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By R G. Richards

The Australian glass sand industry produces some 2.8 million tonnes per annum of silica sand, of which about 2.0 million tonnes are exported and the rest is for the domestic market. Approximate production rates for each Australian state are listed. The variety of processing methods used in the currently exploited deposits reflects the size, location, and characteristics of the various deposits and the requirement of the end market/s. The industry uses to a large extent equipment developed for the separation of mineral sands, particularly as it applies to low grade heavy mineral deposits, where low cost, high capacity and metallurgically efficient equipment has proved eminently suitable for the production of the low value glass sands. The requirements of the domestic market, as well as those of the present and potential export markets are discussed covering quality requirements, distribution channels and other factors critical to success.

Jan 1, 1990

In preparing this paper, the writer hopes to achieve two main objects. Firstly, an indication of the desirable features of coke from the viewpoint of a blast furnace operator should be of assistance and value to those connected with coal and coke research, coal mining, the manufacture of coke and the production of iron. Secondly, it is hoped that the conclusions and opinions expressed herein, which are known to be of a controversial nature, will promote some discussion and thought. In this way, other workers may see fit to contribute and enlarge our general knowledge of Australian coke and its behaviour in blast furnaces.Those properties of coke that are considered to be of importance to blast furnace operation will be examined. Although broadly speaking, the composition and characteristics of coke are inherent in the coals used, any special features of coal preparation and carbonization that affect the resultant coke will be discussed. An attempt will also be made to indicate the effect on blast furnace operation of significant irregularities in these properties.THE FUNCTION OF COKE IN A BLAST FURNACECoke has four important functions in a blast furnace:1. To reduce the oxides of iron and other elements to metal and to provide the carbon absorbed by the iron.2. To supply the necessary heat for the process.3. To provide an open supporting structure in which the descending ore and limestone lie exposed to the action of the ascending gas.4. To provide voidage in the bottom of the furnace, so that iron and slag can accumulate in the hearth.

Jan 1, 1957

IT has often been stated in the past that the materials known as inert fillers were merely adulterants nsed in the manufacture of paint, and that their purpose was to cheapen paints made from more expensive pigments, such as zinc oxide or white lead. In recent years, however, practical tests in various parts of the world have proved that many of the inert fillers, when used with wisdom, possess very definite and advantageous properties.Another oft-repeated statement which had a far-reaching effect in the past, and which is not without influence to-day, is that the very best paint must always be made from a pure pigment, without admixture with either a fellow pigment or an inert filler. Both or either of these statements may be true in a few isolated instances, but for the vast majority of ordinary painting conditions there is an abundance of experimental evidence to prove that neither is true.With the desire to further investigate these points and po 'determine the best combination of pigments and fillers for use as an outside white paint on plant buildings, a number of panels were prepared in the laboratory of this company.

Jan 1, 1924

In New York City, on the walls of the library of the United Engineering Societies are these words:"Engineering-the art of organising and directing men and of controlling the forces and materials of nature for the benefit of the human race," but who, reading the schedules of even our best engineering schools, would infer that engineering is an art or that it should always havejn mind the benefit of the human race? While it must be remembered that our engineering schools exemplify the British cult of the amateur, that cult which lets men who have never attended a lecture on "Education" or perhaps nevereven read a book on it, become enginering teachers by profession (and so educators by inference), the root of the matter is to be found in the fact that our educational aims, and consequently our educational practice, seem suited much better to the position engineering held in the community in 1900 than to the position it holds to-day. This civilization of ours has developed, !;loth for good and for ill, into one based largely on engineering achievement; technical progress is so continuous and so rapid that thevalue of descriptive knowledge of current practice is ever lessening; enough must be imparted to make the young graduate immediately employable, and this amount is sufficient for illustrating the principles on which practice is based and on which its advance depends, but the young graduate's technical progress depends much less on his having acquired additional knowledge than on his ability to acquire knowledge, so, paradoxically, the more useful knowledge there is availabJe the less of it the student should be taught.Less conspicuous but fully as important is the enlargement of the field of work of engineering graduates, especially its extension to the initiating of policies and to the broader problems of administration. At present the road to such positions lies normally through a considerable period of professional work, but it is by no means unlikely that the field will soon include much that requires little professional expel'ience. At all events it is safe to say that the changed. and changing position of engineering in the communitydemands the attention of the engineering schools and that profitable discussion of engineering education demands some understanding of the real nature of education and of the part which engineering plays in the life of the community.THE NATURE OF EDUCATIONUnfortunately "to educate" supplies an example of how words degenerate in meaning; most people regard it as the equivalent of "to instruct"; a small number feel they have gone to. the root of the matter when they say...

