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By Holly J

The period following World War II has seen many changes in stoping techniques at The Great Boulder Gold Mine. The new methods resulted in improved unit production figures, and have given some relief from the rising worldwide cost spiral in the post war years.Significant production figures are shown graphically in...

Jan 1, 1956

By A Rantala, C Cruickshank, I Muzinda, O Haavisto, J Timperi

The production at First Quantum Minerals’ (FQM) Kevitsa Mine, located in northern Finland, commenced during the second quarter of 2012. Presently, the mine processes approximately five and half million tonnes of ore annually, producing nickel, copper and platinum group metal (PGM) concentrates. In order to support fast production ramp-up and optimise the performance of flotation thereafter, an extensive advanced flotation control solution was implemented by Outotec in collaboration with FQM Kevitsa.In addition to basic process instrumentation and process control, each of the 14 Outotec 300 m3 and another 26 cells, ranging from 20–160 m3, have been equipped with state-of-the-art systems providing froth image analysis and automatic froth speed control. Also, the flotation cell levels are stabilised with advanced feed-forward level control.The online analyser provides key feedback information of the process performance for the advanced process control (APC) system. Based on this information, APC system defines grades and recoveries according to rules defined by Kevitsa process metallurgists. This system executes the control strategies for optimising the production of concentrates.Throughout the implementation and support phases, specific and intensive attention was paid to ensure plant personnel gained full understanding of interacting with the system and how to incorporate their process experience and skills to optimise the APC strategy. This level of expertise is also a valuable asset in understanding the APC system’s contribution to the overall performance of the plant as well as providing the ability and confidence to define key performance indicators used for continuous assessment. The experiences and results from site achieved so far are discussed in this paper.CITATION:Rantala, A, Muzinda, I, Timperi, J, Cruickshank, C and Haavisto, O, 2014. Implementation of advanced flotation control at First Quantum Minerals’ Kevitsa mine, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 369–378 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By S R. Green, G D. Corder

The legacy issues from mining can, and have often, extended well beyond the closure of operations. However, conventional cost-benefit analysis provides little incentive to implement initiatives at the project development stages of a new mining project as the costs that will be incurred towards the end of the mine life, 20 years or longer, appear minor in net present value (NPV) terms. This analysis can be misleading as the true costs of managing post-mining land can continue for many years, or decades, after mining ceases and any resulting unfavourable legacy issues can delay or prevent government permits or licences to develop new resources. Proper upfront planning is critical for implementing successful rehabilitation and closure strategies. The investment in this planning needs to be done in a structured and rigorous manner taking into consideration the long-term and broad benefits of sustainable land uses after mine closure. The advantages of such an approach could include the streamlining of regulatory approvals by early advice to the regulator of identified issues and responses to those issues, and clear evidence that a strong social licence to operate ethic with local, regional and national benefits is included in the decision-making process. This paper investigates the potential closure options for two case studies at the early stages of project development - concept and prefeasibility. By using a sustainability framework that can identify opportunities and risks, prospective initiatives that deliver enhanced environmental, community and social benefits will be compared with compliance-orientated approaches. This comparison is made across the Five Capitals Sustainability Model - natural, human, social, manufactured and financial. The results of this analysis demonstrate that upfront planning during project development and due care and effort during the life of the working mine will reduce the risks of long-term detrimental legacy issues. This will ultimately benefit the mine operator, the local community and the state.CITATION:Corder, G D and Green, S R, 2012. Using a sustainability assessment framework to achieve enhanced legacy outcomes, in Proceedings Life-of-Mine 2012 , pp 311-318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

The Sishen iron-ore-mine produces 3 pro= ducts with size gradings of 25 to 8 mm, 11 to 5 mm and 5 to 0,2 mm and has a product capacity of 20 Mtpa. Ore is produced at an average Fe content of 66,2 % Fe for the two coarser pro= ducts and an average of 65,3 % Fe for the fine ore product. Three stage crushing is practised to re= duce the run-of-mine ore to -90 mm after which it is screened into five different size frac= tions of which four are heavy media beneficiated in static baths and cyclones and the fifth frac= tion discarded to slimes dams. A final three stage crushing and screening process is employed to produce the final three Products which are homogenized by means of blen=ding systems nrinr to despatch.

