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By Large RR

Precious metals in the Rosebery north-end orebody occur predominantly in sphalerite- galena-pyrite ore and to a lesser extent in massive barite mineralisation. Gold may also occur in the upper parts of pyrite-chalcopyrite ore (although this ore type is usually gold poor), in pyritic mineralisation lateral to base metal sulphide lenses and in the footwall (very patchy). Although present, remobilised precious metals do not occur in economically significant quantities. Mineralogically, silver occurs dominantly in tetrahedrite and, to a lesser extent, argen- tiferous galena. Gold occurs as electrum associated dominantly with pyrite and, to a lesser extent, tetrahedrite. Geochemical modelling suggests that silver was probably transported as a chlorocomplex, while gold was transported dominantly as a thiocomplex, although at high temperature gold was transported as a chlorocomplex.

Jan 1, 1987

A contract for three 20 ft diameter vertically mounted axial flow fans of the same aerodynamic design, was placed by Mount ]sa Mines Limited in 1963. The hydraulic blade pitch changing mechanism, the method of blade fabrication, and the roll out centre casings are features of these fans. Protection devices and fan control are designed for unattended operation and remote control. The erection and commissioning of the fans during 1964-65 is described.

Jan 1, 1967

There are a number of examples of how environmental factors have been integrated into the water management aspects of mining projects. The Kingston Lignite project in South Australia, Pine Creek Gold Mine in the Northern Territory, gravel and sand extraction from the Nepean River flood plain near Penrith, and the Olympic Dam Project have all illustrated that consideration of environmental factors can be integrated with project developments, with beneficial outcomes for both the project and the environment.Each of the above cases demonstrated an individually significant environmental issue, directly related to the interaction between the proposed project and its environment. In each case, careful research and an integrated approach to the problem resulted in a solution that gave both maximum protection to the environment and optimum consideration to the economic feasibility and success of the proposed project.The solutions ranged from alternative mining methods and improved waste and water management through to the ultimate objective of converting a mining project into a major water-based recreation source. These examples have set a precedent that will contribute ignificantly to the successful development of future projects.

Jan 1, 1988

Thank you for this opportunity to address your conference on The role of coal in the New Zealand energy market".New Zealand's energy market has, in common with much of New Zealand, undergone major change following the market reforms of the Labour Government.As far as the energy sector is concerned this change has been for the better, as it has created for the first time in a very long time a "true economic market" for energy in New Zealand.

Jan 1, 1990

By Edwards R

Greater efficiency of capture of minus 6 mm to fine micron size particles of free gold is achieved with the Knelson Concentrator. The development, principles of operation and recent innovations relating to this enhanced gravity concentrating device are described by the inventor, followed by a description of application and consequent economic benefits in low grade alluvial gold deposits by a large scale user of Knelson Concentrators in the Northern Territory of Australia.

Jan 1, 1990

By O. J. RICHARDS

The Wongawilli system of mining has been in use for over 30 years and has enabled high production rates and acceptable extraction ratios to be achieved in seams less than 4 m in thickness. A modification of the Wongawilli system has been developed to permit the use of a continuous miner and mobile equipment to extract a coal seam 6 m thick. Following physical and mathematical model studies the new mining method is now undergoing field trials at Collinsville, Queensland. Progress of the field trials to date has achieved 99% extraction of the upper slice by remote control operation of the continuous miner and established the feasibility of installing resin grouted wooden dowels in the coal floor to reinforce the coal septum. The method is explained in the text.

Jan 1, 1980

By Y S. M Tabatabaei, R Hosseini Tabata

Application of Acidithiobacillus ferrooxidans bacteria to flotation of Sarcheshmeh low-grade copper sulfide ore was studied. Sarcheshmeh low-grade ore contains pyrite, which causes some problems in the flotation of copper minerals. In this study, A ferrooxidans was used to change the surface chemistry of pyrite and copper sulfide ores and consequently, their flotation behaviour. In the presence of A ferrooxidans and xanthate as a collector, pyrite was depressed whereas chalcopyrite and other sulfide minerals were unaffected. In addition, the pulp pH remained unchanged. It was shown that the surface chemical properties of the bacteria could be manipulated successfully to achieve the desired effects in a flotation process. The results showed that the recovery of pyrite in the presence of the bio-depressant is 50 per cent lower than when no bacteria were present. At the same time the recovery of chalcopyrite remained unchanged.

