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By R A. Pax

Heavy machinery such as AG and SAG mills generate a significant amount of noise due to the processes that are occurring inside them. From an environmental perspective, the level of noise generated is a significant occupational safety hazard. However from a technical perspective the noise presents an opportunity to determine some details of the processes occurring inside the mills. The noise generated is not random and can be attributed to a range of events that occur inside these mills, consequently non-contact acoustic determinations of in-mill behaviour provide powerful insights into the operation of the primary comminution tumbling mills. Traditionally, the use of perfect mixing has been assumed when modelling the operation of AG/SAG mills. If this were true then the acoustic emissions from AG/SAG mills would be uniform along the length of the mill. Experimentally this has been found not to be the case. From another perspective it should not be the case because of the different conditions existing at the feed end compared to the discharge end. This paper presents the results determined by non-contact acoustics and their analysis in terms of understanding of the mechanisms occurring inside a mill.

Aug 8, 2011

By T Gready

Stawell Gold Mines operates the Magdala underground mine in western Victoria, Australia. Several orebodies are extracted by longhole open stoping at a depth of 900 m below the town of Stawell. Some stopes are backfilled with cemented slurry rock fill (CSRF) to ensure stability, increase recovery of ore reserves, minimise dilution of ore grades, and add value to the project. StawellÆs simple CSRF system is described, including the novel equipment used to minimise capital costs. Design criteria, operating procedures, monitoring systems and results are discussed in detail. Practical aspects are considered, including lessons learnt about barricades, overbreak and segregation. The economics of CSRF are discussed, including capital costs, operating costs and the total cost per ounce of gold poured. Options for mining with and without CSRF are compared in terms of return on investment and net cash flows. Examples demonstrate the method used to calculate æbreak-evenÆ stope ore grades which determine whether or not CSRF will add value in different circumstances.

Jan 1, 2002

By J Knecht, R Klymowsky, E Burchardt

The wide spread introduction of SAG mills into grinding circuits 20 years ago was the last development which had a major impact on the design and economics of comminution circuits. Single SAG mills were able to replace batteries of high maintenance and cost intensive crushers in order to achieve high throughput operations. Today, where the head grades of gold and copper ores are falling, there is again a strong need for a significant breakthrough to reduce investment and operating costs as well as improve metal recoveries. High-pressure grinding rolls is the new technology available to meet this challenge. HPGRÆs are state-of-the-art in several mining and minerals applications such as the grinding of iron ores and concentrates, and diamond bearing ores. Reasons for their success in these industries are overall cost reductions and improved product properties achieved by the application of high compressive forces. But these ores are relatively soft, with unconfined compressive strengths up to 150 Mpa.

Jan 1, 2000

By E Yurakov, D J. Ashelford, M I. Slate

The push for increasing coal production rates continues to place increasing demands on mine management to safely and effectively control seam gas. Gas drainage strategies applied vary in both effectiveness and form. Methods employed are a function of assessed risk, gas reservoir characteristics, surface and underground access, budgetary constraints and gas utilisation potential. With the aim of establishing and optimising the effectiveness and efficiency of gas drainage systems, Australian coal miners in cooperation with gas management specialists are embracing the use of gas reservoir simulators and gas emission models. This paper discusses the evolution of gas drainage practices in Australian underground coal mines and the role of gas reservoir assessment methods in optimising gas drainage systems and gas production forecasts.

Jan 1, 2005

By Johnson N. W, Manlapig E. V, Alexander D. J, Franzidis J. P

The importance of the froth region on flotation performance is often emphasised in the literature. It is well-known that decreasing froth depth or increasing air flowrate results in increasing cell recovery at the cost of lower concentrate gra

Jan 1, 1997

This paper looks at the development in management education for engineers at the undergraduate level with particular reference to mining engineers. The management core content of the engineering degree course at Ballarat C.A.E. is described is some Detail.

