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By Rao S. B, Baafi E. Y

A venturi based multi-scrubber air cleaning system has been developed for dust control along a longwall face in coal mines. The system consists of a number of scrubbers. strategically placed along the wall face which deliver cleaned air at high exhaust velocity into the middle section of the longwall cross-section thus dividing it into two zones. The aim is to maintain the walkway on the powered support side as a zone of relatively clean air. Laboratory studies have shown that the scrubber's average efficiency is 90 per cent. Field trials in three longwall faces have shown that. under normal operating conditions. 40 to 50 per cent average protection efficiency can be achieved within 3 m to 4 m downstream of the scrubber. A three-dimensional finite element computational fluid dynamic model. FIDAP. was used to simulate the airflow patterns the dust concentration and the scrubber dust control technique at a typical longwall face. Results of simulations tally very well with the field results.

Jan 1, 1995

By Yianatos J. B

The advances in the study of control alternatives for flotation columns are reviewed. An integral solution to the control problem has to deal with problems associated with instrumentation, process modelling, control strategies and control algorithms. The term hierarchical control is used here to mean the intelligent integration of available knowledge, control algorithms and logic rules of decision. The selection of information, algorithms and rules is based on the experimental and theoretical knowledge of the column flotation process. The software support was designed and implemented in object oriented computer programs. This technique allowed the implementation of a combination of control techniques, algorithmics and heuristics, in the form of a control strategy. This strategy has shown to fit well with processes exhibiting complex dynamic characteristics. The hierarchical control was implemented in a pilot column and included the following general aspects: co-ordination of distributed conventional control loops, use of sets of control parameters for the froth depth control loop according to the froth depth state, verification and diagnosis of sensors, on-line predictive estimation of gas hold-up, diagnosis of common operating problems and the use of predictive control to account for feed flowrate changes.

Jan 1, 1995

In dense medium processes for the beneficiation of minerals the consumption of medium (generally ferrosilicon) represents a major component of the operating cost. This provides a strong incentive for improvements in heavy medium recovery circuit design and operation. A major thrust in heavy medium plant design over the past decade has therefore been towards circuits which reduce medium losses. In this paper recent trends in plant design are examined in relation to the factors infl uencing circuit performance and medium losses. Operational details ' which have a significant effect on losses are discussed and illustrated by means of plant and pilot plant test data, with particular emphasis on the performance of wet drum magnetic separators. While the emphasis is on reducing the consumption of the high-cost ferrosilicon medium used in minerals beneficiation, most of the principles described in this paper are equally relevant to the design and operation of magnetite recovery circuits for coal preparation plants.

Jan 1, 1987

Discontinuities often have a very detrimental effect on the stability of mine highwall faces. The west wall of the Muja open cut is remarkable for the number and variety of discontinuity sets which occur over a relatively small area. To-date 14 separate structural domains have been identified over an area measuring approximately 560 m by 120 m.The structural domains have been grouped into four structural assemblages on the basis of their angular relationships to each other and to regional folding and faulting. The distribution of these structural assemblages appears to be erratic and no controlling factors have been identified to explain or predict them other than in the most generalised terms.

Jan 1, 1993

By McCarthy P. L

A distinctive feature of the goldfields of Victoria was the extrac- tion of gold from deep leads, that is the buried river beds of Vic- toria's ancient rivers and streams. It is estimated that about 265,000 kg of gold was produced from Victoria's deep lead mines which comprises about 11.5% of Victoria's total production of gold (Bowen, 1974). The significance of deep lead mining for Victoria, however, went far beyond its economic contribution to Victoria. If Profes- sor Blainey is correct it was the frustrations of mining gold from deep alluvial leads in Ballarat during 1854 which precipitated the Eureka Stockade (Blainey, 1963, 46-52). This event resulted in the implementation of a fair mining administration and was an emphatic statement of the rise of democratic movements in Australia. Much of the technology and skill for mining deep leads had to be developed locally because at that time no other major gold- field elsewhere in Australia or the world had gold deposits with comparable problems. Deep lead mining in Victoria was there- fore largely a home grown industry and the equipment for that industry was often designed and produced in Victoria.

Jan 1, 1988

By Dugan K. J

Mine operators are currently in a situation where market forces are acting to reduce profit margins and at the same time, regulatory bodies are insisting on improved mine safety and stability. This means that ground support must be made more cost efficient while maximising operator and equipment safety.A key aspect of ground support efficiency is the 'in the ground' performance. This paper discusses the factors that influence the way rock bolts and cable bolts perform. It highlights the need to know how support efficiency varies in different ground conditions.

Jan 1, 1992

The Porgcra gold deposit is an epithermal gold base-metal deposit located in the Enga Province of Papua New Guinea. Gold-silver- spha le rite-galena-pyrite mineralization is related to stocks and dykes of dioritic composition which have intruded a series of folded marine sediments, mainly shales and siltstones, often with calcareous and carbon- aceous horizons, of middle Jurassic to middle Eocene age. The most intensely mineralized zone is at Waruwari Hill, where the mineralization occurs predominantly as massive mixed sulphide veins, and less frequently as quartz-chlorite veins and as disseminations. Mineralization occurs in all rock types and several phases of mineralization have been Recognized.

