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By Thomas R

The successful `marriage' between a company seeking to raise funds to develop a project and their financiers calls for a strong mutual understanding of each other's needs. For a company attempting to raise funding, the alternative methods are ever expanding. The optimum method will vary depending on the financial position, risk/reward outlook of the company and the strength of the project for which development capital is being sought. It is likely that small mining companies will need to raise equity funds for advancing projects to the development stage. At that time, they will probably still require a reasonable level of shareholder equity to meet the requirements of banks and other parties to cover potential cost over-runs on the project and feasibility costs. Larger companies, however, are likely to find it much easier and cheaper to raise debt from banks. When evaluating companies and projects for funding, banks will pay particular attention to the quality and experience of management in developing similar projects and it may be necessary for some companies to retain the services of outside consultants. Before a project needs funding, companies should meet with potential financiers to develop relationships to select and ensure a smooth transaction to funding in the future.

Jan 1, 1997

This study of the tin-tungsten ore of the Shepherd and Murphy Mine, in central northern Tasmania, was originally undertaken at the request of the Moina Tungsten-Tin Mining Co., N.L., as part of the research programme of the Mineragraphic Investigations Section of the C.S.I.R.O. It is based on the examination of a suite of specimens supplied by the management, supplemented by a more extensive collection and observations made by the author during a short visit to the mine in October, 1956.The Shepherd and Murphy Mine is at Moina, 36 miles S.W. of Devonport and 22 miles from Sheffield, the nearest railway station. It was worked almost· continuously from 1893 to 1919, when a fire destroyed the mill; to that date it had produced concentrates to the value of £141,000. After a long period of idleness, the mine was re-opened by the present company, but it has been announced recently that unfavourable market conditions have again forced closure.GENERAL GEOLOGYThe mine is on a deeply dissected plateau, about 2,500 ft. above sea level; it lies between the Iris and the Forth Rivers, whose valleys are deep gorges cut to about 400 to 600 ft. above sea level. From Moina westwards to the Iris River, a limestone regarded as part of the Gordon River Group, of Ordovician age, conformably overlies a sandstone containing tubicolar casts which are circular in cross section, half an inch in diameter and up to two feet long, and which resemble marine worm burrows (Elliston, 1953).

Jan 1, 1958

The Hyde-Macraes Shear Zone (HMSZ) is low angle, duplex thrust system that has developed in a graphitic pelite schist within the Otago schist belt, New Zealand . At Round Hill lateral ramps have developed parallel to the movement direction between+ the footwall and hangingwall shears. These structures exhibit normal oblique-slip displacement which has been an important mechanism for creating space in an otherwise compressional system. Gold-bearing quartz veins were emplaced along the boundary shears and lateral ramps during thrusting. Gold within the lateral ramps is coarse (up to 300 microns) however hanging wall cataclasite development in the boundary shears after the gold was deposited has reduced the grainzise of most of the gold to less than one micron. This bimodal gold distribution has metallurgical implications with respect to the maximisation of gold recovery at Macraes.

Jan 1, 1993

New Zealand China Clays produces a unique halloysite clay product at Matauri Bay, Northland.   The company has licences over four deposits that were derived from the weathering of rhyodacite domes. Clay is mined and processed from two of the four deposits and is refined using a complex process based on gravity separation.   The product is almost entirely exported to niche markets in 24 countries. The main market is the fine ceramic industry where the product is used as a component in the manufacture of high quality porcelain and bone china bodies. The use of halloysite in these bodies gives the manufacturer the ability to achieve high whiteness and translucency. The other major market is for use in technical ceramics, where the product is sought after due to its high purity, fine particle size and stability at high temperatures.

Jan 1, 1997

The importance of the Broken Hill mining field may be gauged from the fact that since the discovery of the ore-body in 1883, till the end of 1931, approximately 43,000,000 tons of ore have been raised.The lode covers a length of 31 miles, and in places is upwards of 300 ft. in width. The ore, as at present mined, consists of an intimately blended mixture of lead and zinc sulphides with silver and gangue minerals.Structurally the lode conveys the impression of a huge longitudinal arch (when viewed from the east or west), having its apex or crown near the centre of the field, in the leases of the Broken, Hill Proprietary Co. Ltd., where the lode outcropped at the surface.The minimum depth of the lode in the Proprietary mine was some 500 ft. from the surface, but huge undulations, having an average pitch of 45°, carry the extensions of the arch gradually deeper, to those places where active stoping operations are now in progress in the workings of the North mine at one extremity, and the South and Zinc Corporation mines at the other. The depth of the lode from the surface, as exposed at present, is approximately 1700 ft. at these extremities.The structure and physical character of the ore-body, and its containing walls, are so complex and varied that almost every type of mining problem is met with.

