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By B Vorster, T Medhurst, A Huey

Roof conditions at Oaky North Mine can be prone to stress related damage and/or time dependent degradation. The ability to identify these areas prior to mining has proved challenging using traditional methods. To help alleviate this situation, a study was initiated to investigate methods for roof characterisation using geophysical logs. This involved the use of neutron log data to provide an indirect measure of the proportion of carbonaceous/micaceous laminae present in the immediate roof strata. Detailed analysis of the shale–porosity inter-relationships arising from this analysis provided a means to estimate the proportion of laminations for a given roof interval. This paper outlines the process and how it was used to improve the current GSR modelling and hazard mapping process.

Nov 29, 2022

By C Swamydas

VV Mineral (VVM) group of companies is the largest and the first private producer and exporter of beach sand mineral products in India. During 2010, the company produced and marketed around 750 000 tons of saleable products. Their operations are mainly in the state of Tamil Nadu and Andhra Pradesh, India. Almost all the wet pre-concentration plants use sea water as the concentration medium, since there is no fresh water source available near the deposits. The mines are located along the south-east coast of India in the states of Tamilnadu and Andhra Pradesh. The orebody varies in terms of mineral assemblage, slime content, grain size, and surface coating resulting in different behaviour of the minerals. Three different deposits containing ilmenite of different TiO2 content were studied. The study shows that there is no significant impact of using sea water for wet concentration prior to high tension separation of ilmenite. There is no significant variation in recovery and purity of ilmenite produced from these deposits when wet concentration of the deposits were carried out with sea water as the concentration medium and whether the concentrates were washed with fresh water or not before dry separation using High Tension Roll Separators (HTRS).

Oct 5, 2011

By J Rutter, E Amini, D La Rosa, N Beaton, M Scott, F Faramarz, L Keeney

Anglo American’s Los Bronces copper mine in Chile has been conducting detailed assessments investigating value adding options for their asset. The mine has conducted several detailed Mine-to- Mill and Grade Engineering studies to investigate increased throughput and head grade and to quantifying the impact of these approaches across the life of mine. CRC ORE has two key technologies namely Grade Engineering and the Integrated Extraction Simulator. These two technology suites have been combined to understand the technological landscape and associated value drivers suitable for application at Los Bronces. Detailed ore characterisation test work was conducted to:  measure and spatially model the propensity of ores to naturally deport and  develop customised blast models for Mine-to-Mill and Grade Engineering evaluation The outputs of this work were utilised to develop a block model populated with a range on new Grade Engineering and blasting parameters suitable for scenario analysis. To facilitate scenario analysis a high-fidelity value chain model of the Los Bronces operation from blasting to concentrate production was built in IES. IES was combined with sophisticated analytical tools such as Neural Networks to develop and reconcile a fully integrated value chain. The value chain model made it possible to simulate in IES all available blocks in the block model to predict throughput and grade changes for different strategic scenarios. The scenario analysis was run across 24 strategic combinations of Mine-to-Mill and Grade Engineering and comprised several million simulations. The scenarios investigated each technology independently and jointly to provide an attributed block model that can feed forward into technoeconomic modelling to determine optimal execution strategies for the mine. This paper presents the first published study combining Grade Engineering and IES to provide mass simulation capability to investigate strategic options for a mining asset.

Nov 10, 2020

By Takasaki Y, Ohzeki S, Hotta H

TO measure high temperature properties of blast furnace burdens ( the change of gas permeability accompanied by contraction, soft- ening and melting ) which govern the gas flow and its distribution, a series of experiments were carried out under simulated blast furnace conditions, using sinter, acid pellets and self -fluxing pellets. 1) The high temperature properties are affected by the ore's reducibility ( up to 1000 -1200¦C ), and the composition, and volume of gangue before reduction. Generally, the burde- ns with high basicity ( Ca0/Si02 ), high reduc- ibility and low volume of gangue have good high temperature properties. Good high temperature properties are : a high temperature at which the gas permeability rapidly decreases, a high melting point and a low maximum pressure drop. 2) Using acid pellets, slow-down of red- uction rate occurs around 1000¦C because the pellet forms a dense metallic shell, while its slag core, resulting from a FeO, Si02 and A1203 reaction, has a lower melting point. 3) The addition of MgO sources improves high temperature properties both of sinter and Pellets.

Jan 1, 1980

By Nava-Vasquez E, Torres-Torres J, Mendez-Nonell J

The ZA-27 zinc base alloy was poured into cylindrical moulds and solidified under different conditions ie normal freezing and unidirectional freezing. In addition a cylindrical ingot with rheocast material was obtained by stopping the stirring action and, at a specific solid fraction, gravity casting it into a graphite mould. It was observed that the material obtained under normal freezing conditions is likely to present both segregation and inverted pipe. In contrast, the unidirectional solidified and the rheocast cylinders showed the absence of inverted pipe. The segregation pattern was quite irregular in the rheocast ingot while such segregation was more uniform in the unidirectional solidified cylinder. By virtue of these observations, the inverted pipe formation may be ascribed to the interdendritic flow, while the irregular segregation pattern in the rheocast ingot may be attributed to an irregular distribution of the liquid and solid fraction along such a cylinder.

