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By C J. Noack, P B. Ganza

The concept of large trucks underground has been around for some time. While the road train concept is gaining momentum, there are underground mining applications where these trucks have not been suitable. Unfortunately few of the ægreenfieldsÆ projects that are most suited to the road train concept have come æon lineÆ since the underground road train was first introduced to Australia in 2001 so that the trucks have generally been adapted to existing operations. As at December 2004, there were 17 road trains operating underground in Australia, one being rebuilt and one under construction. This paper addresses the necessity for the mining industry to have an integrated ore transport system that starts at the underground load haul dump unit (LHD) in the stope production area and finishes at the crusher feed at the processing plant. Chute and orepass designs are investigated, as well as feeders to determine the best load and haul system for large-scale trucking. The paper also discusses potential developments in the large truck scene. The paper highlights the cost and productivity gains by introducing large trucks and associated integrated ore transport systems underground. While 400 vertical metres was seen as the limit of vertical hauling in the 1970s, one kilometre is a common discussion point for trucking limits today. In real terms the cost of underground trucking (including ownership costs) has decreased from $1.50 - $2.00/t.km in the mid-1990s to $1.00 - $1.20/t.km at present.

Jan 1, 2005

I have chosen this topic for my address with the intention of preserving a rather extraordinary record of recurrent additions of capital in the financing of one of the world's important silver-lead-zinc mines. The recitation of the trials and tribulations which fore-shadowed the rise of Mount Isa Mines to a position of relative prominence in the realm of non-ferrous mineral production may, I hope, be of assistance to some of the younger members of the Institute who may be called upon during their careers to meet similardevelopmental and financial problems.Mount Isa Mines Limited was incorporated in New South Wales in 1924 with an Authorised Capital of 40,000 shares of £20 each.In November 1925 the Company acquired the leases and water rights of the Mount Isa Proprietary Silver-Lead Limited for 6,250 fully paid £20 shares. Shortly thereafter, but in the same year, the £20 shares were split up into £1 shares, thus bringing the Authorised Capital to £800,000.The leases purchased consolidated and brought under one management the principal ore bodies of the Mount Isa area.Transportation facilities were indispensable to the economic future of the field, so the construction of a railway extending the Government line from Duchess, 54 ,miles to Mo.unt Isa, was assured by the passage of a bill in October 1925 by the Queensland Parliament. Under the provisions of the so-called Mount Isa Railway Act the Company was required to idemnify the Government against national loss on this branch line for a period of 10 years.

Jan 1, 1953

During the course of an investigation into the fundamental chemistry of the cyanide process, it became evident that the usual method of determining protective alkalinity was not completely satisfactory. T.he routine method for the determination of protective alkali by first removing free cyanide by the addition of silver nitrate, followed by titration of alkali with dilute acid using. phenolphthalein as indicator, can be shown to give correct results only when the alkali is a strong base. For other sUbstances, the alkali so determined is not the protective alkali. In view of the complications associated with the presence of zinc in cyanide solutions the discussion will be restricted in the first place to solutions free from zinc. Until the chemistry of simple cyanide solutions is placed on a quantitative basis it will be difficult to elucidate the behaviour of complex mill solutions.By the use of physico-chemical theory, it is possible to treat certain aspects of 'the chemistry of cyanide solutions in a manner which not only illustrates the important variables involved, but which also shows the need for care in interpretIng results obtained by conventional methods.In the following, comparatively simple systems are discussed; the principles established should be of use in interpreting the behaviour of more complex solutions. The methods described are not intended for routine work, but may be regarded as supplementary to the usual analysis carried out for the control of plant solutions, or as alternatives to be used when the latter do not appear to be satisfactory.

