Search Documents

By Knight J. L, Baker G

The Wonthaggi coalfield is in South Gippsland, about 90 miles southeast of Melbourne. It is situated on the down-faulted block of the South Gippsland highlands that lies south of the Kongwak fault, between the Powlett River and the sea (Fig. 1). The coal, which is of Jurassic age, occurs in two small, and intensely faulted, limnic basins, that lie on either side of a concealed ridge of Silurian sediments. The coal was first found as thin seams outc1'opping in the cliffs at Cape Paterson, but the seams that are worked at Wonthaggi are concealed beneath a veneer of Cainozoic sands that covers the Jurassic strata, and were found by boring.The c9al seams are worked by the State Coal Mine, which was opened in 1909 to ensure a supply of coal for the Victorian railways, following a prolonged strike in the Newcastle field of New South Wales. The total production from 1910 to June, 1943, amounts to 13,918,800 long tons of coal. The coal seams are faulted to a degree unknown in most coal...

Jan 1, 1944

By Lloyd F, Bayley F. J

The new South Mine in the Western Deep Levels complex is destined to become an ultra deep project extending to depths of 4 200 m below surface and where rock temperatures are likely to exceed 65 ¦C. Initial estimates put refrigeration requirements at 133 000 kWR. A surface refrigeration plant with an initial capacity of 42 000 kWR has been commissioned and will be used for mining the upper levels.

Jan 1, 1988

Supercritical fluids are gases compressed to near liquid densities and, as such, have unique properties compared to liquids: low viscosity; zero latent heat; high diffusivity and pressure-dependent, solvation characteristics. These properties are being utilised in new processes and current research is delineating areas where such processes may be applicable to extractive metallurgy. The processes and areas of interest are as follows: Supercritical Fluid Extraction in which substrates are dissolved at high pressure and fractionated at successively lower pressures. Areas of interest include extraction of organic materials for regeneration of activated carbon for the CIP process and for upgrading alumina industry products and, separation of transition metal chlorides. ò Supercritical Water Oxidation in which high pressure gaseous water acts as a medium in which substrates are oxidised while suspended or dissolved. This process may be of use for oxidation of organics in Bayer liquor and oxidation of mine waters etc. ò Supercritical Fluid Reactions where reactions occur in a supercritical fluid medium, particularly when the medium itself is a reactant. This may be of use in treating refractory or carbon-aqueous auriferous ores and in lower-temperature chlorination of transition metal oxides. Research is described which is aimed at chlorination and separation of transition metal oxides by two supercritical operations.

Jan 1, 1991

Zinc alloy castings continue to account for a very large, world-wide end-use market for zinc. However, an ever expanding multitude of other materials and processes are increasingly providing viable, cost-effective alternatives to designers, many of whom have no particular allegiance to any one industry. In order to meet this challenge, innovation of and for the zinc hot chamber pressure die casting process, in concert with sustained and inventive market development, is clearly required. While 'Quality' is now the watchword, and the goal of zero defects is being rigorously pursued, other important goals which must be addressed include net shape casting, enhanced productivity and increased energy efficiency. The paper gives an overview of several practical, process-orientated, projects designed to help achieve these goals. For example, a project designed to understand and precisely measure dimensional changes of castings with time has provided some of the critical information needed for net shape casting. A second study is looking anew at surface quality in relation to process conditions as an important step toward the goals of zero scrap rate and increased productivity. Developing the correct die casting machine parameters for achieving optimal quality and properties of zinc (ZA) die castings is a further example of research designed to benefit both the die caster and his customer, chiefly the original equipment manufacturer (OEM). A project on die soldering or galvanising in response to varying process parameters is similarly being considered in order to foster increased understanding and avoidance of problems, with a special interest in the use of special coatings. The maintenance or expansion of the future market for zinc die casting alloys also depends on design for functional applications, as an adjunct to their traditional decorative use. The role that alloys with enhanced properties can play, such as ZATEC, a new high creep resistant alloy developed specifically for elevated stress/elevated temperature applications, will be briefly discussed.

Jan 1, 1993

By Mroczek C. R, Evans D. A

Renison is a world-class ore deposit that has been mined for over 100 years. It currently has reserves of 5.06 Mt @ 1.88 per cent Sn and a projected mine life of 8.5 years. Recent advances in the geological understanding of the deposit have been associated with detailed structural and geophysical investigations accompanied with the discovery and exploitation of the Rendeep orebodies. Mineralisation is linked to the forceful emplacement of the Devonian Pine Hill Granite that resulted in a complex brittle (-ductile) deformation of the Eo-Cambrian host stratigraphy. Dilation jog development on the Federal-Bassett Fault in the Federal and Rendeep areas provided access for cassiterite-rich magmatic hydrothermal fluids responsible for carbonate replacement Mineralisation.

Jan 1, 1997

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

Evolutionary changes to the original sizer concept are mild when compared to those which have taken place in the engineering standards embodied in today's commercially available machines. This paper examines the principles of sizer operation and reviews the development trends in new applications for this unique screen type.

