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Teleseismic travel time residuals measured on 600-1000 km seismic arrays across the Rio Grande and East African rifts provide evidence for upper mantle low velocity zones beneath each rift of velocity contrast 6%-8%. Refraction studies show thinning of the crust below the rift axes. Regional uplift which extends hundreds of km either side of the axes, is isostatically compensated by negative density contrast at depth. Since the refraction argues against compensation by thickened crust, compensation in the upper mantle low velocity zones is suggested. Temperature effects alone can not explain the reduced velocities. Generation of a few percent of partial melt is the most probable source of the reduction. A passive extensional mechanism is investigated for the Rio Grande rift in which hot asthenosphere intrudes the lithosphere raising its temperature and generating moderate melting. It requires less than 1% extension to explain the melting but a prodigious 26% to raise the temperature from a pre-rifting continental geotherm to the solidus. Geological estimates find that extension is less than 10% over the uplift zone. Such a mechanism is possible only if the prerifting lower lithosphere geotherm lies closer to the solidus than that of stable continent. This is supported by the observed high heat flow in the Rio Grande rift uplift region which, given the long time constant for thermal diffusion, reflects elevated temperatures at depth well in advance of the onset of rifting.

Jan 1, 1987

By C Killip

Working in Australia’s harsh climate can have a significant impact on the health, safety and productivity of our teams, but is our working environment expected to be more prone to heat stress in the future? Climate modelling suggests that we are likely to encounter more frequent heatwaves and higher apparent temperature. Does this mean that our teams will be at greater risk of heat stress, and are we prepared to deal with the changes in our future climate and the potential impacts on our working population? This paper will review the recent research on climate and projected changes to all meteorological parameters that are important in understanding the likelihood of heat stress. The paper will also describe the challenges encountered in the management of heat stress in a workforce, and then outline a systematic approach to heat stress management that will allow you to assess your own risk and manage your day-to-day operations into the future.CITATION:Killip, C, 2015. Future climate – is heat stress a real risk for the future and how can we better manage it?, in Proceedings Third International Future Mining Conference, pp 181–188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By M P. Sandy, R M. Stephenson

Portals to access underground mines are important infrastructure and their design requires careful consideration. Portals are generally expected to last for the life of the mine. Typically, the exposure of personnel and equipment is high, with many hundreds of movements through the portal per day. Consequently, the risk associated with geotechnical instability must be extremely low. Portals are often established from a boxcut. In areas where the weathering profile is well developed, the design and execution of the boxcut can involve significant effort, with the objective of minimizing the volume of the boxcut, whilst ensuring that conditions at the design depth are suitable for establishing a stable portal. Properly designed site investigations are a critical part of this process. Currently available portal design guidelines have not been updated for decades, however the equipment and ground support systems have changed significantly in recent years. Many mine portals have since been constructed in a relatively short time frame with success, often in challenging ground conditions using some of the more modern approaches to ground support. This is beneficial because delays in establishing a portal will generally delay other critical path activities, and lead to cost overruns.

Mar 15, 2021

Following the Moura No 2 Wardens Court of Inquiry and subsequent changes to the Queensland Mining Legislation there is a requirement in Queensland coal mines for: a person with the recognised competencies to be appointed at each underground coal mine to the position Ventilation Officer; and the person is directly responsible for the implementation of the mine ventilation system and for the establishment of effective standards of ventilation for the mine. The Regulations require that an underground mine must have principal hazard management plans that provide for at the least the following: emergency response, gas management, methane drainage, mine ventilation, spontaneous combustion, and strata control. Other than strata control all the plans require the ventilation officer to have roles and responsibilities to develop, control, monitor and undertake actions in relation to these plans.There are also another 34 Regulations that either directly or indirectly requires the Ventilation Officer to take actions.The purpose of this paper is to outline the information that the regulators look for in sealing plans and the actions the regulators will take if the sealing does not go to plan (TARPs being exceeded).

