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By Koppe J. C, Dimitrakopoulos R, Costa J. F

Grade control and the delineation of ore/waste in open pit operations is traditionally based on the comparison of estimated grades with an economic cut-off. This paper deals with an alternative approach to grade control based on estimating gra

Jan 1, 1998

The results of the washing of coal are often presented by using Partition Curves. By analogy, it is possible to express the results of screening by using similar partition curves. As in the coal washing processes, this method determines the accuracy of screening and is also suitable for different separations depending on the difference in size distribu- tion. This method compares the effectiveness of two screening operations and forecasts the performances.

Jan 1, 1984

The Queensland Magnesia Project is based on a unique cryptocrystalline nodular magnesite orebody which required an innovative approach to process design in order to economically exploit the characteristics of the ore and produce a marketable range of high quality refractory magnesias for a declining world market. High quality natural refractory magnesia must have an MgO content in excess of 95 per cent with a very strictly controlled content and ratio of residual impurities such as calcium, silica and iron. The natural products compete with magnesias derived by chemical extraction from sea water or brines which exhibit very high purity but often lack other characteristics which are of value to refractory brick makers. Since start up in late-1991 QMAG has achieved a remarkable market penetration for both its deadburned and electrofused products with sales for the 1993/94 financial year representing 92 per cent of deadburned capacity and 138 per cent of original electrofused capacity respectively, all at a time when the world steel industry has been in recession.

Jan 1, 1995

The Knelson Concentrator is a centrifugal gold concentrator developed in Canada, which utilises the combination of high gravitational ("G") forces and a unique fluidising action to efficiently recover free gold particles from minus 6 mm to fine micron gold in both alluvial and hardrock applications.Operating parameters including water requirements, fluidising pressures and feed rates are given, as well as an indication of their various effects on gold recovery.Results include a Colorado School of Mines Research Institute (CSMRI) report comparing the Knelson concentrator with various other gravity concentrators.

Jan 1, 1984

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 C F. Nichol, L Smith, R D. Beckie

A better understanding of the hydrogeology within mine waste rock and cover systems is essential for the quantification, prediction and prevention of metals loading to the environment surrounding waste rock piles. The effect of surface condition on the internal flow mechanisms within an intermediate-scale constructed waste rock pile is being investigated at the Cluff Lake Mine, Saskatchewan. Changes in the water balance, the outflow distribution and water residence time have been observed in the waste rock pile following successive modifications of the surface condition. The three year old, run of mine, free-dumped surface was ripped to a depth of 30 cm to 40 cm, and levelled in October of 2001. In August 2002, a 10 cm to 15 cm cover of compacted waste rock was placed on the pile. Outflow, precipitation and run-off data collected during natural and artificial rainfall events have been used to quantify the maximum infiltration rate, and the spatial pattern of discharge and cumulative volume of water that infiltrated into the waste rock under each surface condition. Infiltration data together with the outflow data provide a basis to address the residence time of water within waste rock and the dominant flow mechanisms for different surface conditions. With a free dump surface spatially distinct wetting fronts are observed at the base of the pile that vary in flow rate by an order of magnitude (measured at a 2 m by 2 m scale) and in time by up to a week. Following ripping and levelling, similar cumulative outflows were observed, but the magnitude and arrival time of wetting fronts changed across the pile. A decrease in outflow volume, a decrease in infiltration volume, a two-fold increase in the response time of wetting fronts and a more spatially uniform distribution was observed following placement of the compacted surface layer. Based on preliminary data, the internal structure appears to be the dominant factor controlling outflow variability.

Jan 1, 2003

By K Uchino, M Inoue

Self-potential anomalies are generated by fluid pressure gradient, by temperature gradient or by chemical gradient. On the basis of this principle, a new technique is proposed to locate the fire source of spontaneous combustion of coal by the self-potential method. In order to investigate whether this method can be applied to locate the spontaneous combustion of coal in practice, surveys of self-potential distributions were undertaken in a coal waste pile undergoing spontaneous combustion. The results showed that there is a negative centre of the electrical potential distribution in the measurement area. The potential in this centre is about 140 mV lower than that in the surrounding area. Moreover, the negative centre of electrical potential distribution almost overlaps with the high temperature zone. Therefore, it is concluded that it is possible to locate the heat source by the measurement of self-potential distribution.

