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By A J. Morrison, M Yahyaei, J S. Siong, J Wang, K Runge

The flotation cells used to upgrade ultrafine metallurgical coal (-250 µm) are usually poorly controlled leading to unnecessary loss of combustibles from the flotation system. This is mainly because coal flotation cells are typically controlled for process stability rather than optimisation of flotation performance. This is especially true for a flotation device commonly used in coal applications in Australia – the Jameson Cell. This then provides an opportunity to improve the flotation performance by shifting from a stabilising control strategy to a proactive optimising control strategy. For an optimising control strategy, the control system will require a means of relating and then measuring in real-time, the effect of changing operating conditions on the coal flotation performance. Hence, the major aim of this work is to propose a possible model-informed process control strategy that could be used for real-time performance optimisation. In this study, industrial site work was conducted on an industrial-scaled Jameson Cell at a Coal Handling and Preparation Plant (CHPP) in Central Queensland, Australia where superficial gas velocity was controlled to six different levels. At the same time, other process variables such as froth depth and flotation feed properties were measured. The empirical models developed from this study suggested that combustible recovery is a function of superficial gas velocity, froth depth, feed solid content and feed ash content and that a peak in combustible recovery existed as a function of superficial gas velocity. This led to the development of a model-informed control strategy that aimed to maximise the combustible recovery by determining and then operating the cell at the superficial gas velocity at which the peak occurs. This peak superficial gas velocity was found to be only a function of feed solid content. Based on these findings it would seem possible to operate a Jameson cell at peak performance by online measurement of feed solid content, prediction of the optimum superficial gas velocity and stabilising control to maintain operation at that superficial gas velocity set point. The development of this modelinformed control strategy can serve as a basis for the development of a more sophisticated modelpredictive control (MPC) system. However, more work will need to be done to improve the predictivity of the combustible recovery model by measuring and modelling performance over a wider range of operating conditions.

Aug 24, 2022

By J-P Franzidis, E V. Manlap

Froth transportation characteristics have a significant impact on the flotation recovery especially in large flotation cells. The probability of an attached particle being recovered into the concentrate depends strongly on the location where it enters the froth phase. A mathematical model for froth transportation in industrial flotation cells was proposed (Zheng et al, 2004). The model has been tested on the experimental data obtained from testwork conducted at the Western Metals Hellyer lead/zinc concentrator. The results show that the model fits the experimental data well, especially when the froth is well developed (ie for a deep froth). The model fitting can be significantly improved by incorporating an air dispersion factor. However, the models encounter some limitation, ie inconsistent prediction at different froth heights, due to change in froth viscosity which cannot be modelled at the present time.

Jan 1, 2005

The sixth international symposium on mining with fill nearly coincides with the 25th anniversary of the Jubilee Symposium on Mine Filling. That symposium, held in August 1973 in Mount Isa, in part to commemorate the 80th anniversary of The Australasian Institute of Mining and Metallurgy, was the first in what has turned out to be a very successful series of symposia. Subsequent symposia were held in Sudbury, Canada (1978), Lulea, Sweden (1983), Montreal, Canada (1989) and Johannesburg, South Africa (1993). The series of symposia has now become an established part of the mining industry calendar, and it will be interesting to see which country is given the honour, and accepts the challenge, to organise the next symposium.One way of predicting the future, or some small part of it, is to revisit where we have already been with a view to determining the existence of any trends that may impact on the future. An historical review of filling practice and research, with special emphasis on Australian experience in particular and worldwide in general over the previous 25 years, will enable me to address the historical and predictive objectives. Controversy can always be achieved by producing a best of list; it can be guaranteed that everyone will disagree with at least one of the nominations. On this occasion, the best contributions by individuals or groups in a number of areas of mine fill technology, over the last 25 years, will be the basis for the nominal awards. The controversy can be increased by posing a number of questions that, hopefully, some of the authors will address during their presentations. I imagine the social functions will be busy enough, but the questions may just add to the cut and thrust of the debate.