Jan 1, 1948

During October 1947 an Authority to Prospect was granted by the Minister of Mines to lVIount Isa Mines Limited over an area of approximately 75 sq. miles to the north of Mount Isa.Application for the Authority to Prospect had been made after Zinc Corporation Limited had been granted prospecting rights over two areas, one of 1,265 acres immediately to the north of the Mount Isa Mines leases and the other of 1,960 acres adjoining the south end of Mount Isa Mines leases.METHODSAs a means of providing a cheap map of sufficient accuracy on which to plot geological features, both Mount Isa Mines Limited and Zinc Corporation Limited agreed upon aerial photographs and the two companies shared the cost of an aerial photographic survey by Adastra Airways of 130 sq. miles which covered the prospecting areas held by both companies.The photographs were on a scale of 800 ft. to I in. with 60% overlap on the north-south runs and 25% overlap east-west. A set of alternate prints enlarged to 400 ft. to 1 \in. were obtained for field work. The 400 ft. to 1 in. scale unglossed photographs (size 18 in. x 18 in.) were taken On to the field and rock outcrops, and uncorrelated structures were plotted directly on to them in red crayon pencil. The geological observations were then transferred in the office to a tracing on which accuracy of azimuth and scale was controlled by use of a photo mosaic and ground surveys.

Jan 1, 1953

By Fountain C. R

In April 1987, Mount Isa Mines Limited (MIM) commissioned an ISASMELT reactor to smelt 15t/h of copper concentrate at the Mount Isa Copper Smelter. This unit was based on the Sirosmelt lance technology and incorporated features proven in the Lead ISASMELT plant which has been operating in the MIM Lead Smelter since 1983. From April 1987 to June 1989, the copper smelting plant treated 167000 tonnes. Concentrate, coal and fluxes are fed continuously to the furnace. Oxygen enriched air is injected through a lance which is submerged in the slag bath. Matte and slag are tapped together through a single taphole into a reverberatory furnace, and from there are treated with normal reverberatory furnace production. Advantages of the process include its ability to eliminate most lead and arsenic in feed, its flexibility with respect to feed composition, sizing and moisture, and the plant's low capital cost. Acceptable refractory life has also been demonstrated. The commissioning of a 70 t/day oxygen plant has rerated the plant from 15t/h to 18t/h while allowing a reduction in fuel usage of one third. A trial using 150 t/day oxygen was carried out in May 1989, and showed that the furnace could treat 48 t/h chalcopyrite concentrate while maintaining a very low fuel requirement. The oxygen trial results have given considerable confidence for plant scale-up. Detailed project evaluation is currently underway for the replacement of the roaster and reverberatory furnaces at Mount Isa with a single 110 t/h ISASMELT reactor.

Jan 1, 1989

Scale build-up in titanium palladium alloy spent electrolyte heat exchangers in the residue treatment plant commissioned at Risdon, Tasmania in 1971 was shown to be a mixture of manganese dioxide and anhydrite (CaSO4). The manganese dioxide was deposited as a result of thermal decomposition of permanganate ions present in the spent electrolyte. It was shown that deposition of manganese dioxide and associated anhydrite scale could be prevented by prior reduction of permanganate ions to the manganous (Mn++) state by the addition of ferrous ions. In the plant this was conveniently accomplished by injecting into the inlet line to the heat exchangers sufficient zinc plant solution containing ferrous sulfate to decolourise the spent electrolyte. This action prevented deposition of such scale for another 21 years, until the heaters were finally decommissioned in March 1992. Measurements indicated that addition of the reducing solution lowered the anodic potential of the titanium alloy by 200 - 300 mV (depending on the solution resistance), but that it was still +300 to 400 mV with respect to a standard calomel electrode. It was shown that, if necessary, a small impressed current could be applied to provide anodic protection. Before scale deposition was overcome by the addition of ferrous sulfate solution, badly scaled heat exchangers were cleaned by recirculating a solution of hydrogen peroxide in spent electrolyte or dilute aqueous sulfuric acid, after laboratory testing of a variety of possible solvents for the scale. Corrosion tests indicated that attack on the titanium alloy by the acidic peroxide cleaning solution was insignificant.

