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By Stevak D, Plesingerova B, Ellias K, Tkacova K

This paper presents information on the processing of minerals by decrepitation that can be an integral part of their mineral dressing. In the case of carbonates, processing by decrepitation is a special operation that has its objective as concentration of the oxide. Selective fragmentation of magnesite brought about by decrepitation uses pseudomorphosis which was observed at thermal decomposition of carbonates. By decrepitation of magnesite high-grade MgO concentrates were obtained with MgO contents above 80 per cent. With the sideritic ores a very important phenomenon was observed consisting in the removal of quartz in the fragmented fine-grained product which favourably affect pelletisation of the fines. The selective concentration of the MgO product brought about by thermal decomposition of dolomite accompanied with decrepitation was negligible.

Jan 1, 1993

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

By M Behrens, A McPhee, B D. Hegan

This paper describes the design and construction of twin 400 m long road tunnels as part of the Northern Motorway Extension Project in Auckland, New Zealand. Construction of the tunnel civil works is now completed and installation of mechanical and electrical systems is well underway. The tunnels are expected to be open for traffic at the end of 2008. The paper will address the design aspects of the project including: tunnel alignment and cross-section, geotechnical conditions and rock support, waterproofing and concrete lining and fire and life safety. The paper will cover the bored tunnel section, the cut-and-cover tunnel section, cross passages and portal structures. The design brief included a requirement for the tunnels to be a gateway to Auckland and this required particular attention to be given to the visual appearance of the finished tunnel structure. The final arrangement of the portal structures and a requirement for recesses in the concrete lining for emergency cabinets, deluge pipework and cable runs, reflects these requirements. The tunnels were excavated by a roadheader and road planer using a heading and bench. Initial support was provided by a combination of lattice girders, cement grouted rock bolts and steel fibre reinforced shotcrete. The permanent lining consisted of installation of a drainage geotextile and waterproof membrane, followed by cast in situ unreinforced concrete. Each portal consists of a cut-and-cover section. This paper describes the tunnel construction methods, including the particular requirements for safety, the environment and community relations. The tunnel is fitted with a compartmentalised deluge system for fire fighting purposes. The tunnel control centre is incorporated into the control centre for Auckland Harbour Bridge, some 30 km from the tunnel location.

Jan 1, 2008

By M Kuruppu, B Besa

Currently, conventional methods of decline development put enormous cost pressure on the profitability of mining operations. This is the case with narrow vein orebodies where current methods and mine design of decline development may be too expensive to support economic extraction of the ore. The time it takes to drill, clean and blast an end in conventional decline development can be up to 473 minutes. This is because, once an end is blasted, cleaning should first be completed before drilling can commence, resulting in low advance rates per shift. Improvements in advance rates during decline development can be achieved by application of the electric monorail transport system (EMTS) based drilling system. The system is composed of a two-boom drill mounted on the monorail and a pneumatic face cleaning system that loads blasted material into monorail containers. The operation allows for drilling of the top part of the face to commence as the monorail loading system continues to clean the blasted material at the development face. The preliminary indication is that an advance rate of 12 m per day could be achieved compared to 6 m per day in conventional decline development. The increase in the advance rate results from increased number of blasts that are possible per shift due to reduced time of cleaning and drilling the development face. The continuous drilling system has the advantage of accelerated decline development and orebodies will be accessed quickly and cheaply. Other advantages of the system include negotiating steep and changing gradients (ie reducing decline length), ability to negotiate tight horizontal curves, small operating room and limited diesel fumes.

Jan 1, 2008

By C W. Lu, Y F. Chen, M J. Lian, W W. Guo

This paper proposes a set of new approaches for the optimisation of planning and designs in mines by means of evolutionary algorithms, which include the determination of ore grade, layout of development system, selection of mining methods and production scheduling in underground mines. The applications indicate that evolutionary algorithms are particularly suitable to the complex and complicated problems in mines.

Jan 1, 2003

By Bowdler RJ, Lowson RT, Sarbutt JV

There have been few long-term studies of sulphide oxidation under controlled conditions. The object of this study was to investigate the oxidation and leaching characteristics of pyritic mine material under conditions that were commensurate with field conditions but which could be controlled and monitored on a long term basis. The test material - overburden from Woodlawn Mines Pty Ltd - was packed into a 300 cm high column and leached with water at an infiltration rate of 256 mm y-1 for 5 years. Chemical conditions within the column were continuously monitored by sensors embedded in the overburden and leachate from the base of the column was analysed weekly. The study examined the relationships between heavy metal release and gas, moisture, and chemical conditions in the column.

