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By K Buda, W Staunton, M Hill, V Tjandrawan

One of the challenges facing the gold industry in the 21st century is the continuing need to identify new reserves of economically treatable ores. Discoveries of large, metallurgically simple orebodies are becoming increasingly rarer, forcing companies to investigate options for the processing of ores which may present recovery, economic and/or environmental issues, requiring innovative approaches to their treatment. Ores which contain naturally occurring carbonaceous material (æpreg-robbing oresÆ) are an example of one such ore type. NewmontÆs Jundee operation contains zones of carbonaceous ore within the oxidised orebody. A program consisting of detailed laboratory work and extensive plant trials has been undertaken to assess the options of the processing of this material. Laboratory tests demonstrated the advantage of carbon-in-leach (CIL) over direct cyanide leaching and carbon-in-pulp (CIP) for treatment of these ores. The laboratory program identified several factors which would enhance overall gold recoveries where preg-robbing ore was being processed, including: keeping preg-robbing ore separate from non-graphitic ore; maximising gravity recovery; and ensuring the plant operates in æpureÆ CIL mode, ie no leaching prior to first adsorption tank. Several plant trials were undertaken to assess the economic sustainability of treating moderate preg-robbing ores through a modified gravity/leach/adsorption circuit. Results indicated that where good operational control of the circuit was maintained to ensure high gravity recovery, minimal leaching prior to carbon contact, and maintenance of good, active carbon inventory, then acceptable and sustainable overall gold recoveries could be obtained. Using these relatively simple plant modifications potentially allows a plant to treat ores with preg-robbing index (PRI) values up to one. When PRI values rise to 1.3 - 1.6, leach recoveries can drop from >85 per cent to

Jan 1, 2007

A key premise to this paper is that most people involved in the design and implementation of drilling and blasting operations could benefit from a greater understanding of the geological materials, deposits and landforms they are dealing with. The second key ingredient for successful blasting is the concept of blasting objective. Mine operators and blasting contractors must be clear on what drives their costs (blasting leverage) and should formulate blasting objectives and operational targets which help in this regard. Many operators ignore geology descriptors and features apart from the name of the rock and start crudely quantifying the rock mass properties in terms of uniaxial compressive strength, or even worse still as hard or soft. This occurs too early in the design process and not much attention is paid to the geological materials, geological structures and the characteristics of the deposit they intend to excavate. In effect the rock type name and the strength descriptor become the site geology. Furthermore many blasting operators do not formalise their blasting objective, do not set operational targets and do not measure results to the degree required for continuous improvement. In this paper a number of civil, surface mine and underground mine blasting applications are tabulated in terms of typical blasting objectives and common geological materials. A good description of geological materials can convey a lot of useful information for blasting operators if they are able to accommodate this knowledge. In addition a clear statement of the blasting objective and associated operational targets will maximise the likelihood of achieving blast-driven downstream productivity improvements. The æStarting at Both EndsÆ combination is deemed extremely useful for any continuous improvement blasting program.

Jan 1, 1999

This paper presents a review of heat illness in mining, including reference to several recent investigations by the author. Heat illness is a collective term, covering the conditions of heat stroke, heat exhaustion, heat cramps and miliaria rubra. Heat stroke is life-threatening and is by far the most serious condition. It is rare in mining, if appropriate control measures are instituted. Heat exhaustion is primarily due to hypohydration, following prolonged sweating in hot conditions. Symptoms include fatigue, headaches, dizziness, anorexia, nausea, vomiting, shortness of breath, or brief syncope. Confusion, ataxia, prolonged unconsciousness or convulsions are strongly suggestive of heat stroke. Heat cramps are painful involuntary contractions of skeletal muscle associated with work in hot conditions. The limbs are usually involved and the spasms typically last a few minutes, during which the affected part of the body is incapacitated. Heat cramps tend to occur in heat exhaustion, when hypohydration becomes marked. Miliaria rubra is a skin rash caused by extravasation of sweat into the skin, as a result of obstruction of the sweat glands. It occurs after prolonged and profuse sweating in hot environments. It can take three to four weeks of sedentary duties, in an air-conditioned surface environment, for the condition to resolve. Heat illness would be unlikely in underground mining, if the thermal environment was sufficiently well controlled by ventilation and refrigeration. This is however, often not practicable. Where engineering controls alone cannot provide sufficient control of risk, the residual risk can be assessed using an appropriate heat stress index. While procedural controls may further reduce the residual risk, it is important to remember that these are less reliable than engineering controls and cases of heat illness may still occur. Procedural controls include the application of heat stress limits, education, hydration, self-pacing, early symptom reporting, medical advice, acclimatisation procedures, air conditioned accommodation, support to achieve a healthy body mass index, and an effective emergency response capacity.