Jan 1, 2005

The Cannington silver lead zinc deposit is located near Mt Isa in North West Queensland. This world class orebody is owned by BHP World Minerals (BHP) and is estimated to contain 45 million tonnes of ore at an average grade of 11 per cent lead, four per cent zinc and 500 grams/tonne silver. At BHPÆs planned 1.5 Mtpa extraction rate, the mine life will exceed 20 years. Construction of the underground mine, which commenced in August 1993, was carried out by Peabody Resources Ltd (Mining Services Division) (PRL) for BHP Minerals Pty Limited (BHP) under contract packages totalling approximately $100 M using several innovative techniques to deliver safety, quality and time related project goals. Client/Contractor Partnering, resulting in harmonious working relationships, a combined commitment to the achievement of an excellent safety record, and a seamless transition from the construction phase to operation of the mine, has been a feature of the project.

Jan 1, 1998

By Jarvensivu M, Ylinen R, Jamsa-Jounela S-L

The paper presents a new integrated system for control of concentration processes. The system is based on cluster-based modelling taking the ore quality into account and a new on-line particle size analyser capable also for reliable measuring of particle size distribution of concentrate. A metallurgical precontrol audit was performed at the Hitura concentrator in order to design the control strategy of the integrated grinding and flotation control. A new analyser PSI-200, was used to the measurement and control of the distribution of nickel in the total particle size range. An expert control system using the cluster model together with a new control strategy for decision of necessary control actions is outlined. The method has been tested to real data from mineral processes. The results are in good correspondence with empirical process knowledge. KEYWORDS: Cluster analysis, expert control, flotation control, mineral processes, modelling, particle size.

Jan 1, 1993

By Whitworth N, Anderson P

New plant has been commissioned to treat off-gases from the Fluo-solids Reactor in the Copper Smelter. The new section of plant was built onto an operating system and commissioned with minimum disruption to production. Under construction is a 270 m tall stack for Lead Smelter gases. Additional items for the Lead Smelter will include a new gas cooler, a central baghouse to replace Sinter Plant wet gas scrubbers, a new exhaust fan on the main baghouse, and ducting of drossing gases to the main baghouse. Emphasis is given to discussing improvements the new plant has made to working conditions, the general environment and increased production capability. Total expenditure in the two smelters is in the order of $25 million.

Jan 1, 1978

By J Pan, Q H. Li, D Q. Zhu, C C. Yang, X Wang, Z Q. Guo

Al2O3 in natural iron ores generally occurs in goethite, kaolinite, gibbsite, hematite and iron carbonate. When the content of alumina in sinter increases from 1.11 per cent to 3.50 per cent, the reducibility of sinter decreases with the addition of four different types of alumina. When gibbsite and kaolinite are added, the low temperature reduction disintegration (RDI+3.15 mm) of sinter increases with the increase of Al2O3 content in the range of 1.5 per cent to 3.5 per cent. Furthermore, when adding pure reagent alumina, the increase of Al2O3 content in the range of 1.5 per cent to 3.0 per cent will increase the RDI+3.15 mm of sinter. The addition of ferric oxide–alumina spinel with the Al2O3 content in the range of 1.5 per cent to 2.5 per cent, also increases the RDI+ 3.15 mm of sinter. The influence difference is results from the change of the mineral composition and microstructure of sinter because of the occurrence state of Al2O3. Under the condition that Al2O3 content of sinter is 2 per cent, the porosity of sinter with kaolinite is 37.26 per cent, and the shape is irregular. When gibbsite and ferric oxide–alumina spinel are added, the porosity of sinter is about 16 per cent, and the pores are round. When pure reagent alumina is added, the porosity of sinter is 17.49 per cent, and the pores are regular and small. When kaolinite, gibbsite and ferric oxide–alumina spinel are added, platy calcium ferrite is mainly formed in the sinter, and some of it is columnar calcium ferrite. On the other hand, when pure reagent alumina is added, in addition to platy columnar calcium ferrite, acicular calcium ferrite is also formed in the sinter.

Nov 8, 2021

By Rowena C. Duckworth

The Ocean Drilling Program (ODP) is the largest international geoscience project in the world, and the state-of-the-art drill ship, the JOIDES Resolution, is permanently at sea. Each year there are six scientific cruises (legs) which each last approximately two months. These legs are designed by geoscientists from the nineteen countries that subscribe to ODP. Australia and Canada presently share ODP membership under the banner of the AUSCAN Consortium. The benefits of Australia's involvement in ODP include internationalisation of Australian geoscience, advanced graduate training, and unique scientific investigations of the ocean floors in the Australasian region. In addition, visits to Australian ports by the ODP drill ship, the JOIDES Resolution, contribute up to $2 million per visit to the local economy. Amongst the many other aspects of ten years of scientific drilling, ODP has significantly contributed to our understanding of hydrothermal processes on the seafloor. To date, three hydrothermal sites have been drilled to date by the ODP, Snakepit (MAR), Middle Valley (Juan de Fuca Ridge) and TAG (MAR). Two more hydrothermal sites are scheduled for 1996.