Jan 1, 2004

By D H. Bell

Slab-buckle failures in coal sequences involve thin slab deformation in strata dipping parallel to the footwall, and are a consequence of both unloading and the weak nature of the thinly bedded rock mass. Methods of modelling and predicting such occurrences include: +        a conceptual model using a base friction table, +        a mathematical model using the Euler solution for column and beam bending (after Goodman, 1980), and +        computer analysis techniques such as UDEC (Universal Distinct Element Code after Cundall and Hart, 1993).   Slab-buckle failures have the potential to seriously disrupt production because of their volume and rapidity, and to endanger both equipment and personnel working on the pit floor.   In July 2004 a large slab-buckle failure occurred overnight after a new batter and bench had been formed at the Malvern Hills Opencast Mine in inland Canterbury. This involved the entire length of the pit (85m along strike) when a 2m thick intact slab with a total volume of ~3500m3 translated down dip 6.2m on the base of a thin coal seam to form a pronounced buckle at the toe. The coal measures consist of finely laminated mudrocks with multiple coal seams of varying thickness dipping ~45¦ to the southeast, and the opencast mine had been designed with footwall batters formed parallel to bedding with a vertical bench separation of 15m.   Back analysis of the Malvern Hills failure was necessary to investigate the controls on footwall instability, and for future mine design. An engineering geological model was created and samples of the slab material and failure surface were collected and tested to establish the required parameters for use in the Euler solution for column and beam bending. Back analysis using the Euler solution provided unrealistic results that overestimated the overall length of a stable slope by more than 10 times.   No further large scale slab-buckle failures have developed at the mine site, in part because of the slow rate of coal extraction, but precautionary drainage of the footwall slopes has been undertaken to improve overall batter stability. The location of the slab-buckle failure on a critically positioned pre-sheared thin coal seam with full hydrostatic head is considered the most probable cause of the July 2004 failure, rather than inherent instability of the generic bench and batter arrangement adopted. The use of a precedent-based engineering geology approach to future mine design is considered the most appropriate solution in the circumstances.

Jan 1, 2007

By Walshe JL, Solomon M

The Emperor vein system lies on the eastern margin of the Tavua volcanic structure. This is of Miocene age and occurs in basalts(the Mba Volcanics) probably underlain at about 2 km by calcite-rich sediments (the Vatukoro Formation). The lodes are generally flatmakes, or steep fault fillings, or complex shatter zones, and consist of quartz and altered wall rock. In areas of open cavities it is possible to establish a paragenesis which involves five quartz stages and two ore mineral stages. The first ore stage contains calaverite, krennerite, sylvanite and native tellurium, the second petzite, hessite and native gold. The quartz stages are thought to have formed slowly (102 years) from boiling solutions of low salinity at temperatures varying with time from about 250¦C to 190¦C. The system was sealed, the temperature gradient near vertical and the mass flux small. The ore mineral stages probably formed relatively rapidly (101years) from boiling solutions at 250¦ to 200¦C when the system was mainly open. Gold deposition was probably largely a result of fall in aH2S due to boiling, the calculated solution concentration falling from a maximum of about 8 ppb at 250¦C to about 8.10-3ppb at 200¦C. Boiling is also probably responsible for an increase in a02 (by loss of H2) and fall in aTe2 (by loss of H2Te). The fluids are thought to have had a large component of meteoric water and to have been heated by plutons in the core of the volcanic structure. Stable isotope data indicate that they derived their carbon from the underlying Vatukoro Formation and their sulphur from sediments. Circulation may have been confined to the outside of the volcanic structure because of the relatively low permeability of the flows, pyroclastics and dykes within it.

