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A good blending system is one that ensures that a plant can cope with the amount of grade variation that it will encounter. Prediction of amounts of variation that will be encountered on time or tonnage scales that are important should be regarded as an essential part of the planning of mines and plants. In some cases, the natural amount of grade variation when ore is mined and handled in the cheapest way will be acceptable. In other cases, it is necessary to understand the effects that various ore-handling processes have on amounts of grade variation at various scales and to design a blending system with considerable care. Blending tends to matter more when plants are sensitive to many aspects of grade. It can be very difficult to find the best compromise between capital cost and the amount of grade variation. In these cases it is important that ore blending options be considered carefully as part of the planning of mines and plants. Failure to make plans that consider likely amounts of variation can be very expensive.

Mar 1, 2010

By Goldie R

The use of options theory in business has become well established in recent years and is currently one of the most exciting areas of current finance research. The theory can be used to value levered firms, and streams of contingent payments. This technique also has very practical applications in the areas of capital investment analysis and the valuation of equities in the natural resource industry. The use of options theory has been well accepted and used for many years in the trading of commodity options and futures contracts, in banking and insurance and in other industries. It also can be used to value such diverse contingent claims problems as the income tax liabilities of the firm and share underwriting agreements.Its application to the more complex options, such as those present in the resource industry, is only now becoming known. This lag is, at least partially, due to the difficult mathematics involved in solving complex options problems. Another factor is the almost overwhelming abundance of uncertainties, such as grade, tons and other natural risks, which must be considered in the evaluation mining projects.

Jan 1, 1990

The implementation of the Mining Further Amendment) Act, 1970, and later the Coal Mining Act, 1973, placed a requirement on the Department of Mines to accept an initiative in relation to coal exploration and coal mine development which does not apply in the case of other minerals. It is necessary to consider the exploration of the total coal resources of the State when considering exploration rather than one individual basin or deposit. If the level of knowledge of the coal resources in these basins is considered in relation to their potential for development it is possible to allocate broad scale priorities to their assessment. Due to the enormity of the task which involves a conservative estimate of in excess of 400 000 m of drilling to reach a broad reconnaissance level of understanding the involvement of industry with the Department in the exploration programme is necessary. The development of the coal deposits by mining operations must give consideration to a number of constraints apart from the simple availability of the resources. Principal among these are aspects

Jan 1, 1976

This paper explains why the valuation of mining assets is often a very different exercise from the valuation of the shares in the mining company which owns those assets. The fundamental reason for this is that mining assets, and the shares of the company which owns those assets have different risks. In order to properly value mining securities it is essential to: ò ensure all the different risks and other factors which impact on the value of the mining assets and the value of the shares are taken into account; and determine the extent to which the different risks and other factors are addressed in the value of the mining assets and the value of the shares so as to avoid double counting or not counting at all. If the alternative, but far from consensus, view is accepted that the correct valuation methodology to apply to shares in mining companies should be based on option pricing theory then conventional valuation practice of both mining assets and shares in mining companies will need to be fundamentally reassessed.

Jan 1, 1994

By Parker GJ

The financing of smaller resource projects has proven to be a difficult problem for promoters and financiers alike as very often such projects have not met the requirements of available financing methods and promoters have equally found it difficult to establish credibility, management and technical ability with potential financing sources. Solutions to the dilemma in which many of these projects find themselves are not readily apparent but will need to be found if the full potential of Australia's resources is to be realised. INTRODUCTION The growth of so called project financing in its present form is normally considered to be a phenomenon of very recent times, however, paradoxically there are references to what could be called financing in the old testament. To confuse the issue further financing small resource projects may not, and very often are not undertaken on a project financing basis. It is therefore quite apparent that one should be completely clear on:

Jan 1, 1982

By Higuchi K

For the mechanisation or automation of mining, recognition of the shape of mined cavities is basic information. A three dimensional shape measuring system, developed and tested, includes an ultrasonic range finder which is attached to the tip of a serial link manipulator. The range finder can be moved to any position and direction in the operational space of the manipulator. The position of a point on the surface of the object is obtained from the position of the range finder, the direction of the beam of the ultrasonic waves and the measuring distance of the range finder.To avoid collision between the sensor and the object, the manipulator is controlled to trace the surface of the object For the tracing control, another ultrasonic range finder is employed. The test results show that the developed system has high performance.

