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By Baafi E. Y

A heuristic approach for the optimisation of the stope geometry is presented. The heuristic method uses economic model of a given deposit to search for the best combination of mining blocks that results in the maximum profit while imposing geo

Jan 1, 1998

By Yates M. G, Rowlands A. T

Most geostatistical techniques applied to the estimation of ore reserves assume relatively unifonn grade and thickness within an ore deposit environment. In shear-hosted mineralisation this rarely occurs. The distribution of mineralisation is controlled by the kinematic and geometric variation within the shear zone. Although the kinematic variation is dependent primarily on the temperature (and consequently the depth) of formation of the deposit, the geometric variation appears to be relatively insensitive to this parameter. Shoot mineralisation is controlled either by the intersection of secoodary shear planes (brittle deformation) or the stretching lineation of the mylonitic fabric (ductile defonnation).Once the shear geometry is clearly identified, it is critical to review the distribution of grade and thickness of mineralisation. The practice of cutting high-grade intersections without reference to the shear model leads to underestimation of the amount of gold in the deposit. High-grade shoots may occur as pipe-shaped bodies within the system; their identification is essential for both resource estimation and mine planning purposes.

Jan 1, 1991

The excavation of sandstone of generally medium strength for the Liverpool Link Line by Dosco Mark 2A Roadheaders has demonstrated the versatility and good performance of road- headers in suitable rock formations. A description is given of the strata traversed by the tunnels together with descriptions of equipment and crews, excavation sequences, operating difficulties and the results achiev- ed. In addition tunnel construction is des- cribed for a difficult section where there was only O.Sm clearance between invert and a four lane vehicular tunnel below, and O.5m clearance between tunnel crown and a century old sewer above.

Jan 1, 1976

By Soma T

Pyrite and Cu-concentrate were roasted in vertically suspended state in an externally heated tube. Tubes of three different lengths of reaction zone were used for three different reaction times. Roasted ores were submitted to chemical analysis and the extent of roasting reactions was determined. In case of pyrite, extent of roasting reactions was not affected much by reactor length and heating temperature (above 500¦C), but was considerably by ore/air ratio. Micro- scopic and XMA examinations led to the conclus- ion that pyrite particles decomposed to pyrrho- tite and then pyrrhotite was oxidized to give Fe-S-0 melt, magnetite and hematite. The extent of reaction was not uniform in all particles but had a wide distribution from unreacted pyrite to completely oxidized particles. Combustion of Cu-concentrate from Kuroko complex sulfide ore ) was unstable under a uniform wall temperature of 450¦C, but proceed- ed rapidly at temperatures above 500¦C. Sticking of roasted ores to the wall of the reaction tube induced choking of the tube, caused by melting of roasted ores, at tempera- tures above 950¦C. Enrichment of oxygen exterted less influence on reaction rate than heating temperature of the tube. Particle size of ore had a big effect on reaction rate.

Jan 1, 1980

By T Leach, F Kaiqiang

The Jianchaling gold deposit is located about 1200 km south west of Beijing in central China. The deposit was discovered in 1988 by the Northwestern Geological Exploration Bureau (711 Exploration Team). Sino Gold Limited, an Australian based company, developed the mine in 1998 and is currently operating a 1000 t per day underground mine, producing about 80 000 ounces of gold per year. The pre-mine resource for Jianchaling was 1.6 million tonnes at 9.85 g/t gold. The deposit occurs within the east-west trending Mesozoic Qinling-Dabie orogenic belt formed during the Yanshanian Orogeny. In the Jianchaling region, gold mineralisation is primarily hosted by regional west-northwest to east-southeast striking faults, the most important of which, the reverse sinistral F145 fault, hosts the larger gold deposits including Jianchaling. At the mine scale, the most important zone of mineralisation is localised within a shallowly north dipping dilation on the F145 fault. Proterozoic dolomite forms the hangingwall and serpentinite and talc schist the footwall to the fault. Within the footwall, serpentinite is the most important host rock to mineralisation. Initial alteration involves replacement of serpentine to dolomite ¦ pyrite, talc to ankerite ¦ pyrite, and magnetite and chromite to pyrite, the latter locally through a transitional hematite phase. Proximal to feeder structures, the carbonate minerals have undergone partial dissolution and replacement to quartz. Gold is related to arsenean pyrite and marcasite rimming and replacement of early-formed pyrite, and associated with iron release during the processes of dolomitisation, silicification and carbonate dissolution.

