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Resource rent tax is a form of taxation or royalty, which only become effective at such a time as a pre-determined rate of return has been achieved by an operation. The offshore petroleum industry in Australia is already subject to RRT as is the Roxby Downs (Olympic Dam) Mine in South Australia. Both the mining and petroleum taxation regimes in Papua New Guinea include a resource rent tax component called Additional Profits Tax (APT). The implications of the current form of Additional Profits Tax for shareholder cash returns are that the tax burden on the operation may suddenly increase at some stage in the life of the mine, if and when the threshold level of profitability for the tax to be triggered is exceeded. From that point in time onwards the cash return to the shareholders on the capital invested is greatly diminished. For mining companies in Papua New Guinea, the effective tax rate increases from 35% to 57.75% as a result of the onset of Additional Profits Tax. This tax rate penalty is so severe that there appears to be merit in considering the concept of managing profitability through time rather than purely maximising annual pre-tax profits as is currently the case in most mining operations. This would have the benefit of deferring or perhaps preventing altogether the onset of the tax. One possible method for the effective management of profitability is through the control of average mining grade by cutoff grade manipulation. Traditional cutoff grade theory has usually considered taxation as a direct cost at a fixed or variable percentage of annual profits. As a result of this most analyses are conducted on a pre-tax basis. If tax is included in analyses it is usually present as a time independent function of gross profit. Additional Profits Tax is both time and rate of return dependent and therefore not adequately accommodated by currently accepted cutoff grade theory. A review has been made of the effects of resource rent taxes on both the investment decision-making process as well as possible development and mining strategies which may be employed by mining companies faced with Additional Profits Tax. The review includes examples based on the structure of Additional Profits Tax which is levied in Papua New Guinea.

Jan 1, 1997

The Honeymoon Well nickel sulphide deposits are located in the Agnew-Wiluna greenstone belt, about 45 km south of Wiluna. Both disseminated and massive sulphide nickel deposits are hosted by komatiitic rocks within the deformed and metamorphosed Honeymoon Well ultramafic complex. Fresh ultramafic bedrock is covered by up to 50 m of highly conductive transported material which greatly hampers both exploration and understanding of the bedrock geology. In the early-1970s, mineralisation was discovered by diamond drilling geochemical anomalies defined by wide-spaced percussion drilling over ultramafics that had been outlined by ground magnetics. Subsequent drilling has defined a resource of 158 Mt at 0.71 per cent nickel (based on 0.4 per cent nickel cut-off, 300 m below surface, December 1995) in four deposits. Over the life of the project a wide range of geophysical techniques have been used including airborne and ground magnetics, time domain clectromagnetics (EM), induced polarisation (IP)/resistivity, gravity and downhole techniques including EM, IP and physical property Measurements.

Jan 1, 1996

By M-A Van Ende, N Kumar, I-H Jung

In order to utilise the powerful thermodynamic databases for process simulations, a concept called Effective Equilibrium Reaction Zone (EERZ) was introduced to couple thermodynamic database calculations and reaction kinetics. Using the EERZ concept, many process simulation models for steelmaking processes have been developed within the FactSage steelmaking consortium. After validation of the simulation results by comparing with plant data, the simulation models have been applied to improve plant operations. Several success stories of the improvement of real steelmaking operations are shared. A new user-friendly FactProSim software developed for building process simulations is introduced.

Aug 21, 2024

By Lauha E. A

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike subdistrict, there are seven major deposits; Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the subdistrict are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Bamck Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post, and Deep Star occur both on Barrick and Newmont Property.

Jan 1, 1991

The ore mined from the Lead Lode of The Zinc Corporation leases consists of a fairly granular mixture of galena, marmatite, chalcopyrite, tetrahedrite, pyrrhotite, pyrite, and lollingite with a gangue association of calcite, quartz, bustamite, rhodonite, mangan-hedenbergite, garnet, fluorite, mangano-calcite and apatite. The silver content of the ore occurs in three minerals tetrahedrite, dyscrasite, and pyrargyrite, the last two mentioned occurring in microscopic association only. Other metallic and gangue minerals are also present in this complex mineralogical association, but do not influence the milling operations.Fortunately, the silver minerals favour the galena and chalcopyrite as their host minerals, thus facilitating the recovery of both copper and silver in the lead concentrate. The ore from the Lead Lode assays from 14 - 18 per cent lead; 3.0 - 4.5 oz silver per tonne, and 9.5 - 12.0 per cent zinc.A parallel lode, known as the Zinc Lode, is well developed in The Zinc Corporation leases. This lode assays from six to eight per cent lead, 1.5 oz silver per ton, 18 - 25 per cent zinc with a siliceous gangue. The common Lead Lode gangue minerals, calcite, rhodonite, bustamite - are very rare in present underground exposures. No metallurgical work was done on this ore during the pilot plant operations.The aim in the milling process is to produce:1. A lead concentrate with the maximum economic recovery of lead, silver, gold, copper and antimony, and minimum zinc content.2. A zinc concentrate with the maximum economic recovery of zinc, cadmium, and cobalt, and minimum iron, arsenic and fluorine content.3. A waste residue containing sufftcient granular material to be utilised as underground fill.In considering the economics of the milling practice the above three requirements plus consideration of the tariffs submitted by the purchasers of concentrates were the deciding factors in the evolution of the present milling practice.Towards the end of 1924 The Zinc Corporation Limited added to and adapted the old zinc tailings plant for the treatment of 5000 tons of crude ore per week. This plant, which operated until January 1936, was in general principles similar to the standard Broken Hill methods of ore concentration, whereby the galena was recovered by the gravity concentration methods of jigging and tabling with selective flotation concentration of the residual galena and marmatite. One important difference from other Broken Hill plants was that the primary grinding of the jig tailing was performed with flint-loaded mills operating in closed circuit with revolving screens. Two primary grinding sections were installed, each consisting of two 5 ft diameter by 10ft long tube mills loaded with flint pebbles working in closed circuit with four 3 ft diameter by 3 ft wide revolving screens covered with 22mesh Toncap woven wire screen with 0.57 mm opening. Each section carried a circulating load of 28.3 tons per hour for a jig.