Jan 1, 2005

By Hll J. K, Zhang Y. G

The wear mechanisms of impregnated diamond drill bit matrices are complex and believed to be the key point in solving drill bit self-sharpening problems. A method has been developed to find the change in c,, the wear rate of matrices having different fracture toughness K_ at the increment of drill pressure P. The worn surfaces of specimens were placed under a scanning electron microscope to examine the wear patterns and wear mechanisms at different pressures, and were compared with the worn surface of a practical drill bit. A model is proposed that within a wide range of pressures there exist two different wear mechanisms and three wear regions for cemented car- bide matrix materials. In region one (linear region), at low pressure, the major wear mechanism is plastic deformation in which the preferential wear of the binder phase of the matrix results in the loss of WC, tung- sten carbide particles. Wear rate is controlled by hardness, H as Archard's formula predicts. Wear enters region two and three (non-linear region) simultaneously as pressure is being increased. Consequently, wear transfers to fracture mechanism in which micro-fracture occurs at the root of wear grooves and the material is removed mainly in piece and mass. It has been shown fracture toughness K,, plays a more important role than hard- ness H. It is concluded that for a specific drilling condition, the pressure on the matrix should be carefully controlled and a balance between hard- ness and toughness of the material is essential for a steady drilling Condition.

Jan 1, 1989

By D Chalmers

Drill and blast mining techniques are used to mine coal outburst prone and high gas content coals in Australia. As the risk of an outburst is increased in high gas content coal, it is considered that drill and blast is the safest way to mine coals that refuse to yield gas even after considerable gas drainage efforts. The availability of suitable explosives for drill and blast in Australia is dependent on the æBuxtonÆ tests. With the diminished coal operations in England, the type and supply of such explosives is tenuous, causing significant disruption to the production of coal in some mines. In an attempt to free up the availability of explosives a review of the methods used for the testing of coal mine explosives was undertaken to ascertain the scientific basis for these tests. It was hoped that this comparison would allow regulators to have the confidence in explosives that had been tested elsewhere. Although this was not achieved, it has spawned a major research project that aims to better understand the mechanisms involved so that either confirmation of the current testing regime can be achieved or more suitable and scientifically based tests can be adopted. This paper looks at the ongoing research program investigating the parameters that are involved with methane ignitions from explosives. By utilising high-speed data capture and processing the research project is trying to view an ignition as it happens to identify the mechanisms involved so that better explosives can be designed for the coal mining industry.

Jan 1, 2007

By M Araos, I Onederra

A novel explosive formulation that substitutes the use of ammonium nitrate (AN) with hydrogen peroxide (HP) as the main oxidising agent has been developed and tested as part of an Australian Coal Industry Research Program (ACARP) project. The main objective was to provide a step-change solution that has the potential to completely eliminate NOx fumes in blasting. The development of this HP/fuel-based explosive started with a comprehensive detonation characterisation program, consisting of unconfined velocity of detonation (VOD) measurements of samples at different diameters, densities and void sensitisation techniques. VOD results showed that the HP/fuel-based explosive mixtures behaved similarly to non-ideal commercial explosives; in that way mixtures could be tailored to achieve specific detonation performance targets. The next stage of testing in this development involved preliminary confined tests to evaluate the rock breakage potential of the HP/fuel-based explosive mixtures. Fully instrumented single-hole tests were conducted in a limestone quarry. Results from these preliminary trials confirmed the rock breakage performance of HP/fuel-based explosive mixtures. The confined VOD measured in one of the tests was 5100 m/s in a 102 mm diameter blasthole at a density of 0.96 g/ml. The corresponding borehole pressure measurement of this HP charge was 2.61 GPa with a detonation temperature of 2921°C. Based on near-field accelerations, both HP and ANFO charges displayed similar attenuation characteristics in the test conditions. Post-blast observations indicated that the breakage performance of the HP mixtures clearly reflected the in-hole detonation performance measurements obtained, confirming the ability of these explosive mixtures to both fragment and effectively displace the rock mass under evaluation. Further research work continues with the future commissioning of a prototype mixing and delivery unit, the successful completion and analysis of data from multiple-hole trials, and further characterisation work associated with product stability, reliability and performance under different geotechnical conditions.CITATION:Onederra, I and Araos, M, 2015. Detonation and breakage performance of a hydrogen peroxide-based explosive formulation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 565–574 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

