Optimisation of the Proeminent Hill Flotation Circuit

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Metallurgical Plant Design and Operating Strategies (MetPlant 2013) 15 - 17 July 2013, Perth WA

Optimisation of the Prominent Hill Flotation Circuit

P Woodward1, N Muhamad2 and T Ly3

1. GAusIMM, Plant Metallurgist, OZ Minerals Ltd Prominent Hill, Ground Floor, 170 Greenhill Road, Parkside SA 5063. Email: [email protected]

2. MAusIMM, Senior Plant Metallurgist, OZ Minerals Ltd Prominent Hill, Ground Floor, 170 Greenhill Road, Parkside SA 5063. Email: [email protected]

3. AAusIMM, Senior Project Metallurgist, OZ Minerals Ltd Prominent Hill, Ground Floor, 170 Greenhill Road, Parkside SA 5063. Email: [email protected]

ABSTRACT OZ Minerals' Prominent Hill copper-gold concentrator is located 650 km north-west of Adelaide in the Gawler Craton of South Australia. The concentrator was built in 2008 and commenced commercial production in early 2009. The Prominent Hill concentrator is comprised of a conventional grinding and flotation processing plant with a design capacity of 8 Mtpa. The flotation circuit includes six rougher cells, an IsaMill for regrinding the rougher concentrate and a Jameson cell preceding the three stage conventional cell cleaner circuit.

Since its commissioning, the Prominent Hill flotation circuit has been the focus of a series of projects aimed at continual performance improvement. This has been achieved by a systematic approach of project identification, evaluation and implementation which has led to a progressive improvement in flotation performance. Innovations that have been successfully implemented include aspects of cell design and operation, and reagent suite optimisation.

Improvements to the mechanical cells initially focused on the installation of a modified rotor-stator design in the rougher circuit, as recommended by Outotec. Isolated cells were fitted with this technology and proven to provide a benefit for copper recovery before the design was trialled in subsequent cells along the bank. Based on this success, further modifications were made to other aspects of the rougher and cleaner cells.

Laboratory trials conducted at Prominent Hill involve a screening process identifying potential reagents from a list of products, which are then rigorously tested in the laboratory before one is selected for trial in the concentrator. Where these reagents have demonstrated a statistical improvement in performance they have typically been incorporated permanently into the flotation circuit. This paper discusses the process of continual improvement at the Prominent Hill flotation circuit and the optimisation achieved by the implementation of key initiatives.

INTRODUCTION OZ Minerals Prominent Hill operation is located 650 km northwest of Adelaide in South Australia and approximately half way between the town of Coober Pedy and the BHP Billiton Olympic Dam operation. The project area landscape is flat gibber terrain with few notable features. The climate is arid with high daytime temperatures, high evaporation and low annual rainfall.

The Prominent Hill deposit was discovered in 2001 by Minotaur Resources with OZ Minerals securing 100% ownership in 2005. Mining commenced in 2006 with plant construction in 2008 and first production and sales in February 2009.

Prominent Hill is an iron oxide hosted copper-gold (IOCG) deposit with geological characteristics similar to Olympic Dam (Reeve et al., 1990). Mineralisation consists of copper-gold breccia (80% of the known mineralisation) broken down into four main types (Colbert et al., 2009):

Chalcocite-bornite Bornite-chalcopyrite

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Chalcopyrite-bornite Chalcopyrite-pyrite. In addition, a considerable amount of gold only low sulphide content ore with a host rock of iron oxide was identified in the upper area of the deposit. This material forms up to 20% of the feed with the gold being recovered as part of the flotation concentrate.

Mine reserve is currently 69.8 Mt at a grade of 1.1% copper and 0.60 g/t gold. The open pit currently has an estimated mine life of eight years. Significant exploration activities occurring within the lease boundaries, particularly beneath the pit floor, have potential to add to the mine life.

During the design phase, testwork conducted as part of the bankable feasibility study indicated the following expected results for different copper sulphide mineral species (for testwork purposes bornite-chalcopyrite and chalcopyrite-bornite were considered as one mineral species):

Chalcocite-bornite - 88% recovery at 54% copper concentrate grade Bornite-chalcopyrite - 80% recovery at 25% copper concentrate grade Chalcopyrite-Pyrite - 83% recovery at 34% copper concentrate grade. Given that the feed would consist of a blend of these mineral species, actual recovery would depend on their relative proportions. Similarly, the concentrate grade realised would depend on the proportion of secondary copper sulphides contained in the feed.

