Search Documents

While convergence of plates at a subduction zone produces shortening at the toe of the overriding plate, this deformation is localized to the frontal 100 km or so of the plate. There is increasing evidence that the state of strain in back-arcs, volcanic arcs, and possibly the entire forearc is extensional. The most likely cause of this extension is rollback of the subducting plate and trenchward advance of the overriding plate. Arcs are thermally weakened, and are activated repeatedly through time. The primary expression of the extensional state of strain is spreading of the weak arc material, either by splitting the arc or by back-arc spreading behind it. This study presents evidence for extension of volcanic arcs from an analysis of the moment tensors of shallow earthquakes (

Jan 1, 1990

A paper describing the treatment of the Mary Kathleen uranium ores must necessarily be historical and confined mainly to a review of the four papers which have already appeared. Couche and Hartley (1958) described the development of the treatment process just prior to the commencement of operations in June, 1958. Harris, Boag and Hemingway (1961) described the treatment during the operations, and Wreford (1965) reviewed all aspects of the mine and mill, when operations were suspended in November, 1963. Harris and Steele ('1960 presented a paper especially describing the radiometric sorting operation. Some hitherto unpublished information is also presented in the paper to describe some of the peculiarities of the ore, indicate reasons for the adoption of the treatment flowsheet, and some interesting problems connected with this treatment.

Jan 1, 1968

In 1955 the annual production of steel at Australian Iron and Steel Pty. Ltd., Port Kembla was 1.2 million tonne and over the following two decades this had progressively increased to the present capacity of 5.4 million tonne per annum. This increase in productivity has also been accompanied by important developments in steelmaking technology and these are explained in the chronological order in which they have taken place. Reference is made to the use of oxygen in open hearth furnaces, the B.O.S. process, the Argon-Oxygen decarburisation process for stainless steel, vacuum degassing and continuous casting. When the vacuum degassing and continuous casting units are commissioned, the Port Kembla Works will have achieved a standard of steelmaking technology equal to any in the world.

Jan 1, 1976

By Kupper T

Firstly, electric analog models are discus- sed to show fluid streaming conditions. In these models the depth of blast at tuyere level, the height of the bath, the influ- ence of different angles of the furnace zones and the different possibilities of the root of the cohesive zone have been changed. Tests to define the influence at a large blast furnace are given. Secondly, the wear of carbon bricks in the hearth is examined under the influence of gas, slag and pig iron. Oxidation tests in a special scanning microscope with the pos- sibility of heating and gas treatment are shown. Wear mechanisms are discussed fora large blast furnace and proposals for im- provement are given. Finally, the possib- ilities and value of the temperature meas- urement in the hearth block are discussed.

Jan 1, 1981

By Mitchell D. S

BackgroundIn March 1990 Pasminco resolved to replace and increase the capacity of the underground pumping system at the Southern Operations, Broken Hill. The existing pump station was built 23 years ago while the rising main had been in service for 38 years and was subject to frequent failure.The old system was a conventional slurry/clear water separation and multi-stage pumping system. It was inadequate in the following areas:ò insufficient capacity to handle current and expected future flows;ò unable to consistently dewater lower production areas; ò pumping capacity restricted sandfilling rates;ò dirty water dams had insufficient settling capacity and were difficult to de-sludge;ò the operating costs of dewatering were high; ò it was labour intensive; andò it did not offer enough protection to the 25 level loading station.

Jan 1, 1993

By Jankowski P

The Bannockburn gold deposit is located 67 km north-west of Leonora in a poorly exposed part of the Norseman-Wiluna belt of Western Australia. The deposit consists of narrow, complexly shaped orebodies which have presented a challenge to find successful grade control and mining methods. The deposit also presents an opportunity to examine in detail the geology of this part of the Norseman-Wiluna belt.This paper discusses the geology and structure of the Bannockburn gold deposit as well as the grade control and mining systems developed to define the ore and extract it with minimum dilution. We discuss the different techniques employed for grade control in the past and their shortcomings, and the evolution of the present system of doing grade control in cross section from blast hole assays.

