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By J Knoblauch, D, P J. J Strobos, C Foggo

The Sally Malay Project is located 120 km north of Halls Creek in the eastern Kimberley region. Since commissioning, ongoing improvements on the plant have resulted in recoveries now greatly exceeding the initial design targets. The continual optimisation endeavours of the Sally Malay metallurgy department included an automation project that was done in close collaboration with Mintek. In this team effort, several problem areas were addressed and the FloatStar advance control system was successfully commissioned to stabilise and optimise the flotation circuit. The remote location of the Kimberley Nickel Mines operation, fly-in, fly-out roster and the current mining boom makes the acquisition of experienced flotation staff difficult. The implementation of an automated flotation control system reduces this burden and contributes to the training of inexperienced staff. This paper illustrates not only the process control improvements achieved as a result of the installation of the FloatStarÖ advanced control system, but also how it has assisted operational personnel with their understanding of the process.

Jan 1, 2006

By J J. Cilliers, K Hadler

Air is fundamental to flotation; not only is it required to collect the valuable particles, but it also controls the froth stability and consequently the separation performance for a given feed. Froth stability can be described and quantified in numerous ways, which are subtly different. Air recovery is one such measure of froth stability which accounts for both the stability of the bubbles and the mobility of the froth. The benefit of using air recovery as a measure of froth stability is that it exhibits a peak as air flow rate is increased, and this corresponds to the air rate at which the optimal separation performance is obtained. As such, it provides a single target value for optimising air flowrate for a given set of feed conditions. Use of air recovery, however, has one potential drawback: accurate measurement of the inlet air flow rate to a flotation cell is required. This can be problematic for operations, particularly where calibration of air flow rate is carried out infrequently or where there is no air flow rate measurement, such as for many self-aerated flotation cells. To this end, we present an alternative method for determining the peak in air recovery (PAR) air rate.We introduce a simplified method for determining the PAR air rate using trends in froth velocity and overflowing froth height, both of which are readily measured using existing froth image analysis systems. We will show, using industrial data, the application of this simple technique to find the optimal air flowrate for flotation cells. We will also discuss other alternative techniques for air rate optimisation that have the potential to improve separation performance using existing technology.CITATION:Hadler, K and Cilliers, J J, 2018. How to find the optimum air rate for flotation cells, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 377–384 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By T Purvis, Z Liu

Ernest Henry mine (EHM) is an underground sublevel caving mine located in north-west Queensland with a production rate of 6.4 Mt/a. The mine has sublevels spaced with a 25 m vertical interval. The production process on each level starts with the drilling and firing of a blind uphole rise to start the slot extraction. These rises are fired as a single shot and routinely need to achieve a design height of 22 m to 30 m depending on the local mine geometry. If the rise fails to perform as designed then the production phase of the level is delayed with significant rework required to remedy the situation.This paper describes the process that the EHM team has followed to improve the first time performance of each rise. The improvement process commenced with a review of results from previous rises and resulted in the identification of a number of improvement opportunities. A revised holistic approach was established for the process, which included involvement from operators and engineers. Through continued measurement and review of rise performance, inputs to the process were improved to a point where reliable results can now be expected. The successful performance of subsequent rises has been verified through a comprehensive quality assurance quality control (QA/QC) program. Before quality control processes were implemented, the success rate of blind uphole rises was only 11 per cent (one out of nine rises) at EHM. In comparison, the success rates have been vastly improved to 25 per cent (one out of four) and 75 per cent (three out of four) respectively following two stages of improvements. This paper concludes with the ‘current’ series of best practices used at EHM and recommendations.CITATION:Purvis, T and Liu, Z, 2017. Improving the performance of blind uphole rises at Ernest Henry Mine – a case study, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By A K. Raina, V M. S R Murthy

