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Statistical frequency distributions may be used to characterize the overall variation of grade in orebodies. Special types of distribution (e.g. lognormal, log-type A) are necessary to describe skewness inthe case of rare metals. Also needed (but for the most part hitherto neglected) is the serial correlation function which describes the tendency for grades near together in an orebody to be closer together than grades at points relatively far apart.The sampling problem for orebodies is interpreted in statistical terms. Different methods are reviewed, and the effect of serial correlation discussed.A discussion is given, based on experiments and observations made by the author, of biases arising in the minei:l material by such methods as chip sampling and grab sampling due to such causes as nonrepresentative selection by the sampler.INTRODUCTIONMiners have always recognized the large element of chance in their operations. Chance is the raw material of statistical theory and, provided there is some recognizable pattern or underlying regularity in a set of data arising from the operation of chance events, statisticians are able to formulate mathematical models to study them. Mining engineers, geologists, and statisticians have gone a long way between them towards finding general statistical rules which describe the distribution of minerals and metals in orebodies, and even the distribution of orebodies over the earth's surface.These rules do not have the force of physical laws, though they obviously derive from them and have been used to throw light on them. From statistical theory it is possible to find methods of estimating from sampling some of the characteristics of orebodies which are of importance to...

Jan 1, 1962

In order to maintain an accurate survey underground, it is first necessary to connect all shafts used for the transferring of the survey to the levels below by a precise surface survey.This has been achieved at Mount Isa by a careful triangulation survey with stations adjacent to those shafts most suitably located for transferring the survey below.The precedure used is described herein.The Weisbach triangle commonly used is obtained by reading to swingirig wires, the theodolite being placed in line with them as nearly as is possible. The surveyor at the surface places the wires in the shaft as far apart as the size of the shaft will permit, with sufficient space between the wires and walls to ensure their swinging freely. The far wire is fixed in position, while the near one is movable by means of fine adjusting screws to facilitate its being brought into line with the fixed wire and the theodolite. When this is done the surveyor at the lower level is advised by pre-arranged signals and the survey can then commence.The surface portion of the survey is simple; all that is necessary being to read the angle from the backsight to the wires, measure their distance from the theodolite, and keep a check on them throughout the survey to make sure that no movement takes place.The lower portion of the survey is more difficult, the surveyor first qf all having to place his theodolite as nearly as possible in line with the wires.

Jan 1, 1953

By Liu X

The solubility of cobalt oxide in iron silicate slags has been measured at 1573 K by equilibration of silica and alumina saturated slags with liquid Co-Au-Fe alloys, and by equilibration of silica unsaturated slag with solid Co-Fe alloys, at oxygen pressures of either 10-9 or 10-10 atm (1 atm = 1.013 x 105 Pa). The activity coefficient of cobalt oxide has been calculated and compared with previous studies.

Jan 1, 1991

By G Steward

Gravity Leaching of high-grade gravity gold concentrates, such as Knelson Concentrates, with the ACACIA Reactor represents a new generation of concentrate treatment methods. The ACACIA Reactor is a complete packaged plant for the maximising of gold recoveries from gravity gold concentrates. This paper will introduce the process technology and provide process results from the Porgera ACACIA Reactor installation. The advantages of the ACACIA Reactor are many, and justification for installation has been varied. The typical advantages of the process include: increased recovery of gold from the Knelson Concentrate; no return of high-grade table tails, often grading several thousand g/t, into the mill circuit; reduction in tails grades of slow leaching gold; reduction in the requirement for operating staff by the removal of the manual tabling process and replacing with a fully automated treatment system; improved security by removing the tabling step where operating staff come into direct contact with visible gold; improved health and safety, by the removal of the treatment steps for the table concentrate, which often include operators handling corrosive chemicals and the production of sulphur and arsenic compound fumes; and improved metallurgical accounting, by allowing daily head grade calculations. The ACACIA Reactor was developed by Anglogold for Union ReefÆs Gold Plant and has been in production for over two years, and has proven to be a low cost, high recovery, mechanically reliable method for the processing of gold concentrates. Such has been the success of the plant, there are now four full installations of the processing plant, including Anglogold Union ReefÆs, Anglogold Sunrise Dam, PACMIN Carosue Dam and Porgera Joint Venture.

