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Efficient project planning during the detailed feasibility to final engineering stages of a project requires not only the accurate prediction of the grade, tonnes and recovery, but their degree of variability as well. An understanding of the major parameters involved in the grade and tonnage estimates is essential, and the communication to those receiving the results is most important. The personnel involved in the project require more than just a global reserves classification. Quality parameters other than grade should be evaluated as carefully as the estimate itself. This paper does not present any novel ideas to overcome or enhance any of this. Rather, it takes a step back and tries to look at the global picture of requirements for proper project planning.

Jan 1, 1987

By Misra A

After review of the status of research on optirnisation of retreat longwall faces it is argued that an acceptable optimisation model must be based upon realistic cost data that take into account not only the face costs, but the total panel costs. These include the cost of development, face cost, removal and installation cost. The determined optimum length of a retreat longwall face is based upon a realistic model and actual costs.Parameters that influence the optimum face length have been varied over wide limits to allow determination of the sensitivity of the model and the effect of the parameters on the optimum face length. It is concluded that for medium production rates and medium system availability, the optimum face length of a retreat longwall face under Australian conditions lies between 180 and 220 metres.

Jan 1, 1995

By S Maritsa, E K. Chiwandika, S M. Masuka

The iron and steel industry is experiencing an increase in the use of iron and steel commodities within societies, decarbonisation pressures, depletion of high iron ore grades and high energy consumption. This necessitates scrap metal recycling, low-grade ore utilisation using the induction or electric arc furnace to achieve the global target of net zero CO2 emission. The available highquality scrap metal cannot sustain the steel industry but the world has unused hematite-goethite ores. It is the aim of this research that this resource be utilised using the induction furnace to sustain the steel industry in an environmentally friendly manner. Indurated pellets prepared from the hematite-goethite ore, 5 wt per cent limestone and 5 wt per cent coal addition were smelted in the induction furnace at 1350 ± 50°C with 25 mins holding time. The effects of basicity and carbon content were also investigated to optimise the smelting parameters. The results showed that the careful control of the basicity, and iron-to-carbon ratio maximised total metal recovery. The optimal basicity ratio was determined to be 1.3 and a carbon to iron ratio of 1.4 achieved a total metal recovery of 73 per cent. The metal recovery was closely related to the estimated slag melting temperature. The basicity ratio of 1.3 achieved the lowest slag melting temperature estimated to be around 1380°C based on the CaO-SiO2-Al2O3 phase diagram. The recovered metal had a comparable chemical composition and microstructure to that products from an ITmk3 furnace.

Jun 19, 2024

The excavation of a tunnel through rock and mixed ground of basalt and silty clays presents a challenge to engineering organisations. Such was the situation facing the Melbourne and Metropolitan Board of Works (MMBW) in constructing the 15.3 km, 5.5m dia. tunnel component of the new Western Trunk Sewerage System. The tunnel geology showed that there were two distinct components to the excavation - rock and mixed ground. By drawing on extensive experience in the use of Tunnel Boring Machines (TBM's) used previously by the MMBW and using techniques developed for predicting TBM per- formance, a comparison of the options of drill and blast versus TBM was made. The conclusion was that TBM methods would provide the best solution to the problem. Tenders were called for the supply of a TBM. A performance specification was used to attract tenders offering designs which re- flected the state of the art on an internation- al level. Particular features required by the MMBW were included in the specification. The excavation planning and operation are described in this paper. The production achieved has shown that the TBM can very adequately handle rock excavation (best weekly production 167.9m). Extreme conditions of mixed ground with heavy groundwater inflows have been handled using an auxiliary thrust system to maintain gripper reaction through the soft ground encountered.