Jan 1, 1995

By Woodcock J. T, Zhu T, Sparrow G. J

A lead-zinc-pyrite flotation middling was pressure oxidised to give residues containing iron hydroxy sulphates (a mixture of basic iron sulphate (BIS) and a hydrated iron sulphate (HIS)) and lead sulphate. Direct thiourea leaching of this residue gave over 90 per cent extraction of gold and silver, but thiourea consumption was high (56 kg/t) because of soluble iron(M) in the residue. Attempts were made to decrease the thiourea consumption by removing the water-soluble iron(M) or reducing it to iron(II). Water washing of the pressure oxidation residue removed most of the hydrated iron sulphate but little of the basic iron sulphate. Iron removal was only 12-20 per cent, depending on the number of washes, from one sample which was low in HIS, and 40-45 per cent in another which was high in HIS. Iron extraction was not appreciably increased by using dilute sulphuric acid (with or without additions of sodium sulphite), dilute phosphoric acid, or sodium chloride solution (150 g/L NaCI). Direct thiourea leaching of the water-washed residue gave over 90 per cent extraction of gold but only 49 per cent of silver, with a thiourea consumption of 27 kg/t. However, the application of a water wash followed by reduction of dissolved iron(III) with sodium sulphite in the presence of thiourea, and then thiourea leaching resulted in over 98 per cent extraction of gold and silver for a thiourea consumption of 26 kg/t.

Jan 1, 1991

The lignites of Otago and Southland offer a potentially viable future feedstock for electricity production and possible conversion to petrochemicals or liquid fuels. The deposits, when combined, represent New ZealandÆs largest energy inventory; equivalent to about 74 000 petajoules û or approximately 35 times current natural gas reserves. Too often dismissed as irrelevant to New ZealandÆs energy future because of adverse perceptions of the value of low rank coals, the strategic value of this resource is in fact huge.   Investigations of the lignites extend back over more than 50 years (LFTB various, CRL Energy Ltd). Whilst it is not the intention of this paper to review this work, these investigations have confirmed the suitability of the resource as a feedstock for thermochemical conversion. Current estimates of South Island lignite mining costs are NZ$1.0 - 3.0/GJ (Natusch 2005), making these resources amongst the most competitively-priced energy sources available world-wide.   This value, however, will only be captured if we as a country begin to envisage a world-scale, long-life, integrated and multi-faceted development sized to supply world markets for chemicals or fuels. Recent CAE studies (Hooper and Riddolls, 2005) have emphasised the vital importance of ensuring that any exploitation of this resource maximises their value to New Zealand. The question that thus must be applied is how might large-scale utilisation of the resource fit with New ZealandÆs primary energy supply, and its potential for the export of high-value commodities.   From the broader perspective of New ZealandÆs total energy supply equation we need to examine other supply options beyond just the generation of electricity. We face in this country a situation wherein almost all our liquid fuels feedstock has to be imported with projections for an increasing dependence on imported oil. In addition NZ has a natural gas reserves-to-production ratio of less than ten years, and dwindling supply from local production. Without further natural gas discoveries, New Zealand has only a window of approximately five years before we will need to commit to imported LNG or some other thermal fuels option.   In other words, New Zealand is facing an uncertain future unless we can restore energy inventories to cover an adequate strategic reserve capacity as well as enable long-term investment in alternative sources. Within this context the South Island lignite resources are thus deserving of more attention. The extent of the resource is well known, its suitability for conversion reasonably assessed, and its magnitude such that there is little doubt that lignite conversion could adequately meet NZÆs future energy needs for many years out.   This paper reviews coal gasification technology, its application to lignite and the possibilities for future development of the lignite resources. It is argued that the strategic imperative for this country is to secure the lignite resources as a primary energy source for this country well into the latter half of this century.