Jan 1, 1993

By Kidd CH

The excavation of a coal mine or any other mine, tunnel, or quarry, below the water table establishes a void towards which ground- water will flow. Inflows into the mine, if significant, can cause not only problems such as flooding, and/or muddy floors, in the mine, but commonly also require disposal of poor quality groundwater. The flow of groundwater towards a mine is accompanied by a decline in groundwater levels, which may extend up to several kilo- metres around the mine. This may seriously effect vegetation, stream flow and existing users of groundwater. At the pit face groundwater gradients can also cause slope stability problems and where a water table is intersected, increase blasting costs.

Jan 1, 1983

By M I. Pownceby, M A. Rhamdhani, S Purohit, G Brooks

The current practice of magnetite ore agglomeration involves high temperature oxidation roasting (typically at 1200–1350°C) of magnetite to hematite phase in order to improve the strength and reducibility of pellets. The requirement to pre-oxidise the magnetite before introduction to an ironmaking plant increases the CO2 emissions generated during the ironmaking process. In our previous papers, a novel, alternative agglomeration route for magnetite ores was presented where magnetite was converted to a reducible CaFe3O5 (CWF) phase through the addition of lime to produce a Lime-Magnetite Pellet (LMP) feedstock that can be directly charged to ironmaking units. The LMP process eliminates the magnetite oxidation stage, thereby reducing the CO2 emission during ironmaking. The concept was tested by thermodynamic calculations, high temperature experiments and scaled-down pilot scale test work. In this paper, larger scale synthesis of halfstoichiometric LMPs (1 mole of Fe3O4 and ½ mole of CaCO3) were prepared using a balling drum, followed by overnight drying at 110°C and induration at 1050°C for two hours. The LMPs were analysed using X-Ray Diffraction and Scanning Electron Microscope techniques for phase and microstructure characterisation. The LMPs were found to have 14–15 wt. per cent of CWF phase when indurated under a CO2/CO ratio of 8.5:1. Pilot scale testing of the LMPs was conducted following ISO standard test procedures. The test results indicated the LMP’s had a Reducibility Index (RI) of over 91 per cent, a Tumbler Index (TI) of 87 per cent and a Reduction Degradation Index (RDI) of 4.6 per cent. The results indicate LMPs may be useful as an alternative feedstock to ironmaking processes that would result in lower overall CO2 emissions.

Nov 8, 2021

Nauru Phosphate, which is one of the world's highest grade deposits discovered to date, contributed in 1969, 2.2 million tons of the total world production of 77.7 million tons. Phosphate production, which is the major source of revenue for the island nation, is carried out by the Nauru Phosphate Corporation, headed by a Government appointed Board of Directors. The complete mining operation, including ship loading techniques, is discussed along with proposals at present being investigated to upgrade the Quality of the product.

Jan 1, 1971

Corrosion affects the performance of rock support and reinforcement at various underground mines, including the George Fisher Mine, where recent studies showed that this risk to mining operations is generally not well understood. Corrosion reduces the capacity and life expectancy of ground support and generally is undetected unless the traditional destructive pull out test is employed to detect defect bolts. Where it is still acknowledged that the pull out test has still an important role to play in determining critical bond lengths for static and quasi static ground support designs, it does not provide an underground operation with any reassurance regarding its bolt's integrity, which has been compromised by in situ aggressive conditions. Non-destructive rock reinforcement calibration testing on single and twin strand cable bolts, rebar bolts and friction bolts at the George Fisher Mine enabled the testing team to detect bolts with compromised integrity in one area of the mine. The non-destructive rock reinforcement integrity testing conducted uses a complex 'Stress Wave Analysis' package based on the processing of clear seismic signals imparted into the rock reinforcement element that is being tested. The seismic signals are processed by 'Fourier Transform' into various criteria which can be used to produce models of the element such as mechanical admittance, frequency spectra and velocity which are all being used in the final modelling of the rock reinforcement element under analysis. This paper highlights the enormous potential to effectively manage the geotechnical risk that corrosion presents for an underground mining operation.

Nov 25, 2010

By D Cliff

"It has been 17 years since the mine disaster at Moura No 2 Mine in Queensland. Recent disasters in the USA and New Zealand prompt the question what has changed since 1994. This paper att emptsto answer this question and identify areas that need improvement."