Jan 1, 1986

By Y Peng, D Liu, S Vink, B Wang

There have been strong industrial observations that clay minerals have a deleterious effect on mineral flotation grade and recovery. However, rigorous explanation on the role of clay minerals in flotation and effective ways to reduce their negative effects are not available. In this study, the flotation behaviour of low quality and high quality coal samples were examined at the Xstrata Oaky Creek Coal plant, and laboratory in fresh and recycled water with high ionic strength. Anionic and non-ionic dispersants including lignosulfonates and triblock copolymers were also tested with an objective of improving coal flotation in recycled water. It was found that overly stable froth was produced in the flotation of both low quality and high quality coal samples in saline water. Speciation modelling indicated precipitation of hydrophilic components which may adversely affect the flotation. Despite the overly stable froth, saline water produced much higher combustible recovery than fresh water without significantly losing the product quality. Lignosulfonate dispersants displayed a potential to improve the flotation in fresh water, but not in saline water. Significant flotation improvement was achieved with the triblock copolymer examined in both fresh and saline water.CITATION:Liu, D, Wang, B, Peng, Y and Vink, S, 2012. Determining the effect of clay minerals on coal flotation using saline water, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 151-158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

The Mt Lyell Mine at Queenstown, Tasmania was re-opened in 1995 by Copper Mines of Tasmania Pty Ltd, a wholly owned subsidiary of Mt Lyell Mining Co Ltd. The re-opening followed over 100 years of copper and gold mining at Mt Lyell. Major changes in practice were implemented across the site. Preventing further damage to an already disturbed environment was a major priority. Sublevel caving, at a lower cut-off grade, replaced open stoping for the deep underground mining. Development and later stoping are handled by a contractor, National Mine Management Pty Ltd, in the largest underground contract awarded at the time. Large scale sublevel caving was new to Mt Lyell and not widely practised in Australia, requiring studies and systematic development of the method, particularly in drilling and blasting. Rehabilitation and upgrading of mine infrastructure have been and will continue to be a challenge. The mine has, since 1995, returned to being a stable producer with potential for growth.

Jan 1, 1998

By T Higuchi, K Fukada, K Takehara, Y Iwami, S Fujiwara

Following the Paris Agreement adopted in 2015 and the SDGs, reduction of CO2 emissions has been taken up as an issue worldwide, and the steel industry, which has a particularly large emission, is required to significantly reduce it. Most of the CO2 generated in the steel industry is generated from the ironmaking process, due to the use of coke and its raw material coal in the ironmaking process. JFE Steel Corporation has been considering the use of hydrocarbon-based gaseous fuels and liquid fuels as a partial alternative to coke breeze used in the sintering process since 2006, immediately after the Kyoto Protocol came into effect in 2005. In a laboratory study, a pot test was used to investigate the effect of the type of fuel, its amount and its injection method on the heat pattern in sinter bed. As a result, the authors developed a technology, in which a predetermined amount of gas fuel or liquid fuel was injected from the surface of sintering bed to extend the holding time of 1200°C or higher at which liquid phase sintering occurs in the layer, to improve the sinter strength while reducing the amount of coke breeze. The authors succeeded in putting this technology to practical use using hydrocarbon-based gas fuel in 2009 and achieved a maximum annual reduction of 60 000 tons of CO2 per sintering machine. In this report, the authors introduce the results of laboratory studies on the use of various energy sources, the practical application of the technology for injecting hydrocarbon-based gaseous fuel into the sintering machine, and the operational results.

Nov 8, 2021

By Weller KR

Computer programs are described which help the metallurgist to process sample data from a plant survey; to carry out simple mass balance calculations; to present the results of circuit and equipment performance in convenient form; and to simulate the circuit response to changing operating conditions. The uses and limitations of these programs are explained by following through a case study of the sulphide flotation circuit at Cleveland Tin Ltd. The circuit was sampled, the data analysed, and some process inefficiencies established. Simulation calculations were then made to provide information on which to base decisions regarding possible circuit changes aimed at improving performance.

Jan 1, 1983

The liquid products of low-temperature carbonisation of coal are of variable composition, very much influenced by the rank and type of coal, and process parameters. In general the tar contains a high proportion of phenols and a low proportion of bases. The neutral oil is more analogous to a thermally cracked petroleum oil than to a high temperature tar. Present practice and possible future trends in the production of chemicals and liquid fuels from low temperature tar are reviewed in the light of recent work on the detailed composition of the tar The phenols and aromatics will probably continue to be of most value, with the bases a useful source of spec- ialty products. However the high aliphatic content of the neutral oil (particularly 1-olefins and n-paraffins) is bound to receive more attention for chemicals as well as for liquid Fuels.

Jan 1, 1969

Where tunnel rounds are based on the burn cut, faster advance could often be achieved by increasing blasthole diameter from (the conventional)

Jan 1, 1981

A survey of derelict and active alluvial tin and sapphire mines in the Emmaville area of northern N.S.W. as the first step in a pro- gramme of similar surveys to be undertaken throughout the State by the State Pollution Control Commission is presented. Thirty nine individual mine sites in the study area were included in the survey and an assessment made of the current level of impact on the environment at each site by assigning values of "magnitude" and "importance" to a number of impacting factors. Results are pre- sented in matrix form and mine sites ranked in order of impact "importance". Examples of alluvial tin, underground tin/arsenic and alluvial sapphire operations are discussed in detail and rehabilitation programmes proposed for implementation.

