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Bougainville Copper Limited (BCL) ships about 600,000 dry tonnes of copper concentrate per annum to Japan, Germany and Spain, with some spot sales to other countries. Concentrate sales value for 1984 was 335 million US$, representing almost half of PNG exports. Contained metal determination is based on physical and chemical measurements on representative samples. The entire procedure is subject to statistical uncertainties and possible systematic errors; losses as high as several percent of contained copper or gold are common and frequently are regarded as unavoidable. In this context, the function of the chemical laboratory is to identify and eliminate such errors and recommend correct technical procedures for possible inclusion in sales contracts. BCL's marketing management has encouraged this approach and the close buyer versus seller agreement is beneficial for all parties involved. BCL participates in the respective technical committees of the Standards Association of Australia (SAA) and the International Standards Organisation (ISO). Standard methods for sampling and analysis of copper, lead and zinc ores and concentrates are in course of preparation, some being due for publication shortly.

Jan 1, 1986

The concept of "profit" is implicit in the definition of an ore reserve. It is suggested that the flexible concept "economic" is more appropriate. This allows different economic considerations to be taken to account when determining what is ore at the feasibility study stage; during actual mining production; before mine closure; and from the viewpoint of the national economy. Economic factors which are highly variable, and largely beyond a mining enterprise's control, affect the economic exploitation of a mineral resource. Major economic factors include: metal prices; operating costs; the cost of original and replacement capital equipment; the cost of capital; taxation and royalties; inflation; exchange rates and the state of the world economy. The paper suggests why a careful quantification of the average value, trend, and variation from the trend of major economic factors should be made and how this will lead to a better definition of ore reserves. The paper also discusses the necessity of reappraising economic factors during the life of a mine in order to maximise the economic surplus and to minimise the wastage of natural, economic and human resources employed in mining.

Jan 1, 1979

Differences in the assay results of replicate samples engender doubts on the reliability of ore sampling and of assaying procedures. An analysis of variance is a technique to estimate the variability at each level of the procedures. In an example, the variability of one-metre core samples was far greater than that of the assaying technique.

Jan 1, 1976

Due to collapsing copper prices during 1974/75, a rapid changeover was made at the C.S.A. mine from mechanised cut and fill stoping with incline access to the more economic long hole open stoping method. In 1974/75, 20 per cent of total production came from open stopes. For the 1976/77 year-to- date, more than 80 per cent of total production has been won from open stopes. As a result, mining performance has improved considerably. Stops, drilling performance has increased by more than 50 per cent since the changeover from extension rod, 50 mm diameter cut and fill uphole drilling to 115 mm diameter in-the-hole hammer drilling of holes up to 65 m long. Stops blasting performance has improved from 750 tonnes to 950 tonnes blasted per manshift. Open stope primary blasting per- formance is much higher, but reduces to 950 tonnes per manshift when secondary blasting and firing of hung drawpoints are taken into consideration. Ground control, the most expensive and least productive aspect of cut and fill mining, is almost entirely eliminated in long hole open stoping.

Jan 1, 1977

Australasian mining companies expect a high standard of professionalism from their metals exploration teams. They also have, increasingly, a global perspective, employing explorationists of diverse cultural backgrounds and operating in diverse environments. Human resource development (HRD) of these professional explorationists needs to address all personal facets of functioning independently and interdependently in a modem working culture, as well as the needed technical competency. Creation of a learning organisation to promote this development is critical. Organisational consultants can support managers and supervisors as mentors facing the wide spectrum of development required by the explorationists; mentorship and guidance counselling can then complement training in the maturing of professionals from technical competence to professional independence and interdependence. Empowerment and clearly stated expectations are keys by which professionals can learn efficiently and effectively.