Jan 1, 2004

By Nairin J. D, Hayes P. C

Detailed studies of the microstructures and compositions of zinc and lead blast furnace sinters have been undertaken. An analysis of the results obtained has indicated that in many cases the microstructures of these complex materials can be explained by the solidification of melts from pseudo-ternary phase systems. Further laboratory studies have been carried out to more accurately determine the extent of primary phase fields and the liquidus temperatures in the appropriate binary and ternary systems. This approach shows considerable promise in simplifying the descriptions of slag systems used in oxidising and reduction smelting processes for lead and zinc recovery.

Jan 1, 1992

By Woodcock J. T, Sparrow G. J

Activated carbon particles obtained from a number of Australian CIP operations were examined with an optical and a scanning electron micro- scope and an electron microprobe. External surfaces, and polished sec- tions through individual particles, were examined with special reference to materials on the surface and to calcium and gold distributions. Photographs are presented of surface contamination of the particles by salts precipitated from the pulp such as calcium carbonate (calcite), calcium sulphate (gypsum), and a magnesium salt; ore minerals such as quartz, hematite, pyrite, arsenopyrite, pentlandite, and various alumino- silicates; and other substances such as grinding media and a fungus. Calcite was very abundant but the other materials were less common. Contamination in the interior of carbon particles was almost exclu- sively calcium carbonate, and extensive contamination extended to the centre of some particles. A possible mechanism for the formation of cal- cium carbonate inside the carbon particles is noted. Gold X-ray dot maps of sections through carbon particles indicated that gold was distributed throughout coconut shell carbons and that although gold was more concentrated near the outer surfaces of extruded peat carbon particles, it was also present to depths of at least 500 ¦m. The gold distribution throughout the carbon particles was similar to that rf alrit~

Jan 1, 1988

With the progress of modern mining engineering, one of the features of which is the mining from greater depths and the hoisting of greatly increased loads, it becomes a matter of increasing importance that the engineer should be able to determinewith some degree of precision the character of the strains on the hauling rope. But a wire rope is a complex structure; it is made up of spirally-twisted strands, which in turn are composed of spirally-twisted wires, and it is not particularly easy to say exactly what happens when this "doubly-twisted structure is wound round a drum or over a pulley.. The difficulty has been generally evaded in ordinary practice by the simple device of adopting a large factor of safety for the rope-usually from 8 to 10-a factor which experience has shown is sufficiently large to cover the bending strains set "up when the rope is passed over pulleys of the sizes commonly considered appropriate.When, however, we add the stress due to the bending of the rope to the stress produced by" the direct pull, we find that the actual factor of safety is usually more nearly 4 than 10, and frequently the bending stresses in the rope are so large compared with the simple tensile stresses that their neglect may easily lead to disastrous results when dealing with problems a little out of the common run. Common Empirical Rules.-It is always "recognized that the bending of a wire rope round too small a pulley is likely to do the rope serious injury, but as it is desirable in ordinary winding operations to reduce the inertia of the moving parts to a minimum...

Jan 1, 1907

By Kuganathan V

The processing of black coal in Australia segregates waste in the form of coarse reject and fine tailings. The coarse reject is relatively easy to handle, while the tailings can be problematic. Conventionally, the two waste materials are disposed of separately, the coarse reject in dumps, and the tailings in man-made containments. Aqueous tailings slurry is pumped to a 'wet' tailings storage, where the fine particle size of the tailings limits dewatering. Their low bearing capacity and high compressibility result in tailings deposits being difficult to rehabilitate. Disposing of the waste streams separately moves away from the heterogeneous mixture in the undisturbed ground, and concentrates potential problems with each waste stream. The feasibility and desirability of the co-disposal of tailings and coarse reject by combined pumping is demonstrated. This technique is in operation at Jeebropilly Mine and is proposed for a number of other coal mines.

