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By Lai KF

The Hellyer orebody is a fine grained, massive sulphide Pb-Zn-Ag- Cu-Au deposit located in western Tasmania. Initial testwork showed that the orebody would be difficult but not impossible to treat by conven- tional flotation. A staged programme-of work was commenced to demon- strate that marketable concentrates could be produced with satisfactory recoveries. Following laboratory testing of drill core to define two flowsheets, bulk samples of Hellyer totalling 20,000 tonnes were trialled at 6 tph in the Cleveland concentrator over six months. The high through- put and extended duration of the trials ensured maximum confidence in the results and that scale-up to subsequent plants would be with a mini- mum of risk. The milling trials were successful and the Cleveland concentrator was expanded in early 1987 to treat 250,000 tpa of Hellyer ore to produce 85,000 tpa of bulk concentrates. Late in 1987 construction commenced on a 1 mtpa concentrator at Hellyer to produce separate copper/silver, lead, zinc and bulk concentrates.

Jan 1, 1988

A feasibility study will fail its objective if it does not identify and then correctly assess, all the risks which could have a substantial impact on the financial viability of a project. Before this assessment can be undertaken, one needs to understand the risk profile of the entity which is making the decision about the project. Some of the commonly encountered issues when assessing project risk are related to the problem of not being able to see the wood for the trees. In any risk analysis it is important that conservatism does not strangle a viable project; that the variables are internally consistent with each other, that reality checks are carried out and that appropriate expertise is used. Sensitivity analysis forms a part of the overall project risk assessment; however, it can only test those variables which have already been identified in the financial model. The most useful tool in performing a sensitivity analysis is Monte Carlo simulation. When properly used, it provides a more real world scenario than the simple adjustment of key variables by ¦ 10 per cent one at a time. Monte Carlo can provide valuable information about the robustness of a project. Project risk and sensitivity assessment is prone to the analysis paralysis syndrome. The focus should be on quality rather than quantity.

Jan 1, 1997

By J Chegwidden

Rare earths are a critical minor constituent of many advanced materials that are essential inputs to the manufacture of items such as mobile telephones, computers, televisions and autocatalysts. Although rare earths have a relatively high unit value, the impact of this cost has little, if any, impact on the selling price of the final item. Furthermore, as they are generally present in minute concentrations they are not recycled. It is for these reasons that rare earths are considered strategic materials. China dominates the market as it supplies over 85 per cent of world demand. It has recently taken steps to increase prices through the restriction of exports and support for minimum prices by an association of the major producers. This paper provides an overview of future opportunities for Australia in the context of the current dynamics of world supply and demand.

Jan 1, 2001

The non-metallic minerals, excluding the construc- tions and fuel materials have for long been the "poor relations" of the Mining Industry of New South Wales. The State is self-sufficient in only a few of the industrial minerals and is almost completely lacking in any of the essential fertilizers. The deficiencies must be met by imports from overseas and interstate and in fact New South Wales imports some quantity of every one of the non-metallics. For the year 1967 the value of non-metallic mineral production amounted to only $9,390,000 or less than 3.5% of the States total of $275,900,000 for all classes of mining and quarrying. In roughly the same period, the 1967-68 financial year, New South Wales imported non- metallic materials, valued at well in excess of $22,000,000 from overseas and over $2,000,000 from interstate sources.

Jan 1, 1969

Nordberg has conducted extensive research, during 1982-85, on the effects of cone crusher variables such as speed, throw and cavity design on the productivity of the crushers. Simultaneously, Nordberg's engineers have developed advanced design and testing techniques that ensure efficient and reliable crusher designs. Combination of this knowledge has resulted in a design of the MPI000 (1000 hp) crusher which fits on the existing 7ft Symons foundation and yet is capable of producing twice the ton- nage of the 7ft. In this paper the development of the MP1000 crusher and its performance compared to the 7ft heavy duty and super heavy duty crushers will be discussed. Also, substantial cost savings resulting from the application of such a high performance machine will be presented.