Jan 1, 1987

By D M. Verster, P L. Gillot, A Kone

Randgold ResourcesÆ MorilaÆs gold leach plant is subjected to uncommon æoxygen stressesÆ. Feed ores exhibit very high oxygen demands, primarily caused by iron sulfides. In addition, ore oxygen demand varies significantly over time, as well as between different feed ore sources. The inability of the Morila gold leach plantÆs oxygenation system to cope with these high and fluctuating oxygen stresses manifested itself in variable gold residue grades, and cyanide consumption rates.Management launched a Morila oxygen system review project during September 2009, with the objective of auditing the performance of the then current oxygenation system, against required performance parameters as calculated from oxygen demands of the various feed ore types and targeted dissolved oxygen levels in the leach train.This paper describes the systematic changes made since 2009 to the Morila oxygen system in four main areas: O2-supply plant, O2-volumes, O2-controls and oxygenation equipment. Data are provided on corresponding improvements in leach plant performance. Theoretical, as well as practical aspects of gold leach oxygenation systems are covered.CITATION:Verster, D M, Gillot, P L and Kone, A, 2013. Oxygenation system upgrades and leach plant performance improvements at Morila Gold Mine - 2009 to 2012, in Proceedings World Gold 2013 , pp 215-224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

Over a century ago the first ship designed solely for carrying a bulk cargo was launched. This vessel, the "John Bowes", with a deadweight of 660 tonnes was a single decked ship with machinery and accommodation aft. As such she was undoubtedly the fore- runner of the bulk carrier of today only some two hundred and fifty times smaller. Whilst the "John Bowes" pioneered the present accepted mode of transporting the bulk com- modities of the world, it is unlikely that her cargo was either loaded or discharged as quickly as that of a 150, 000 tonner of today. Two decades ago the bulk carrier was beginning to feature in the bulk handling ports of the world. Cargoes of iron ore previously carried in the 'tween deck vessels of the Empire type and Second World War Liberty ships began to be poured into the unrestricted open holds of bulk or ore carriers. The size of vessels catering for this relatively new innovation has rapidly grown to pass the 150, 000 deadweight tonne mark, but only in the last few years. The growth from now into the future is not simply one of ship size evolution. Neither is it a function of the depth of water available at ports. It is in fact a function of a number of features such as ports, loading and unloading facilities, ship trading characteristics, length of voyage and total economies of the transport task from supplier to destination.

Jan 1, 1973

With commodities suffering dramatically low real prices, mining business margins are under intense scrutiny. Unfortunately, management systems developed early this century for manufacturing are driving counterproductive behaviours that choke productivity. The paper and presentation will explain this and present a proven methodology for increasing productivity. This will be supported by operational examples from Australian and American mining management to demonstrate the importance of modern business performance measurement and analysis systems. It will explain the importance of management systems in driving organisational change to sustain superior productivity and margins. The paper will explain why many executives and managers confuse production (a measure of volume) with productivity (which measures efficiency and effectiveness). It will explain how this and other counterproductive managerial and operator behaviours and attitudes are driven by traditional business management systems exacerbated by managerial and consulting fads. The paper will begin with the simple principle that to improve results one needs to first improve the process producing the result û and will show how this is often violated. Improving productivity then boils down to:accurately identifying opportunities using sound, modern measurement, analysis and reporting systems; methodically improving operating and commercial processes, and changing peopleÆs behaviours and attitudes to sustain changes in practices. The paper will include fundamentals of applying sound measurement and analysis to:processes directly, eg cycle time charts and their impact in cyclical (non-continuous) operations commonly used in rock breakage; drivers of productivity; and process results themselves since correct analysis identifies opportunities accurately. The paper will cover the importance of practical leadership and the need to follow a simple, solid plan for changing systems that drive behaviour. Overall, it will highlight use of modern performance Measurement, Analysis and Reporting systems to drive behaviours and improve margins - without capital investment û and make executive and managerial work easier and more effective.

