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By Onton W

During the latter part of 1936, conditions encountered in sinking the Main Ore shaft made it impractical and uneconomical to continue deepening it to serve haulage levels below the present No. 5 level. Plans were therefore made for an interior shaft, to serve new lower levels, that terminated above No. 5 level so that ore hoisted could be drawn off on this level and transported to the Main Ore shaft for final conveyance to the mill crude ore bin. The No. 2 interior ore shaft was only developed below No. 4 level and borehole ropeways with a winder located on the surface were installed in preference to an underground winder installation. No. 2 ore shaft with borehole ropeways commenced lead ore hoisting operations in September 1938. Apart from the copper ore hoisted in the war years of 1943-46, lead ore was hoisted to No. 5 level until September, 1951.

Jan 1, 1988

By M Noy, P Hawkes

Improvements in the drill and blast process can impact on loader performance in a number of ways. The main effects being improved loading cycle times, less non-productive cycles such as oversize removal, clean-up and face raking and better bucket fill factors. The impact of improved loading cycle times on the overall cost and productivity of the load and haul cycle is very much dependent on the loader truck match and the management of the haul fleet. Previous work has shown that a 20 per cent improvement in dig cycle times may only lead to three per cent or less improvement in the overall productivity of the load and haul process. However, improving the mass loaded per pass by five per cent will lead to a five per cent improvement in productivity for any given haul fleet situation, assuming sufficient truck capacity. Work by Orica Explosives at Lab ChrysotileÆs Thetford Mine, Quebec, Canada showed a relationship between muckpile fragmentation and truck payload. With this in mind, work was carried out to determine the effect differing muckpile fragmentation distributions can have on excavator bucket fill factors. This work was performed in the laboratory to a 1:100 scale. Nine different distributions were used. These were characterised by the Rosin Rammler parameters, xc the characteristic size, and n, the uniformity index. The values of xc and n used were modelled on those previously measured at a Sydney quarry. For the range of distributions measured, it was found that the fill factors were lowest at a low characteristic size and a high uniformity index and highest at a high characteristic size and a low uniformity index. In other words the best fill factors were achieved with a more dispersed muckpile distribution with a larger characteristic size. The difference in fill factors was 16 per cent indicating that controlling the drill and blast process to produce a specific muckpile distribution can have a significant impact on the overall cost-efficiency and productivity of the load and haul process. Field measurement by Orica Explosives at a quarry in Canada supports this conclusion showing improvements of up to seven per cent in average bucket load by either increasing the characteristic size or decreasing the uniformity index of the muckpile.

Jan 1, 1999

By Ehlers HK

Mount Isa Mines Limited has 25 rod and ball mills of various sizes installed in two Concentrators at Mount Isa. A continuing investigation into installation, design and materials of liners for these mills has been in progress since the early sixties. Both manual and mechanical methods of liner installation are used and described. Materials for the various applications have been evaluated, mainly by field trials. Design of liners has also been evaluated by field trials and the history of trials in No.4 Concentrator is given. The purpose of the investigation has been to reduce the cost of mill lining and the life of many linings has been greatly increased as a result of this work.

Jan 1, 1978

Blasting effectiveness must be gauged by total production costs. ANFO charges made up in polythene "sausages" are not as profitable as is indicated by the price of ANFO. All-slurry charges are warranted only where blastholes cannot be dewatered effectively, or where drilling costs are very high. An increase in blasthole diameter leads to coarser fragmentation. This effect is most pronounced in tough and massive or blocky strata, or in ground which consists of unfissured boulders in a softer matrix. When ANFO and some slurry-type charges of small diameter are used in plastic-acting ground, charges may fail to detonate through precompression by charges fired on an earlier delay. The optimum blasthole length is rarely less than four times the burden distance. For best results, blastholes should be inclined to the vertical and parallel to the face. Nominal burdens and spacings are often altered radically by the initiation sequence. For best fragmentation, all blastholes must have good effective faces, and should be effectively stagg- ered with an actual spacing:burden ratio in the approximate range 2.0-5.0.

