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Low-grade, porphyry copper type mineralization at the Moonmera prospect is related to the intrusion of a granodiorite porphyry mass into the Upper Permian "Gracemere granodiorite". Significant copper mineraliza- tion appears to be associated with the alteration assemblage quartz-sericite- kaolinite. The ore shell is surrounded by a zone where montmorillonite and kaolinite are in greater abundance and this assemblage is over- lapped, mainly at depth, by potassium feldspar alteration. Secondary biotite is abundant throughout the mineralized zone. Preliminary sulphur isotope results on the sulphide mineralization are compatible with a magmatic origin for the sulphur.

Jan 1, 1974

By Meloy TP

Several important, fundamental aspects of the grinding behaviour of mineral systems are addressed. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations was used to solve the steady-state and dynamic population balance model (PBM) grinding equations to obtain the mill matrices and grinding selection and breakage rate functions, respectively. The fact that the PBM model equation Inverse Problem is degenerate or underspecified is demonstrated. Multiple solutions to the same PBM equations are provided. It is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the Arbiter-Bhrany normalisation assumption. The severity of the non-uniqueness problem for steady state grinding is demonstrated in several examples using typical feed distributions and mill matrices. In addition, it is also demonstrated that when higher than single powers are used in steady-state mill matrix expressions during simulation or calculation (or iterative procedures are used during numerical simulation) and four or more size intervals are used considerable amount of error is propagated throughout any calculation. Each solution to a PBM, while giving the same prediction during a single mill pass, gives different solutions or predictions for mill composition upon subsequent passes. In addition, it is shown that there is a problem with building up a grinding mill knowledge base with PBMs. A similar analysis was done for the dynamic or kinetic PBM equations. The fact that the dynamic PBM Problem is degenerate or underspecified is also demonstrated. Multiple solutions to the same dynamic PBM equations are provided. Again, it is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the normalisation assumption. Each solution to a dynamic PBM, while giving the same prediction for a given grinding time interval, gives different solutions or predictions for mill composition for other grinding times. Actual experimental grinding data was assessed to determine the functionality of mill selection and breakage functions. The functionalities obtained through constraints were compared with those obtained with the normalisation assumption of Arbiter-Bhrany which relates breakage functions to particle size distribution. The capability of the population balance model to predict grinding behavior over time in various mineral grinding systems was assessed. The required functionality of selection and breakage functions for effective prediction of grinding behavior in mineral systems is discussed.

Jan 1, 1993

Discovered in 1896, the Sons of Gwalia orebody is located in a ductile mylonite zone within a sequence of Archaean pillow metabasalts and minor metasediments of greenschist facies which are variably sheared.The ore zone has good continuity, being 110 m wide and 500 m long, dipping 45 degrees east and plunging 70 degrees to the south to a depth of 1500 m downplunge. A strongly-developed foliation is present together with a prominent lineation paralleling the plunge. The mylonite zone consists of unmineralised chlorite schist and a 'U' shaped mineralised zone of chlorite-sericite schist with varying amounts of quartz-carbonate as veins parallel to foliation, boudins, and locally as massive quartz-carbonate. Pyrite is the dominant sulphide present.Grade control utilises RC holes on a 10 m x 10 m pattern, with infill blast rig holes 5 m deep where necessary.Some visual control of ore boundaries is present and, combined with good ore continuity and a knowledge of the structure of the orebody, enables cost-effective grade control to be achieved. To-date, over three million ounces of gold have been produced from the orebody.

Jan 1, 1993

By Durucan S

The southern Attiki peninsula is a very interesting area from an environmental point of view. The port and the city of Lavrio is situated at the east coast of the peninsula with about 10 000 inhabitants and there are also a few villages in the vicinity. The south-eastern part of the peninsula hosts the famous Lavrio mines which exploited the silver bearing orebodies of the area for more than 25 centuries. As a result, soils around the city of Lavrio are polluted with high heavy metal loads. The area is also of archaeological interest, as there are well preserved remnants of ancient mining and processing plants and archaeological sites. Soil samples collected from an area of approximately 120 km2 around Lavrio were analysed for their metal contents and the spatial distribution of the concentrations of ten selected elements were estimated from these data sets. The spatial data analysis and transformation capabilities of Geographic Information Systems, combined with extensive mining and geological data, helped the authors to identify the extent and causes of metal pollution around Lavrio.

Jan 1, 1995

By Brockway DJ, Holmes RJ

A natural gamma-ray gauge has been devel- oped for discriminating overburden and inter- seam sediment from low ash coal located on a moving conveyor belt. It is based on the difference in natural radioactivity of the sediment and overburden compared with the low ash coal, which is detected with a highly ef- ficient "Polyscin" NaI(T1) gamma-ray detector located underneath the conveyor. Gauges have been successfully installed on the bucket wheel boom of the two coal dredgers at the Loy Yang Open Cut. They are used to warn dredger operators that they are digging overburden or sediment and that action is required to avoid the sediment or divert it to the waste dump rather than send it to the coal bunkers at the power station.