Jan 1, 1978

The 1980's have produced an outstanding revival of the Australian gold industry. In contrast to some previous mining booms, the economic aspects of the growth in gold production are soundly based. In general the new developments have been highly profitable and this is beneficial to all parties- whether they be government, shareholders employees or suppliers. Mining companies are showing a large commitment to gold exploration with approximately 50% of Australian exploration budgets now being directed towards gold. An increasing proportion of this expenditure is being channelled towards the eastern States with Queensland 'being the major centre of interest. Further strong growth in production is expected with some 50 projects likely to come on stream before 1990. A very significant aspect of the foundation for this growth is a continuation of the existing tax status of the industry.

Jan 1, 1987

The present Pacific Ocean arose from rapid sea-floor spreading that commenced in the late Mesozoic, and continues to the present day. It started within what is here called the Medusa complex of seaways, basins and troughs with spreading ridges and volcanic arcs, that girdled the earth, including the Palaeotethys and Neotethys of Eurasia between Gondwanaland and Laurasia. Detailed mapping and analysis of palaeofaunas and volcanic arcs indicate that several seaways, rather than one or two, extended throughout Tethys, and into areas now occupied by the Pacific Ocean. The Medusa complex developed under a long sustained wrench regime, right lateral at least from New Zealand to Eur.ope, and saw the origin, maturation and closure of elongate and oval basins under erratic sea-floor spreading, in which no Eulerian pole of rotation remained fixed for long. The name Medusa stems from the analogy of snake-like writhing hair to the constantly shifting development of basins and orogens within the complex. The Indian Ocean split and opened up Gondwanaland concomitant with the later development and deformation of the Tethyan segment- of Medusa, whereas, to the east, the Pacific Ocean opened within Medusa itself, and dispersed Medusa around the rim of the Pacific through sea-floor spreading and strike-slip faulting.

Jan 1, 1987

By Johns A. L

The concept of the Melbourne Underground Rail Loop and the organ- isation to achieve its construction are covered in the companion papers (Reference 1, 2) and will not be repeated here. The Victorian Railways, as well as being the eventual operator of the Loop when it is completed by MURLA, have also been responsible as "Contractors" to MURLA for the construction of the "cut and cover" or "box" tunnels and related approach works located on existing Railway property. These tunnel connections link the existing suburban system to the new underground works. The following tabulation indicates the significant work volume involved in this cut and cover tunnelling exercise and which is covered in some detail by this paper.

Jan 1, 1981

Proposals for engineering works in the River Dement in recent years have been made in the context of very little geological informat- ion. Breakage of the Tasman Bridge, forced a complete re-appraisal and collection of inform- ation in order to select a new site and predict problems. Seismic, magnetic and gravity methods foll- owed by drilling have allowed an assessment of the nature, thickness and distribution of mater- ials underlying the river bed. Key discoveries included recognition of low seismic velocity silts (1100 m/s) and a separate channel for the river since the Late Tertiary.

Jan 1, 1977

By Chenggang W, Junhua D

Fragmentation variation laws in loading and non-loading areas are obtained by cement block model blasting experiments under various stemming lengths. A reasonable ratio between loading length and stemming length is worked out according to minimum average fragment size. The present continuous loading structure, for its very long length to be stemmed, leads to insufficient fragmentation in the upper part of bench. So a new loading structure with bottom air cushion is put forward. The author analyzes blasting effects and processes of two loading structures' and proves that there exists a optimal length of air cushion.\

Jan 1, 1990

By Bukovinsky SB

The smelting, refining and hydrometallurgical operations practised in the winning of non-ferrous metals are associated with severe aqueous and high temperature corrosion problems.With the increasing costs of maintenenace and the utilization of computerization to control the processes, the trend in recent years has been to spend more capital on improved and proprietory grades of engineering materials, which offer greater reliability and more cost effective plant performance.The problems which have plagued stainless steel users for many years are the alloys' poor performance in chloride or other halide media where pitting, crevice or chloride induced stress corrosion cracking may occur, have been essentially solved by the new proprietory grades. The controlled additions of minor alloying elements including rare earth metals have led to the development of stainless steels with high mechanical strengths, improved corrosion resistance, and high temperature corrosion resistance and structural stability.

Jan 1, 1985

Drill and blast excavation in underground mining and. civil engineering projects has grad- ually given ground to mechanical boring of tun- nels, shafts and raises during the past twenty years. The use of.boring equipment must today be considered significant and wide spread al- though comprising only a very small percent of total underground excavation. The encroachment of mechanical boring into the domain of blast- ing has been by slow incremental advances. There have been few, if any major breakthroughs in this development, and none can be foreseen in the next decade. After 1990 it is possible that scientific. development will provide some form of breakthrough in rock breaking, but this is so uncertain that it should have little relevance to planners in the 1980's. A more near term view of the future, con- centrating on the next five to ten years, has lead to the conclusion that significant im- provements will be seen in tunnel borers for poor ground conditions. A universal machine will be developed that converts from a dry hard rock machine to a closed slurry type machine for passing through fault zones with unstable crushed rock and water. Two other machines have been described as alternate designs for tunnelling in squeez- ing ground conditions.