Jan 1, 1999

By K Evtiminova, G Jobson, M Nolte, S Meik

Chelopech Mining EAD (CMEAD) is a wholly owned subsidiary of Dundee Precious Metals Inc (DPM) and operates the Chelopech underground mine and processing facility located in Bulgaria. The final product sold is a flotation concentrate containing copper minerals with associated gold and silver. The increase in production from 0.6 to 1.0 Mt/a by 2009 occurred with the original (1975) secondary/tertiary crushing, and primary/secondary ball mill circuits. As part of the mine/mill upgrade project to 2.0 Mt/a, a new single stage semi-autogenous (SAG) mill and ancillary equipment was installed, replacing the original circuits, with commissioning occurring during the first half of 2011. Aspects of the design, commissioning and operation of the new comminution facility are the subjects of this paper.An extensive program of comminution characterisation test work was completed in 2004/2005, which indicated moderate hardness and competency characteristics. The characteristics were considered suitable for a range of comminution approaches which were assessed with respect to power requirements and capital and operating costs. Retention of the existing primary crushing facility, and installation of a new single stage SAG mill located within the existing mill building, was selected as the design for the expansion.An extended ramp-up schedule for the overall concentrator upgrade turned out to be necessary as the comminution and flotation circuits were completed prior to several downstream unit processes (concentrate filtration and tailings thickening), which were required to reach the design mill feed throughput rate on a sustainable basis. This resulted in the opportunity to gradually increase the SAG mill ball charge as necessary, to obtain the throughput corresponding to the various downstream processing constraints.A relatively fine cyclone overflow stream particle size distribution is a feature of the Chelopech comminution circuit that has not been fully overcome with increasing ball charge conditions. However, design throughput has been met even under the finer product size conditions and will be consistently achieved following the commissioning of two further process improvement projects scheduled for late 2012.CITATION:Jobson, G, Nolte, M, Evtiminova, K and Meik, S, 2012. The modernisation and upgrade of concentrator operations at the Chelopech Mine, Bulgaria - Design, installation and operation of the 250 tonnes per hour comminution circuit, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 325-332 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By A Trench, S Ulrich, S Hagemann

A synthesis of reported All-In Sustaining Costs (AISC) for 57 Australian gold mines in the period 2014–2016 reveals for the first time the clear influence of grade upon cost performance, most evident in gold-only underground mines. Past syntheses of costs on a single quarter basis have viewed grade as potentially subordinate to other factors such as production scale, mine geometry, mineralisation style and a combination of other mining-related costs. Better understanding of the grade to cost relationship on both an individual mine and whole-of-portfolio portfolio basis is needed. Insight into the roles and trade-offs between other cost-determining factors will aid the future sustainability of the gold mining sector in Australia and assist in targeting prospects for future resource growth and development. While the overall trend is toward higher-grade mines displaying lower costs and vice versa, the grade to cost functions appear radically different between mines based on time-series data. The median cost of Australian gold production in the final quarter of 2016 was A$1081/oz. The threshold for lowest cost quartile production was A$965/oz. Underground production now dominates Australian gold output – with 71 per cent of ounces originating from operations that are either entirely underground or hybrid pit/underground mines. Scale economies are evident, with smaller mines predominately among the higher cost producers. For mines of equal grade, open pit mines are lower cost than underground operations. Reserves are modest, with a median mine life for underground operations of 4.7 years based on current production rates. Reserve additions at mines are likely constrained not only by the finite nature of mineralisation at each mine but also by the geometrical difficulty of accessing suitable drilling locations to test for reserve extensions.CITATION:Ulrich, S, Trench, A and Hagemann, S, 2017. Towards an understanding of production costs at Australia’s underground gold mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 241–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By C M. Stewart

Lithium battery electric powered vehicles and machines (BEVs) continue to gain traction inunderground mining use, with predictions they will dominate the underground light and heavy vehicle fleets for some mines within the next decade. There are clear advantages for ventilation systems through reduced heat output and the elimination of harmful exhaust gases and diesel particulates. However, the risks and effects of BEV fire emergencies for underground personnel and ventilationsystems are still largely in the early stages of analysis and understanding. This paper conducts an industry review of a selection of lithium battery fire incidents and research.A research paper review on lihthium fire behaviour, intensity and toxicity will be analysed and comparisons made with equivalent diesel machinery fires for context. Guidelines for mine firemodelling parameters will be offered to assist in predicting the behaviour, heat and emissions from BEV fires, and recommendations and conclusions will be drawn on the specific hazards of lithium battery fires compared to conventional diesel powered machines.