Jan 1, 1941

By J L. Mauk

 Broken Hills is an adularia-sericite epithermal Au-Ag deposit, hosted in flow-banded rhyolites and overlying rhyolitic pyroclastic rocks in the eastern Hauraki Goldfield. The 7.1 Ma deposit was the largest producer of gold in the eastern Hauraki Goldfield, and was one of very few economic deposits hosted in Pliocene rhyolites. This paper presents the results of a recent study in the upper levels of the deposit. Maps and cross-sections constrain structural and lithological relationships, and the lateral and vertical extent of a breccia pipe û the major feature of the upper levels.   Previous studies in the upper levels of Broken Hills have shown that gold and silver values are concentrated around and within a large breccia pipe, mined by a series of æcaveÆ stopes and in veins. Contour diagrams of Au-Ag data from channel samples indicate that the breccia pipe was a major fluid channel-way for mineralising solutions.   The breccia pipe deposits are part of the dynamic geothermal system that formed the Broken Hills ore bodies; they developed as a result of hydrothermal brecciation in areas of structural weakness within a rhyolite pyroclastic unit that overlies a massive rhyolite lava-flow unit. The main breccia pipe begins near the rhyolite/pyroclastic contact, having the shape of an inverted, inclined cone, and consists of silicified breccia, stringers of quartz, and irregular patches of clay-altered country rock. Smaller zones or pockets of hydrothermal eruption breccia are silicified and contain low grade gold in the matrix and in the adjacent silicified wall rocks.   Quartz has been classified according to its physical characteristics as seen in situ and hand specimens indicate that vein definition decreases upwards, perhaps as a result of changing lithological conditions and/or increasing proximity to the paleosurface. Hydrothermal quartz is widespread as veins and as a replacement mineral, or lining fractures and cavities and overgrowing rock fragments. Breccias contain vein quartz, but some quartz veins cross-cut breccias, indicating that vein and breccia formation was relatively synchronous and overlapped in time.   Disseminated gold-silver mineralisation is associated with vein quartz and silicic alteration of the wall rock within the breccia pipe. The auriferous zones are highly irregular and erratic, and sampling results show a wide range of gold-silver ratios, suggesting that highly volatile physiochemical conditions prevailed during mineralisation.