By the end of 2009, its first year of operation, the processing plant was consistently meeting its design capacity of 8 Mtpa throughput. As part of the commissioning process, two major changes had been made to the flotation reagent scheme, including the change from sodium isobutyl xanthate (SIBX) to a staged addition of sodium ethyl xanthate (SEX) as the main collector, and from an aryl ester product to a polyoxyalkylene alkyl ether product as the intermediate strength frother used in the rougher circuit.

From 2010 the focus of the Metallurgy team has shifted from commissioning to process optimisation. As part of this process, opportunities for process improvement are identified and solutions implemented.

Process description The Prominent Hill Concentrator (Figure 1) is fed a blend of copper-sulphide bearing ore types and gold-only ore from both the open pit and underground sources. This blend is determined by availability, composition and production targets. Ore is tip fed into a Fuller-Traylor type NT gyratory crusher, which feeds the coarse ore stock pile at a maximum rate of 3600 tph.

The grinding circuit is fed at approximately 1200 tph. It is operated as a SAB circuit, including a semi-autogenous grinding (SAG) mill followed by a closed circuit ball mill. The SAG mill has a 10.36 m diameter and a 5.18 m effective grinding length, featuring a ring gear with dual-pinions connected to twin hyper synchronous wound rotor motors, providing a total power draw of 12 MW. It operates with a variable speed drive operating between 8.6 and 10.6 rpm. A single ball mill with a 7.3 m diameter and 10.4 m effective grinding length provides 12 MW of energy, and is operated in closed circuit with a cluster of hydrocylones to produce a flotation feed of 80% passing 100 to130 m.

Copper sulphide bearing particles are separated from gangue using conventional flotation. All major equipment installed in the circuit is supplied by either Outotec or Xstrata Technology. These cells are listed in Table 1.

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Table 1 Floatation equipment

Number of items Function Model Capacity (m3)

6 Rougher OK-TC-150 150

1 Jameson Cell J5400/18 5.4m diameter and 18 downcomers

8 First Cleaner OK-TC-50 50

6 Second Cleaner OK-TC-20 20

4 Third Cleaner OK-TC-20 20

The rougher circuit consistently recovers 87 to 92% of the total copper sulphide minerals, with the greatest loss typically being from the >106 m size fraction. The rougher upgrade ratio is typically between eight and ten to one. The tailings from the rougher circuit is sent to the final tailings hopper.

Concentrate from the rougher circuit is fed via a cluster of hydrocylones to the regrind circuit. Underflow from the cyclones reports to an Xstrata M10000 IsaMill where it is reduced in size to approximately 80% passing 15 m. The IsaMill uses 3.5 mm inert ceramic media in order to limit its impact on the pulp chemistry of the cleaner circuit. The overall purpose of regrinding is to further liberate the cleaner feed, so as to improve rejection of non-floating penalty elements such as fluorine.

The product from the IsaMill is combined with the regrind hydrocylone overflow before being fed to the Jameson cell. This cell produces a high quality copper concentrate, which aids in the subsequent reduction of the cleaner circuit load. Wash water allows fine non-floating gangue particles, which might otherwise be recovered by entrainment, to be removed from the concentrate. The Jameson cell provides up to 75% of the total final concentrate mass.

Tailings from the Jameson cell are fed to the three stage dilution cleaning circuit. This circuit operates with the following recirculating loads:

Second cleaner tailings to the first cleaner feed hopper Third cleaner tailings to cell one of the second cleaner circuit. Concentrate from the third cleaner circuit is combined with concentrate from the Jameson cell to make up the final concentrate product, which is dewatered using a high-rate thickener and pressure filter. The cleaner circuit recovers 98 to 99% of copper sulphide minerals fed to this section. The first cleaner tailings and rougher tailings are combined to make up the final tailings of which the first cleaner contributes 8 to 13% of total copper losses. This combined stream is dewatered using a high rate thickener and sent to the tailings storage facility (TSF).

All major flotation streams are analysed for copper, iron and solids composition using an Outotec Courier 5 SL on stream analyser (OSA). Additionally, the feed to the flotation circuit and the feed to the Jameson cell are analysed for particle size distribution by an Outotec PSI 500 particle size instrument (PSI). These two instruments provide metallurgists and operators with the real time metallurgical performance of both the flotation and grinding circuits. As such operating parameters can be adjusted quickly to account for changes in the plant in order to optimise recovery and concentrate quality.