Jan 1, 2002

With some notable exceptions, marine placers located just below, or just above, present sea level, are responsible for much of today's production of detrital ilmenite, rutile, zircon, and other minerals of value. The purpose of this paper is to discuss the paleogeographic and paleo-oceanographic factors which may have determined the location of presently submerged marine placers. These factors-include changes in sea level, burial by recent marine sediments, stream capture and other i changes in drainage patterns, and recent changes in climate. Selected geologic situations in the Yellow Sea off the coast of Korea, in the Atlantic Ocean off the coast of Portugal, in the Bering Sea off the coast of Alaska, and in the Arabian Sea off the coast of India, will be used to illustrate the author's point of view.

Jan 1, 1980

By D Newton

The Mt Morgan Minesite in Central Queensland has been subject to both underground and surface gold mining operations since the late-1800s. The site is largely unrehabilitated and poor quality surface run-off and subsurface leachate is contaminating the nearby Dee River. The site is dominated by a large open cut, which now stores contaminated surface and subsurface run-off. Three models were used to simulate the complex hydrologic processes occurring at the Mt Morgan Mine: a rainfall-run-off model, a groundwater model and a storage behavioural model. Study results showed that the open cut is filling with water and will soon spill large volumes of highly polluted water to the Dee River on a regular basis if no remedial action is taken. This will result in a three-fold increase in pollutant load to the Dee River. Based on a consideration of water quality and quantity it was concluded that the first priority for future minesite water management should be the prevention of spills from the open cut. Potential management options to achieve this objective included surface rehabilitation, catchment diversions, modification of the pump-back system and controlled releases to the Dee River during floods. However, assessing the relative effectiveness of these measures required a thorough understanding of the complex surface and subsurface hydrology of the site. The results of a 100 year simulation of hydrologic processes revealed that previously favoured management options would be ineffective in preventing spills to the river. On this basis, a continuous treat and release strategy was proposed as the only reliable method of preventing future spills. The results of this study demonstrate that good environmental management decisions must be based on an understanding of the relevant physical processes and consideration of cumulative effects over an appropriate time scale.

Jan 1, 2003

A number of mines in Australia have experienced premature detonations caused by bulk explosives reacting with the rock type being blasted. Premature detonations are extremely high risk events as they are unplanned, occurring at any place, at any time, potentially resulting in high loss (personnel and equipment). Many Australian mines have also experienced spontaneous combustion where spilt explosive reacts vigorously with the rock type. Premature detonation in these cases does not occur due to the lack of confinement and the volume of explosive present, but these reactions could impinge on the surface initiation system and provide an early warning of future premature detonations. The explosive ground reactivity phenomena is not restricted to Australia with similar incidents being reported in North and South America, South Africa, China and South East Asia. All reported incidents have two common denominators, being the presence of sulphide rock types and nitrate based explosives. Both premature detonation and spontaneous combustion result from the same series of reactions of partially weathered sulphides that ultimately result in the violent decomposition of the ammonium nitrate based explosive. A number of relatively easily observable indicators can be used to assess a particular minesiteÆs potential for explosive ground reactivity. The presence of two or more of these indicators means that minesite personnel should contact their explosives manufacturer for assistance in determining if a problem exists and if so then developing strategies to overcome the situation. The paper describes the indicators as well as discussing, via a case study, the holistic approach required to efficiently develop a relevant æSafe and Efficient Blasting ProcedureÆ to deal with explosive ground reactivity problems.