Jan 1, 1991

Before proceeding to the main portion of the above subject, a few remarks as to the general question of our mill slimes seem called for, and, with this in view, it is intended to briefly refer to the salient, points connected with their production, treatment and disposal at the mills.It is well known that, owing to the inticate mixture of the constituents of our sulphide ore, 'a very great deal of crushing and grinding is required to detach the particles of galena from the zinc blende and gangue of the ore, and it will be readily understood that, in this operation, a considerable amount of the material is converted into a slime which consists of minute, but ,(as can be see~ under a glass) well definied particles of all the constituents· 6f the ore arid combinations thereof, the relative proportions of which depend on the dual characteristics of hardness and abundance of the different constituents. An analysis of the slime shows the contents to be as follows :-Galena (PbS)Blende (Zn S)Pyrites (Fe Sll)Ferric Oxide (Fell Os)Ferrous Oxide (Fe 0) contained in garnetsOxide of Manganese (Mn 0) contained in rhodonite and garnets

Jan 1, 1903

By Hainsworth D, Winstanley G, Gurgenci H, Corke P

Past experience has shown that the automation of the dragline swing motion requires real time monitoring of the bucket position. A current project at the Centre for Mining Technology and Equipment (CMTE) is aiming to achieve this using machine vision. The hardware platform is a Datacube MaxVideo 200 system. The images are obtained by a fixed camera installed on the dragline boom. The field of view is large enough to include the bucket in all possible configurations. Standard chain coding and run-length coding algorithms are used to process the video image. The three-dimensional bucket position is calculated by combining the output of the machine vision system with the rope length data obtained from transducers installed on drag and hoist drums. This information is then fed into a control computer which takes corrective action to suppress bucket oscillations before they reach dangerous levels.

Jan 1, 1995

By Lysnar R, Horswill M

Since the introduction of the pocket calculator, electronic measuring equipment, lasers and computers, the mine surveyor's approach to his work has changed. Where he once used steel bands he now uses infra-red, visible light or radio waves. The reading and storing of angles is done automatically and he now has to be familiar with the facilities that a computer can offer, instead of plotting and calculating manually. This highly sophisticated equipment is continually being upgraded, modified and fine tuned. This paper will attempt to highlight some of the equipment at present in use by the surveying profession and research currently being conducted by the WA School of Mines. The various options in EDM will be considered including the latest unit capable of measuring distance without the benefit of a reflector, thus enabling the surveyor to co-ordinate points that were previously thought inaccessible. The School is currently working on changes to the GAK1 Gyro Theodolite which may improve results and enable the operator to have more control and confidence in his observations. Areas under consideration are improved lighting, binocular viewing and interfacing the instrument to a stopwatch. In the last few years the computer is being used not only for surface pickups and control but also for underground work. We will highlight the underground options in this area and the software available.

Jan 1, 1987

In contrast with mining in areas close to the main centres, mining in remote areas is characterised by comparatively high initial investment and relatively high running cost for the life of the mine. This is because of:the real cost of establishing and running the operation at a location distant from the necessary infrastructure; and the perceived risks priced into their costs by the multitude of suppliers involved in the project. Optimal co-operation between the mine and the supplier in developing the right rela tionship and the correct technical solution permit both cost elements to be reduced. This re duction may well mean the difference between success and failure. This paper examines the possibilities for optimising the contribution of the equipment supplier to the overall success of the process. Issues covered include the necessity to provide more than merely equipment fit for the purpose , but also the need to maximise the benefits of equipment ownership over the life of the mine. A simple method of determining the optimum timing for equipment replacement or rebuilding is proposed . Furthermore the maintenance contract (or performance agreement) is suggested as a means of leveraging the supplierÆs commitment to the mining operation. The specific examples are based on experience with mobile equipment but the methodology has relevance to other equipment and supplies.

