.

Jan 1, 1987

In line with mining operations throughout Australia, Western Mining Corporation Limiter' is striving to increase productivity by intro-ducing mechanized mining techniques wherever possible. Kambalda Nickel Operations' (K.N.O.) largest operating nickel mine, Long Shaft, is currently introducing mechanized cut and fill methods which must provide flexibility to cater for an orebody that variesconsiderably in width, both along the strike and up dip.This has resulted in modifications to the previous approach to primary level develop-ment, and intermediate stope development, and in the type of development and production equipment being employed. Electric-hydraulic diesel jumbos and diesel loaders have now been mated with conventional rail equipment and production airtrack machines are being utilized.The transition to mechanized methods is in its preliminary phase and is being monitored closely to ensure any productivity gains are not offset by a substantial drop in mine grade. The precise method ofmechanized mining has not been finalized and selective methods will be used, according to the ore width and ground conditions, which vary throughout the mine.

Jan 1, 1985

Expansion of the B.H.P. Co. Ltd. mater ials handling facilities, at their Newcastle Steelworks, began in 1964 and continued until 1970. The present complex handles the annual iron ore requirement of some three million tons for the Sinter Plant and Blast Furnaces. Iron ore is discharged from ore carriers and conveyed at rates up to 3,000 t.p.h. to either of two 180,000 ton capacity storage yards, where it is blended using boom stackers. Material is reclaimed from these yards at rates up to 1,000 t.p.h. using a slewing boom bucket-wheel reclaimer and fed to a screening station. Oversize material is scalped out and crushed in a closed circuit cone crusher. Undersize material is sized on double-deck vibratory screens which separate at 1/4in (6mm). The two fractions are blended in two of four 70,000 ton capacity blending yards using slewing boom travelling stackers. Bridge-mounted bucket-wheel reclaimers reclaim the blended piles at 1,000 t.p.h. Fine ore is conveyed to the Sinter Plant and lump ore to a second screening station, for rescreening, before passing to the Blast Furnace.

Jan 1, 1972

By W Lu, D Wang

Study of coal oxidation at low temperatures forms the basis of investigating the inherent properties of spontaneous combustion of coal. In general, the process of coal oxidation at low temperatures is very complex, involving many factors. Experiments examining the properties of oxidation and ignition of coal have been carried out. Based upon the results of these experiments, the catastrophe properties in the process of coal oxidation are analysed and the mechanism of catastrophe is proved for the ignition of coal. A folding catastrophe model is also established for the process of coal oxidation. Results obtained show that the process of coal oxidation to ignition is discontinuous, where the coal-environment system yields structure destabilisation. The system can jump from one stable attractor to another. The research results presented in this paper help to show the irregularities of coal oxidation at low temperatures and how to pursue effective control measures.

Jan 1, 2005

By Ormsby W, Peters M, Van Gils H, Kehprens P, De Boorder H

The northern margin of the Arunta Block is characterized by a metasedimentary and volcanic sequence of lower metamorphic grade than that of the central Arunta Block. Whereas the Harts Ranges have granulite to amphibolite metamor- phic grades, the northern margin only reached greenschist to lower amphibolite facies. Most of the high grade area of the central Arunta Block appears to be unprospective, but the lower grade marginal fringe contains most mineral pros- pects to name a few: Barrow Creek, Molyhill and the Jervois Mine. Numerous smaller prospects occur in this marginal zone. Four major lithostratigraphic units can be recognized in the Jervois Mine area: 1. Gneissic Suite consisting of granitic and rhyolitic gneisses which are characterized by a distinct intersection lineation. 2. Metasedimentary Suite of cordierite- biotite schists and chlorite-biotite schists. 3. Mine Sequence, consisting of spotted schists with andalusite and cordierite, quartz- sericite-feldspar schists with distinct rhyo- litic remnants and quartz-sericite-feldspar schists which contain the lode horizons:

Jan 1, 1984

Blasting in Norwegian mines is often carried out by contractors who tend to look for the cheapest solution, without concern about fragment quality. The requirementsfor a contractor are usually only related to the maximum size of boulders and the quantity per month. Even when the owners of the mine are responsible for blasting, very little effort is made to optimise the blasting process. This paper presents test methods which were used and results from small-scale and full-scale blasting tests. In the small-scale tests, cubes 500 x 500 x 500 mm of four different rock types were blasted in a chamber, using two types of dynamite explosive. The velocity of detonation (VOD) for the dynamite explosives was 3000 m/s and 6000 m/s respectively. Three cubes of each rock type were blasted with each type of explosive, and a total of six cubes of each rock type was used. The entire muckpile (approximately 350 kg) was- sieved and weighed after each blast and fragments between 8-16 mm were tested for impact values and flakiness. The results of these tests clearly showed improvement in fragmentation the closer the acoustic impedance ratio of the explosive (VOD x density) over the rock (Cp density) was equal to one. The results also showed that the quality of the fragments (in terms of impact values) tends to be better when the cubes are blasted with the high velocity dynamite.

Jan 1, 1995

By F Shi, W Valery

WMC Fertilizers (WMCF) operates a Beneficiation Plant at Phosphate Hill in Queensland, Australia. The plant consists of two-stages of crushing, followed by a wet scrubbing and desliming circuit. Ore is then fed to a tertiary crusher and a milling/classification circuit, with the final product going to a swing-lift thickener and storage tanks. From the slurry storage tanks, the phosphate rock is fed to a horizontal belt filters which dewater the phosphate rock ahead of a hemi-hydrate phosphoric acid plant. The water soluble recovery of phosphate in the phosphoric acid plant is dependent on the moisture content in the filter cake, as this governs the wash water addition to the hemi-hydrate filters. Since commencement of operation, the moisture content of the filter cake fed to the phosphoric acid plant has been higher than design reducing the phosphoric acid plant recovery and at times reducing the throughput through the phosphoric acid plant. The moisture content in the filter cake can be decreased by reducing the generation of fines in the milling and classification circuit (classified as û38 micron material). This paper identifies the causes of fines generation in the Phosphate Hill beneficiation plant. It discusses the options that were assessed to minimise fines generation, and outlines the results to date of circuit changes undertaken at Phosphate Hill.

Jan 1, 2003

By Espinosa-Gomez R, Johnson NW

The Copper Concentrator at Mount Isa Mines Limited treats on average 18 000 tonnes/day of chalcopyrite ore containing typically three per cent copper. The main gangue minerals are iron sulphides (-13 per cent) and non sulphide gangue (-78 per cent). In August, 1991, the comminution flowsheet was changed from a conventional circuit (crusher/rod mill/two stage ball milling) to a modem circuit (fully autogenous grinding/one stage ball milling). The 80 per cent passing size of the flotation feed with the conventional circuit was 125 microns. The Copper Concentrator has two parallel grinding lines, two roughing and scavenging flotation lines, and common cleaning, recleaning and retreatment sections. During the first six weeks of the installation phase, one of the two flotation lines was fed by the conventional grinding circuit and the other by the autogenous grinding circuit. Data from parallel surveys and historical data are used to analyse the rougher/scavenger flotation performance before and after the change. The solid and mineral distributions of the flotation feed, the pulp chemistry and the reagent requirements are compared. The mineral liberation before and after the installation of autogenous grinding is compared on a sized basis using data from the 14 consecutive months before, and the seven months after the change. Liberation was measured using the QEM*SEM(*) instrument. The overall effect of the new grinding circuit on the plant metallurgy is also assessed using the copper recovery values, the dilution of the final concentrate and the distribution of copper losses in the final tailings. (*) Quantitative Evaluation of Materials by Scanning Electron Microscopy

Jan 1, 1993

By W F. Bawden, J T. Paynter

This investigation involves laboratory testing and stability analysis of paste fill at the Golden Giant Mine. Site-cast samples are tested in unconfined, confined, and consolidated-undrained triaxial compression. Pore pressures during shear and consolidation characteristics are measured to determine both drained and undrained shear strength parameters and assess the potential for undrained loading. Liquefaction potential is also considered. A limit equilibrium solution is used to obtain factors of safety against failure of the fill during mining of adjacent stopes.

