Search Documents

By Jensen B, Ofori P, He Y, White E, Stanmore B, Brien M, O&apos

As part of a large AMIRA project, an on-line moisture meter was installed at two mine sites in Central Queensland. This project investigated the factors which control the moisture content of coarse (>0.5 mm) coal from the centrifuges used in conventional coal preparation plants. It was placed immediately after the first centrifuge to isolate the factors pertaining to one machine and its feed.The meter was found to be accurate and precise when compared with manual and mechanical sampling methods. The Grubbs estimator technique indicated that its precision is better than 0.3 per cent at the 95 per cent confidence limit.It has been identified that:1. the variability of the measured moisture contents of coarse coal can be described by normal distributions. Standard deviations of about 0.6 per cent are common; and2. the treatment of the coarse coal on the drain and rinse screens immediately prior to the centrifuge can affect the final moisture content.

Jan 1, 1995

By Khosia NK, Ravishankar SA, Sankar TAP

Alumina reduction in Rajhara iron ore slimes essentially involves separation of hematite from gibbsite in relatively coarser fraction and from kaolinite in the finer fraction. Selective dispersion flocculation studies on synthetic mixtures clearly indicated that while it was possible to achieve almost perfect separation of hematite from kaolinite using starch and PAMX (modified polyacrylamide containing hydroxamate functional groups) flocculants, no selectivity was observed in iron oxide-alumina system. A schematic flowsheet suggested on the basis of this work for the beneficiation of Indian ore slimes thus consists of classification in a hydrocyclone, followed by selective dispersion of coarse fraction (underflow) and selective flocculation of the overflow fraction. Starting with a feed assaying 46 per cent Fe and 11.6 per cent A1203, a concentrate assaying 60 per cent Fe and 4.7 per cent A1203 could be produced at an overall iron recovery of 60 per cent using conventional Reagents.

Jan 1, 1993

The Mt Leyshon Volcanic Complex lies 24 kilometres south-west of Charters Towers and is part of a major continental volcano-plutonic province of Permo-Carboniferous age in north-east Queensland.The volcanic complex is located on the contact between Cape River Beds of Cambrian age and the Ordovician Ravenswood Granodiorite Complex. The emplacement of the complex appears to have been structurally controlled and is at the intersection of major north-east and minor north-west trending lineaments. The gold mineralisation occurs in the form of cavity coatings, matrix replacement, disseminations, and vein and fracture fillings containing quartz, chlorite, carbonate, pyrite, sphalerite, chalcopyrite and galena in various volcanic breccias and rhyolitic intrusives. The current published mineable ore reserves, calculated by Noranda Australia Limited, are 6.3 million tonnes of 1.8 grams per tonne gold and 4.8 grams per tonne silver. The orebody is open at depth, and in all directions except north where it abuts the granodiorite.

Jan 1, 1986

By Wang J, Ma Y, Jia H

The Hedong Gold Mine is located in the Yan(ai area, tihandong hroo%ill, e. China. It is an underground mine with an annual gold output of some 700 0(H) grams. The orebody is located on the edge of the Wanger Shan metamorphism zone, and the hangingwall of orebodies is thus defined by a prominent set of fractures. The proximity of the metamorphism zone and the inclusion of the fracture set ensure that both the orebody and the country rocks are unstable. The main orebodies dip at an angle of between 40 to 45¦, with a strike length of 160 metres and a horizontal width of 50 metres. Surface subsidence in the area is not permitted. Cut and fill mining is usually practiced. As the mining operation proceeds to greater depths, the ore grade is diminishing and it is necessary to find a more efficient stoping method. Sublevel open stoping with sequential extraction and filling of each sublevel has been designed and applied in situ. This new mining method is called 'sublevel open and fill stoping method' in the mine. Experience to-date is that new mining method is Satisfactory.