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Fig. 1- Prominent Hill flow sheet

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PROCESS OPTIMISATION AT PROMINENT HILL In a metallurgical process, any recoverable metal lost to the tailings is a missed opportunity. Metallurgists are tasked with identifying these opportunities, and investigating potential methods for realising lost recovery or cost savings. At Prominent Hill a policy of ongoing process improvement seeks to realise the greatest efficiency possible from the processing plant. Projects will typically focus on the following objectives:

Copper sulphide recovery Gold recovery Copper concentrate quality Equipment availability Cost reduction. The process for optimisation revolves around the identification of an opportunity and subsequent evaluation by a rigorous bench scale, pilot scale or plant test program wherever possible followed by statistical analysis of the data obtained.

Mineralogical studies are undertaken periodically in order to analyse concentrator performance. Such data and analysis allows metallurgists to define specific problems within the process, so that they can be targeted with the appropriate strategies. In particular size by size information provides particular insight into where losses can be reduced, or quality improved.

In general project lifetimes will follow a series of stages:

Opportunity identification and definition Measurement of potential improvement Detailed analysis or laboratory scale testwork Plant scale evaluation Permanent implementation Close-out and record keeping. Projects are treated as business improvement cases by following standard procedures for financial evaluation such as net present value assessment and stakeholder communication. These formal processes provide the means by which to ensure both financial due diligence and a strong technical database for the company. Once a project is proven to provide value to Prominent Hills bottom line, it will typically be handed on from the project metallurgists to the plant metallurgists and processing teams. As such the improvement can be permanently imbedded into the operation.

For the purposes of this paper, flotation optimisation projects have been categorised into three areas:

Reagent trials Mechanical cell modifications Process control.

FLOTATION REAGENT OPTIMISATION Reagent trials have been conducted at Prominent Hill to determine whether the inclusion of an additional collector in the reagent scheme will provide an improvement to the process. Historically frothers and modifiers were investigated during the plant commissioning process; however flotation optimisation has more recently focused around collector trials.

A specific area for improvement will be identified by the analysis of mineralogical data and plant performance, after which typically a series of different collectors are received from suppliers and are tested on representative splits of an ore blend sample in the laboratory as a screening trial. These flotation tests will replicate the section of the flotation circuit for which the reagents are intended. In most cases these will initially be rougher stage tests replicating existing concentrator conditions, including the established reagent scheme at equivalent dosage rates. Those collectors providing the

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greatest potential for process improvement are selected for further trials. Where an improvement is indicated the reagent is recommended for trial in the concentrator.

Plant trials are conducted as random on-off tests for the required length of time to gain a statistically significant result from a paired t-test. Addition is typically from a bulk container on the top of a cell via a small metering pump. Where a reagent has shown a statistically significant improvement as an addition to the existing reagent scheme it is permanently incorporated into the circuit.

In addition to SEX, three collectors have been included in the Prominent Hill reagent scheme after being screened in the laboratory and trialled in the plant. A summary of these collectors including their dosages and addition points is provided in Table 2. Overall these projects have contributed to improvements in both copper and gold recovery.

Table 2 Collector scheme summary

Collector Type Addition Points Dosage (g/t) Purpose

Sodium Ethyl Xanthate (SEX) Xanthate

Primary hydrocyclone feed hopper

Rougher circuit

First cleaner circuit

10-30 Selective sulphide collector

Interfroth CMS2500 Thionocarbamate Ball mill 1.5-3.5 Copper recovery

Cytec Aero 404 Dithiophosphate Rougher circuit head

Cleaner circuit head 3 Gold recovery

Orica DSP110 Thionocarbamate Rougher circuit head 0.25 Copper recovery

Interfroth CMS2500 CMS2500 was shown during an early reagent screening program to give a potential improvement in copper recovery when mixed with sodium ethyl xanthate. It is a sodium isopropyl ethyl thionocarbamate collector which was trialled by addition into the primary cyclone underflow, and as such received conditioning time in the ball mill. Its use in conjunction with the existing xanthate was shown to give an improvement in copper recovery of 1.1% at 98.8% confidence during the plant trial. The paired tests are shown in Figure 2.