Jun 1, 2012

Results of investigations on adsorption and desorption of CO M CH and a mixture of the two gases are described.4 Results showed that even when the equilibrium conditions contains 50% Co and 50% CH4, the gas emission in the initia' stages will contain as much as 80% CH . 4 The temperature has a small effect and so also particle size for 1.4-11.2mm. The ratio of CO2/CH gases adsorbed in coal samples depends upon t4he equilibrium pressure and this ratio decreases with pressure. Results of field tests support laboratory studies.

Jan 1, 1988

Attention is drawn to the largest eruptions with dense rock equivalent (D.R.E.) volumes approx-imating 50 km3. These have been strongly clustered during the last 40 000 years, with 11 recognised in the period 35 000 to 22 000 years ago, and 10 in about the last 9000 years, but none in the period 22 000 to 9000 years ago. With the latest such eruption, at Tambora, only 175 years ago, it is likely that we remain in a period of increased activity. During the last 100 000 years, roughly the period during which modern Homo sapiens has existed as a species, there has only been one eruption an order of magnitude larger (>_ 500 km3 D.R.E.). This took place at Lake Toba, Sumatra, about 75 000 years ago, and is estimated to have deposited ash to a thickness of a centimetre or so in parts of Ethiopia, Somaliland, Saudi Arabia and Iran, and to a thickness of a few millimetres in the eastern Mediterranean. The average interval between global eruptions of this magnitude is probably about 40 000 to 50 000 years. Insufficient work on the Quaternary history of volcanoes has been carried out to suggest where the next such eruption might occur. At Yellowstone, which has been well studied, the average interval between very large explosive eruptions is about 700 000 ¦ 120 000 years.As a prerequisite for magnitude-frequency analysis of eruptions, and hazard and risk impact assessments, it is important to classify past eruptions in a consistent manner. In an attempt to find a universally applicable method to estimate order of magnitude D.R.E. volumes from the distribution of airfall tephra, an empirical correction has been derived for the elongation of tephra dispersal fans due to wind. Dispersion distances for various thicknesses of tephra, recalculated for windless conditions, have been obtained from a study of about 40 tephra isopach maps for which D.R.E. volumes have been calculated, and a range of distances derived, equivalent to D.R.E. volumes from 106 m3

Jan 1, 1990

By J P. Richards, M D. Johnston

The Porgera gold mine, located in the highlands of Papua New Guinea, produced 7.7 Moz of gold between 1990 and 1998. Reserves are estimated to be 12 Moz of Au. The deposit is associated with 6 Ma-old mafic alkalic intrusions emplaced at shallow levels into unconsolidated Jurassic and Cretaceous sediments, where they caused the formation of peperites. The mineralisation consists of an earlier base-metal-sulphide-rich stage with sericite-carbonate alteration (stage I), and a later phase represented by quartz-roscoelite veins (stage II). New styles of mineralisation and alteration have been recognised at depth in association with stage I. They consist of the assemblages magnetite-chalcopyrite-pyrrhotite and biotite-actinolite-anhydrite respectively. In addition, the recent recognition of adularia in some stage II veins (with roscoelite) confirms the similarity of this style of mineralisation with other adularia-sericite or low-sulphidation epithermal deposits.

Jan 1, 1999

By Hamblyn S

Oakbridge, in combination with its joint venture partner, Nippon Steel of Japan, is expanding its Bulga underground and open cut mines to meet the growing demand for coal in the Asian market. Expansion works underway will see the Bulga underground mine become a world leader in underground productivity, the introduction of a high capacity dragline into the open cut mine (largest capacity dragline in NSW) as well as a major upgrade of the coal preparation plant (CPP) and coal handling facilities (CHF) to process the increased production. This paper describes the planning and implementation of this major expansion program and highlights the rationale behind some key aspects of the program.

Jan 1, 1995

By B Murphy

Safescape Laddertube provides an improved system for emergency egress in ventilation shafts. The addition of Laddertube in a rise has very little impact on ventilation flow, studies have indicated that the difference in flow velocities are difficult to measure due to the minimal impact. Due to the size and open-ended nature of Laddertube, the air velocity inside and out of the Laddertube is mostly linear. Laddertube can be used either permanently or during an emergency as a secondary ventilation duct. One project involved a 385 m ladder installed in a surface return air raise that could be made to bypass the primary circuit and supply fresh air to a sea container fresh air base at the bottom of the raise. Laddertube has been designed to be installed to any feasible length and can be fitted with a climb assist system ensuring enhanced speed and reduced fatigue during ascent. The climb assist used in association with Laddertube is a Tractelift system which applies a weight relief of up to 36 kg off the climber’s body weight when using the ladder. This system has successfully been tested for ladders up to 600 m in length and is currently in use for a ladder of 185 m length. The use of refuge chambers in underground coalmines has long been a contentious issue due to the concern that while it may provide temporary shelter, the risk of being exposed to high heat or the inability for rescuers to access them due to fire or explosive atmosphere means that they may be effectively trapped. The additional application for coal environments includes Laddertube installed alongside a refuge chamber concealed behind a blast proof door ensuring a secondary means of emergency egress. In certain operations designs may allow for this chamber to be provided withpositive pressure fresh air.

