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TIMBER supports for large underground cavities are temporary expedients until the permanent filling can be put in. Nevertheless, timber supports are very necessary in some form. The general problem is to support the cavity in all directions withthe minimum of timber, disposed in the strongest way. The simplest way of filling an irregular space with timber sets is to form triangles.The right-angled isosceles triangle (Fig. 1) leads to the true square set, in which caps are equal to struts. The right-angled unequal-sided triangle and the scalene isosceles triangle (Fig. 2) lead to the oblong square set, where caps are longer than struts.The scalene triangle (Fig. 4) leads to the rhombic or oblique set. The equilateral triangle leads to the hexagon set (Fig. 3), in which the caps and struts are all equal. These five plane figures, the triangle, square, rectangle, rhomb and hexagon, are the only figures that will completely fill any irregular plane figure, without interstices. Hexagon sets were first suggested by the writer in 1902 to a mine manager at Broken Hill, who did not see his way to use them.

Jan 1, 1912

The Porgera Joint Venture commenced production during September 1990. A small tonnage underground mine extracts high grade gold ore using small scale stopes. Conventional drill and blast methods are used for development and production mining. Ground support is effected with Splitset anchors, grouted rebar bolts and grouted cable bolts. Splitsets and grouted rebar can be installed by mechanised means. Vertical crater retreat, slot and massfire, and modified VCR stoping tech- niques are used at Porgera. Stopes are backfilled with a relatively strong cemented rockf ill. Future stope sequences require recovery of pillars beside and under filled stopes.

Jan 1, 1991

By B C. Sarkar, D Ray, V Sarkar, P K. Sinha, R K. Singh, A Kumar

Estimation of iron ore grade distribution has been attempted using geostatistics and artificial neural network (ANN) based models for a banded iron formation (BIF) type iron ore deposit of East India. Geologically, it is a supergene iron ore formation through an enrichment process of parent material (BIFs) by gradual leaching of impurities, namely SiO2 and Al2O3. As the degree of leaching differs spatially, distribution of Fe varies depending on local controls of ore formation. While geostatistical methods work on models based on spatial correlations of mineralisation parameters, ANN models a non-linear distribution and is widely used as a global approximator. Spatial distribution modelling of Fe values has been carried out employing ordinary kriging (OK) and sequential Gaussian simulation (SGS). Non-linear modelling has been performed using hybrid neural networks (HNN) that provided an alternative option for grade estimation. Classical statistical modelling revealed a negatively skewed 3-parameter lognormal Fe population having a mean of 60.49 per cent with a skewness of -0.08 and a kurtosis of 2.60. Semi-variography and geostatistical estimation employing OK procedure led to block-by-block kriged estimates with associated kriging variance, which provided an overall mean kriged estimate and kriging variance of Fe as 60.29 per cent and 7.76 (per cent)2 respectively. SGS procedure revealed a mean of 60.71 per cent and a standard deviation of 5.89 per cent with minimum and maximum values as 45.12 per cent and 68.70 per cent respectively in respect of Fe. HNN model provided values of mean squared error (MSE) and correlation coefficient (R2) as 12.33 and 0.61 respectively, thereby exhibiting the robustness of the model to sustain maximum heterogeneity within the target domain. A comparison of Fe grade estimates obtained by kriging, simulation and HNN models more or less maintain similar distribution patterns that are close to the sample data. It is thus opined to carry out the grade prediction exercise employing all these three modelling approaches to obtain alternative scenarios for improved mine planning and design exercises. The techniques provide a foundation for cogent grade modelling leading to improved iron ore reserve estimation procedures.CITATION:Sarkar, B C, Singh, R K, Ray, D, Kumar, A, Sinha, P K and Sarkar, V, 2017. Iron ore grade modelling using geostatistics and artificial neural networks, in Proceedings Iron Ore 2017, pp 431–438 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By B Moynihan

The Roa Opencast Coal Mine is situated at the north-eastern end of the Greymouth Coalfield. It lies on an eastern flank of the Paparoa Range, 16 km north-east of the town of Greymouth on the West Coast of the South Island. Road access is via a sealed road from Blackball to Roa, then by a 5.3 km all weather, gravel road, which gains 340 m in elevation from 190 m RL at Roa to a maximum height of 530 m near the opencast.