Jan 1, 1988

By Lemberg D. W, Friday R. G

Potential means of lowering overall costs to permit deeper stripping include : 1. the use of larger diameter blastholes in highly-fissured strata (to reduce drilling costs); 2. dewatering from semi-permanent bores to reduce blasting costs (by maximising the use of bulk ANFO) and promote highwall stability; and 3. the use of inclined blastholes, bulk AN, staggered V1 patterns, adequate backfill and more cost-effective stemming columns. Each of these is covered. The pumping of bulk watergels continuously raises the blasthole water column, thereby perpetuating the demand for these blasting agents. This must be a principal consideration when choosing between a bulk and a packaged watergel. Any packaged product should exhibit dimensional permanence and an energy yield per metre length equal to that of bulk ANFO. Possible ways in which controlled trajectory blasting (CTB) could benefit deeper stripping operations are outlined. By allowing the maximum use of bulk ANFO, de- watering may be a prerequisite of a viable CTB Operation.

Jan 1, 1981

By A G. L Pratt, M S. Kemp

BHP has used many innovative techniques when recruiting its workforce for the Cannington Project. Looking for a balance of experience and enthusiasm it was necessary to develop pre-selection tests to reduce the initial number of applicants to a manageable number for first interviews in Townsville. Success at this stage led to an applicant, and their spouse, to go through a second interview at the mine site. The full process from application to job offer took up to six months, but the results were felt to be worth the effort. The approach taken has resulted in a highly motivated and flexible workforce. This paper outlines the philosophies behind CanningtonÆs recruitment process, highlights some of the issues associated with the approach, and offers some measures of the outcomes.

Jan 1, 1998

By Zichenko ZA, Volkov SV, Shaluhina LM, Emelyanov AF

A method of selective gold recovery from black sands has been elaborated which is based on the liquid phase low temperature chlorination of materials. A liquid agent mixture of sulphur monochloride S2C12 and sulphur dichloride SC12 is used. This method ensures the gold extraction either in the state of AuC13.SC14 complex salt solution or as metal. The kinetics and main physico-chemical parameters of the process (eg density, solid: liquid ratio, temperature) have been investigated. The materials investigated were quartz-insipid ride samples with low sulphur and high iron (up to 70 per cent Fe2O3) contents. Gold recovery is 96 - 99 per cent at temperatures not exceeding 100¦C. Most of the associated minerals remain in the cake. To obtain metallic gold, the resulting solution of the AuC13.SC14 salt after leaching is reduced by hydrazine with subsequent annealing. The elaborated method is remarkable for small energy expenditures owing to low process temperature and a high gold dissolution rate. The solution of sulphur chlorides and other reagents are used in closed cycle.

Jan 1, 1993

By Mine F. J, Woods P. H

The Top End of the Northern Territory lies in the monsoonal zone and receives rain during the November-April period. Initially, at the start of the wet season, rain storms are localised, but, following the descent of the monsoonal trough from below the equator, widespread rain occurs. Overflow incidents at mine sites tend to arise midway through the annual wet season when excess water accumulated in ponds begins to discharge to the external environment. Remote-access monitoring may be undertaken at mine sites using equipment to continuously measure water quality parameters with storage of the information on a data logger. The data is then retrieved by visiting the site and transferring it to a portable computer or by remotely accessing the system using a telemetry system and transmission via telephone, VHF/UHF or satellite. Such systems are readily available and vary in cost depending on the sophistication of the data transfer system. Available sensors for continuous monitoring include those for conductivity, temperature, pH and other ion selective electrodes, eg nitrate, and water level. Of these variables, conductivity is most useful due to its inherent accuracy and stability of reading. Remote monitoring capability is able to provide: (i) more intensive monitoring of key issues; (ii) more timely information; (iii) correct perspective on the degree of environmental problem; and (iv) information from remote locations, which would be difficult to monitor by more conventional methods. Examples are given for applications of continuously logged measurement of conductivity of waters discharging to drains and in creeks at Pine Creek, Ranger, Nabarlek and Woodcutters mines in the Northern Territory. These applications demonstrate the timeliness of the continuous monitoring technique.