Jan 1, 1932

By E Asakpo, S Chaffer, A Heath

Newmont has had continuous production at their Ahafo operations, Ghana, since 2006. In 2013, Ahafo initiated an efficiency programme to improve mill performance and reduce energy consumption. Following this assessment, a Turbo Pulp Lifter (TPLTM) was installed in the Ahafo SAG mill in April 2015 to replace the existing radial pulp lifters. Plant operational data showed delivery of a power saving of 10 per cent, an improvement in throughput of 3.3 per cent, with no loss of grind size. Pulp lifter life was also doubled from 11 to 22 months.However, during subsequent relines when the grates were removed it was found that one in four of the outer pulp lifters were wearing at a faster rate than the remainder. This was investigated by Discrete Element Method (DEM) modelling, which predicted some overtopping and internal recycle within the pulp lifter. Significantly, the model predicted that the recycled material would pass back down every fourth outer pulp lifter, matching the field observations. Subsequently, the DEM investigation was continued and became an R&D project to improve the TPL design. The results are summarised here, leading to the development of the next generation Spiral TPLTM.CITATION:Heath, A, Chaffer, S and Asakpo, E, 2018. The development of optimised pulp lifter design for the Ahafo SAG mill using discrete element method modelling, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 585–594 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By C M. Stewart, P Bowen

McArthur River Mine, in the Gulf Country of the Northern Territory, exploits one of worldÆs largest deposits of zinc, lead and silver. It was officially opened in September 1995, 40 years after its discovery in 1955. This paper describes the geological, engineering and metallurgical assessments which made up the feasibility study. It then relates how these study components compare with the first two years of operation. The challenges that had to be overcome before the McArthur River Mine became economically viable included the metallurgical problems associated with extremely fine grained ore and the development of an effective mining process.

Jan 1, 1998

By A E. Petts

Record iron ore prices and a renaissance of infrastructure in the Pilbara have Flinders Mines poised to move from explorer/developer to an iron ore producer. The potential of the company’s Pilbara Iron Ore Project was first highlighted by the announcement of Rio Tinto’s Caliwingina North deposit to the north and the Fortescue Metals group’s Serenity deposit in the southeast. The success of Flinders Mines’ exploration has been based on incorporating landscape studies into an existing geological framework, and using this to understand the iron-rich materials that were emplaced during the Tertiary. The development of the Delta and Eagle deposit resource models highlights this process. There are three main mineralisation styles at the project; detrital iron, channel iron and bedded iron deposits. They have textural and mineralogical similarities with comparative deposits in the region. Gaining an insight into the geological processes unique to detrital iron deposits and more distal channel iron deposits has been important to understanding the geometallurgy of the mineralisation. The model sits comfortably with other regional oregenesis models and allows a contextual framework to be developed around the timing of deposition of the Fe-rich detritus and pisolitic nodules that dominate the deposits. The exploration model also allows Flinders to explore more effectively for bedded iron mineralisation developed prior to, and since the development of the Tertiary weathering landscape.

Jul 11, 2011

By S Henderson

The Thames gold-silver deposits are part of the Hauraki goldfield, situated within the Miocene to Pliocene calc-alkaline Coromandel Volcanic Zone (CVZ). The Waitangi vein system is one of the mineralised ore shoots in the Thames district. The Thames gold deposits are characterised by shallow level epithermal vein mineralisation with phyllic to advanced argillic alteration assemblages and abundant sulphide minerals including pyrite, arsenopyrite, chalcopyrite, galena and sphalerite. Gold occurs as electrum in association with sulphide minerals. Microprobe analyses.of sphalerite grains from the Waitangi deposit mostly range from 0.8 to 1.5 mole % FeS, although one sample contains 9.5 mole % FeS. Arsenopyrite from Waitangi yields a range from 33.1 to 34.6 atomic As (%). There is no discernible correlation between the FeS content of sphalerite and gold grade in the Waitangi deposit suggesting that gold deposition is probably not controlled by changes in temperature and activity of sulphur aS2 that control the FeS content of sphalerite. The possible causes for gold deposition are thought to be boiling, mixing and changes in pH. Sulphur isotope analyses of mixed sphalerite-galena and sphalerite-galena-ehalcopyrite samples yield a narrow range of d34SCDT values (-1.0 to 0.9 ë;n=5), whereas late spongy pyrite gives unusually light sulphur isotope values (-16.7 to -27.9 ë; n=4). The sulphur isotopic values of base metal sulphides from Waitangi suggest that the sulphur was derived from a magmatic source. However, the source of light sulphur in the late pyrite grains is not known. Preliminary fluid inclusion+studies indicate homogenisation temperatures between 173¦ and 284¦C and salinities of 0.23.0 NaCI equiv. wt % (uncorrected for C02). Vein quartz at Waitangi yields d18OSMOW values from 6.8 to 12.7 ë (n=23). The calculated oxygen isotopic composition of ore fluids is between -2.1 to 3.8 ë at 250¦C and -0.1-5.8 ë at 300¦C. Oxygen isotope analyses have revealed significant variations in d18O values with elevation and gold grades. Zones of gold enrichment coincide with a zone of variable oxygen isotope values at the top of the vein system, where boiling and/or fluid mixing most likely occurred. Oxygen isotope values varying with gold grades within the Waitangi conduits suggest that d18O values may be useful in targeting bonanza grade gold mineralisation in epithermal vein systems.