Jan 1, 1993

A recent Evening Post Headline read 'Officialdoms Inertia Risking Millions in Growth Strategy'. The article beneath that headline outlined the difficulties encountered by the Government's growth strategy projects and included the paragraph 'public efforts by Government to brush up communication of the widespread nature of its growth strategy is believed to have been matched by efforts in private by some ministers to overcome their frustration at the constant delay while reports and paper work are moved between departments and through the system'. The article went on to point out that these delays could cost New Zealand millions of dollars in lost overseas exchange savings. We as responsible citizens should be appalled or at least concerned that such costly delays should or even could occur. But those on the outside of the system who spend much of their working life prodding, reminding, pleading, cajoling, even begging, the bureaucracy should be excused a smirk or a smile or even a good belly laugh. The Minister is usually a part of the bureaucracy passing judgment on someone else's proposals. This time the Government has plans of its own. Plans which it wishes to see implemented as rapidly as possible and even with the assistance of the precautionary National Development Act with its 'fast track' provisions those plans have got bogged down in the bureaucratic machine which this Government has done as much as any other to create. In the circumstances, the thought of Her Majesty's Ministers frustrated at the constant delay while reports and paper work are moved between departments and through the system is not unpleasing.

Jan 1, 1982

Interest in those physical properties of minerals which might be used to good effect in prospecting is not new. Early in the nineteenth century attempts were made in th'e Cornish mines to measure the natural electric potentials set up by chemical changes proceeding in the lodes. The distortion of the earth's magnetic field by bodies of strongly magnetic iron ore received early recognition in Sweden. Treasure-finders, working on the principle of electrical induction, appear to have been invented about eighty years ago, though were probably not then applied to mineral exploration. By the end of the nineteenth century Eotvos, a Hungarian physicist, had constructed a highly sensitive type of torsion balance capable of measuring the minute distortions in the earth's field of gravitation resulting from variations in the density of the materials composing the crust. During the first decade of this century he demonstrated its value in tracing rock-salt deposits in virtue of their low density compared with the surrounding rocks. Geophysical prospecting began to be recognised as having a very definite value and its development gathered momentum. Its great expansion took place after the 1914-18 war, when its value in oil exploration was amply demonstrated, and this expansion has continued to the present time and shows no signs of abating.Divisions of Applied Geophysics.The four main divisions of applied geophysics are electrical, magnetic gravitational and seismic. With the importance of ores of radio-active metals, one might add to these a radio-active division. The first two are more important to the field of mining, but techniques based on gravitational attraction have their uses in particular cases. Seismic methods are not generally suited to the exploration of metallic ores, but have proved of enormous value in the search for petroleum. With vast quantities of oil as the prize, more money has been lavished on the deve10pment and practice of these methods than on all the others put together.Geophysical Prospecting Methods.Geophysical prospecting methods may be used to detect a mineral deposit directly in virtue of differences in the intensity of some physical attribute common to it and the enclosing country rock. Examples of this are the detection of rock-salt by gravity measurements, or of iron ore by magnetic methods. Of much wider application, however, is the indireot approach in which the aim is to determine, by geophysical means, the geological structures controlling the disposition of mineral deposits. These structures may be partly known from geological work, in which case geophysical methods are useful adjuncts. Where, because of an 'unbroken cover of overburden, no useful geological information presents itself, scout drilling or geophysical prospecting are the only alternatives. Overburden is here intended to mean any covering material not, involved in the structures controlling the mineral deposits. Prospecting for petroleum amounts to the detecting of favourable reservoir structures, and as the chief types of such are the same the world over...

Jan 1, 1950

The large increase in secondary industries in this country, during the war and post war periods, has caused a shortage of capacity for the production of merchant bar.To overcome this shortage, an expansion of rolling mill facilities has been undertaken by the Broken Hill Pty. Co. Ltd. A small, but modern, merchant mill has been erected at Kwinana in Western Australia and a strip and skelp mill is under construction at Newcastle. The latter mill will roll strip and skelp at present being rolled by the Newcastle 10 in. Merchant Mill, enahling this mill to concentrate on merchant bar production.The Kwinana mill was installed to supply the Western Australian market. This state has a small population (approximately 658,000) and is not at present highly industrialised. It was necessary, therefore, to design a mill which would be capable of producing a wide diversity of sections and could be expanded as the demand increased. To begin with capital expenditure had to be kept within reasonable bounds. The design work for this mill, with the exception of a few specialised items of equipment, was carried out at Newcastle.All design work for the Newcastle mill was carried out by the lVIorgan Construction Co. of America. Although initially intended for rolling flat. products, the designers were asked to make the mill as flexible as possible, so that should the market for flat products decrease, this mill with additional equipment could undertake the rolling of medium sized sections.

