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By R Jacobs

"The Jaguar project is relatively unique in that it was evaluated, financed, built and operated to completion within the last ten years, providing the opportunity to holistically review and reconcile expectations against the actual outcomes. It is a case study that allows wider conclusions to be drawn with respect to the risks and opportunities involved with project evaluation and execution.Jaguar is located in the Leonora Mining District of Western Australia and was commissioned in mid-2007 as an underground accessed, single high-grade volcanic-hosted massive sulfide (VHMS) deposit with an on-site concentrator, producing copper and zinc concentrates exported via the Port of Geraldton to South-East Asian markets.The feasibility study (FS) had several iterations (JML, 2005a); the last dated July 2005 was specifically targeted to secure project funding, and summarised the reserves-only portion of the resource and its planned exploitation. The commissioning of the mine was the transition for the owner Jabiru Metals NL from junior explorer to producer and the project was the dominant asset of the company.Jaguar operated through several significant deviations from the linear project plan set out in the FS, including the Global Financial Crisis (GFC), a corporate takeover and disruption to the mine plan from the onset of material geotechnical issues. Whilst the GFC or mining disruption were not specifically predicted in the FS or peer reviews, the generic effects of the events were assessed in the project risk assessment and they influenced subsequent management decisions. In parallel to the internal project-specific risks, the short planned life of Jaguar was a risk to the continuation of the corporate entity which was being addressed by significant investment into brownfields exploration to extend or replicate the project, and ultimately added value such that attracted a corporate takeover.Holistically, the project delivered the returns predicted in the FS, but in a much different guise than was expected. This paper will describe the reality of operations compared with the study predictions and expectations through the perspective of the project and corporate risk assessment.CITATION:Jacobs, R, 2016. Jaguar base metals project case study – has reality reflected the study?, in Proceedings Project Evaluation 2016, pp 86–97 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By M Bettison, R Wright, N Taylor

The primary mine planning focus during early study phases of future mining projects is Life of Asset ore production and grade quality, this will always be the situation. While waste schedule optimisation is generally considered in the latter study phases nearing execution for a limited number of schedule periods only and not a true optimisation considering all attributes such as waste destination location, design, cycle time and closure. This can be particularly applicable in large multi-pit bulk mining operations where one approach to meet Life of Asset ore tonnes and grade targets has been to maintain pit development flexibility resulting in large open pit areas and substantial expit Overburden Storage Area (OSA). The value opportunity is to develop a Life of Asset waste schedule source-to-destination optimisation prior to mine development considering all applicable attributes and routinely review throughout the Life of Asset taking account of improved ore and waste knowledge.CITATION:Taylor, N, Wright, R and Bettison, M, 2018. Utilising mine planning to deliver closure landforms through productive movement, in Proceedings Life-of-Mine 2018, pp 96–99 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

British Coal has made a practical progressive approach to improving the reliability of its mining equipment. Reliability must be addressed at the specification stage but does not end there and routine procedures are used to procure equipment of adequate reliability. The techniques used to monitor and improve reliability during the operational phase of the equipment, providing engineers and operators with detailed printouts, together with the types of maintenance employed, ensure high levels of availability. Finally, the methods of repair and overhaul of British Coal equipment and systems ensure that the initial reliability targets outlined on the specification, can still be achieved.

Jan 1, 1991

By T R. Stacey

South Africa has a long history of rockbursts, some 100 years. During this time much research and many developments have taken place in the country to limit the occurrence of rockbursts, and to mitigate their effects. In this paper I shall present a personal view of what I consider to be important achievements, and contributions made. Some of these are: planning of stope layouts, and the use of strike barrier pillars; recognition of energy as a key factor, the use of the energy release rate ERR as a layout planning criterion, and development of MINSIM for calculation of ERR and stope planning; sequential grid stope layouts; use of backfill for stope support; and, development yielding support elements, and dynamic testing of stope and tunnel supports. The record shows the establishment of a rock engineering research powerhouse over a 40 to 50 year period and, unfortunately, the complete breakdown of this capability in the subsequent 10 years. CITATION:Stacey, T R, 2018. A personal review of South African rockburst research, experience and lessons learnt, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 5–16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By T Atchison

In-pit crushing and conveying (IPCC) systems have come under growing scrutiny as a perceived mitigation to fuel and equipment price fluctuations, labour shortages and the need to move everincreasing volumes of material. Individual vendors and delivery organisations are now offering a sometimes confusing array of systems, particularly for the dig and dump side operations.One system does not suit all operations. This paper seeks to document the factors that should be considered in assessing the suitability of different IPCC systems, with a focus on dig side equipment layouts in particular. These factors include the productivity of the systems, interactions with the drill/blast and bench operation sequence, the ease of relocation, flexibility to changes in the reserve, scalability and compatibility with other elements of the system.