Jan 1, 2005

By R Herbert, M E. Malmstr÷, S U. Salmon

The study focuses on sulfide oxidation processes in unweathered pyrite-rich mine tailings from a soil-covered impoundment in northern Sweden. To simulate the oxygen-limited conditions in water saturated tailings two long-term column experiments were performed. Results are presented for the first 11 months of the experiments at room temperature. The tailings used in the experiments were of two different grain sizes (one coarse grained, in the range 0.02 - 0.6 mm with a grain surface area of 1.86 m2 g-1, and one fine-grained, in the range 0.0015 - 0.06 mm with a grain surface area of 10.00 m2 g-1) and with slightly different mineralogical composition. The S:Fe molar ratio in the leachates (1.0 - 1.5) indicates either that pyrrhotite is the main iron sulfide undergoing oxidation in our experiments, or, alternatively that the S:Fe molar ratio in the leachate is determined by pyrite weathering in conjunction with other processes releasing iron or immobilising sulfate. However, speciation modelling of the leachates indicates that ferrihydrite was close to saturation, suggesting that a ferric oxyhydroxide may have dissolved/ precipitated during the experimental period, thereby affecting the S:Fe molar ratio. Pyrite oxidation rates obtained from the two column experiments during æsteady-stateÆ were 2.25 + 10-13 and 8.45 + 10-14 mol m-2 s-1 in the coarse and fine tailings, respectively. Pyrrhotite oxidation rates, as an alternative, were 2.31 + 10-12 and 1.24 + 10-11 mol m-2 s-1 in the coarse and fine tailings, respectively. Natural microbial activity was confirmed in both the tailings and the leachates; therefore, the obtained oxidation rates are not strictly abiotic. It is thus concluded, based on the experimental results, that tailing heterogeneity will result in zones with different oxidation rates, related to their physical and chemical properties.

Jan 1, 2003

The GDR has extensive lignite deposits at its disposal, which formed the basis for the development of an independent energy source after 1945 and which will retain their significance well beyond the year 2000 (see fig. 1). In 1946 lignite output was about 110 x 106 t. In 1985 312x 106 t was produced and in 1988 the planned output will be ca. 315 x 106 t. Thus, the domestic produc- tion of lignite covers ca. 75% of the GDR's primary energy requirements. More than 80% of the electrical energy is gener- ated by the use of lignite and about 12% by nuclear energy. In addition to this, about 18 x 106 t/a mineral oil and about 6 x 109, m3/a natural gas are imported, predominantly from the Soviet Union. The lignite deposits of the GDR are of Tertiary origin and are recovered exclusively by opencast mining. There are two large regions (fig. 2): - in the region east of the river Elbe (Cottbus/Senftenberg- "Niederlausitz") and - in the region west of the river Elbe (Halle/Leip- zig/Magdeburg). These deposits differ in geological age and conditions of depo- sition, consequently there are differences in their chemical and physical composition and, thus, in their uses. The younger Mio- cene coals of the main region in the East of the river Elbe belong to the epirogenetic type and have a low content of ash and sul- phur. Among other things, they are suitable for the production of brown coal high-temperature coke (Lauchhammer and Schwarze Pumpe). The older Oligocene coals of the Halle/Leip- zig region are bitumenous in certain areas. Therefore, they form the basis for production in low-temperature carbonizing and chemical plants. In the Halle-Magdeburg region, where the lig- nite is in contact with the underlying Zechstein subdivision, so- called "salt coals" are found.