Jan 1, 1998

BHP-Utah Coal Limited operates 33 draglines of varying sizes in the Bowen Basin of Central Queensland. The group's operations with draglines commenced in 1963 with the establishment of opencut operations at the then TPM Moura Mine and continued through expansion of that mine, the commissioning of the Utah Development Company Blackwater Mine in 1968, and the subsequent establishment of six (6) other large opencut mines, all in the general area over the next fourteen years. These operations generally commenced with boxcuts on the sub-crop at depths of 15 to 25 metres. Over the years, depths have increased so that average depths now are in the 45 to 50m range. It was soon realised that dragline operations would have to be supplemented with additional stripping equipment. In 1981, a symposium "45m and Beyond" was held in Rockhampton to assess the problems associated with such "deep" stripping. Subsequently, dragline operations have continued and although addi- tional stripping capacity has been added, in many instances, draglines have been used and are being used to dig depths greater than 45m, some- times as much as 65 to 70m.

Jan 1, 1989

By R Symes

The Fosterville Goldmine in Victoria Australia employs the BIOX« Process to liberate gold from its sulfidic flotation concentrate through bacterial oxidation. Gold occurrence is primarily as submicron particles in pyrite and arsenopyrite and has been described as being in æsolid solutionÆ and therefore not amenable to direct cyanidation. Once liberated by the oxidation process, the gold is then available for cyanide leaching. During the oxidation process it has been found that a portion of the liberated gold becomes suspended in the liquid phase in what appears to be a colloidal state. This liquid becomes a waste stream during washing of the oxidised solids and the suspended gold is therefore lost. A method was previously developed using an addition of quebracho tannin to significantly reduce this loss by formation of an iron-tannin precipitate which captures the gold which then reports to the cyanide leach circuit with the oxidised concentrate solids onto which it is adsorbed.This paper discusses the development and plant trial of a second processing step to further enhance gold recovery by use of flotation tailings essentially as a source of extra surface area to capture residual tannin-iron precipitate and its associated gold not recovered in the first step.CITATION:Symes, R, 2012. Recovery of colloidal gold from oxidised concentrate wash liquor - Further improvement, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 383-388 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By B K. Da, S A. Balaji, G P. Roy, T K. Dutta

The raw material handling complex at the Durgapur steel plant provides iron ore, crushed coke and flux to two sinter plants. Either some facilities were not envisaged or not properly designed before the project stage which caused problems during operation of the plant. The absence of an in situ roll turning facility, used to increase maintenance activities for disassembly, transportation of rolls to central machine shop and assembly of rolls, led to decreased crusher availability and increased activities for the maintenance crew. The provision of a smaller vibro feeder/screen in place of a suitable sized screen caused jamming of the screen deck, adversely affecting screening efficiency and the crushing index of crushed coke. Some design modifications and developmental work was undertaken, such as the development and installation of an in situ roll turning facility in the existing limited space, achieving low feed (0.1 - 0.2 mm/rev), lower cutting speed of 30 - 40 m/minute for 350 BHN hard roll, which was also a difficult engineering challenge to bring within the tolerable limit of vibration. This was successfully achieved. Modifications to the screen deck, introduction of differential speed crushing and modification to the vibro screen and vibro feeder for uniform distribution of feed have been incorporated. These innovative design modifications to the in situ roll turning have led to a drastic decrease in maintenance activities and an improvement in the crushing index. Modifications to the screen have resulted in the elimination of jamming and improved screening. Modifications to the vibro screen before the primary crushers and to the vibro feeder before the secondary crushers have prevented excessive wear in the central portion of rolls, ultimately leading to increased roll life. Incorporation of differential speed crushing has resulted in an increased crushing index and decreased generation of micro fines. All the above modifications have led to distinct improvements in equipment availability, increased roll life and a decrease in maintenance activities and improvement in crushed coke granulametry, ultimately resulting in improved productivity and quality of iron ore agglomeration at the sinter plant. The innovative design modifications mentioned above are discussed in detail in this paper.

Jan 1, 2005

By L R. Sousa, M He

Rock burst is common in deep underground excavations and is characterised by a violent ejection of block rocks from excavation walls. It is critical to understand the phenomenon of rock burst and particularly the failure mechanism. Laboratory experiments are one of the ways. For that purpose, a rock burst laboratory test system was developed at the State Key Laboratory for Geomechanics and Deep Underground Engineering at the China University of Mining and Technology, Beijing. A true triaxial test system, designated the Deep Underground Rock Burst Analogue Test Machine, was developed, which can transfer a stress state from three-direction-compression on six surfaces to the compression on five surfaces with one set free. The rock burst experimental system comprises an acquisition of acoustic emission signals, a high-speed recording in order to accurately record the kinetic characteristics of rock fragments ejected during a rock burst event and the possibility of infrared thermography showing the surface temperature of the samples. In this paper, analyses of typical results from rock burst tests are presented with a description of the obtained results. The mechanisms of rock burst are illustrated, and a rock burst classification is proposed based on these laboratory tests. For the control of rock burst, the constant resistance, large deformation (CRLD) bolt or anchor is presented for accommodating the large displacement of surrounding rock masses and absorbing the impact of the sudden release of rock burst while outputting a constant resistant force in response to the external load. The CRLD bolt or anchor has had practical applications in underground mines. Finally, in situ tests performed in a tunnel at Qingshui coalmine, China, are analysed in detail.CITATION:He, M and Sousa, L R, 2014. Experiments on rock burst and its control, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 19–32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By S Natsui, Y Goto, S Kawanishi, J Takahashi, H Nogami