Rock mass response in blasting is an important element to determine the performance of a blast along with its other outcomes. The near-field monitoring for rock mass response analysis is vital for determining the behaviour of a blast; however, due to costly and cumbersome methods involved in such measurements the subject has received scant attention so far and the publications on this account are perfunctory in nature. This paper presents a non-destructive method to monitor the blast-induced pressure in the rock mass at a distance from a blasthole. The methodology of monitoring and a few examples of actual field monitoring are detailed in this paper. The responses of the rock in the near-field of a blasthole under dynamic loading have been documented to predict fragmentation and throw. The proposed method has also been used in limited cases earlier by the author to predict flyrock using a semi-empirical method and trajectory equation. The pros and cons of the method are discussed while throwing light on the actual response and the prediction of fragmentation and throw of blasted rock.CITATION:Raina, A K and Murthy, V M S R, 2015. Measurement of blast-induced pressure in bench blasting and deciphering explosive performance through rock mass response analysis – a methodology, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 501–508 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Grossi M, Baiden G

This paper describes a new mine backfill method based on a newly invented binder with several years of test results from laboratory and on- site applications. The new binder has several advantages over traditional Portland and slag cement binders. One tonne of the new binder can replace two to three tonne of Portland cement when used to consolidate backfill and can result in the same compressive strength within seven days. When comparing backfill slurries of the same pulp density, the new binder attains more volume of in-place backfill mass than Portland cement because of the high crystallisation of water, resulting in tightly filled stopes. The crystallisation of the water provides for less or no de- watering in the backfill stope and easier transportation of the backfill slurry. Pastefill performance can be achieved by using pulp densities typical of a hydraulic backfill and the new binder, all the while transporting with the same ease of hydraulic fill.

Jan 1, 1998

By M Saghaeian, A H. Baladastian, A Dehghani Ahmadabadi, V Sheikhzadeh, R Hejazi

With the declining of high-quality hematite and magnetite iron ore reserves and the increasing accumulation of material resulting from mining and beneficiation operations that appear as lowquality depots and discharged materials in tailing dams, the necessity of recycling these reserves is increasingly becoming a critical demand. The Chadormalu iron ore mine is among the largest deposits of magnetite-hematite iron ore in Iran. In this mine, the total wet processing tails accumulated in tailing dams are over 92 Mt containing 25–40 per cent Fe. Laboratory and pilot tests on tailing samples led to the design and implementation of the Chadormalu Tailing Recovery plant (CTR) with a unique process circuit in Iran. In the CTR plant, after three steps of re-pulping with spiral classifiers and sanding machines, the underflow is concentrated by two stages of WMIMS and produces 64 per cent Fe grade magnetite concentrate. The tailings of the drums are mixed together and introduced into the hematite recovery section, including two stages of VPHGMS separators, and 60 per cent Fe grade hematite concentrate is produced. This plant has been in operation for over ten years with a total yield of 18.93 per cent. Due to changes in the materials extracted through new tailing dams, the quality of the final concentrate dramatically dropped to 56.36 per cent Fe and 0.79 per cent P; therefore, applying reverse flotation and removing phosphorus from the final concentrate was inevitable. By using this approach, upgrading of the concentrate to 63.01 per cent Fe and 0.05 per cent P was obtained. Furthermore, regarding the high amount of phosphorus in the tailing streams, direct flotation has been designed to produce apatite concentrate as a by-product stream through a flotation system comprising series banks of Rougher, Cleaner, and Re-Cleaners flotation cells. Hence based on the results, at optimum conditions, a final apatite concentrate with a yield of 15.78 per cent and 14.06 per cent P could be achieved. Successful implementation of this project has led to the production of magnetite-hematite and apatite concentrates with annual capacities of 250 000 and 45 000 t, together with total yields of 11.59 per cent and 6.19 per cent (includes de-sliming of apatite flotation feed), respectively.