Jan 1, 1987

By J Cortinez, P Vallejos, J Yianatos, M Rodriguez

Nowadays, one of the main problems in current flotation plants and new projects is the significant decrease in feed grades and changes in the mineral composition, which has an important effect on the mineral liberation and associations. Additionally, flotation plants usually operate with feed throughput higher than the original design, which has a significant impact on the feed particle size. All these conditions affect metallurgical performance, and must be evaluated and addressed, by improving control strategies for banks optimisation. For this purpose, the flotation of valuable minerals along the circuits requires better understanding, considering the compromise between performance and selectivity in flotation circuits. This paper presents a characterisation of the different minerals recovered along industrial flotation circuits. Plant sampling campaigns, performed in a copper industrial concentrator in Chile, provided the data for the study. Two rougher flotation banks consisting of cells of 130 m3 and 300 m3 were analysed. All the samples from the industrial surveys were analysed by screening and mineralogy, and the mineral recovery along the circuits was evaluated per particle size class, liberation class, type of associations, and others. Additionally, operating data on froth depth profiles complemented the evaluation of the mineral composition of concentrate streams, along the circuit. The results allowed for identifying and quantifying the main factors that affect the copper recovery and concentrate grade along the flotation banks. It was found that minerals with liberation lower than 50 per cent have a significant impact on the recovery. On the other hand, the decrease in the Cu grade in concentrates along the flotation circuits is mainly due to the relative increase of middling minerals (less liberated), non-valuable floatable minerals, such as free pyrite, and gangue entrainment. The characterisation of the gangue entrainment flow rate along the flotation banks showed a strong relationship with froth depth, which becomes more critical towards the last cells of the banks.

Aug 24, 2022

By T Trott, M Lewis, G Lumley

The analysis of equipment trends in The AusIMMÆs revision of Monograph 19 - Australasian Mining and Metallurgical Operating Practices (AMMOP) (in prep) in the paper by Graham Lumley raised some interesting, and in parts disturbing, trends in the Australian open cut mining industry. According to the Australian Bureau of Statistics (2011) the productivity of the whole mining industry is down by 34 per cent since 2001. In terms of open cut equipment, median output for draglines is down by 15 per cent since 2003, electric rope shovels are down by 41 per cent since 2003, hydraulic excavators are down by 39 per cent since 2008, front-end loaders are down by 39 per cent since 2007 and trucks are down by 41 per cent since 2006. Clearly e boom has not been good for the efficiency of the mines. During this same time, best practice (defined as the average of the top ten per cent by annual output per unit of input) has declined, but not by as much as the median (eg shovels down by eight per cent, excavators down by 19 per cent and FELs down by five per cent). This paper will build on the analysis of AMMOP to understand the differences occurring between median and best practice and identify the factors contributing to the decline in performance. As the industry enters a period of potentially lower prices for commodities and reduced margins, pressure will be brought to bear on mine sites to start moving more with the equipment they have. An understanding of where efficiency has been lost will be a key component in that. The information contained in AMMOP, and the subsequent analysis of that information in papers such as this one, will be crucial to reversing the decline in open cut equipment performance.CITATION:Lumley, G, Trott, T and Lewis, M, 2012. Reversing the trend in open pit mining equipment output, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 75-82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

The changes in layout and design over 48 years, from the first crushing and shiploading plant installed at Whyalla in 1915, up to the present plant being built at Koolan Island, Yampi Sound may be summarized as follows.1. Smaller motors and lower power consumption have resulted froma. oil lubrication, where practicable, in place of grease,b. a high pressure "oil-lift" device to reduce starting torque in crushers with white metal bearings, andc. roller bearings in place of white metal.2. Short centre drives with pivot-based motors permit controlled loads on bearings and a reduction in size of crusher houses and motor rooms.3. Dust proofing and pressurising of crusher houses and motor rooms reduces working temperatures and improves cleanliness.4. Variable speed pan feeders give improved plant control, with the use of one man only, and remove the need for large surge bins between crushing stages.5. The use of diesel quarry trucks to dump ore through a "drive over"tip results in faster truck cycles.6. Elevated cylindrical silos with air operated chutes, replace long horizontal storage bins with multiple manually operated side discharge chutes for loading rail cars, and give faster and more accurate truck loading. The silos are charged by belt conveyors with automatic distributors.7. Increased shipping bin capacity (40,000 tons at Whyalla and 6O,OOO tons being built at Koolan Island) caters for the bigger vessels now in use and envisaged for the future. Automatic travelling distributors deliver ore to the bins in layers to ensure, maximum mixing and a more uniform grade for blast furnaces.INTRODUCTIONThe Broken Hill Proprietary Company Ltd has six major crushing plants in Australia at its principal sources of raw material. These are at Iron Knob bench G, Iron Knob scree ore plant, Iron Baron, and Cockatoo Island, all of which are ironstone operations. The other two plants are at Rapid Bay, a limestone quarry, and at Ardrossan, which is the Company's only source of dolomite.