Jul 11, 2011

By G Zhang, I Glacken

Multiple indicator kriging (MIK) has been used in the minerals industry for some decades. As one of the non-linear estimation methodologies, MIK has advantages related to resolving multiple or mixed populations, high variability data and strongly skewed distributions. Applying the MIK methodology requires a lot more effort when compared to other non-linear methodologies, for example localised uniform conditioning. This is due not only to the variogram modelling for multiple indicators, but the validation is also very important because the panel model is fundamental for follow-up work, including the generation of recoverable resources at the local or SMU scale. Apart from this, only a few reported case studies of MIK have documented post-processing of the estimated modelled distribution, representing the probability distribution at point scale at un-sampled locations. The MIK post processing should include the change of support from the point scale to the panel scale, and then the extraction of quantile values from the panel conditional cumulative distribution function (CCDF) for localisation of grades into the SMUs within each panel, based on a ranking estimate marking the SMUs from high to low. In this paper, we present a case study on a gold deposit with the MIK method with full-post processing implemented for recoverable resources. The MIK point estimate was carried out with an indirect lognormal change of support from point to panel scale, and localisation was done with a custom script. The localised uniform conditioning (LUC) method was also applied for comparison purposes. The comparison shows that MIK has advantages compared to LUC when comes to capturing the high-grades, especially when mixed or varying anisotropy is present within the mineralisation.

May 24, 2023

By M G. Hawtin

The Rocklands copper project is a multilode, iron oxide copper gold (IOCG) + cobalt mineralised system located in the Eastern Fold Belt of the Mt Isa Inlier. Rocklands orebodies cover a range of oxidation zones from oxide, to supergene and primary. Each zone contains different economic minerals of interest. The supergene zones contain significant amounts of native copper and the primary zones are dominated by chalcopyrite. The juxtaposition of these oxidation zones and minerals make it an interesting mineralisation system.Current mine production sampling collects a nominal 3 kg drill chip sample from a 1 m composite, RC drilled interval. A site specific sampling procedure was needed to quantify introduced sampling error when taking grade control samples. Due to oxidation and mineralogical variation in ore zones we needed to develop a practically achievable sampling methodology that ensures minimum sample mass and sample error requirements are achieved to ensure ‘representative’ samples for all ore types.These issues are planned to be resolved using an experimentally derived method using principles from the Theory of Sampling. This method uses an experimental calibration of parameters K and a for Gy’s fundamental sampling error formula using a modified 32-piece sampling tree experiment to compile sampling nomograms for the primary and supergene ores. This paper demonstrates the process undertaken to improve the quality and standard of existing mine production sampling procedures at the Rocklands operation.Results indicate a sample mass of 5 kg for RC drill chips is appropriate for both the primary and supergene ores to achieve a fundamental error below 0.01 or 10 per cent relative error, which is slightly higher than the existing sampling protocol of 3 kg. An additional experiment is recommended to compile sampling nomograms using the exact laboratory comminution and mass reduction stage information to assess the use of a 3 kg sample. The results also indicate no changes are required to existing sampling protocols when sampling RC drill chips in primary and supergene ore at Rocklands.Sampling nomogram results also provide a useful ‘rule of thumb’ reference guide to other mining and exploration companies to help understand minimum sample mass requirements and sampling error during exploration drilling, resource evaluation and mining production stages when targeting similar IOCG mineralised systems. A sample mass of 5 kg is recommended when RC drilling similarly IOCG mineralised prospects and deposits in the Cloncurry area. Future test work is recommended when additional open cuts become active as well as including resource drilling drill core to provide better three-dimensional sample representivity.CITATION:Hawtin, M G, 2017. Minimum sample mass from reverse circulation grade control drilling at Rocklands copper project, in Proceedings Tenth International Mining Geology Conference 2017, pp 337–346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By A Parry, C Fitzmaurice