Jan 1, 1993

Incorrect sampling and measurement operations and misunderstanding the components of variability can cause huge economic losses to the mining industry. The main objective of this paper is to illustrate by means of four historical facts how Codelco has been evolving in those issues since the late 1980s. The El Abra bias, the awareness of the different kind of sampling errors and the role of Francis Pitard, the awareness of weighting errors, and the understanding of the components of nature and process variability are described. It has been a slow but a consistent process. Much progress has been achieved but still there are many opportunities for improvement to transit from the tonnage culture to the productivity culture.

Jan 1, 2008

By Kavetsy A

In surface mining operations, the ease with which a muckpile may be dug is a dominant factor in mining efficiency. Within broad limits this is largely independent of the fragment size dis- tribution, since the equipment used to move the broken rock is generally larger than in underground mines. In such cases, muck- pile shape and voids ratio within a muckpile heavily influence mine productivity. In a particular operation, the muckpile shape after blasting should be tailored to the digging equipment being used. A front- end loader is best suited to a low, flat-lying, loose muckpile, because of its fairly good mobility and small break-out force with its bucket. In contrast, a rope shovel lacks mobility, generates a much larger break-out force with its bucket, and fills its bucket in a vertical filling motion. Therefore, it is ideally suited to well fragmented, steep faces. In situations where a dragline is used, the requirement for a suitable muckpile depends on the operat- ing scheme of the dragline. For a conventional highwall key method the preferred work- ing level of the dragline is the same as the highwall, so that the dragline may sit over its key. In this situation, the ideal muck- pile shape involves relatively little displacement of the fragmented rock, with a minimal "power trough" at the back of the blast. In throw blasting, on the other hand, it is desirable to cast as much of the spoil as possible across the pit. It is then necessary to optimize the blast design by maximizing the throw percentage under any necessary constraints (e.g. damage, vibration, flyrock, explosive cost).

Jan 1, 1988

The polymerisation of silica is found to interfere with thickening of leach pulps at Risdon. Hydroxyl ion and fluoride ion are catalysts for this reaction. Stability may be obtained by the presence of aluminium or ferric iron.INTRODUCTIONAt Risdon it has been a matter for satisfaction that, although the concentration, of silica in leach solutions is appreciable, it has ,given relatively little cause for anxiety.However the margin of safety is small and some intermittent difficulty in thickening leach residues during the last few years has prompted a further investigation, certain parts of which are described here since they may be of general interest.Leaching and ClassificationThe method of leaching which is practised at Risdon has been described in, two previous articles, by W. C. Snow (1936) and S. W. Ross (1949) to whiCh the reader is referred for detail. Continuous leaching is practised, the circuit solution flowing through five air agitated pachucas in series, to tlie first of which calcine is added. The circuit solution, which also enters the first pachuca, consists of spent electrolyte from, the electrolytic cells and contains 90 -gm. of free sulphuric acid per litre. About 80 per cent of the solublezinc oxide is extracted from the calcine in the first pachuca, at a pH value of 1-1 (7 gm.H2S04/1 at 55 to 60°C. In the later pachucas the leaching rate decreases sharply. The leach pulp which leaves the 'last pachuca contains an average of 17 gm. of free acid per litre, corresponding to a pH of 1.7; but, owing to variations in extraction, the end point fluctuates between 2.5 and 0·3 gm. free acid per litre (pH:> 1·5 to 2.5). The average flow through the plant is 1,250,000 gallons per day, which corresponds to a production of 300...