Jan 1, 2005

By A Croll

A panel cave using LHDs for ore extraction came into production at Premier in 1990 at a depth of 630 metres below surface on the western side of the mine in the BA5 mining block. A post-undercut mining sequence was used with all development on both the undercut and production levels completed prior to the undercut being advanced over the pre-developed drawbells. Support and rock mass damage on the production level was extensive as the undercut moved overhead. Undercutting and coarse fragmentation created problems. The mining sequence was changed to an advance undercut with the minimum of development and support undertaken on the production level prior to the undercut moving overhead. Only once the abutment stresses had stabilised were drawbells developed and final support installed. The height of the undercut drill design was decreased from 18 to 13 metres. The changes resulted in markedly less rock mass and support damage on the production level. Lessons learned in the BA5 mining block on the 630 level were incorporated into planning and scheduling the BB1E mining block which came into production on the 732 metre level on the eastern side of the mine in 1996. An advance undercut mining sequence was planned, undercut height was minimised and undercutting parameters were optimised in terms of the BA5 experience. Numerous problems still occurred. As the undercut area increased in size severe spalling from the cave back resulted in vertical propagation of the cave to a height of 30 metres instead of the planned 13 metres. The resultant coarse fragmentation created secondary blasting problems and an excess of undercut ore that had to be loaded and trammed, slowed the rate of undercut advance. The planned mining sequence was compromised and considerable support and rock mass damage resulted on the production level below. Once these problems had been overcome the undercut advanced at the planned rate and continuous caving initiated at the predicted hydraulic radius. At a later stage the unexpected ingress of water hampered undercut drilling and slowed the rate of undercut advance in a section of the cave. Leads and lags between adjacent tunnels and the overall face shape could not be developed as planned. The rate of natural horizontal cave propagation exceeded the rate of undercut advance and three undercut drilling tunnels were extensively damaged. More tunnel development on the production level prior to undercutting than was planned resulted. The slow advance of the undercut and high abutment stresses caused extensive damage to installed support and the rock mass on the production level, 15 metres below. Experience in the BB1E mining block on the 732 metre level has taught that an advance undercut mining sequence reduces damage on the production level markedly. Extremely tight control on the rate of undercut advance, leads and lags between adjacent tunnels and overall undercut face shape as well as extraction ratio, tunnel development and support sequence on the production level below is required. Premier Mine plans to implement a block cave at a depth in excess of 1000 metres within the next decade. All the experience gained on current mining levels together with data collection and numerical modeling is being used to plan the proposed mining operation. The geotechnical challenge of mining at this depth in weak rock has been identified as the greatest risk to the project. Challenges centre around adopting the correct mining sequence, limiting the extent of rock mass damage associated with undercutting and effective support. The hydraulic radius needed to initiate caving, fragmentation, drawpoint spacing, secondary blasting and the possibility of seismicity are geotechnical concerns that are being addressed. Results to-date suggest that a pre-undercut mining sequence with all development and support on the production level carried out only after the undercut abutment stresses have passed overhead will have to be implemented.

Jan 1, 2000

By C Verdel, M Lee, A Oorloff, K Welsh

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Thomson Orogen is a large but poorly understood element of Queensland geology. Extensive cover conceals the Thomson Orogen at depth, thus limiting studies to a small number of surface exposures. Previous studies of the northern Thomson Orogen have been restricted to the largest of these exposures in the Anakie Inlier and Charters Towers Province. Less extensive exposures, including Mt McLaren in east-central Queensland, are largely overlooked and poorly documented. Fieldwork suggests that Mt McLaren is a west-tilted fault block of Thomson Orogen metasediments that are at least 2200 m thick. The substantial thickness of these sediments (which we have named the Mt McLaren Formation) and the consistent shallow marine facies throughout the block suggest deposition in an actively subsiding basin. Initial dating of detrital zircons places deposition of the Mt McLaren Formation in the Late Cambrian to Early Ordovician, allowing correlations with formations of similar composition and age in the nearby Anakie Inlier and Charters Towers Province. Both of these areas have a long history of mining and exploration for gold and base metals, suggesting that correlation of basement sequences across these areas could be beneficial for exploration models of the Thomson Orogen as well as for tectonic models of eastern Australia.CITATION:Lee, M, Verdel, C, Welsh, K and Oorloff, A, 2015. Stratigraphy of the Thomson Orogen – new insights from Mount McLaren, north-east Australia , in Proceedings PACRIM 2015 Congress, pp 551–556 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By J Hall, A Gallardo, M Strizek

Mineralogy and coproponents Sino Iron, International Minerals and Austeel are in the process of developing four world class magnetite iron ore mines with multiple open pits along a 25 km strike length of Brockman Iron Formation to the south of Cape Preston on the West Pilbara coast. The close proximity of the proposed pits raises some challenging project approvals and environmental management issues relating to the impacts of dewatering at individual projects and the cumulative impacts of progressive development on local and regional groundwater resources, which includes a large fresh water aquifer system in the Fortescue River alluvium.This paper presents an outline of the hydro-environmental impact assessment process adopted and the key result that the cumulative impacts of dewatering at all four projects on the local brackish groundwater system in the basement rocks is only marginally more than the impact of any one project on its own, and that the impact on the Fortescue River alluvium aquifer is negligible. The paper also presents an outline of the proposed integrated water management approach that will involve coordinated monitoring, ongoing impact assessment and management, and reporting programs for all projects.

