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Blasting is known to be both an important and an easily quantified cost factor in rock breaking operations. However, the indirect costs and benefits of the blasting operation are not easily determined due to the irreversibility of the mechanisms involved and the multiplicity of influencing factors. A general conceptual model showing the relationship between blasting and mining costs is well known, but serious attempts to address the critical real relationships have all floundered on the fact that not enough is yet known about either detonation physics or blasting effects. This can only be remedied to the extent that blasting instrumentation enables researchers to pin down not only the relationship between the detonation process and its impact on a particular environment, but also the downhill costs of handling the rock, repairing any damage and building in "Safety Factors" to provide for imponderables. It is vital to standaraize on specifications for instrumentation and measurement techniques and there is a need to review what has been achieved in blasting expertise so as to focus on the most fruitful paths for future work.

Jan 1, 1990

By Khosrowshahi S

The objectives of grade control remain unchanged but new methods are being developed to attain them. Since the early-1990s, an improvement in the power of mine site computers has made the geostatistical tools of conditional simulation more accessible. Optimisation of the grade control process on mine sites now involves two stages: optimisation of the sampling regime and optimisation of the interpretation of ore and waste boundaries. Optimisation of the sampling regime first requires an understanding of the nature of the mineralisation and in particular the impact of particle size on the sampling precision. This relationship, termed the Fundamental Error of sampling, enables an optimum subsampling protocol to be defined for the sample preparation and assaying. However, the actual sample collection method, whether drilling or trenching, must be correctly selected and the sampling grid should be optimised. The relative costs and benefits of various alternative sampling methods and grids can be determined using the method discussed. The use of the grade control data can also be optimised. In the past ore and waste boundaries were often defined using a linear interpolation algorithm that smoothed the data (such as polygonal, sectional, inverse distance squared or even kriging methods). Frequently the relative impact of ore loss and dilution could not be estimated. Conditional simulation to generate equiprobable alternative maps (realisations) can now be adopted to address these issues. A transfer function is then used to evaluate the similarities and differences between the maps. The Ore Block Optimisation (OBO¬) process is a transfer function that produces a three-dimensional model of the optimal ore block outlines. This provides a clear guide for the mining geologist to refine and mine. The nature of the transfer function and the inputs and outputs are discussed. In the past, reconciliation has been the `acid test' for any grade control system. Any ore blocking method based on conditional simulation can make use of the exhaustive data set to ensure that reconciliation between prediction and production will improve significantly. The OBO¬ method provides a guide to the mining geologist to ensure that the best ore blocks are mined. Misclassification between ore and waste is reduced, ore loss and dilution are minimised (and are measurable) and ore is optimally assigned to stockpiles of various cut-off grades. These advantages significantly enhance mine profitability and control of the mined grade.

Jan 1, 1997

By Lawson F

The leaching behaviour of BHAS copper matte in oxygenated acidic sulphate chloride solutions at 85¦C has been studied using samples containing 34% copper, 41% lead and 12% sulphur. Copper sulphide in the matte, essentially Cu2S was found to leach in two distinct stages. Similar to the behaviour of pure chalcocite, copper dissolution in the first stage was affected by the availability of oxygen in solution. The presence of chloride ions in the leachant was essential if there was to be any leaching in the second stage (which usually commenced after about 40% of the copper had been taken into solution). Lead sulphide in the matte was oxidised to lead sulphate and formed a shell around the partially leached matte particles. Electrochemical studies showed that this lead sulphate and/or sulphur produced during leaching can form a passivating layer around the copper sulphide. However, this layer was disrupted when chloride ions were present. A Plackett-Burman analysis was used to determine the species in the recycled leach solution that affect the leaching of copper. Under the experimental conditions used, in the first stage the rate of copper dissolution was influenced by the concentrations of sulphuric acid, Zn(II), Cu(II), Fe(III) and Cd(II). In the second stage, the rate was futher modified by the concentrations of Cl(I) and As(V) ions. In solutions of low acidity and high As(V) concentration, insoluble copper arsenate formed which coated the partially leached matte particles and acted as a barrier to futher reaction.