Jan 1, 1998

By G De Tomi, R Sousa, A Lapworth

One of the current challenges for iron ore producers is the ability to respond to changes in ROM stockpile specifications in a quick and cost-efficient manner. The decision-making process to respond to such changes is normally associated with grade-control and short-term mine planning activities, from where new operating instructions to the mine are provided. Mines are under increasing pressure from changes in the industry, such as a scarcity of skilled staff; a higher turnover of skilled employees and tighter product specifications. The quality of operational activities easily suffers as a result of these pressures. The technology that supports operational activities is often poorly implemented, which results in systems being unsustainable and poorly understood by the organisation. All successful technology implementations rely on the people, processes and technologies involved being well understood. Because of the complex nature of mining, the processes that underpin mine planning, scheduling and operational control are often not well defined. This results in activities undertaken by individual departments being poorly integrated. Datamine has developed a set of tools and methods for decomposing; capturing and documenting processes and ensuring those are embodied in implemented solutions. A case study of such a solution is the GEROS planning system, which has been successfully implemented at CVRDÆs Southern Iron Ore System, in Minas Gerais, Brazil.

Jan 1, 2005

By J Koppe, J F. Costa

A fundamental error of sampling occurs when a sample is extracted from a larger mass of ore or lot. The act of sampling requires that all particles belonging to the lot have an equal chance of being extracted. This type of sampling is called unbiased sampling. The sampling equipment (herein referred to as the sampler) should be constructed with some additional mechanical characteristics to guarantee that the samples will be unbiased. Samplers, extracting increments from a continuous flow, such as a conveyor belt, collect aliquots at regular time intervals. These time intervals relate to the number of aliquots extracted from a given mass of lot, whilst passing through the continuous flow. The frequency of extractions will influence the precision or the error of the sample (integration error). Further, the ore variability influences the amount collected from the continuous flow. Normally, the sampling protocol utilised is designed for the extractions obtained from the conveyor belt, omitting any error committed during this operation, ie the error of extracting from the continuous flow. This study aims to analyse the error of sampling a continuous flow by using a variogram with added on auxiliary functions. Each different piece of material passing through the flow will exhibit a distinct temporal variogram, which should influence the frequency of the samples being extracted for each chosen sampling error. The methodology used is presented in the form of a case study from a coal processing plant.

Jan 1, 2005

An efficient stores organisation is essential for an efficient undertaking. Unless the stores organisation is able to meet the requirements of its requisitioners promptly and economically, the undertaking as a whole cannot function efficiently.Delays or errors in supply of material, or substitution due to lack of material availability from the stores are costly and must be eliminated. This then makes the objective of a store, to supply on demand at the cheapest possible price, those items of stock which it is organised to carry, also to procure as quickly as possible and at the lowest price those special items required which are not normally carried in stock. To do this it is necessary to set up a stores organisation consistent with the size and requirements of the undertaking. Stores organisations vary with the nature of the undertaking they are designed to serve. In the case of the Broken Hill Associated Smelters Pty. Ltd., an organisation has been established to meet the operating and maintenance requirements of the Port Pirie Works. These embrace the particularly wide range 0:1; activities associated with roasting" blast furnacing and refining the lead concentrates from the Broken Hill Mines in a continuous metallurgical process producing a variety of refined metals; also many associated activities including power production and engineering maintenance and construction.