Jan 1, 1992

By Hermann J. A

Over the last few years enormous dapooits of high-grade bauxite have been discovered in Australia, ;_ d an alum .nium smelting industry based on them is rapidly being developed,, This industry requires large amounts of carbon, as about 60 pounds of carbon anodes are consumed for every 100 pounds of aiumin.'.'-n produced. Tie anodes are usually made by mixing finely ground petroleum coke with coal tar or petroleum pitch, forming the mix into shapes under pressure, and baking them at around ?.200¦C0 Petroleum coke is ussd uecause its high density gives good strength and conductav_ty to the finished electrode, and its purity ensures that contamination. of the alumin- ium by extraneous i,iorganic material from tho carbon is low,

Jan 1, 1969

By Ahmed M, Leung L

A program of microseismic noise monitor ing for gas outbursts, in conjunction with other mining engineering measurements and observations, is being undertaken at Leichhardt colliery in Queensland. Headings are developed at present by shotfiring. The equipment being used in this study includes piezoelectric accelerometer assemblies to detect microseismic noise which is then transmitted to a surface base station by cable. Data are recorded on an analogue magnetic tape recorder and are also analysed on-line using a commercially-available acoustic emission pulse analyser. It is proposed to re-interpret recorded data using various modes of analysis and to interface a desktop computer to the existing system to permit continuous monitoring on the mine site. No outbursts have been recorded or analysed and only a limited number of develop- ment shots, and the resultant microseismic activity, have been recorded to date.

Jan 1, 1980

By Orr D. B

This is a case history of prospec- ting carried out by Comstaff Pty. Ltd. over the Pinnacles Area, part 4 of Exploration Licence 5/63, 9 km north of Rosebery in Western Tasmania. Evidence is presented to show that A 0 soil samp ling is a viable prospecting method for outlining polymetallic sulphide occur- rences in areas where leached organic/ glacial soils are common. Diamond drilling of low threshold anomalies has intersected base metal mineralisation.

Jan 1, 1977

By Roddick F

From its mining lease at the northern end of Cohens Reef at Walhalla in the North Gipps- land mountains, the Long Tunnel Extended Gold Mining Company produced 13,695kg of gold, which at 1982 prices represents a value of about $140 million. In the period 1885 to 1908 the mine was one of Australia's principal reef gold producers, being top Victorian producer in six of these twenty-four years. Prior and subse- quent occupants of the lease produced an addit- ional 160kg of gold. The Extended and the other mines on Cohens Reef whilst contributing importantly to the financial resource of Victoria, were the sole important support for the substantial town of Walhalla that had grown up around them. When the mines closed, Walhalla gradually reduced from a bustling developed town to the present attractive mountain village so favoured by tourists.

Jan 1, 1982

By Will D

This presentation is to outline the current practice of mechanised stoping a one-metre wide, gold bearing ore body to optimise fragmentation, minimise dilution and reduce stoping costs.Coolgardie underground operations have historically been mined using traditional shrink stope methods, but in this recent economic environment (with falling gold prices and high costs of traditional methods) it was necessary to look for alternative methods in order to reduce costs and increase productivity.Although still in a learning and refinement phase, CGNL is satisfied that it is feasible, practical and more economic to use mechanised long up-hole stope and long-hole rising methods to significantly reduce the mining cost, reduce dilution, increase safety and increase productivity three-fold compared to traditional airleg methods used throughout the Fasten Goldfields.

Jan 1, 1993

Ulan Coal Mines Limited operates an underground and open cut mine near Mudgee in the Central West of NSW. The mines are part of a Joint Venture managed by Exxon Coal and Minerals Australia Limited (ECMAL). Currently all the mines output of over five million tonnes per annum is sold into the export market predominantly as a steaming product.