Jan 1, 1999

The phrase "Total-Energy" has, during the past few years, become widely used to describe a wide range of very different operations. However, if accurately described they all have one basic factor in common - energy usage is optimised with the prime mover being powered by gas or oil to generate shaft horsepower and the products of combustion being put to some use. The item which distinguishes a Total Energy system from any other engine or turbine driven project is that orate pains are taken to utilize the waste heat, whether this be in the form of exhaust gases and/or engine jacket ling water. n areas where grid supplies of electricity are readily available, the economics of most projects undoubtedly hinge upon the successful application of waste heat. However, there has been a growing awareness of other benefits, such as reliability of supply, which can be incorporated into the system. In particular these factors sway managements of hospitals and companies with complex computer facilities to examine closely the feasibility of Total Energy, Consequently, in America for example, where many systems have proved themselves the list of applications is wide - shopping centres, apartment blocks, office buildings, airline terminals, universities, schools, motels. And these do not cover the industrial sectors where the range is wider. The total number in North America is now approximately 500 and this to some extent-speaks for itself. In Australia, the real work involved in carrying out feasibility studies for Total Energy is only just beginning. 'in some quarters, the concept is not well received in that it is too new. Therefore, a typical approach is to play safe and wait until some other company has proved its operation "under Australian conditions". This is certainly a realistic approach when considering something revolutionary but as far as Total Energy.is"concerned all the individual components and sometimes combinations, (engines, generators, boilers, air-conditioning units) have been in operation for many years. The only innovation is that they are now all being brought together under one roof. This should not be forgotten when the question "where can I see something like this operating?" is asked.

Jan 1, 1970

By Muir D

A review of the various methods of degrad- ing cyanide either from gold processing liquors or electroplating baths is presented with some discussion on their relative merits or problems. Whilst alkaline chlorination is common practice in many U.S. and Canadian plants it poses particular problems for certain plants. Alter- native methods include electrolysis, hydrolysis and air oxidation with activated carbon as catalyst which are also integral steps in the carbon-in-pulp process. A basic study of the degradation of cyanide ion has been carried out therefore to determine the effect of temperature, oxygen and carbon. It is shown that carbon is an excellent catalyst for degradation by air and likely to lead to higher losses of cyanide in a C.I.L. circuit. Degradation by hydrolysis is important at high temperatures and high pH such as employed in the Pressure Zadra or Anglo elution processes. Carbon catalysed degradation of cyanide by oxygen in effluent streams may be an environmentally acceptable alternative to conventional chlorine degradation.

Jan 1, 1987

By Y Potvin

Risk assessment in the mining industry is currently a topic of great interest with risk methodologies being increasingly applied beyond the traditional areas of finance and feasibility to analyses of risks due to various physical hazards including chemical, electrical, mechanical and geotechnical sources. The application of risk analysis and evaluation techniques to the management of personnel safety is being promoted by both industry and regulators but, particularly for geotechnical hazards, often there are inadequate databases for a meaningful quantitative calculation of risk. In Western Australia over the decade 1987 - 1997, the annual fatality rate for underground mining has averaged at approximately 1.3 in 1000 employees with rockfalls/rockbursts accounting for over half of these deaths (Prevention of Mining Fatalities Taskforce, 1997). Recent improvements have been made since this time, perhaps halving the annual fatality rate, mainly due to industry improving ground control measures and implementing various recommendations from the Prevention of Mining Fatalities Taskforce (1997). However there still remain a large number of unknowns when trying to address the complex area of geotechnical risk in mining. Risk calculations require information about the source of the hazard, the people or assets exposed to the hazard (the æelements at riskÆ) and the effects on these vulnerable elements if the hazard actually occurs (the potential consequences). To date, little information has been available on the exposure of mining personnel and equipment to underground hazards other than occupational safety studies on chemicals, heat, dust, etc. This paper concentrates on underground geotechnical risks and presents a data collection and rating system for the exposure of both the underground workforce and equipment to rockfalls and rockbursts. The methodology considers exposure times, personnel protection levels and hazard proximities to give exposure ratings for the major underground mining activities and hence rate different locations within a mine. This exposure methodology is then applied to the workforce and production/ development cycles in an actual WA underground mine, creating a snapshot map of differing levels of personnel exposure across the mine.

