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By D A. Williams, J C. J Boshoff

The properties of tailings that emanate from laterite nickel processing plants are significantly different to most other mine tailings. They typically comprise a mixture of fine materials that are made up of altered clays, chemical residues and salts. Neutralisation processes that are undertaken prior to tailings discharge result in a high proportion of gypsum in the tailings. The salinity of the pore fluid is commonly higher than 140 g/L of salts, dominated by magnesium sulfate. Hydraulically-placed tailings that undergo solar evaporation typically reach dry densities of less than 1 t/m3 of insoluble solids. In situ water contents after many months of drying may be as high as 80 per cent, and peak undrained shear strengths are unlikely to be greater than 20 kPa.This type of material is not conducive to upstream raising, from both a practicality and overall slope stability perspective. Even at rates of rise of less than 1 m/a, it is difficult to effect upstream raising on unaltered laterite nickel tailings. However, the authors have successfully designed and implemented upstream-raised laterite nickel tailings storage facilities. The upstream raises have been formed from both imported natural materials and air-dried and compacted tailings borrowed from the tailings beaches.Drying and associated strength gain has been achieved through various means of mechanical intervention, repeatedly exposing a zone of tailings to the atmosphere for evaporation. Field trials have been undertaken to optimise the approach, and the findings from the trials have been implemented in practice to allow stable upstream raises to be constructed. The cost savings and reduced environmental impact compared to high-volume downstream raises have been significant.CITATION:Williams, D A and Boshoff, J C J, 2015. Upstream raising of laterite nickel tailings storage facilities, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 271–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By K Grohs, A Satriawan, S R. Pearce

Martabe gold and silver mine is operated by PT Agincourt Resources (PTAR) and is situated in northern Sumatra and comprises several deposits in steep terrain, and in a tropical climate, that are required to be developed in the optimal sequence for the best possible Net Present Value (NPV) return on the project. In addition, the waste rock from excavations and tailings from processing is a by-product to be scheduled and used for a number of purposes identified as part of life-of-mine planning. These uses include construction of the current integrated tailings storage facility (TSF) as well as future engineering construction and waste disposal projects which includes plans for a program of in-pit backfilling. These plans need to be aligned to ensure the waste rock and tailings can be contained relative to the production rate. Given that the site will have multiple open pit voids upon cessation of mining activities opportunities for integration of in-pit disposal of mine waste have now been assessed with technical studies to review the practicality of the approach with respect to operational challenges and conformance with closure planning requirements. This includes assessment of disposal of waste rock, tailings (including consideration of filtered tailings) and co-disposal of waste rock and filtered tailings.

Aug 2, 2023

By R Barritt, P Scott

Across the globe, it is a common scenario that tailings storage facilities (TSFs) are being decommissioned; however, their subsequent impact on the local environment and landscape can often be overlooked during the mine planning process. In addition, the requirement of a cover system for a facilities closure may not be a priority until the latter stages of the mine/mill operation when potential cover materials may have been utilised elsewhere or, worse, buried. Developing a conceptual design and closure plan for a TSF early in a mining venture is fundamental to its success once operations have ceased. If a cover system is a planned component for rehabilitation of a TSF, it is vital that its design is appropriate to the facility and any local site constraints, such as climate and cover system material availability. It is also strongly recommended that various cover system options are physically trialled at the site by using performance-monitoring instrumentation. Through this process, an informed decision can be made regarding the most appropriate cover system design to meet any regulatory and stakeholder closure objectives and criteria specific to the site in question; however, in order for the cover system’s performance to be determined through on-site trials, it is essential that an appropriate instrumentation design is utilised. Often, little attention is paid to the data that is being obtained, and its importance may only become apparent after several years of monitoring at an expense to the venture. This should not be the case. Many sites have used an appropriate initial planning stage to understand what is required for the successful closure of a TSF, how it can be achieved and how monitoring data can be utilised to prove, or otherwise, that a cover system design will be a success.CITATION:Barritt, R and Scott, P, 2015. Cover system performance monitoring for tailings – are we doing it correctly?, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 283–288 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

The aspect ratio (mill diameter/mill length) of autogenous and semi autogenous mills varies widely and can be as high as three or as low as 0.5. The literature on the subject of what effect aspect ratio has on grinding mill performance or energy efficiency is almost non-existent. However, at the design stage of many grinding circuits the subject is often vigorously debated amongst metallurgists. In this paper the performance characteristics of mills with different aspect ratios are examined to determine whether process performance characteristics are a function of aspect ratio and whether high aspect ratio mills are any more or less energy efficient than low aspect ratio units. Data from both pilot and full-scale mills are used for this purpose in open and closed circuit configurations.