Jan 1, 1989

Efforts to stabilize international markets in commodities have gradually intensified during the course of this century in keeping with the grow- ing complexity and interdependence of the world economy and the increasing involvement of government in economic activity. Successive Australian Governments have con- sistently supported the concept of commodity agreements and arrangements in an effort to lessen short term fluctuations in price and to moderate the boom/bust conditions which tend to charac- terize production and trade in many commodities. The objective is to stabilize price at a level which equates supply and demand over the life of the arrangement. Such action involves a degree of market inter- vention and government involvement in the inter- national trade in the commodity concerned; the acceptability and desire to foster such arrange- ments varies from country to country depending upon attitudes to market intervention and man- agement. However attitudes, even among those opposing commodity agreements, have under- gone a major reversal in this century. Before the first world war, such intervention as existed almost entirely involved the physical producers. There was almost no government involvement and at that level most regarded commodity agree- ments as neither desirable nor practical. However government regulation of such activities as pro- duction and marketing of food during World War I, coupled with post-war shortages, followed by overproduction and the crash in prices during the Great Depression, stimulated producer gov- ernment interest in commodity market regulation. Consumer governments took a little longer and with a few exceptions, it was not until the post World War II period, that the fear of shortages of basic commodities brought some consumer countries to accept the concept.

Jan 1, 1978

Until recently, nickel laterite projects have been largely ignored, due to their supposedly higher treatment costs compared with sulphides, and to their perceived processing difficulties. A number of laterite projects in the 1970s were abandoned because of high capital and operating costs, while others experienced severe technical difficulties. Conventional wisdom had it that laterites would not be exploited until most of the sulphide orebodies had been depleted. Why then, have Australian mining and exploration companies started a resurgence of interest in the treatment of nickel laterites? It all began with the Bulong project, which has been under study since 1987, while more recently two further projects, Murrin Murrin and Cawse, have been initiated and are being fast-tracked to take advantage of the current high nickel and cobalt prices. A further project in NSW, Syerston, has also been investigated at bench-scale, but no further development has yet been announced. All these projects have the following advantages: 1. Good location near a major mining centre and,reasonably close to power, water, roads, accommodation and a developed service industry. 2. Straightforward, low cost mining. 3. Low cost of acid or sulphur. 4. Good to very good cobalt credits. In addition, there have been significant technological developments in the design and operation of high pressure autoclaves and high rate thickeners, as well as solvent extraction and electrowinning technology. This has helped to decrease capital costs and technical risks, and has allowed the development of alternative flowsheets to the existing laterite operations (Taylor, 1996).

Jan 1, 1996

The establishment of vegetation onto open cut mine spoil is dependant on the nature of the soil and rock strata of the overburden. Experience has shown that in the Bowen Basin of Central Queensland the nature of the minespoil changes considerably as subsequent and deeper mining strips intercept changing rock strata. The different mixes of strata at the surface of reshaped spoilpiles can produce variable response in the sown vegetation cover. It is usual that land features of mine sites are known in detail and are depicted on mine or locality maps. Subsurface strata and lithology descriptions are available and are used for planning of open cut mining operations. Surface and subsurface data can also be used to estimate the intrinsic nature of overburden through the use of fence diagrams. Lithology at points along a mined strip can be obtained and used to describe overburden. Indications are that correlations exist between salinity of overburden components and the response of vegetation. The developed procedure thus becomes a useful tool for the prediction of revegetation Practices.