Oct 12, 2022

By D Johansson, C Yi

Blasting techniques are widely used to fragment rock masses into smaller pieces. Numerical modelling is an efficient method employed by many researchers in the blasting field. It is difficult for a conventional continuum-based approach such as the finite element method (FEM) to model the rock fragmentation by blasting and the expansion work on the rock by explosive and its detonation products. In this paper, the particle blast method (PBM) was employed to model the behaviour of the detonation and a bonded particle model (BPM) was used to model the brittle material to be blasted. A mortar cylinder with a centrally placed hole for the explosive was modelled and the results were compared to the experimental data. The blast process from crack initiation to fragment formation was analysed. The influence of coupling ratio on fragmentation was also investigated.CITATION:Yi, C and Johansson, D, 2015. Discrete element modelling of blast fragmentation of a mortar cylinder, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 793–798 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By T D. H McGrath, O Baker, W P. Staunton, C Ypelaan

"The carbon-in-pulp process has been used extensively in the gold industry since the late 1970s to recovery leached gold from solution. Despite more than 30 years of experience in operating carbon circuits, average gold solution loss has remained at an average of 0.02–0.03 ppm (mg/L), higher than the ‘best practice’ target of 0.01 ppm.Process modelling, such as SIMCIL developed by the Curtin Gold Technology Group (GTG), can provide information on optimum set points; however, manual control of the circuit limits the potential benefits.An automated carbon measurement device, the Scout Carbon Meter, has been developed to allow for automation of carbon concentration measurement, and automated control of the carbon transfer pumps. This paper describes the results from the evaluation of the first two prototypes of the meter.Citation:Staunton, W P, McGrath, T D H, Ypelaan, C, Baker, O and Eksteen, J J, 2016. Optimising Carbon Management - Increasing Gold Recovery and Decreasing Costs with the Carbon Scout, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 225–228 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

The deep seafloor in Papua New Guinea's proposed Exclusive Economic Zone appears to be a gold-rich province in the same sense as the territory above sea level. Two significant sites with polymetallic massive sulphide deposits forming today are known on neovolcanic ridges in the Manus Basin. Their high precious metal contents have led to renewed interest in the issue of exploiting seafloor mineral deposits. The prospects of finding other, possibly larger deposits in the region appear substantial. This paper reviews current data on seafloor deposits in Papua New Guinea (PNG) and raises some issues relating to future commercial exploration and mining of the sea floor. One of the known PNG deposits could become a prime candidate for the trials needed to develop technology, establish costs, and minimise environmental impact.

Jan 1, 1994

By Schaap W

A test on Taylor's rule of mine life using published data on open pit porphyry copper mines confirmed that mine life is, on average proportional to the fourth root of reserve tonnage. Deviations from this rule-of-thumb occur to a large extent as variations between regions that are qualitatively explained in terms of differences in grade, infrastructural needs or special taxation effects.

Jan 1, 1984

Mining is a global industry. The conference is a good example of this, as itÆs jointly organised by professional associations from Canada, Australia and South Africa, and has attracted speakers and delegates from around the world. I commend the organisers for their initiative. I am pleased to be asked to participate in this panel û although I would hasten to add I see myself as perhaps an informed observer rather than an expert. It wonÆt be news to most in this room that AustraliaÆs mining sector is booming. As one of the most productive and diversified mineral regions in the world, this activity is also something that has not escaped the attention of CanadaÆs largest mining companies! This means that I follow what is happening in the industry and more specifically what might be occurring here. Two-way investment between Canada and Australia stood at $9.8 billion in 2005 with Canada as the seventh largest overall investor in Australia with $8.22 billion in investments. The majority of this investment is by Canadian minerals and metals companies. In recognition of the importance of Canadian investment in this sector in Australia, I maintain close contact with our companies. By way of example, in the past two months I spent a week in Western Australia visiting Perth and meeting with companies for example, like Teck Cominco and LionOre as well as seeing various Barrick Gold operations in Kalgoorlie. I attended the opening of AlcanÆs new Asia Pacific Headquarters in Brisbane in August and just two weeks ago was in Cowal, NSW for the opening of BarrickÆs new mine there. Having met with BHP Billiton in Vancouver, IÆm equally aware of active Australian mining interests in Canada. This is not designed to indicate how active I am but rather to demonstrate the dynamism in the mining industry and the diversity of Canadian mining interests in this country and Australian interests in Canada.

Jan 1, 2006