Jan 1, 1998

Better quality at lower cost is today's formula for remaining competitive in a world market. For an integrated steel company, high quality low cost steel production must originate before the blast furnace. In 1979, when U.S. Steel initiated a Quality Management Program throughout its steelmaking operations, efforts began at the coal, ore and flux mines. The objective was to improve the quality and reduce the variability of the critical parameters for steelmaking raw materials, to get the blast furnaces, and subsequently the melt shops, under optimum control. The general details of U.S. Steel's Quality Management Program are discussed and how it was used to promote the desired improvements in steelmaking raw materials. Some of the outstanding results obtained by the cooperative efforts between the mines and the steel plants are reported. The lessons learned by U.S. Steel were through upgrading existing operations and facilities. These principles should now be applied to new projects and the benefits of good quality management should commence from the time new projects are Commissioned.

Jan 1, 1986

By A I. M Ritchie, G P. Timms

Monitoring of water infiltration into WhiteÆs waste rock dump at the Rum Jungle mine site in the Northern Territory, Australia, started in 1983, and has since produced a unique and long-running data set. Following closure of the uranium mining operations at the site, a soil cover was constructed on the dump in 1984 primarily to reduce water infiltration into, and the quantity of low quality effluent out of, the waste material. The performance of the cover in reducing water infiltration has been monitored using ten lysimeters installed across the dump prior to construction of the cover. Over the past eight years or so, the average infiltration rate as measured by the ten lysimeters appears to have risen compared to the early years of monitoring. The significance of this apparent increase is discussed given the variability observed in the data from individual lysimeters, and the variability in the rainfall. Estimates of the infiltration rate as measured by each of the lysimeters are examined using statistical tools. It is concluded that the infiltration rate has increased with time and with increasing rainfall. The increase with time is a stronger factor than the increase with rainfall. It is further surmised that the cover system at the locations of the lysimeters is less effective now at reducing infiltration into the dump than it was when newly installed.

Jan 1, 2003

The ore mined from the Lead Lode of The Zinc Corporation leases consists of a fairly granular mixture of galena, marmatite, chalcopyrite, tetrahedrite, pyrrhotite, pyrite, and lollingite with a gangue association of calcite, quartz, bustamite, rhodonite, mangan-hedenbergite, garnet, fluorite, mangano-calcite and apatite. The silver content of the ore occurs in three minerals tetrahedrite, dyscrasite, and pyrargyrite, the last two mentioned occurring in microscopic association only. Other metallic and gangue minerals are also present in this complex mineralogical association, but do not influence the milling operations.Fortunately, the silver minerals favour the galena and chalcopyrite as their host minerals, thus facilitating the recovery of both copper and silver in the lead concentrate. The ore from the Lead Lode assays from 14 - 18 per cent lead; 3.0 - 4.5 oz silver per tonne, and 9.5 - 12.0 per cent zinc.A parallel lode, known as the Zinc Lode, is well developed in The Zinc Corporation leases. This lode assays from six to eight per cent lead, 1.5 oz silver per ton, 18 - 25 per cent zinc with a siliceous gangue. The common Lead Lode gangue minerals, calcite, rhodonite, bustamite - are very rare in present underground exposures. No metallurgical work was done on this ore during the pilot plant operations.The aim in the milling process is to produce:1. A lead concentrate with the maximum economic recovery of lead, silver, gold, copper and antimony, and minimum zinc content.2. A zinc concentrate with the maximum economic recovery of zinc, cadmium, and cobalt, and minimum iron, arsenic and fluorine content.3. A waste residue containing sufftcient granular material to be utilised as underground fill.In considering the economics of the milling practice the above three requirements plus consideration of the tariffs submitted by the purchasers of concentrates were the deciding factors in the evolution of the present milling practice.Towards the end of 1924 The Zinc Corporation Limited added to and adapted the old zinc tailings plant for the treatment of 5000 tons of crude ore per week. This plant, which operated until January 1936, was in general principles similar to the standard Broken Hill methods of ore concentration, whereby the galena was recovered by the gravity concentration methods of jigging and tabling with selective flotation concentration of the residual galena and marmatite. One important difference from other Broken Hill plants was that the primary grinding of the jig tailing was performed with flint-loaded mills operating in closed circuit with revolving screens. Two primary grinding sections were installed, each consisting of two 5 ft diameter by 10ft long tube mills loaded with flint pebbles working in closed circuit with four 3 ft diameter by 3 ft wide revolving screens covered with 22mesh Toncap woven wire screen with 0.57 mm opening. Each section carried a circulating load of 28.3 tons per hour for a jig.