Jan 1, 1993

By S M. Aminossadati, C M. Stewart, M S. Kizil

Mine ventilation models are now an accepted component of most mine management systems. However, modern ventilation models also represent a highly structured spatial data source, defining underground pathways and connections across a mine. This creates opportunities to extend the use of network models beyond ventilation design, by using critical path algorithms to find pathways such as minimum distance or minimum time.This paper explores the use of ventilation network models to automatically analyse and calculate potential emergency escape routes. A variation of Dijkstra’s algorithm is used to predict complex pathways between any two points across a model, representing an escape route from an emergency area (such as a fire) to a safe location (such as the surface or a refuge station). Weighting can be assigned to paths to represent potential travel speed, obstructions or preferred routes. Finally, emergency considerations such as smoke or gas in some parts of the mine can then be incorporated into the pathways to force the algorithm to avoid dangerous routes and specify safer pathways. Ventsim is used to visually show example results.Emergency egress pathway prediction using ventilation network models can provide an efficient way to quickly predict the quickest or most efficient escape routes for emergencies or planning purposes.CITATION:Stewart, C M, Aminossadati, S M and Kizil, M S, 2017. Emergency egress pathway prediction using ventilation models, in Proceedings Australian Mine Vent Conference 2017, pp 57–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Muchi I

To clarify the characteristics of non-uniform flow of gas through layered burdens of ore and coke, flow equations of continuity and motion were solved numerically taking account of the geometrical effect of a bed. The results are compared with that predicted by an approximate solution. A mathematical-kinetic model for determining the distributions of process variables over the region from the top to the melting level of blast furnace with the horizontal or the inclined layers of burdens is developed in consideration of the uneven gas flow. By the use of this model, the longitudinal and the radial distributions of process variables in an existing blast furnace in Japan were calculated with the aid of a digital computer. Computed results show that the process variables and the melting level change remarkably over the cross-section of the furnace and that the patterns of these distributions are similar to the results observed by other investigators.

Jan 1, 1975

By M Titley, E Maidens

Many gold deposits were mineralised by fluids and processes that also altered the host rocks. This alteration may often be a useful visual aid that distinguishes barren, low-grade from high-grade regions in a rock mass. Alteration intensity is commonly used in gold deposits as a visual tool, along with face sampling or grade control support, to define oreblocks and guide excavation in underground and open pit mining. However, alteration is not often used at the resource estimation stage. Mineralised lodes are usually defined by geologists using a ægeo-grade envelopeÆ, where a number of constraints are considered, including an (arbitrary) cut-off grade; the ænaturalÆ grade break between high- and low-grades; and geological features including structural, lithological or alteration continuity. The geo-grade envelope is usually thought to satisfy the requirements of stationarity for grade estimation, and is considered a single domain. This paper examines a modelling technique combining gold grade and alteration, applied to the Wallaby deposit in Western Australia, to imbue a greater level of detail to the grade estimation in a region tested by relatively sparse drilling. This was achieved by utilising the correlation of gold grade and alteration, along with the spatial characteristics of the alteration, when estimating grades within a number of lodes. The alteration-driven estimation was utilised in conjunction with an unfolding approach, and the use of probability estimates, to overcome geometric data constraints. This technique allows greater control and most likely provides a more reliable estimate of the mineable resources than a global grade cut-off when visual control is to be a major vector in grade control.

Jan 1, 2003

By G W. Wilson, P Ritchie, N A. Currey

The design and rehabilitation of potentially acid forming (PAF) waste rock dumps is site specific, being a function, among other factors, of the rock types, the dumping and storage method employed, and the climatic setting. The æstore and releaseÆ cover system developed to manage acid rock drainage (ARD) from mineralised waste rock dumps at Kidston Gold MinesÆ open pit operations in the semi-arid climate of North Queensland, Australia, has been monitored for seven years. The paper describes the philosophy behind the design of the PAF dump and æstore and releaseÆ cover system and the adaptation of the cover system over time to suit KidstonÆs conditions. The results of monitoring over the seven years since the first cover was constructed are presented, and the approach being taken at Kidston to ensure that the risk of impacts from any residual ARD is accommodated and to facilitate lease surrender are described. The Kidston story is a valuable case study of a successful approach to remediating an identified source of ARD in a semi-arid climate, which has actively engaged all Stakeholders.