Jan 1, 1963

By A Vakili

Dilution is associated with considerable direct and indirect costs in underground open stoping operations. As shown in previous works, an improved ability to predict dilution enables the economic risks associated with unplanned dilution to be reduced. Depending on the width of the orebody and depth of mining, the economic performance of an open stoping operation can become even more sensitive to dilution. It is shown in several well-documented studies that as little as 1 per cent of additional dilution can impose millions of dollars of lost profits per annum. Optimisation of a stoping operation is therefore largely dependent on the ability of the operation to minimise dilution. This can only be achieved through sensible analysis of past and future performance of mined stopes using the most appropriate recent available technologies and tools. This article presents a new design process that utilises advanced geotechnical numerical modelling and various other analytical tools to assist with a more robust mine design of open stoping operations. The focus of this design process is on geotechnical factors affecting dilution during the life-of-mine. A recent application of this optimisation method for a mining operation is presented in this paper as a case study. Through the application of this method and various other operational improvements, the mine was able to deliver more consistent production and lower operating costs over its life-ofmine outlook and was able to reduce dilution by up to 50 per cent and achieve sustainable record high production rates.

Mar 29, 2023

By D R. Seaman, B Adamson, P Sharman, M McMahon

"The Telfer processing plant commissioned its pyrite regrind and flotation circuit in August 2012. The circuit was designed to regrind pyrite concentrate to a p80 of <30µm then float a gold and copper rich concentrate before tails from the flotation circuit fed the carbon-in-leach (CIL) circuit downstream. Expected benefits were: improved CIL performance that would result from the finer grind and a reduction in cyanide soluble copper to the CIL circuit, as well as a small increase in overall flotation circuit recovery. While the benefits of a finer grind were soon realised, recovery in the post-regrind flotation circuit (named the ‘pyrite recleaner circuit’) was consistently and significantly lower than that expected based on laboratory test work. Selectivity in the pyrite recleaner circuit was virtually nil and copper reporting to the CIL circuit did not change as a result of the pyrite recleaner circuit operation.A pulp chemistry survey of the plant and comparison with the lab showed that the dissolved oxygen (DO) demand in the plant was much higher than that in the lab. Lab flotation tests conducted using nitrogen gas instead of air resulted in recoveries similar to those from the plant. It was identified that the freshly ground pyrite surfaces exiting the regrind mill were consuming oxygen in the slurry and there was insufficient oxygen available for collector adsorption and pyrite depression to occur. Test work, using a pilot regrind mill, showed that a reduction in grind size resulted in an increase in DO demand.A range of oxidising agents were tested in the laboratory and using a pilot flotation rig set-up in the plant. Oxygen was found to be the most reliable and effective agent and options for increasing oxygen delivery to the plant were explored. Scale-up from the lab oxygen requirement to the plant is difficult and efforts to implement a permanent solution for meeting the DO demand in the plant are ongoing.Citation:McMahon, M, Seaman, D R, Sharman, P, Adamson, B and Seaman, B A, 2016. Optimising the Telfer Pyrite Regrind Circuit - Effect of Dissolved Oxygen Demand, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 51–58 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By S Walters

The emerging discipline of ‘geometallurgy’ is not new but is becoming increasingly recognised as a discrete and high-value activity. Geometallurgy involves a quantified and spatially constrained approach to ore characterisation in terms of relationships to critical processing performance behaviours. A key outcome is enhanced economic optimisation of mining and improved risk management tools.Industry recognition of the need for large-scale, integrated research to support this emerging area resulted in commencement of a major ongoing initiative in mid-2005. The AMIRA International P843 ‘GeMIII’ project (Geometallurgical Mapping and Mine Modelling) is a cross-discipline collaboration involving a number of world-class research organisations supported by over 20 industry sponsors.The project is delivering integrated tools and methods which link intrinsic rock characteristics to prediction of mineral processing performance. These indices must be capable of spatial distribution in 3D resource models and incorporation into mine planning and optimisation. A key aspect is provision of new cost-effective tools and methods which can provide the large numbers of measured and estimated data points required to undertake effective modelling and spatial distribution. The integrated methodology and enabling technologies being developed through the ongoing AMIRA GeMIII project are outlined, together with implications for supporting industry best practice.