Jan 1, 1957

By Gordon DM

Tyres account for 25-30 per cent of the operating costs of large capacity haul units as used in open-cut mines.Tyre operating costs can be substantially reduced and often contained in real terms by applying knowledge that is now available.This paper describes certain specific advances in tyre management, namely batching, bias adjustment, cumulative plotting and the so-called "pressure-temperature" system of tyre pressure control, originated on the Mt Newman Mining Company's Newman minesite, and discusses the contribution that each has made to improving tyre management and reducing costs.

Jan 1, 1983

By R Hardie, J Crerar, J Merritt, B Kirsch

Longwall mining and related subsidence, and watercourse diversion for surface mining operations have the potential to impact on fluvial geomorphic processes and the health of river systems. This is evident in the Isaac River in central Queensland. The scale and likelihood of these impacts are a function of the extent of existing and proposed mining developments and of the ongoing geomorphic, hydrologic and ecological processes within the Isaac River. Understanding the objectives for the river, the past and ongoing processes at work, the cumulative impacts of longwall mining development and the options for managing those impacts is essential for the development of an effective strategy to manage the health of the river system. An assessment has been undertaken to identify and understand the cumulative impacts of mining subsidence and other mining influences on geomorphic processes and waterway health in the Isaac River over a river length of approximately 100 km near Moranbah in central Queensland. The assessment included the development of a vision and objectives for waterway health. The assessment has identified mining and landuse changes that have impacted on the hydrology, geomorphology, ecology and hence the health of the Isaac River. The assessment has then sought to identify the cumulative impact of longwall mining and related subsidence on current stream condition and the proposed vision for the system. The primary impact of longwall mining on the river was found to be associated with sediment transport. The investigation included assess- ment of total sand available for transport, the volume of sand transported annually and the fluvial process response to subsidence. Recommendations have been developed for the management of the system and for longwall mining to increase system robustness and achieve the river health objectives.

Jan 1, 2009

If lead buttons are cupelled under closely controlled conditions in a suitable design of furnace, silver losses during cupellation are given by a simple equation. The effect of copper on these silver losses has been studied and a "copper limit" for cupellation has been determined. Scorification and crucible fusion procedures for copper-bearing materials have been designed so that the lead buttons produced will not contain amounts of copper greater than this determined copper limit. Silver losses during these crucible fusion and scorification procedures are given by the distribution law, and can be calculated. Thus, silver can be determined in copper-bearing materials with a satisfactory degree of accuracy provided that the appropriate corrections for losses are applied to the weight of the silver prill produced.

Jan 1, 1957

In setting out to describe the methods and machinery employed at Iron Knob the writer does not attempt to give any information as to the situation, topography or geological features of the locality. This, together with estimates of the quantities of ore still available, has been carried out in a most thorough manner by R. L. Jackr and F. R. Hockey. This essay is intended to deal with working methods as they exist to-day, beginning with drilling, blasting, quarry traction, etc., and touching on such details as the supplyof electricity, water and compressed air.At the present time almost the entire output of ore is won from the hill known as Iron Monarch. The form of the hill, a smooth, rounded dome, rising some 640 ft. above the plain and having a base diameter of n miles, lends itself ideally to the "bench" system of open-cut quarrying.Fig. 1 shows the relationship of the benches "A," "B" and "E" in their order of development. Bench "E" is at present the principal working, but, as the greater part of the ore above this level has now been removed, bench "A," some...