Jan 1, 1981

The investigations described in this paper aim at the development of a new impact mill. The objective is to produce particle size distributions below 10 .tm without using an air classifier. Circumferential rotor speeds of up to 200 m/s are strived for.

Jan 1, 1993

By Mallett CW, Hammond RL

Geological maps of the Pacific Rim recently published by the Circum-Pacific Council for Energy and Mineral Resources have provided a useful perspective from which to view modern plate interaction and the evolution of modern fold belts. An important lesson from any study of modern plate interaction is that of the normality of change. The chaotic is more usual than the simple. Present day convergent margins with mixed characteristics are measures of this chaos. Indeed, the character of less than one third of the present length of the Pacific Rim can be ascribed to conventional models of plate interaction. Another lesson is that of the great mobility of oceanic crust. Enormous areas of the Pacific may not be represented in future fold belts developed at convergent boundaries unless normal consumption processes are disrupted, and even then only by linear zones a few kilometres wide. The axes of divergent boundaries creating Pacific Ocean crust have been equally mobile, with new spreading sites taking over from older sites through time. Divergent boundaries, whether active or inactive, consist of oceanic crust, and may be wholly consumed at collision sites with convergent boundaries. Their only potential contributions to fold belt evolution are transforms and magmatic activity. It is this transform component that can provide us with a mechanism to explain the apparent contradiction of both compressional and extensional features occurring together in a developing fold belt. Reconstructions for the SW Pacific are used to demonstrate that the fold belts under construction during the last 4% (Jurassic- Recent) of geologic time have involved interaction between convergent, divergent, and transform boundaries. In the last 15% of earth history (Late Proterozoic-Recent), many enigmatic features of the geologic landscape in Eastern

Jan 1, 1987

By Okabe K

Development in the theory and practice of hearth drainage is reviewed. Difficulties in the hearth drainage were re- newed during late sixties and early seventies when the size of a blast furnace and the top pressure were increased to result in the increase in tapping rate. Hearth drainage was improved first by in- creased number of tapping and then decreased tapping rate as it was predicted by theoretical studies. State of the coke bed in the hearth, e.g., 'floating' or 'sitting-on' the hearth bottom, is discussed in relation with influential factors on it and its influence on the furnace operation. The 'sitting-on' coke bed is to be aimed at for the consistent furnace working and for the lower rate of erosion of the hearth refractory. As the continuous tapping became standard prac- tice in large blast furnaces, the interest in the basic research renewed. Prospect of the further research including mathematical modelling of the hearth drainage is discussed.

Jan 1, 1981

Both safety and productivity in underground gassy coal mines can be improved substantially if an appropriate gas management system is introduced. A strong direct relationship exists between the gas emission rate, roof and floor strata relaxation zones characteristic, mining activities and gas drainage practices. Detailed knowledge of geological factors, gas and coal-rock properties, as well as mining systems are necessary for the methodology used in predicting overall underground gassiness, and planning gas capture and ventilation systems. Early gas emission calculations for various mining activities, particularly for the longwall mining system are essential. A reasonably accurate prediction of gas make as well as the design of ventilation, gas recovery (drainage holes) techniques can be made using 'Floorgas' and 'Roofgas' computer simulations, provided sufficient geological, mining, and gas data are made available.

Jan 1, 1998

By Braaksma M, Dudley K

The Girilambone Copper Mine is located in central New South Wales and has been operational since May 1993. Girilambone is operated by the Girilambone Copper Company (GCC) which is a joint venture between Straits Resources (60 per cent) and Nord Resources (40 per cent). The mine complex consists of an open cut pit, ore crushing and stacking, heap leaching, solvent extraction (SX) and electrowinning (EW) allowing for the recovery of 14 600 tpa of LME grade A cathode copper. The leaching and SX-EW plant have been described previously by Rear, Taylor and Busby (1994) and Miller (1994).

Jan 1, 1996

By Szymanski J

Although efforts towards producing a `total quality rockfill product' have allowed cemented rockfill costs to be reduced considerably, there is still tremendous potential for further cost reductions. Cemented rockfill costs range from approximately $7 to $12 (US) per tonne of fill placed. Approximately 50 per cent of the rockfill costs are associated with cement costs. A large portion of the remaining 50 per cent is associated with labour and materials handling costs. Several Canadian underground mines utilise haulage trucks and/or conventional belt conveyors to distribute the rockfill. However, due to the restrictive nature of the underground environment, these current materials handling systems have limitations (ie spillage from trucks, dust from conveyors). The Sicon conveyor system (developed in Sweden) has considerable potential for replacing these current methods. The Sicon conveyor utilises a revolutionary approach - the conveyor belt is folded over upon itself (forming a tear drop shape) so that the transported material is completely encased within the belt. The Sicon conveyor's ability to negotiate very tight comers (without transfer points) makes the conveyor very appealing for underground mining applications. An analysis comparing the pros and cons associated with the Sicon conveyor system versus conventional materials handling systems will be presented in this paper.

Jan 1, 1995