Jan 1, 1987

By Eupene GS

The valuation of exploration properties which contain no identified resources or reserves is the most subjective of all valuation tasks likely to be carried out by a geologist. The geoscience rating method proposed by Kilburn (1990) recognises this inherent subjectivity but also attempts to apply some discipline to the valuation process. Some other methods used for valuations of this type clearly lack discipline and are open to misuse and abuse. The Kilburn method essentially requires the practitioner to justify all aspects of the valuation process. The valuer must specify and, more importantly, quantify aspects which enhance or downgrade the intrinsic value of each property. The intrinsic value is called the ""base acquisition cost"" (BAC) and it represents the average cost to identify, apply for and retain a base unit of area of title. The BAC and base unit of area both vary with different types of exploration and mining title but remain constant for similar types of titles in the same mineral tenure regime. In the Kilburn Method the enhancement/ downgrading factors are determined by the geotechnical prospectivity (Kilburn Method) within the title. A modified version of the Kilburn Method presented here (""Modified Kilburn Method"") also focuses attention on other real variables besides the geotechnical attributes which influence valuations of this type, viz., competition for tenure and activity in the markets in which the exploration properties are being traded. The most active such market at present is the stock market. By utilising uniform BACs and base units of area (for similar titles) for all exploration properties (in practice in Australia this is only possible within a particular State or Territory), the method exposes the valuer's opinions of each of these variables to the scrutiny of the investor. The investor (or his professional adviser) is afforded the opportunity to directly compare valuations on different properties by different practitioners and can assess how the final valuation is weighted in respect of geotechnical prospectivity, competition for tenure, and stock/financial market sentiment. No other method currently employed in Australia to value mineral exploration properties affords the investor this `luxury', which some may argue is their right.

Jan 1, 1994

By P Andrieux

By 1996 ground control-related problems at Brunswick Mine had raised serious concerns regarding the safe and economical extraction of large portions of the reserves. These difficulties were mainly caused by high stress levels in pillars, instabilities resulting from wide spans supported by ageing support elements, and chronic difficulties supplying rock fill from the surface quarry to the underground workings, which resulted in many large voids remaining open for long periods of time. Significant changes have been implemented at the site since 1996, amongst which were a change of mining method, the introduction of paste backfill, the establishment of stress management measures, and the introduction of shotcrete on a large-scale. This paper focuses on the regional ground conditions associated with both the previously used primary-secondary mining method and the newly implemented pyramidal pillarless technique, as well as on some of the stress management measures implemented at the mine.

Jan 1, 2000

By Johnson RD

The variation in coal properties and the coal seam reduced level can be analysed using partial trend-surface analysis techniques. For the area studied seam reduced level and seam thickness data from the Bulli Coal yield trend-surfaces with a high coefficient of determination, since they have relatively small systematic local and random components in their overall variation. Sulphur content appears to have no significant re.gi_onal trend, and phosphorus content has a very weak regional trend. Other analytical variables have regional trends which are of intermediate strength. The strike-directions of.the statistically significant first degree! trend-surface are similar, sug-gesting.: that the variation of the several coal properties was controlled by a set of- related causes. The relations apparent from the dip and strike of the first degree trend-surfaces are similar to- those which are apparent from the trend- surface residuals and'from the results' of canonical trend-surface analysis.'.. It is probable that differential subsidence controlled the areal

Jan 1, 1975

By Davey KJ

Complex sulphide ores are characterised by complex texture of the valuable minerals. Any assessment of the performance of differential flotation circuits treating such ore should include analysis of the effects of poor liberation of the valuable minerals. Selected samples were taken from balanced size by size surveys of the flotation section of a concentrator treating an ore body containing fine grained galena and sphalerite in a matrix of iron sulphides which is mostly pyrite. liberation measurements were made using the QEM*SEM system on four or seven size fractions. The measurements indicated that less than 40 per cent of the galena and less than 60 per cent of the sphalerite in the flotation feed was liberated. The final concentrates were largely composed of composites of valuable minerals and iron sulphide however there was a small but significant fraction of liberated iron sulphide. Using the sized mineral flows obtained from the original balances and the liberation measurements, a satisfactory liberation balance was obtained. This enabled the effect of liberation on the flotation performance to be examined; not only for the entire circuit but also in the rougher, scavenger and cleaning sections. In the zinc circuit the effect of a regrind mill could be assessed. Recovery of galena in the lead circuit was limited by the recovery of composite lead particles. Recovery of liberated galena exceeded 95 per cent in all size fractions while the recovery of composite galena exceeded 85 per cent below 38 ¦m but fell sharply above 38 ¦m. Examination of the behaviour of the liberated and composite galena in the various sections of the lead flotation circuit revealed high recoveries of both liberated and composite galena particles in the roughing and scavenging sections but very low recoveries in the final two cleaning stages. Similar trends to those observed in the lead circuit applied in the zinc circuit although the performance of the liberated sphalerite also fell off at sizes greater than 38 pm in this case. Thus the zinc recovery was limited by the flotation of both the liberated and the composite sphalerite. The effect of regrinding was to increase the recovery of sphalerite mainly by reducing the amounts of sphalerite in less liberated sizes rather than by increasing the liberation of the sphalerite within a given size Fraction.