Sep 5, 2011

As the mining industry looks to new technologies for a safe work environment and increased production rates, so should emergency response teams when dealing with organisational incidents. Implementation of technology has transformed the nature of incidents within the international mining community with lower frequency, high impact events replacing high frequency, low impact incidents of the past. In turn the approach to mines rescue response and preparation has naturally diversified. New rescue technologies when applied effectively can only further advance preparation and the response of mine rescues teams. This paper discusses some of the changes associated with mines rescue as the industry embraces technology. It highlights some recent rescue responses and their approach and gives examples of some of the new technologies being used for improved mines rescue.

Jan 1, 2004

By P Craig, I Canbulat, J Naylor, J Emery, A Sykes

Longwall mining is by far the most common method of underground coal extraction in Australia. Industry trends and expectations are placing increasing emphasis on the reliability and productivity of these operations. Longwalls are becoming wider and longer while retreat rates are continuously increasing due to significant improvements achieved in longwall equipment reliability and automation. This increased longwall productivity is placing significant emphasis on the reliability of longwall panel development.Although there have been significant improvements in the reliability of continuous miners and hydraulic drill rigs, the traditional resin-encapsulated bolt installation is still the principal method used in all major coal producing countries around the world. Anglo American realised that an opportunity existed to introduce an alternative roof bolt installation technique called ‘spin-to-stall’ (STS) into Australia. STS was first introduced by Anglo American Coal in South Africa, where it has been successfully used for over a decade, though implementation of South African STS resin in Australia has proven to be near impossible. Therefore, a new STS development project was initiated between Anglo American Coal and Jennmar Australia. This paper summarises the journey of this project, the results achieved and the successful implementation of STS at Grasstree mine.CITATION:Emery, J, Canbulat, I, Craig, P, Naylor, J and Sykes, A, 2014. Development and implementation of spin-to-stall resin at Anglo American’s Australian Underground Coal Operations, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 287–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By J Salaya, J Kwak, L Keeney, S Dehkhoda

In addition to volatile commodity prices influencing decision making, in recent years, social and environmental performance have become important decision drivers within the mining industry. There are increased demands from stakeholders, communities, and governments to ensure that raw materials are mined, processed and refined responsibly. The industry also faces the challenge of better managing its waste, which has led to severe consequences when not done properly. The high commodity prices of the late 90s and early 2000s encouraged larger economies of scale and drove mining companies to extract large volumes of rock for separation and concentration at the downstream processes. Over time, as ore grades dropped, the cost of mining escalated and tailings volumes grew. This arduous process also caused strains on recovery cost and performance. Scarcity of water and energy resources coupled with increased production demands and higher operating costs are putting pressure on companies to find innovative ways to increase mining intensities. Hatch’s value chain optimisation methodologies, specifically Grade Engineering® and early waste rejection of the mine, have been of interest to intensify operational performance and minimise waste generation. Enabling preconcentration of the plant throughput, the methodology has significant potential to improve overall metal production and reduce water and energy intensities, whilst minimising wet tailings. Using representative data from real world mines, this paper reports on a case study that evaluates the impact of preconcentration using sensor-based ore sorting on downstream process improvements as well as energy, water and tailings reduction. Financial and economic viability of this technique is presented for both brownfield and greenfield implementation cases. The results show that business case for preconcentration is best when: the distribution of metal in the run of mine ore is negatively skewed and left tailed; mining costs are low; energy, water and tailings management costs are high; and low cost methods of recovering pay metal from low grade material are available.

Nov 10, 2020

One of the responsibilities of the Melbourne and Metropolitan Board of Works is to provide a sewerage system for the metropolis of Melbourne which now contains over 2.5 million people. In providing this sewerage system it was necessary for the Board to embark on a large tunnelling programme some 20 years ago. As a result of this extensive tunnel construction programme, tunnel boring machines and shaft sinking methods have been developed to cope with the soft ground and soft to medium rock found in the southern and eastern areas of Melbourne where the majority of the recent tunnelling has been carried out. While in the last few years radical changes in construction methods have not been made, development has continued and improvements have been made, which have enabled the Board to extend the limits of the ground conditions in which it can efficiently construct shafts and also tunnels with boring Machines.

