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The screening of iron ores, sinter and coke, and investigations undertaken to improve screening efficiency and cloth life are discussed. The major modifications to coke screening proposed with the construction of No. 7 coke ovens battery are briefly described. The major problem areas were identified as screen cloth blinding and pegging, feed presentation and screen overloading. Blinding and pegging have had a significant effect upon screening efficiency with the screening of sinter, coke breeze and wet iron ores in particular. Pegging can be reduced or eliminated by the correct selection of aperture size and shape, screen excitation and slope, and screening medium. Blinding encountered with wet coke breeze was a particular problem in which no significant progress was made.

Jan 1, 1984

By Carter NB

A statistically-designed experimental program has been used to study compositional and processing variables which influence the development of strength and reducibility of iron ore pellets. The effects of chemical composition and processing variables were investigated by indurating laboratory-made green pellets, of known composition, under approximately isothermal conditions in a pot- grate simulator. Some findings from a six- variable study are summarized in the form of contour diagrams and emphasize the importance of interactions between the variables. Production of strong, highly reducible pellets is possible over a considerable range of combinations of temperature and firing time. Abrasion index (AI) and cold compression strength (CCS) improve as both these variables increase, but reducibility (R) declines, so a compromise is required. When the lime level is too low to form enough slag for bonding, the AI and CCS may be inadequate. Larger additions of lime tend to improve AI and CCS, with only slight effects on R. Finer grinding of the balling feed (i.e. higher Blaine index) tends to improve Al and CCS without

Jan 1, 1980

By Neville Rockhouse

This paper examines the interrelationship of conducting full risk assessments in the context of the coal mining industry and under the framework of the Health's Safety in Employment Act 1992. In the context of Occupational Health's Safety, Risk Management is a holistic management process that can be used by individuals working in all organisations and from all industries. The Australian New Zealand Standard 4360: 2004 defines a Risk as being; The chance of something happening that will have an impact on objectives. This definition is followed by several notes that include: a risk is often specified in terms of an event or circumstance and the consequences that may flow from it, risk is measured in terms of a combination of the consequences of an event and their likelihood, and risk may have a positive or negative impact. For the purposes of this paper, the above definition will be adopted. This paper examines the newly expanded approach of the fully documented risk management process in the New Zealand coal mining industry. This is done in the context of the coal mining regulations but more importantly by using the framework of the Health & Safety in Employment Act 1992. This legislation under Section 6 requires all employers to, Take all Practicable Steps to prevent harm coming to employees while at work and to others who might be at or in the vicinity of a workplace. When the term 'all practicable steps' is studied, one can clearly see that such steps should be the same steps taken that a prudent and reasonable person would have taken given the same type of circumstance. Due to the fact that in New Zealand parliament made statutes is administered by a Government Department, means that their breaches will be heard before a judge in the District Court. Under the Westminster System of Justice, a basic dictum of that court in matters relating the occupational health and safety is that a breach needs to be satisfied to a specific standard. That standard is, 'Beyond a reasonable Doubt'. One of the primary benefits of adopting a proactive approach to risk management is that if the industry were to adopt similar approaches, then this mythology could be seen as an industry standard. As such, the approach carries the same status in a court of law, as that of an Approved Code of Practice.

Jan 1, 2007

By Bromley JC

Eimco Great Britain, a division of Baker Mining Equipment Company, was contracted to develop a hardrock tunnelling machine in conjunction with British Coal. The objective: a machine to cut rock up to 170 MPa compressive strength yet retaining the flexibility of roadheader type machines. This flexibility to encompass mobility, wide range of excavation shapes and sizes, simplicity of design and use, compact size, and efficient cutting operation. Current roadheaders operating in hard material are characterized by: 1. Severe machine vibration 2. Bouncing of the boom away from the rock 3. Very high pick wear 4. Inability to sump head in bad floor conditions The reasons for this poor performance can be attributed in part to: 1. High speed of cutting head rotation 2. Inability to hold boom against rock while cutting variable hardness strata. To overcome the problems described, a new articulation method was developed utilizing four hydraulic rams to "lock" the boom in position on one axis and four hydraulic motors to rotate the boom for cutting via a turret arrangement. The slide mounted turret is hydraulically advanced for sumping into the face, independent of the machine base. To transfer cutting forces back to the rock, the machine base is held rigidly in the excavation by floor to roof or side to side rams. A cutting head mounted on the boom rotates at very low speed, but with very high torque.