Jan 1, 1987

By Irving R. C

THE objective of the iron smelter is naturally the production of high quality iron at the lowest practicable cost. To enable this, large tonnages are put through the blast furnace, and, at the same time, the quality of the iron must be under definite control.The modern blast furnace enables these objectives to be attained. The description whieh follows sets out the general details of construction of such furnaces, and the operation at thc Broken Hill Proprietary Company's blast furnaces at Newcastle, New South Wales.The occurence of iron in many forms is so well known as to need no description. Modern civilisation may be said to be built on a foundation of iron, and, today, the production of iron and steel has beeome one of the world's industries.A short historical introduction will serve to show the evolution of the processes and apparatus since iron production assumed importance.There is no definite date fixed as to when iron was first made, or by what means it was first discovered. Perhaps prehistoric man threw iron bearing stone on to his fire, and these became reduced, Ieaving a soft metal behind, or more probably the first iron was of meteoric origin.There is evidence, however, to prove that it has been known for a period of 6000 years. Iron has been found in the Pyramids and its use was known to the early Eqyptians and later to the Hebrews, Assyrians, Greeks and Chinese. Following the Greeks, the Romans excelled in its extraction and uses in the manufacture of their instruments of war, and to this fact can largely be attributed the success of their many wars of conquest. As the Romans overran the rest of the then known world they carried the art with...

Jan 1, 1930

By Trois P

A fully instrumented and bench-mounted diamond drilling machine, purpose designed and built, has been used for investigating the effect of aqueous solutions of various chemical compounds when used as drilling fluids. The rocks investigated were andesite, basalt and granite, the chemical compounds were alkylamines, with various hydrocarbon chain lengths, aluminium chloride and dioxane. Rotation speed seems to be one of the major factors affecting the emergence of mechanochemical effects as the results obtained with aluminium chloride clearly indicate. Penetration rate is either unaf- fected or enhanced by the presence of certain compounds, such as aluminium chloride. On the other hand, penetration rate diminishes when the drilling fluid contains dioxane and exhibits an apparently unpredictable behaviour with alkylamine solutions, although it appears that an increase in hydrocarbon chain length usually equates to an increase in penetration 1. Full Professor, Mining and Mineral Dressing Department University of Cagliari - Italy 2. Associate Professor, Mining and Mineral Ikea- sing Department University of Cagliari û Italy rate. Rock texture seems to have a pronounced effect on test repeatability. With hexadecy- lamine acetate solutions in concentrations ranging from 10-5 to 5 .10-4 molò dm 3 and 41.88 radòs-1 rotation speed, 46 % increments in penetration rate of andesite were observed, with respect to water, whereas penetration rate decreased in basalt by as much as 60¦%o when a dioxane solution was used as drilling fluid. An interpretation of the observed effects is proposed in the light of current knowledge of solid state physics and physical Chemistry.

Jan 1, 1992

On Monday, October 25th, 1971 at approximately 12.15 a.m. the night shift proceeding underground discovered smoke at No.1 and No-3 cut throughs on the eastern side of the belt heading and in close proximity to the upcast shaft. Attempts to control the fire continued throughout the morning; as the position underground altered various procedures were adopted in an effort to contain and control the fire. Despite these efforts at approx. 12.40 p.m. a sudden change occurred which made it necessary to withdraw all workmen from underground, the vicinity of the Tunnel entrances and upcast shaft. Sealing of the mine at the entrances was the only remaining alternative. Several boreholes were put down to enable sampling of the atmosphere and air temperatures to be taken. This was essential as a guide to determining when conditions were suitable to allow exploration of the area using mine rescue self contained breathing apparatus.

Jan 1, 1972

MERLIN, the Queensland Department of Minerals and Energy's corporate geographic information system, provides ready access to all georeferenced data held by the department. Its aim is to provide a consistent, current, statewide coverage of timely information to assist in tenures management, exploration targeting and competing land use decision-making. Initially developed in 1988 and under continual enhancement since then, its functionality is the result of on-going close consultation with a wide range of departmental clients and potential users. A true geographic information system, MERLIN maintains both graphical data with linked textual information on a wide range of features of interest. The proprietary software products Arclnfo and Oracle are used to hold the graphics and attribute information respectively. Access to information is provided by a specially designed graphical user interface programed in-house. Hardcopy output of graphics displays including related attribute data as well as detailed reports of textual information can be retrieved at any departmental office. MERLIN is a network of computer systems which link each of the Department's regional offices and head office in Brisbane. The current state of exploration and mining is maintained by departmental officers processing tenure applications, transactions and dealings directly into the system. Data entered at regional offices are transferred overnight to head office to up-date central records and maintain a currency of data statewide as at the close of business the previous day. Through MERLIN the Department of Minerals and Energy now offers a much streamlined tenures management service as well as access to information about past exploration and mining, Queensland's mineral and energy occurrences and resources, and up-to-date information on the state's geology including maps, boreholes, geophysical surveys and field observations. In the future, this Geographic Information system will be invaluable to the mining industry in the development of mining projects.