Jan 1, 1980

By Dinuzzo P, Wychie J, Desoe C

The Selwyn Gold-Copper Mine is located 150 km southeast of Mount Isa within Proterozoic units of the Mount Isa inlier (Figure 1). Mineralization in the mine area is associated with strongly sheared ironstones and iron rich schists at the base of the mid- Proterozoic Staveley Formation. The ironstone horizons outcrop as a series of dominant ridges over a 10 km strike. Economic gold-copper mineralization has been defined in 4 separate zones within a 3.5 km length of the outcropping ridges. A current combined geological resource for the deposits is 5.3 million tonnes of 5.0 g/t Au and 2.02 Cu. Weathering of the deposits has resulted in a pronounced vertical zonation of mineralogy, especially copper, within the ore zones. This has produced 3 separate ore types which require different treatment techniques. The categorization is based on copper content and zones are termed leached (surface), oxide and sulfide. Ore removed from the pits will be mainly leached and oxidized with minor sulfide near the pits final depths, while the underground ore will be from the sulfide zone with minor oxide in some areas.

Jan 1, 1989

The occurence of high silver values in the oxidised zone of the main lode at Broken Hill is well known as a large factor in achieving the early fame of Broken Hill, and the minerals of this zone form a long list, which has been tabulated by G Smith*, and includes...

Jan 1, 1926

By Chend J

Research conducted into backfill drainage at Mount Isa Mines since 1992 is described. Piping in draining backfilled scopes has been the primary cause of bulkhead failures and emphasis is placed on research into the piping mechanism. Laboratory and in situ tests aimed at understanding the piping mechanism have been conducted and the results are presented. A case history of piping in a draining bench scope fill mass is described and a technique for reducing the potential for bulkhead failures in hench stopes is presented. Hydraulic fill is produced by standard cycloning of tailings and the overflow (reject material) is sent to thickeners prior to placement in the tailings dams. Research into the partial introduction of thickener underflow into the backfill system and its influence on backfill drainage is also descrihed.

Jan 1, 1998

By Woodcock JT, La Broody SR

As part of a project on the application of thiourea leaching to a variety of Australian ores, the systematic variation of pH, redox po- tential, and thiourea concentration were in- vestigated on an oxidized gold ore from the Nevoria mine, WA. Stirred open beaker tests were conducted with a pH-stat and Eh-stat system to automati- cally control pH and redox potential at selected values, while thiourea concentration was main- tained manually. Increasing the acidity of the leach liquor from pH 3.6 to pH 1, increased the gold extrac- tion from 37 per cent to over 90 per cent in S h, but there was only a limited improvement below pH 1.5. Silver extraction and thiourea consumption increased as the acidity was in- creased. Increasing the redox potential from 150 to 200 mV (i.e. potential of Pt electrode vs SCE) increased the initial rate of gold and silver extraction, but the effect on cumulative gold extraction by 5 h was slight. Thiourea consump- tion was greatly increased as the redox poten- tial was increased. An increase in thiourea concentration from 1.2 to 4.8 per cent increased the initial rates of gold and silver extraction, but, as for the change in Eh, the improvement in cumulative ex- traction by 5 h was marginal. Thiourea consump- tion increased with thiourea concentration.

Jan 1, 1984

The economic significance of a fundamental understanding of the mineral pyrrhotite is dis- cussed. Particular emphasis is placed on the relationship of other sulphide minerals to the pyrrhotite when it is the major sulphide mineral present in an ore body. Studies of the Kambalda nickel deposit are used to give a better under- standing of (a) the genesis and other character- istics of a particular ore body (b) the textural relationships between pyrrhotite and other sul- phide minerals (c) magnetic properties of natural pyrrhotite, and (e) the oxidation and supergene processes that take place in a sulphide ore body.

Jan 1, 1972

Japanese pig iron production in 1973 registered about 90 million tons. As clearly seen from the productivity (2.04 t/m3/D), and fuel ratio (494 kg/t-pig), the Japanese steel industry has maintained quite high levels of efficiency in blast-furnace (BF) operations. Among the many factors which have contributed toward these high levels of efficiency, the use of high quality coke is very important. The Japanese steel industry imports about 85% of its metallurgical coals from various countries of the world, including Australia. The effective use of these metallurgical coals of various origins in accordance with their re- spective properties is most essential for maintaining coke quality. This paper describes coking properties of various metallurgical coals and blending techniques based on these coking properties, in relation to the specifications of coke quality required for efficient BF operations. This paper also describes briefly new technology for expanding the scope of the use of coking coals.