Jan 1, 1994

By E S. Bernard

Toughness testing of fibre reinforced concrete (FRC) at 28 days age is typically undertaken as part of quality control for the many applications where fibres are used in concrete, including shotcrete, tunnel segments, and cast-in-place tunnel linings. The performance achieved at 28 days is usually assumed to be retained with increasing age. However, as the average strength grade of concrete used in most tunnelling applications, including tunnel segments, has steadily increased over the last 20 years, this assumption is becoming increasingly unviable. This is because for some types of fibre the mode of post-crack fibre behaviour depends on the strength of the concrete and can change from a desirable high-energy pull-out mode to a low-energy rupture mode as the strength and age of concrete increases. This paper describes a series of trials performed over two years in which the American Society for Testing and Materials (ASTM) C1609/C1609M beam tests were used to assess the performance of FRC reinforced with two widely used brands of steel and macro-synthetic fibre. The hooked-end steel fibres used for half the beams exhibited a dramatic fall in performance beyond 56 days age as the mode of failure changed from pull-out to rupture. The other fibre did not exhibit a fall in performance with age. This phenomenon highlights the need to quantify performance of FRC at much later ages when long-term performance is required, for example, to resist seismic events or changes in ground stress due to nearby excavations. As an alternative, a reduction factor may be applied to the performance of FRC mixes for which evidence of satisfactory long-term performance is not?available.CITATION:Bernard, E S, 2014. Age-dependent changes in post-cracking performance of fibre-reinforced concrete for tunnel?segments, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 229–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

The Grootegeluk coal beneficiation plant is situated near Ellisras in the Waterberg coal= field in the Transvaal, RSA. At this plant 15 million tons of coal bearing material per annum are beneficiated by means of two-stage heavy medium bath and cyclone plants. Because of the very low yield of 12 % coking coal product, run= ping costs are of the - utmost importance. For this reason extensive tests were carried out to establish the most effective crushing and bene= ficiation methods and suitable aquipment. At the second heavy medium separation stage, the near-gravity material (+ 0,1. g/cc) amounts to 45 % and daily plant performance ana=lysis is required to ensure acceptable plant efficiency. Beneficiation processes for the -0,5 mm coal originally considered were froth flotation, shaking tables, heavy medium cyclones and water- only cyclones. When the froth flotation route was decided upon, further test work was done to enable selection of the equipment most suitable for the particular requirements.

Jan 1, 1987

By Voss Smith F, Matters C. W, Slee R. T, Coldham JC, Davies HW, Wallman H. H

The Committee desires to thank the managers of the various mines along the line of lode for their hearty co-operation in its labours. It would also extend thanks to Messrs. J. O. Moulden, Howchin, Twelvetrees, and the West Australian Geological Survey for various information; to Messrs. J. G. Dreyer, S. Pope, T. Read, P. Moncrieff, R. Williams, and W. J. Rose for analyses; and to a number of local gentlemen for advice and help. Professor Skeats, of the Melbourne University, gave much valued assistance in petrology, and Mr. Herbert Lavers kindly undertook the study of the garnets.INTRODUCTIONThe famous Broken Hill lode is situated in a low range of hills, the Barrier Ranges, near the western border of New South Wales. It has been worked since 1884-first for, silver, then for silver and lead, and at present for lead, silver, and zinc. No excuse seems necessary for placing before members even an imperfect report on the geological features of this notable ore deposit, since so little work has been done on the subject as to constitute almost a national reproach. This is the more deplorablesince the evidence laid open by mining operations is destroyed almost as soon as it is exposed, and there exists the real need of a continuous and connected record of geologieal developments.

Jan 1, 1911

By Seedsman R. W

Good roads are essential in moving men and materials to and from the underground workplace. Coffey Partners International Pty Ltd (Coffey) has recently completed a underground coal industry funded project on underground mine road construction and maintenance. This paper discusses practical approaches to construction and maintenance of underground mine roads using transferrable civil technologies and innovative techniques. Mine pavements are generally low-cost (relative to civil roads), constructed to varying standards using locally available materials to best meet the mobility needs of the mine. Performance of pavements is thus largely dependent on the environmental conditions, quality of the available road making materials, maintenance policies and available resources. The paper will detail `what causes bad roads?' in various underground environments, available management strategies, construction and water control techniques, road maintenance and vehicle considerations.