Jan 1, 1936

Process Options for Difficult Arid-Region Nickel Laterites In the absence of the discovery of significant nickel sulfide deposits, the future of Australia's nickel industry will increasingly depend on cost effect processes for low-grade nickel laterites. The problems encountered with the West Australian HPAL plants, resulting in three of the four plants being shut down, have caused the industry to revisit atmospheric leaching options, particularly heap leaching. West Australian laterites are characteristically very varied in grade, chemical composition and mineralogy with the result that, thus far, one process does not fit all laterites. In this paper the leaching of an especially refractory ore is compared using column leaching of whole ore and atmospheric leaching and HPAL processing of ground ore. The key characteristic is the resistance of the goethite phase to acid attack with low-to-moderate temperature leaching conditions. The refractory characteristic is attributed to the stabilising influence of chromium and aluminium and possibly manganese substitution in the goethite crystal structure and goethite morphology. A significant three-fold increase in both nickel and cobalt extractions under atmospheric leaching conditions was achieved by the relatively simple modification of bubbling sulfur dioxide into the reaction vessel to create a reducing environment. Recoveries increased from <30 per cent to 90 per cent nickel and 86 per cent cobalt after 10 hours of leaching at 95¦C. An even greater improvement was achieved under ambient conditions by heating the ore to temperatures above 250¦C for 30 minutes. Subsequent leaching at ambient temperature gave an eight-fold increase in both nickel and cobalt recoveries after 14 days bottle rolling. Both methods could be optimised and implemented in such a way as to increase laterite reserves in conjunction with a heap leach operation but may be better suited to vat or closed tank processing.

Sep 13, 2010

The plant and processing site at Porgera has been built on a levelled mudstone ridge about lkm E of the mine. Excavation of 7xl06m3 of soil and rock was necessary to achieve the required area. The exposed mudstone belongs to the Chico Formation and is weak, sheared and readily breaks down by slaking upon exposure. Tectonic uplift and subsequent erosion have produced the present landscape of narrow bedrock ridges, with deep colluvium in the incised valleys. The deep excavation to a maximum of 60m, has rapidly unloaded the mudstone, and subsequent stress relief has caused rebound and dilation of the material. The processes of pore pressure equilibration, softening, progressive failure and loosening, combine to deteriorate the newly exposed rock mass. These processes are commonly associated with pre-existing shear surfaces, fissures and a

Jan 1, 1991

By H W. Wu

The objective of this paper is to examine some modern forms of auxiliary ventilation fabric ducting with streamline design fittings and the efficiency of construction practices. The most dynamic form of auxiliary ventilation is a moveable fan and ducting, which is easy to install and uses light weight fabric. The porous nature of some ducting construction results in leakage and loss of efficiency. Flexible fabric ducting is primarily associated with metalliferous mining and industrial material quarrying. Some applications are found in coal in stone/rock development and with use of dust scrubbers.Forcing auxiliary ventilation systems employing circular fabric ducting have been examined. Leakage of air from ducting is affected by ducting material and construction methodology (such as welded or sewn), quality of installation, number of joints, total length, pressure differences between the inside and outside and diameter. The best ducting system with welded construction can have up to four times less leakage as compared with some systems with sewn construction. It is also evident that the sewn type ducting will deliver less air to working faces and require more fan power, hence higher operating costs to run when connected to the same fan.A case study has also been undertaken to compare predicted operating costs of auxiliary ventilation systems connecting various types of ventilation duct fittings. The study also assesses the technical importance of streamline design with low aerodynamic resistance to reduce the shock losses of the duct fittings. It was found that the system connected with streamline designed fittings is able to provide some power cost savings and deliver more air compared with the system fitted with conventional fitting pieces.Using a ventilation ducting system with a lower leakage and frictional characteristic represents a sound solution to new challenges faced by the industry for increasing demand for better quantities and quality of air delivered to working faces; this is due to higher production schedules and stricter mine health and safety regulations within the Australian mining industry.CITATION:Wu, H W and Gillies, A D S, 2017. A comparison of auxiliary ventilation systems and their predicted operational performances, in Proceedings Australian Mine Vent Conference 2017, pp 207–214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By I F. Bell, K P. Hammerschmid

Well planned and executed environmental management plans can reduce life-of-mine operating costs and the need to deal with major environmental issues at the time of mine closure. With proper planning during the exploration, feasibility and execution phases of a project, final closure costs can be reduced. The reduction of closure costs should be considered during exploration and initial feasibility studies and when process facilities, waste rock dumps and tailings impoundments are designed. During the mining of the resource, closure cost reduction will depend on effective and efficient environmental management plans for ongoing land clearance, segregation of mine waste materials, management of mine site water and workshop wastewaters, and the establishment of progressive rehabilitation strategies. These issues are the responsibility of planning, production, technical support and maintenance personnel at an operating site. The successful implementation of environmental plans will ensure that all impacts are reduced and that closure issues with major cost implications are addressed prior to closure of the mine.