Jan 1, 1987

By Hayes P. C

The reduction of small, dense zinc oxide (ZnO) samples in CO/CO2, and CO/N2 gas mixtures has been investigated at temperatures between 900 and 1100¦C. The microstructural characterisation of the reacted and partially reduced samples was complemented with measurements of the rates of the reactions. The mechanisms and kinetics of reduction of zinc oxide were found to be dependent upon the CO partial pressure, the oxygen potential of the gas mixtures, temperature and degree of reduction.

Jan 1, 1991

By G R. Hancock, J B. C Lowry, T J. Coulthard

A reconstructed landscape may exert long-term influences on its surrounds and behave in ways that may not be predictable given uncertainties regarding climate, soil and vegetation interactions (Evans, 2000). In recent years, computer-based landscape evolution models (LEM) have been used to assess potential and existing mining landscapes and their long-term geomorphic behaviour (Hancock et al, 2007; Hancock, Lowry and Coulthard, 2015; Tucker and Hancock, 2010).In this paper, we focus on the evolution of post-mining landforms, which are designed to include burial or encapsulation of mine-impacted areas and materials, including tailings, drains, spoil tips and other industrial architecture (Figure 1). At the Ranger Uranium mine in the Northern Territory of Australia, low-grade uranium ore, tailings, brines and other mine wastes will be buried at depth in the areas of the former pits and tailings storage facilities.The use of LEMs to predict long-term landscape evolution has several issues. These include that model predictions are based on the calibration and parameterisation of the model carried out using values determined from present day, or recent surface conditions. Furthermore, there is also the question as to how subtle perturbations or roughness on the DEM surface can produce alternative model results by randomly varying the elevations of the DEM surface.In this study we examine the effect on sediment transport rates and geomorphology for a proposed rehabilitated landform using multiple landscape realisations with increasing magnitudes of random changes in the DEM using the SIBERIA LEM (Willgoose, Bras and Rodriguez-Iturbe, 1991).CITATION:Hancock, G R, Coulthard, T J and Lowry, J B C, 2016. Use of landform evolution models to assess uncertainty in long-term evolution of post-mining landscapes, in Proceedings Life-of-Mine 2016 Conference, pp 67–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

It is difficult with inadvertent explosions to establish fundamental data, especially of original dust, of pressure, temperature etc. and of ventilation oscillations, as exposed personnel rarely survive. Retrospective data from explosions must be derived from damage, from fatalities, from ventilation analyses, from analyses of dusts and other indications of temp- erature and duration of temperature. The five disastrous explosions selected for analysis provide examples of what data can be established as to the cause and extent of explosions. Such information is required for legal etc., inquiries subsequent to explosions, but most importantly to give the best guidance for avoidance of possibility of further Disasters.

Jan 1, 1981

IN preparing a sample of refined lead for analysis, it is necessary to exercise great care to avoid contaminatien, as the amounts of the various impurities present in market lead are very small. The lead is cut into convenient-sized pieces, which are flattened out with a hammer, so that, on putting tbe lead through the rolls, strips of about one inch in width and Ij32iu. in thickness are obtained. The hammer, anvil, and rolls should be carefully cleaned before use. The strips oflead are cut up into pieces of about one inch square. If the lead is roIled out very thin and cut up into small pieces there is considerable risk of the acid acting too violently and causing loss through frothing over. A blank assay on all the reagents used should becarried right through, along with the actual analysis of the lead. This is of the greatest importance, particularly with regard to the determination of such impurities as iron, sulphur, arsenic, and antimony.METHOD OF ANALYSISThe method of analysis is as follows: Take two lots of 600 gIm. each, place in a large beaker, add 2000 cc. distilled water and 750 cc. concentrated HNOs. Cover with a clock glass and warm on a hot asbestos plate until all action ceases. (If any white precipitate forms, filter off and examine for Sn and Sb.) Add 420 cc. H2S04 (1-1), and stir well while adding the acid: Allow PbS04 to settle, pour off the clear liquid into a 12-in. porcelain evaporating dish, and start evaporating down, the dish being placed directly on an 8-in. ring gas burner. Wash the precipitate three times by decantation using approximately 1200 cc. hot water for each washing, and stir well...

