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By I M. Platten, Y Xie

Narrow vein gold mineralisation generally contains both fine (<100 ¦m) and coarse (>100 ¦m) gold particles. The in situ size and shape, deportment, distribution and abundance of the particles controls deposit sampling characteristics, grade distribution and metallurgical properties. Particles can range from individual disseminated grains, clusters of particles and masses above 1 cm in size. At each end of the coarse-gold to fine-gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated gold particles, through to extremely difficult for very coarse particles. Deposits generally show a background grade of mineralisation dominated by disseminated fine gold particles. Drilling will resolve the background grade well, though is likely to considerably understate the grade related to the coarser gold particles. Gold mineralogy has a significant impact on metallurgy, with key factors affecting recovery being particle size, deportment, liberation parameters and silver content of gold minerals. For coarse gold particles the focus should be on liberation and the early removal of the particles from the mill circuit by gravity concentrators and gold traps. Finer particles will require more grinding to liberate prior to flotation or cyanide extraction. The determination of gold particle sizing is thus required to minimise evaluation and geometallurgical uncertainty and lower project risk.

Jan 1, 2008

It should be noted that with the passage of time all aspects of the mineral extraction process are becoming more sophisticated and complex. In order to deal with this, the education system should be geared to this continual technological advance.A new scheme is designed to attract high quality school leaven to take up courses serving the mineral industry. After graduation these students will play an important role in the areas of research and development which is essential for the growth of the Australian mining industry.

Jan 1, 1991

The Australian Mineral Industries Research Association, set up by the mineral industry in 1959, acts as a research and development broker and manager for the industry. In 1984/85 it contracted out just over $3 million of projects. Its structure and method of operation is described and highlights of some of the successful projects are given. The complex process of developing new proposals is described. This involves the establishment of effective communication networks within the industry and between the industry and research personnel working outside it. The advantages of the industry tackling some of its problems on a jointly sponsored basis are listed. Possible avenues for future development by the Association are given.

Jan 1, 1986

By H Catchpole, L FontbotT, J PTrez, M Ageneau, A Bendez·

In the world-class mining district of Morococha, epithermal polymetallic replacement bodies and veins overprint porphyry mineralisation and skarns related to subvolcanic intrusions of Miocene age, thus indicating ore formation in two different environments, separated in time or forming a continuum. The district covers an area of about 70 km2 in the north-western part of the Domo de Yauli complex in theWestern Cordillera of central Peru and is part of the Miocene polymetallic belt, also hosting the deposits of Colquijirca (Bendez· et al, 2008b) and Cerro de Pasco (Baumgartner, FontbotT and Vennemann, 2008). Multiple late-Miocene porphyry stocks intruded Permian, Triassic-Jurassic and late-Cretaceous sedimentary carbonate and volcano-sedimentary formations, as well as large mid-Miocene barren intrusions. Extensive field work and detailedmapping of different styles of orebodies suggest that ore formation in the area was related to the late-Miocene magmatism. Good outcrop conditions and superimposing of different mineralisation styles make Morococha an ideal location for studying ore-forming processes in a complex porphyry-related magmatic-hydrothermal system in which porphyry-to-epithermal transition occurred. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

The Lower Proterozoic metasediments of the Pine Creek Geosyncline form a chrono- stratigraphic sequence of mainly greenschist- and amphibolite-grade shallow-marine to supratidal pelites, psammites, carbonate rocks, and volcaniclastics which in places rests unconformably on Archaean basement. Granite and later dolerite intrude the sequence, and are associated with the major orogenic 1800-m.y. event which regionally metamorphosed the sediments. Most mineralisation is stratabound, and can be related at least partly to volcanic activity. Uranium mineralisation is mainly confined to particular carbonate-rich horizons near basement. Other metals are mainly in small hydrothermal deposits near intrusive granite. Specialist studies indicate that uranium was leached from its source rock, and probably carried as carbonate complexes in highly saline fluids at between 100 and 3500 C. Precipitation took place by redox reactions in breccia zones in carbonate rocks; these zones were formed by carbonate solution or diapiric movement of evaporites which preceded the carbonate. Extensive chloritisation in the ore zones suggests metasomatism by Fe- and Mg-rich fluids which may have evolved during dewatering of the evaporites. The main mineralising event took place after the 1800 m.y. metamorphism, and was probably

Jan 1, 1979

By Hamblyn S

Oakbridge, in combination with its joint venture partner, Nippon Steel of Japan, is expanding its Bulga underground and open cut mines to meet the growing demand for coal in the Asian market. Expansion works underway will see the Bulga underground mine become a world leader in underground productivity, the introduction of a high capacity dragline into the open cut mine (largest capacity dragline in NSW) as well as a major upgrade of the coal preparation plant (CPP) and coal handling facilities (CHF) to process the increased production. This paper describes the planning and implementation of this major expansion program and highlights the rationale behind some key aspects of the program.