After conducting laboratory ore sorting testwork on samples of a low grade nickel ore stockpile at Western Areas’ Flying Fox nickel mine, a mobile crushing, screening and ore sorting plant was located adjacent to the stockpile. An initial two month trial of the ore sorter program proved successful and was extended to process the entire Flying Fox low grade stockpile in a further four month campaign. A total of 167 660 t of low grade ore was processed, providing highly upgraded feed trucked 26 km to the Cosmic Boy concentrator. A more than three-fold grade increase was achieved on ore sorter accepts. The moderately upgraded fines that by-passed the mobile ore sorter were also subsequently blended into plant feed. This paper describes the mineralogy of the Flying Fox low grade ore, the mobile ore sorting campaign and provides some commentary on the economic and environmental benefits achieved in the ore sorting campaign. The ore sorting campaign demonstrated the benefits of being able to utilise mobile ore sorting equipment temporarily located adjacent to sub-economic low grade stockpiles in order to effectively treat these stockpiles and produce viable plant feed.CITATION:Parry, A and Fitzmaurice, C, 2018. The upgrading of low-grade nickel ore stockpiles at Western Areas Ltd Forrestania operations, using a mobile ore sorting plant, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 541–550 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

In most surface mining operations, overall project economics is driven to a significant extent by the slope angles that can be achieved within the rock masses present. This is particularly true of precious metal pits in which stripping ratios can be relatively high, although examples from other non-precious metal operations (such as large iron ore and copper pits) can also be found. As a consequence, it is not surprising that in most large (deep) open pit mines, relatively small changes in slope angle (of the order of two or three degrees can translate into changes in project value measured in the tens or even hundreds of millions of dollars. Understanding how this potential value can be realised, and quantifying the associated risks, should be one of the key outcomes of modern slope engineering practice. In striving for optimised slope angles, therefore, mining companies and their specialist consultants are increasingly turning to more sophisticated methods of engineering open pit walls. This paper summarises contemporary slope engineering practice as well as some of the key technical issues that are either currently being researched or will need to be researched in the future. It is written in the context of the slope engineering process; namely, data collection and analysis, failure mode identification and stability assessment, slope design, slope formation, and slope (face) mapping and monitoring (the latter two activities being the primary on-going data collection functions that close the design loop).

Jan 1, 2002

By A F. von Wielligh, M Scott, L Keeney

Operational Grade Engineering (GE) is the early (pre-processing) discard of low-grade mineralised and/or barren rock to improve the ore grade and/or reduce deleterious elements within the run of mine ore to be processed. GE activities generally have an impact on primary and ancillary mining activities, equipment utilization and overall equipment productivity. By discarding material which would have reported as ore (in a non-GE mine plan) means that GE must increases the total ore and total rock mining rate requirements to sustain mill feed targets. One challenge of GE and the planning of GE activities is that there are several indirect parameters which impact operational productivity. Modelling these potential impacts and determining if they can be overcome with alternate mine sequences, equipment application or possibly a different equipment fleet altogether is a key question requiring investigation. Overcoming these potential productivity obstacles associated with a more complex operation by introducing new operational parameters and destinations for ore and possibly sub-grade blocks, requires a GE mine plan that is coupled with detailed equipment productivity metrics and a sound operational plan incorporating all GE infrastructure requirements. Several GE mine plans and equipment productivity models indicate that mining rates generally need to increase by approximately 5% to 15% to sustain mill targets and often negatively impact equipment unit productivity metrices through increased cycle times, additional queuing and destination changes. These changes to productivity metrics are however offset by step change increases in asset value. This paper details a methodology to develop GE mine plans that incorporate equipment modelling, flexible mine sequencing and equipment-based production scheduling. In addition, the paper will outline impacts of GE planning on equipment unit productivities through worked examples and models.

