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By Kobe HW, Balance PF, Black PM, Sporli KB, Smith IEM, Locke CA

The Hauraki Goldfield consists of a large number of volcanic-associated epithermal gold deposits within the Coromandel Volcanic Zone (CVZ), North Island , New Zealand; it is the most accessible and most studied of the Southwest Pacific gold regions. The deposits occur generally as steeply dipping quartz veins and breccia sheets in faults and fractures.From a tectonic perspective, the CVZ is generally considered a Neogene convergent volcanic arc constructed under an extensional tectonic regime; the common tectonic setting for epithermal mineralisation. The gold deposits are mostly hosted in subaerial andesitic arc-type volcanic rocks. Temporally, however, mineralisation is associated with rhyolitic rocks of a bimodal volcanic suite that may represent a back-arc environment. Rifting and calderas may be important components of the latter regime, but this is not yet clear; the general structural framework controlling the location of CVZ gold deposits remains poorly understood. Geophysics, particularly aeromagnetics, has a role in mapping regional fault patterns in the CVZ

Jan 1, 1990

There exist many formulae for designing coal pillars. However, when applied to a given set of mining parameters, they lead to different pillar sizes and factors of safety. From the subsidence point of view, the pillars designed as protection pillars not only have to be stable, but also have to limit subsidence over them to a level acceptable to the structure being protected. The subsidence over a pillar of given width to height ratio depends upon the mining depth. A pillar may be stable, but the subsidence over it may be quite large and unacceptable for the structure. In many cases even though pillars may yield, they support the undermined strata and reduce surface subsidence. In addition, the yielding pillars eliminate peaks and troughs in the surface subsidence profile and reduce ground strains. In a given situation, whether a pillar yields or not depends primarily upon its width in relation to mining depth.

Jan 1, 1992

The paper covers the history and develop- ment of electrical and diesel-powered hydrau- lic percussion rock drills. It examines main design aspects and problems encountered in pro- ducing an efficient and reliable machine to fully cover the nominal hole sizes required for underground development, production drill- ing and for general quarry work. The main design features and advantages of a hydraulic rock drill are relatively low input power requirement to energy per blow (this being achieved by the use of an electric or diesel- powered hydraulic system) and a specially con- structed piston using a powered damper cylinder to absorb the recoil forces from the drill steel and reduce stresses on the drill, feed and hydraulic boom. A further important design feature is the anti-jamming device which controls the drill both during manual and automatic operation. This anti-jam device works on feed and rotation press and prevents the drill bit becoming jammed in broken or soft ground. These features and many other mechanical and environmental benefits are highlighted when comparing hydraulic percussion rock drills with current pneumatic machines. The hydraulic rock drill gives an overall high penetration and production rate, with an added bonus for ergonomy and environmental conditions such as lower noise level, no fogging from air and oil exhaust (which naturally gives better air for breathing),plus improved vision when in under- ground situations. Hydraulic rock drills and systems have been fully tested in many mines, quarries and contract sites during the past years. They h6! been improved and modified and are now provi~ to be very reliable and economical piece drilling equipment whò in mines and quarries.

Jan 1, 1978

Results of investigations on adsorption and desorption of CO M CH and a mixture of the two gases are described.4 Results showed that even when the equilibrium conditions contains 50% Co and 50% CH4, the gas emission in the initia' stages will contain as much as 80% CH . 4 The temperature has a small effect and so also particle size for 1.4-11.2mm. The ratio of CO2/CH gases adsorbed in coal samples depends upon t4he equilibrium pressure and this ratio decreases with pressure. Results of field tests support laboratory studies.

Jan 1, 1988

An intensive safety campaign at Mount Isa Mines Limited from 1956 to 1966 saw the lost time accident frequency rate fall to half its original level. A review of the safety programme was carried out in 1967 and in 1968 the Five Point Safety System was introduced. The seven years since its introduction have been years of significant achievement both in production and safety. Improving safety is a fundamental part of Mount Isa Mines Limited's policy and this system has been a major tool in implementing that policy. To be successful personnel need to be prepared and trained for its introduction and subsequently counselled on its use. A carefully prepared programme is required to phase in various aspects of the system and to make use of complementary steps. The system has been a success and it is anticipated that the continued drive to improve the use of principles of the system will further improve safety. It is hoped that this paper will be of value to those personnel concerned with industrial safety in Australia.

