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By A D. Stewart Gillies

Resource rent taxes are taxes which only become effective at such a time as a pre-determined rate of return has been achieved by an operation. Resource Rent Taxes have from time to time been considered for implementation in bothAustralia and New Zealand. 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.   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 resource rent taxes. The review includes examples based on the structure of additional profits tax which is levied in Papua New Guinea.

Jan 1, 1995

The need for legislative reform of health and safety legislation has been recognised in New Zealand for about a decade. Previous legislation did not cover all work places, many areas were excluded from coverage, and there were at least 14 different acts and dozens of sets of regulations dealing with various aspects of health and safety.

Jan 1, 1993

IN all wet concentration processes it is of primary importance to determine to what degree the crushing must be carried in order to obtain the maximum profit per ton of ore milled.To effect a clean separation, either by gravity or flotation treatment, between either one valuable sulphide from another, or a sUlphide from the gangue, the ore must have been subjected to grinding to such an extent that the particles to be separated are completely liberated from each other.Insufficient crushing will result in either an incomplete separation of the sulphides from each other, and thus a loss of the one sulphide in the other, or else a loss of the valuable sulphide in the gangue.This being so, the question arises whether the added cost of extra crushing would be economically warranted by the increased recovery consequent on such a step.

Jan 1, 1927

At the inception of the gold-mining industry at Kalgoorlie the small supply of firewood required for steaming purposes was naturally all drawn from the limited local areas, which promised soon to become denuded. With the advent of the railway toKalgoorlie came the ever increasing machinery and steam power, and the accompanying demand for firewood so increased that the fuel contractors began their operations, by following the timber belts along the Yilgarn railway line, and graduallygetting further westward, until at present we find them as far as Woolgangie, 63 miles from Kalgoorlie, and with the regular railway rates, I0. per ton per mile, this maybe considered the limit of payable timber at current rates. Although in the early days the reserve of timber along the railway line must have appeared as incalculable and inexhaustible as that of coal did in Europe a couple of centurys ago, the day is now near us when even this source will fail to meet the demands made upon it, for, although a good two years' supply is available or the areas under the axe, yet it is time to look ahead and find from whence the future supplies are to be drawn. Along the railways we find the zone of felling operations limited for want ofcommunication, and only such portions of the forests as are within six or seven miles of the railway come under the axe at present while virgin forests to the rear remain practically unexploited. It is only in the course of the past sixteen months that the firewood industry has developed...

Jan 1, 1901

By F Farías, D Villa

Codelco’s Salvador Project has been operating a block/panel caving mine for more than 50 years. This underground mining method dynamically mixes the ore and dilution. As a result, forecasting grades is difficult and achieving 100 per cent extraction of the reserves is practically impossible. A substantial volume of the ore mixed with dilution becomes remnant ore and remains to be subsequently extracted.A potential open pit mine is under evaluation at Codelco’s Salvador Project, which includes the extraction of remnant ore post-block caving extraction. An effective methodology has been implemented to estimate what is left behind once the underground mine has closed. A new mixing method using the Cellular Automata (Alfaro and Saavedra, 2004) approach has been used to allow estimation of the remnant ore with a sufficient level of confidence to be included as part of the open pit reserve.A remnant block model is created using elements such as in situ block model, drawpoint layouts, historical production records and the drawpoint extraction. Using this information, simulations of the extraction of the mine by month from 1959 to 2019 were completed, using different mixing scenarios and trying to replicate the tonnage and grade extracted.Finally, the remnant block model is categorised using a score card with four inputs to assess the risk of the estimation of this material into a category class (measured, indicated and inferred).CITATION:Villa, D and Farías, F, 2016. Remnant ore model generation and categorisation post-block caving extraction at Salvador Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 461–470 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By H North, J Barringer, S McNeill, D Pairman