Jan 1, 1989

The last decade of national water reform implementation has improved the availability and efficiency of water source allocation in Western Australia. However, it is critical to recognise that the concurrent mining boom witnessed the approach of full water allocation limits, and increasing trends in mineral processing, water infrastructure costs, and wastewater management costs. Water supplies are commonly viewed as absolutely critical to project feasibility in mining, industrial and energy generation projects, even if considered 'non-core business'.   An increasing density of mining projects and industrial estates in Western Australia (WA) creates an opportunity for water infrastructure cost sharing and synergies. The WA government and its agencies have given preliminary consideration to the establishment of independent water utilities in the goldfields (Kalgoorlie), the Pilbara, and Collie regions, and in the Kwinana Industrial Area. The impending Oakajee industrial area and Mid West regional development, and Anketell port in the East Pilbara, could also be considered for common non-municipal water supplies.   The critical issue of apparent commercial risk due to the large scale of water demands and the low customer numbers in the minerals sector relative to other water markets is expected to mandate government partnership in any non-municipal water utility ownership. The commercial feasibility risk is observed as a risk to water supply security for potential mining and industrial customers. Absence of proper water infrastructure planning and governance has the potential to create infrastructure access issues as observed for Pilbara rail developments under the Trade Practices Act 1974.   Other aspects of water cycle management which could be addressed by a non-municipal utility include resumption of mine dewatering water (required changes to WA legislation that are progressing) and consolidated wastewater management for maximising synergy or reuse opportunities and minimising cumulative environmental impacts.   Address of water infrastructure planning for non-municipal water demands must cover commercial and environmental sustainability outcomes to successfully progress minerals sector growth in the State.

Jun 1, 2010

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

About 60 persons are admitted to the graduate course every year after passing the entrance examinations. The entire course of studies is free of charge and the universities provide accommodation for the students who need it. The five years of studies are divided into 10 semesters. One semester lasts 15 weeks. Automatics can be studied at three separate faculties. At the University of Mining and Metallurgy, it is offered by the Faculty of Electrical Engineering, Automatics and Electronics as well as the Faculty of Mining and Metallurgical Machines (metrology can also be studied there); at the Silesian Technical University in Gliwice, the Faculty of Mining offers the course. The educational plans and programmes comprise 3 groups of subjects: common for a given course of studies (foreign languages, political science and the basic technical knowledge) common for the speciality and subjects of diploma courses. The whole time of studies covers about 4400 hours excluding 3 periods of professional training and the physical training. The classes, laboratory classes, seminars and design classes are obligatory and the attendance is strictly checked. Students may extend their knowledge by participating and working in the Science Clubs. The students' work is checked not only during the classes but also by the examinations held at'the end of respective semesters. Those who fail the exams can repeat them only if very important reasons are presented. At the very end of the studies there is a diploma examination together with a discussion on the diploma thesis, written by the student. The successful result entitles the student to recieve the title of "magister inzynier",M.Sc. of his speciality. The graduates, after working for 2 years, can attend another course of studies lasting 2 semesters and called "Postgraduate Course", or start "Doctoral Studies" finished by the defence of a doctor's thesis. In'these cases the expenses are usually covered by the graduates' employers.

Jan 1, 1985

By V Narayanaswamy

SustainabilityÆs imperative of economic development in tandem with social advancement and environmental protection is widely accepted, but much debate remains about the practical implications for the minerals processing technologies and practices for the future. Experience in other industry sectors however suggests that sustainability can be a value-adding framework for innovation in processing technologies, business models and management systems. This position paper explores how sustainability can drive innovation in minerals processing, by reviewing pertinent ideas and experiences gained in non-minerals sectors. Sustainable innovations can generally be broadly ranked from incremental to transformative, with each category having its own typical improvement potential, timescale and technological and operational challenges. This leads to a æmud mapÆ for sustainable innovation in minerals processing with three distinct tracks: eco-efficient operations; sustainable plant design and sustainable processing. Competing models for the sustainable innovation process through either forecasting or back-casting, have in common the strong reliance on vision, perspective and competency, which in turn highlights the importance of sustainability frameworks. Such sustainability frameworks provide normative goals and option elicitation prompts to assist with the analysis of current processes and scoping of more sustainable alternatives. A comparative analysis of five prominent environmental sustainability frameworks revealed three cross cutting sustainability themes that challenge current resource processing technologies and practices. These are: fate of materials (zero dissipation of materials); compatibility of materials and processes; and materials intensity of industrial products and processes. Although the sustainability concepts presented in this paper have not been extensively road tested in the minerals processing industry, there is ample evidence that recent initiatives in the Australian resource sector illustrate the applicability of the proposed framework. It is therefore argued that more in-depth assessment of sustainable innovation concepts would be a valuable contribution to the sustainable resource processing theory and practice.

