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By Slechta JJ

The performance of a hydrocyclone treating fine coal has been examined over a wide range of feed and operating conditions.The results were expressed in terms of partition curves from which the water split to the oversize flowstream,the corrected separation size and reduced partition curves were determined-.The following conclusions were obtained. (a) The water split to the oversize flowstream was found to be dependent upon the vortex finder and spigot diameters of the cyclone and the flowrate and solids content of the feed slurry. (b) The corrected separation size was dependent on the solids content of the feed,and the vortex finder and spigot diameters.The hydraulic pressure (or flowrate) of the feed slurry did not have a significant effect.This phenomenon could be explained in terms of crowding of the particles at the Spigot.

Jan 1, 1984

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

By Trutwin W, Tracz J

The outbreak of open fires underground cause disturbances to the conditions of the mine ventilation process. Thermal and chemical effects due to fire create unsteady, transient states in airflow and the spread of combustion products in the mine ventilation network. Changes in airflow have an influence on the fire, constituting a sort of feed-back between the fire and the ventilation process. This paper deals with a numerical simulation method, which enables the determination of transients caused by fires. The mathematical model, of the simulation method considered, has been based upon a: simple model of combustion of fuel in the airway, unsteady exchange of heat between the fire, airflow and surrounding rocks, airflow in mine ventilation networks and the theory of heatflow in the rocks. Initial and boundary conditions allow the determination of a set of parameters describing the airflow, the propagation of combustion products, the tempera- ture of the fire and flow etc. due to the fire. The simulation method, facilitates a graphical presentation of the spread of combustion products throughout the network. The simulation method has been prepared for an IBM PC/AT Computer.

Jan 1, 1988

By Mouritz M

Ventilation characteristics and the occurrence of nocturnal surface inversions have been investigated within the Mount Whaleback open cut iron ore mine at Newman in Western Australia. When winds are light and/or nocturnal surface inversions form within the pit, episodes of atmospheric stagnation can occur with resultant accumulation of dust, diesel exhaust fumes, and sulphur dioxide evolved from spontaneous combustion of pyritic shale. Nocturnal surface inversions were recorded outside the mine on more than two-thirds of nights. Inside the pit, inversions were much less frequent - occurring on roughly 20% of nights when they were observed outside - and much weaker - the maximum temperature difference being 5 C¦ over 210 m inside the pit compared with 15 C¦ over 150 m outside.

Jan 1, 1988

By Binns RA, Murao S

The PACMANUS and Jade deposits are two active hydrothermal fields that are forming massive sulfide deposits at the Pacific rim margin. Both are associated with felsic submarine volcanic rocks and both occur in back-arc settings. However, PACMANUS is associated with almost sediment-free dacites and lies on the crest of a volcanic ridge, whereas Jade occurs in a heavily-sedimented tectonic depression associated with a basement of pumiceous rhyolite. The PACMANUS deposit is richer in Cu and Au, and Jade in Pb. Zinc, Ag, As and Sb contents are similar. Sulfide textures at PACMANUS suggest formation of Cu and Zn sulfides by simultaneous double-diffusion involving inwards-moving seawater mixing with outwards-moving hydrothermal fluid. By contrast, at Jade there is a more complex history of formation where initial growth of barite on the sediment surface, probably associated with microbial activity, formed an impervious cap which trapped higher temperature hydrothermal solutions.

Jan 1, 1995

Kidston Gold Mines Limited (70 per cent Placer Pacific and 30 per cent Public Shareholders) has been mining the Wises Hill Pit since late-1984. The Wises Hill Deposit is a large low grade gold deposit and as such is highly sensitive to economic parameters. The uniformity of the orebody has allowed a bulk mining method to be used, with minimal dilution. Total reserves defined to-date are 64 160 OOOT at a grade of 1.60 g/t gold. Mineable reserves remaining as of January 1992 are 36 357 OOOT at a grade of 1.28 g/t gold.Mining investigations to reduce the impact of lower gold prices, the effect of decreasing headgrade and increasing mining costs have focused on wall steepening.