Jan 1, 2003

By D S. Stewart, K W. Keskimaki

The Henderson Mine has been utilising a continuous panel caving method to extract molybdenum ore since starting operation in 1976. In the past three decades since the mine was designed, many changes have taken place in underground technology as well as the general nature of the mining business. The impacts of larger scale underground equipment and automation are significant at Henderson and continue to reshape the nature of the enterprise. During the first years of operation in the 1970s, Henderson required almost 2000 employees to achieve full production, today only about 400 people are required to fully utilise the plantÆs capacity. The most recent change to the facility is the conversion from a rail haulage system to an underground crushing and conveying system that transports ore 25 km to the Henderson mill site. This change has required the introduction of large, rubber tired haulage trucks underground and the mining methods necessary to develop the large openings demanded by the trucks and underground crusher. The development of the underground crusher is also the first step to mining the final bottom horizon of the orebody. Along with this move comes an opportunity to almost triple the effectiveness of the mining effort, through higher draw columns and wider draw bell spacing. This final advancement to a totally trackless mine has positioned Henderson well for safe and efficient operation as it enters the 21st century.

Jan 1, 2000

An experimental study of the influence of surface active agents on the dewatering of fine coal was undertaken with a view to evaluating the usefulness of such materials in reducing the residual moisture contents of filter cakes. Experimental evidence is presented which suggests that while polymeric fiocculants have a beneficial effect on settling, they can have adverse effects on the filtration of the thickened underflow. Detergent addition, on the other hand, was shown to reduce filter cake moisture, and the magnitude of this effect was determined, in part, by the prevailing electrochemical equilibrium at the solid-solution interface.

Jan 1, 1976

By K Heiskanen

Flotation is affected by several factors, part of which depends on the mineralogical characteristics of the ore and part on process variables. Sulfide Ni-Cu ores occur typically in mafic and ultramafic igneous rocks. Serpentine minerals are also common. As a consequence of metamorphosis, sulfides and secondary minerals may be finely disseminated in an altered ore matrix. The floatability of minerals depends also on process variables. Oxidation of sulfide particles, process iron and dissolved ions in process water affect the behaviour of sulfides. The effects of some essential factors on flotation of Ni-Cu ores are considered.

Jan 1, 2005

By G McSpadden

At September 2001 the beneficiation plant at BHP Billiton Iron OreÆs Mt Whaleback mine is set to treat 9.5 million tonnes per annum (Mtpa) of iron ore, 40 per cent better than original design. This paper describes the steps, decision-making processes and innovations used to increase capacity at minimum cost. The plant was designed in 1979 to operate at 1133 t/h for 6000 hours per annum, treating 6.8 Mtpa. Sufficient suitable contact ore was unavailable and feed was finer than planned. The plant was designed with minimum surge capacity between multiple process units. It had never reached design capacity. In 1993 a study by Fluor Daniel to treat increased tonnage resulted in modifications to improve plant operations. Efforts to expand production by increasing reliability did not achieve the desired capacity. NJ Morrow (Pty) Ltd (NJM) conducted a technical audit in 1996 with process evaluation by Mineral Processors. Replacement of operator interface and PLC logic in 1997 made plant operation and diagnosis easier. Involving operators in logic development enhanced their plant knowledge. Fluor Daniel Simulation developed a simulation model of the process. Mineral Processors and NJM reviewed the model findings, recommended metallurgical improvements and developed preliminary designs and costs. BHP Engineering produced a detailed design with a cost estimate of $A34 million. After analysis and revision of the design, a $A10.4 million upgrade to 8.5 Mtpa was carried out. Detailed modifications to the process units, particularly the HM drum plant, allowed significantly higher capacities and improved metallurgical performance. The target capacity was achieved in June 2001. Further modifications are progressing to treat lower-grade ores.