Jan 1, 1922

By A F. Cooper

The northeast-southwest trending ~25 km2 area incorporating Bald Hill is located 18 km northeast of Haast, and 5 - 7 km west of the Alpine Fault in South Westland, New Zealand. The geology consists of Greenland Group greywacke overlain by a Cretaceous-Tertiary sedimentary sequence and fluvio-glacial/marine terrace deposits of Quaternary age. Alluvial gold in Cole Creek, draining west from the summit of Bald Hill, may be derived either from vein mineralisation in basement rocks or from fluvial or marine terraces.   This paper focuses on the potential for in situ gold and base-metal mineralisation in sporadic, siderite-rich quartz veins that cut basement greenschist facies metasediments that have been overprinted by contact metamorphism.   Throughout the area, vein compositions are dominated by quartz and commonly feature zoned plagioclase. Alteration adjacent to veining within the contact aureole is dominated by 1 - 2 mm, coarse grained biotite, with small amounts of sulphide, and is pervaded by abundant siderite veinlets. Outside the aureole, wall rock alteration to veins consists of fine grained chlorite. Trace element XRF analysis has been used to ascertain base metal concentrations within samples of vein and alteration zones collected from throughout the area. Vein and alteration zone mineral assemblages containing <5 per cent sulphide, with low concentrations of As, Cu, Pb and Zn indicate low potential for gold and base-metal mineralisation in the Bald Hill region. Contact metamorphism of Greenland Group basement in the northeast of the region, is likely due to emplacement of a poorly exposed Cr- and Ni- enriched gabbro. The presence of biotite and andalusite in hornfelses indicate contact metamorphism occurred at temperatures >350¦C and at depths <10 km. Widespread vein distribution does not appear to be related to contact metamorphism or gabbro emplacement. Further research is required in order to establish the fluid source from which the veins were precipitated.

Jan 1, 2007

By M S. Manono, K C. Corin

The optimisation and process developments surrounding the beneficiation of Cu-Ni-PGM ores is of fundamental importance when considering the continued rise in global demand for these precious metals. The selective sequential flotation of these ores is accompanied with various processing challenges such as the successful separation of the Cu-Ni-PGMs from non-sulfide naturally floatable gangue and pyrrhotite. Reagents such as sodium iso-butyl xanthate (SIBX) and sodium carboxymethyl cellulose (CMC) have proven to significantly improve the selectivity of the flotation process in their respective roles. The use of recycled water with abnormal inorganic electrolyte concentrations can modify the selectivity of these reagents, as ions may adsorb onto minerals such as pyrrhotite, thereby hindering or promoting the hydrophocity and floatability of pyrrhotite. Process water quality effects on the behaviour of pyrrhotite may have negative or positive influence on the recovery and grades of the wanted Cu-Ni-PGMs as valuable minerals associated with pyrrhotite such as pentlandite may be affected in like manner. Thus, the impact of concentrator process water quality on the behaviour of pyrrhotite needs to be determined. In this study synthetic process water at various ionic strengths was investigated against various CMC dosages to understand the behaviour of pyrrhotite during the flotation of a Cu-Ni-PGM Merensky ore in a batch flotation cell. This study showed that pyrrhotite grades increased with an increase in CMC dosage for fixed ionic strengths whereas the recoveries of pyrrhotite increased with an increase in ionic strength until 3SPW, then a trend of a decrease in recoveries was seen with 5SPW resulting in the lowest pyrrhotite recoveries. Furthermore, this study showed that moderate CMC dosages of 100 g/t resulted in the highest pyrrhotite recovery for all four ionic strengths of synthetic process water tested. It can be said that to maximise value recovery from Cu-Ni-PGM ores, understanding the behaviour of pyrrhotite against degrading water quality and reagent suites could be of paramount importance given the sensitivity of pyrrhotite to oxidising chemical conditions.

Aug 24, 2022

By Jiaxin Zhou

Acid mine drainage is a serious and chronic environmental problem of mining. This paper discusses the factors affecting the rate of acid generation by mine rocks and illustrates the relevance of these factors to the mines of the Northern Territory, Australia. The factors may be divided into two groups: internal factors and external factors. The first group covers characteristics of ores, mine waste rocks, tailings, etc and the second group covers surrounding conditions. The latter is further divided into four sub-groups, viz surrounding temperature and pressure, chemical conditions (ferrous/ferric adsorption ratio, total iron concentration, oxygen concentration and pH), surrounding biological conditions and mechanical conditions. Special attention is given to the surrounding P-T conditions, especially water partial pressure, and its relevance to the Northern Territory mines.

