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By A T. Owen, F A. Benn, J D. Swift, D M. Labbett, A F. Grabsch

The AMIRA P266 æImproving Thickener TechnologyÆ series of projects has sought to provide a firm scientific basis for feedwell and thickener design, a requirement as pressures on water usage in the minerals industry increase. While advanced computational fluid dynamics modelling of feedwell processes has generated the most obvious and successful applications to improving the performance of operating units, such outcomes have drawn heavily on parallel studies into flocculation fundamentals. Central to this has been the development of a linear pipe reactor system that allows the kinetics of flocculated aggregate growth and rupture to be measured for thickener feeds under turbulent pipe flow conditions. This ensures much greater control of the intensity and duration of applied shear than is possible with conventional flocculation test procedures, offering insights into flocculation processes that would be otherwise hidden in time-averaged measurements.

Jan 1, 2009

By Seedsman RW, Duncan Fama ME

Mine design procedures will be revolu- tionised by technological developments in computers, software, database construction and management, and numerical modelling programs. Developments in geotechnical databases will be required which utilize geological and geomechanical tests to supply appropriate input for numerical models. Techniques utilizing sedimentological and structural modelling are described. The capacity of current numerical models in mine design is outlined and a program for developing a fully integrated mine design package proposed.

Jan 1, 1987

The geologic settings, geochemistry of host rocks, mineralogy and metal values in modern back-arc volcanic-hosted massive sulphide (VHMS) mineralisation are very similar to those in many ancient polymetallic VHMS deposits. The geology, distribution and styles of seafloor mineralisation in modem back-arc basins, especially the eastern Manus and Lau Basins, southwest Pacific, are compared to VHMS deposits in the Mount Read and Mount Windsor districts of Australia . Based on exploration and research in modem back-arc settings, geologists are now observing the direct analogues of the polymetallic VHMS deposits currently being exploited in ancient back-arc volcanic belts throughout Australia and the world.

Jan 1, 1995

By D K. Weatherley, A N. Mainza, I Govender, L M. Tavares, M S. Powell

It is understood that rocks do not instantaneously transport along a grinding mill and are consequently not perfectly mixed, but this is conveniently overlooked in mill modelling. A lack of understanding of the transport phenomenon and the difficulty of modelling realistic transport in a complex tumbling system, contribute to this. Visual observation of segregation in AG and SAG mills and measured lag time of mill response to changes in feed provide evidence of the influence of axial transport within mills. Incorporating this lag in dynamic models should underpin dynamic simulation of milling circuits for design and for model-based control. Limitations and errors in predicting the influence of increased power via mill length versus diameter, inability to predict pebble production, and a lack of the differential in residence time across rock sizes and competences, all contribute to inadequate design prediction that can be especially acute for large Autogenous mills. Examples of dramatically under – and overloaded pebble regrind circuits and the inability to predict pebble load in AG milling discouraging the application of this energy-efficient option, point to the need for predictive modelling of breakage by competence linked to transport through and out of mills. Incorporating progress in granular flow and mixing, coupled to computational advances enable models to be based on complex breakage and transport models at high spatial resolution. This allows mechanistic models to simulate thousands of times faster than real time, opening the door to more accurate mill design, including dynamics in process simulation and to live simulation for process control – all with advanced mechanistic models. The value of grasping this opportunity is not easily refuted.

Aug 24, 2022

By Peck W

The tunnel alignments investigated for the Gosford Regional Sewerage Scheme are located in the Terrigal Formation and are covered for most of their length by a thick blanket of soil and weathered rock. The following techniques were found to be most effective in geotechnical investigations for tunnelling in this area: air-photo interpretation, seismic surveys to pinpoint drilling targets, in-situ measurements of strength,deformation modulus and permeability in cored holes, and the construction of rock- mass models. Cross-hole seismic modulus measurements, surface resistivity soundings and electric well-logging techniques were found to have limited applicability due to adverse local conditions.