Jan 1, 1975

THIS paper is not intended to be more than a mere outline of the economic geology of Tasmania. It is desired to present in a condensed form the present state of our knowledge in regard to the distribution of the ore, coal, and oil-shale deposits of Tasmania in time and space.Tasmania is exceptionally well endowed with mineral wealth, particularly in the north-western and western districts. In the enthusiasm resulting from the first discoveries of mineral deposits at a great number of localities in those districts, it became a generally accepted belief that the whole of that portion of Tasmania constituted a continuous metalliferous province. As geological research in these, areas has progressed, however, it has become increasingly clear that ore-deposition has been confined on an economic scale to definite well-defined areas or belts which have a genetic relationship to certain tectonic and petrologic phases of the general geology. These areas or belts have recently been defined by the writer, and...

Jan 1, 1923

By G Johnson, G W. Wilson

The settlement and drainage behaviour of co-mix, or mixtures of waste rock and tailings, are examined in a column study. Three co-mix profiles were observed for settlement, drainage, and pore water pressure response. A fourth profile with waste rock and no tailings was also observed for settlement. Co-mix consolidated faster than predictions for tailings alone, and maintained a saturated void space relative to waste rock alone. Practical benefits of co-mix as a waste disposal technology may include faster time to consolidation than tailings, a reduction in total settlement of placed material compared to tailings alone, and a reduction in acid drainage by limiting the flow of water and oxygen through maintenance of a saturated void space.

Jan 1, 2003

Historic mining across the Bendigo goldfield reached an average mining depth of 750 m over an area of about 16 km by 4 km, with two shafts exceeding 1400 m. Mining ceased in the mid 1900s due in part to increased dewatering and ventilation demands. Water extraction technology of the day, combined with multiple mine ownership, did not allow uninterrupted and thus economic mining activity to prosper. Today Bendigo Mining Limited (BML) is targeting gold-bearing reefs beneath the water-filled historic mine workings. To ensure mining activity can proceed without the risk of water inrush, historic workings are being dewatered by submersible pumps in historic shafts and through a series of underground drain holes intersecting old workings. Due to the high heads involved, individual drain hole development requires rigorous safety control implementation and assessment prior to drilling. Water extracted via drain holes is pumped to the surface through a series of pipe lines and rising mains in conjunction with two staged pumping stations. Both stations are equipped with high-speed centrifugal pumps, each capable of pumping 40 L/s at a static head of approximately 300 m. BML, which operates beneath and within a large city, is confronted with unusual environmental and social challenges compared to many within the mining industry. The raw mine water, which contains elevated salt levels, is piped through residential areas and must comply with strict controls to prevent impacts on the surrounding environment. The final delivery point is BMLÆs water treatment plant at the north end of the city. The water treatment plant utilises chemical pretreatment and reverse osmosis. It is able to process 7 ML of mine water per day at full production. The product is approximately 5 ML of reusable irrigation quality water, which is made available to the Bendigo community for public gardens, sporting facilities and rural irrigation. The 2 ML of brine is directed to a purpose-built evaporation pond facility located 7 km north of the water treatment facility.

Jan 1, 2008

There are two main areas of application of geology in quarrying: (i) In regional planning for industrial mineral requirements.(ii) In direct quarry management. The regional planning requirement has recently become more evident because of greatly increased land demand conflicts around cities. The direct quarry involvement is a reflection of both the economy and the greatly increased sophistication of the quarry industry. Here, professional planning and development expertise by a geologist is required, to ensure continued supply of raw materials at the best price to the consumer with sufficient profit to the producer. Today, geological insurance safeguards capital investment in plant and assures economical development plans.

Jan 1, 1978

Over the last decade mineral exploration in New South Wales has increased markedly. This is due to various factors including the influx of overseas companies an. capital, increase and stabilization of metal prices and improvements in exploration techniques. The initiation of full-scale petroleum exploration and recent discoveries of large mineral deposits in the west, north-west and north of Australia has increased overseas capital, and brought scientists and technicians into the country. Naturally there has been an overflow into New South Wales, which is less attractive as an area for new and large-scale discoveries. In some fields, rise in metal prices and price stabilization has largely contributed to the intensif- ication of exploration. Increased tin production in New South Wales since 1963 is a direct result of price rise and stabilization, and rise in the price of silver has revived an interest in silver prospecting in recent Years,

Jan 1, 1969

The limitations of the conventional practices, and their effects, in prospecting for and in the evaluation of alluvial gold deposits are briefly reviewed. Geophysical prospecting methods have demonstrated their complementary role in the delineation of deposits by reducing the number of boreholes which are primarily of a 'probing' type. Larger diameter boreholes, although more expensive on a linear basis, are much cheaper on a volume recovered basis. The need to have sufficient volume as well as number of samples is stressed. Classical statistical methods are not appropriate for such deposits as there is sufficient structure, or spatial correlation, to require the application of geostatistics. Quite reliable semi-variograms, but not in all cases, of the spherical scheme have been obtained. Subsequent kriging has, to date, been confined to unworked deposits: retrospective estimates to compare to production have not therefore been produced. However, the technique shows promise but indicates a considerably greater borehole density (of the conventional diameter) may be necessary to produce confident estimates. Used in conjunction with larger diameter boreholes, a lesser borehole density may be sufficient, through radical reductions of the sampling error.

