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By A P. Brown

Comparison of legal permits required for mining (as opposed to prospecting or exploration) inNew Zealand, under the Mining Act 1971 and the Resource Management Act/Crown Minerals Act 1991. Mining generally receives the same treatment as any other industrial or commercial activity.

Jan 1, 1995

Jan 1, 2004

By D M. Hunter, S M. Iveson, K P. Galvin

For low density materials such as coal, density-based fractionation of particles via the sink-float method is relatively simple due to the availability of liquids of suitable density; however, for high density minerals, suitable heavy liquids are less available and those that are available are expensive and pose significant hazards. At best, sink-float separation can be performed up to densities of 4400 kg/m3 with the use of Clerici’s solution at elevated temperatures. Hence the direct measurement of grade-recovery and density-partition curves is problematic. Therefore, in most cases, beneficiation plants must rely on methods such as QEMSCAN, density tracer particles or very limited information to guide them in the design and optimisation of their plants.This paper describes a density-fractionation method utilising laminar flow through a system of parallel inclined channels to generate a series of overflow fractions at different flow velocities. Here the particles are subject to precise hydrodynamic forces with minimal dispersion or mixing. The size distribution of each overflow fraction at a given flow velocity is obtained using a laser particle size analyser, and combined with a laminar flow model to deduce the corresponding density distribution. The paper describes the application of the method to measure the separation achieved using a REFLUX Classifier to obtain the corresponding feed, product and reject ‘washability curves’, and in turn the full partition surface. Approaches used to corroborate the findings are discussed.CITATION:Hunter, D M, Iveson, S M and Galvin, K P, 2017. A batch elutriation technique for the density-based fractionation of iron ore, in Proceedings Iron Ore 2017, pp 195–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Study on Mineral Processing Technology for a Refractory Iron Ore

Sep 13, 2010

By A J. Cornah

Critical decisions in iron ore project evaluation and production are based on global and local spatial estimates of primary mineral deposit properties (such as in situ geochemical grades) and geometallurgical responses (such as screened, washed or concentrated product yields and grades), which are derived from limited sample data. These spatial estimates are typically made using classical geostatistical techniques, which fundamentally assume that the attributes of interest behave additively. This assumption is generally appropriate for æprimaryÆ variables but æresponseÆ variables may behave non-additively and therefore their direct linear estimates may be biased.In this paper an existing additivity testing mechanism is used to quantify the bias resulting from direct linear estimation of a non-additive iron ore attribute. Data from a magnetite project are used to determine the circumstances under which such biases may be of material impact. The implications for iron ore resource estimation, geometallurgical modelling and grade control are outlined and discussed.CITATION:Cornah, A J, 2013. Assessment of the impact of non-additivity in the estimation of iron ore attributes, in Proceedings Iron Ore 2013 , pp 129-136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

Andesites are a major source of aggregate for much of the North Island of New Zealand. There are regional differences with respect to some important properties of the andesites. Some are reactive with cement and are designated as potentially deleterious or deleterious by the concrete industry. Other andesites, particularly those that are slightly altered or weathered, have rather high Plasticity or Clay Indices and perform poorly in road construction.   The performance of the andesites has been investigated and can be shown to be determined by: +        the chemistry of the rock which in turn determines the chemistry of the glass in the rock; +        the presence of large amounts of groundmass glass in the rock; and +        the nature of the superimposed alteration processes. Environment of extrusion and how rapidly the rock has been cooled or chilled are also important as they determine the fabric of the rock and how much glass will be present in the rock.   There are three main types of alteration that affect the quality of the aggregate: 1.   hydrothermal alteration, 2.   late magmatic alteration associated with the devitrification of glass, and 3.   weathering.   Each of these alteration types produces different alteration minerals. In fresh andesites the devitrification of glass has an important affect on the rockÆs properties. The Taranaki andesites are shown to have unusually (in comparison with other North Island andesites) high Na2O contents, held in the groundmass glass, which is the fundamental reason for the high alkali û silica reactivity of these andesites.

Jan 1, 2005

When a thin film of volatile matter is deposited under vacuum on a polished coal surface, and the coated surface is examined microscopically in plane-polarized reflected light, colour changes are observed which are 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. Bituminous coal gave the best results.

Jan 1, 1970

Miners and explorers in New Zealand are expected to consult with stakeholders, keep out of core conservation areas, and operate a high standard of environmental management and rehabilitation. These requirements are not difficult to meet, but many of the industry's own actions have brought it to a low level of general public esteem in New Zealand. Reasons for this are discussed, drawing examples from the Maruia Society's experiences with the industry since the mid-1980s. The boundary between core conservation areas and other land is not easily drawn, and the Maruia Society has sought to work with the mining industry to promote legislation for net conservation benefit trade-offs. However this initiative was not successful. Today the industry, unlike most other major industry sectors in New Zealand, has no accord with the country's conservation movement.