Jan 1, 1995

By Falconer A. J

Two magnetic parameters are proposed as a basis for the assessment of ironsands beneficiation. The parameters are deter- mined for raw sand prior to dredging and for magnetic separator head feed over a production period of five months. The relationships between these parameters and the performance of the magnetic separators are examined to establish the value of magnetic assessment compared with the traditional soluble iron assay method. The results illustrate that the first parameter, true magnetic fraction (TMF), has a value superior to that of soluble iron when relating raw sand grade calculated by tri- angulation to magnet performance. In terms of the relationship between magnet head feed grade and magnet performance, TMF and soluble iron perform equally as assessment parameters. For the ironsands mined during the five month period, the second magnetic assessment parameter, composite fraction (CR), is shown to merely reflect TMF and offers no additional information for assess- Ment. Conclusions are that true magnetic fraction has many advantages over soluble iron in terms of time and cost of determination and that it is a meaningful and reliable parameter upon which to base all calculations relating to the mining and beneficiation of ironsands.

Jan 1, 1980

By Leach B. G

A geostatistical study was made of diamond drill hole intersections within 18CC stope block at the C.S.A. Mine, Cobar, N.S.W. The stope block is located in 18CC orebody which is a massive sulphide - multiple vein, Copper-Zinc type, lacking clear definition on gangue mineralogy, base-metal assays and total sulphide considerations. Of the variograms constructed for inter- section width and copper, lead and zinc grades and accumulations, only zinc displayed behaviour amenable to model fitting and kriging procedures. Zinc grades were calcu- lated for sub-blocks comprising the total stope block and comparison with equivalent grades determined by traditional methods showed them to be generally less extreme in the highest and lowest grade sub-blocks. The total-block grades derived by the two methods were almost the same. It is suggested that the failure of copper to show variogram continuity might reflect the difficulty in defining the actual 18CC orebody, a proposition which is supported by the poor continuity in the variogram of horizontal width. In the case of lead the poor continuity may be due to the frequent manner of occurrence of galena as coarse grained patches of limited extent. The results of the study, did not provide a convincing reason to depart from the traditi- onal methods of grade estimation at the C.S.A. Mine.

Jan 1, 1979

By Heidecks C

Sub-level stoping with consolidated rockfill is the main method for mining steep dipping baryte and fluorite veins in Germany. Drifting is fully mechanised using drill jumbos, LHD units and shotcrete support. Stopes have heights up to 50 m with sub-level distances up to 15 m. Winning of the pillars between sub-levels is done by longhole blasting in slices of 3-5 m length on strike. Mucking is done on the lowermost level by LHD units. After each blast rockfill with binder (cement and/or fly ash) is dumped into the scope from the uppermost level. Economic success depends on both geological and technical parameters and factors, eg vein thickness and dip, ore grade, size and distance of sub-level drifts. Of particular influence are ore loss in pillar winning and dilution both in drifting on vein and in pillar mining. A comprehensive computer program has been developed for calculating the total cost per tonne run-of-mine ore respectively per tonne of concentrate for a single stope. The cost model includes development, longhole blasting, mucking and haulage to the mill, milling and ventilation. All costs (labour, energy, supplies, maintenance, depreciation and capital cost) are taken into account. Dilution and recovery are both considered. The program can be used to estimate the cost of mining a particular stope. It can also be used to investigate the influence of relevant parameters and factors on the economic result. By this way it should be possible to optimise the technical design of a stope.