Jan 1, 1995

By R Higashi, D Maruoka, T Murakami, Y Iwami

The ironmaking industry consumes a large amount of fossil fuel derived carbon as heat source, reducing agent of iron ores and carburising agent of reduced iron. Although the demand for drastic decrease of carbon dioxide emission, carbon is an essential element for smelting process of molten iron. The carbon recycling ironmaking process by circulating CO has been already proposed to achieve carbon neutrality. However, the production of molten hot metal is not considered in this process because sufficient amount of carbon does not dissolve in reduced iron by CO. Therefore, our group has suggested a new carbon recycling ironmaking process which can produce hot metal. In this process, free carbon and iron carbides produced by carbon deposition reaction using metallic iron as a catalyst are used. It is known that only Fe3C is obtained as iron carbide by using CO gas, however, Fe5C2 is also produced by adding H2 gas. The composite agglomerated with these carbonaceous materials and fine iron ore (Deposited Carbon-Iron oxide Composite: DCIC) is reduced and melted in a furnace. It is reported that Fe3C in DCIC accelerates the reduction reaction and melting of the composite. In this study, the effects of iron carbides and free carbon on the melting behaviour of DCIC are investigated. Fe3C, Fe5C2 and free carbon were produced by vapour deposition using porous iron whiskers and CO-CO2-H2 gas. These were agglomerated with hematite reagent at a certain ratio to prepare DCIC samples with and without Fe5C2. The samples were heated up to 1300°C in inert atmosphere. The DCIC containing Fe5C2 completely melted and iron nuggets were obtained after the experiment. This behaviour was not observed in the composite without Fe5C2. This indicates that using Fe5C2 is more preferable than Fe3C for molten iron production using DCIC.

Jun 19, 2024

In order that the processes seen may be followed in their proper 'order, the subject will be dealt with as follows, (1) Wallaroo and Moonta Mines; (2) Wallaroo and Moonta Mines Smelting Works; (3) Broken Hill Mines; (4) Concentration at Broken Hill; (5) Smelting and refining of Lead, Silver, and Gold at Port Pirie. The first acquaintance with the copper region was made at the Yelta shaft and dressing mill of the Parramatta Copper Mines Co. at Moonta. The country rock at Moonta is a hard, tough, felsitic porphyry, the copper lodes having a general strike of N. 30° Kilipping from 500 to 70°. This necessitates shaft-sinking on the lode, and underlay shafts are the rule on the field. The ore is raised in the Yelta shaft in wheeled skips, and consists of ·chalcopyrite, bornite, pseudomorphic hematite, containing, in addition, molybdenite and tourmaline. The ore from the bins at the brace is passed over a grizzly; the over-size is hand-picked into smelting ore, concentrating ore, and waste rock (00 attle ), which is sent below for filling. The under-size is elevated to a trommel having in. holes. The over-size falls on to a picking belt made up of lengths of rope strapped with iron, working over wooden pulleys.

Jan 1, 1907

By Barro L

Very large reserves of gas are contained in coal. Because of the low permeability of the coal gas flow rates are very low. Fracturing of the coal can be achieved by use of the nitrogen - foam frac techniques described but the flow rates after fracturing are not sufficient to support economic development. Fracturing of the seams in the Bowen Basin was as predicted but in the Sydney Basin no trace of the fracture could be found when development proceeded past the fractured well. Testing of coal samples has provided some insight into parameters affecting desorption Rates.

Jan 1, 1982

By Chitombo G. P, Thompson A. G

Excavation engineering involves three key design processes; excavation design, blast design and reinforcement design. An excavation engineering methodology is proposed in an attempt to promote integration and simultaneous consideration of these three design processes. This methodology requires research and development of, inter alia, a universal rock mass classification system and a universal data display system. Simple examples are used to explain and illustrate the concepts central to these components in the three design processes.

Jan 1, 1995

GENTLEMEN, I have to thank you very much for the honour you have conferred upon me by electing me President of the Institute for this year. On behalf of resident members, I have to offer the visitors a very cordial welcome to Mount Morgan, and to tell them that all arrangements have been made to enable them to inspect the mine and works at their own convenience, and to supply them with any particulars they may need.It is very pleasing indeed to see such a large gathering, especially on account of the long journeys many have undertaken in order to be present. The first congress in Queensland, about eleven years ago, was attended by a comparatively small number of members, and a rather long time has been allowed to pass in consequence. The large attendance at this meeting encourages the holding of meetings in Queensland more frequently. Owing to the long distances, and the number of mining centres in Australia and New Zealand, we cannot expect to meet oftener than once in six or seven years in...

Jan 1, 1911

Politicians and economists talk glibly about the so-called knowledge revolution. The reality is that knowledge is fundamental to economic progress. Consequently there have been many technological revolutions. The global impacts of the invention of the steam engine and the development of the frozen meat industry are well known. Another less publicised technological advance occurred in Central Otago late in the nineteenth century. This was the adaptation of the bucketladder dredge to the mining of placer deposits. A product of over 30 years experimentation and innovation, New Zealand dredging technology was taken to the Risdon Iron and Locomotive Works, San Francisco by R H Postlethwaite, a Dunedin based mining engineer. New Zealand-style dredges built by Risdon operated successfully in California, Alaska and the Yukon. Californian engineers assimilated the best features of the New Zealand dredges with American (Bucyrus) designs to produce a standard for the worldwide placer mining industry.

Jan 1, 2003