Jan 1, 1951

By U Berg, T Neumann, Y Song

Eutrophication of water bodies is one of the most severe environmental problems worldwide. It is well known that the availability of phosphate, as the limiting nutrient, is crucial for increased primary production and eutrophication. Calcite exhibits positive surface charge in most natural waters and can therefore be used for phosphate immobilisation. In this study, sorption experiments were performed in order to test different calcite materials regarding their suitability for use in restoration of eutrophic lakes. These short-term experiments were performed under different hydrochemical conditions (pH, SICC, initial dissolved P concentration) and with varying calcite properties (specific surface area and amount) in order to predict the long-term stability of the Ca-P-bonds. Peculiar shapes of isotherms that could not be explained only by adsorption processes were detected in the individual experiments. Depending on the residual P-concentration in solution, the isotherms can be divided into three sections indicating different processes responsible for the P-fixation on calcite surfaces. Adsorption prevails in equilibrium with lowest residual P-concentrations. The inflection of the isotherm at moderate residual P-concentrations suggests that precipitation and transformation of a Ca-P compound becomes dominant. This is supported by characteristic Ca/P-ratios for different Ca-P-compounds (b-tri- calcium-phosphate, octa-calcium-phosphate). On the new surface, phosphate ions again are fixed by adsorption. The observed transformation of P-bonding is crucial for sustainable phosphate immobilisation on calcite surfaces. While pure adsorption processes are reversible, the development of a thermodynamically stable Ca-P-phase, like hydroxylapatite, will lead to a lasting immobilisation of phosphate.

Jan 1, 2008

When a thin film of volatile matter is deposited under vacuum on a polished coal surface, and the coated surface is examined microscopically in piano--polarized reflected light, colour changes are observed characteristic of the various macerals present. The colour changes appear to be mainly due to interference between light reflected at the upper surface of the film and at the film/coal interface. A variety of source materials for the volatile matter required have been tested, including powdered bituminous coal, coal tars, boron oxide, and certain resins.

Jan 1, 1969

By M Noppe, I Glacken

There are many critical nodes along the mine value chain, from orebody to mineral product, and inter-disciplinary input is required to analyse the variability and uncertainty at each node in order to identify and mitigate areas of risk. Mining differs from many other industries in that the variability in the product is dictated largely by the inherent nature of the input material (the orebody). The true characteristics, including the variability of the orebody, are never known exactly and are instead based on estimates derived from sample data. A further difference is that bottom-line gains are largely controlled by world commodity prices, which can vary with time, rather than by local supply and demand issues. Methods for identifying, reporting and responding to this inherently variable raw material are discussed. These include analytical and reporting methods, equipment and software, risk analysis and reality checks (eg reconciliation). Sampling results, mineral resource and ore reserve estimates and economic assumptions are a function of the variability of the orebody. Risk quantification should be expressed as a level of confidence, which takes into account the scale or period over which the risk is being assessed (life-of-mine, annual or shorter production periods) and should convey the likelihood, severity and consequence of occurrence of a given event. The future generation of mining specialists needs to understand the entire mine value chain to better manage risks and maximise mine dollar-value.

Jan 1, 2002

During the course of an investigation into the fundamental chemistry of the cyanide process, it became evident that the usual method of determining protective alkalinity was not completely satisfactory. T.he routine method for the determination of protective alkali by first removing free cyanide by the addition of silver nitrate, followed by titration of alkali with dilute acid using. phenolphthalein as indicator, can be shown to give correct results only when the alkali is a strong base. For other sUbstances, the alkali so determined is not the protective alkali. In view of the complications associated with the presence of zinc in cyanide solutions the discussion will be restricted in the first place to solutions free from zinc. Until the chemistry of simple cyanide solutions is placed on a quantitative basis it will be difficult to elucidate the behaviour of complex mill solutions.By the use of physico-chemical theory, it is possible to treat certain aspects of 'the chemistry of cyanide solutions in a manner which not only illustrates the important variables involved, but which also shows the need for care in interpretIng results obtained by conventional methods.In the following, comparatively simple systems are discussed; the principles established should be of use in interpreting the behaviour of more complex solutions. The methods described are not intended for routine work, but may be regarded as supplementary to the usual analysis carried out for the control of plant solutions, or as alternatives to be used when the latter do not appear to be satisfactory.