Jan 1, 2007

By S J. Henderson

Over much of Australia, rainfall is highly seasonal and storm-driven. Consequently, operational mines often need extensive earthworks – drains, dams and levees – for protection during the occasional large floods and for water storage against the dry times; however, it has not been appreciated that many of these earthworks will need to function after mining has finished, sometimes, beyond a normal design life for engineered structures.While a mine is operating, standards for design and maintenance are dictated by regulation and risk assessment. For dams and levees – regulated structures – the standards imposed mainly relate to life-of-mine. The levels of risk and maintenance accepted by the mine operator may not be acceptable to another landholder in perpetuity. However, the Environmental Authority cannot be surrendered unless the landholder has accepted responsibility for any unrehabilitated regulated structures (Department of Environment and Heritage Protection (DEHP), 2016).In order for a future landholder to be willing to take responsibility for a dam or levee, the structure should be of value to the business of the property. In addition, its management needs must be consistent with that business; for example, it should be maintainable using skills, equipment and materials normally available to the business.CITATION:Henderson, S J, 2016. Earthworks or landforms? Designing for lease surrender, in Proceedings Life-of-Mine 2016 Conference , pp 151–153 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By Borsaru M, Wylie AW

A neutron irradiation technique has been developed which is suitable for the determinat- ion of the iron and aluminium content of iron ore fines (-6 mm particle size) on a moving rubber conveyor belt. The determination of iron entails measure- ment with a NaI(Tl) gamma ray detector of the characteristic prompt gamma rays (7.64 MeV) due to thermal neutron capture in iron, while the determination of aluminium is based on thermal neutron activation analysis. For the latter a second detector must be placed down- stream to monitor the 1.78 MeV gamma radiation emitted after activation of aluminium. Although conveyor speed has no effect on the Fe measurement, it has an adverse influence on the aluminium signal, and the belt speed should not exceed 0.1 m/s if good accuracy is required. Static trials on a 460 mm rubber conveyor belt with constant ore geometry indicate that for iron an accuracy of ¦ 1.2% Fe (2a) can be achieved for crushed run-of-mine ore at

Jan 1, 1978

By Y V. Haarlem, P Coghill, N G. Cutmore, M Millen, I Carter

Due to the low concentration of gold, ore sorting for gold has always required measuring indirect properties, such as density or colour, to allow separation on a rock by rock basis. This only works on an ad hoc, by deposit basis and is likely to be least reliable where it is most required in low grade ores. One candidate technique, Gamma Activation Analysis (GAA) has been demonstrated to directly measure gold extremely accurately in powder samples of around 500gm and is used in the Chrysos PhotonAssay assay system. This method uses a linear accelerator (linac) to generate the X-ray radiation that activates the ore at low levels to emit a characteristic gold gamma ray that is then measured by a radiation detector. CSIRO is adapting this measurement technique to application on a belt at up to 800tph to measure pods of ore. The principal differences between measuring samples and an on-line measurement of pods are the requirement to measure coarse ore (<50mm), to measure a larger volume of ore as uniformly as possible, and to have an open-ended geometry with adequate shielding of the linac radiation source. These issues have all been addressed with measurements of coarse ore reported down to around 1ppm in sub-optimal test conditions. They have been demonstrated for <75mm particles with detectors capable of measuring a large volume geometry continuously. These are projected to allow measurements down to 0.3ppm in more optimum conditions for a 10 second measurement time period where the U/Th content of the ore is less than ~10ppm. Extensive Monte Carlo modelling has demonstrated that adequate shielding can be provided in relatively simple geometries with only 1 right angle transfer in the material handling. Steady progress is being made to reach the technical position required to trial an ore sorting system.

Nov 10, 2020

Better quality at lower cost is today&apos;s formula for remaining competitive in a world market. For an integrated steel company, high quality low cost steel production must originate before the blast furnace. In 1979, when U.S. Steel initiated a Quality Management Program throughout its steelmaking operations, efforts began at the coal, ore and flux mines. The objective was to improve the quality and reduce the variability of the critical parameters for steelmaking raw materials, to get the blast furnaces, and subsequently the melt shops, under optimum control. The general details of U.S. Steel&apos;s Quality Management Program are discussed and how it was used to promote the desired improvements in steelmaking raw materials. Some of the outstanding results obtained by the cooperative efforts between the mines and the steel plants are reported. The lessons learned by U.S. Steel were through upgrading existing operations and facilities. These principles should now be applied to new projects and the benefits of good quality management should commence from the time new projects are Commissioned.