Jan 1, 1977

Reconciliation of the ore reserve has been an integral part of mine planning since Bougainville Copper Ltd. commenced mining operations at Panguna in 1972. Confidence in the ore reserve is considered essential, both for long term planning of the deposit, and for fair and accurate reporting of the mining resource to shareholders. Recoverable, proven reserves are published annually. Although the ore reserve quoted is based only on diamond drill hole (DDH) information on a 122 metre by 122 metre grid, predictions are regularly reviewed against production. Concentrator results are taken to be the best estimate of grade and tonnage. Surveyed mined perimeters and average blasthole grades are reconciled at the end of each month against the concentrator figures. Predictions of the in-pit reserve are made using an orebody model. DDH and blasthole (BH) sample grades are used to make predictions for both long and short term planning. This paper describes how reconciliations are used to validate ore reserves at Panguna. Development of the orebody model is described, and some of the difficulties encountered in doing reconciliations are addressed.

Jan 1, 1987

While international coal trading operations often involve relatively small contract quantities, delivered over short periods or even in single shipments, most coal is supplied under long term arrangements. In entering into these arrangements the customer needs to be assured that coal of suitable and consistent quality can be supplied for their duration in the volume required. A detailed knowledge of the mine and transport system is required and must be presented from the customer's perspective.

Jan 1, 1983

Studies of the morphology of seamounts within the Hawaiian, Line Islands, Gilbert and Phoenix Seamount groups indicate that the morphology and size distribution of seamounts vary significantly from one seamount group to another. The Line Islands group appears to be the most complicated of all the groups studied thus far. This group is complicated by reactivation of volcanism, which has superimposed volcanics on sedimentary rocks. These seamounts display abundant volcanic features on their summits. Seamounts within the Hawaiian seamount chain display a marked absence of volcanic features due to the . presence of thick carbonate caps. Reef platforms and sealevel benches are very common on these seamounts but are absent from seamounts in most other seamount chains in the central Pacific. Slope angles vary regionally between seamount groups. The minimum slopes are found on Necker Ridge in the central Pacific basin. The maximum slopes are found on ridge-crest seamounts. Roughness increases proportionally with mean slope angle.

Jan 1, 1987

By T Kang, V Sahajwalla, L Lu

During devolatilisation, physical behaviour of coals was investigated in horizontal electrically heated furnace with an inert gas atmosphere, and gasification rates of four coal chars and coke were measured thermogravimetrically in a carbon dioxide atmosphere at temperatures in the range 1100oC - 1500oC. The volume change of chars was also measured in horizontal electrically heated furnace at various temperatures. Both reactivity and the activation energy for the gasification of coal chars were found to be strongly influenced by pore structure and the carbonisation conditions employed during preparation. CO2 reactivity of chars increases with increasing reaction temperature, and particularly increases more rapidly over 1300¦C. CO2 reactivity of coke is lower than that of non-coking coal chars in the range of 1100¦C to 1500¦C. CO2 reactivity of chars with smaller pore area and bigger pore diameter is less than that of chars with bigger pore area and smaller pore diameter. During gasification, the volume of chars did not change significantly at the lower temperatures of 1100¦C and 1200¦C, but at the high temperatures, 1300¦C to 1500¦C, the volume of chars quickly decreased due to ash softening and melting. The CO2 reactivities of the chars are controlled by the mixed control of chemical reaction and pore diffusion in the temperature range 1100¦C to 1300¦C, and by bulk diffusion in the temperature range 1400¦C to 1500¦C.

