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Drill and blast excavation in underground mining and. civil engineering projects has grad- ually given ground to mechanical boring of tun- nels, shafts and raises during the past twenty years. The use of.boring equipment must today be considered significant and wide spread al- though comprising only a very small percent of total underground excavation. The encroachment of mechanical boring into the domain of blast- ing has been by slow incremental advances. There have been few, if any major breakthroughs in this development, and none can be foreseen in the next decade. After 1990 it is possible that scientific. development will provide some form of breakthrough in rock breaking, but this is so uncertain that it should have little relevance to planners in the 1980's. A more near term view of the future, con- centrating on the next five to ten years, has lead to the conclusion that significant im- provements will be seen in tunnel borers for poor ground conditions. A universal machine will be developed that converts from a dry hard rock machine to a closed slurry type machine for passing through fault zones with unstable crushed rock and water. Two other machines have been described as alternate designs for tunnelling in squeez- ing ground conditions.

Jan 1, 1981

By S S. Kanchibotla, D La Rosa, R W. Pesch

The Porgera Joint Venture and Dyno Nobel have commissioned a joint project to optimise the drill and blast operations to increase the overall profitability of the mine. One of the aims of this project is to increase the throughput of semi autogenous (SAG) mills by optimising the blast fragmentation. A number of test blasts were conducted during the period May 2000 to January 2002 and the ore from these blasts was campaigned through the mill. The data from these trials suggested up to 15 per cent increase in the SAG mill throughput with high energy blast designs. However, changes in ore geology (shape, structure and hardness) and potential ore dilution/loss and wall damage have raised concerns about the economic benefits of these designs over the entire orebody. The lack of a system to track the economic benefits of these modified designs has also compounded these concerns. PJV and DynoConsult, the consulting arm of Dyno Nobel have initiated steps to minimise the potential for ore dilution and wall damage resulting from these modified designs. DynoConsult worked with Julius Kruttschnitt Mineral Research Centre (JKMRC) to develop and implement a blast management system to track the quality of blast implementation and down stream process benefits. This paper discusses the implementation of the system and the results achieved to date.

Jan 1, 2003

By Tien J. C

Many factors (type of coal mined, water pump pressure, wetting agent concentration, etc) will affect the performance of a dust suppression system using a water spray in an underground coal mine. While a two-level factorial method is useful in

Jan 1, 1994

This paper presents a resume of the likely profitable mining areas in New Zealand. It covers the main "minerals" - gold, coal, oil and gas, ironsands, silica sands, clays, lump silica, perlite, sulphur and limestone.The potential mining projects are depicted on a map of New Zealand together with the associated works involved in hydro-electric and geothermal power development requirement for industries such as aluminium, nickel ferro-silicon or silicon carbide production.The political need for mining development to relieve unemployment and reverse emigration is stressed. A case is made for exploration and development assistance by government in labour re-training, energy supply and transportation, if the tremendous losses through lack of use of human and industrial resources are to be rapidly reduced. These losses are currently estimated at $10,000,000,000 per year.The need for protection of the sanctity of contract and security of tenure of all mining operations is touched on briefly as is the need for a reasonably balanced view on conservation. However as both of these are more properly covered in papers on the legal and environmental aspects of the mining climate they are presented here only as they affect the economy of the mining operation.Finally there is a brief comment on the mining climate in New Zealand relative to Australia and South Pacific mining operations.

Jan 1, 1990

General design of pillars to ensure a continuing roof support during ex- traction is discussed. Practical problems associated with pillar extraction are Outlined.

Jan 1, 1974

By Nilsson C

Man has always been and will always be part of his environment, in ,a good, bad or indifferent manner. Until quite recently, this environment has been the atmospheric boundary layer above the land masses, and to a limited extent the air-sea interface of the oceans. Since the days when he lived in caves, he has built up a wealth of observations on these two environments,-with ever-increasing scientific precision which unfortunately until quite recently was completely insufficient for modern capabilities of data analysis. Consequently, in a sense, he has left in his wake thousands of years of missed, opportunities for making exact observations and increasing his understanding. The data of the past are lost and he has to be satisfied with what he can assemble from now on when his environ- ment, largely as a result of his actions, is exhibiting more and more rapid variations in time; in other words, time series of observations of phenomena are required, the length of which is critical for most purposes of analysis.