Jan 1, 1995

By Linge HG, Fernandez PG, Hughes HC

Aqueous oxidation is a possible alternative to roasting for the processing of gold bearing arsenopyrite (FeAsS) concentrates. The reaction has been studied by voltammetry and this has shown, for the first time, that FeAsS can be readily dissolved without passivation at room temperature in dilute sulphuric acid at relatively modest oxidation potentials (0.7 V SHE). The reaction forms sulphur on the mineral surface and the oxidant consumption is thus minimal. Two practical modes of slurry oxidation are listed.

Jan 1, 1989

By J L. Maule, S J. Mathews, K A. Rodgers

Gold and Silver bearing epithermal veins of the Golden Cross deposit are hosted in Miocene and Pliocene calc-alkaline volcanics occurring 8 km northwest of Waihi at the southern extent of the Coromandel Peninsula, North Island, New Zealand. Veining occurred during a period of hydrothermal activity that began early to late Pliocene, and possibly continued into the Pleistocene.   Field relations and petrographic relationships reveal that multiple generations of FeS2 occur in the Golden Cross region, with FeS2 occurring in all nine rock types recognised at Golden Cross. The variability of FeS2 morphology was investigated by preparation of high purity FeS2 separates, and grain counting. Marcasite is the dominant FeS2 phase at Golden Cross, and along with pyrite is shown to have a systematic habit variation. Pyrite shows a sequence from cubes through octahedra to pyritohedra to dendritic growth. This pyrite sequence conforms to an experimentally determined sequence. The parallel sequence for marcasite at Golden Cross is from tabular through bladed aggregates to euhedral miscellaneous marcasite morphologies. The FeS2 sequences observed are believed to be due to increasing temperature, and perhaps also increasing FeS2-oversaturation and fluid flow.

Jan 1, 1994

By Larkin F, Farrer E, McGhie R. R

The Electrolytic Zinc Company of Australasia Limited commenced productive operations during February, 1936, at the- Rosebery and Hercules mines, which are situated near Rosebery, Tasmania. At this time it was decided that before re-organizing the steel sharpening shop a test should be made of the relative merits of conventional drill-steel and detachable bits. For this purpose Ingersoll-Rand type"I" thread centre hole.jackbits were selected and seventy-two of these were tested against conventional steel. Results indicated that, under the conditions pertaining at these mines, j ackbits should prove more economical than conventional drill-steel bits, and that a large-scale test, under working conditions, should be made. This was done by gradually replacing conventional drill-steel with jackbits at the Rosebery mine. Results were satisfactory and by the end of 1936 both mines were using only the jackbits.

Jan 1, 1939

The placer mining industry of the West Coast region of the South Island is based largely around the production of alluvial gold, although other valuable minerals are also present. Since the first major discoveries in 1864-65, reported gold production has totalled around 264 t (8.5 Moz). During the past 10 years, annual production has totalled around 1460 kg (47,000 oz). It is anticipated that gold production over the next three years will continue at a level of 1400-1800 kg.   Annual gold production peaked during 1866 at approximately 17,170 kg (550,000 oz) and has not exceeded 100,000 oz since 1885. This reflects the ease with which gold was won from shallow, rich deposits that were present at many localities. Subsequently, there has been a general decline in the availability of this type of deposit, a trend that will continue in the future. This paper outlines the present state of placer mining in the West Coast region, gives some historical background to the industry and briefly predicts future trends.

Jan 1, 1997

The presence of gold or tin in a particular place in payable quantities may be suspected from geological and prospE;cting reports. It behoves the engineer by judiciously spaced boreholes or pits to establish whether the place is exploitable with profit, and it is the purpose of this paper to set out the ways in which this is done. The various types of deposit to be considered occur in Malaya, Thafland and Borneo, in which countries the writer spent four years in estimating alluvials.The methods described were used in actual practice both by the writer and previous engineers for the same company. The subsequent exploitation of the alluvials evaluated by the methods given below shows that the recovery was as good as, and sometimes higher than, expected. No claims are made to the originality of the methods, but it is 'felt that they may be new to some engineers and< interesting to others contemplating alluvial testing.

Jan 1, 1942