During the 1998/99 Asian crisis Solid Energy's export revenues collapsed from over US$70M to under US$40M. Simultaneously, domestic market uncertainty led to decreases in volumes and prices. A major new underground mine was not technically viable, and was closed, and several other mines were marginal. Less than two years later, Solid Energy and its JV partner closed a second new underground mine. The company was in financial crisis, and reported an $86M loss for 1998/99. After refinancing with stringent workout conditions it still had minimal returns due to low prices, unaffordable transportation costs and huge unrealised FX losses as the NZ dollar fell 40 per cent in value. The obvious scenario was to æcash upÆ û complete extraction at remaining mines, sell off any viable parts of the business, pay off debt and wind the company down.In 2002 Solid Energy has completed its recovery. Although margins remain slim and volatile in both export and domestic markets, it is achieving record volumes and revenues. It has paid off its shareholder loan, has minimal remaining FX losses, and cashflow is allowing further mine and infrastructure development. The key to the turnaround has been implementation of rigorous planning, analysis and decision-making in all aspects of the business. The company has a comprehensive, rolling 20-year plan used annually to update rolling five year and annual business plans. Solid Energy augments strong line management operations with rigorous standards and processes for mine planning and development, operational decision-making, and functional support. Detailed, quantitative risk analysis is used in all aspects of the business and allows comprehensive integration of opportunity and risk management across all activities in the company.Coal mining is widely perceived as an æold-economyÆ industry. But, like other successful æold economyÆ companies, the information systems and management processes used by Solid Energy are as leading edge as any in the high-tech sector. They are the key to managing to add and sustain maximum value for a company that has access to coal resources sufficient for hundreds of years.

Jan 1, 2002

The Porgera gold project is now in its seventh year of operation as one of the world's prime gold mining projects in one of the most underdeveloped and remote regions of the world. The unique gold deposit was development in stages to its present size of operation with an underground mine of 2000tpd, an open pit operation moving 210,000tpd and a complex metallurgical plant treating an average of 16,500tpd of ore. During the past years the operation had to address an array of issues relating to the "development" of the region and this is still ongoing. Development means different things to different people and though the parties that signed the different agreements relating to the Mining Development Contract were aware of this, none has real- ised the extent to which this is true. The developing company (a joint venture between Placer Pacific as the Manager, Goldfields Porgera, Highlands Gold and the Government of PNG), provided funds for risky exploration and the capital for development of the project. Its shareholders ex- pect an economic and viable mine operation from the deposit to ensure them returns on their investment. The local people gave up their land, their isolated way of living and accepted to be out of their comfort zone for some time in anticipation of a better lifestyle and economic benefits in support of that lifestyle. The PNG Government has a leg in both camps and expects both outcomes at the same time. The Government is also the regulator and expects compliance on top of that. If development in general is to be successful, all parties must substantially satisfy all expectations. It is evident that the outcome of some elements of development are reasonably defined (i.e. develop a viable mine to exploit the deposit), whilst other elements are moving targets (i.e. a better lifestyle). The seeds for conflict are thus abundantly present and to resolve them requires the will of all parties in all areas to come to a solution. This path to problem solving is many times torturous as each party comes from a different culture and background and has a different understanding of the parameters in the equation.