Jan 1, 1976

By S Azam

Coal is a vital energy source and source of carbon for metallurgical applications, contributing significantly to the world economy. Coal mining and processing involve multiple processes that generate Respirable Coal Mine Dust (RCMD), one of the primary sources of health hazards for coal workers. Since 2000, the rate of Coal Workers’ Pneumoconiosis (CWP) has continually increased in the U.S, with severity of the cases also worsening. Increasing evidence shows that exposure to RCMD in coal workers is a high-risk factor for lung cancer, which causes more deaths than the following three major cancers combined in the US Recent observations show an increased incidenceof CWP or other lung diseases, particularly among young miners in the Appalachian basin. The CWP prevalence in Appalachia is four times higher than the national average. Although various regulations are in place, the resurgence of such disease among coalminers demands additional efforts to better understand all the possible facets of coal dust toxicity, taking insights from current interdisciplinaryresearch efforts. One such important field is the interaction of coal dust with moisture in underground mines. Although moisture is prevalent and dynamic in an underground mining environment, it has never been evaluated for its impact on modifying the toxicity of coal dust and transport or flow behaviour. However, research conducted in atmospheric sciences in the past decade makes it clear that moisture in the atmosphere can significantly alter the behaviour of mineral dust. This paper is a part of research aimed at understanding how moisture interacts and alters the characteristics of coal dust. Such insight is crucial in understanding the potential toxicity of coal dust and developing mitigation technologies.

Oct 12, 2022

By S Youds

The backfilling operation at Olympic Dam mine supports a 9.8 Mtpa underground Long Hole Open Stoping (LHOS) operation. It involves a combination of Cemented Aggregate Fill (CAF), surface rockfill and underground rockfill. The fill material is introduced from the surface via boreholes into the top of the stopes. Due to the deleterious effects of the dust and the thickness of the atmosphere in the stope it is not possible to view the filling process either at optical or infrared (IR) wavelengths. The need for a means to measure the filling process is driven by the placement of both rock and CAF fill in the stopes. The large volumes and high relative cost of CAF makes the minimisation of CAF fill a business priority. Incorrect filling can lead to the sterilisation of ore reserve. The use of millimeter wave radar to view through the haze to give real-time data on the relative positions of the different fill masses is being developed as an in-stope fill monitoring device. This paper reviews the salient points of the technology and its potential use in the backfilling operation at Olympic Dam. The broader potential of this technology for use in the mining industry by æseeingÆ through water and dust laden environments such as that found in stopes and ore passes is also discussed.

Jan 1, 2002

By Locke CA

Geophysical signatures of the Taranaki and Tongariro volcanoes reflect similarities in their age, composition and hydrothermal histories, but also reflect differences in host rock settings and edifice evolution. The Taranaki volcanoes have strong positive gravity anomalies showing that their edifices largely consist of dense andesite which reflects substantial lava production or dyke injection during construction and that large sub-edifice dykelstock complexes occur. In contrast, the Tongariro volcanoes have strong negative gravity anomalies indicating low density edifices of volcaniclastic material; no sub-edifice intrusions can be identified, probably because of the lack of density contrast with host basement rocks. Strong positive magnetic anomalies over the younger cones can mainly be attributed to near-surface andesite lavas or dykes whereas subdued magnetic effects are associated with hydrothermally altered zones within both edifices and sub-edifice intrusions.

Jan 1, 1995

The Permian rocks at Gympie were first studied as far back as 1868 in conjunction with the discovery of gold. The relationship of the Gympie Group to other sequences in the Gympie Composite Terrane is an important subject of investigations in a new mapping project of the Geological Survey Program of the Department of Resource Industries.In two areas the Gympie Group has been divided into four defined formations. They are the Highbury Volcanics (base), Ram mutt Formation, South Curra Limestone and Tamaree Formation (top) in the Gympie area, and the Mant basalt (base), Kolbar Formation, Gigoomgan Limestone and Teebar Formation (top) in the Gigoomgan area. Geochemical and lithological evidence from the basal volcanics of the Gympie Group (Highbury Volcanics, Mant basalt) indicate that they developed in an intraoceanic island arc setting. The overlying volcaniclastic sediments (Rammutt Formation, Kolbar Formation), which contain some continentally-derived material, are mainly of local derivation and shallow-water marine. A hiatus is present at the top of the Early Permian Rammutt Formation and Kolbar Formation. Following the hiatus, limestone sedimentation characteristic of a basin of restricted circulation developed in the Late Permian. There is some evidence of a hiatus between the limestone deposition of the Gigoomgan and South Curra Limestones and the overlying probable turbidite deposits of the Teebar and Tamaree Pnrmatinnc

Jan 1, 1990

Controlled recirculation of nine ventila- tion air is becoming an acceptable practice world-wide. A brief review of operating and planned schemes is given which illustrates the various purposes for using controlled recircu- lation in different types of mines. A de- tailed description is given of the operating and proposed schemes on South African gold mines. This is followed by a description of some theoretical and experimental work which has recently been carried out into certain important aspects of controlled recircula- tion. This includes: safety systems, dust filtration, blast contaminant removal, radia- tion hazards and the development of an expert computer program for the design of controlled recirculation systems.