Nov 10, 2020

By P Wahyono, H Vega, S Riza, P Vergara, P Gonzalez-Carbonell

PT Freeport Indonesia (PTFI), operating in the Ertsberg Mining District in the Province of Papua, is developing the Grasberg Block Cave copper-gold mine. The site aims to output 160 000 t/d and will be located underneath the current Grasberg Open Pit. Initial studies of the potential to develop a block cave mine in the Grasberg orebody have revealed that the mine will require significant volumes of air. The Grasberg Block Cave (GBC) project requires four primary fans (3750 kW each) to support production at full capacity.Fan #1 commissioning was accomplished successfully on 9 February 2012. However, Fan #2 chamber, which is separated by a 20 m pillar, had not been completed. The main challenge was Fan #2 chamber still needed to be benched. The risk of damage to the critical infrastructure in Fan #1 chamber, including ground support, cracks in pedestals, and misalignment in the impeller shaft were considered. The challenges were blasting the bench without damaging the surrounding infrastructure, completing the work safely and meeting the schedule. This was achieved with the engineering control methodology. This paper summarises the benching process of Fan #2 chamber and its impact upon Fan #1.CITATION:Vega, H, Riza, S, Gonzalez-Carbonell, P, Wahyono, P and Vergara, P, 2013. Excavating an underground primary fan chamber that is adjacent to a fully operational primary fan in PT Freeport Indonesia's Grasberg Block Cave Mine, in Proceedings The Australian Mine Ventilation Conference , pp 115-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By P Jonsén, S Larsson, M Parian, B I. Pålsson

The question of effective energy utilisation in grinding mills is not new. There are several conflicting arguments about tumbling mills, whether the efficiency is around 1 per cent or maybe 10 per cent, or even much lower. The energy not used is assumed to be lost as heating of the pulp, the grinding mill body, the charge, generation of shock waves and vibrations, etc. Stirred media mills on the other hand are generally considered to have better energy utilisation, but their energy efficiency is still not that clear. To shed some light on this a pilot-scale, wet stirred media mill was investigated over a range of operating conditions. The wet stirred media mill is a Drais PMH 5 TEX pearl mill fitted with an electric motor at 11 kW. It has been investigated over a range of operating conditions to try to balance the dissemination of the input energy in forms of the net grinding energy, mechanical energy losses, and the heating transferred to the pulp, the mill, the charge, and the cooling water. It is found that approximately 20–40 per cent of the input energy accounts for the grinding process. Also, that the difference between gross and net input electrical energy is mainly disseminated as heating of the pulp and cooling water. Mechanical energy losses appear to be much smaller than the heating effects. The use of a dispersant seems to mainly influence the heating effect.

Aug 24, 2022

By K J. Riihioja, E Nozawa

SmartTag is a radio frequency identification (RFID) based technology designed to allow tracking of ore from its source through blasting, run-of-mine (ROM) pads, crushers, intermediate stockpiles and finally into the concentrator. This paper presents current developments and the future direction of the SmartTagÖ ore tracking system, as well as presenting some case studies. Successful applications of the SmartTag system have encouraged development to allow the system to be used in a wider variety of plants, in particular plants with finer crushing and screening stages. This presented Metso with a number of technological challenges, including RFID tag and antenna design. By reducing the traditional RFID tag diameter from 60 mm to 20 mm the RFID tags can now successfully pass through a secondary crusher. The new smaller RFID tags (referred to as mini RFID tags) have been used in some Process Integration and Optimisation projects with very promising results. The results indicate that the miniature RFID tags have a higher survivability to blasting and through secondary crushing stages. Extending ore tracking further through the process allows more reliable linking of spatial data with time based process performance. Metso is looking at developing even smaller micro RFID tags, and is also investigating other applications for the SmartTag system, including ore tracking from the original source to the final destination (ie from the mine, through the plant and ports to the customer).

Sep 26, 2011

Past arguments advocating reverse circulation sampling against blasthole sampling are reviewed to present the debate under a different light. The advantages and disadvantages of each drilling method are compared, and the choice is presented as an informed trade-off between them.