Jan 1, 1988

The Geological Survey of the U.S. Department of the Interior is primarily a domestic agency whose responsibility is furnishing impartial data and analyses to the public, private, and academic sectors of the Nation. The Survey concentrates on earth-science issues, such as mapping the land surface, determining the quality and quantity of water resources, estimating the nation's endowment of fuel and nonfuel minerals, and predicting and mitigating geologic hazards, such as those inherent in the tectonically active Pacific Rim. One of the challenges to managing this program is striking a sustainable balance between concentrating on the problems society wants solved today and investing in the research that seeds our vitality for the future. The Geological Survey's role in the Pacific results from the Nation's geography and the Nation's long standing interest in and commitment to the region. The longest segment of the U.S. coastline borders the Pacific Ocean, one of our states is a Mid-Pacific island chain, our lands are 80 degrees--nearly one-fourth--of the Pacific perimeter, and our Exclusive Economic Zone (EEZ) underlies significant parts of the eastern, northern, and central Pacific waters. Thus, the program of marine and terrestrial science operating in these areas make substantial contributions to the world's growing understanding of the Pacific realm.

Jan 1, 1990

The development of the lower Hunter Valley, centred around Newcastle and its suburbs is closely linked to the mining of coal and the settlements which grew to house the colliery officials, the miners and their families. The Port of Newcastle expanded and developed as a port exporting coal to many ports of the world ranging from Hawaii and Brazil to Japan and Korea. The coal which passed through the Port of Newcastle, depend- ing on the historical period in question may have been mined in Newcastle itself, or one of the nearby colliery townships such as Lambton, Wallsend, Charlestown or Hamilton, or from one of the estuarine collieries located at Carrington or Stockton or from the West Wallsend area or from East Greta, Pelaw Main or Cess- nock located on the South Maitland (Greta) coal field or from the open cut and underground mines of the Singleton Coal District.

Jan 1, 1988

By J de Vries

Arthur Page, a past President of AT&T said:All businesses in a democratic society begin with public permission, and exist by public approval. Product stewardship in its most basic form is simply risk management applied to the products we produce. Conceptually it may be considered as a more expansive approach to many existing safety, heath and environmental programs. Key differences include the extension of responsibility beyond the direct control of management, and consideration of the implications your products and processes have on the broader community, as opposed to the confines of an individual mine site or operation. This paper reviews the processes used by Orica Ltd to manage its product stewardship program. OricaÆs product stewardship program is expansive and supports activities and business that range from manufacture and delivery of commercial explosives and sodium cyanide to mines throughout the world, supply and operation of municipal water facilities, and manufacture and distribution of consumer products such as household paints and adhesives. We highlight the development of the program through experience both good and bad, and by use of case studies to illustrate how an active product stewardship program is an effective business risk mitigation strategy.

Jan 1, 2006

In the Ora Banda area of the Eastern Gold- fields, the ultramafic rocks tend to be more deeply lateritized than most of the surrounding rock types, and lateritic nickel concentrations have been formed. Extensive drilling_has shown that, of the two intermixed suites be- neath the laterite - an extrusive peridotite- pyroxenite suite and an intrusive, highly magnetic dunite - the latter weathers to a more nickel enriched laterite. The top horizon I of the laterite consists of ferricrete. Horizon II consists mainly of bands of secondary silica in a clay matrix, formed in the reworking zone around the water table and stranded as the weathering profile migrated downwards. Horizon III ('ºaprolite") is composed of serpentinite, magnesite, iron oxides and silica, and grades dowil to the fresh bock composed variously of olivine, ser- pentine, talc, amphibole-chlorite and iron oxides. The main locus of nickel deposition is the zone containing the bottom of horizon II and the top of horizon III. The water table is also at this general level. .

Jan 1, 1973

The cement industry requires large quan- tities of limestone, its main raw material. It is the major consumer of this mineral. Limestone is widely distributed throughout Australia but location in relation to major markets, and transport considerations render most deposits of no economic value. Of those which are sufficiently close to the major me- tropolitan markets many are rejected as being unsuitable on grounds of quality, inadequate size for major development, or other reasons such as environmental considerations. Detailed geological investigations are necessary, not only to prove raw material sources prior to establishment of a cement works but also to permit planned extraction programmes and satisfactory grade control during subsequent development. Conventional field techniques have generally proved adequate for raw material exploration. Data assessment and reserves estimation also are by conventional methods although the specific requirements of the industry relating to raw material and cement quality, the type of manufacturing process and fuel used are relevant. A number of case studies from different geological environ- ments are examined and comparisons made bet- ween the predictions of the exploration stage and subsequent experience in quarrying prac- Tice.