Fig. 2- CMS2500 plant trial results (Ly and Bashay, 2010)

This collector was permanently added to the circuit using an existing test reagent infrastructure. This tank and piping system is a replication of the system used to dose xanthate to the circuit as

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installed during initial construction. Bulk containers are delivered to Prominent Hill and decanted into the top of the tank.

Cytec Aero 404 Mineralogy and size by size analysis had shown that up to 17% of gold losses in the flotation circuit were of relatively fine particles less than 15 m. These gold particles were inferred to be essentially liberated, and as such a reagent trial was conducted to find a collector which could improve gold recovery when added to the existing reagent scheme. Aero 404 was found to give an improvement in the laboratory when added to simulated rougher and cleaner stages. It is a sodium mercaptobenzothiazole dithiophosphate salt promoter, which had been used mainly for the flotation of gold bearing pyrite ore (Ly, 2011). Results of this trial are represented in Figure 3.

Fig. 3- Aero 404 plant trial results (Ly, 2011)

Analysis of data (Figure 3) from the subsequent plant trial showed that when added to the third rougher cell the dithiophosphate gave:

1.5% increase in rougher gold recovery at a 98.8% confidence level, and 1.68% overall improvement in gold recovery at a 95.9% confidence level. There was no indication that the promoter impeded copper recovery. A subsequent trial in the cleaner circuit indicated potential for further improvement in gold recovery. This was added into the Jameson Cell tailings box prior to the first cleaner circuit.

This reagent has been permanently added to the heads of both the rougher and cleaner circuits. A dedicated self bunded tank was installed adjacent to the flotation section with two small pumps directing the reagent to the dosing points. The tank is filled directly from bulk containers using a small transfer pump.

Orica DSP110 A large scale screening trial of 50 potential collectors was undertaken between November 2011 and February 2012 with the objective of finding a reagent, which when added along with the existing suite of xanthate, thionocarbamate and dithiophosphate collectors, would provide additional improvements in valuable metal recovery. From these 50 reagents five were short listed and further trialled in the laboratory, using paired t-tests to determine the statistical significance of the results.

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DSP110 was selected from these flotation tests for trial in the concentrator. It is a proprietary thionocarbamate blend and was trialled in the rougher circuit. Statistical analysis by Ly (2012) indicated:

0.35% increase in overall copper recovery at a 95.0% confidence level, and 0.42% increase in the rougher circuit copper recovery at a 97.7% confidence level. As a result this collector has been permanently added to the head of the rougher circuit.

FLOTATION CELL DESIGN OPTIMISATION Historical mineralogical and plant performance data has indicated that the greatest potential for process improvement exists in the rougher circuit. In general over 80% of the copper losses in the circuit occur through the rougher tailings. Whilst reagent trials can provide the surface chemistry solutions for improved flotation, the internal configuration of the flotation cells presented an opportunity for an improvement in mass transfer.

Mineralogy reports submitted by G&T Metallurgical Services Ltd (Shouldice and Ma, 2010) suggested that a relatively large proportion of sulphide bearing particles were being lost to the rougher tailings in both the coarse (>100 m) and fine (

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The modification, Outotecs Floatforce mechanism, is designed as a half-length stator with its greater impeller clearance intended to increase circulatory flow. Air flows in from the impeller shaft via dedicated dispersion slots and slurry is therefore able to be pumped without disruption. The mechanisms configuration is shown in Figure 4.

Fig. 4- Rougher cell rotor-stator configuration

Impeller shaft configuration An additional modification investigated was the addition of a bi-directional pitch-blade turbine to the impeller shaft of the rougher cells. Outotec claimed that the FlowBooster design would result in an improvement in mixing in both the bottom of the cell and the upper pulp area beneath the froth, providing improved coarse particle recovery (Bourke, 2007). The rationale behind these claims was that larger tank cells, such as the 150 m3 cells installed at Prominent Hill, do not provide as effective mixing as found in smaller cells. The installed blades are illustrated in Figure 5.

Fig. 5- Pitch-blade turbine installed in a rougher cell

CFD studies completed by Bourke (2007) showed that after the installation of a mid-shaft turbine exerting downwards force in the pulp, an improvement in both primary and secondary mixing was seen.