Jan 1, 1958

In undertaking to write a few notes on practical mining in Bendigo, the great quartz mining centre of Victoria, which just now is celebrating its fiftieth anniversary of gold mining, satisfaction must be expressed which is, no doubt, shared by all mining men and inyestors, that Bendigo has not lagged behind other Australian mining districts in the evolution of mining from its crude state, subsequent to the discovery of gold in 185 to its present more perfect state; and though it may be said that it has not yet reached the high pinnacle of perfection towards which advanced science and change of conditions may yet lead it in the course of future progress, yet, what has already been done in this respect, the adoption of the most approved methods appliances and modern machinery, tending towards greater and still greater efficiency, facility, and economy in our mining industry, must be accepted as a guarantee that in tne future as well as in the past, progress in our means of developing our mining resources will ever remain our watchword, by means of which future difficulties will be overcome as well as they have been removed in the past.The adoption of this principal, combined with a study of rigid economy, has raised gold mining here, as well as in other places, from a state of speculation, and sometimes wild speculation, to the status of a solid, stable industry, the strong supportand backbone of the country in which it flourishes. Two of the principal factors which have been to a great extent instrumental in bringing about this satisfactory state, must be specially mentioned.

Jan 1, 1902

Computational models are very useful for studying many of the physical mechanisms which can cause sample bias. Within such models we can predict the trajectories of all individual particles and thereby make observations which are not possible for physical systems. Physical mechanisms highlighted include congestion at the cutter aperture, particles bouncing over the cutter aperture, air drag on fine particles, waves of material being bulldozed off the belt by the upstream side of the body of square cutters, and particles being thrown by the leading edges of cross-belt cutter blades. Having identified relevant physical mechanisms for an existing cutter, we can estimate the extent to which they are likely to result in unequal representation of portions of a stream of material and thereby estimate the maximum likely sample bias.

Mar 1, 2010

Many problems occur in recruiting staff to remote mining operations, relating to both domestic and works environments. These are stated, together with steps which have been taken to overcome them. Geographical and climatic conditions applying to the Agnew mining operation are described. Company policies have been established to define criteria for selection of staff, and to define methods by which the criteria are applied.

Jan 1, 1980

Disseminated gold mineralization in the Vunda River area 12 km SE of Lautoka in Viti Levu occurs sporadically in shoshonite volcanics within an alteration area of some 6 km2. No definite intrusions have yet been located though possible intrusions occur toward the centre and on the eastern margin of the area. The nature and distribution of alteration suggests the presence of a co-magmatic mineralizing stock just below the surface.The gold occurs within close spaced fractures and occasionally around the c1asts of breccia and agglomerate.Various types of alteration compatible with porphyry mineralization occur, but to date show no zoning or defined correlation with incidence of gold which occurs in various alteration facies.It is suggested that the gold and trace copper mineralization at Vunda arises from the sub-volcanic intrusive phase (monzonite) of the Sambeto shoshonite (5 m.y.) and is part of an E-W zone of porphyry-type mineralizationtrending easterly to the Kingston porphyry copper deposit at Navilawa.There is a close similarity between the Vunda mineralization and some of the porphyry deposits of alkali affinity in British Columbia, Canada.

Jan 1, 1978

Asbestos is a commercial term applied to fibrous varieties of several minerals, the properties of which are not generally appreciated by the majority of geologists. A thorough knowledge of these properties and of the uses of asbestos is of fundamental importance in the assessment of the economic value of an occurrence of asbestos. The varieties of asbestos that are used predominantly by the manufact- urers of asbestos products are chrysotile, crocidolite and amosite but chrysotile constitutes 95% of the world's usage. It is the properties of high tensile strength, 'heat resistance and large surface area that make chrysotile asbestos the most acceptable of the mineral fibres. There are no known exploration aids, other than direct visual inspec- tion of outcrops in ultrabasic environments, that could be used in the exploration of chrysotile asbestos. The surface exploration of an occurrence of chrysotile asbestos is relatively routine, though it lends itself to a unique form of bulk sampling by the use of a twelve inch diameter diamond drill core. The laboratory assessment of the prop- erties of the actual fibre requires specialized techniques and tests to assess not only the amount of fibre present but also its length distri- bution, inherent strength, filterability, dust content and other prop- erties. The way a fibre reacts to milling will determine what milling process- es must be implemented to ensure a product that is acceptable to the asbestos product manufacturing industry.