Jan 1, 1994

By McKenzie C. K, Stewart R. S, Simpson J

Blast control in small scale underground mining leads to improved fragmentation control, improved control over overbreak and dilution, and the optimisation of drilling and charging operations. Greatly improved control can be achieved through blast monitoring, to confirm proper implementation of blast designs and blasthole charging. Further improvements can be achieved through simple modelling, enabling blastholes to be placed in the correct locations and charged with the correct weight and strength of explosive. Improved design can be shown to significantly reduce overbreak and dilution, and even ground support costs. In one mine in Quebec, open stopes of widths varying from 2.5 metres to four metres and dipping at 36¦ to 38¦ were designed to achieve zero dilution using open sloping blasting practices. The first stope designed in this manner was monitored in detail and achieved its objective.A method for contouring damage around blastholes is presented as a basis for selection of drilling patterns, with particular application to the control of overbreak and dilution. Contouring can be used to provide reliable estimates of either overbreak or damage (where rock is broken het reynainc in nlarr)

Jan 1, 1993

Open pit mines in the Yilgam Craton have unique hydrogeological characteristics resulting from a combination of geology, mineralisation and the complex and extended development of the regolith. The principal features of this geological relationship are:ò deep and complex multi-stage development of the weathering profile; ò steeply dipping rock layering;ò supergene enrichment; andò mining across the regolith/rock interface.These features result in large changes in permeability horizontally across rock layers; vertically through the weathering profile and along-strike in association with mineralisation and the mineralised Structure.

Jan 1, 1993

By M Sandy, A Vakili, J Albrecht

Although rock strength anisotropy is a well-known phenomenon in rock mechanics, its impact on geotechnical design is often ignored. No widely accepted guideline currently exists for its characterisation. Anisotropy can significantly control the failure mechanism and progression of damage into the rock mass, particularly in high-stress conditions. As such, it can play a key role in the stability of underground excavations and subsequent geotechnical design.This paper introduces the concept of anisotropy at both intact and rock mass scales. It then presents guidelines for measuring anisotropy and assigning rock mass strength properties. An improved unified constitutive model (IUCM), which can account for more complex failure mechanisms, is then briefly described. This IUCM is used to better understand the typical responses of anisotropic rocks to underground mining and to develop an improved damage classification scheme for these conditions.The application of conventional design methods in anisotropic conditions is shown to lead to significant errors. Two case histories are then presented, illustrating how the proposed methodology can improve the reliability and accuracy of the geotechnical analysis when compared with conventional design methods.CITATION:Vakili, A, Albrecht, J and Sandy, M, 2014. Rock strength anisotropy and its importance in underground geotechnical design, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 167–180 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By J Boland

Polycrystalline diamond compacts (PDC) have been widely used as cutting elements in the drilling tools for the oil, gas, civil and mining industries because of their faster penetration rates and longer bit life. US Department of Energy reports that PDC bits account for more than one-third of the total footage drilled worldwide (US Department of Energy, 2004). However, non-thermally-stable diamond composites (NTSDC) have seldom been applied to geothermal drilling, since premature failures of such PDC cutters have been observed in hard rock formations. Several factors need to be considered to prevent premature failure of cutters and improve cutting performance when using PDC-based bits and other rock cutting tools. The first set of factors consists of the strength, density, stiffness, toughness and thermal resistance of the PDC and the rock. A second set relates to the complex behaviour of the bonding between the PDC cutter and the bit matrix, or the pick and the pick holder, which is vital in maintaining stable, reliable and durable adhesion of the cutters to their hubs. Finally, based on a better understanding of the cutting processes, the formulation of a predictive model would assist in further development of cutter design.