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Results of mechanical modifications On the basis of claims from the supplier, the rotor-stator modification was initially trialled in the first rougher cell. Surveys taken before and after the change indicated an improved copper sulphide recovery. Additionally the P80 of the cell concentrate increased indicating improved coarse particle recovery. Subsequently the modified mechanism was trialled in cells two and three, then four and five, and was finally installed in cell six. Similarly after the successful installation of the pitch blade turbine in the first rougher cell, this was also installed in the other cells along the bank. These installations were completed between June 2010 and June 2011.

Pitch blade turbine The difference in mixing caused by the installation of the pitch blade turbine was investigated by using a survey to demonstrate the difference in P80 at various pulp depths. In the cell in which the turbine was installed a greater P80 was seen at all depths tested (Figure 6), demonstrating improved secondary mixing and coarse particle suspension.

Fig. 6- Effect of pitch-blade turbine installation on rougher pulp P80 (Alexander, 2011)

Overall loss reductions It can be seen from Table 3 that over the period of these installations that the rougher circuit copper and gold losses reduced by approximately 2.4% and 1% respectively.

Table 3 Rougher copper and gold losses

Average rougher losses (%)

Year Cu Au

2010 9.7 18.3

2011 7.3 17.3

Total reduction 2.4 1.0

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Table 4 Size by size rougher copper losses

Average rougher copper losses by size range (%)

Year >106 106-C1 C1-C4 C4-C5 106 m range 0.7% copper -106m C1 size range 0.7% copper -

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The resulting benefits were:

Improved performance in recovery Improved stability after start-up Improved day to day circuit stability Reduced pump movement and disturbance propagation Simplified rougher circuit control Consistent strategy across the processing crews.

Flow optimisation in the cleaner circuit After the successful implementation of the flow optimisation process control system in the rougher circuit, this was also installed in the first cleaner section. With regards process control, the major difference between the two systems is that instead of controlling a measured flow rate, the first cleaner flow optimiser controls the output of the pump variable speed drive in terms of percentage. The first cleaner circuit is split into four banks of two cells each, where each bank has independent level control. Air set points are controlled for each cell by the flotation operator, and similarly to the rougher circuit the controller allows the pump to operate at the set point by maintaining the concentrate hopper level. The flow optimiser stabilises and optimises the mass flow by manipulating the four level controllers.

The aim of the modification is to:

Minimise the liberated non-sulphide contaminants, such as fluorine, recovered in the first cleaner concentrate and therefore the final concentrate, and

Maintain a consistent mass flow from the first cleaner circuit. The mass pull can be adjusted to account for changes in upstream performance, such as in the Jameson cell. The optimiser ensures that an appropriate mass pull is achieved from across the cells, such that each flow is aligned to achieve optimal copper sulphide recovery whilst limiting the amount of gangue recovered to the concentrate. This would improve the quality of the concentrate by rejecting penalty element bearing gangue particles that may have otherwise been recovered in cells at the end of the circuit.

This control system allows the flotation operator to focus on other tasks in the flotation circuit, as they need to spend less time focused on the first cleaner section. Additionally this would provide a consistent strategy for operation across all four crews, as the relative mass pull from each cell is set by the plant metallurgist.

ONGOING IMPROVEMENT Optimisation of the flotation circuit has allowed the plant to exceed the performances predicted during the bankable feasibility study for Prominent Hill, indicated by the end of year results achieved:

2010 total copper recovery of 89.1% 2011 total copper recovery of 90.5%. The greatest recovery predicted was 88% for a blend consisting solely of chalcocite-bornite ore. These results improved upon the testwork predictions significantly, emphasising the value created by process optimisation.

Initial projects provided large step changes in performance, therefore adding considerable value to the bottom line of the Prominent Hill operation. As the life of the mine progresses, process optimisation will be required to respond to changes in the overall operation. Changing operating conditions, such as the increased inclusion of underground ore in the concentrator feed, will present additional opportunities for process improvement. As such, additional modifications to the operation of the concentrator will be required in order to achieve optimal performance.

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Additionally, the focus of the metallurgy team has shifted towards cost reduction strategies, continuing the process of ongoing improvement.

Cost optimisation in the flotation circuit can be achieved on the supply side by seeking to reduce the costs of reagents. Opportunities exist to reduce pricing by negotiation, including delivery initiatives and direct substitution at a lower price.

A more complex cost reduction strategy involves improving the quality of the concentrate by reducing the incidence of contaminants such as fluorine. Typically these are non-sulphide particles which are recovered into the final concentrate either by entrainment or due to poor liberation. These two problems can be targeted using further cell modifications or changes to the circuit configuration.