Jan 1, 1988

By Dodd SF

Valuation of mining companies and their underlying assets prepared by brokers' analysts are, by necessity, approximations. The reliability of the valuations is entirely proportional to the quality of available data, the reliability of forecasts and the nature of underlying commodity price assumptions. The latter is perhaps the greatest single cause of gross variations in company and asset earnings estimates and- valuations. Assumptions are often necessary regarding commodity price achievement based on commodity hedge positions. Public disclosure from listed companies provides a sound base from which to project earnings, cashflows and balance sheets. The uncommon disclosure of projected production and cost schedules often reduces the reliability of future estimates. The application of reserve and resource estimates is contentious with practitioners applying differing weightings to importance of resources in estimating mine lives (and therefore cashflow streams). Valuation methods applied in equity markets usually focus on relative value and the identification of pricing anomalies. The commonest ""rules of thumb"" applied in the valuation of mining companies (and therefore their underlying assets) is with the use of year specific price/earnings (P/E) and price/cashflow (P/CF) ratios, with low multiples suggesting undervalued assets, high multiples overvalued situations (but these rules can often be clouded by market expectations of underlying commodity price movements). Another simply applied valuation tool is to examine the examine the value placed on reserves and resources by the market. Inexpensive gold in the ground (expressed as $ of market capitalisation per ounce of reserves or resources) might indicate a buying opportunity, but the market does discount the value of gold in the ground prior to mine development and where development risk is perceived.

Jan 1, 1994

Since early 1968 the Bureau of Mineral Resources (B.M.R.) has carried out VLF-EM test surveys in various parts of Australia and Papua. The aim of the work, primarily, was to examine the effect- iveness of the method as an exploration tool under a variety of Australian conditions. Selection of test areas was determined by the availability of geological, geophysical and drilling information and by the desirability to include a variety of physical variables such as depth of weathering and topography. The aim of the present account is to review the results of this work and to make an assessment of the method available to the mining industry. The author wishes to acknowledge considerable assistance both by way of data and discussion provided by Messrs. Paul Gillespie (B.M.R.). and John Haigh (formerly B.M.R., now Senior Geophysicist, McPhar Geophysics Australia.) The article is presented with permission from the Director, B.M.R.

Jan 1, 1971

A small-charge rock excavation method based upon the Penetrating Cone Fracture (PCF) technique has been demonstrated to be capable of excavating the hardest of rocks. The PCF technique involves drilling shallow holes in the rock which are then pressurised at the bottom by a propellant charge device. A controlled fracture is initiated at the hole bottom comer and propagates in such a manner as to excavate the rock at an energy efficiency three to five times better than explosives. Due to the low flyrock velocities and airblast pressures realised with PCF breakage, the method may be used in close proximity to equipment and personnel and is thus ideally suited for integration into continuous hard rock excavation systems. Over the past 18 months full-scale testing of the PCF method has been carried out in mines in the US and Australia. This testing has utilised a 76 mm diameter gas injector for hole pressurisation and employed propellant charges ranging from 80 to 320 gm. In addition to extensive data on rock excavation performance, data on ground motion, dust, carbon monoxide and air blast have been obtained. These data indicate that none of the parameters associated with PCF breakage are detrimental to the development of PCF-based, continuous-excavation machines. Machines employing the PCF method may range from simple single-boom machines for secondary breakage and small precision-blasting jobs to integrated systems with several booms, continuous mucking capabilities and ground-support equipment for drifting and tunnelling.