Jan 1, 1979

Asian countries are now facing very crucial aspects of urban living under the recession of the economy. The current situation is such that those hard aspects may make the living standards worse and worse in the next century, unless proper measures are taken on the infrastructure for urban lives. More than half of the population in Asian countries are now living in cities. Nowadays, the socio-economic development of the Asian countries has been closely linked to the development of world economy because of the border-less economy system. The population inflow to big cities is inevitable as the Asian countries step into an industrialised economy. Such a tendency will be further accelerated when Asia becomes a centre of financial business in the 21st century. The government of any country has realised the situation very well. The United Nations has established a specific agency to solve the problems caused by the rapid urbanisation. This global agency for urbanisation is named United Nations Center for Human Settlement and it is so called Habitat. There are three Habitat offices in the world, Nairobi in Kenya, Santiago in Chile and Fukuoka in Japan. The activities of Habitat offices cover a wide field of issues such as housing, urban development, infrastructure and environment, etc. Habitat Fukuoka Office is serving Asia and Pacific in co-operation with the government offices concerned.

Jan 1, 1999

By R Nakia, R Livingstone

Historically the Goldfields of Victoria produced large volumes of gold. Interest in these historical Goldfields has grown over recent years with a view to restarting production of gold. A notable example of this is the Bendigo Goldfield. There is also interest in the Ballarat Goldfield and Ballarat Goldfields Ballarat East Project is a particular example of this. The aim of this paper is to describe the ventilation aspects of the potential Ballarat East project. The mine is proposed as a decline access. The paper gives an overview of the project and in particular the ventilation planning associated with a number of possible equipment scenarios. The paper also analyses the main ventilation pollutants that are likely within the proposed mine as it develops to increasing depth. An attempt is also made to determine the depth at which mine climate will become the dominant pollutant rather than diesel exhaust pollutants.

Jan 1, 2003

Carbothermal Reduction and Nitridation of Ilmenite Concentrates and Chlorination of the Reduced Samples

Sep 13, 2010

This paper describes the characteristics of blasting which set it apart from other methods of breaking rock. The mechanism of rock breakage and the influence of rock proper- ties are then discussed. The strain and fragmentation produced by a cylindrical charge does not change once the charge is longer than 16 blasthole diameters. The influence of bench geometry, charge length and drill diameter are then examined. It is shown that spherical charges have advantages over long slender cylindrical charges. By selection of the appropriate drill diameter, explosive and charge configuration the optimum blasting practice for a given rock to give suitable fragmentation and muckpile profile for sub- sequent handling can be found. The fragmentat- ion depends not only on rock and explosive properties but also on the pattern which dictates how effectively the cracking is utilised. The size distribution of the fragments is given by the Rosin - Rammler equation. Undesirable cracking of the rock in the final wall can be controlled by the careful design of blasts as they approach the final wall. Finally, it is concluded that because of the distance to which blasting can fracture and then displace rock it is suited for the breakage of large volumes of rock.

Jan 1, 1978

SASOL Synthetic Fuels has recently completed the design of sampling systems for raw and blended coal feeding the gasifiers at Secunda, South Africa. The new systems will replace manual, stopped belt sampling and have been designed to achieve specific accuracy targets on a daily basis. The sampling system is unusual in the coal industry in that the fines content (-5.5 mm nominal) of the coal is very critical and is to be determined with high accuracy.The sampling system was designed to meet carefully considered target accuracies using methods of modern sampling theory. The heterogeneity of the coal streams involved with respect to the critical analytes was determined by appropriate sampling and sample analysis. The statistical characterisation of the time variation of analytes in the process streams was based on variograms derived from on-line ash gauges. From this point, the design was completed using fundamental statistical sampling theory and some simulation studies. The paper discusses the development of the sampling system design in detail as well as the plans to use the data stream to provide timely alarms when the coal quality deviates from the target specification.