Aug 24, 2022

By A Kondratiev, A E. Moiseev

Viscosity of oxide melts is one of the fundamental physicochemical properties that plays a crucial role in important technological and natural processes like slag flow, slag/metal separation, volcano eruptions etc. However, many oxides melt at extremely high temperatures and are highly corrosive in the liquid state, which makes experimental measurement of melt viscosity by traditional experimental techniques a difficult and expensive, if not unachievable, task. In this case it might be useful to employ other methods of viscosity determination such as modelling or simulation. In the present paper the shear viscosity coefficients of selected pure refractory oxides (CaO, MgO, Al2O3 and others) have been simulated at temperatures above their melting points via the classical molecular dynamics and compared to the available viscosity data (eg experimental viscosities, other model predictions) collected by the authors. The simulation has been carried out using the noncommercial molecular dynamics simulation package LAMMPS and the Born-Mayer-Huggins potential, which parameters for the selected oxides were taken from the literature. Several viscosity calculation techniques (the Stokes-Einstein and Green-Kubo equations, the so called Einstein relations, and the non-equilibrium molecular dynamics methods) have been applied to ensure a more reliable viscosity calculation. It has been demonstrated that the simulated viscosity of the selected melts agrees with the available experimental data. It has also been shown that the simulated viscosity of a number of the oxide melts investigated is close to that calculated by phenomenological viscosity models, which supports viscosity extrapolation from the corresponding binaries and ternaries, if no experimental data is present for unary systems. In general, it has been demonstrated that the molecular dynamics simulation could provide a reasonable estimation of viscosity if no other viscosity data is available.

Jun 19, 2024

In this paper, three types of value-adding in the minerals industry are discussed: downstream processing, improving the efficiency of existing processing and increasing the knowledge base and expertise of the staff. It is shown that, while downstream processing seems to offer a good way of improving Australia's trade position, there are a number of impediments to such development, notably, limited access to the appropriate technology and overseas markets. Transport costs can also be a problem. To reverse the situation will require more positive policies by government. In the meantime, something can be done towards adding value by increasing the efficiency of existing processes. Examples are given, showing how it might be possible to make economies in reagent costs in the gold industry, how innovative technology has led to more complete processing of a tailings dump, how research might lead to an increase in the throughput in the production of synthetic rutile and how it is possible to leach selectively from gold/copper ores.

Jan 1, 1995

By J Siliézar

The Ernest Henry Mine (EHM) is situated 38 km north-east of Cloncurry in the Mount Isa – Cloncurry mineral district of northwest Queensland. The EHM orebody is an iron oxide copper gold deposit with an average grade of one per cent copper, 0.5 g/t gold and 23 per cent magnetite, with current reserves of approximately 88 Mt.The copper concentrator is a single line plant with a nominal throughput rate of 1300 tonnes per hour. An average of 350 000 tonnes of concentrate is produced each year containing around 100 000 tonnes of copper metal and 120 000 troy ounces of gold.In December 2009, Xstrata Copper announced approval of a $589 M investment to extend the life of EHM to at least 2024, through the transformation of open pit mining operations to a major underground mine together with the construction of an associated magnetite extraction plant.The EHM magnetite plant extracts the magnetite from the copper concentrator’s tailings stream. It will produce approximately 1.2 Mt of magnetite concentrate per annum at full capacity for export to Asia, making EHM Queensland’s first iron ore concentrate exporter. Construction of the magnetite extraction plant commenced in July 2010 and was completed in January 2011.This paper gives an overview of the development of the EHM magnetite extraction plant flow sheet from the early mineralogy and laboratory test work through to the plant commissioning and early operation of the base plant. It has a major focus on the commissioning learnings from the plant start-up and includes a review of the operational performance of the plant versus original design and expectations.

Jul 11, 2011

By G Lumley

PlannersÆ optimism (or maybe commercial necessity) means that most mine plans use equipment rates that are rarely achieved (Lumley and Beckman, 2009). This lack of understanding of what equipment actually moves is causing erroneous equipment forecasts, leading to incorrect mine development plans and economic evaluations. Compounding this problem is a downward trend in actual equipment performance in some areas. Consequently, the presentation of realistic mine plans that are actually achieved in practice is not a common occurrence. However, rational, fact-based mine planning is available to those who want it. Hundreds of millions of cycles of data from open cut mining equipment has been collected from mines around the world since 1992. This unique and highly valuable databank is growing at an exponential rate and is being used by a number of our big miners to support rational and fact-based decision-making. However, neither the use nor the appreciation of the value of this data is universal. There is a challenge to everyone in the mining industry - how do you access value from it? The databank was drilled into and the results analysed for, the Australasian Mining and Metallurgical Operating Practices (AMMOP) publication (Lumley, in press). For this paper the analysis has been extended to include interpretation of trends for draglines, shovels, excavators and trucks. It investigates trends between coal and non-coal mines and across geographic areas. It is known that mining equipment performance in most sections of the industry is falling. This paper attempts to quantify the fall and provide explanations. The trends are analysed to extract the reasons behind the changes and most importantly, what can be done about it.CITATION:Lumley, G, 2012. Understanding trends in performance of open cut mining equipment, in Proceedings Project Evaluation 2012 , pp 203-224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By A N. Danoucaras, S E. Goater, D Hearne, A M. Bansuan