Jan 1, 1993

The advancements achieved in rapid tunnelling in the 60's and 70's have been notable. It is unfortunate that shaft sinking has not enjoyed equivalent advances and there are many good reasons why this is so. Technical and commercial considerations have held back development and continue to do so despite the increasing urgency in the search for minerals and energy. By the careful selection of an appropri- ate project and the application of specialist engineering the Bdard took advantage of a unique opportunity to apply a mechanised shaft borer in field conditions.

Jan 1, 1981

By M Fahey, A B. Fourie

Over the past ten years, the mining industry has witnessed the introduction of a new and innovative mine filling technique known as paste fill, which consists of placing full stream tailings with small amounts of binder and water into underground stopes. Paste fill has benefits over traditional backfill methods, such as higher solids contents than hydraulic fill and easier transportation than rock fill. From a geotechnical perspective, the behaviour of very fine material in a fully saturated state can be complex, particularly when binder is added. Previously, there has been no rigorous solution to understanding the paste fill deposition process, resulting in uncertainty regarding critical aspects such as barricade load calculations. This uncertainty has the obvious consequences of potential barricade failures (including at least 12 over the past four years), and for many operations attempts to deal with this uncertainty has led to excessively conservative filling schedules, restricting production. This paper presents an application of Minefill-2D, the first rigorous model capable of representing the paste fill deposition process. The model couples the processes of material accretion, consolidation and cement hydration to calculate the distribution of stress around a stope (including the total stress applied to barricade structures) during filling. Minefill-2D is a finite element numerical program, which has been verified using laboratory element tests, centrifuge tests and in situ measurements (Helinski, 2008). The authors present a sensitivity analysis, carried out using the model, to demonstrate some of the critical and less critical aspects relating to paste backfill deposition. The results of this sensitivity analysis are used to devise a fill management strategy that can be utilised to minimise the risk of barricade failures and maximise fill rates where appropriate.

Jan 1, 2008

Rheology is the science which deals with the deformation and flow of matter. Thus rheology is concerned with the flow of any material. The mining industry is concerned with digging things out of the ground, extracting the good stuff and throwing away the bad stuff. In the upgrading processes associated with mining, ie mineral processing, wet techniques are used where the primary material being handled is a particulate fluid, ie a suspension. After the processing operation, with the concentrates extracted, what is left behind generally is a wet material in suspension form, which may or may not contain reagents harmful to the environment. The amount of waste generated in any of the mining processes is large, in fact, the mining industry is the largest generator of solid waste in Australia. In order to minimise the waste generated within the industry it has become of interest to handle the particulate fluid wastes, or suspensions, at high concentrations, thus removing water and some of the reagents which may be harmful to the environment. The resultant highly concentrated suspension is a non-Newtonian fluid. Rheology deals with the flow of non-Newtonian fluids; therefore a combination of rheological understanding of high density suspensions, in conjunction with an understanding of the environmental problems being faced by the mining industry, can and has led to improved methods of waste disposal in the industry, ie waste minimisation. This paper describes the progress that has been made in the development of dry disposal technology in the mining and minerals industry in Australia.

Jan 1, 1998

Peko Mines, a Division of Peko-Wallsend Operations Limited (PWOL) has operated several small underground mines in the Tennant Creek district of the Northern Territory supplying ore to a central treatment plant. The Argo Mine is the most recently developed by Peko Mines. A magnetic anomaly was identified from low level airborne magnetics in 1960 and drilling, which commenced on the site in 1969, was halted in 1974 and resumed in 1980 following the rise in the price of gold. By mid 1983 a resource of + 200 000 tonnes of 12 g/tonne Au had been outlined and a decision to develop the resource was taken following the drilling of three further diamond drill holes which did not significantly alter the value of the resource. The small size of the orebody could not support the full capital cost of two shafts and a single entry mine plan was developed to extract the ore at a rate of 15 000 tonnes per month and to provide all the safety features, ventilation systems and services of a two shaft mine. In December 1983 a contract was let to Allied Constructions Pty. Limited (Allied) to sink and equip a 4.8m shaft to a depth of 410m and to convert the headframe and winder, which are leased for the life of the mine by PWOL from Allied, from a sinking to a production configuration. Shaft equipment designed by Hardcastle & Richards Pty. Ltd. (H & R) in conjunction with PWOL includes a skip/cage, counter- weight, and an auxiliary cage on rope guides, a sealed ladderway and exhaust air ducts.