Jan 1, 1994

By Heyer T, Wasmuth H-D

The concentrator plant of Fahrica Mine, that started production in 1977, was using nine Jones wet high intensity magnetic separators (WHIMS) of the standard type DP 317 with a 1.5 mm gap width for the production of pelletfeed concentrate. These WHIMS units were operating in parallel with a feed rate of 110 t per hour, with about 47 per cent Fe in the feed, and with a maximum of only 0.8 per cent magnetite. The field strength was about 1.2 Tesla. From 1986, the mine has adapted its production facilities to mine and concentrate larger amounts of lowgrade itabintes to maximise the use of the available iron ore reserves. An increase of up to three per cent magnetite in the magnetic separator feed, resulted in a reduction of capacity. This was due to partial clogging of the separation boxes at high field intensities, which were required for the recovery of the very fine hematite. Even by lowering the feed rate and the field intensity the problem could not be resolved. After extensive testwork in a pilot plant, with a Jones separator model DI' 90, the commercial WHIMS plant was modified into a two stage process using the existing nine Jones separators. The gap of the first stage with four machines was increased to a width of 3.5 mm, corresponding to a maximum field intensity of 0.7 Tesla. This first 'medium intensity scalping stage' is followed by a second 'real' high intensity WHIMS step with five machines operating at the original settings with 1.5 mm gap width and 1.0 Testa maximum field intensity. Feed rates of up to 320 tons per hour in the first and up to 240 tons per hour in the second stage could be achieved. The design concept of the concentrator at Fabrica mine is described using the old and new flowsheets. Details of the pilot plant testwork as well as actual performance data of the new plant section are presented.

Jan 1, 1993

Jan 1, 2004

The procedures for an audit and review process upon which continuous improvement programs may be based are described. The case for regular audits of mining operations to establish performance trends is advanced. Analysis of performance data using the parameters of the capacity equation used in conjunction with learning curves is described. The extrapolation of learning curves in performance target setting, operating and capital cost budgeting is advocated.

Jan 1, 1992

By P H. Warton

It is proposed to construct a gold extraction plant at Matatoki, near Thanes. Ore to be processed at the mill will come from reopened and enlarged underground mines north of Thanes. The project has been described in some detail in environmental impact reports (Worley Consultants Ltd 1984, 1987), and is now at an advanced stage in terms of obtaining the required statutory approvals.

Jan 1, 1987

Underground mechanized excavation in New Zealand has become more commonplace in civil and mining applications during the last three years. At one stage up to seven Dosco Road- header machines were being used on different projects around the country. The Huntly West Mine Drifts inclined at one in four were by far the most severe grade conditions that the machines were subjected to; however, other operations posed their own particular problems for the machines. Two major interrelated factors became evident as soon as the machines commenced at Huntly. These were traction problems on the grade and control of water, particularly on the invert.

Jan 1, 1978

The purpose, basic data requirements and various analysis/modelling tools employed for geomechanical evaluation of mine-site conditions are overviewed. The impact and application of computer technology are dis- cussed. Broad guidelines and criteria are presented for establishment of a practical geomechanics data-base system to yield infor- mation suitable for mine design purposes. Future needs of the Australian mining in- dustry are examined.

Jan 1, 1983

This paper addresses; land use, rehabilitation and the State/Federal regulatory process, in light of Australia signing various international conventions and agreements in the area of environmental protection. The conventions on biological diversity, climate change and the implications of the Rio and Agenda 21 declarations are examined. The implementation of these initiatives through the Inter-Governmental Agreement on the Environment, and through legistlative mechanisms at Federal and State level is explored.Particular attention is given to the biodiversity strategy in context of the need to integrate economic aspirations and environmental concerns as a basis for sustsainable development. The paper concludes with a brief comparison of the major approval processes in each State, relating to mining environmental issues.

