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By Lilly PA, Kavetsky AP

An empirical, kinematic model is developed which calculates the trajectory of individual blocks of rock in a blast, their point of impact in the muckpile and the final shape of the muckpile. The method is based on the determination of initial block velocity and requires input on stemming length, bench height, subdrill, burden, spacing, energy of explosive per unit length of blasthole, energy attenuation rate and resistance to movement. The model, which will form part of a comprehensive blast simulation package, has application in open cut mining in predicting muckpile geometry and the movement of grade blocks during blasting, which in turn impact on shovel productivity and grade control.

Jan 1, 1986

The region we call the West Coast is acknowledged as one of the richest and most diverse mineral provinces in the world. It's the most rugged part of Tasmania and our island is one of the most rugged parts of Australia, so that speaks for itself. A hostile land of razorback mountains, deep ravines, dangerous rivers, almost impenetrable rainforests and a climate that can change from mild to freezing in a matter of hours.

Jan 1, 1993

By Worner H. K

The paper briefly summarises the work of the Titanium Research Section in the Metallurgy Department of the University of Melbourne and mentions the development of a new electrolytic process for titanium production. This process utilises the "hot-spot" cathode technique and titanium carbide anodes. An introduction is given to three further papers on titanium metallurgy to be presented to the Institute.INTRODUCTIONThe unique combination of strength, lightness and corrosion resistance possessed :by titanium and its, alloy has made them of great interest to engineers. However, high cost, difficulties of production and limited knowledge of techniques of application restrict their usage at present almost exclusively to high priority armaments.The cost of the metal is divided between extraction and processing and much research has been carried out to devise new and cheaper methods for winning the metal from its ores. Processing costs will be reduced when production volume increases.Extraction research is proceeding rapidly overseas and Kellogg (1955, p. 72) reports that 'at least seventeen companies in the U.S.A. are interested in titanium production. Of these, two are producing the metal by a modified Kroll process, three are building Kroll plants and the remainder are in various stages of research activity. The Horizons Corporation alone is contemplating electrolytic extraction and is building a pilot plant. Steinberg et aI. (1955, p. 252, p. 332) have reported the early work done by the HorizonsCorporation on electrolysis of potassium fluotitanate and titanium monoxide in fused salt electrolytes. Of these two, the former appears to be the more attractive process.

Jan 1, 1956

By Pratt V, Davis K

Challenges facing middle management in the 1980's and beyond are not confined to business matters such as industrial relations, government and legal constraints, corporate takeovers, and commodity marketing. More particularly they deal with people issues and the interrelationship of corporate/ family relationships. There is a need for corporations to acknowledge the growing conflict between corporate/family roles being brought about by such matters as equal opportunity, double professional marriage partnerships, personal mobility and the increasing stress faced by managers as a result of current demands and expectations being placed on them. While the main responsibility for managing professional life as well as the relationship between professional and private life rests with the individual executive, corporations nevertheless have a major responsibility to assist these executives in this management process. Corporations in Australia are taking steps to address this situation but much more needs to be done. This was highlighted in the March 1985 "Middle Management" course with its associated Spouses Programme presented jointly by Australian Mineral Foundation and The Australian Administrative Staff College. Effective communication is at the heart of the matter but no amount of training on this subject will bear fruit unless there is an associated commitment by executives to improve the effectiveness of their communi- cation process both in their corporate and family roles.

Jan 1, 1986

By Baafi EY, Appiah HK

The Prestea Goldfields Ltd of Ghana, West Africa has produced over 170 t of gold with average grade of 11 g/t since 1912. The deposits occur in a wide shear zone which closely follow the Birimian-Tarkwaian contact. Both the Birimian and Tarkwaian systems are of Precambrian age. Underground exploration is carried out to delineate ore bodies by means of AX size diamond drilling at 50 m sampling intervals. After the orebody has been delineated, development work is carried out by exposing the gold reef. Channel sampling is then carried out at about 3 m intervals in both the stope and stope drives. A channel sample length is commonly 0.6 in, but may vary depending on physical characteristics of the reef. The values of channel samples are linearly combined to obtain the average reef or slope values and/or widths of the exposed sections. The sampling practice and methods of improving the efficacy of sampling at the mine are described.