Mar 1, 2010

Waihi Gold Mining Company Limited, a wholly owned subsidiary of Normandy Mining Limited, operates the Martha gold mine, located in the township of Waihi, New Zealand. The operation, an unincorporated joint venture, comprises Normandy Mining Limited (67.070/0) and Otter Gold Mines (32.94%). Since gold was first discovered at Waihi in 1878, it has formed a key part of the region's economy. In 1909 the Waihi mine was described in a report to Parliament as æthe most important gold mine in Australasia and one of the greatest in the world.Æ That was a record year for production, with 416,813 tons of ore mined and some 1,120 men employed. Today the mine produces up to 1,250,000 tonnes of ore annually, and the project employs some 234 men and women. In 1999 the value of the gold and silver produced ($59 million) made up 47% of Waihi's estimated GDP. Waihi Gold has made significant contributions to the Waihi economy, community and the Hauraki region as a whole. Since the mine was re-opened in 1987, thousands of local people have benefited from the mine. In 1999, consents were granted allowing an extension to the mine life (the Extended Project) and this will result in a further seven years of economic benefits resulting from mining activity. The Company has undertaken extensive consultation throughout project planning, construction, operations and rehabilitation. Ongoing liaison and involvement with all community sectors, including Tangata Whenua and Iwi, local residents, recreational groups and schools remains an integral part of the operation. Throughout the life of the modern Martha Mine, the Company has actively supported the local community in the form of donations, sponsorships, the provision of amenities, and by participating in community events. A well established environmental team exists at the site. Environmental and community performance is measured by an independent five-assessment process, and the Company is committed to achieving excellence through ongoing improvement programmes and staff awareness. When the mine is closed, the open pit area will be transformed into a recreational lake, and the tailings storage facilities will be rehabilitated to become a combination of wetlands, grassed areas and ponds. Resources will be provided by the Mine to ensure the rehabilitated site remains in a safe and self-sustaining, stable condition in perpetuity. The mine is regarded as a showcase on a world standard of how a modem mining operation can successfully coexist with the nearby community.

Jan 1, 2000

Production sharing and cost apportionment in joint ventures is commonplace in Australasia today and elsewhere. It is a recognised convention that, with the exception of a free carry situation, joint venture participants usually share the proceeds of the joint venture in direct proportion to their respective participating interest, after having first paid its respective cash calls, in advance, to cover the projectÆs ongoing operating and capital cost requirements.In surface mines, the parties simply pay their way and take their proceeds in this manner. In underground mines, the situation is no different, though treatment of capital, depreciation and tax may differ between the parties. A common feature in many cases is the creation of a joint venture entity to conduct the business. This entity then collects cash from the parties, banks it, employs the staff, runs the operation, provides reports and pays out the proceeds. This convention appears to be relatively simple in application. In practice, it has been known to be complicated in the situation where the participants take their product at the mine gate and undertake their own marketing and selling arrangements. A more complex situation presents itself where the joint venture tenement boundary with an unrelated third party straddles an economic deposit. In this scenario, both the joint venture parties and the third party may wish to mine the deposit, sharing some infrastructure and costs, yet taking their own product as it is produced. A case study outlining such a situation is presented in the paper, outlining firstly how the major cost categories were identified and treated for cost apportionment purposes. Secondly, a mechanism for the equitable apportionment of product is suggested. Finally, issues such as timing and cost reporting are dealt with, together with a checklist of points which should be considered when a similar situation might arise in the future.

Jan 1, 2002

By S Long, D Carnovale, L Louwrens

The Mt Wright underground mine (MTW) is located near the town of Ravenswood in north Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited.The Mt Wright mine has gone through many stages, from the conception and implementation of the world first ‘sub-level shrinkage’ stoping (SLS) with continuous fill mining method in 2010, through to steady state production. These have been outlined in detail in papers presented by Mackay (2011) and Mackay, Long and Koen (2014) at previous Underground Operators Conferences.Since the last paper was presented, MTW has experienced significant change in two key areas.The first significant change was the discovery of a previously unknown hazard in the form of flat rilling events (FREs) from closed drawpoints (DPs). These events are believed to be unique to MTW and pose a significant risk to both the safety of personnel and the business as a whole. The paper will discuss this hazard and the evolution of the controls and practices that have been introduced to mitigate the risk posed by the identified hazards. The material involved in these events is extremely dry, fine and hot.The second significant change is an altered stress regime bought on in part by a change in the production front orientation and a general deterioration in ground conditions in some areas of the mine. This has caused some production interruptions at MTW. The second half of the paper will describe the challenges encountered, the mechanisms behind these challenges and the strategies implemented to safely return MTW production to planned levels.It is believed that other operations can learn from the issues mentioned above, and the paper has been written with this in mind.`CITATION:Long, S, Carnovale, D and Louwrens, L, 2017. Mt Wright – managing unique risks, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 295–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By R Berry, J Lett, C L. Harraden