Jan 1, 1992

By Morley I. W

Offshore minerals legislation has been introduced to provide jurisdiction over the exploration and recovery of mineral resources, particularly petroleum, from the territorial waters and parts of the continental shelves adjacent to coastal states. Ratificat- ion of the 1958 Geneva Conventions on the Law of the Sea has provided some measure of international agreement amongst signatory powers. Because the relationship of the Australian States to the Commonwealth in their federal system, the Australian offshore petroleum legislation is of particular interest. The customary role of the States in mineral resources management, which has extended to the offshore, is under challenge from recent unilateral Commonwealth Government legislative actions in the fields of mineral resources jurisdiction. Environmental considerations provide an additional issue, as yet unresolved, with the delay in submission of the Report of the Great Barrier Reef Petroleum Drilling Royal Commissions

Jan 1, 1974

By Piotto P

Pit optimisation algorithms are designed to produce a pit with maximum value, but for certain minerals like iron ore, limestone, coal, etc, it is also necessary that the designed pit contains ore which meets the customer's chemical specifications. This paper describes a technique of using linear programming for blending optimisation and the Lerchs-Grossmann algorithm (as in Whittle's 3D software) for pit optimisation in tandem, to achieve pit designs of targeted grade specifications.

Jan 1, 1996

The relationship between the permeability of coal to a mixture of methane and carbon dioxide, and the permeability to methane and carbon dioxide separately is described in this paper, along with the analysis of the differences in permeabilities of coal to methane and carbon dioxide.

Jan 1, 1989

By Jifan X, Yongyu W, Liangjing L

Shallow interception of groundwater is a special dewa- tering form in the specific geological and hydrogeological conditions. It has an economic and technical effect. The roof of the Fankou Lead-zinc deposit is the Hutianqun aquifer made up of the limestone of the upper Carboniferous system. - A "water-bearing basin" is surrounded by the aquifuge and the aquitard below ¦0 m level at the Shiling Hill section in the Hutianqun aquifer. Based on the natural conditions, an interception gallery is excavated at -40 m level out of "the water- bearing basin", the other gallery excavated at ¦0 m level in the poor water-bearing zone of the Jinxing Hill. During 20 years of experience, the better interception effects have been gained.

Jan 1, 1988

Because of the mineralogical complexity of nickeliferous laterites, most commercial and laboratory extractive processes require the ore to be blended to a feed of "constant" chemical composition. Even using the "constant" feed there are significant variations in processing behaviour within and between different feed lots. Chemical and mineralogical analyses of lumps of ore taken from the Yabulu stockpile of Queensland Nickel have highlighted the complex- ity of the ore making up the blended feed material. Each sample has been subjected to acid leaching and reduction/ammonia leaching tests and the results correlated with the mineralogical location of the nickel. The consequences of the variability in ease of leaching of the nickel are indicated.

Jan 1, 1978

The Transportable Moisture Limits, as ,measured by the procedures laid down in The IMCO Code of Safe Practices for Bulk Cargoes, determine the target moisture contents for the concentrates produced at the West Coast Mines of Electrolytic Zinc Company of Australasia Limited at Rosebery. Filtration of these concentrates gives moisture contents considered to be low in comparison with those achieved for similar sulphide concentrates, but which are very close to these Transportable Moisture Limits. The filtering techniques used are outlined and the problems associated with-maintaining concentrate moistures below the required limits, together with the methods used to solve these problems are discussed.

Jan 1, 1978

By G K. Robinson

The existence of bias in samples taken by cross-stream sample cutters has been investigated using three-dimensional discrete element method (DEM) modelling. Detailed quantitative information on overall extraction ratios, size specific extraction ratios, missed and extra sample components can be made by comparing a reference sample to the actual sample. A key advantage of using this modelling approach over physical experimentation is that the reference sample can be measured on precisely the same portion of the stream of material as the actual sample, thereby allowing the elimination of a significant fraction of the variability and allowing statistically significant results to be obtained using many fewer replicates. Quantitative analysis of results broadly supports the commonly-used rule that the cutter aperture should be at least three times the nominal top-size of the material being sampled, but does not support the commonly-used rule requiring increase in cutter aperture if the cutter speed exceeds 0.6 m/s. Sampler performance can be understood in terms of the balance of forces in the congested region of material formed by the slowing of the particle stream due to collisional interactions around the mouth of the cutter.

Jan 1, 2008

By Ciminelli VST

Thiourea leaching has been applied to a refractory gold concentrate previously treated by bacterial oxidation. Following the bio-oxidation, gold has been leached in acidic thiourea solutions, under different pH(1 - 2.4), thiourea concentrations (2 - 15 g/1), ferric ion concentrations (0.04 - 3 g/1) and temperatures (298 - 333 K). Through this procedure, it was possible to increase gold extraction from 40 to 77 per cent. The increase in temperature raised gold extraction and reduced reagent consumption. Sodium sulphite addition was also very effective in lowering thiourea consumption. Staged leaching operations with interstage acid washing and carbon-in-leach experiments were tested, in an attempt to increase gold extraction. The results of thiourea leaching were compared with those obtained with cyanidation.

Jan 1, 1993