The demand for copper increases yearly, and further improvements in copper smelting efficiency using flash furnaces are required. This study was conducted to understand and promote the interfacial reaction associated with the collision of silica flux and iron oxide particles, ie the formation reaction of fayalite slag, in the reaction shaft of the flash furnace. High-temperature microscopy was used to observe the reaction behaviour of a 2 mm granular SiO2 reagent in contact with micrometreorder- sized FeO reagents in situ. When the amount of FeO was lower than the stoichiometric amount with SiO2, the molten slag formed at the interface between FeO and SiO2 diffused into the SiO2 particle before dissolving the remaining FeO particles. It did not contribute to the subsequent reaction, and despite having the lowest amount of FeO among the samples in this study, many unreacted FeO particles remained on the surface of the samples after testing. On the other hand, under conditions with high FeO content and close to the eutectic composition of the FeO-SiO2 system, a liquid phase formed from low temperatures, gradually increasing in volume and eventually completely dissolving the 2 mm SiO2 grain. These results indicate that the early-stage slag is essential in increasing the interfacial area between FeO and SiO2 and facilitating the supply of FeO to SiO2. In other words, the FeO/SiO2 determines the amount of liquid phase and significantly influences the subsequent interfacial reaction rate between FeO and SiO2. Therefore, the local FeO/SiO2 of the particles falling down the reaction shaft should also be optimised to ensure early slag formation. Meanwhile, the time required for 2 mm SiO2 to complete the reaction for the temperature history employed in this study was significantly longer than the particle residence time in the reaction shaft. Further detailed investigation of the effects of silica flux particle size, composition, and reaction temperature on the reaction time will help find the conditions under which the reaction of silica flux can be completed in the reaction shaft. These kinetic approaches could contribute to future innovations in the copper smelting process using flash furnaces.

Jun 19, 2024

By R A. Medower

This paper provides a glimpse into the future of minerals processing with emphasis on æAutomation InnovationsÆ for the new millennium, particularly those involving advanced process control and innovative new applications of process control technology in 2007.

Jan 1, 2000

By B Rouvray, R Bertuzzi

The development of a design-and-construct tunnelling project in Australia from its concept to its construction requires designs to be prepared and reviewed at several distinct stages prior to documenting ‘for construction’. On recent projects the post-tender stages have been variously called 30 per cent—70 per cent—100 per cent; or concept–substantial–final; or system definition–preliminary–critical. The design is reviewed at each stage by the designer’s internal reviewer, the contractor and its independent advisor(s), the owner and its independent advisor(s), the project’s independent certifier, proof engineers and often third-party stakeholders and their advisors. Documentation for each stage often dominates the design effort, at times distracting from design. This paper presents the authors’ experience of this design-and-review process. Comparisons of design budget and actual design spend and design program implications are presented. It is postulated that a subtle change has occurred in our industry that has diminished the value of the design dollar. Is there a better process? An alternative is suggested.CITATION:Bertuzzi, R and Rouvray, B, 2014. Reducing the cost of tunnel design in Australia, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 501–506 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

This paper attempts to draw together the experience of over 30 years of research and practice in the United Kingdom on the rehabilitation of abandoned metalliferous mining wastes. The reliance on water when the mines were operating has implications for water quality and the techniques used to restore sites to alleviate the principal impacts of the mines. Drivers of reclamation included concerns about human health from wind blown dust and pollution of watercourses as well as perceptions of dereliction. Techniques of reclamation used involved removal of spoil from near to surface watercourses, capping of spoil, diversion of watercourses, use of impermeable membranes, prevention of surface sinks into underground workings and the use of constructed wetlands. The issues to be dealt with in mine reclamation have become more complex and sometimes diverge. The schemes in the 1990s described have been effective in dealing with pollution from spoil heaps and small but significant adit discharges; however, significant issues, particularly those of large flows of polluted water from mine sites, still need to be dealt with. Although the paper describes the legacy of mining, which largely finished in the late 19th/early 20th century, similar issues but on a larger scale are to be found in more recent mining, for example Eastern Europe. In many of these areas minerals still remain to be won and dealing with this legacy may fall on new mining developments.