Jan 1, 2003

It is a very great privilege for me to be able to address you tonight and I am deeply sensible of the honour which has been done me. I am equally sensible of the inadequacy of my training for the position of President of your Institute.May I say at once what a very great pleasure it is to have so many members from the mainland States visiting us here in Tasmania. We do hope that you will find pleasure and profit in your stay.Since the Annual Conference is always held in the vicinity of one or other of the great mining fields, it has become the practice for the Presidential address to review the history of the particular field and t(j) indicate its place in the economic structure of the country.I propose to follow this practice and to try and present to you a short picture of thÇ mineral industry as it has existed in Tasmania. None of the information is new it is available in diverse and remote geological reports and in publications such as Witham's Western Tasmania and the more recent Peaks of Lyell. The last composite approach was written twenty years ago by P. B. Nye and published as a Geological Survey Bulletin.I have enjoyed preparing this address because on occasion I find it refreshing to look back and see what was known and what was accomplished in the days when the going was a little tougher than it is now, and to speculate upon the reasons that drove men to do what they did. I shall therefore discuss the search for minerals in this State; the discoveries over the years; the elation with which the new fields are greeted; the disappointments attending some of them; the mines that have come and gone; and the...

Jan 1, 1958

The provision of electrical power is an important consideration in project develop- ment. The first step to be taken in this area is to assess the power requirements of the project. The alternatives of taking a supply from a power authority or providing local generation can then be considered. This requires additional definition of the prob- able characteristics of the supply. The availability of authority power in Australia is limited by the extent of the state power grids. Recent developments now allow these grids to be extended and their load capacity increased to meet major load increases at less cost than was possible pre- viously. The options for local generation include diesel, gas turbine, steam, hydro, solar and wind, each having its particular performance characteristics and costs. The choice of fuel for diesel, gas turbine, and steam plant likewise involves consideration of a range of factors. The arrangements adopted for a number of development projects illustrate some of the aspects which influence the decisions on power supply.

Jan 1, 1986

By H Kundapen, B Bolton, S Miller

The Ok Tedi porphyry copper and gold mine is an open-pit operation located within the Star Mountains in the Western Province of Papua New Guinea and is situated near the headwaters of the Ok Tedi-Fly River system. The climate is equatorial sub-alpine with rainfall ranging from five to ten metres per year. Mining commenced in 1984 and to-date approximately 500 Mt of waste rock has been produced. A failing waste rock dump system operates whereby the dumps are eroded by tributary creeks of the Ok Tedi. It is estimated that approximately 250 Mt of waste is retained within the upper reaches of the river system. The waste rock comprises both potentially acid forming rock and limestone and to-date the overall waste has been acid consuming. However, the long-term mine plan identifies declining limestone production and hence an increasing risk of acid generation over the remaining years of the operation. A program was initiated to determine the net acid producing potential (NAPP) required (ie target NAPP) to minimise the risk of acid generation within the waste rock dumps. The results from this program provide guidelines for an operational target NAPP strategy to provide sufficient acid buffering across all size fractions in the waste rock dump for long-term ARD control. Implementation of this plan requires additional limestone to be mined and co-disposed with ROM waste rock.

Jan 1, 2003

By Mowat BA, Leach TM

The Morobe Goldfield in Papua New Guinea has produced in excess of 120 tonnes of gold from predominantly alluvial sources. Hardrock gold has been mined historically at Wau (23t) and Edie Creek (40 and geological resources have been established at Hidden Valley (780, Kerimenge (360 and Hamata (30t). Numerous prospects have also been identified within the goldfield. Primary gold mineralisation is related to intrusion of dacitic to andesitic Edie Porphyry (2.4 to 3.8 Ma), often with associated diatremes, which have intruded along major regional structures. A full spectrum of deposit styles from proximal (mesothermal) to distal (epithermal) to the porphyry source is recognised. The transition between the proximal and distal styles is recognised both between deposits and within an individual deposit. The deposit styles should be termed porphyry related gold mineralisation rather than given the generic epithermal and mesothermal labels.