Jan 1, 1997

By Sale M, Clarke R, Parker M

The Mount Gibson goidmine is located at the southern end of the Retaliation greenstone belt within the Murchison Province, approximately 300 km northeast of Perth, Western Australia. Economic gold mineralization occurs in the upper part of a Tertiary lateritic surface; its ultimate source presumably being Archaean greenstones. Gold is present in the laterite profile over a distance of 4 km in four separate prospects, from north to south, Mount Gibson Well, Midway, Orion and Tobias Find, the two last constituting the Mount Gibson mine. The area has'low relief. A low ridge to the west of the mineralized zone is formed mainly of rubble with minor outcrops of mafic volcanic and intrusive rocks. The terrain slopes gently to the northeast, and the maximum relief, in the vicinity of the mineralization, is about 20 m. The weathering profile comprises, from the surface: (i) soil, windblown sand or colluvium (thin), (ii) laterite; hardcap (including ferricrete and lesser silcrete and calcrete) is overlain by loose nodules and pisolites, and passes downwards into a mottled zone of variably ferruginized clay, (iii) clay; mainly pale brown, cream or yellow in colour, but in places contains relic quartz veins or dark ferruginous zones, (iv) clay with fragments of altered rock; normally grey to pale green in colour but sometimes includes an oxidized iron-rich horizon just above the weathered/fresh rock interface, (v) bedrock. The complete profile varies from 10-100 m thick, averaging 20 m. Zone (ii) is commonly 3-5 m thick. Loose pisolites of this zone fill cavities in the massive ironstone left by former tree roots, and cover irregular depressions which may represent former stream courses. Samples, representing 3 m intervals down the holes, have been collected from cuttings taken from rotary drill-holes along each of four traverses; one traverse at each-of the northern prospects and two traverses in the Orion part of the mine area. These samples have been submitted for X-ray diffraction analysis and for chemical analysis for a wide range of elements. Bedrock lithologies have been determined from microscope studies of bottom-of-hole chips.

Jan 1, 1988

Equity finance provides the most suitable and frequently the only access to capital during the exploration and evaluation stages of resource projects when project risk is at its highest. Investors are prepared to provide equity funds in the knowledge that they are compensated for the higher risk they take on with higher potential returns or sufficient upside potential to justify the higher risk. The context of resource projects which determines the role of equity finance has changed considerably. Prior to the resurgence of the gold price and the development of new mining technology many resource projects were selectively mining orebodies by underground methods frequently with limited reserves proved up in advance of mining. The limited proved ore reserves base and the volatility of the gold price all contributed to a higher risk and higher return investment environment in which the use of equity finance was more appropriate and frequently the only option for capital raising. The financial risk of a resources project can be transferred to an underwriter who makes the commitment to distribute the financial risk between a number of investors. There is also the opportunity for financiers to use a mix of equity and debt finance to allow a company to proceed with the development stage where without such a mix the resource project would not proceed. By using a level of equity finance the project becomes robust enough in its ability to service the debt finance facility and the project proceeds with the equity participants receiving a suitable risk reward return. The liquidity from the establishment of a market for the company's securities enhances further capital raising and generally enables the company to satisfy its financial requirements on more favourable terms particularly during bull markets. The role of equity finance in the management of the financial risk during the exploration, evaluation, development and mining stages of resource projects is summarised in Table 1. In more detail the principal roles of equity finance and the ways in which equity finance impact on the risk management of resource projects will be considered in turn.