Jan 1, 2002

By Groves D. I

The Norseman-Wiluna Belt (Fig.1) is a richly mineralized (production 1900 tonnes Au), Archaean greenstone belt, up to 800km long and 200km wide, which forms the major part of the Eastern Goldfields Province within the Yilgam Block. The Belt evolved ca. 2700 Ma ago as an oblique-slip mobile belt between flanking portions of an older greenstone terrane. Volcano-sedimentary successions in the Belt represent two distinct tectono-stratigraphic associations. Sequences of metamorphosed caic-alkaline intermediate to silicic volcanic rocks interlayered with tholeiitic basalts probably represent the remains of a dissected Archaean volcanic arc (or arcs), and sequences composed dominantly of ultramafic to mafic lavas and intrusions, with minor interflow tuffaceous, sulphidic or cherty sediments are interpreted as remnants of the floor of an ensialic marginal basin (Barley and Groves, 1988). Ultramafic volcanism at Kambalda has been dated at 2692 ¦ 2 Ma (Claoue-Long et al., 1986). The dominantly volcanic associations are locally overlain by coarse clastic sedimentary succes- sions. The Belt is also typified by major north- to north-northwest-striking fault systems, shear zones, and tectonic lineaments, many of which are traceable for more than 300km. As well as defining the boundaries of the belt, these structures have accomodated much of the regional strain and acted as conduits for hydrothermal fluids during deformation, metamorphism and mineralization. As a result, most of the epigenetic gold deposits in the Belt occur in subsidiary structures related to these fault systems (Eisenlohr et al., 1988). Deformation involved oblique compression resulting in a closely spaced network of low-angle faults (thrusts) as well as upright folds and oblique- to strike-slip faults (Archibald, 1987; Veamcombe et al., 1988). This was accompanied by regional metamorphism and granitoid emplacement. At Kambalda, regional deformation and metamorphism were synchronous with the emplacement of the Kambalda Granodiorite which has been dated at 2662 ¦ 4 Ma (Hill and Compston, 1986), approximately 30 Ma after volcanism.The tectonic history and style of deformation of the Norseman-Wiluna Belt are similar to those of Phanerozoic oblique- slip mobile belts at continental margins, which are also a major source of hydrothermal gold mineralization.

Jan 1, 1988

By J J. Jiang, M Reimnitz

The Kalgoorlie Consolidated Gold Mines (KCGM) Fimiston Open Pit is mining through a dense network of disused level workings and open stopes of greatly varying sizes. The condition of the stope crowns and remnants is often unknown, and ultimately these structures become a significant proportion of the production floor and pit walls. Significant seismic events and occasionally rock bursts often occur in the underground workings. Seismicity is becoming an issue to the viability of the KCGM Fimiston operations. KCGM needs to take a leading role in understanding mine-induced and regional seismicity. The seismic system trials were initiated in the Fimiston Open Pit in 1996 using the ISS system. The initial system included two triaxial geophone arrays and two triaxial accelerometer arrays installed into two boreholes. The main objectives of the trial were to investigate the suitability of the two types of sensors and the detectability of seismicity in the pit. The trial was regarded as a success and the system has been expanded and improved. The current system consists of 12 triaxial geophone and accelerometer arrays and nine uniaxial geophones. The 12 triaxial arrays are installed in nine boreholes drilled from the pit and the nine uniaxial geophones are installed from underground level workings about 660 m below the original surface elevation. The system is designed to provide seismicity coverage for the entire pit area that is about 2.7 kilometres long, 1.5 kilometres wide and about 300 metres deep. The accuracy of the source location has always been a challenge due to the existence of the dense concentration of stopes and lack of the sensors. It is uncommon to have direct ray path for the seismic waves to propagate to the sensors across the strike, hence sensors have been located along strike and under the old workings. This paper discusses some of the challenges associated with seismic monitoring near mine remnants and seismically active faults. The results of the seismic monitoring are presented, and contrasted to results of three dimensional boundary element numerical modelling. The impact of the seismicity upon pit slope stability is briefly discussed.