Jan 1, 1987

By Hagan T. N, Tucker A. J

The Cumnock Open Cut Mine (COCM) is located in the Hunter coalfield in New South Wales. Five coal seams are being mined, mostly by drilling and blasting, loaders and excavators, and trucks. The annual production of coal is 1.3 million tonnes. Overburden and interburdens consist mostly of siltstones and medium to thickly bedded sandstones. The strata dip to the south-east at approximately four degrees. There are no major faults in the rock mass.

Jan 1, 1995

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

By M Noppe, I Glacken

There are many critical nodes along the mine value chain, from orebody to mineral product, and inter-disciplinary input is required to analyse the variability and uncertainty at each node in order to identify and mitigate areas of risk. Mining differs from many other industries in that the variability in the product is dictated largely by the inherent nature of the input material (the orebody). The true characteristics, including the variability of the orebody, are never known exactly and are instead based on estimates derived from sample data. A further difference is that bottom-line gains are largely controlled by world commodity prices, which can vary with time, rather than by local supply and demand issues. Methods for identifying, reporting and responding to this inherently variable raw material are discussed. These include analytical and reporting methods, equipment and software, risk analysis and reality checks (eg reconciliation). Sampling results, mineral resource and ore reserve estimates and economic assumptions are a function of the variability of the orebody. Risk quantification should be expressed as a level of confidence, which takes into account the scale or period over which the risk is being assessed (life-of-mine, annual or shorter production periods) and should convey the likelihood, severity and consequence of occurrence of a given event. The future generation of mining specialists needs to understand the entire mine value chain to better manage risks and maximise mine dollar-value.

Jan 1, 2002

By Harris J. W

Mr. Gillie and Mr. Harris have given us a wealth of information and food for thought on the vital subject of information and food fo rthought on the vital subject of reducing costs and mention considerable saving in some of the larger items. There are a number of points on which I would like further information, but I will confine my remarks to a relatively small saving which is of particular interest in view of another paper to be presented this afternoon.Mention is made of a 50 per cent reduction in the amount of zinc used in the precipitation of gold slime from the pregnant solution. Would Mr. Harris enlarge on the methods by which they obtained this reduction; and could he give an actual figure of zinc consumption either by ton of ore treated or per ounce of bullion recovered.AuthorsWe consider the reduction of zinc is due to improved clarification of the pregnant solutions. The sand clarifiers used prior to the installation of the 50 ft. -thickener were not satisfactory due mainly to the blending of the hessian and matting under the sand. Under these conditions the leaf clarifiers were fed with overflow solution from the clarifiers and were overloaded in consequence. The addition of Calgon has also been beneficial.The present consumption of zinc per ton of solution treated is 088 lb. per ton.A. L. "Keats (No,rth Broken Hill Limited)In the operation of milling equipment there is a progressive increase in maintenance expenditure during the life of a machine, so that when comparing the cost of operating old equipment with the cost of operating new equip...

Jan 1, 1956

The need for the hydraulic transportation of coal in the New South Wales coal industry, both from the coal face to the surface and from the coal mine to the consumer or the port for export, is explained. Details of research projects currently in progress and involving the hydraulic transportation of New South Wales coals are given together with information on the hydraulic transportation of coal in the United States of America. The potential of hydraulic transportation as a viable alternative to the proposed expansion and upgrading of the New South Wales railway system to meet the projected New South Wales coal production to the year 2000 is described.

Jan 1, 1980

By Potter OE

There appears to have been a swing away from the study of mathematics, the physical sciences, foreign languages and the classical humanities subjects by many students in high schools in Victoria. The same trend is believed to be occurring in other states as well. This has the direct result of many students entering tertiary studies inadequately prepared academically. This is particularly true in engineering and commerce. The position as far as postgraduate training in the areas of concern to the minerals industry is critical with almost no Australian nationals undertaking advanced technological studies.

Jan 1, 1981

By Sullivan BJK

The 1100 orebody is a massive copper sul- phide orebody which contains a major portion of the Isa Mine copper ore reserves of 130 million tonnes at 3.2%. The underground mining of a deposit as large as the 1100 orebody is technologically a complex operation as extraction strategies have to be evaluated with reference to 1. rock mechanics considerations, 2. safety and environmental standards, 3. production and operating require- ments and 4. metal recovery and costs. The mining philosophy in the orebody has undergone considerable change over the past five years as a result of experience and improved technology. At this stage, primary stopes are extracted by high rise sublevel open stoping and pillars by slot and mass blast drawn either under rock fill or as an open Stope.

Jan 1, 1978

The three systems of mining in use in the Southern Coalfield of New South Wales are bord and pillar with or without subsequent extrac- tion, longwall and shortwall. Bord and pillar with extraction is regarded as the conventional system. The application of continuous miners and powered roof supports (Shortwall) to coal min- ing has, grown in recent years from something of an oddity among extraction systems to an acceptable and viable approach in certain min- ing environments. The method can be applied in a high proportion of situations where normal pillar extraction is practised with advantages over the conventional approach. These advantages extend to both safety and efficiency aspects and also include better utilization of coal reserves. It holds hope for further gain in efficiency because its simplicity of layout lends itself to achieving the goal of contin- uous haulage towards which operators are always striving.