Jan 1, 1994

HAPPENING to be in Cue recently the writer was unexpectedly called upon to make surveys of some diamond drill bores on the Big Bell mine on the Murchison goldfield. The owner of the mine Mr Herman Mandelstam. had brought such apparatus with himas he could lay his hands on. and no other was available without prohibitive delay.The usual method of making these surveys as is well known is by putting a glass tube half filled with gelatine or glue in a melted state down the hole with a small magnet freely suspended in the glue and having it there till the glue sets solid. When this tubeis withdrawn (its depth down the bore being noted) the bearing and inclination of the borehole at this particular point can be read - the bearing by the compass and the inclination by the angle between the tube and the surface of the glue which of course ishorizontal. By taking a number of these observations according to the degree of accuracy required the course of the bore can be fairly accurately plotted.In dealing with dry holes there is little trouble but when the holes are full of water great difficulty is experienced. In the case in point the first observation was made in water 300 ft. deep, corresponding to a pressure of 130 lb. per sq. in. The tube containing the gelatine and glue (a mixture was used) was found, when hauled to the surface, to be completely filled with a weak mixture of water, gelatine, and glue and there was no horizontal surface from which to measure the angle of inclination of the bore. The water had been forced through the corks and sealing wax with which the tube had been closed. After several attempts it became obvious that no method available would keep the water from getting into the air-space in the tube, and to a pressure-proof metal container was impossible, nothing remained but to do away with the air-space and this was accomplished by using two liquids of different specific gravity - mercury and melted glue. The tube...

Jan 1, 1930

It is indeed an honour to address the perth branch of the australian institute of mining and metallurgy and to have the opportunity to talk to you about the future role of upgraded ilmenite on t102 feedstock supply and demand. There have been many papers written on upgraded ilmenite supply and demand and now I would like to share with you QIT's view of the situation first, a word about demand, although I will be talking principally on the supply issue. The principal use of t102 is in the manufacture of pigments which, in turn, are used in paints, plastics, and the paper industry together with a few miscellaneous uses, while a further b% or so of t102 minerals are consumed for the manufacture of titanium metal and for the manufacture of welding electrodes. the total demand for contained t102 is of the order-of 3 million tons per annum, and the general consensus in the industry is that growth rates should be of the order of 2% annually- it is against this backdrop that suppliers must compete with one another and produce least cost materials for the pigment industry. At the moment, supplies are relatively tight, but the generally slow growth in demand coupled with the abundance of titanium bearing minerals should ensure that long term the reverse is generally true. Now, let us examine the supply situation. Titanium is the 9th most abundant element in the earth's crust, so the problem from the producers` point of view is not one of scarcity of titanium minerals, but of how to extract most economically t102 feedstocks from a wide variety of choices- up to the present, all titanium feedstocks are being derived from either rutile or ilmenite rutile, at about 95% t102 content, is indeed a premier raw material which does suffer from potential scarcity and rutile supplies will likely be a diminishing factor in future decades- whereas ilmenite, a combination of iron and titanium oxides found in varying ratios, may be found in huge quantities all over the world.

Jan 1, 1986

Reliable sampling practices are the key to optimising the market value of a mining or chemical companyÆs stock. As a result, reliable sampling standards are needed. However, current standards on sampling present the æuniversalÆ Pierre GyÆs Sampling Theory in an ambiguous way. For example, the Total Sampling Error is divided into its basic components only in informative annexes, when it should clearly be the main body of the standard. Sampling standards are presently loaded with statistical concepts that actually belong in the annexes. Furthermore, many non-probabilistic sampling procedures are still mentioned which do not belong in a standard. The objective is not to criticise existing sampling standards, but to suggest better ones. Sections on the Sampling Theory should divide the Total Sampling Error into a sum of its nine basic components. Then, and only then, should they be addressed one at the time. Sections for establishing a sampling protocol should address the in situ Nugget Effect, the Fundamental Error, the Grouping and Segregation Error, the Long Range Quality Fluctuation Error, and the Periodic Quality Fluctuation Error. Sections for sampling methods, mechanical sampling, manual sampling, grab sampling, sampling of trucks, railroad cars, bags, and drums should be part of the critically important practical implementation of a recommended sampling protocol, called Sampling Correctness. It includes the increment Delimitation Error, the increment Extraction Error, the Weighting Error, and the Preparation Errors. Unless these errors are addressed one at a time, in an unambiguous way, the standard will remain ineffective in solving sampling problems for the industry. Therefore, a strategy is needed to create better standards required at the early stages of new projects, both by manufacturers of sampling equipment and by engineering firms. A logical sequence of important points that cannot be ignored in any sampling standard is presented. An analysis of the practical use of the words sampling uncertainty versus sampling error is recalled. Finally, as a practical example, an in-depth analysis of the correctness of cross-belt samplers is presented, and emphasis is placed on the correct ways to perform bias-tests for mechanical sampling systems.