Jan 1, 1976

By D Howe

The Athena gold deposit was discovered in 2007 by Gold Fields Australia Ltd, at the St Ives Gold Mine, 35 km southeast of Kambalda, Western Australia. Gold anomalism was identified in sheared Paringa Basalt as a result of a regional scale aircore drilling program, in association with geophysics. In the 18 months following discovery, the deposit was intensely drilled and by June 2009, it was announced that the Athena deposit contained an ore reserve of 1.7 Mt @ 5.6 g/t for 316 koz. This was followed by a feasibility study, and as a result mine development commenced in November 2009.The Athena mineralisation is hosted in a discrete, north-south striking, steep to moderately dipping shear zone within the southwest dipping Paringa Basalt. Vein intensity has a strong correlation to grade and vein type varies from early thin quartz-albite-sulfide (pyrite and/or pyrrhotite) shear parallel veins to strong brecciation and irregular veining with quartz-albite-actinolite-biotite-pyrrhotite infill. The geology preproduction process developed at the Argo mine was refined and improved following a business improvement project. The aim of the process is to construct detailed geological interpretations prior to development allowing informed mining decisions to be made. The process delivers significant cost savings and revenue enhancements.The development of macroscopic classification scheme was critical to determine ore or waste in the early phases of mining. The Style of Deformation, Alteration and Veining (SAV) Code was the result, and has been enhanced as greater geological knowledge is gained over time.

Aug 22, 2011

By G S. Esterhuizen, M M. Murphy, T S. Bajpayee

The strength reduction method (SRM) has been implemented in the FLAC3D finite difference software and applied to coalmine entry support evaluations. The FLAC3D numerical models have been calibrated against instrumented field sites in varying geologies, depths and field stress conditions. The calibration between the field and model results obtained a satisfactory match for rock deformation and support response. Previous research has also developed good correlations between numerical model stability estimations using the SRM and empirically derived stability estimations using the analysis of roof bolt systems (ARBS) software and the coalmine roof rating (CMRR). The purpose of this paper is to further apply the SRM to investigate how specific geotechnical and support parameters can impact coalmine entry stability. Results from different studies demonstrate how the calibrated models were used to investigate a few of the well-known questions in both mine design and support design. For mine design the impact of strong and weak beds in the roof strata, rotating the principal stresses and weakening the floor on excavation stability is investigated. For support design the impact of support length, support spacing and adding cable bolts to the design is demonstrated. These scenarios are evaluated in developmental coalmine entries for a variety of geology and field stress conditions. Stability factors are calculated for each scenario using the SRM. The SRM allows the impact of each parameter to be quantified and allows the support system to be optimised for given geotechnical conditions.CITATION:Esterhuizen, G S, Murphy, M M and Bajpayee, T S, 2014. Analysis of geotechnical and support parameters on coalmine entry stability using the strength reduction method, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 383–392 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By G S. C Murray

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutionsÆ funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industryÆs concept of the unwritten æsocial licence to operateÆ is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007

By B D. Burford

High intensity stirred milling using the IsaMill has been the enabling technology for many projects by transforming the economics of fine grinding and simplifying circuit design. IsaMill grinding technology was originally developed for large-scale grinding to P80 sizings of 7 ¦m. The IsaMill is a high throughput, high efficiency mill that produces sharp product size distributions in open circuit configuration. The ability to grind in an inert environment, using a wide variety of media types, can give further metallurgical and economic benefits. The high energy intensity results in a small footprint that enhances the ability to distribute grinding power throughout the circuit, applying grinding energy to the minerals that need it. Recent scale up developments in IsaMill technology have enabled the benefits to be extended to large-scale conventional grind sizes, until now the domain of ball and tower mills. This paper will examine the crossover of IsaMill technology from ultrafine applications into the more conventional grinding area (P80 20 - 150 ¦m). Scale-up developments in IsaMill technology that have enabled this are reviewed. The upcoming commissioning of a 3.0 MW M10,000 IsaMill, the most powerful to date, grinding to P80 55 ¦m at PPL in South Africa will be discussed, as will the recent commissioning of a 2.6 MW M10,000 IsaMill at Kumtor. Recent testwork at McArthur River, where an IsaMill is being considered as an addition to the primary grinding circuit to replace the current tower mill will be reviewed. The potential combination of HPGR and IsaMill to transform concentrator grinding economics will also be discussed. Large-scale IsaMill technology has the ability to transform circuit design and energy efficiency for both coarse and fine grinding.