Jan 1, 1997

Comparison of Grinding and Liberation Processes for Stalky Biomass Materials as a Prerequisite for Production of Energy Pellets with High Calorific Value Pelletising biomass, especially straw and stalky materials, requires a product specific size reduction and liberation. However, moisture content plays an important role in palletising and also affects the energetic properties of the biomass. The paper illustrates the characteristics of the mentioned type of biomass and specifies the necessities for production of energy pellets. Defined requirements for biomass energy pellets will be shown based on relevant standards. The work focuses on a comparative investigation of the straw fibres after grinding with hammer/impact mill and after the liberation of the straw fibres with twin-screw extruder (two different communition units). A traditional hammer mill as well as an hydrothermal process taking place in a twin-screw extruder were utilised. Results of the grinding and liberation of rye and wheat straw fibres are discussed based on a detailed particle characterisation (particle size and shape distribution). Besides high calorific value the main pellet quality parameters are mechanical stability, abrasion resistance and further combustion technical characteristics. The particle size distribution displayed optimum characteristics for the combustion processes to be carried out in a furnace. The durability of the pellets produced from straw fibres liberated with twin-screw extruder was comparatively better then that prepared with the straw fibres after grinding with impact mill. Particle size distribution, abrasion values and the strength characteristics showed a good correlation with each. The high presence of N and S would result in high NOx and SOx emissions, where as the high concentrations of Cl would corrode the furnace. These chemical properties of the straw would restrict its usage in small scale furnaces.

Sep 13, 2010

By B Rosemberg, F Lemos, A J. B Dutra

The chemistry of cyanide solutions is complex, this complexity being responsible for the ability to act as complex-forming agents in metal dissolution processes, among them gold and silver. Such ionic species are used in hydrometallurgical processes, in particular in gold extraction and electro-plating. Due to the high toxicity of cyanide, the discard of effluent from processes and/or industries demands rigorous treatment so as to minimise its concentration. Among the conventional chemical treatment of such effluents one can mention SO2/air; biological degradation; oxidation by using hydrogen peroxide; oxidation by sodium hypochlorite, etc. However, the electrolytic recycling process is also promising for cyanide recovery and offers the possibility of recycling it to the aforementioned industrial processes. Such a process does not use additional chemicals but enables direct re-utilisation to the main process aiming at adjusting the cyanide concentration.

Jan 1, 2002

By S Sandover, D Glenister

Alcoa World Alumina Australia is committed to sustainability principles as a basis of business success into the future. In March 2001, Alcoa Inc chairman Alain Belda announced a set of far-reaching environmental goals for the corporation, with the challenge that they should be achieved in ways that enhance economic and social performance, while substantially reducing environmental impact. Application of Cleaner Production methods is seen as the key to achieving these joint objectives. In Australia Alcoa has launched a co-ordinated effort to accelerate our application of Cleaner Production principles to delivering cost-effective in-process solutions to environmental issues. Our Western Australian Operations are a signatory to the WA Cleaner Production Statement, through which we provide a Cleaner Production Plan to the State Government on a voluntary basis. This paper describes in general terms AlcoaÆs goals, achievements and directions in applying Cleaner Production to enhance business performance in the economic, environmental and social dimensions. Quantification of the benefits and tracking of progress in quantitative terms is a key challenge for the future

Jan 1, 2002

The Golden Cross mine commenced production in December 1991. Both open pit and underground mines produce 1000 tonnes of ore per day. Mining techniques are discussed along with results and variations to proposed methods of extracting the ore.

Jan 1, 1992

By P Meehan, R McAree, Z Guan

Equipment maintenance is 30 - 50 per cent of the operating costs for a typical mining company. While this is substantial, its importance is beyond its significance as a cost heading. Modern mining requires large amounts of investment in capital infrastructure and equipment to produce a product sold at a low unit cost. To stay competitive, such a business has to focus on full realisation of its capital investment, ie sustained production at high levels. Maintenance plays an essential role in achieving this goal. Mining companies typically use a mix of breakdown or corrective maintenance, planned maintenance, and some condition-based maintenance. The share of breakdown maintenance has been coming down through more effective planned maintenance and better condition monitoring tools. Planned or preventive maintenance (PM) is playing an increasingly important role in todayÆs mining maintenance. This is the suite of inspection and repair/replacement actions performed at scheduled time intervals as part of a preplanned activity. The activities are scheduled well in advance and, usually, the current wear-state of the machine is irrelevant. For example, the replacement of a major gear may have been planned 18 months in advance; replacement is carried out when the time comes regardless of the actual condition of the gear. The PM costs are significant and include direct cost of parts and labour as well as the opportunity cost of lost production while the machine is under maintenance. It is important to identify the optimum PM effort because over-maintenance should be avoided as much as under-maintenance. A new concept called severity-based maintenance is introduced in this paper. We have seen that measuring equipment ageing in mining merely by counting the engine hours is a very imprecise way of planning and scheduling maintenance because the damage accumulated in one hour varies enormously from operator to operator and with changing pit conditions. We recommend continuous monitoring of duty on all major equipment. This is feasible without having to fit out the machine with an army of sensors because most of the physical sensors required by dutymeters are already installed and maintained as part of the existing performance monitors. While the investment is modest, the potential benefits are huge and can be grouped under three headings:Immediate benefits will come from providing operators with direct feedback on the effect of their behaviour on machine health and training them to use this feedback to correct their operating style. The equipment can operate closer to the limits of capacity, producing more without unduly sacrificing the availability by monitoring and controlling the severity of the operation, ie the duty on the machine. Longer term benefits accrue from establishing correlations between actual time to failure data and measured equipment duty and using these correlations to optimise maintenance effort as well as planning new equipment purchases and warranty conditions.