Jan 1, 1975

THE area of the State of New South Wales is not great, nevertheless it has very large and important Mineral Resources. This is the more noticeable when the values of the annual mineral production from the individual States of the Commonwealth arecompared with the value of the New South Wales production. The principal minerals mined now are not gold, copper, and tin, as they were in the early years following the gold rush of 1851, the centre of gravity of commercial mineral activity having moved to coal and "oil-shale," water, limestone (with cement), silver-lead-zinc cadmium, sulphur, slate and other building and ornamental stone, road materials, and clays.From small areas totalling only 650 sq. miles, coal to the extent of 311,000,000 tons, valued at £151,000,000, has been won.The estimate of actual and probable reserves by the Mines Department within an area of less than 1000 sq. miles is about 14,000,000,000 tons, while the potential reserves within the remaining 15,500 sq. miles of concealed coal fields must be enormous. Even taking into account only the actual and pI:obable reserves in the 1000 sq. miles known, and assuming a depletion at the rate of 350,000,000 tons a year, or somewhat greater than that of the British Isles at present, and assuming an average value of £1 a ton, with money at 5% compound interest, then the present value of this coal (40 years of depletion) would be £5,575,000,000 approximately: truly an enormous present value for a business of 40 years, dealing only with 1000 sq. miles of country. The location of the main coal basin in New South Wales is one of great strategic importance. It lies almig and near a seaboard, with excellent facilities for anchorage; the coal is of very high quality, and is readily accessible; the climate is admirable. Were this same coal at Port Darwin, its commercial importance would not be be pronounced.

Jan 1, 1926

The initiation of cast Pentolite primers by detonating cord has been examined by the combination of two different experimental techniques with computer simulation by the finite element hydrodynamic code DYNA2D. In the first type of experiment, the cord/primer system was placed in a water aquarium, and photographed using a high-speed image converter camera. This highlighted the emergence of the detonation front through the primer surface and the generation of shock waves in the surround- ings. Numerical simulation was used to interpret the experimental record, establishing where the cord had induced buildup to detonation inside the primer. The second experiment used the plate dent test, where the primer was placed in contact with a block of metal (here aluminium), with the resul- tant dent in the metal surface being a measure of primer output. Detailed numerical simulation of this test confirmed that the observed dent was caused by the development of a complex series of shock waves inside the Primer.

Jan 1, 1988

By Sauer P

The paper deals with the method of operat- ion, types of construction and sizing of screening machines as well as the selection of suitable screen decks. The application of novel screening mac- hines in hard coal preparation plants is explained in detail by way of examples.

Jan 1, 1984

By Large RR

Underlying the 15 million tonne, high grade Hellyer volcanogenic massive sulphide deposit of western Tasmania is an extensive, well developed, and well preserved stringer system. Pervasive alteration of the footwall mafic volcanics occurred as the hydrothermal system initiated. Mineralogical zoning exists within the footwall alteration pipe, with a central siliceous core giving way to zones of chlorite, chlorite-carbonate, sericite-chlorite, and finally sericite-quartz on the margins (stringer envelope zone). However, the alteration morphology and zonation is not symmetrical around the central siliceous core; eastward the alteration zones are steeply dipping and terminate abruptly under the massive sulphide, while westward they extend out under the ore body in a blanket fashion. Geologic evidence indicates that the pervasive alteration started with the development of sericite-quartz which was subsequently overprinted by chlorite and finally quartz-sericite as the hydrothermal system became focused towards the centre of the stringer system.

Jan 1, 1990

Pyrrhotite is the predominant gangue mineral at Renison comprising about 60 percent of the sulphides in an average ore blend. It exists as two crystal structures - monoclinic and hexagonal. Monoclinic pyrrhotite is the slowest floating of all minerals but is ferromagnetic and hence recoverable more efficiently by low intensity magnetic wet drum separators than flotation. This paper discusses the installation and commissioning of four 0.915 m x 3.0 m, 0.1 Tesla permanent magnet, wet drum separators prior to sulphide roughing flotation. Planned circuit and process control modifications to better accommodate magnetic separation into Renison's flowsheet will be Discussed.

Jan 1, 1991

By Dunn P. G

The copper ore reserves at the Chuquicamata mine were re-estimated during March to June 1994, as part of a comprehensive audit of the mine's overall short- and long-term planning. The basic principles essential to all ore reserve estimates were implemented viz: 1. A detailed study of the geology, in this case particularly of the orientations of structural features of copper mineralisation and the subdivision of the orebody into geologically homogeneous sections, 2. the use of both drillhole and blasthole data sets, 3. statistical and geostatistical analyses of both data sets to model anisotropic spatial structures for all the geologically homogeneous sections, 4. block kriging using both data sets individually; and 5. a comprehensive validation of the block valuations to confirm the absence of global and conditional biases and to quantify the actual improvement achieved in the overall quality of the estimates compared to those executed on earlier techniques.

Jan 1, 1995

By Grant JR, McKavanagh BM, Dear SJ

A geophysical technique of rock mass assessment for engineering purposes is being investigated and shows positive correlation with direct structural logging and mapping techniques for the detection of major geological features. The technique is cross-hole acoustic surveying incorporating high speed signal averaging, with a maximum hole separation in excess of 30 metres in hard unfractured rock masses. The bulk of the field test work was carried out in open stopes in the copper ore bodies of Mount Isa Mines Limited. The investigation forms part of an integrated study of blasting in mining, aiming for fragmentation control through blast design modification. The rock quality factor, Q, is presented as a blasting index and can be determined for a significant portion of a production stope.

Jan 1, 1981