Jan 1, 2003

One of the features of modern life has been the increasing speed of change. We see this in many facets of activity, but in few areas more clearly than in the financial sector. The speed of communication and the advent of screen trading have made world markets one.We have titled this presentation "Cycles". It has been the conventional wisdom that Economies, Metal Prices, Equity Markets, etc. move in cycles. The objective of our presentation is to examine these cycles, to comment on the interrelationships, and to postulate where we are in The Current Cycle". We will draw conclusions as to where one should direct effort in the Mineral Scene over the next decade or so.Throughout this discussion we will use various terms to describe Time. The "Short Term" is typically meant to refer to the next six months: the "Medium Term" is one to two years; and the "Long Term" is the three to five year horizon.

Jan 1, 1990

By E du Plessis, J Kapusta, J L. Mauk

The world-class Bulyanhulu gold deposit (375 t Au) is in the Sukumaland greenstone belt, Northwestern Tanzania. The main mineralised quartz vein structure, termed Reef one, occurs at the contact of felsic metavolcanic rocks on the hanging wall and mafic metavolcanic rocks on the footwall. Reef one is dominated by massive quartz together with pyrite, pyrrhotite and minor chalcopyrite. Alteration in the footwall basalt is characterised by extensive chloritisation, calcification and silicification, which is strongest near the vein. Sericitisation also locally occurs adjacent to the vein. Metamorphic hornblende and plagioclase (albite) increase in abundance at a distance of 120 m from the vein and reflect the gradation into less altered rocks. The increasing abundance of chlorite, calcite, quartz and local sericite near Reef one, coupled by replacement textures suggests that most of these footwall minerals are the product of hydrothermal alteration, rather than regional metamorphism. Geochemical data shows slight enrichment in Ca, Fe and As towards the vein, whereas Zn in several drill holes becomes enriched away from Reef one. The Bulyanhulu gold deposit is a quartz-pyrite-chalcopyrite shear controlled vein with an adjacent extensive chlorite-quartz-calcite hydrothermal alteration zone (and a limited local sericite alteration zone) that passes to a hornblende-albite metamorphic assemblage further into the footwall.

Jan 1, 2002

In recent years, wide consideration has had to be given to methods of improving the condition of the mine environment in many coal mines, and significant developments and changes have evolved. Thus even after substantial increases inòair flow rates at the working place (they have increased over three fold in the last generation), environmental conditions have arisen for which it has been necessary to introduce or consider: i) additional ameliorative measures, such as good housekeeping; ii) layout changes: such as Y or Z layouts; iii) homotropal ventilation; and iv) air conditioning. In certain countries, consideration has been given also to: v) additional payments reduced working times; vi) heat acclimatisation programmes; and vii) the use of cold or cooling suits At many hot and humid mines, the principal benefits from adopting (i), (ii) and (iii) have already been realised. At such mines,

Jan 1, 1983

In recent decades the awareness of environmental issues by the general public has developed at an accelerat- ing rate. This is the result of a number of factors including more scientific knowledge of environments and of the impacts of modern society upon them, higher levels of education, the opportunity for people to travel more, and the success of the various communication media in bringing in- formation to the communities of the world about such environmental crises or threats as the smogs of Los Angeles and London, the Torrey Canyon and Santa Barbara oilspills, Minamata disease in Japan, the spread of the Crown of Thorns starfish, the disposal of toxic industrial wastes into the Upper Rhine, the discovery of high mercury and zinc contents in marine foods in southern Australian waters, and the proposal to mine limestone at Precipitous Bluff in Tasmania.

Jan 1, 1975