Jan 1, 1995

By H R. Watling, W van Bronswijk

Of the various copper sulfides in the EarthÆs crust, chalcopyrite is by far the most common. This mineral is also the most difficult to leach, with hydrometallurgical extraction processes characterised by prohibitively slow kinetics. While a number of processes, including leaching at atmospheric pressure and temperature, pressure leaching at higher temperature, and bioleaching of concentrates in stirred tanks and whole ores in heaps have been demonstrated to some extent, there is currently no full-scale unit process for the hydrometallurgical extraction of copper from chalcopyrite ores. Titan Resources NL operated a test bacterial heap leach at Radio Hill, Western Australia in 2001, to extract nickel and copper from a mixed sulfide ore that contained significant amounts of chalcopyrite, pentlandite and pyrrhotite. A proprietary mixed bacterial culture was used to inoculate the heap, and the nickel and copper were precipitated from the resultant solution as mixed hydroxides. Although 65 per cent of the copper from the Radio Hill heap was eventually recovered, the rate of extraction followed an unexpected trend, as the initial rates of copper recovery were much slower than column tests had suggested. It was postulated that this was due to dissolved copper precipitating as covellite or chalcocite in the most poorly aerated zones within the heap, ie furthest from the aeration pipes at the base. It was further hypothesised that the lack of oxidants (oxygen, ferric iron) and the likely inactivity of bacteria in these areas limited the re-dissolution of such secondary copper precipitates. In this study the above hypothesis was tested in column experiments using the same mixed sulfide ore and a synthetic leach solution. One set of columns was aerated and another set was operated without aeration. Results showed that precipitation of copper occurred regardless of whether the column was aerated or not. The results suggested that pH of the leach solution played a significant part in the precipitation of the copper. Further column tests revealed this to be the case. These results are described here in detail.

Jan 1, 2004

By C J. Corbett

Many underground mining methods rely on blasted rock moving under gravity to report to extraction points. Mining of orebodies dipping between 20 - 45 degrees poses a unique challenge for mining engineers in that a dip angle in this range will not allow the movement of broken ore down the footwall to the mucking horizon utilising gravity. This is more so in cases where the natural angle of repose of the rock is less than the dip of the orebody. Hence, innovative mining systems are necessary to mine this type of orebodies. In Australia, the method of uphole retreat panel stoping is commonly used to extract orebodies in the dip range of 20 - 45 degrees and thickness range of 5 - 15 m. In the Zambian Copperbelt a method called continuous retreat updip stoping is used for orebodies with similar dips and thicknesses. The mechanised form of this mining method has potential for application in the metalliferous mining industry in Australia. In this study a comparison is made between mechanised updip (MUDS) and transverse retreat stoping (TRS) methods. A hypothetical nickel sulphide orebody located in Western Australia is used as case study. The net present value for mechanised updip stoping is seven per cent higher than that of transverse retreat stoping based on the assumptions applied. Initial results of this study indicate that mechanised updip stoping can be adopted for Australian mining conditions. However, lack of significant local experience with the method is often cited as a reason for not adopting it even in situations where it is clearly the best option.

Jan 1, 2003

A blast is designed to completely break competent rock such that it can be economically extracted, and efficiently handled or processed. Efficient breakage of the rock is critical to the success of an operation, and in many operations blast design is optimised to achieve fragmentation, muckpile profiles, and material that is easily excavated. There are inevitably other issues, such as damage to adjacent rock, that should be taken into account when designing a blast to achieve overall optimisation. Some of the key issues with respect to the integrity of the in situ materials adjacent to a blast are identified and briefly discussed in this paper. The potential for damage and the effects of a blast will be strongly influenced by the rock mass properties. This makes it important that site specific conditions and their response to blasting are known. Practical techniques that allow the disturbance adjacent to a blast to be measured with minimum disturbance to operations are described in the paper. Experience shows that, during the blasting process, there is considerable potential to disturb the in situ rock mass adjacent to the blast. In some circumstances a very important objective must be to minimise disturbance outside of the immediate blast area. Measured and observed disturbances caused by blasting to adjacent rock, for various common types of blasting, are discussed in this paper. Blast induced disturbances to the rock mass have been observed in both the near and far fields. These disturbances have the potential to impact on geotechnical design. The geotechnical significance of blast disturbance on a rock mass that is to remain in situ is explored and suggestions with respect to design are given.