Jan 1, 2009

The Archaeozoic Willyama Complex at Broken Hill has suffered several periods of deformation and metamorphism. New structural and petrological information together with that available from the literature gives a picture of the metamorphic evolution of the Barrier Ranges. Several epochs of metamorphism are recognized, and potassium-argon dating of minerals has been applied with limited success to the resolution of these epochs.INTRODUCTIONAdvancements in the mineral industry at Broken Hill over the past eighty years have been accompanied by a continual striving towards increased understanding of both the geological history of the Barrier Ranges and the environment of the Broken Hill ore deposits. However, although many detailed studies of selected localities and particular-aspects of Broken Hill geology have been carried out recently, the regional geology of the Barrier Ranges as a whole has received little attention from a petrological viewpoint since the pioneer investigations of Mawson (1912) and Browne (1922). There still remains a great need for regional surveys combining field studies of the habits, structures and outcrop relationships of the various rock types with laboratory investigations of their chemistry, mineralogy and microscopic ,fabrics. Recording observations arising from three brief visits to the Broken Hill area during 1959 and 1963 may stimulate further surveys.During one of these visits, the generosity of the Zinc Corporation Limited in providing field transport and geological guidance enabled the writer to collect material and study field relationships and appearance of the various rock types at numerous localities covering most of the Willyama outcrop. A complete study has not been conducted...

Jan 1, 1963

This paper examines the issues involved in the technical audit and valuation of exploration prospects. Certain methodologies are more appropriate to use depending upon whether the mineral property valuation is of an exploration area, a project under development, or an operating mine. Valuation approaches that are reviewed include the Multiple of Exploration Expenditure, Joint Venture Terms, Rules of Thumb, and particularly the Kilburn Rating Method. The DCF/NPV Financial Simulation Method, even modified by the use of Expected Values, is not considered appropriate for valuing exploration prospects. The choice of the most appropriate methodology and its successful application depends primarily upon the amount of reliable input data available and, more importantly, the experience and judgement of the valuer. It must be remembered that all valuations are time and circumstance specific and will be generally subject to revision as more data becomes available.

Jan 1, 1993

THE most important part of the routine survey work on a mine is the keeping up-to-date of plans and sections showing progress of stoping and development work, and the direction of the latter for the purpose of making necessary connections. Except in specialcircumstances, e.g., major horizoittal development, the exactitude required in this work is not extreme, and a method of survey in keeping with the demands of the work itself is all tbat is required.For example, no one would consider measuring the walls of a stope to a fraction of an inch; such extreme accuracy would be wasted.The stope walls being irregular, a mean is usually taken, and for ordinary purposes a survey with a limiting error of six inches is quite satisfactory for the purpose of plotting either stoping or development.It is the author's aim in this paper to describe the method in use at the North Broken Hill Oompany's British mine. This method, while being sufficiently accurate for the purpose in view, possesses the very great advantages of speed and simplicity of operation,with a minimum of necessary equipment. This latter is a very important item where several surveys on different levels have to be carried out on the one day.Let it be understood, however, that the use of this method does not dispense with the theodolite, but simply serves as a convenient adjunct to obtain details and to extend the accurate theodolite survey up rises and down winzes, and through ladderways orwinzes into stopes, where the use of a theodolite, if not actually impossible, is often exceedingly inconvenient. This is particularly so on the British mine, where a large proportion of the ore is won from narrow and complex-dipping lodes, and where vertical ore...