It is globally recognised that existing and emerging mining activities should be conducted in a æsustainableÆ manner for the entire life of mine. Many companies annually publish corporate sustainability reports to demonstrate their actions in accordance with international expectations. This concept of sustainable mining practices also applies to mine water management, with influences often extending beyond site operations, affecting surrounding catchments and community users. This paper explores differences in conceptual and operational terms of æsustainableÆ mine water management within the Philippines. Outcomes of a review of corporate sustainability reports, governance documentation, research programs, and stakeholder knowledge acquired through action-research workshops are presented. The paper aims to inform and support future capacity building exercises delivered by the International Mining for Development Centre (IM4DC), with outcomes tailored to government officials and policy makers of developing countries. The project is funded by IM4DC, which is working with AusAID to identify needs and develop capacity with regard to mining for development; specifically, issues pertaining to governance and regulation, social and environmental sustainability, and operational effectiveness in developing countries.CITATION:Bansuan, A M, Goater, S E, Danoucaras, A N and Hearne, D, 2012. Integrated sustainable water management in mining for development in the Philippines, in Proceedings International Mine Management 2012, pp 205-226 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By M Edwards

The paper outlines the successful application of some of the on-belt technologies available from Scantech International Pty Ltd and how these have provided benefits in a number of mining and mineral processing operations. Effective process control requires real time analysis so quality can be fed back to the previous process and fed forward to a subsequent process. A range of on-belt analysers that allows for full stream, continuous, non-contact analysis of conveyed materials is available to achieve this. Real time results can provide timely information for effective process control. Benefits of on-belt analysis systems become more evident once the true variability of material quality and moisture content in conveyed flows is measured. To obtain economies of scale in mineral processing operations large material flows are achieved using conveyors. The cost and effort to sample representatively increases as conveyor flows increase. One sample may represent a few tonnes or up to 10 000 tonnes of material. The turnaround time between sampling and availability of sample analysis data does not allow real time process control. Tonnage flow rate, moisture content and elemental or mineralogical composition are required to perform effective process control of most conveyed streams. Tonnages can be effectively measured using belt weighers. The analyses derived from small samples supplied by conveyor-based sampling systems contain high variability. On-belt, continuous analysers see all the material and, through short term compositing of analyses, supply less variable results. Real time analysis helps operators develop a better understanding of material variability. Analysers can be effectively utilised to improve the consistency of product quality through bulk sorting and blending control. Many existing users of the technologies have gained competitive advantages through their ability to supply a more consistent quality product to the market.

Jan 1, 2008

By D J. Williams, S Islam

Fine-grained coal tailings slurry undergoes only limited settling and self-weight consolidation, and tends to remain slurry-like and unsuitable for conventional laboratory consolidation testing. In addition, constant rate of loading consolidation testing is more representative of the continuous disposal of tailings slurry into a tailings storage facility (TSF) than conventional step loading. The laboratory consolidation testing of coal tailings slurry under a constant rate of loading has been carried out in a purpose-built, large-scale, slurry consolidometer, instrumented with load cells and pore water pressure (PWP) transducers. In the slurry consolidometer, the rate of loading may be varied to represent the actual rate of rise of the tailings in the TSF. A slow rate of loading increases the test duration, while too fast a rate of loading may build up very high excess PWP, without achieving significant consolidation. For the particular fine-grained coal tailings slurry tested, the rate of loading in the slurry consolidometer is varied to access its effect on the development and dissipation of excess PWP. The resulting consolidation parameters are evaluated and explained using the recorded settlement and PWP data.CITATION:Islam, S and Williams, D J, 2018. Optimisation of constant rate of loading slurry consolidometer testing of fine-grained coal tailings, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 72–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By J Li, H Hooi, D Payne