Jan 1, 1993

The Mt Leyshon Gold Mine is located 30 kilometres south of Charters Towers in Northern Queensland. The current open cut mine has been in operation since 1986. In 1992 a feasibility study was completed that recommended an increase in production to over 240 000 ounces of gold per year. This proposal required an upgrade of the processing plant to five million tonnes per year, and an enlarged mining fleet to provide additional ore, and to meet the increased waste removal requirements. The implementation of the mine expansion program during 1993 required the Life of Mine plan to be extensively revised. This required the assessment and management of potential risks associated with the mine design. The updated geological model using the 1992 drilling results along with the actual contract mining and processing costs were used to establish a series of nested optimised pit shells. The total and incremental quantities and costs were then analysed to determine a suitable pit perimeter. The pit and phase plans were then created and used to devise a staged development plan. The block layout plans for each bench were then established from which a detailed life of mine production schedule was created.

Jan 1, 1994

By M F. Lee

In order to make good decisions, as to whether large diameter raise bored shafts can be constructed in blocky rock at a particular location, mine planners, management, geotechnical engineers and contractors must understand and consider a range of geotechnical issues. Firstly, mine management must ensure that adequate time and resources are available to find appropriate shaft sites. Deep weathering, adverse structures, groundwater, etc might mean that the most desirable location, with respect to other mine development, might not be suitable. Special site investigation drilling, etc may be necessary. Even then, alternative construction options might be necessary, other than just reaming through to the surface. A site investigation borehole should then be drilled to investigate specific and general ground conditions along the raise alignment. Often, only small sections of weak blocky rock dictate raise stability. While the empirical McCracken and Stacey method is typically used in Australia to assess raise stability and assess geotechnical risk, until recently it had no published performance data.An Australian database of raise performance now exists and is presented below, courtesy of an industry survey by the Eastern Australian Ground Control Group. Raise diameter and ground conditions (in terms of a lower bound Qr value) is presented for 50 cases versus raise performance.

Jan 1, 2008

By Juniper LA

ERM Consultants Pty Ltd was established in 1980 for the purpose of introducing a disciplined coal technology and power station planning service, to support Australia's efforts in establishing a major export steaming coal industry. At that time, major coal exploration programs were mounted on more than 50 potential export coal deposits with proven open-cut reserves to export 200 Mt/a of coal. The fact that Australia achieved an export trade of only 30 Mt/a, equivalent to the energy requirements for a population of around 5 million people, illustrates the very small achievement to date. The main reasons for this small export steaming coal growth have been: 1. Failure to convince potential overseas coal buyers of the benefits of coal-fired power generation, and the ability of proper power station design to overcome environmental problems, and achieve reliable operation and long life when burning Australian coals. 2. Failure to promote Australian power engineers to advise on the use of Australian coals, resulting in Northern Hemisphere power station experience dominating in market countries. 3. Failure of governments to draw on privately practising Australian power engineers and coal technologists in technical workshops, presentations and assistance to overseas countries, to ensure that personnel whose business it was to serve the follow-on needs of countries were readily available. The result of these failures has been that: 1. Only a fraction of prospective overseas coal-fired power projects have proceeded. 2. Australia has had no influence in the design of overseas power stations to ensure that potential customers would be confident that Australian coals could be reliably burnt in their boilers.