Jan 1, 1996

In the past two decades the global metalliferous mineral industry has trended away from pyrometallurgical (pyromet) and towards hydrometallurgical (hydromet) technologies including biometallurgical (biomet) processes. Pyromet, biomet and hydromet technologies have all developed considerably over this period. New projects have been biased or directed by legislation towards supposedly cleaner and greener hydromet and biomet technologies. The environmental cost and energy cost of pyromet production processes for copper and cobalt are compared with comparable hydromet processes using Life Cycle Assessment (LCA). The æreal costÆ of the global warming obsession and negative public perception of pyrometallurgy include greater carbon dioxide emissions and energy consumption per unit, associated with current hydromet technologies. Specific examples for copper and cobalt produced via the different routes are provided. The poor science involved with the global warming hypothesis is discussed. The use of LCA with sensitivity analysis as a decision making tool for mineral processing projects and technology developers is discussed.

Jan 1, 2004

The techniques used in evaluating gold placers and in recovering gold therefrom are briefly reviewed and critically assessed, relative to the estimated and actual recoveries from many operations. The discrepancies between these quantities can be significant and sometimes disturbing. The coefficient of variation for the annual percentage recoveries, relative to the estimates, is in excess of 10 and commonly above 20 . The difficult- ies in evaluating placers are recogni- sed both in the gathering of meaning- ful sample data and in the derivation of estimates. There are deficiencies, perhaps insurmountable at reasonable cost, in the techniques used to derive an estimate and in the gold saving devices usually employed. There is a subconscious trend to use recovery as a check on the estimate. The industry could have extracted more information during the evaluation and working of deposits in order to fully characterise them and in order to quantify metallurgical efficiency. There is a place for other prospecting techniques, particularly geophysical, in placer evaluation and a need for more appropriate and sophisticated

Jan 1, 1976

By S Vianna

Mineralogical information obtained from plant surveys is subject to errors, both due to sampling and experiment. To reduce these errors, and to ensure that information is consistent, a data reconciliation model has been developed for mineralogical data. Its capability includes mass balancing size data, total assays, assays within size-classes and liberation data. Unlike any other mass balance package, this package also allows reconciliation of the complex mineralogical information. For example, particles cannot simply be treated as binary, but consist of combinations of many minerals. Hence the distribution of mineralogical information is multidimensional and the mineralogical distributions are referred to as multiphase. In this paper, the different levels of mass balancing are explained, including how to mass balance liberation data. Furthermore a new technique based on probability theory can be used to infer distributions even when there is insufficient information to perform a mass balance, and this technique is also explained. Results for various stages are given.

Jan 1, 2002

Increasingly, mineral operations need to manage water as a key business asset. Managing water solely as an environmental issue leaves a business exposed to social, cultural and economic risks associated with water. Adopting a company-wide strategic approach, which takes account of the true value of water will provide businesses with opportunities and risk protection. Rio Tinto has recognised the business imperative for water stewardship and has responded by producing the Rio Tinto Water Strategy. This strategy commits the company to managing water assets in a responsible manner, taking account of environmental, social and economic values. To incorporate the true value of water in site decision making, a new set of tools is required at the operational level. A key part of the strategy focuses on developing a framework to value water based on case study examples from around the Group. This paper presents progress on the companyÆs experiences in developing and implementing the water strategy.

Jan 1, 2006

Pajingo Gold Mine Pty. Ltd. is a subsidiary of its United States of America parent the Battle Mountain Gold Company. Battle Mountain Gold Company was created in August 1985 as a spin-off of the United States of America Pennzoil Company's gold interests.Pajingo Gold Mine Pty. Ltd. currently has its headquarters and base for operations located in Townsville, Queensland. The Company's main current activities are the exploration and evaluation of the Pajingo Gold Property situated some 50 kilometres south-east of Charters Towers and in the northern Drummond Basin.The discovery of the Pajingo gold mineralisation by the Company was the indirect result of a regional program established to evaluate Carboniferous age volcanic plugs in north Queensland for gold mineralisation.