Caval Ridge Mine (CVM) is one of the newly established open-cut coal mines of BHP in Queensland, where no tailings dam is planned to be built in order to minimise environmental impacts from mining activities. The waste streams from the Coal Handling and Processing Plant, including fine tailings dewatered by belt filter presses, coarse rejects, and mixed plant rejects, are co-disposed within waste dumps built with pre-strip and dragline spoils. Due to high rejects output (35 – 60% of feed) and low spoil to reject ratio (< 5) the large quantities of rejects bring significant geotechnical and operational challenges to CVM, which are exacerbated by increasing annual production rates and additional rejects from washing coal from an adjacent mine. Further in-house geotechnical review commenced in mid-2014 based on the initial geotechnical studies during the project stage of CVM between 2011 and 2013. The outcomes have enabled rejects disposal at CVM by constructing large belt filtered tailings cells, coarse rejects only dumps, and co-disposal of the mixed plant rejects at dump tip-heads. This paper presents the rejects disposal strategies at CVM from both technical and operational aspects. It also discusses future projects for belt filtered tailings moisture reduction including assessment of tailings clay mineralogy, as well as mixed plant reject co-disposal verification and optimisation.CITATION:Li, J, Payne, D and Hooi, H, 2018. Plant rejects disposal strategies applied at Caval Ridge open cut coal mine, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 50–60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By D Mather, H R. Asche

"In the civil tunnelling field, the use of tunnel boring machines (TBM) has now overtaken the use of conventional excavation methods (drill and blast / roadheader). This is due to a number of reasons, including the increasing availability and reliability of TBMs, the ability to deal with a wider range of face conditions, and the reduced excavation cost that TBMs can bring.Mining companies have spearheaded the advances in shaft boring by mechanised means, both in blind and raise boring. However, mining companies have been slower to adopt mechanised tunnelling.When contrasted with a conventional mining contract, there are good reasons why TBMs in mining applications are relatively rare. A conventional decline contract may have very little geotechnical information. The decline alignment can be subject to change as the tunnelling progresses. The infrastructure requirements are less for a conventional decline, and the sunk cost prior to excavation commencing is lower. Contract documents can be very simple.The history of TBM use in mining is reviewed and lessons are described. From the case histories and lessons learnt, the paper identifies ways that mining companies can maximise the potential benefit of TBM technology.We believe that despite the additional requirements for TBM declines, the cost and time advantage to mining companies is very attractive. The challenge is to recognise and to meet the requirements for success in a TBM drive to achieve the advantages of: faster advance rates reduced rock damage/overbreak reduced support requirements uniform muck characteristics greater personnel safety.From the case histories and lessons learnt, the paper identifies ways that mining companies can maximise the potential benefit of TBM technology.CITATION:Asche, H R and Mather, D, 2014. Use of ?tunnel boring machines in the mine environment, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 655–662 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 17, 2014

By T Barto, D Thomson, T Norgate, C Doblin

Collaboration between CSIRO Minerals and SunSalt Pty Ltd, a salt producing company located in rural Victoria, has resulted in a commercial process to recover magnesium sulfate (commonly called Epsom salt) from the saline waters of the Murray Basin. The feed for this process is bittern; the liquor remaining after halite (common salt) has been harvested from the saline water by evaporation.SunSalt produces salt and bitterns from three locations, namely Hattah (Victoria), Mourquong (NSW) and Wakool (NSW). The small size and considerable distances between these operations makes it uneconomic to build a stationary processing plant to extract value-added products, in particular Epsom salt, from the bitterns of the three operations. This fact led SunSalt to build a containerised mobile plant that could be moved to each site to process the bitterns at the end of the salt harvesting period.Epsom salt is extracted from the bittern by further evaporation, refrigeration and recrystallisation. In this process the bittern is diluted with five per cent volume of fresh water to minimise precipitation of residual halite in the bittern. Cooling the diluted bittern to between -5 and -10¦C precipitates up to 70 per cent of the magnesium sulfate, which is recovered as 85 to 96 per cent purity Epsom salt by filtration. This product is marketed as an industrial grade Epsom salt. Higher purity (up to 99.9 per cent) Epsom salt (USP or BP grade refined product) is made from the industrial grade product (raw Epsom salt) by recrystallisation.The containerised mobile plant was commissioned in December 2002. The raw Epsom salt generated in the mobile plant is refined to a higher purity Epsom salt in a separate plant located in Mildura. The Mildura plant was commissioned in December 2003.The CSIRO-SunSalt collaboration has demonstrated that the saline waters can be processed into a useful resource, and in addition could create jobs and a new skill base in regional Australia. The production of Epsom salt locally in Australia, which is worth currently about $A600 per tonne, removes the need to import over 3000 tpa from overseas with a net positive impact of $A2 million on the balance of trade.