Jan 1, 2005

By Coxhead B. A, Brandt B. A

The geological exploration and evaluation of coal reserves involves the appraisal of very large amounts of data. Computers afford an ideal means of handling and manipulating the data, thereby avoiding the laborious and expensive method of manually compiling the logs in full descriptive language. The Minad system of computer storage and retrieval of geological and analytical data is particularly suited to the description of cores and cuttings from exploration drill-holes. The encoded data is arranged in a 120-column computer output sheet format; descriptive geological information in a 54-column geolog and analytical information in a 64-column assaylog. The acquired data is quantitative, uniform and relatively complete and can be selectively retrieved for processing by a wide range of specialized computer programs developed for the coal mining industry. Visual retrieval of data for manual processing is facilitated by the use of simple codes and logical word abbreviations.

Jan 1, 1977

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

Hamersley Iron Pty. Limited has maintained an interest in the screening of iron ore fines (nominally -6 mm). However, no dry screening process had successfully demonstrated acceptable separating efficiencies at high tonnage rates, low operating costs, and mechanical reliability when screening iron ore fines (containing up to 6% free moisture) at sizes of around 1 to 2 mm. A new type of vibrating inclined screen has recently been developed which is claimed to have a non-blinding screening surface. It was decided to test a pilot scale unit in an existing pilot plant located at Hamersley's facilities at Dampier, Western Australia. The appropriate operating parameters such as vibration speed and feed rate were determined using one fine ore type. Mats with different aperture sizes, and different feed moisture contents were also tested. Trials were then conducted on various fine ore types to indicate the effect of different size distributions on separating efficiencies. The effects of feed moisture content were determined with these ore types, and a blend of lump (nominally -30+6 mm) and fines was tested to compare the screen's performance with that of the bottom deck of the minesite product Screens.

Jan 1, 1991

By Biswas AK, Hayes P

During the reduction of iron oxide pellets in the blast furnace it has been found that catastrophic swelling (up to 300% volume increase) can occur. Although the burden preparation conditions can be designed to avoid this phenomenon the exact reason and mechanism of the swelling has yet to be clearly identified. Swelling of the burden is undesirable since it reduces the interparticulate voidage in the blast furnace thus reducing gas flow through the stack resulting in low production rates of iron. The present study differs significantly from previous experiments in that reduction is carried out on single crystals of wustite thus the problems of control of gas composition and specimen preparation are minimised. The microstructures formed on reduction have been examined by optical and scanning microscopy. Pure wustite and wustite doped with various levels of CaO have been examined after reduction in controlled CO-CO 2 gas mixtures at 968¦C. The catastrophic swelling on reduction coincides with the formation of an unusually open iron structure in which the iron appears as whiskers or needles as previously reported. The spacing and thickness of the needles are shown to vary with impurity content and gas composition. Metallographic examination has shown in addition, however, that the whiskers do not necessarily constitute the only product form of the iron produced and in CaO containing wustites with less than - 2% CaO there is a transition from needle growth to porous growth of iron. Thus the % swelling of the oxide particles is dependent on the initial size of the oxide grains. Samples of FeO - 10% CaO exhibited a previously unreported product inorphology associated with the nucleation of 2CaO.Fe203.