Jan 1, 1975

The Elura Orebody consists of a number of parallel, vertically oriented pipe-like structures of pyrite-sphalerite-galena mineralization located at the core of a structural dome. Concentric zoning of the mineralization into an outer Siliceous, intermediate Pyritic and inner Pyrrhotitic Zone has been previously recognized and is used in routine geologic modelling of the lead, zinc and silver grades.Statistical analysis of the metal grade distribution in the orebody has confirmed the importance of the mineralogical zones in the understanding of grade trends. The gradational nature of intra-zone boundaries, especially those related to the subjective definition of the Siliceous Zone, are apparent in the statistics.

Jan 1, 1990

By R Justa Cámara, J María Bertrán Llop

"The need for suitable geotechnical characterisation of the rock mass for underground construction is evident. The enlargement project of Railways of the Generalitat of Catalunya (FGC) in Sabadell is a patent example.In general, it is uncommon to encounter problems in the identification and characterisation of certain relevant weak rock formations, which affect project designs. However, all materials should be properly studied, as mischaracterisation can lead to a suboptimal design, resulting in construction problems during the course of the work.Good quality rock is generally not difficult to characterise, but this is not the case for Quaternary or Tertiary cemented soils. Geotechnical investigations based on boreholes do not provide enough information because samples are often badly damaged during the drilling process, if appropriate techniques are not taken. The samples can be altered and may not be representative of the in situ?material.The design and construction of the extension to the FGC line in Sabadell highlighted the importance of the characterisation of Quaternary and Tertiary cemented soils, in particular their rigidity and its underestimation. The twin tunnel project had a total length of 5.1 km, including five stations with 3.5 km excavated by tunnel boring machine (TBM). The remaining 1.6 km was constructed using cut and cover methods. The TBM portion of the tunnel had a bored diameter of 6.83 m with an internal radius of 3 m and 0.25 m thick precast concrete segments. Much of the tunnel alignment passed through and was affected by the presence of certain stiff layers of Quaternary cohesive materials.In this paper the TBM challenges faced will be discussed in detail. In particular:  TBM excavation rate reductions and overheating problems due to the required excessive thrust and torque floating problems in the lining due to nil earth pressure over the rings and the development of an improved, controlled setting time mortar to address this issue block-in and block-out methodology for each station, in some cases with internal blocks to prevent earth pressure drops and soil scouring the relevance of performing simpler solutions, for example, hyperbaric interventions to examine the cutter wheel tools when it has been shown that interventions under atmospheric conditions were equally feasible the implementation of conventional bivalve machines as standard procedure for excavation of diaphragm walls in stations, where in fact, hydrocutter machines or pile boring machines may have been required, given the mechanical characteristics of the materials to be dug out.CITATION:Justa Cámara, R and María Bertrán Llop, J, 2014. Underground extension of the FGC line in Sabadell through cemented soils, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 161–170 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 17, 2014

In 1985 BMR assessed Australia's economic demonstrated resources of mineral sands as follows: rutile 8.0 Mt, ilmenite 41.4 Mt, zircon 11.5 Mt, and monazite 229 000 tonnes. These resources are located along the east coast of Australia, in the southwest corner of Western Australia, and in the Eneabba region, north of Perth, WA. However, over 40% of Australia's rutile and zircon resources, particularly those on the east coast, are presently not available for mining because of environmental considerations. As well, east coast ilmenite has been considered unsuitable for use by sulphate route pigment producers because of its relatively high chrome content. World demonstrated resources of rutile and zircon are estimated by BMR as 29 Mt and 38 Mt respectively. Demonstrated resources of ilmenite amount to about 1 billion tonnes. These occur predominantly in hard rock deposits in Norway, Canada, USSR and China, as well as alluvial deposits in Australia, South Africa and India. Quantitative data for world monazite resources is sparse. However, world production of rare earth oxides is now mainly from bastnaesite, a hard rock resource. Australia is presently the world's principal producer of rutile and zircon, and also provides a major share of the world's ilmenite. With the expected increase in Australia's rate of output of these commodities, combined with restrictions on mining along parts of the east coast, its position could diminish substantially over the next 25 years.