Jan 1, 2006

By R Castedo, P Segarra, I del Castillo, L M. López, J A. Sanchidrián

This work investigates some suggested methods for blast vibration monitoring on a hard surface based on 53 tests on a vibration exciter. Errors in the measurement attributable to coupling have been described as function of frequency by the rock-to-mount (or coupling) transmissibility, ie ratio of the velocity of the vibration sensor mount to the velocity of the rock motion. Transmissibility has been measured from 2 to 200 Hz, at two vibration levels (5 and 20 mm/s), in four seismographs. Attachment methods with an anchor, thermal adhesive and gypsum plaster allow stiff rock-to-mount coupling. They ensure accurate measurements (errors below 0.3 dB) for frequencies commonly found in blasting (below 100 Hz) irrespective of the mount characteristics and the vibration level. Free laid mounts and sandbagged vibration sensors lead generally to a poor, weak coupling. Errors are non-linear errors with the input velocity, ie the operating frequency window narrows as the velocity of the ground increases. Free mounts follow ground motion acceptably well (error up to 0.4 dB) at both vibration levels and frequencies below 15 Hz. At higher frequencies, free mounts lead to the largest distortions with expected errors ranging from 0.8 to 6.6 dB. Sandbagging limits the expected errors below 1.3 dB, but it does not prevent large errors that can be up to 4.5 dB. Both frequency and velocity should be considered together to assess the measurement errors instead of the expected accelerations, as it is currently made.CITATION:Segarra, P, Sanchidrián, J A, Castedo, R, López, L M and del Castillo, I, 2015. Effect of vibration sensor mounting method on the quality of vibration measurements, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 545–552 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By P Yß±ez, G Ferguson

The El Teniente mine produces more than 340 000 tonnes of fine copper per year from an industrial complex of underground mine, concentrator and smelter. Mass caving methods are employed to deliver approximately 95 000 tpd of ore to the mill, from a number of sectors underground, each sector being in effect a large-scale mine in its own right. This mining activity has faced challenges over the course of the last century such as:the capacity of the underground mine has been expanded to maintain and increase output of fine copper; the increasing size of the ore fragmentation forced to change the mining method to achieve the high productivity and profitability required in the business; and to modify the mining methods to continue mining at depth with safety. Fundamental activities in these mining methods, for the successful initiation of caving and subsequent draw, are:undercutting the base of the block or panel by blasting; and excavating of drawbells. The undercutting design evolves mainly on the height of the blasting to manage the change on ore fragmentation. The methodology move away from incorporating massive areas, typical of the block caving method, to a continuos blasting, typical of the panel caving method. Drawbell design changes on geometry, dimensions and sequence of excavation to deal with a corse ore fragmentation and the resolution of mining difficulties in the form of major rock bursts and collapses of production facilities. This paper focuses upon the evolution of the undercutting and drawbell design used at El Teniente mine and techniques under consideration to deal with future caving operations to provide the bulk of the daily production for the foreseeable future.

Jan 1, 2000

This paper will review some of the work conducted in the past at the Dynamic Effects Laboratory to examine the use of stress waves and fracture mechanics in understanding dynamic fracture and fragmentation in blasting applications. Along the way, we will use photoelasticity and high-speed photography to better understand the mechanisms of fracture and fragmentation.CITATION:Fourney, W L, 2015. The role of stress waves and fracture mechanics in fragmentation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 27–40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By A T. Bernardes

Using the cellular automata computational technique it was possible to simulate the generation and discharge of an iron ore pellet pile inside a direct iron reduction oven, as well as to calculate the reduction degree of the pellets as they leave the oven. It allows simulation of the variation of operational parameters and verify the results of those variations in the pellet reduction degree. The simulated data was validated in two instances: for the dynamics of the pellet flow inside the oven it was used in an acrylic bi-dimensional silo; and data from direct reduction iron literature was used for validation of the pellet reduction. The simulated results were considered acceptable to describe the movement of the iron pellet inside the direct reduction iron oven and to describe the iron pellet reduction direct in the oven.