Jan 1, 1987

During the 20th century, the iron ore mining industries of Canada and the United States passed through several periods of transformation. The beginning of the 21st century has seen yet another period of transformation, with the economic failure of a number of steel companies, the acquisition of their facilities by more viable steelmakers, and the consolidation of control within the North American iron ore industry. Changes in Canadian and United States iron ore production and the market control structure involved are analysed. The consolidation of ownership, formation of foreign joint ventures within North America, planned divestitures of upstream activities by steelmakers, and industry changes made to ensure availability of feedstocks will be reviewed. The traditional isolation of the Canadian and United States iron ore operations and their strong linkage to downstream steel production will be discussed in the context of a changing global economy. Management-labour conflicts that have taken place and agreements made during 2000 through 2004 will be discussed in the context of the economic environment leading up to these agreements. Cooperative agreements between competing Canadian and United States companies to resolve client needs in processing and blending will be examined. A joint industry-government project designed to use new technology to produce direct reduced iron nuggets of 96 - 98 per cent iron content using non-coking coals will also be assessed. Changes in iron ore transportation methods, ownership and infrastructure will be reviewed for both rail and inland waterway transport between Canadian and United States companies. A brief analysis of social and environmental issues relating to sustainable development of the Canadian-United States iron ore industry will be included.

Jan 1, 2005

By H P÷llmann

Calcium aluminates, calcium aluminate ferrate and calcium aluminate sulfate were synthesised by solid-state reaction, sol-gel method, a self-combustion method and by a polymeric precursor process. For chemical sintering methods the base chemicals CaO, CaSO4, Al2O3 and Fe2O3 were used. As precursors for sol-gel synthesis metal nitrate hydrates and Al2O3-Sol were used. In order to synthesise pure phases by a self-combustion reaction glycine was used as fuel and nitrates as metal components. In the polymeric precursor process metal nitrates and diluted H2SO4 were used as metal components and the resin was made using citric acid (C6H8O7) and ethylene glycol (C2H6O2). Precursor phases synthesised by these different methods were sintered step-by-step in order to investigate the crystallisation. Further on single phases were hydrated and their hydration behaviour was studied by heat flow calorimetry, X-ray diffraction and cryo-transfer scanning electron microscopy. Due to the different synthesis procedures different hydration reactions and microstructures of the phases will be shown.

Jan 1, 2008

By Olden WH

A scheme is presented whereby the complexities of design and operation of a hydraulically powered coalmine support are modelled using the finite element method. This enables predictions to be made of the interaction of the support with its environment in a variety of operating conditions. The model is a two dimensional representation. The modelling scheme was applied in two case studies. In the first, the performance of a four leg support was uprated by increasing the front leg force. The finite element model enabled changes in overall support performance to be verified. In the second case study, the change in lateral force developed by a two leg support was assessed with changes in support operating height and floor foundation stiffness. The modelling scheme is capable of further development with the possibility of extending the model into three dimensions and the addition of control elements that would enable an actual mining sequence to be Represented.

Jan 1, 1992

By Cerutty L

To those who have been engaged in the construction of mining and metallurgical plants during the war and post-war periods, it is quite unnecessary to point out the large increases and violent fluctuations in prices of basic commodities and the steady and persistent rise in labour costs. It may, however, be of interest to present these facts in graphic form, and survey the relative heights of the various maxima and the lead and lag of individual waves. Since Descartes demonstrated for us moderns the analogy between geometric form and algebraic statements, the two-dimensional graph has found widespread application. Mathematicians have developed for our information, if not for our confusion, the triangular diagram and the solid three-dimensional figures, which have proved so useful, at least in the hands of the metallurgists at Port Pirie. The model (Plate 1.) which is exhibited here does not pretend however, to indicate the connection between any three inter-related variables, and it is not proposed to burden members with any abstruse mathematical expression for the irregular surface of the blocks. While time is an ordinate common to all sections of the model, each illustrates separately the variation in cost of some particular quantity between the years 1914 and 1922. It is an easy matter to record such individual variations, but it would be an impossible task to state any equation describing accurately the dependence ot the prices, say, of hardwood or of galvanized iron upon that of labour at any particular point of time. The cost of living curve, which has attained such prominence, if not notoriety, in the last few years, is the result of an attempt to show the mass-effect of the components. It is the difficulty found in "assigning the correct weight to the separate items which makes the aggregate curve somewhat misleading at times.Turning to the model, it will be noticed that each section consists of half a dozen pegs.. The first in each row,that coloured red, represents the cost of some particular quantity, such as bricks, timber or coal, at Broken Hill in 1914. The next peg, that coloured blue, represents proportionately prices for that quantity in Hobart during...