Jan 1, 1928

Effects of High Pressure Grinding Rolls on Platinum-Bearing Ores and the Flotation Response as Compared to the Conventional Ball Mill Three major PGM ore types from the Bushveld Complex of South Africa: Merensky, UG2 and Platreef were comminuted with the use of the high pressure grinding rolls (HPGR). The influence of the feed characteristics and the various operational and design features of the HPGR on energy consumption, throughput, mineral liberation and PGM flotation recovery were investigated. The test work variables included two feed top sizes of 12 mm and 6 mm, specific grinding forces ranging between 3 - 7.5N/ mm2 and zero gaps of 1.5 mm and 3 mm. The results show that the influence of the HPGR operational and design features on energy consumption, throughput, mineral liberation and PGM recovery are ore dependent. The size reduction-specific energy relationships show that the most energy efficient utilisation of the HPGR for Platreef ore was at the lower specific grinding force of 3N/mm2 and the zero gap at 3 mm. For Merensky and UG2 ore on the other hand, the most energy efficient operation was at the higher specific grinding force of 7.5N/mm2 and the zero gap of 1.5 mm. At a specific energy input of 3 kWh/t, reduction ratios (F50/P50) of 6.5, 3.8 and 10 were obtained for Merensky, UG2 and Platreef, respectively for feed top sizes of 12mm. Further application of the HPGR as a pregrinding stage to a ball mill showed a 25 - 30 per cent increase in throughput for Merensky and UG2 ore. Batch flotation tests performed on selected samples appear to indicate that ore comminuted with the ball mill had superior grades compared with that ground with the HPGR. However, Merensky and UG2 ore comminuted at different HPGR operating conditions showed distinctions in PGM recovery. Platreef on the other hand did not appear to show any differences. Therefore, this study highlights the significance of ore type and operating variables in HPGR applications with regards to energy efficiency, throughput and PGM recovery.

Sep 13, 2010

By A J. Scogings, W J. Shaw

The successful development of industrial minerals projects requires an integrated, holistic understanding of the metallurgical and product performance test work in the context of the geological setting of the deposit and applied to mining, processing and marketing of saleable products. The product specifications provide the essential starting point for geometallurgical studies. A sound understanding of the desired product is needed to design and interpret a program of test work. Examples are provided from recent studies on bentonite and graphite deposits.For bentonite projects, the naïve testing of only the cation exchange capacity (CEC) as a measure of purity can lead to unexpected outcomes when the deposit is mined. The CEC attribute may remain the same, while other important properties such as pH and swelling index change markedly with depth, due to weathering and oxidation, leading to disappointing production outcomes.For graphite projects it is not enough to report only total graphitic carbon content (TGC). Knowledge is required of the in situ flake size and textures in addition to purity and flake size distribution of extracted graphite, which may all vary from one domain to another across the deposit. Such geometallurgical attributes of the ore will impact on the ‘basket price’ used to estimate the value of marketable parcels of expected product.Disclosure of such information must be considered part of fully informing the market. As with all new project developments, consideration of the JORC (2012) and VALMIN (2015) Codes requires disclosure of all material information. This includes the geometallurgical characterisation, ie those aspects of the mineralogy that impact on resource evaluation, ore reserve definition and project valuation.CITATION:Shaw, W J and Scogings, A J, 2017. The importance of geometallurgical test work for industrial minerals projects, in Proceedings Tenth International Mining Geology Conference 2017, pp 83–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By S Taylor, B Lumsden, G Long