Jan 1, 1970

By Hammond J. R, Ward T. A

The Tom Price orebody, in the Hamersley Ranges of North West of Western Australia, is mined by Hamersley Iron Pty. Limited. The orebody is a folded sequence of hematite and shale bands capped with goethite, with a con- sequential variable iron content. The overall grade is below that required to yield spec- ification product, necessitating selective mining, 'Zone Plans' based on geological structure have been developed to yield forward information on material types and grades. Short and medium term mine plans - the initial stage of quality control - are based upon these 'zone plans'. Blasts are laid out to break to the grade boundaries, thus minimising dilution, and the samples taken from the blasthole cuttings provide blast grades. Blending of shovel out- put from different blasts forms the operational basis of grade control. Shales, being more friable than hematite, produce fines that are lower in iron grade than lump. Quality control in the mine centres around maintaining the target fines grade, compensation being applied in the mine if the fines grade lies outside the target range.

Jan 1, 1973

By Potter DJ, Firkin GR

The Imperial Smelting Furnace operated by Sulphide Corporation Pty. Limited at its Cockle Creek zinc-lead smelter was recently equipped with tuyeres angled at 25 degrees instead of the usual 10 degrees. This change was prompted by the results of model studies undertaken by tha Research Department of Imperial Smelting Processes Limited, at Avonmouth in the United Kingdom, and by the favourable results of operating trials on the Cockle Creek furnace using bent-tip tuyeres to simulate 25 degree inclination. The use of 25 degree angle tuyeres has made it possible to operate with lower zinc values in discard slag and has improved hearth stability over a wider range of sinter quality and composition.

Jan 1, 1981

By Selby DW, Hamill J, Cauley ID, Thomas I, Thornton AJ

The main objective of sulphide flotation in a cassiterite concentrator is to remove sulphide minerals (pyrite, pyrrhotite and sometimes chalcopyrite) from the ore prior to gravity concentration. Tin losses in the sulphide flotation stage account for a significant proportion of the total tin loss. separate studies of the sulphide flotation circuits of Renison Ltd and Cleveland Tin Ltd were conducted to investigate reasons for the tin losses. Sampling surveys were conducted in the rougher-scavenger and also the regrind-cleaner sections of both plants. In both plants, the rougher circuits recover excessive quantities of liberated cassiterite, while recovery of the desired composite cassiterite-sulphide fraction is low. The regrind mills are successful in liberating the composite cassiterite in the rougher concentrate, but at the expense of increasing the proportion of very fine tin mineral. The cleaner circuits recover between 40 and 60% of the cassiterite received, and this is all lost.

Jan 1, 1978

By Edwards A. B

Re-opening of the old Proprietary mine has provided new exposures of the system of uralite dolerite dykes observed in 19110 by the Geological Sub-Committee of the Scientific Society of Broken Hill. The newly exposed dykes have been invaded and replaced by the massive ore, with development of manganese garnet and biotite adjacent to the sulphides. A similarly altered dyke in massive ore has been encountered in the North Broken Hill mine.The textures of the unaltered portions of these dykes indicate that they have not been affected by the intense regional metamorphism that has recrystallized the other rocks of the area. Moreover, in mineral composition and textures, in chemical composition, and in cross-cutting relations, they are so similar to the uralite dolerites of the district which post-date the folding and metamorphism of the Broken Hill area, that they must be regarded as typical members of this suite of post-metamorphic dykes.The invasion and replacement of the dykes by the massive sulphide ore, and their metasomatic alteration adjacent to the invading sulphides, establishes that the lode was formed after the dykes were intruded, so that the high temperature features of the ore cannot be attributed to metamorphism and recrystallization, but are primary features of high temperature hydrothermal deposition.INTRODUCTIONTwo cross dykes are recorded on the plan of the 300-ft. level of the Broken Hill lode accompanying the report on the geology of the Broken Hill lode published by the Geological Sub-Committee of the former Scientific Society of Broken Hill (1910). One dyke occurs in Block 12, and the other in Block 13, and both were stated to consist of a dark basic amphibole rock, called diorite for convenience. The more southerly dyke was traced from some distance out in the footwall, and even through the lode, by means of occasionalpatches of it still existing in the ore, in a direction...