Jan 1, 1992

By Callaghan T

The Henty Gold Mine is located approximately 30 km north of Queenstown, at the head waters of the Henty River on the west coast of Tasmania at 41¦50'S, 145¦40'E on the Queenstown (SK 55-5) 1:250 000 and Sophia (8014) 1:100 000 map sheets (Figure 1). The mine is accessed from Queenstown along the A10 Highway and Anthony's Road. The town of Queenstown is located 260 km north west of Hobart on the A10 Highway, and

Jan 1, 1997

DR. WARK, said: I have not come to Broken Hill to tell you how to conduct flotation operations; indeed, during my short stay here I have already learned much concerning the process, of the many difficulties which have been overcome, and of those still awaiting solution. My purpose to-night is rather different. All who have been concerned with the operation...

Jan 1, 1933

By Hendrix J. L, Nelson J. H

A study was conducted to examine how pretreatment of carbon-bearing gold ores with chlorine enhances gold recovery by cyanidation. It is hypothesized that metal species (including iron and copper) dissolved during chlorination adsorb on the carbon surface hindering the adsorption of dissolved gold. To test the hypothesis, samples of several sulfide minerals were subjected to reaction with sparged chlorine gas to determine which, if any, dissolve faster than gold under these conditions. Then, a synthetic carbonaceous refractory gold ore containing pyrite, chalcocite, activated carbon, and gold was subjected to gas sparging. The results of these experiments showed that chalcocite and arsenopyrite dissolve so that metal (copper and iron) is put into solution slightly faster than gold under the same chlorination conditions. Also, it was observed from the experiments that gold adsorbs on activated carbon during chlorination, but is replaced by copper and iron as the chlorination process dissolves more of the chalcocite and pyrite. The study concluded by investigating ferric chloride addition prior to chlorination to hinder gold adsorption on activated carbon.

Jan 1, 1991

Rifting and transfer faulting in the Late Cretaceous to Early Tertiary resulted in the formation of the Bundaberg Trough and Wallaville Basin and deflected the margin of the Maryborough Basin southwestward between the Kolan and Burnett Rivers. During the Cainozoic, three periods of volcanic activity occurred in the Bundaberg-Gin Gin area. The oldest of these periods, Paleocene to Early Eocene, resulted in the outpouring of tholeiitic lavas. During the Late Miocene to Pliocene, undersaturated alkali basalts generated at depths of from ca. 35 to 55 km were emplaced. These lavas were followed in the Pleistocene by the alkaline Hummock and Berrembea Basalts. The loci of eruption of all of these lavas were controlled by the intersection of the transfer fault system and pre-existing north to northwesterly trending faults in the Bundaberg-Gin Gin area.

Jan 1, 1990

By OÆBrien D, Priddle D

In order to avoid costly moisture penalties on coal shipments and to minimise rail freight costs, screen bowl centrifuges were selected and installed in the Mount Thorley Coal Preparation Plant for dewatering fine coal product. The Mount Thorley fine coal circuit consists of desliming the -0.5 mm (ww) fine coal in two stages of classifying cyclones prior to recovery by froth flotation. Provision has been made to bypass the flotation circuit with the classified flotation feed reporting directly to product and the centrifuge dewatering circuit has been designed to handle either flotation feed or flotation product. Major mechanical failures of the gearboxes and the ceramic tiling occurred early in the operation life of the machines which led to design changes being made to achieve satisfactory operation. This paper discusses the operating experience at Mount Thorley with respect to both mechanical and metallurgical performance of the screen bowl centrifuges since their installation in 1985.