Jan 1, 2002

MR. E. J. HORWOOD wrote: In view of the difficulty of obtaining accurate results when using plumb lines in shafts, owing to the effect of currents of air, the writer, over M years ago, devised a method of transferring oearings from the surface to, the underground workings independently of plumb lines.An attachment was procured for the theodolite consisting of a 45° prism enabling a view of a fine line stretched across the shaft at the surface to be observed from the bottom of the shaft. The instrument was set up in such a position that.a view of the portion of the surface line could be obtained as close as possible to the shaft timbers.By candle light signals an assistant at the surface moved his line so that the portion close to the side or end of the shaft coincided with the cross wires of the theodolite. The theodolite was then swung to enable the crosswires to traverse the surface line. It was a simple matter to transfer the bearing of the surface line to points in the drive extending from the shaft. Similarly the relation of the bearing of the surface line to the shaft, with which a connection was intended, was easily obtained.The success of this method was demonstrated at Broken Hill in making connections many hundreds of feet from the shafts from which these were driven.

Jan 1, 1940

By Sterns UJ, Weller KR

Grinding to sizes less than 80 per cent passing 20 ¦m in both primary and regrind circuits is becoming increasingly important in processing metalliferous ores, as many of the remaining orebodies are very fine-grained and refractory. The process of very fine grinding, however, is expensive, and neither the performance nor the design criteria are well understood. This paper presents some findings from a collaborative research program, one of the objectives of which has been to better understand and improve the performance of very fine grinding circuits. Data from surveys of an industrial tower mill grinding circuit are reviewed and analysed using the population balance models of the CS]RO and 7KMRC. The performance of both models with regard to changes in feed size distribution, ball load and feedrate is assessed using these data. From comparisons between pilot and full scale tower mill operation a prototype scaling methodology is also presented which shows promise in allowing the models to be used to predict the effect of changes in mill Design.

Jan 1, 1993

The geotechnical and environmental aspects of heap leaching are very closely tied during design, operations and closure. Potential environmental impacts from heap leaching are mostly due to land disturbance and water quality issues, including both groundwater and surface water. Water quality issues are mostly related to containment design, which is primarily a function of proper sizing of the facilities and site specific liner design. Geotechnical analyses is the dominant discipline in providing cost efficient, operationally effective and environmentally sound heap leach facility designs. Much has been published on geotechnical aspects of heap leach design, for example Van Zyl, Hutchison and Kiel (1988) and Van Zyl (1987). This paper will emphasize a few specific aspects related to the geotechnical and environmental consideration for heap leach projects. These aspects are: ò site investigation; ò containment design; ò slope stability; ò heap flow dynamics; and ò closure design. Design of a heap leach project must consider not only the operating life but also closure and post-closure considerations. As a matter of standard practice, designing for closure is an extremely important concept. Not only is it important for environmental aspects, but experience also shows that projects designed for closure will be overall more economical for the total life cycle of the project. Closure considerations are also important during project feasibility evaluations to ensure that total life cycle costs are evaluated.

Jan 1, 1994

The efficiency with which it is expected that a particular coal may be burnt in a power station boiler significantly affects the value of the coal. Consequently many laboratory tests have been developed to provide data on the combustibility of coal. Computer modelling of coal combustion has also provided insight into limits on coal burn- out. Such modelling suggests that burnout of bituminous coal in a power station boiler will be strongly influenced by physical limits on the diffusion of oxygen to the individual coal particles. Coal chemical reactivity appears to be relatively less important. As a consequence of the diffusional limits, significant improvement in burnout is achieved either by producing less large p.f. particles or by providing sufficient furnace residence time to burn the large particles. Field data from a variety of power stations supports these cn.clusions. Burnout was also found to correlate well with volatile content for a number of coals from widely different sources. This is expected as the high vola- tile coals produce less residual char to be burned by the relatively slow heterogeneous Combustion.

Jan 1, 1987

FINANCE FOR EXPLORATION Two factors have basic importance in relation to the availability of finance: the apparent success of continuing exploration activity and tax concessions. It is not proposed to discuss the effect of existing tax incentives, as these have already been outlined and are generally accepted as being reasonably attractive; certainly not a deterrent to possible investors. However, it is obvious that the greater the tax incentives, the greater the amount of money that will be attracted, and the wider the number of people who can be brought into the pool. If, as is suggested, the chance of discovery is related to expenditure and effort, then the more money attracted, the better the prospects of significant finds. It is probably correct to assume that the largest expenditure in mining will come from, or be induced by, people expert in the field, people who are fully aware of the risks and benefits and perhaps making conservative decisions because of this awareness. Insofar as the general public is concerned, while in the first burst of enthusiasm it will frequently follow any promoter, in the long run it too will become more sophisticated and will strongly support only those promoters and companies of good repute and proven record.

Jan 1, 1971