Jan 1, 1986

By Cooper W. C, Stokes M. A

Proterozoic gold deposits in the Pine Creek Geosyncline are at present receiving renewed attention with the opening of old mines and several new discoveries. This important polymetallic province contains occurrences of gold, base metals, tin, tungsten, tantalum, platinum, palladium and aluminium. These resources have been exploited over the past century with periods of major interest during the turn of the century and during the past 20 years. Economically viable resources of predominantly gold, eg Pine Creek, Woolwonga, Brocks Creek and Union Reefs, and Ag-Pb-Zn, eg Woodcutters are currently in development or being mined. A variety of genetic models, ranging from magmatic through hydrothermal to syngenetic, have been postulated in the past for the formation of gold deposits in the Pine Creek Geosyncline. The first discussion on the regional geological factors that control ore deposition in the Brocks Creek-Howley District was by Sullivan and Iten (1952). They recognised that the most important ore deposits are associated with anticlinal and domal structures and that granites may be a controlling factor in the localisation of the mineralisation. More recently a group of authors, Needham and Roarty (1980), Goulevitch (1980), Nicholson and Eupene (1984), Sanger-Von Oepen, Friedrich and Kater, (1988), Nicholson and Eupene (1990) and Kruse, Whitehead and Mulder (1990) have suggested an exhalitive syngenetic origin, or remobilised syngenetic during dolerite intrusion and/or regional deformation, for gold mineralisation, especially those associated with South Alligator Group lithologies (eg Bridge Creek, Mt Bonnie group of mines and Cosmopolitan Howley). Studies carried out at the Bridge Creek and Western Arm Prospects over the last three years suggest that syngenetic models for gold mineralisation are less relevant to gold mineralisation in the Howley District than first thought (Wall, 1989; Partington, 1990). The Bridge Creek prospect has been cited as an example of a syngenetic-syngenetic remobilised deposit (Oepen, Friedrich and Kater, 1988) while the Western Arm prospect is more clearly a vein hosted epigenetic deposit and a comparison of the styles of mineralisation at both prospects will be made. The nature of the gold mineralisation at both prospects will be described and compared, and possible genetic models for gold mineralisation and their relevance to regional exploration discussed.

Jan 1, 1994

By Aspinall T. O, Bell L. C

Increased awareness and stricter enforcement of regulatory requirements for adequate rehabilitation of surface mining sites has made environmental planning an essential part of strip mine planning. Rehabilitation is site specific and should be based on data which relate to that site. Cost-effective spoil pile design to minimise erosion is an important part of rehabilitation. Spoil pile design is an integral part of strip mine design. QCT Resources Limited has provided a postgraduate scholarship toward research in this area. The controlling factors of spoil pile design are post-mining land use, drainage requirements and degree and rate of erosion. The extent to which mine design is controlled by these factors is determined by regulatory requirements. To plan acceptable rehabilitation programs, erosion processes must be accurately modelled, and a range of erosion prediction models are available. Useful prediction models can be placed in two categories with the first category containing soil loss prediction models which can be used to predict the amount of soil lost from an area over a short or long term basis. Models in this category include the Universal Soil Loss Equation (USLE), Water Erosion Prediction Project (WEPP), Griffith University Erosion and Sedimentation System (GUESS) and Chemical, Runoff and Erosion from Agricultural Management Systems (CREAMS). The second category contains topographic evolution models which give an indication of the long term morphological development of a formed surface subjected to erosion processes. Models in this category include "Topog", Willgoose's Physically Based Catchment Evolution Model and Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS). The USLE has been used in the agricultural field for soil loss prediction. To apply the equation to mine sites in Central Queensland, it is necessary to understand the factors affecting erosion at the sites. This understanding should allow the variables of the equation to be quantified. The rainfall factor applied in the USLE is independent of engineering design or soil management techniques. The factor of spoil erodibility is dependent on the material's physical and chemical properties and can vary from site to site. In the equation, the topographic factor, cover and management factor and conservation practices factor can be varied by design to reduce erosion on rehabilitated areas.

Jan 1, 1991

Interactive data exploration is essential for visualising grade distribution and geological controls on orbodies. Quick and appropriate computer techniques for making daily 'value adding' decisions include routine imaging of numerical data suc

Jan 1, 1998