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By Millen M. J, Rainey S, Sowerby B. D

The control of size reduction in grinding machines and circuits may be enhanced by a continuous and accurate measurement of the particle size of solids in appropriate process streams. This paper presents a brief review of commercial particle s

Jan 1, 1997

To carry out its responsibilities the SECV needs to manage the visual environment effectively. Every land oriented decision effects what we see and the value in pursuing visual excellence is supported by informed opinion, widespread community interest and evidence of cost- effectiveness.By knowing how we perceive the landscape and then changing or conserving it we can assist in fostering a positive mental image of a countyside which is welcomed by the local and regional community.It is useful to examine key design elements and the value we place on visual impressions in relation to three significant SECV rehabilitation projects, at Loy Yang, Newport and Morwell Open Cut.

Jan 1, 1992

By Fleming GJ

The Miwah prospect lies on the dilational 070¦ trending Miwah Lineament near its intersection with northerly oriented fractures within Pliocene volcanic rocks exposed between a NW trending segment of the dextral transcurrent Sumatra Fault, and the more northerly trending Samalanga-Sipopok Fault to the east. These faults reflect the continued interaction between stresses from the India-Australia plate located to the southwest, and spreading within the Andaman Sea to the north of Sumatra. A system of deep seated faults is believed to have facilitated emplacement of post-Miocene magmas and Quaternary volcanic centres at shallow crustal levels throughout northern Sumatra.

Jan 1, 1995

Against a background of deeper pits, the introduction of prestripping fleets and the need for closer control of operating costs (especially the waste removal component), Australian coal operations utilising draglines have in recent years become increasingly focused on:1. assessment of more efficient excavation methods; and2. application of explosive products and initiation systems which offer more flexibility than ever before.Additionally, developments in blast performance assessment techniques and equipment, and computer modelling and excavation monitoring systems have provided an improved opportunity to design a blast to achieve a desired profile suited to the excavation equipment and Sequence.

Jan 1, 1992

By Robinson BW, Walker RK

Using a new highly stable automated electron microprobe analyser, detection limits for gold in arsenopyrite have been improved. Using the AuLA emission tine at 40kV and 500nA, a limit of approximately 10gpt is attained in 10- lSmins. Some unusual features of the background need to be taken into account. Several ores containing different levels of gold in arsenopyrite have been examined, and it has been shown that gold is not evenly distributed between grains (some may contain more than 1%, invisible optically), and that the grains containing gold are often zoned. Gold may be released from the arsenopy rite by weathering or by heating in an inert or slightly oxidising atmosphere.

Jan 1, 1989

By Prosser AP

The large body of knowledge about the relation between chemical process efficiency and mineralogical features is of only limited use. The profession ought to try to improve the methods of using information as well as adding to the knowledge. One attempt isòdescribed. Correlations between process efficiency factors and the mineralogical features of low- grade concentrates have been developed from both a theoretical analysis and experimental measurements. The ultimate recovery of a reactive phase in an inert matrix can be calcu- lated from simple measurements of the particle size, porosity and pore size of the concentrate, and the grain size of the reactive mineral., The rate of recovery, up to 98% recovery, can be calculated from simple measurements of particle size, porosity, proportion of reactive mineral and tortuosity. Some details are given. The correlations are of potential use in process selection and preliminary design. Satisfactory predictions have been made for near-ideal systems. Improvements in the measurement of pore size and tests on more realistic materials are required. The ultimate benefit of the correlations will be determined by the magnitude and frequency of the effects of mineralogical features other than those specified above.

Jan 1, 1975

For the purpose of this paper the Otago Region is that covered by the Otago Regional Council. This area, like other South Island Regions, has a river system starting in the Mountains and are all gravel bed rivers. The gravel from these rivers has been the major source of aggregate in the region since the development of the province began. The majority of the aggregate is a mix of greywacke, schist and quartz, which will be referred to later with its production problems. The region has been broken down into various areas.

Jan 1, 1992

By C O. Gomez

The bubble size, together with the gas rate, determines the bubble surface area flux in flotation machines and, therefore, impacts directly on the kinetics of flotation. Understanding the variables that influence bubble size is one of the keys to understanding flotation recovery. Surprisingly, these relationships are poorly understood, largely due to the difficulties associated with gas dispersion measurements in industrial environments. The McGill gas dispersion sensors (bubble size, gas rate, gas holdup) are capable of reliably making such measurements. This paper reports on a study, using the McGill sensors in a 0.8 m3 Metso RCSTM pilot cell, which investigated the effect on bubble size of frother type and concentration, gas rate, temperature and rotor speed. A Denver laboratory cell was used to investigate the effect of elevation above sea level. Frother concentration proved to have the predominant influence on bubble size, and the effect of frother type can be normalised as a function of the critical coalescence concentration (CCC). Measurements made at many plant sites worldwide are compared to the model developed using the Metso RCSTM unit.