Jan 1, 1995

By Rivers CJ

The Brolga deposit is a Ni-Co enriched laterite, formed over intensly serpentinised peridotites of the Marlborough Block. Basement lithologies at Brolga consist predominantly of serpentinised dunite, with lesser massive serpentinite shear, gabbro and harzburgite. Investigation of the deposit has defined 17 different varieties of saprolite, ferralite (limonite), and ferricrete. Different combinations of these varieties form three distinct lateritic associations, the Hard, Soft and Dyke Associations. Recognition of key textural and mineralogical features in each association, an understanding of basement geology, and an awareness of current climatic conditions, suggest that: 1. both the Hard and Soft Associations have formed under relatively dry climatic conditions; 2. the Soft Association reflects much poorer groundwater drainage than the Hard Association; and 3. the Dyke Association has formed from a gabbroic basement, and has also been affected by restricted groundwater drainage, caused by poorly permeable marginal serpentinite shears.

Jan 1, 1996

By Hayes P. C

The reduction of small, dense zinc oxide (ZnO) samples in CO/CO2, and CO/N2 gas mixtures has been investigated at temperatures between 900 and 1100¦C. The microstructural characterisation of the reacted and partially reduced samples was complemented with measurements of the rates of the reactions. The mechanisms and kinetics of reduction of zinc oxide were found to be dependent upon the CO partial pressure, the oxygen potential of the gas mixtures, temperature and degree of reduction.

Jan 1, 1991

Batterham and Algie began their paper on: `The role of technology in the minerals industry' (1995) by noting that while: it is often stated that innovation is central to the economic survival of mining and minerals processing in the face of global competition, .. . technology is often far from a core strategy in our industry. This point is correct. Throughout the world, as a broad generalisation, mining companies do not value technology development as a principal means of gaining competitive advantage. It is important to understand why this is the case. Batterham and Algie address this question by making distinctions between innovation, technology and research. They note that while: all successful (mining) companies are good at innovation . . . that innovation can proceed without any research and development and that it is innovation that generates the competitive advantage, not research and development per se. In this paper we accept these arguments. However, our focus is somewhat different. Whereas Batterham and Algie took a mining company's perspective on the technologies of mining and processing, we take a broader view of the opportunities for technology development for company Australia but, in order to focus the argument, we restrict our discussion to the area of mining (rather than processing); we focus particularly on mining systems and mining equipment. We begin by looking at the motivation of companies operating in any industrial sector to invest in research and development. Figure 1 recognises four levels of industrial maturity. For companies in the embryonic and growth stages R&D often is essential to initiating and developing the business. Mining, on the other hand, is a mature industry. In mature industries the conventional roles for R&D are to reduce costs, to extend product differentiation, or to develop new technology with the aim of rejuvenating the business. Next we ask whether these general-industry arguments apply to the mining industry. If they do then the mining industry should value R&D more highly; after all cost reductions and business rejuvenation are goals that are worth achieving. On the other hand if, for whatever reason, these general arguments do not apply to mining then this may lead the mining industry to invest only modestly, or not at all, in R&D. In this event, while this may be a rational decision for the mining industry, it may not be in the best interest of a nation like Australia where revenues from the sale of mineral products represent an important part of the country's economy.

Jan 1, 1997

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 Bruce See J

Oxidation of artificial Imperial Smelting Furnace lead bullion was performed during cooling between 1180 and 820°C in order to attempt to produce a tin-rich dross.The addition of sodium carbonate together with stirring increased the tin content of the dross when oxidation was carried out with air or PbO on zinc-free bullion.Zinc in the bullion during oxidation resulted in a decrease in tin concentration of the dross due to zinc oxidation and copper entering the dross.

Jan 1, 1987

By Williams JK, Bolitho BC

Laverton Gold NL (Laverton) is the first junior Australian mining company to establish a viable mining operation in Indonesia. It successfully commissioned the Rawas plant in Sumatra this year with an average anticipated production of 85 000 ounces of gold equivalent (as gold and silver) per year, a feat of which Laverton is justifiably proud.Working in Indonesia and South-East Asia generally is very stressful for juniors and stretches human and financial resources to the limit - more so than in medium to large companies which can absorb the workload in-house more effectively.

Jan 1, 1997

By den Drijver J

Worldwide, hard coal mining is being carried out at ever increasing depth, and has, therefore, to cope with correspondingly increasing methane emissions. About seven per cent of global methane emissions are caused by coal mining. Beside carbon dioxide, chloro-fluorocarbons (CFCs) and nitrogen oxides, methane is one of the most significant `greenhouse' gases. It is mainly through the release of such trace gases that the greenhouse effect is brought about. Reducing methane emissions is therefore an important problem to be solved by the coal mining industry. This paper begins by highlighting some of the fundamental principles of methane in hard coal mining. The methane problem in German hard coal mining and the industry's efforts to reduce methane emissions are presented. The future development in German hard coal mining is illustrated by an example which shows how large methane volumes can be managed, while still maintaining high outputs at increasing depth.