CONCLUSIONS Since 2010, optimisation in the flotation circuit at Prominent Hill has provided improvements to both valuable metal recovery and throughput. During 2011 this allowed the concentrator to achieve a throughput of 9.9 Mtpa, 24% beyond its design capacity of 8 Mtpa, and copper recoveries of 90.5% compared to 89.1% in 2010 and the maximum of 88% predicted from the design test work.

Additional reagents have allowed increased copper and gold recoveries without compromising copper concentrate quality. The evaluation of these additions has followed a disciplined and rigorous approach, requiring that any added value was shown to be statistically significant before a change was permanently included in the circuit.

Similarly, retro-fitted modified rotor-stator mechanisms in the rougher cells have contributed to improvements in rougher copper and gold recoveries of approximately 2.4% and 1% respectively. These modifications have allowed for improved coarse particle recovery, and this in turn has allowed an increase in mill throughput. Additionally, expert process control systems installed in the flotation circuit have allowed for improved process stability.

Ongoing improvement is an integral focus of the Prominent Hill metallurgy team. As process improvement opportunities become more complex to achieve, objectives have moved towards responding to changes in the mine operation, such as a changing ore supply as the underground ore resources are introduced into the feed blend. Additionally the focus has moved towards cost reduction strategies in order to further optimise the flotation circuit. Retaining a continual focus on process optimisation ensures that opportunities to increase efficiency will be recognised and explored.

ACKNOWLEDGEMENTS The authors thank OZ Minerals Limited for permission to publish this paper.

REFERENCES Alexander, B, 2010. PH/TN/3410/10/142 Effect of FloatForce Mechanism on Rougher One Performance, internal

technical note (unpublished), OZ Minerals Limited, Prominent Hill.

Alexander, B, 2011. PH/TN/3410/11-004 Effect of Outotecs Flowbooster Mechanism on Rougher Three Performance, internal technical note (unpublished), OZ Minerals Limited, Prominent Hill.

Bourke, P, 2007. Optimizing large flotation cell hydrodynamics using CFD, Output Australia, 19: 1-4.

Colbert, P J, Munro, P D, Yeowart, G, 2009. Prominent Hill Concentrator- Designed for Operators and Maintainers, in Proceedings Tenth Mill Operators Conference, pp 23-31 (The Australian Institute of Metallurgy and Mining: Melbourne).

Lombardi, J, Weidenbach, M and Muhamad, N, 2011. Flotation Process Control Optimisation at Prominent Hill, Proceedings MetPlant 2011, pp 602-614 (The Australian Institute of Metallurgy and Mining: Melbourne).

Ly, T and Bashay, M, 2010. PH/TN/3400/10/155 Plant Trial using Mixed SEX-CMS2500 Collectors, internal technical note (unpublished), OZ Minerals Limited, Prominent Hill.

Ly, T, 2011. PH/TN/3400/11/019 Aero 404 Gold Collector Plant Trial, internal technical note (unpublished), OZ Minerals Limited, Prominent Hill.

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Ly, T, 2012. PH/TN/3400/12/029 DSP 110 Rougher Plant Trial, internal technical note (unpublished), OZ Minerals Limited, Prominent Hill.

Nelson, M G, Lelinski, D and Grnstrand, S, 2009. Design and Operation of Mechanical Flotation Machines, in Recent Advances in Mineral Processing Plant Design (Ed: D Malhotra, P R Taylor, E Spiller, and M LeVier), pp 168-189, (The Society for Mining, Metallurgy and Exploration: Colorado).

Reeve, J S, Cross K C, Smith, R N and Oreskes, N, 1990. Olympic Dam copper-uranium-gold-silver deposit, in Geology of the Mineral Deposits of Australia and Papua New Guinea Volume 2 (Ed: F E Hughes), pp 1009-1035, (The Australasian Institute of Metallurgy and Mining: Melbourne).

Shouldice, T and Ma, W, 2010, Mineralogical Assessment of the Prominent Hill Flotation Streams March 2010 KM2641, technical report (unpublished), G&T Metallurgical Services, Kamloops.

Weidenbach, M and Rajiwate, F, 2010. PH/TN/3400/10-133 Feasibility study for installing Floatstar level stabilizer on the flotation circuit, internal technical note (unpublished), OZ Minerals Limited, Prominent Hill.

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Optimisation of the Proeminent Hill Flotation Circuit