Statistical metallurgical plant trials are becoming more widespread, as a valuable tool for increasing plant profitability. Generally, a single parameter like metal recovery varies under the trial condition while all other variables such as average metal feed grade or average metal concentrate grade are equal for the two test conditions during the period of the test. Metal recovery is usually the measured variable because concentrate grade is fixed by smelter terms, and plants operate to maximise recovery at the required concentrate grade. However, in all flotation plants there is a relationship between concentrate grade and metal recovery, and under the same conditions increasing one results in a decrease in the other. At MMGÆs Rosebery Mine the zinc concentrate produced is generally above smelter specifications, so zinc concentrate grade can vary during a test. During trialling of magnetic conditioning in the Rosebery zinc circuit, the difference in both zinc recovery and zinc concentrate grade were analysed. The analysis of changes in zinc grade and recovery during the trial raised some interesting questions about the relationship between concentrate grade and recovery. A paired statistical method was developed and tested to combine in each pair the change in concentrate grade and recovery in a single result that could be analysed by a paired t test. This method was found to be very sensitive to combined, varying changes in concentrate grade and/or metal recovery. It was also evaluated on plant test results from another flotation plant to verify its applicability in other plants. CITATION:Long, G, Taylor, S and Lumsden, B, 2012. Statistical plant trials - Efficiently combining concentrate grade and metal recovery results, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 355-362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Sedimentary pyrites from Tasmania have Se contents that are high for it province showing no overall Se enrichment. Sulphides from Devonian granitic rocks, and related cassiterite-sulphide deposits, Sn-Wand PbZn-Ag fissure veins have similar and relatively low Se contents, and pyrites from Devonian gold-quartz veins have very low Se contents. The high concentrations of Se at Mount Lyell are consistent with enrichment in pyritic Cu deposits in volcanic rocks elsewhere, and the dispersion of Se is consistent with a surface volcanic origin for several of the orebodies. In contrast, sulphides from Cambrian volcanic rocks and associated granitic rocks, and from the Rosebery and Hercules pyritic PbZn deposits, also believed to be of volcanic origin, are impoverished in Se.In the Mount Bischoff cassiterite-sulphide deposits there is no relationship between Se content of sulphides and temperature of formation as indicated by fluid inclusion studies, and sulphides from Devonian ores with different temperatures of formation have similar Se contents.The Se content of Tasmanian sulphides appears to be an unsatisfactory discriminant of their genesis and temperature of formation but in volcanic terrains may be a useful pathfinder for Cu concentrations.

Jan 1, 1969

OWING to two large falls of ground which resulted in serious accidents occurring towards the end of 1908, it became evident that the "open chamber" system then in use was unsuitable for the conditions existing in the Mount lVIorgan mine. It will be admitted that in all mining operation, the first consideration is the economy of the system adopted, combined with its safety and ability to give the desired output. A sectional system with square sets has been introduced into the mine, in which due attention has been paid to these factors. In this paper a brief description of this system will be given. An outline of those previously used will be ineluded, as it is necessary to understand the eonditions which existed in the mine at the initiation of the sectional system. Outside the actual mining methods employed, various points that might prove of interest will be touched on.The square set system of mining has been in use throughout the stopes in the gold ore in the upper levels of the mine since underground operations were started in Mount Morgan.

Jan 1, 1910

By D Thorburn

This paper reviews the history of environmental assessment in New Zealand with reference to mineral developments. Emphasis is given to larger more controversial projects particularly metal mines. The changing role and application of the Environmental Protection and Enhancement Procedures is examined in the context of changes in the government's environmental administration and the response of the Ministry of Energy's resource allocation group. Conclusions are drawn on the effectiveness of the present environmental assessment activities and on the allocation of administration of priorities in the Ministry. The Ministry of Energy has effectively ceased to exist.