Jan 1, 1994

By R Loweth

The application of discreet event simulation has matured in modelling manufacturing systems for production analysis. This simulation tool was used in studying a number of mining operations, especially material handling processes. The study of truck-shovel operation including equipment matching, selection, and production estimation utilised the discrete event simulation for providing valuable decision-making information. The sophistication of the available simulation tools grew over times, and simulation driven animation was used to facilitate the validation and visualisation of the simulated system. This form of visualisation enhanced the simulation use greatly. First of all, it provided a communication medium to transfer information to the non-technical managerial personnel as a better decision-making tool. Moreover, the animated visualisation provided a validation tool to check the working of the simulated system and interaction among its components.

Jan 1, 2003

In the Massif du Sud ophiolite complex platinum group elements occur predominantly as ultrafine-grained inclusions of rutheniridosmine, laurite and iridosmine. These form primary inclusions less than 5 to 10 um in diameter within chromite in podiform chromitite fringed by dunite, and emplaced subsequent to solidification of the host harzburgite. There is no specific association with trace inclusions of transition metal sulphides. The crystallization of then: Ir. Os and Ru minerals may have occurred concomitant with hromite, perhaps related to more reducing conditions produced by crystallization of the chromite. The Ir, Os. and Ru show pronounced fractionation from Pd, Pt and Rh expected to be also present in the mantle source rock. The dunite shows evidence of metasomatic origin from adjoining harzburgite, and the possibility of selective crystallization of the Ir sub-group elements suggests that Pd, Pt and Rh may have been transported elsewhere.

Jan 1, 1989

By G Diprose

Diamond exploration in Queensland is influenced by the South African approach modified by the discovery of diamonds in Lamproite in Western Australia. The current approach is to explore for Kimberlite and Lamproite bodies using indicator minerals dispersed by fluvial and colluvial processes. In the north-west, diamonds are derived from kimberlitic and lamproitic sources, whereas those in the coastal and subcoastal areas of eastern Queensland are associated with xenoliths included in rocks formed during Cainozoic volcanism. In these areas, sapphire is commonly associated with diamonds. In New South Wales diamonds in economic quantities occur in alkali basaltic intrusions and a subduction model has been proposed for these occurrences (Barrows et al, 1996). Exploration for diamonds in Australia increased following the discovery and exploitation of the Argyle mine. State geological surveys have produced digital information on the local occurrences of diamonds. As part of the Smart Mining Initiative (2006 - 2010), the Geological Survey of Queensland compiled a database and report on microdiamonds and diamond indicator minerals from open file company exploration data from 1968 to 2008 from the Department of Mines and EnergyÆs QDEX system. Most exploration in Queensland was conducted with exploration for other commodities. There is no commercial exploitation of diamonds in Queensland and, to date, only rare occurrences of microdiamonds. There is a regional difference in diamond occurrences with the kimberlitic and lamproitic models favoured for the north-western regions of the State and the subduction (S-type model) favoured for the eastern coastal zone linked to Cainozoic alkalic basaltic volcanism. Further diamond exploration is warranted in Cainozoic basalt provinces along the eastern coastal and near coastal regions and in the north-west of the state in conjunction with airborne geophysics flown as part of current Departmental Smart initiatives. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By J Mavrogenes, C J. Spandler, S M. Eggins, K Worden