Oct 12, 2022

By I Lumsdaine

QNI Pty Ltd operates the Yabulu Refinery located 25 kilometres north of Townsville, North Queensland. The plant treats nickel laterite ores sourced from the Philippines, Indonesia and New Caledonia. The cobalt head grade and overall recovery expectations for the 2001/2002 financial year are 0.161 per cent and 53.8 per cent respectively. Cobalt is a valuable byproduct derived from the nickel refining operation which utilises the Caron Process. Any increases in cobalt recovery that are achieved from the existing relatively low level provide significant improvements to the bottom line of the operation. Towards the end of 2000, a project was undertaken to characterise cobalt losses with the sole purpose of improving cobalt recoveries using a variety of analysis techniques. The Time-of- Flight Secondary Ion Mass Spectrometry (TOF-SIMS û University of South Australia) method was used to verify the presence of surface bearing cobalt species, originating from either co-precipitation or adsorption mechanisms. Cross-section examinations were also performed using Scanning Electron Micrscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDXS). These techniques indicated the presence of high cobalt concentrations (in the order of several per cent) within a select number of roasted and leached ore particles. The phenomenon of cobalt losses due to incomplete leaching within specific ore particles was not widely documented within the Refinery prior to these studies. In order to quantify losses via this mechanism, Mineral Liberation Analysis (MLA û JKTech Centre) was also performed on key samples. This paper serves to document a systematic approach in determining the source of significant valuable mineral losses in an established, operating plant. It discusses the use of a variety of analytical techniques, which have been adapted for the minerals processing industry, but are strongly relevant for plant investigations in the hydrometallurgical industry.

Jan 1, 2002

The nation of Fiji is located the South Pacific on the æRim of FireÆ some four hours flying time from the eastern sea board of Australia. It is a tourist destination situated on the main route from Australia to the Americas. Fiji is a developing country that has had a fewsetbacks but the country has able, happy people that are very resilient. Most importantly, the country is a safe destination for tourists and businesspeople as the local people are friendly, have good ethics, and most speak English. Fiji is a very willing nation, hungry for knowledge and advancement. The Fiji geological setting on the æRim of FireÆ, that runs from New Zealand across the Pacific through Fiji and on to Papua NewGuinea, has many large deposits of gold and copper. Fiji is an exciting destination for mineral explorers with discoveries of gold, silver, manganese, bauxite, iron and copper. Gold was first discovered in 1921 and the first two mines opened in 1935; one of which was Emperor Gold Mining Company (EGM) the other being Mt Kasi. EGM mines gold on the margin of the Tavua caldera, some 85 km north of the Nadi international airport. EGM has operated continuously for close to 70 years, producing approximately 6.9 million ounces of gold and has an underground reserve of 847 600 ounces with a total mineral resource of 12 335 600 tonnes at 10 g/t (as given in the Emperor Mines Limited Annual report 2003). The mineralisation in Fiji is very exciting and it is common to discover spectacular intersections and outcrops, which are typical for this type of epithermal narrow vein mineralisation, but be aware that the orebodies are variable and not easy to understand.

Jan 1, 2004

By J Samosir, L A. Snyman

Northparkes is located 27 km north of the township of Parkes in central New South Wales, Australia. The operations consist of underground block cave mines and an ore processing plant that produces high-grade copper and gold concentrate. Production is currently sourced from the E48 Lift 1 block cave mine and open cut stockpiles. Mining commenced at Northparkes in 1994 as an open cut operation. Underground block cave mining began in 1997. Northparkes was the first mine in Australia to use the highly efficient block cave mining method, which relies on gravity and natural rock stresses to fragment the ore.An issue affecting production in 2011 was the stability of the E48 mine. A small portion of the drives on the extraction level began to deteriorate as the ground support system failed. The problem was temporarily fixed by stopping production in three extraction drives and tight filling selected areas within these drives (and drawpoints) with low-strength concrete. This action provided immediate support and stability whilst allowing time to investigate potential ground support remedies. From these investigations it was decided to use resin injection technology and additional ground support to stabilise the rock in the aforementioned extraction drives as the concrete plug was excavated in a controlled advance and sequence. This made the area safe and ensured the ongoing safe operation of the E48 mine. The redevelopment of one of these drives began late in 2011, with the remainder being progressively redeveloped over the next two years in order to maintain the extraction level stability.This paper looks at the strategies employed to safely re-open previously converged drawpoints and associated extraction drives that were subject to high abutment loading that was possibly associated with premature cave breakthrough.CITATION:Samosir, J and Snyman, L A, 2014. Redevelopment at Northparkes following significant drive closure, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By K J. McDonald