Jan 1, 1986

By P Heppner, J Schell, R Newell

The effect of various methods of conditioning on subsequent flotation performance was reviewed, where complex interactions involving attrition, aggregation, dispersion and surface cleaning were discussed. The present study focussed on the influences of standard laboratory cell conditioning, ultrasonic dispersion and high intensity conditioning on copper mineral flotation characteristics. The effect of substituting demineralised water for the WMC plant water was also examined. It was found that higher copper concentrate grades were often obtained using demineralised water, however the use of high intensity conditioning in mill water gave the highest copper recovery and highest flotation rate constant. This process should be considered if copper grade and recovery in this section of the plant drops, especially if the drop is due to surface oxidation of the copper minerals. Other methods of conditioning (cell and ultrasonic techniques) improved the rate of copper flotation above that obtained in the virtual absence of conditioning, showing the importance of conditioning on subsequent flotation operations.

Jan 1, 2000

The recommissioning of the plant at Mary Kathleen involved several distinct phases. The previous plant process was modified significantly, the plant capacity was increased by the addition of new equipment and the exist- ing equipment was in most cases overhauled. This equipment was either reused in its original duty or relocated. Maintenance requirements after the plant was cmommissioned were high because of the amount of modified equipment and also because some old items of equipment were deliberately not overhauled during recommissioning. The equipment that was overhauled has operated reliably. However some new equipment has not been as satisfactory.

Jan 1, 1978

By McKee DJ

Many workers have observed an inverse relationship between final concentrate grade and valuable component recovery achieved by a flotation circuit, i.e. an increase in either grade or recovery may only be achieved at the expense of the other. The relationship is termed a "grade-recovery" curve and, in theory, limits the separation obtained by the circuit. However, circuit surveys in a nickel concentrator indicate that the operating "grade-recovery" curve of a circuit is not only determined by the nature of the ore and the circuit operating conditions, but also by the circuit design, particularly in terms of stage capacities. The surveys show that different capacity circuits can produce different operating curves for the same ore, and that capacity reallocation between stages has the potential to improve both grade and recovery. In particular, the relationship between circuit design and operating curve position is shown to be a function of the circulating loads generated by the circuit design, balancing the beneficial effects of recycling material against the proportion of plant capacity consumed by recycling.

Jan 1, 1986

In simple terms, heap leaching means the removal in solution of valuable elements from a heap of material, and their recovery from that solution. The heap of material can consist of essentially unprocessed ore, sub-ore, low grade gangue and country rock, tailings from other upgrading processes, or artificial materials such as slags or furnace and flue products. The solvents can be solutions of acids (commonly sulphuric acid because of cost) or of other chemicals such as cyanides. Because of cost factors the solutions are aqueous; because of this, leaching operations may be curtailed in cold-climate areas. The guiding principle must surely be `large volume / low cost'. Since solutions are generally easier to manage than gases, there is a strong incentive for replacing roasting of materials by leaching, eg arsenical gold ores. Where sulphides are present in the material to be leached, these may provide the necessary acid, with or without the aid of bacteria, to dissolve and extract the recoverable metals. The mineralogical aspects of the operation relate to the nature of the `ore' and gangue minerals present in the heap, their textural relationships, and their effect on the process itself.

Jan 1, 1994

The paper sets out the context for water and the challenges that have to be faced in the battle to alleviate global poverty. It acknowledges that the world has been blessed with abundant water but because of population and development pressures, and the projected changes in climate, avoiding serious water shortages in some places will be difficult. MiningÆs use of water is placed in context and the paper then considers the specific threats to the industry in terms of availability and price and the need to find mechanisms to deal with the issue of resource degradation caused by abandoned mines. Rio TintoÆs use of water is then set out and three examples are given of how different water challenges have been addressed. The paper goes on to consider each element of a water strategy designed to move Rio TintoÆs performance towards excellence. This strategy incorporates improved management procedures (policy, principles, standards and targets), performance enhancement (through use of the Rio Tinto Water diagnostic and technology changes) and working with others in the academic and NGO community who seek to address the same global issue.