Jan 1, 1990

By D A-F Batchelor

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.South-East Asia represents the world’s most productive tin province, mainly from placers. Kalimantan has been a major diamond producer, while in the 1980s a placer gold rush occurred in Indonesia and Malaysia. Reviewing extensive geological and mining data highlights phenomenal palaeo-environmental changes in the Sundaland region, interpreted to be responsible for generating ‘giant’ placers. Correlation of the Late Cainozoic stratigraphy has been facilitated from mine exposures and drill holes distributed throughout Peninsular Malaysia, the Indonesian Tin islands and Kalimantan, including contiguous marine areas with extensive shallow seismic profiling data. Knowing the association of rich placers with palaeo-environmental episodes and stratigraphical units has been helpful to facilitate their discovery. All three placer commodities responded similarly to region-wide landscape evolution following Mio-Pliocene high sea levels. Commencing with major regression, important stages comprised: a long period of landscape stability with deep weathering during the maximum Sundaland extent gradually rising sea levels/precipitation initiated slumping of mineralised regolith to form fans, later reworked by braided streams with aggradation (Old Alluvium); during episodic pluvial periods downcutting upgraded placers significant change occurred around Middle Pleistocene time with peneplanation and pedogenesis from Late Pleistocene time ‘modern’ fluviatile deposition (Young Alluvium) filled incised V-shaped valleys.Placer seams show systematic variation in stratigraphic position, in particular cassiterite especially occurs in the Old Alluvium (equivalent Upper Dahor Formation in Kalimantan). Gold is commonly richer in gravelly younger deposits, partly because of secondary precipitation within permeable alluvium. Reworked diamonds are predominantly concentrated especially in younger fluviatile alluvium.CITATION:Batchelor, D A-F, 2015. Conceptual exploration for tin, gold and diamond placer deposits in ‘Sundaland’ (Indonesia and Malaysia) by understanding the late Cainozoic stratigraphic context, in Proceedings PACRIM 2015 Congress, pp 499–506 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The commercial development of the shallow (2200 ft2 400 ft) Windalia sand reservoir at Barrow Island provided the opportunity to conduct an intensive drilling programme using equipment and techniques designed for optimum performance.During the initial exploratory and reservoir delineation phase, 12 specific Windalia test wells were drilled using drilling equipment with an optimum depth range of 6QOO ft - 8000 ft and a 9 5/8 in by 7 in. casing programme was employed. The average time from commencement of move-in to rig release exclusive of coring for five representative wells was 187 hr during this phase.Development drilling commenced December 1966 with one rig, with the second in operation January 1967.As of January 1 1968, 168 development wells had been completed. The two rigs employed are drive-in units equipped with a telescoping .gelf raising doubles mast.Optimum depth range with 4 1/2 in. drill pipe is 2500-4000 ft. Casing programme is 8 5/8 in. by 5 1/2 in. Efficient performance was achieved immediately. The average time from commencement of move-in to rig release for 15 wells drilled early in the development programme was 99 hr.By application of experience and further modification of techniques, performance was improved to an average time of 72 hr per well for 15 wells recently completed.The major drilling problem on Barrow Island is surface hole drilling due to the very hard surface limestone combined with complete loss of circulation at sea level.In this operation, significant improvements have been effected. During the exploratory phase drilling, 12 1/4 in hole to set 9 5/8 in. casing, average penetration rate was 23 ft/hr. At the commencement of the development programme penetration rate, drilling 10 5/8 in. hole to set 8 5/8 in. casing, was 28 ft/hr for the 15 early wells considered, improving to 55 ft/hr for the 15 recent wells considered.This programme is a team effort and much credit must be given to the enthusiastic co-operation of the two drilling contractors.The current field record is 2 days 4 hr with a 4 1/2 hr move including the drilling of mousehole and rathole.

Jan 1, 1968

By Carlos G. C

Geological mapping in various parts of Australia is revealing a number of regional associations of mineralizations with particular persistent stratigraphic horizons. Such associations have been found in the Broken Hill district of New South Wales, in the Nairne district of South Australia, in the Mount Isa district of Queensland, and in the Cloncurry district of Queensland. The question has arisen as to whether such mineralizations are of sedimentary origin, syngenetic with the enclosing formation, or whether they are of epigenetic origin, and reflect the selective hydrothermal mineralization of favourable beds on a regional scale.The purpose of this investigation is to test the use of sulphur-selenium ratios as an objective method of distinguishing between suphide deposits or sedimentary or supergene origin, and sulphide deposits of hydrothermal origin, with particular application to the districts mentioned. At the same time much data has been accumulated as to the selenium content of Australian sulphide ores. The possible use of sulphur-selenium ratios for this purpose was first demonstrated by Goldschmidt and his coworkers (1933; 1935), and later by Carstens (1941). Goldschmidt and Strock (1935) found that pyrite of sedimentary origin had a sulphur : selenium ratio of the order of 200,000 or more, whereas pyrite of hydrothermal origin had a sulphur: selenium ratio of 10,000 to 20,000. Carstensfound that sedimentary pyrite deposits in Norway contained less than 1 g. Se per ton, whereas hydrothermal pyrite deposits contained 20 to 30 g. per ton.

Jan 1, 1954