Jan 1, 1998

By Kapoor M. L

EMF measurements were performed in the temperature range of 933-1095 K to determine the thermodynamic properties of oxygen dissolution in liquid lead and lead-tin alloys with tin in the dilute concentration range of 0 to 6 atom per cent. The oxygen in the Pb-O system was varied by equilibrating with (PbO) slag, and that in the Pb-O-Sn system was varied with the addition of lead oxide. Wagner's interaction parameter approach was used to evaluate the self interaction parameter and ternary interaction parameters at different temperatures, to yield: E8(pb) = 97.35 - 113.27 x 103/t Eo(pb) = 139 - 20.616 x104/1' Quasichemical formulation was employed to yield Inf to reveal the effect of tin on oxygen in lead. Results have been predicted on the basis of classical models and those obtained using the QCT approach of Alcock and Richardson at Z=2 have been found to agree with the experimental Data.

Jan 1, 1992

A study of the bacterial oxidation of naturally occurring high-purity sulphide minerals (FeS2, Fel_xS, CuFeS2, Cu2S) has been conducted using a mesophilic strain of T. 6ejtAooLcdcth4. As well as metal analyses and solution pH, partitioning of sulphide sulphur into elemental sulphur and sulphate ion has been monitored. Partially oxidised sulphide substrates have been characterised at regular time intervals by X-ray diffraction methods and extra-cellular organic compounds reporting into leach solution have been identified by'thin layer chromatography. The results indicate that the S¦/SO4 2 partitioning of the sulphide substrates is independent of cell inoculum size and initial pulp density and varies with solution pH, Eh, leaching time and mineralogical properties of the individual sulphide minerals. The signifi- cance of results for applications in selective flotation, coal desulphurisation and agglomera- tion has been outlined.

Jan 1, 1984

Mount Isa Mines Limited has been mining copper ore for 50 years. In recent years, this production has been entirely by open stoping methods with cemented backfill, mostly in the large 1100 orebody.This has been the major ore source for 20 years, with smaller amounts coming from the 400, 500, 650 and 1900 orebodies. At present, the 1100 orebody is the only source, and this situation will continue until the deep 3000 and 3500 orebodies begin producing in late 1992/93. Production rates have increased to almost 6 Mt/yr, and are planned to rise to 7 Mt/yr by 1995/96. In the future, there will be a move towards variations of the open stoping system as production moves to more lensy zones of the southern 1100 orebody and to the deeper 3000 and 3500 orebodies. This paper describes current operations in the 1100 Orebody, with some indications of future directions.

Jan 1, 1993

With the recent wider introduction of friction hoists of the Koepe type. for winding from depths of more than 3000 feet it has been found that failure by fatigue is the most common form of rope deterioration. Large numbers of wire breaks occur near the centre of the rope cross-section and it is difficult to detect these with certainty using the preferred d.c. magnetic test. For best results with conventional search coils their dimen- sions should be related to the typical wire break field pattern surrounding the longitudionally magnetised rope. The field of a broken wire was experimentally determined, using a Polish type MD6 Defectograph wire rope testing magnet and a short prepared length of rope with a movable simulated broken wire. The external field distortion perpendicular to the rope was measured by means of a gaussmeter and Hall probe. The advantages of this method are that terrestial magnetism and inherent rope "noise" have no effect on the results.

Jan 1, 1971

By Baafi EY, Appiah HK

The Prestea Goldfields Ltd of Ghana, West Africa has produced over 170 t of gold with average grade of 11 g/t since 1912. The deposits occur in a wide shear zone which closely follow the Birimian-Tarkwaian contact. Both the Birimian and Tarkwaian systems are of Precambrian age. Underground exploration is carried out to delineate ore bodies by means of AX size diamond drilling at 50 m sampling intervals. After the orebody has been delineated, development work is carried out by exposing the gold reef. Channel sampling is then carried out at about 3 m intervals in both the stope and stope drives. A channel sample length is commonly 0.6 in, but may vary depending on physical characteristics of the reef. The values of channel samples are linearly combined to obtain the average reef or slope values and/or widths of the exposed sections. The sampling practice and methods of improving the efficacy of sampling at the mine are described.