Models of ground surface elevation, slope, aspect, curvature, roughness, deformation, as well as other features are gathered together in the term Digital Terrain Model (DTM). DTMs can be generated from a wide range of technologies such as ground surveying, aerial and satellite imagery, including both active and passive sensors. Some elevation derived parameters, such as roughness and slope, can be measured directly using innovative active sensor technology and smart processing, rather than via traditional processing of elevation information. Such models are used as part of a visual interpretation process, and increasingly for computer-assisted analysis using visualisation technology. There is an ever-increasing demand for DTM information to be used in the mineral exploration and mining industry, and consistent pressure from industry to develop models of higher spatial resolution, higher accuracy, and better overall reliability, regardless of the world-wide location of interest. This presentation will survey the range of techniques available for DTM generation, including active (LIDAR, SAR interferometry and differential interferometry) and passive (optical or SAR stereo) methods, as well as interpolation methods (contour or structure interpolation), and the economic placement of these various techniques in the local and regional context. The research issue oftrue-ground elevation models and slopes is also addressed, using LIDAR and SAR polarimetry as signpost technologies. Particular emphasis will be given to the strengths and limitations of new data sources that will, over the next few years, make the acquisition of elevation models of remote regions of the world inexpensive and relatively accurate.

Jan 1, 2000

Experiments in the bolting of a mine roof were commenced at Elrington Colliery on the South Maitland Coal Field early in 1949, following the appearance of an article in the American publication, "Coal Mine Modernisation Year Book" 1948. Prior to this, although bolting had not been used in the maintenance of satisfactory roof conditions, the principle of roof bolt anchorage had been illustrated in instances such as the hanging of a trolley locomotive power wire using an expanding shell type of bolt anchorage, or the insertion of an eye bolt with a split and wedge, as used to suspend a rope block over a winze being sunk in a metalliferous mine.The experiments at Elrington Colliery were the first efforts in this country to supplement the work of timber supports under a mine roof with systematic placement of roof bolts.Following the series of experiments at Elrington, full scale bolting was commenced at that Colliery in a trackless mobile section in April, 1950.The obvious success of the system at Elrington indicated that it might also be a success in the support of weak roof strata immediately overlying the workable section of the Victoria Tunnel Seam at John Darling Colliery.The system was commenced at John Darling Colliery in April, 1951, in one mechanical section on the Victoria Tunnel Seam, and the scope was gradually widened until by December, 1952, ail'six mechanical units then operating on this seam were working under bolted roofs.

Jan 1, 1954

In addressing the need for non-degree tertiary training, let us examine some recent reviews of engineering and geoscience education. The Finniston Report (1) criticised the formation of engineers in the UK and stated that this was largely due to the narrow British conception of engineering as a branch of applied science which militates against an effective marriage between theory and application. It also criticised the system for not giving students sufficient grounding in the synthesis of technical, human and financial considerations within their undergraduate courses. As we all know, this report has led to the restructuring of engineering education in the UK. More recently, a Review of the Discipline of Engineering was carried out in Australia by a committee chaired by Professor Sir Bruce Williams (2). The report stated that: Australia has a fairly good system of engineering education that should be made better. more should be done to develop the communication skills of both staff and students. more attention should be paid to changes in engineering practice and the human element in technology. there is a serious shortage of state of the art equipment in most engineering schools. female enrolments in engineering courses should be increased from the current level of about 7% to 20% by 1997. employers should develop a better understanding of the need for continuing education. staff in engineering schools should develop closer relations with employers of engineers. higher education institutions with engineering schools should give financial and other inducements to staff to increase the proportion of study leave or professional development leave spent working as engineers in the business sector. there is considerable room for improvements in the teaching process and in the development of evaluation schemes for assessing the teaching contributions of staff. In its recent report to the Council of the Institution of Engineers, Australia, the Task Force on Engineering Education(3) makes the following points: managerial, entrepreneurial, professional and interpersonal skills should be introduced and integrated into the undergraduate courses but studied in depth as part of continuing education. the continuing education policy of the Institution should be promoted and strengthened with all engineers required to pursue continuing education. the Institution should develop a comprehensive guide to continuing education available from universities, colleges and other public and private sector organisations.