Jan 1, 2003

By Robson L. C

The developing countries whether they be in Africa, Asia or the Pacific, are a potentially vast market for the technologies of the more developed countries.Conducting business in the less developed countries however requires a keen understanding of their culture. A keystone of the culture of the Pacific Island Nations is kinship with the land. Without an appreciation of the implications of the land rights debate, a business venture into these countries is likely to be delayed or even doomed to failure.The European heritage, with its notions of private ownership of land, have frequently been a stumbling block to a proper understanding of the concepts of customary lands. According to our laws, ownership of land confers a number of definite rights: principally the right to use the land, the right to exclude others from its use, the right to transfer it and the right to receivF income from the property independent of use.

Jan 1, 1990

By Baker EM

The Kidston orebody is a kilometre diameter breccia pipe of Permo-Carboniferous age' assoc- iated with rhyolitic dykes and hosted by Proterozoic granodiorite and metamorphic rocks. Mineralization and alteration are associated spatially and temporally with brecciation and rhyolite intrusion. Three stages of alteration have been recognized: pre-brecciation, and early and late stage post-brecciation. Gold is known to be particularly associated with late stage post-brecciation cavity infill and sheeted veins. Fluid inclusion and stable isotope results show the importance of moderate-high temperat- ure, saline, magmatic fluids in the early stage mineralization and in the brecciation of the pipe. Later periods of alteration, accompanied by gold deposition, are associated with fluids only slightly depleted in 180 relative to mag- matic waters, unlike the strongly 180-depleted meteoric water typically found in hydrothermal Permian and Carboniferous deposits of eastern Australia. The 5180 values and low salinities in fluid inclusions suggest the fluid may have formed from vapour condensation from a magmatic fluid. Fluid inclusion data and alteration assemblages define the prevailing chemical conditions. Gold transport under these, conditions would have been primarily as a bisulfide complex.

Jan 1, 1987

By Richards AG

The stimulus of major capital expenditure in establishing open cut coal mining operations in the Hunter Valley led Coal & Allied Industries to look to a computer based information system as a tool to assist mine management in day to day operating decisions, as well as to provide a base of comparative data to help in long term equipment procurement decisions. The mine information system was conceived as an integrated set of three subsystems; costing, production recording, and maintenance. The maintenance management features of the system are closely keyed to a policy of preventive maintenance and maintenance costing based on user specified parameters. Central to this policy is the maintenance work order, which may be created and updated directly via interactive procedures at visual display terminals. The, system was designed for on-line processing in a multi-mine shared operating environment. Each mine controls its own data capture, and most other processing functions directly from terminals. The system is currently operational on the Combined Group Services Pty Ltd FACOM M150 computer, located in Newcastle, NSW.

Jan 1, 1983

A wide range of models are available to computer process simulators that require a large number of parameters which often are physical measurements, coefficients, calibration factors and functional forms. This makes it intuitively difficult in the majority of cases, to tune the parameters in order to simulate a circuit in agreement with experimental results. Unit calibrators operating on the principle of least squares minimisation of the difference between predicted and observed plant data, are relatively successful when the parameters are unconstrained and independent of each other. In the case of constrained parameters, a set of carefully chosen transforms is presented which map the unconstrained variables being minimised into the constrained parameters required for the model. This technique has been used successfully with the Powell minimisation algorithm and it may also be applied to other unconstrained minimisation methods. Necessary model characteristics are discussed to enable these transforms to be applied to interdependent model parameters such as points of a graph. Examples of the calibration of several unit models using these transforms are presented. KEYWORDS: Calibration, optimisation, transforms, process simulation.

Jan 1, 1993

By Madgwick J

A novel method for determining viable cells of the mineral leaching bacterium Thiobacillus ferrooxidans has been developed. The cells were collected on 0.45/Lm cellulose acetate filters, washed with artificial minewater, and incubated in the presence of ferrous ion at pH3 in an atmosphere containing radioactive (14C) carbon dioxide. Colonies of bacterial growth were detected by the image formed on X-ray photographic paper (autoradiography). The method was compared with three conventional techniques and shown to detect three orders of magnitude more cells in cultures of Thiobacillus ferrooxidans in the late exponential phase of growth.

Jan 1, 1987