Jan 1, 2000

Computer simulation of the control systems for the heavy media coal washing process have been presented in this paper. The simulation model applies the Simulink module of the Matlab 5.1 software package and allows monitoring of variations of a

Jan 1, 1998

By Giannini L. M

Optimisation techniques, based on the block model, for solving the optimum pit limit problem were discussed in an earlier paper. Of the available techniques the one based on graph theory proved to be the most attractive. In the graph theory model the vertices represent blocks and the arcs represent the mining restrictions. For large ore-bodies direct application of the graph theory method poses considerable computational and storage problems. Techniques for easing the computational effort by reducingthe problem size were introduced in an earlier paper. Further, significant computational savings can be made by exploiting the structure of the graph. This is done by building the graph up level by level and successively applying the graph theory algorithm to reduce the number of blocks. In building up the graph in this way one needs what is called a "search pattern" to indicate which arcs are to be added as new vertices are introduced. Moreover, as it is essential to keep the number of arcs to a minimum it is necessary to establish a "minimum search pattern".The problem of determining minimum search patterns for any block model and for any wall slope restrictions has not been considered in the literature.The objective of this paper is to present a complete solution to this problem and to discuss, through typical case studies, the application of the associated software developed.

Jan 1, 1988

The latent conditions clause in various general conditions of contract have traditionally proved to be a source of significant disputes in tunnelling contracts, even when extensive geotechnical investigations have been carried out at the tunnel site and a report of these investigations provided with the tender documents, informing the contractor of the nature and extent of subsurface conditions likely to be met with during execution of the works. This paper discusses the contractual aspects of the new latent conditions clause in the recent Australian Standard AS 2124-1986, General Conditions of Contract, in relation to tunnelling contracts. A comparison of this new clause is made with other latent conditions clauses in general conditions of contract in use in Australia and other commonwealth countries. It is seen that the new latent conditions clause in the recent Australian Standard 2124-1986 has, by providing for a reasonable apportionment of risks, attempted to minimize contractual disputes relating to latent conditions in tunnelling contracts and to provide a satisfactory basis for quick and efficient settlement of such disputes should they arise during execution of these contracts.

Jan 1, 1987

The old Trekelano mining area is situated in the Cloncurry Gold and Mineral Field 14 km east-south-east of Duchess. It connected with the main Cloncurry-Dajarra railway line by a private line from Juenburra, a distance of 10 km. The distance by rail from Townsville is 561 km. The area was first mentioned circa 1902 - 1903 when a very short report said, that a Tony Allis had taken a parcel of copper ore out of a mine which, he called æThe InheritedÆ. After that report, nothing further was printed until about 1906, when traces of copper were noticed on a wagon track going to Kiama Well. The Trekelano deposit did not outcrop, with the cap covered by about two metres of soil. The deposit was named after an early pastoral holding. The early prospectors were however disappointed by TrekelanoÆs low copper grades, approximately five per cent Cu. This is understandable when, in those days, about 25 per cent was the cut-off grade for mines in the district. Meanwhile, The Hampden Mining and Smelting Company were constructing a smelter to treat their sulphide ores at Kuradala that was replacing their high grade oxides ore. By about 1910, the Hampden Mining and Smelting Company was experiencing smelting problems, and needed suitable oxidised copper ore to blend with the Kuradala pyritic ore. Someone must have remembered the Trekelano low-grade oxides, resulting in agreement to mine and cart the ore to Duchess, from where it was railed to Hampden, as Kuradala was known at that time.

Jan 1, 1998

By Pell D

Mechanical cleaning of coal was porforined in a few small plants in New South Wales from 1577 brit the first large coal washeries were built by Broken Hill Wbprietary Company Limited and Australian Iron and Steel Pty. Limited in the late 1940's. Mechanization of colleries in the 1950bs was abcomp" anied by construction of many coal washing plants and in the 1960's the growth of the coal export trade gave further impetus to the coal preparation industry. Design of coal preparation plants in Australia is modelled on practice overseas. Planning of a new plant in- volves investigation of many factors both technical and economic and the preparation of a specification by the operator for the designer's guidance. A wide range of preparation processes and equipment is on offer, but the nature of the coal to be treated and the separating efficiency desired usually dictate process selection. Simple or moderately difficult separation can be achieved with jigs, shaking tables or water washing cyclones. Coal which is difficult to treat or which has to be cut at a specific gravity lower than 1.5 is normally washed in a heavy medium process. In large plants it is usual to separate the coal into large, small and fine fractions and concentrate each fraction in a circuit designed to suit the grain size handled.

Jan 1, 1969

Interactive data exploration is essential for visualising grade distribution and geological controls on orbodies. Quick and appropriate computer techniques for making daily 'value adding' decisions include routine imaging of numerical data suc

Jan 1, 1998