Jan 1, 1989

By P Paredes, T Leaño, D Gajardo, C Tramón, S Peñaloza

The definition of an ore handling system and its consequent layout design is of crucial importance in cave mining projects. It not only represents the main driver in the production capacity and reliability of the mining system, it is also a fundamental variable in the footprint’s development time and cost.In recent decades, load-haul-dump (LHD) tramming distance optimisation through the allocation of several orepasses inside the footprint has been the most common practice in ore handling system layout definition at Codelco’s operations. Today, the improvement of existing technology, such as higher-capacity LHDs and jaw-gyratory crushers, and intensive preconditioning techniques to improve fragmentation allow the conceptualisation of simple and highly productive ore handling system layouts for wide caving areas that avoid the complexity and high cost of developing numerous orepasses inside the footprint.The initial macroblocks of the Chuquicamata underground mine project (PMCHS) consider an ore handling system layout in which LHDs dump into orepasses located inside the footprint area. The ore is then transferred into crusher chambers located below the production level, where it is crushed by jaw crushers and then conveyed to surface. In an effort to reduce development time and costs, a new ore handling system layout for the PMCHS experimental macroblocks was engineered using improved technologies and techniques in a simpler mining system. This paper compares the new ore handling system layout for the project’s experimental macroblocks with the traditional LHD-orepass layout in terms of production capacity, reliability, development time and cost.CITATION:Paredes, P, Gajardo, D, Leaño, T, Peñaloza, S and Tramón, C, 2016. Simplifying the ore handling system through the use of current technology at Chuquicamata underground mine project, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 571–584 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By M Dickie

During the 1980s and early 1990s low cost gold treatment plants were at the forefront of the Australian engineering and mineral processing business. This opportunity was the result of a high gold price and innovative design by emerging engineering companies in an expanding market. The low cost approach to gold plant design and project execution resulted in smaller and shorter life projects becoming viable and the multiplicity and fast track approach of the projects resulted in sharp learning curves. From the mid 1990s to the early 2000s the relatively low commodity prices and resultant reduction in minerals opportunities also resulted in innovative design in both small and large plants, albeit on a reduced scale. The innovation was associated with alleviating capital cost pressures for large capacity low-grade (eg NewcrestÆs Cadia) or small-scale (eg JubileeÆs Cosmos) projects to either improve NPV or to enable the project to be won and profitable in the competitive lump sum environment. Between 2004 and 2008 the engineering market became less competitive from an engineerÆs perspective due to the high demand for engineering services in a high price commodity market. The need for innovation remained but was driven overtly by shortages in water, power and personnel and long equipment lead times. This paper discusses some of the factors that contribute to the capital cost of a project and the scope for improving the likelihood of financing and increasing the project net present value (NPV). Case studies with recent large copper concentrator projects will be used to demonstrate how a value driven approach to project and plant layout can result in significant improvement in NPV.

Jan 1, 2009

By G R. Mould

The paper presents a general background to the subsidence research program being undertaken by the Department of Mineral Resources and Development in New South Wales. The results of the studies undertaken over the last ten years are summarised. The differences between these results and those obtained by the National Coal Board are discussed. The results of a study carried out on the effect of total extraction beneath a freeway in the southern coalfields are discussed in some detail. The procedures developed for the construction of a 500 mm diameter natural gas pipeline crossing a number of collieries in the northern coalfields are also outlined. The future direction of the Department's subsidence research program is discussed.

Jan 1, 1980

By W B. Edgar, I M. Platten, C A. J Towsey, B W. Cuffley

The evaluation of historical goldfields has been common over the past 15 years, reflecting changing economic conditions, improvements in knowledge and technology and lack of greenfield sites. Many goldfields comprise narrow gold-quartz veins, which are structurally complex with an irregular distribution of gold, have variable geometry and architecture and display late deformational effects. The study of historical mine records can be an important tool during early and advanced project evaluation, since it contributes to understanding the orebody, exploration target size and setting expectations. Mine records include documents such as plans, sections, reports, news cuttings, production tabulations, etc. A major advantage for the modern explorer is the capability of computer modelling to display this data in 3D. Historical records can give the explorer substantial information on various deposit characteristics, not least grade and geological continuity, geometry and architecture, mineralogy, metallurgical properties, bulk density and ground conditions. From an evaluation perspective, historical records can be used to support a Mineral Resource estimate, though its application will depend upon the quality and quantity of the data and judgement of the Competent Person. Effectively used, historical records can reduce geological uncertainty and focus evaluation efforts û thus reducing project risk.