Jan 1, 2004

By C Li

Removal of gangue minerals from ilmenite concentrates can beaccomplished by relatively low temperature roasting in controlled gasatmospheres to selectively enhance the magnetic separationcharacteristics of the ilmenite. At roasting temperatures below 800¦C the magnetising reactions are often not consistent with phase equilibria considerations. Metastable phases can nucleate and control the roasting products. In weathered ilmenites the phase assemblages and microstructures in the altered ilmenite grains can influence the roasting reactions. In this paper we give an overview of the phase chemistry of chemically weathered ilmenites and of metastable phases formed by low temperature roasting. We also report the results of roast experiments conducted in a neutral gas atmosphere. Major increases in magnetic properties after short roasting times at low temperatures were obtained for a range of ilmenite concentrates. For example heating a secondary ilmenite concentrate from Western Australia for 15 minutes in nitrogen at 600¦C gave an increase in the three kilogauss magnetic fraction from three to 92 wt per cent. The solid state phase changes accompanying the inert atmosphereroasts were characterised by combining elemental analyses withquantitative phase analyses of the ilmenite concentrates and their roast products. It was found that the phase reaction that is principally responsible for the increase in the magnetic properties of weathered ilmenites involves a transformation of disordered ferrous-containing pseudorutile to an ordered ilmenite-hematite solid solution containing typically ten to 35 mole per cent of the hematite component. Examples are given of the application of the inert atmosphere roast to effect separations of ilmenite from gangue minerals.

Jan 1, 2001

By S P, F Villanueva, R Palomo, D Meadows

During 2002, design and development of the worldÆs largest flotation cell was completed. The cell is the mineral industryÆs first 257 m3 flotation cell, and represents a major development in the design of larger flotation cells, with a 50 per cent increase in cell volume over the widely installed 160 m3 WEMCO« SmartCellTM flotation machine. It is anticipated, in the next few years, world-class copper sulfide concentrators will incorporate 257 m3 flotation cells in their rougher-scavenger flotation circuits. The prototype 257 m3 cell, No 250 SmartCellTM flotation machine is installed in Minera Los PelambresÆ existing rougher flotation circuit. The machine is located in front of the first cell in Row 1 and is followed by nine No 130 SmartCellTM flotation cells. The unit has been in operation since April 2004, and has proven itself in this duty. A key to the successful development of the equipment has been the emphasis placed on fundamental hydrodynamic scale-up criteria. Hydrodynamic factors include superficial gas velocity, water (pulp) circulation through the draft tube, and pulp mixing (distribution) characteristics. This paper will review the scale-up criteria of the No 250 flotation cell, and a case study will be presented on the in-plant testing of the equipment. The case study will document the metallurgical and hydrodynamic performance of the machine. It will also illustrate the economic benefits derived by incorporating larger flotation cells in a modern copper sulfide concentrator.

Jan 1, 2005

This paper provides a brief fundamental insight regarding the fabric media concept for liquor filtration. The subject matter will be of interest to metallurgists and engineers with professional responsibility for world class design of solid liquid separation processes and efficient lowest cost operation of existing mineral process plant. Avocet Mining commissioned the worldÆs first mineral liquor clarification process incorporating a fabric media liquor filter at their Lanut gold mine in Sulawesi, in 2004 with design consulting provided by the Australian company SLS Technology Pty Ltd. Development of the technology continues with applied research focused on selecting textile parameters to apply filtration to a wider range of particle and contaminant types, higher solids concentrations, and different process liquors. Liquor filtration with the Fabric Media technology offers an array of attractive benefits. For Avocet Mining, filtration of pregnant liquor directly from the heap leach pad has enabled removal of the sediment pond and sand filters from the traditional process flow sheet, thus providing significant cost and installation time savings. Avocet Mining has recently expressed confidence in the technology indicating selection preference of the technology for the expansion at Lanut and for a new project. The application design window for the Fabric Media concept is extremely flexible with the technology now successfully applied to many different liquor chemistries and application objectives around the world. Potential cost savings for solid liquid separation process plant, such as counter current decantation circuits, clarifier vessels and thickener tanks can be calculated from laboratory measurements or pilot plant demonstrations.