Jan 1, 1971

By J Vann, C Seymour

Geology is generally treated as a æfront endÆ step in mine development. After infill drilling, the majority of resource estimation, mine-planning, development, mineral processing strategies and operational procedures are planned and implemented with little geological input, particularly in open pit operations. However, significant benefits in overall costs, cash flow, and technical risk reduction can be realised when sound geology is utilised more rigorously throughout the mining process. This under-utilisation of geology in the mining process has arisen due to a combination of factors:A lack of interest in, or knowledge of the full mining process by geologists. Few geologists fully understand where their inputs make critical impacts on downstream users. As a result of this, geologists generally do not focus their inputs towards areas of greatest value added, ie addressing issues critical for other members of the mining team. Most importantly, few geologists effectively communicate their results to the downstream users of their geology models. The results are that the potential benefits of geology, and the appropriate status of geology in the mining industry, are not fully realised. It is fundamental to realise exactly what geologists do. Geologists constrain geological processes and geometry. All geoscientific tools at the geologistsÆ disposal are geared towards one of these goals. An emphasis on geological processes is present throughout the exploration process, whereas in the resource estimation and mine development process an emphasis on geometry is required. The mining process is a web of disciplines that are attempting to optimise development of a resource to provide value to shareholders. Yet few people within these disciplines have a full appreciation of this web, and where sound geology inputs can add value through various feedback loops. Geology inputs do not end at the resource estimation stage, nor are they relegated to grade control implementation. If geologists have an appreciation of the mining process and close liaison with the other disciplines such as geostatistics, geotechnical engineering, hydrogeology, and mining engineering, they can significantly benefit project costs, timelines, and constrain technical risk by addressing their issues at the earliest possible stage. Furthermore, the mining process is not a single pass timeline, but an iterative process where the exploration, resource definition, mine planning and mining loop is continually repeated over the life of a project. Therefore, the potential inputs of geology are critical throughout the mining process. Effective communication of the impacts of geology inputs on downstream users is often lacking on mining projects. The most effective way to communicate geological results is through where it impacts most û project risk. Focussing all geology inputs and communication in terms of potential material risk allows the geologist to be more effective in contributing value to the mining process, and allows the downstream users of geology inputs to better constrain the risks associated with their aspects of the mining project. Through a program of geologists:taking an interest in the entire mining process and identifying critical areas for geology inputs to downstream users (the geologistsÆ clients); focussing geology inputs to address the potentially material issues on mining projects; and communicating their inputs to the æclientsÆ in terms of technical risk, geology will be much better integrated into the mining process. As a result, the potential benefits of geology throughout the mining process will be realised, and the status of geologists within the mining process will be elevated to a more pivotal position.

Jan 1, 2000

By N Rivera, A Music, C Cisternas

In an underground mine operated with panel caving and subjected to high stresses, geotechnical events such as collapses or rock bursts are fairly recurrent. Both situations can involve risks for people, considerable production losses and increasing operational costs.This paper discusses an operational methodology for the recovery of the undercutting front carried out at El Teniente mine, which uses panel cave mining with post-undercutting, after the occurrence of severe damage due to a seismic cluster. The main objective of the recovery of the undercutting front is to prevent the spread of the collapse to the production level, risking the operational continuity. The methodology is the result of repairs that were carried out in the year 2014 at the North Reserves sector from El Teniente mine. Its characteristics are an undercutting front of almost 1000 m long, with the presence of relevant structures and faults, high stresses and high seismic activity.The practical implementation of the proposed methodology was successful since it prevented the spread of the damage, completely recovered the undercutting front and avoided production losses during the execution of the repairs. Also, considering the origin of the damage and the operations associated to the subsequent recovery of the undercutting front, in this paper we discuss the main control variables to be measured. These variables should allow any operator and short-term planner to take action in mines operated with conventional panel caving in a complex geotechnical environment.CITATION:Rivera, N, Music, A and Cisternas, C, 2016. Recovery of the undercutting front in a mine with conventional panel caving – case study at North Reserves sector, El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 713–722 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

INAP was formed in 1998 by a number of major mining companies, with a view to sharing acid rock drainage knowledge and experience, and to coordinate global research on the management of sulfidic mine wastes. INAP is now moving to further strengthen its global role by networking with regional organisations that are active in the area of ARD, including MEND 3/NEDEM 3 in Canada, the ADTI in the USA and ACMER in Australia. The INAP-Regional Organisation partnership will be formally launched at the 6th ICARD.

Jan 1, 2003