Jan 1, 1976

By Gardner H. J, Wadsley m. W

Bauxite from the Weipa and Andoom (North Queensland) deposits was treated to provide a low-iron raw material for high- alumina refractories or aluminium chloride manufacture. The operation involved passing crushed, calcined bauxite continuously through a single laboratory shaft furnace. Consecutive sulfidation and chlorination of the iron minerals within the furnace resulted in a beneficiate containing less than 2% (wt.) Fe203 and by-product ferric chloride con- taining only traces of aluminium.

Jan 1, 1979

By Delahey G, Dunne R

At New Celebration Gold Mine the advent of treating primary sulphide ores resulted in decreased gold recoveries of four to ten per cent. The grind coarsened due to an increase in ore hardness and gold in the residue was found to be associated with pyrite. Finer grinding improved recoveries but was impractical as production rates would have decreased to unacceptable levels. An alternative approach that has proved to be viable combines both gravity separation, to recover the coarse gold bearing sulphides, and then regrinding the concentrate in a tower mill prior to releaching in the cyanide leach circuit. The tailings treatment plant was commissioned in December 1990 and details of the first 18 months' operations are Provided.

Jan 1, 1993

Expert systems are a product of Artificial Intelligence (AI), a field of long standing, dedicated to the study of problem solving using heuristics, construction of symbolic representations of knowledge about the world, communications proce

Jan 1, 1998

By Ranklin W. J

The mechanism and rate-limiting step of carbonaceous reduction of zinc from slags was investigated in the laboratory. Disks of graphite were rotated in ZnO-containing slags at various speeds for fixed periods at 1250 to 1325¦C. The mass loss was used as a measure of the amount of ZnO reduced. Application of the Levich equation indicated that at rotation speeds at which it is valid, the reduction was chemically controlled with an activation energy of 27 kcal/mol. At zero rotation speed the reduction of ZnO by carbon appeared to be slag-phase mass transfer controlled with an activation energy of 38 kcal/mol. An increase in the FeO content of the slag increased the rate of reduction while an increase in sulphur content decreased the rate of reduction. When FeO was present in the slag, reduction appeared to occur by a combination of indirect reduction of ZnO by carbon and by reduction by FeO with reduction of Fe203 back to FeO by carbon. The effect of sulphur was consistent with a surface blockage mechanism due to the surface active nature of sulphur in slags.

Jan 1, 1993

By M Barley, C A. RosiFre, L Lobato

The Carajßs iron ore deposits contain approximately 17.5 billion tons of ore with >64 per cent Fe and occur in the eastern part of the Amazonas Craton. They are hosted by jaspilitic banded iron-formation (BIF) of the Carajßs Formation which, together with metavolcanic rocks, comprise the ~2.75Ga Grpo Parß Group of the Itacai·nas Supergroup in the ~1000 km long, E-W trending Carajßs Synclinorium. The Carajas Formation comprises discontinuous layers and lenses of partly dolomitised BIF (17 - 43 per cent Fe and 35 - 61 per cent SiO2) and lenses of high-grade iron ore, cut by mafic sills and dykes. The high-grade iron ores occur as large tabular bodies of friable (soft) hematite with smaller lenses of hard (compact) hematite. The hard hematite ores typically occur at the contact with the underlying volcanic rocks and are surrounded by an aureole of hydrothermal carbonate alteration. BIF that has been overprinted by dolomite and magnetite crystallisation has recently been discovered at depth in the N4E Mine. With increasing amounts of carbonate, the original lamination (microbanding) and other fine primary structures in the BIF have been progressively obliterated resulting in alternating carbonate and iron oxide mesobands. The friable hematite ore that is characteristic of the Carajßs deposits results from ongoing weathering and leaching of the carbonates from this type of altered BIF. The hard hematite ores probably result from more extensive early oxidation. The association of both carbonate-altered and jaspilitic BIF with the N4 Mine is similar to that observed at the Mount Tom Price deposit in Western Australia, where carbonate-altered BIF occurs below massive hematite ore with a jaspilitic halo developed above the orebody. This indicates that as at Mount Tom Price, hydrothermal carbonate alteration and associated loss of silica from BIF may be an important step in the formation of these giant hematite deposits.