Jan 1, 2009

It is a great honour to address our Institute as President, but the choice of a suitable subject was not an easy one. In the past when the presidential address was given at an annual conference the subject usually related to the conference or industry concerned; more recently the subjects have been more philosophical and this is a distinct advantage to me.I appreciate that I am addressing an informed audience and I am sure' that you are well advised in many of the points that I hope to leave with you. Unlike the specialist who gets to know more and more about less and less and eventually knows everything about nothing, I am one of the group who gets to know less and less about more and more and eventually knows nothing about everything.I hope you will appreciate this point whilst you are listening to me.In recent years I have been closely associated with the problem that troubles most governments of our time: the competition of many groups of differing backgrounds for the land that is available to the nation.This is of particular interest to the industry with which we are concerned as it is of critical importance to the discovery and development of future reserves of minerals and metals. Part of my daily task is involved with the administration of legislation for mining operations and the conditions under which such operations may be undertaken, in implementing government policies relating to mining, and in designing and administering legislationdirected to safety and health in mines.Most of our members are involved in exploration or in day-to-day problems associated with the production of minerals or the management of companies in these pursuits and would be aware of many of the conflicting viewpoints on priorities.F. F. Espie in his presidential address of 1975 'On being a minority', made the point that our Institute found that the mining industry had a great communication 'Problem with the Australian people.I believe that this is one of our major problems.

Jan 1, 1977

Kudremukh Iron Ore Company Ltd, a wholly owned Government of India Enterprise, was established in the year 1976 to develop mine and plant facilities to produce 7.5 Mtpa of high-grade iron ore concentrate at Kudremukh. The mine and plant facilities were commissioned in 1980. In view of high demand for iron oxide pellets in iron and steel industry worldwide and as a diversification activity, a pelletisation plant of 3.0 Mtpa capacity was commissioned in the year 1987 at Mangalore for production of high-quality blast furnace and direct reduction grade pellets for export. The pellet plant capacity has been increased to 3.5 Mtpa by technological improvement which included installation of roll press for quality and productivity improvement. In addition, the pellet capacity is being increased to 4 Mtpa by the addition of Shaft Pelletising Furnace plant.

Jan 1, 1999

Concentrations of bright green material in the "Golden Mile" of Kalgoorlie, which carry particularly high gold values, are known locally as "green leader".This assemblage consists largely of quartz, sericitic muscovite, carbonates, and pyrite. Some of the sericitic muscovite contains vanadium, giving the rock its green colour. Vanadium oxides, including nolanite, are also present. Tellurides identified in this study are calaverite, altaite, petzite, melonite, and coloradoite. Native gold was found in most of the samples; some of the gold, at least, has been formed from the decomposition of gold tellurides.It is suggested that mineralizing solutions carrying gold and tellurium leached vanadium from the host rocks and subsequently deposited gold tellurides and vanadium-bearing minerals in the "green leader".

Jan 1, 1977

Silica reacts with cryolite at 1010°C in two stages. The first stage is the formation of a sodium aluminosilicate of composition consistent with the mineral jadeite (Na20.AI20s.4Si02). The formation proceeds by atleast two different reactions. Formation of alumina or an aluminosilicate proceeds to its limiting value in the first 30 min while the formation of jadeite proceeds at a steady rate until quantitative conversion is achieved after 150 min. The net overall reaction can be expressed by the equation 6 Si02+2 Na3AlF6? (Na20.AI20s.4Si02) +2 SiF4 +4NaF.The second stage involves a slow reaction that proceeds with the evolution of a little SiF4, The net result is the formation of sodium aluminosilicates that are soluble in 30 per cent AlCIs-HCI solutions. While this could be explained by disproportionation of jadeite to form albite (Na20.Al203.6Si02) and nepheline (Na20. AI203.2Si02), it is more likely that it is due to further but limited reaction between the oxides and fiuoroaluminates.