Jan 1, 1956

By Wu Y. H, Lu J. P

Slope stability has now become a practical tool in the design and oper- ation of open pits. The stability of rock slope depends on many factors, including not only structural geology, the existence of weak layers, ground- water, blasting and weathering, but also the virgin stress field. This paper presents an application of a numerical method to investigate the effect of the virgin stress on slope stability. The finite element method is employed to simulate the excavation of open pits. Redistributed stress fields in the slope of open pit are computed for several different virgin stress fields. Based on the redistributed stress fields, the shear force which tends to produce sliding of a rock mass and the frictional resistance to sliding are evaluated. The possibility of potential failure is assessed by the limit equilibrium method. The combination of the finite element method with the equilibrium method provides a powerful analytical tool for slope stability. The significant effect of virgin stress on the stability of slopes is shown by studying a typical case.

Jan 1, 1989

By Spottiswood DJ, Kelly EG, Bull WR

An empirical model of a 254mm water-only cyclone treating minus 17001im coal has been developed. The model includes the prediction of by-passing, SG50 corrected, water split and the use of a single equation forthe reduced performance curve of particles in the range 1700-106pm. Particles finer than 106pm did not separate according to specific gravity. Simulations using the model showed the water-only cyclone performance to be dependent more upon feed size distribution than washability when the feed contains high-ash fines, but that, with a deslimed feed, the yield and ash content of the over-flow should be controllable by altering feed rate or feed pulp density.

Jan 1, 1985

The Woodlawn base metal sulphide deposit, located 50km S of Goulbum, New South Wales, was mined as an open pit operation for 10 years from 1977, producing 8 million tonnes of ore. Underground development began in 1985 and reached full production of 500,000t/yr as open pit mining ceased in mid 1987. Underground development highlighted the extensive deformation and intense alteration associated with the deposit and the host rocks.The deposit occurs above an acid volcanic pile in a sequence of interbedded and interfingering shales, cherts, volcanogenic sediments and pyroclastics of mid to late Silurian age intruded by dolerite sills.

Jan 1, 1990

INCREASE OF CATASTROPHE FREQUENCY AND SEVERITYIn the last couple of decades the frequency of natural catastrophes has increased dramatically. This realization results from the statistical analysis of the comprehensive loss data that we have been collecting constantly over the last 30 years and have evaluated in connec-tion with the preparation of our "World Map of Natural Hazards", which is now in its second edition (Munich Re, 1988). Each month brings data on between 30 and 50 new loss events. Fortunately, however, only a few of these have to be added to the list of major natural catastrophes, that is only those involv-ing damage that considerably exceeds what the country or region concerned can handle itself so that substantial na-tional or international aid is required. That is generally the case if the number of dead runs into the hundreds or thousands, if tens or hundreds of thousands of people are rendered home-less and if the total economic loss is in the region of US$ 100 million. These major catastrophes, about which we have fairly comprehensive data even in the case of those that occurred farther back in the past, numbered only 14 in the 1960s but 70 in the 1980s; they there-fore increased over a period of 30 years by a factor of 5. The trend is also very clear when we consider the total economic loss, which - adjusted for in-flation - increased during the same period from an average of US$ 3.7 bil-lion per year to US$ 11.4 billion, i.e. by a factor of 3.1. The insured losses, finally, increased by as much as a fac-tor of 4.8.

Jan 1, 1990

The introduction of new technology into thegold-mining industry has been encouraged in recent years by increases in the price of gold andthe necessity for costs to be contained.At most new gold mines, run-of-mine millingis preferred over crushing and multistage milling, and this change at the head of the circuit leaves no place for the manual sorting of ore and for gravity concentration in the mill circuit.Flotation continues to hold its place in goldrecovery. However, a decline in the demand forsulphuric acid may limit the amount of pyrite thatcan be roasted before cyanidation.