Jan 1, 1976

The Copper Concentrator at Mount Isa Mines Limited treats approximately 6 Mt of chalcopyrite ore annually. The ore is currently sourced from the 1100 and 3000 orebodies at Mount Isa. Chalcopyrite is the only significant copper bearing mineral, with pyrite, quartz and dolomite being major gangue minerals. Ore is typically 10% chalcopyrite, 11% iron sulphides and 79% non-sulphide gangue. Copper ore is treated through two autogenous mills, two ball mills and a flotation circuit. The autogenous mills replaced a crushing plant, two rod mills and two primary ball mills during 1991. For routine analysis of concentrator performance, composite samples of mill feed, final concentrate and tailings are generated every 4 week period. All samples are sized and size fractions are assayed. Recovery of mineral species to the concentrate are then calculated for each size fraction. Sometimes liberation analysis was also performed by QEM*SEM (Quantitative Evaluation of Material by Scanning Electron Microscope).

Jan 1, 1990

By Meyer T

Sunburst PCF (Penetrating Cone Fracture) technology has recently undergone extensive underground field trials at Leinster Nickel Operations, Western Australia. Trials with the Sunburst machine started in September 1994 and continued through to December 1994 during which approximately 130 metres of tunnel were developed. The Sunburst technology was used to excavate sub-levels through ultramafic nickel ore for future sub-level caving operations at the Perseverance nickel mine. The Sunburst machine demonstrated reasonable instantaneous advance rates, however, there are still a number of future developments/design changes which need to be addressed prior to the PCF technology being trialed again in a production environment. This paper benchmarks conventional drill and blast at Leinster against the Sunburst Excavator machine performance within similar tunnel dimensions and rock conditions. In addition to productivity and cost information; environmental considerations, support and labour requirements are also discussed. Problems with the current machine design are highlighted and possible future design changes are suggested. The Sunburst machine could be a suitable technology for advancing development through weak to moderate rock conditions and may also reduce overall support costs. With the potential for automation and the ability to reduce rock damage into the development tunnel walls, it is proposed that the Sunburst machine warrants further consideration.

Jan 1, 1995

By E Philippa, J Vitanza, C Hawtin, B Miller

B Miller , E Philippa , C Hawtin and J Vitanza

Mar 22, 2022

The Charters Towers 1:250 000 Gravity Data Set represents a new initiative of the Department of Resource Industries (DRI, formerly Queensland Department of Mines) to provide high quality regional gravity data over areas of the State that have high potential for new mineral discoveries. The Department has adopted a strategy to upgrade geophysical data to complement the ongoing Regional Geological Mapping Program (RGMP) of this Department and in areas where the data would be of most benefit to the mineral exploration industry. Part of this strategy is to ensure that these data are released within 6 months of data collection.The 1989 Charters Towers survey was completed as a joint project with the Bureau of Mineral Resources, Geology and Geophysics (BMR), and is the first regional geophysical data acquisition project undertaken by the DRI. Prior to this survey, the only gravity data in this area dates from the B MR regional surveys carried out between 1960 and 1967.

Jan 1, 1990

Despite the large areas of sedimentary basins in Western Australia, the coal resources are very meagre., This is a serious problem for the State, which-at present-lacks any other alternate source of fuel-for power production.. Located coal deposits are all poor in quality and mostly brown coals of little importance. The best..coal suitable for extraction is at Collie, where a black=sub- bituminous non-coking coal is mined. Most other coals recorded are low grade or lignite, with high ash'and moisture content and a low calorific value. Coal was first discovered in Western Australia in the bed of the Irwin River, 50-miles south-east of Geraldton, by the Gregory brothers, explorers, in the year 18+6,. but although investigated, it has never been developed. The most noteworthy discovery of coal was in the Collie River, 26 miles east of Bunbury, by Arthur Perrin in 1883. Production commenced in 1898 and ever since, Collie has continued to be the State's sole producing coalfield.