Jan 1, 2004

By Blaskett K. S

The physical properties of monazite and the minerals with which it is associated in east coast beach sands are studied and discussed. Possible means for improving recovery are examined. In particular, it is suggested that the practice of splitting the heavy mineral concentrate into two parts as a preliminary to treatment in separate "rutile" and "zircon" mills can be modified in a simple fashion by the addition of an extra magnetic separation stage so as to aid monazite recovery.INTRODUCTIONBeach sand deposits on the east coast of Australia are a major source of rutile and zircon, and supply 80 per cent or more of world requirements. The deposits also contain a small amount of monazite, averaging about 0.5 per cent of the total heavy minerals. Yet despite a steady price in recent years of £150-160 per ton, monazite production has remained relatively small.On the basis of rutiIe production, potential monazite production on the east coast was about 1,500 tons in 1956, but only 102 tons of high-grade concentrate was produced. The main deterrent to increased production has probably been the capital cost of the necessary equipment. Separate electrostatic and magnetic equipment and separate table concentration and drying constitute a considerable outlay for a by-product contributing 4 to 5 per cent of the revenue from rutiIe.It is the purpose of this paper to discuss monazite concentration generally and to suggest modifications to flowsheets, which may facilitate monazite production while maintaining the main objective, simple and cheap means for maximum rutile production.

Jan 1, 1958

By Kershaw M. G

At the Risdon plant of the Electrolytic Zinc Company of Australasia Limited, impurities toxic to the electrolytic production of zinc metal, notably arsenic and antimony, have traditionally been coprecipitated when precipitating iron as ferric hydroxide. With the development of a new lead/zinc mine at Elura, New South Wales, it was anticipated that the concentration of impurities, particularly arsenic, in the zinc sulphide concentrates treated at Risdon would increase. This suggested that an increase in the capacity of the iron purification step in the Risdon plant would be required to cope with the higher input of these impurities.Laboratory investigations showed that the additional capacity would be achieved, either by a large increase in the amount of iron used as the "collector" in the process, or by a two-stage process. The latter approach was preferred as a increase in the amount of iron precipitated would lead to much higher operating costs and overloading of the existing equipment.In the two stage procedure, acidic iron bearing solution is added to solution feeding the first stage and most of the arsenic removed from solution when iron is precipitated from solution by neutralisation with limestone. Mter separation of the precipitated solids, acidic iron bearing solution is added to the solution, and remaining arsenic removed almost completely following neutralisation by limestone.This paper describes the laboratory and pilot plant results and the plant modifications required. Abrief account is also given of the operator training and acceptance in the use of the digital control facilities installed in the new plant.The new plant is working well and good solution purity is being maintained despite a substantial increase in the concentration of impurities in the raw materials.

Jan 1, 1990

By Schommarz KH, Dunne RC, Goodall CM

Column cells are widely used today for the recovery of base metals by flotation. Their use for the flotation of iron sulphides has not been as rapid. Australia has pioneered the use of large rougher flotation columns. During the last six years, seven rougher columns have been installed on gold mines treating iron sulphides and the technical viability of this technology has been demonstrated. Laboratory column testwork on a gold bearing iron sulphide ore demonstrated the effects of both physical and chemical parameters. In general the large commercial columns operate over a broad range of conditions depending on the downstream treatment of the flotation concentrate. The addition of wash water to commercial columns is not universally applied and there appears to be a need for a better wash water System.

Jan 1, 1993