Jan 1, 1922

By H Rose, T J. Sheer, M Dumka

Whenever rock is tipped from above, severe eruptions of airborne dust occur into the airways connected to tipping stations of rock passes (ore and waste) on the lower levels of a gold mine in the North West Province of South Africa. An investigation was undertaken to understand the nature of the physical phenomenon, in order to propose possible solutions. Accordingly, measurements were taken underground, involving the simultaneous logging at two levels of the transient pressures produced in the orepass by tipping from various levels. Two portable data loggers with associated transducers were custom-built for this purpose. Measurements were taken during a tipping program in which rock quantities and levels were controlled. Pressure pulses that are generated by the falling rock drive the airborne-dust eruptions. When tipping from a specified level, recorded pressure pulse waveforms were found to be repeatable on any given level, irrespective of the amount of rock falling, but measurements were conspicuously different on different levels. It was recognised that a pressure pulse is generated as the falling rock passes through the constricted region û a relatively narrow neck û at each tipping station. In passing through the constricted areas the mass of falling rock acts as a æleaky piston in a cylinderÆ and compresses the length of the air column in the orepass below that level. Once the rock has passed through the constriction, the pressure is released and this behaviour causes a regular train of pressure pulses that are separated by the time taken for the rock to move from one level to the next. Based on this physical understanding of the dust eruptions, a computational model has been developed that can reproduce all the main features of the measured phenomena. The model has been verified adequately against the measurements and can now form the basis for simulating a range of possible engineering solutions.

Jan 1, 2005

By D V. Boger

The use of chemical additives to initiate such processes as particulate separation through flotation or dewatering through flocculation, is common in the mining industry. The dosing of additives is none the less poorly controlled from a process control viewpoint and it is perhaps fortuitous that over-dosing or misuse of chemicals is rarely catastrophic to the production cycle. In many cases, such events would go undetected if it were not for economic considerations. Recently, the advent of orebodies with finer mineral disseminations and the push for greater efficiencies in both production and tailing disposal have resulted in the need for greater control of the dosing and utilisation of chemical additives. The need to grind at higher pulp densities and to finer sizes and to dewater to higher solid contents are but two examples that require a more stringent understanding of the true role of additives in controlling the rheology of suspensions and the influence of additives on the surface chemistry of particles. The inter-relationship between the surface chemistry of particles and the role of additives in controlling suspension rheology is now well understood for systems in which the average particle shape in the mixture is spherical or close to spherical. Luckily, this is the case for a large number of systems in the mining industry and the true role of typical additives in these systems will be explored. Difficulties arise for suspensions containing clays or other platey or needle shaped minerals and in many cases, quite small quantities of platey minerals dominate the rheology of suspensions. The role of additives in controlling the rheology of asymmetric particle systems is more complex but the effect of the additive in changing particle alignment in solution is the key to understanding suspension behaviour. The manipulation of the rheology of asymmetric particle systems will also be explored.

Jan 1, 1998

By S Youds

The backfilling operation at Olympic Dam mine supports a 9.8 Mtpa underground Long Hole Open Stoping (LHOS) operation. It involves a combination of Cemented Aggregate Fill (CAF), surface rockfill and underground rockfill. The fill material is introduced from the surface via boreholes into the top of the stopes. Due to the deleterious effects of the dust and the thickness of the atmosphere in the stope it is not possible to view the filling process either at optical or infrared (IR) wavelengths. The need for a means to measure the filling process is driven by the placement of both rock and CAF fill in the stopes. The large volumes and high relative cost of CAF makes the minimisation of CAF fill a business priority. Incorrect filling can lead to the sterilisation of ore reserve. The use of millimeter wave radar to view through the haze to give real-time data on the relative positions of the different fill masses is being developed as an in-stope fill monitoring device. This paper reviews the salient points of the technology and its potential use in the backfilling operation at Olympic Dam. The broader potential of this technology for use in the mining industry by æseeingÆ through water and dust laden environments such as that found in stopes and ore passes is also discussed.

Jan 1, 2002