Jan 1, 1976

By J Rostami, D Tadic

While hard rock tunnel boring machines (TBMs) have an established track record in the tunnelling industry, accurate estimation of TBM performance for each specific project remains critical. Machine performance prediction is required to assist planning activities, including costing and schedule preparation, machine specification and effective planning of maintenance and repairs. In addition, monitoring machine performance during the construction period is required to assess and manage excavation progress, and to achieve optimal advance rates based on specific geotechnical conditions exposed during excavation. TBM performance analysis can also contribute to the development of more accurate performance prediction models for future applications. Rock mass characteristics play a dominant role in machine performance. This paper offers a review of the impact of rock mass characteristics on TBM penetration rates for two specific tunnelling projects. A discussion is provided on the results of statistical analysis of available field data, including geological back mapping, rock properties and measured rates of penetration (ROP). The analysis offers a comparison of the achieved and predicted ROPs to provide a better understanding of the influence of rock mass properties on the performance of hard rock TBMs. A new rock mass adjustment factor is introduced to enhance the accuracy of an existing prognosis model for use in jointed rock masses.

Jan 1, 2008

By Sivell W

We discuss the origin of the Patuki ophiolite complex and the Dun Mountain ultramafics of Middle Permian age in Nelson, New Zealand. It is shown that the Patuki volcanics have strong affinities with tholeiites of mid ocean spreading ridges transitional to alkaline basalts similar to those from fracture zones and ocean islands. At D'Urville Island, typically pillowed alkaline basalts enriched in rare light rare earth elements (LREE) - ophitic spilites - are associated with LREE-depleted (N-MORB-like) tholeiitic spilites with intergranular textures. The metabasalts are associated with a wide variety of sediments, and with sediments are intruded by conformable sheets of serpentinite. Coarsely crystalline mafic and plagiogranitic rocks signify vents and magma chambers, and we propose that the group developed as ocean crust from a slowly spreading mid-ocean ridge, transform association, overwhelmed at intervals by volcaniclastic sediment. Detailed mapping at a scale of 1:5000, and stratigraphic and geochemical development and structural coherence, show that the group is not melange in the Franciscan sense. The Dun Mountain Group, of serpentinites, peridotites, dunites, gabbros and other rocks, intruded the upper Patuki Group as a linear series of aligned pods and sheets. They carried up with them tectonic inclusions of older rock, which were metasomatised, and altered wall-rock, and one low angle dike passed several hundred metres into overl~ing sediment, at moderate temperatures (500 C). The rocks did not act as a floor (and alleged source) for the Patuki, but partly post-dated and were emplaced into Patuki.

Jan 1, 1987

By J Zhao, C E. Loo

The flame front is a narrow region in the iron ore sintering bed where coke particles combust. The maximum flame front temperature is as high as 1400°C. At high temperatures, the sinter mix components react to form melts, which facilitates material coalescence and the formation of dense sinter particles. It is well-established that flame front speed is an important factor influencing sinter productivity, sinter quality and fuel rate. In this work, the effect of suction, coke addition and mix moisture on flame front speed was studied in a pilot-scale sinter pot and also using the outputs of a recently developed theoretical model, which takes into account most of the significant physicochemical processes in sintering. Airflow through the bed has a large influence on flame front speed. A power law relationship between these two parameters means that increasing sintering airflow rate will lead to increased flame front speed, but the increases become smaller at higher airflow rates. Sinter pot test results showed that increasing coke addition decreased green bed permeability and increased flame front temperature, which resulted in increased flame front resistance and decreased flame front speed. Studies also showed that green bed properties are sensitive to sinter mix moisture level. The changes in green bed properties further influence the flame front speed and temperature.CITATION:Zhao, J and Loo, C E, 2015. Dependence of flame front speed on iron ore sintering conditions, in Proceedings Iron Ore 2015, pp 83–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By H Mansouri, M A. Ebrahimi Farsangi, F Faramarzi