Jan 1, 1995

By Blair J. R

In the Bayer process, bauxite is leached with caustic soda, forming a solution of sodium aluminate, from which hydrated alumina is precipitated. The efficient operation of the continuous form of this process requires that the concentration of caustic soda be controlled. A computer simulation of the concentration of caustic soda has been conducted to provide information, regarding the dynamic behaviour of caustic concentration, which is not available from normal plant data. The basis of the simulation is a state- space model of an alumina refinery, linearized about the normal operating condition. The formulation of the model, with the relevant approximations and assumptions, is outlined. The simulation of the mudwash section of the. plant is described in detail. A continuous model of the mudwash, having time-varying coefficients, was driven using operating data from an alumina refinery. The modelled response showed reasonable agreement with the recorded plant response.

Jan 1, 1977

By Browner R, Kyle J

The adsorption of gold cyanide by the weak base ion exchange resins, PAZ-4¦ and Duolite A-7C, the neutral polymeric adsorbent, Amberlite XAD7¦, and the strong base resins, PAZ-8~a and IRA-400 have been studied in both low and high salinity waters, and their performance compared with activated carbon. A systematic study has also been made of the effect of different ions (Na+, Cat+, Mgt+, Cl', SO4) ) on the gold adsorption capacity and kinetics of these resins. The results indicate that, contrary to popular belief, the ion exchange resin, can perform effectively in highly saline environments. The performance of the neutral polymeric adsorbent im- proves with increasing salinity but cannot match the performance of the ion-exchange resins.

Jan 1, 1991

The planned extraction of deeper copper ore at Isa Mine has necessitated a review of existing equipment and methods to contain costs and improve working conditions. Mining is in progress for a crushing-conveying system to serve the deeper southern areas of the 1100 Orebody. This system will permit direct tipping of ore to the crushers and conveying of the crushed ore by cable belt conveyor to existing shaft loading facilities, a distance of about 2 km. To develop part of the conveyor drive a new machine will be used, the Robbins MM120 Mobile Miner, a joint development project between The Robbins Company and Mount Isa Mines Limited. The Mobile Miner uses a rotating cutting wheel to excavate headings 3.7 m high and from 4.7 m to 7.5 m wide. To ventilate the deep crusher complexes and associated development at high virgin rock temperatures, a refrigeration plant will be built on surface to reticulate chilled water underground. Bulk cooling of air to the 3000/3500 Orebodies and the southern crushers will be combined with the reticulation of chilled service water to the lower workings of the mine.

Jan 1, 1984

The interaction of man with the environment has a double character. From one side, mankind can not exist without co- nsuming the natural resources and, from the other side, we actively alter and exert influence upon nature. Analysis reveals that the ecological problem is, to a great extent, a geological one. The paper deals with the application of grouting techniques to construct impermeable barriers for the protection of ground water and soils from depletion and industrial wastes pollution. A number of case histories in the field of mine construction is given to illustrate the solution of geotechnical problems in concert with environ- mental protection measures.

Jan 1, 1988

By Kavetsky A

A new model of flotation is presented which allows predictive calculations of total solids flows and metal grades and recoveries to be made for industrial flowsheets. A method of making these calculations is presented and illustrated with examples. The problem of determining sufficient flotability characteristics from a sample of circuit feed to predict the behaviour of that specific ground ore in the flotation circuit (ie performing flotometric analysis) is addressed, and some suggestions are made for its solution. A feature of the flotation model is its practical technological orientation, allowing determination of a small number of ore flotability parameters by fitting observed batch kinetic flotation data. The unit model explicitly includes the cell aeration as total bubble area per unit pulp volume, and pulp residence time. Although more complex unit models are feasible, it is thought that this model is sufficiently realistic to illustrate the points made. The modelling approach is illustrated by application to flotation data from a Kambalda ickel circuit. The model is parameterised and ore flotability parameters are back-calculated from batch kinetic data. These parameters are then used to fit the observed behaviour of the industrial circuit by numerically adjusting the unit aerations. Finally, it is shown how the model may be used to predict the effect of circuit and ore changes on the circuit's technological indices.

Jan 1, 1992

This study begins with the semivario- gram modelling of variables rutile grade and clay content from a beach sand rutile deposit. This is followed by two dimensional block kriging. The deposit was divided into blocks of 30 x 30 x 1.5 m dimensions and the kriged estimate together with the associated kriging variances for each variable within each block were determined. Finally, using the results of the krig- ing program and considering the acceptable limit of clay content together with the cutoff grade for rutile, a method for optimization of mineable thickness and hence the tonnage of ore was applied and the results were dis- Cussed.

Jan 1, 1986

By Fraser CJ

Stability control plays a prominent part in the planning and execution of coal winning in the deep open cuts in the Latrobe Valley operated by the State Electricity Commission of Victoria (SECV). Different stability mechanisms affect the individual overburden and coal faces. These are the classical rotational slip in overburden and the three-dimensional tetra- hedral wedge or planar block slip in the coal faces. The stability of the overall batters is affected by the so-called "block sliding" mechanism, which is unique in Australian open cuts. The basal stability of the open cuts is affected by pressure from water in confined aquifers underlying the coal being excavated. This paper describes each of these mechanisms and the current monitoring and con- trol techniques practised by the SECV.

Jan 1, 1982