Jan 1, 2002

Supercritical fluids are gases compressed to near liquid densities and, as such, have unique properties compared to liquids: low viscosity; zero latent heat; high diffusivity and pressure-dependent, solvation characteristics. These properties are being utilised in new processes and current research is delineating areas where such processes may be applicable to extractive metallurgy. The processes and areas of interest are as follows: Supercritical Fluid Extraction in which substrates are dissolved at high pressure and fractionated at successively lower pressures. Areas of interest include extraction of organic materials for regeneration of activated carbon for the CIP process and for upgrading alumina industry products and, separation of transition metal chlorides. ò Supercritical Water Oxidation in which high pressure gaseous water acts as a medium in which substrates are oxidised while suspended or dissolved. This process may be of use for oxidation of organics in Bayer liquor and oxidation of mine waters etc. ò Supercritical Fluid Reactions where reactions occur in a supercritical fluid medium, particularly when the medium itself is a reactant. This may be of use in treating refractory or carbon-aqueous auriferous ores and in lower-temperature chlorination of transition metal oxides. Research is described which is aimed at chlorination and separation of transition metal oxides by two supercritical operations.

Jan 1, 1991

By Moore A. J, Evans R

Blast vibration control and assessment techniques have been developed which supplement traditional charge mass scaling methods. The improved techniques, which can be used to predict air and ground vibration levels at the planning stage, and to assist in the control of blasting operations, have reduced the level of operating risk concerning blast vibration. In addition to such factors as charge mass, distance and blast vibration levels, these additional techniques take account of orientation of the blasting face, topographic shielding, wavefront reinforcement, and meteorological conditions. They have assisted in compliance with specified blast vibration levels for environmental licence and mining lease conditions, the reduction of blast vibration nuisance to residents in the area surrounding a mine, and control of building and rock structure response in adjacent areas on the mine lease area.

Jan 1, 1994

In recent years new instrumentation and digital technology have Wrote possible a new facet of goo-physics: broadband seismology. From digitally record-ing networks and arrays. broadband scistnograrns of body waves that are flat to displacement and veloc-ity in at least the frequency range from 0.01 to 5.0 liz can now be routinely obtained for most carthquakes of magnitude greater than about 5.5. In contrast to data from conventional narrowband seismographs, broad-band body waves have sufficient spectral information to nvest,igate the many frequency-dependent eflects that may arise from source finiteness and from wave prop-agat ion phenomenon. Besides the usual parameters of depth. moment and focal mechanism, broadband data have sufficient spectral information to provide estimates of radiated energy, associated stresses and the frequency dependence of source parameters. Moreover. teleseis-mically recorded broadband data and near-field strong motion accelerograms overlap in the frequency band be-tween about 0.1-2.0 Hz. Thus. v it h broadband data it is possible to connect far field and near field data in order to make estimates of acceleration for almost any seismically active region of the circum-Pacific.

Jan 1, 1990

By K M. Watling, F M, G K. Parker

Surface enhanced Raman scattering (SERS) spectroscopy at surfaces under electrochemical control has been applied to elucidate the adsorption of thiol collectors. SERS spectroelectrochemical studies at coinage metal electrodes have been carried out on ethyl xanthate and three iso-xanthates, O-isopropyl-N-ethylthionocarbamate, 2-mercaptobenzothiazole, diisobutyl- dithiophosphinate and butylethoxycarbonylthioura. For each collector, adsorption occurs via charge transfer to form a metal-sulfur bond and, in situations for which the reversible potential of the formation of the bulk phase is known, at underpotentials.

Jan 1, 2005

By Braithwaite J. C

A brief summary is given of the applications of geochemistry on two areas in North West Nelson. It has been found to be an effective method for reconnaissance prospecting. Its particular advantage lies in areas which due to thick bush cover or ru

Jan 1, 1980

By KenGemar P, Perembo R. C B, Winn R. D

The New Guinea orogen comprises terranes that have accreted to the northern margin of the Australian craton. The history of the accretion of terranes begins earlier (in the Late Cretaceous) and is more complex than has been suggested previously. There was a collision in the central highlands in the Late Paleocene or Early Eocene, and a Finisterre collision that precedes and is distinct from the later (Pliocene) Bismarck volcanic arc collision.