Jan 1, 2008

The magnesite deposits near Young, N.S.W., occur in decomposed serpentine rock below a soil. and alluvial cover. They show considerable variation in both quality and depth which greatly hampers mining operations. Seismic refraction techniques afford methods of conducting detailed and reconnaissance surveys which yield a depth and velocity analysis of the serpentine/magnesite refractor. The measured seismic velocities may be used as an index of the presence and quality of the deposits. The Seismic Timer which was used in the test surveys is a simplified seismograph which makes use of seismic reciprocity by replacing the conventional seismic shotpoints with geophone stations and the conventional geophone stations with impact points of a sledge hammer. Thi,s enables the use of detailed seismic refraction techniques which yield the depth and velocity analysis of the refractor.INTRODUCTIONThe magnesite deposits near Young, N.S.W., were produced by a process of leaching and enrichment of magnesium in serpentine rock. The magnesite occurs in nodular form emplaced in decomposed rock at shallow depths below soil and alluvium. The depth ranges from close to the surface down to some tens of feet. The deposits are patchy and show considerable variation in both quality and depth, giving riseto considerable difficulties in mining operations.Due to the thorough leaching of the surface material, geochemical tests carried out so far have not proved satisfactory for locating the pockets of magnesite enrichment.It was decided to test the application of detailed shallow seismic refraction methods to the investigation of both the depth and quality of the deposits. The tests were carried out...

Jan 1, 1962

By Li G, Dean-Jones G. L, She T

Highwall mining is a specialised and largely automated mining method developed in the United States for the extraction of coal left under a shallow overburden cover after cessation of economical open cut mining operations. As the name indicates, coal is extracted from the seam exposed along a highwall by a remotely controlled continuous miner operating in a single unsupported opening and brought to the surface by a string of conveyor segments. The single entries are separated by coal .pillars and driven normal to the highwall, over areas where the thickness of cover and volume of recoverable coal is insufficient to allow or justify conventional underground mining. An additional highwall mining method is augering. The success of high wall mining operations depends significantly on geological features, notably the stability of the working roof, determined by the type and mechanical properties of the immediate roof strata. Stability of the ribs, absence of floor heave, faults and dykes are further important prerequisites for profitable highwall mining. The geometric relationship between the spatial attitudes of existing joint systems, the direction (azimuth) of the single entry opening and its vertical profile determine the unimpeded depth of penetration into the coal and thus its economic success. The mechanical implications of the lithological transition zone from a coal seam to either primary or original roof strata, compared to an interface between the coal seam and overlying strata, characterised by a sharp erosional boundary between coal and a secondary immediate roof stratum, are very significant. The compatibility between the response to mining by the geological system (floor-seam-roof) and the capability of the mining equipment to prevent the development of instability are essential requirements from a mechanical viewpoint. The minimisation of vibrations, very good horizon control, an ability to vary the profile of the opening, and the maintenance of consistently high advance and retreat rates, are also important aspects of profitable highwall mining.

Jan 1, 1995

By T Cutts

Since 1989 Kalgoorlie Consolidated Gold Mines has managed the Kalgoorlie gold operations of joint venture partners Normandy Mining Ltd and Homestake Gold of Australia Ltd. Current production from the Fimiston Open Pit is approximately 650 000 ounces per annum. The mine incorporates a multitude of narrow shear hosted, subvertical lodes, predominantly within Golden Mile Dolerite. Traditionally KCGM has used blasthole based grade control in the Fimiston pits. A single sample is taken from vertical production blastholes, drilled on ten metre benches. This process was improved with the addition of infill drilling along blasthole rows to provide additional samples across strike. However the limitations of adequately defining subvertical mineralised structures with vertical blastholes remain. In 1997 the first of two trial areas were drilled with close spaced, inclined Reverse Circulation (RC) drilling. These tests indicated that RC based grade control had the potential to provide significant advantages. These include:improved delineation of mineralised structures, particularly across strike; reliable short-term mine schedules based on the advance data available from drilling over three benches; and the angled RC drilling is capable of providing samples of near stope and stope fill material which often remains unsampled by blasthole drills due to the safety constraints around unstable underground openings. Based on the success of this initial work RC based grade control was gradually implemented across production areas commencing September 1998. Some of the many challenges faced include:development of effective procedures and systems for the planning, logging, interpretation and modelling of the RC data; obtaining adequate drill coverage due to mine scheduling constraints and restricted access around underground openings; requirement for integrated systems to handle either blast hole or RC data; and development of effective methods to evaluate the performance of RC grade control. RC based grade control is delivering significantly improved lode definition, grade estimation and subsequent ore classification.