Jan 1, 1976

The coking coal produced by Utah Development Company in the Bowen Basin is processed by a dual system of dense media cyclones for the 30mm x 0.5mm feed and flotation for 0.5 x 0mm material. The basic metallurgy of these processes will be presented with emphasis on the operational characteristics which are peculiar to coal. Potential areas for process improvement by the application of more sophisticated control systems will also be discussed.

Jan 1, 1978

Education and Training for the minerals industry has been identified as one of the key priorities by the AusIMM and many closely related groups. The AusIMM Education Taskforce has been engaged, through a visioning exercise, in evaluating what minerals education and training should look like by 2025. A common recurring theme is that for minerals education and training to be efficient and effective into the future, it needs to be comprehensive and inclusive. Some previous attempts to achieve efficiency and effectiveness have had limited success, mainly due to approaching the issues involved from a narrow, singular perspective. This paper outlines that the achievement of the desired outcome may require an approach that parallels the same techniques that are used for multi-dimensional mine planning, treating tertiary minerals education and training in a similar way to the planning involved for a complex orebody. Just as efficient and effective mine planning requires engagement and understanding of many factors, so too does engagement with tertiary minerals education and training. The major factors that need to be considered are outlined in the paper, including: levels of tertiary education and training; Australian Qualifications Framework (AQF), Levels 1 to 13: systems of minerals education and training, such as higher education, (mainly universities), industry/professional associations and licencing requirements, vocational education, (mainly TAFE) and workplace programs; types of minerals or mining methods involved; volume of delivery; stage in the flow sheet, (geology, mining, beneficiation, extraction, refining). For comprehensive mine planning there is the need to develop links or roadways and openings between different levels of a mine. Similarly, to achieve a comprehensive tertiary minerals education and training model, there is a need to develop pathways, recognition and credit transfer between the various levels and components of minerals tertiary education and training.

Jan 1, 2005

Modern Management Systems for Higher Margins By Malcolm Roberts, Catalyst for Corporate Performance Ltd Malcolm Roberts put the case for changing systems in order to change behaviours and attitudes and improve productivity. ""The key to lifting margins is changing systems."" A system is anything that drives ways of doing things. Sometimes these are formal, and documented, and sometimes they are not. Improving productivity The way to dramatically improve performance is to use the systems. Roberts stressed that if systems and processes are under control, the benefits of automation are huge. If they are not, the benefit of automation will be lost. To improve productivity, you need to: ò identify what to change in the process, ò use the proven methodology to systematically improve the process, and ò change what people do - change work practices.

Jan 1, 1997

The ore deposits investigated are composed primarily of hcmatite and can be grouped into three categories depending on the amount of leaching of silica and carbonate which has occurred from the original iron formation, and on the amount of recrystallization of the hematite. Minor constituents are magnetite. goethite, and quartz.Texturally. there are five different types of hematite, formed at different stages during the genesis of the ores.These are1. anhedral hematite grains formed by recrystallization of hematite already present in the original iron formation.2. hematite formed by martitization of euhedral magnetite, 3. massive aggregates of fine- to medium-grain hematite formed by recrystallization of (l) and (2).4. tabular or prismatic hematite grains occurring around the boundaries of the massive aggregates or martite euhedra. and in fractures and5. specular hematite. which is present in fractures in ore types (l) to (4).Minor and trace-element analyses, determined using an electron-probe microanalyser. indicated that only silica (less than 0·01 per cent) and cobalt (less than 0·002 per cent) were present in the magnetite and hematite from unaltered iron formation and in the hematite from the ores. Low concentrations of trace elements are typical of magnetite in ores formed as marine precipitates. On the basis of the analyses alone. it proved impossible to distinguish between the five hematite types. A determination of the variation in rare-earth trace element contents between iron oxides in the iron formation and iron oxides in the ores indicates that the rare earths were depleted during ore formation. A possible explanation is that they were removed in solution with silica as it was leached from the iron formation.

Jan 1, 1971

By Scott IA, Jefferson C, Dipasquale S

This paper describes the use of modelling and simulation techniques in the analysis of the heavy medium plant at the Lead/Zinc Concentrator of Mount Isa Mines Limited. The objective of the study is to determine how to increase heavy medium plant recovery at a higher than current rejection rate in order to achieve the desired throughput through the grinding and flotation sections of the concentrator. Three options were considered: 1. Install smaller aperture preparation on screen to enable the cyclones to be fed finer materials. Install smaller diameter cyclones. 3. Maintain low viscosity medium.

Jan 1, 1987

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 A Struminski

The principles of occupational risk evaluation resulting from the improper ventilation of the underground mines were presented. It was shown that the risk level implies the appropriate planning and usage of prevention methods. That approach is fundamental in the ventilation, fire and climate safety management in the copper ore mines. The paper uses the adequately modified Risk Score method.

Jan 1, 2003