Jan 1, 1995

Mt Todd lies towards the south end of the Pine Creek Geosyncline, sandwiched between the Cullen Batholith and the Edith Falls Basin, in an area of regionally metamorphosed sandstones, siltstones and shales. The Batman deposit, some 3 km west of Mt Todd is a sheeted quartz vein system hosted within greywackes of the Palaeoproterozoic Burrell Creek Formation (Finniss River Group). The gold-bearing quartz veins, trending 010¦-020¦ and dipping 60¦-70¦E, are commonly 0.5 to 5 cm wide and occur at intervals which are from 10 cm to 1 m apart. Gold tends to be restricted to the quartz veinlets and immediately adjacent country rock. Grade Control utilises two 4 m 'collar' samples which are collected from each 8 m production blasthole. The irregular distribution of the quartz veins and erratic gold mineralisation has resulted in a disseminated 'salt and pepper' type of gold occurrence, with only a poorly defined footwall. Delineation of ore and waste blocks for mining uses an approach which combines the smoothing effect of kriging with a pragmatic view of the raw data. Large ore blocks with simple geometry help to minimise mining dilution, reduce block variance and give good reconciliations to interpreted ore tonnes and grade. Daily mine face advance is reported against truck counts and provides continual comparison with budgeted production. All data processing uses Gemcom software, together with Lotus spreadsheets.

Jan 1, 1994

By Ostrea AM

Aqueous oxidation in an autoclave at ele- vated temperatures and oxygen partial pres- sures is applied to Philippine gold-bearing sulfide ores and concentrates which respond poorly to conventional cyanidation. The gold concentrates are recovered from ores and tail- ings material using the patented OMLI Process (the OMLI Process is able to upgrade tailings material analyzing 0.50 g/t Au to a concen- trate with a grade of 5 g/t Au or better). The results show that with aqueous pre- oxidation of the concentrates ahead of cyani- dation a four-fold increase in gold recovery is obtained compared with straight cyanida- tion. The observed differences in response to the pre-treatment step between various mate- rials are correlated with their mineralogical composition. The chemistry of aqueous oxida- tion is also presented.

Jan 1, 1986

By Mousset-Jones P, McPherson M. J

Underground airways are characterized by irregular shape and uneven surfaces including large-scale natural roughness, fractures, and a super-imposed sand roughness. Swirls in the grooves of the wall and separation because of the periodic variation of the open cross sec- tion, due to the blasting patterns, make it almost impossible to calculate average con- vective heat transfer computationally on the bases of the geometrical description of the surface. However, dimensionless friction factors can be used to characterize the surface effect of an airway and an analogy between heat and momentum transfer can be applied to calcu- late an average convective heat transfer Coefficient.

Jan 1, 1988

Woodlawn Mines began underground operations in 1986. At the time of going underground it was envisaged that there would be no 'contract' payment to the underground employees. This was a relatively unique step to make, especially as most major underground mines in Australia relied heavily on the contract system to motivate their workforce. (Obviously with varying degrees of success.) Woodlawn faced the task of motivating their employees through a multi-skilled system with a great emphasis on leadership and a genuine care for their employees. The 'proof of the pudding' is that Woodlawn has not lost any time over industrial issues since beginning underground operations in 1986. To achieve success in any operation the organisation must not only be advanced in its management principles but also be prepared to be innovative in the way it deals with physical problems, ie ground control, equipment selection and maintenance. Difficult ground conditions at Woodlawn have necessitated the deployment of two Cabolt Jumbos and the construction of cost-effective shotcrete systems. The shotcrete system now being built has been tested in a prototype form and is proving to be a safe and simple way to manage weak, low stress friable ground. Although the ground at Woodlawn has low stress component by virtue of the fact the ore can have a density of 4.5dm3, cable dowelling has become a necessity. The two cable dowel jumbos install high quality reinforced cables. The pressure of 'production' means that these machines must be consistently available for use and the training of maintenance personnel and operators ensures that a maximum of cable dowels can be installed over any given time span. In any modem mine ventilation is a primary concern and the major area of concern comes from the vehicles themselves. In our recent replacement for the standard 'Toro' loader, three engine options were considered. A relative newcomer to underground mining was accepted. The Detroit 60 series (DDEC) engine came with a great reputation and has lived up to this. The engine has an electronic management system that reduces particulates to a hardly visible minimum, provides great amounts of engine power and reduces fuel consumption by approximately 45 per cent. The operational benefits of such an engine are worth sharing through this conference.

Jan 1, 1995