Jan 1, 2007

The progress of longhole open stoping (LHOS) at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited (ZC/NBHC) is described. The design of a novel sloped wall longhole stoping method at NBHC which should allow the cuplete extraction of the orebody without the formation of pillars and with minimal dilution of the ore with sandfill is reviewed.

Jan 1, 1983

By Artone E

screening equipment installed in e Hamersley Iron operation is described, and tails of operating parameters and screening - Iia in use are given. Tests were carried out on full-size reens in the operating plants to study the Meets of mat aperture size, feed size distri 1,ution, feed rate, screen speed and throw, angle of inclination, and feed moisture content n screen performance. Sampling equipment was signed so that undersize samples could be htained from various locations along the length of the screen, thus providing information pout the quantity and size of particles passing òhro gh the screen at any point. Conclusions derived from the testwork and relevance of these to the Hamersley Iron aeration are discussed.

Jan 1, 1984

By Garg R. K

Himalayan ranges on the northern border of India are source of many perennial rivers and suitable sites for large dams have been located therein. However, Himalayas are young mountains and comprise of comparatively weaker rocks having adverse geological features like shear seams, thrust zones, minor and major faults and intense jointing. Tehri dam project under construction, is located in lower Himalayas. It envisages construction of a 260.5 m high earth and rock fill dam and an underground power station of 2000 MW (Eight machines of 250 MW each, four of which will be reversible) installed capacity. This dam will be the highest and the underground complex will be the largest to be constructed in India in the Himalayas. The under- ground complex comprises of 25 km of tunnels varying in diameter from 6 m to 11 m and seven large cavities of various sizes, the biggest being 22 m in width, 194 m in length and 65 m in height. Rock formation in the power house complex belong to phyllites having various joint sets spaced from 0.5 m to 3 m. Due to the poor geological conditions and closely spaced net work of large cavities, the planning, analysis and design of the cavities is a challenging job. Many aspects have to be considered in determining the sizes, locations and orientations of the various cavities taking into account the properties and jointing pattern of rock mass, functional requirements and economics. Correct evaluation of loads and forces is necessary for economical design of supporting system for the various cavities. Rock loads on the roof of cavities and their supporting system will be assessed with the help of the latest methods. The stability of the rock mass around the cavity will be evaluated by elasto- plastic method using finite or boundary element techniques. A scheme of field investigations, laboratory tests and instrumentation for deter- mining rock properties in preconstruction stage and for monitoring behaviour of the underground cavities during and after construction is envisaged.

Jan 1, 1987

By Hayes P. C, Matthew S. P

The product morphologies formed on the reduction of dense wustite crystals are classified into three types, A) porous iron, B) porous wustite covered with dense iron, and C) dense wustite covered with dense iron. The mechanisms of formation of these structures and the effects of impurity elements on the product morphologies are discussed.

Jan 1, 1985

By Ichinose M, Tsuru T, Gotoh K

Since 1980, the Department of Mining Engineering at Kyushu University, in co-operation with the Ikeshima Colliery, Matsushima Coal Mining Co. Ltd., has been conducting a research project into longwall gateroad designs applicable to deep and poor strata conditions. During this period, the economic environment has drastically changed the situation of the domestic coal mining industry. Conventionally, the retreat longwall method, with re-use of gateroad, has been employed as it achieves higher recovery. However, from the view point of production efficiency, this method is not suitable because it requires intensive work in side packing and roadway maintenance. Therefore an interpanel-pillar system, or a two-entry gateroad system, was adopted to identify the factors responsible for excessive vertical closure in longwall gateroads. Field measurements and non-linear finite element analyses were undertaken to confirm the performance of this system. Study results indicate that the stability of the gateroad employing the rib pillar system is comparable to that of the conventional system of re-using Gateroads.

Jan 1, 1992

By Bhattacharyya AK

With increasing demand for more efficient production from the underground coal mines in the Southern Coalfields- of New South Wales, their design and operational aspects are constantly being reviewed and improved. One key area in such pursuits is the reliable design of stable and yielding pillars. The current designs of pillars based mostly on experience leads to unnecessary sterilisation of coal or strata control problems. To explore such mine design problems, computer based modelling is increasingly being applied. In the study described in this paper, the object was to determine the particular width of pillars separating three roadways in a panel at which the pillars yielded completely and their loads largely transferred to the unmined coal at the flanks of the panel. This was approached through a computer simulation of the behaviour of the strata around a panel, in which the three roadways were separated by pillars of progressively decreasing width. A computer program called FLAC based on the finite difference method was used to simulate the relevant strata behaviour in vertical sections. The appropriate in situ values of the deformability parameters relating to the coal seam, roof and floor were determined from the back analysis of some displacement measurements in such a panel. The process involved successive modelling of a vertical section through such a panel,starting with realistic values of the parameters and varying them until the measured and the modelled displacements agreed closely. Based on the results of the numerical modelling, the width of a yielding pillar for the given conditions is Suggested.