Jan 1, 2004

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

By Y Cao, J C. Tien

Occupational health and safety is essential in modern mining workplaces and in China it is often not given enough emphasis due to a lack of knowledge and/or appreciation. Although many health and safety regulations have been passed over the years, serious and relevant laws and regulations on mine health and safety are of recent history (since 2002), the level of stringent enforcement is still inconsistent and accurate field data are scant and not readily available. As of year-end 2006 there were 676 562 recorded cases of occupational diseases in China, of which 616 442 or 91 per cent were miners’ pneumoconiosis. Of these, 146 195 (23 per cent) have died, and an average of 10 000 new cases were added every year between 1991 and 2006. Another report shows that 93.18 per cent of miners have never had a contract with their companies, which means their cases were not even part of China’s official statistics. This study attempts to examine the prevalence of occupational diseases in the Chinese mining industry during 2000–2013, compiled from government annual reports and academic studies. The research will review the correlational analysis among occupational diseases, ventilation practices, protection devices and legislation.CITATION:Cao, Y and Tien, J C, 2015. Occupational diseases in China, with the emphasis on its occurrence in Chinese mine workers, in Proceedings The Australian Mine Ventilation Conference, pp 155–160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By S M. Gover

Estimating the probability of failure for embankments is not intuitive. It requires not only an appreciation of the strength of the embankment, but an understanding of the variability and uncertainty in the strength parameters as well. These additional aspects are, in themselves, relatively new to most practicing engineers, and therefore require some discussion.This paper discusses the concepts of probability and uncertainty, and presents a reliability-based numerical experiment, together with a literary study and collation of some of the author’s historical slope stability analyses, to investigate whether a direct relationship between safety factors and probabilities of failure exists for certain levels of uncertainty in strength parameters. In doing so, a useful tool is presented whereby knowing the safety factor of a simple slope or embankment with a consistent level of uncertainty, one can infer an approximate probability of failure.CITATION:Gover, S M, 2018. Linking safety factor to probability of failure, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 384–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By G M. Evans, C M. Phan

This paper presents an analysis on the dynamic adsorption of frothers and collectors onto air bubbles in flotation. The analysis was carried out using the theory on the surfactant transfer by diffusion and adsorption. The bubble size was considered when solving the diffusion equation for the dynamic surface excess. The adsorption kinetics was modelled employing the Langmuir adsorption isotherm and its extension with the inclusion of the lateral interaction of the adsorbed molecules (the Frumkin adsorption isotherm). The numerical computation was applied to solve the governing equations. The dynamic adsorption of the surfactants was measured in terms of the dynamic surface tension for sodium dodecylbenzene sulfonate (SDBS) and Dowfroth 250, using pendant bubble tensiometry. The results show that for air bubbles with diameter of the order of 1 mm, the bubble size effect on the dynamic surface tension is small and the solution of the diffusion equation for a planar gas-liquid surface can be used to describe the dynamic adsorption onto the air bubbles. The experimental data obtained with SDBS were well described by the Frumkin adsorption isotherm and the molecular diffusion. The model description for the experimental data obtained with Dowfroth 250 required the kinetic equations. The paper is relevant for further analysis of the role of the adsorbed surfactants in the particle collection.

Jan 1, 2005