Sep 26, 2011

By P Fines, D J. Williams, G W, S Miller

This paper presents the results and findings of geochemical and mineralogical testwork conducted on samples collected from waste rock dumps at two mine sites, located in South Carolina, USA (Site 1) and Sudbury Ontario, Canada (Site 2). Important aspects of the relationship between the physical and geochemical aspects of the dumps are also presented. The overall aims of the project were to 1. determine if the physical and hydrological nature of the waste-rock dumps had any impact on the geochemical and mineralogical characteristics of the dump materials; and 2. to identify key implications for dump construction for ARD control. The results of geochemical and mineralogical tests indicate that the waste rock at Site 1 had undergone significant in-dump weathering and was relatively advanced with respect to ARD evolution. In contrast, the waste rock at Site 2 had undergone some weathering, however still contained a considerable amount of sulfide minerals. Testing also suggested that flushing of oxidation products at Site 2 had been limited, which therefore promoted the storage of oxidation products at the site. In addition, materials that had a D50 particle size in the range of 5 mm to 30 mm appeared to be more readily flushed than samples that had a D50 particle size of 30 mm. This suggested that preferential water pathways may have developed within the dumps at both sites.

Jan 1, 2003

As a result of high fuel prices and substantial haul distances or vertical lift from pits, the development of large inpit crushing and conveying systems at many open pit operations has occurred over the last decade.The basic criteria that has to be met is that the material is reduced in size to be conveyable. Generally this requires a top size of less than 300 mm.

Jan 1, 1992

Safety bulletins and stickers issued for the paste backfill plant at Cannington read as follows: æCannington Paste Fill Plant, First of ItÆs Kind in AustraliaÆ. We could even dare to state that the Cannington plant is different than any other paste backfill plant in the world because of the overall design, plant equipment and underground delivery. However, one thing to be certain of is, the paste backfill plant works as designed and a pump is not required to deliver paste underground given the general plant arrangement at Cannington. The past two years have been a process of evolution to design and construct the plant and make it work. This paper will describe the paste process using full mill tails along with placement of cemented paste underground. Discussions will include rationale of fixed plant selection along with various control requirements. BHP World Minerals recently commissioned its paste backfill plant in December 1997. Cannington is placing full mill tails underground via two surface boreholes that deliver either to primary or secondary stopes.

Jan 1, 1998

By Adeloju S, McQuade CV, Riley SJ

Metal contamination of sediments can be an issue for minesites discharging water. Water sampling of receiving waters is frequently undertaken. Sampling and analysis of sediment is less common. The variability of receiving environments makes the formulation of a generic sediment sampling strategy virtually impossible. Each situation needs to be carefully assessed before sampling is undertaken. This paper outlines the approach taken for one such survey.The main factors that need to be considered in a survey of surficial sediments are sample representativeness and sample variability. A simple data set from one site within a regional survey is used to illustrate the importance of these factors. The metal content of sediment is shown to vary significantly over small spatial scales.The variability associated with the spatial distribution of samples within a site is shown to be the most significant source of variability in the study. This variability could bias the results of a study if not planned for in the sampling methodology. Taking multiple samples from within each site (sub-site samples) and combining the data gives a more representative indicator of overall conditions than a single sample. The optimum number of sub-site samples to be taken from each sampling site was found to be 15.It is shown that a composite of sub-site samples can give a good indication of the average site metal content, while considerably reducing the sample preparation and analysis effort.

Jan 1, 1998

By A Salama, J Greberg, B Skawina

In today’s underground mass mining, the orepass is an important part of the infrastructure as it connects two or more mine levels and is used for conveying or storing large amounts of material. One of the main risks related to an orepass is when operational or structural failure occurs, leading to long-term loss of functionality. Developing or rehabilitating an orepass when major failure has occurred is a time-consuming and expensive operation, and the risk of a long-term orepass loss motivates the development of alternative transportation strategies to ensure the continuation of smooth operations in large underground systems. The study presented in this paper has been done at the Loussavaara Kiirunavaara AB Malmberget mine in Sweden, where iron ore deposits are being extracted using sublevel caving. The study analyses the transportation system in one of the mine’s orebodies using discrete event simulation, with a focus on maintaining ore transportation in the event of the loss of an orepass.CITATION:Skawina, B, Greberg, J, Jonsson, K and Salama, A, 2016. Orepass loss mitigation approach in Malmberget mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 617–622 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016