Jan 1, 1989

Mining, like most other businesses, is based upon capital assets; and the primary cap- ital of any mining company is its ore reserve. A company's survival and growth is, thus, dep- endent upon its ability to replace, increase, redistribute and to diversify its ore reserves. A Kennecott executive addressing a group of geologists in 1957 stated, "Management expects a geologist to find ore! That is the primary objective and the justification of the geologist in the minerals industry. There is no other function that we can rationalize." This is, however, a restricted point of view, and one which I an sure is not fully shared by mining executives or mine operators at the present time. Ore reserves are 'made' as well as 'found' and the geologist contributes to this process. A mining geologist engages in activity in- volving the study of geology in connection with the total mining operation. His major task is the adaption of geological knowledge of ore de- posits and rock behaviour to mining needs, and the application of principles of the science of geology to specific problems of finding, develop- ing and extracting of ore bodies.

Jan 1, 1975

By J Tsiklieris, O Turner

Suppliers of products and services have a pivotal role in sustainable development in the mining and minerals industry. Reputable suppliers know their products and services, and the industry, and have unique knowledge of these in relation to their customerÆs needs. Petroleum hydrocarbon suppliers, in particular, impact upon a mineÆs sustainability because of the extensive reach of petroleum hydrocarbons into the mining and minerals life-cycle. The petroleum hydrocarbon life-cycle is a useful framework to enable engagement between supplier and customer on the issue of sustainability. The life-cycle starts with supply of fuels, lubricants and services at the mine, through to plant operation and maintenance, transport of mined products, ship loading, and finally through to mineral processing and other downstream value-adding. There are barriers to leveraging supplierÆs capabilities which have to be overcome before the industry will gain the potential benefits from such supplier engagement.

Jan 1, 2004

By S Latchireddi

Close circuiting autogenous and semi-autogenous mills is anenergy efficient way of grinding and a number of operations haveutilised this in the design of their comminution circuits. Owing tothe large flow of slurry through the mill that results fromoperating this way the grates and pulp lifters have to be designedto cope. However, the literature has little or no information onhow grate and pulp lifter size and design are related to theirability to remove slurry from the mill. Over the last few years theJKMRC has been researching this area and has developedrelationships between grate/pulp lifter design and flowratecapacity. At the same time it has determined the major causes ofpulp lifter inefficiency and a solution to preventing thisinefficiency (the Twin Chamber Pulp Lifter). This paperdescribes the models that have been developed through thisprogram and uses industrial scale data to illustrate their accuracy.Results from the industrial trials of the Twin Chamber PulpLifter are also presented.

Jan 1, 2001

The comparison of belt drives with other types of power transmission involves the consideration of many factors before a final choice is made. Where other forms of power transmission might also be suitable, the selection of the correct type of belt has first to be made, in order to obtain a true comparison. The paper first deals with the types of belting available, followed by a description of most other forms of transmission equipment. An example is then given of the selection of suitable belts, which are then compared with other types of transmission. Comparative costs are also given. Reference charts provided show drives found suitable in general practice...

Jan 1, 1964

By Payne AR

The high cost of gateroad repairs and maintenance in U.K. longwall coalmining is a clear indication of the failure of permanent support systems to fulfill their prime function, i.e. control of strata movement. The main component of gateroad support is the pack, the design and materials of which have experienced an important development process during the last 10-15 years. More recently, research investigators have attempted to give a design basis to pack quality and dimension, and reference is made to two theoretical approaches. In the course of a current research programme based upon in situ monitoring, interim design recommendations have been proposed as a means of effecting improvement in support efficiency. Identification of characteristic deformation behaviour forms the basis of the recommendations made and the subsequent improvement in gateroad performance reported.

Jan 1, 1986

The products of the steel tube industry play an important part in the production,' transrzission and refining of oil. Steel tube manufacturing is already well established in Australia and supplies the petroleum industry with its requirements" within the .present limitations of the various tube plants., With the discovery of oil in commercial quantities in this country, the steel tube industry could be expected to extend its scope to cover a much wider range; of oil country tubular goods, line pipe and refinery. Tubing.