A blast fragmentation model is developed based on the gamma function to describe the run-of-mine fragmentation distribution. The model presented is aimed to benefit from simplicity in application and also to be efficient in description of the fine to coarse part of the blast rock fragments. In fact, the gamma based model (KC-KUM), gives a unit distribution curve, which is made up of two separate equations, covering different fragment sizes in the muck pile. The generated values of the fines to central part of the equation and the central to coarse part of the equation are connected at the 40 per cent grafting point. For validation, eight production blasts, which were specially designed for this purpose, were carried out at an iron ore mine (Jalal-Abad iron ore mine/Iran). Results achieved by KC-KUM and two of the most well-known models. Kuz-Ram and Swebrec, are compared with measured data. Moreover, to assess the models’ efficiency in presenting the best distribution curve, a Logarithmic error method is chosen. Based on the achievements. KC-KUM has the least deviations by the least absolute log error of 0.52, whereas the values obtained for the Swebrec and Kuz-Ram models were 0.79 and 1.34 respectively. Furthermore, the models were applied to predict X80 for 12 production blasts carried out at Gol-e-Gohar iron ore mine/Iran. These predictions were compared with the results from these trials. The coefficient of determination (R2) and root mean square error (RMSE) are calculated. Consequently, the highest R2 was obtained for KC-KUM at 0.837 with the least RMSE of 11.31. On the other hand, R2 and RMSE are equal to 0.832 and 20.19 for Swebrec; and 0.813 and 19.75 for Kuz-Ram respectively. The results obtained suggest the superiority of the KC-KUM model over the other two models in assessment and prediction of blast fragmentation in a reliable way.CITATION:Faramarzi, F, Ebrahimi Farsangi, M A and Mansouri, H, 2015. Prediction of rock fragmentation using a gamma-based blast fragmentation distribution model, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 685–692 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By F Cappuccitti

A colourimetric technique, originally developed for methyl iso butyl carbinol (MIBC) based on the Komarowsky reaction, has been extended to a wide range of common mineral flotation frothers. The procedure, which is briefly described, is shown suited to on-site determinations in a campaign at Kennecott Utah Copper Copperton Concentrator (Rio Tinto). Some observations are described, including: frother (MIBC) concentration evolution down a bank, frother distribution between pulp and froth phases, and loss of frother over time due to adsorption on certain minerals. A possible interference with a fuel oil addition was overcome. MIBC in recycle water was also measured. The ability to monitor frother easily will help interpret gas dispersion behaviour and should permit further optimisation of flotation cell hydrodynamics and chemistry. The capability to directly measure should help optimise the type, amount and location of frother addition, and to assess frother recycled with reclaim process water.

Jan 1, 2005

By D J Rawlings

The Palaeo- to Mesoproterozoic McArthur Basin contains a thick (-10 km) intracratonic platform cover sequence of unmetamorphosed and relatively undeformed sedimentary and volcanic rocks (Pietsch et al, 1991). It covers an area exceeding 180 000 km2 of the North Australian Craton (Figure 1), overlying segments of the older deformed basement and transitional igneous units. Volcanism in the basin (including transitional domain) followed a four-phase pattern. These phases are geologically distinct and widely distributed, and are also recognised beyond the McArthur Basin in many similar-aged tectonic provinces in northern Australia. The four phases are described briefly below. Regional and structural nomenclature used refers to Figure 1. A stratigraphic correlation diagram is presented in Figure 2.

Jan 1, 1994

By A R. Firth

The induration furnace for iron ore pellets was originally designed to process concentrates with high contents of magnetite. To support the use of haematite concentrates, internal fuel was added to the pellets in the form of ground coke breeze or anthracite. To ensure that the addition of coke breeze was not excessive, the ‘heat of magnetite equivalent’ or heat of magnetite equivalent (HME) relationship was developed, guaranteeing that the fi ring temperature requirements remained the same. However, this oversimplifi es the different reaction paths of magnetite and carbon in iron ore pellets. At fi ring temperatures, gas diffusion controlled reactions such as the combustion of coke, the calcination of carbonates and the reduction and oxidation of iron oxides can all occur in different parts of the pellet simultaneously. The interaction of these reactions produces a range of atmospheres across the diameter of the pellet that vary from oxidising at the pellet shell to reducing at the pellet core. Mathematical modelling and pellet fi ring experiments to preheat temperatures before quenching have shown that a higher proportion of coke relative to magnetite slows down the oxidation process, irrespective of temperature. A higher temperature, however, results in an increase in the rate of haematite reduction in the pellet core and a more reducing atmosphere, which could lead to different sintering rates in different parts of the pellet and shrinkage cracks forming. To observe these gas-solid reaction rates at a larger scale, the COREM pot grate has been updated with an additional oxygen analyser. This, along with other improvements, will allow better optimisation of straight-grate firing cycles for different pellet compositions.

Jul 11, 2011