Jan 1, 1964

Silica and limestone fluxing levels in copper smelting slags were studied. Copper concentrates with flux additions were smelted to matte (55.5 per cent Cu) and slag in a pilot scale submerged combustion furnace.Results indicated that oxidic and sulphidic copper levels in slags were minimised with a slag Si02 level of 36 per cent and a SiO2/CaO ratio of 5.5. Total copper losses in slags were 0.6 per cent under these conditions.To produce the desired slag chemistry, additions of bulk silica and limestone to copper concentrates of fluctuating grades were predicted numerically. The method employed the solution of two simultaneous equations, each respectively for silica and limestone calculations.The predicted flux additions were applied in a further series of tests and the resultant stages were found to be satisfactory. The method is applicable to smelting 'operations which employ two flux bins, with weigh feeders, so that slag chemistry may be controlled with the flux/concentrate feed mix.

Jan 1, 1985

The Graham Farmer Freeway Project in Perth, Western Australia, is the largest urban infrastructure project ever carried out in the State. At a project cost of over $360 million, it also ranks as one of the largest in Australia and is even large by world class standards. The project provides a much needed east-west freeway bypass around the CBD of Perth, linking the Great Eastern Highway in the east with the Kwinana and Mitchell Freeway system in the west. The Bypass will have 6.5 kilometres of freeway, a major bridge over the Swan River, several pedestrian overpasses and underpasses, dual use paths, interchanges and flyover bridges and a rail tunnel. The whole project is being carried out over a four-year time frame, due to be complete and open to traffic in June 2000. The project has been divided into two stages, with Stage 1 including the 1.63 kilometre long Northbridge Tunnel, the subject of this paper.

Jan 1, 1999

Before commencing design of a coal prepar ation plant, it is essential to have detailed information of the raw coal to be treated to- gether with a clear understanding of the products required. Prediction of raw coal size distribution, particularly the amount of fine material, is difficult and the methods employed should be large scale pilot plant studies or techniques to simulate coal degradation and shale breakdown in water. A detailed knowledge of well proven coal preparation processes and new developments allows processes and process combinations to be compared to'obtain the maximum economic recovery when using lower cost, less efficient processes within acceptable limits. Equipment should be selected bearing in mind its precise application and the location where it is installed. Plant layout should be carefully studied to minimise equipment requirements and to simplify construction. Measurement, control and automation should be an integral part of plant design in order to obtain the optimum performance of the processing equipment.

Jan 1, 1974

By Parr JM, Scott SD, Herzig PM, Gemmell JB

PACMANUS is an actively-forming seafloor analogue of volcanic-hosted massive sulfide orebodies, situated on the crest of an andesite-dacite-rhyodacite ridge overlying rifted older arc crust in a back-arc basin. Hydrothermal deposits range from Mn-oxide crusts to Cu-Zn-rich massive sulfide mounds and chimneys containing significant Au and Ag. Preliminary data suggest a substantial magmatic component to fluids and metal sources, and we speculate that PACMANUS is the cap to a complete hydrothermal system including subvolcanic and intrusive-related mineralisation.

Jan 1, 1995

By Grady PO

The longwall panels at Clarence Colliery have experienced intermittent sudden weightings on the face that have caused some production delays. These weightings have typically been more severe on the wider faces. A program of surface subsidence and extensometer monitoring was undertaken above Longwalls 4 and 5 to investigate the behaviour of the overburden strata during longwall extraction on two faces of different widths.The monitoring indicated that a dome shaped zone of large downward movement extends up into the overburden strata to a height equal to about the panel width.

Jan 1, 1998

By Rashad MZ

The evaluation of ore deposits consumes much effort, cost and time, hence research work must aim to minimize these inputs with no loss of accuracy. The present study is devoted to assess the optimum conditions and methods of calculations which give minimum costs of ore exploration. An area of (a x a) where "a" is the zone of influence of the semi-variogram, i.e. (2800 x 2800 square metres) located within the Abu Tartur plateau is the subject of the intensive study. The distances between boreholes are varied ie. a/4, a/6, a/8 and a/ 10 respectively. The average ore grade (G), thickness (t) and relative ore reserves (tG) are calculated by four methods. The results indicate that at a distance equal to a/5, the inverse distance squared method gives the best results. These parameters save about 50 percent of the cost of exploration with a map accuracy greater than 90 Percent.

Jan 1, 1987