Jan 1, 1986

The history and milestones in the evolution of support systems utilised in the mass-mined chrysotile mines of Shabanie and King are discussed in detail. The use of block caving, false footwall or sublevel caving mining methods brings with it some major support problems, which are exacerbated, in our low rock strength mining environments. The paper discusses the various support elements and systems that have been used successfully or otherwise in these operations. Some predictions for the future of rock reinforcing in our ground conditions are highlighted, in relation to geomechanics, levels of mechanisation and production risk analysis.

Jan 1, 2000

As an indication of the overall quality for the three periods the expected run of mine ashes are given. Operating Period R.O.M. Quality Years 1 - 4 22.0% Ash (db) Years 5 - 14 18.8% Ash (db) Years 15 - 20 17.3% Ash (db) The size distribution of the coal was found to be generally as predicted in the 1980 study. However the ash, particularly in the smaller fractions, was found to be higher due to the previously mentioned friable nature of contaminant material. Following evaluation of this additional information, the proposed washery design was reconsidered. Three basic process schemes were examined. 1. A jig with two-stage heavy medium cyclones and spirals for treatment of three different size ranges. 2. A heavy medium vessel, two-stage heavy medium cyclones and spirals for the different size fractions. 3. A jig for initial treatment of the total feed (that is all sizes) with single-stage heavy medium cyclones and spirals for rewashing of the intermediate and smaller size Fractions.

Jan 1, 1986

This paper provides an overview of current and future mine developments in the major island nations Indonesia, Papua New Guinea (PNG), New Zealand, and Fiji, and the French territory of New Caledonia. Many of the other 11 small island nations in the region, such as Vanuatu, Pulau and the Solomons have been the subject of considerable exploration orientated towards gold in the past few years but without any deposit found with confirmed economic viability.

Jan 1, 1990

By Lawrence PR, Hoffman W

The dissolution of gold from various ore-bodies is discussed in terms of extraction rates and reagent consumptions during leaching. Gold dissolves slowly in cyanide but reagent consumptions are usually satisfactory. In almost all cases where excessive cyanide consumptions occur, similar high consumptions result with other lixiviants. Recovery of gold from cyanide solution is well established and comparatively simple technology.Gold dissolution in thiourea is faster than cyanide but significant consumptions of thiourea, due to both adsorption and oxidation, occur. Gold recovery from thiourea solutions is likely to be more difficult than from cyanide.Chlorination of gold is very fast in acidic conditions but excessive consumption of chlorine occurs for ores containing greater than 0.5% S. Reprecipitation of gold and handling of acidic chlorine solutions are both significant problems. The mechanism of gold reduction onto activated carbon creates difficulties in the carbon in pulp process for recovery of gold but means a simplification in the production of bullion from loaded carbon.

Jan 1, 1984

By Fejes G

An integral part of the Brisbane Suburban Railway Electrification involved the relining, refurbishment and track lowering in the Roma Street, Brunswick Street and Gloucester Street double track tunnels. The design and the construction procedures had to satisfy the Queensland Railways electrification clearance and track standards and the requirements of maintaining track services through the tunnels during work. Refurbishing of the tunnel linings was carried out to extend the life of the tunnels.

Jan 1, 1981

A case is made for broader commercial education of executive and operational managers in Australian mining companies. The competitive advantages and disadvantages of Australian miners are examined. Areas of opportunity are identified which could be exploited by broader applications of proven techniques to commercial management of mining companies.

Jan 1, 1985

HISTORY Up until the late 1880&apos;s the mining industry acquired a considerable proportion of its capital needs from domestic sources. Exchanges were established wherever major new fields were opened and Ballarat, Bendigo, Charters Towers, Coolgardie, Kalgoorlie and Silverton all boasted active trading in mining shares. For much of the first half of this century there was only modest developments in the mining industry and its capital require- ments were correspondingly lower. RECENT EXPERIENCE The new mines of the sixties were, in many cases, characterised by their remote situation and their output of bulk commodities such as iron ore., coal and bauxite. Infra- structure costs were particularly high and the level of capital expenditure was of previously unheard of proportions.

Jan 1, 1975

Most mining dredges are adapted from canal/harbour dredges. Their automation and control systems are generally not designed for integrated mining operations. Consequently they have a number of limitations. This paper describes a new dredge control concept which paves the way for improved efficiency and increased production.