Jan 1, 1948

By J J. Cilliers, K Hadler

Froth structure and stability are known to play important roles in determining mineral flotation recovery and selectivity. However, measuring froth stability in a consistent manner remains a significant challenge, especially at an industrial scale. Following preliminary tests on a copper concentration plant, a quantitative dynamic stability measure is investigated in this study in order to extend the results over a wider range of conditions and on a different orebody. The technique is based on the Bikerman foam test and uses a non-overflowing froth column to quantify froth stability. Experiments were carried out using an automated version of the froth stability column under different operating conditions. Air flowrate was the key operating variable. Tests were reproduced on a single flotation cell of a Platinum Group Metals concentrator. The froth stability factor, , was measured for each operating condition, and compared with the air recovery in the cell, , which was measured using image analysis. The froth stability column results gave the same trends as image analysis. In particular the froth stability factor was found to be linearly related to the actual fraction of air overflowing the cell. The metallurgical results clearly indicated that changes in air flowrate result in variations in flotation performance that can be attributed to changes in froth stability. The results showed that high froth stability conditions occur at intermediate air flowrates, and result in improved flotation performance. It is found that the froth stability column is a simple, cost-effective and reliable method for quantifying froth stability, and for indicating changes in flotation performance.

Jan 1, 2005

By G C. Lukey, J S. J van Deventer

The disposal and subsequent encapsulation of mine tailings in a cost-effective and environmentally secure and responsible manner is one of the principal issues facing any modern mining project. A careful assessment of all options available for the capping and subsequent remediation of tailings is important because it can result in large capital, operating and closure cost-savings. For these reasons, the technology of geopolymerisation is receiving increasing attention for the stabilisation and solidification of waste materials produced from mining operations. The first part of the current study investigates the application of geopolymer technology to the capping of hypersaline mine tailings. It has been found that suitable geopolymeric materials which have satisfactory compressive strength, durability as well as low permeability, can be formed using between 60 - 75 per cent of mine tailings as the main ingredient. It has been established that geopolymeric materials have the ability to suppress dust generation and prevent salt precipitation on the surface of the mine tailings. The slurry-like consistency of geopolymers would promote efficient application procedures through established tailings disposal techniques. This is a possible close-out technique for hypersaline tailings storage facilities such as those commonly found in Western Australia, which meets both regulatory requirements and community expectations. The immobilisation of contaminant metals within geopolymers has been investigated in the second part of the present study. In particular, the leaching characteristics of Cu and Pb from geopolymeric matrices derived from different fly ash sources have been examined. Potential breakdown of each geopolymer containing metal contaminants due to the leaching of Si and Al from the geopolymeric matrix has also been investigated.

Jan 1, 2000

If an orebody has been drilled to achieve some level of regulatory compliance, then a number of associated geological databases will exist, representing 10 000 to 100 000 m plus of core intervals. The databases usually contain data about assays, lithology, mineralisation and geophysical attributes. They will also include location information such as collar positions and downhole surveys. Obviously this data is collected by geologists for, predominantly, geologists and mining engineers. However, from a process design viewpoint process engineers usually ignore the geology where possible and rely on a small number of metallurgical test samples. Typically these test samples are sourced from convenient and available cores or from a small number of specially drilled metallurgical holes. One of the worst instances known to the author was the design of a SAG mill using only two SAG specific test results (one for each of the major ore types) while, geologically, the orebody was defined by more than 30 000 m of drilling. This paper sets out a philosophy to maximise the use of the geological data, both for process design and in preparation for the commissioning phase of projects. Geological data is used in the identification of preferred locations for metallurgical test samples, for checking the metallurgical validity of the geological ore-type definitions, where necessary developing new ore-type definitions (geometallurgical domains) and developing mathematical relationships for the estimation of important metallurgical factors across the geological database. If the estimation of factors (for example ore competence) is considered reliable enough then there is also the possibility of feeding calculated data back into the block modelling process to allow the generation of metallurgically relevant outputs in the mine plans.

Jan 1, 2007