Jan 1, 1992

By Turco E, Pelizza S, Castellani F, Stanganelli V

Excavation are in progress for the building of tunnels of the waterworks in West Campania (Naples). The works afferent to part II envisage tunnelling through a miocenic clay formation over consolidated by two tunnels whose sections are respectively 50 and 10m2. Tunnel blasting is carried out by mechanical means. An excavator is used in the big tunnel, whereas in the small tunnel a roadheader machine is used for a short tract and a mechanized shield is used over a long stretch. The tunnel feature complex problems regarding stability. This is particularly so for the big tunnel whose face appears unstable. For this reason the clay on the face is sistematically bolted by means of 3-metre and 12-metre bolts. This prevent the use of a TBM for tunnel Excavation.

Jan 1, 1987

By E R. Ramanaidou, M S. Piggott

Transport to and handling of iron ore at Port Hedland, Western Australia, results in the generation of airborne particulates that contribute to the atmospheric dust load, with concerns about potential local environmental impacts (eg mangrove swamps) and possible human health implications. Mineral and chemical characteristics of the Background soil samples were contaminated with particles of iron ore as martite octahedra and grains of micro-platy hematite as detected by scanning electron microscopy (SEM) in the 2.5 - 10 ¦m and 10 - 50 ¦m size fractions. Fossilized wood fragments similar to those observed in Yandicoogina fines ore were also detected in some background soil samples. With a predicted increase in demand of channel iron deposits (CID) ores and the inherently dusty Marra Mamba ores (eg West Angelas, MAC, OB29/30/35, Marandoo), in conjunction with particulate emissions from hot-briquetted iron and direct reduced iron (HBI/DRI) processing plants, there is the potential for additional sources of anthropogenic dust to contribute to background levels. Mineralogical and chemical characterisation of the entire range of particulates that could be produced is necessary for a complete understanding of their potential impact on the local environment.

Jan 1, 2002

The Burragorang Valley lies approx. 95 km by road south west of Sydney and some 35 km west of Camden. It is over 80 km in length and varies in width from 3 km to over 16 km. Geologically, the history of the Burragorang Valley is of interest. It was referred to by early geographers and N.R.M.A. booklets as the largest sunken valley in Australia. This description is incorrect as it is a water worn valley formed by the dissection of an uplift in the south western portion of the large Sydney Sedimentary Basin. Ages2 ago there extended right across the Blue Mountains, a continuous tableland into which the Nattai, Wollondilly and Cox's Rivers have carved out the formation of the Burragorang. This dissection together with other valleys such as the Megalong, Jamieson and Grose, formed part of the eastward drainage pattern of the uplifting tableland into the Pacific ocean. The lapse of time since the streams in the Burragorang began their work of erosion can

Jan 1, 1976

By Leigh J. H

A history is given of the dust control techniques developed and applied by the mining companies at Broken Hill. A history of the regeneration works undertaken since 1936 is out- lined. Particular emphasis is placed on the stabilization of mine residue dumps which are located throughout a belt of mining leases in the middle of the city and which began in 1937. The establishment of vegetation for dust control techniques is discussed in detail and a case study is given of the successful revegetation of the sides of a 650 metre long, 350 metre wide and 35 metre high residue dump.

Jan 1, 1976

By Mallett C

Coal mines are dynamic systems that change continually in size, shape, and condition. Large quantities of data about production, coal quality, ground stability, ventilation monitoring, equipment performance and location, vehicle and personnel movements and geology, are generated from all parts of the mine.Internet technology and virtual reality technology are now being combined to provide an intuitive, multi-dimensional information system which can simultaneously display any information that can be collected and stored by a computer. Physical information is directly displayed as 3-dimensional objects in the mine model. Numerical and text information is dynamically linked to these objects and accessed by "clicking" on them.

Jan 1, 1998

The laboratory-scale reduction of fixed beds of iron ore pellets has been investigated over a range of experimental conditions. The effects of reduction temperatures, gas compos- itions and flowrates on 1) the rate of reduction and 2) the physical properties of the metallized products after reduction are being studied as part of a general programme aimed at the evaluation of the use of gaseous reductants for the direct reduction of Australian iron ores. This paper deals primar- ily with the effects of temperature on the rate of reduction using a H2/CO gas mixture. The physical properties of the metallized products such as strength after reduction, abrasion resistance and porosity are presented as functions of the reducing temperature.

Jan 1, 1974