Jan 1, 1986

By M L. Leybourne

In 2012, in response to an increasing potential unfunded liability, the Western Australian Government passed the Mining Rehabilitation Fund Act 2012. The intent of this Act was to introduce an annual levy on tenements covered under the Mining Act 1978 based on the area of disturbed land. The fund generated from these levies could then be used to rehabilitate mining sites where all other options to ensure rehabilitation had been exhausted. The fund could also be used to rehabilitate abandoned sites or features which, in Western Australia, number over 10 000.The Mining Rehabilitation Fund (MRF) was implemented on 1 July 2013 for an initial voluntary year. It becomes compulsory on 1 July 2014. By the end of March 2014, nine months into the voluntary period, over $6.5 million had been paid into the fund. The incentive for tenement holders to voluntarily enter the fund was the opportunity to have unconditional performance bonds held against their tenements retired. While there will be circumstances where bonds will continue to be applied, it is the State Government’s intention to retire most of the bonds.The MRF has received mostly accolades from industry and companies that have entered. Most have found the system easy to use. The MRF was also cited as a reason for Western Australia’s improved position in the Fraser Institute’s annual survey of mining jurisdictions. Work is now starting on processes to select priority abandoned mines for rehabilitation.This paper explains the background to the MRF and its development, and reviews its implementation during the first, voluntary, year. It also discusses how the fund will be managed into the future and what this will mean for both abandoned mine features across Western Australia and any future abandoned mine sites.CITATION:Leybourne, M L, 2014. Ensuring rehabilitation into the future – The Western Australian Mining Rehabilitation Fund, in Proceedings Life-of-Mine 2014 , pp 441–448 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By James CH

For drainage sediment to be used as a successful sampling medium in reconnaissance geochemical surveys, the length of any dispersion train from a typical target must be great enough for it to be detected by a widely spaced sampling pattern, and must also be homogeneous enough to avoid it being missed by the unfortunate selection of a random low value sample. Elements which occur in stream sediments in the form of discrete heavy minerals present two special problems in this regard. Since the element is concentrated into a few particles, the medium is extremely heterogeneous, which makes representative sampling impossible unless very large samples are taken, while the high specific gravity of such grains leads to their being concentrated in traps along the stream bed. Several ways of overcoming these difficulties have been suggested. Among these the "schlich" test, in which heavy material obtained by panning is taken for analysis is among the most popular. However, the results of the present study indicate that while this method improves the nature of the patterns obtained, they are still far from satisfactory. Alternative methods of sample preparation, including the taking of light material for analysis, appear to provide better answers to the problem. In the area studied this approach eliminated most of the "noise" associated with the data obtained by other methods, as well as giving an extended dispersion pattern.

Jan 1, 1986

By Moxon N. T

A series of low shock energy water resistant emlulsion based explosives have been developed by combining inert materials, such as Perlite P500, into the formulation. The material handling, water resistance and explosive properties of these mixtures were determined as a function of inert additive type, density, charge diameter and emulsion base. Of the emulsion bases tested Emulite produced the best and most stable low density mixtures ranging in density from 0.8 to 1.35 g/cm3 producing velocity of detonations (unconfined) ranging from 3000 to 5500 nits. The mixtures could be detonated successfully at these densities at diameters as low as 25mm. Low shock mixtures formed by combining Emulite with Perlite P500 were successfully trailed at the Cadjebut zinc mine in Western Australia. The performance of the explosive, at three densities, was monitored using both continuous and point to point VOD techniques. The fragmentation produced by the blasts were compared by photographic analysis. During this trial the low shock emulsion mixtures were shown to be as effective as the currently used explosives (packaged emulsion) at a significantly reduced cost.

Jan 1, 1990

By H Asche

The Melbourne Metro project has evolved from the Victorian Transport Plan. MM1 is the second major phase of the proposed separation of Melbourne’s radial railway system, creating a line that will operate independently across the metropolitan region. The central section will run beneath the inner suburbs and the central city. The initial project comprises nearly 8 km of twin bore tunnels, three cavern stations and two cut and cover stations, as well as a dive structure and connections with the existing rail system. This paper describes the development of the geological model, a modification of the rock mass classification system derived during the EastLink project and the influence of the geology on the design of the tunnels and stations for the Department of Transport’s business case.The majority of the tunnelling will be in the siltstone and sandstone bedrock. This material has been extensively folded, sheared and intersected by igneous intrusions. A revised rock mass classification system has been developed for the Melbourne Formation to assist in identifying the important engineering properties of the rock and to rationalise the support types required.The Metro’s tunnel alignment crosses the Yarra Delta deposits in the lower reaches of the Moonee Ponds Creek and again at the Yarra itself near Princes Bridge. These deposits vary in extent and thickness over very short distances. The investigation of these materials has been carried out using conventional drilling techniques in conjunction with sonic drilling methods.Over the central section of the Metro, the positions of the new station are determined largely by transport planning requirements and urban development opportunities. However, the stations, and the tunnels, have been the subject of studies, optimising exercises, and selection processes to arrive at the concept design. This paper describes the influence of the varied geology on the development of the design, and the identification and management of the risks in tunnelling under the centre of Melbourne.