Jan 1, 2004

By Edwards A. B

This paper presents the results of an examination of four samples representative of the low-lead matte, high-lead matte, lead speiss and antimony speiss, respectively, produced during smelting operations at Port Pirie Smelters. The investigation was undertaken at the request of the Broken Hill Associated Smelters Pty. Ltd., as part of the research programme of the Mineragraphic Section of the Council for Scientific and Industrial Research.Analyses of the specimens are as follows:-

Jan 1, 1949

In 1985 BMR assessed Australia's economic demonstrated resources of mineral sands as follows: rutile 8.0 Mt, ilmenite 41.4 Mt, zircon 11.5 Mt, and monazite 229 000 tonnes. These resources are located along the east coast of Australia, in the southwest corner of Western Australia, and in the Eneabba region, north of Perth, WA. However, over 40% of Australia's rutile and zircon resources, particularly those on the east coast, are presently not available for mining because of environmental considerations. As well, east coast ilmenite has been considered unsuitable for use by sulphate route pigment producers because of its relatively high chrome content. World demonstrated resources of rutile and zircon are estimated by BMR as 29 Mt and 38 Mt respectively. Demonstrated resources of ilmenite amount to about 1 billion tonnes. These occur predominantly in hard rock deposits in Norway, Canada, USSR and China, as well as alluvial deposits in Australia, South Africa and India. Quantitative data for world monazite resources is sparse. However, world production of rare earth oxides is now mainly from bastnaesite, a hard rock resource. Australia is presently the world's principal producer of rutile and zircon, and also provides a major share of the world's ilmenite. With the expected increase in Australia's rate of output of these commodities, combined with restrictions on mining along parts of the east coast, its position could diminish substantially over the next 25 years.

Jan 1, 1986

This paper discusses the requirements for a successful simulation modelling study, and the steps involved in the modelling process. Advantages and disadvantages of simulation are described, and a case study highlights how not to go about it. Two other case studies, for a decline truck haulage and a block caving production operation, are used to illustrate the types of variables whose impact may be investigated. Typical results are presented to indicate the sorts of presentation styles the author has found useful for conveying study results to project sponsors. Standard spreadsheet charting techniques can be very useful in this respect, but the possibilities are limited only by the imagination of the study team.

Jan 1, 2000

By Needham RS

Hydrothermal mineral deposits are the dominant mineral deposit type in the Cullen Mineral Field, and have been important sources of tin, tungsten gold, silver-lead, zinc and copper. The deposits are mostly in north to northwest-trend- ing shear zones, and are confined to Early Proterozoic contact metamorphosed metasediments or synorogenic to postorogenic granitoids. The distribution of the vein-type deposits with- in the contact aureole defines a district-scale metal zonation of uranium closest to granitoid, through tungsten, copper, tin, silver-lead to gold with increasing distance from granitoid contacts. This zonation probably reflects de- creasing temperatures within the contact aureole during granitoid emplacement, and at the time of generation of a variety of metal-bearing fluids. A magmatic source for some of the metals is indicated by the positive spatial relationship between uranium, tungsten, copper and silver-lead deposits and granitoids abundant in those metals. There is little evidence for any such relation- ship for tin and gold deposits, except for an association of some tin deposits with tin-enriched mafic rocks. Most of the granitoids with anomalous metal values are late stage highly fractionated leuco- granitic phases forming younger plutons peripheral to the main body of the Cullen Batholith, They probably form cusps connected to the main body at shallow depths.

Jan 1, 1984

Government established and financed the NZ Steel Investigating Co in 1960. Its investigations showed that a steel industry was feasible and desirable based uponNorth Island titanomagnetite ironsands, and charted a route for its establishment. The initial processing used post-1945 preheating and prereduction developments, but later innovative improvements created what was essentially a new New Zealand technology. Of the North Island titanomagnetite deposits: the small ones at Waipipi were best made available for export; those at Kawhia and Taharoa were too remote for the economic siting of a mill; that at Raglan proved too small; while at Waikato North Head three times the requirement of 50 million tons of concentrate were located in two sand areas averaging 18 per cent titanomagnetite. Economic studies showed that a South Auckland site would be ideal, close to New Zealand's biggest market. The mill site, on a basalt flow at Glenbrook, was located by a half-day's fieldwork - near both the Waikato North Head deposit, and a railhead for bringing in Waikato coal, etc, and taking out steel products.   This development was one of several since World War II which altered significantly the lives and homes of New Zealanders (others were natural gas, oil, geothermal power, epithermal gold, aluminium, opencastable lignite, etc). All had the essential ingredients of the highest government backing, direct or indirect government finance, and first-class New Zealand scientific and engineering skills (eg to create new technologies). Not one such project failed.

Jan 1, 1993