Jan 1, 2001

By R O. Laidlaw, J L. Mauk

The Coeur d&apos;Alene mining district in northern Idaho, USA is the second largest producer of silver in the world. Mesothermal silver-lead-zinc veins occur in the metasedimentary rocks of the Belt Supergroup with five main types of associated hydrothermal alteration: 1) feldspar destruction, 2) hydrothermal bleaching, 3) carbonatisation, 4) sulfidation, and 5) silicification. Hydrothermal bleaching is characterised by hematite destruction with associated siderite and quartz veins and veinlets, coarse euhedral pyrite and magnetite. Bleached zones envelop both mineralised and barren veins and extend for metres to tens of metres into the wall rocks. Carbonatisation consists of addition of siderite, which occurs as veins, veinlets, stockwork, irregular blebs or spots, and coarsely disseminated grains, depending on the relative distance from the main vein structure. Siderite envelops nearly all mineralised veins, relates to all other alteration types and extends from several metres to tens of metres into the wall rocks. Pyrite and galena alteration dominate sulfidation and are associated with some mineralised veins. Pyrite alteration strongly correlates with siderite alteration and exists in three main forms: a) very fine-grained pyrite flooding, which can extend for metres to tens of metres into wall rocks; b) coarse-grained, euhedral pyrite, which is sporadic and associated with the redox boundary in hydrothermally bleached zones; and c) small isolated zones (6 - 15 cm) of medium-grained, subhedral to euhedral pyrite associated with pervasive siderite alteration. Where present, disseminated galena extends for metres to tens of metres into the wall rocks. Silicification is characterised by veins, veinlets, stringers, irregular patches and variable hardness in siltites and commonly appears in association with hydrothermal bleaching and siderite alteration. Although related to mineralisation, silicification is sporadic and in most places a clear envelope around mineralised veins cannot be identified.

Jan 1, 2001

By O Omidi, P D. Katsabanis

The effect of delay time on fragmentation has been discussed for a long period but rarely in a satisfactory and unbiased way. Despite the efforts of many researchers, delay selection for fragmentation improvement or optimisation remains a controversial issue. Large-scale tests have been plagued with scarcity and scatter of observations, while small-scale tests have been associated with boundary effects and energy losses. Theoretical work is often used to produce explanations for available measurements or tries to simplify wave propagation and wave interaction to guide observation and practical work. The present work analyses results obtained from a relatively large number of small-scale experiments in blocks made of grout, and re-analyses results of previous experiments, to conclude on the effect of delay on fragmentation. It is shown that the main contribution of the delay is found in the fragmentation of the larger fragments of the blast, while the small fractions show almost no effect. Samples, where copper liners were used to inhibit penetration of detonation products in the rock mass, showed effect of delay only when short times were used and steady but poor fragmentation when long delays were used. Based on small-scale experiments, it appears that the fragmentation is optimised when a hole fires prior to the radial cracks, produced by the previous hole, reach the free face of the blast. Gas penetration may result in the development of few more fractures that affect the fragmentation of the largest particles of the blast.CITATION:Katsabanis, P D and Omidi, O, 2015. The effect of delay time on fragmentation distribution through small- and medium-scale testing and analysis, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 715–720 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Walsh V

The Australian economy has been adversely affected by the hesitation in developing countries to commit to the construction of .new coal-fired power stations. World coal trade which was expected to grow at an appreciable rate has stagnated, world export coal prices have plummetted, and facilities in place in Australia for the production and export of coal are being underutilized. While in some countries this hesitation has been caused by a reduction in electricity load growth, another cause has been the unduly long lead-time imposed on developing countries by the conventional "Banker&apos;s Approach" to the planning and initiation of commitments to finance and construct coal-fired power plants. In some countries electricity growth has been met by increased usage of indigenous energy resources, even though this involves costs in excess of imported coal-fired power generation. The avoidance of foreign exchange commitments in these cases can however be desirable. In many other developing countries however, fuel oil continues to be used for power generation at a cost in foreign exchange of up to 50% above the total cost of coal fuel plus capital to construct a new coal-fired power station. The conventional "Bankers Approach" to new power station planning imposes the need for successive feasibility studies to satisfy the normal processes of international development lending agencies. No feasibility study can however, show how keen vendor countries may be to win major power plant contracts; and no feasibility study can determine whether the power station eventually procured will be one of the more reliable, at better than 80% availability, or one of the more unreliable at worse than 60% Availability.

Jan 1, 1987

This paper discusses considerations to be made for the selection of rock tunnelling machines, as opposed to drilling and blasting. A systematic approach is presented in terms of utilizing data frcm site investigations to accurately forecast machine performance for estimating and planning purposes and to help minimise associated risks. Useful rock index properties are identified, and correlations for predicting advance rates for roadheader and full face machines are presented together with a simple method of characteristing rock mass conditions for estimating machine utilization and the savings to be gained in support costs. Finally considerations for tunnelling in adverse ground, for advance probing and for large sized tunnels are outlined.

Jan 1, 1987