All commercially available zircon sands contain radioactivity sourcing from the decay of trace amounts of contained uranium (U) and thorium (Th). The fine particle size zircons of the Horsham area in the Murray Basin region of Victoria, Australia, contain significantly more (about twice) Th+U than those commercial zircon sands. The marketability of these fine-grained zircon sands is likely to rely on the removal of these radioactive impurities. CSIRO Minerals have been working for some time to develop processes for the removal of the radioactive impurities from zircon. It is generally agreed that it is quite impossible to leach U and Th from zircon, however, the Heat and Leach (HL) process, described in detail in Aral and McDonald (1999), reduces the radionuclide levels significantly. The identified (HL) process aims to leach uranium and thorium selectively from a decomposed zircon. The novelty of the process is that a large part of the leached product can be reconstituted to a low radiation zircon by a subsequent heat treatment. The HL process uses a flux mixture of sodium carbonate and calcium borate to decompose the zircon at relatively low temperatures (900 to 1150¦C) and a weak acid (0.5M HNO3; 80¦C/0.5 h; pulp density ten per cent) to leach the radionuclides selectively. The process leaves the major components (ZrO2 and SiO2) behind with little loss. The HL process for example lowers the U+Th content of a Murray Basin zircon from 1000 ppm to 400 ppm U+Th. Among the radionuclides more U progeny is removed than the Th series radionuclides. This is very significant as the radioactivity of U series is 2.5 times more that from the Th series. Therefore the reduction in the radioactivity level of zircon is more than the reduction in Th+U indicated by XRF analysis. A schematic flow sheet of the HL process is shown in Figure 1. Although the HL process successfully lowers the radionuclide levels in zircon sands, the final product contains significant amounts of sodium (up to 14 per cent Na2O) and small amounts of CaO. By comparison, the sodium content of the commercial zircon sands is in general 2O. Zircon is used mainly as an opacifier in tile glazing where the addition of ten to 15 per cent zircon to a translucent base glaze gives the sanitary white colour to the tile surface. Opacification is the result of the refractoriness of zircon particles at the glaze firing temperatures that is generally around 1050¦C.

Jan 1, 2001

By S Whitton, W Wimmler, L Wimmler

“Given the increasing scrutiny of the mining industry and its relatively poor record with regards to mine tailings management, increased requirements to minimise water usage (often accompanied by very high costs of water) and the need to demonstrate achievable long-term closure strategies, it is likely that the option of a filtered tailings system will need to be considered in many operations in future.” (Australian Centre for Geomechanics, 2018). Given such a statement as a conference introduction, it is only appropriate that a range of potential technologies are investigated and compared, to create awareness for even underrated but appropriate technologies. The advantages and disadvantages of all technologies need to be considered and analysed. Suppliers are swift to promote their technologies advantages; however aspects of sustainability are not always fully understood. Perhaps a combination of two filtration technologies is appropriate. This paper delves into the technical details, good or bad, of four mechanical dewatering technologies in tailings dewatering and provides insight on an undervalued and, in the author’s opinion, young technology – the screw press.

Jul 1, 2021

The Rio Tinto Iron Ore group currently estimates grade attributes for mineral resources using ordinary kriging (OK). OK produces a smoothed globally unbiased estimate, but does not capture local variability, which can have significant impact on mine planning and scheduling. The dimensions and the multivariate nature of iron ore deposits make point simulations of whole deposits impractical. With a direct block simulation method the size and speed limitations of point simulations can potentially be overcome, resulting in a viable method for capturing local variability and for providing risk measures into the mine plan and schedules. Some iron ore deposits are highly folded (post mineralisation) and require preprocessing using an unfolding algorithm to properly define the continuity parameters and directions of anisotropy before simulation can proceed. Block co-simulation proceeds in unfolded space and since mine planning require a block-model with regular block-sizes; a regular block-model is unfolded first. This paper discusses a block co-simulation approach that can be used to simulate the irregular blocks resulting from the unfolding process. A section of an iron ore deposit is used for testing the block co-simulation algorithm and the simulation results are compared against the Isatis direct block simulation method. Available blasthole data is also used to validate the behaviour of the block co-simulation algorithm.