Major occurrences of platinum group minerals (PGM) are in crustally-contaminated, huge, layered igneous complexes (Bushveld and Stillwater) and gabbroic intrusions (Norilsk); relatively minor occurrences include arc-related æzoned Alaskan ultramaficsÆ. In terms of arc-related provenances, the recognition of alluvial PGM in river and beach deposits of southern South Island (Mitchell, 1995), in situ in the Longwoods (Cowden et al, 1990), and the ultramafic-mafic layered Greenhills Complex at Bluff (Spandler et al, 2000) raise the possibility that some economically-significant PGM deposits may exist in New Zealand. The Longwoods and Greenhills are in the Brook Street Terrane which is a remnant of a primitive intra-oceanic arc system of Late Permian-Early Triassic age. The Terrane comprises volcanogenic sequences containing plagioclase- and clinopyroxenephyric basalts, high-MgO ankaramite and dolerite dikes, trondhjemite plutons, and basaltic to andesitic volcaniclastic and sedimentary rocks. The cumulate complexes contain early-formed olivine- and clinopyroxene-rich ultramafic cumulates overlain by anorthite and hornblende-bearing gabbros. Primary (isoferroplatinum) and secondary (sperrylite) platinum group minerals are preserved in chrome-rich spinel pods in basal dunite of the Greenhills Complex. Saturation during early fractionation of primitive high-MgO magmas rather than magma mixing seems likely for the primary PGM. Together with correlative terranes in Queensland and New Caledonia, the Brooks Street Terrane is an exposed cross-section of an extensive Permo-Triassic island-arc system. Most parental magmas were primitive island-arc tholeiites, but other primary magma-types include high-MgO ankaramites and trondhjemites û the latter formed by partial melting of lower crustal clinopyroxene-rich cumulates and gabbros, respectively. The parental ankaramites fractionated to form mafic-ultramafic cumulates and primitive to evolved melts of high-Al basalt to andesite compositions (Takitimus). The Brook Street Terrane is an analogue for modern intra-oceanic islandarc systems and allows detailed study of subvolcanic arc processes.

Jan 1, 2005

By C A. Foss, K Blay, K Leslie, D Hillan

Magnetic field studies provide remote sensing of magnetisation distributions and a means to investigate moderately- to strongly-magnetised ore deposits that may be partially or totally buried. However, above-surface magnetic field surveys have limited capability to resolve the detail of magnetisation distributions because of the large separation between the magnetisation and the magnetic sensor. While some of this detail is available from magnetic susceptibility logging within boreholes or from magnetisation studies on recovered core, these measurements are limited to the exact trace of the boreholes. The large disconnect between ground or aeromagnetic surveys and highly-localised borehole sampling can cause problems in developing robust source models from magnetic survey data. The measurement of magnetic field in boreholes has the capacity to at least partially bridge that gap by measuring the magnetic field due to magnetisations proximal to, but not intersected by, the boreholes.CSIRO has developed the world’s first downhole magnetic tensor gradiometer. This instrument measures magnetic field gradients in all directions within a borehole. A prototype instrument has been built and tested as part of phase 1 of the Deep Exploration Technologies Cooperative Research Centre (DET CRC). The prototype performed well with magnetic pyrrhotite at the DET CRC test site in the Adelaide Hills and at Carpentaria’s Hawsons magnetite deposit south of Broken Hill. Further work is required to reduce the diameter of the probe so that it can operate in NQ holes (it is currently limited to HQ or wider) and to transform it to a continuous logging tool. The borehole tensor gradiometer can be used to investigate the continuity of magnetisation over a distance of several metres to tens of metres away from a borehole intersection and the structural dip of the magnetic body. It can be used to either replace or augment downhole magnetic susceptibility logging. This instrument is one component of an integrated CSIRO suite of new magnetic field utilities and methodologies for iron ore exploration and development.CITATION:Leslie, K, Foss, C A, Hillan, D and Blay, K, 2015. A downhole magnetic tensor gradiometer for developing robust magnetisation models from magnetic anomalies, in Proceedings Iron Ore 2015, pp 299–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Woodcock JT, La Broody SR