Jan 1, 2000

By R J. Everett

The mining industry is beginning to adopt quality systems based on the requirements of International Standards for quality assurance, such as the ISO 9000 series. Indications from similar industries are that considerable benefits are to be had from their adoption. This paper describes the use of the International Standard ISO 9001 for quality assurance within BUKA Minerals Limited. This provided guidance for the development of a clear statement providing agreement on the processes to be followed and the outputs required when dealing with outside service providers. Discussion focuses on the interaction with BUKAÆs consultants and contractors during the specification stage, resulting from the application of quality assurance techniques. Risk analysis was used to identify and manage the risks associated with the companyÆs contract for geotechnical and mine design services and the tender for a mine development program of work during the feasibility stage of the project. Setting acceptance controls for the deliverables from such contracts is traditionally fraught with difficulty. BUKA used Failure Mode and Effect Analysis for exposing underlying risks that were not effectively being countered. The briefs were reviewed and additional controls were developed to manage the risk. These controls have provided clearer instructions to the consultants and contractors, indicated audit points for the company and defined the deliverables. There exists within the company, and among its outside service providers, a clearer understanding of what is to be achieved and how it will be measured. The process has imparted considerable confidence to both parties on how the work will proceed and what outputs are to be provided. Some discussion is provided on how quality principles are being applied throughout industry and commerce, generally, and how they may apply to the mining industry. The paper argues that, far from being an appendix to the tendering process, Risk Management should be a mandatory step integrated into the definitions of the work.

Jan 1, 1998

The past decade has seen a great increase in activity in deep seismic reflection profiling of the continental crust. Some 20 countries have conducted field experiments and the total length of deep seismic profiles surveyed to date is approximately 25,000 km. This total is very large compared to the quantity of such data that existed previously, but very small compared to the total length of seis- mic profiles of the shallow crust carried out for petroleum exploration, which some- times has exceeded 600,000 km on land in one year alone and 1,600,000 km/yr on land and sea. Furthermore, 25,000 km of seismic pro- filing corresponds to exploration of only a tiny fraction of the total volume of the entire continental crust. Thus at this stage of development of the subject, one must be wary of generalizations that are based on these limited data and then ex- tended in scope to include the crust everywhere. The state of the subject is such that virtually every new seismic line reveals totally unexpected seismic fea- tures, a sign that the subject is in its major discovery phase and a warning to the generalizers. Nevertheless, in addition to much new information on deep crustal structure in specific locations, some broad consequences of application of this powerful geophysical technique to a region of the earth not pre- viously explored in this manner are be- coming clear. One is that, as seismic data on the deep continental crust become more abundant and more revealing of complexi- ties, the deep crust can be far better re- lated to rocks at the surface. Conse- quently, the geological style of reason- ing is now being extended from its normal domain of the near-surface to include the deepest crust in a comprehensive story of the evolution of the continents. This change is a subtle but important one and is evident, for example, in some cross sec- tions of the North American Transect Pro- gram, which show surface geology extended in a consistent, though speculative, manner to the top of the mantle. In other words,