Jan 1, 1980

After reviewing the many excellent papers being delivered here, it is apparent that we are all concerned with the same general subjects of commodity agreements, international cartels, and anti-trust problems as well as the impact of governments on resource management and minerals pricing. Accordingly, as a relative newcomer to the mining business, I feel that my most meaningful contribution can be made by taking a more philosophical look at the future of our system of democratic capitalism. Unfortunately, governments the world over seem intent on jeopardizing the high standards of living resulting from the Industrial Revolution and furthered by the emergence of its by-product, capitalism. This tendency is particularly germane to the basic natural resource field, since government regulations, controls, and intervention in mining far exceed even the constraints normally imposed on hard-pressed consumer-oriented businesses. Increasingly, many governments seem to feel that natural resources no longer belong to private individuals but rather are the property of the state to be developed in a regulated manner and usually in a way directly contrary to the functioning of the free market system.

Jan 1, 1978

Stressed steel cables, similar to those used in pre-stressed concrete, have been used for rock mass reinforcement, in civil engineering, for many years. This type of reinforcement has been attempted for open pit wall support, on several occasions, but has never gained wide acceptance as a practical approach because of high cost and complexity of installation in a mining environment. On the other hand, untensioned, fully grouted cable dowels (cable bolts) have gained wide acceptance for ground support in underground mining and it is perhaps surprising that this technique has not been used to a greater degree in open pit mining. The first systematic application of this technique in Australia was at the Mary Kathleen uranium mine in 1976, where it was spectacularly successful in maintaining steep stable walls in a jointed rock mass with unfavourably dipping structures. Cable bolting, and other techniques, are now being used to an increasing degree for wall support in both small and large open pits, for two basic applications: 1. stabilisation of potentially unstable sections of a wall, or 2. to allow steeper walls and reduce waste stripping volumes. In virtually every situation, wall rein- forcement has significant economic as well as technical advantages. The paper describes the development of the techniques, the mechanisms of wall support, the methods used, and discusses several case histories of its application to Australian open pit mines.

Jan 1, 1986

By G Partington

A regional scale prospectivity model was developed for Papua New Guinea (PNG) to identify areas of porphyry Cu-Au mineralisation. Weights of evidence modeling techniques were used to determine spatial correlations between porphyry Cu-Au mines and predictive maps created from available spatial data. These predictive maps were then combined into a final prospectivity map. Despite limited regional scale data the model has successfully identified areas of known porphyry mineralisation as prospective and has also identified areas where new mineralised systems may be discovered with further exploration. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Over the last few years several important developments have taken place in the Electro- lyte Purification Plant at Copper Refineries Pty. Ltd. A fully automated system for the continuous removal of arsenic has been develop- ed. A submerged combustion process for the removal of nickel has been developed to a stage where patent coverage has been obtained in most of the copper producing countries. A plant has recently been commissioned for the production of Tetra Cupric Arsenate, which it is hoped will find a ready market in the timber preservation industry.

Jan 1, 1974

Don Hausen was a pioneer in the field of quantitative mineralogy. Methodology that he developed at Newmont almost 40 years ago is still employed today, only the technology has advanced. Petrographic methods were stressed with an emphasis on alteration, mineralisation and paragenesis. Methodologies employed by Don on the Carlin deposit were applied to developing the Carlin Trend by helping to work out lithology and structure, which ultimately led to the discovery of deep high-grade deposits. Quantitative methods used by Don on San Manuel, Copper Creek and Superior, Arizona were applied to the development of the Batu Hijau Deposit in Indonesia. Advancements in technology since DonÆs time have made the mineralogist much more efficient. Manual measurement of peak heights off of strip charts for semiquantitative XRD has been replaced by software that does Rietveld refinement and whole pattern fitting. Hand contouring of XRD data has been replaced by digitised data incorporated into geologic models. Optical point counting, which would take a dayÆs work to process 1000 points, has been replaced by automated SEM methods where 20 000 points are possible in an hour. The use of the optical microscope remains relatively unchanged, and still remains as Don emphasised the æeyesÆ of mineral exploration. However, the information can be relayed much more quickly with digital image capture and electronic data transfer. Don insisted on becoming involved in projects at the grassroots level and supporting the project through mine closure. This made the mineralogist a liaison between exploration geologists, mine geologists, metallurgists and mine engineers. The methodology that Don helped develop continues to provide invaluable support to Newmont geologists and metallurgists worldwide today.