Jan 1, 1997

During the past seven years silver recovery has been increased from 9 per cent to over 61 per cent. The changes in plant practiee which have led to this increase are described. Gold room clean-up procedure has been varied, so that half the additional silver is obtained as pure silver chloride, which.is converted to silver bullion for marketing.

Jan 1, 1964

By Kristiansen J

A series of laboratory blasting and ball mill grinding tests have been done on four different types of hard and competent rocks. The results show that exposing these rock types to a higher level of explosive energy will enhance their grindability. True blasting optimisation should therefore look at the whole comminution process from solid rock to a marketable product.

Jan 1, 1995

By K S. Smith, B P. Jackson, P J. Lamothe

The upper Arkansas River south of Leadville, Colorado, USA, contains deposits of fluvial tailings from historical mining operations in the Leadville area. These deposits are possible non-point sources of acid and metal contamination to surface- and ground-water systems. We used stable-metal isotopes to help ascertain metal retention and release mechanisms that influence metal transport from the deposits to shallow ground-water systems. To accomplish this, we excavated an intact core from a small fluvial tailings deposit and performed laboratory column experiments to examine the amount of metals leaching through the core. Deionised water was continuously applied to the top of the core, and effluent was collected from the bottom of the core for a period of about two months. Three saturation conditions were used, including unsaturated, partially saturated, and fully saturated. Reducing conditions developed upon partial and complete saturation of the core. During the unsaturated leaching phase, core effluents were acidic (pH 2.8 - 3.5) and contained elevated metal concentrations. During a portion of the unsaturated leaching phase, stable-metal isotope spikes and conservative tracers were simultaneously applied to the top of the core. The isotopes provide a means to delineate metal behaviour within the core. During the unsaturated leaching phase, the isotope spikes did not exhibit breakthrough with simultaneously added conservative tracers. However, some of the stable-metal isotope spikes did break through when reducing conditions occurred in the core (during the partial- and completesaturation conditions). In this paper, we use Cd as an example of the utility of stable-metal isotopes in geochemical studies. In the case of Cd, after the core was partially saturated, the 111Cd spike was released as evidenced by a change in the Cd isotope ratios in the effluent. This release continued during the fully saturated leaching phase, however, the total Cd concentration did not increase. These results suggest that the 111Cd spike was retained inside the core during the unsaturated leaching phase, and only partially released as reducing conditions developed. Results from this core-leaching experiment indicate there is a large reservoir of water-soluble material within the fluvial tailings deposit, which yields elevated metal concentrations and high acidity, and which may degrade adjacent ground- and surface-water quality. Use of stable metal isotopes in this study facilitated the determination of different metal-retention processes, metal-release processes, and metal sources in the fluvial tailings deposit in response to changing geochemical conditions.

Jan 1, 2003

Diamonds have been known in Australia for many years, especially in association with alluvial gold and tin occurrences. Exploration for primary sources in the Kimberely area of Western Australia has been carried out since 1968, culminating in the discovery, in 1979, of the Argyle Kimberlite No 1 (AK1) kimberlite pipe. Various techniques have been used in the search for diamonds such as geologic interpretation, aerial photography and Landsat, soil geochenical techniques, geophysics, and stream sediment sampling. Stream sediment sampling, a method developed in South Africa, using the detection of indicator minerals derived from kimberlites in gravel samples, has had wide application and success in Australia. Nevertheless, although Australian diamond bearing kimberlite and lamproite rocks contain some of the classic indicator minerals, their concentrations are generally much lower than in South Africa and Russia. Despite this paucity of indicators, stream sediment sampling is still the best known and most commonly used method of diamond prospecting in Australia. Small samples are treated by hand but larger samples require the use of diamond pans, jigs or heavy media separation plants. Each of these methods has advantages and disadvantages. The final concentrate is passed over a grease table or subjected to x-ray sorting.

Jan 1, 1984