Jan 1, 1993

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

By Selischop F, Tredoux M

The distribution of platinum-group elements (pGEs) has been investigated in matte and slag samples from Waterval Smelter (Rustenburg Platinum Mines). The study showed that a strong preference of PGEs for alloy phases in matte represents a concentration mechanism that commenced in the furnace but can be considered a continuum from natural processes. Metal losses to fayalite (converter) slag occur by matte entrainment due to the mechanical capture of liquid sulphide droplets from the matte layer, and the exsolution of dissolved metal sulphide resulting from changes in the oxidation state of the slag. The latter is comparable to immiscible sulphide in basic magmas. However, the observed distribution of PGEs shows enrichment in metal phases of the matte. A mechanism is proposed whereby naked PGEs in silicate melts coalesce to form clusters which are stabilised by surface attachment of sulphur atoms. This envelope acts to 'draw the cluster into sulphide melts. Small particle melting effects permit PGE clusters to remain as liquids at magmatic and smelter temperatures.

Jan 1, 1994

By Preston JC, Richards DJ

A multicommodity exploration programme was mounted in the 1970s by CRA Exploration Pty. Limited over a major part of the southern Murray Basin in Victoria. Commodities sought were brown and black coal, gold, uranium, diamonds, titanium and zirconium rich heavy minerals, and base metals. An area of 40 000 km2 was held under exploration licences by the Company. Exploration techniques used were literature research, airborne magnetics and gamma ray spectrometry, drilling, and geophysical well logging. Targets were defined in both the Tertiary basin sediments and the underlying Palaeozoic sedimentary and igneous rocks. Although exploration is continuing, large resources of brown coal and low grade titanium rich heavy minerals have already been discovered. Exploration for uranium was abandoned in accordance with statutory requirements. The search for significant resources of the other commodities has not been successful.

Jan 1, 1986

By K Marler

The Water Act 2000 includes provisions to manage the take of overland flow water. Overland flow water is water that runs across the land after rainfall either before it enters a watercourse, after it leaves a watercourse as floodwater, or after it rises to the surface naturally from underground. To ensure adequate environmental flows and long-term security for water users, it is necessary to balance the amount of water taken as overland flow water and the amount left to flow into watercourses. A water resource plan made under the Water Act 2000 establishes the basis for the sustainable management of this type of water. Of the water resource plans that have been prepared for Queensland catchments, six include provisions to manage the take of overland flow water. This paper discusses some of the common features of these plans and the management approaches adopted. The paper identifies and explains key aspects of the Water Act 2000 framework for managing the take of overland flow water by the mining industry. In particular it explains key concepts of this framework, such as the ability to take overland flow water using existing works, uses of overland flow water that a water resource plan permits, situations where a specific entitlement under the Water Act 2000 is required, and the means for controlling works that take overland flow water. Future initiatives for the regulation and management of overland flow water are then identified and particular challenges for the mining industry associated with using overland flow water highlighted.

Jan 1, 2006

The Vera Nancy orebodies, although simple in overall geometry, are in detail generally narrow, multi-veined and fluctuating in width, strike and dip. Tight geological control is required to optimise gold and silver production from this bench stoping operation. The processes used to model the resource and to control ore drive development have evolved since mining commenced in 1997. Grade control is a combination of orebody sampling, geological data collection, understanding orebody geometry and the optimisation of ore driving and stoping activities. Global resource modelling utilises mainly drill hole data which is largely superceded by drive development data as stope development progresses. The orebody has a relatively low nugget effect that assists in grade estimation. Rather than rely on sophisticated grade interpolation methods, resource estimation to-date has focussed on developing the geological understanding of the orebody to ensure the framework for estimation is correct. Drill data alone is not adequate to define deposit geometry for stoping . Drive data is used as the dominant data set for stope geology modelling once development for a stope is complete.

Jan 1, 2000