Jan 1, 2005

The Youga gold mine in Burkina Faso, West Africa, is scheduled to produce first gold in the third quarter of calendar 2007. The project is expected to produce 540 000 oz of gold over 6.5 years, from a conventional open pit carbon in leach mine. The direct capital cost of the project is US$47 M. Etruscan Resources Inc, a Canadian based gold exploration and development company, holds 90 per cent of the project company Burkina Mining Company SA (BMC). The state of Burkina Faso is free-carried for the remaining ten per cent of BMC. RMB Resources Limited, of Melbourne Australia, has arranged a US$35 M project finance facility for BMC (the Borrower) as the majority of funding for the Youga project development. The loan facility was provided by RMB Australia Holdings and Macquarie Bank Ltd (the Lenders) each as to 50 per cent in the lending syndicate. The Lenders also provided a gold hedging facility to guarantee a minimum price for the projectÆs gold production. Burkina Faso is a francophone country, part of the Economic and Monetary Union of West Africa (UEMOA). The project financing is the first such facility to be arranged for a mining project in Burkina Faso, with little or no precedent available in other UEMOA countries. Therefore, while the Youga gold project is forecast to be a robust project applying conventional mining and processing methods, a number of legal, technical, commercial and social issues required identification, evaluation and resolution before the loan could be established. This paper describes that evaluation process and the resolution of these issues. In-house experience and expertise in both the LendersÆ and BorrowerÆs teams has facilitated a greater understanding and æownershipÆ of the issues and hence provided comfort with risks which might not normally be taken in conventional project developments and project financings. As a result, blanket external reviews were not required by the Lenders. A long-standing relationship between Etruscan and RMB Resources also facilitated solutions to a number of issues. Nevertheless, a degree of flexibility by the Lenders, the Borrower and Etruscan was required to successfully close the financing.

Jan 1, 2007

By D Schwab, R M. Tosdal

The Quesnell-Stikine arcs, in the Canadian Cordillera, are host to Triassic and Early Jurassic alkalic porphyry Cu-Au and calc-alkalic porphyry Cu-(Mo-Au) deposits formed outboard of ancestralNorth America in island-arc tectonic settings (McMillan, 1991). The majority of the alkalic porphyry Cu-Au deposits are products of a discrete magmatic event at the end of the Triassic, with a second and smaller event in the Early Jurassic (Mortensen, Ghosh and Ferri, 1995). Of the Triassic complexes, the Galore Creek alkalic intrusive suite is one of the largest and most silica-undersaturated intrusive complexes, and host to the most significant undeveloped alkalic porphyry Cu-Au resource in North America (Lang, Stanley and Thompson, 1995). Because of the common presence of feldspathoidal-bearing rocks in the complex (Enns et al, 1995), Galore Creek likely represents an end member example of the alkalic porphyry Cu-Au class. The Galore Creek alkalic Cu-Au-Ag porphyry district, located in NW British Columbia (Canada), contains 12 mineralised prospects (Enns et al, 1995; Micko et al, 2007; Schwab et al, in press) with a total measured and indicated resources of 785.7 Mt at 0.52 per cent Cu, 0.29 g/t Au and 4.87 g/t Ag (NovaGold Resources Inc, February, 2008). The Central Zone is the largest and best delineated. Other economically important mineralised centres include the South-West, Bountiful, West Fork and Junction deposits. The South-West Zone, the focus of this contribution, is a Cu-Au-Ag breccia-centred deposit with a measured and indicated resource of 69 Mt grading 0.42 per cent Cu, 0.69 g/t Au, 2.67 g/t Ag. Hosted in brecciated intrusive rocks, the South-West Zone is distinctly younger than the Central Zone and most of the other mineralised centres (Enns et al, 1995; Schwab et al, in press). The South-West Zone therefore preserves the late stages of hydrothermal evolution at Galore Creek. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Van Deventer J S J