Jan 1, 2008

The correct design and effective operating strategies of metallurgical plants require a constant analysis of data gathered for process control, or for due accountability. Conventional, oldfashion statistical tools often fall short of helping management, either because they are too complicated and ambiguous, or because they fail to address structural problems leading to causes of setbacks. This paper focuses on three statistical tools known for their practicality and the in-depth perspective they offer in attempts to retrieve important information from existing data. These tools also provide a better appreciation of the importance of carefully selected data quality objectives. Chronological data are meticulously gathered and stored at considerable expense: They have value, and it is the duty of management to take full advantage of them. These three selected tools are the variogram and its auxiliary functions, the moving average and its auxiliary functions, and the relative difference plot. This paper offers solutions, and a reference for managers to optimise metallurgical plants.

Jan 1, 2002

By Mozley R

Contaminated sediments are a multinational problem. A crucial factor in solving an environmental problem is knowledge of, not only the amounts of polluted soil, the contaminants involved and their concentration, but also the historical background of the problem. Processing polluted soil is a tailor made activity based on rational decisions resulting from a detailed treatability study. Lack of information about characteristic properties of a specific sludge/pollution combination is the main obstacle in the route from first ascertaining that a particular harbour subsoil is polluted, to final identification of the full scale treatment plant. In the first instance, information must be generated regarding the distribution of pollutants in relation to the distribution of the original geophysical components. Based on this information rational decisions can be made on separation at a particular cutpoint and what sequential techniques should be involved for a certain fraction. For this purpose a `fingerprint method' is presented especially developed for investigation of polluted soil and sediments. The heart of the fingerprint method is a series of sequential hydrocyclone separations, by which a series of products is generated. The objective of the fingerprint method is to select an optimised treatment procedure in which the pollutants are concentrated in as small a volume of material as possible, leaving the bulk of the material clean. The pollutants can then readily be destroyed or isolated from the environment. The philosophy and advantages of the fingerprint method are demonstrated for a harbour sludge containing heavy metals as main pollutants. Hydrocyclone separation combined with flotation of both the coarse and fine fraction resulted in reusable and dischargeable products. Flotation of the fraction of fines was carried out by means of an experimental flotation cyclone enabling the selective recovery of mineral particles with diameters less than 10 microns. The overall conclusion is that design and engineering of treatment flow schemes for polluted dredged materials is a tailor made activity based on rational decisions resulting from the fingerprint information.

Jan 1, 1993

By J A. Brown

Osborne Mine commenced hydraulic filling of three stopes in April 1999. Two of these stopes experienced barricade failures in July 1999 and January 2000. As a result, a review of hydraulic filling was commissioned in April 2000. The design of a trial of revised specifications and practices is in the final stages, prior to the trial commencing in mid-2002.

Jan 1, 2002

By J Rapkoch, M Cerna

As long as the tendency of Chilean copper ores continues to feature high levels of impurities, the smelters will tend to produce high-impurity mattes. The most notable impurities include As, Sb, Pb and Zn. Producing high-quality copper with such materials is a major challenge to metallurgical engineers and operators. More investigations into process optimisations and/or alternatives are needed, using both theoretical knowledge and operational skill. Converting of matte in Chile depends on the matte grade using established technologies. Mattes up to 66 per cent Cu, such as those from Outokumpu Flash furnaces, are converted in two stages, while typical Teniente Converter mattes, ranging from 70 - 74 per cent Cu are converted in one blow, directly to copper. In this paper thermodynamic data are used to evaluate possible variations in the use of traditional technologies applied to smelt copper concentrates with high impurity levels. The results of this analysis help to predict the impurity distributions between matte-slag-gas during the slag blow, and between copper-slag-gas during the copper blow. For converting high-impurity white metal, the effectiveness of volatilisation in the slag blow is analysed. In the copper blow, the type and the amount of flux (SiO2, CaO and others) are altered with the aim of optimising impurity distribution to the slag and gas.

Jan 1, 2005