Jan 1, 1987

THE MORWELL BROWN COAL DEPOSITSTHIS deposits of brown coal in the neighbourhood of Morwell, are of tertiary age, and are represented on several horizons, but, owing to lack of evidence, the exact age cannot be fixed definitely. It is chiefly by reference to the basalt flows of the Older Volcanic series that the brown coal beds have been classified as of Pre-Volcanic and of Post-Volcanic age. The Pre-Volcanic brown coals are less widely distributed, and the seams generally are thin, though near Thorpdale a thickness of 40 tt. has been recorded, and from 10 ft. to 12 ft. in the vicinity of Narracan. Both of these localities lie to the south-west of Yallourn, and it has not been proven as yet whether these older coals and accompanying basaltic flows pass under the Morwell beds.The brown coal deposits have accumulated in an area where extensive faulting in early tertiary times has taken place with oscillations of elevation and depression of the land surface. In the vicinity of Yallourn, Paheozoic strata (probably Silurian) are exposed on either bank of the Latrobe River about a mile above the powerhouse weir, where the river flows through steep banks rising a couple of hundred feet on either side. The Silurian strata are highly inclined, and consist mostly of slates and Illudstones. Resting unconformably on the upturned edges of the Silurian is a conglomerate bed of Mesozoic age, above which occur beds clipping to the south-east of felspathic sandstones, with alternating mudstones at times carbonaceous, and containing thin seams of black coal.The brown coal seams and associated lignitic Clays, sands, gravels, etc, rest on the Mesozoic strata (as proved in the vicinity of the power-house and by boring north of the Latrobe River, near the old open cut), but do not appear on the surface of the Mesozoic, where these beds attain an altitude of more than 50 ft. above the present level of the Latrobe River.Half a mile upstream from the power-house a layer of basalt of the Older Volcanic series, almost resting upon the Silurian strata, is...

Jan 1, 1924

By K Osman, P Bennett

The mining of an underground orebody requires development both in waste and ore before stoping commences. Regardless of what metal is being extracted, the waste development is minimised to reduce the cost per unit of metal mined. At the Western Metals Zinc Kapok mine site, reducing the cost per tonne of lead and zinc mined is paramount. Decline waste development costs can be minimised by methods such as increased gradient or reduced drive size. Ore development will also involve some mining of waste. The degree to which waste mining can be minimised will depend on the thickness and dip of the orebody. The drive geometry will also determine the percentage of waste within the face. It is by mining methods such as resue mining that selective mining may be used to maximise the amount of metal mined and reduce waste dilution. Resue mining can be used around a set of selection criteria established by the mine site. These selection criteria will determine how resue mining can be applied to the mine site. Selection criteria include firing times, number of headings available, acceptance criteria for percentage lost metal, dilution and most importantly operator acceptance. The single pass or two pass resue mining method should be chosen depending on the site acceptance criteria and selection criteria. The Western Metals Zinc Kapok mine site has established a set of parameters which accept the two pass resue mining method for the mining of the ore drives. The blasting results from a single pass resue method were reviewed during more recent trials in a single heading. Through a comparison of results, the parameters allowed the decision to determine the applicability of resue mining and its current form to Kapok. This paper outlines the parameters set by the Kapok mine site, reviews these in relation to the two forms of resue mining and examines the criteria which make this mining method applicable for Western Metals Zinc.

Jan 1, 2002

THE object of this note is to set forth some particulars of the effect of light on cinnabar occurring in a deposit of this mineral at Puhipubi, in the North Auckland peninsula of New Zealand. This deposit is contained within a gently-inclined sheet of siliceous sinter forminga hillock called Mount Mitchell, and is particularly notable in that it is an instance of the simultaneous deposition of cinnabar and silica on a large scale. The mercury-bearing material varies in character from semi-porous sinter to dense translucent cbalcedony, of which the former is stained to various shades of pink, the latter to brilliant reds and vermilion. On exposure to daylight-and particularly to sunlight - these colours change to corresponding shades of translucent bluish-grey. As a direct result of this change the Mount Mitchell deposit remained unknown until some ten years ago, for, while prospectors early discovered cinnabar in the adjacent city and in a neighbouring stream bed, none of them recognized this mineral in the bluish chalcedony strewing portions of the surface of the Mount. The writer has carried out a series of experiments designed to indicate the cause and nature of this change, and to form a basis for the elaboration of more delicate experiments which would yield positive information. Circumstances, however, have so far combined to prevent the continuation of the research, and, as there seems little prospect of the writer being able to do more work on the subject, it seems well to publish the data so far obtained. Prior to describing this colour change, the writer would point out the desirability of restricting the meaning of the term cinnabar to the naturally occurring red sulphide of mercury; this would eliminate the ambiguities which arise from its indiscriminate application, in chemical literature, to both natural and artificial sulphides. Further the term cinnabarite having long since fallen into disuse, there appears to be no good reason for retaining the companionterm "metacinnabarite" when reduction to "metacinnabar" would preserve the meaning in a less clumsy word.

Jan 1, 1923