Jan 1, 2005

By E M. Jones

On 26 June 2000 a hydraulic fill retaining barricade failed at the Bronzewing mine in Western Australia. The barricade failure resulted in the release of 19 000 m3 of saturated hydraulic fill into the mine, which caused the deaths of three miners. Following this tragic accident, the practices and procedures of mines using hydraulic fills came under intense scrutiny by regulatory bodies and mining companies. At this time, the use of hydraulic fill at NormandyÆs zinc/copper Scuddles mine was suspended and waste rock became the sole backfill material in use underground. By 2003, development of the mine adjacent to Scuddles, Gossan Hill had progressed to a point where a self-supporting fill material was required to enable full recovery of high-grade ore. Cemented hydraulic fill (CHF) was identified as the optimal fill type and work began on designing appropriate management procedures and controls to ensure the safe implementation. This work included definition of the fill properties, plant design and construction, reticulation system design, design of stope barricades and drainage systems and fill placement control and monitoring practices. CHF placement began on 16 July 2004 and has continued to date. Significant operational experience has since been gained in areas including plant performance, fill product quality assurance, barricade construction, stope drainage and in situ performance.

Jan 1, 2008

The brown coal deposits of the Latrobe Valley are ideal for open cut mining and this method has been used since the start of coal winning in 1894. Operations at the main Yall9urn open cut commenced in 1922, but after a few years the main excavators were replaced by German continuous excavators and subsequent developments of Yallourn and the newer Morwell open cut have been based on this type of plant. The reasons for preferring continuous to intermittent excavators in the Latrobe Valley are indicated in this paper.Under the pressure of post-war conditions, and from their long experience and ability, German engineers have recently made substantial improvements in their continuous excavators and these developments have been enhanced by some American innovations. These changes have extended the economic limits of open cut mining and also serve to emphasize the close inter-relation between the nature of coal and overburden deposits, excavator design and methods of operation.As an aid to descriRing recent excavator developments, this interdependence is demonstrated by means of diagrams which show typical methods of operations, together with examples of actual machines using these methods. The types of excavator dealt with are mainly those in use at, or destined for Yallourn or Morwell open cuts, together with additional types used in U.S.A. and Western Europe. For completeness, and also because they will continue in service at Yallourn and Morwell for some years, rail-mounted dredgers have been included in this paper even though in Europe they are now regarded as obsolescent.Explanations are given of how the intrinsic qualities of Latrobe Valley brown coal and overburden have sometimes prevented overseas plants from operating with the full efficiencies and/or in the methods visualized by the manufacturer, and references are made to the modifications and investigations being undertaken to overcome these problems.A compresensive bibliography is given. Dates shown on illustrations are not commissioning dates of the plant concerned, but the year when photographed.

Jan 1, 1960

By D W. Nisbet

Today Hudson Bay Mining and SmeltingÆs 777 Project is the largest mining construction project under way in Canada. The project comprises six components: construction of the new 777 zinc-copper mine; construction of the new Chisel North zinc mine that will truck ore out from 600 metres below surface; expansion of the Flin Flon ore concentrator; expansion of the zinc plant to increase throughput by 15 per cent; a spill gas project that will reduce fugitive gas emissions by some 90 per cent; and infrastructure improvements including construction of a new electrical substation. Total investment in The 777 Project is over $US 260 million. Seven years ago, the Flin Flon, Manitoba-based company was fighting for its very existence. How does a company go from down-for-the-count to robust contender in just seven years? Contributing reasons are many, but all have their root in a process HBMS calls æTransformationÆ. It is transformation that has taken HBMS, a very traditional company, through a very non-traditional turnaround (Figure 1).

Jan 1, 2000

A comprehensive analysisof rock structures in non-oriented (axially oriented) drillcore is now available (Laing, in press). The system embodies new concepts which better equip the geologist and engineer to deal from the outset with optimising the acquisition of structural information in drillcore, logging, interpreting, and graphically presenting the results. The few existing techniques for determining orientations of structures are augmented by a wide range of new techniques, and all are brought together into two solution types by considering the underlying Euclidean geometries. Analysis of these solution types in terms of what data are required to implement each solution and what assumptions need to be made, leads to strategies which facilitate intelligent design of different drilling programs for blind and outcropping situations. Drillcorc is variably structurally fertile, depending on the number of different structures present. This concept fosters the selective logging only of the more fertile core. Drillholes are also variably fertile, depending on their orientational relationship to the structures in the host rocks. Structural parameters are either vectorial or non-vectorial. Vectorial structures parameters comprise normal structural orientations plus polar vectors like vergence, younging, shear sense and so on. They can be determined by one of two solution types: external solutions, which use an external reference structure to fix the drillcore and thus permit orientation of all structures within that core, and internal solutions, which use orientational data from a selected structure at three or more different drillhole orientation to determine the unique orientation of that structure, without reference to any external structure.