Jan 1, 1972

A Good Product Range - So What! While in terms of water, waste management and environment protectrion, the Gippsland Basin may appear to have a good product range, what does this really mean? What it means is that, like any product range, the virtues of the product range must be sold and accepted by a majority of the public. The social, economic and environmental benefits of any enterprise using these products must be sold and accepted by the regional population. Many a budding entrepreneur has failed because he assumed that the public would accept his product, so good did it appear to be! However, we know that such an assumption must be avoided and that a great deal of time and effort needs to be invested in promoting and gaining acceptance of a product to ensure a long term and viable market.

Jan 1, 1992

Reconnaissance geochemical exploration in the vicinity of low angle detachment faults which bound the core of the Paparoa metamorphic core complex yielded Au up to 14 ppm, with 35% of greywacke, granitoid and quartz vein samples in the northern range exceeding the 0.01 ppm detection limit. Au is associated with Ag, As, Sb and Cu anomalies consistent with epithermal-type mineralisation. The Ag and Cu anomalies also distinguish this mineralisation from older, mesothermal Au deposits widespread in the Ordovician 'slate belt' greywackes, which comprise much of the upper plate of the core complex. Baryte, molybdenite, fluorite and stratiform U mineralisation in the northernPaparoa Range may also be related to hydrothermal activity along the detachment fault zones.

Jan 1, 1995

By Burns K. L

Keyboard patterns of hundreds of minor faults with vertical displacements of 3 mm to 2 m occur within the Greta coal seam and cause serious mining problems in collieries. Many of the faults are concentrated in linear zones termed swarms. One swarm is 600 m wide and more than 800 m long and others are of comparable size.The minor faults between the swarms are normal and are relatively widely spaced and show dip-slip movements, but the faults within a swarm are clustered and show strike-slip and oblique-slip movements. Fault swarms ofthis size and frequency have not previously been described from the Sydney Basin or on a comparable scale elsewhere but appear to be a widespread phenomenon in Australian coalfields. The faults are assigned to classes onthe basis of orientation which are then assigned to sequential phases I to IV on the basis of offsetting relations between representatives of each class. Phase I faults are minor thrusts. Phase IT, Ill, and IV faults are concentratedin the swarms and show sinistral strike-slip and normal dip-slip movements. The interference of slickenlines indicates that multiple movements have occurred within a single phase; their order is (i) strike slip (ii) dip slip and (iii) oblique slip. All faults truncate and post-date both cleat and sedimentary "stone" dykes.Phase I minor thrusts trend at a high angle to the Hunter Thrust and are considered to predate the Late Permian movements on the Hunter Thrust. Phase II and III minor faults are younger and may be any age between the latePermian and Tertiary.

Jan 1, 1978

By E K. Leeka

Process control limitations have led to suboptimal performance of the crushing section of Sishen MineÆs Jig Plant. The performance of the PID (proportional-integral-derivative) controller implemented during commissioning was hampered by the relatively small buffer capacity between the crushers and screens. The inability to maintain the tertiary crushing chamber under full choke conditions lead to inefficient crushing and reduced crusher product cubicity.Model predictive control (MPC) was implemented in the tertiary crusher plant in May 2012 and resulted in a throughput improvement of six per cent in its first month. The controller was further optimised and indicated a throughput improvement of 16 per cent during on/off testing in July 2012. The throughput improvement is attributable to the finer crusher product resulting from operating the crusher under full choke conditions and controlled feed rate to the tertiary crusher plant screens. The next step is to couple the model predictive controller, automated gap control system and an economic optimiser to ensure maximised throughput and value from the resource.CITATION:Leeka, E K, 2013. Performance of model predictive control on the crushing circuit at Sishen Mine, in Proceedings Iron Ore 2013 , pp 417-420 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013