Jan 1, 1984

By Ritchie IM

The Parker Centre was formally established by the Australian Government's Co-operative Research Centre (CRC) Program in 1992 and is one of over 60 such centres encompassing a wide-range of applied scientific and resource based disciplines. Government funding for the CRC Program is currently around $A140 million per annum and the Parker Centre receives $A1.8 million per annum to support its core research and education activities.

Jan 1, 1997

By Liu Y

Mathematical modelling of scrubbers in development and longwall operations in underground mines produces useful results. Mathematical modelling on the mounting of scrubbers on longwall supports shows that the number of scrubbers and the air quantity through the scrubber are the two important parameters. Increase in both these parameters results in decrease in dust levels at the tail gate. The critical factors are scrubber efficiency and the ratio of the air through the scrubber/total air quantity.Results of parametric studies conducted to establish factors which have dominant influence on the effectiveness of the scrubbers on dust levels and high gas build-up in the scrubber show that for use of scrubbers in development headings, the order of importance of parameters in relation to dust concentration in the scrubber area is: scrubber efficiency, rate of production, specific dust make/tonne, leakage factor, intake dust concentration, recirculation factor and air quantity through the scrubber.The equations developed for mathematical analysis and the detailed results of modelling provide useful data on recirculation of emitted gas in the use ofscrubbers for dust control.

Jan 1, 1995

By Jones KW, McClelland RA, Denholm WT, Taylor RN, OÆShea J

Associated Tin Smelters, Sydney, are developing tin smelting operations in a prototype commercial SIROSMELT plant comprising two furnaces of 5 to 8 tonnes capacity. Features of the plant and its operation are discussed and results of its application to tin slag reduction and high-grade tin concentrate smelting are presented. Development work is still in progress but experience indicates that the technology has potential for lowering the costs of tin smelting and relieving constraints on grade and iron content of concentrate imposed by conventional technology.

Jan 1, 1984

By DAVID C LAURENCE

The richer, shallower sapphire deposits of the New England region of New South Wales which have been traditionally mined by the small miner are almost worked out. Larger mining and exploration companies are replacing the small miner and exploring for the primary source of sapphire or lower grade alluvial deposits.Although in recent years considerable exploration effort has been directed at locating the primary source, commercial exploitation of sapphire is still restricted to the working of alluvial deposits.If the Australian industry is to compete against Asian and African producers it must use cost effective exploration, mining, processing and marketing methods.

Jan 1, 1990

By Greg Brown

The underwriting of professional negligence has proved to be an evolving science. As with most insurance products coverage offered in the past was very broad but as legal precedent demonstrated to Insurers areas of unforeseen exposure policy documents per se have become more restrictive until today the insurance market through attrition have produced a basic policy structure with various purchasable extensions which together provide insuring professionals with coverage that has proved to be adequate for their needs. The basic policy provides indemnity and protection for fortuitous negligence. In a practical sense, however, professional indemnity policies are really a defence document in so far as policy holders are relying upon the expertise of Insurers to protect them in the event that a claim is made upon them. Whether damages are awarded is in many respects a secondary consideration, the most important factor is to ensure that policy holders are protected in terms of the legal defence mechanism. By way of illustration we are currently in the process of defending a large professional firm which purchased from us a policy with a limit of indemnity of $10M. The case has been running in a Supreme Court now for 14 months and the defence costs which we have incurred on their behalf are rising close to $8M as I put pen to paper. Defence costs of that magnitude would in effect terminally cripple all but the very largest professional operations in Australia. In more recent times coverage has been provided in Australia for breaches of the Trade Practices Act and similar legislation enacted in various States. No-one really appreciated the comprehensive impact which the Trade Practices Act would have on commerce in Australia. Most professionals thought that indeed they would be exempt from prosecution under this Act. The passage of time has clearly indicated that this is not the case and we have found that it is much more difficult to defend a claim involving breaches of the Trade Practices Act than it would be to defend a claim for breach of tortuous liability.

Jan 1, 1995