As part of a project on the application of thiourea leaching to a variety of Australian ores, the systematic variation of pH, redox po- tential, and thiourea concentration were in- vestigated on an oxidized gold ore from the Nevoria mine, WA. Stirred open beaker tests were conducted with a pH-stat and Eh-stat system to automati- cally control pH and redox potential at selected values, while thiourea concentration was main- tained manually. Increasing the acidity of the leach liquor from pH 3.6 to pH 1, increased the gold extrac- tion from 37 per cent to over 90 per cent in S h, but there was only a limited improvement below pH 1.5. Silver extraction and thiourea consumption increased as the acidity was in- creased. Increasing the redox potential from 150 to 200 mV (i.e. potential of Pt electrode vs SCE) increased the initial rate of gold and silver extraction, but the effect on cumulative gold extraction by 5 h was slight. Thiourea consump- tion was greatly increased as the redox poten- tial was increased. An increase in thiourea concentration from 1.2 to 4.8 per cent increased the initial rates of gold and silver extraction, but, as for the change in Eh, the improvement in cumulative ex- traction by 5 h was marginal. Thiourea consump- tion increased with thiourea concentration.

Jan 1, 1984

By Hoffmann CF, White NC, Tedder IJ, Wood DG

Since the discovery of Pajingo in 1984, the northern Drummond Basin has emerged as a significant new gold province, and has become the focus of intense exploration for epithermal gold mineralisation. Prospects in the Conway area are hosted by felsic to intermediate lavas and volcaniclastic rocks near the base of the Drummond Basin sequence. These Drummond Basin rocks appear to represent favourable hosts to mineralisation because they are cut by structures which could have focussed and channelled fluids on a regional scale, and because they constitute a possible source of gold and, perhaps more significantly, sulphur for the transport of gold. Prospects in the Conway area are up to 15 km2 in area, and are of the adularia-sericite type. They illustrate many of the classic features (siliceous sinters, alteration mineralogy, and fluid characteristics) recognised in epithermal deposits. K-Ar dating of sericite alteration in three of the prospects has produced a range of ages from 283 to 334 Ma, suggesting that the systems are the product of multiple hydrothermal events.

Jan 1, 1990

Large Off Highway Trucks operated in this country are generally of Diesel Electric Drive, this system tends to employ the familiar Electric Wheel. A number of fleets now employ the Traction Motor System as an alternative. An investigation is made of the operation of two such fleets. A brief description is given defining the components and their basic functions in each system. Available life history is presented and system reliability, maintainability and operator reaction is examined. Trlmnnnr rpm rn~r In the past large Off Highway Trucks operated in this country, that is those greater than say 120 tons, have tended to be driven by a Diesel Electric traction system. Although manufacturers are now offering mechanical or mechanical/hydraulic drives in the larger machines comments will be restricted to examining the Diesel Electric System. Since commencing operations in the mid 1960 period Hamersley Iron has made use of the diesel electric drive system using the familiar Electric Wheel. A departure was made at Tom Price with the purchase of the Wabco 3200 Series Trucks. These 235 ton capacity units employed a dual rear axle system with externally mounted motors. In 1976 a

Jan 1, 1982