Sep 26, 2011

By Stevenson I, Dickinson W, Taylor R. N

Despite flash smelting's widespread use little is known about the actual processes taking place in flash furnace shafts and comparatively few reports of sampling campaigns have appeared in the published literature. his paper reviews the previous reports of the use of horizontal trough samplers and analyses their expected collection efficiency. In the light of the deficiencies revealed by this analysis an isokinetic sampler was produced and a vertical sampling technique was also developed to obtain samples from directly below the burners in the shaft of the flash furnace at the Kalgoorlie nickel smelter. Comparison of the sizing of the samples obtained with the horizontal trough and isokinetic samplers confirmed the theoretical analyses and showed that the trough samplers were not collecting the fine particles. Besides providing data to validate mathematical models of the burners and shaft, chemical analyses of the shaft samples showed that the coal in the charge was reacting preferentially and that the plume of at least one of the burners was being deflected from its axial position. In the region directly below the burner there was evidence that the disperser on the burner was imparting more momentum to the coarser particles and that these were concentrating in the outer regions of the particle plumes issuing from the burners.

Jan 1, 1992

By Read T. A

THE Broken Hill South Ltd. is one of ten companies operating on the Broken Hill lode (See Fig. 1). It has two leases-Blocks 7 and 8-of a total length of 2250 ft. on strike of lode.From the surface to 425-ft. level the ore was found principally in the form of carbonates and high-grade friable sulphides. Below the 425-ft. level the ore is found in the form of compact sulphides. The ore-bodies found in the South mine may be broadly divided into two classes...

Jan 1, 1921

By M Hernan

Bendigo Mining Limited has established a modern underground gold mine and processing plant at Bendigo in central Victoria. The Bendigo goldfield produced around 22 000 000 oz of gold between 1851 and 1954. Approximately 4 000 000 oz were sourced from surface alluvial workings with the remaining 18 000 000 oz won from underground quartz reefs. The modern mine is accessed via the Swan Decline, which commences at the Kangaroo Flat site on the southern outskirts of Bendigo and progresses in a north easterly direction between the Deborah and Sheepshead anticlines, reaching a depth of almost 1000 m below the City of Bendigo. Development of this decline commenced in 1998. Since that time 20 km of underground development has been completed. Exploration drilling, on-reef development and bulk sampling carried out between 1999 and 2005 resulted in the estimation of a Probable Ore Reserve of 700 000 tonnes at 9.0 g/t gold for 207 000 oz of gold. These Ore Reserves were contained within four reefs located on the Deborah and Sheepshead anticlines. Reef mining commenced in late 2005 from the Shywolup and Greater Garrard reefs. Material mined was stockpiled on the surface in preparation for commissioning of the process plant which commenced in mid 2006. Mining and processing were carried out between August 2006 and May 2007 during which time 176 000 tonnes were processed at an average grade of 5.4 g/t gold to produce 26 735 oz of gold. Plant feed was sourced from four reefs. This paper discusses some of the issues which were encountered with the definition and mining of these geologically variable and nuggetty reefs. This paper covers exploration techniques, grade estimation, mine geological control, mining methods, geotechnical issues and reconciliations. It will also discuss some of the lessons learnt and how these will be applied to future Mineral Resource and Ore Reserve estimation, as well as underground operations.

Jan 1, 2008

The homologous series of saturated fatty acids investigated in this study generally show a steady gradation of properties with chain length. The solution pKa values were assumed constant at 4.9, however reported pKa values could be lower or higher. Hematite flotation response and surface pressure for aqueous solutions of these fatty acids were measured as a function of pH. For the shorter chain fatty acids, the undissociated acid was shown to be the predominant surface active species with flotation, supplemented by the physical adsorption of acid anions as the chain length increased. The reduced solubility of the longer fatty acid carbon chains made these reagents ineffective as flotation agents. The maximum flotation response of hematite using tetradecanoic acid corresponded with the precipitation edge of the reagent. The results show that the values of surface pressure of the surfactants are not always a good indication of their effectiveness as flotation collectors.

Jan 1, 2005