Mar 8, 2011

In order to understand the technique, basic theoretical principles of radiation emission and in- strumentation theory are reviewed. Methods of surveying, reduction of data and interpretation are outlined. Other applications of the technique (e.g. in airborne geological mapping), as well as its specific use in uranium exploration, are discussed. By means of case history-type examples the successful applicant of gamma-ray spectrometry, as a tool in Australian mineral search, is demonstrated.

Jan 1, 1969

By Noller B. N, McGill R. A

The Alligator Rivers Region has been the scene of one of Australia's most intensive environmental monitoring efforts since the current generation of uranium mining was mooted in the 1970s. Prior to mining, the local environment and the nature of potential impacts were not well known. The initial monitoring programs therefore included large baseline characterisation and research components. After some 15 years, water, soil and sediment monitoring programs have been reduced to a fraction of their early size, as the mining and natural systems became better known and characterised, and the actual nature of the environmental impacts were established. Modem techniques allow much more rapid and thorough identification of chemical species and elements of concern, allowing much more focused monitoring programs to be designed. In the 1980s data collection was emphasised at the expense of interpretation, and monitoring programs were maintained at much higher levels than were in fact required. It is now clear that investigations are important and should be distinguished from monitoring programs, and that the timely interpretation of investigations and implementation of recommendations can greatly reduce the effort and expense that can be involved in a monitoring program. Monitoring programs based on a sound understanding of potential environmental impact may then be efficient and cost-effective, yet provide sufficient information to assess the environmental impact of mining, guide further environmental protection measures when problems are detected, and demonstrate compliance with regulatory requirements.

Jan 1, 1994

By Resta S. A

Energy Resources of Australia Ltd - Ranger Mine is located about 255 kilometres east of Darwin in the Alligator Rivers Region of the Northern Territory. The Ranger project is surrounded by Kakadu National Park which is on the UNESCO World Heritage list. . Ranger Mine operates the largest uranium mine and processing plant in Australia. It is designed to produce 3000 tonnes of uranium oxide per year, but presently is producing a little less than one half that figure due to the depressed uranium market. The safety performance of the employees and Ranger as a whole continues to improve. The lost time injuries (LTI) have significantly reduced from 74 in 1985 to five in 1994. The total days lost due to LTIs have gone from 1543 to 14. These significant improvements have reflected directly on workers' compensation premiums in which a four-fold reduction has occurred. It is estimated that the actual monetary saving to the company is about $1.3 million per year and directly reports to the profit of the company. There is also an obvious and significant reduction in the less quantifiable costs such as the suffering of the injured employees and cost to society. The paper will review the various initiatives introduced and assess their effectiveness. Performance improvement is primarily dependent on the commitment, introduction of various initiatives and the subsequent change in workplace culture.

Jan 1, 1994

By H Asche

The proposed Rockwater Power Project is a hydropower development on the Waitaki River in the South Island of New Zealand. The proposed development will have an installed capacity of 250 MW with a peak flow capacity of 260 m3/s. The project commences at Lake Waitaki and extends some 35 km downstream on the north bank to a surface power station at Stonewall. Flow is returned to the Waitaki River via an outfall channel.The tunnelling for the project is through Greywacke, which comprises Permian and Triassic age marine sediments that are well indurated and weakly metamorphosed. The rock mass is jointed and sheared and there are frequent faults, which range up to hundreds of metres in width. Three 12 m diameter tunnel boring machines (TBMs) are proposed to excavate the 35 km long tunnel.The paper describes the development of the tunnel alignment, rock mass classification, design of the support, rock and hydraulic loads, support installation options and construction sequencing.The alternatives of rock bolts and shotcrete and segmental lining were both investigated and are discussed. Support using rock bolts and shotcrete offers the potential of rapid construction with minimum support cost when the ground conditions are good, but delays due to support installation increases with deteriorating ground conditions. In contrast, segmentally lined tunnels offer greater certainty in cycle time with reduced program risk. Both options are described and discussed.The horizontal alignment is affected by the presence of major fault zones, which are either avoided, or pretreated by driving conventional tunnels through in advance of the TBM delivery, topographical constraints with the rugged topography and operational hydraulic constraints. Construction requirements, future power station operation and the minimisation of leakage from the tunnel have all impacted on the vertical alignment.The number and sequencing of TBMs to be used is discussed in terms of program time and risk minimisation.