The first step in the design of a process to treat a possible economic precious metal deposit should be an examination of the mineralogy of the ore. Using this and other initial tests, the extractive metallurgist can design a process to treat the ore. In the field of precious metal metallurgy, little emphasis is placed on the mineralogical information available to the metallurgist. The information is of far more use to the geologist and the mining engineer. Diagnostic leaching was designed to open up the field of mineralogical analysis to the metallurgist. When a mineralogist looks at the deportment of gold in an ore, he is usually looking for an element which is present in parts per million, so that errors in sampling are multiplied dramatically. Diagnostic leaching offers a cheap, simple, practical alternative. In order to determine with which minerals the desired precious metal is associated, a specific mineral is first eliminated using a selective oxidative leach, and cyanidation is used to extract the precious metal (in this case gold and silver) liberated by the destruction of this mineral. The precious metal extracted can be measured in solution to give a fairly accurate record of the amount of the precious metal associated with that mineral. Furthermore, the residue from this first stage can be subjected to another selective acid leach, and the process repeated. The procedure can be varied to suit the mineralogy of the matrix material. At the end of this diagnostic leach the metallurgist is left with a complete record of the deportment of the precious metal. He can now use this information to design a metallurgical flowsheet to treat the ore. Diagnostic leaching is thus an analytical tool which can be used by the metallurgist not only to examine new ores, but also to look at problems occurring at existing plants. The procedure is not only limited to ores and residues but in fact can deal with any type of intermediary product that occurs on a plant. The information gained from analysing an intermediary product can give a useful indication of how well a unit process is working, eg flotation, roasting, etc.

Jan 1, 1992

Krupp Polysius AG, FRG, in close cooperation with Prof. Dr. K. Schoenert, FRG have developed the principle of the high pressure grind- ing roll POLYCOM. The POLYCOM mill basically consists of two counter-rotating rolls of large diameter and relatively small width, one of which is fixed and the other moving in slide blocks. The pressure required for comminu- tion is applied via the sliding roll by a powerful hydraulic system. The comminution takes place between the rolls under high pressure in the bed of material by nipping and compacting. The top feed size-depending on the rolls diameter -may be as coarse as conventional secondary crusher feed and the product is a compacted cake containing a high amount of fines created by micro-cracking. The amount of fines depends on the pres- sure (grinding force) applied. Operating results show that even in wet griding circuits capacity increases at downstream connected grinding mills of up to 100010 can be accomplished with an interconnected POLYCOM machine and energy savings of up to 25070 may be achieved depending on application. POLYCOM can be used in existing grinding plants for low-cost upgrad- ing of capacities but also as an advanced alternative to conventional crush- ing and grinding equipment in open or closed circuit configuration. A single industrial size 2.8m roll diameter POLYCOM machine may be fed with top feed size of up to 200mm and produce a finish product as fine- grained as known from rod and ball mills but with less energy consumption. Meanwhile, the POLYCOM high pressure grinding roll has established itself world-wide in the cement industry and is now entering the mining industry. POLYCOM machines are currently designed in industrial standard sizes of 1.0m to 2.0m rolls diameter and drive units of up to 2400 kW. This paper includes: principles of high pressure grinding, main fea tures of the POLYCOM machine, results of tests on various materials including Australian gold and copper ores carried out at the POLYSIUS research centre in Germany. Some examples of industrial applications of high pressure grinding will also be presented.

Jan 1, 1988