Jan 1, 1990

By Longworth C. R

Competing requirements for land usage sometimes make the correct all- ocation difficult. The decision can be complicated by many factors such as local resident pressure, previous government decisions, economic pres- sures and the duration or permanency of the competing land usages. This problem often confronts the extractive industries with consequent delays in granting leases and some- times considerable local dissension. A proposal to extend the high grade silica sand quarry of the Wamberal Sand Company Pty. Limited is a microcosm of these competing requirements. The sand quarry is located on the New South Wales central coast. It is an open pit operation on a near beach deposit of silica sand suitable for flint glass manufacture.

Jan 1, 1976

A new watersoluble binder for mineral ore pellets has been developed by the sulfonation of bituminous materials. A highly effective binder for iron ore pellet making is obtainable from bituminous materials produced in the hightemperature cracking of crude oils. This paper deals with production process and basic properties of this binder as well as new applications in the field of iron ore pelletizing.

Jan 1, 1974

The Pacific Rim countries ofAustralia, New Zealand, Papua New Guinea, Indonesia, Fiji, Philippines and Solomon Islands will be reviewed from an equity investors perspective.   The following areas will be covered: Country risks Exploration spending and activity Project development Taxation Relative cost of doing business Environmental considerations Political/bureaucratic situations Capital raising Equity markets as a source of funds Developing market funds The aim of the paper will be to outline the most attractive areas for investment by equity and private funds plus documenting the changes needed in the less favourable countries if they are to attract investors.

Jan 1, 1995

By Jarvis ST

Colliery spoil is the major constituent of colliery spoil 'rockpaste' which has been used to infill abandoned limestone mines in the West Midlands of England since the early-1980s. The other constituents of rockpasle 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 mulling a 6600 nt' section of an abandoned mine was conducted prior to the mulling of the Littleton Street Mine which had a volume of about 500 000 m'. 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 rued 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 I I mines with a total volume exceeding two million cubic metres have been backfilled.

Jan 1, 1998

By H S. Smit, P Lotz

Gold mining companies who are signatories of the International Cyanide Management Code (visit www.cyanidecode.org for further information) are required to measure WAD cyanide on-line and destroy WAD cyanide in excess of specified limits. Weak acid dissociable (WAD) cyanide refers to those cyanide species liberated at a moderate pH of 4.5 such as HCN(aq) and CN-, and the majority of Zn, Cd, Cu, Ni and Ag complexes with low dissociation constants. It is potentially toxic to humans and animals. Recognising and in response to the gold mining industryÆs need for an on-line WAD cyanide measurement device, Mintek recently developed the WAD Cynoprobe. The WAD cyanide analysis technique is based on the use of a ligand exchange reagent that liberates WAD cyanide from metal-cyano complexes. The ligand exchange reaction is represented by the following chemical equation: Metal(CN)X + yLigand <-> Metal(Ligand)y + xCN- The plant filtrate is treated with a ligand exchange reagent, to liberate WAD cyanide, before measuring the free cyanide concentration via amperometry. The instrument proved to be accurate and reliable in the laboratory as well as under industrial gold plant conditions during various trials. It has gained wide-spread commercial acceptance both locally and internationally. However, itÆs recent exposure to complex ore types have called for refinements to the analysis technique. It has been further developed to improve its precision and accuracy and to remove reagent and thiosulfate interferences. Its compatibility with the most commonly used destruction oxidants has also recently been investigated. The WAD Cynoprobe may be configured to measure both free and WAD cyanide concentration. Its fast analysis time, approximately 5 min, makes it suitable for use in the control and optimisation of the cyanide destruction and recovery process. Proper oxidant dosage control and monitoring of effluent concentration levels will ultimately result in less cyanide and post-destruction salts discharged into the environment.

Jan 1, 2008