Mar 8, 2011

The treatment of the Broken Hill ores has,undergone many changes during the last ten years, and it may be of interest to some of the members to know what are the main lines on which the Proprietary Mine works at present. It must be understood that the want of absolute uniformity in the treatment amongst the various mines at the Barrier does not prove that some of the mines are working on wrong lines, for the ore is not exactly the same along the whole line of lode; this necessitates a variation in treatment, although generally only in detail.At the Proprietary Mine the ore is all mined by contract the miners are paid so much per ton for clean ore. The ore in the mine in most stopes is mixed with gangue, and the inclination of the uliners is, of course, to mix gangue with the ore, so as to be paid for as large 3 tonnage as possible. This is quite natural clean ore is easily distinguishable from clean gangue, but most lumps are a mixture of clean ore and gangue in varying proportions. The miner will naturally throw into his heap pieces which he considers still good enough, whilst the management may consider these pieces just a trifle too poor; consequently a check must be kept on this.This necessitates the first operation to which the ore is submitted. 'The trucks tare 51 cwt.; average load 21 cwt.), as they are loaded underground, have a ticket attached::showing to whiyh contract they belong on arrival at the top of the shaft they are passed over a weigh bridge...

Jan 1, 1907

By Cocker J, Urosevic M

Seismic methods have become common for the detection of low-throw faults ahead of underground coal mining. Surface seismic methods cannot theoretically be used where dykes occur, because seismic waves transmit from the surface down to the seams, and reflect back to the surface. Consequently, where sub-vertical structure such as dykes occurs, the surface seismic method fails.The ability of seismic methods to image dykes depends on the geometry used, the dyke thickness and the seismic wave propagation mode in relation to dyke composition and internal structure. Surface seismic methods find it difficult to distinguish between faults/fractures and very thin dykes (1-2m in thickness) when the dyke's thickness is less than the seismic wavelength. Consequently, borehole seismic methods have to be used to detect the presence of such thin dykes.

Jan 1, 1998

By Brumley J

The development of the SECV brown coal open cut at Loy Yang will require depressurisation of aquifers both within and below the coal seam sequence in order to maintain open cut stability. Prediction of future open cut dewatering requirements at Loy Yang Open Cut and evaluation of the regional consequences of dewatering has required development of a detailed hydrogeological model of the Loy Yang area. The complex stratigraphy of the coal seam and aquifer/aquitard sequences at Loy Yang have been analysed and integrated with the hydrogeological concepts developed from regional groundwater studies to formulate a realistic hydrogeological model as a basis for finite-element flow modelling.

Jan 1, 1988

By Needham RS

Hydrothermal mineral deposits are the dominant mineral deposit type in the Cullen Mineral Field, and have been important sources of tin, tungsten gold, silver-lead, zinc and copper. The deposits are mostly in north to northwest-trend- ing shear zones, and are confined to Early Proterozoic contact metamorphosed metasediments or synorogenic to postorogenic granitoids. The distribution of the vein-type deposits with- in the contact aureole defines a district-scale metal zonation of uranium closest to granitoid, through tungsten, copper, tin, silver-lead to gold with increasing distance from granitoid contacts. This zonation probably reflects de- creasing temperatures within the contact aureole during granitoid emplacement, and at the time of generation of a variety of metal-bearing fluids. A magmatic source for some of the metals is indicated by the positive spatial relationship between uranium, tungsten, copper and silver-lead deposits and granitoids abundant in those metals. There is little evidence for any such relation- ship for tin and gold deposits, except for an association of some tin deposits with tin-enriched mafic rocks. Most of the granitoids with anomalous metal values are late stage highly fractionated leuco- granitic phases forming younger plutons peripheral to the main body of the Cullen Batholith, They probably form cusps connected to the main body at shallow depths.

Jan 1, 1984