Jan 1, 2002

By B Murphy, A Uliana, P STrgio de Oliveira, G Ara·jo de Souza Franco, T Miettinen

Outotec has performed numerous research and development projects and various surveys in the study of reverse iron ore flotation. Over the past four years their TankCell-70 and TankCell-160 flotation cells at the Germano concentrator of Samarco in Brazil were extensively surveyed. These surveys have revealed some extreme operating conditions in reverse iron ore flotation and are the subject of this paper. Some of the findings include large variations in the content of solids in the various flotation stages. At the bottom of the cleaner cells, the content of solids by weight reached over 60 per cent, whereas at the bottom of the scavenger cell this was less than 50 per cent. Froth carry rates were also significantly different in the various flotation stages. In the case of coarse material, the scavenger cells operated at a froth carry rate of over 40 t/h.m2. With fine material, however, froth carry rates of less than 10 t/h.m2 were measured. High froth carry rates caused significant changes in the residence times at Samarco. In the rougher cells, the fifth cell had more than double the residence time of the first cell. This was even more pronounced with the scavenger cells, where the second cell had more than triple the residence time of the first cell. High froth carry rates also caused losses in iron recovery. As a consequence of such findings, it appears that different rules apply in the sizing of reverse flotation circuits compared to direct flotation circuits. Different operating parameters (mixing intensities and air flow rates) must also be used in the rougher, cleaner and scavenger cells in order to optimise the metallurgical performance. Outotec has also been working on a number of new technologies aimed at improving the metallurgical performance of iron ore reverse flotation circuits by increasing froth carry rate and decreasing fine iron entrainment.CITATION:Miettinen, T, Uliana, A, Ara·jo de Souza Franco, G, STrgio de Oliveira, P and Murphy, B, 2013. TankCell flotation at SamarcoÆs Germano concentrators, in Proceedings Iron Ore 2013 , pp 441-444 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The importance of the minerals industry to any economy is clearly demonstrable. Its raw materials and products are the foundation of modem society and they have shaped the history of mankind from prehistoric times to the space age of today. However, those in the minerals industry have clearly failed to impress this fact on the consciousness of the public, bureaucrats and politicians. They have also failed to engage their dedicated opponents in a constructive debate. This is mainly because the minerals industry has been unwilling (until recently) to deal with the "soft" issues of civil society, nor understand and operate on a more emotional level. Technical professionals (as well as managers) in the future must be as comfortable in handling community concerns over social, environmental or landowner issues, as they are with logging complex drill core, designing blast patterns and separating one mineral from another. They must become caring, effective communicators and mediators. These are the new skills of a professional in the Third Millennium. These issues are outlined and discussed with some Australian data used to illustrate the point. If there is to be a future for all, then the policy makers within all levels of government (national, regional or local) must not drive essential mineral development offshore. They must address ways to support wealth creation mechanisms, particularly innovation. The minerals industry is a powerful wealth creator for ordinary citizens and an innovator. Politicians and their advisers must not .be allowed to forget this fact. If the ANZAC minerals industries do not win the emotional debate and successfully deal with the "soft" issues as well as they deal with the technical issues, there can be only a dim future ahead.

Jan 1, 2000

Lead Removal from Contaminated Soils with Chelating Agents

Sep 13, 2010

Research on the Thermodynamics of Siderite Roast Decomposition and the Experiment of Magnetic Roasting-Separation

Sep 13, 2010

The role of government and the community has changed significantly over the last two decades in relation to environment protection, particularly in the mining sector. Increased community expectations have moved well ahead of regulatory requirements, and there is now a much greater appreciation generally of the concepts of ecologically sustainable development and intergenerational equity, and the gap between current practice and practices which would be in harmony with these concepts. Besides providing a `safety net' through regulations to ensure that basic environmental performance standards are met, government is now working proactively with the mining industry to encourage higher levels of environmental performance. This paper describes some initiatives between the Commonwealth government and the industry designed to achieve these higher levels of environmental performance, through programs aimed at the paradigms of best practice environmental management and continual improvement.

Jan 1, 1997

The Detachment of Coarse, Composite Particles from Bubbles

Sep 13, 2010

The theme of this conference is æRediscover OtagoÆ. In order to ensure the development and exploitation of mineral discoveries in New Zealand, considerable capital will be required, particularly from overseas. This paper briefly reviews the Government's foreign investment policies and procedures and highlights some trends.

Jan 1, 1992