Jan 1, 1962

By Radenkovic C, Ivkovic S, Minic I

The model, already tested and applied, enables a highly efficaceous solution of the problem of issuing instructions for interested services on the basis of known contents of in- dividual stages of mine mechanization repair and known time intervals between repairs for specific machines and total mechanization. Application of the model provides work orders for all types of repairs for specific machines or systems, and orders for the commercial department regarding spare parts Supply.

Jan 1, 1977

By Yu AB, Azahari HL

Indonesia has the largest coal reserves in the south-east Asian region. According to estimates from the World Energy Confer- ence, it has reserves of 18 billion mt lignite, 4.4 billion mt sub-bituminous coal and 774 million mt bituminous coal (Wyllie,1988). In recent years, substitution of coal for oil in power plants has been the goal of the Indonesian government since proven deposits of coal are about five times as large as national hydrocarbon reserves and most of Indonesia's power stations are still oil fired. Recently a coal fired power plant has been built in Java Barat, which will have a full capacity of about 3000 MW. It is intended to supply coal for this power plant from Bukit Asam mining area (South Sumatra). Coals from Bukit Asam - which are of the lignite or brown coal type - usually contain considerable moisture . It should be noted that reference to moisture in coal pertains to the total moisture content. This is comprised of what is commonly termed as equilibrium moisture and surface moisture. Surface moisture typically affects combustion process as well as pulveriser performance since it possibly influences the relative ease with which coal may be ground. In practice, the surface moisture produces agglomeration of the fines in the pulverising zone and reduces pulveriser drying capacity because of the inability to remove the fines as quickly as they are produced. This agglomeration has also the same effect as coarse coal during the combustion process because the surface area available for the chemical reaction is reduced, hence the combustion efficiency is also reduced. The influence of the moisture of some coals on their grindability (Hardgrove Grindability Index) has been previously correlated by several authors; some of them will be mentioned later. Those correlations, however, could not be immediately applied to any coal since it is still believed that there are other factors which influence the grindability of the coal, such as type and rank of the coal. The relationship between coal moisture content and its grindability has been investigated by Ellmann and Belter (1955). It was found that, for North Dakota lignites, the grindability varied as the moisture content changed. In Britain, Fitton, Hughes and Hurley (1957) stated that, for Bilsthorpe coal, over a wide range of free moisture content (from air-dried to about 30 per cent moisture), the Hardgrove Grindability Index (HGI) remains virtually unchanged. In addition to that, it was suggested that it would be slightly advantageous to dry the coal below its air-dried moisture content (at temperature ¦ 100¦C) to increase the ease with which coal could be ground, especially for low-volatile coal and high-volatile non-caking coal. Furthermore, it was also concluded that a broad relationship appeared between coal rank and Grindability.

Jan 1, 1993

By Graham J

The successful processing of arsenopyritic ores is difficult and will be facilitated by a better understanding of the mineralogy of gold within arsenopyrite and the type of arsenopyrite in which gold is taken up. Solid solution gold in arsenopyrite is now well documented, and is a significant cause of refractory behaviour in gold processing. Investigations of the crystal structure and stoichiometry of arsenopyrite by X-ray diffraction, electron microprobe analysis and convergent beam electron microscopy have been carried out in order to understand how the gold is incorporated into the structure. Variations in stoichiometry, particularly the As:S ratio, of arsenopyrite leads to variations in structural parameters. These variations result in slight changes in thermal behaviour. The distribution of invisible gold in an arsenopyrite grain is generally non-uniform and synthesised samples contain up to 2 wt per cent gold. A transmission electron microscopy (TEM) technique called ALCHEMI is being used to identify the substitution site. The process of gold agglomeration together with evidence of an ordered breakdown of arsenopyrite to pyrrhotite has been documented with the use of TEM. An arsenopyrite grain containing invisible gold was heated with an electron beam resulting in recrystallisation of arsenopyrite to pyrrhotite with arsenic being expelled. The gold is mostly insoluble in the pyrrhotite lattice and therefore exsolves out and combines with other gold atoms to form droplets at the boundary of the pyrrhotite.

Jan 1, 1992