Jan 1, 2006

By C M. Ramotsabi, F Bornman, W Erasmus

Spiral concentrators are gravity based separation devices used for the preparation of coal, iron and heavy mineral ores (Wills, 1992). Gravity concentration remains the main separation method for fine iron ore and is used extensively for treating many minerals. Gravity concentration methods separate minerals of different specific gravity by their relative movement in response to gravity and one or more other forces, the latter often being the resistance to motion offered by a viscous fluid such as water or air (Wills, 2006).The main operating variables for a spiral concentrator are the feed rate, the slurry concentration, the wash water addition and the position of the splitters used to separate the tailings, middlings and concentrate streams (Sadeghi, Bazin and Renaud, 2014). Wash water is an important control variable used to wash away entrapped light minerals from the concentrate stream (Burt, 1984; Bouchard, 2001). Sadeghi et al concluded the spiral operation to be sensitive to the wash water flow addition and resultant economic trade-off. Increasing the wash water flow rate increases the concentrate grade at the expense of the iron recovery.The paper addresses the effects of dripping wash water onto the concentrate stream of a spiral processing fine iron ore. The dripping wash water system offers a low flow alternative and could possibly provide a good balance between grade and recovery of valuable minerals without using excessive water. The Multotec SC20HC/7 WW spiral was used for the experimental test work. The spiral was tested at varying solids concentrations; the wash water rate and the splitter positions were kept constant.The use of wash water at 30 per cent, 35 per cent and 40 per cent solid concentration improved the Fe grade in the concentrate by about 1.5 per cent, six per cent and eight per cent respectively. The additional SiO2 rejected by the wash water is approximately three per cent, nine per cent, and 11 per cent at 30 per cent, 35 per cent and 40 per cent solid concentration respectively. Addition of wash water is shown to have minimum effect on grade at 30 per cent solid concentration, and Fe upgrades obtained with and without wash water were found to be similar. Notable upgrades were observed at 35 and 40 per cent solid concentration with wash water. The results obtained suggest that the additional SiO2 rejection by wash water increases with an increase in solid concentration. This suggests that the benefit of using the drip system is notable at higher solid concentration. It is believed that at lower solid concentration SiO2 particles are reasonably free to move around and are possibly less entrapped than at high solid concentration.The Fe grade/recovery and solid concentration relationship with wash water showed a non-linear correlation. The Fe grade increases with an increase in solid concentration up to a somewhat optimum point and then drops as solid concentration increases further. The recovery of Fe on the other hand follows a converse relationship with solid concentration, the recovery decreases from 30 per cent to 35 per cent solid concentration and then increases again at 40 per cent solid concentration. The increase in recovery at higher solid concentration could possibly be explained by the fact that the mass yield to concentrate also increases with solid concentration. Since recovery is a function of both grade and mass yield, the higher recovery at 40 per cent solid concentration is likely due to the high mass yield obtainable at 40 per cent solid concentration.The drip system could therefore possibly offer a safe guarding against grade and solid concentration variations without using excessive water, and possibly ensure that a product within specification is maintained.CITATION:Ramotsabi, C M, Erasmus, W and Bornman, F, 2015. Optimisation of wash water on an iron ore spiral to improve grade, in Proceedings Iron Ore 2015, pp 175–184 (The Australasian Institute of Mining and Metallurgy: Me

Jul 13, 2015

By G Danckert

The key technical theme of ‘orebody knowledge’ has been applied by Rio Tinto in the Pilbara iron ore precinct from 1966, when operations first started there. It forms the basis of present day application, as well as planning for the future.This paper will review how the early towns and mines commenced and how they formed the basis of Rio Tinto’s early operations, on which the Pilbara precinct has been based. A profile of the last decade of Pilbara growth will be highlighted, together with the current integrated network of mines, rail and ports and the next generation of expansions.The paper will specifically describe the Rio Tinto process of significant resource evaluation, including comprehensive drilling programs and the conversion from resource to reserves. It will also describe the overall mine planning process, both from the strategic view, as well as for short-term mine plans.The ability to innovate in resource development will be discussed. This will include not only the technical dimension of changing cut off grades, use of low-grade ores and managing low-grade stockpiling and beneficiation, but also the broader application of new technology and innovation in the iron ore business.

Jul 11, 2011