"In the past decade, increased processing capacity combined with precision robotics in high resolution spectrometers has resulted in a new generation of high-speed hyperspectral core logging systems. The application of these multisensor automated platforms provides a key advancement in the characterisation of metal resources. The development of this technology has allowed for comprehensive, drill core-based, mine-scale rock mass characterisation studies. Here we propose a new method for the extraction of parameters that seek to more accurately quantify ground conditions, including quantified rock mass rating (RMR) and the Rock Tunnelling Quality (Q) Index. Data inputs include rock quality designation (RQD), number of joint sets, joint roughness, joint alteration and joint spacing. Geologists and geotechnical engineers have historically collected these inputs by manually logging drill core. With automated core scanning technologies, these parameters can be estimated from the acquired image data and used to objectively calculate RMR and Q-index values for oriented core.Corescan is an automated hyperspectral core scanner that uses a 3D laser profiling system to measure the height of the surface of drill core. This technology allows for rapid core analysis to produce detailed fracture and rock condition data. Through an integrated geometallurgical approach, the proposed methodology will test the accuracy of joint measurement using the height profile Corescan data from oriented drill core. This will be combined with joint roughness and alteration mineralogy measured from the hyperspectral images to calculate the RMR and the Q-index continuously downhole. The values obtained can then be compared to the traditional, manual geotechnical log data. If the precision is sufficient, these techniques can then be applied site-wide to automate the collection and modelling of key ground condition classification indices across an entire deposit. Compared to the laborious manual geotechnical logging procedures that currently form the industry standard, utilisation of core laser profile data and high resolution red-green-blue (RGB) images provide an opportunity to collect large volumes of consistent geotechnical data, which can increase the efficiency and accuracy of deposit scale geotechnical models.CITATION:Harraden, C L, Berry, R and Lett, J, 2016. Proposed Methodology for Utilising Automated Core Logging Technology to Extract Geotechnical Index Parameters, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 119–124 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By J F. C L Costa, J C. Koppe, C Diedrich

Currently mineral resources evaluation is firstly expressed in terms of volume. Next the resources are transformed into tonnes by using an average bulk density applied to the whole deposit or, in some other circumstances, various different densities to distinct geological domains. Previous work in uranium, copper and nickel deposits used linear correlation between grades and bulk density to derive the density. Geophysics methods are also another good way to obtain density indirectly.These approaches do not take into account that two samples with the same grade but with different bulk densities can characterise different sample supports, leading to severe bias in grade and tonne estimates. It is important that the systematic measurements of bulk density are included into the estimation process, particularly when density is not correlated with the grades. Additionally, the extra time and costs involved in obtaining the bulk density data have made the mining industry disregard it.This study reports the impact in resource estimates by using a methodology that includes the bulk density variability. It involves the determination of a variability model for the bulk density and another model for the composite that was weighted by density as well as by its length. Next, these variables are estimated by kriging and the final grade estimates are obtained. The tonnages are obtained with the bulk density estimates. The conventional methodology was also applied and both estimates are compared to the reconciliation data from a major copper deposit. The results show a significant difference between the tonnage and grade estimates obtained from these two methodologies.The results show that considering density variability when compositing leads to a more accurate methodology resulting in better grade and tonnage estimates locally and globally.

Sep 26, 2011

By H Weitz

Bateman Engineering provided process technology and engineering design to China Yunnan Metallurgical Company (CYMCO) for a 30 MW DC furnace for the production of high-grade titanium dioxide slag.Following the successful commissioning of the furnace during the latter part of 2009 and the first quarter of 2010, a period of adverse circumstances resulted in having to operate the furnace without feed and at a low power input for a period of time. When normal feed resumed, a layer of solid material was detected on the slag-iron interface during sounding measurements. The condition of the iron was also significantly altered. The iron temperature was much higher than the design value, but the carbon content had decreased to such an extent that a large amount of iron solidified in the furnace, which made iron tapping very challenging. The slag temperature was increased in order to melt the solidified iron. However, severe sidewall damage resulted, which finally led to a burn-through. A number of samples were taken from the slag that remained in the furnace. These samples were analysed to determine the chemistry and phase profile throughout the slag bath. The mechanisms of formation of the high melting-temperature phase on the slag-iron interface are discussed, as well as procedures that can be applied to prevent a recurrence of this phenomenon. Some recommendations are made for instances when furnace feeding is interrupted for an indeterminate period.

Oct 5, 2011